Metallosis after contemporary metal-on-metal total hip arthroplasty. Five to nine-year follow-up.

BACKGROUND: Authors of recent studies have reported early periprosthetic osteolysis in patients who have been treated with a contemporary metal-on-metal total hip arthroplasty and have suggested that metal hypersensitivity associated with an immunologic response to metal may be of etiologic importance. We evaluated the results and histologic findings in patients who had undergone revision of a failed contemporary metal-on-metal total hip arthroplasty. METHODS: Two hundred and seventeen total hip arthroplasties (SL-Plus stem and Bicon-Plus cup) with a Sikomet metal-on-metal articulation were implanted in 194 consecutive patients, and the results were retrospectively reviewed at a mean of seventy-seven months postoperatively. Clinical follow-up with the Harris hip score and plain radiographic evaluation were performed. Periprosthetic tissues from fourteen hips that had undergone revision arthroplasty were subjected to histologic analysis. RESULTS: The mean Harris hip score improved from 45 points preoperatively to 88 points at the final evaluation. Fourteen hips (6.5%) were revised: nine because of aseptic loosening, two because of technical failure, and three because of septic failure. Histologic examination of the retrieved periprosthetic tissues from the eleven patients who had undergone revision because of aseptic loosening or technical failure showed metallosis and extensive lymphocytic and plasma-cell infiltration around the metal debris. With removal of the component because of aseptic loosening as the end point, survivorship was 93% for the stem and 98% for the cup. CONCLUSIONS: Our findings are in agreement with those in recent publications and support the possibility that periprosthetic osteolysis and aseptic loosening in hips with a metal-on-metal articulation are possibly associated with hypersensitivity to metal debris. Prospective, comparative, randomized long-term studies are necessary to determine the cause(s) of loosening of prostheses with this particular articulation.

Posterior compact Cotrel-Dubousset instrumentation for occipitocervical, cervical and cervicothoracic fusion.

The authors report on 32 consecutive patients with instability at the craniocervical, cervical and cervicothoracic regions suffering from various pathologies, who were treated with posterior instrumentation and fusion using the posterior hooks-rods-plate cervical compact Cotrel-Dubousset (CCD) instrumentation alone or, in three patients, in combination with anterior operation. The patients were observed postoperatively for an average of 31 months (range 25-44 months) and evaluated both clinically and radiographically using the following parameters: spine anatomy and reconstruction, sagittal profile, neurologic status, functional level, complications and status of arthrodesis. All patients but one (who died) achieved a solid arthrodesis based on plain and flexion/extension roentgenograms. Cervical lordosis (skull-C7) and cervicothoracic kyphosis (C7-T2) was improved by instrumentation towards a physiological lateral curve by an average of 33% (P<0.05) and 28% (P<0.05) respectively. Anterior vertebral olisthesis was reduced in the craniocervical and cervicothoracic region, by 73% and 90% respectively. At final follow-up there was an improvement of the neurologic Frankel status by an average of 1.2 grades and of myelopathy in 75% of the operated patients. Good to excellent functional results were seen in 77% of the operated patients, while acute and chronic pain was reduced by an average of 2.4 grades, on a scale of 0-3, in operated patients. No neurovascular or pulmonary complications arose from surgery. There was no significant change in lateral spine profile and olisthesis at the latest follow-up evaluation. There were no instrument-related failures. One patient requested hardware removal in the hope of reducing postoperative pain in the cervicothoracic region. The poor and fair results were related to the lack of improvement of neurologic impairment and myelopathy. The results of this study demonstrate that cervical CCD instrumentation applied in the region of the skull to the upper thoracic region for various disorders is a simple and safe instrumentation that restores lateral spine alignment, improves the potential for a solid fusion and offers sufficient functional results in the vast majority of the operated patients. However, the use of hooks in spinal stenosis is contraindicated.

Treatment of dysplastic and congenitally dislocated hips with the Zweymueller total hip prosthesis.

