[Comparison of medium-term X-ray imagings between anatomique benoist giraud hip and anatomic medullary lokcing hip]

To compare the bone resorption between the proximal fixation of the anatomique benoist giraud (ABG) hip and the distal fixation of the anatomic medullary locking (AML) hip by the medium-term X-ray films, and to evaluate the clinical results of the two prostheses.

From January 1992 to December 1996, 298 patients (396 hips) underwent the total hip arthroplasty at Wilson Hospital in Korea. In 125 patients, 176 hips were ABG hips, including 103 avascular necrosis hips, 57 dysplasia hips, and 16 other diseased hips; In the other 173 patient the remaining 220 hips were AML hips, including 147 avascular necrosis hips, 65 dysplasia hips, and 8 other diseased hips. The A-P X-ray imagings were followed up for 5-12 years averaged 8 years, and were compared with the immediate postoperative X-ray imagings. The bone resorption area was measured and the bone resorption cases were recorded according to the Gruen zone obsesvation.

During operation, 2 ABG hips and 5 AML hips were cracked at the femoral diaphysis; 3 ABG hips and 1 AML hip were cracked at the metaphysis; 6 ABG hips and 3 AML hips were fractured because of trauma after operation; among them, 2 ABG hips needed the stem revision and the remaining hips underwent the open reduction and the internal fixation. During the follow-up, 9 ABG hips were revised, 7 hips of which developed the aseptic loosening. No AML hip was revised, but 3 AML hips developed the aseptic loosening. The bone resorption pattern in the ABG and AML hips was similar. The bone resorption occurred most commonly in the Gruen zones 1 and 7, and it extended from the metaphysis to the diaphysis. In the Guren zones 2, 5, 6 and 7, there were more AML hips than ABG hips that developed the bone resorption. The bone resorption area around the AML hip was larger than that around the ABG hip.

The stress shielding bone resorption usually occurs proximally to the union area of the bone and the prosthesis. The ABG prosthesis is a proximal fixation prosthesis, therefore, the stress shielding bone resorption can be reduced. The bone resorption around the AML prosthesis develops slowly within 10 years after operation. The stress shielding bone resoption may reach the summit within 10 years and it will not develop endlessly, so the prosthesis will be stable for a long time. The probability of the bone resorption in the ABG prosthesis is smaller than that in the AML prosthesis. The bone resorption around the AML prosthesis may develop slowly after 10 years and will not affect the stability of the prosthesis for a long time.