Hoffman, Clayton Metatarsal Head Resection for Rheumatoid Forefoot

6 Hoffman, Clayton Metatarsal Head Resection for Rheumatoid Forefoot

Graham McCollum

Abstract

Untreated or resistant rheumatoid arthritis can lead to significant forefoot deformities and morbidity. Typically, the hallux deforms into valgus and the lesser metatarsophalangeal joints dislocate dorsally with varying degrees of joint destruction and bone erosion. Surgical reconstruction entails creating a stable hallux with arthrodesis of the metatarsophalangeal joint and resection of the lesser metatarsal heads if the joints are not reducible or destroyed by the disease process. The hallux is generally fixed with a combination locking compression plate and the lesser toes held reduced with K-wire fixation. The results are generally good with high patient satisfaction long term if there are no complications. The most common complications are wound-healing problems, inadequate resection of the metatarsals, overgrowth of the resected bone, and hallux nonunion/malunion.

Keywords: rheumatoid forefoot, hallux arthrodesis, Hoffman’s procedure, Clayton’s procedure, forefoot reconstruction

6.1 Introduction

Rheumatoid arthritis (RA) is a systemic inflammatory disease that affects the forefoot, requiring surgical intervention in about 15% of cases. Between 85 and 92% of patients with RA will have some form of foot involvement, and it presents in the foot for the first time in around 20% of cases.¹

With the introduction of disease-modifying drugs and biologics, the incidence of gross forefoot deformity and joint destruction has decreased. Deterioration after surgery in stable, well-controlled disease may also not be as prevalent.²

The timing of surgery is important to consider. Other joints are frequently affected and might need surgical intervention themselves. This might limit postoperative ambulation and affect the recovery of the foot surgery. The cervical spine, particularly the subaxial spine, can be unstable in uncontrolled disease, and stability should be confirmed prior to elective surgery.

The most common procedure performed for the management of these cases when advanced is the Hoffman or Clayton procedure.³^,⁴ This involves creating a stable hallux metatarsophalangeal joint (MTPJ) with an arthrodesis, resection of the lesser metatarsal heads, and correction of the lesser toes with osteoclasis of the proximal interphalangeal joints (PIPJs) or condylectomy of the proximal phalangeal heads. For patients who have endured longstanding suffering from walking on exposed metatarsal heads, often with gross deformity, the operation is life-changing, and it is rewarding for the surgeon too. With symptomatic lesser deformities and better management with disease-modifying drugs, joint-preserving procedures can be considered, such as shortening, elevating osteotomies of the lesser metatarsals, and correction of hallux valgus with conventional soft-tissue and bony work. This chapter focuses on the technique of hallux MTPJ arthrodesis and resection arthroplasty of the lesser metatarsal heads, the Clayton or Hoffman procedure.

6.1.1 Indications

• Advanced symptomatic disease with deformities not managed by conservative intervention.

• Subluxing or dislocated lesser MTPJs with joint destruction and erosion, plantar callus formation, and fat pad advancement. If the lesser MTPJs are passively reducible and the joints preserved on radiographs, shortening, elevating osteotomies can be considered.

• Hallux valgus or varus with joint destruction, instability, and subluxation. If the disease is well controlled and the joints preserved on radiographs with mild deformities, consider a joint-preserving procedure. If the interphalangeal joint is arthritic and symptomatic, consider a resection arthroplasty rather than an arthrodesis.

• Skin erosion or threatening of the skin from the bony prominences.

6.1.2 Clinical Evaluation

• Poorly treated or uncontrolled RA leads to deregulation of the cellular and humoral immune systems, resulting in synovial proliferation, pannus formation, capsuloligamentous destruction, and cartilage erosion.

• Initially, this presents as painful swelling of the MTPJs. If poorly treated or resistant, it proceeds to subluxation and dislocation of the joints with symptomatic plantar callus formation, metatarsalgia, fat pad migration, and dorsal callus formation over the lesser toes, which develop fixed flexion deformities.

