Summary

Tibial tubercule osteotomy in RTKA is an efficient procedure to improve knee exposure, with a high union-rate, despite specific and significant complications.

Abstract

Introduction

Revision Total Knee Arthroplasty (RTKA) is a complex surgery requiring adequate exposure. Tibial tubercle osteotomy (TTO) allows good exposure and reduces the complications' risks on the extensor mechanism. The purpose of this study was: 1) to determine the rates of bone healing, complications, and revisions secondary to TTO; 2) to assess the functional outcomes at mid-term of RTKA with TTO (range of motion and clinical score); 3) to identify the risk factors of TTO failure.

Material & Methods
Between 2010 to 2020, 810 consecutive RTKA were included in a monocentric prospective database. Inclusion criteria of this cohort were all RTKA with a tibial tubercle osteotomy, without extensor mechanism allograft, with at least two years of follow-up. 135 RTKA were included, with a mean age of 65±9 years old [41-94], a mean body mass index of 29.8kg/m²±5.7 [16.8-51.8], and 49% of men. Most frequent indications for revision were: 50% infections (n=68), 25% aseptic loosening (n=34) and 13% stiffness (n=18). The tibial tubercle has been positioned in the same place in 105 patients (77.7%), has been moved proximally in 18 (13%), and medialized in 8 (7%). Bone healing was confirmed on radiographs or CT scan. Complications and revisions were evaluated at the last follow-up. Functional outcomes were assessed using the Knee Society Score (KSS) and range of motion.

Results

The mean follow-up was 51±26 months [24-121]. Bone healing was confirmed for 95% of patients (n=128) after a delay of 3.4±2.7months [1.5-24]. Complication rate was 15% (n=20): 9 fracture of the tibial tubercle (6.7%), 7 non-union (5%), 2 delayed union, 1 tibial metaphyseal fracture, 1 wound dehiscence. Seven patients (5%) required eight revision surgeries (6%): 3 bone grafts of the TTO, 3 osteosyntheses, 1 extensor mechanism allograft, and 1 wound revision. The functional scores and the knee flexion were significantly improved after surgery: KSS knee pre-op 48.8±17 [14-100] versus KSS knee post-op 79.6±20 [29-100] (p<0.001); KSS function pre-op 37.6±21 [0-80] versus KSS function post-op 70.2±30 [0-100] (p<0.001); flexion pre-op 81.5°±33 [0-140] versus post-op 93°±29 [0-140] (p=0.004). 98% (n=132) of patients had no extension deficit. Previous TTO or septic revisions didn’t significantly impact non-union or secondary displacement. No risk factor of failure of the procedure was highlighted.

Conclusions

TTO during RTKA is an efficient procedure to improve knee exposure, with a high bone healing rate, despite significant specific complications. Functional outcomes are improved at mid-term, with a satisfying range of motion.