A Guide To The Percutaneous Bunionectomy

Minimally invasive techniques for hallux valgus feature minimal soft tissue dissection and can facilitate earlier weightbearing. This author discusses appropriate patient selection and evaluation, surgical technique pearls and how to address common post-op concerns with percutaneous bunionectomies.

Hallux valgus correction is one of the most common procedures podiatrists perform. Researchers have described many procedures since Reverdin reported his technique in 1881.¹ A PubMed search on hallux valgus correction will yield multiple studies that report procedural equivalency. The studies tend to measure patient satisfaction, pre- and post-radiographic correction, demographics and other factors that validate a variety of correction methods.  

The common theme in a majority of the literature is the focus on an open surgical approach to bunion correction utilizing definitive fixation. This approach generally involves a long dorsal or medial incision with exposure of capsular and bony structures. One performs the correction with direct visualization and achieves fixation using either plates or screws. However, recently, there has been an increasing body of work that provides evidence of a minimally invasive “percutaneous” alternative to the traditional open surgical method.^2-4    

Bosch and coworkers first described this method in 1990 with a subsequent follow-up article of their findings in 2000 providing seven- to 10-year follow-up.^5,6 The technique involved performing a through and through extrarticular/extracapsular osteotomy of the first metatarsal via a 5 mm incision. They stabilized the fragment through percutaneous placement of a wire, which they removed four weeks after surgery.

The authors allowed protective full weightbearing in a surgical shoe. In 114 feet, the authors reported significant reduction in radiographic measurements and 81 percent satisfaction with no pain in 95 percent of the patients at seven- to 10-year follow-up.

In 2005, Magnan and colleagues presented their results in following the method described by Bosch on 118 patients with a follow-up of two years.³ They reported significant correction from preoperative to postoperative radiographic parameters in the study patients. Ninety-one percent of patients reported satisfaction.

Giannini and colleagues in 2008 published their modification on this method and termed it SERI (simple, effective, rapid, inexpensive).⁷ The authors used this term to describe the osteotomy with minor modifications to the method described by Bosch.^5,6 The authors reported a 92 percent excellent to fair satisfaction rate in 54 patients who had the surgery.⁷

Key Insights On Patient Selection And Evaluation
The selection criteria for percutaneous bunionectomy fit a wide range of patients. As a general rule, any patient who is capable of having traditional elective bunion surgery safely and can understand general postoperative guidelines is eligible. The importance and emphasis are on the practitioner knowing the patient. Patients with a history of poor vascularity, general non-adherence, uncontrolled diabetes and failed previous open bunion surgeries are not suitable patients for this technique. Smoking is a concern but is not a contraindication to performing this procedure. (I do not perform the procedure on active smokers.)

During the physical exam, the patient must have a reducible hallux valgus deformity in the transverse plane. The surgery is contraindicated in patients with stiff arthritic joints secondary to hallux limitus/rigidus or other etiology. Hypermobility of the medial column or metatarsocuneiform joint is not a contraindication to performing the technique. An elevated or plantarflexed first ray is not a contraindication, but one must address the deformity with appropriate translational maneuvers during the procedure. Radiographic parameters correspond with the clinical findings.

Currently, I do not have an upper threshold for the intermetatarsal or hallux valgus angle. I have performed this technique on patients with intermetatarsal angles up to 20 degrees and a hallux valgus angle of 40 degrees. Additionally, I would not perform this technique on individuals with a loss of joint space due to degenerative arthrosis and periarticular bone spurs. Metatarsus adductus is not a contraindication.  

What You Should Know About Positioning And The Surgical Technique
Ensure supine positioning of the patient. Prep the extremity to the thigh with a large bump below the thigh that allows for the knee to bend at a 30 to 45 degree angle on the operating table. This position allows the solo surgeon to utilize both hands for stability and manipulation. Additionally, having the foot in a near plantigrade position facilitates greater ease in obtaining anterior-posterior/lateral fluoroscopy images with minimal movement of the radiographic equipment, thus saving time.  

Step 1. Insert a 2 mm Kirschner wire in an extraperiosteal manner from the medial aspect of the great toe to the medial aspect of the first metatarsal head with fluoroscopic guidance. The goal is to keep the wire midline between the dorsal and plantar aspects of the metatarsal as close to the bone as possible and not in the subcutaneous tissue. Maintaining close proximity to the bone will prevent skin necrosis and prevent irritation of the dorsomedial hallucal nerve.

Step 2. Make a 5 mm skin incision at the medial aspect of the first metatarsal at the level of 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 aids in easier 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 initial drill hole for the low energy osteotomy. Place additional 1.8 mm wires above and below, creating multiple drill holes in the intended path of the osteotomy.

Step 4. After making the multiple drill holes, one can use an osteotome or a mini-micro sagittal saw to complete the osteotomy.

Step 5. Advance the 2 mm K-wire slightly through the medial incision while simultaneously placing a Kelly hemostat through the incision into the shaft of the first metatarsal. Manipulate the hallux with the K-wire 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. Use fluoroscopy to confirm this corrected position and K-wire placement in the shaft of the metatarsal in the anterior-posterior and lateral views. Then advance the K-wire into the medial cuneiform for additional stability.  

