JUPITER 4.0 - Risk Factors for Failure of Isolated Medial Patellofemoral Ligament Reconstruction

JUPITER 4.0 - Risk Factors for Failure of Isolated Medial Patellofemoral Ligament Reconstruction

The goal of this observational study is to learn about the outcomes of medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent patellar instability. The main questions it aims to answer are:

• What are the risk factors for recurrent patellar instability after MPFL reconstruction?
• What functional outcomes do patients report after MPFL reconstruction?

Participants undergoing MPFL reconstruction will answer survey questions about their knee and activity level 1 year and 2 years after surgery.

The JUPITER group consists of high-volume patellofemoral surgeons across the United States, and was organized to facilitate the collection of clinical and radiographic outcomes following surgical and non-surgical treatment of patellar instability. With this study (JUPITER 4.0), the group aims to prospectively enroll a new cohort of consecutive patients with recurrent patellar instability that would undergo isolated MPFL reconstruction regardless of radiographic measurements or anatomic risk factors to address two specific aims - 1) what patient, injury, and surgical factors lead to recurrent instability following isolated MPFL reconstruction and 2) the creation of an instability severity index score, with the long-term objective of identifying preoperatively, patients with a high risk of failure of an isolated MPFL reconstruction who may be better served with concomitant bony procedure.

Inclusion Criteria:

• 10-35 years old
• Recurrent patellar instability with at least one episode defined as either (1) a dislocated patella requiring reduction in the emergency department or (2) a convincing history for dislocation, associated with full giving way, and the following physical findings: (a) hemarthrosis or effusion, (b) tenderness along the medial retinaculum, and (c) apprehension when laterally directed force was applied to the patella or (3) MRI-documented dislocation with associated bone bruises

Exclusion Criteria:

• Previous ipsilateral knee surgery
• Obligatory/fixed/habitual patella dislocation or subluxation
• Unloadable inferior or lateral chondral damage on the patella that would require a tibial tubercle transfer for unloading purposes
• Pathologic tibiofemoral instability