下肢力线与膝关节软骨下骨板杆结构和软骨退变的关系

目的利用骨小梁分割技术(individual trabecula segmentation,ITS)和组织学方法分析膝关节骨关节炎(osteoarthritis,OA)的胫骨平台骨软骨标本,研究下肢力线与软骨下小梁骨显微结构以及软骨退变的关系。方法接受全膝关节置换术病人术前进行下肢全长X线平片拍摄,进行髋-膝-踝(hip-knee-ankle,HKA)角测量。收集术中切除的胫骨平台标本进行显微CT扫描,利用ITS分析软骨下骨小梁结构。通过组织学方法评价软骨退变。对下肢力线与软骨下骨显微结构参数改变和软骨退变进行相关性分析。结果胫骨平台软骨下骨小梁体积分数(BV/TV)、骨小板(pBV/TV)体积分数、骨小杆体积分数(rBV/TV)及轴向骨小梁体积分数(aBV/TV)、骨小板及骨小杆体积比值(P/R)、骨小板数量(pTb. N)、骨小板厚度(pTb. Th)、骨小板表面积(pTb. S)、骨小杆长度(rTb. L)、骨小板-骨小板连接密度(P-P Junc. D)、骨小板-骨小杆连接密度(P-R Junc. D)与软骨退变程度和下肢力线角度显著相关。HKA角度绝对值越大,受累侧胫骨平台软骨下骨小板增厚,骨小板数量增加,骨小板-骨小板以及骨小板-骨小杆的连接性越强,同时软骨退变OARSI评分也越高。结论下肢力线异常可能通过改变膝关节正常的应力分布而导致胫骨平台软骨下骨小梁显微结构异常,尤其是骨小板和轴向骨小梁的显著增多和增厚可能是进一步加重被覆软骨退变、导致OA进展的危险因素。因此,通过改变力线和调节软骨下骨代谢有望成为早期干预骨关节炎发生和发展的切入点。

Relationship of Subchondral Plate-Rod Structure and Cartilage Degeneration with Lower Limb Alignment

Objective To study the relationship of the tibial plateau subchondral trabecular bone (STB) microstructure and the cartilage degeneration with the lower limb alignment based on individual trabecula segmentation (ITS) and histology analysis in knee osteoarthritis (OA). Methods Hip-knee-ankle (HKA) angles were measured on the full-length lower extremity films of patients before total knee arthroplasty (TKA). The tibial plateau excised from the TKA were collected for micro-CT scanning and ITS analysis. The cartilage degeneration was evaluated by histology. The relationship between the HKA angle and the changes in microstructural parameters of STB and cartilage degeneration were analyzed. ResultsThe plate, rod and axial bone trabecular volume fraction (BV/TV, pBV/TV, pBV/TV), ratio of trabecular plate versus rod (P/R), plate trabecular number density (pTb.N), plate trabecular thickness (pTb.Th), trabecular plate surface area (pTb.S), trabecular rod length (rTb.L), and plate-plate and plate-rod junction density (P-P Junc.D, P-R Junc.D) of the subchondral bone of the tibial plateau were significantly related to the cartilage degeneration OARSI score and the HKA angle. The greater the deviation of the lower limb alignment, the greater the number of subchondral trabeculae, the thicker the trabeculae, the greater the bone mass, the stronger the connectivity, especially the plate trabeculae on the affected side of tibial plateau, and the higher the OARSI score of cartilage degeneration. Conclusions Abnormal lower limb alignment may cause abnormal microstructure of the plate and rod STB of the tibial plateau by changing the stress distribution of the knee, especially the significant increase and thickening of the plate trabecular and axial trabecular bone, which may be an important risk factor that further aggravates the degeneration of articular cartilage and the progress of OA. Therefore, lower limb alignment correction with surgical intervention and improving STB with bone metabolism agents may efficiently contribute to preventing cartilage damage and mitigate OA progression.