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

BACKGROUND

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.

PURPOSE/HYPOTHESIS: 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.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

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 tests were used to compare patellar height indices at different time points.

RESULT

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 ( < .001) and 0.855 ± 0.209 ( < .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 ( < .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.

CONCLUSION

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.