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MRI study using a semi-rigid ankle brace MalleoLoc proven to be effective

Issue 01/2021

An ankle stability diagnostics study conducted in Freiburg, Germany, proven with an innovative, MRI-based method: the MalleoLoc brace significantly improves ankle congruency in patients with chronic mechanical instability and increases subjectively perceived stability.

Study director PD Dr. Dominic Gehring from the University of Freiburg’s Institute for Sports and Sports Science.

Is it possible to quantify mechanical instabilities in the upper ankle using 3D stress MRI imaging? And can this also prove the stabilizing effect of the semi-rigid MalleoLoc brace? Those were the two central questions of an ankle instability diagnostics study that was started in November 2019 by Dr. med. Markus Wenning (orthopedist at Freiburg University Hospital) and PD Dr. Dominic Gehring (sports scientist at Freiburg University).
As a parameter for mechanical ankle instability, the study used three-dimensional MRI scans to examine the size of the cartilage contact areas (CCA). The higher their congruency, the more stable the joint. That is why area congruency was examined in the normal position as well as in a functional position (plantar flexion + supination). The contact areas between the talus and the fibula as well as between the talus and the tibia were measured. 50 subjects took part in this controlled cross-sectional study, which consisted of a control group with healthy subjects (stable ankles) and 25 patients with mechanical ankle instability (MAI). The joint congruency was measured in different joint positions for all the patients. In the MAI group, all measurement parameters were also determined with the test subjects wearing the MalleoLoc ankle brace.

Measurable improvement in joint congruency

Study director, Dr. med. Markus Wenning, Department for Orthopedics and Trauma Surgery, Freiburg University Hospital, and clinician scientist in the Berta Ottenstein program supported by Freiburg University’s Medical Department.

The study was recently completed and provides valid findings for both questions. “The data shows that the measurement method delivers good and robust results in a larger cohort, too, and that three-dimensional talofibular joint congruency could be a suitable parameter to quantify ankle stability. We have also proven that the MalleoLoc brace has a positive mechanical effect on joint congruency,” Dr. Markus Wenning summarizes.
The study showed specifically that the talofibular articular surface significantly decreases in all test subjects when switching from the normal position to a functional position: by 32.8 percent in the control group and by 56.3 percent in the MAI group. Patients with chronic mechanical instability therefore show a significantly reduced joint congruency in a functional position compared with healthy subjects.
The effect of the MalleoLoc on this stability indicator in MAI patients also became clear. Improved joint congruency was observed in all three ankle dimensions – talofibular, talotibial horizontal and talotibial vertical. On average, the MalleoLoc increased the talofibular contact area by 18.8 percent, the talotibial horizontal area by 19.5 percent and the talotibial vertical area by as much as 32.2 percent. According to these findings, the MalleoLoc significantly improves joint congruency, which may provide a biomechanical explanation for its stabilizing effect in secondary injury prevention that was proven in other studies. The effectiveness of the brace is also apparent from the assessment of the test subjects themselves, who evaluated their subjective feeling of stability on a scale of 0 (very poor) to 10 (very good). Healthy control subjects rated their stability with MalleoLoc at 7.2 on average, MAI patients at 8.

Comparison of joint congruency in a functional position in healthy controls, subjects with mechanical instability (MAI) and subjects with mechanical instability wearing an ankle brace (MAI + MalleoLoc). The chart shows the mean values of the articular surface areas in square centimeters; * significant difference; p<0.05.

A method with potential

Valid data based on reproducible results, measurable effects on cartilage contact areas – the MRI measurement method offers a lot of research and application potential: “We want to see if we can determine a cut-off value for the extent of mechanical deficits from which patients would benefit from early surgical stabilization or need prolonged treatment with an brace to lower the recurrence rate and chronification risk after ankle sprains,” Dr. med. Markus Wenning explains. “We believe the prospects are good to use the MRI method for this group of patients as standard during everyday clinical work as soon as we can carry out the evaluation semi-automatically with a reduced measurement effort. We will continue to examine the options of clinical applications, in particular with a view to treatment recommendations, in current studies.”
The results regarding the MalleoLoc’s effectiveness are also interesting for further studies: “We can see a positive effect of the brace on joint congruency parameters, which explains the effectiveness in terms of mechanical stabilization. The findings suggest that this can lower the likelihood of recurrence,” Dr. Dominic Gehring explains. “We intend to examine the connection between mechanical instability and cartilage lesions in follow-up studies.”

 

Digital white paper

 

A summary of selected findings from the study conducted by Wenning et al. can be found in the white paper “The effectiveness of the MalleoLoc brace in reducing chronic mechanical ankle instability”. The PDF file can be obtained in German and English by contacting

medical.affairs@bauerfeind.com.

Images: Udo Schönewald, Patrick Seeger


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