# Changes in Glenohumeral Musculoskeletal Development Following Brachial Plexus Birth Injury

## TL;DR

This paper reviews how brachial plexus birth injury affects shoulder development and highlights the need for better understanding of treatment differences based on injury type.

## Contribution

The paper identifies key gaps in understanding the distinct effects of postganglionic and preganglionic injuries on musculoskeletal development.

## Key findings

- BPBI leads to complex musculoskeletal issues like muscle weakness and joint deformity.
- Current treatments for nerve rupture and avulsion are similar despite differing outcomes.
- Animal and computational models offer insights but more research is needed for targeted therapies.

## Abstract

Brachial plexus birth injury (BPBI), one of the most common nerve injuries in children, often leads to impaired shoulder development, resulting in sustained postural and bone deformity and muscle weakness. Despite the substantial long‐term consequences, clinical consensus is lacking for what BPBI treatments are optimal in terms of timing and approach, primarily because BPBI sequelae are complex, involving stunted muscle growth, muscle denervation, and limb disuse that can disrupt glenohumeral joint development. Injury can occur as nerve rupture (postganglionic injury) or nerve avulsion (preganglionic injury), which have distinct musculoskeletal consequences yet are often treated similarly clinically due to their similar initial presentations and the inability of existing methods to distinguish between them. Most of our clinical knowledge about the musculoskeletal detriments in the shoulder comes from studies in nerve rupture patients. Knowledge is generally lacking for the specific effects of injury location on the development and progression of muscle and bone deficits following BPBI. A better understanding of the distinct effects of postganglionic and preganglionic BPBI is important for developing more effective and targeted treatments. More studies are needed to elucidate differences between nerve rupture and nerve avulsion and the particular factors driving glenohumeral deformity development. This paper reviews current knowledge about clinical musculoskeletal deformity development in the shoulder following BPBI, as well as additional insights gleaned from animal and computational models, and identifies key gaps that need to be addressed in future studies to inform better approaches for mitigating and preventing glenohumeral deformity in these patients.