Hanson George R, Park Sang E, Suggs Jeremy F, Moynihan Angela L, Nha Kyung W, Freiberg Andrew A, Li Guoan
Department of Orthopaedic Surgery, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, GRJ 1215, Boston, MA 02114, USA.
J Orthop Sci. 2007 Sep;12(5):476-83. doi: 10.1007/s00776-007-1165-7. Epub 2007 Sep 28.
Kneeling is one of the activities sought by patients after total knee arthroplasty (TKA). This study investigated the six degrees of freedom (DOF) kinematics and three-dimensional (3D) contact during weight-bearing kneeling.
A total of 16 South Korean female patients (22 knees) after posteriorly stabilized (PS) TKA (LPS-Flex) were randomly recruited and had the same surgeon. The patients were imaged using a dual fluoroscopic technique while they kneeled from initial to maximum flexion. The acquired images and 3D models were then used to recreate the in vivo pose of the components. Contact was determined by locating the surface intersections in the tibiofemoral and cam/post (between the femoral cam and tibial post) articular compartments.
Patients flexed, on average, from 107.3 degrees to 128.0 degrees during the kneeling activity. Changes in kinematics included 1.0 mm of proximal, 0.9 mm of medial, and 7.6 mm of posterior translation and 1.7 degrees of varus rotation (P < 0.04). A difference in internal tibial rotation was not detected. Articular contact moved posteriorly by 5.9 mm and 6.4 mm in the medial and lateral compartments, respectively. Contact also moved medially by 3.2 mm and 5.8 mm in the medial and lateral compartments. A decrease in articular contact was observed in both condyles, and lateral condylar lift-off increased with flexion (P = 0.0001). More than 80% of the patients demonstrated cam/post engagement, which always occurred in the distal portion of the post.
In this patient cohort, the knee joint was constrained during the weight-bearing activity such that femoral subluxation and dislocation were not observed. Furthermore, posterior cam/post engagement occurred only in the distal portion of the tibial post, which may improve the longevity of the post. The tibiofemoral and cam/post articular contact data presented in this study further suggest that kneeling may be performed by patients after clinically successful PS TKA who feel comfortable with the activity and are free of pain.
屈膝是全膝关节置换术（TKA）后患者所期望的活动之一。本研究调查了负重屈膝过程中的六自由度（DOF）运动学和三维（3D）接触情况。
随机招募了16名接受后稳定型（PS）TKA（LPS - Flex）手术的韩国女性患者（22个膝关节），且由同一位外科医生进行手术。患者在从初始屈膝到最大屈膝的过程中，使用双荧光透视技术进行成像。然后利用获取的图像和3D模型重建组件的体内姿势。通过定位胫股关节和凸轮/柱（股骨凸轮与胫骨柱之间）关节腔中的表面交点来确定接触情况。
在屈膝活动中，患者平均从107.3度屈曲至128.0度。运动学变化包括近端平移1.0毫米、内侧平移0.9毫米、后方平移7.6毫米以及内翻旋转1.7度（P < 0.04）。未检测到胫骨内旋差异。关节接触在内侧和外侧关节腔分别向后移动5.9毫米和6.4毫米。在内侧和外侧关节腔中，接触也分别向内侧移动3.2毫米和5.8毫米。两个髁的关节接触均减少，并且外侧髁抬起随着屈曲增加（P = 0.0001）。超过80%的患者表现出凸轮/柱啮合，且总是发生在柱的远端部分。
在该患者队列中，负重活动期间膝关节受到限制，未观察到股骨半脱位和脱位情况。此外，后方凸轮/柱啮合仅发生在胫骨柱的远端部分，这可能会提高柱的使用寿命。本研究中呈现的胫股关节和凸轮/柱关节接触数据进一步表明，临床上成功接受PS TKA且对该活动感到舒适且无疼痛的患者可以进行屈膝活动。
