Primary care physicians are often the first to see patient's who present with acute knee injuries. Various knee injuries present with the symptoms: pain, swelling, instability. However, a systematic examination and radiographic series enable physicians to isolate the pathology and determine the extent of injury. Once incorporated into everyday practice, the emphasis of the exam will shift depending on the specific injury. Arthroscopy is not usually needed for initial diagnosis.
Though pain and swelling, and instability can suggest one of many acute knee injuries, a system method for evaluation can help primary care physicians pinpoint the injury on the initial exam. Sophisticated evaluation techniques are not always needed. A complete history, physical exam with thorough palpation, tests to evaluate ligament function, and a standard radiographic series can usually provide enough information to specifically diagnose the patients injury in the office.
A first step in evaluating an acute knee injury is to establish whether the patient has had a past knee injury. Some examples include patellar instability with recurrent subluxation or dislocation, ACL insufficiency with recurrent giving way, and meniscal tear with recurrent locking.
Some examples of Anterior Cruciate Ligament tests:
The Lachman test- In the Lachman test for the ACL injuries, the examiner flexes the patient's knee to 30 degree's, grasping the proximal tibia with one hand and supporting the femur with the other. The tibia is then pulled anteriorly. Complete rupture of the ACL results in a notable increase in translation without a firm end point. Increased translation with an end point suggests a partial rupture of the ACL or an injury to the posterior cruciate ligament.
The Anterior Drawer test- The anterior drawer test assesses the ACL and, more specifically, the Posterior Cruciate Ligament. To perform the maneuver, the patient's knee is flexed as close to 90 degree's as possible. After anchoring the patient's foot, the examiner grasps the proximal tibia with both hands, pulls it forward, then pushes it back. The amount of excursion and end point quality is noted and compared to the other leg.
Valgus and Varus Stress tests- Valgus and varus stress tests evaluate the medial and lateral collateral ligaments. The tests are performed at 30 degree's of knee flexion and at full extension. The examiner notes the amount of opening at the joint line as well as the presence of an end point.