Expected bony contact
Authors: Kıyak Görkem , Esemenli Tanıl 
Published: September 2018

Category:

Bunion

Introduction/Purpose:

Hallux Valgus has been traditionally quantitated by measuring Hallux Valgus Angle (HVA) and Intermetatarsal Angle (IMA). Classic treatment algorithms based on angular measurements limits the use of distal chevron osteotomy to cases with an IMA less than 15º, assuming possible correction is only 4-6º which is equivalent to 4 – 6 mm displacement. There are studies confirming that larger displacement distal osteotomies can be safely performed. Since distal metatarsal osteotomies provide a correction by shifting, we have created a new algorithm based on the expected bony contact and aim to use the full potential of the distal chevron osteotomy. The purpose of the present study is to investigate if this new concept is more reliable than the widely accepted angular measurements in hallux valgus surgery.

Methods:

Patients with symptomatic hallux valgus subdivided as mild, moderate and severe hallux valgus using traditional angular radiologic measurements. After excluding the mild cases we calculated the expected bony contact by measuring the width of metatarsal head, and the required amount of lateral shifting. We performed a modified chevron osteotomy with extended plantar limb for the cases if the expected bony contact is more than 20%. We excluded patients with congenital deformities of the foot, hallux rigidus, tarsometatarsal (TMT) instability previous first ray trauma or foot and ankle surgery, diagnosis of rheumatic, dysmetabolic, neurologic, infective or psychiatric pathologies. The 100-point AOFAS hallux-metatarso-phalangeal-interphalangeal scale was used to assess the clinical outcome. We also recorded per and postoperative complications like infection, hallux varus, recurrence, etc. Radiologic measurements recorded for statistical analysis.

Results:

There were 24 patients suitable for chevron osteotomy according to our classification. We also subdivided our patients as moderate (14) and severe hallux valgus (10) with traditional classification. Table shows the Radiographic results and AOFAS scores by groups Paired t-tests showed significant improvement comparing pre-op and post-op AOFAS scores, IMA, HVA and sesamoid position of moderate, severe and all patient subgroups. (p<0.001) Unpaired t-tests showed that the difference is not significant between moderate and severe subgroups when we compare post-op AOFAS scores, IMA, HVA and sesamoid position. (p>0.05) The difference between the expected bony contacts was not statistically significant in the moderate and severe subgroups.

Conclusion:

Modified chevron osteotomy performed well enough radiologically and from the perspective of patient satisfaction when used according to the new concept of “expected bony contact” criteria. Dividing patients into angular subgroups did not affect the results of modified chevron osteotomy. The amount of possible lateral translation is not correlated with IMA and HVA. Our study has shown that expected bony contact is a reliable criteria and superior to angular measurements for preoperative planning in hallux valgus surgery.