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Knee Injuries: Acute and Overuse

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Ovid: Manual of Orthopaedics

Editors: Swiontkowski, Marc F.; Stovitz, Steven D.
Title: Manual of Orthopaedics, 6th Edition
> Table of Contents > 24 – Knee Injuries: Acute and Overuse

24
Knee Injuries: Acute and Overuse
I. Foundation of Injury Diagnosis
Knee injuries are common in active individuals. Both
acute and overuse injuries occur, and they require different
investigative processes to diagnose and treat them properly.
  • Subdivision of clinical categories
    • Acute injury is an injury that happens
      where a single application of force creates the musculoskeletal damage.
      This is common in athletics, motor vehicle trauma, etc.
    • Acute or chronic injury is an injury that
      results in a disabled state that can be quiescent over time and result
      in a new injury episode at a later time. This new injury would
      represent an acute injury. However, this new injury did not depend on
      abnormal forces creating the injury but rather the fact that there was
      pre-existing damage to the musculoskeletal tissue. Common examples
      might be recurrent patella instability or recurrent shoulder
      subluxation.
    • Overuse injury is an injury that is
      characterized by the absence of an injury or at least no injury
      significant enough to explain the current clinical situation. This kind
      of injury results from repetitive submaximal or subclinical trauma that
      results in macro- or microscopic damage to a structural unit and/or its
      blood supply. This overuse pattern can be seen in all musculoskeletal
      tissue but is most common in bone (overuse pattern resulting in stress
      fracture), bursal tissues (overuse pattern resulting in bursitis), and
      tendon (overuse pattern resulting in tendonosis).
  • Clinical correlation. The clinical approach to a knee injury (acute/chronic/overuse) depends on four cornerstones:
    • History
    • Physical examination
    • Tests and their interpretations
    • Treatment
II. Approach to The Acutely Injured Knee
  • History
    • Mechanism of injury.
      This helps to identify potential structures that may have been damaged
      by the application of force, either direct (contact) or indirect
      (twisting mechanism). If the injury was a contact injury, one should
      look for external signs at the point of force application and what
      structures might have been injured as that force continues. For
      instance, a blow to the anterior tibia might create upper tibial
      bruising. This force creates a posterior displacement of the tibia on
      the femur, potentially injuring the posterior cruciate ligament.
      Non-contact injuries frequently involve rotatory twisting; the lower
      limb remains fixed as the upper body twists around the knee.
    • Was a pop heard or felt? A pop is frequently associated with tearing of a ligament, most commonly the anterior cruciate ligament, or a bone bruise.
    • Return to play.
      The degree of pain and/or disability cannot be used as a reliable
      indicator of the seriousness of an injury. However, continued play with
      little or no impairment in performance diminishes the likelihood of a
      serious knee injury.
    • Has the joint been previously injured?
      Frequently this question uncovers an acute on chronic injury. Two
      common examples are recurrent kneecap dislocation and recurrent
      subluxation after initial anterior cruciate ligament injury.

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    • Joint swelling.
      Knee joint swelling within 12 hours after an injury is, by definition,
      hemorrhage into the joint. An effusion that occurs after 12 hours
      suggests synovial fluid accumulation due to reactive synovitis, often
      due to cartilage or meniscus damage. (see 6.b below).
    • The differential diagnosis of an acute knee hemarthrosis (1) (what inside the knee can bleed?) is:
      • Ligament injury.
        The anterior cruciate ligament (ACL) and posterior cruciate ligament
        (PCL) are intraarticular/extra-synovial structures. The superficial
        medial collateral ligament (MCL) is an extraarticular structure.
        However, the deep MCL is a thickening of the joint capsule and is
        intraarticular. In a complete tearing of the MCL, both structures are
        torn. The lateral collateral ligament (LCL) is an extraarticular
        structure. It is rare that this ligament is torn in isolation. The most
        common ligament torn in acute hemarthrosis is the ACL (approximately
        70%) (2).
      • Peripheral meniscus tear.
        The outer, or peripheral, one third of the meniscus is vascular, and a
        tear in this region results in a hemarthrosis. Meniscus tears in this
        zone have the potential for healing and are repairable. Tears in the
        inner two thirds of the meniscus are more often associated with
        synovial irritation leading to a serous effusion that arises later
        (e.g., 24–48 hours) after the initial injury.
      • Fractures.
        Any fracture that involves the joint surface results in a joint
        hemarthrosis. In addition to obvious condylar/patellar fractures,
        occult osteochondral fractures can be a source of hemarthrosis. These
        can include avulsion fractures of the PCL and ACL (more common in
        developing adolescents) and fractures secondary to patella dislocation.
      • Synovial/capsular tears.
        Patella dislocations, even in the absence of fractures, are a source of
        hemarthrosis as the medial patellofemoral ligament and medial
        retinacular restraints are torn. Also, a significant contusion without
        a frank fracture or ligament/meniscus injury can create synovial
        bleeding. This is often considered a diagnosis of exclusion.
  • Physical Examination
    • Inspection
      • Swelling. The
        absence of notable intraarticular swelling does not signify a less
        severe injury. Severe ligament disruptions are associated with large
        capsular disruptions, and fluid typically escapes into the surrounding
        tissue. The absence of knee swelling may indicate an extraarticular
        source of pain.
      • Localized bruises and abrasions.
        These can be useful to identify the point of application of force in a
        contact injury. These can indicate the direction of the force, which
        helps to indicate what structures may be injured.
    • Palpation
      • Direct palpation
        of the injured area corresponds to the anatomic structure underneath
        that area. This is most useful for diagnosis when surface anatomy is
        directly correlated such as iliotibial band tendonosis and patella
        tendonosis. Direct palpation of meniscal, patellofemoral, and MCL
        structures can be useful in distinguishing a differential diagnosis.
        The cruciate ligaments do not have a palpable attachment to the
        capsule, and, therefore, direct palpation of these structures is not
        possible. However, injury to the ACL is associated with anterolateral
        subluxation of the tibia on the femur and, therefore, anterolateral
        joint line tenderness is common.
      • Patella subluxation/dislocation.
        This is associated with tenderness along the patella retinaculum,
        especially at the medial epicondyle where the medial patellofemoral
        ligament (MPFL) inserts and/or along the superior medial portion of the
        patella. Note that although the patella dislocates laterally, it is the
        medial based structures that are injured and thus are painful when
        palpated.
    • Range of motion.
      This is best assessed with the patient in the supine position. When the
      knee has an effusion, the knee’s resting position prefers approximately
      30 degrees of flexion (where potential capsular distention is largest).
      Full extension and full flexion should be compared to the opposite
      side, presuming

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      that
      side is normal. If the opposite side knee hyperextends, then an injured
      knee that goes just to zero would be considered lacking full extension.

