Expert Insights On Performing The Akin Osteotomy
Plates. Bone plates are usually not used for the Akin osteotomy. If the surgeon uses a plate, one can only apply it to the dorsal surface of the phalanx. In addition, there is very little subcutaneous tissue so the plate and screws must be low profile in order to prevent soft tissue irritation. Even if the surgeon is using a locking plate, he or she should utilize bicortical fixation. Research has shown that unilateral fixation has only half the holding power of bicortical fixation.22
Interfragmentary compression with a lag screw generates the greatest amount of compression in an oblique fracture but the surgeon cannot accomplish this with a transverse osteotomy or fracture. However, one can achieve some compression using a straight plate on a transverse osteotomy. This involves drilling the hole eccentrically, away from the osteotomy, within the holes of the plate. As the screws tighten, the bone shifts toward the osteotomy site and compression occurs at the bone-plate junction.
What You Should Know About Complications
Fracture of the lateral hinge is a complication that can occur while making the osteotomy or postoperatively through bone resorption or premature weightbearing. Researchers have reported restriction of motion as well as arthritis of the interphalangeal joint but this appears to have been more of a clinical and radiographic observation with patients remaining asymptomatic.6,11,23 Researchers have also reported inadvertently extending the osteotomy into the metatarsophalangeal joint, resulting in degenerative joint changes.24
Frey noted that the most common technical complication was plantar angulation of the osteotomy site.11 She felt this could be due to the pull of the extensor hallucis longus or malposition of the osteotomy during the procedure. Goldner noted that upward displacement of the distal fragment could occur as one completes the osteotomy.25 Researchers have also reported nonunion and malposition as well as delayed union.11
Authors have also noted overcorrection, under-correction and sagittal plane deformities such as hallux extensus and hallux malleus.12 Other potential complications include: internal fixation failure, resulting in gapping of the osteotomy; extensor tendon irritation; displacement of internal fixation; delayed healing and infection.13,17
Postoperative splints, bandages and surgical shoes have been recommended following the procedure. Usually, one performs the Akin in conjunction with a first metatarsal osteotomy and non-weightbearing with cast immobilization. This provides the best protection against complications like delayed healing, nonunion and displacement.
For the best correction of hallux abductus, perform the procedure only after reducing the intermetatarsal angle and ensuring the joint is congruous.
Do everything you can to preserve the lateral hinge but if it is weak or breaks, use additional internal fixation. When it comes to osteoporotic bone, the cortex is brittle and may easily break.
If one is placing the Akin in diaphyseal bone, it may take longer to heal than the distal first metatarsal osteotomy, which the surgeon would usually place in the metaphysis. I would not permit full weightbearing until I see evidence of radiographic consolidation.
Although the Akin is generally thought of as a minor procedure, complications do occur. Respect the principles of bone healing and internal fixation when performing this procedure.
Dr. Fallat is a Fellow of the American College of Foot and Ankle Surgeons. He is the Director of Podiatric Surgical Residency at Oakwood Annapolis Hospital in Wayne, Mich.
Editor’s note: For related articles, see “Can Alternative Fixation Foster Better Outcomes With The Akin Osteotomy?” in the March 2007 issue of Podiatry Today or “Key Pearls For An Alternative Approach To The Akin Osteotomy” in the August 2006 issue.