Despite a lack of long-term follow-up, there is an increasing trend towards using femoral heads of large diameter in total hip replacement (THR), partly because of the perceived advantage of lower rates of dislocation. However, increasing the size of the femoral head is not the only way to reduce the rate of dislocation; optimal alignment of the components and repair of the posterior capsule could achieve a similar effect.

In this prospective study of 512 cemented unilateral THRs (Male:Female 230:282) performed between 2004 and 2011, we aimed to determine the rate of dislocation in patients who received a 22 mm head on a 9/10 Morse taper through a posterior approach with capsular repair and using the transverse acetabular ligament (TAL) as a guide for the alignment of the acetabular component. The mean age of the patients at operation was 67 years (35 to 89). The mean follow-up was 2.8 years (0.5 to 6.6). Pre- and post-operative assessment included Oxford hip, Short Form-12 and modified University of California Los Angeles and Merle D’Aubigne scores. The angles of inclination and anteversion of the acetabular components were measured using radiological software. There were four dislocations (0.78%), all of which were anterior.

In conclusion, THR with a 22 mm diameter head performed through a posterior approach with capsular repair and using the TAL as a guide for the alignment of the acetabular component was associated with a low rate of dislocation.

Cite this article: Bone Joint J 2014;96-B:1202–6.

Objectives: Dislocation is one of the common complications of total hip Arthroplasty. Posterolateral approach and small femoral heads have been shown to be high-risk factors for dislocation of the implanted total hip prosthesis. The use of a posterior capsulorraphy has also shown to decrease the rate of dislocation with a posterolateral approach. The objective of this study was to evaluate the early dislocation rate using size 22 mm head and a Posterolateral approach augmented with a posterior capsulorraphy.

Methods: Questionnaire and case notes review of 148 patients operated at one institution by 3 different senior surgeons from Aug’03 to Jan’05. A posterior capsulorraphy was performed in all the patients. The primary outcome measure was the dislocation of the prosthetic hip within the first year of surgery.

Results: 4 of the 148 patients (2.7%) had an episode of dislocation during the first year of surgery. 3 patients were treated conservatively and 1 required operative intervention in the form of PLAD. Radiographic analysis of this patient showed excessive anteversion of the socket(28⁰⁾.

Conclusions: Studies have consistently shown an increased rate of dislocation with a Posterolateral approach and use of a size 22mm head. A recently published study by Berry et.al has shown a 12.1% dislocation rate with the use of this approach and size 22mm head. However posterior capsulorraphy was not performed in patients in this study group. Our study shows that performing a posterior capsulorraphy can reduce early dislocation rates using Posterolateral approach and size 22 mm head. The dislocation rate (2.7%) is comparable to any other approach and the use of a larger head size.

These patients continue to be monitored to evaluate long term outcomes with this approach. (301 words)

We have assessed the long-term results of 292 cemented total hip replacements which were performed for developmental dysplasia of the hip in 206 patients. The mean age of the patients at operation was 42.6 years (15.9 to 79.5) and most (202) were women. The severity of dysplasia was graded according to both the Crowe and the Hartofilakidis classifications. A 22.25-mm Charnley head was always used and the acetabular components were inserted with cement into the true acetabulum. Bone grafting of the acetabulum, using the patient’s own femoral head, was performed on 48 occasions.

At a mean follow-up of 15.7 years (2.2 to 31.2) the overall survival of the acetabular component was 78%. The main cause of revision was aseptic loosening (88.3%). The rate of survival at 20 years based on the Hartofilakidis classification was 76% in the dysplastic, 55% in the low-dislocation and 12% in the high-dislocation groups and on the Crowe classification, 72.7% for group I, 70.7% for group II, 36.7% for group III and 15.6% for group IV. There was no statistical correlation between bone grafting of the acetabulum and survival of the acetabular component. This study has shown a higher rate of failure of the acetabular component with increasing severity of hip dysplasia.