We investigated the effect of different nutritional regimens on fracture healing in the injured rat model. Four groups, each consisting of 12 male rats (307 +/- 16 g), were subjected to anesthesia, laparotomy (injury), and tibial osteotomy with internal fixation. Group I received 23% protein, group II received 23% protein and high caloric feed, group III received 5% protein, and group IV received 38% protein. After 8 weeks, calluses were x-rayed and the tibia was removed, fixed in a special block of methyl-metacrylate, and tested at tension up to failure in a mechanical testing apparatus. The distraction force at failure was measured, and callus stiffness and energy absorbed to failure were calculated. The low protein diet resulted in significantly lower tensile strength and stiffness of calluses compared to the other three dietary regimens, this despite adequate caloric intake. In addition, the low protein diet resulted in a callus with "rubbery" mechanical properties compared to the "rigid" calluses of the other three groups. The high protein diet did not result in any significant improvement in fracture healing. These results gain clinical significance in the face of a high incidence of protein calorie malnutrition in injured orthopedic surgery patients.

Analysis of Variance↗

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Stress fractures. Identifiable risk factors.

To answer the question why such large differences in stress fracture morbidity rates (2% to 64%) exist in different countries, we prospectively evaluated 312 recruits for possible risk factors for stress fractures. Prior to training, each recruit underwent an evaluation including the following: orthopaedic examination, foot and tibial radiographs, measurements of tibial bone width, bone mineral content, bone density, aerobic physical fitness and leg power, assessments of somatotype and smoking habits, and evaluation of sociological and psychological factors. Using a multivariate analysis, two risk factors were identified: recruits with stress fractures had significantly narrower tibiae (P less than 0.001), and a higher degree of external rotation of the hip (P = 0.016). These two variables were independent and cumulative. Stress fracture morbidity was 17%, 29%, and 45% when neither, one, or both risk factors were present, respectively (P less than 0.001). Identification of these risk factors might explain the susceptibility of some people to stress fractures.

Adult↗

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