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

Treatment of PTOA

As a progressive and chronic condition, PTOA should be treated at an early stage to minimize its long-term effects and prevent the development of end-stage OA.[3,15] Unlike idiopathic OA, there is a clear injurious event involved in the case of PTOA. A known "starting point" presents the opportunity for targeted treatments.[3] Intervening immediately after injury plays an important role in the prevention of future degradation.

A better understanding of pathogenic pathways makes it possible to develop targeted interventions to prevent clinically significant disease. The most discussed treatment methods in the literature are biological interventions, including anti-cytokine and chemokine interventions (intraarticular injection of IL-1Ra),[5,11] anti-resorptive therapies (bisphosphonates and strontium ranelate, etc.),[35] anti-oxidant treatment (methylsulfonylmethane and pycnogenol, etc.),[18] and joint aspiration to remove hemarthrosis at the time of injury.[17] Selective inhibition of IL1, IL6, IL-17, and metalloproteinases may decrease the degradation of the articular cartilage ECM, and inhibition of resistin and TNF-a may decrease synovial inflammation and boundary lubrication.[3] Extracellular matrix–blood composite injection relieved the pain during weight bearing and attenuated cartilage damage after ACL transection in a rat model.[37] Studies on genetically engineered mice show promising interventions targeting certain gene transcriptions.[3] Using p16-3MR transgenic mice, Jeon et al.[41] demonstrated that selective removal of senescent cells retards OA progression, reduces pain, and creates a pro-regenerative environment. Non-pharmacological treatments such as cryotherapy improve footprint patterns and reduce synovial inflammation.[42] Weight loss is often recommended in treatment programs, as it decreases joint loading and IL-7 levels through biomechanical and inflammatory pathways.[11]

Surgical techniques such as reconstructive procedures have been improved and new ones, such as arthroscopic surgery, have been introduced. As mentioned earlier, the use of hamstring autografts in ACL-R exhibits good clinical outcomes.[6] Notably, the functional outcome in quadriceps autograft groups is equal to or better than in hamstring autograft groups.[43] For patients with concomitant meniscus injury, the more of the meniscus is preserved, the better the outcome will be. Thus, meniscal repair instead of partial meniscectomies during surgery is recommended.[5] Removing a part of the meniscus decreases the distribution of the transmission force, and partial meniscectomy decreases quadriceps strength, which could be associated with altered lower extremity biomechanics.[6]

Regardless of treatment by surgical or nonsurgical means, an integrated rehabilitation program that helps to improve neuromuscular control, strength, power, and muscular symmetry is necessary.[1,5] Rabbits treated with early continuous passive motion (CPM) after ACL transection have normal articular surfaces, thicker articular cartilage, better tidemark continuity, lower levels of inflammatory cytokine, and abundant GAG, indicating that CPM has a significant effect in protecting against PTOA.[44] In Frobell's study, for young patients with acute ACL tear, structured rehabilitation plus early ACL-R did not result in better outcome of Knee Injury and Osteoarthritis Outcome Score than patients with structured rehabilitation plus optional delayed ACL-R. Moreover, for patients using latter strategy, 61% of ACL-R could be avoided without adverse outcome, indicating that structured rehabilitation program is of great importance in the management of ACL injury.[45] For patients undergoing ACL-R, early rehabilitation both preoperatively and postoperatively is needed.[5] Exercise is an integral part of rehabilitation programs and has positive effects.[46] Patients with limited range of motion have a higher incidence of PTOA. Those with a quadriceps and hamstring strength deficit fail to maintain normal loading patterns and absorb impact, which may lead to joint space narrowing. Therefore, returning to the normal range of motion and quadriceps and hamstring strength training should be essential parts of rehabilitation programs.[14]

Education also plays a crucial part that cannot be ignored. It is necessary to raise patients' awareness of re-injury and PTOA risk, help them understand the importance of re-injury prevention and return-to-play criteria, and educate them in modifying physical activity and weight management and diet.