Abstract
Introduction
Traditionally it has been thought that the use of a small diameter femoral head in conjunction with a posterior surgical approach would result in a high rate of dislocation. We present the results of a consecutive series of 350 total hip replacements performed using a 22mm femoral head and a standard posterior approach, with prospective data collection.
Objective
To determine the outcome of total hip replacement using small diameter heads via a standard posterior approach.
Methods
Between March 2000 and April 2005, 319 patients underwent 350 total hip replacements with a small diameter 22mm head under the care of four different consultants, using a standard posterior approach. All patients underwent annual clinical and radiological review.
All of the femoral implants were cemented modular polished triple-tapered C-stems (Depuy Ltd.) and all of the acetabular components were cemented UHMW-polyethylene components with long posterior walls. Palacos-R cement (Heraeus GMBH) containing gentamicin was used in all cases, with a third generation cementing technique. A standard posterior approach was used in all cases, with direct repair of the short external rotators, but without the use of transosseous sutures.
Results
There were 245 female and 105 male patients, with 198 right-sided operations, 152 left with 31 patients undergoing staged bilateral operations. The average age at the time of surgery was 69.2 years (range 25–92 years). Five patients (6 THRs0 were lost to follow-up and 101 patients (29%) died during the study. The average duration of follow-up for surviving patients is 128 months (108 – 169 months).
Five acetabular components have been revised for aseptic loosening associated with a high wear rate, and 4 are currently loose. There were three peri-prosthetic femoral fractures treated by internal fixation, and two temporary nerve palsies.
Four femoral components were revised at the time of revision of a loose acetabulum, but none were loose. There has been no aseptic loosening of any femoral components and there were no cases of deep infection.
The average acetabular abduction angle was 43.2 degrees (30–62) and the average femoral offset was 46mm (35–54).
Five patients suffered dislocations, 3 female and 2 male, 2 right-sided and 3 left. Average age was 70 (60–85), average offset was 44.6mm (40–48). Four occurred on a single occasion only and were stable on reduction and only one required further surgery for recurrent dislocations, with application of a PLAD. Extended, skirted femoral heads had been used in four of these cases, reducing the head/neck ratio (p<0.5).
Conclusions
Total hip replacement using small diameter femoral heads and a posterior approach has provided excellent results and implant longevity, with a low complication rate. Dislocation occurred in five cases and was associated with the use of an extended head. When using a posterior surgical approach the use of extended heads should be avoided, with high offset stems and standard heads being used in preference in order to achieve the correct length and offset, whilst maintaining the maximum head/neck ratio.
