Fourth-Generation Minimally Invasive Hallux Valgus Surgery With Guided Percutaneous System: Step-by-Step Surgical Technique

Abstract

Hallux valgus is a common condition in foot and ankle surgery practice. Nonoperative treatment is the first line of management in painful cases. Once these actions have failed, surgical treatment is indicated. Minimally invasive surgery has gained popularity owing to its favorable clinical and radiologic outcomes. Nevertheless, the learning curve of these procedures may be difficult in the initial cases. To solve this problem, some guided devices have been developed. The objective of this technical note is to describe 3-dimensional hallux valgus deformity correction surgery through a guided percutaneous system.

Hallux valgus (HV) is one of the most prevalent pathologies in foot and ankle surgery, with an estimated prevalence of 23% in adults aged 18 to 65 years and 35.7% in those older than 65 years.¹ It is a complex 3-dimensional deformity of the first ray that leads to altered joint mechanics, dysfunction, and progressive pain often at the medial eminence of the first metatarsophalangeal joint.^1,2 Surgical treatment is indicated once nonoperative management has failed and patients have persisting substantial pain and footwear problems.

Depending on the degree of deformity, various techniques can be performed, including soft-tissue and osseous procedures. Nowadays, special focus has been placed on minimally invasive surgery (MIS) to treat HV, which can result in decreased surgical time, reduced postoperative pain and complication rates, and greater patient satisfaction compared with open surgery.^3,4

The current third generation of HV MIS, which combines a minimally invasive chevron-Akin (MICA) osteotomy with internal fixation provided by 2 parallel screws, is increasing in popularity.⁵ Despite the mentioned benefits of HV MIS, the learning curve of the technique may be challenging. Some authors have published technical tips to diminish or avoid complications related to performing osteotomy and screw positioning.^6,7

Recent studies have described the metaphyseal extra-articular transverse and Akin osteotomy (META), defined by some authors as fourth-generation HV MIS.^8,9 The purpose of this technical note is to describe the META procedure using a guided percutaneous system (Pecaplasty; Novastep, Orangeburg, NY), as well as pearls, pitfalls, and risks related to the surgical technique.

Patient Evaluation

The patients who may benefit from this technique are the same candidates for open surgical techniques. Before a surgical approach is proposed, patients should have exhausted conservative therapies, such as changes in footwear and the use of plantar orthoses, as well as symptomatic treatment with analgesics. As with open surgery, this technique is contraindicated in patients with acute or chronic infection, vascular abnormalities of the limb, and severe osteoporosis.

Patients are examined to assess deformities of both the hallux and the rest of the foot. The range of motion of the metatarsophalangeal joint should be systematically evaluated, along with the mobility of the sesamoids. Gait analysis will also be performed, noting any cutaneous signs of vascular pathology or scars from previous interventions that may influence the technique. A weight-bearing radiograph is mandatory before surgery to assess the intermetatarsal angle, the HV angle, the position of the sesamoids, and the proper alignment of the first metatarsal on the lateral radiographic view.

Surgical Technique

The patient is positioned supine with the heel hanging freely over the surgical table; then, local anesthesia and sedation are applied (Video 1). A tourniquet is not mandatory for this procedure. The surgeon’s position is at the medial aspect of the affected foot, regardless of whether he or she is right- or left-handed, while the Fluoroscan system (Hologic) is set up on the contralateral side. Once the foot is prepared and draped at the ankle level, it is set over the Fluoroscan surface. Anatomic structures including the bunion and the midshaft axis of the first metatarsal are marked with a sterile pen (Fig 1).

Fig 1.

(A) Percutaneous incision (arrow) just proximal to intersection between bunion (circle) and first metatarsal shaft (dotted line) in right foot. (B) Intraoperative anteroposterior fluoroscopic view of stab incision placement in right foot. The arrow mark the surgical blade during the stab incision. (C) Stab incision with percutaneous blade in right foot. The arrow show the point where the incision is made with the blade. (D) Stab incision with percutaneous blade avoiding excessive stripping of plantar capsule in right foot.

A percutaneous incision is made just proximal to the bunion at the intersection between the bunion and the first metatarsal shaft; next, the capsule is released with a periosteal elevator, avoiding stripping the plantar capsule (Fig 1). By use of a 2.0 × 20-mm Shannon burr, a transverse extracapsular first metatarsal Bosch osteotomy is completed (Fig 2). Concerning the Bosch osteotomy, it is important to consider the metatarsal formula. The Bosch osteotomy is performed as follows: A 2.0 × 20-mm burr is introduced centrally into the diaphysis along the dorsal-plantar axis at the described point. By use of an oscillating dorsal movement, the osteotomy is made in the upper half of the metatarsal. Then, the same technique is applied in a plantar manner to complete the osteotomy. The mobility of the distal end is verified under fluoroscopy. The metatarsal formula refers to the length relationship between the metatarsals of the foot that can influence load distribution during gait. In cases of index minus, in which the first metatarsal is shorter than the second one, to avoid excessive shortening, it is advisable to perform an oblique osteotomy in the frontal plane in a proximal-medial to distal-lateral direction and 10° angulation (Fig 2).

