Abstract
BackgroundNo studies have directly evaluated kinematic changes during squatting before and after bicruciate-stabilized total knee arthroplasty (BCS-TKA) with the dual cam-post mechanism and asymmetric surfaces. This study investigated the effect of BCS-TKA on changes to pre- and postoperative skeletal knee kinematics, to identify factors associated with postoperative skeletal kinematic parameters.MethodsSeventeen knees in 17 patients were prospectively recruited before primary TKA for advanced medial knee osteoarthritis. Subjects underwent BCS-TKA and were evaluated more than 1 year postoperatively. In vivo dynamic skeletal knee kinematics were evaluated using periodic radiographic images collected during squatting to quantify the tibiofemoral functional extension/flexion angle, anteroposterior (AP) translation, and axial rotation angle using image-matching techniques. Rotational alignments of femoral and tibial components were measured postoperatively using computed tomography images.ResultsThe pre- and postoperative tibiofemoral functional extension/flexion angles during squatting were 12.2° ± 6.7°/100.1° ± 16.8° and 9.6° ± 8.6°/109.4° ± 16.8°, respectively, with a significant difference in flexion angle (p < .05). Total AP translation was significantly larger postoperatively than preoperatively (10.8 mm ± 3.7 mm vs. 14.4 mm ± 4.2 mm, respectively; p < .05). The pre- and postoperative total rotation angles were 6.6° ± 3.0° and 6.4° ± 3.7°, respectively, indicating no significant difference. The pre- and postoperative tibiofemoral functional flexion angles were significantly associated with each other (p = .0434, r = .49). The postoperative total rotation angle was significantly smaller when the total component rotational mismatch angle between the femoral and tibial components was above 5° vs. below 5° (4.6° ± 2.7° vs. 8.3° ± 3.9°, respectively; p < .05).ConclusionsBCS-TKA significantly increased the tibiofemoral functional flexion angles, with larger AP translation postoperatively. Both preoperative skeletal kinematics and surgical techniques affected the skeletal kinematics of the replaced knee. A total component rotational mismatch angle greater than 5° significantly decreased postoperative total knee rotation during squatting.
Highlights
No studies have directly evaluated kinematic changes during squatting before and after bicruciatestabilized total knee arthroplasty (BCS-Total knee arthroplasty (TKA)) with the dual cam-post mechanism and asymmetric surfaces
The mean total component rotational mismatch angle was 5.4° ± 4° in all 17 knees, and in nine knees this angle was larger than 5°, indicating malalignment (Table 2)
Secondary aim: pre- and postoperative kinematics and component rotational alignment The pre- and postoperative tibiofemoral functional flexion angles were significantly associated with each other (p = .0434, r = .49)
Summary
No studies have directly evaluated kinematic changes during squatting before and after bicruciatestabilized total knee arthroplasty (BCS-TKA) with the dual cam-post mechanism and asymmetric surfaces. Previous studies revealed that physiological knee kinematics improved functional performance in patients with TKA [3, 4], while non-physiological knee kinematics [5], decreased or paradoxical tibiofemoral anterior-posterior (AP) translation and axial rotation, worsened clinical outcomes after TKA [4, 6]. Bicruciate-stabilized TKA (BCS-TKA) is designed to achieve more physiological kinematics with asymmetrical femoral condyles and tibial baseplate with concave medial and convex lateral polyethylene articular surfaces, and the dual cam-post mechanism by alternating the function of both the anterior and posterior cruciate ligaments [7]. Postoperative rotational kinematics might be significantly affected by preoperative kinematics, as well as by rotational alignment of the tibial component due to the relatively restrictive BCS design
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