Editorial: factors influencing the outcome of total hip and knee arthroplasty.

Background: Total hip and knee arthroplasty for end stage arthritis are among the most cost-effective interventions available in all of medicine. Success of hip and knee arthroplasties is not universal and approximately one in ten patients are not satisfied with their arthroplasty and 10 to 34% of patients have an unfavourable long term pain outcome. The aim of this edition of Arthroplasty was to identify factors associated with: (1) poor joint specific outcome, (2) poor health related quality of life outcome and (3) dissatisfaction following total hip and knee arthroplasty.

Methods: The scope was deliberately broad to identify factors (known and unknown) that influence outcome of total hip and knee arthroplasty, and of 40 submissions, eight were selected for this special edition after peer review.

Results: Many of the included studies reported subjective patient reported outcome measures as their key outcomes but other objective measures such as muscle mass, timed Up-and-Go test, kneeling ability and postoperative pain are also featured. Some studies involved a focus on early rehabilitation after surgery (ERAS) principles and how to optimise pre-rehabilitation and reduce length of hospital stay readmission and reoperation. The effect of metal allergy and drain usage on outcomes is also explored. A variety of methodologies have been used including one randomised control trial, some machine learning and three systematic reviews investigating the effect of metal allergy on outcomes, associations with postoperative pain and the effect of patella resurfacing.

Conclusion: This special edition has advanced our knowledge of factors influencing to the outcome of hip and knee arthroplasty but has also identified several areas of research that need to be addressed to improve the outcomes of our patients.