High Yield Topics

Knee Pain

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Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.
Title: 5-Minute Orthopaedic Consult, 2nd Edition
> Table of Contents > Knee Pain

Knee Pain
John H. Wilckens MD
Bill Hobbs MD
Basics
Description
  • Knee pain has many causes, including
    pathologic processes in the knee and disorders in distant locations
    with referral to the knee area.
  • Diffuse or located in a specific region
  • A characteristic history and physical examination frequently narrow the diagnosis (1).
  • Classification:
    • Traumatic
    • Acquired
Risk Factors
  • Athletic activity (2)
  • Obesity
  • Sedentary lifestyle
Etiology
  • Traumatic injury
  • Overuse injury
  • Disease process(es) in or around the knee
Associated Conditions
  • Rheumatoid arthritis
  • Active lifestyle
Diagnosis
Signs and Symptoms
  • General:
    • Swelling
    • Locking
    • Popping
    • Difficulty with stairs and rising from a chair
    • Chronic pain with increased activity
  • Patellofemoral conditions:
    • Patellofemoral syndrome:
      • Typically occurs in young adults
      • Involves articular cartilage softening
      • Pain is most frequent in the anterior knee and is worse with stairs.
      • Knee ROM often has a grating sensation, and pain is elicited by pressing firmly on the patella.
    • Patellar subluxation–dislocation:
      • Traumatic
      • Can be related to a combination of
        structural variations (compared with normal anatomy) in the knee and
        leg: Femoral anteversion and valgus (a configuration that increases the
        Q angle) and a laterally moving patella with an extended knee (“J sign”)
    • Articular cartilage injury:
      • Frequently related to a traumatic event
      • Pain is worse with activity.
  • Meniscal injuries (3):
    • Can be degenerative (with an incidental initial event) or traumatic (with a clear injury)
    • Swelling develops slowly and is activity related.
    • Locking or giving-way of the knee, along with medial or lateral joint line pain, is common.
  • Arthritis:
    • Symptoms frequently are gradual in onset and progressive.
    • Pain is worse with increased activity and improves with rest.
    • Pain at night after an active day is common.
  • Ligament tears:
    • ACL:
      • Prevents anterior translation of the tibia on the femur
      • Injured predominantly from noncontact decelerations such as stopping suddenly, pivoting, or landing after jumping
    • PCL:
      • Primary stabilizer to posterior translation of the tibia on the femur
      • Direct trauma to anterior knee (“dashboard injury”)
      • Knee pain and swelling occur after the injury, with improvement in generalized pain symptoms at several weeks.
      • Develop medial compartment and patellofemoral symptoms over time
    • MCL:
      • The primary restraint to valgus stress on the knee
      • Pain is felt along the medial aspect of the knee, typically extending proximally and distally along the region of the MCL.
      • Isolated MCL injuries occur from a direct blow to the lateral knee.
      • Can be associated with ACL and meniscal tears.
    • LCL:
      • Extends from the lateral femoral condyle to the fibular head
      • Isolated injury to the LCL is rare.
      • LCL Injury frequently is associated with a cruciate ligament injury.
      • Assessment of the peroneal nerve is important.
  • Quadriceps or patellar tendon rupture (4):
    • Causes a loss of extension of the leg
    • Symptoms include the inability to extend the knee actively, pain, and knee effusion.
    • Often a palpable defect and a patella that appears more distal (quadriceps) or more proximal (patellar) than normal
    • Most frequent cause is direct trauma to
      the knee or forced flexion of the knee that is resisted by maximal
      quadriceps contraction.
  • Bursitis and tendinitis:
    • Inflammatory changes occur in the bursa
      or tendon insertions around the knee, typically with tenderness to
      direct palpation over the anatomic location.
  • Osteochondritis dissecans:
    • Observed in children and young adults who are active and participate in sports
    • Result of localized bone necrosis with loss of overlying cartilage support
    • Symptoms include knee pain, effusion,
      tenderness over the lesion, and (occasionally) locking or catching of
      the knee if the fragment has become a loose body in the joint.
    • Pain often is insidious and related to activity.
  • OSD:
    • An overuse syndrome from repetitive stress on the tubercle, resulting in an apophysitis of the patellar tendon insertion
  • Baker cyst (popliteal cyst):
    • Caused by a distended capsule in the posterior fossa of the knee, often directly connected to the joint space
    • Most often associated with intra-articular disease
    • Presents as a mass in the popliteal fossa of the knee
    • The intra-articular disorder may not be symptomatic; therefore, the patient may complain only of posterior knee fullness.
  • Fracture:
    • Fracture about the knee should be ruled out in any patient with a traumatic injury.
    • Can occur in the distal femur, proximal tibia, and patella
    • Usually, plain AP and lateral radiographic views are sufficient.
  • Bone tumor:
    • Rare, but should be a differential diagnosis in patients with night pain
    • Most patients have musculoskeletal pain.
      • Typically described as dull, deep, aching
      • Often becomes constant
      • Many patients experience pain at night.
      • May not be related to activity
    • Patients also may complain of swelling,
      loss of function at the involved site, weight loss, or acute symptoms
      of a pathologic fracture.
Physical Exam
  • Palpate the joint for:
    • Effusion and localized swelling
    • Joint line tenderness (Medial and lateral tenderness suggests meniscal tear or arthritis.)
  • Compare ROM of the affected knee with that of the contralateral knee.
  • Observe patellar tracking as the knee is ranged from flexion to extension.
  • Check joint stability (MCL, LCL, ACL, OSD).

