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Emerging Insights On Minimally Invasive Hallux Valgus Correction
Hallux valgus i
s a common first ray deformity that can affect the stability of the forefoot. Those with the deformity have complaints of pain, difficulty with ambulation and cosmetic concerns. When conservative measures fail to provide relief, surgical intervention is necessary to realign the osseous and soft tissue structures that contribute to this deformity.
Traditionally, surgeons have employed open procedures (chevron, scarf, Lapidus) to correct the anatomic and biomechanical forces that contribute to hallux valgus.1-7 More recently, there has been an interest in performing hallux valgus correction through a less invasive approach.8-12 Authors have used various terms, including percutaneous distal metatarsal correction, distal linear osteotomy and minimally invasive distal metatarsal osteotomy among others, to describe this approach.9,13
This approach to “bunion surgery” occurs routinely in Europe and Asia, but it has yet to gain popularity among podiatric surgeons in the United States. While we have been routinely performing the procedure and there are positive results in the literature, we find that podiatric surgeons are reluctant to perform this method of correction for various reasons. Lack of stability, unpredictable healing and prominent metatarsals are common concerns.14
Accordingly, our goal is to describe the osteotomy and discuss the benefits in comparison to traditional open procedures. The benefits of this approach are:
• Cosmetic incision
• Minimal soft tissue/bone dissection
• Low energy osteotomy
• Shorter recovery
• Greater patient satisfaction
A Step-By-Step Guide To The Surgical Technique
When correcting a hallux valgus deformity, we use a modified minimally invasive approach that Magnan and colleagues described.8 Place the patient in a supine position on a radiolucent table and ensure the use of local or general anesthesia. No tourniquet is necessary. Prep the extremity in an aseptic fashion to the level of the thigh. Prepping to the thigh allows for knee flexion, which can be helpful in obtaining anteroposterior fluoroscopy images during the procedure. 
Step 1. Insert a 2 mm K-wire extraperiosteally from the medial aspect of the great toe to the medial aspect of the first metatarsal head under fluoroscopy. The goal is to keep the wire midline between the dorsal and plantar aspects of the metatarsal as close to the bone and not in the subcutaneous tissue. Maintaining close proximity to the bone will prevent skin necrosis and dorsal medial hallucal nerve irritation.
Step 2. Make a 5 mm skin incision at the medial aspect of the first metatarsal at the level of the metaphysis-diaphysis. Deepen the incision to bone and use iris scissors to elevate the soft tissue dorsally in line with the osteotomy. Elevating the soft tissue helps prevent entrapment of the extensor tendon and ensures a smoother translation of the capital fragment after the osteotomy. 
Step 3. Then insert a 1.8 mm K-wire medial to lateral as a guide and an initial drill hole for the low energy osteotomy. Place additional 1.8 mm wires above and below until this creates multiple drill holes in the intended path of the osteotomy.
Step 4. After making multiple drill holes, use an osteotome or a mini- or microsagittal saw to complete the osteotomy.
Step 5. Advance the 2.0 mm K-wire slightly through the medial incision while simultaneously placing a Kelly hemostat through the incision into the shaft of the first metatarsal. With the K-wire, manipulate the hallux into a varus position. Use the hemostat to translate the capital fragment until the lateral cortex of the metatarsal shaft and medial aspect of the metatarsal head are in contact. 
Step 6. One can use fluoroscopy to confirm this corrected position and K-wire placement in the shaft of the metatarsal in anteroposterior and lateral views. Then advance the K-wire into the medial cuneiform for additional stability. Close the incision with a 4.0 Monocryl suture (Ethicon).
A Closer Look At The Research And Clinical Experience
Surgeons traditionally perform hallux valgus correction open with soft tissue and bony correction. The technique we discussed above is designed around bone repositioning without the need for capsular reefing/repair or additional phalangeal osteotomies to address the components of a bunion deformity.
This approach varies from traditional methods. However, the literature supports results that are equivalent to traditional hallux valgus correction. Bosch and colleagues reported results on 114 feet that had a minimally invasive osteotomy for hallux valgus correction.12 In the study, they noted a correction of the average preoperative hallux valgus angle of 36 degrees to 19 degrees while the average intermetatarsal angle went from 13 degrees to 10 degrees. Patient satisfaction in this study was at 81 percent while 95 percent of patients reported no pain after long-term follow-up. 
Magnan and coworkers more recently reported results on 118 patients.8 The average preoperative intermetatarsal angle and hallux valgus angle were 12.3 degrees and 31.5 degrees respectively. Postoperatively, these angles improved to 7.3 to 13.7 degrees respectively. Patient satisfaction was reportedly 91 percent at an average of 35.9 months.
