Preoperative Thresholds of Pain and Function to Achieve a Minimal Important Change and Patient Acceptable Symptom State After Proximal Interphalangeal Joint Arthroplasty

Abstract

There is ongoing discussion about the level of symptoms patients with proximal interphalangeal (PIP) joint osteoarthritis should have to undergo surgery. The aims of our study were to determine the minimal important change (MIC) and patient acceptable symptom state (PASS) for PIP joint range of motion (ROM), and define clinically relevant thresholds of preoperative pain and function at which patients have the greatest chance to achieve a MIC and PASS in these outcomes 1 year after PIP arthroplasty. We analyzed registry data that included patients with PIP joint osteoarthritis who underwent an arthroplasty for this condition and had a 1-year follow-up. Patients indicated pain on a numeric rating scale (0-10) and completed the brief Michigan Hand Outcomes Questionnaire (MHQ). Active total PIP ROM was measured. The preoperative thresholds, predictive of achieving the MIC and PASS for each outcome measure of pain, function, and ROM, were determined using receiver operating characteristics curves. We included 196 patients who experienced a relevant improvement in ROM (= MIC) when there was an increase by ≥8° compared with the ROM preoperatively. Patients were satisfied with their postoperative ROM (= PASS) if they achieved PIP mobility of at least 66°. Pain at rest and during activities was predictive for achieving a MIC but not a PASS. Due to an insufficient area under the curve for the brief MHQ and ROM, their baseline values cannot predict the postoperative achievement of MIC or PASS. We suggest that patients with preoperative pain at rest ≥4.5 or pain during activities ≥5.5 have the greatest chance of achieving a subjectively relevant change 1 year after surgery. The determined thresholds may support surgeons in the preoperative process of deciding for or against a surgical intervention and explain the probability of achieving sufficient postoperative symptom relief for the patient. Prognostic I.