Department of Orthopedics, Tongji Hospital, and Department of Regenerative Medicine, School of Medicine, Tongji University, Shanghai, PR China.
Med Hypotheses. 2011 Oct;77(4):620-3. doi: 10.1016/j.mehy.2011.06.048. Epub 2011 Aug 6.
Patella Baja, as a common complication of knee trauma or knee surgery, was very difficult to deal with, and scarring and shortening of the patellar tendon were looked on as the most important reason for it. Infrapatellar fat pad, also known as Hoffa's fat pad was traditionally regarded as with only buffering and lubricating functions in knee joints, which can limit the knee's excessive activities, absorb shocks from the anterior knee and reduces friction between the patellar tendon and the tibia, it should be with direct protection function and avoid the damage of patella tendon. Recently, a large number of studies had shown that adipose tissue was an accessible and abundant source of mesenchymal stem cells for tissue engineering. Adipose derived stem cells (ADSCs) can be induced to differentiate into adipocytes, osteoblasts, nerve cells, tendon cells and so on. In addition, interestingly, infrapatellar fat pad were just located behind the patellar tendon, and SDF-1 (stromal cell-derived factor-1), as a powerful cytokine that regulates inflammatory cell recruitment and stem cell homing, was unregulated after ligament injury, so there may be a certain correlation between ADSCs from infrapatellar fat pad and injured tendons, maybe ADSCs from infrapatellar fat pad can biologically repair injured tendons when patella tendon was damaged. We hypothesized injured patella tendon repairing should include not only the self-repairing of the tendon, but also the biological repairing from ADSCs in infrapatellar fat pad. When both of the repairing failed to repair the damage of the tendon, patellar tendon may begin to shrink and scar, which will result in patella Baja. In our opinion, healthy infrapatellar fat pad was with direct protection function of patella tendon and full of rich ADSCs, which may play an important part in patella tendon repairing and the developing process of patella Baja.
髌腱下极作为膝关节创伤或膝关节手术后的常见并发症,处理起来非常困难,而髌腱的瘢痕和缩短被认为是最重要的原因。髌下脂肪垫,也称为 Hoffa 脂肪垫,传统上被认为仅具有膝关节的缓冲和润滑功能,它可以限制膝关节的过度活动,吸收前膝的冲击并减少髌腱与胫骨之间的摩擦,它应该具有直接的保护功能,避免髌腱损伤。最近,大量研究表明脂肪组织是组织工程中间充质干细胞的一种易于获得且丰富的来源。脂肪来源的干细胞(ADSCs)可被诱导分化为脂肪细胞、成骨细胞、神经细胞、肌腱细胞等。此外,有趣的是,髌下脂肪垫刚好位于髌腱后面,而 SDF-1(基质细胞衍生因子-1)作为一种调节炎症细胞募集和干细胞归巢的强大细胞因子,在韧带损伤后会失调,因此髌下脂肪垫中的 ADSCs 与受损的肌腱之间可能存在一定的相关性,也许髌下脂肪垫中的 ADSCs 可以在髌腱受损时对受损的肌腱进行生物修复。我们假设受伤的髌腱修复不仅应包括肌腱的自我修复,还应包括髌下脂肪垫中的 ADSCs 的生物修复。当两者的修复都未能修复肌腱的损伤时,髌腱可能开始萎缩和瘢痕化,从而导致髌腱下极。在我们看来,健康的髌下脂肪垫对髌腱具有直接的保护作用,并且富含丰富的 ADSCs,这可能在髌腱修复和髌腱下极的发展过程中发挥重要作用。