• Typically, the hallux, together with erosive cartilage destruction, develops a valgus deformity of the MTPJ and sometimes subluxation. Hallux varus is a less common deformity (Fig. 6.1).¹

• Patients typically experience pain under the exposed metatarsal heads, over the medial eminence of the hallux valgus and the dorsum of the lesser toes. Their skin is often thin from the systemic disease and prone to ulceration and skin breaches.

6.1.3 Radiographic Evaluation

• Global evaluation of the foot and the ankle is necessary for adequate surgical planning. Standing X-rays, three views, and anteroposterior (AP), lateral, and an oblique view are mandatory. Standing ankle views are also necessary if there is hindfoot malalignment, an acquired flatfoot, or rheumatoid ankle.

• Typically, the hallux is in valgus alignment, but sometimes it is in varus with varying degrees of bone erosion and loss. The proximal phalanx of the hallux can be very short if there is longstanding disease with erosion, which can make fixation for fusion difficult.

Fig. 6.1 Typical forefoot deformities. Photograph showing hallux valgus and dislocated lesser metatarsophalangeal joints.

• It is important to evaluate the interphalangeal joint (IPJ) of the hallux—this might sway you from fusion of the metacarpophalangeal (MP) joint. The lesser toes often have dislocated or subluxed MP joints and fixed flexion deformities of the PIP joints.

• Osteoporosis is common in these patients; they often are on longstanding corticosteroid treatment and have low activity levels; this might affect implant choice and fixation, and hence should be evaluated. If there is a concern with previous ulceration and osteomyelitis, a magnetic resonance imaging (MRI) scan is useful for detecting collections and bone involvement—otherwise, the role of further imaging is limited (Fig. 6.2).

6.1.4 Nonoperative Options

• The conservative treatments include.

Shoes with a high and wide toe box.

Metatarsal pads.

Rocker bottom soled shoes.

Metatarsal bars.

Accommodating medium density orthotics.

• The goal is to offload the prominences and allows the callus formation to recede. These patients often suffer tremendous pain from their multijoint disease and cope with extreme deformity for a long time.

6.1.5 Contraindications

• Proven deep infection.

• Extreme skin fragility or soft-tissue infection.

• Vascular insufficiency.

• Other medical reasons and patient fragility, cervical spine instability and myelopathy, poor mobilization potential, etc.

6.2 Goals of Surgical Procedure

A successful procedure culminates in a stable united hallux in a good position, with resolution of the plantar calluses and correction of the deformities both in the hallux and the lesser toes. These patients have tremendous pain from the disease and can be extremely grateful with improvement in their pain and function.

Fig. 6.2 Standing foot X-ray. Radiograph showing typical rheumatoid deformities, hallux valgus, and dislocated lesser metatarsophalangeal joints.

6.3 Advantages of Surgical Procedure

The fusion of the first MTPJ creates a stable medial column against which the lesser toes remain balanced. Prior techniques of resection arthroplasty (Keller’s procedure) of the first MTPJ had no medial stability and recurrent valgus deformity of all the toes frequently occurred.

The resection of the lesser metatarsal heads alleviates the necessity of osteotomies of the metatarsals to heal in these patients with poor quality bone. Additionally, loss of plantar padding is no longer an issue given there is no metatarsal head to be prominent in this area after resection. Although the lesser MTPJs are unstable, this rarely causes any difficulty in low-demand rheumatoid patients.

6.4 Key Principles

• Perform an arthrodesis of the hallux in a good position for the patient’s function.

• Remove the metatarsal heads at the appropriate level to form a cascade of decreasing lengths from medial to lateral.

• Hold the PIPJs and the distal interphalangeal joints in a reduced position after either an osteoclasis or proximal phalanx condylectomy and reduce the base of proximal phalanx onto the resected metatarsal with the extensor tendons acting as an interposition graft.

6.5 Preoperative Preparation and Patient Positioning

A thorough history and physical examination must be performed, looking for features of myelopathy including cervical spine instability, skin integrity, and ability to ambulate. Ankle, hindfoot, and midfoot involvement, including tendon function and involvement, must be examined and documented. In the forefoot, the hallux IPJ must be assessed for range of motion and pain and the lesser MTPJ dislocations/subluxations checked to see if they are reducible or not. Most patients have thin skin from the systemic disease and from prolonged steroid use, but extreme cases may be a contraindication to the surgery. Vascular competence, both venous and arterial, must be documented and areas of callus and threatened skin identified.

