COntralateral CorticoSTeroid Injection in Total Knee Arthroplasty (COSTI)

Total knee arthroplasty (TKA) is a common and successful procedure used to improve the quality of life and function for patients experiencing debilitating pain from degenerative knee osteoarthritis (OA).

Some patients with knee OA have bilateral involvement and surgery may be needed in both knees. Having bilateral knee OA is a known risk factor for dissatisfaction, as there can be an overuse of the less affected, contralateral knee, in order to avoid symptoms from the more severely affected knee. Moreover, one of the principal determinants of patient-reported functional outcome after a unilateral TKA is residual pain and limited function in the contralateral, un-replaced knee.

One option to improve range of motion, pain, functional scores and reduce postoperative stiffness on both knees is a bilateral TKA; however, it has been previously reported to have a higher risk of serious cardiac complications, pulmonary complications, and mortality when compared with a unilateral TKA. A less invasive and widely available treatment option is intra-articular corticosteroids applied pre-/peri-operatively in the contralateral (un-replaced) knee to improve post-operative rehabilitation.

Intra-articular corticosteroids are extensively used to reduce inflammation and pain in inflamed arthritic joints. They are associated with a moderate improvement in pain and a small improvement in physical function usually up to 3 months after injection. The use of intra-articular corticosteroids in patients with symptomatic knee OA has been shown to improve Visual Analog Scale (VAS) scores at up to 3 months, as well as the WOMAC scores up to 6 months, compared with baseline scores. There is limited data on contralateral steroid injections and its impact on surgical site infection or PROMs.

It is estimated that from 6.5% to 20% of patients report early dissatisfaction after knee replacement surgery. Furthermore, having bilateral OA is a known risk factor for dissatisfaction among patients who undergo TKA. Residual pain, limited function and limited range of motion are primary factors in patient satisfaction after undergoing TKA. Therefore, improved pain control in the contralateral knee is hypothesized to play a role in improving patient satisfaction after a TKA on the opposite side, in addition to helping with the post-operative rehabilitation process.

Understanding whether contralateral steroid injections confer superior functional and/or patient reported outcome measures after a TKA is critical to enhance patient care and improve patient functional outcomes in OA patients. There is currently a lack of high-quality prospective trials investigating the use of contralateral corticosteroid injections for TKA outcomes.

The COSTI trial (Contralateral Steroid Injection in Total Knee Arthroplasty) was developed to fill this knowledge gap. We propose a prospective, triple-blinded (patient, surgeon and outcome assessor), randomized controlled trial comparing contralateral corticosteroid knee injections versus placing a band-aid (control) in patients with bilateral osteoarthritis undergoing a TKA for osteoarthritis.