The study was conducted to test the hypothesis that alterations in shoe gear can affect tibial strains in the human during dynamic loading. Rosette strain gauges were mounted on the medial border of the mid-diaphysis in two human subjects with a new strain gauge bonding technique using methyl methacrylate. Strain measurements were made at this site, the most frequent location for stress fractures in the Israeli Army during treadmill walking and free running while wearing various sport shoes (Rockport ProWalkers and New Balance NBX 900) and army boots (light Israeli infantry, double layered sole Israeli infantry, and Zohar infantry boots). Data were analyzed for only one of the subjects because strain gauge bonding was found to be inadequate at the time of surgical removal in the other subject. No single shoe lowered both the principal tibial compression and tensile strains, and the shear strains. The Zohar boot had the lowest principal compression strains during treadmill walking and mobile running, despite its relatively higher weight and sole durometry.
Percutaneous axial extensometers were mounted on the medial cortex of the midtibial diaphysis in seven male volunteers and the effect of three different shoes on in vivo peak-to-peak axial compression-tension strains measured during dynamic loading. Zohar shoes had lower axial strains and strain rates during treadmill walking than Nike Air Max running shoes or Israeli infantry boots. During running on a running track, there was no statistically significant difference between the axial strains or strain rates between the shoes tested. Shoe gear can modify tibial strains and strain rates that contribute to the development of tibial stress fractures.
Although sacroiliac strain is frequently diagnosed, objective evidence of such a disorder is generally lacking and the whole subject is controversial. We report four soldiers who developed pain in the sacroiliac region after excessive physical activity with abnormal scintigrams which resolved when the symptoms improved.
Patients, methods, and resultsA large group of highly motivated military recruits were evaluated in a prospective study of stress fractures. All soldiers had an evaluation before and after training and were followed throughout this. The soliders had free access to the medical staff as well as mandatory three week check ups and were followed until the resolution of any orthopaedic problem. Soldiers with symptoms compatible with stress fractures were given three days' rest and if they still had symptoms on return to activity stress fractures were diagnosed on the basis of Tc99 MDP late phase scintigraphy, with the activity rated from I to 4. The scan was repeated when clinically indicated.Four soldiers in this study presented with unilateral pain in their sacroiliac region (table). The pain was proportional to effort, relieved by rest, and did not respond to treatment with non-steroidal anti-inflammatory drugs by immediate relief. All the symptomatic sacroiliac joints were tender to direct palpation of the area and showed positive Gaenslen tests. There was no limitation of the range of motion in the lower back of the four soldiers. The results of blood and urine analysis were normal, including tests for rheumatoid factor and HLA-B27, as were x ray films taken near to the time of the onset of the pain and after relief. None of the soldiers had had lower back complaints or pain in the region of the sacroiliac joint before army training and after a period of rest all returned to normal activity, in cases 3 and 4 as combat soldiers and the rest in less demanding duties.
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