Retrospective Analysis of the Akin Osteotomy

Steven Douthett, DPM1; Nathan Plaskey, DPM1; Lawrence Fallat, DPM FACFAS1; John Kish, PhD2

1Foot and Ankle Surgical Residency■ Beaumont Hospital – Wayne, MI 2Department of Medical Education ■ Beaumont Hospital – Dearborn, MI

STATEMENT OF PURPOSE LITERATURE REVIEW ANALYSIS AND DISCUSSION The lateral cortical hinge was disrupted intra-operatively in 47 patients. This most commonly occurred while The purpose of this study was the investigate the impact of lateral cortical hinge disruption on healing time of The Akin osteotomy was first introduced in 1925(1). Fixation techniques have progressed from a tongue depressor to monofilament wire, Kirschner wires, staples, and screws. Throughout the years, osteotomy the Akin osteotomy. Additionally, we evaluated the frequency of disruption of the lateral cortex, osteotomy placement, orientation, wedge size, and fixation methods have all been investigated (2,3,4,5). According to Frey et al., for correction of the DASA, the best placement of the osteotomy is in the proximal feathering for reduction of the osteotomy site in poor bone stock. We have found that in these patients, the displacement, and the need for surgical revision associated with the procedure. metaphyseal bone 5-7 millimeters distal to the articular surface of the base of the proximal phalanx (2). Their study also determined that removing 3 mm of bone resulted in 8 degrees of correction, 5 mm cortex is often thin, brittle, and easily breaks during reduction. It should be noted that these osteotomies resulted in 16 degrees of correction, and 8 mm resulted in 24 degrees of correction (2). Chacon et al. determined that crossing bicortical Kirschner wires were the most biomechanically stable form of fixation(3). were performed on teaching cases, likely contributing to intra-operative hinge disruption. Surgeons have advocated maintaining the lateral cortical hinge as an additional point of fixation. Lateral hinge fracture is a common complication that may occur intra-operatively or post-operatively secondary to Our study found that healing time did significantly change with disruption of the lateral cortex. Patients with METHODOLOGY AND HYPOTHESIS bone resorption or premature weight bearing. In their study of first metatarsal base osteotomies, Christensen et al noted that osteotomies which maintained the cortical hinge provided superior stability compared an intact lateral cortical hinge healed in a mean time of 7.05 weeks compared to those who sustained lateral A retrospective chart review was conducted of 132 consecutive patients who underwent an Akin osteotomy to osteotomies using identical internal fixation without maintenance of a cortical hinge (4). To combat lateral hinge disruption, Boberg et al. suggested there was less of a chance of hinge failure in an obliquely cortex interruption intra or post-operatively, which healed in a mean time of 8.06 weeks. We attribute this performed by the same board certified foot and ankle surgeon (LMF) between July 2011 and January 2014. oriented osteotomy as opposed to a transverse osteotomy (5). significant difference in healing time to micro motion and incomplete stability at the lateral aspect of the An Akin osteotomy was indicated when patients presented with an abducted hallux, or a hallux that Surprisingly, there is a paucity of literature accessing complications that may be associated with the Akin. Additionally, no study has evaluated the healing time of the osteotomy or the frequency of lateral cortical osteotomy site. Had hinge failure not been recognized intra-operatively and adequately fixated, healing time overlapped or underlapped the second digit. Weight bearing radiographs of the patient’s foot displayed hinge disruption. and complication rates would likely be even greater. either an increase in HAA, HAI angle, or DASA. The patient's bunion discomfort had to be significant enough Smoking history was also taken into account. 25% of our patients (N=33) were noted to have a smoking for the patient to request surgical correction. Patients were excluded if they sustained prior fracture of the history. Smoking has been shown to reduce bone and soft tissue healing potential by decreasing the proximal phalanx of the hallux or had prior hallux valgus surgery. oxygen-carrying capacity of hemoglobin as well as inhibiting the metabolism of oxidative energy at the Data collected from the individual’s medical records included the following: age, gender, tobacco use, foot RESULTS cellular level (6, 7). Surprisingly, we found no noteworthy difference in healing time of the osteotomies in operated on, osteotomy orientation, type of fixation employed, lateral cortical hinge integrity, healing time in One hundred thirty-two patients (132 feet) with a mean age at surgery of 46.9 years ± 15.8 (range 11-78 years) were included in this study. 110 patients were female and 22 male. The Akin procedure was smokers compared to non-smokers. Although we found this to be negligible, Krannitz et al. found that on weeks, displacement of osteotomy site, and the need for surgical revision. The osteotomy site healing was performed on 66 left and 66 right feet. Non-smokers comprised 75% (N=99) of the patient population. 