Attritional rupture of the flexor tendons to the small finger caused by osteophyte of the ulnar head: case report

Are Flexor Tendon Ruptures Ever Spontaneous? - A Literature Review on Closed Flexor Tendon Ruptures of the Little Finger

Background: When closed ruptures of flexor tendons of fingers occur, there is often an identifiable pathology, which should be addressed in the same surgical setting as the tendon repair. The concept of “spontaneous” tendon rupture, occurring in the absence of identified pathology, however, has also been reported in a significant number of papers. This controversy has prompted us to do a review of the existing literature.

Methods: We did a review of cases of closed ruptures of the flexor digitorum profundus (FDP) of the little finger in existing literature. Fifty-three publications were retrieved by searching “FDP tendon rupture” and “little finger” using PubMed database. We analyzed data such as the zone of rupture noted intra-operatively; and any precipitating factors, pathology or trauma. We also conducted a review on papers which discussed the concept of “spontaneous rupture”.

Results: Fifty-three publications were retrieved. There were 8 cases of ruptures in Zone I; 2 in Zone II; 30 in Zone III; 59 in Zone IV and 5 in Zone V. Majority of cases were associated with an element of trauma of varying severity, or pathology. A precipitating cause was not documented in 12 cases. Amongst all 36 cases of ruptures labelled as “spontaneous”, only 1 case was truly “spontaneous” without any associated trauma or pathology.

Conclusions: Most reports labeled as spontaneous rupture occurred in Zone III, where tendon ruptures are rare. There are documented pathological causes or evidence of trauma to most of these cases. We conclude these ruptures may have been mislabeled as spontaneous ruptures. Bearing in mind the propensity for tendon excursion, we suspect the lack of documentation of exploration in proximal zones contributed to this mislabeling. Understanding this concept of non-spontaneity to most tendon ruptures and the common sites of rupture or pathology is crucial for a surgeon to make strategic incisions and minimize future recurrence.

Spontaneous flexor tendon rupture due to atraumatic chronic carpal instability

Background Spontaneous flexor tendon rupture is considered to be invariably associated with previous hand/wrist injury or systemic disease such as rheumatoid arthritis. Case Description A 54-year-old man presented with a 4-month history of mild ulnar wrist pain and spontaneous left little finger flexion loss in the absence of distant/recent trauma and systemic arthropathy. Surgical exploration confirmed a zone IV left little finger flexor digitorum profundus (FDP5) attritional rupture (100%), ring finger flexor digitorum profundus (FDP4) attenuation (40%) and a disrupted lunotriquetral ligament and volar-ulnar wrist capsule. Volar subluxation of the narrowed carpal tunnel resulted in flexor tendon attrition against the hamate hook. A side-to-side tendon transfer was performed along with a lunotriquetral ligament repair and temporary Kirschner wire fixation. At 6 months the patient had full active, synchronous flexion of the ring and little fingers and reduced wrist pain. Literature Review Traumatic flexor tendon ruptures have been reported following distal radius/hamate hook fractures, from carpal bone osteophytes, accessory carpal bones and intraosseous ganglia. Attritional ruptures caused by chronic, degenerative carpal pathology are less common. Clinical Relevance This case highlights an unusual cause of flexor tendon rupture due to chronic carpal instability.