Outcomes have been reported for a limited number of short frontal plane fractures of the proximal phalanx following nonsurgical treatment and internal fixation. To describe a new approach, arthroscopic debridement, of short frontal plane fractures of the proximal phalanx in flat-racing Thoroughbreds and post-operative racing outcome. Retrospective case-control study. Medical records of 81 Thoroughbred racehorses treated with arthroscopic debridement for frontal plane fractures of the proximal phalanx were reviewed. Diagnostic images and operative reports were used to characterise lesions and a technique for arthroscopic treatment was described. Post injury racing career length, starts, earnings and race quality are compared with matched controls. Of 81 treated horses, 74 (91%) raced post-operatively. Treated horses had fewer post-operative starts compared with controls (median 12, 95% CI 9-16 vs median 19, 95% CI 15-23; P<.001), but there was no difference in post-operative earnings (median $51465, 95% CI $39868-$85423 vs median $68017, 95% CI $54247-$87870, P=.7) or career length (median 7 quarters, 95% CI 5-8 vs median 9 quarters, 95% CI 8-10, P=.1). Retrospective studies prevent prospective control of sampling bias and limit selection of matched controls. Treatment of frontal plane fractures of the proximal phalanx by arthroscopic debridement results in racing performance comparable to uninjured controls with respect to longevity and earnings.