Klinikum Stuttgart-Olgahospital, Kriegsbergstr. 62, 70174, Stuttgart, Germany.
Sportklinik Stuttgart Taubenheimstr. 8, 70372, Stuttgart, Germany.
Arch Orthop Trauma Surg. 2019 Aug;139(8):1141-1147. doi: 10.1007/s00402-019-03221-8. Epub 2019 Jun 17.
Correct femoral rotational alignment in total knee arthroplasty (TKA) is important for femoropatellar knee kinematics as well as for the overall clinical success. The goal of the present study was to evaluate how accurately standard instruments of various manufacturers with specific rotational settings in posterior referencing restore the posterior femoral condylar anatomy and allow a rotational alignment which matches a particular anatomic rotational landmark on CT.
The anatomical transepicondylar axis (aTEA) and the posterior condylar line (PCL) were identified and the angle formed by these two axes was measured on 100 consecutive CT scans of knees. A virtual posterior condylar resection was performed relative to the aTEA for femoral sizers of various manufacturers in different external rotations ranging from 3° to 7°. The resections of medial and lateral posterior condyle were calculated as well as the condylar twist angle (CTA) between PCL and aTEA.
The posterior condylar resection varied between 9 mm and 14 mm on the medial side and between 4 mm and 10.5 mm on the lateral side. The mean CTA was 5.5° of internal rotation (SD ± 1.9°). External femoral rotation resulted in increased resection of the medial posterior condyle and decreased resection of the lateral posterior condyle.
Femoral sizers using a posterior referencing technique increase, with rising external rotation, medial posterior condylar resection to an extent that may exceed the implant thickness in the majority of systems. Surgeons should be aware that current standard instruments do not restore the anatomy of the posterior medial and lateral condyle and do not align the femoral component parallel to the aTEA, which may result in internal rotation of a symmetric femoral component.
在全膝关节置换术（TKA）中，正确的股骨旋转对线对于髌股关节的运动学以及整体临床成功至关重要。本研究的目的是评估各种制造商使用特定旋转设置的标准器械在后参照中恢复后股骨髁解剖结构的准确性，并允许旋转对线与 CT 上特定的解剖旋转标志相匹配。
在 100 例连续膝关节 CT 扫描中，确定解剖髁间轴（aTEA）和后髁线（PCL），并测量这两条线之间形成的角度。对于不同制造商的股骨试模，在不同的外旋角度（3°至 7°）下，相对于 aTEA 进行虚拟的后髁切除。计算了内侧和外侧后髁的切除量以及 PCL 和 aTEA 之间的髁间扭转角（CTA）。
内侧后髁的切除量在 9 毫米至 14 毫米之间，外侧后髁的切除量在 4 毫米至 10.5 毫米之间。平均 CTA 为 5.5°内旋（标准差±1.9°）。股骨外旋导致内侧后髁切除量增加，外侧后髁切除量减少。
使用后参照技术的股骨试模随着外旋的增加，内侧后髁的切除量增加，在大多数系统中，可能超过了植入物的厚度。外科医生应该意识到，目前的标准器械无法恢复后内侧和外侧髁的解剖结构，也无法使股骨部件与 aTEA 平行对齐，这可能导致对称股骨部件的内旋。
