Abstract

Background:This clinical trial examined the effectiveness of a hip prosthesis (HP) for exercise tolerance/ performance using cardiopulmonary ergometer exercise testing in a trans-pelvic amputee for improving physical fitness.

Case Presentation: A 50-year-old male had undergone left trans-pelvic amputation due to osteosarcoma primarily in the left femur. After 9 months of continuous post-amputation physiotherapy, he performed breath-by-breath incremental upright cycle ergometer exercise (CERx) with 5W ramp-up (1W increasing every 12sec) to exhaustion in three different conditions: without the HP (HPoff) and with a fitted prosthetic leg HP with/without pedal rotation by the prosthetic leg (HPon+ and HPon-, respectively). Peak oxygen consumption (VO2peak), work rate, exercise time, and other parameters were measured. The peak work rates for HPoff, HPon-, and HPon+ were 24, 42, and 50W, respectively, associated with exercise times of 293, 504, and 606 sec; VO2peak of 12.6, 12.0, and 14.6ml/kg/min; peak heart rates of 158, 147, and 148 beats/min; and mean blood pressure of 133, 143, and 122mmHg.

Conclusion: For CERx to exhaustion, a fitted prosthetic leg HP (HPon+) increased peak work rate and exercise time (~2.1-fold) compared with one-legged CERx (HPon- and HPoff). The stability of two-legged pedal cranking may be improved compared with one-leg pedal cranking. Furthermore, the exercise time for HPon- was 1.7-fold (211s) longer than for HPoff, potentially because the pelvic socket provided a more stable sitting fixation/position on the saddle, allowing stable unilateral leg pedal rotation. VO2peak was similar between HPoff and HPon-, representing equivalent limitations for one-legged working muscle metabolism to exhaustion, but the slightly higher value (+2.54ml/kg/min) for HPon+ compared with HPon- may indicate more effective utilization of working muscles via two- legged pedal cranking. This case indicates the utility of an HP for two-legged exercise program development in trans-pelvic/hip disarticulation amputees.

Keywords:Exercise performance; Oxygen consumption (V-dot O₂); Hemipelvectomy amputee; Hip disarticulation; Hip prosthesis; Prosthetic leg