There is a surge of patients on the waiting-list for primary total hip replacement (THR), due to unprecedented reduction of elective activity caused by COVID-19. A higher incidence of femoral head collapse (FC) and acetabular erosion (AE) leading to increase in pain and instability as well as requirement of more complex surgery and potentially higher risk to patients was noted in this period. Rapidly progressive Arthritis (RPA) of the hip is a known entity often described as progression of joint space narrowing greater than 2mm over one year time period. The study aims to identify any potential relationship between waiting time and establishment of femoral head collapse and/ or acetabular erosion. A retrospective review of arthroplasty surgeon's waiting list during COVID. Serial hip radiographs recorded between February 2020 and February 2022 were analysed. FC was quantified as a percentage of the femoral head radius, while AE was assessed by drawing two parallel lines, one through both tear drops and the other through superior most aspect of intact acetabulum, parallel to the inter tear-drop line and expressed as percentage of normal side. Only 105 patients out of 264 patients added to the waiting list had elective arthroplasty for hip/knee. Only 35 patients out of 90 listed for THR, had the surgery. 36 of 90 (40%) were found to have developed FC and fitted the criteria for RPA. Acetabular erosion was seen in 19 (21%). Therefore 53% (19 of 36) of those who developed FC progressed to AE. Incidence of collapse was higher in females (32%), with mean age of 62 (range 51–81), compared to 21% in males with mean age 59 (range 53–87). Mean extent of femoral head collapse was 20% (10 – 44%). A significant proportion of patients added to waiting list during COVID developed RPA of the hip with 40% having femoral head collapse and 21% progressing to acetabular erosion leading to a complex case-mix. Patients on long waiting lists need regular x-ray checks/PROMS since significant proportion progress to FC and Acetabular Erosion.
