Spiral oblique retinacular ligament reconstruction using lateral band technique to treat swan neck deformity due to chronic mallet finger: A case report.

INTRODUCTION: Swan neck deformity (SND) is characterized by hyperextension of proximal interphalangeal (PIP) joint and extension lag of distal interphalangeal (DIP) joint with functional loss of finger and impairs of tight grip of the finger. SND often results from chronic mallet injury and requires surgical treatment. One of the procedure is spiral oblique retinaculum ligament (SORL) reconstruction. We reported good outcome of swan neck deformity due to chronic mallet finger cases treated with SORL reconstruction using lateral band technique.

CASE PRESENTATION: We presented 2 case of swan neck deformity due to chronic mallet finger. A 21-year-old male with deformity of the left index finger for 2 years with with extension lag 50° and -20° PIP joint hyperextension and A 18-year-female with deformity of right ring finger for 4 years with extension lag 40° and -20° PIP joint hyperextension. We performed SORL reconstruction using lateral band technique. Ten weeks after surgery, patient achieved good range of motion and stability of PIP and DIP joint was obtained.

DISCUSSION: SORL reconstruction in a finger with a chronic mallet deformity coordinates extension of PIP and DIP joints by a dynamic tenodesis effect. This concept improves stability of both DIP and PIP joints by linking the volar flexor sheath to the lateral aspect of the terminal tendon using lateral band, thereby providing a mechanism of for automatic DIP joint extension upon active PIP extension.

CONCLUSION: SORL reconstruction using lateral band technique may be a good choice for treating swan neck deformity.