BACKGROUND Residual size discrepancy between the affected and unaffected limbs is a distinct but not well-understood consequence of an obstetrical brachial plexus injury. This study aimed to document the extent of limb length differences in children with obstetrical brachial plexus injury compared with typically developing children. The effects of age, growth patterns, severity, and surgical intervention were also explored. Also, this study examined the reliability of the clinical measurement technique. METHODS A prospective cohort of 179 children with obstetrical brachial plexus injury was systematically evaluated for limb length and girth by a multidisciplinary team. Clinical measurements were obtained at regular intervals until 12 months and then yearly. A control group of typically developing children aged 6 months to 17 years had limb length and girth measured on one occasion. RESULTS Interrater reliability of clinical measurement techniques demonstrated high consistency, with an intraclass correlation of 0.90 (p < 0.0001). Limb measurements were recorded at nine time points. Paired t tests of children with and without surgical intervention found significant differences between affected and unaffected sides in arm, forearm, and total length as early as the 1-month measurement and at most other time points (p < 0.05). The 3-month total limb length difference was a statistically significant predictor of 12-month limb length difference (p < 0.05). CONCLUSIONS Obstetrical brachial plexus injury significantly affects the length of the arm and forearm. Early detectable limb length deficits are associated with the likelihood of requiring surgical reconstruction. Clinical limb length measurement can be performed reliably and noninvasively.
