Soininvaara Tarja A, Miettinen Hannu J A, Jurvelin Jukka S, Suomalainen Olavi T, Alhava Esko M, Kröger Heikki P
Department of Surgery, Savonlinna Central Hospital, Finland.
Acta Orthop Scand. 2004 Oct;75(5):600-5. doi: 10.1080/00016470410001493.
The critical structure supporting the prosthetic components in total knee arthroplasty (TKA) is tibial trabecular bone. The quality of tibial bone can be evaluated by bone mineral density (BMD) measurements.
We prospectively measured changes in BMD in the proximal tibia after cemented TKA in osteoarthrotic knees. 69 patients were scanned by dual-energy X-ray absorptiometry (DXA) within a week after surgery, and after 3, 6 and 12 months.
At baseline, the medial region of interest (ROI) BMD was higher in the varus knees than in the valgus aligned knees (p=0.02). The medial metaphyseal ROI showed a decrease in BMD during the follow-up in preoperatively varus knee joints (p<0.001). In preoperatively valgus knees, there was a slight increase in medial compartment BMD which was not significant (p=0.2). Alignment correction in both groups showed bone remodeling giving similar medial and lateral BMD values, suggesting that the bone became equally strong in both compartments of the metaphysis. There was no association between increasing American Knee Society (AKS) scores and bone remodeling.
We suggest that this remodeling is caused by postoperative changes in tibial loading. Our results support the clinical importance of recreating proper valgus alignment of the knee joint in the TKA operation, thus possibly providing better conditions for longevity of the tibial component.
全膝关节置换术（TKA）中支撑假体组件的关键结构是胫骨小梁骨。胫骨骨质量可通过骨密度（BMD）测量进行评估。
我们前瞻性地测量了骨关节炎膝关节行骨水泥型TKA术后胫骨近端BMD的变化。69例患者在术后1周内以及术后3、6和12个月接受了双能X线吸收法（DXA）扫描。
基线时，内翻膝的内侧感兴趣区域（ROI）BMD高于外翻对齐膝（p = 0.02）。术前内翻膝关节的内侧干骺端ROI在随访期间BMD下降（p < 0.001）。术前外翻膝中，内侧间室BMD略有增加，但不显著（p = 0.2）。两组的对线矫正均显示骨重塑，内侧和外侧BMD值相似，表明干骺端的两个间室骨强度变得相同。美国膝关节协会（AKS）评分增加与骨重塑之间无关联。
我们认为这种重塑是由术后胫骨负荷变化引起的。我们的结果支持了在TKA手术中重建膝关节正确外翻对线的临床重要性，从而可能为胫骨组件的长期使用提供更好的条件。
