The effects of cementless femoral stem shape and proximal surface texture on 'fit-and-fill' characteristics and on bone remodeling.

We measured the post-operative radiological "fit and fill" of two different femoral stem designs, one with a straight proximally porous-coated (Bi-Metric, n=50) and the other with a proximally anatomic, hydroxyapatite-coated and distally over-reamed stem (ABG, n=26). A comparison was then made between the clinical and radiological 5-year follow-up data of these two series and also of the bone remodeling changes around the stems. The observed differences in "fit and fill" parameters in the metaphyseal region were minute. However, in the diaphyseal bone the straight stem had substantially more cortical contact. The clinical results were excellent for both groups. Subsidence (>2 mm) was more frequent with the anatomical ABG stems, although the ABG stems had better bone ingrowth in the lower metaphyseal area. The present results indicate that the anatomical design may improve the fit and fill of a femoral stem in the metaphysis. On the other hand, a looser fill of the diaphyseal bone made the stems of this type more susceptible to subsidence. The straight stem with tight diaphyseal fit showed excellent stability, but the good bone ingrowth and remodeling around the distal part of the stem indicates stress transfer through this region and increased stress shielding of the proximal metaphyseal femur.

The results of operative resection of the lateral end of the clavicle.

Seventy-three patients had operative resection of the lateral end of the clavicle for the treatment of a painful condition of the acromioclavicular joint. Thirty-two of the patients had had a traumatic separation of the acromioclavicular joint, eight had had a fracture of the lateral end of the clavicle, and thirty-three had primary acromioclavicular osteoarthrosis. An average of sixteen millimeters (range, fine to thirty-three had primary acromioclavicular osteoarthrosis. An average of sixteen millimeters (range, five to thirty-seven millimeters) was resected; the amount was similar in each of the three groups. The patients were evaluated an average of nine years (range, four to sixteen years) after the operation. The result was considered good in twenty-one patients, satisfactory in twenty-nine, and poor in twenty-three. A poor result was more common in the patients who had had a fracture of the lateral end of the clavicle (p<0.01). Forty-six patients reported pain with exertion, and thirteen noted pain at rest. Eighteen patients had a decrease in the strength of the involved upper extremity, and sixteen had some limitation of the mobility of the shoulder. Elevation of the lateral end of the remaining part of the clavicle as compared with the scapula was noted in eighteen patients and was more likely to be associated with pain (p<0.05). The extent of the resection was significantly associated with pain; patients who had had a smaller amount of resection (ten millimeters or less) had less pain than those who had had a larger amount (p<0.03). A good result was more common in the patients in whom less than ten millimeters had been resected and who had had a previous traumatic separation of the acromioclavicular joint or had primary acromioclavicular osteoarthrosis. We recommend that resection of the lateral end of the clavicle be considered with caution for patients who have severe post-traumatic or degenerative osteoarthrosis of the acromioclavicular joint. If resection is performed, it should not exceed ten millimeters.

Survival of the Lubinus hip prosthesis. An eight- to 12-year follow-up evaluation of 444 cases.

The Kaplan-Meier survival method was used to analyze 444 Lubinus arthroplasties in 398 patients who were observed between eight and 12 years. The indication for arthroplasty was osteoarthrosis in 316 hips, rheumatoid arthritis in 84 hips, and various other conditions for the other 44 hips. Survival was determined for the entire prosthesis, as well as separately for the femoral stem, the acetabulum cup, and their four subgroups. Four patient-related variables (diagnosis, gender, age, and weight) were analyzed. The overall survival of the Lubinus implants was 97.1% at five years and 87.1% at ten years. No significant difference in survival was found between the acetabular and femoral components. Survival was not significantly better with a new anatomic (SP1) stem than with the old curved one (IP). Of the four patient-related variables studied, only diagnosis and age had a significant effect on prosthesis survival. There was no difference in survival between osteoarthrosis and rheumatoid arthrosis hips, but survival was clearly poorer at ten years in the miscellaneous diagnosis group. The authors obtained a significantly lower survival percentage for patients younger than 65 years of age than for those 65 years and older. There were no deep postoperative infections in this series. The revision rate was 11.5%. The wear seen at the lower front edge of cups that were removed is discussed.

Failures after revision hip arthroplasties with threaded cups and structural bone allografts. Loosening of 13/18 cases after 1-4 years.

Uncemented threaded, smooth cup acetabular components and structural deep-frozen bone allografts harvested from femoral heads during arthroplasties were used for reconstruction of the acetabulum in 18 revision hip arthroplasties. Autogenous bone grafts were also used in every case. The mean follow-up time was 2.5 (1-4) years. Loosening of the prosthetic component occurred in 13 cases. In 8 cases revision of the acetabular component has already been performed, and 5 cases remain to be reoperated. The use of uncemented, threaded cups in combination with reconstruction of bone defects with structural allografts cannot be recommended in acetabular revisions.

Revision of cemented hip arthroplasties. 101 hips followed for 5 (4-9) years.

101 hips were revised with cemented Lubinus prostheses after failed primary cemented arthroplasty, and followed for 5 (4-9) years. Radiographically, 41 hips (36 femoral stems and 13 acetabular components) had become loose. The use of an intramedullary plug at the revision did not prevent sinking of the prosthesis. No difference was found between conventional or pressure-injection cementation techniques. In cases where the stem was inserted in varus or the acetabular component was in malposition there was increased loosening. Patients below 50 years of age had oftener more than 5 mm sinking of the stem and more prosthesis loosenings.

Methodology for restoring functional leg length in revision total hip arthroplasty.

Functional leg length was measured in 30 patients before and after revision total hip arthroplasty. The authors emphasize the importance of preoperative planning, and determination of adjustment of the leg length should be aimed at a balanced attitude of the entire pelvis and lower back. In order to correct the length inequality, the leg was lengthened in the revision in 25 cases, left unchanged in 2 cases, and shortened in 3 cases. The mean functional leg-length inequality was 13 mm before operation and 4 mm after operation. The mean radiographic inequality between the upper surfaces of the iliac crest was 13 mm before operation and 9 mm after operation. The side operated was more often functionally shorter than the other side before operation, and longer than the other side after operation. The authors emphasize the importance of functional leg length in revision hip arthroplasty. The functional length discrepancy can be corrected in revision, but there appears to be a risk of overlengthening.

Revision of aggressive granulomatous lesions in hip arthroplasty.

Fourteen patients had revision arthroplasty for aggressive granulomatosis in 16 previously replaced cemented total hips. The revision was performed on average 8 years (range, 6-13 years) after the primary arthroplasty. Twelve patients had multifocal granulomatous lesions. Pain was the first clinical sign of the aggressive granulomatosis, beginning on average 1.7 years (range, 0.8-3.8 years) after the primary operation. One patient had a fracture of the femur due to large granulomas while waiting for revision. The patients were under follow-up evaluation for an average of 5.4 years (range, 4-7 years) after revision. Two patients had recurrence of aggressive granulomatosis at the original sites 4.5 and 6.5 years after revision. Eleven patients had good or excellent results of revision.