SLR- November 2022- Callie Morlock, DPM
Title: Measuring Deltoid Insufficiency After Supination-External Rotation Ankle Fracture with Lateral Talar Subluxation on Gravity Stress ViewReference: Haupt ET, Sebro R, Iturregui JM, Stanborough R, Siddiqui A, Shi GG. Measuring Deltoid Insufficiency After Supination-External Rotation Ankle Fracture With Lateral Talar Subluxation on Gravity Stress View. Foot Ankle Int. 2022 Sep 8:10711007221119162. doi: 10.1177/10711007221119162. Epub ahead of print. PMID: 36082428.
Level of Evidence: Level II, prospective comparative
Scientific Literature Review
Reviewed By: Callie Morlock, DPM
Residency Program: North Colorado Medical Center, Greeley, CO
Podiatric Relevance: When evaluating patients after a traumatic injury such as an ankle fracture, it is important for a thorough evaluation to provide the patient with the best care and outcome. Even small amounts of malalignment related to these injuries can have devastating effects regarding post traumatic osteoarthritis, hence why it remains important to provide the best treatment possible. Evaluation of the deltoid remains a difficult task after such injuries however the integrity of the ligament may determine the stability of the talus within the ankle mortise. Due to the rotational component of these injuries, there may be a migration of the talus that may be more difficult to assess and a new measurement of the lateral talar subluxation could assist with defining instability.
Methods: This is a review that identified 103 gravity stress views (GSV) of supination external rotation (SER) ankle fracture radiographs from an outpatient clinic or emergency department. When evaluating the radiographs, the medial clear space (MCS), superior clear space (SCS), and a new measurement of the lateral talus subluxation (LTS) was evaluated. The LTS was measured by identifying a vertical line demarcating the anterolateral rim of the ankle syndesmosis and the lateral edge of the talar dome. If these two lines are not continuous, possible subluxation was noted and the horizontal distance between the edge of the syndesmosis and the lateral wall of the talus was measured. Surgery was indicated for SER4 variant ankle fractures with compromised ankle joint stability after surgeons evaluated the LTC versus the MCS.
Results: The MCS, SCS, and LTS measurements were performed on 103 GSV radiographs. There was found to be a significant increase in the mean MCS, MCS:SCS ratio, and LTS within the group that was deemed appropriate for operative management. Person correlation analysis found a positive and significant correlation between the MCS and SCS along with the MCS and LTS. It was found that a MCS greater than or equal to 5mm had a sensitivity of 95% and specificity of 60% while LTS greater than 4mm had a sensitivity of 95% and a specificity of 75% after evaluations on radiographs.
Conclusion: When evaluating radiographs for SER 4 type ankle fractures, it is important to understand the integrity of the deltoid complex. This can be evaluated using the MCS, SCS, and a new measurement of the LTS. It has previously been shown that the MCS may cause an overestimate for surgical intervention as the deep fibers of the deltoid ligament may remain intact. The new measurement using the LTS has shown that a continuous line along the lateral talus and syndesmosis likely represents and anatomically aligned talus despite suffering a rotational injury. When evaluating this type of injury, it can be difficult to truly understand the stability of the medial structures, but the LTS can provide adjunctive information when the MCS measurement may not fully represent the instability. Regardless, bimalleolar equivalent fractures remain a prominent injury and required careful evaluation and management surgically when appropriate.