[Surgical principles and clinical experiences with the DUROM hip resurfacing system using a lateral approach].

OBJECTIVE

Objective Bone-preserving hip resurfacing in young and active patients using a soft-tissue-sparing, modified transgluteal, lateral approach.

INDICATIONS

Primary hip osteoarthritis in physically active, working patients aged < 65 years (males) and < 60 years (females). Good bone quality.

CONTRAINDICATIONS

Male patients > or = 65 years of age, female patients > or = 60 years of age. Necrosis of the femoral head. Varus deformity of the femoral neck with a reduced horizontal femoral offset. Femoral head cysts (> 1 cm in diameter). Infection. Osteoporosis. Rheumatoid arthritis. Tumor. Reduced renal function. Leg length difference (> or = 1 cm). Metal allergy. Previous femoral neck fracture. Previous intertrochanteric femoral osteotomies.

SURGICAL TECHNIQUE

Supine position of the patient. Modified transgluteal, lateral approach to the hip joint. Luxation of the femoral head. First, reaming of the femoral head to improve visualization of the acetabular cup. Central positioning of the guide wire in the femoral neck in a slight valgus position of approximately +5 degrees to the anatomic collodiaphyseal (CCD) angle using the mechanical targeting device. Overdrilling of the central guide wire to the appropriate depth for the implant. Central insertion of the guide rod. Preparation of the femoral head over the guide rod using cylinder cutters one or two sizes larger than the smallest possible femoral component. Cement-free implantation of the acetabular component according to the predetermined definitive size of the femoral component. Final preparation of the femoral head using profile, surface and forming cutter. Following cemented implantation of the femoral component, repositioning of the hip joint and conclusion of the surgical procedure.

POSTOPERATIVE MANAGEMENT

Mobilization of the patient using two forearm crutches as of the 1st day after surgery. Removal of the Redon drains after 24 h. Partial weight bearing of 20 kg for 3 weeks under continuation of thrombosis prophylaxis. Limitation of hip flexion to 90 degrees during the first 6 postoperative weeks, and no adduction and forced external rotation allowed in order to avoid luxation. Avoidance of sports involving the loads of jumping and axial impact loading for 12 postoperative months.

RESULTS

Analysis involved the pre- and postoperative functions of 72 patients with a total of 82 prostheses and a mean durability time of 29.2 +/- 11 months based on the Harris Hip Score (HHS), the modified UCLA (University of California, Los Angeles) activity index, and the Merle d'Aubigné Score. Postoperatively, prosthetic angle and femoral offset as well as periprosthetic signs of loosening/lytic areas were assessed by means of radiology and compared with the preoperative CCD angle and femoral offset. Compared to the preoperative evaluation, follow-up yielded a significant increase in the average HHS values (94 +/- 4.6 vs. 40.1 +/- 7 points), the modified UCLA activity index (8.9 +/- 2.6 vs. 4.6 +/- 2.2), and the Merle d'Aubigné Score (17.9 +/- 1.9 vs. 7.3 +/- 2.4; p < or = 0.05). In 98.8%, a solid osteointegration of the cup and femoral components was observed. The average deviation of the physiological CCD angle (136.6 degrees +/- 3.6 degrees ) from the postoperative angle of the prosthesis (142.6 degrees +/- 4.9 degrees ) was 6 degrees +/- 2.8 degrees . The postoperative femoral offset was reduced by an average of 2.3 mm compared to the preoperative offset. During clinical follow-up n = 2 prostheses (2.5%) required revision (one femoral neck fracture; one periarticular ossification [Brooker III]).