      • A locked knee
        is defined as the inability to obtain full passive motion of the joint
        secondary to a mechanical block. This does not mean that the knee is in
        one position, but rather that there is an inability to obtain full
        motion. Common causes are a displaced meniscus tear or loose body.
      • A pseudo locked knee
        is defined as the inability to obtain full range of motion secondary to
        pain or intraarticular knee swelling. A torn meniscus without
        displacement can result in pain at the limits of flexion and/or
        extension. If the patient’s knee “locks” in full extension and doesn’t
        want to bend, the most common reason is an injury to the extensor
        mechanism, resulting in pain when the patient attempts to engage the
        kneecap in the trochlear groove.
      • Active range of motion
        assesses the integrity of the motor units surrounding a joint. Even in
        a severely injured knee, the patient typically retains the ability to
        lift his or her leg. Therefore, active straight leg raising and range
        of motion should be assessed. Frequently missed acute knee injuries are
        disruptions of the extensor mechanism, which include quadriceps tendon
        and patella tendon injuries. In this instance, the patient will
        generally be incapable of a straight leg raise.
    • Stability testing. The sine qua non of a ligament disruption is the presence of pathologic joint motion.
      • Straight plain instabilities
        are the easiest instabilities to test on a knee. This represents the
        ability to move the tibia away from the femur in four known planes.
        • Medial instability is associated with injury to medial or tibial collateral ligament
        • Lateral instability is associated with injury to lateral or fibular collateral ligament
        • Anterior instability is associated with injury to ACL
        • Posterior instability is associated with injury to PCL
      • Rotary instabilities. This refers to the rotation of the tibia around its vertical or longitudinal axis (Fig. 24-1).
        • Anterolateral instability is associated with ACL injury
        • Posterolateral instability
          is associated with structures of the posterolateral corner of the knee
          (LCL, popliteal fibular ligament, popliteus tendon). These are
          frequently associated with PCL and/or ACL injuries.
        • Posteromedial injuries. These injuries are rare and are commonly associated with PCL injury with or without MCL injury.
        • Anteromedial injuries are associated with ACL/MCL injuries
      • Extensor mechanism instability
        • Apprehension sign.
          Passive lateral movement of the patella causing pain and/or quadriceps
          contraction is suggestive of patellofemoral subluxation/dislocation.
          This maneuver is typically done with the leg in full extension,
          quadriceps muscles relaxed.
        • Straight leg-raising against gravity
          confirms integrity of the extensor mechanism, including quadriceps
          tendon, patella, and patella tendon. A “lag” sign represents the
          difference between passive and active extension of the knee. A lag
          signifies disruption and/or weakness of the extensor mechanism.
        • Medial/lateral patella restraints.
          Stability testing of the patellofemoral joint involves assessing the
          degree of passive patella motion in a medial and lateral direction of
          the patella. This is typically measured against an imaginary midline of
          the patella in the resting position (Fig. 24-2).
          This maneuver tests the static restraints of the medial and lateral
          extensor retinaculum complex. Any change from the patient’s “normal”
          measured

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          against
          their normal contralateral knee is suggestive of extensor mechanism
          disruption. Most particularly, an increase in lateral patella motion
          represents laxity or incompetence of the medial patella femoral
          ligament and medial retinacular structures associated with past or
          present patella dislocation.

          Figure 24-1.
          Rotatory instability of the knee. PCL, posterior cruciate ligament;
          POL, posterior oblique ligament; MCL, medial collateral ligament; ACL,
          anterior cruciate ligament; ITB, iliotibial band; LCL, lateral
          collateral ligament; PT, popliteal tendon. (From Arendt, EA. Assessment
          of the athlete with a painful knee. In: Griffin, LY, ed. Rehabilitation of the injured knee, 2nd ed. St. Louis, MO: Mosby, 1990, with permission.)
  • Tests and their interpretation
    • Plain radiographs
      • Anterior/posterior view.
        The primary utility of this view is to rule out diagnoses and assess
        overall tibiofemoral alignment. Standing views are preferred as they
        best assess tibial-femoral joint space. If pain/swelling limits full
        extension and/or full weight bearing, supine views are performed but
        provide less information.
      • Lateral view
        evaluates the caudad/cephalad position of the kneecap. Patella alta, or
        increase in the cephalad position of the kneecap, suggests a patella
        tendon injury, especially when the injured side’s kneecap is higher
        than the opposite side. Avulsion fractures, especially those of the
        PCL, are typically visualized along the posterior aspect of the tibia
        in this view.
      • Axial view
        evaluates the position of the patella in its relationship to the
        femoral trochlear groove. Oftentimes, osteochondral fragmentation
        following a patella dislocation can be visualized on this view.
        Typically, one would see fragmentation of the medial patella facet
        and/or lateral femoral condyle in an acute patella dislocation (Fig. 24-3). Different axial views have been established (Laurin’s, Merchant’s) (3).
        The clinician should become familiar with one technique. Axial views
        are a must for complete evaluation of all acute knee injuries.
        Figure 24-2.
        Demonstrates one quadrant medial “glide.” The patella is divided
        visually into four quadrants. Holding the patella between the
        examiner’s thumb and index finger, the limits of medial and lateral
        motion are assessed and recorded as “quadrants” of motion. (From
        Halbrecht JL, Jackson DW. Acute dislocation of the patella. In: Fox JM,
        Pizzo WD, eds. The patellofemoral joint. New York: McGraw-Hill, 1993, with permission.)

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      • Notch or tunnel view
        is most useful for evaluation of avulsion fractures of the tibia,
        osteochondritis dissecans, and loose bodies. This view is not standard
        for an acute knee injury.
    • Magnetic resonance imaging (MRI)
      for the knee. MRI has its largest application in evaluating meniscus
      and cruciate ligament injury. The overall accuracy is greater than 90% (4).
      An MRI is typically an adjunct test in the evaluation of an acutely
      injured knee. It should be performed only if it will alter the
      treatment protocol and is typically ordered by the physician who will
      be giving definitive treatment. It should never be used in the absence
      of a thorough and knowledgeable history and physical examination.

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      Posterolateral knee structures are not well visualized in the standard knee MRI views.

