- General complications of anaesthesia and surgery: should be relatively low for most people as most hallux valgus surgery is short-duration daycase surgery. Need to be discussed with patient individualised by general medical condition and past anaesthetic history.
- Thromboembolic disease: the incidence of DVT is less than 5%, almost all distal thrombi. The risk of pulmonary emboli in the average patient is minimal. There is no need for routine thromboembolic prophylaxis, but this may be required in high-risk patients.
- Wound problems: vary from minimal to about 10%, not particularly dependent on procedure. Probably most important to know one's own wound healing problem/infection rate.
- Nerve injury: the true rate of dorsomedial cutaneous neuroma is about 5%. The rate may be minimised by using a medial rather than a dorsomedial approach. Regional pain syndrome occurs in probably about 2%. It's important to warn patients of these risks as they may end up worse than they started.
- Recurrent deformity: reported rates vary from 5-20%. Fokter's long-term (>20 year) follow-up of the Mitchell osteotomy showed an increasing rate of recurrent deformity after 10 years, although studies of the Mann and proximal wedge osteotomies over 10 years have not reported this. Klosok's RCT comparing the distal chevron and Wilson osteotomies showed a higher rate of recurrence in the chevron, possibly because the Wilson decompressed the joint more. It would be interesting to see if this was repeated comparing the Mitchell and chevron.
- Recurrent deformity usually presents as recurrent bunion pain, but in Klosok's study it also produced metatarsalgia. Recurrent deformity is often less severe than the original problem, but some patients will require revision. If bone stock and soft tissue problems permit, a repeat of the previous procedure may be enough; however, if additional correction is required, a more extensive procedure may be necessary, such as a proximal osteotomy after failed chevron. Recurrence may be mainly because hallux valgus interphalangeus or DMAA were not addressed originally and an Akin osteotomy may be needed.
- Metatarsalgia: reported rates vary from 5-40%. The Keller and Wilson procedures have high reported rates, but not in all series. Henry and Merkel both showed that >10mm shortening of the 1st MT shaft in the Mitchell osteotomy inevitably resulted in metatarsalgia, but dorsal malunion was often present as well. The scarf osteotomy, in which the distal fragment is displaced plantarward, seems to have a low incidence of metatarsalgia, but dorsal displacement due to "troughing" can be an exception, and most pressure studies have failed to show rebalancing of forefoot pressure after the scarf. Recurrent hallux valgus deformity can also defunction the first ray and lead to metatarsalgia. Metatarsalgia is not entirely predictable. However, excessive first ray shortening, dorsal malunion and recurrent hallux valgus are the main precipitating factors, and should be avoided as far as possible. Most patients with metatarsalgia post-operatively can be managed with chiropody, careful choice of shoes or a metatarsal dome insole. Recurrent deformity and malunion may be best managed with a revision. Shortening is usually best managed by controlled shortening of the lesser rays; we prefer the Weil osteotomy for this.
- Over-correction (hallux varus): rates vary from 0-5%. The main precipitating factors are probably excessive medial eminence resection, excessive lateral release and fibular sesamoidectomy (in the traditional McBride procedure), although there have been few systematic studies. Fortunately, hallux varus is often well-tolerated, but may lead to pressure on the shoe. Medial capsular release and lateral capsular plication or EHB tenodesis can give stable results, but in some patients a fusion is better.
- MTP joint stiffness: may occur after any procedure and the rates have not been well reported. Lateral release increases the rate of stiffness. Other causes include arthritis and an unrecognised congruent joint. Few pateints require intervention, but a few with a painful stiff joint may be best with a fusion.
- Avascular necrosis of the capital fragment: the true rate is about 1%. Although it is said to be associated with the distal chevron osteotomy, this is probably spurious. Most AVN is asymptomatic; occasionally segmental metatarsal head collapse leads to symptomatic OA needing a fusion or excision arthroplasty.