The purpose of this study was to examine the effects on plantar pressure of the rocker bottom shoe, which is a frequently used intervention for the ulcerated diabetic foot. In-shoe pressure distribution was recorded during walking in a conventional extra-depth shoe which was then modified into a rocker bottom configuration with a 24 degrees rocker, and the experiment was repeated. Peak pressures in the rocker shoe were reduce by approximately 30% compared to the conventional shoe in the medial and central forefoot and in the toe regions, but pressures were elevated in the heel, the midfoot, and in the lateral forefoot regions. These experiments suggest that a correctly designed rocker bottom show may reduce the risk of ulceration in certain areas of the foot. However, since pressures in some regions can also be elevated by this type of footwear, attention to individual design is critical.

Knee injuries in alpine skiing, especially the rupture of the anterior cruciate ligament (ACL), are still the leading indication for surgical treatment. The boot-induced anterior drawer (BIAD) caused by the backward fall is one of the possible injury mechanisms. We investigated the landing of approximately 250 jumps to collect data for a computer model of the BIAD. During our experiments one test subject suffered an ACL rupture of his right knee. This accidental event was recorded on video for later 2D motion analysis. Furthermore, the muscle activity of four muscles (vastus medialis and lateralis, biceps femoris and semitendinosus) was registered for both lower extremities during this event. Seven more subjects were analyzed under identical experimental conditions, thus representing an adequate reference group. The results of the 2D motion analysis will be presented and compared to the results of the reference group. Further, the registered EMG signal of the injured subject will be illustrated and discussed in relation to a reference subject. Our observations allow the conclusion that during landing situations different kinematics besides those described for the BIAD, in combination with certain muscular conditions, may lead to an ACL rupture.

In a retrospective study the results of operatively treated ankle joints were critically discussed. In a period from January 1, 1977 to December 31, 1994, a total of 35 arthrodeses were carried out. Seventeen patients were followed up clinically, radiologically and with a gait analysis. Not only the radiological surgical result was of interest, but also the heel-toe movement of the stiffened foot in the individually adapted orthopedic footwear compared to standard footwear. A significantly improved heel-toe movement was found in orthopedic shoes, although there is a reduction of movement in the hindfoot in the sagittal plane.

In a state-of-the-art paper on skiing performance and on skiing safety, aspects of ski boot design are discussed. The influence of ski boots on the skier-bootbinding-ski system is described, and suggestions are made about improving ski boots regarding better skiing performance, less inadvertent binding releases, and less lower extremity equipment related injuries. The design of the boot sole and the boot shaft with its influence on binding release values is particularly described. Furthermore, in the forward lean the shaft stiffness of modern ski boots and their pressure distribution is very important for good skiing performance and reduction of injuries of the ankle joint and the tibia. The built-in forward lean and the stiffness to the rear can be related to the acting forces in the anterior cruciate ligament, and first approximations to reduce the risk of these injuries are given.

Contraction of knee flexors and extensors in skiing related to the backward fall mechanism of injury to the anterior cruciate ligament Aune AK, Schaff P, Nordsletten L. Contraction of knee flexors and extensors in skiing related to the backward fall mechanism of injury to the anterior cruciate ligament. Scand J Med Sci Sports 1995: 5: 165-169. 0 Munksgaard, 1995 The purpose of this study was to examine the motion pattern and muscle activity during jumping and landing in downhill skiing to estimate the muscular involvement during the jump-landing-backward fall-anterior cruciate ligament (ACL) injury. A digitized 2-D video motion analysis and a synchronous %channel electromyography registration was performed over ajump on a downhill slope during 3 runs by 2 skiers and during 6 control jumps in the laboratory. The knee flexors (lateral gastrocnemius and biceps femoris) were recruited before touchdown and mean 60 ms earlier than the extensors (vastus lateralis and rectus femoris). Extensors and flexors reached peak activity simultaneously at the instant of landing. The knee flexion angle at the instant of landing was mean 36". As the landing was stabilized, the extensor activity persisted during eccentric work at increasing knee flexion as a corresponding flexor relaxation took place. The control jump in the laboratory showed a similar order of recruitment and timing of muscle contraction. The gastrocnemius was recruited mean 96 ms earlier and the biceps femoris mean 63 ms earlier than the extensors. This recruitment pattern during the landing movement suggest a learned motor program engaging the kinetic chain of the lower extremity to intercept the landing energy. The results also indicate that the knee flexor activity may protect the ACL at the instant of landing but that it is minimal shortly thereafter and probably not able to protect the ACL when a backward fall occurs. The knee was flexed substantially as the extensors became the dominating muscles. Thus, their ability to apply any anterior drawer force able to rupture the ACL is questioned.