TOTAL HIP ARTHROPLASTY DISLOCATION NEEDING OPEN TREATMENT

Abstract

The author reviewed 10 patients with irreducible or unstable Total Hip Arthroplasty (THA) dislocation. After clinical and radiological assessment an attempt was made to classify these cases based on the radiological findings and anatomical derangement and review of the literature. The purpose of this study was to correlate the cause of dislocation and the treatment.

The material consisted of ten cases of irreducible or unstable THA dislocation seen in the Healthcare Hawke’s Bay Hospital, Hastings, between 1995 and 2000. The mechanism of dislocation was either bending to put on socks or shoes, twisting injury pivoting on the leg or slipping in the shower. These patients had been treated by different surgeons and had various types of implants. All 10 were female and presented with pain, limp, shortening or deformity. Patients were categorised into:

1. Irreducible dislocation:

   1. Dislodgement of the stem

   2. Dislodgement of the cup

   3. Disassociation of the liner or head in a modular system

   4. Soft tissue interposition: Capsule, tendon

   5. Miscellaneous: Cement interposition; Pseudoaneurysm, Myositis ossificans

2. Unstable Dislocation:

   1. Subsidence of the stem

   2. Cup migration

The incidence of dislocation, not an uncommon complication, has been reported to be 1.5% following primary THA. One-third may develop recurrent dislocation. Most of the reports in the literature are on the incidence and causes of dislocation. They include cup malposition, trochanteric migration, decreased femoral offset, inappropriate head size, leg length discrepancy, surgical approach and postoperative mobilization. Closed reduction can usually be easily achieved under sedation or general anesthesia. Very rarely, the hip joint cannot be reduced.

The author discusses his experience with irreducible dislocation and tries to classify its different causes and to the best of his knowledge, there is no classification of irreducible dislocation according to the anatomic-radiological findings in the literature. The treatment depends on the type of dislocation and is discussed under the specific types of irreducible dislocation.