Radiographic and Clinical Outcomes After Tibial Tubercle Osteotomy for the Treatment of Patella Alta: A Systematic Review and Meta-analysis

Abstract

Background: Patella alta is a known risk factor for patellar instability and, in the setting of recurrent patellar instability with significant patella alta, correction of patellar height with a tibial tubercle osteotomy (TTO) may help decrease the failure of soft tissue-based stabilization.

Purpose: To perform a systematic review and meta-analysis of radiographic and clinical outcomes after TTO for patella alta.

Study design: Systematic review and meta-analysis; Level of evidence, 4.

Methods: PubMed, OVID/Medline, and Cochrane databases were queried in June 2020 for studies reporting outcomes of TTO for patella alta. Data pertaining to study characteristics and design, radiographic and clinical outcome values, and incidence of complications and reoperations were extracted. DerSimonian-Laird continuous and binary random-effects models were constructed to (1) perform subgroup-based analysis of mean changes in radiographic indices after TTO and (2) quantify the pooled incidence of complications and reoperations.

Results: Eight studies including 340 patients (420 knees) with a mean age of 24.7 ± 8.4 years were included. The mean follow-up was 53.1 months (range, 3-120 months), with 1 study reporting a mean follow-up of less than 2 years. The pooled mean anterior transfer was 5.6 mm; the mean medial transfer was 8.7 ± 1.3 mm; and the pooled mean distalization of the tibial tubercle was 12.2 ± 4.5 mm. Continuous random-effects meta-analysis determined that significant reductions in the mean Insall-Salvati ratio (1.40 vs 0.98, P < .001), Caton-Deschamps index (1.26 vs 0.97, P < .001), and tibial tubercle to trochlear groove ratio (18.27 vs 10.69, P < .001) were observed after TTO. The overall incidence of complications was 7.6% (95% CI, 4.8%-10.5%), while the overall incidence of reoperations was 14.3% (95% CI 6.2%-22.4%).

Conclusion: TTO for patellar instability in the setting of patella alta results in a significant decrease in patellar height with varying degrees of medialization depending on the utilized technique. A mean postoperative complication rate of 7.6% was reported with a reoperation incidence of 14.3%, related primarily to hardware removal.

Keywords: distalization; knee; meta-analysis; osteotomy; patella alta; tibial tubercle.