Hallux valgus is a common foot deformity where the big toe drifts towards the second toe, causing a bony protrusion on the side of the foot, often called a bunion. This misalignment can lead to pain, inflammation, and difficulty wearing shoes. Surgical intervention aims to correct the structural issues, alleviate discomfort, and restore proper foot mechanics. The procedures focus on realigning bones and balancing soft tissues to improve overall foot function.
Understanding Hallux Valgus
Hallux valgus involves a lateral deviation of the big toe (hallux) and a medial deviation of the first metatarsal bone, the long bone connecting to the big toe. This causes its head to bulge outward, forming the characteristic bunion. The normal angle between the first metatarsal and the proximal phalanx (the first bone of the big toe) is typically less than 15 degrees; in hallux valgus, this angle can increase significantly, often exceeding 20 degrees in moderate cases and over 40 degrees in severe deformities.
This structural collapse occurs at the first metatarsophalangeal (MTP) joint, the joint at the base of the big toe. Over time, the joint capsule and ligaments on the inside of the foot can stretch, while those on the outside become contracted, further pulling the toe out of alignment. The displaced big toe can also crowd the adjacent second toe, potentially leading to additional deformities like hammer toes or claw toes.
Key Anatomical Changes Addressed in Surgery
Surgery targets deformed or dysfunctional anatomical components. The most noticeable alteration is the reshaping or shaving down of the prominent bony bump, known as an exostosis, on the medial side of the first metatarsal head. This procedure, called an exostectomy, removes the excess bone that causes friction and pain against footwear.
Beyond the visible bump, the underlying bony misalignments of the first metatarsal and the big toe’s phalanx bones are addressed. The abnormal angle between these bones is corrected by repositioning them to restore proper alignment. Soft tissues around the joint also play a significant role in the deformity. The tightened soft tissues, particularly the joint capsule and ligaments on the lateral (outer) side of the big toe joint, are often released to allow for proper realignment.
Conversely, the soft tissues on the medial (inner) side of the joint, which become stretched and weakened, may require tightening to stabilize the corrected position. Small bones located beneath the great toe joint, called sesamoids, can also become displaced due to the shifting metatarsal bone. In rare instances, a sesamoid bone may need to be partially or completely removed.
Common Surgical Techniques and Their Impact
Exostectomy, the shaving of the prominent bony bump, is often the first step in hallux valgus surgery. This reduces the painful bump and improves the foot’s contour. The primary goal of surgery extends beyond this cosmetic change, focusing on realigning the bones.
Osteotomies, which are surgical cuts made in the bone, are frequently performed to achieve this realignment. For instance, a Chevron osteotomy involves a V-shaped cut near the head of the first metatarsal, allowing the bone segment to be shifted laterally and secured with small screws or pins. This repositions the metatarsal head, correcting its medial deviation. Another technique, the Scarf osteotomy, involves a Z-shaped cut along the shaft of the first metatarsal, enabling precise repositioning and often used for more severe deformities. These procedures may involve removing a small wedge of bone to facilitate the desired angular correction.
Soft tissue procedures are performed in conjunction with bone work to balance the forces around the joint. A lateral capsular release involves cutting or lengthening the tight ligaments and joint capsule on the outer side of the big toe joint, releasing the pull that contributes to the toe’s deviation. Concurrently, the stretched medial capsule may be tightened through a procedure called medial capsular plication, which helps stabilize the joint in its corrected position. In severe cases, arthrodesis or joint fusion may be performed. This involves removing the remaining joint cartilage from the ends of the bones and then fusing the first metatarsal and the proximal phalanx together with screws or plates, creating a stable, non-moving joint.
Restoring Foot Function
The goal of hallux valgus surgery is to restore the normal alignment of the big toe, reducing pain and improving the foot’s overall biomechanics. By correcting the abnormal angles of the bones and balancing the surrounding soft tissues, surgical procedures aim to redistribute pressure more evenly across the foot during walking and standing. This comprehensive approach allows the big toe to bear weight more effectively and function properly in propulsion.
Successful surgery leads to a significant reduction in pain and discomfort, particularly when wearing shoes. The corrected appearance of the foot is a beneficial outcome, but the primary focus remains on enhancing the foot’s ability to perform its natural functions. Patients often experience improved stability and a greater capacity for daily activities, making it easier to walk, run, and comfortably fit into a wider range of footwear.