Biotribology of a new bearing material combination in a rotating hinge knee articulation.

The objective of the present study was to evaluate the biotribological behaviour, in terms of wear and particle release, of bushings and flanges made of carbon fibre reinforced poly-ether-ether-ketone (CFR-PEEK) in articulation with a zirconium nitride (ZrN) multilayer surface coating in a rotating hinge knee system. For the bushings of the rotational and flexion axles and the medial and lateral flanges, a CFR-PEEK with 30% polyacrylonitrile fibre content was used in a new bearing combination with ZrN. In vitro wear simulation was performed for patients with metal ion hypersensitivity, using a new rotating hinge knee design with a ZrN surface articulation in comparison with the clinically established cobalt-chromium version. For the bushings and flanges made of CFR-PEEK subjected to wear simulation, the volumetric wear rates were 2.3±0.48mm(3)million(-1) cycles in articulation to cobalt-chromium as reference and 0.21±0.02mm(3)million(-1) cycles in the coupling with ZrN, a 10.9-fold decrease. The released CFR-PEEK particles were comparable in size and shape for the coupling to cobalt-chromium and ZrN with most of the particles in a size range between 0.1 and 2µm. The study reveals comparable low wear and no macroscopic surface fatigue in a new rotating hinge knee design with highly congruent flanges and axles bushings made of CFR-PEEK articulating to a ZrN multilayer surface coating. Favourable wear behaviour of the newly introduced CFR-PEEK/ZrN coupling in comparison with the clinically established CFR-PEEK/cobalt-chromium articulation was found.

[Prosthetics of metacarpophalangeal joints]. / Endoprothetik des Fingergrundgelenks.

Only a few of the large number of implants developed during the last decades for replacement of the metacarpophalangeal (MCP) joint have proven to be reliable. The rates of loosening and mechanical failure of almost all types of constrained prostheses are so high that their use cannot be recommended at present. For more than 40 years silicone arthroplasty according to Swanson has been regarded as the gold standard in the prosthetic replacement of the MCP joint. In long-term studies this device provided good pain relief and a lasting correction of preoperative ulnar deviation. The degree of patient satisfaction continues to be high after more than 10 years. With the NeuFlex spacer, a modification of the original Swanson implant, a better range of motion and a reduction of wear-related problems is expected. In this study the results of 130 NeuFlex spacers after a mean time of 3.6 years were examined and 82% of the patients were completely pain free. The mobility of the joints improved from 40 degrees preoperatively to 54 degrees after 3.6 years. Radiologically periprosthetic erosions or osteolyses were seen in approximately 15% of implants. A minimal sinking of the stems developed in 24%, a massive one in 6% and 13% of the spacers were broken. Thus the use of the NeuFlex implant resulted in a better range of motion compared to the Swanson spacer, but the problem of radiological appearance remained unchanged. For unlinked prostheses sufficient soft tissue stability is mandatory as well as wear-resistant surface materials. The pyrocarbon prosthesis according to Beckenbaugh is the only implant for which long-term results are available. In a prospective study we evaluated 28 Ascension pyrocarbon prostheses with a mean follow-up of 4 years. Stability was not found to be a problem. Subjective results were satisfactory, the range of motion remained unchanged, however 46% of prosthesis stems exhibited radiolucent seams, 7 prostheses (25%) were rated as loose and 5 of those had to be replaced by a silicone implant. Use of the implant was abandoned, as it was unreliable regarding bony fixation. There are promising concepts in some new prostheses but independent data are still lacking.

[Differences in elbow replacement in rheumatoid arthritis]. / Vergleichende Endoprothetik des rheumatischen Ellenbogengelenks.

