Hallux Valgus Osteotomy

Hallux valgus is a deformity at the base of the big toe, or metatarsophalangeal (MTP) joint, in which the great toe (hallux) is deviated or points toward the lesser toes; in severe types of the deformity, the great toe goes over or under the second toe.

The head of the first metatarsal does not have any musculotendinous attachments. These structures in the great toe bypass the head of the first metatarsal to be inserted into base of the proximal and distal phalanges. When the great toe is in a normal alignment, the tendons and muscle forces exerted around the head and at the first MTP joint are balanced. When there is a malalignment at this joint muscle imbalance gradually worsens the deformity.

Long-standing hallux valgus deformity is associated with a contracture in the overpowering lateral musculotendinous structures and stretching of the medial joint capsule. As the deformity increases, the first metatarsal head becomes prominent medially, giving rise to the bunion deformity.

A number of operative procedures and osteotomies have been devised and or modified over the years. The great variety of procedures and osteotomies underscores the points that not all hallux valgus deformities are similar and that no single osteotomy is versatile enough to treat all such deformities. Therefore, selection of the exact procedure(s) to be employed for operative intervention must be based on careful clinical and radiologic evaluation and planning.

Decision-making requires careful consideration of the following:

• History - Patient age; duration and severity and location of pain; involvement of other joints; response to conservative care; activity level; occupation; expectations
• Comorbid conditions - Diabetes mellitus; rheumatoid arthritis; gout; stroke; any other underlying spastic neurologic conditions
• Physical findings - Severity of deformity; presence of bursitis, cellulitis, calluses, rotational deformity, or pronation; passive reducibility of the hallux valgus subluxation or the bunion deformity; hypermobility of the metatarsocuneiform (MTC) and other joints; pes planus; gastrocnemius contracture; neurovascular status
• Diagnostic imaging - Radiographic evaluation of the hallux valgus; intermetatarsal (IM), interphalangeal (IP), and distal metatarsal articular angles; MTP joint congruity; sesamoid-metatarsal head subluxation; MTC joint congruity or arthrosis; relative lengths of the metatarsals and the parabola at MTP joints 1-5

Failure of conservative care in relieving symptoms due to hallux valgus deformity is an indication for consideration of surgical intervention. Some patients worry that the deformity may become worse and therefore prefer it to be corrected earlier rather than later.

However, rapid progression of a hallux valgus deformity is unusual; therefore, the deformity can be observed and the decision regarding surgery based mainly on symptoms. Pain and discomfort and failure of conservative measures to relieve symptoms and meet lifestyle needs should be the major considerations for surgical correction.

Patients should realize that return to professional or recreational activities (eg, sports or dancing) cannot be guaranteed. They must understand that some residual stiffness, pain, or deformity may be inevitable. After surgery, they may or may not be able to return to their previous level of activity. Therefore, surgery is deferred unless the bunion deformity is interfering with their activities. If patients can eventually resume their previous level of activity after surgery, they will be much more satisfied with the outcome. ^[1]

At present, reputable societies such as the American Orthopedic Foot and Ankle Society (AOFAS) advise against cosmesis as an indication for surgery. Surgery should not be performed just to enable patients to wear fashionable shoes. Patients who have bunion surgery only because they believe that they will then be able to wear a more fashionable shoe are subsequently disappointed if they are still not able to wear the shoes they wanted to wear or if the surgery leaves them with a stiff toe or with pain.

In reviewing more than 300 bunion cases, Coughlin and Jones observed that a third of patients could wear the shoes that they wanted before surgery and that two thirds could after surgery. Unfortunately, this still leaves one third of patients unable to wear their shoes of choice, and this should be explained to those patients who do not have pain but simply want to fit their feet into narrower shoes. ^{[2, 3]}

Patients with poor vascularity are at risk for wound-healing problems and gangrene with loss of toes. Other contraindications include advanced arthrosis of the MTP joint, gout, neuropathy, spasticity of any type (eg, cerebral palsy, cerebrovascular accident [CVA], or head injury), and ligamentous laxity.

