Hallux valgus, commonly known as a bunion, is a prevalent foot deformity where the big toe shifts abnormally towards the second toe. This misalignment creates a bony prominence on the side of the foot at the base of the big toe. Surgical intervention aims to correct this structural deviation and alleviate associated pain. The specific anatomical structures removed or altered during hallux valgus surgery depend on the individual’s condition and the chosen surgical technique.
The Bony Prominence
The visible bony bump, medically termed an exostosis, forms on the side of the first metatarsal head. During an exostectomy, surgeons shave off this overgrowth using a surgical saw. While removing the bump addresses cosmetic concerns and reduces pressure from footwear, it does not correct the underlying angular misalignment of the toe. Exostectomy alone is rarely sufficient for comprehensive bunion correction and is often combined with other procedures.
Bone Realignment
Many hallux valgus surgeries involve cutting and repositioning bones to correct the deformity. This procedure is called an osteotomy. Surgeons make precise cuts into specific parts of the first metatarsal bone and sometimes the proximal phalanx. For instance, a V-shaped cut is made in a Chevron osteotomy, while a Z-shape is used in a Scarf osteotomy, allowing the bone segments to be shifted into a straightened position. In some cases, a small wedge of bone is removed to achieve the necessary angular correction.
After the bone segments are cut and realigned, they are stabilized in their new position using various types of hardware. These include small screws, pins, or plates, which hold the bones in place while they heal. The choice of osteotomy technique depends on the severity and specific characteristics of the bunion deformity. This bone reshaping addresses the skeletal misalignment.
Soft Tissue Modifications
Soft tissues surrounding the big toe joint are also modified during bunion surgery. These tissues include ligaments, tendons, and the joint capsule. In a longstanding bunion, soft tissues on the outer side of the big toe become tight, pulling the toe further out of alignment. Surgeons often perform a release of these contracted lateral soft tissues, such as the adductor hallucis tendon and the lateral joint capsule.
Conversely, the joint capsule on the inner side of the big toe may become stretched and loose. To maintain the toe’s corrected position, this medial capsule might be tightened through a procedure called plication. These soft tissue adjustments rebalance the forces around the joint. They work with bone procedures to ensure the big toe remains in its newly aligned position, preventing recurrence.
Joint Surface Preparation for Fusion
For severe cases of hallux valgus, or when significant arthritis affects the big toe joint, arthrodesis (joint fusion) may be performed. In this surgery, the damaged or arthritic joint surfaces of the big toe are removed. This involves excising the cartilage and a thin layer of the underlying bone from both sides of the joint. The goal is to create raw bone-to-bone contact.
The prepared bone ends are then compressed and held stable with screws, plates, or pins, allowing them to grow into a single, fused bone. This eliminates all motion at the joint, resolving pain caused by arthritis or severe instability. While it permanently stiffens the big toe joint, it offers a durable solution for patients with advanced disease.