Joint unloading ankle brace to aid cartilage regeneration

Ankle injuries are one of the most common sports injuries that often lead to further complications such as cartilage defects. Recovery from these injuries can take a long time and a solution that could aid in the rehabilitation of these injuries is beneficial to the young and active patient group. The goal of this study is to design a device that can unload the patient’s ankle to such an extent that recovery is promoted. Using human motion analysis and a mathematical descriptive model, an unloading mechanism is designed that modifies the forces on the ankle joint. The resulting device consists of an attachment to the lower leg onto which a mechanism is attached that transfers a part of the load of the foot to the lower leg. The device is tested using a force plate set-up. The results are that the device can provide an unloading force throughout the stance phase of gait, reducing the maximum load on the ankle from 1.2 BW to 0.94 ± 0.04 BW. The proposed design is a wearable device that could be used during the rehabilitation of a patient’s ankle. The manner in which this device should be attached to the user’s leg needs further research; when these limitations are solved further testing can be initiated.Medical instruments and Medical saftey (Biomedical engineering)BioMechanical EngineeringMechanical, Maritime and Materials Engineerin

What quantitative mechanical loading stimulates in vitro cultivation best?

Articular cartilage has limited regeneration capacities. One of the factors that appear to affect the in vitro cultivation of articular cartilage is mechanical stimulation. So far, no combination of parameters has been identified that offers the best results. The goal is to review the literature in search of the best available set of quantitative mechanical stimuli that lead to optimal in vitro cultivation. The databases Scopus and PubMed were used to survey the literature, and strict in- and exclusion criteria were applied regarding the presence of quantitative data. The review was performed by studying the type of loading (hydrostatic compression or direct compression), the loading magnitude, the frequency and the loading regime (duration of the loading) in comparison to quantitative evidence of cartilage quality response (cellular, signaling and mechanical). Thirty-three studies met all criteria of which 8 studied human, 20 bovine, 2 equine, 1 ovine, 1 porcine and 1 canine cells using four different types of cultivated constructs. Six studies investigated loading magnitude within the same setup, three studies the frequency, and seven the loading regime. Nine studies presented mechanical tissue response. The studies suggest that a certain threshold exits for enhanced cartilage in vitro cultivation of explants (>20 % strain and 0.5 Hz), and that chondrocyte-seeded cultivated constructs show best results when loaded with physiological mechanical stimuli. That is a loading pressure between 5–10 MPa and a loading frequency of 1 Hz exerted at intermittent intervals for a period of a week or longer. Critical aspects remain to be answered for translation into in vivo therapies.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin

The Mechanical Functionality of the EXO-L Ankle Brace: Assessment With a 3-Dimensional Computed Tomography Stress Test

A new type of ankle brace (EXO-L) has recently been introduced. It is designed to limit the motion of most sprains without limiting other motions and to overcome problems such as skin irritation associated with taping or poor fit in the sports shoe. To evaluate the claimed functionality of the new ankle brace in limiting only the motion of combined inversion and plantar flexion. Controlled laboratory study. In 12 patients who received and used the new ankle brace, the mobility of the joints was measured with a highly accurate and objective in vivo 3-dimensional computed tomography (3D CT) stress test. Primary outcomes were the ranges of motion as expressed by helical axis rotations without and with the ankle brace between the following extreme positions: dorsiflexion to plantar flexion, and combined eversion and dorsiflexion to combined inversion and plantar flexion. Rotations were acquired for both talocrural and subtalar joints. A paired Student t test was performed to test the significance of the differences between the 2 conditions (P ≤ .05). The use of the ankle brace significantly restricted the rotation of motion from combined eversion and dorsiflexion to combined inversion and plantar flexion in both the talocrural (P = .004) and subtalar joints (P < .001). No significant differences were found in both joints for the motion from dorsiflexion to plantar flexion. The 3D CT stress test confirmed that under static and passive testing conditions, the new ankle brace limits the inversion-plantar flexion motion that is responsible for most ankle sprains without limiting plantar flexion or dorsiflexion. This test demonstrated its use in the objective evaluation of brace