髌下脂肪垫在膝骨关节炎发病和进展中的作用

Advances in the role of the infrapatellar fat pad in the initiation and progression of knee osteoarthritis

关节炎是慢性退变性疾病,可以发生在髋、膝、踝、脊柱等全身多个关节,其中以膝骨关节炎（knee osteoarthritis,KOA）最为常见.KOA临床表现为关节疼痛、肿胀、僵硬、畸形,严重影响患者日常生活质量.KOA的发生是一种由力学和生化因素导致的缓慢、渐进的病理过程,可能与软骨细胞的合成与分解代谢失衡有关.力学因素主要是软骨退化及韧带损伤引起的关节失衡,而生化因素主要是软骨细胞代谢失调及滑膜炎引起的关节微环境改变.髌下脂肪垫（infrapatellar fat pad,IPFP）充填于髌骨、股骨髁下部、胫骨髁前上缘及髌韧带之间,位于滑膜外关节内的一种以弹性纤维为网状支架的脂肪组织.既往IPFP长期被认为是结构性脂肪组织,因无或鲜有代谢反应而被忽视,膝关节手术时为获得清晰的视野常部分或全部切除IPFP.但近年来研究发现,IPFP具有潜在的生物力学、内分泌功能,可产生多种炎症细胞因子、趋化因子、炎症介质,同时存在丰富的神经纤维结构,此外其内含大量脂肪间质干细胞,使其越来越受到学者们的关注.研究表明除滑膜、韧带、软骨和骨外,IPFP可能在KOA的发病、进展过程及膝疼痛中发挥重要作用.IPFP在生理情况以及KOA的早期阶段可通过缓冲震荡、稳定润滑来保护膝关节,但随着KOA进展,IPFP会通过分泌瘦素、脂联素等脂肪因子、炎症介质对膝关节起到破坏性作用.然而在膝关节手术中,切除IPFP后可能会增加膝关节疼痛,导致髌腱短缩,虽然切除IPFP后对膝关节功能无明显影响,但全部切除时有增加切口并发症的风险,因此建议谨慎切除IPFP或适当保留“密集血管区”.

Osteoarthritis （OA） is a common chronic debilitating disease among middle-aged and old people,which can occur in the hip,knee,ankle,spine and other joints,but it is most commonly seen in the knee.The clinical manifestations of the knee osteoarthritis （KOA） include pain,swelling,stiffness,joint deformity,seriously affectting the quality of life.Mechanical and metabolic factors have been shown to play roles in the initiation and progression of this disease,resulting in a slow,progressive pathological process,and the normal balance of anabolic and catabolic activities of the chondrocytes has been disrupted.The mechanical factors are the joint imbalance caused by cartilage degeneration and ligament damage,and biochemical factors are mainly the changes of the joint microenvironment caused by the dysregulation of chondrocytes and synovitis.Infrapatellar fat pad （IPFP）is situated in the lower part of patella and femoral condyle,between tibia condyle and the patellar ligament,and it is an intracapsular but extrasynovial elastic fiber adipose tissue.Researches have shown that besides the synovial membrane,ligament,cartilage and bone,IPFP may play an important role in the onset and progression of KOA and knee pain.IPFP has long been regarded as a structural fatty tissue without metabolic reactions,thus often been neglected,what＇s more,to get a clear vision in knee surgery,IPFP is often partially or totally resected,but recently owning to its potential biological mechanics,endocrine function,which can produce a variety of inflammatory cytokines,chemokines,rich in nerve fiber structure and IPFP-adipose derived stem cells,more and more scholars pay attention to the IPFP.IPFP may play a protective role in the early stage of KOA by cushioning shock,stabilizing lubrication,but this article emphatically explain how IPFP play a desctructive role in the initiation and progressionof KOA through leptin,adiponectin,and many other adipocytokines,or inflammatory mediators,so as to get further understanding of KOA,and discuss whether IPFP should be resected or not in knee surgery,providing a new method to the prevention and treatment of KOA.