Flexor tendon rupture of the little finger caused by calcium pyrophosphate dihydrate crystal deposition disease of the pisotriquetrum joint

Closed rupture of extensor tendon resulting from untreated Kienböck disease: A case report and a review of the literature

RATIONALE

Spontaneous closed extensor tendon rupture is a rare complication of Kienböck disease with only 23 cases reported in the English literature.

PATIENT CONCERNS

We present a case of painless attritional rupture of the extensor tendons of the right fourth finger in a 69-year-old woman with Kienböck disease and review reported cases of Kienböck disease with subcutaneous closed tendon rupture.

DIAGNOSES

Physical examination had shown mild painless swelling of the dorsum of the right hand. Plain radiographs showed a dorsally displaced fragment of collapsed lunate bone fracture (Lichtman grade IIIb). Although surgery was recommended, the patient did not desire surgery because she had no pain and no interference with the activities of daily living. Six months later, however, the patient returned to our hospital with complaints of loss of spontaneous extension of the fourth finger. CT and MRI showed aseptic necrosis and large dorsally displaced fragments of the lunate under the extensor tendons of the fingers, suggesting a subcutaneous fourth extensor tendon rupture.

INTERVENTIONS

Surgery was performed to achieve functional recovery of the ring extensor and to prevent further subcutaneous tendon rupture. The extensor digitorum communis (EDC) of the ring finger was found to be ruptured and the EDCs to the third and fifth fingers were frayed due to attrition from the protrusion of the dorsal fragmented lunate bone. Inspection of the floor of the compartment revealed that the dorsally displaced fragment of the lunate bone had perforated the wrist capsule and protruded into the fourth compartment. The dorsal and volar fragments of the lunate bone were excised completely and scaphocapitate arthrodesis followed by the reconstruction of the fourth extensor tendon was performed.

OUTCOMES

A year after the surgery, radiography showed complete union of the scaphocapitate arthrodesis. The joint motion reached 45% of normal without any pain and there was full active extension of the fourth finger.

LESSONS

Because dorsally displacement of collapsed lunate bone fragments is a risk factor for attritional closed rupture of tendons, radiography, and MRI are essential to diagnose and to treat any closed tendon rupture.

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.