Consultation with their rheumatologist prior to the operation is mandatory. Most are on drugs to modulate their immune systems and theoretically could lead to an increased infection rate. This has not been proven in large retrospective studies.⁵ The biologic drugs, tumor necrosis factor, should perhaps be discontinued for a month around the surgery but there is little high-level evidence to guide us.⁶

“Pre-hab” is essential to protect the surgery postoperatively. These patients often have upper limb involvement and are generally weak. Assisting devices and offloading shoes are required for safe ambulation postoperatively. We find that if the patient is introduced to the physical therapist and the rehab team before the surgery, the transition to independence is smoother and faster.

In cases of bilateral disease, staging the surgery is the safest option with the most symptomatic side operated on first (not necessarily the worst radiologically). The contralateral side should be treated surgically once the fusion of the hallux is proven and they can ambulate unassisted on the operated foot and have had time to appreciate the benefit of the surgery. Generally, this time frame is around 6 months but can be shorter if they recover fast. In certain circumstances, either for socioeconomic reasons or if there is equal bilateral threatened skin, they can be done at the same time, but this renders them extremely dependent and increases the complication rate.

Standing radiographs of both feet, AP, lateral, and an oblique view are necessary. The deformity of the hallux MTPJ, IPJ, and the lesser toes can be assessed, as well as the bone density, joint destruction, and bone stock. We like to take preoperative standing photographs of all patients given the deformity correction can be very dramatic and the patients seem to appreciate the operation even more when they see where they have come from.

The patients must be informed of the potential risks and complications. The most common of these are wound-healing problems, infection, nonunion of the hallux, IPJ degeneration, recurrent deformity of the lesser toes, and bony overgrowth of the metatarsal resection. Less commonly, in severe deformity, ischemia and digit loss of the hallux or the lesser toes is a possibility.

The patient is positioned supine with a sandbag or a bump under the ipsilateral buttock to position the foot facing the roof. We prefer to use a formal tourniquet and exsanguinate the limb with an Esmarch bandage prior to incision. The procedure can be time consuming, and duration of inflation must be monitored.

Meticulous handling of the skin and soft tissue, avoiding excessive retraction, exposing properly as opposed to forced retraction, will reduce the soft-tissue complications.

6.6 Operative Technique

6.6.1 Exposure

A three-incision technique should be used: one for the hallux MP fusion, one for the second and third metatarsal heads, and one for the fourth and fifth metatarsal heads. If the lesser toe flexion deformities are severe, then dorsal elliptical transverse incisions allow adequate exposure of the PIPJs. After reducing the joints, this skin incision removes the excessive skin on the dorsum of the toes and heals well.

The most common deformity of the hallux is valgus. By using a medial incision to approach the MTPJ, the skin bridge can be kept as wide as possible and in our experience the skin heals better. If there is a wound dehiscence, then the plate is covered with a decent flap and metal is not generally exposed. The medial skin is also less fragile. To correct gross hallux deformity, the joint must be circumferentially released and, in particular, the adductor tendon, medial capsule, and suspensory ligament of the sesamoids for adequate exposure of the joint for preparation.

The lesser metatarsals are approached through two dorsal incisions in the second and the fourth web spaces. We have found that if the incisions are gently curved, there is a better flap and there is less tension on the skin during the resection. It is helpful then to mark the incisions with crossed lines for the appropriate suturing of the skin. Other incisions include transverse plantar and dorsal plantar incisions, but we prefer the less invasive three-incision technique and have not had trouble with the wound if careful with the soft tissue.

6.6.2 Hallux Arthrodesis

Once the joint is exposed, there are several ways to prepare the surfaces for a successful arthrodesis. These include the cup and cone reamer technique, described first by McKeever,⁷ burring the remaining cartilage and subchondral bone and making square cuts. If there is a prominent medial eminence, a sliver bunionectomy can be performed with an osteotome or oscillating saw, given that it is easier to appreciate the center of the metatarsal head after this is done. The cup and cone reaming technique allows the angle of the fusion to be adjusted and manipulated. It does not compromise stability and contact. This is the preferred method but can be dangerous in soft osteoporotic bone because the reamers can plunge into the metaphysis after penetrating the subchondral bone or can fracture the phalanx or metatarsal. Make sure the reamers are sharp and you do not have to apply too much pressure to ream. Great care must be taken not to plunge and destroy the bone necessary for fusion. If there is doubt, rather use a rongeur or burr to prepare the surfaces.

