Sandra L. Najarian
FRACTURES
CLINICAL FEATURES
Patients with patellar fractures present with localized tenderness, swelling, and often, a disrupted extensor mechanism (inability to extend the knee or perform a straight leg raise against gravity).
Transverse fractures are the most common type of patellar fracture; other types include comminuted, non-displaced, vertical, and avulsion-type.
Patients with femoral condyle fractures present with pain, swelling, deformity, rotation, shortening, and an inability to ambulate.
Popliteal artery injury, deep peroneal nerve injury, ipsilateral hip dislocation or fracture, and quadriceps mechanism injury can be associated with femoral condyle fractures.
The tibia is the most commonly fractured long bone.
Patients with tibial spine fractures present with diffuse knee swelling and tenderness, inability to extend the knee, and a positive Lachman’s test.
Anterior tibial spine fractures are 10 times more common than posterior tibial spine fractures.
Patients with tibial tuberosity fractures present with tenderness over the proximal anterior tibia and pain with passive or active extension.
Patients with tibial plateau fractures have pain, swelling, and limited range of motion.
Ligamentous instability can be present in up to one-third of tibial plateau fractures. Injuries to the anterior cruciate and medial collateral ligament are associated with lateral plateau fractures; injuries to the posterior cruciate and lateral collateral ligaments occur with medial plateau fractures.
Patients with tibial shaft fractures present with pain, swelling, and crepitance.
Distal tibial fractures involving the articular surface (tibial plafond or pilon fracture) present with pain, swelling, and tenderness about the ankle.
A thorough neurovascular examination is necessary as the risk of compartment syndrome is high in tibial shaft and tibial plafond fractures.
In patients with tibial plafond fractures, a search for other injuries associated with an axial-loading mechanism, such as vertebral body fractures of the lumbar spine, is indicated.
Proximal fibular fractures may be associated with ankle injuries (Maisonneuve fracture).
Patients with isolated fibular fracture may be able to bear weight.
DIAGNOSIS AND DIFFERENTIAL
Use the Ottawa Knee Rules (Table 176-1) or the Pittsburgh Knee Rules (Fig. 176-1) to determine if radiography is needed for knee injuries. These rules have been validated in both children and adults.
In suspected tibial and fibular injuries, radiographs of the ankle and knee may be necessary to exclude associated fractures.
TABLE 176-1 Ottawa Knee Rules: Radiograph If One Criterion Is Met
Patient age >55 y (rules have been validated for children 2-16 y of age)
Tenderness at the head of the fibula
Isolated tenderness of the patella
Inability to flex knee to 90 degrees
Inability to transfer weight for four steps both immediately after the injury and in the ED
FIG. 176-1. Pittsburgh Knee Rules for radiography. (Reproduced with permission from Seaberg DC, Yealy DM, Lukens T, et al.: Multicenter comparison of two clinical decision rules for the use of radiography in acute, high-risk knee injuries. Ann Emerg Med 32:8;1998. Copyright Elsevier.)
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Table 176-2 describes the mechanism and treatment for the various knee fractures.
Emergency orthopedic consultation is necessary for the majority of tibial fractures. Open fractures, vascular compromise, and compartment syndrome are indications for emergent operative repair.
Patients with tibial fractures may be placed in long-leg immobilization and discharged home if they have a low-energy mechanism, have their pain well controlled, and are not at risk for compartment syndrome.
Proximal fibular fractures associated with ankle injuries require surgical intervention and urgent orthopedic consult.
Treatment for isolated fibular fractures includes splinting, ice, elevation, and orthopedic or primary care physician follow-up. Patients with less pain may only need knee immobilizer or elastic wrap for immobilization and are encouraged to bear weight as tolerated.
TABLE 176-2 Mechanism of Knee Injury and Treatment
DISLOCATIONS
PATHOPHYSIOLOGY
Knee dislocations are a result of high-energy mechanisms, such as falls, motor vehicle crashes, and sporting accidents.
Patellar dislocations are more common in women and result from a twisting injury on an extended knee.
CLINICAL FEATURES
Knee dislocations result in significant ligamentous and capsular disruption.
Anterior dislocation is the most common knee dislocation (40%), followed by posterior dislocations (33%), lateral dislocations (18%), medial dislocations (4%), and rotary dislocations.
Spontaneous reduction occurs in 50% patients with knee dislocation.
Multidirectional instability of the knee should raise suspicion for a spontaneously reduced knee dislocation.
A high incidence of associated injuries to the popliteal artery and peroneal nerve, as well as ligaments and meniscus, exists with knee dislocations.
Patellar dislocations present with pain and deformity over the knee as the patella is displaced over the lateral condyle.
Tearing of the medial joint capsule can occur with patellar dislocations.
DIAGNOSIS AND DIFFERENTIAL
Radiographs are warranted to rule out associated fractures.
Some recommend arteriography for all patients with confirmed knee dislocations.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
For knee dislocations, early reduction is essential along with documentation of pre- and post-reduction neurovascular status.
Immediate orthopedic and vascular surgery consultation is warranted for all confirmed and suspected knee dislocations, and admission is mandatory for observation of neurovascular status. Normal distal pulses do not rule out a popliteal injury.
