NON-CONCENTRIC REDUCTION FOLLOWING SIMPLE HIP DISLOCATIONS AS AN INDICATOR OF INTRA ARTICULAR LOOSE BODIES – A PROSPECTIVE STUDY OF 117 DISLOCATIONS.

Abstract

Background: Intraarticular loose bodies following simple dislocations can lead to early degeneration. Non concentric reduction may indicate retained loose bodies and offer a method to identify patients requiring exploration to avoid this undesirable outcome.

Methods: 117 consecutive simple dislocations of the hip presenting to the hospital from January 2000 to June 2006 were assessed for congruency after reduction by fluoroscopy and good quality radiographs. Patients with non concentric reduction underwent open exploration to identify the etiology and removal of loose bodies. The post operative results were analyzed using Thomson and Epstein clinical and radiological criteria.

Results: 12 of the 117 (10%) dislocations had incongruent reduction which was identified by a break in Shenton’s line and an increase in medial joint space in seven patients, superior joint space in three patients or a concentric increase in two patients. CT scan performed identified the origin of the osteocartilagenous fragment to be from the acetabulum in six patients, femoral head in four, from both in one and one patient had inverted posterior labrum. In addition to this a patient had posterior capsular interposition. Following debridement, congruent reduction was achieved in all patients. At an average follow up of four years and nine months (4.9 years), the functional outcome evaluated by Thompson and Epstein criteria was excellent in 11 cases and good in one case.

Conclusions: Intra articular loose bodies were identified by non-concentric reduction in 12 out of 117 patients with simple hip dislocation. Careful evaluation by immediate post reduction fluoroscopy and good quality radiographs are a must following reduction of hip dislocations.