Acute Traumatic Swan Neck Deformity: A Case Report of the Oblique Retinacular Ligament Lesion

The retinacular ligaments of the digital extensor expansion revisited: An anatomical and biomechanical study

Our aim was to clarify the anatomy and function of the retinacular ligaments. Forty-eight fingers were dissected and the thickness of the oblique retinacular ligament (ORL) was graded. In four fingers, the motion in the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints was subjected to an in-depth analysis before and after sectioning of either the lateral bands (LB) or the ORLs. The function of the ORLs in restricting flexion of the DIP joint with full extension of the PIP joint was measured in 10 fingers. An ORL could be identified on both sides in all 48 fingers. The distribution of the insertion on the proximal phalanx was 7/96 (7%) in the distal third, 70/96 (73%) in the middle third and 19/96 (20%) in the proximal third. Among the specimens, 29% were graded as having a strong bundle of fibers, 51% as having well-defined and regular fibers and 20% as having thin and sparse fibers. With the PIP joint extended, there was a statistically significant increase in flexion of the DIP joint after the ORL was cut. After the LB was sectioned, the ORL was able to extend the DIP joint with an extension lag of 10-22°. Cutting the ORL did not affect the ability to extend that joint. We conclude that the retinacular ligaments are consistent. Their major role is not connected with finger movement, but to provide stabilizing links between the PIP and DIP joints. They are active in not only specific, uncommon finger positions but also in ordinary use of the fingers.

Terminal extensor tendon reconstruction as a reliable options for chronic mallet finger with swan neck deformity of index finger: A case report

Introduction

and importance: Chronic mallet finger resulted in mallet deformity or swan neck deformity are caused by imbalance of flexor and extensor mechanism. We tried to offer a reliable option of treatment by terminal tendon reconstruction using needle passer to exchange the use of K-wire which resulted in great result within 3 months of follow up.

Case presentation

36 years old male with previous history of several trauma on his right arm and hand about three months ago; consists of distal phalangeal fracture of right index finger, right fifth metacarpal fracture, proximal phalanx fracture of right small finger, and right shaft radius fracture. After 3 months since initial injury, we focused on the right index finger which suffered in a swan neck deformity. The patient was unable to reach maximum flexion of his right index finger. We performed terminal extensor tendon reconstruction with great result after three months of follow up.

Clinical discussion

Chronic mallet finger has many different techniques of surgical intervention, such as Fowler's tenotomy, tenodermodesis, spiral oblique retinacular ligament (ORL) reconstruction, and arthrodesis of distal interphalangeal (DIP) joint. The surgery was indicated after failure of 4 weeks finger splinting to correct the swan neck deformity. The aim of surgery was to improve finger function, restore normal active-passive flexion of proximal (PIP) and distal interphalangeal (DIP) joint by rebalancing the extensor mechanism of finger, relieve pain, and improve cosmetic appearance.

Conclusion

Terminal extensor tendon reconstruction is a simple, reproducible and reliable option of surgical treatment in chronic mallet finger case. At minimum follow up of 3-months after surgery has showed a satisfactory result.

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Chronic mallet finger resulted from failure of conservative treatment >4 weeks.

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Surgery is indicated as the treatment of choice with many different techniques.

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Terminal extensor tendon reconstruction is a favorable option of surgical treatment.