      Figure 24-3. Three types of fractures associated with patella dislocation. A: osteochondral fracture of the medial patella facet. B: osteochondral fracture of the lateral femoral condylar. C:
      Avulsion fragment of medial patella femoral ligament off medial
      epicondyle (osseous-nonarticular). (From Halbrecht JL, Jackson DW.
      Acute dislocation of the patella. In: Fox JM, Pizzo WD, eds. The patellofemoral joint. New York: McGraw-Hill, 1993, with permission.)
    • TcMDP bone
      scans are most useful in occult infections and to rule out stress
      fractures. Their usefulness in diagnosing reflex sympathetic dystrophy
      is variable. This is not a common diagnostic test ordered for acute
      knee injuries.
    • Computerized tomography (CT)
      has few specific applications for routine imaging of acute knee
      injuries. It continues to have utility for evaluating complex fractures
      around the knee, especially those involving articular surfaces. When
      used with contrast, it can be useful to evaluate the cartilage
      integrity of osteochondral defects such as osteochondritis dissecans.
    • Stress radiographs
      can be utilized to document ligamentous disruption of the knee but are
      infrequently performed. Stress radiographs can be useful to help
      evaluate the stability of a fracture through the growth plate,
      typically used within a surgical setting. Stress views of the knee are
      recommended to evaluate the degree of PCL laxity, most often used in
      the subacute or chronic setting.
  • General treatment
    • Joint aspiration
      is rarely used to help with evaluation of an acute knee injury. It is
      classically taught that fat dropules in a bloody aspirate helps to
      diagnose a fracture through bone. When a tense effusion is present, an
      aspiration can be therapeutic. Aspiration continues to be used when a
      non-traumatic effusion is present and to rule out infection,
      rheumatological diseases, especially crystalline deposit diseases such
      as gout and pseudogout, and rarely synovial based tumors such as
      pigmented villonodular synovitis. Aspirations for non-traumatic
      effusions are usually complex with blood workup including complete
      blood count (CBC) with differential, erythrocyte sedimentation rate
      (ESR), C-reative protein (CRP), rheumatoid factor (RF), flourescent
      antinucclear antibody test (FANA), and Lyme’s titer.
    • Immobilization/crutches.
      This is the safest way to protect an injured knee until a repeat
      examination or a definitive diagnosis and/or treatment can be initiated
      by the same or a referral physician. However, if no
      significant/unstable fracture is present, removal of the brace to
      perform gentle range-of-motion exercise is useful to help resolve an
      effusion. Partial weight bearing, depending on the patient’s comfort
      level and the working diagnosis can also be therapeutic and is
      encouraged. A knee immobilizer may be indicated for the acute knee
      injury when the patient’s knee is unstable or the pain is severe with
      passive flexion. It is crucial to advise re-evaluation within a few
      days as prolonged immobilization can precipitate atrophy and may turn a
      small, self-limiting injury into a chronic problem.
    • Reduction of swelling.
      Strategies to reduce swelling should be included in the initial
      treatment recommendation. These include ice, gentle passive or active
      assisted range of motion, elevation, and compression.
    • Repeat examination
      is helpful in establishing a more firm diagnosis, especially when pain,
      swelling, and/or apprehension limit the initial examination.
    • Antiinflammatory medication
      is commonly used to control pain. The efficacy in the reduction of an
      acute effusion or inflammation of injured tissues is debated.
      Antiinflammatory medications also change the role of platelet function
      and can theoretically increase bleeding of an injured site. It is
      recommended that this class of medications be used only for analgesic
      reasons and should be taken as a prn drug.
III. Specific Acute Knee Injuries
  • Fractures of the patella
    • Anatomic considerations.
      The patella is a sesamoid bone that is contained within the extensor
      mechanism. Its main function is to provide a lever arm for superior
      mechanical functioning of the extensor mechanism and to help stabilize
      the limb in deceleration. The strong quadriceps muscle complex is
      attached to its superior pole.
    • Common types of fractures
      • Transverse fractures, with or without comminution. These can be caused by direct or indirect trauma. They frequently are associated with disruption

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        of the extensor mechanism and need to be surgically stabilized in order
        to regain the mechanical function of the extensor mechanism.

      • Vertical fractures
        of the patella frequently are due to a direct injury; infrequently they
        represent an overuse injury of the patella. When they are associated
        with no or minimal displacement, they do not constitute a disruption of
        the extensor mechanism and can be treated conservatively.
      • Chip fractures
        of the medial border are commonly seen with a patella dislocation;
        infrequently, they can be associated with direct trauma. This variety
        will be more thoroughly discussed under patella dislocation.
    • Treatment
      • Undisplaced or minimally displaced fractures
        may be treated symptomatically without surgery. However, they must be
        protected from further damage. Immobilization in a knee immobilizer for
        2 to 4 weeks is sufficient, with weight bearing as tolerated.
        Quadriceps isometric exercises can be performed during this time.
        Gentle, passive range of motion as per the patient’s comfort level is
        recommended.
      • For displaced fractures
        involving the articular surface, an anatomic reduction is essential.
        Open reduction and internal fixation of the fragments with a tension
        band wire or lag screw is the treatment of choice (5).
      • Comminuted fractures
        require surgical treatment. A patellectomy is necessary if the entire
        patella cannot be internally fixed to gain stability. If more than half
        of the patella remains intact, then the comminuted pieces may be
        excised and the tendon sutured just above the subchondral bone into the
        remaining pole of the patella. Occasionally, fragments are large enough
        to fix with tension band wiring or 2.7-mm cortical lag screws (5).
      • If an osteochondral fracture
        is suspected, an arthroscopy to inspect the joint and remove small
        fragments of bone and cartilage may be of benefit. This is often the
        result of a patella dislocation and will be more thoroughly discussed
        below. At times, typically due to direct trauma, a large osteochondral
        fragment can be present. If the chondral fragment has an osseous layer,
        open or arthroscopic fixation should be attempted. This might be most
        readily accomplished by using bioabsorbable implants. Cartilage
        injuries are ominous for the future health of the joint; their
        treatment is beyond the scope of this text (6,7).
      • Postoperative treatment
        must be individualized according to the type of fracture and the
        security of the repair. Most knees are initially placed in a
        compressive dressing with a posterior splint or knee immobilizer. If
        rigid internal fixation is achieved and the patient is trustworthy,
        early protective passive range of motion is initiated, progressing to
        active motion. Typically, 6 weeks of some form of immobilization is
        necessary for healing of the fracture(s). Quadricep muscle strength
        within the limits of the allowed knee motion should be encouraged
        throughout this time.
      • The prognosis
        of patella fractures depends on the degree of articular damage and the
        ability to re-establish quadricep strength. Both are necessary for full
        recovery of the extensor mechanism complex. If articular damage is
        minimal, and good extensor mechanism strength can be restored, the
        prognosis of patella fractures is excellent.
  • Patella dislocations
    • Mechanism of injury.
      This injury can result from a direct blow but is more commonly
      associated with a non-contact twisting injury involving an externally
      rotated tibia combined with a forceful quadriceps contraction. The
      patella is dislocated laterally which disrupts the medial retinaculum.
      Spontaneous reduction frequently occurs when the patient instinctively
      tries to straighten his or her leg. When the patella relocates,
      osteochondral fragments can occur as the medial patella facet abuts the
      lateral femoral condyle. These two areas, in particular, should be
      scrutinized for osteochondral damage (see Fig. 24-3).

