The distal interphalangeal joint is distended and the arthroscope inserted using routine technique through a stab incision located 2 cm proximal to the coronary band and 2 cm lateral to the sagittal plane.
A second stab incision is performed at the same level and same distance from the sagittal plane. The joint is explored with a probe. To improve visibility and facilitate recognition of the fragment, excessive villus proliferation is removed with the shaver. The use of a Holmium YAG-Laser has also been described.
The fragment is identified (arrow) and the fragment is partially loosened with a periosteal elevator.
Eventually it is firmly grabbed with toothed holding forceps. Using rotating movements while firmly holding the fragment, the forceps is withdrawn from the joint. Occasionally, the skin incision has to be slightly enlarged to allow fragment removal.
An alternate method is the use of a 4.5 mm oval shaver bur to grind the fragment down.
After complete removal of the fragment the fragment bed (arrow) and rest of the joint is inspected and if needed additional small bone or cartilage are fragments removed.
The intraoperative lateromedial radiograph assures complete removal of the fragment.
3. Treatment: large fragments
The distal interphalangeal joint is distended and the arthroscope inserted through a stab incision located 2 cm proximal to the coronary band and 2 cm lateral to the sagittal plane using routine technique.
A second 1-cm stab incision is made in the sagittal plane down to the fragment, approximately 2 cm proximal to the coronary band. A spinal needle is carefully inserted through this incision and the extensor tendon under arthroscopic supervision. Advancement of the needle along the articular surface of the fragment in the sagittal plane occurs under arthroscopic supervision as well. This needle serves as a guide during screw insertion. Careful manipulation of the needle may also assist during anatomical reduction of the fragment.
The incision is parted and a hypodermic needle is inserted down to the tip of the extensor process at a slightly different angle.
An alternate option is to insert a 2 mm drill bit protected by the corresponding guide and advance it into the fragment for 6-8 mm. Again the orientation of the drill bit is checked with the help of a lateromedial radiograph.
Drilling the glide hole
The drill bit is removed and the 3.5 mm glide hole is prepared across the fragment.
Dependent upon the radiographically identified 2 mm drill bit orientation, corrections in entry point and/or drill bit orientation are taken in consideration during drilling, if deemed necessary.
With the help of the 2.5 mm drill guide inserted into the glide hole anatomical reduction of the fracture is achieved under arthroscopic observation.
Once achieved, the thread hole is prepared with the 2.5 mm drill bit. Frequent radiographic control of the thread hole depth is advisable.
The countersink is used carefully to prepare a depression for the 3.5 mm screw head. The depth of the blind hole is determined and the threads are carefully cut along the thread hole.
A screw 4 mm shorter than the determined hole depth is inserted and carefully tightened.
Maintenance of fragment fixation is arthroscopically and radiographically evaluated.
4. Treatment: large chronic fragments
Large chronic fragments can be split before removal.
An alternate, more time-saving method is the use of a large 4.5 mm oval shaver burr to grind the often relatively soft fragment away.
The fragment is gradually ground away. The debris is continuously suctioned off. Care is taken not to damage any intact articular surface (arrows).
The fracture bed is examined with a hook probe to detected any additional loose fragments.
Intraoperative radiographs are taken to ensure complete fragment removal. This is especially important in large fragments, because small chips that developed during fragmentation may still be present in the joint. Any fragment detected should be removed.
The joint is thoroughly lavaged and the skin incisions closed with simple interrupted sutures using a mono-filament suture material.
The distal limb is protected by a sterile pressure bandage.
5. Rarely occuring fracture configurations
Under exceptional circumstances, frontal plane fractures can occur that extend distally towards the tip of the distal phalanx.
Note: Two washers (arrow) are taped over the dorsal hoof wall to assist in the determination of the ideal entry point for the cortex screw.
These fractures cannot be treated by means of fragment removal, because they extend too far distally. They are either treated conservatively or through internal fixation using cortex screws in lag fashion in a dorsopalmar/plantar direction.
The horse is kept in a box stall for 10 days. The bandage is changed after 2 days. Follow up radiographs are usually taken at 60 days postoperatively before returning to training. Intra-articular medications depend on surgeon’s preference and the degree of articular damage encountered during surgery.
The horse is kept in a box stall for 60 days. The bandage is changed after 2 days and then at 4-day intervals.
Intra-articular medications depend on surgeon’s preference and the degree of articular damage seen.
Follow up radiographs are usually taken at 60 days postoperatively. Progression of follow up management depend to a great extent upon the results of the follow up radiographic evaluation.