Strength Recovery from Nonsurgical Treatment of Apophyseal Avulsions of the Pelvis

Background: Strength deficits, strength recovery, and return to sports timing following nonoperative apophyseal avulsion fractures are relatively unknown, as is the effect of displacement of the avulsed fragment. This study aims to assess strength recovery following a pelvic apophyseal avulsion and determine whether a relationship between radiographic characteristics and strength exists. Methods: Twenty-eight patients from a prospective pelvic apophyseal avulsion study database, were treated nonoperatively with physical therapy, and a minimum 3-month follow-up was included. Patients were categorized by location of injury and fracture displacement (greater or less than 15 millimeters). Strength measurements obtained at a minimum of 3 months postinjury were used to quantify overall hip and knee strength across several strength measurements. Limb symmetry index (LSI) was calculated as a percentage of the affected limb strength compared with the unaffected limb. Affected and unaffected sides were compared with t tests. Spearman correlation coefficients were calculated to assess radiographic characteristics and affected limb strength correlations. Results: Twenty-three (82.1%) patients were male, with an average age of 14.7 ± 1.1 years. The mean fracture displacement was 10.87 ± 10.24 mm. The most common location of injury was the anterior inferior iliac spine (35.7%, n = 10). Among all patients, no strength deficits were observed on the affected limb compared with the unaffected limb, and affected knee extension (KE) strength was greater than unaffected (LSI 110.94%, P = 0.013). In fractures displaced < 15 millimeters, the affected limb KE strength was stronger than the unaffected limb (LSI 110.92 ± 15.52, P = 0.022). Increasing fracture displacement positively correlated with hip flexion (P = 0.008), hip extension (P = 0.049), hip abduction strength (P = 0.040), and KE strength (P = 0.011). Conclusion: No strength deficits were identified in the affected limbs following pelvic avulsion injuries compared with the unaffected limb. Affected limb knee extension strength was greater compared with the uninjured side following physical therapy. A majority of apophyseal avulsion fractures have near complete recovery of strength at 3 months with conservative management.