A Closer Look At An Emerging Fixation Option For The Akin Osteotomy
The original Akin osteotomy for the correction of hallux abducto valgus (HAV) included resection of the medial prominence of the first metatarsal head in combination with a medial based wedge osteotomy of the proximal phalanx of the hallux.1 Subsequently, there have been several modifications to the original procedure in order to address factors such as location, rotation, shortening, dorsiflexion and plantarflexion.2-12
In regard to fixation options, researchers have described different approaches (transverse, oblique) to the orientation of the osteotomy.11
The Akin procedure is rarely indicated alone in the treatment of HAV deformity but surgeons commonly use it in combination with a more proximal procedure in order to address all components of the deformity.13 Surgeons utilize this procedure in the correction of a structural lateral deviation deformity of the hallux due to a high distal articular set angle (DASA) or hallux interphalangeus angle (HIA). Contraindications of this procedure include severe metatarsus primus varus, incongruous and/or severe osteoarthritis of the first metatarsophalangeal joint (MPJ).12
The original procedure described stabilization of the osteotomy via external splinting. Advances in fixation techniques introduced a variety of internal fixation options including: Kirschner wires (single or crossed double); stainless steel wire-loop fixation; and the more rigid options of the screw or staple.14
Let us take a closer look at the use of EasyClip SI™ staple fixation (Memometal Technologies, Inc.), which is a viable option for the fixation of an Akin osteotomy. The advantages of using the EasyClip SI include:
• elastic memory property of the material that allows for constant compressive forces from 5 to 6 kg;
• rigid fixation;
• technical ease of insertion that minimizes surgery time; and
• a low profile that minimizes the chance of irritation to the patient and thus the need of a second surgery for removal of hardware.
A Step-By-Step Guide To The Surgical Technique
Ensure the patient is in a supine position on the operating table. Following IV sedation, local anesthesia (Mayo block) and the application of an ankle tourniquet (if appropriate), proceed to perform the surgical prep and drape of the extremity.
Make a curvilinear skin incision over the dorsomedial aspect of the first MPJ extending from approximately the midshaft of the first metatarsal to approximately the head of the proximal phalanx. Place the incision medial to the extensor hallucis longus (EHL) tendon and follow the contour of the underlying joint alignment. Identify and retract all vital neurovascular structures during dissection and exposure of the osteotomy site.
One would perform the appropriate first metatarsal procedure first. We have typically performed the Akin in combination with an Austin osteotomy (through and through, distal apex V-type osteotomy through the head and distal shaft of the metatarsal) and two-screw fixation.
The surgeon would perform a transversely oriented Akin procedure because it provides a wider surface area of bone on each side of the osteotomy in which to secure the staple. Proceed to perform subperiosteal dissection of the proximal phalanx. Perform an osteotomy with the base medial and the apex proximal. For a proximal Akin, the apex is located at least 5 mm away from the MPJ to ensure preservation of the joint space. Take caution to preserve the lateral cortex to serve as a second point of fixation. “Feather” the osteotomy and reduce until you have achieved good correction and bone apposition.