Sagittal Band Tear “Boxer’s Knuckle”

Do you have a snapping feeling over your knuckle when you make a fist? And are you having difficulty straightening your finger?  

Sagittal Bands are the “tie downs” that connect to either side of our extensor tendons over the back of our hand at the knuckle or metacarpophalangeal joints (MCPJ). Their role is to make sure our tendon stays in place over the MCP joint when making a fist. It also holds the tendon close to the joint when you hyperextend the MCPJ preventing bowstringing. 

If you have ruptured your sagittal band, the extensor tendon slips off to one side of the MCPJ causing a snapping sensation. You are also likely to have difficulty straightening the finger at the MCPJ. This injury is also known as ‘Boxers Knuckle’.  

If the injury has happened recently your hand therapist can make a splint that limits how much the finger flexes or bends at the MCPJ allowing the sagittal band to heal. It is called a relative motion splint. It needs to be worn full time for 6 weeks and the hand can continue to perform light activities. 
Following splinting your hand therapist may prescribe movement and strengthening exercises. 
If the injury is chronic or related to rheumatoid arthritis surgery may be required.  

Written by Carla Bingham (Occupational/Hand Therapist)