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Second biomechanical study of a tri-compartment unloader

By using a biomechanical model of the knee, this study demonstrated a tri-compartment unloader brace (TCU) can reduce a number of contact and ligament forces across the knee during a deep knee bend. The results replicate and extend the findings of Budarick et al. 2020, which demonstrated that a TCU can reduce knee joint loading.

Third biomechanical study of a novel tri-compartment unloader knee brace

This study examined the biomechanical effects of a tri-compartment unloader brace (TCU) in patients with multi-compartment knee OA while they performed actions of daily living. Results showed that Levitation can significantly reduce quadriceps muscle effort and internal knee extension moments.

Research Summary

First evaluation of a novel tri-compartment unloader

Design evaluation of a novel multicompartment unloader knee brace

Budarick, A.R., MacKeil, B. E., Fitzgerald, S., and Cowper-Smith, C.D. (2020). Journal of Biomechanical Engineering. 142(1).

Key Findings

Reduced Knee Joint Forces

At a 90 degree flexion angle, Levitation can reduce PF and TF joint contact forces by an amount equivalent to losing 45 lb of bodyweight.

Powerful extension assistance

Levitation is found to provide sufficiently powerful extension assistance to unload all three knee compartments when the knee is flexed and bearing weight.

Confirmed by Subsequent Research

The unloading capabilities of Levitation, as indicated in this study, are replicated in future studies.

This study outlined the unique design of a novel tri-compartment unloader (TCU) knee brace and analyzed its potential to unload multiple compartments of the knee. The TCU’s force output was measured in order to calculate the capacity of the brace to unload the knee joint at various angles. The findings demonstrated that, at a 90-degree knee bend, the TCU can reduce patellofemoral (PF) and tibiofemoral (TF) joint contact forces to a level that would be achieved by losing 45 lb of bodyweight (Figure 2B). For comparison, the only other commercially available knee extension assist brace was tested and found to reduce internal joint contact forces to a level that would be achieved by losing 5 lb of bodyweight.

 

Figure 2A

Assistive moment provided by the Levitation Tri-Compartment Unloader versus the OA Rehabilitator at varying brace flexion angles. 

 

Clinical study on Levitation 2 Knee brace at mccaig institute

Figure 2B

Effective bodyweight reduction at 90 degrees of knee flexion offered by the Levitation Tri-Compartment Unloader and the OA Rehabilitator.

implications for care

The Importance of Joint Unloading and the Effect of Weight Loss

The reduction of joint contact forces to a level that would be achieved by losing 45 lb of bodyweight is important for understanding how Levitation can provide rapid pain relief and functional improvement for patients with knee OA.

Clinical guidelines for the conservative treatment of knee osteoarthritis (OA) agree that weight loss is an important intervention that can improve pain and function while simultaneously helping to delay the progression of knee OA. For weight loss to be effective in the treatment of OA, research has shown that patients must lose at least 10% of their starting bodyweight, while the largest benefits are seen in patients who achieve a >20% reduction in bodyweight. For an average individual with knee OA weighing 205 lb, a 20% body weight reduction can be a daunting challenge. The findings of this study indicated that a TCU can reduce joint forces to a level that would be achieved by losing 45 lb of bodyweight, which is the equivalent of a 22% bodyweight reduction in a 205 lb individual and a 27% bodyweight reduction in a 165 lb individual.2

The data showed that the TCU reduced forces in both the PF and TF joints, indicating that a TCU’s spring loaded hinge is sufficiently powerful to provide clinically meaningful tri-compartment unloading benefits. Given that unloading the knee is commonly associated with a reduction in pain for patients with knee OA, the researchers concluded that the TCU may be an effective treatment option to reduce pain and functional limitations in patients with multicompartmental osteoarthritis (OA), allowing them to resume or increase their physical activity.3

This study was our first formal evaluation of the biomechanical effects of the Levitation knee brace. It provided the first data supporting the tri-compartment unloading effect of the brace. These findings informed the direction of future research and have since been replicated in independent studies that focused on the biomechanical effects of Levitation.4

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Third biomechanical study of a novel tri-compartment unloader knee brace
Third biomechanical study of a novel tri-compartment unloader knee brace

Third biomechanical study of a novel tri-compartment unloader knee brace

This study examined the biomechanical effects of a tri-compartment unloader brace (TCU) in patients with multi-compartment knee OA while they performed actions of daily living. Results showed that Levitation can significantly reduce quadriceps muscle effort and internal knee extension moments.

View Details

Second biomechanical study of a tri-compartment unloader
Second biomechanical study of a tri-compartment unloader

Second biomechanical study of a tri-compartment unloader

By using a biomechanical model of the knee, this study demonstrated a tri-compartment unloader brace (TCU) can reduce a number of contact and ligament forces across the knee during a deep knee bend. The results replicate and extend the findings of Budarick et al. 2020, which demonstrated that a TCU can reduce knee joint loading.

View Details