Introduction

Patient dissatisfaction for persistent pain or failing to achieve good clinical outcome is common with approximately 20% of patients reporting dissatisfaction following primary total knee arthroplasty (TKA), despite a mechanically stable knee joint. Patient dissatisfaction after TKA is attributed to several key factors: patient expectations prior to surgery, the degree of improvement in knee function, and pain relief following surgery. In a recent study in our laboratory, synovitis has been shown to be present at both baseline and 1-year post-TKA and associated with pain. However, patient dissatisfaction was not assessed. The persistent synovitis both pre-TKA and post-TKA in the subset of individuals, could potentially explain patient dissatisfaction and pain. Further to this, it is unknown if synovitis is persistent and if it is associated with patient dissatisfaction and adverse outcomes/dissatisfaction (pain, poor functional outcomes, and poor quality of life) post-TKA. The objectives of this research study were to 1) determine the role of synovitis in patients who were dissatisfied ≥2 years post-TKA and 2) to determine if synovitis ≥2 years post-TKA was associated with pain, poor functional outcomes, and poor quality of life.

Methods

Study participants ≥2-5 years post-TKA were recruited. The time point (≥ 2-5 years) post-TKA was chosen as there can be still improvements (pain, stiffness, etc.) in clinical status post-TKA up to 2 years. Satisfied and dissatisfied patients were recruited based off the Knee Society Score Patient Satisfaction rating. A clinical evaluation, ultrasound for synovitis based on the Outcome Measures in Rheumatology (OMERACT) knee OA protocol, patient reported outcome questionnaires (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)), functional assessment (30 second Chair Stand Test (CST)), and pressure pain threshold (PPT) were completed at the study visit. Pearson correlations and Spearman correlations were used to determine associations. Significance for all statistical tests was accepted at p≤0.05.

Results

Sixty-two patients (n=36 satisfied and n=26 dissatisfied) were recruited into the study (55% female, average age 72±6.9 years, mean BMI 31.4±5.0 kg/m2). Satisfaction score was comparable between sexes (p=0.48), BMI (p=0.70), and waist circumference (p=0.13). Satisfaction scores were significantly negatively correlated with WOMAC total scores (r=-0.769; p<0.01), significantly positively correlated with the CST (r=0.589; p<0.01), significantly positively correlated with PPT (r=0.391; p<0.01), and significantly positively correlated with EQ-5D-5L (r=0.455; p<0.01). Satisfaction score post-TKA was not correlated with OMERACT measures of synovitis including overall synovitis grade (rS=0.172; p=0.22), hypertrophy/hyperplasia (rS=0.008; p=0.96), effusion, (rS=0.152; p=0.28), and power doppler (rS=-0.138; p=0.34).

Conclusion

Patient reported pain, stiffness, and poor physical function at 2 years following TKA was directly correlated to decreased patient satisfaction. However, patient satisfaction following TKA (≥ 2-5 years post-TKA) was not correlated to the presence or burden of knee joint synovitis. Patients who were satisfied with their TKA demonstrated improved functional outcomes and PPT (tissue sensitivity). Further characterization of synovitis at a cellular level should be considered in future studies.