Arthrodesis of the Hallux Metatarsophalangeal Joint
Chirag S. Patel, MD
Loretta B. Chou, MD
Dr. Patel or an immediate family member serves as a paid consultant to or is an employee of Arthrex, Inc. Dr. Chou or an immediate family member serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot & Ankle Society.
PATIENT SELECTION
Indications
First metatarsophalangeal (MTP) joint arthrodesis is commonly indicated for patients with hallux rigidus, hallux valgus with arthritis, failed surgeries of the hallux, neuromuscular conditions, inflammatory disease, and primary or secondary arthritis.1 Hallux rigidus can be categorized into mild (grade 1), moderate (grade 2), and severe (grades 3 and 4) degenerative joint disease. First MTP joint arthrodesis is usually reserved for severe degenerative arthritis. First MTP joint arthrodesis is typically performed after nonsurgical treatment has failed. Initial treatment of early disease includes nonsteroidal anti-inflammatory medication, orthoses and shoe modification, taping, and occasional intra-articular steroid injection.2 Other indications may include joint subluxation, dislocation, or instability.
Contraindications
Contraindications include active infection, certain malignant conditions, and nonarthritic conditions. Nonarthritic conditions include tenosynovitis of the flexor hallucis longus, osteochondral defect lesion, and pain referred to the hallux from other pathology.
Alternative Treatments
Resection arthroplasty with cheilectomy, interposition graft arthroplasty, hemiarthroplasty, and total joint arthroplasty have been described as substitutes for arthrodesis of the first MTP joint. Recently, Baumhauer et al have supported the use of synthetic cartilage implant as an alternative to MTP joint arthrodesis.3 However, a cartilage implant may not allow for a significant deformity correction. Thus, arthrodesis remains the benchmark of treatment. Gibson and Thomson4 reported on a randomized controlled trial comparing arthrodesis and total joint arthroplasty. At 2-year follow-up, the group with arthrodesis had better pain ratings compared with the arthroplasty group. Stiffness continued to be a problem in the arthroplasty group, and there was a high rate (15.4%) of component loosening of the proximal phalanx.4 Brewster5 had similar results and concluded that arthrodesis had better results compared with total joint arthroplasty. Raikin and Ahmad6 compared arthrodesis and metallic hemiarthroplasty and reported a 24% failure rate and a 4.8% revision rate with hemiarthroplasty. The hemiarthroplasty group had 57% good to excellent results compared with 81% for the arthrodesis group. The American Orthopaedic Foot and Ankle Society (AOFAS) rating was significantly better in the arthrodesis group. Brodsky et al7 showed with a prospective gait analysis that patients have increased maximal ankle push-off power, increased single-limb support time, and decreased step width after first MTP joint arthrodesis. Thus, gait mechanics are not significantly altered and are likely improved from the preoperative diseased state.
PREOPERATIVE IMAGING
Preoperative imaging consists of three weight-bearing views of the foot (AP, lateral, and oblique). In some cases, it is better to correct proximal pathology before distal pathology. Thus, when viewing imaging studies, it is important to not focus directly on the hallux but review the entire series of radiographs. However, a moderate amount of correction of the intermetatarsal angle (13° preoperative to 9.6° postoperative) can be achieved without a separate proximal osteotomy during first MTP joint arthrodesis.8 Typical signs of osteoarthritis may be observed on radiographs: joint space narrowing, osteophytosis, sclerosis, and subchondral cysts. With severe deformity, joint subluxation or dislocation may be present (Figure 1). Radiographs are sufficient for preoperative planning. Noting the preoperative intermetatarsal angle, the hallux valgus angle, and the angle of inclination of the first metatarsal relative to the floor can be useful for planning and intraoperative correction (Figure 1, B). CT, MRI, or other imaging is typically not necessary for preoperative planning.
PROCEDURE
Special Equipment and Implants
A radiolucent table may be convenient in obtaining intraoperative imaging. A sterile Esmarch tourniquet may be used around the ankle. Mini-fluoroscopy (mini C-arm) or
an image intensifier is helpful in assessing intraoperative deformity correction. A microsagittal saw and/or Hoke osteotomes are useful in preparing the MTP joint surfaces. Depending on bone size, a small fragment or a modular hand set can be used for lag fixation. Low-profile plates are typically used as fixation for MTP joint arthrodesis. Depending on the technique, other special sets may be necessary.
an image intensifier is helpful in assessing intraoperative deformity correction. A microsagittal saw and/or Hoke osteotomes are useful in preparing the MTP joint surfaces. Depending on bone size, a small fragment or a modular hand set can be used for lag fixation. Low-profile plates are typically used as fixation for MTP joint arthrodesis. Depending on the technique, other special sets may be necessary.
 FIGURE 1 Preoperative weight-bearing AP (A) and lateral (B) radiographs of a right foot. The MTP angle is approximately 30°; the intermetatarsal angle is approximately 13°; and the inclination angle of the first metatarsal is approximately 30°. There are signs of first MTP joint arthritis as well: joint space narrowing, sclerosis, osteophytosis, and mild sclerosis. The MTP joint is also subluxated, and the metatarsal head is flattened. |
Surgical Technique
In our preferred technique, the patient is positioned supine on the operating table. A local, regional, or spinal anesthetic in conjunction with sedation is sufficient for the procedure. General anesthesia can also be used if necessary. A thigh tourniquet can be used in patients with spinal or general anesthesia. However, an Esmarch ankle tourniquet is sufficient.
After the tourniquet is applied, a dorsal longitudinal incision is made over the MTP joint; alternatively, a medial midline approach may be used (Figure 2, A). Dissection is performed with Littler or tenotomy scissors to the capsule. The extensor hallucis longus (EHL) tendon can be mobilized and retracted laterally to aid in exposure (Figure 2, B). Care is taken not to damage any cutaneous nerve branches (medial dorsal cutaneous branch of the superficial peroneal nerve).
The capsule is incised sharply in line with the incision, and the MTP joint is exposed. The periosteum and capsule are incised in one layer and elevated sharply off the bone. Subperiosteal elevation is performed to expose the diaphysis of both bones (Figure 2, C). The joint is then prepared using a microsagittal saw or Hoke osteotomes (Figure 2, D). Small Homan or Bennett retractors may be used to protect the adjacent structures. The cartilage is removed to the subchondral bone. Bony surfaces are prepared to obtain optimal positioning. The joint is aligned such that the MTP angle is no more than 15° valgus, the hallux is in neutral rotation, and the joint is approximately 20° dorsiflexed relative to the metatarsal (Figures 2, E, F and 3). Pressure under the first metatarsal head increases with increased dorsiflexion. With decreasing dorsiflexion angle, the pressure under the first metatarsal head decreases but increases under the lesser toes, resulting in secondary metatarsalgia and callosities. The optimal dorsiflexion angle should be 20° to 25° relative to the first metatarsal.9 Soft-tissue releases may be necessary to obtain acceptable correction.
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