The stiff total knee replacement: Evaluation and treatment

Arthrofibrosis After Total Knee Arthroplasty: A Critical Analysis Review

» Arthrofibrosis after total knee arthroplasty (TKA) is the new formation of excessive scar tissue that results in limited ROM, pain, and functional deficits.» The diagnosis of arthrofibrosis is based on the patient's history, clinical examination, absence of alternative diagnoses from diagnostic testing, and operative findings. Imaging is helpful in ruling out specific causes of stiffness after TKA. A biopsy is not indicated, and no biomarkers of arthrofibrosis exist.» Arthrofibrosis pathophysiology is multifactorial and related to aberrant activation and proliferation of myofibroblasts that primarily deposit type I collagen in response to a proinflammatory environment. Transforming growth factor-beta signaling is the best established pathway involved in arthrofibrosis after TKA.» Management includes both nonoperative and operative modalities. Physical therapy is most used while revision arthroplasty is typically reserved as a last resort. Additional investigation into specific pathophysiologic mechanisms can better inform targeted therapeutics.

Molecular pathology of human knee arthrofibrosis defined by RNA sequencing

Arthrofibrosis is an abnormal histopathologic response, is debilitating for patients, and poses a substantial unsolved clinical challenge. This study characterizes molecular biomarkers and regulatory pathways associated with arthrofibrosis by comparing fibrotic and non-fibrotic human knee tissue. The fibrotic group encompasses 4 patients undergoing a revision total knee arthroplasty (TKA) for arthrofibrosis (RTKA-A) while the non-fibrotic group includes 4 patients undergoing primary TKA for osteoarthritis (PTKA) and 4 patients undergoing revision TKA for non-arthrofibrotic and non-infectious etiologies (RTKA-NA). RNA-sequencing of posterior capsule specimens revealed differences in gene expression between each patient group by hierarchical clustering, principal component analysis, and correlation analyses. Multiple differentially expressed genes (DEGs) were defined in RTKA-A versus PTKA patients (i.e., 2059 up-regulated and 1795 down-regulated genes) and RTKA-A versus RTKA-NA patients (i.e., 3255 up-regulated and 3683 down-regulated genes). Our findings define molecular and pathological markers of arthrofibrosis, as well as novel potential targets for risk profiling, early diagnosis and pharmacological treatment of patients.

Pathological mechanisms and therapeutic outlooks for arthrofibrosis

Arthrofibrosis is a fibrotic joint disorder that begins with an inflammatory reaction to insults such as injury, surgery and infection. Excessive extracellular matrix and adhesions contract pouches, bursae and tendons, cause pain and prevent a normal range of joint motion, with devastating consequences for patient quality of life. Arthrofibrosis affects people of all ages, with published rates varying. The risk factors and best management strategies are largely unknown due to a poor understanding of the pathology and lack of diagnostic biomarkers. However, current research into the pathogenesis of fibrosis in organs now informs the understanding of arthrofibrosis. The process begins when stress signals stimulate immune cells. The resulting cascade of cytokines and mediators drives fibroblasts to differentiate into myofibroblasts, which secrete fibrillar collagens and transforming growth factor-β (TGF-β). Positive feedback networks then dysregulate processes that normally terminate healing processes. We propose two subtypes of arthrofibrosis occur: active arthrofibrosis and residual arthrofibrosis. In the latter the fibrogenic processes have resolved but the joint remains stiff. The best therapeutic approach for each subtype may differ significantly. Treatment typically involves surgery, however, a pharmacological approach to correct dysregulated cell signalling could be more effective. Recent research shows that myofibroblasts are capable of reversing differentiation, and understanding the mechanisms of pathogenesis and resolution will be essential for the development of cell-based treatments. Therapies with significant promise are currently available, with more in development, including those that inhibit TGF-β signalling and epigenetic modifications. This review focuses on pathogenesis of sterile arthrofibrosis and therapeutic treatments.

Arthrofibrosis Associated With Total Knee Arthroplasty

BACKGROUND

Arthrofibrosis is a debilitating postoperative complication of total knee arthroplasty (TKA). It is one of the leading causes of hospital readmission and a predominant reason for TKA failure. The prevalence of arthrofibrosis will increase as the annual incidence of TKA in the United States rises into the millions.

METHODS

In a narrative review of the literature, the etiology, economic burden, treatment strategies, and future research directions of arthrofibrosis after TKA are examined.

RESULTS

Characterized by excessive proliferation of scar tissue during an impaired wound healing response, arthrofibrotic stiffness causes functional deficits in activities of daily living. Postoperative, supervised physiotherapy remains the first line of defense against the development of arthrofibrosis. Also, adjuncts to traditional physiotherapy such as splinting and augmented soft tissue mobilization can be beneficial. The effectiveness of rehabilitation on functional outcomes depends on the appropriate timing, intensity, and progression of the program, accounting for the patient's ability and level of pain. Invasive treatments such as manipulation under anesthesia, debridement, and revision arthroplasty improve range of motion, but can be traumatic and costly. Future studies investigating novel treatments, early diagnosis, and potential preoperative screening for risk of arthrofibrosis will help target those patients who will need additional attention and tailored rehabilitation to improve TKA outcomes.

CONCLUSION

Arthrofibrosis is a multi-faceted complication of TKA, and is difficult to treat without an early, tailored, comprehensive rehabilitation program. Understanding the risk factors for its development and the benefits and shortcomings of various interventions are essential to best restore mobility and function.