Abstract
Introduction
A recent paper suggested implanting an uncemented acetabular shell which is 6mm or greater than the native femoral head in total hip arthroplasty (THA) significantly increased the risk of postoperative pain. We retrospectively analyzed 265 Delta ceramic-on-ceramic (DCoC) THA comparing the native femoral head size to the implanted shell and reviewing if the patient suffered with post-operative pain (POP).
Methods
265 consecutive THAs were performed using the Corail and Pinnacle prostheses with DCoC bearing. Native femoral head size was calculated retrospectively on pre-operative radiographs using TraumaCad software. All patients were sent questionnaires requesting information on satisfaction, sounds, postoperative pain and complications. Statistical analysis was then undertaken on the data.
Results
Questionnaires were returned by 169 patients (189 hips). 42 patients reported postoperative pain. Patients suffering with pain had an average difference between native head and implanted shell of +6.8mm, compared to those without of +5.4mm. A shell of +6mm larger than the native head was associated with a statistically significant increase in the risk of postoperative pain (P=0.01). Patients with groin pain were more likely to have a smaller native head (46.1 Vs 47.3mm (P=0.046)). Patients with pain were more likely to complain of noisy hips (P=0.001). 70% of patients described being satisfied to the point where they forgot they had a THA. The dislocation rate was 1.1%.
Discussion
A +6mm difference between native head and implanted shell was found to be a significant predictor of postoperative pain. We propose that to reduce the risk of postoperative pain, a limit of +4mm should be used. Overall complications were low and patients were very satisfied with their THA.
