Background/Purpose: Osteoarthritis (OA) is the most common form of arthritis, and is the major source of joint pain and disability. The aim of the study was to estimate the percentage of non-responders to total joint replacement therapy (TJR) in OA (hip and knee) patients and identify factors and biomarkers that associated with it.

Methods: TJR patients due to OA were recruited at the surgery and followed up for 4 years on average. The WOMAC pain and function subscales at pre- and post-surgery were used to assess the improvement of joint pain and function. Based on the minimal clinically important difference (MCID), participants were classified as non-responders if the change score of less than 7 points (of 20 points total) for WOMAC pain subscale from pre-surgery to post-surgery. For physical function, participants were non-responders if the change score was less than 22 points (of a total of 68) from pre-surgery to post-surgery. Metabolic profiling (186 targeted metabolites) was performed on plasma samples collected at baseline. Demographic and medical information was collected systematically using standardized questionnaires.

Results: A total of 242 TJR patients were included, 20% were hip replacements and 80% were knee replacements. 42% of them were males and 58% were females. Mean age was 65.6 ±7.4 years old. 16.5% of the study participants were classified as non-responders to TJR, as they failed to reach MCID for pain. A similar percentage for non-responders was noted for physical function. There was no difference between knee and hip replacements. About 63% of the non-responders as defined by pain score were also non-responders in physical function. No association was noted between the non-responders in pain and physical function and clinical epidemiological factors including age, sex, BMI, and comorbidities (cardiovascular disease, metabolic related disease, and cancers). However, four amino acids – histidine, sarcosine, phenylalaine, and serine levels were significantly associated with non-responders in physical function (all adjusted p values (FDR)<0.05). Phenylalanine level was also associated with non-responders in pain although the significance didn’t pass the multiple testing adjustments by FDR (unadjusted p=0.02).

Conclusion: Our data indicated that over 16% of OA patients did not reach MCID from TJR in either pain or physical function and non-responders to TJR were associated with higher levels of several amino acids. While further confirmation is needed, our findings have great potential in the clinical decision-making process when contemplating TJR for knee or hip OA.

« Back to 2017 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/non-responders-to-total-joint-replacement-therapy-in-osteoarthritis-patients-and-novel-metabolic-markers/