Abstract
Category:
Hindfoot; Basic Sciences/Biologics
Introduction/Purpose:
Since its description by Evan for correction of overcorrected clubfoot cases, lateral column lengthening ( LCL) has been widely used for correction of pes planovalgus deformity of any etiolog. The main indication is correction of forefoot abduction manifested radiologically as talonavicular uncoverage. It was reported by many authors that LCL improved forefoot abduction and talonavicular uncoverage, but it was also noticed that LCL corrects the flattening of medial longitudinal arch. The mechanism by which LCL corrects the medial longitudinal arch is still not clearly understood. It was also reported that LCL is associated with forefoot supination, but the exact mechanism of supination is not understood. This study aimed to try to understand the mechanism by which LCL changes the shape of the foot.
Methods:
LCL osteotomy using Hintermann technique was performed in ten fresh frozen below knee cadaveric specimens. After completion of the osteotomy, the talus and leg were removed to monitor how the foot moves under the talus with opening of the osteotomy to change the shape of the foot. The amounts of osteotomy displacement medially, laterally and planetary were observed and measured. After that, the whole plantar skin was removed and plantar ligaments were dissected to study the influence of plantar ligaments on the plane of motion of the osteotomy and the effect of the osteotomy on plantar ligaments.
Results:
With opening of the osteotomy, the distal portion did not move in pure adduction. Instead, it moved medial and plantar, working as a dorsolateral opening wedge . So, the distal portion was adducted and plantarflexed correcting the forefoot abduction and the flat arch. Because the osteotomy opens dorsally and laterally only, the lateral part of the distal portion was plantar flexed more than the medial part, and this is the cause of forefoot supination. After dissection of plantar ligaments, it was found that the long and short plantar ligaments prevent the osteotomy from opening inferiorly . It was possible to move the distal portion in pure adduction only after cutting the long and short plantar ligaments. Plantar fascia was relaxed after opening of the osteotomy.
Conclusion:
This mayexplain how the LCL osteotomy corrects the flat medial longitudinal arch and how it causes supination and lateral side overload. Based on this study, Cotton osteotomy should be added to LCL to correct the supination. Also, plantar fascia tightening can not be the cause of medial longitudinal arch correction as it actually becomes more lax after opening of the osteotomy.