ANALYSIS OF MUSCLE BIOENERGETIC METABOLISM IN RABBIT LEG LENGTHENING

The effect of lengthening on muscle metabolism was measured and correl ated to the percent lengthening at early and late time points. Using t he rabbit tibial lengthening model, the authors examined the effects o f lengthening on the tibialis anterior muscle using phosphorus-31 magn etic resonance spectroscopy, Thirty-six rabbits were divided into five groups, four groups by percent lengthening (0%, 15%, 20%, and 25%), w ith each group divided into subgroups of early (end distraction) and l ate (12 weeks after end distraction), and the fifth group using the op posite untreated leg as control. Several parameters measuring metaboli sm of muscle using phosphorus-31 magnetic resonance spectroscopy analy sis were compared. No changes occurred to 15% lengthening, but signifi cant decreases were measured at 20% and 25% lengthening. After a 25% l engthening, the decreased metabolism persisted at 12 weeks after distr action, indicating the possibility of permanent damage. After 20% leng thening, the same parameters improved but never to normal levels, The authors conclude that lengthening to 15% is safe for muscle, but 20% t o 25% lengthening may result in permanent metabolic damage, The curren t study also suggests that phosphorus-31 magnetic resonance spectrosco py may provide a viable clinical method for evaluating muscle damage d uring lengthening.