Avulsion fractures are the result of side-to-side (coronal) forces acting on the finger, putting the collateral ligament under sudden tension. The ligament is usually stronger than the bone, causing the ligament to avulse a fragment of bone at its insertion.
Avulsion fractures result in marked joint instability.
If the fracture is not displaced, nonoperative treatment is usually indicated (buddy taping to the adjacent finger). Displaced fractures, however, must be internally fixed.
In some circumstances, the fracture is severely comminuted with multiple tiny fragments. It may be preferable to excise the fragments and reattach the collateral ligaments directly to the bone.
Animation of the injury mechanism
Suture anchors or tunneling
Two alternative techniques are available for collateral ligament reattachment: suture anchors, or tunneling. The advantage of suture anchors is the relative ease of the procedure. It is also a time-saving technique. Tunneling is the more demanding procedure, but it is significantly less expensive.
All comminuted fragments need to be removed in order to prevent osteoarthritis. If any fragments remain attached to the ligament, they have to be excised with a fine scalpel.
Visualize the joint
Laterally deviate the phalanx in the opposite direction to gain maximal visualization of the joint (open book). Ensure that all bony fragments have been removed.
4. Option 1: suture anchor fixation
Drill anchor hole
Keep the phalanx laterally deviated to visualize maximally the area of the fracture at the base of the phalanx. Make a perforation of the same diameter as the anchor to be used, as close as possible to the subchondral bone.
Insert the anchor according to the manufacturer’s instructions. Ensure that the whole anchor is completely buried in the bone.
Insert the sutures
Insert the sutures into the free end of the ligament. Reapproximate the ligament to the phalanx and make a loop in each end of the thread as an anchoring pass. Tie a knot to secure the ligament to the phalanx. Reattaching the ligament close to the subchondral bone will ensure a smooth surface for ideal mobility.
If the ligament is reattached too far from the joint surface, there is a sharp edge in the joint which may cause cartilage abrasion and eventually result in degenerative joint disease.
5. Option 2: tunneling
A pair of parallel perforations, using a 1.0 mm drill or a K-wire, can be made as close as possible to the subchondral bone, angled from proximal to distal, and from palmar to dorsal, penetrating the opposite cortex. A drill sleeve for soft-tissue protection is mandatory.
4.0 nonresorbable, threaded sutures, with straight needles, are used. Insert the sutures obliquely through the end of the ligament, make a loop in each end of the thread as an anchoring pass, and thread each needle through a drill hole.
Reapproximate the ligament
Make a small incision in the opposite side of the finger to retrieve the sutures. Cut off the needles, pull the sutures to approximate the ligament, and tie a knot over the cortical bone.
Immobilize the hand in a safe position for at least 3 weeks.
See patient 5 days after surgery to check the wound, clean and change the dressing. After 10 days, remove the sutures. Check x-rays.
The healing process is slower than in bone-to-bone repair and will take 3-4 weeks.
At this stage, remove the splint, and apply buddy strapping.