COMPLICATIONS OF KNEE SURGERY

Postoperative hemarthrosis is the most common
complication of knee arthroscopy, comprising 60% of all complications.
It occurs in approximately 1% of all cases and is seen most often after
lateral retinacular release (5,25). Other procedures that frequently result in hemarthrosis

include arthroscopic synovectomy, meniscectomy, and ACL reconstruction.
Use of a tourniquet can be associated with postoperative hemarthrosis
because unrecognized intraoperative bleeding may occur (4,23).
A coagulopathy (ASA-induced, liver dysfunction, or hemophilia) may
first present as abnormal intraoperative or postoperative bleeding.

Treatment for hemarthrosis consists of brief
immobilization, elevation, compressive dressing, and isometric
quadriceps exercises. Oral nonsteroidal antiinflammatories may also be
of benefit. Resume range-of-motion exercises once swelling is
decreased. A tense effusion may require aspiration, but repeated
aspiration may lead to septic arthritis and is not recommended. Rarely,
a large hematoma may require repeat arthroscopic surgery. Consider
checking a coagulation screen and a bleeding time in patients with
unexplained bleeding.

Infection following arthroscopic knee surgery is uncommon and occurs with an overall incidence of 0.24% (25).
Risk of infection is increased with perioperative use of intraarticular
steroids, with any break in sterile operative technique, in
immunocompromised patients, and in patients with skin lesions in the
operative field. Postpone elective arthroscopic procedures in any
patient who has wounds, scrapes, or skin rashes that involve the
operative field. Avoid intraoperative injection of corticosteroids
because this has been associated with an increased rate of infection (1,11).
In those patients who have had recent intraarticular corticosteroid
injections, it is preferable to postpone elective procedures for 3 to 4
weeks to minimize the risk of infection.

The effectiveness of routine prophylactic antibiotics
for knee arthroscopy remains unproven, but it should be considered for
high-risk patients and with more extensive procedures (21). I recommend antibiotics for procedures that involve implants, internal fixation, osseous tunnels, or osteotomy.

Delay in diagnosis is common with postoperative knee
infections, and a high index of suspicion is necessary to ensure early
recognition (6,25).
Immediate and aggressive treatment is required in any suspected septic
knee to avoid severe articular damage. Make the diagnosis of infection
by knee joint aspiration, sending the fluid for immediate Gram stain,
cell count, and differential. Order routine aerobic and anaerobic
cultures as well. Once an infection is confirmed, urgent surgical
debridement, arthroscopically or open, and postoperative intravenous
antibiotics are required. The type and duration of antibiotic therapy
are dependent on the causative organisms and severity of infection. In
some cases repeat surgical debridements may be necessary. With
infection after ACL reconstruction, graft retention may be possible,
but arthroscopic debridement alone may be inadequate because
extraarticular spread of infection is frequent (9).

All surgical procedures of the lower extremity have some
risk of thromboembolic complications. Knee arthroscopy, however, is
associated with a lower risk than more extensive procedures such as
total knee arthroplasty. Small (25) reported
the overall incidence of deep venous thrombosis (DVT) with arthroscopic
knee surgery to be 0.15%, and the incidence of pulmonary embolism (PE)
was 0.05%. Of the 12 DVTs that occurred in Small’s series, eight
involved cases in which the tourniquet was used for an average of 50
min or more. Demers et al. (6) also reported a
significantly higher incidence of DVT after knee arthroscopy with
prolonged tourniquet times, suggesting a relationship between
tourniquet use and thrombosis.

Although rare, fatal pulmonary embolism has been
reported in young healthy patients after routine elective outpatient
knee arthroscopy (20). A high index of
suspicion is necessary to ensure early identification and treatment of
thrombosis to reduce the risk of embolization. Noninvasive studies (or
venography) are mandatory in any patient with suspected postoperative
thrombosis. Initiate anticoagulation immediately for all patients with
positive tests. The presence of a negative test in a patient with the
clinical picture of DVT does not exclude the possibility of an evolving
DVT, and careful follow-up with repeat studies is required. A ruptured
popliteal cyst may mimic thrombosis, but this diagnosis can also be
established with noninvasive studies such as ultrasound or MRI.

Risk factors for postoperative thromboembolism include
prolonged tourniquet use, hypercoagulable states (malignancy, oral
contraceptives), morbid obesity, congestive heart failure, and history
of prior thrombosis or pulmonary embolism (5,21).

Prevention of postoperative thromboembolic complications
is best accomplished with early mobilization, range-of-motion
exercises, and weightbearing as soon as possible. Aspirin may be of
benefit for routine postoperative prophylaxis. Consider coumadin or
low-molecular-weight heparin in patients at increased risk.

