Post-Traumatic Osteoarthritis Following ACL Injury

Li-Juan Wang; Ni Zeng; Zhi-Peng Yan; Jie-Ting Li; Guo-Xin Ni


Arthritis Res Ther. 2020;22(57) 

In This Article

ACL Reconstruction and PTOA

Patients who wish to return to high-level activities commonly choose to undergo ACL reconstruction (ACL-R). It is believed that ACL-R helps to restrain the anterior translation of tibia, regain proper joint kinematics, restore knee stability, and prevent excessive torsional loading, thus resulting in pain relief, functional recovery, low complication rates, and highly predictable improvements.[1,11] Notably, reconstruction methods, including graft choice, attachment point, fixation, and tension, as well as rotational stability, could affect the biomechanical load of the knee joint.[1] Evidence shows that hamstring autografts demonstrate lower incidence, less knee pain, and better self-reported function than bone-patellar tendon-bone autografts.[6]

Interestingly, arthroscopic surgery seems to have almost the same incidence as open surgery.[6] However, convincing evidence for the superiority of ACL-R to conservative management in terms of PTOA incidence is still lacking.[12,13] A number of reasons may explain why ACL-R does not provide protective benefits for long-term joint health. Firstly, surgery cannot completely restore normal joint mechanics.[1] The disruption of normal loading distribution and biomechanics may result in loading on articular areas that are not accustomed to load during weight-bearing activities.[14] Gait analysis reveals that patients with ACL-R knees exhibit altered joint loading patterns and tibial rotation compared with uninjured contralateral knees or healthy patients.[14] The average knee center of rotation (KCOR) during the stance phase of gait after ACL-R changes. Compared with an uninjured contralateral knee, the KCOR of an ACL-R knee is more lateral and anterior at 2 years after surgery, leading to greater motion between the femur and the tibia in the medial compartment relative to the lateral compartment.[15] Secondly, inflammation of the synovium at early time points has been observed.[15] It is supposed that surgery itself could lead to knee joint trauma, and postsurgical hemarthrosis could result in prolonged joint inflammation.[13] Postoperative inflammation may damage synovial stem cells and lead to a compromised joint environment, thus affecting the ability of tissues to heal. A study using mini pigs as animal models showed that the expression of inflammatory cytokines, especially IL-1β, IL-6, and TNF-α, which are correlated with the morphological score of PTOA, increased after an idealized ACL-R.[16] Thirdly, molecular and cellular alterations to joint tissues caused by injury are not readily reversible through joint stabilization.[11]