[Chronic cobalt poisoning in endoprosthetic replacement]. / Chronische Kobaltvergiftung in der Endoprothetik. Ein Fallbericht.

This article outlines symptoms and therapeutic options in chronic cobalt poisoning including a case report in which metallosis caused by a ceramic-metal articular pairing led to almost complete loss of sight and hearing after revision of a total hip prosthesis. At primary revision the firmly incorporated stem was left in place. For a better offset only the head was exchanged from a ceramic to a metal model which articulated with a socket containing a ceramic inlay. Postoperatively, movement of the hip joint became increasingly uncomfortable and painful. After 2 years, the patient started complaining about increasing impairment of his eyesight followed by a gradual loss of hearing. In a second revision, examination of the explanted material showed almost complete deterioration of the metal femoral head and a partially fractured ceramic inlay with extensive contamination of the bone and surrounding soft tissue by metal debris. At the time of revision increasing concentrations of the alloy elements cobalt, chromium, and molybdenum were measured in the serum and liquor. The concentration of cobalt, in particular, was remarkably high. Treatment options in cases with chronic cobalt poisoning include chelation therapy with EDTA or BAL/DMPS.

Polyetheretherketone--cytotoxicity and mutagenicity in vitro.

The results of the incubation of polyetheretherketone (PEEK) fibre material with seven different genotype variants of salmonella bacterium showed with and without an external metabolic activation system (S9) with no mutagenic or cytotoxic activity of the test material. In the so-called "plate incorporation test" in which the PEEK raw material is finely cut and applied direct to the agar plate without the addition of solvent there was, as expected, no evidence of cytotoxic or mutagenic effects. In the HPRT test there was a significant increase in the number of mutants per dish, both after addition of N-acetylaminofluorene and N-methyl-N'-nitro-N-nitrosoguanidine (with and without an external metabolic activation system = +S9), but not after treatment of the cells with PEEK-DMSO-eluate. This means that the PEEK material under study did not release any substances that cause V79 cells to mutate. The investigation of the toxic reaction on the material under study revealed that the number of surviving colonies per 10(5) surviving cells lay within the range of or below the solvent control even in the presence of high PEEK concentrations (5.0 microg/ml). Therefore, in summary, the study produced no evidence of cell damage caused by PEEK.

Ionogran in revision arthroplasty.

Glass ionomer cement (Ionocem) was developed for use in bone surgery and is reported to be notably biocompatible. Between 1991 and 1994 we performed revision operations for aseptic loosening of arthroplasties of the hip on 45 patients using this material in its granulate form (Ionogran) mixed with homologous bone as a bone substitute. Of these 45 patients, 42 were followed up for a mean of 42 months. Early reloosening of the acetabular component has occurred in ten after a mean of 30 months. Histological examination showed large deposits of aluminium in the adjacent connective tissue and bone. Osteoblastic function and bone mineralisation were clearly inhibited. The serum levels of aluminium were also increased. The toxic damage at the bone interface caused by high local levels of aluminium must be seen as an important factor in the high rate of early reloosening. Our findings cast doubt on the biocompatibility of this material and we do not recommend continuation of its further use in orthopaedic surgery.

[Mid- to long-term results after treatment of 118 cases of periprosthetic infections after knee joint replacement using one-stage exchange surgery]. / Mittel- bis langfristige Ergebnisse nach Behandlung von 118 periprothetischen Infektionen nach Kniegelenkersatz durch einzeitige Austauschoperation.

From 1976 to 1985, 157 periprosthetic infections after knee arthroplasty were treated surgically at the ENDO-Klinik in Hamburg. Of these, 118 cases underwent one-stage revision arthroplasty using specific antibiotic-loaded cement; 104 were available for analysis after a postoperative follow-up period of 5-15 years. Seventy-six cases were cured as a result of this single operation. This number was increased to 84 by a repeated operation in cases that had failed to respond to therapy. In 20 cases one-stage revision arthroplasty failed in the treatment of periprosthetic infections after replacement of the knee joint.

Management of infected prostheses.

A retrospective actuarial analysis of 825 onestage reimplantations using antibiotic-loaded acrylic cement for infected total hip replacements is presented. Staphylococcus aureus was the most commonly encountered organism. Failure rates of prostheses infected by S. aureus, Staphylococcus species, and anaerobic Corynebacteria did not differ statistically. A factor that significantly contributed to failure of this method of treatment was Pseudomonas infection. By actuarial analysis (with a twoyear minimum followup) at five years after operation 23% of the implants had failed, and at 11 years, 50%. This compares to a 77% success rate implied by conventional arithmetic.

Disarticulation of the hip as a result of failed arthroplasty. A series of 11 cases.

Eleven patients underwent disarticulation for infected arthroplasty of the hip. Exchange total hip arthroplasty or conversion to a Girdlestone excision arthroplasty had been undertaken previously an average of 2.9 times. The indications for disarticulation were as a life-saving measure, or as a result of severe infection of soft tissue and bone, loss of bone stock, or vascular injury. While the indications for this drastic operation were highly individual, there were instances where disarticulation could have been avoided if repeated exchange operations had been eschewed in deference to a Girdlestone procedure.