Between 1987 and 2005, 165 patients with rheumatoid arthritis of the elbow, four with psoriatic arthritis, and eight with osteoarthrosis of the elbow were treated with total elbow arthroplasty using 126 semiconstrained GSB III elbow replacement prostheses; 46 semiconstrained Coonrad-Morrey prostheses; 24 Souter-Strathclyde unconstrained, unlinked prosthesis; four constrained link hinge prostheses; two custom-made prostheses; and one Pritchard elbow replacement. All implant procedures relieved pain and improved functionality. The complication rate was 34.4%. Revision surgery was needed in 27.2% of elbows because of infection, dislocation, or aseptic loosening. Survival of the semiconstrained implants with ventral or epicondylar flanges for load transfer was better than that of the other implants. Component linkage with the Coonrad-Morrey implant prevents dislocation without increasing the risk of loosening; therefore, semiconstrained implants are our choice for advanced arthritis of the elbow. Total elbow replacement is associated with a high complication rate and therefore may be warranted only for seriously disabled patients.

Ten-year follow-up of silicone arthroplasty of the metacarpophalangeal joints in rheumatoid hands.

In resection arthroplasty of destroyed metacarpophalangeal joints stabilisation with a silicone spacer is regarded as the gold standard. In 28 patients with rheumatoid arthritis (34 hands) 102 arthroplasties of the metacarpophalangeal joint were assessed a median of 10 years postoperatively (range 8.7-12.5). All patients reported pronounced subjective relief of pain, and in three quarters function of the hand had improved. The median active range of movement decreased from 40 degrees (range 10 degrees-90 degrees) preoperatively to 35 degrees (range 5 degrees-85 degrees) postoperatively. Ulnar deviation was corrected from a median of 35 degrees (range 0 degrees-60 degrees) preoperatively to 10 degrees (range 0 degrees-40 degrees) postoperatively. The extension deficit was improved from a median of 35 degrees (range 10 degrees-80 degrees) before surgery to a median of 10 degrees (range 0 degrees-30 degrees) at follow up. Grip strength remained unchanged. Radiological examination showed surrounding osteolysis in 89% of the implants and 28% had broken. The well-known discrepancy between fair clinical and good subjective results with distinct radiological findings such as osteolysis was therefore confirmed. Material fatigue and sharp bony edges that result from osteolysis may be the cause of the relatively common implant fractures and ulnar deviation in this long-term follow-up.

The effect of the additional use of grommets in silicone implant arthroplasty of the metacarpophalangeal joints.

After silicone arthroplasty of the metacarpophalangeal (MP) joint there is increasing osteolysis, subsidence and fracture of the implants in the longer postoperative term. In 44 patients with rheumatoid arthritis (54 hands) 151 arthroplasties of the metacarpophalangeal joint were assessed at a mean of 3.9 years postoperatively. In 57 arthroplasties titanium protectors (grommets) were used. There were no significant differences in the clinical outcomes with respect to swelling, correction of ulnar deviation, range of active movement and grip strength. The additional use of grommets in MP joint arthroplasty slightly reduced reactive osteolysis, protected the spacers from breakage and slightly reduced the amount of pain with only a few additional complications in the midterm follow-up.

[Therapy of rheumatoid destruction of the middle finger metacarpophalangeal joint with a Swanson silastic implant stabilized resection arthroplasty: comparative study of long and intermediate term results with and without implantation of titanium grommets]. / Die Therapie des rheumatisch destruierten Langfingergrundgelenkes mit der durch das Silastik-Interponat nach Swanson stabilisierten Resektionsarthroplastik: Vergleichende Studie lang- und mittelfristiger Ergebnisse mit und ohne Einsatz von Titangrommets.

