PURPOSE: We sought to determine the incidence, extent, and prognostic factors for physeal growth resumption after partial physeal bar resection.
METHODS: We performed a retrospective chart review of all patients treated between 1981-2017 by lower extremity physeal bar resection. All radiographic images were reviewed from preoperatively until cessation of affected physeal growth, subsequent surgery, or skeletal maturity. 
RESULTS: Eighty-nine patients met inclusion criteria (26 distal femora, 49 proximal tibiae (including 40 infantile Blount patients), 14 distal tibiae). Thirty-seven (42%) had at least two years’ normal growth (defined as “successful”), 13 (15%) showed less than two years’ growth (“partial”), and 39 (44%) had no growth (“failure”) after resection surgery. 56% of the “successful” and “partial” groups required subsequent surgery compared to 100% of the “failure” group. The use of methylmethacrylate (CranioplasticTM) as interpositional material was superior to autologous fat (p <0.01). Anatomic type of bar (peripheral, central, linear), physis affected, patient age, and etiology were not prognostic.
CONCLUSIONS: Approximately 40% of patients demonstrated useful resumption of growth after partial physeal bar resection. With the exception of interpositional material, other demographic variables were not prognostic. These results should be considered when determining whether physeal bar resection surgery is warranted in individual patients.
            Advanced 3-D imaging reconstruction preoperatively, imaging confirmation of complete bar resection, markers to detect and monitor growth, and periodic radiographic follow up until cessation of growth or maturity should be incorporated in a standardized treatment regimen. LEVEL OF EVIDENCE: Level 3
KEY WORDS: Physeal Arrest, Physeal Bar, Bony Bridge, Physiolysis, Epiphysiolysis