Pediatric and Adolescent Patellar Instability (PAPI)

This is a multi-center, randomized controlled clinical trial, the purpose of which is to determine if patients age 25 and younger who undergo medial patellofemoral ligament (MPFL) reconstruction have lower rates of recurrent instability compared to those treated non-operatively. The MPFL is a ligament that stabilizes the kneecap, and maintains its proper position in the groove on the femur (thighbone). Instability refers to a situation in which the kneecap moves out of place, or dislocates. When instability is recurrent, it occurs more than once in the same knee.

Study Overview

• Status: Enrolling by invitation
• Conditions: Patellar Instability
• Intervention / Treatment: Procedure: Medial patellofemoral ligament reconstruction surgery; Other: Physical therapy and rehabilitation

Detailed Description

A total of 240 patients will be enrolled across participating sites around the country. These sites currently include: The Hospital for Special Surgery, Oregon Health and Science University, Inova Sports Medicine, and Mayo Clinic. Patients are randomly assigned to one of two treatment groups. Patients assigned to the "stabilization" group will undergo surgery to reconstruct the MPFL using either a hamstring tendon that is your own or one obtained from a donor. Patients assigned to the "conservative" group will be treated with physical therapy, and possibly a simple knee arthroscopy if you are found to have a loose fragment on x-ray or MRI. All patients will be required to return for follow-up visits, which will continue over the course of 5 years. During these visits, patients will be examined, asked to answer questions about their surgery and general health, and have imaging (x-ray and MRI) performed on the knee. All patients enrolled in this study will undergo a standardized, intensive rehabilitation protocol. The investigators anticipate that all patients may benefit from extensive rehabilitation, including strengthening and return to sport training. The knowledge gained from this study may benefit others in the future.

• Study Type: Interventional
• Enrollment (Estimated): 240
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 8 years to 25 years (Child, Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients must be age 25 or younger
• Patients must be first-time dislocators, meaning have had only one episode of patellar instability, during which they dislocated their patella (kneecap)

Exclusion Criteria:

• Patients with more than one episode of patellofemoral instability
• Patients who have had prior patellofemoral surgery on the knee of interest
• Patients with large cartilage tears in the knee. These patients will undergo stabilization of the patellofemoral joint (MPFL reconstruction) as per standard of care, and will not be included in the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Surgical Intervention; The surgical intervention to be studied in this arm is medial patellofemoral ligament reconstruction surgery using hamstring tendon. The tendon used will generally consist of autograft semitendinosus. If the hamstrings have been previously harvested or injured (i.e. in the setting of anterior cruciate ligament reconstruction or proximal tibial surgery), or if the patient/his or her family prefers to minimize donor site morbidity, allograft may be used.	Procedure: Medial patellofemoral ligament reconstruction surgery; Medial patellofemoral ligament reconstruction surgery using hamstring autograft; Other Names: CPT code: 27427
Other: Conservative treatment; The intervention to be studied in this arm is a rehabilitation program directed by physical therapists. If patients in this arm are found to have a small loose body, a simple arthroscopy will be performed to remove the loose body, but no stabilization of the patellofemoral joint will be performed. The rehabilitation program will be compiled into a booklet and distributed for use by the physical therapist chosen by the patient.	Other: Physical therapy and rehabilitation; A standardized physical therapy and rehabilitation program to be administered and guided by rehab specialists

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recurrence of patellar instability	The primary outcome is recurrent episode of patellar instability within 5 years following the primary patellofemoral dislocation event. A preliminary analysis will be performed at 2 years to examine for any early results of the study. Patellar instability will be defined as any patient-reported episode of subluxation or dislocation following the index event. Subluxation or dislocation will be defined as a feeling of dissociation of the patella from its trochlear groove. Subluxation will be noted if the patella spontaneously reduces into the groove, and dislocation will be noted if the patella requires any change in position or force (i.e. extending the knee or exerting a medially-directed force on the patella) in order to reduce into its trochlear groove. (Apprehension will not be classified as subluxation unless the patient specifically notes a sensation of departure of the patella from its trochlear groove at some point during the experience.)	5 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Kujala Scoring Questionnaire	The Kujala Scoring Questionnaire is a validated patient reported outcome measure	Preoperatively and at 1 year, 2 years, 3 years, 4 years, and 5 years after treatment.
Knee Injury and Osteoarthritis Outcome Score (KOOS)	The KOOS is a validated patient reported outcome measure	Preoperatively and at 1 year, 2 years, 3 years, 4 years, and 5 years after treatment.
International Knee Documentation Committee (IKDC) Subjective Knee Evaluation	The IKDC Subjective Knee Evaluation is a validated patient reported outcome measure	Preoperatively and at 1 year, 2 years, 3 years, 4 years, and 5 years after treatment.
Hospital for Special Surgery Pediatric Functional Activity Brief Scale	The Hospital for Special Surgery Pediatric Functional Activity Brief Scale is a validated patient reported outcome measure	Preoperatively and at 1 year, 2 years, 3 years, 4 years, and 5 years after treatment.
Outerbridge grade of any cartilage lesions	Outerbridge grade will be used to describe the severity of articular cartilage lesions at initial presentation and for surgical patients, 1 and 5 years after treatment as well	MRI taken at initial exam, and for patients randomized to surgery only at 1 year and 5 years after surgery as well

Collaborators and Investigators

• Sponsor: Hospital for Special Surgery, New York
• Collaborators: Mayo Clinic; Oregon Health and Science University; Inova Medical Group
• Investigators: Principal Investigator: Beth E Shubin Stein, MD, Hospital for Special Surgery, New York; Study Chair: Jacqueline Munch, MD, Oregon Health and Science University Hospital; Study Chair: Diane Dahm, MD, Mayo Clinic; Study Chair: Robin V West, MD, Inova Sports Medicine

Publications and helpful links

Helpful Links

• Principle Investigator: Beth Shubin Stein, MD

Study record dates

Study Major Dates

• Study Start: December 1, 2015
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: December 12, 2014
• First Submitted That Met QC Criteria: January 5, 2015
• First Posted (Estimated): January 7, 2015

Study Record Updates

• Last Update Posted (Actual): February 13, 2026
• Last Update Submitted That Met QC Criteria: February 11, 2026
• Last Verified: February 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Therapeutics; Patient Care; Health Services; Health Care Facilities Workforce and Services; Aftercare; Continuity of Patient Care; Rehabilitation; Physical Therapy Modalities
• Other Study ID Numbers: 2014-087