15 osteotomies (11.4%) were oriented oblique to the long axis of the proximal phalanx and 117 (88.6%) average, smokers have a 42% increase in time needed to achieve bone healing in their study on elective assessed with anteroposterior, oblique, and lateral radiographs at two week intervals by a board certified were perpendicular to the long axis. foot surgery (8). In our study, we feel that the impact of smoking on bone healing was negated by the stable radiologist, as well as two contributing authors (LMF, NKP). Complete union of the osteotomy site was 47 (35.6%) lateral cortices were disrupted intra-operatively, of which, nine (19.1%) displaced in the postoperative course. Three of these patients required surgery to correct this displacement. An additional six fixation employed. determined by complete bridging of cortical bone. Minimum patient follow up was 14 months post- patients suffered lateral cortex fracture and osteotomy displacement post-operatively and two required surgical revision. In total, five patients required surgical revision, three of which sustained lateral cortex A total of five patients required surgical revision in our study. Of these five revisions, three sustained cortex operatively. An unpaired t-test was used to evaluate statistical significance of osteotomy healing time. Our disruption intra-operatively, and two of which sustained lateral cortex fracture post-operatively. interruption intra-operatively. Two patients left the operating room with an intact cortex, but fractured in the hypothesis was lateral cortical hinge disruption would lead to increased osteotomy healing time. The mean healing time for patients who retained lateral cortex integrity was 7.05 weeks, versus 8.06 weeks in patients who sustained lateral cortex disruption. The difference in healing time was found to be post-operative partial weight bearing period and subsequently required surgical revision. One of these five statistically significant (p=0.002) using an unpaired t-test. Smokers were not associated with a substantial delay in healing time. Osteotomy consolidation was noted at a mean of 7.06 weeks in smokers. In total, surgical revisions was not due to displacement, but to nonunion following lateral cortex interruption. PROCEDURE one patient suffered from superficial infection which resolved after a course of oral antibiotics. Six patients complained of prolonged edema, two of neuritis of the proper branch of the medial dorsal cutaneous There were some limitations to this study. All radiographs were read by one board certified radiologist and nerve, and two of generalized pain, all of which resolved within the follow up period. Two patients were unsatisfied with the cosmetic result. evaluated by two authors. The wide variety of fixation constructs limited the statistical comparisons which All patients underwent a chevron style osteotomy prior to the Akin procedure. The proximal phalanx was could be observed. The retrospective nature of this study also limited parameters which could be evaluated. exposed using the same incision as the first metatarsal osteotomy. The axis of the osteotomy site (proximal, Our study has shown that surgical complications can and do occur with the Akin osteotomy, which is central, or distal) and orientation (perpendicular or oblique to the long axis of the proximal phalanx) were Table 1: Fixation generally thought of as a simple procedure. We have found that disruption of the lateral cortical hinge has a determined based upon the patient’s presenting deformity. The osteotomy was performed under fluoroscopy statistically significant impact on healing time, even when adjunctive fixation is employed. Surgeons must with the intent to keep the lateral cortex intact. The hinge was feathered until it was reduced. The osteotomy take in account the importance of osteotomy stability and adequate fixation at the time of hinge disruption. site was evaluated for lateral hinge integrity and was fixated using one of the following techniques: screw, Additionally, we have noted a higher rate of displacement and subsequent surgical revision after cortical staple, monofilament wire, Kirschner wire, plate, or a combination. The fixation was tailored to the age of the interruption has occurred. Further prospective studies could evaluate the rate of displacement with varying patient, location of the osteotomy, the quality of the bone, and the patient’s ability to comply with the post- types of fixation and better assess and determine the most reliable method. operative course. When the lateral cortex was disrupted intra-operatively, adjunctive fixation was used if the Table 2: Time to osteotomy consolidation osteotomy was considered unstable. The stability of the osteotomy site was analyzed via manual pressure under intraoperative fluoroscopy. In the cases where the osteotomy site was deemed unstable, adjunctive 8.2 fixation via means available to the primary surgeon at the time of operation was used (staple, Kirschner wire, 8.06 REFERENCES screw, or cerclage wire). After the deformity was corrected, a layered closure was completed. Patients were 8 1.Akin OF. Treatment of hallux valgus a new operative procedure and its results. Med Sentinel 33:678–679, placed into a slipper cast post-operatively and allowed to weight bear to the heel as tolerated. 1925. 7.8 2.Frey C, Jahss M, Kummer FJ. The Akin procedure: an analysis of results. Foot Ankle 12:1–6, 1991. 3.Chacon Y, Fallat LM, Dau N, Bir C. Biomechanical Comparison of Internal Fixation Techniques for the Akin Osteotomy of the Proximal Phalanx. J Foot Ankle Surg 51:561–565, 2012. 7.6 4.Christensen JC, Gusman DN, Tencer AF. 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metatarsal base osteotomy. J Am Podiatr Med Assoc 1995 Feb; 85(2):73-82. 7.4 5. Boberg JS, Menn JJ, Brown WL. The distal Akin osteotomy: a new approach. J Foot Surg 30(5):431-436, 1991.

7.2 6.Kwiatkowski TC, Hanley EN, Ramp WK. Cigarette smoking and its orthopedic consequences. Am J Orthop WEEKS 7.05 7.06 25(9):590–597, 1996. 7. Daftari TK, Whitesides TE Jr, Heller JG, Goodrich AC, McCarey BE, Hutton WC. Nicotine on the 7 revascularization of bone graft. An experimental study in rabbits. Spine 19(8):904–911, 1994. 8. Krannitz K, Fong H, Fallat L, Kish J. The Effect of Cigarette Smoking on Radiographic Bone Healing After 6.8 Elective Foot Surgery. J Foot Ankle Surg 46(5): 525-527, 2009.

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6.4 Intact Fracture Smoking Figure 2. Dorsoplantar view showing the senior Figure 1. Dorsoplantar view showing a author’s preferred method of fixation utilizing a 3-0 displaced Akin osteotomy after staple failure. headless compression screw.