1 Principles topenlarge
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.
Screw vs. plate fixation
When fixing this fracture, one should strive for maximal stability.
In a single-plane fracture with good bone stock, a single interfragmentary lag screw is adequate.
2 Approach and reduction topenlarge
Jones fractures can best be approached through a lateral incision to the fifth metatarsal (see Lateral approach to MT5).
Reduce the fracture under direct vision. Since it is a single-plane fracture, absolute stability is required. Secure and maintain the reduction with pointed reduction forceps.
3 Screw fixation topenlarge
Screw size will vary with the canal size. The screw must be of sufficient diameter to obtain purchase and to generate compression.
Depending on the size of the canal, a 3.5 mm or 4.5 mm cortex screw is chosen, but, in larger individuals, a 6.5 mm cancellous screw may be necessary.
Alternative: lag screw insertion
An alternative technique is lag screw fixation.
The screw enters the styloid process through the peroneus brevis tendon insertion and is angled obliquely medially and distally. It gains purchase in the strong medial cortex distal to the fracture.
The proximal fragment is overdrilled as a gliding hole to allow interfragmentary compression. Screw size should be selected according to the size of the bone. 3.5 or 4.0 mm is usually sufficient.