The Weil osteotomy has gained popularity for surgically treating patients with metatarsalgia, intractable plantar keratosis and/or metatarsophalangeal joint dislocation because of its simplicity and lack of complications. Different geometric configurations of the Weil osteotomy have been proposed to reduce plantar pressure. In a dynamic cadaver model, these different geometric configurations of the Weil osteotomy did not significantly alter plantar pressure. Metatarsal head resection was required to significantly reduce plantar pressure.

The purpose of this study was to evaluate the effect of different geometric configurations of the Weil osteotomy on the plantar pressures in a dynamic cadaver model.

Different geometric configurations of the Weil osteotomy have been proposed to decrease plantar pressure, but in a dynamic cadaver model, these modifications did not significantly alter plantar pressure. Metatarsal head resection was required to significantly reduce plantar pressure.

The plantar translation of the metatarsal head occurring with a more oblique Weil osteotomy compared to a standard Weil osteotomy did not significantly increase plantar pressure in a dynamic cadaver model. The addition of a 4 mm slice resection did not significantly reduce pressure. Metatarsal head resection was required to significantly reduce pressure (p=0.02).

Ten specimens (5 matched pairs of cadaver lower extremities) were tested. Each pair of specimens had an oblique Weil osteotomy performed on one side, and a standard (parallel) Weil osteotomy on the other. Then, a 4 mm slice resection, and metatarsal head resection were performed sequentially. The plantar pressures were measured with an F scan in-shoe sensor while cyclically loaded to 700 N at a frequency of 1 Hz in intact specimens, and after each intervention.

The different geometric configurations of the Weil osteotomy did not significantly alter plantar pressure; metatarsal head resection was required to significantly reduce pressure. The Weil osteotomy reliably reduces dislocated metatarsophalangeal joints. The angle of the osteotomy does not affect plantar pressure. Further study in a dynamic model is required to identify other factors, which affect plantar pressure.

Aims: To evaluate the effect of different geometric conþgurations of the Weil osteotomy on the plantar pressures in a dynamic in vitro cadaver model. Methods: Ten specimens consisting of 5 matched pairs of cadaver lower extremities were tested. Each pair of specimens had an oblique Weil osteotomy with 5 mm shift performed on one side, and a standard (parallel) Weil osteotomy with 5 mm shift on the other. Then, a 4 mm slice resection, and metatarsal head resection were performed sequentially on each specimen. The plantar pressures were measured while cyclically loaded to 700 N at a frequency of 1 Hz with a F scan in-shoe sensor in intact specimens, and after each intervention. Results: This is the þrst study to demonstrate that the plantar translation of the metatarsal head occurring with a more oblique Weil osteotomy compared to a standard (parallel) Weil osteotomy did not signiþcantly increase plantar pressure in a dynamic in vitro cadaver model. Furthermore, the addition of a 4 mm slice resection did not signiþcantly unload the metatarsal head. Metatarsal head resection was required to signiþcantly unload the metatarsal head (p=0.02). Conclusions: The different geometric conþgurations of the Weil osteotomy did not signiþcantly alter plantar pressures in a dynamic cadaver model. Metatarsal head resection was required to signiþcantly unload the metatarsal head. Future studies of the effect of metatarsal osteotomies on plantar pressure should include evaluation in a dynamic in vitrocadaver model to account for all factors, which determine the distribution of plantar pressure.

Insertional Achilles tendonitis is an inflammatory disorder affecting mainly active young patients. The etiology is multifactorial and include the combination of anatomical and biomechanical characteristics. One fifth of the tendon injuries in athletes are insertional complaints which includes bursitis and insertion tendinitis.The complex of the insertion of the Achilles tendon includes three main components of fibrocartilage sesamoid, periosteum and enthesis. A conservative regime is recommended as the first line of treatment. In case of failure a surgical decompression of the posterior margin of the calcaneum is indicated.

Nine cadaveric legs were used for the experiment. The leg was mounted on an MTS machine and was axially loaded 360 N. The foot was attached to a plate which enabled dorsal and plantar flexion. The Achilles was sutured twice in an Ethibond No. 5 using the Krakow technique in order to anchor the tendon to an actuator. A thin pressure sensor plate (Teckscan) was inserted into the retrocalcaneal bursa to measure the force, pressure and contact area of the Achilles to the calcaneus in various positions of the foot. The conditions included 90 degrees of the foot, 15 and 30 degrees of dorsiflexion while the tension that was applied on the Achilles was 0, 200 N and 300 N. After resection of the posterior surface of the calcaneus in a 20 degrees inclination.

The mean peak force, pressure and area did not change in Achilles tensioning while the foot was in 90 degrees and were close to zero. In 15 degrees of dorsiflexion there was increase in the mean peak force, pressure and area when the Achilles was tensed to 200 and 300 Newton. Larger increase in these parameters was achieved by further dorsiflexion of the foot to 30 degrees.

After resection of the posterior margin of the calcaneus in an angle of 20 degrees the mean peak force, pressure and area dropped close to zero and remained almost unchanged during the various conditions of the experiment.

Dorsiflexion and tension of the Achilles tendon increases the mean peak force, pressure and area in the Achilles retrocalcaneal bursa. These data may explain the mechanism for insertional Achilles tendinosis. Resection of the posterior surface of the calcaneus in 20 degrees efficiently decompresses the retrocalcaneal bursa in various angles of the foot and in various tensions of the Achilles.

The Mayo Conservative uncemented stem (Zimmer, Warsaw, USA) is designed to conserve proximal bone stock by virtue of a minimal neck resection and to maintain proximal femoral stress transfer, thereby reducing problems associated with stress shielding.

This study was performed to evaluate proximal femoral strain after implantation of the Mayo stem, in cadaveric femora.

Eight fresh-frozen cadaveric femora (each selected at random from within a pair) of known bone mineral density were prepared and coated with photoelastic materials (Measurements Group, Raleigh NC). Strain patterns of the intact bone were determined using a reflection polariscope, and recorded photographically, while under load. Quantitative measurements were taken from set points of the proximal femur. The femoral head was then replaced using a Mayo femoral prosthesis. Under the same loading conditions strain patterns were re-examined and measurements taken from the same set points.

The strain patterns following insertion of the Mayo stem closely matched those seen in intact femora except in two areas. Strain was reduced in the region of the lesser trochanter (53% of normal), although more proximal than this strain in the neck was closer to intact values (78% of normal). Previous studies have found that implantation of diaphyseal press fit stems in particular have led to significant reductions in shear strain values in the calcar region and distally along the medial border of the femur.

This study documents the strain pattern in the proximal femur after implantation with a new “conservative” short stem cementless prosthesis. The hypothesis that the Mayo femoral stem maintains proximal femoral stress transfer and may thus prevent stress shielding in vivo remains to be proven, but is supported by the results of this study.