Evaluating the Impact of Tibial Tubercle Osteotomy in Adult Patients on Patellar Height and Patellar Tendon Length.

Background: Patellar height (PH) constitutes an important component of patellofemoral biomechanics. Iatrogenic decrease in PH after knee procedures has been demonstrated for arthroplasty and high tibial osteotomy, among others. However, alterations in PH resulting from tibial tubercle osteotomy (TTO) have yet to be described.

Purpose/hypothesis: This study aimed to compare pre- and postoperative PH ratios and patellar tendon length (PL) in adult patients who have received an anteromedialization or medialization TTO. The authors hypothesized that TTO would result in PH alterations with trends toward patella baja.

Study design: Case series; Level of evidence, 4.

Methods: This was a retrospective review of adult patients receiving primary TTO +/- medial patellofemoral ligament reconstruction from 2013 to 2020. All patients had a minimum 6-month radiographic follow-up. Pre- and postoperative PH measurements were assessed with the Blackburne-Peel Index (BPI), Caton-Deschamps Index (CDI), Insall-Salvati Ratio (ISR), and PL. Paired t tests were performed for each measurement index comparing pre- and postoperative radiographs.

Results: A total of 42 patients (64% women), with a mean age of 26.5 years (range, 18-51 years) and a mean radiographic follow-up of 19 months (6 -110 months) met the inclusion criteria. The mean preoperative PH using the BPI, CDI, and ISR were 0.99 ± 0.239, 1.20 ± 0.240, and 1.29 ± 0.206, respectively. The mean preoperative PL was 54.52 ± 7.23 mm. The mean postoperative PH using the BPI, CDI, and ISR were 0.95 ± 0.24, 1.16 ± 0.21, and 1.20 ± 0.19, respectively. The mean postoperative PL was 52.79 ± 7.25 mm. The mean differences between the pre- and postoperative were as follows: BPI: 0.04; CDI: 0.04; ISR: 0.08; and PL: 1.73 mm, none of which were statistically significant.

Conclusion: While changes were observed in approximately 50% of patients, there were no statistically significant, nor predictable, alterations in PH after TTO using the BPI, CDI, ISR, or PL measurements at a minimum 6-month follow-up. Further large-scale studies are needed to determine the reliability of these PH findings and whether the changes are clinically impactful on surgeon decision-making and patient outcomes.