The effect of different bearing surfaces on metal ion levels in urine following 28 mm metal-on-metal and 28 mm metal-on-polyethylene total hip arthroplasty.

BACKGROUND AND AIMS: Recent advancements in manufacturing technology have enabled more precise tolerances and surface finishes using metal-on-metal bearing surfaces in total hip arthroplasty. The aim of this study was to compare the level of metal ions in urine after implantation of a 28-mm metal-on-metal bearing manufactured from high-carbon wrought alloy and a 28-mm metal-on-polyethylene bearing. MATERIAL AND METHODS: A total of 92 total hip arthroplasty patients were prospectively randomized into two groups: those receiving metal-on-metal bearings and those receiving metal-on-polyethylene bearings. Chromium, cobalt, and molybdenum ion levels in urine were measured preoperatively and at 1 year and 2 years postoperatively. RESULTS: In the metal-on-polyethylene group, there was a slight increase in mean chromium and cobalt concentrations at 2-year follow-up compared to the preoperative level (p = 0.02 for both chromium and cobalt). In the metal-on-metal group, there was a 15-fold increase in chromium and a 26-fold increase in cobalt at 2-year follow-up compared to the preoperative level (p < 0.001 for both chromium and cobalt). However, the quantity of chromium and cobalt in urine from the metal-on-metal group was not higher at 2-year follow-up than at 1-year follow-up (p = 0.5 and p = 0.6, respectively). CONCLUSIONS: The 28-mm metal-on-metal bearings yield chromium and cobalt concentrations in urine that can be higher than those recommended for occupational exposure. However, our results also indicate that a steady state in wear and ion production using metal-on-metal total hip arthroplasty can occur.

Severe periprosthetic osteolytic lesions after the Ankle Evolutive System total ankle replacement.

Between 2002 and 2008, 130 consecutive ankles were replaced with an hydroxyapatite (HA) and titanium-HA-coated Ankle Evolutive System total ankle prosthesis. Plain radiographs were analysed by two independent observers. Osteolytic lesions were classified by their size and location, with cavities > 10 mm in diameter considered to be 'marked'. CT scanning was undertaken in all patients with marked osteolysis seen on the plain radiographs. Osteolytic lesions were seen on the plain films in 48 (37%) and marked lesions in 27 (21%) ankles. The risk for osteolysis was found to be 3.1 (95% confidence interval 1.6 to 5.9) times higher with implants with Ti-HA porous coating. Care should be taken with ankle arthroplasty until more is known about the reasons for these severe osteolyses.

Successful treatment of frozen hip with manipulation and pressure dilatation.

A 44-year old man with prolonged frozen hip was treated with manipulation under anesthesia and pressure dilatation of the left hip joint. The treatment was successful and after one year the hip was symptomless.

Total wrist fusion: a study of 115 patients.

This retrospective study evaluated the outcome of total wrist fusion, predominantly using the Mannerfelt technique, in patients with rheumatoid arthritis. One hundred and fifteen patients were operated on for painful wrist destruction. The mean pain scores were 3.6 (1-4) pre-operatively, 1.9 (1-4) after 6 weeks and 1.3 (1-4) at 1 year. Although the radiological fusion rate was good, only 40% of the patients were very satisfied with the result. Ability to perform activities of daily living was only very much improved in 30% of the patients. Grip strength significantly improved after surgery.

The reliability of diagnosis of infection during revision arthroplasties.

BACKGROUND: Follow up studies have shown that 0.5 to 4% of the total joint arthroplasties will be complicated by infection. Distinction between aseptic loosening and infection is important for prediction of the final outcome after revision arhtroplasty but also for the choice of operative treatment. However, diagnosis of low grade chronic infection is extremely demanding. MATERIALS AND METHODS: 68 hip and knee revision arthroplasties were reviewed retrospectively in order to evaluate the reliability of pre- and perioperative analysis of infection during total joint revision arthroplasties. The sensitivity and specificity for clinical signs, blood white-cell count, C-reactive protein level, radiographic analysis, bone and leukocyte scans, joint aspirations, and gram staining were determined. Tissue sample were harvested and cultured in all cases. Positive cultures were regarded as a true infection. RESULTS: We were not able to characterize the infection by clinical signs. Also no single test was able to show the presence of infection in all cases. The best results were obtained from pre- and perioperative joint aspirations. Joint aspiration showed 1.0 specificity and 0.75 sensitivity. CONCLUSION: It is clear from this study that no single test is able to show the presence of infection in every case. Classical clinical signs, laboratory tests, special imaging studies and joint aspirations have all yielded a notable rate of false negative results. Therefore, we recommend that, if arthroplasty patients have pain in prosthetic joint without clear radiological evidence of loosening, bone scans and preoperative joint aspirations should be undertaken. Also, if radiological evidence of loosening is accompanied with one or more of following criteria; C-reactive protein level elevated, radiologic evidence of infection, loosening within the first five years after implantation. In case of infection a delayed two-stage reconstruction should be managed.

An arthropathic form of osteogenesis imperfecta.

A 14-year-old girl gradually developed severe osteoporosis and destructive generalized joint disease, resulting in joint stiffness and anchyloses. She also had moderate hydroxyprolinemia and hydroxyprolinuria. Rheumatoid arthritis was highly unlikely. Anamnestic data revealed two long bone fractures. Collagen biosynthesis was studied in fibroblasts cultured from the patient's skin. Chromatograms of 3H-labelled culture media proteins on ion exchange celluloses revealed an increased ratio of type III collagen to type I collagen when compared with the chromatograms of age-matched control fibroblasts. This finding is typical of certain cell strains in osteogenesis imperfecta. The patient might thus express a new variety of osteogenesis imperfecta with chronic arthropathy.