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      Medial patellar dislocations
      are rare in knees which have not had previous surgery. It is most often
      associated with iatrogenic causes, in particular a lateral retinacular
      release (8).
    • Physical examination.
      The patient will invariably have medial retinacular tenderness,
      especially at the medial femoral condylar region. If an attempt is made
      to displace the patella laterally, the patient resists this (patella
      apprehension test). A straight leg raising effort should be requested.
      The patient should be able to lift the leg, although he or she will
      report pain with this maneuver. This is frequently associated with
      minimal extension lag (the difference between passive and active
      extension).
    • Radiographs.
      An axial view is necessary for a complete evaluation of patellofemoral
      or extensor mechanism injury. If the patient is seen prior to
      spontaneous reduction of the patella, axial views will reveal the
      dislocated patella. Once reduced, the axial view may reveal any
      residual tilt and/or subluxation as well as the presence of
      osteochondral fragmentation. Axial views taken in lower degrees of
      flexion (Laurin’s 20-degree views or Merchant’s 30-degree views) will
      be more likely to show minor degrees of continued subluxation (9,10,11,12,13,14).
      • If the patella remains dislocated,
        then a reduction should be performed without delay to relieve pain.
        Achieve intravenous analgesia with morphine sulfate and a hypnotic
        before reduction is attempted. Once the patient’s muscles are relaxed,
        the knee is placed in full extension and the patella is reduced into
        place by a gentle, medially directed pressure. Slight elevation of the
        medial border of the patella during this maneuver is ideal. On occasion
        the kneecap can be “trapped” by the condyle, and reduction can be
        difficult. After appropriate prep of the skin, grabbing the kneecap
        with a large towel clip and using it to gently unlever the kneecap can
        be a useful maneuver for difficult reductions. Due to large hematomas
        frequently associated with patella dislocations, and the fact that
        there is a large retinacular tear medially, the use of local
        intraarticular injections is not favored. General or regional block
        anesthetic is rarely required.
      • If a large associated hemathrosis is present, aspiration is suggested as this can be therapeutic in relieving pain.
      • There is no consensus in surgical treatment
        for patella dislocations. There is universal agreement that, if it is
        associated with radiographic osteochondral fragmentation, an
        arthroscopy with irrigation and debridement or fracture repair is
        advisable. Whether surgical repair of the injured retinacular
        structures is necessary and/or whether it produces superior functional
        outcome is unclear (12).
      • When acute surgical repair is performed, it is directed at the medial retinacular structures, in particular the MPFL (12). Classically, this may also involve a lateral retinacular release and/or a medial transfer of the tibial tubercle (13), though these additional surgical procedures continue to be debated (13).
      • If there is no evidence of a fracture or continued radiographic subluxation/tilt, non-operative treatment
        can be elected. Non-surgical treatment is directed at providing an
        environment where the patella does not dislocate. Typically, the
        patient should be treated initially with crutches and a knee sleeve,
        encouraging gentle motion. In the presence of a significant
        hemarthrosis, a compression dressing and immobilization in extension is
        appropriate until early motion is comfortable. The knee sleeve is used
        for 4 to 6 weeks while an aggressive quadriceps rehabilitation program
        is pursued. Typically 6 weeks of monitored activities, keeping the knee
        out of pivoting and twisting activities, is recommended. The most
        important thing to accomplish in the first 6 weeks post-injury is
        return of normal quadriceps strength. Return to full functional
        activities should be based on functional strength rather than a
        specific time period from the original injury (13).

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    • Complications
      • Recurrent dislocation.
        The main physical examination feature associated with recurrent
        dislocation is continued quadriceps weakness. Recurrent dislocators
        that have successfully accomplished strength comparable to their other
        side will likely need surgical reconstruction to stabilize their
        patella. Recurrent patella dislocations are frequently associated with
        recurrent effusions at the time that the patient dislocates; a history
        that “my knee gives out” following an initial patella dislocation may
        represent quad weakness and not necessarily a re-dislocation.
      • Degenerative joint changes
        of the patellofemoral joint may occur when significant cartilage trauma
        is present from the initial/recurrent patella subluxations.
  • Meniscus injuries about the knee
    • Anatomic concerns.
      Menisci are C-shaped structures that rest on the medial and lateral
      sides of the tibial plateau, whose main function is shock absorbency of
      the tibial–femoral knee articulation. Because their outer perimeter is
      thicker than their inner rim, some stability is afforded by their
      anatomic construct as well. This added stability is most important when
      cruciate ligament laxity is present.
    • Mechanism of injury.
      Most isolated injuries of the meniscus (not associated with ligamentous
      injuries) occur with a rotatory stress on a weight-bearing knee.
      Isolated meniscal injuries occur from trapping of the meniscus between
      the femoral condyle and the tibia while the knee is weight bearing,
      typically in flexion. A history of locking or clicking is helpful, but
      it is frequently misleading.
      In a young patient (typically under age 30), significant
      trauma is necessary to injure a meniscus. However, in the older knee, a
      degenerative tear can occur from repetitive day-to-day activities.
    • Physical examination
      • Joint line tenderness is typically
        present along the medial (medial meniscus tear) or lateral (lateral
        meniscus tear) joint lines. This joint line pain increases with
        attempts at full extension or full flexion.
      • The McMurray test.
        An audible, palpable, and often painful clunk is produced when the knee
        is extended from the full flexed position while the tibia is forcefully
        externally rotated (medial meniscus) or internally rotated (lateral
        meniscus). This sign is associated with a torn meniscus. Crepitus or
        pain along the joint line and when this maneuver is performed, even in
        the absence of an audible clunk, are also suggestive of a
        medial/lateral meniscus tear. The reliability of this test is low,
        though it is classically discussed in most textbooks (14).
      • The presence of an effusion
        is frequent in a meniscus tear. Typically the normal knee has less than
        15 mL of fluid and is not detectable on physical examination. Small
        amounts of fluid can be detected by “milking” the suprapatellar pouch,
        looking for a fluid wave as one tries to push the fluid from the
        lateral side of the knee to the medial side of the knee. This maneuver
        is the best way to detect small amounts of swelling.
        The presence of an effusion limits complete extension of
        the joint and may be a cause of a lack of full extension and /or
        flexion.
    • Radiographs
      • A meniscus tear is not seen on plain x-ray.
        However, in an older patient, medial or lateral joint space narrowing,
        best seen on standing films, may give some indication as to the
        likelihood of a degenerative meniscus tear.
      • An MRI is
        frequently requested to confirm the presence of a meniscus tear. The
        MRI has high accuracy in diagnosing a meniscus tear (greater than 93%) (15,16).
    • Treatment
      • An isolated meniscus tear
        in the repairable zone in a young person should generally be repaired.
        The re-tear rate of a meniscus repair in a stable knee (not associated
        with a ligamentous tear) has a higher re-tear rate

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        than
        those meniscus tears associated with ligamentous instability when both
        meniscus and ligament injuries are surgically treated (17).

