Assessing risk of damage to posterior ankle structures during total ankle arthroplasty

SLR - June 2022 - Alex Barnett, DPM

Reference: Callaghan CJ, McKinley JC. Assessing risk of damage to posterior ankle structures during total ankle arthroplasty. Bone Jt Open. 2021;2(7):503-508. doi:10.1302/2633-1462.27.BJO-2021-0057.R1

Level of Evidence: IV

Scientific Literature Review

Reviewed By: Alex Barnett DPM
Residency Program: John Peter Smith Hospital

Podiatric Relevance: Total ankle replacements Are becoming more prevalent in treating end stage ankle arthritis. Placement of guide wires have the potential to cause significant injury to the proximate vital structures.

Methods: The Authors looked at 5 cadaver specimens and used the infinity prophecy total ankle replacement system.  Exclusion criteria included any previous trauma or soft tissue damage or bone deformity. The transcortical pins were inserted beyond the tibia intentionally to simulate surgeon inserting past the posterior cortex of the tibia. The tissue was then reflected off the posterior aspect of the leg. The tibial nerve and artery as well as posterior Tibi-al tendon, Flexor Digitorum Longus, Flexor Hallux Longus were then identified to see if they had any injury.

Results: The tibial nerve was found to be contacted 4/5 specimens, no signs of gross structural damage. The tibialis posterior artery and vein was contacted in 4/5 specimens, 3/19 pins showed physical signs of gross structural dam-age. Tibialis posterior tendon was contacted in all 5 specimens 11/14 pins showed physical signs of gross structural damage. FDL tendon was contacted in 2/5 specimens, and none showed gross structural damage. FHL tendons were never contacted. The tibial pins lying within the anatomical axis of the tibia showed more likely to contact posterior neurovascular structures.

Conclusion: The authors concluded that neurovascular structures are at risk with transtibial pins from the infinity prophecy system. The pins that are placed in the middle of the tibia are most likely to injure posterior structures. Tactile feedback is mostly used to determine if the surgeon has gone through the posterior cortex of the tibia however in elderly patients, total ankles are most likely to be applied. The posterior cortex can be relatively thin. Increasing lateral images while applying transtibial pins can help reduce the risk of damaging posterior structures. I conclude that placing transtibial pins increases the risk of posterior structures. This is not routinely thought of to increase serious injury to the lower extremity. This information will help future surgeons take more care in placing the pins in the tibia to preserve all posterior structures and reduced injury to the patient.