Anatomy

The metatarsal bones are roughly cylindrical in form, with the body tapering gradually from the proximal to the distal end. They are curved in the long axis and present a concave plantar surface and a convex dorsal surface.

The first metatarsal is the stoutest and the shortest of the metatarsal bones. The body is strong and of well-marked prismoid form. The base usually has no articular facets on its sides, but occasionally there is an oval facet on the lateral side, by which the first metatarsal articulates with the second metatarsal.

The proximal articular surface of the first metatarsal is large and kidney-shaped; its circumference is grooved (for the tarsometatarsal [TMT] ligaments) and medially gives insertion to part of the tendon of the tibialis anterior; its plantar angle presents a rough, oval prominence for the insertion of the tendon of the fibularis (peroneus) longus. The head is large; on its plantar surface are two grooved facets, on which glide sesamoid bones; the facets are separated by a smooth elevation.

For more information about the relevant anatomy, see Foot Bone Anatomy.

Complication prevention

It is essential to remain constantly aware of the anatomy and location of the neurovascular structures. Careful dissection and retraction of the flaps before execution of the osteotomy is important to prevent soft-tissue damage. Also, thermal damage should be avoided by using a low setting on the driver for the saw, performing irrigation, employing a sharp thin blade with fine teeth, and taking care to unclog the teeth if the same saw is being used.

Jeuken et al published a level II randomized control trial that provided long-term follow-up data on the results of two widely used operative treatments for hallux valgus: scarf osteotomy (36 feet) and chevron osteotomy (37 feet). ^[4] Conventional weightbearing anteroposterior (AP) radiographs of the foot were obtained for evaluation of the IM angle (IMA) and hallux valgus angle (HVA) and for clinical evaluation. The AOFAS rating system for the hallux MTP-IP scale was used, together with physical examination of the foot. These data were compared with the results from the original study.

The Short Form 36 (SF-36) questionnaire, the Manchester-Oxford Foot Questionnaire (MOXFQ), and a general questionnaire including a visual analogue scale (VAS) pain score were used for subjective evaluation. ^[4] The primary outcome measures were the radiologic recurrence of hallux valgus and the reoperation rate of the same toe. Secondary outcome measures were the results from the radiographs and subjective and clinical evaluation.

At 14 years' follow-up, the response rate was 76%. ^[4] In all, 28 of the 37 feet in the chevron group and 27 of the 36 in the scarf group developed recurrence of hallux valgus. One patient in the scarf group had a reoperation of the same toe, compared with none in the chevron group. Current VAS pain scores and results from the SF-36, MOXFQ, and AOFAS did not significantly differ between groups.The authors concluded that the two techniques yielded similar results after 2 years of follow-up. At 14 years' follow-up, neither technique was superior in preventing recurrence.

Wester et al conducted a prospective randomized study to assess radiologic and clinical results after operation for severe hallux valgus, comparing open wedge osteotomy with crescentic osteotomy. ^[5] The study included 45 patients (41 female, 4 male) with severe hallux valgus (HVA >35º, IMA >15º). Mean patient age was 52 years (range, 19-71 y). Treatment involved either proximal open wedge osteotomy and fixation with plate (group 1) or operation with proximal crescentic osteotomy and fixation with a 3-mm cannulated screw (group 2). Clinical and radiologic follow-ups were performed 4 and 12 months after the operation.

In group 1, the HVA decreased from 39.0º to 24.1º after 4 months and to 27.9º after 12 months. ^[5] In group 2, it decreased from 38.3º to 21.4º after 4 months and to 27.0º after 12 months. The IMA in group 1 was 19.0º preoperatively, 11.6º after 4 months, and 12.6º after 12 months. In group 2, the mean IMA was 18.9º preoperatively, 12.0º after 4 months, and 12.6º after 12 months. After 12 months, the AOFAS score improved from 59.3 to 81.5 in group 1 and from 61.8 to 84.8 in group 2. The ratios of the length of the first metatarsal to that of the second were 0.88 and 0.87 preoperatively and 0.88 and 0.86 after 12 months for groups 1 and 2, respectively.

