Comparison of Tibial Tubercle Landmark Technique and Range of Motion Technique in Primary Total Knee Arthroplasty: A Retrospective Cohort Study.

Objective: There is not a standard for rotational alignment of the tibial component in total knee arthroplasty (TKA). For now, the most commonly methods are tibial-tubercle -landmark technique (TTL) and range-of-motion technique (ROM). The study is aimed to compare clinical outcomes and radiographic data of patients who undergone primary TKA with TTL or ROM technique.

Methods: This single-surgeon retrospective cohort study includes 60 patients with TTL technique and 60 with ROM technique from December 2017 to January 2019. All patients were evaluated clinically using Hospital for Special Surgery Knee Score (HSS), Feller patellar score, visual analogue scale (VAS) and maximum knee flexion and extension angle before and after surgery at both 6 months and 12 months postoperatively. Radiographic data contain hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), posterior slope angle (PSA) on pre and postoperative X-ray and rotation angle of femoral component (relative to surgical trans-epicondylar axis) and tibial component (relative to surgical trans-epicondylar axis, tibial posterior condylar line and Akagi') on postoperative computed tomography (CT) scan. Clinical outcomes and radiological data were compared between the two groups.

Results: One hundred twenty patients (120 knees) were enrolled in this study, including 38 males and 82 females, aged from 58 to 78, with an average of 65.7 years. There was no significant difference in demographics and preoperative X-ray data between the two groups (P > 0. 05). Clinical scores of the TTL group were better than those in the ROM group at 6 and 12 months after surgery, when comparing HSS (83.57 ± 5.00 vs 75.90 ± 4.89, F = 59.004, P < 0.001; 90.53 ± 4.31 vs 82.83 ± 4.98, F = 54.509, P < 0.001), Feller patellar score (21.43 ± 2.54 vs 19.10 ± 2.52, F = 14.864, P = 0.001; 26.27 ± 1.98 vs 23.20 ± 2.31, F = 42.204, P < 0.001) and VAS (3.70 ± 0.62 vs 4.38 ± 0.92, F = 14.508, P = 0.001; 2.10 ± 0.90 vs 2.79 ± 0.80, F = 11.554, P = 0.002). But there was no significant difference in the flexion and extension angle between the two groups. In imaging evaluation, no statistical difference was found in pre- and postoperative HKA, mLDFA, mMPTA and PSA. Rotational angles of tibial component only did relative to Akagi' have statistical difference in two groups (2.33 ± 4.3 vs 4.41 ± 3.2, t = 2.143, P < 0.05) (Positive value represented external rotation).

Conclusion: The results of our study showed that both methods were reliable, and TTL technique provided better clinical scores and larger external angle of tibial component, compared to ROM technique.