Summary

In this study, we develop a novel method to measure anteriorization following tibial tubercle osteotomy using routine perioperative radiographs, revealing achieved amount of anteriorization is often less than intended.

Abstract

Introduction

There is growing interest in sagittal plane malalignment as a risk factor for patellofemoral chondral wear and a correspondingly important measure to correct when performing certain tibial tubercle osteotomy (TTO) procedures. However, a technique to radiographically measure anteriorization following TTO has not been described. The purpose of this study was to develop and validate a radiographic method of measuring anteriorization following TTO.

Methods

Patients from two high-volume sports medicine surgeons at a single institution who underwent a TTO from 2015-2023 and had both pre- and postoperative radiographic and magnetic resonance imaging (MRI) were identified. Two methods to assess anteriorization following TTO on lateral knee radiographs were developed, using the pre-post difference in distance between the anterior-most aspect of the tibial tubercle and either the center of the tibial shaft or the anterior tibial plateau. To validate the radiographic techniques, agreement was calculated between each method of radiographic measurement and the gold standard MRI measurement (pre-post difference in sagittal tibial tubercle-trochlear groove distance) using intraclass correlation coefficients (ICCs). ICC scores ≥0.75 are considered to represent excellent agreement, 0.6-0.74 good, 0.4-0.59 fair, and <0.4 poor. Anteriorization amounts between techniques were also compared with One-Way Analysis of Variance tests.

Results

There were 70 patients (52 [74%] women) with a mean age of 31.5 ± 9.2 years. The mean anteriorization amount among the 57 anteriorizing TTOs was 4.9 ± 2.5 mm on the XR shaft technique, 4.6 ± 2.6 mm on the XR plateau technique, and 5.3 ± 2.7 mm on MRI (p=0.35). The mean anteriorization amount among the 13 straight distalizing TTOs was 0.1 ± 2.5 mm on the XR shaft technique, -0.3 ± 2.2 mm on the XR plateau technique, and 0.6 ± 2.6 mm on MRI (p=0.66). There was excellent agreement with MRI for both the XR shaft (ICC 0.89) and XR plateau (ICC 0.82) technique. Interrater (ICC=0.94-0.95) and intrarater (0.97-0.98) reliability was excellent for both techniques.

Conclusions

Anteriorization following TTO can be measured using routine pre- and postoperative radiographs. Additionally, the amount of anteriorization achieved with modern TTO techniques was than is traditionally aimed for. Moving forward, surgeons can assess the amount of anteriorization achieved during TTO on standard radiographs, while researchers may investigate the potential role of anteriorization on postoperative outcomes.