No significant difference was found between the two groups with respect to postoperative improvement of hallux valgus and IMA at 4 and 12 months postoperatively. ^[5]  Postoperative VAS and AOFAS scores were comparable for the two groups, with no significant differences. An expected tendency to gain better length of the first metatarsal with open wedge osteotomy than with crescentic osteotomy was not found. Even though the reductions in IMA and HVA were only suboptimal, the improvement in AOFAS score was comparable to that seen in other similar clinical trials.

Minimally invasive approaches are increasingly being used for hallux valgus surgery. In a prospective randomized study of 50 patients undergoing operative correction of hallux valgus, Lee et al compared percutaneous chevron-Akin (PECA) osteotomy (n = 25) with open scarf-Akin (SA) osteotomy (n = 25). ^[6] Data were collected preoperatively and at 1 day, 2 weeks, 6 weeks, and 6 months postoperatively. Outcome measures included the AOFAS hallux-MTP-IP (AOFAS-HMI) score, the VAS score, the HVA, and the 1-2 IMA.

Both groups showed significantly improved AOFAS-HMI scores after surgery (PECA, from 61.8 to 88.9; SA, from 57.3 to 84.1), with comparable final scores. ^[6] HVA and IMA were also similar at final follow-up. However, the PECA group had a significantly lower pain level in the early postoperative phase (postoperative day 1 to postoperative week 6). No serious complications were observed in either group. The two groups had comparable good-to-excellent clinical and radiologic outcomes at final follow-up. 

Choi et al investigated the efficiency of simultaneous correction of moderate-to-severe hallux valgus deformity and adult-type pes planus in 19 consecutive patients (15 [79%] women, 4 [11%] men; mean age, 44.50 ± 17.13 y; mean follow-up, 31.30 ± 17.02 mo). ^[7] Medial calcaneal sliding osteotomy was performed to correct hindfoot valgus, whereas treatment of hallux valgus was case-dependent.

Postoperatively, mean HVA was 8.40º ± 5.29º, mean IMA was 4.20º ± 2.54º, mean hindfoot alignment angle was 3.09º ± 2.92º, and mean hindfoot alignment ratio was 0.41 ± 0.17. ^[7] Although there was one case of hallux varus deformity occurring as a postoperative complication, there were no cases of postoperative recurrence. The authors found simultaneous correction of hallux valgus and pes planovalgus with a medial calcaneal sliding osteotomy to be effective technique in reducing recurrence of hallux valgus and increasing satisfaction in patients with moderate-to-severe hallux valgus deformity complicated with adult-type pes planus accompanying hindfoot valgus.

McDonald et al prospectively studied 60 patients undergoing right first metatarsal osteotomy for hallux valgus correction surgery with the aim of determining when patients could safely return to driving after the procedure. ^[8]  Testing of patients' brake reaction time (BRT) was performed at 6 weeks and repeated until patients achieved a passing BRT. A control group comprising 20 healthy patients was used to establish a passing BRT. Patients were given a novel driver readiness survey to complete.

At 6 weeks, 51 of the 60 patients (85%) had BRTs of less than 0.85 seconds and were considered safe to drive. ^[8] At 6 weeks, the passing group average was 0.64 seconds. At 8 weeks, 59 (100%) of the patients who completed the study achieved a passing BRT. Patients who had a failing score at 6 weeks had statistically higher VAS pain scores, as well as diminished range of motion (ROM) in the first MTP joint.

On the driver readiness survey, eight (89%) of the nine patients who did not pass disagreed or strongly disagreed with the statement "Based on what I think my braking reaction time is, I think that I am ready to drive." ^[8]  The authors concluded that most patients can safely return to driving 8 weeks after right metatarsal osteotomy for hallux valgus correction; some patients may be eligible to return to driving sooner, depending on VAS score, first MTP ROM, and driver readiness survey results.