Anesthetic complications may occur with procedures using
general, regional, or local anesthesia. Intubation may result in
laryngeal, dental, or temporomandibular joint (TMJ) injury;
neuromuscular blockade may reveal pseudocholinesterase deficiency or
malignant hyperthermia; and intraoperative cardiac arrhythmia,
infarction, or arrest may occur, although rarely. Spinal or epidural
anesthetic can lead to spinal headache, transient spinal block,

or
epidural hematoma. Local anesthetics in high doses may produce systemic
effects. A careful preoperative assessment by both surgeon and
anesthesiologist can identify those patients at increased risk and
minimize the likelihood of anesthetic-related complications.

Most intraoperative instrument failure and breakage is
preventable and results from improper instrument use or maintenance.
With proper surgical technique and instrument care, the incidence of
instrument breakage is minimal (5,25). Arthroscopic instruments, unlike osteotomes and elevators, are fragile and delicate and require special care and handling.

Never use an arthroscopic instrument that is dull, worn,
or bent. If a broken metallic instrument fragment (or guide pin) does
become an intraarticular loose body, a prepackaged sterile magnetic
probe (for example, the “Golden Retriever,” Instrument Makar, Okemos,
MI) is an indispensable tool. Intraoperative x-ray or fluoroscopy may
occasionally be required to localize elusive fragments. Most broken
instrument and pin fragments can be removed arthroscopically; although
an accessory posterior portal may be helpful, an arthrotomy is seldom
necessary.

Reflex sympathetic dystrophy (RSD) of the knee is most
common in patients who have sustained diffuse crush injuries or direct
injuries to motor and sensory nerves. Patients who develop RSD often
have some predisposing diathesis that is triggered by an injury. It may
present initially as pain out of proportion to injury or physical
findings.

Although many tests, including three-phase bone scan,
can support the diagnosis of RSD, the diagnosis is made primarily on
clinical grounds. The findings of delayed recovery with severe diffuse
pain, skin sensitivity, and erythema should suggest early RSD (12,15,18).
Treatment consists of sympathetic blockade, gentle restoration of joint
motion to prevent fibrosis, and, if possible, elimination of the
underlying painful stimulus.

Careful surgical technique and careful patient selection
are the best means to avoid RSD. Inaccurate arthroscopic portal or
meniscus repair incision placement can injure the infrapatellar branch
of the saphenous nerve and incite RSD (15,18).
Avoid prolonged immobilization, prolonged protected weightbearing, and
diagnostic arthroscopy in patients with severe diffuse knee pain.

Arthrofibrosis of the knee can develop after trauma or
elective surgery. It is seen most commonly with anterior cruciate
injuries, particularly when ligament reconstruction is performed early
following injury (3,22).
The initial phase of arthrofibrosis begins with adhesions, which, if
allowed to progress, lead to patellar entrapment, joint fibrosis,
capsular contracture, and extracapsular scarring. Once patella infera
has developed, permanent loss of motion is likely.

Treatment of arthrofibrosis is based on stage and severity (13). Early recognition and treatment are the best means to restore movement and function. In the prodromal stage
(2 to 8 weeks), direct therapy at patellar mobilization and restoration
of motion. Correct underlying causes of stiffness, such as graft
impingement. Arthroscopic lysis of adhesions followed by gentle
manipulation under anesthesia can relieve early patellar entrapment. A
valuable technique involves using a blunt arthroscopic obturator in the
superomedial portal to disrupt patellar adhesions. To maintain
improvements in motion, postoperative epidural pain control combined
with continuous passive motion (CPM) for 3 to 5 days is beneficial.

Once the active stage (8 to
20 weeks) of arthrofibrosis has developed, all patellar mobility has
been lost, capsular contracture is established, and joint fibrosis has
begun. At this stage, open surgical release is often required. When
patella infera with severe limitation of motion is present, it is
indicative of the burned-out stage. At
this point, salvage procedures such as tibial tubercle osteotomy or
patellar tendon lengthening may be necessary to improve knee flexion;
however, do not expect restoration of normal motion (13).

Risk factors for developing arthrofibrosis include poor
rehabilitation before surgery, early extensive ligament reconstruction,
prolonged postoperative immobilization, older patients, associated
fractures, and nonisometric graft placement (3,13,17,22).
To prevent arthrofibrosis, postpone reconstructive procedures until
knee motion has been restored following injury. At the time of
reconstruction, it must be confirmed intraoperatively that full knee
motion is possible, and postoperative immobilization should be with the
knee in extension. Focus early rehabilitative exercises on regaining
quadriceps control and full extension, followed by patellar
mobilization and restoration of flexion (3).
When recovery of motion is unusually slow, early intervention is
essential to avoid the progression to active arthrofibrosis. Once
established, arthrofibrosis invariably causes some degree of permanent
stiffness.

