This study is a prospective series reporting on 143 consecutively treated proximal humerus fractures. The majority were low energy injuries with 93 non-displaced and 50 displaced fractures. Patients were followed with clinical evaluations including manual motor strength testing in the deltoid, supraspinatus, infraspinatus, biceps, triceps, and distal musculature. In addition, EMG's were performed and repeated every 2 months until recovery was noted. Results demonstrated that at 5-6 weeks post injury, 67% of patients showed denervation potentials on needle examination. Interestingly, the mean number of nerves involved for all patients with nerve injuries was 2.8. Solitary nerve involvement was seen in 21 of the 96 cases. The axillary nerve was most commonly affected in 83 of 96 cases.
The most important predictive factor for nerve injury was the type of fractures. As would be expected, nerve lesions were seen more frequently in displaced fractures (82%) than non-displaced fractures (59%). Clinically, recovery of shoulder function in patients with axillary nerve lesions took longer but did not ultimately influence the recovery of shoulder motion. Shoulder function returned more rapidly in non-displaced fractures without nerve injuries (18 weeks) compared to those with nerve involvement (26 weeks). Lastly, axonal nerve injuries were present in 8 of the 9 patients in their series with severe inferior shoulder subluxation. None of these patients demonstrated a neurotmetic lesion. Ultimately, all patients recovered adequate nerve function.
This study suggests that nerve injury in proximal humerus fractures are more common than has been previously documented in the literature, possibly even above that for shoulder dislocations. The most common pattern for nerve injury appears to be multiple nerve involvement. Close to 50% of patients had some injury to the suprascapular nerve, which is much higher than previously documented. This may explain the clinical findings of rotator cuff dysfunction following these injuries.
Journal Shoulder Elbow Surg