The Science of Scar Tissue: Understanding Arthrofibrosis in Knee Replacement Surgery

Arthrofibrosis, a condition characterised by excessive scar tissue formation, poses a significant challenge following knee replacement surgery. This complication can severely restrict the range of motion (ROM) of the joint and cause considerable pain and discomfort. Delving into the science behind scar tissue formation is crucial for developing effective treatment strategies and enhancing patient outcomes.

What is Arthrofibrosis?

Arthrofibrosis is defined as the

“fibrosis of the soft tissues that was not present pre-operatively, and not due to other causes such as prosthetic conflict, pain or infection” (Kalson et al., 2016).

Essentially, it involves an abnormal response to surgical trauma, leading to the excessive proliferation of fibroblasts and extracellular matrix proteins, which results in joint stiffness.

Pathophysiology of Scar Tissue Formation

Scar tissue formation is a natural part of the body’s healing process. After an injury or surgery, the body initiates a repair process involving inflammation, tissue proliferation, and remodelling. This process is regulated by various cytokines and growth factors that stimulate fibroblasts to produce collagen and other extracellular matrix components.

During knee replacement surgery, the initial inflammatory response is critical for healing. However, in some patients, this response can become exaggerated, leading to abnormal scar tissue formation. This pathological process is described as

“pathogenic stiffening of a joint because of an exaggerated inflammatory response, including the proliferation of metaplastic fibroblasts and extracellular matrix proteins” (Thompson et al., 2019)

,is at the core of arthrofibrosis.

Risk Factors for Arthrofibrosis

Several factors can predispose patients to develop arthrofibrosis after knee replacement surgery:

Pre-operative Stiffness: Patients with limited ROM before surgery are more susceptible to developing post-operative stiffness.
Inadequate Rehabilitation: Proper post-operative rehabilitation, including range of motion exercises, is crucial for preventing excessive scar tissue formation.
Biological Factors: Genetic predisposition and individual variations in the inflammatory response can influence the degree of scar tissue formation.
Management of Pain and Swelling: Poor control of pain and swelling can exacerbate inflammation and contribute to the development of scar tissue.

Identification and Treatment

Early identification of patients at risk of developing arthrofibrosis is crucial. Studies indicate that signs of stiffness can manifest as early as four weeks post-operatively (Kornuijit et al., 2020). Patients showing limited ROM during early recovery stages should be closely monitored and treated promptly to prevent further complications.

Innovative Solutions: The STAK Knee Stretcher

Traditional treatments for arthrofibrosis include physiotherapy and manual manipulation under anaesthesia (MUA). However, these approaches may have limited success rates and inherent risks.

The STAK Knee Stretcher offers a promising alternative. This device allows patients to perform high-intensity stretching exercises at home, which can help break down scar tissue and improve knee flexion. The STAK tool operates by applying controlled forces similar to those used by physiotherapists, with the added benefit of allowing patients to adjust the intensity based on their comfort level.

Conclusion

Arthrofibrosis remains a complex and challenging complication following knee replacement surgery. By focusing on early identification and proactive management, healthcare providers can mitigate the impact of arthrofibrosis and support a smoother recovery for their patients.

References

Kalson, N.S., et al. (2016). Pathogenic mechanisms of arthrofibrosis: fibrosis of the soft tissues that was not present pre-operatively, and not due to other causes such as prosthetic conflict, pain or infection.
Thompson, S.M., et al. (2019). Pathogenic stiffening of a joint because of an exaggerated inflammatory response, includes the proliferation of metaplastic fibroblasts and extracellular matrix proteins.
Kornuijit, A., et al. (2020). Recovery of knee range of motion after total knee arthroplasty in the first preoperative weeks: poor recovery can be detected early.