      • A symptomatic meniscus tear in the non-repairable zone
        and/or a complex meniscus tear that persists despite conservative
        management should be arthroscopically debrided. However, in the older
        age group, consideration must be given to the fact that the symptoms
        may be the result of osteoarthritis and cartilage wear and not from the
        meniscal tear.
      • In the older age group,
        where one suspects a degenerative meniscus tear, the meniscus tear is a
        reflection of generalized early arthritis of the knee joint. This
        “tear” should be treated symptomatically according to the patient and
        physician’s discussion. The presence of a degenerative meniscus tear on
        MRI is not an indication to treat. If the symptoms associated with a
        degenerative meniscus tear can be quieted down with rest, relative
        rest, and/or medication, surgical treatment may not be necessary (18).
  • Ligamentous injuries of the knee
    • Anatomic considerations.
      The cruciate ligaments are intraarticular/extra-synovial structures.
      When the cruciate ligaments are torn they can create a hemarthrosis or
      bleed into the joint. The LCL and superficial MCL are extraarticular
      structures. The deep MCL is a thickening of the joint capsule and thus
      is intraarticular.
    • Mechanism of injury
      • Ligamentous injuries
        can be the result of a direct or indirect trauma. Indirect trauma
        frequently occurs when the body rotates around a relatively fixed
        foot/leg. Direct injuries are a consequence of force directed to the
        knee or limb. Typically, the ligament opposite the area of contact is
        the ligament which is the most vulnerable. For instance, a blow to the
        lateral side of the knee places the MCL most under stress for injury.
        Straight plain instabilities (anterior, posterior, medial, lateral) are
        most readily assessable by direct physical exam. Rotatory instability
        of the knee (anterior lateral and posterior lateral) requires more
        sophisticated physical exam skills.
      • In an isolated tear of the MCL,
        palpable discomfort can be detected anywhere along the ligament from
        its origin on the medial femoral condyle to its insertion on the tibia
        (approximately three finger breadths below the joint line). The deep
        capsular ligament is a thickening at the joint line. Medial joint line
        tenderness is also associated with MCL injuries. However, different
        from a meniscal injury, an MCL injury would create pain to stressing
        the knee in a valgus direction, as well as externally rotating the leg
        with the knee flexed. Although attached to the medial meniscus, the
        incidence of an in-substance medical meniscus tears in an isolated tear
        of the MCL is low (19).
      • Isolated injuries of the LCL
        are rare. Frequently accompanying complete tears of the LCL are tears
        of the posterolateral complex with or without cruciate involvement. If
        one suspects a lateral/posterior lateral injury, physical examination
        must include close inspection of peroneal nerve function distally in
        the leg and foot region. Complete (grade 3) injuries to the
        posterolateral region of the knee do not heal, and superior results are
        present if the injury is addressed in the acute phase (with repair of
        structures) rather than the chronic phase of this injury. Any increase
        in external rotation of the tibia with the femur fixed that is
        increased over the patient’s opposite uninjured knee should be suspect
        for a posterolateral knee injury. This needs to be evaluated within
        days of the injury by a surgeon competent in treatment of
        multi-ligamentous injuries of the knee.
      • Isolated tears of the PCL
        are frequently associated with a hyperextension injury (indirect
        injury) or a blunt contusion to the front of the tibia (direct injury).
      • Isolated ACL injuries
        can be sustained through a number of mechanisms, most commonly a
        non-contact deceleration injury or landing from a jump. The potential
        causal mechanisms in non-contact ACL injuries have been

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        the subject of intense research in the last decade (20).
        Recent interventional studies suggest that neuromuscular training in
        improving bent knee landing and pivoting can be helpful in injury
        reduction (21).

    • Physical examination.
      The amount of joint line opening or motion between the tibia and femur
      that occurs with manual testing is graded according to American Medical
      Association (AMA) guidelines (4): grade 1
      injuries would be less than 5 mm of joint line opening; grade 2 are 5
      to 10 mm; and grade 3 injuries (complete tear) are more than 10 mm of
      opening (13).
      • The main clinical motion test
        for providing an analysis of the severity of MCL complex injuries is a
        valgus stress test with the knee flexed at 30 degrees. The leg is put
        over the side of the examining table, the fingers are placed on the
        medial joint line to assess the amount of joint line opening and
        rotation, and a valgus stress is applied to the knee. The reverse of
        this, placing a varus stress on the knee, is the main clinical motion
        test to analyze LCL instability.
      • Typically injuries to the LCL also involve injury to the posterolateral complex.
        Motion tests to determine the amount of injury to the posterior lateral
        complex of the knee are the most complex of all knee exams. It is
        beyond the scope of this text (22).
      • The main clinical motion test for an analysis of ACL injuries is the Lachman’s test (23) (Fig. 24-4).
        This is performed with the knee in approximately 20 degrees of flexion,
        with the leg in neutral rotation. The examiner holds firmly the distal
        femur in one hand and the proximal tibia in the other hand, then one
        places an anterior-directed force on the proximal tibia. Grading of
        displacement of the tibia on the femur is along the AMA guidelines. In
        addition to the Lachman’s exam, ACL injuries are associated with
        anterior lateral rotatory tibial subluxation that is best evaluated
        through the pivot shift maneuver or Losee maneuver (24).
        The anterior drawer test (done at 90 degrees of knee flexion), though
        historically cited, is not as reliable as the manual test for laxity of
        the ACL (14).
      • The main clinical motion test to detect injuries of the PCL is the posterior drawer test.
        This is performed by placing the knee at 70 to 90 degrees of flexion. A
        posterior force is applied to the tibia and the extent of translation
        and the quality of the endpoint is recorded. Again, AMA guidelines are
        used to assess the degree of translation. The key to this test is
        accurately assessing the starting point of the tibia (25).
        Another useful test in assessing PCL laxity in an awake
        patient is the “quads active” test: With the knee at 70 to 90 degrees
        of flexion, the patient is asked to activate his or her quads with the
        examiner holding the tibia in the position in which the tibia comes to
        rest. Posterior motion from this starting point is then assessed.
      • An acute knee examination should include all major ligamentous structures
        within the knee. Significant anterior-posterior translation (>10 mm)
        with the drawer or Lachman’s test may suggest an injury to both the ACL
        and the PCL. Varus and valgus stress testing should be performed both
        at 0 and 30 degrees of knee flexion. Asymmetry in varus or valgus
        laxity that exists at 0 degrees of knee extension suggests a posterior
        cruciate/posterior capsular injury as well as collateral ligament
        injury. Varus or valgus asymmetry laxity existing at 30 degrees of
        flexion but not at 0 degrees is indicative of at least an injury to a
        collateral ligament.
    • Treatment
      • Isolated tears of ligamentous injuries
        • MCL. Isolated tears of the MCL can be treated conservatively (19,26).
          For complete tears, progressive weight bearing on crutches, in a brace
          limiting valgus stress for 4 to 6 weeks is recommended. In the absence
          of a complete tear of the MCL, one can bear weight as pain and motion
          permits. Complete recovery after isolated MCL injuries is the norm,
          though distal MCL tears typically have more disability and take longer
          to heal (26).
          Figure 24-4.
          Lachman’s exam of the knee: This is a test for deciding the degree of
          anterior translation of the tibia under the femur. The knee is held
          firmly in place at 20 to 30 degrees of flexion by the examiner’s hand (A) or by resting the patient’s leg over the examiner’s knee (B).
          With a firm hold of the proximal tibia, the examiner places an upward
          or anteriorly directed force on the tibia, judging both the distance of
          translation and the firmness of the endpoint.

