An isolated rupture of the anterolateral ligament of the knee: A case report

The anterolateral ligament (ALL) is a controversial ligament in the knee that may play a significant role in knee stability. It is difficult to identify on magnetic resonance imaging (MRI) imaging and is often injured in conjunction with other ligaments, such as the anterior cruciate ligament (ACL) and medial collateral ligament. CASE PRESENTATION: This is a unique case of an isolated ALL tear in a 48-year-old woman who presented with severe left knee pain, swelling, and inability to bear weight during a yoga session. Physical examination showed swelling and tenderness at the lateral aspect of the femoral condyle, with increased pain on varus stress testing. Radiographs revealed normal osseous structures with the absence of traumatic bone lesions. MRI revealed an intact meniscus, cruciate, and collateral ligaments, but a rupture of the ALL at its femoral origin. Diagnosis of isolated ALL rupture of the left knee was made, and the patient was treated conservatively with icing, rest, and non-steroidal anti-inflammatory drugs. Physiotherapy was started 2 weeks post-injury, and return to sports was allowed at the sixth week. Upon last follow-up, the patient had excellent functional outcomes and was satisfied with the treatment. Physical examination showed a stable knee with negative Lachman and pivot shift tests. To the best of the authors’ knowledge, this is the first case of isolated ALL rupture to be reported. DISCUSSION: The paper highlights the rarity of isolated ALL injuries and the difficulty in diagnosing them. Conservative treatment can be successful for isolated ALL injuries, with physiotherapy playing an essential role in rehabilitation. In conclusion, isolated ALL injuries are rare and can be challenging to diagnose. Conservative treatment with physiotherapy can lead to successful outcomes. Further research is needed to understand the role of the ALL in knee stability and to determine optimal treatment options.