The bone mineral density and isokinetic knee strength in amputee soccer players

The aim of this study was to examine the isokinetic knee strength, H/Q ratio (%), and bone mineral density values between amputees (n=14; amputee soccer players) and healthy football players (n=14; non-amputee soccer players).

A total of 28 amputee soccer players and non-amputee soccer players participated in the study. An isokinetic dynamometer was used to determine the knee flexion/extension forces of the dominant legs of the athletes at 60, 180, and 240°/s. Bone mineral density scans were performed using dual-energy X-ray absorptiometry.

H/Q ratio and 60º/s flexion and 180 and 240º/s flexion/extension strength (p<0.05) were found to be high (180º/s, p=0.03; 240º/s, p=0.048) in the non-amputee soccer player group. Accordingly, the bone mineral density values of the lumbar vertebra, femoral neck, proximal metaphysis of the femur (p<0.01), tibia/fibula proximal metaphysis, and tibia/fibula distal metaphysis (p<0.05) were found to be high. A correlation was observed between the 60º/s knee extension strength and tibia/fibula diaphyseal bone mineral density (p=0.025; r=0.594) and tibia/fibula distal metaphysis bone mineral density (p=0.017; r=0.623) values in the amputee soccer players group. The Z-scores of the amputee soccer players and non-amputee soccer players were in the expected range according to age (>-2).

The bone mineral density, H/Q ratio, and all measured angular velocities of isokinetic strength were high in non-amputee soccer players. This finding made us think that lower extremity amputation may also be associated with losing strength. However, it was observed that the relationship between strength and bone mineral density in amputee athletes might vary according to different angular velocities. It is recommended that isokinetic strength measurement can be evaluated together with bone mineral density in athletes.