[Morbidity and reliability of total hip implants positioning using the posterior minimally invasive approach: a consecutive series of 100 cases].

PURPOSE OF THE STUDY: We wanted to determine whether the minimally invasive posterior approach for total hip arthroplasty leads to defective implant positioning or specific complications.

MATERIAL AND METHODS: One hundred total hip arthroplasties were performed in 98 patients via the posterior minimally invasive approach using a specific instrumentation between June 2003 and January 2004. All operations were performed by the same surgeon. The series included 59 men. Mean patient age was 61 years (range 25-83) and the mean body mass index as 26.1 kg/cm2 (14.1-40.7).

RESULTS: Mean length of the incision was 65 mm (range 45-80 mm). Mean operative blood loss was 393 ml. The VAS decreased from 2.6 on day 1 to 1.0 on day 5. The Harris score rose from 54.5 preoperatively to 85.6 six weeks postop. Mean cup abduction was 43.6 degrees and mean anteversion 16.4 degrees . The center of the hip was restituted within 5 mm in 91% of hips. Stem alignment was 0.8 degrees varus. The femoral offset and the overall hip offset were restituted within 10 mm in 88% of hips. There were no leg length discrepancies greater than 15 mm. Two patients required in addition cup fixation intraoperatively due to acetabular fracture and cup instability. There was one vertical fissuration at the lower end of the stem on one postoperative x-ray. There were no infections nor vascular or neurological lesions. Early dislocation occurred in one 78-year-old patient. There were no revisions for complications.

DISCUSSION: Total hip prosthesis implanted via the minimally invasive posterior approach is a difficult operation. Despite the use of specific instruments adapted to this limited approach, the method appear to be safe and to provide reliable results. If the incision has to be widened in a given patient, use of a familiar approach would be advisable. Experience and use of specific instruments enables proposing this technique for the majority of first intention total hip arthroplasties.