Resection arthroplasty of the metacarpophangeal joints stabilized by a Swanson-Silastic-spacer is the golden standard in MP-joint destruction in R.A. 57 (Gr. I), 91 (Gr. II), and 102 (Gr. III) arthroplasties of the metacarpophalangeal joint were assessed in three groups of patients 3.5 years (Gr. I), 4.3 years (Gr. II), and 10.1 years (Gr. III), respectively, postoperatively on the average. In patients of group I titanium protectors, called grommets, were used additionally. Nearly all patients reported a marked relief of pain. Ulnar drift was corrected from an average of 22 degrees (Gr. I), 23 degrees (Gr. II), and 34 degrees (Gr. III) preoperatively. to 8 degrees (Gr. I), 7 degrees (Gr. II), and 12 degrees (Gr. III), respectively, postoperatively. Active range of motion remains unchanged with an average of 33 degrees (Gr. I), 38 degrees (Gr. II), and 42 degrees (Gr. III) ROM preoperatively and 42 degrees (Gr. I), 37 degrees (Gr. II), and 36 degrees (Gr. III) ROM, respectively, postoperatively. The average extension deficit had improved from 45 degrees (Gr. I), 32 degrees (Gr. II), and 33 degrees (Gr. III) at surgery to 18 degrees (Gr. I), 11 degrees (Gr. II), and 11 degrees (Gr. III), respectively, at the time of follow-up. Functional improvement of the hand was found in the medium term in 82% and in the longterm in 75% of the patients. The radiographical findings showed surrounding osteolysis in 45.7% (Gr. I), 63.5% (Gr. II), and 89.4% (Gr. III) of the implants and 0% (Gr. I), 16.5% (Gr. II), and 26.9% (Gr. III) broken spacers. From the medium to the longterm run there is an increase in radiographical deterioration. The additional use of titanium grommets in MP-joint arthroplasty seems to reduce reactive osteolysis and protects Swanson Silastic-spacers from breakage without substantial influence on the clinical outcome.

[Status of the endoprosthesis in rheumatic metacarpophalangeal joints. Long-term results of metacarpophalangeal prostheses using Swanson's silastic spacers]. / Stand der Endoprothetik des Fingergrundgelenkes beim Rheumatiker. Langzeitergebnisse des Fingergrundgelenkersatzes mit dem Silastik-Interponat nach Swanson.

Advanced rheumatoid destruction of the metacarpophalangeal joints frequently requires implant arthroplasty. Among many different types of implants, the Swanson-Silastic-spacer is widely used. The long-term results of 102 arthroplasties of the metacarpophalangeal joint were assessed in 28 rheumatoid patients (34 hands) 10.1 years postoperatively on the average. Marked relief of pain was found in all patients. 75% of the patients reported functional improvement of the hand. Active range of motion decreased from 42 degrees preoperatively to 36 degrees postoperatively on the average. Ulnar drift was corrected from an average of 34 degrees preoperatively to 12 degrees postoperatively. The average extension deficit had improved from 33 degrees at surgery to 11 degrees at the time of follow-up. Grip strength remained unchanged. The radiographical findings showed surrounding osteolysis in 89.4% of the implants and 27.5% broken spacers. In comparison to other types of finger implants, Silastic-spacers showed similarly limited all over results, however, there seem to be less problems in salvage procedures.

Basement membrane proteins in synovial membrane: distribution in rheumatoid arthritis and synthesis by fibroblast-like cells.

Rheumatoid arthritis is a complex disease of unknown origin. In consequence of some immunological reactions, proliferative invading synovial tissue leads to destruction of normal joint architecture. The aim of this study was to investigate qualitative changes in extracellular matrix distribution of proliferating rheumatoid synovium and their cellular origin. Synovial tissues from 57 clinically indicated arthrotomies were investigated with immunofluorescence, using specific antibodies against extracellular matrix proteins in tissue slides and cultured cells, which were also studied for collagen biosynthesis. Results indicated that synovial fibroblast-like cells synthesize and secrete basement membrane proteins laminin and collagen type IV as e.g. endothelial cells or organogenic fibroblasts. Laminin and collagen type IV were specifically demonstrated pericellularly in the hyperplastic lining layer of active rheumatoid synovitis. These findings are discussed with respect to the possible implication of altered cell-matrix interactions in rheumatoid synovial proliferation.

[6-methoxy-2-naphthylacetic acid level in plasma, synovial fluid and adjacent tissue in patients with rheumatoid arthritis or gonarthroses after a 4-day therapy with nabumetone (Arthaxan)]. / 6-Methoxy-2-Naphthylessigsäure-Spiegel in Plasma, Synovialflüssigkeit und umliegenden Geweben bei Patienten mit rheumatoider Arthritis oder Gonarthrosen nach 4tägiger Therapie mit Nabumeton (Arthaxan).

