Kahlenberg Cynthia A, Berube Erin E, Xiang William, Manzi Joseph E, Jahandar Hamidreza, Chalmers Brian P, Cross Michael B, Mayman David J, Wright Timothy M, Westrich Geoffrey H, Imhauser Carl W, Sculco Peter K
Adult Reconstruction and Joint Replacement Service, Hospital for Special Surgery, New York, New York, USA.
Department of Biomechanics, Hospital for Special Surgery, New York, New York, USA.
Bone Jt Open. 2023 Jun 5;4(6):432-441. doi: 10.1302/2633-1462.46.BJO-2023-0023.R1.
Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model.
We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition.
Mid-level inserts reduced varus angulations compared to PS inserts by a median of 0.4°, 0.9°, and 1.5° at 0°, 30°, and 90° of flexion, respectively, and reduced valgus angulations by a median of 0.3°, 1.0°, and 1.2° (p ≤ 0.027 for all comparisons). Mid-level inserts reduced net IE rotations by a median of 5.6°, 14.7°, and 17.5° at 0°, 30°, and 90°, respectively (p = 0.012). Mid-level inserts reduced anterior tibial translation only at 90° of flexion by a median of 3.0 millimetres (p = 0.036). With an applied varus moment, the mid-level insert decreased LCL force compared to the PS insert at all three flexion angles that were tested (p ≤ 0.036). In contrast, with a valgus moment the mid-level insert did not reduce MCL force. With an applied internal rotation moment, the mid-level insert decreased LCL force at 30° and 90° by a median of 25.7 N and 31.7 N, respectively (p = 0.017 and p = 0.012). With an external rotation moment, the mid-level insert decreased MCL force at 30° and 90° by a median of 45.7 N and 20.0 N, respectively (p ≤ 0.017 for all comparisons). With an applied anterior load, MCL and LCL forces showed no differences between the two inserts at 30° and 90° of flexion.
The mid-level insert used in this study decreased coronal and axial plane laxities compared to the PS insert, but its stabilizing benefit in the sagittal plane was limited. Both mid-level and PS inserts depended on the MCL to resist anterior loads during a simulated clinical exam of anterior laxity.
全膝关节置换术（TKA）的中级约束设计旨在减少冠状面松弛。我们的目的是在模拟膝关节尸体模型临床检查的负荷下，比较Zimmer Biomet Persona后稳定（PS）设计和中级设计在冠状面、矢状面和轴平面上的运动学和韧带力。
我们对8个尸体膝关节进行了TKA，并使用机器人操纵器对其加载。我们通过在0°、30°和90°屈曲时施加内翻和外翻力矩、内外（IE）旋转力矩以及前后力，在模拟临床检查的负荷下测试了PS设计和中级设计。我们测量了由此产生的胫股角度和位移。我们还通过对这些结构进行连续切片并使用叠加原理，量化了内侧和外侧副韧带（MCL/LCL）所承受的力。
与PS植入物相比，中级植入物在0°、30°和90°屈曲时分别使内翻角度中位数减少了0.4°、0.9°和1.5°，使外翻角度中位数减少了0.3°、1.0°和1.2°（所有比较的p≤0.027）。中级植入物在0°、30°和90°时分别使净IE旋转中位数减少了5.6°、14.7°和17.5°（p = 0.012）。中级植入物仅在90°屈曲时使胫骨前移中位数减少了3.0毫米（p = 0.036）。在施加内翻力矩时，与PS植入物相比，中级植入物在所有三个测试屈曲角度下均降低了LCL力（p≤0.036）。相比之下，在施加外翻力矩时，中级植入物并未降低MCL力。在施加内旋力矩时，中级植入物在30°和90°时分别使LCL力中位数降低了25.7 N和31.7 N（p = 0.017和p = 0.012）。在施加外旋力矩时，中级植入物在30°和90°时分别使MCL力中位数降低了45.7 N和20.0 N（所有比较的p≤0.017）。在施加前向负荷时，在30°和90°屈曲时，两种植入物之间的MCL和LCL力没有差异。
与PS植入物相比，本研究中使用的中级植入物降低了冠状面和轴平面的松弛度，但其在矢状面的稳定益处有限。在模拟前向松弛的临床检查中，中级和PS植入物均依赖MCL来抵抗前向负荷。
