Scott Chloe E H, Wade Frazer A, Bhattacharya Rajarshi, MacDonald Deborah, Pankaj Pankaj, Nutton Richard W
School of Engineering, University of Edinburgh, Edinburgh, UK; Department of Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, UK.
Department of Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, UK.
J Arthroplasty. 2016 Mar;31(3):702-9. doi: 10.1016/j.arth.2015.09.046. Epub 2015 Oct 24.
Proximal tibial strain in medial unicompartmental knee arthroplasty (UKA) may alter bone mineral density and cause pain. The aims of this retrospective cohort study were to quantify and compare changes in proximal tibial bone mineral density in metal-backed and all-polyethylene medial UKAs, correlating these with outcome, particularly ongoing pain.
Radiographs of 173 metal-backed and 82 all-polyethylene UKAs were analyzed using digital radiograph densitometry at 0, 1, 2, and 5 years. The mean grayscale of 4 proximal tibial regions was measured and converted to a ratio: the GSRb (grayscale ratio b), where GSRb>1 represents relative medial sclerosis.
In both implants, GSRb reduced significantly to 1 year and stabilized with no differences between implants. Subgroup analysis showed less improvement in Oxford Knee Score in patients whose GSRb increased by more than 10% at 1 year (40/255) compared with patients whose GSRb reduced by more than 10% at both 1 years (8.2 vs 15.8, P=.002) and 5 years (9.6 vs 15.8, P=.022). Patients with persistently painful UKAs (17/255) showed no reduction in GSRb at 1 year compared with a 20% reduction in those without pain (P=.05).
Bone mineral density changes under medial UKAs are independent of metal backing. Medial sclerosis appears to be associated with ongoing pain.
内侧单髁膝关节置换术（UKA）中胫骨近端应变可能会改变骨矿物质密度并引起疼痛。这项回顾性队列研究的目的是量化并比较金属背衬型和全聚乙烯内侧UKA中胫骨近端骨矿物质密度的变化，并将这些变化与手术结果相关联，尤其是持续性疼痛。
使用数字X线密度测定法对173例金属背衬型和82例全聚乙烯UKA在0年、1年、2年和5年时的X线片进行分析。测量胫骨近端4个区域的平均灰度并将其转换为一个比率：灰度比率b（GSRb），其中GSRb>1表示相对内侧硬化。
在两种植入物中，GSRb在1年时均显著降低并趋于稳定，植入物之间无差异。亚组分析显示，与1年时GSRb降低超过10%的患者（8.2对15.8，P=0.002）和5年时GSRb降低超过10%的患者（9.6对15.8，P=0.022）相比，1年时GSRb增加超过10%的患者（40/255）牛津膝关节评分改善较少。持续性疼痛的UKA患者（17/255）在1年时GSRb没有降低，而无痛患者降低了20%（P=0.05）。
内侧UKA下的骨矿物质密度变化与金属背衬无关。内侧硬化似乎与持续性疼痛有关。
