Multiligament Knee Reconstruction of the ACL, PLC, and ALL in a Floating Knee: A Case Report

Ipsilateral fracture of the femur and tibia, known by the moniker "floating knee," is a serious injury that primarily results from high-energy trauma. Up to 53% of patients with floating knee injuries have concurrent ligamentous injuries, with the anterior cruciate ligament (ACL) as the most commonly affected ligament. Approximately 10% of multi-ligament knee injuries consist of injuries to both the ACL and posterolateral corner (PLC); however, the literature reporting the management of this patient population is sparse, particularly, with a lack of consensus on the timing and protocol of surgical treatment. Well-characterized treatment guidelines are needed for patients with concomitant floating knee and multi-ligament knee injuries.

A 26-year-old, previously healthy male involved in a high-speed motor vehicle collision presented with upper and lower extremity, skull, and facial fractures, sacropelvic dissociation, and epidural hematoma. Here we describe a rare instance of a floating knee with a multi-ligament knee injury treated through early reconstruction of the ACL, PLC, and anterolateral ligament following stabilization of long bone fractures. Post-injury day 18, the patient underwent single-stage reconstruction of his multi-ligament knee injury. The timing of this was chosen to allow for capsular scar formation to aid in arthroscopy.

Our surgical algorithm consists of allograft reconstruction using an all-inside ACL technique and a modified anatomical PLC technique. We recommend early (1-3 weeks) surgical treatment of multi-ligament knee injuries for patients without a closed head injury; however, an individualized treatment approach should be sought, considering the severity of ligamentous injuries, pre-injury activity level, extent of soft-tissue damage, and the activity goals of the patient post-injury. In patients with floating knee injuries, the proposed surgical algorithm here may be utilized for successful multi-ligament knee injury reconstruction.