Fig 2.

(A) Angulation of 2.0 × 20-mm Shannon burr prior to transverse extracapsular first metatarsal Bosch osteotomy in right foot. (B) Intraoperative anteroposterior fluoroscopic view of index minus metatarsal formula and 10° osteotomy angulation (dashed line) recommended in case in right foot. (C) Clinical view of transverse first metatarsal osteotomy, performed in dorsal-plantar fashion, in right foot. The arrow shows the movement done for the osteotomy. (D) Intraoperative anteroposterior fluoroscopic view of Bosch osteotomy entry point in right foot.

The guide paddle is introduced through the skin incision for the osteotomy and then placed between the capsule and the metatarsal head. The medullar wire guide is adjusted as close as possible to the skin (Fig 3). The wire handle is inserted through the guide into the shaft of the first metatarsal and screwed into the guide to maintain reduction. When making the desired correction, you must ensure at least 50% overlap between the lateral cortex hallux head and the medial aspect of the lateral sesamoid. This is checked by Fluoroscan, allowing the desired lateral displacement of the hallux head using the external threads of the guide (Fig 4).

Fig 3.

(A) Proper assembly of the percutaneous guide prior to use, ensuring correct placement to facilitate it’s operation. The black mark shows sufficient space to place the guide beneath medial capsule. (B) Guide placement beneath medial capsule in right foot. (C) Intraoperative anteroposterior fluoroscopic view of guide placement between capsule and metatarsal head in right foot.

Fig 4.

(A-C) Intraoperative anteroposterior fluoroscopic view of sequential steps of wire handle assembly through guide into shaft of first metatarsal and screwing into guide to maintain reduction in right foot. The intramedullary guidewire is introduced through the osteotomy, maintaining it as an intramedullary pin for the metatarsal. The wire is then threaded onto the guide. (D) Slight varus maneuver of hallux against wire handle while external threads of guide are adjusted to obtain desired displacement of head in right foot. The arrow shows where the wire is screwed to the guide.

Once the desired reduction is confirmed, the arch of the screw guide is assembled until it contacts the skin so that the proximal protector is as close as possible to the first tarsometatarsal joint level. The protectors are then introduced, followed by the insertion of the K-wires (Fig 5). The distal 1.0-mm K-wire is inserted first and is conducted through the proximal-medial metatarsal cortex to the central aspect of the head fragment. This K-wire does not contact the lateral metatarsal cortex; nevertheless, it is relevant to avoid distal osteotomy fragment rotation (Fig 5). Next, the 1.4-mm proximal K-wire is introduced in a slow fashion, making sure it contacts the lateral cortex. At this point, the surgeon should spend time drilling the medial cortex with minimal force to prevent the K-wire from slipping over it, as well as intramedullary slippage. This proximal K-wire must remain parallel rather than converging with respect to the distal K-wire before it purchases the lateral metatarsal cortex (Fig 5).

Fig 5.

(A) Anteroposterior intraoperative radiograph to assess distal first K-wire insertion in right foot. (B) Lateral intraoperative radiograph to ensure head fragment is centered with respect to metatarsal diaphysis in right foot. The arrow shows the corrected placement of the 2 wires and the correct aligment of the metatarsal head. (C) Anteroposterior intraoperative radiograph to assess lateral translation and rotational correction of head fragment once both K-wires have been placed in right foot. It should be noted that the proximal second K-wire purchases both the medial and lateral cortex (yellow arrow) prior to contact with the head fragment. (D) Clinical view of arch guide and K-wire setting in right foot.

It is mandatory to obtain a strict lateral radiographic view with the Fluoroscan to ensure that the head of the first metatarsal is centered with respect to the diaphysis (Fig 5). This step helps avoid malposition of the head during screw fixation.

Once the guide is removed and the screw lengths are measured, the osteotomy is fixed with two 4.0-mm neutralization cannulated screws. The proximal-medial first metatarsal bone spike consequent to head fragment lateral displacement is removed using a 3.0 × 13-mm wedge burr (Fig 6).

Fig 6.

(A, B) Intraoperative fluoroscopic anteroposterior view of bone spike removal in right foot. The medial bony spur is removed using a 2.0 × 20-mm Shannon-type burr, and the bone fragment is extracted through the Bosch osteotomy incision. The arrow shows the bone to be removed. (C, D) Intraoperative fluoroscopic anteroposterior view of final radiologic appearance after guided percutaneous surgical technique in right foot.

