Expert Insights On Performing The Akin Osteotomy
There are numerous surgical procedures designed to correct the variations of bunion deformities. Often, the final step of the operation is to correct the valgus and abduction component of the great toe. This has been the subject of a popular and technically simple procedure that was introduced approximately 85 years ago.
In 1925, Akin proposed a hallux valgus procedure that consisted of removal of a wedge of bone from the great toe to achieve a rectus position.1 His procedure also included resection of the medial aspect of the first metatarsal head and the corresponding portion of the base of the proximal phalanx.
Surprisingly, during the next several decades, there was almost no published literature on this procedure. The popular procedure during this time was the Keller osteotomy with modifications by Lelievre, Viladot and Regnauld.2-5 The emphasis was on the intraarticular correction of hallux abducto valgus rather than extraarticular correction.
In 1967, Colloff and Weitz suggested that the benefit of the Akin procedure was the ability to correct a mild to moderate deformity without disturbing the congruity and soft tissue relationship of the first metatarsophalangeal joint.6 Numerous articles soon followed that addressed indications of the procedure, placement of the osteotomy and types of fixation.
In general, the indications for the Akin procedure include the correction of hallux valgus interphalangeus. Mann has also recommended using the procedure whenever the great toe causes displacement of the second toe.7 Specifically, the Akin procedure can correct an abnormal proximal articular set angle (PASA) by placing the osteotomy proximally on the phalanx. If one places the osteotomy distally, the surgeon can achieve correction of an abnormal distal articular set angle (DASA).
The surgeon can also place the osteotomy centrally and remove a cylindrical section of bone to shorten a long proximal phalanx. When there is a combination of a long proximal phalanx with a hallux interphalangeus deformity, one can correct this by removing a trapezoidal section of bone.8 The surgeon may perform a derotational Akin to correct a valgus rotation of the great toe.9
It is also recommended that the intermetatarsal angle be less than 15 degrees and the first metatarsophalangeal joint be congruous. When this criteria has not been met, it is possible to compensate for the abduction by taking a larger wedge out of the great toe. Surgery can make the toe straighter but clinically, it may have a cosmetically unacceptable, exaggerated concave surface medially. This procedure is known as a “cheater Akin.”
Pertinent Pearls For Ensuring The Optimal Incision And Osteotomy
The most common location for the incision by podiatric surgeons is on the dorsal medial aspect of the first metatarsophalangeal joint. This location provides excellent exposure of the first metatarsal head for distal osteotomies. One can extend this incision as far distal as necessary for access to the entire proximal phalanx. The surgeon can even expose the head of the phalanx for placement of a distal osteotomy.
Another method for exposing the head of the phalanx is to extend the incision distally to the interphalangeal joint. Extend the incision medially and then distally for several millimeters.10 In my experience, just extending the incision distally to the interphalangeal joint provides adequate exposure.