SLR - September 2021 - Jacob M. Perkins

High-Stress Distribution in the Lateral Region of the Subtalar Joint in the Patient with Chronic Lateral Ankle Instability

Reference: Nakasa T, Ikuta Y, Sumii J, Nekomoto A, Adachi N. High-Stress Distribution in the Lateral Region of the Subtalar Joint in the Patient with Chronic Lateral Ankle Instability. Arch Orthop Trauma Surg. 2021 Jul 20. doi: 10.1007/s00402-021-04078-6. PMID: 34286364.

Level of Evidence: III

Scientific Literature Review

Reviewed By: Jacob M. Perkins, DPM
Residency Program: University of Florida Health – Jacksonville, FL

Podiatric Relevance: Chronic lateral ankle instability is a common pathology treated by the podiatric physician. While the more present symptoms of pain recalcitrant to conservative treatment measures such as bracing and physical therapy are apparent, the more chronic sequela of potential joint destabilization and osteoarthritis are not. This article aims to quantify and delineate the arthritic progression of this pathology which can help podiatric practitioners with patient prognosis in non-operative patients and additionally help articulate indications in operative ones.

Methods: This was a level III comparative series of stress distribution of the talus in the ankle and subtalar joint of patients with chronic lateral ankle instability and a control group of patients without chronic lateral ankle instability. There were thirty-three ankles of thirty-two patients with inclusion criteria of presence of preoperative CT and eventual arthroscopic lateral ankle repairs. There were twenty-six ankles of twenty-two patients who did not have chronic lateral ankle instability with exclusion criteria of systemic arthropathies, concomitant osteochondral lesions of the talus, and osteoporosis treatment. The primary outcome was stress quantified in Hounsfield units on three-dimensional, color mapped computed tomography. Within the surgical group further relationships were correlated between the Hounsfield unit values and ankle activity score, osteoarthritis, talar tilting angle, and cartilage injury.

Results: The measured Hounsfield units in the anteromedial region of the talus and lateral region in the subtalar joint were higher in the patients with chronic lateral ankle instability than in the control group. Furthermore, within the chronic lateral ankle instability group, significantly higher values of stress Hounsfield units were found in patients who had an ankle activity score greater than or equal to 6, over 10 degrees of talar tilt angle, a cartilaginous injury confirmed on arthroscopy, and osteoarthritic changes in the medial gutter.

Conclusions: The authors concluded that there is a quantifiable stress increase in patients with chronic lateral ankle instability and further correlated these measurements within the group to other clinical findings routinely assessable by podiatric physicians. These findings can further our understanding of long-term sequela of patients who have or who have had lateral ankle instability. With reference to the parameters correlated to higher stress levels, these findings can additionally further aid in indications when deciding operative patients. However, to further strengthen this study post-operative CT color mapping comparisons of stress levels to preoperative values should be measured. 

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