• Exposure for reaming is best done with the phalanx in plantarflexion, so the reamer clears the opposite bone. Place the appropriate guidewire in the center of the metatarsal head and make sure it follows the canal of the metatarsal. Trial the reamer sizes at this point as if the joint will be “resurfaced” and not excessive bone removed on the plantar or the dorsal sides. Sometimes, the wire has to be repositioned at this point if too plantar or dorsal.

• It is important to predetermine the amount of bone resection necessary. In extreme cases of hallux valgus, the metatarsal needs to be well shortened to limit the chance of ischemia. Once the metatarsal has been prepared, remove the loose bone and debris and use a rongeur to help fashion a smooth cone.

• The same guidewire (if not bent) can then be removed and placed into the middle of the proximal phalanx. Take care to seat the wire deep as it tends to back out, causing the reamer to slip off the bone and create an eccentric defect. Gently ream the phalanx. The subchondral bone can be quite resistant, and when more pressure is applied, it can literally explode. Ream just through the subchondral bone to good bleeding soft bone.

• If, after the reaming or resection during a trial reduction, the joint is still very tight and you cannot hold it in position easily, rather resect or ream more bone carefully until the reduced joint is decompressed. The reamed surfaces of the two bones should be gently drilled with a 2-mm drill bit to encourage bone bleeding. If the metatarsal is extremely soft, then abandon this because it may compromise fixation.

• The hallux should be set with the MTPJ in 8 to 15 degrees of valgus and with the distal phalanx just clearing the ground, at a 10-degree dorsiflexed angle relative to the floor. Perform the “plate” test by placing a plate under the entire foot and loading it: the hallux should be sitting just off the plate by about 5 mm so that the distal hallux touches the plate in midflexion of the IPJ. This allows clearance during toe-off, but the distal phalanx can still engage the ground.

• The position can be altered and then held in the best position with K-wires. Intraoperative fluoroscopy is useful at this point to assess the coronal alignment but is difficult to assess the sagittal alignment because of the overlapping toes.

• A 2.5to 3-mm cannulated transarticular screw is passed from plantar medial to dorsolateral at this point. It allows for immediate compression and stability. The position of the hallux should be rechecked, especially rotation, given that this can be overlooked. Sometimes, there is a ridge on the proximal phalanx that causes the plate to seesaw. It is a good time to use a rongeur or burr to make a flat surface on the dorsum of the hallux. The plate should be “fitted” to the bone, not the bone fitted to the plate. In other words, the position of the hallux should take priority intraoperatively. The low-profile plate should sit perfectly on the bone and not seesaw or be lifted up on one side, as, when the screws are placed, the bone will be pulled to the plate and the position possibly lost. In most cases, the plate has to be bent slightly to fit well.

• Given that these patients frequently have soft osteoporotic bone, a hybrid technique using a combination of nonlocking screws, to help hold the plate to the bone and achieve some compression, and locking screws, to resist pullout and achieve fixation, should be used. The sequence should be to place the two (preferably three) locking screws into the phalanx and then place a compression screw into the compression slot on the metatarsal. The rest of the holes should be filled with locking screws. In most cases, this provides good fixation, allowing the rest of the forefoot reconstruction to continue without compromising the position and fixation of the hallux.

6.6.3 Lesser Metatarsal Resection

This is the more destructive part of the operation but important to get right. In longstanding gross deformity, this can be difficult as the proximal phalanx dislocates dorsal of the metatarsal head and, with the extrinsic tendons, shortens significantly. The metatarsal head becomes adherent to what is left of the plantar plate and the diseased ligament structures. The skin over the dorsum is very fragile, and excessive retraction must be avoided. Rather, use longer incisions or try the slightly curved incision as the flap generated puts less tension on the skin.

