Teilmann Johanne F, Petersen Emil T, Thillemann Theis M, Hemmingsen Chalotte K, Kipp Josephine O, Stilling Maiken
AutoRSA Research Group, Orthopedic Research Unit Aarhus University Hospital Aarhus Denmark.
Department of Clinical Medicine Aarhus University Aarhus Denmark.
J Exp Orthop. 2024 Aug 8;11(3):e12092. doi: 10.1002/jeo2.12092. eCollection 2024 Jul.
Radial head arthroplasty (RHA) reestablishes elbow stability after complex radial head fracture, but complication rates are high, possibly due to inappropriate implant sizing. Knowledge of impact of radial head implant diameter on elbow kinematics is limited and warranted. This study evaluated elbow kinematics of different radial head implant diameters after RHA using dynamic radiostereometric analysis (dRSA).
Eight human donor arms were examined with dRSA during elbow flexion with the forearm in unloaded neutral position, and in supinated- and pronated position without and with 10N either varus or valgus load, respectively. Elbow kinematics were examined before and after RHA with head diameters of anatomical size, -2 mm (undersized), and +2 mm (oversized). The ligaments were kept intact by use of step-cut humerus osteotomy for repeated RHA exchange. Bone models were obtained from CT, and by AutoRSA software bone models were matched with dRSA recordings. The elbow kinematics were described using anatomical coordinate systems.
Compared to the native radial head during elbow flexion, the anatomical sized RHA shifted 2.0 mm in ulnar direction during unloaded pronated forearm position. The undersized RHA shifted 1.5 mm in posterior direction and 2.1 mm in ulnar direction during unloaded pronated forearm position and increased the varus angle by 2.4° during supinated loaded forearm position. The oversized RHA shifted 1.6 mm in radial direction during loaded supinated forearm position.
The anatomically sized RHA should be preferred as it maintained native elbow kinematics the best. The kinematic changes with oversized and undersized RHA diameters were small, suggesting forgiveness for the RHA diameter size.
Level III.
桡骨头置换术（RHA）可在复杂桡骨头骨折后重建肘关节稳定性，但并发症发生率较高，可能是由于植入物尺寸不合适所致。关于桡骨头植入物直径对肘关节运动学影响的了解有限，因此有必要进行研究。本研究使用动态放射立体测量分析（dRSA）评估RHA术后不同桡骨头植入物直径的肘关节运动学。
对8具人体供体手臂进行dRSA检查，检查时前臂处于无负荷中立位，分别在旋前和旋后位，无负荷以及分别施加10N内翻或外翻负荷。在植入解剖尺寸、-2mm（尺寸过小）和+2mm（尺寸过大）的桡骨头前后检查肘关节运动学。通过阶梯状肱骨截骨术保持韧带完整，以便重复进行RHA置换。从CT获得骨模型，并通过AutoRSA软件将骨模型与dRSA记录进行匹配。使用解剖坐标系描述肘关节运动学。
与肘关节屈曲时的天然桡骨头相比，解剖尺寸的RHA在无负荷旋前位时向尺侧移位2.0mm。尺寸过小的RHA在无负荷旋前位时向后移位1.5mm，向尺侧移位2.1mm，在旋后负荷位时内翻角度增加2.4°。尺寸过大的RHA在旋后负荷位时向桡侧移位1.6mm。
应首选解剖尺寸的RHA，因为它能最好地维持天然肘关节运动学。尺寸过大和过小的RHA直径引起的运动学变化较小，表明对RHA直径尺寸有一定宽容度。
III级。
