Abstract
Purpose: The objective of this study was to observe the change in dislocation rate by introducing a capsular enhanced short external rotator repair during primary total hip arthroplasty.
Dislocation after primary total hip arthroplasty is a relatively common complication. The incidence is usually between 1% and 4%, although 0% to 10% has been reported in the literature. The posterior approach is by far the most popular by surgeons, but it reportedly has an increase risk of post-operative dislocation. The posterior approach causes disruption of the posterior capsule and the short external rotators. Studies have shown that repair of the posterior capsule and the short external rotators greatly reduce the dislocation rate.
Method: Review of the dislocation rate of THR’s by a single surgeon before and after the introduction of a capsular enhanced short external rotator repair (August 2002). It was a sequential cohort of 2213 Total Hip Replacements (THR), inserted over a period from January 1999 to June 2004. All cases were done by the senior author through a posterior approach using a Belfast custom stem, a 28mm head, and a cementless socket. We collected data on all dislocations which occurred on the hips inserted during this time period. We were therefore able to compare dislocation rates for THR’s done before and after the introduction of the soft tissue repair. The posterior capsule and short external rotators were reattached to the greater trochanter through drill holes using a number 5 Ethibond.
Results: This dislocation rate before the introduction of the new posterior soft tissue repair was 3.9% (58 out of 1501 THR’s). After the introduction of the repair the dislocation rate was 0.9% (6 out of 712 THR’s). 81% (47 of58) of dislocations before the change of practice were classed as early dislocations (with 3 months of surgery). 83% (5 of 6) were clearly dislocators after the new soft tissue repair. Considering only the early dislocations, the dislocation rate reduced from 3.1 to 0.7%.
Conclusion: Considering our reduction from 3.9% to0.9%, and results of previous studies, it is clear that the capsular enhanced and short external rotator repair is associated closely with a decreased dislocation rate. We feel other factors such as restoration of joint centre ensuring correct orientation of components are important in conjunction with the posterior soft tissue repair to keep dislocations to a minimum.
The abstracts were prepared by Emer Agnew. Correspondence should be addressed to Irish Orthopaedic Association, Secretariat, c/o Cappagh National Orthopaedic Hospital, Finglas, Dublin 11, Ireland.
