The Weil osteotomy is a technique for shortening a lesser metatarsal. A near-horizontal cut is made through the head and neck. The near-horizontal orientation, large surface area and ease of fixation minimise the risk of mal-union or non-union and allow early weightbearing.
Approach
A longitudinal incision in the adjacent interspace is deepened bluntly to the extensor apparatus, which is mobilised from the joint capsule. The dorsal digital nerves are at risk. A longitudinal capsulotomy is made and the metatarsal head delivered into the wound.
Technique
The saw cut begins just below the upper edge of the articular surface. In the second metatarsal it can be kept almost horizontal with respect to the ground; in the other rays it inevitably sloes downward increasingly. The tendency for the head to displace downwards can be counteracted by taking an extra sliver out of the cut. The head is displaced proximally according to the pre-operative plan and fixed with one or two small screws. The remaining “beak” on the upper edge of the metatarsal is excised (alternatively, the beak can be excised back to the planned level of shortening and the head displaced to lie flush with it – this often makes it easier to get the head in the right place.)
Garg et al (2008) described a modification of the Weil osteotomy in which a segment of the metatarsal head/neck is excised obliquely instead of sliding. In a series of 71 case (see below the results and complication rates were similar to the standard Weil.
Aftercare
No protection is necessary unless the bone is very soft or the fixation unstable. The patient can fully weightbear immediately. The MTP joints can become very stiff and it is important for thepatient to mobilise their toes early and to practise flexing them to minimise the risk of non-functioning “floating” toes.
Results
There are no RCTs comparing the Weil osteotomy with any other procedure. Trnka (1999) reported a retrospective comparison between 15 patients who had 22 Helal osteotomies and 15 patients who had 25 Weil osteotomies, all for MTPJ dislocations. The Helal procedures were a historic series and had mean follow-up of 26m compared with 15m for the Weils. The groups were otherwise comparable.The mean AOFAS lesser ray score in the Weil patients was 85/100 and in the Helals 78 (p=0.02). The Weils also had less pain, fewer transfer lesions and fewer recurrent MTP dislocations.Davies and Saxby (1999) reported 50 Weil osteotomies in 42 patients at short-term follow-up of 6-16m. 21 also had hallux valgus correction. 77% were painfree, but 2 still had moderately severe pain. One transfer lesion developed, and there was recurrent subluxation of one MTP joint.
O’Kane and Kilmartin (2002) reported another short-term series of 19 procedures. They used the line between the apices of the 1st and 4th metatarsal heads as a reference to determine the amount of shortening, which averaged 5.2mm. Mean AOFAS lesser ray score improved from 44 to 89. They noted 8 floating toes and one transfer lesion. They found no relationship between the amount of shortening and either non-functioning or stiffness of the toes.
Vandeputte (2000) 59 Weil osteotomies in 37 feet and 32 patients. 33 of these joints were dislocated pre-operatively. They operated on 33 2nd metatarsals, 22 3rd metatarsals and four 4th metatarsals. Patients rated 32/37 feet good or excellent and the mean AOFAS score increased from 59 to 81. There were four feet with transfer lesions and 3 with persistent pain. 36% of the toes were stiff and 22% defunctioned, and 5/33 MTP joint dislocations recurred. Improvements in pain were correlated with reduction in sub-metatarsal pressure.
Hofstaetter (2006) reported 7yr results in 53 toes (25 feet, 24 patients). Some also had hallux valgus corrections and/or hammertoe straightening. The mean AOFAS score improved from 48 to 83, with some improvement continuing between 1 and 7 years. One patient had continuing pain, another developed a painful prominent screw tip with a sub-metatarsal callus which resolved on removal of the screw. Of 25 feet with pre-operative dislocations only 3 still had dislocated MTP joints at 7 years. 68% of toes did not contact the ground on standing, but this did not affect the clinical outcome.
Garg et al (2008) described a modification of the Weil osteotomy in which a segment of the metatarsal head/neck is excised obliquely instead of sliding. 71 osteotomies in 48 patients were followed up for 6-26 months. 2/3 of patients had the surgery mainly for metatarsalgia; the others were for toe deformities, dislocation and instability.Mean AOFAS score at follow-up was 87.6/100 and 85% of patients were satisfied (25% with some reservations).27% had floating toes, 19% transfer lesions, 15% infection and 10% wound healing problems.
After Weil osteotomy, it is common for the toe not to touch the ground in the standing position (“floating toe”). Most series report an incidence of about 20%, although Hofstaetter (2006) found that 2/3 of their patients had floating toes. Migues (2004) highlighted the problem of floating toes in their report of 70 operations. They found that the amount of metatarsal shortening did not predict the development of a floating toe, but it was commoner (50%) when a PIP joint fusion was also carried out. Trnka (2001) showed, in a cadaver model, that the osteotomy plane is always inclined plantarwards, and this causes the lumbrical muscles to change from flexors of the MTP joint to extensors. Boyer and deOrio (2004) avoided floating toes in patients who also had a flexor-extensor transfer and trans-articular pin fixation, but 11/13 MTP joints were moderately or severely stiff. Gregg (2007) reported a combination of Weil osteotomy and plantar plate repair. It is not entirely clear how many patients had floating toes, proabably 3/35 (8.6%).
Overall about 90% of patients reported have been satisfied with the results of Weil osteotomy. About 40% of MTP joints are stiff and 25% of toes floating. Transfer lesions occurred in 4%, residual pain in 15% and recurrent subluxation or dislocation of the MTP joint in 13% of those that were dislocated pre-operatively. It may be possible to reduce the incidence of floating toes by formal stabilisation, probably at the cost of more stiffness.