Isolated Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability Regardless of Tibial Tubercle–Trochlear Groove Distance and Patellar Height: Minimum 5-Year Outcomes

• Published in: The American journal of sports medicine Vol. 52; no. 9; pp. 2196 - 2204
• Main Authors: Dennis, Elizabeth R., Marmor, William A., Propp, Bennett E., Erickson, Brandon J., Gruber, Simone, Brady, Jacqueline M., Nguyen, Joseph T., Shubin Stein, Beth E.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-07-2024; Sage Publications Ltd
• Subjects: Adolescent; Adult; Female; Humans; Joint Instability - surgery; Knee; Ligaments, Articular - surgery; Male; Patella - surgery; Patellofemoral Joint - surgery; Patient Reported Outcome Measures; Prospective Studies; Recurrence; Return to Sport; Tibia - surgery; Young Adult; MPFL reconstruction; patella alta; patellofemoral instability; tibial tubercle osteotomy; TT-TG; trochlear dysplasia
• ISSN: 0363-5465; 1552-3365; 1552-3365
• DOI: 10.1177/03635465241260039

Background:
It remains unclear which subset of patients with recurrent patellofemoral instability would benefit from a concomitant bony realignment procedure in addition to a medial patellofemoral ligament (MPFL) reconstruction.
Purpose:
To provide midterm results for patients who underwent an isolated MPFL reconstruction as part of an ongoing prospective trial.
Study Design:
Case series; Level of evidence, 4.
Methods:
Patients with recurrent patellar instability were prospectively enrolled in an institutional registry beginning in March 2014. Exclusion criteria included history of a previous surgery for patellar instability, an off-loadable (inferior/lateral) chondral defect, anterior knee pain ≥50% of their chief complaint, and a “jumping J” sign. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of their bony anatomic characteristics. Patient-reported outcome measures (PROMs), episodes of recurrent instability, and ability to return to sport were obtained annually. Radiographic measurements of baseline radiographs and MRI were obtained at baseline.
Results:
A total of 138 patients underwent isolated MPFL reconstruction between March 2014 and December 2019. The mean radiographic measurements were tibial tubercle–trochlear groove, 15.1 ± 4.9 mm; Caton-Deschamps index, 1.14 ± 0.16; patellar trochlear index, 46.9% ± 15.1%; trochlear depth index, 2.5 ± 1.2 mm; tibial tubercle to lateral trochlear ridge, −8.4 ± 5.7 mm; and patellar tendon to lateral trochlear ridge, 5.7 ± 6.2 mm. Trochlear dysplasia, defined as a trochlear depth index <3 mm, was present in 79/125 (63%) patients. A total of 50 patients reached ≥5 years, of whom 40 (80%) completed follow-up PROMs. A total of 119 patients reached ≥2 years, of whom 89 (75%) completed follow-up PROMs. Six patients (5%) reported recurrent instability with a mean time of 2.97 years after surgery. All PROMs improved over time except for the Pediatric Functional Activity Brief Scale (Pedi-FABS), which had no change. At 2 years, the mean changes from baseline for Knee injury and Osteoarthritis Outcome Score (KOOS) Quality of Life subscale (QOL), Pedi-FABS, International Knee Documentation Committee (IKDC) score, KOOS Physical Function Short Form (PS), and Kujala score were 42.1, 0.6, 35.1, –23.5, and 32.3, respectively. All changes had P values <.001 except for Pedi-FABS, which showed no change and had P > .999. At 5 years, the mean changes from baseline for KOOS-QOL, Pedi-FABS, IKDC, KOOS-PS, and Kujala score were 42.6, –2.8, 32.6, –21.5, and 31.6, respectively. All changes had P values <.001 except for Pedi-FABS, which showed no change and had P > .453. In total, 89% of patients returned to sport with a mean of 9.1 months.
Conclusion:
Midterm outcomes for patients who underwent isolated MPFL reconstruction were favorable and were maintained at 5 years. Outcomes for the expanded cohort of patients with a minimum 2-year follow-up support previously published results.