Researchers have also evaluated the effectiveness of traditional open procedures versus minimally invasive hallux valgus procedures. Chiang and colleagues reported a retrospective radiographic review on 86 feet, comparing the outcomes of the Ludloff osteotomy with the minimally invasive distal first metatarsal osteotomy for hallux valgus.13 The findings of the study led the authors to report that the minimally invasive approach had equivalent clinical results in comparison to the Ludloff osteotomy. However, the authors also reported that minimally invasive correction had less recurrence, better correction and was an easier technique.
However, there are concerns about the minimally invasive osteotomy. Kadakia and coworkers reported on 13 patients who had minimally invasive distal osteotomies.14 The authors abandoned the study due to a high complication rate with problems including infection, nonunion, osteonecrosis and malunion. The authors felt this procedure had an unacceptable rate of complications and did not recommend it. A critique is that the authors adopted too many modifications to the original technique when performing the procedure, thus resulting in the complications they reported. 
Another common concern is in regard to the distal medial corner on the shaft of the metatarsal, which one does not resect during a minimally invasive osteotomy, and whether it can cause soft tissue irritation. In our literature review, this was a concern in 1 to 2 percent of the population.12 It was not a source of complaint in other studies, likely due to the angulation of the minimally invasive osteotomy.8 Additional concerns focus on the stability of the minimally invasive osteotomy. The minimally invasive osteotomy is not as inherently stable as a chevron osteotomy, but in our review of the literature and our own experience, the patients are able to ambulate starting on postoperative day one with a nonunion rate/malunion rate similar to those who have had traditional internal fixation.8-10,12-13 This is also true for other complications such as hallux varus and infection when one compares the open procedure to the minimally invasive approach.13
Surgeons may also be reluctant to perform the minimally invasive procedure due to the reliance on the “corrective device” when translating/fixating the osteotomy. The procedure, as described by Magnan and Bosch, utilized a grooved device that guides the 2.0 mm K-wire into the shaft of the metatarsal.8,12 Not having the device can be a limiting factor in performing the procedure. However, we have performed this procedure with minor modifications that substituted the grooved instrument with those instruments that are routinely available in all operating theaters. We speculate that training bias with using internal fixation and open techniques may also create an apprehension for some in performing the minimally invasive bunionectomy. 
We have been performing the minimally invasive bunionectomy routinely for mild to moderate hallux valgus deformity with success. We have modified the original procedure and adapted it to be reproducible by podiatric surgeons. This technique is not easy for the novice surgeon and there is a learning curve associated with manipulation of the osteotomy. The article by Kadakia and colleagues is an example of problems that can occur when surgeons make too many modifications to the original technique.14 However, using the aforementioned technique, we have performed this procedure in conjunction with other procedures with successful results.
In Conclusion
We feel the minimally invasive method for hallux valgus correction is a technically sound method in achieving the goals of bunion surgery. We are in the process of reporting a multicenter retrospective review on our cases in an effort to validate the results that surgeons in Europe and Asia have seen.
Dr. Siddiqui is affiliated with the International Center for Limb Lengthening/Rubin Institute for Advanced Orthopedics at Sinai Hospital of Baltimore. He is the Medical Director of Diabetic Limb Preservation at LifeBridge Health in Baltimore and is the Division Chief of Podiatry at Northwest Hospital in Baltimore. Dr. Siddiqui is an Associate of the American College of Foot and Ankle Surgeons.
Dr. LaPorta is the Chief of Foot and Ankle Surgery at Geisinger Community Medical Center in Scranton, Pa. He is a Fellow of the American College of Foot and Ankle Surgeons.
References
1. Park HW, Lee KB, Chung JY, Kim MS. Comparison of outcomes between proximal and distal chevron osteotomy, both with supplementary lateral soft-tissue release, for severe hallux valgus deformity: A prospective randomised controlled trial. Bone Joint J. 2013;95-B(4):510-6.
2. Moon JY, Lee KB, Seon JK, Moon ES, Jung ST. Outcomes of proximal chevronosteotomy for moderate versus severe hallux valgus deformities. Foot Ankle Int. 2012;33(8):637-43.
3. Nery C, Réssio C, de Azevedo Santa Cruz G, et al. Proximal opening-wedge osteotomy of the first metatarsal for moderate and severe hallux valgus using low profile plates. Foot Ankle Surg. 2013;19(4):276-82.
4. Klos K, Wilde CH, Lange A, et al. Modified Lapidus arthrodesis with plantar plate and compression screw for treatment of hallux valgus with hypermobility of the first ray: a preliminary report. Foot Ankle Surg. 2013;19(4):239-44.
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