Minimally Invasive Chevron and Akin (MICA) Procedure
A Chevron osteotomy is indicated for correction of a mild to moderate hallux valgus deformity. This allows for a small reduction of the angle between the first and second metatarsal. It is ideal for bunions that are not particularly pronounced.
The procedure involves a V-shaped cut in the distal aspect of the first metatarsal near the metatarsal head. This allows the distal aspect of the bone to be translated between 45 mm in the lateral direction. The cut bone is then fixed in this position with a small screw or a suture of some sort. The excess bone on the inside of the foot (medial side) is then resected. The joint capsule is also tightened to allow for correction of the bunion (link to 1st MTP medial Capsulorraphy).
The Akin procedure is a medial closing wedge osteotomy used to correct hallux valgus interphalangeus. The fragments may be stabilised with a suture, wire or staple.
The Akin is not commonly done on its own; it is usually performed as a component of a larger procedure, in which a technique such as a chevron or scarf osteotomy is simultaneously used for the correction of MTP joint angulation and metatarsus primus varus. Two series of isolated Akin procedures both reported a high failure rate in the presence of significant uncorrected metatarsus primus varus.
- Wound healing Problems
- Local nerve injury
- Deep Vein Thrombosis (DVT)
- Pulmonary Embolism (PE)
Complications that are specific to Chevron and Akin osteotomy include:
- Malunion: This can occur when the bone either is not positioned correctly resulting in abnormal position of the toe or where the position of the osteotomy changes following surgery. In this instance, the toe may be malpositioned even to the point where further surgery is required.
- Avascular necrosis of the metatarsal head: This occurs when there is a loss of blood supply to the metatarsal head. Fortunately, this is relatively uncommon occurring in less than 3% of patients.
- Recurrence of the Deformity: Other complications include failure to fully correct the bunion deformity or the potential for recurrence of the bunion over time.