Introduction

Many of the patterns of long bone injury described with abuse have been noted with obstetric trauma. Skeletal lesions associated with obstetric injuries were described in the literature before child abuse was fully acknowledged as a valid medical entity (1–3). Caffey relied on these studies in formulating his concepts of the pathogenesis of traumatic subperiosteal new bone formation (SPNBF) and the classic metaphyseal lesion (CML) of abuse (2, 3). Although the frequency of skeletal injuries with the birth process has decreased with modern obstetric techniques, major orthopedic injuries still occur and provide valuable insights into the mechanisms entailed in similar lesions occurring with abuse. Thus, an examination of obstetric injuries is not only of value in distinguishing them from abuse, but it also provides important information regarding the biomechanics, natural history, and imaging characteristics of inflicted skeletal injuries.

The overall incidence of obstetric injuries has recently been estimated at approximately 2.29 per 1000 births (4); however, this figure may well be higher, since some studies estimate the incidence of clavicular fracture alone as high as 7% of term deliveries (see below). Risk factors include oligohydramnios, prematurity, cephalopelvic disproportion, abnormal presentations, prolonged or accelerated delivery, instrumented delivery, and a birth weight greater than 4 kg (5). Shoulder dystocia figures prominently into clavicular and upper extremity fractures, as well as brachial plexus injuries (6). However, obstetric fractures may be encountered in infants born by uncomplicated vaginal delivery and cesarean section (7–12).