股骨假体对位不齐对骨质疏松患者膝关节内侧单髁置换后外侧间室结构应力的影响

Stress effect of femoral prosthesis misalignment on structure of lateral compartment during medial unicompartmental knee arthroplasty in patients with osteoporosis

背景:假体对位不齐和患者骨质情况是影响单髁置换预后的重要因素,内侧单髁置换后外侧间室骨关节炎进展是导致其高翻修率的主要并发症。因此,这将成为今后的研究热点。目的:分析不同股骨假体倾斜角度对正常骨质和骨质疏松患者内侧单髁置换后外侧间室结构应力的影响,并探讨骨质疏松与术后外侧间室骨关节炎的相关性。方法:使用经验证的膝关节有限元模型,建立正常骨质(M1)和骨质疏松(M2)单髁置换模型,并分别建立股骨假体倾斜模型(正常骨质组:内倾3°,6°,9°,12°、标准位置0°、外倾3°,6°,9°,12°;骨质疏松组:内倾3°,6°,9°,12°、标准位置0°、外倾3°,6°,9°,12°),共计18种工况。评估不同股骨假体倾斜角度对外侧间室半月板、胫骨软骨和股骨软骨的应力大小和分布的影响。结果与结论:①两组模型外侧间室半月板表面和胫骨软骨表面的高应力值随假体内倾角度的增加而增加,随假体外倾角度的增加而减小,相同工况下骨质疏松组半月板表面的峰值应力大于正常骨质组,但骨质疏松组胫骨软骨表面的峰值应力却小于正常骨质组;②两组模型外侧间室股骨软骨的高应力值随假体内倾和外倾角度的增加而增加,相同工况下骨质疏松组股骨软骨的峰值应力大于正常骨质组;③提示固定平台股骨假体内倾时,正常骨质和骨质疏松膝关节内侧单髁置换后外侧间室结构的应力均将增加,骨质疏松膝关节外侧间室应力增加更为明显;所以单髁置换过程中应特别注意假体安放位置,尽量避免内倾和外倾;同时,研究结果证实了骨质疏松可能会加重内侧单髁置换后外侧间室骨关节炎的进展。

BACKGROUND:Prosthesis misalignment and patient bone condition are important factors affecting the prognosis of unicompartmental knee arthroplasty,and postoperative osteoarthritic progression of the lateral compartment is a major complication leading to its high revision rate.Therefore,this will become a hot research topic in the future.OBJECTIVE:To analyze the effect of different femoral prosthesis tilt angles on the stress on the structure of the lateral compartment after unicompartmental knee arthroplasty in patients with normal bone and osteoporosis,and to investigate the correlation between osteoporosis and osteoarthritis of the lateral compartment in the postoperative period.METHODS:Using a validated finite element model of the knee,normal bone(M1)and osteoporotic(M2)unicompartmental knee arthroplasty were modeled.The femoral prosthesis tilt models(normal bone group:varus angles of 3°,6°,9°,12°,and 0°,valgus angles of 3°,6°,9°,12°;osteoporosis group:varus angles of 3°,6°,9°,12°,0°,valgus angles of 3°,6°,9°,12°)were established respectively,totaling 18 working conditions.The effects of different femoral prosthesis tilt angles on stress magnitude and distribution in the meniscus,tibial cartilage,and femoral cartilage of interstitial compartment were evaluated.RESULTS AND CONCLUSION:(1)The high stress values on the meniscus surface and tibial cartilage surface of the healthy lateral compartment of the two models increased with the increase of the prosthesis varus angle,and decreased with the increase of the prosthesis valgus angle.Under the same working conditions,the peak stress on the meniscus surface of the osteoporotic group was greater than that of the normal bone group,but that of the tibial cartilage surface of the osteoporotic group was less than that of the normal bone group.(2)The high stress values on the femoral cartilage of the lateral compartment of the two models increased with the increase of the prosthesis varus and valgus angles.Under the same working conditions,the peak stress on the femoral cartilage of the osteoporotic group was greater than that of the normal bone group.(3)It is indicated that when the fixed-bearing femoral prosthesis is varus,the stresses on the lateral compartment structures after medial unicompartmental knee arthroplasty in normal bone and osteoporotic knees will increase,and the increase in the stresses on the lateral intercondylar structures in osteoporotic knees will be more pronounced.Therefore,special attention should be paid to the placement of the prosthesis during unicompartmental knee arthroplasty to avoid varus and valgus of the prosthesis as much as possible.At the same time,the findings confirm that osteoporosis may exacerbate the progression of lateral compartment osteoarthritis after medial unicompartmental knee arthroplasty.