An observational study in Patellar Dislocation, Recurrent, Patellar Dislocation and Patellar Instability, sponsored by Hospital for Special Surgery, New York. Recruiting at 16 sites in United States. Open to participants aged 10 Years to 35 Years. Per ClinicalTrials.gov, last updated 2026-02-13.
Sponsored by Hospital for Special Surgery, New York · Observational
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:
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.
41 studies on the registry are indexed under Patellar Dislocation; 9 are open to participants now.
This study's planned enrollment of 850 is above the median of 100 across 15 observational studies indexed under Patellar Dislocation.
Browse Patellar Dislocation studies →Hospital for Special Surgery, New York is the lead sponsor of 226 studies on the registry; 40 are open to participants now.
Of its 30 completed or terminated interventional studies of FDA-regulated products, 22 (73%) have results posted.
Counted across the registry records on this site, refreshed daily.
Patients presenting to the participating surgeons for treatment of recurrent patellar instability
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Patients with recurrent patellar instability (2 or more dislocation and/or subluxation events) undergoing isolated MPFL reconstruction
Procedure: Medial Patellofemoral Ligament (MPFL) Reconstruction
For the purposes of this study, isolated MPFL reconstruction is defined as MPFL reconstruction with a tendon graft, with or without additional soft tissue procedure(s) including lateral retinacular lengthening or release, patellofemoral chondroplasty and/or cartilage restoration. No patient in the study will receive a bony realignment procedure to treat patellar instability.
Recurrent patellar instability
Patient-reported patellar dislocation or subluxation
Time frame: Within 24 months post-operatively
Patient-Reported Outcome Measures (PROMs): Kujala score
The Kujala score, also known as the Anterior Knee Pain Scale (AKPS), is a 13-item questionnaire that helps assess subjective reactions to activities and symptoms related to patellofemoral pain. It is a 0-to-100 point scale, with higher scores indicating better outcomes and less pain and disability.
Time frame: 12 months post-operatively and 24 months post-operatively
Patient-Reported Outcome Measures (PROMs): Pedi-IKDC
The Pedi-IDKC is a modified version of the International Knee Documentation Committee (IDKC) Subjective Knee Form for use in young patients. It is a 15-item knee-specific questionnaire that measures symptoms, function, and sports activity. Scores range from 0-100, with higher scores indicating better outcomes.
Time frame: 12 months post-operatively and 24 months post-operatively
Patient-Reported Outcome Measures (PROMs): HSS Pedi-FABS
The Hospital for Special Surgery Pediatric Functional Activity Brief Scale (HSS Pedi-FABS) is a validated 8-item questionnaire scored from 0-30, with higher scores indicating higher levels of activity.
Time frame: 12 months post-operatively and 24 months post-operatively
Patient-Reported Outcome Measures (PROMs): KOOS-12
The Knee injury and Osteoarthritis Outcome Score-12 (KOOS-12) is a 12-item measure evaluating the difficulties people experience due to problems with their knee. Each question is scored from 0 to 4 points, with 0 representing no knee problems and 4 representing extreme knee problems. Overall, scores range from 0 to 100, where, in contrast to the individual questions, 0 is the worst possible and 100 is the best possible score.
Time frame: Time Frame: 12 months post-operatively and 24 months post-operatively
Patient-Reported Outcome Measures (PROMs): BPII 2.0
The BPII 2.0 (Banff Patellofemoral Instability Instrument) is a patient-reported outcome measure assessing quality of life in individuals with patellofemoral instability. The score ranges from 0 to 100, with higher scores indicating greater quality of life.
Time frame: 12 months post-operatively and 24 months post-operatively
Patient-Reported Outcome Measures (PROMs): PROMIS-29
PROMIS (Patient-Reported Outcomes Measurement Information System) is a questionnaire that evaluates health-related quality of life across seven key domains: physical function, pain interference, fatigue, sleep disturbance, physical and mental health, and social health. It is scored a T-score metric. High scores mean more of the concept being measured. 10 points on the T-score metric is one standard deviation (SD).
Time frame: 12 months post-operatively and 24 months post-operatively
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Hospital for Special Surgery, New York →