Finally, the percutaneous Akin procedure is performed. It is carried out through a percutaneous incision at the proximal metaphyseal-diaphyseal junction of the phalanx. With a periosteotome, the periosteum is elevated both dorsally and plantarly to avoid tendon injuries. A 2.0 × 20-mm Shannon burr is introduced dorsally, leaving a lateral margin of the phalanx, and an oscillating motion is performed downward to carry out the osteotomy. It is recommended to complete the osteotomy with an osteoclasty of the lateral cortex, if possible. Once performed, fixation is not required, and the correction is maintained with a bandage. Preoperative and postoperative clinical images are shown in Figure 7.

Fig 7.

(A) Clinical preoperative appearance of hallux valgus deformity in right foot. (B) Clinical postoperative appearance of hallux valgus deformity in right foot treated by guided percutaneous surgical technique.

Postoperatively, the patient is allowed to bear weight as tolerated while wearing a flat postoperative shoe and using crutches for support. A compression dressing is applied and changed weekly up to 4 weeks after surgery.

Discussion

Currently, HV MIS is increasing in popularity owing to its promising clinical and radiologic outcomes.⁴ Nevertheless, the learning curve of MIS hallux procedures may be difficult in the initial cases, resulting in prolonged surgical time, radiation exposure, and higher rates of operative technique complications.⁷ Some authors have made suggestions highlighting the importance of choosing less complex cases, knowledge of surgical equipment, intraoperative tips and tricks, and above all, obtaining surgical training through Sawbones (Pacific Research Laboratories) or cadaveric practice courses.^6,7

We believe that a guided percutaneous system could shorten the learning curve of hallux MIS for surgeons who do not have high surgical case volumes and do not have the chance of participating in a formal training program in MIS procedures. The advantages and limitations of the technique are summarized in Table 1.

Table 1.

Advantages and Limitations

Advantages

The osteotomy configuration enables correction of rotational deformity and lateral displacement, as well as control of length of first metatarsal.

Accurate setting of screw position is achieved, yielding a stable configuration.

Guided systems are technically less demanding than non-guided systems.

Early postoperative rehabilitation is possible.

Limitations

A narrow first intermetatarsal space could interfere with lateral displacement; nevertheless, this is not a contraindication.

High deformity of the forefoot and midfoot (e.g., pes cavus or rheumatoid foot) may hinder the appropriate setting of the guided system.

The technique is contraindicated in patients with open physes or hallux metatarsophalangeal arthritis.

Lately, most HV MIS publications have included the MICA procedure, which is challenging in early cases because of its high learning curve.⁶ Furthermore, MICA osteotomy has limited fixation stability owing to limited bone stock, lateral wall fracture risk, and postoperative loss of correction,⁸ in addition to limitation in achieving precise control over lateral displacement of the hallux head.⁵

The transverse extra-articular osteotomy in the META procedure can achieve higher rotational stability and lateral displacement owing to its biomechanical osteotomy configuration, in which 2 screws can be safely placed across the lateral metatarsal cortex, whereas in the chevron configuration, 1 screw can not be place proximal enough in the lateral cortex, risking wall fracture and consequent screw malpositioning.⁸Moreover, this procedure corrects the rotational (pronation) HV deformity, which is a demonstrated recurrence factor.¹⁰

The addition of the guided percutaneous system described in this article provides a reliable and controlled 3-dimensional correction of HV deformity, through correct placement of a paddle and external thread, and biomechanically stable fixation, provided by 2 parallel non-compressive cannulated screws. As with other HV MIS procedures, there are some tips to be aware of and pitfalls to avoid before performing the technique, which are described in Table 2.

Table 2.

Pearls, Pitfalls, and Risks

Pearls

The operative foot should be positioned with the heel hanging freely at the end of the table. This is helpful to obtain correct intraoperative radiographs.

The surgeon should consider the metatarsal formula before performing the first metatarsal osteotomy. The cutting burr takes 2-3 mm of bone, so the surgeon must be aware of the correct burr orientation to achieve the correct first-ray length.

Once the osteotomy is performed and the guided system is properly set, the head fragment is held in varus against the wire handle, controlling pronation and dorsal-plantar displacement; then, the external thread of the guide is screwed.

After correct setting of both K-wires controlled by strict frontal and lateral fluoroscopic views, the surgeon should withdraw 4 to 6 mm to each K-wire measure to prevent intra-articular screw placement and proximal-medial screw prominence as if you do not substract 4 to 6 mm the screws can be too long.

The surgeon should make sure to insert the distal neutralization screw first. This reduces the risk of malrotation deformity of the hallux head.

Slight compression through a dorsiflexion maneuver of the head fragment is advisable at the moment of screw fixation to avoid loss of reduction.

Pitfalls and risks

Use of a tourniquet is not mandatory. If a tourniquet is used, saline solution irrigation is recommended when working with a cutting burr to avoid soft-tissue injuries or bone necrosis.

