Outcomes of Medial Patellofemoral Ligament Reconstruction With Concomitant Tibial Tubercle Osteotomy for Failed Surgery for Patellar Instability Versus Primary Medial Patellofemoral Ligament Reconstruction With Concomitant Tibial Tubercle Osteotomy

Abstract

Background:

Management of patellofemoral instability is complex. It is not known whether the outcomes of medial patellofemoral ligament reconstruction (MPFL) with concomitant tibial tubercle osteotomy (TTO) performed in the revision setting after a failed surgery for patellar instability equal the outcomes of an MPFL-Reconstruction +TTO performed as a primary procedure.

Hypothesis:

Both groups would have low recurrent instability rates, significantly improved subjective outcomes, and return to sport (RTS) percentages equivalent to or higher than those currently established in the literature. Additionally, we hypothesized that the revision group would have poorer subjective outcomes postoperatively compared with the primary surgery group.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A retrospective review of data from March 2014 to December 2018 was conducted for analysis. The inclusion criteria were surgical stabilization with combined MPFL-Reconstruction +TTO performed as either a primary or revision procedure. Instability events included both dislocations and subluxations and were based on patient reports, physical examination, and magnetic resonance imaging (MRI) findings. Patients were included in the revision group if they had undergone previous surgical intervention for patellar instability. Patients were excluded if they lacked baseline patient-reported outcome measures (PROM) or had a concomitant distal femoral osteotomy at the time of their index patellofemoral surgery. Patients were separated into 2 groups: MPFL-Reconstructiom + TTO as a primary procedure, and those who underwent MPFL-Reconstruction + TTO after a previously failed surgical attempt for patellar stabilization. Standard knee radiographs and MRIs were obtained preoperatively in all patients. Radiographic measurements included the Caton-Dechamps index (CDI), patellar trochlear index (PTI),⁴ tibial tubercle-trochlear groove distance (TT-TG), patellar tendon-lateral trochlear ridge (PT-LTR),²⁰ and trochlear depth index (TDI). Evaluation of subjective measures included several knee-specific PROMs, collected pre- and postoperatively at 1 and 2 years. These PROMs included the Knee injury and Osteoarthritis Outcome Score–Quality of Life (KOOS-QoL), KOOS–Physical Function Short Form (KOOS-PS), International Knee Documentation Committee (IKDC), subjective knee form, Kujala Knee Score, and Pediatric Functional Activity Brief Scale (Pedi-FABS). Episodes of recurrent instability and patients’ ability to RTS were documented at each postoperative visit and yearly with subjective outcome assessments.

Results:

A total of 58 knees (51 patients) underwent primary surgery, and 33 knees (32 patients) underwent revision surgery, of which 90% and 88% had at least a 2-year follow-up, respectively. There was no difference between groups in patient characteristics—including age (23.8 vs 22.5; P = .442), sex (85% vs 82%; P = .742), or body mass index (28% vs 16%; P = .176). Concomitant cartilage restoration procedures were performed in one-third of patients in each group (34% vs 33%; P = .911) and included both particulated juvenile articular cartilage and osteochondral grafting of the patellofemoral joint. Recurrent instability did not occur in the revision group, whereas it occurred at a rate of 7% in the primary group. The primary surgery group had an RTS rate of 88%, compared with 83% in the revision group, but the difference was not statistically significant. Significant gains were seen in both patient cohorts from baseline to 1-year follow-up, with outcome scores sustained at 2-year follow-up. Initial stratified analysis of patients who had concomitant articular cartilage procedures found no effect on outcome scores in either group over time.

Conclusion:

This study demonstrates that MPFL-Reconstruction + TTO is a reliable and reproducible procedure whether performed in the primary or revision setting. Patients who had primary and revision surgery reported clinical and statistical improvements in nearly all PROMs over time, with low recurrent instability and high RTS rates in both groups.