Weight bearing films of the foot should be obtained to assess adjacent lesser TMT stability. If unstable, fixation of the lesser TMT should also be addressed (see midfoot section).
Proper alignment of the metatarsal heads is a critical goal in restoring the pathomechanics of the forefoot. On the AP view, a normal curved “cascade” (Lelièvre’s parabola) appearance, symmetric with the other foot, is mandatory. See illustration. This ensures that the normal length of the metatarsal is restored.
It is also critical to restore the metatarsals in their axial or horizontal plane so that in the axial or tread view all the metatarsal heads are on the same level.
Any malalignment particularly flexion will recreate focally high pressure during the stance phase and toe-off and will result in pain and subsequent callus formation.
Note that for the first ray, it is the sesamoids rather than the first metatarsal head, that bear weight, and therefore one must look at the sesamoid level in establishing the alignment in the axial or horizontal plane of the first metatarsal.
Minimally displaced stable fractures may be treated nonoperatively, with non-weight bearing in a short leg cast or brace.
Soft tissue injury
Fracture dislocation is often associated with significant soft tissue swelling. Temporary percutaneous pinning with K-wires for stability and alignment may be required prior to definitive fixation.
2. Patient preparation and approaches
This procedure is normally performed with the patient in a supine position.
For ORIF, the approach requires visualization of the articular surfaces of the first TMT and often the base of the first web space.
Lisfranc injuries are often associated with plantar lateral and dorsomedial fragments. Debris must be cleared from the base of the first web space in order to obtain reduction.
A dorsal approach to the first MT is used and extended proximally over the first TMT. The EHL tendon is retracted medially, and the EHB muscle belly and tendon are retracted laterally.
A laminar spreader may be placed between the bases of the first and second metatarsals to expose the web space for debridement of bone fragments and soft tissue, if the Lisfranc ligament has been disrupted.
Capsular and ligamentous attachments are released from the first TMT. A distractor is placed dorsally across the first TMT to expose the joint.
Irrigation and debridement of the joint is performed.
4. ORIF with lag screw and plate
Reduction and preliminary fixation
Reduction of articular fragments is performed and maintained with pointed reduction forceps and provisional K-wire fixation.
A dental pick and elevator may be useful in mobilizing and reducing articular fragments.
If one or two fracture fragments are present, lag screw fixation may be sufficient.
This x-ray shows the internal fixation of a displaced intraarticular fracture of the first metatarsal base with a T-type buttress plate.
5. ORIF with locking plate
Reduction and preliminary fixation
For multiple fragments, locking plate fixation or primary fusion may be performed.
For locking plate fixation, the articular surface is reconstructed and provisionally fixed with 1.25 mm K-wires.
At this time, bone grafting of metaphyseal defects is performed as necessary. Bone grafts may be obtained from the calcaneus or distal medial tibial metaphysis.
A dorsal locking 2.4 mm / 2.7 mm VA LCP T-plate may be contoured and applied. It is fixed to the shaft with a 2.7 mm cortex screw. 2.7 mm locking screws are then placed proximally through the T-portion of the plate to support the subchondral bone.
Two to three 2.7 mm cortex shaft screws should be inserted through the plate distal to the fracture site.
Non-weight bearing is recommended in addition to short leg cast fixation for at least six weeks. In more comminuted fracture patterns, non-weight bearing may have to be prolonged but cast immobilization may be discontinued. These injuries are unstable and require time to heal properly. It is better to err on the side of longer non-weight bearing and immobilization.