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        • Isolated tears of the PCL
          are frequently treated non-operatively. In the rehabilitation process,
          special emphasis on quad strength is important to maintain a muscular
          support to limit posterior displacement of the tibia.
        • Isolated tears of the ACL
          are prone to subluxation events when jumping and pivoting activities
          are performed. In young active patients, or middle-aged patients that
          have a high demand job or recreational aspirations, ACL reconstruction
          is typically advised. The goal of ACL reconstruction is to prevent
          future subluxation events which can be associated with meniscus and/or
          cartilage damage.

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        • Multi-ligamentous knee injuries
          most commonly involve the ACL/MCL or PCL with posterolateral injuries.
          An operative treatment yields the best functional results in two
          complete ligament knee injuries.
  • Knee dislocations
    • Evaluation and treatment.
      This relatively rare dislocation requires immediate reduction and
      evaluation for joint stability. Reduction under anesthesia is sometimes
      necessary (27,28).
      Immediate and continuous evaluation of vascular status of the leg
      reduction is important. If there is any question of the vascular
      supply, most specifically if pulses are diminished or absent in the
      affected limb, an arteriography must be performed immediately.
      Prophylactic fasciotomy should be considered to prevent a compartment
      syndrome following vascular repair, particularly if there is greater
      than 6 hours from injury to vascular repair. If a vascular repair is
      present combined with severe knee instability, an external fixator may
      be applied to protect the vascular construct until definitive surgical
      treatment of the torn ligaments ensues.
    • Early reconstruction of torn ligaments offers the best outcomes (28).
      If the injury is associated with a vascular repair and/or significant
      disruption to the skin, a subacute reconstruction is indicated (0–3
      weeks). Late surgical approach (more than 4 weeks) is more difficult
      secondary to soft tissue scarring, particularly if it involves a
      posterolateral corner, where individual structures can become more
      difficult to dissect. In dislocated knees that are approached late
      (more than 6 weeks), reconstructive efforts aimed at collateral
      ligament injuries are frequently necessary (in deference to a primary
      repair if done early). The cruciate ligament injuries are frequently
      reconstructed in acute and late surgeries in deference to a repair.
      Because of the typically severe nature of these injuries, allograft
      tissue in deference to autograft tissue from the same or contralateral
      knee is the norm.
      If the original injury has adequate joint surfaces and a
      competent vascular system, functional use of the leg will parallel the
      ability to get back satisfactory strength and motion. Acceptable
      function for day-to-day activities is common following these injuries.
      The ability to perform high-level activities following knee
      dislocations is rare.
  • Extensor mechanism disruptions
    • Anatomic considerations.
      The extensor mechanism consists of the quadriceps muscle complex,
      quadriceps tendon, patella, patella tendon, and patella tendon
      insertion into the tibial tubercle. Disruption of the extensor
      mechanism along any one of its parts can result in failure of the
      patient to perform a straight leg raising effort. A partial tear
      frequently results in the patient’s ability to lift his or her leg, but
      with a considerable lag (difference between passive and active
      extension of the leg).
    • Clinical considerations.
      A quadricep tendon disruption is difficult to assess on physical
      examination unless one requests a straight leg raising effort by the
      patient. Quadricep tendon ruptures are a frequently missed cause of
      acute knee injuries.
      Patella tendon disruptions
      are often associated with an indirect trauma consisting of a forceful
      quadriceps contraction against a relatively fixed lower limb. These can
      be subtle injuries.
      If the rupture is below the inferior border of the
      patella (i.e., in the patella tendon or at the tibial tubercle),
      patella alta would be present, best seen on lateral knee x-rays.
      Extensor mechanism disruptions commonly occur in
      patients with systemic illness such as diabetes or renal failure, or
      with use of exogenous steroids (prednisone or anabolic steroids).
      Cortical steroid injections for treatment of patella tendinosis has
      been associated with an increased incidence of rupture.
    • Treatment. The goal of treatment is to restore a functioning extensor mechanism to the knee. This is best accomplished surgically.

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IV. Special Concerns in The Growing Adolescent
  • Physeal injuries. One cause of an acute knee injury in a growing adolescent is an injury to the physis.
    • A distal femur physeal injury,
      particularly if it is a non-displaced injury, can be confused with a
      collateral ligament injury. Pain is present, not only at the origin of
      the collateral ligaments, but across the anterior aspect of the femur
      or tibia, which is readily palpable in most children. X-rays can show
      some widening and, at times, displacement of the physis. Stress x-rays
      can confirm the diagnosis and assess the stability of the fracture
      construct. Surgical reduction and stabilization for any displaced
      physeal fracture is imperative. Stable injuries can be treated
      non-operatively (29).
    • The tibial apophysis
      can avulse in the adolescent with closing growth plates. The tibial
      growth plate fuses from posterior to anterior, and an avulsion of the
      tibial tubercle frequently involves an interarticular fracture into the
      joint. By history this injury is associated with a strong quadriceps
      contraction; radiographically this injury is associated with patella
      alta. Surgical reduction and fixation is advisable for the best outcome
      when the tubercle is displaced.
  • Ligament avulsion.
    Cruciate ligament avulsions, particularly the attachments of the ACL
    and PCL onto the tibia, occur in the growing adolescent. When these are
    associated with a large bony fragment, surgical reduction and fixation
    is advised. The rehab will follow the course of a bone healing rather
    than of a ligament reconstruction/revascularization.
  • Osteochondritis dissecans
    • Definition.
      Osteochondritis dissecans (OCD) is defined as an area of avascular bone
      commonly presenting in the medial femoral condyle of a skeletally
      immature child. The etiology of this area of avascularity is unknown.
      Most commonly accepted theories are trauma, abnormal ossification
      within the epiphysis, ischemia, or some combination of the above.
      Approximately 40% of patients with OCD have a history of prior knee
      trauma to a mild or moderate degree (21). The
      medial condyle is involved 85% of the time versus 15% of the lateral
      condyle. Fifty percent of loose bodies in the knee are associated with
      OCD.
    • Natural history.
      The majority of juvenile lesions (presenting before closure of growth
      plates) heal spontaneously. In the skeletally mature, there is a higher
      incidence of bone fragmentation (subchondral fracture). This bone
      collapse is in the area of the avascular bone and is felt to be because
      of faulty lead transmission of bone just below the cartilage. In its
      extreme form, the osteocartilaginous lesion can break away from the
      healthy bone forming a loose body. Once there is a fracture of bone in
      the area of avascularity, symptoms increase and the involved fragment
      may become disengaged.
    • Treatment
      • Juvenile osteochondral
        lesions can generally be treated nonsurgically with rest or reduction
        from high impact activities and repetitive deep knee bending. The goal
        is to have the knee become pain free. The presence of an effusion is
        indicative of possible disruption of the articular surface, signifying
        the need for surgical evaluation. The patient and their family should
        be informed to return to the doctor if recurrent effusions are present.
        Following these patients in regular intervals (6–12 months) until
        resolution of the lesion on x-ray is advised.
      • Surgical treatment for adult OCD
        (OCD after growth plate closure) is typically recommended. The type of
        surgical treatment depends on the size and location of the OCD site and
        the quality of the overlying cartilage. Options include drilling,
        debridement, fixation, replacement, or excision. The discussion of this
        is beyond the scope of this review (6).
V. Overuse Syndromes
  • Definition.
    Repetitive submaximal or subclinical trauma that results in macro-
    and/or microscopic damage to a tissue’s structural unit can result in
    pain and/or dysfunction. Although clinicians refer to it as an “itis,”
    an inflammatory response

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    is
    not seen histologically. It is thought that damage to a tissue’s
    structural unit and/or blood supply is a frequent cause of overuse
    injuries.