Close the incision with 4.0 Monocryl suture (Ethicon). No lateral release or adjunctive soft tissue capsule/tendon balancing procedures are necessary.   

What The Postoperative Regimen Entails
Postoperative dressings consist of 4x4 gauze, ABD pads, cast padding and an Ace bandage. There is no need for additional splinting of the hallux with gauze or tape. The patient bears weight immediately in a flat postoperative shoe. Instruct the patient to leave the dressings in place until the first postoperative visit and ambulate as tolerated for activities of daily living (bathroom, dinner, transfers, etc.).

The patient usually presents in the office at one week post-op for dressing removal. Obtain radiographs to confirm that the hardware and intraoperative position are unchanged. The patient may take regular soap and water showers after one week and one should provide pin care instructions. Pin care instructions consist of applying iodine to the pin after showers and using a circumferential gauze wrapping to limit edema and protect from pin site infection.

The patient maintains weightbearing as tolerated in a surgical shoe until the second postoperative visit. The visit occurs four weeks after the procedure for pin removal and transition into a sturdy tennis shoe. One can remove the pin with sterile pliers in the office setting, usually without local anesthesia. The patient transitions to shoes and starts gentle range of motion exercises of the metatarsophalangeal joint. Obtain follow-up radiographs at eight and 12 weeks. Patients may usually pursue full activity and sports between eight to 12 weeks postoperatively based on healing and callus formation.

Addressing Common Concerns
The most common concern is a pin site infection. Though this can occur, it is easily preventable if the patient follows the postoperative pin care instructions and is vigilant in protecting the pin. One can usually manage local pin site infections with oral first-generation cephalosporins or clindamycin for those who are allergic to penicillin. The infections usually resolve within a few days of starting the antibiotic regimen. So far none of my cases have gone on to osteomyelitis or deep space infections.

Another concern is the stability of the hardware and the capital fragment. The hardware crosses the metatarsocuneiform joint and is surprisingly stiff and stable during the postoperative period. Not crossing the joint can increase the likelihood of loosening with weightbearing. I have had three cases of premature hardware loosening at three weeks. The cases were for varying reasons but there was no adverse effect or loss of surgical correction in two of the cases. One case necessitated a return to the operating room for an exchange of the hardware and the patient healed without loss of correction or further complications.  

The hardware provides relative stability, not fixation to the capital fragment. The fixation not engaging the metatarsal head can create anxiety for the novice since AO fixation principles are ingrained in most foot surgeons. Although there is a lack of direct primary fixation, the fragment is very stable due to the limited soft tissue dissection. The capital fragment maintains the tibial and fibular sesamoid ligament attachments along with the dorsal and plantar capsule/soft tissue attachments that are normally disrupted in open surgery. Accordingly, the pin provides a stable buttress, which prevents the capital fragment from losing correction. The overcorrected hallux and long lever arm of the pin fixation stabilized from the hallux to the cuneiform add additional stability, which prevents rotation. Dorsal translation can occur but I have not seen it be a factor with maintenance of fixation.

The pin can create additional irritation of the dorsal medial hallucal nerve. This can cause numbness in the postoperative period and after pin removal. The sensation returns a few weeks after pin removal and so far, I have had no cases of lasting paresthesias to the medial aspect of the great toe.   

There are also anatomical concerns in regard to the bony overhang that remains after completing the osteotomy. The technique described by Bosch and Magnan does not involve removing the medial flare on the shaft of the first metatarsal after the osteotomy.6,8 Magnan and Bosch comment that in their cohort of patients, bony remodeling reduced the irritation associated with the shaft to less than 1 percent. The authors also recommended performing the osteotomy with a slight obliquity, which decreases the likelihood of shaft-related irritation.

I found these principles to be true in many cases. However, if I feel the shaft protruding intraoperatively, I tend to remove the bony flare to decrease the likelihood of post-healing irritation. As expected, this is most common in patients with higher intermetatarsal angles.  

Why Percutaneous Bunion Correction Is Valuable
There are numerous benefits to the percutaneous method of correction.

Minimal soft tissue and bony dissection with multiplanar correction. Minimal dissection decreases the swelling associated with more extensive dissections. This in turn decreases pain and allows for an earlier functional return to normal weightbearing activity. A through and through osteotomy allows for correction in the sagittal, transverse and frontal planes. This amount of control makes it really easy to correct all aspects of hallux valgus deformity without the use of additional soft tissue procedures.

Decreased operating time. Despite a learning curve, once the surgeon gains familiarity with the maneuvers associated with surgical correction, operating room time is significantly decreased and one can complete most cases within a half hour.

Earlier weightbearing. Increased dissection and placement of hardware can lead to a loss of fixation and fragment stability with premature weightbearing. Incision dehiscence due to early weightbearing may be a concern in certain populations. This method decreases those concerns, thus promoting earlier return to ambulation and mobility for all patients.

Cosmetic incision. Traditional exposure techniques can create visible, large, painful and hypertrophic scars that can be unappealing. This method leaves minimal scarring, which is not readily visible to the average person.  

