Excessive femoral torsion is not associated with patellofemoral pain or instability if TKA is functionally aligned and the patella denervated

Abstract

Purpose Recent data suggest that individual morphologic factors should be respected to restore preoperative patellofemoral alignment and thus reduce the likelihood of anterior knee pain. The goal of this study was to investigate the effect of excessive femoral torsion (FT) on clinical outcome of TKA. Methods Patients who underwent TKA and complete preoperative radiographic evaluation including a long-leg radiograph and CT scan were included. 51 patients showed increased FT of > 20° and were matched for age/sex to 51 controls (FT < 20°). Thirteen patients were lost to follow-up. Thirty-eight matched pairs were compared after a 2 year follow-up clinically (Kujala and patellofemoral score for TKA) and radiographically (FT, frontal leg axis, TT-TG, patellar thickness, patellar tilt, and lateral displacement of patella). Functional alignment of TKA was performed (hybrid-technique). All patellae were denervated but no patella was resurfaced. Results There was no significant difference between clinical scores two years after surgery between patients with normal and excessive FT (n.s.). Kujala score was 64.3 ± 16.7 versus 64.8 ± 14.4 (n.s.), and patellofemoral score for TKA was 74.3 ± 21 versus 78.5 ± 20.7 (n.s.) for increased FT group and control group, respectively. There was no correlation between preoperative FT and clinical scores. Other radiographic parameters were similar between both groups. No correlations between clinical outcomes and preoperative/postoperative frontal leg axis or total leg axis correction were found (n.s.). Conclusion If the leg axis deformity is corrected to a roughly neutral alignment during cemented TKA, including patellar denervation, then excessive FT was not associated with patellofemoral pain or instability. Level of evidence. Prospective comparative study, level II.

Widening of tibial resection boundaries increases the rate of femoral component valgus and internal rotation in functionally aligned TKA

“…The most alarming concern that has been raised is the heightened potential to induce patellofemoral maltracking, which remains one of the most frequent complications after TKA and an important contributor to patient dissatisfaction [2,5,27]. Despite the aforementioned dangers associated with femoral component malrotation, an article by Flury et al shows no influence of excessive femoral torsion on patellofemoral pain and instability when the overall alignment remains neutral and denervation of the patella has occurred [8]. A recent study denies the isolated influence of femoral component malrotation on patellofemoral symptoms and patient satisfaction [6].…”