Anterior Cruciate Ligament Rupture with Concurrent Gastrocnemius Tear: A Case Report of a Rare Pattern of Injury.

Background, Clinical Significance: Anterior cruciate ligament (ACL) injuries are common, however the occurrence of concurrent gastrocnemius muscle tears is exceptionally rare. Given this, the diagnosis and management of this pattern of injury is poorly characterised, with lack of current clinically relevant classification systems and evidence-based guidelines to guide treatment. Early recognition is essential. with advanced imaging critical to guiding the diagnosis and management of patients with this pattern of injury. Case presentation: A 39 year old man presented with acute right knee swelling, pain and difficulty weightbearing following a sports-related fall. Clinical examination was suspicious for an ACL injury. Magnetic Resonance Imaging (MRI) of the knee demonstrated the disrupted and displaced ACL fibres, with extensive peri-cruciate oedema around the expected position of the ACL. It was associated with partial avulsion of the medial gastrocnemius origin and incomplete avulsion of the lateral gastrocnemius origin. The patient was referred for an urgent orthopaedics review and is currently on trial of conservative management. Conclusions: In this case report and review of the literature, we evaluate the current understanding of the complexities of combined musculoskeletal injuries and limitations of existing classifications in providing accurate diagnosis and management strategies. Given the rarity of this presentation, the case underscores the lack of evidence-based recommendations for early management, particularly in young, active individuals who are at risk of significant long-term functional impact.