For patellar dislocations, closed reduction under procedural sedation is indicated. Flexing the hip and hyperextending the knee while sliding the patella back into place will reduce the patella dislocation.
Place patients with patellar dislocations in knee immobilization and refer them to orthopedics or primary care for follow-up in 1 to 2 weeks. Patients may bear weight as tolerated, take NSAIDs, and perform isometric quadriceps strengthening exercises.
TENDON INJURIES
PATHOPHYSIOLOGY
Quadriceps and patellar tendon ruptures result from a forceful contraction on the quadriceps muscle or falling on a flexed knee.
Patients younger than 40 years old with a history of patellar tendonitis or steroid injections are at risk for patellar tendon rupture.
Quadriceps rupture is most commonly seen in patients over 40 years of age.
The Achilles tendon is the strongest and largest tendon in the body.
Achilles tendon rupture occurs when an eccentric force is suddenly applied to the dorsiflexed foot. It is most frequently ruptured at a point 2 to 6 cm above the calcaneous where the vascular supply is weakest.
Middle-aged males with subpar athletic conditioning and patients with history of prior steroid or prior quinolone use are at risk for Achilles tendon rupture.
CLINICAL FEATURES
Patients with quadriceps or patellar tendon rupture have pain and swelling about the knee and will not be able to extend the knee against resistance. A palpable defect is present above or below the knee depending on which tendon is involved.
Patients with an Achilles tendon rupture have severe pain and are unable to perform toe walk, run, or climb stairs. A positive Thompson test (with the patient lying prone and knee flexed at 90 degrees, the foot fails to plantar flex when the calf is squeezed) is diagnostic.
DIAGNOSIS AND DIFFERENTIAL
The diagnosis is largely clinical.
A high riding patella may be seen on the lateral radiograph of the knee with patellar tendon rupture.
Ultrasound or MRI of the Achilles tendon may be useful when the diagnosis is not clear.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Treatment of patellar or quadriceps tendon rupture includes knee immobilization and orthopedic consultation for surgical repair, usually within the first 7 to 10 days after the injury.
Treatment of an Achilles tendon rupture includes splinting in plantar flexion, non-weightbearing, and referral to orthopedics for possible surgical repair.
LIGAMENTOUS AND MENISCAL INJURIES
CLINICAL FEATURES
Most ligamentous injuries present with hemarthrosis, although serious ligamentous injuries may present with little pain and no hemarthrosis due to disruption of the capsule.
Disruption of the anterior cruciate ligament accounts for 75% of all hemarthroses.
Patients with anterior cruciate ligament tears often describe a “pop” and significant swelling over the next several hours after injury.
Lachman’s test is the most sensitive test for ACL injuries. The anterior drawer and pivot shift test are also useful for diagnosis.
Posterior cruciate ligament injuries are less common than ACL injuries and may result in a positive posterior drawer test (55% sensitivity); the composite history and examination findings, however, are more accurate for diagnosis.
Medical and lateral collateral ligament injuries are diagnosed with abduction (valgus) and adduction (varus) stress testing in 30-degree flexion. Laxity greater than 1 cm without a firm end point compared with the other knee is diagnostic for a complete medial or lateral collateral ligament rupture.
Stress testing for collateral ligaments should be repeated with the knee fully extended. If laxity is detected, then injury has occurred to the cruciate ligaments and posterior capsule.
Peroneal nerve injuries can occur in lateral injuries.
Cutting, squatting, and twisting maneuvers can cause injury to the meniscus.
Meniscal injuries often occur in combination with ligamentous injuries.
The medial meniscus is injured more commonly than the lateral meniscus.
Symptoms of meniscal injury include painful locking of the knee; a popping, clicking, or snapping sensation; a sense of instability with activity or joint swelling after activity.
McMurray’s test and other tests for meniscal injury are not sensitive.
DIAGNOSIS AND DIFFERENTIAL
Radiographs are usually normal or show a joint effusion in ligamentous or meniscal injuries.
An avulsion fracture at the site of the lateral capsular ligament on the lateral tibial condyle (Segond fracture) is associated with anterior cruciate ligament rupture.
Outpatient MRI or arthroscopy provides definitive diagnosis.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Treatment for ligamentous and mensical injuries includes knee immobilization, ice, elevation, analge sics, and orthopedic referral.
OVERUSE INJURIES
CLINICAL FEATURES
Patellar tendonitis or “jumper’s knee” presents with pain over the patellar tendon worsened by running up hills or standing from a seated position. Patients have point tenderness over the distal aspect of the patella and proximal patellar tendon.
Patients with shin splints and stress fractures present with activity-induced anterior leg pain initially relieved by rest, but eventually progresses to constant pain. Patients typically describe a change or sudden increase in their training pattern.
DIAGNOSIS AND DIFFERENTIAL
The diagnosis is clinical. Radiographs are usually normal. If a stress fracture is suspected, an outpatient bone scan or MRI can confirm the diagnosis.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Treatment for patellar tendonitis includes heat, NSAIDs, and quadriceps-strengthening exercises. Steroid injections should be avoided.
Discontinuation of the activity is the treatment for both shin splints and stress fractures.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 271, “Knee Injuries,” by Jeffrey N. Glaspy and Mark T. Steele, and Chapter 272, “Leg Injuries,” by Paul R. Halier.