Inexpensive. Kirschner wire fixation is cost-friendly in comparison with traditional fixation in a changing healthcare environment in which the burden of costs are shifting onto patients.⁷ Certain healthcare plans and patients are seeking providers that can provide excellent care at a lower cost. Though this is not a major concern at the moment, it is something worth paying attention to in the evolving healthcare environment.

Defusing Concerns About The Procedure
Despite the various positives, the percutaneous bunionectomy method is not without controversy. Some surgeons feel this method is fraught with complications and bound for failure.

However, the evidence does not side with the naysayers. Multiple articles have looked at this method and reported results with statistically significant data relating the equivalency of the minimally invasive method in comparison to traditional 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.⁹ 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.

As of now, there is only one publication to date that discussed the failures of a minimally invasive approach. In 2007, Kadakia and coworkers reported on 13 patients who had a minimally invasive bunionectomy.¹⁰ The surgeons abandoned the study due to a high rate of complications including infection, non-union, osteonecrosis and malunion. The authors felt this procedure had an unacceptable rate of complications and did not recommend this method for bunion correction.

However, Kadakia and colleagues did not follow the technique as described by Bosch and Magnan.¹⁰ In 2013, Magnan commented that the modifications introduced by Kadakia to the surgical steps excluded it from consideration similar to a minimally invasive correction as described by Bosch, Magnan and Giannini.⁸   

In Conclusion
Though the method detailed above is a modification of the method described by Bosch and Magnan, the essence of the technique is the same with some thoughtful alterations.^3,5,6 Podiatric surgery has a negative relationship with minimally invasive approaches to hallux valgus correction due to suboptimal results attributed to surgeons in the 1970s and 1980s.¹⁰ Unfortunately, hallux valgus is singled out and bears the brunt of the negativity with anything relating to minimally invasive correction.

Surgeons praise minimally invasive methods of repair for lateral ankle stabilization, osteochondral lesions, calcaneal osteotomies, calcaneal fractures, ankle fusion, brachymetatarsia and many others for their ingenuity. This attitude can only be due to a cherry picking bias that perpetuates the classrooms and lecture halls of our profession. The surgical modifications take this history into account. Therefore, one does not perform the osteotomy with a burr but instead uses multiple drill holes and an osteotome in a manner similar to the corticotomy technique for limb lengthening.  

My interest in this topic began with the Magnan publication while I was a resident and the interest has carried over into my clinical practice.³ I have performed this procedure since starting my practice four years ago and many of the fellows who have left our institution are performing this method in their practice around the country. We have recently submitted our multicenter study of patients who have had correction with this technique. The study includes over 100 patients with long-term follow-up.

In closing, I do not claim that the percutaneous method is superior to an open method. Those who perform open correction well should continue with their preferred method.

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.

References

1.     Reverdin J. De la deviation en ehors du gros orteil et de son traitement chirurgical. Tr Internat Med Congr. 1881; 2:406-12.
2.     Siddiqui N, LaPorta G. Emerging insights on minimally invasive hallux valgus correction. Podiatry Today. 2014; 27(9):26-32.
3.     Magnan B, Pezzè L, Rossi N, Bartolozzi P. Percutaneous distal metatarsal osteotomy for correction of hallux valgus. J Bone Joint Surg Am. 2005;87(6):1191-9.
4.     Giannini S, Ceccarelli F, Bevoni R, Vannini F. hallux valgus surgery: the minimally invasive bunion correction (SERI). Techniques Foot Ankle Surg. 2003; 2(1):11–20.
5.     Bosch P, Markowski H, Rannicher V. Technik und Erste Ergebnisse der Subkutanen Distalen Metatarsale, I Osteotomie. Orthopaedische Praxis. 1990; 26:51-56.
6.     Bosch P, Wanke S, Legenstein R. Hallux valgus correction by the method of Bosch: a new technique with a seven-to-ten-year follow-up. Foot Ankle Clin. 2000;5(3):485-98S.
7.     Giannini C, Faldini F, Vannini F, et al. The minimally invasive osteotomy  “S.E.R.I.” (Simple, Effective, Rapid, Inexpensive) for correction of bunionette deformity. Foot Ankle Int. 2008; 29(23):282-286.
8.     Magnan B, Bondi M, Mezzri S, Bonetti I, Somalia E. Minimally invasive surgery of the forefoot: current concept review. Int J Clin Med. 2013; 4(6):11-19.  
9.     Chiang CC, Lin CF, Tzeng YH, Huang CK, Chen WM, Liu CL. Distal linear osteotomy compared to oblique diaphyseal osteotomy in moderate to severe halluxvalgus. Foot Ankle Int. 2012;33(6):479-86.
10.     Kadakia AR, Smerek JP, Myerson MS. Radiographic results after percutaneous distal metatarsal osteotomy for correction of hallux valgus deformity. Foot Ankle Int. 2007;28(3):355-60.

For further reading, see “Emerging Concepts With Percutaneous Osteotomies” in the May 2014 issue of Podiatry Today. For an enhanced reading experience, check out Podiatry Today on your iPad or Android tablet.