Patient acceptable symptom states after total hip or knee replacement at mid-term follow-up

Objectives: To define Patient Acceptable Symptom State (PASS) thresholds for the Oxford hip score (OHS) and Oxford knee score (OKS) at mid-term follow-up. Methods: In a prospective multicentre cohort study, OHS and OKS were collected at a mean follow-up of three years (1.5 to 6.0), combined with a numeric rating scale (NRS) for satisfaction and an external validation question assessing the patient's willingness to undergo surgery again. A total of 550 patients underwent total hip replacement (THR) and 367 underwent total knee replacement (TKR). Results: Receiver operating characteristic (ROC) curves identified a PASS threshold of 42 for the OHS after THR and 37 for the OKS after TKR. THR patients with an OHS ≥ 42 and TKR patients with an OKS ≥ 37 had a higher NRS for satisfaction and a greater likelihood of being willing to undergo surgery again. Conclusions: PASS thresholds appear larger at mid-term follow-up than at six months after surgery. Without external validation, we would advise against using these PASS thresholds as absolute thresholds in defining whether or not a patient has attained an acceptable symptom state after THR or TKR.