Background/Purpose:

 Unmet patient expectations of total knee replacement (TKR) correlate with postsurgical dissatisfaction, and are linked to outcomes. Patients with rheumatoid arthritis (RA), may have lower expectations than patients with osteoarthritis (OA), due to the systemic nature of the disease and its other manifestations such as fatigue. Biologic DMARDs enhance RA patient quality of life. The effect of pre-operative use of these medications on patient expectations and outcomes of TKR is not known.  The purpose of this study was to assess the correlation of preoperative expectations with TKR outcomes in RA patients on biologics and those not on biologics, compared to matched OA patients undergoing TKR.

Methods:

Validated RA patients were identified from an institutional TKR registry and their use of biologics was recorded from chart review. RA patients were matched to OA patients on age, sex, prior TKR, and preoperative activity level using the Lower Extremity Activity Scale (0-18, 18 highest level of activity). Preoperative patients completed the validated Hospital for Special Surgery (HSS) Knee Expectations Survey (19 items, score range 0-100, 100 is highest expectation). At 2 years, patients completed the WOMAC pain and function. Preoperatively, expectation scores between RA patients on biologic DMARDS, conventional therapy and matched OA patients were compared.  We used regression to determine the association between expectation scores and 2-year WOMAC pain and function subscale scores, adjusted for baseline score.

Results:

One hundred fourteen RA cases, 46.5% on biologics, were matched to 228 OA cases. The RA cases were 11.8% male and the average age was 62.6 +/-12.2 years. The average pre-operative LEAS score was 8.3 +/-2.9, which corresponds to being able to walk around the house and walk for several blocks at a time without any assistance. 16.7% of the patients had a prior contralateral TKA.  The mean duration of RA was 19.7 +/- 13.4 years. RA patients on biologics had expectations similar to matched OA patients (total expectation score 76.3 ± 8.1 vs. 77.4 ± 17.4, p = 0.71), while RA patients not on biologics had expectations that were clinically and statistically significantly lower (69.9 ± 22.4 vs. 77.1 ± 19.0, p-value = 0.03). Higher expectations scores were associated with better 2-year WOMAC function and pain scores (2-year WOMAC pain coefficient=0.393, p-value<0.001, 2-year WOMAC function coefficient=0.441, p-value<0.001) in RA patients not on biologics therapy but not in RA patients on biologic DMARDS (2-year WOMAC pain coefficient=-0.126, p-value=0.426, 2-year WOMAC function coefficient=0.005, p-value=0.977) nor matched OA patients (2-year WOMAC pain coefficient=-0.037, p-value=0.614, 2-year WOMAC function coefficient=0.060, p-value=0.460).

Conclusion:  

Expectations of post-operative outcomes are only significantly related to post-operative pain and function in RA patients not on biologic DMARDS; there is no relation in RA patients on biologics or in OA patients. The reasons for this are unclear, and whether this is due to unrealistic expectations in OA and RA patients on DMARDS or that biologics reduces the need to manage expectations needs to be explored.