[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.

[Swan-neck and buttonhole deformities on rheumatic long fingers]. / Die Schwanenhals- und die Knopflochdeformität an den rheumatischen Langfingern.

Patients suffering from rheumatoid arthritis in many cases develop typical swan-neck and buttonhole deformities. In the further course of the disease we observe several stages. In the beginning active and later passive correction are still possible, while ultimately a fixed contracture is present. The activities of daily life may be severely reduced. The pathology of the swan-neck deformity is initiated at the level of the metacarpophalangeal joint, while at the origin of the buttonhole deformity the synovitis of the proximal interphalangeal joint is obvious. In the early stages, synovectomy and balancing of the soft tissues are surgically indicated. In advanced stages, complicated soft tissue reconstruction in combination with alloarthroplasty or arthrodeses may become necessary to allow for sufficient finger function.