Influence of body mass index on the outcome of brachial plexus surgery: are there any differences between elbow and shoulder results?

Abstract

Body mass index (BMI) has recently been identified as a predictor of outcomes following reconstructive surgery of shoulder palsies. In this study, we sought to determine if the same holds true for the reconstruction of elbow flexion. Forty patients who had undergone partial ulnar-to-biceps nerve transfer (Oberlin's procedure) for shoulder palsy were assessed and compared against18 previously reported patients who had undergone reconstruction for elbow palsies. The British Medical Research Council (BMRC) scale and an index dividing shoulder abduction strength in the affected arm by healthy arm were recorded. All patients had undergone surgery within 12 months of injury and had a parts per thousand yen12 months of follow-up. M4 or M3 biceps strength was obtained in 90 % of patients. Final strength on the affected side averaged 5.8 kg, versus 20.2 kg on the normal side, for a mean recovery index score of 0.30. In this sample of 40 patients, BMI did not predict percentage strength or BMRC grade recovery. Neither did age, number of roots involved, the affected side, nor time to surgery. Comparing patients with elbow versus shoulder reconstruction, there were no differences, except that patients undergoing Oberlin's procedure had a statistically longer duration of time between injury and surgical repair (7.4 vs 5.1 months, p < 0.006). Our data suggest that proximal muscle re-innervation is functionally more dependent upon BMI than distal re-innervation, likely because proximal muscles must support the weight of the entire extremity, while more distal muscles do not. BMI should be taken into consideration when planning surgery.