The surgeon should avoid excessive stripping of the plantar capsule once the first metatarsal osteotomy is completed. This can help to prevent blood flood disruption of the hallux head.

During insertion of both screws, the surgeon should be aware of the head screw’s position, which should be flush relative to the medial metatarsal cortex to avoid postoperative symptomatic osteosynthesis.

After both screws are inserted, the medial bone prominence should be removed through the previous Bosch osteotomy percutaneous approach. This is recommended to avoid painful medial impingement related to bone spikes.

Disclosures

All authors (D.C-R., E.Q-P., I.F-G., J-A.C-G., Y.M-S., O.P-S., G.A-F.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Data

Video 1

Fourth-generation minimally invasive hallux valgus surgery with guided percutaneous system. The patient is positioned supine with the heel hanging freely over the surgical table. A tourniquet is not mandatory for this procedure. The surgeon positions himself or herself at the medial aspect of the affected foot. Once the foot is prepared and draped at the ankle level, it is set over the Fluoroscan surface. Anatomic structures including the bunion and the midshaft axis of the first metatarsal are marked with a sterile pen. The green dotted line displays the percutaneous incision point just proximal to the intersection between the bunion and the first metatarsal shaft. The capsule is released with a periosteal elevator using a 2.0 × 20-mm Shannon burr. A transverse extracapsular first metatarsal Bosch osteotomy is completed. Concerning the osteotomy, it is important to consider the metatarsal formula; in cases of index minus, to avoid excessive shortening, it is advisable to perform an oblique osteotomy in the frontal plane in a proximal-medial to distal-lateral direction and 10° angulation. Through dorsal-plantar movements, the osteotomy is then completed. Once again, the capsule is released by a periosteal elevator prior to insertion of the guided system. The guide paddle is adjusted an fixed screwing on clockwise rotation. Next, it is introduced between the capsule and metatarsal head, adjusted as close as possible to the skin. The guide paddle should be parallel to the second metatarsal shaft prior to proceeding to correction. The wire handle is inserted through the guide into the shaft of the first metatarsal and screwed into the guide to maintain lateral displacement of the head. By use of the Fluoroscan system, when making the desired correction, you must ensure at least 50% overlap between the lateral cortex hallux head and the medial aspect of the lateral sesamoid. The head fragment is held in varus against the wire handle, controlling pronation and dorsal-plantar displacement. Then, the external thread of the guide is screwed until appropriate clinical and fluoroscopic correction is achieved. The head fragment is held reduced in the previous position. Once the desired reduction is confirmed, the arch of the guide is assembled until it contacts the skin so that the proximal protector’s hole is as close as possible to the first tarsometatarsal joint level. Preceded by a percutaneous stab incision, the K-wire protectors are introduced. The distal K-wire is inserted first and is conducted through the proximal-medial metatarsal cortex to the central aspect of the head fragment. This first K-wire does not contact the lateral metatarsal cortex; nevertheless, it is relevant to avoid distal osteotomy fragment rotation. Next, the proximal K-wire is introduced in a slow fashion, making sure it contacts the lateral cortex. At this point, we should spend time fatiguing the medial cortex to prevent the K-wire from slipping over the bone in intramedullary slippage when drilling the lateral cortex. This proximal K-wire must remain parallel rather than converging with respect to the distal K-wire before it purchases the lateral metatarsal cortex. Once both K-wires are inserted, the guided system is removed. Then, it is mandatory to obtain strict anteroposterior and lateral radiographic views to ensure that the head of the first metatarsal is centered with respect to the diaphysis. Both guide K-wires are measured; it is advisable to withdraw 4 to 6 mm to each K-wire measure to prevent intra-articular screw placement and proximal-medial screw prominence as if you do not substract 4 to 6 mm the screws can be too long. Next, by use of a 3.2-mm drill bit, both K-wires are over-drilled. The first distal 4.0-mm neutralization cannulated screw is inserted. Slight compression through a dorsiflexion maneuver of the head fragment is advisable at the moment of screw fixation to avoid loss of reduction. Next, the same procedure is repeated for proximal screw insertion, ensuring both medial and lateral cortex purchase in this case. Finally, the proximal-medial first metatarsal bone spike is removed using a 3.0 × 13-mm wedge burr. A minimally invasive Akin procedure (not shown) is usually performed. The Akin procedure is performed through a percutaneous incision in the metaphyseal-diaphyseal region of the phalanx. By use of a periosteotome, the soft tissue is elevated dorsally and plantarly to prevent tendon injury. The burr is introduced dorsally, maintaining a lateral margin of the phalanx, and an oscillating downward motion is used to perform the osteotomy. It is recommended to complete the osteotomy with lateral cortical osteoclasis, if feasible. Once the osteotomy is performed, fixation is not required, and the correction is maintained using a dressing.