Chalmers B P, Mehrotra K G, Sierra R J, Pagnano M W, Taunton M J, Abdel M P
Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
Bone Joint J. 2018 Apr 1;100-B(4):450-454. doi: 10.1302/0301-620X.100B4.BJJ-2017-1041.R2.
Primary (or spontaneous) and secondary osteonecrosis of the knee can lead to severe joint degeneration, for which either total or unicompartmental arthroplasty may be considered. However, there are limited studies analyzing outcomes of unicompartmental knee arthroplasties (UKAs) for osteonecrosis involving an isolated compartment of the knee. The aims of this study were to analyze outcomes of UKAs for osteonecrosis with specific focus on 1) survivorship free of any revision or reoperation, 2) risk factors for failure, 3) clinical outcomes, and 4) complications.
A total of 45 patients underwent 46 UKAs for knee osteonecrosis between 2002 and 2014 at our institution (The Mayo Clinic, Rochester, Minnesota). Twenty patients (44%) were female; the mean age of the patients was 66 years, and mean body mass index (BMI) was 31 kg/m. Of the 46 UKAs, 44 (96%) were medial UKAs, and 35 (76%) were fixed-bearing design. Mean mechanical axis postoperatively was 1.5° varus (0° to 5° varus); 41 UKAs (89%) were performed for primary osteonecrosis. Mean follow-up was five years (2 to 12).
Survivorship free of any revision in the cohort was 89% (95% CI 77 to 99) and 76% (95% CI 53 to 99) at five and ten years, respectively. In patients undergoing UKA for primary osteonecrosis survivorship free of any revision was 93% (95% CI 83 to 100)at both five and ten years. Secondary osteonecrosis was a significant risk factor for poorer survivorship free of any revision or reoperation (hazard ratio 7.7, p = 0.03). Three medial UKAs (6.5%) were converted to total knee arthroplasties (TKAs): two for lateral compartment degeneration and one for development of lateral osteonecrosis. No implants were revised for loosening, fracture, or wear. Knee Society scores improved from a mean of 60 (44 to 72) preoperatively to a mean of 94 postoperatively (82 to 100) (p < 0.001). There were no surgical complications.
When done for primary osteonecrosis of the knee, UKA resulted in reliable clinical improvement, minimal complications, and durable estimated implant survivorship free of revision at ten years. UKA done for secondary osteonecrosis was substantially less durable at mid-term follow-up. Progression of knee degeneration, rather than implant failure or loosening, was most common indication for conversion to TKA. Cite this article: Bone Joint J 2018;100-B:450-4.
膝关节原发性（或自发性）和继发性骨坏死可导致严重的关节退变，对此可考虑行全膝关节置换术或单髁膝关节置换术。然而，分析单髁膝关节置换术（UKA）治疗累及膝关节单个间室的骨坏死疗效的研究有限。本研究的目的是分析UKA治疗骨坏死的疗效，特别关注1）无任何翻修或再次手术的假体生存率，2）失败的危险因素，3）临床疗效，以及4）并发症。
2002年至2014年期间，在我们机构（明尼苏达州罗切斯特市梅奥诊所）共有45例患者接受了46次UKA治疗膝关节骨坏死。20例患者（44%）为女性；患者的平均年龄为66岁，平均体重指数（BMI）为31kg/m。在46次UKA中，44次（96%）为内侧UKA，35次（76%）采用固定平台设计。术后平均机械轴为内翻1.5°（0°至5°内翻）；其中41次UKA（89%）用于原发性骨坏死。平均随访时间为5年（2至12年）。
该队列中无任何翻修的假体生存率在5年和10年时分别为89%（95%CI 77至99）和76%（95%CI 53至99）。接受UKA治疗原发性骨坏死的患者在5年和10年时无任何翻修的假体生存率均为93%（95%CI 83至100）。继发性骨坏死是无任何翻修或再次手术的较差假体生存率的显著危险因素（风险比7.7，p = 0.03）。3次内侧UKA（6.5%）转换为全膝关节置换术（TKA）：2次因外侧间室退变，1次因外侧骨坏死进展。没有因松动、骨折或磨损而翻修假体。膝关节协会评分从术前平均60分（44至72分）提高到术后平均94分（82至100分）（p < 0.001）。无手术并发症。
当用于膝关节原发性骨坏死时，UKA可带来可靠的临床改善、最少的并发症以及10年时假体无翻修的持久估计生存率。在中期随访中，用于继发性骨坏死的UKA耐久性明显较差。膝关节退变进展而非假体失败或松动是转换为TKA最常见的原因。引用本文：《骨与关节杂志》2018年；100 - B：450 - 4。
