Noninvasive arterial studies including transcutaneous oxygen pressure measurements with the limbs elevated or dependent to predict healing after partial foot amputation.

OBJECTIVE: Noninvasive arterial studies have been used to determine level of amputation. The objective of this study was to examine each component of the noninvasive arterial studies to determine optimal cut points to predict healing and to evaluate whether physiologic maneuvers could improve the utility of transcutaneous oxygen pressure (TcPO2) values to predict healing of partial foot amputation. DESIGN: The authors conducted a retrospective, observational study of 307 patients who underwent partial foot amputation and had noninvasive arterial studies in the perioperative period. RESULTS: The TcPO2 values were significantly predictive of healing. Specifically, a cut point TcPO2 value of 38 mm Hg had a sensitivity and a specificity of 71% for predicting healing or failure. The optimal cut point was mostly unaffected by patient characteristics. The addition of noninvasive arterial studies recorded in a position with the limb elevated improved prediction in the subgroup with supine TcPO2 values of 38 mm Hg or lower. CONCLUSIONS: The findings of this study validate previous reports and confirm that TcPO2 measurements are valuable to more accurately determine the correct amputation level and, in turn, obtain better outcomes. TcPO2 measurements may provide better prognostic value than do ankle-brachial indices for healing after partial foot amputation. TcPO2 measurements are useful but should not be used in isolation to make treatment decisions regarding amputation level.

Effect of environmental temperature on shock absorption properties of running shoes.

OBJECTIVE: To determine the effect of temperature changes on the shock attenuation of 4 running shoe shock absorption systems. DESIGN: Prospective. SETTING: Motion analysis laboratory. INTERVENTIONS: The shock attenuation of 4 different running shoes representing common shock absorption systems (Nike Air Triax, Asics Gel Nimbus IV, Adidas a3 cushioning, Adidas Supernova cushion) was measured at ambient temperatures of -20 degrees C, -10 degrees C, 0 degrees C, +10 degrees C, +20 degrees C, +30 degrees C, +40 degrees C, and +50 degrees C. Repeated-measures analysis of variance was used to determine differences between shoes. OUTCOME MEASURES: Shock attenuation as indicated by peak deceleration (g) measured by a mechanical impactor following ASTM Standard F1614-99. RESULTS: Shock attenuation decreased significantly with reduced temperature for each shoe tested. The Adidas a3 shoe exhibited significantly higher peak decelerations (lower shock attenuation) at cold temperatures compared with the other shoes. CONCLUSIONS: Cold ambient temperatures significantly reduce the shock attenuation of commonly used running shoes. These findings have important clinical implications for individuals training in extreme weather environments, particularly those with a history of lower limb overuse injuries.