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Tests
Lab
  • Order serum laboratory tests based on a suspicion for specific clinical entities, as follows:
    • Septic arthritis: Complete blood count with differential ESR, C-reactive protein
    • Rheumatoid arthritis or other inflammatory arthritis: Rheumatoid screen, including rheumatoid factor and antinuclear antibody
    • Gout: Serum uric acid level
Imaging
  • The 1st step is plain radiographs
    (including weightbearing posteroanterior, lateral, and tangential
    [Merchant] views) of the patella.
  • MRI is used to detect meniscal tears, ligament injury, synovial proliferative disorders, tumors, and AVN.
Diagnostic Procedures/Surgery
  • Arthrocentesis often can aid in establishing a definitive diagnosis.
    • With septic arthritis, findings include positive culture and elevated white blood cell count (>50,000).
    • With gout, findings include uric acid crystals.
    • Fat droplets suggest intra-articular fracture.
Pathological Findings
Depend on causative factors
Differential Diagnosis
  • A complete differential diagnosis is beyond the scope of this chapter (5), but most common:
    • Patellofemoral conditions
    • Articular cartilage injury
    • Meniscal disorders
    • Arthritis
    • Ligament tears
    • Tendinitis and tendon ruptures
    • Osteochondritis dissecans
    • OSD
    • Baker cyst
    • Gout
    • Fracture
    • Tumor
  • The diagnosis can be made by symptoms and history in conjunction with the physical examination and imaging studies (Table 1).
Table 1
Symptom/History Location of Pain Diagnosis
Locking Medial or lateral knee Meniscus tear
Pop and sudden turn Entire knee with swelling ACL injury
Stairs and getting out of chair Anterior knee Patellofemoral cause
Striking knee hard against dashboard Entire knee with swelling OSD injury
Side contact to knee Medial or lateral knee Collateral ligament
Chronic pain with increased activity Medial or lateral knee Arthritis
Treatment
General Measures
  • Patellofemoral syndrome: Anti-inflammatory medication and exercise
  • Patellar subluxation-dislocation: Often improved by extensive physical therapy and patellar bracing
  • Arthritis: Initially, analgesics, activity modification, injections, unloader bracing
  • Bursitis and tendinitis: Analgesics, topical treatments, activity modification
  • OSD: Rest and activity modification
  • Ligamentous and meniscal injuries: Protected ROM and weightbearing, ice, analgesics, and orthopaedic referral
Special Therapy
Physical Therapy
  • Excellent for treating patients with knee pain (6)
  • Therapists:
    • Concentrate on ROM; quadriceps, hamstring, and core strengthening; and stretching.
    • May include modalities such as cryotherapy, electrical stimulation, and ultrasound
Medication
  • NSAIDs
  • Acetaminophen
  • Mild narcotic analgesics
  • Intra-articular hyalurans
Surgery
  • 3 main categories of knee surgery (7):
    • Arthritis: Arthroscopic meniscal and cartilage débridement, tibial and femoral osteotomy, total and hemi knee replacement
    • Sports medicine: Arthroscopic evaluation and treatment of meniscal and ligament injuries, patellar mechanism realignment
    • Trauma: Internal fracture fixation, tendon rupture repair
Follow-up
Prognosis
Excellent with well-defined diagnoses and appropriate surgical and nonsurgical treatment
Complications
  • Loss of motion
  • Loss of function, particularly weightbearing
  • Chronic pain
Patient Monitoring
Patients are followed at 4–6-week intervals until they regain strength and ROM.
References
1. Jensen JE, Conn RR, Hazelrigg G, et al. Systematic evaluation of acute knee injuries. Clin Sports Med 1985;4:295–312.
2. Collins HR. Screening of athletic knee injuries. Clin Sports Med 1985;4:217–230.
3. Henning CE, Lynch MA. Current concepts of meniscal function and pathology. Clin Sports Med 1985;4:259–265.
4. Carson WG, Jr. Diagnosis of extensor mechanism disorders. Clin Sports Med 1985;4:231–246.
5. Wilckens
JH, Mears SC, Byank RP. Knee, lower leg, and ankle pain. In: Barker LR,
Burton JR, Zieve PD, eds. Principles of Ambulatory Medicine, 7th ed.
Philadelphia: Lippincott Williams & Wilkins, 2006, in press.
6. Montgomery JB, Steadman JR. Rehabilitation of the injured knee. Clin Sports Med 1985;4: 333–343.
7. Feagin JA, Jr. Operative treatment of acute and chronic knee problems. Clin Sports Med 1985;4: 325–331.
Miscellaneous
Codes
ICD9-CM
  • 719.46 Pain in joint
  • 719.6 Knee pain
Patient Teaching
Activity
Depends on causative pain factors
FAQ
Q: What is a sensitive physical finding for intra-articular knee pathology?
A: In addition to localized tenderness, a knee effusion suggests intra-articular abnormality.

Q: How do meniscal tears occur?
A:
Meniscal tears can occur with an acute ligament injury, such as an ACL
injury, or in chronically ligament-deficient knees because the menisci
serve as secondary knee joint stabilizers. Degenerative tears can occur
in the meniscus from malalignment, overuse, and repetitive trauma.

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