The physical examination of the knee begins with assessing for abrasions, lacerations, previous surgical scars, and the presence of significant intra-articular or lower extremity swelling. A careful neurovascular examination to detect pulse asymmetry and distal motor or sensory deficits is performed, and concern for arterial injury should prompt urgent evaluation with noninvasive vascular studies (ankle-brachial indexes [ABIs]), computed tomography (CT) angiography, or popliteal arterial angiography.³ Characterization of the pattern of ligamentous instability is performed with an evaluation of patellar stability and Lachman, anterior and posterior drawer, and varus and valgus testing at full knee extension and 30 degrees of flexion. Additional rotatory testing including a dial test and evaluation of posteromedial and posterolateral rotatory instability is performed as indicated. It is important to evaluate clinical laxity with the tibiofemoral joint initially reduced, because abnormal positioning of the joint may lead to overestimation or underestimation of tibial translations, especially during posterior drawer or rotatory testing. Comparison with the contralateral extremity allows detection of subtle clinical laxities, although swelling, pain, and guarding may interfere with the ability to accurately identify and grade ligament injuries. We grade all injuries with the International Knee Documentation Committee (IKDC) standard clinical laxity scale (grade 1, 3 to 5 mm; grade 2, 5 to 10 mm; grade 3, more than 10 mm). By definition, a partial ligamentous injury is categorized as grade 1+ or 2+, and a complete tear as grade 3+.⁴

We obtain standard radiographs of both knees in all patients to evaluate for fracture, associated arthritis, and joint reduction. The presence of subtle findings including avulsion fracture, joint subluxation, and patellar height is also assessed. Magnetic resonance imaging (MRI) assists in the grading of ligamentous injuries and identification of pathology of the menisci, chondral surfaces, and related structures.⁵ The MRI findings are reviewed with the direct input of our musculoskeletal radiology colleagues before an individualized treatment plan is established.

Acute surgical indications include vascular injuries requiring intervention, open or irreducible knee dislocation, and compartment syndrome. We previously reported on performance of ligamentous repair or reconstruction within 1 to 3 weeks of injury,4,6 although we now prefer delaying surgery to allow for resolution of the acute inflammatory phase of injury (i.e., swelling), interval healing of previous surgical interventions (e.g., vascular repair, fasciotomy), restoration of knee range of motion (ROM), and the return of quadriceps motor control. Relative indications for acute surgical intervention (within 14 days) in our hands include grade 3 PLC avulsions and displaced longitudinal meniscal tears; anatomic repair can be performed before the onset of significant scarring or retraction. Primary cruciate ligament reconstruction can be deferred for 6 to 8 weeks with frequent clinical evaluation to assess the pattern of ligamentous instability and detection of factors including deep vein thrombosis (DVT) or wound complications. A detailed discussion of the diagnosis, the treatment options and alternatives, and the risks and complications of surgical intervention is performed before surgical consent is obtained and the procedure is begun.