Uncemented Zweymueller total hip prostheses were implanted in 35 dysplastic or dislocated hips in 33 patients. Sixteen hips were dislocated and 19 hips were dysplastic; in 12 hips, an intertrochanteric or pelvic osteotomy was performed in early childhood. In all cases, the titanium screw socket was implanted at the level of the original cotyloid cavity. Osteotomy of the greater trochanter, shortening osteotomy, or roof acetabuloplasty were not performed. In cases in which the femoral cavity was too narrow for the Zweymueller stem, an anterolateral longitudinal window-shaped osteotomy was performed. In cases of severe dysplasia, cotyloid cavity bone grafts from the resected femoral head were placed medially to reinforce the acetabular bottom. Clinical and radiographic follow-up ranged from 3-8 years. Average Harris hip score improved from 47 points preoperatively to 86.2 points postoperatively. Complications included two primary anterior dislocations, two temporary femoral nerve pareses, and two deep vein thromboses. At longest follow-up evaluation, no revision was indicated in any of the hips. Satisfactory results in this series were attributed to careful patient selection, precise preoperative radiographic planning, and an operative technique that included implantation of the socket at the primary acetabulum and achievement of primary stability using press-fit fixation.

Prediction of thoracic kyphosis using the Debrunner kyphometer.

The Debrunner kyphometer is an accepted tool for detecting and evaluating thoracic kyphosis. This prospective study was conducted to create a mathematical formula that provides, with high approximation, the roentgenographic angle of thoracic kyphosis (T4-T12) using only the kyphometer. Several clinical (kyphometer value, age, and sex) and radiographic (Cobb angle [T4-T12]) parameters from 90 consecutively screened adolescents (44 male and 46 female) were correlated using simple and multiple linear regression analyses. The reliability of measurement using the Debrunner kyphometer was high. The kyphometer value was strongly correlated with the roentgenographically measured thoracic Cobb angle (simple linear regression analysis; probability range, 0.0026 to 0.0002). There was no correlation between age or sex and thoracic kyphosis. The predicted kyphosis angle using the kyphometer and the mathematic formula was 44.66 degrees +/- 2.68 degrees, (range 27 to 62 degrees), and the real roentgenographic kyphosis angle was 47.5 degrees +/- 3.53 degrees, (range, 24 to 70 degrees). The kyphometer and formula were more reliable and accurate when kyphosis less than 50 degrees was measured. In this study, the authors constructed a mathematical formula that accurately provides the roentgenographic T4-T12 kyphosis angle in adolescents using only the Debrunner kyphometer with a deviation of less than 3 degrees. The authors recommend that all physicians engaged in kyphosis screening programs use the kyphometer combined with the recently constructed simple mathematic formula. This method will reduce the cost of school screening programs, overdiagnoses, and unnecessary exposure of adolescents to irradiation.

Unilateral psoas abscess following posterior transpedicular stabilization of the lumbar spine.

A case of unilateral psoas abscess in a 58-year-old patient, shortly after posterior lower spine stabilization and fusion for spinal stenosis using transpedicular spine fixation is reported. The diagnosis was delayed because the patient's symptoms were referred to the thigh and the plain roentgenograms were negative for pathology. The technetium scintigram and computed tomography (CT) helped localization, diagnosis and treatment of the psoas abscess. Percutaneous CT-guided drainage was followed by recurrence of the abscess, and open surgical evacuation was performed successfully in combination with antibiotic treatment for 8 weeks. Psoas abscess should always be suspected when recurrent pain is associated with fever and elevated erythrocyte sedimentation rate after instrumentation of the lumbar spine. Hardware of a low profile and volume should be used to decrease dead space in the fusion area, and the volume of bone substitutes should be limited for the same reason.

Mueller roof reinforcement rings. Medium-term results.

Short term results of cemented acetabular reconstruction with the use of the Mueller reinforcement ring in 30 hips in 29 patients have been reported previously. The indications for reinforcement were primary and postrevision segmental, cavitary, and combined acetabular deficiencies. The current study reports the medium term clinical and radiologic results of 20 of the 29 patients who were surgically treated (18 primary and eight postrevision hips) and who underwent followup with detailed clinical and radiographic analysis within an average of 9 years (range, 7-12 years). In the latest followup, there has been a statistically insignificant decrease in clinical scores compared with those obtained immediately after surgery; the changes probably are a result of the patients' aging. The radiologic scores at the latest followup were lower, although not statistically significant, than those at the short term followup. The causes of the three ring failures that occurred 5, 8, and 8.5 years after surgery and required revision arthroplasty were either acute trauma or tuberculous arthritis. Three additional hips (two primary and one revision) had evidence of loosening in the ring and socket associated with symptomatology and were considered as hips with impending revision. The rate of success of primary implantation was 94% at 7 years, 86% at 10 years, and 86% at 12 years and was not statistically different from that of revision implantation, which was 86% in all three followup periods. In this small series this surgical technique was successful and effective and followed by good medium term clinical and radiographic results in primary and revision implantation in segmental, cavitary, or complex acetabular deficiencies and in osteoporotic or deficient acetabular bone.