    The most common form of overuse injury is from an
    endogenous source, that being mechanical circumstances in which the
    musculoskeletal tissue is subjected to greater tensile force or stress
    than the tissue can effectively absorb.
  • History.
    Overuse injuries are characterized by the absence of an acute injury,
    or at least no injury significant enough to explain the current
    clinical situation. The most important feature to look for in the
    patient’s history is a “change” in functional demand. A transitional
    athlete/worker, defined as a person with a change in his or her
    internal or external environment, is at high risk for development of
    overuse injuries. These include:
    • Change in intensity of repetitive activity (distance/time)
    • Change in frequency or duration of repetitive activity
    • Changes in equipment (footwear/surface changes including material composition and/or slope)
    • Changes in competitive climate/work climate/activity level
    • Changes in weather
    • Changes in lifestyle (puberty, aging, significant weight gain, and, for women, pregnancy and menopause)
  • Physical examination
    • Inspection
      • Alignment of
        the limb is a must in evaluating any overuse injury of the lower
        extremity. This includes tilt of the pelvis, rotation of the femur,
        varus or valgus alignment of the knee, and pronation or supination at
        the foot. Any change in “normal alignment” can cause tissue overload
        anywhere along the kinetic chain. Some limb alignment features are
        constitutional and cannot be changed short of surgery; others can be
        modified. The two most common forms of modification are:
        • An orthotic
          may change the position of a flexible foot and thus can affect the
          entire kinematic chain. Particularly, a flexible pronated foot can be
          restored to normal alignment with the use of an orthotic.
        • An anteriorly tilted pelvis is associated with increased internal femoral rotation and functional knee valgus. This can frequently be altered by appropriate hip abductor and extensor strengthening exercises (30).
      • Redness or warmth is not common in overuse injuries but may indicate the presence of an injured bursa or tendon.
      • Joint effusion is not common in overuse injuries. It indicates an intraarticular source of pathology.
  • Investigational tests
    • Strength tests. These can include:
      • Weakness compared to the contralateral limb
      • Concentric
        (muscle shortens while contracting) muscle strength versus eccentric
        (muscle lengthens while contracting) muscle strength in same muscle
        group (see H.1.b).
      • Agonist
        (joint motion in one plane due to muscle contraction) versus antagonist
        (the muscle group opposing or resisting joint motion caused by agonist
        muscle) strength in same limb (i.e., quad to hamstring strength)
      • Absolute strength and peak torque to body weight ratio compared to population norms
      • Endurance strength with a measure of muscle fatigability
    • Evaluation of flexibility, especially in key muscle groups, including quadriceps, hamstring, hip flexors, and Achilles tendon
  • Radiographs
    • Plain radiographs
      are infrequently necessary for evaluation of overuse injuries.
      Radiographic views of the patellofemoral joint, in particular axial
      views, may be helpful to assess patella position. Standing knee views
      show arthritic changes including bone spurs and joint space narrowing.

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    • MRI. The main
      advantage of an MRI is its ability to view intra- versus extraarticular
      pathology. Routine use of an MRI to diagnose overuse injuries is not
      advantageous, although significant tendinosis and bursal edema can be
      visualized by MRI.
  • Blood work
    • When there is a knee effusion that arises
      spontaneously or is associated with other complaints (e.g., rash or
      fatigue), then it is important to consider systemic diseases. Evaluate
      for systemic disease, including collagen vascular disease and Lyme’s disease (see II.D.1).
  • Treatment
    • Reduce tissue irritation and pain with:
      • Analgesic non-narcotic medications [nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen]
      • Physical therapy modalities (ultrasound, e-stim, massage)
      • Rest or relative rest of the injured part (reduce activities, substitute activities, and protect the injured part)
      • Ice
      • Elevation and compression if swelling is present
    • Correct anatomical problems when possible (patella sleeves, orthotics, braces, rarely surgery).
    • Correct biomechanical errors
      when possible (training sequence, sport style and form, strengthening
      and stretching of musculoskeletal units, evaluation of workplace
      station).
    • Correct environmental concerns when possible (new shoes, change to a more absorbent surface, adequate clothing).
  • Sports-specific rehabilitation
    • Recovery of strength
      • Closed chain exercises
        of the lower extremity are those exercises where the foot is supported
        or planted during the exercise thus “closing the loop.” Leg press or
        stand-up exercises such as partial squats are examples of closed chain
        lower leg exercises. For lower extremity activities,
        closed chained techniques are more functional and can obtain comparable
        gains in quadriceps strength with less overuse of the patellofemoral
        joint (30).
      • Concentric/eccentric muscle strength. Concentric
        muscle contractions occur when a muscle shortens as it contracts. In an
        eccentric contraction, the muscle lengthens as contraction occurs.
        Eccentric strengthening has
        long been favored for recovery of strength in the treatment of
        tendinosis. For the patellofemoral joint, eccentric muscle activity is
        an important part of functional use of the joint. Eccentric strength is
        the main decelerator of the body, an important function of the
        quadriceps complex.
  • The physician.
    The physician’s role in diagnosing overuse injuries is to render an
    injury with its appropriate treatment as well as educating the patient.
    Patient education is the best treatment for the prevention of overuse
    injuries in the future.
  • The patient.
    The patient’s role is to understand the causative factors in the injury
    and to understand the progression from injury to wellness. This
    includes activity modifications and their role in modifying their
    activities. The patient needs to implement a paced return to full
    activities.
VI. Overuse Injuries About The Knee
  • Patella tendonosis
    • Patella tendonosis is a common overuse
      injury that more typically affects the proximal attachment of the
      patella ligament to the inferior pole of the patella, but can also
      affect the distal end of the tendon. It is also called a jumper’s knee
      because it occurs most frequently in athletes who require repetitive
      eccentric quadricep contractions, as is common in jumping athletes, and
      athletes who frequent heavy weight training.
    • The case of patella tendonosis is generally considered to be chronic stress overload resulting in microscopic tears of the tendon with incomplete healing.

