Abstract
INTRODUCTION: Isolated rupture of the flexor digitorum profundus tendon within flexor zone 3 is exceptionally rare and easily mistaken for the far more common zone 1 "Jersey finger" lesion. To the best of our knowledge, only two such middle-finger cases have been documented over the past six decades. Reporting this case, together with a literature synthesis, highlights the diagnostic pitfalls and supports timely, tendon-preserving intervention. CASE REPORT: A 65-year-old right-hand-dominant White male felt a sudden snap in his right palm while restraining a dog leash, followed by an inability to flex the distal interphalangeal joint of the middle finger. Clinical examination showed loss of the tenodesis effect, but plain radiographs excluded fracture. Initial exploration aimed at tendon reinsertion in zone 1 revealed an intact insertion, prompting proximal extension of the incision. A complete mid-substance rupture was identified in zone 3, approximately one centimeter proximal to the origin of the lumbrical muscle. Primary repair was performed using a four-strand cruciate core technique reinforced with circumferential epitendinous sutures. Post-operative rehabilitation employed early-motion protocols. Twelve months after surgery, the patient regained full strength, achieved a total active finger motion of 230°, and reported 95 percent functional recovery. CONCLUSION: This case illustrates how a concealed zone 3 rupture can masquerade as a distal avulsion, emphasizing the need for high clinical suspicion and, when feasible, pre-operative ultrasonography or magnetic resonance imaging to guide incision planning. Early direct repair within days of injury provided an excellent functional result, underscoring that prompt recognition prevents unnecessary grafting or transfer procedures. By adding the first modern case of isolated middle-finger zone 3 rupture and proposing a minimum reporting dataset, this report broadens surgeons' awareness of an uncommon injury and supports evidence-based management strategies that may preserve grip strength and hand function across orthopedic practice.