Evaluation of the Soft Tissue Correction Improvement with Tendon Transfer in Flatfoot Deformity Reconstruction

Abstract

Category: Midfoot/Forefoot Introduction/Purpose: An adult flatfoot deformity is a complex pathology that has been attempted to be addressed surgically with a variety of different procedures. Transfer of the flexor tendon has been a cornerstone of the treatment of flatfoot deformity for years. After the procedure, the appearance of the bony correction of the foot is noticeable on radiography, but after surgery when the patient begins to bear the weight the soft tissue laxity affects the achieved bony correction when compared to non- weight bearing images. This study aims to identify the effects of tendon transfer on bony and soft tissue after weight-bearing to better predict what the outcomes of surgery will be. Methods: 29 patients were included. there were 18 patients that underwent tendon transfer as part of their flat foot correction and 11 patients that underwent non-tendon transfer procedure for correction of flat foot deformity. Imaging was performed on patient's weight bearing (WB) and non-weight bearing (NWB) before and after surgery. X-ray measurements included Angles: calcaneal pitch (ML-CP), talo-1st metatarsal (ML-T1MT),talocalcaneal (ML-TC), talar declination (ML-Tdec), calcaneal 1st metatarsal (ML-C1MT) and Distances: talar height (ML-Tal-h), navicular height (ML-Nav-h), 1st cuneiform height (ML-1CN-h), cuboid height (ML-Cub-h), and 1st to 5th metatarsal distance (ML-1CN/5MT) in lateral X-ray and Angles: talonavicular coverage (AP-TN), talar 1st metatarsal (AP-T1MT), talar 2nd metatarsal (AP-T2MT) and Distances: talonavicular uncoverage distance in AP. The differences in measurement between the pre op post op non weight bearing considered as bony correction effect The differences in measurement between the pre op post op weight bearing considered as soft tissue effect. Results: the results from non-weight bearing imaging, tendon transfer had a statistically significant impact on calcaneal pitch (, p=0.026), Talo-1st metatarsal (p=0.048), talar declination ( p=0.038), talar height (p=0.016), navicular height ( p=0.014), 1st cuneiform height (p=0.001), talonavicular coverage (p=0.019), talar-1st metatarsal angle (p=0.015), and talar to 2nd metatarsal angle ( p=0.001). the results from WBimaging, tendon transfer had a statistically significant impact on calcaneal pitch ( p=0.000), calcaneal 1st metatarsal (p=0.02), talar height (35 to 39, p=0.003), navicular height ( p=0.002), 1st cuneiform height (p=0.016), cuboid height ( p=0.016), 1st to 5th The post-op effect calcaneal pitch was 12 degrees of difference in NWB compared to 6 degrees of difference in WB The effect on talar height, navicular height, and 1st cuneiform height was 10mm, 9mm, and 8mm, respectively, in NWBimages. This compares to an effect of 4mm, 6mm, and 4mm, respectively, WB imaging. Conclusion: When comparing NWB to WBimages, the effect of surgery on flat foot correction is consistently less pronounced inWB. there will be a difference between the bony correction and soft tissue correction. there is still a significant soft tissue effect seen in WBimaging. The comparison between NWB, WB changes shows that the soft tissue effect is around 50% of the bony correction on several key measurements. These include calcaneal pitch and talar, navicular, and 1st cuneiform height. These results provide a framework for establishing the soft tissue effect that tendon transfer surgery provides for flat foot correction surgery.