FRCS EMQs: Knee

Clinical Rationale: Quadriceps active test.

Clinical Rationale: Lachman test.

Clinical Rationale: Pivot shift test. As with most joints, the knee has a number of special examination tests beyond the look, feel and move. Lachman, anterior drawer and pivot shift all assess anterior cruciate deficiency, and the Lachman test is the most sensitive. The pivot shift relies on an intact medial complex and an intact iliotibial band; with the initial valgus and internal rotation force the tibia will be anterolaterally subluxed on the distal femur; with flexion, the iliotibial band goes from an extender to a flexor of the knee and the tibial anterolateral subluxation reduces. Clark’s test, apprehension test and J sign refer to the patellofemoral joint. McMurray and Apley’s tests are to detect meniscal pathology. The dial test is for posterolateral corner (PLC) injuries; this is carried out prone with the knee at 30
and 90
; in an isolated PLC injury, there is increased external rotation at 30
and to a lesser extent at 90
. In a combined PLC and posterior cruciate ligament (PCL) injury there is further increased external rotation at 90
compared to 30
. The quadriceps active test is positive in PCL injury.

Clinical Rationale: Medial patellofemoral ligament tear.

Clinical Rationale: Knee dislocation.

Clinical Rationale: Bucket handle tear of the medial meniscus. More often than not the history of the mechanism of injury is sufficient to establish the diagnosis. The first case is a likely patellar dislocation with associated osteochondral fracture of the lateral femoral condyle (often on reduction of the patella), and the additional injury is a tear of the medial patellofemoral ligament. The second case is a likely knee dislocation with rupture of the anterior and posterior cruciate ligaments. In addition the medial collateral ligament or lateral collateral ligament/posterolateral corner would need to be injured as well for the knee to dislocate. Common peroneal nerve (25%) and vascular (30%) injury are commonly associated. The third case describes a previous anterior cruciate ligament injury, with a valgus/external rotation force, which has not been treated. The subsequent loading on the medial meniscus has resulted in a bucket handle tear following a twist, resulting in a locked knee (reduced range of motion). Posterior cruciate ligament tears occur after a direct force to the proximal tibia with flexed knee (e.g. dashboard injury) or in hyperflexion with plantarflexed foot.