The mobile Oxford unicompartmental knee arthroplasty (UKA) implant has been widely used with an intramedullary guide for femoral preparation. We modified the femoral guide technique based on the tibial cut first and spacer block technique. This study was performed to determine the radiographic accuracy and early clinical outcomes of the extramedullary method. We retrospectively evaluated 50 consecutive patients who underwent UKA using the extramedullary technique. An equal number of patients who underwent UKA with the conventional technique were matched as the control group. Clinical outcomes were evaluated in terms of the operating time, blood loss, range of motion, and Hospital for Special Surgery score. Radiographic accuracy was evaluated by the implant position and alignment in the coronal and sagittal planes. The mean follow-up period was 39.76 ± 5.77 months. There were no differences in the postoperative Hospital for Special Surgery score, range of motion, or hip-knee-ankle angle between the two groups. The operating time in the extramedullary group was shorter than that in the conventional group (54.78 ± 7.95 vs. 59.14 ± 10.91 min, respectively; p = 0.025). The drop in hemoglobin after 3 days was only 12.34 ± 4.98 g/L in the extramedullary group which was less than that in the conventional group (p = 0.001). No significant differences were found in the postoperative coronal and sagittal angles between the two groups. Acceptable radiographic accuracy of the implant alignment and position was achieved in 92% of patients in the extramedullary group and 96% of patients in the conventional group. The radiographic and clinical results of the extramedullary technique were comparable with those of the conventional technique with the advantage of no intramedullary interruption, less blood loss, a shorter operating time, and more rapid recovery. As the technique depends on the accurate tibial cut and overall alignment, we do not recommend it to surgeons without high volume experiences. Retrospectively registered IV, retrospective study

中文翻译：

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一种基于胫骨切口和整体对准的可移动单室膝关节置换术中指导股骨准备的新型髓外技术

牛津移动式单室膝关节置换术（UKA）植入物已与髓内引导装置一起广泛用于股骨准备。我们基于先行胫骨切开术和间隔块技术修改了股骨引导技术。进行这项研究是为了确定放射学准确性和髓外方法的早期临床结果。我们回顾性评估了使用髓外技术连续接受UKA的50例患者。相等数量的接受传统技术UKA治疗的患者作为对照组。根据手术时间，失血量，运动范围和医院特殊手术评分对临床结果进行评估。通过在冠状平面和矢状平面中的植入物位置和对准来评估射线照相的准确性。平均随访期为39年。76±5.77个月。两组的术后特殊手术医院评分，运动范围或髋膝踝角度无差异。髓外组的手术时间比常规组的要短（分别为54.78±7.95和59.14±10.91 min； p = 0.025）。髓外组3天后血红蛋白的下降仅为12.34±4.98 g / L，低于常规组（p = 0.001）。两组术后冠状角和矢状角无明显差异。在髓外组中有92％的患者和常规组中有96％的患者获得了可接受的植入物对准和位置的射线照相准确性。髓外技术的放射线照相和临床结果与常规技术相当，其优点是无髓内中断，失血少，手术时间短，恢复快。由于该技术取决于准确的胫骨切口和整体对齐方式，因此我们不建议没有经验的外科医生使用该技术。回顾性注册IV，回顾性研究