Objective: To explore the imaging features of intramedullary guide rod and its influence on the alignment of the femoral prosthesis in unicompartmental knee arthroplasty (UKA).
Methods: Between August 2016 and November 2016, 50 patients (50 knees) with primary anteromedial osteoarthritis were treated with UKA by Oxford MicroPlasty minimally invasive replacement system. There were 10 males and 40 females. The age ranged from 62 to 77 years with an average of 68.8 years. Preoperative varus and flexion deformity angles were (5.22±3.46)° and (7.42±2.65)°, respectively. The knee range of motion (ROM) was (106.85±7.62)°. The Hospital for Special Surgery (HSS) score was 68.26±4.65. The angles between the femoral intramedullary guide rod and the anatomical axis of femur on the coronal and sagittal planes, the femoral component valgus/varus angle (FCVA), the femoral component posterior slope angle (FCPSA), knee varus deformity angle, and knee flexion deformity angle were measured by intra- and post-operative X-ray films. The postoperative ROM and HSS score were measured.
Results: Intraoperative X-ray films measurement showed that the lateral side angles between femoral intramedullary guide rod and femoral anatomical axis were observed on coronal plane, and the angles ranged from 0.28 to 2.06° with an average of 0.96°. While the posterior side angles were observed on sagittal plane, and the angles ranged from 0.09 to 0.48° with an average of 0.23°. The angulations (>1°) between femoral intramedullary part guide rod and outside part of the rod were confirmed in 12 cases (24%) on coronal plane. Postoperative femoral prosthesis were mild varus in 38 patients (76%). The FCVA ranged from -1.76 to 4.08° with an average of 2.21°. The FCPSA ranged from 7.12 to 13.86° with an average of 9.16°. All patients were followed up 22-26 months, with an average of 24.5 months. The incisions healed by first intention. At last follow-up, the varus and flexion deformity angles were (1.82±1.05) and (2.54 ± 1.86)°, respectively. ROM was (124.62±5.85)° and HSS score was 91.58±3.65. There were significant differences between pre- and post-operative parameters ( P<0.05). No complication such as dislocation or aseptic loosening of the prosthesis occurred during the follow-up.
Conclusion: UKA by Oxford MicroPlasty minimally invasive replacement system can obtain accurate femoral prosthesis position with the help of intramedullary guide system, and the effectiveness is excellent.
目的: 研究单髁关节置换术（unicompartmental knee arthroplasty，UKA）中股骨髓内定位导杆影像学位置特征及其对股骨假体力线的影响。.
方法: 2016 年 8 月—11 月，收治 50 例（50 膝）原发性膝关节前内侧骨关节炎患者。男 10 例，女 40 例；年龄 62～77 岁，平均 68.8 岁。膝内翻畸形角度为（5.22±3.46）°，屈曲畸形角度为（7.42±2.65）°；膝关节活动度（range of motion，ROM）为（106.85±7.62）°；美国特种外科医院（HSS）评分为（68.26±4.65）分。采用 MicroPlasty 牛津膝关节微创置换系统行 UKA。术中及术后 X 线片测量股骨髓内导杆与股骨解剖轴线在冠状位及矢状位的夹角、股骨假体内外翻角（femoral component valgus/varus angle，FCVA）、股骨假体屈曲角（femoral component posterior slope angle，FCPSA）、膝关节内翻及屈曲畸形角度；术后测量膝关节 ROM、HSS 评分。.
结果: 术中 X 线片测量示股骨髓内导杆与髓腔解剖轴线在冠状位均呈外侧交角，角度为 0.28～2.06°，平均 0.96°；在矢状位呈后方交角，角度为 0.09～0.48°，平均 0.23°。12 例（24%）冠状位上股骨髓内导杆的髓内段和髓外段部分成角形变（>1°）。术后 X 线片测量示股骨假体内翻 38 例（76%），FCVA 为–1.76～4.08°，平均 2.21°；FCPSA 为 7.12～13.86°，平均 9.16°。患者均获随访，随访时间 22～26 个月，平均 24.5 个月。术后切口均Ⅰ期愈合。末次随访时，膝内翻畸形角度为（1.82±1.05）°、屈曲畸形角度为（2.54±1.86）°，ROM 为（124.62±5.85）°、HSS 评分为（91.58±3.65）分，与术前比较差异均有统计学意义（ P<0.05）。随访期间均未出现衬垫脱位、假体无菌性松动等并发症。.
结论: UKA 术中采用 MicroPlasty 牛津膝关节微创置换系统进行股骨髓内定位，可获得准确的股骨假体位置，且术后疗效优良。.
Keywords: Knee joint; femoral component alignment; femoral intramedullary guide; unicompartmental knee arthroplasty.