Return to Alta: Patellar Height Increases Over Time After Tibial Tubercle Osteotomy With Distalization

For patients who have patellar instability with patella alta, distalizing the patella via tibial tubercle osteotomy (TTO-d) is one method used to surgically restore stability. Although this procedure is generally associated with favorable outcomes, the effects on maintaining postoperative patellar height remain inadequately understood.

This study aimed to assess changes in patellar height after TTO-d in skeletally mature patients. It was hypothesized that the patella would eventually return to a state of alta after TTO-d.

Case series; Level of evidence, 4.

Skeletally mature patients who underwent a TTO-d procedure with a follow-up lateral knee radiograph at ≥3 months after surgery were included. Caton-Deschamp (CD) and Blackburne-Peele (BP) indices were calculated at various time intervals: preoperative, immediate postoperative, 3-month, 6-month, and ≥1-year follow-up on lateral knee radiographs as available. Paired Student t tests were used to compare patellar height indices at different time points.

A total of 35 knees in 28 patients were included in this study, 20 of which had imaging ≥1 year postoperatively. The mean age of the cohort was 22.3 ± 7.95 years (range, 15.5-43.0 years), mean body mass index was 28.0 ± 7.86, mean tibial tubercle distalization was 10.8 ± 4.83 mm at time of surgery, and mean follow-up using the latest available lateral knee radiographs occurred at 2.83 ± 2.96 years postoperatively. Mean preoperative CD and BP indices were 1.46 ± 0.193 and 1.24 ± 0.196, respectively, which decreased to 1.13 ± 0.189 (P < .001) and 0.855 ± 0.209 (P < .001) on immediate postoperative films. In those with imaging ≥1 year out from surgery, mean CD and BP indices increased to 1.34 ± 0.196 (P < .001) and 1.13 ± 0.131, respectively. Additionally, 88% (15/17) of patients with a minimum 1-year radiographic follow-up transitioned from normal CD and BP indices immediately postoperatively to patella alta at latest follow-up.

Nearly all patients who underwent TTO-d had progressive increases in both CD and BP indices over time, suggesting a return to a state of patella alta over time. Further studies are needed to compare clinical outcomes of patients who have a confirmed return to alta versus those who do not in order to better understand the clinical significance of this observation.