Clinical Outcomes of Zone I Flexor Digitorum Profundus Injuries: A Systematic Review and Meta-analysis of the Last 25 Years

PURPOSE: Zone I flexor digitorum profundus (FDP) tendon injuries, at the distal phalanx insertion, generally require surgery. However, outcomes may vary, and multiple surgical techniques have been described. This review sought to evaluate management, rehabilitation, and outcomes following zone I FDP injuries. METHODS: Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review and meta-analysis was performed. PubMed/MEDLINE, Embase, Web of Science, and Cochrane were queried for articles concerning zone I FDP injuries since 2000. Patients younger than 18 years of age and revision surgery were excluded. Demographics, strength, range of motion, outcome scores, therapy protocols, and complications were evaluated. RESULTS: Twenty studies met inclusion criteria and were stratified by treatment strategy into 31 cohorts comprising 669 fingers. The mean age was 36 years and 25% were women. Injury mechanisms included 348 lacerations (52%) and 234 avulsions (35%); 88 injuries (13%) were unspecified. Primary tenorrhaphy was the most frequently reported treatment (39%), followed by tenorrhaphy with a tie-over button (10%) and bone anchor fixation (10%). The mean time to surgery was 4 days. Range of motion or outcome measures were documented in 12 cohorts (39%) and strength in 10 cohorts (32%). Meta-analysis demonstrated postoperative FDP rupture, revision surgery, and tenolysis rates of 2.0%, 1.0%, and 1.6%, respectively. Lacerations were treated with primary tenorrhaphy more commonly compared with avulsions (59% vs 22%) and had higher revision rates (7.6% vs 1.4%). CONCLUSIONS: Surgical repair of zone I FDP injuries demonstrates low complication rates and generally favorable outcomes; however, inconsistent reporting of functional outcomes limits meaningful comparison between surgical techniques.