Panchbhavi et al measured reduction of the forefoot width in 52 patients after hallux valgus correction with a distal chevron osteotomy and Akin osteotomy. ^[9] A new measurement, the metatarsal span (MS), was introduced as a measure of forefoot width. On pre- and postoperative radiographs, four observers measured the HVA, the first and second IMAs, and the MS. Preoperative HVA ranged from 14° to 48°, IMA ranged from 6° to 25°, and MS ranged from 74.2 to 110.6 mm. Average HVA improvement was 19.4°, average IMA improvement was 6.7°, and average MS reduction was 8.7 mm. No correlation was identified with regard to correction of the HVA or IMA to MS.

Panchbhavi and Lindeman conducted a retrospective analysis (N = 30; 33 feet) to determine the average and maximum corrections achievable with the chevron-Akin double osteotomy. ^[10]  HVA and IMA were evaluated pre- and postoperatively on standard weightbearing AP plain radiographs, and the differences from preoperative to postoperative were calculated. Patients were divided into three groups according to the severity of preoperative hallux valgus (mild [3 feet], moderate [19 feet], and severe [11 feet]). The pre-to-post changes in HVA and IMA and the postoperative values of each angle were compared between severity groups, and the rate of correction to normal was noted in each severity group.

In the mild group, average improvement was 13 in HVA and 6 in IMA; maximum correction was 14 in HVA and 9 in IMA; and three feet (100%) were corrected to the normal range. ^[10] In the moderate group, average improvement was 16.5 in HVA and 5.2 in IMA; maximum correction was 29 in HVA and 9 in IMA; and 18 feet (95%) were corrected to the normal range. In the severe group, average improvement was 28.5 in HVA and 8.8 in IMA; maximum correction was 43 in HVA and 20 in IMA; and nine feet (82%) were corrected to the normal range. These results suggested that the combined chevron-Akin double osteotomy is capable of both small and large degrees of angular correction in hallux valgus.

Tay et al performed a retrospective matched-cohort study comparing outcomes between a group of 30 patients who underwent minimally invasive chevron-Akin (MICA) osteotomy and a control group of 30 patients who underwent open scarf-Akin osteotomy. ^[11]  Outcomes were compared at 6 and 24 months postoperatively. Early postoperative VAS scores were also compared.

Both groups demonstrated significant improvements in VAS score, AOFAS score, and SF-36 physical and mental component scores at 6 and 24 months postoperatively. ^[11] For the MICA group, HVA improved from 23.5º to 7.7º, and IMA improved from 13.5º to 7.5º. For the scarf-Akin osteotomy group, HVA improved from 23.7º to 9.3º, and IMA improved from 13.6º to 7.8º. The first 24-hour postoperative VAS score was significantly lower in the MICA group than in the scarf-Akin group (2.0 ± 2.0 vs 3.4 ± 2.6). However, there were no significant differences in clinical or radiologic outcomes between the groups at 6 and 24 months. 

Lewis et al performed a prospective observational study of patients who underwent primary third-generation MICA with screw fixation for severe hallux valgus. ^[12] The primary outcome was a validated patient-reported outcome measure (PROM), the MOXFQ, assessed a minimum of 2 years after MICA; secondary outcomes were radiographic deformity correction (assessed 6 wk postoperatively), complication rates and other quality-of-life PROMs (EQ-5D and VAS). A total of 106 consecutive feet (n = 78; 73 female, 5 male) met the inclusion criteria; prospectively collected preoperative and 2-year PROM MOXFQ data were available for 86 feet (81.1%).

At 2 years, the MOXFQ score significantly improved for the Pain, Walking and Standing, and Social Interaction domains, from 39.2 to 7.5 and 38.2 to 5.9 and 48.6 to 5.5, respectively. ^[12] Preoperative and 6-week postoperative radiographic data were available for all 106 feet. Mean IMA improved from 18.2º to 6.3º and mean HVA from 45.3º to 10.9º. The complication rate was 18.8%, and the screw removal rate was 5.6%.