Biomechanical significance of the correct length of lower limb prostheses: a clinical and radiological study.

The length of the lower limb prosthesis was compared with the length of the contralateral lower extremity in 113 Finnish war-disabled amputees by a radiological weight bearing method developed by the author. Considering a shortening of 10 mm for above-knee prostheses and of 5 mm for below-knee prostheses as tolerance limits, the length of the prosthesis was acceptable only in 17 cases (15% of the total group). In 79 cases (70%) the prosthesis was up to 47 mm too short and in 17 cases (15%) up to 40 mm too long. Chronic pain symptoms of low back, hip and knee correlated significantly with the lateral asymmetry caused by incorrect length of the prosthesis. Independently of the side of amputation, the unilateral sciatica and chronic hip pain occurred mainly on the long leg side. Physical activity of the lower limb amputees seemed to correlate with the suitability of the length of the prosthesis, and was unrelated to the length of the amputation stump.