Modified Merritt Splint in Proximal Zone IV and Zone V Extensor Tendon Injuries: Nine Years Rehabilitation Experience in a Single Center

INTRODUCTION:

 Post-operative extensor tendon repair morbidity remains a significant problem despite newer splinting methods. The purpose of our study was to assess outcome of patients treated with a “Modified” Merritt Splint (exclusion of the wrist from immobilization) in proximal zone IV and Zone V extensor tendon injuries.

METHODS:

Patients aged 18-65 who underwent primary tendon repair for uncomplicated single digit (thumb excluded) Zone IV or Zone V extensor tendon injuries were provided with the modified Merritt Splint.  Patients were prospectively followed for 10 weeks post-surgery.  Objective measurements included range of motion and grip strength.

RESULTS:

A retrospective review was conducted for all zones IV and V extensor tendon lacerations in a single institution. 615 charts were reviewed for extensor tendon lacerations from 2006-2013. Fifty-five patients met the inclusion criteria, whom completed the entire 10 week study protocol.  All extensor tendon injuries were repaired primarily with a figure of eight non-absorbable nylon or prolene.  The index finger was the most common affected digit.  Ten weeks post-operatively, all five patients demonstrated excellent range of motion at all joints.  Mean range of motion was: MCP - 85^o, PIP - 102^o, and DIP - 68^o.  Wrist motion was full in all patients.  Grip strength returned to equal the non-injured hand in all but 6 cases.  No evidence of tendon rupture occurred and no patient required a tenolysis.

CONCLUSIONS: 

All patients completing the study demonstrated excellent range of motion with no evidence of rupture or need for tenolysis.  Our results suggest that the “Modified” Merritt Splint is an appropriate method for post-operative treatment of Zone IV and Zone V extensor tendon injuries.