[Early primary total hip arthroplasty for acetabular fractures in elderly patients].

PURPOSE OF THE STUDY: The aim of this pilot study was to evaluate the clinical and functional outcomes of total hip arthroplasty (THA) in patients with acetabular fractures due to a low-energy injury. Acute primary THA included an antiprotrusion cage and autologous bone grafting of the acetabulum. This prospective study was carried out between 1998 and 2004.

MATERIAL: Ten patients, of whom six were men, (average age, 71 years; range, 60 to 83 years) with acetabular fractures were treated by THA. Two patients had type A2, two had type B1, three had type B2 and three had type B3 fractures, as assessed by the AO classification. X-ray showed osteoporosis due to decreased bone mass in all patients, and dislocations of the fragments in the weight-bearing area of the joint exceeded 1 cm. The average follow-up was 36 months.

METHODS: Indications for primary THA included, in addition to higher age, displacement in the fracture line exceeding 1 cm, a fracture line extending to the weight-bearing part of the acetabulum, presence of hip arthritis, cartilage injury, defects of the weight-bearing area of either the femoral head or acetabulum, and Pipkin type IV injury. The interval between accident and surgery ranged from 6 to 12 days (average, 9.5). Three surgical techniques were used, namely, cemented THA with a polyethylene cup cemented into an acetabulum-stabilizing cage; reconstruction with a cementless RSC acetabular component; internal fixation using screws and a cemented cup. Bone grafting of the acetabulum was used in all patients. Evaluated were basic operative parameters, complications, X-ray findings, ability to walk and Merle d'Aubigne scores.

RESULTS: The average operative time was 100 min, the average blood loss was 1000 ml. Hip motion showed the following average values: flexion, 110 degrees ; extension, 10 degrees ; rotation, 30 degrees -0 degrees -30 degrees ; adduction, 25 degrees ; abduction, 35 degrees . All patients returned to their preoperative range of motion. X-ray examination showed good reduction, bone graft was completely incorporated in the acetabulum, and no displacement or signs of loosening or graft migration were recorded. Two patients had Brooker type I heterotropic ossification. The final evaluation of function at 36 months on the basis of the Merle d'Aubigne classification showed excellent and good results in four (57 %) and three (43 %) patients, respectively. The remaining three patients had a shorter follow-up, but were fully mobile with no complications observed.

DISCUSSION: It has been reported that bony union of acetabular fracture after open reduction and internal fixation (ORIF) was achieved in 74 % patients younger than 60 years, but in only 44 % of the patients older than 60 years. Secondary THA following ORIF is a demanding technique. Due to adhesions and a frequent malposition of the acetabulum, THA is associated with and increased risk of infection, tendency to develop para-articular ossifications, and a higher risk of early component loosening than in the standard procedure. One of the options is to perform acetabular stabilization and primary THA at one stage. The results of our study are fully in agreement with those reported for THA in hip arthritis or dislocated fracture of the femoral neck.

CONCLUSIONS: Acute primary THA with the use of a antiprotrusion cage and bone grafting for acetabular fractures in elderly patients allows us to employ only one surgical technique for definitive repair. It provides primary stability and immediate pain relief, permits graded weight-bearing and early pain-free mobilization, and may also treat hip arthritis, if it exists. This technique has also good prospects for a selected group of younger patients in whom the treatment of acetabular fractures has a poor prognosis. Key words: acetabular fracture, elderly patient, primary total hip arthroplasty.