The Cotton Osteotomy is a surgical procedure used in foot and ankle reconstruction, primarily targeting the correction of flatfoot deformities. This operation is classified as an opening wedge osteotomy, meaning a controlled cut is made into a bone, and a gap is created and held open by a wedge-shaped graft. The procedure is performed on the medial cuneiform, one of the small bones located in the midfoot that supports the inner arch. The goal is to restore the foot’s natural arch by altering the bony structure of the medial column.
The procedure corrects forefoot supination, a common finding in flexible flatfoot (pes planovalgus). By lengthening the medial column, the surgery drives the front part of the foot downward toward the ground, a movement called plantarflexion. This action realigns the foot’s mechanics when conservative treatments like orthotics or physical therapy have failed to relieve pain or improve function.
Understanding the Need for Cotton Osteotomy
The primary indication for this procedure is a flexible flatfoot deformity that has not responded adequately to non-surgical management. In a flexible flatfoot, the arch collapses when the patient stands, but a partial arch reappears when the foot is non-weight bearing. This collapse often results in the forefoot being angled upward relative to the rearfoot, referred to as forefoot supination or varus.
This upward tilt prevents the first ray (the first metatarsal and medial cuneiform) from making firm contact with the ground during walking, compromising the foot’s ability to function as a rigid lever during push-off. The goal of the Cotton Osteotomy is to address this bony deficiency by lengthening the bone on its dorsal (top) side, thereby plantarflexing or lowering the medial column. This surgical lengthening avoids the shortening that can occur with other arch-reconstruction techniques that involve joint fusion.
The precision of this correction is measurable. Studies show that for every millimeter of opening wedge graft inserted into the medial cuneiform, an average of approximately 1.9 degrees of plantarflexion is achieved in the medial column. This controlled adjustment of the bony architecture is necessary to re-establish the proper relationship between the forefoot and the rearfoot, ensuring the foot is plantigrade, meaning the entire sole can rest flat on the ground.
The procedure is rarely performed in isolation; it usually acts as an adjunctive step in a more comprehensive flatfoot reconstruction. It is often combined with other procedures, such as a calcaneal (heel bone) osteotomy to correct the hindfoot alignment or an Achilles tendon lengthening to address tightness in the calf muscle.
The Surgical Procedure Step-by-Step
Pre-operative planning involves utilizing imaging studies like X-rays to determine the required size and angle of the wedge needed for correction. The procedure begins with the patient under anesthesia, and the surgeon makes an incision over the medial cuneiform bone. Careful dissection is performed to protect nearby delicate structures, most notably the medial dorsal cutaneous nerve and the saphenous vein.
Once the medial cuneiform is exposed, the surgeon creates the osteotomy, a controlled cut through the bone that stops just short of the plantar (bottom) cortex. This incomplete cut is crucial as the remaining bone acts as a hinge, allowing the bone to be opened without separating completely. A specialized instrument called a distractor is then used to gently pry open the cut, creating the desired wedge-shaped gap.
The opening wedge is oriented dorsally, which is the mechanism for achieving the necessary plantarflexion of the first ray. Into this newly created space, a wedge-shaped graft material is inserted to maintain the correction. This graft can be:
- An allograft (bone from a donor).
- An autograft (bone harvested from the patient, often the heel).
- A synthetic wedge.
- A metallic wedge.
After the graft is seated and the desired arch elevation is confirmed, the new position is secured using internal fixation. This fixation commonly involves small screws, plates, or staples, which hold the graft firmly in place while the bone naturally heals and fuses around the wedge. Fixation ensures stability during the initial healing phase. The incision is then closed with sutures, and the foot is prepared for post-operative immobilization.
Post-Operative Care and Expected Recovery Timeline
The immediate post-operative period involves immobilizing the foot in a splint or cast to protect the surgical site and the newly inserted bone graft. Pain management is controlled with prescription medication, and the foot must be kept elevated consistently to minimize swelling. During this initial phase, patients are strictly non-weight bearing on the operative foot to allow the osteotomy site to begin fusing.
The non-weight bearing period typically lasts a minimum of six to eight weeks, during which time the patient must use crutches, a walker, or a knee scooter. At the end of this phase, X-rays confirm sufficient bone healing and graft incorporation before any weight is applied. Once the surgeon confirms adequate healing, the patient transitions from a full cast to a controlled ankle motion (CAM) boot, also known as a walking boot.
The patient begins gradual weight bearing during the next stage, usually between weeks six and twelve, slowly increasing the load on the foot as tolerated. Physical therapy becomes a part of the recovery plan at this point, focusing on restoring the foot’s strength, flexibility, and balance. Therapy exercises target the ankle and foot joints to regain the full range of motion lost due to immobilization.
A return to normal, supportive shoes generally happens around the three-month mark, though swelling may continue to influence footwear choice for longer. Return to full activity, including higher-impact exercise and sports, is a gradual process that can take anywhere from six months to a full year. Long-term success depends on the individual’s commitment to the recovery and physical therapy protocol.