Purpose or Case Report: Healing fractures are a common radiographic finding in cases of child physical abuse. Accurate time since injury estimation of healing fractures may provide an opportunity for identification and characterization of physical abuse, especially in young children unable to verbalize. This study examines patterns of long bone fracture healing in a modern sample of young children.
Methods & Materials: A retrospective study of unintentional long bone fractures of the upper and lower extremities in children less than two years old was conducted at a large pediatric tertiary care center. Features of fracture healing (subperiosteal new bone formation [SPNBF] and callus formation) were evaluated and recorded as present or absent on radiographs at initial and follow-up visits. Casted studies were excluded if the fracture was obscured on all views. Abuse-related fractures and those with unknown date of injury were excluded. Individuals with co-morbidities or disorders affecting bone, and fractures requiring internal fixation were also excluded.
Results: There were 189 fractures in 175 patients (males: 77, 44%; females 98, 56%). One hundred twenty seven (67%) were upper limb fractures (humerus:37, radius:34, ulna:31, clavicle:25) and 62 (32%) were lower limb fractures (femur:26, tibia:24, fibula:12) and 533 exams were evaluated. Over half of upper and lower limb fractures exhibited SPNBF two weeks post-injury. SPNBF was observed 7 to 87 days post-injury in upper limb fractures (mean: 27 days, n=164 radiographs) and 8 to 95 days post-injury in lower limb fractures (mean: 29 days, n=75 radiographs). The majority of fractures exhibited callus formation by the third week post-injury. All levels of callus matrix (soft, intermediate, hard, remodeling) were observed earlier in upper limb fractures. Soft callus was first observed earliest in humerus and ulna fractures (10 days) and latest in tibia fractures (31 days). Hard callus was first observed earliest in humerus fractures (17 days) and latest in tibia and fibula fractures (28 days).
Conclusions: Patterns of healing are evident, with differences noted based on healing feature and fracture location. Though the largest sample to date, the results of this study may not be generalizable to all ages or fracture locations and differences in time of healing based on variables such as patient age and fracture location should be further explored.