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    • Treatment is
      conservative and is the cornerstone of treatment for tendonosis. In
      addition to the general scheme of treatment of overuse syndromes
      outlined previously, the primary treatment emphasizes maximizing quad
      strength and knee joint flexibility, reducing repetitive eccentric
      quadriceps contraction exercises, and re-adding them in a paced
      fashion. Infrequently, surgery is necessary for the patient with
      recalcitrant disease. An MRI or ultrasound can be used to define the
      area of the tendon affected by chronic tearing and subsequent
      degeneration. Excising this area of the tendon can be useful (31).
      Alternative schools of thought feel that the distal pole of the patella
      impinges on the patella tendon, and excision of the distal pole can be
      useful in treating this form of tendonosis (32).
  • Iliotibial band syndrome
    • Iliotibial band (ITB) syndrome (also known as ITB tendonosis)
      is caused by excessive friction between the iliotibial band and the
      distal lateral femoral condyle. The ITB functions as a weak extender of
      the knee in near full extension, and a more powerful knee flexor after
      30 degrees of knee flexion. The ITB is most stretched over the lateral
      femoral condyle at 30 degrees of knee flexion. This condition is common
      in runners and cyclists.
    • Anatomic factors
      have been implicated in ITB syndrome and include excessive foot
      pronation, genu varum at the knee, tight lateral patella retinacular
      structures, and an anterior tipped pelvis. Treatment is directed at
      modification of the initiating causative factors and reducing the
      excessive friction. Stretching of the ITB, treating foot pronation with
      an orthotic, treating a tight lateral patella retinaculum with manual
      therapy, and repositioning of an anterior tilted pelvis all can be
      useful interventions when the patient has these physical examination
      features.
  • Tibial tubercle apophysis (Osgood-Schlatter disease)
    • Clinical diagnosis.
      This syndrome is usually seen in the rapidly growing athletic
      adolescent with open growth plates at the knee. It is characterized by
      point tenderness and enlargement of the tibial tubercle at the site of
      the patella tendon insertion. A constant traction to this location
      produces overgrowth of the tibial tubercle apophysis. X-ray evaluation
      can be negative, or at times a prominent or irregular apophysis is
      seen. Once the apophysis has closed, there frequently can be a free
      bony particle anterior and superior to the tibial tubercle.
    • Treatment.
      The symptoms usually abate when the tibial tubercle fuses to the
      diaphysis, and, therefore, every effort should be made to quiet this
      injury down until full maturation is present in the developing
      adolescent. Treatment depends on the severity of the disease. Nearly
      all cases are managed by the proper balancing of activities against the
      patient’s symptoms. This can follow the general treatment pattern of
      overuse injuries as previously outlined. Surgical treatment is not
      indicated. Aggressive treatment might occasionally involve limited use
      of a knee immobilizer in recalcitrant cases where the patient is
      dysfunctional in day-to-day activities, or non-compliant in activity
      reduction.
  • Patellofemoral pain syndrome
    • Definition.
      Patellofemoral pain syndrome is used to describe a constellation of
      symptoms that are related to the patellofemoral joint. Typically, this
      type of pain is considered an overuse syndrome, although the exact
      etiology and nature of pain continues to be poorly understood.
      Patellofemoral pain syndrome is that pain which originates in the
      anterior knee structures, in the absence of an identifiable acute
      injury (blunt trauma, dislocating or subluxing patella).
      Chondromalacia patella (CMP) is a term often used to
      describe anterior knee pain, though use of this term to describe
      clinical symptoms is not appropriate. CMP should be used only to
      describe the pathological entity of cartilage softening on the
      underneath side of the kneecap. Typically this could only be diagnosed
      by surgical observation or MRI. The presence of cartilage softening
      does not always result in the clinical symptom of pain.
    • Pre-existing conditions.
      Anatomic factors that can predispose a patient to patellofemoral pain
      can include flexibility deficits of the limb, malalignment

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      of
      the lower limbs including excessive femoral anteversion, high Q-angle,
      rotation variations of the tibia, genu velgum at the knee, hind foot
      valgus, and pes planus. Kneecap malalignment,
      both static and functional, has been implicated in the etiology of
      patellofemoral pain. However, there are a few population-based studies
      to support the “malalignment theory kneecap pain.” Any one abnormality
      may be trivial as a single entity. However, in combination with other
      anatomic variables and associated with overtraining and overuse, they
      frequently can lead to overuse injury (14).

      The role of malalignment and
      the etiology of patellofemoral pain continue to be debated.
      Radiographic imaging studies can reveal a patella that is malaligned
      within the trochlear groove, as evidenced by a patella tilt and/or
      subluxation. Some malalignment syndromes of the patella are residual
      from a previous subluxing or dislocating event. However, other
      malalignment syndromes can be present in the absence of an acute event,
      and frequently are similar in both knees of the same person. It is felt
      that patella malalignment, when constitutional in a person, can become
      an overuse syndrome more readily and become a painful problem.
    • Clinical presentation.
      The most common clinical presentation of a patellofemoral pain syndrome
      patient is pain on the anterior aspect of the knee that is aggravated
      by prolonged sitting and stair climbing. Because the retinacular
      structures of the patella extend both medially and laterally from the
      patella, pain can also be associated with either medial- or
      lateral-sided knee pain, therefore, it can create a very confusing
      clinical presentation. It is infrequently associated with swelling.
      Giving-way episodes can be reported; typically the giving-way episode
      is with straight-ahead activities or stair-climbing, when one tries to
      engage the quad and the quad “fatigues.” This should not be confused
      with giving-way episodes associated with ligamentous instability, which
      typically occur with planting, pivoting, or jumping activities.
      Patients can also present with catching or clicking phenomena. This can
      occur because of irritation of the knee-cap as it tracks in the
      trochlear groove. Another common patient complaint is that the knee
      “locks.” If the knee “locks” in full extension, this is a manifestation
      of patellofemoral pain. The patient does not want to engage the knee
      cap in the groove because of pain, and, therefore, keeps his or her leg
      straight. If the knee is locked secondary to a loose body or torn
      meniscus, it is always locked in some degree of flexion.
    • Treatment.
      Historically, non-surgical treatment has been the cornerstone for most
      patellofemoral pain disorders. The primary goal of patellofemoral
      rehabilitation is to reduce the symptoms of pain. This is done by a
      combination of physical therapy modalities, improving quadriceps
      strength, and endurance (see V. H). Other tools such as orthotics, knee sleeves, and McConnell taping can be used (33). Pelvic muscle strength, especially hip abductor and hip extensor strength, is essential for rotational control of the limb (23,30,34).
  • Pes anserinus bursitis
    • Definition.
      The “pes” tendons are terminal insertions of three long thigh muscles,
      one from each muscle group. These tendons come together to insert on
      the anteromedial aspect of the proximal tibia, between the tibial
      tubercle and the distal (tibial) attachment of the medial (tibial)
      collateral ligament. The three tendons are sartorius (femoral
      innervation), gracilius (obturator innervation), and semitendonosis
      (sciatic innervation). They are powerful internal rotators of the leg
      (tibia) and also aide in knee flexion.
    • Clinical presentation.
      The patient will present with soreness just below the medial knee,
      which can be reproduced by direct palpation or resisted internal
      rotation of the leg. In middle age, it can represent a referred pain
      pattern from the knee due to medial knee arthritis.
    • Treatment. In
      addition to the rest, ice, compression, and elevation (RICE) principle
      and physical therapy with modalities of stretching and strengthening, a
      steroid injection at the bursa site can be helpful.

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Selected Historical Readings
Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg (Am) 1977;59:236–239.
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