The concentration of 6-methoxy-2-naphthyl acetic acid (6-MNA) in plasma, synovial fluid, synovial tissue and fibrous capsule tissue was determined in an open study with 20 patients scheduled for knee joint surgery after oral treatment with nabumetone (Arthaxan) under steady state conditions. 6-MNA is the principal metabolite of the prodrug nabumetone arising from an extensive first-pass metabolism in the liver. The patients suffering from rheumatoid arthritis (n = 12) or osteoarthritis stage III or IV (n = 8) received a daily dose of 1 g nabumetone nocte starting 4 days prior to surgery. On day 1 an additional loading dose of 1 g nabumetone was given in the morning. At the time of surgery (day 5) simultaneously blood and synovial fluid was aspirated and after medial opening of the knee joint biopsies of synovial tissue and fibrous capsule tissue were taken. The samples were analysed employing HPLC. After 4 days of treatment mean 6-MNA concentration in plasma was 40.76 micrograms/ml, in synovial fluid 34.79 micrograms/ml, in synovial tissue 19.33 micrograms/g and in fibrous capsule tissue 11.43 micrograms/g. Under steady state conditions mean synovial fluid levels of 6-MNA were higher than after application of a single dose.

[Arthroscopic synovectomy of the shoulder and elbow joint]. / Die arthroskopische Synovektomie von Schulter und Ellenbogengelenk.

We reviewed experiences and results of six shoulder and nine elbow joint synovectomies, performed in a time period between 1989 and 1990 by arthroscopic technique. The operation technique is pretentious an requires some expenditure. The postoperative course distinguishes itself by little pain and early increase of range of motion.

Penetration of the active metabolite of nabumetone into synovial fluid and adherent tissue of patients undergoing knee joint surgery.

The concentration of 6-methoxy-2-naphthylacetic acid (6-MNA) in plasma, synovial fluid, synovial tissue and fibrous capsule tissue was determined in an open study with 20 patients scheduled for knee joint surgery after oral treatment with nabumetone under steady-state conditions. 6-MNA is the principle metabolite of the prodrug nabumetone arising from an extensive first-pass metabolism in the liver. Patients suffering from rheumatoid arthritis (n = 12) or osteoarthritis stage III or IV (n = 8) received a daily dose of nabumetone 1 g in the evening starting 4 days prior to surgery. On day 1 an additional loading dose of nabumetone 1 g was given in the morning. At the time of surgery (day 5), blood, synovial tissue and fibrous capsule tissue were taken simultaneously. The samples were analysed by high performance liquid chromatography. After 4 days of treatment mean 6-MNA concentration in plasma was 40.76 mg/L, in synovial fluid 34.79 mg/L, in synovial tissue 19.33 mg/g and in fibrous capsule tissue 11.43 mg/g. Under steady-state conditions mean synovial fluid levels of 6-MNA were higher than after administration of a single dose and, in common with levels in synovial tissue, persist in a range sufficient for in vitro cyclo-oxygenase inhibition.

[The Interplanta system model knee joint prosthesis. Preliminary results]. / Das Schalen-Kniegelenkendoprothesen-System Modell Interplanta (SKI). Erster Erfahrungsbericht.

The SKI-knee joint is used since three years. Our experiences comprise 220 cases up to now. The follow-up time is still short, but the implant, which is partially designed very close to normal anatomy and on the other hand regards fundamental biomechanical aspects is showing a comparably low incidence of complications. The complications specifically due to the endoprosthetic system sums up to 10%. It is obvious that patellar complications are leading. This fact should be seen in close connexion to the anatomical design of the femoral component. With increasing experience these problems are diminished. Causes and potential elimination of patellar complications are discussed. Surgical procedure, especially advantages in comparison with other knee joints are described. The SKI-System in combination with its aligning instruments allow the surgeon anatomical reconstruction, very exact alignment of the implant and precise correction of preexisting deformities. In general the results are encouraging in comparison with formerly used knee joints after the same follow-up period.