Spontaneous recovery of active shoulder external rotation in patients with brachial plexus birth injury.

Background: Brachial plexus birth injuries (BPBI) occur as a result of a difficult delivery. External rotation of shoulder (ER) is usually one of the last movements which may recover. There is no consensus about the predicting factors for spontaneous recovery or the optimal timing for surgical treatment of ER in BPBI patients. The aim of our retrospective study was to describe spontaneous recovery of active ER and evaluate predicting factors for the recovery.

Methods: We screened 562 patients and identified a consecutive cohort of 103 BPBI patients, who had no active ER at the age of 3 months. We systematically collected clinical data on recovery. In addition, we assessed whether early recovery of elbow flexion, shoulder abduction or Narakas grade at 1 month predicts ER recovery.

Results: Fifty-two (51%) patients spontaneously recovered ER, 44% of whom were recovered by the age of 1 year, 83% by 1.5 years, 92% by 2 years and 98% by 3 years. A breakpoint in the slope of the curve showing proportion of recovered patients occurred at 2 years of age. Recovery of active ER was significantly associated with early elbow flexion and Narakas grade at 1 month, but not with early active shoulder abduction.

Conclusions: Most spontaneous recovery of ER in patients with BPBI occurs until 2 years of age, which thus can be considered a meaningful follow-up period for spontaneous recovery of ER. This information should be considered when making decision about peripheral nerve transfer surgery to improve ER in BPBI.