Long-term follow-up of Keller arthroplasty with irradiated costochondral implants

Design of a first metatarsophalangeal joint simulator

BACKGROUND

The use of total first metatarsophalangeal joint (MPJ) arthroplasty to treat patients in which the pain, due to a pathological joint, has not been relieved with a conservative method or for which the disease or disorder is at an advanced stage, is popular. Although meta-analysis of clinical results indicates that this surgical option is efficacious, there are problems with implant failure due to wear of the components. Although there is a plethora of designs of this type of implant in clinical use, there are no literature reports on total first MPJ simulators, which may be used to evaluate, for example, the wear rate of a total first MPJ implant.

METHODS

We designed such a simulator, guided by the biomechanics of the joint. Thus, for example, the implant under test will be articulated at least 40° dorsiflexion, under a 600 N loading, at 1 Hz. Furthermore, the testing stations will be configured to allow testing of any type of first MPJ implant. We also performed a finite element analysis (FEA) study of a model of an articulating station, subjected to a quasi-static load of 1200 N.

RESULTS

For an articulating station, (1) the highest von Mises stress occurred at the implant-fixture interface; and (2), for the other parts, the minimum factor of safety, against elastic failure, is approximately 9.

CONCLUSIONS

The designed joint simulator is mechanically sound and may be used for wear testing of any type of first MPJ implant.

Does total joint replacement or arthrodesis of the first metatarsophalangeal joint yield better functional results? A systematic review of the literature

As first metatarsophalangeal joint arthrodesis is generally considered to be a successful procedure for the treatment of hallux rigidus, many surgeons question the usefulness of total joint replacement. In an effort to elucidate the clinical evidence, we undertook a systematic review of the literature comparing the functional outcomes of arthrodesis and joint replacement in first metatarsophalangeal surgery. Using multiple search engines and medical subject headings, 10 articles were eligible for inclusion: 5 featured arthrodesis and 5 featured total joint replacement. The American Orthopaedic Foot and Ankle Society-Hallux metatarsophalangeal-interphalangeal score was used in all articles. The mean age at operation was 53 years for joint replacement patients and 55 for those undergoing joint arthrodesis. Most patients in all studies were female. There was a significant increase from pre- to postoperative scores in both procedures. The median postoperative score for joint replacement was 83/100 (range 74-95) and 82/100 (range 78-89) for arthrodesis. The median revision rate in joint replacements was 7% (range 0%-10%) and 0% (range 0%-12%) for arthrodesis. This systematic review reveals that arthrodesis achieves better functional outcomes than total joint replacement. The operative techniques and prostheses for joint replacements are however still in an early stage of development and advances still need to be achieved to produce a more successful and anatomical prosthesis that could be functionally superior to an arthrodesis.

Moje first metatarsophalangeal replacement--a case series with functional outcomes using the AOFAS-HMI score

We report the functional results of a case series of Moje first metatarsophalangeal total joint replacements carried out between February 2001 and November 2006. All patients who underwent Moje arthroplasty under the care of a single surgeon were included; outcome scores and complications were recorded annually. A total of 32 joints in 29 consecutive patients were followed for a mean duration of 34 (range 6 to 74) months, and the mean patient age at the time of operation was 56 (range 38 to 79) years. Hallux rigidus was the primary diagnosis in 28 (87.5%) of the cases. The mean American Orthopaedic Foot & Ankle Society Hallux-Metatarsophalangeal-Interphalangeal score at final follow-up was 74/100 (range 9 to 100), with 13 (40.63%) joints rated good to excellent. Two (6.25%) joints were revised to arthrodesis at a mean of 52 (range 41 to 63) months following the arthroplasty procedure, and the overall prevalence of postoperative complications was 6 (18.75%). Based on these results, we concluded that first MTPJ total joint replacement with the Moje device remains promising, but still has room for improvement before the results match those obtained with larger joint (knee, hip) arthroplasty.