Iatrogenic ligament injuries occur most often when
stress is applied to the knee during arthroscopy. The medial collateral
ligament is most commonly injured, particularly when a rigid
leg-holding device is used (5). In contrast, intraoperative cruciate ligament injuries are usually the

result of instrumentation errors. Ligament damage may occur during
notchplasty and tunnel preparation for cruciate reconstruction.
Aggressive motorized debridement combined with poor arthroscopic
visualization may lead to significant ligament injury. Many
misadventures, including patellar ligament resection, have been
reported (2).

Intraoperative ligament injury can best be avoided by
careful surgical technique. Visualization is better accomplished by
accurate portal placement than by forceful leg manipulation. Careful
instrumentation under direct arthroscopic visualization will prevent
inadvertent damage to ligaments and articular surfaces.

Fractures of both the femur and tibia have been reported during knee arthroscopy (5,21,25).
They are most often the result of excessive forceful manipulation of
the leg but may also occur in pathologic bone. Before surgery, review a
current set of knee radiographs (AP and lateral) in all patients
scheduled for arthroscopic surgery to search for an occult neoplasm or
other bone pathology (8).

Technical errors during ACL reconstruction may lead to
perioperative fracture. Eccentric or aggressive patellar tendon harvest
from the anterior patellar cortex may lead to fracture. Do not violate
the proximal third of the patella and minimize the use of mallets and
osteotomes. I recommend autogenous grafting of the bone defect with
tunnel reamings. With endoscopic femoral tunnel preparation, multiple
guide-pin perforations of the femoral cortex produce a stress riser and
may lead to postoperative fracture (27).

Manipulation of the stiff postoperative knee requires
caution because overly aggressive manipulation may yield disastrous
results. Patellar fractures, long-bone fractures, extensor mechanism
ruptures, and avulsions have all been reported to occur (5,21,24,25). Significant force during manipulation is seldom required or beneficial.

Persistent synovitis following knee arthroscopy may
occur from chemical irritation induced by glutaraldehyde (Cidex)
residue, from mechanical irritation caused by retained debris or
degenerative arthritis, from crystalline arthritis (e.g., gout,
pseudogout), and with septic arthritis (7).
Once infection has been excluded, treat chronic synovitis with
compressive wraps, activity modifications, and oral antiinflammatories.
Refractory cases may occasionally require repeat arthroscopy to treat
sources of ongoing chemical or mechanical irritation.

Synovial fistulas may develop at arthroscopic portal
sites. These are most common with procedures such as synovectomy and
lateral release, which produce hemarthroses (5).
The presence of significant degenerative arthritis and the use of
posterior portals are also associated with an increased risk of fistula
formation (16). Treat with 7 to 10 days of
immobilization to allow wound healing. Prophylactic oral antibiotics
(first-generation cephalosporin) are recommended but may lead to
resistant pathogens should joint sepsis occur. Should the fistula fail
to resolve with immobilization, excision and closure of the fistula
tract are required.

The majority of nerve injuries that occur with knee
arthroscopy involve sensory nerves. Nerve damage may result from direct
injury, tourniquet compression, or compartment syndrome. Although the
actual deficit from a sensory nerve injury is usually minor, it may
lead to neuroma formation or trigger reflex sympathetic dystrophy.

The infrapatellar branch of the saphenous nerve is most commonly injured (18).
It may be damaged by inaccurate portal placement or with a
posteromedial incision for meniscus repair. To minimize the risk of
nerve injury with medial meniscus repair, use a posterior retractor,
pass sutures with the knee extended using the anterolateral portal for
suture placement, and tie suture under direct vision (26).

Motor nerve injuries are fortunately rare. Peroneal
nerve injury may occur with lateral meniscus repair, but it has also
been reported with both diagnostic arthroscopy and partial lateral
meniscectomy (14,19).
Perform operative procedures in the lateral compartment with the knee
flexed in the figure-4 position, as the nerve is most easily injured by
arthroscopic instruments with the knee extended (14).
When repairing the lateral meniscus, minimize the risk of nerve injury
by using a posterior retractor placed through a posterolateral
incision, combined with suture passage from the anteromedial portal
with the knee flexed (26).

Popliteal artery injury is rare and can be avoided with
attention to the anatomy and proper surgical technique. Instrumentation
of the posterior horn of the lateral meniscus must always be under
direct arthroscopic visualization because of the close proximity of the
popliteal artery. Prepare the tibial tunnel for PCL reconstruction only
under direct arthroscopic observation to avoid guide-pin migration or
overreaming. If a popliteal artery injury is suspected, an
intraoperative vascular surgery consultation is mandatory.

When meniscal fragments are lost and unretrievable, do a
systematic inspection of all knee compartments. Lost fragments can
often be found in the suprapatellar pouch,

medial
and lateral gutters, posterior knee, and under the menisci. If, after a
careful search, the lost fragment cannot be located, conclude the
procedure because the majority of even large lost fragments become
attached to the synovium and do not produce symptoms (10).
Similarly, bone fragments and debris generated during cruciate ligament
reconstruction have been found to resorb spontaneously within 6 months (28).