• Make two incisions on the foot, as far apart as you can, one over the second web space and one over the fourth web space. Begin with the second metatarsal and move laterally. It can become confusing to find where you are when the toes are dislocated, but the long extensor tendon is usually tight and will be your guide to the proximal phalanx where you will find the metatarsal. Use harp to dissect down to the metatarsal neck and shaft and expose the joint and release as much of the capsule and the adherent joint as you can. At this point, cut the extensor tendons as proximal as you can so they can be used for an interposition graft.

• If possible, deliver the metatarsal head into the wound by reducing the released joint and plantar flexing the digit. This is not always possible, and if the skin is under extreme tension, then abandon and perform an in situ bone section. Check again where the level of the MTPJ fusion is. The level of resection of the metatarsal should be at or slightly longer than the first metatarsal.

• The resection should be done with an oscillating saw with the appropriate saw blade and angled retrograde to create a flattish surface for weight-bearing. Place two retractors around the metatarsal neck to protect the surrounding tissue and saw through. Once complete, remove the head and the neck. This can be difficult to do in one piece because the metatarsal head is very adherent to the plantar plate and the capsule. It has to be teased out and perform a “crocodile” role to get it out. If it breaks up, remove it piecemeal and put your finger in the defect, feeling for retained parts of head and remove them with a rongeur.

• Through the same incision, identify the extensors for the second toe and follow them to the joint. Once the metatarsal head and neck is visible, check the length of the second metatarsal and section the third about 3 to 5 mm shorter to achieve a cascade of lengths of the lesser metatarsals. If, after head resection, there is still a very tight space between the metatarsal and the phalanx, then remove some more metatarsal until there is a comfortable gap.

• Perform the same resection of the fourth metatarsal through the fourth web space incision noting the length of the third metatarsal. When it comes to the fifth metatarsal, we prefer to make an oblique cut in the metatarsal with the head resection so that there is a smooth lateral border to the forefoot. The same applies to judging length of resection (Fig. 6.3).

• An alternative approach is the plantar “fish-mouth” incision. This is a good alternative if there is gross advancement of the plantar fat pad, if there are severe plantar nodules and intractable callus that must be excised, and if the MTPJs are grossly dislocated and digits dorsally subluxed.

• Make two incisions on the sole of the foot, creating an ellipse over the plantar forefoot proximal and distal to the MTPJs including any plantar callosities. Remove the skin flap and dissect sharply down to the MTPJs. Take care to avoid plunging into the intermetatarsal spaces, given the neurovascular bundles are prone to injury.

• Open the MTPJ capsules longitudinally and expose the metatarsal heads. Resect them obliquely with a saw—creating a cascade from the second to the fifth metatarsal. Closure of the flap will help bring the lesser toes down and reduce the clawing, but an extensor tenotomy will often be necessary to facilitate this. Interposition of the extensor tendons is not possible with this approach.

• Carefully close the plantar skin, making sure there are no overlaps and the skin edges marry up well. Wound complications with this approach are common. Close with nylon sutures, as they will have to remain in for at least 3 weeks to avoid the wound splitting open before healing (Fig. 6.4).

6.6.4 Lesser Toe Fixation

• The next part of the operation depends on the severity of the fixed flexion deformity of the lesser toe PIPJs. If they are fixed at 70 to 90 degrees, we prefer to do a P1 condyle removal through a transverse elliptical incision removing a piece of skin.

• The base of the middle phalanx is also prepared with a saw or the cartilage is removed with a rongeur. In these very fixed joints, forced osteoclasis sometimes causes the plantar skin to split open and there is an increased risk of vascular compromise. By removing the condyles, the PIPJs are open and K-wire fixation, first prograde and then retrograde, is easier than after the closed osteoclasis where the prograde wire can miss one of the phalanges. However, if the PIPJs are easily reducible with little force and the deformity is not severe, we perform a reduction of the joint closed and pass a 1.2to 1.4mm wire through the base of the proximal phalanx prograde to exit the toe just below the nail, trying to kebab the three phalanges. By holding the toe with two fingers and advancing the wire, you can almost feel it through the bones.