Functional evaluation of a novel fibreglass-reinforced polyamide custom dynamic AFO for foot drop patients: A pilot study

BACKGROUND

Ankle-foot orthoses (AFOs) are orthopaedic devices often prescribed to treat foot drop. For patients who are not satisfied with off-the-shelf solutions, custom AFOs personalized to the patient's lower limb anatomy are required. Dynamic AFOs provide stability while allowing for physiological ankle mobility in the stance phase of walking.

RESEARCH QUESTION

Can a morphology-based dynamic custom AFO made of fiberglass-reinforced polyamide restore a quasi-normal gait pattern and improve comfort in patients with foot drop?

METHODS

In this pilot study, the legs and feet of ten foot drop patients (age=64.9 ± 11.4 years; BMI=26.2 ± 2.1 kg/m2) were scanned using a Kinect-based 3D scanner. A custom AFO was designed and produced for each patient using a fiberglass-reinforced polyamide through selective laser sintering. To assess kinematics, skin markers were placed on relevant bony landmarks according to a validated protocol. Each patient was instructed to walk at a self-selected comfortable speed under three conditions: wearing the custom AFO, wearing an off-the-shelf orthosis (Codivilla spring), and without any AFO (shod condition). Muscle activation in the tibialis anterior, gastrocnemius, rectus femoris and biceps femoris muscles in both legs was recorded using wireless sEMG sensors. The comfort and of each AFO was evaluated using a Visual Analogue Scale.

RESULTS

The custom AFO resulted in significant increase of stride length and walking speed compared to the shod condition. Except for the hip joint, which exhibited greater maximum flexion and reduced range of motion, the kinematic parameters of all other joints were similar to those observed in a healthy control population. Furthermore, the custom AFO received significantly higher comfort scores compared to the Codivilla spring.

SIGNIFICANCE

This study has provided evidence supporting the effectiveness of custom orthotic solutions in restoring lower limb kinematics and improving the perceived comfort in foot drop patients compared to off-the-shelf solutions.

A novel apparatus to assess the mechanical properties of Ankle-Foot Orthoses: Stiffness analysis of the Codivilla spring

Ankle-Foot Orthoses (AFOs) are the most common devices prescribed to support the ankle and restore a quasi-normal gait pattern in drop-foot patients. AFO stiffness is possibly the main mechanical property affecting foot and ankle biomechanics. A variety of methods to evaluate this property have been reported, however no standard procedure has been validated and widely used. This study is reporting the repeatability of a novel apparatus to measure AFO stiffness in ideal frictionless conditions. The apparatus is based on a servo-hydraulic testing machine and allows to apply a displacement-controlled rotation of the AFO shell, simulating the physiological ankle dorsi/plantarflexion movement. The repeatability of the apparatus in measuring AFO stiffness in dorsiflexion and plantarflexion was assessed intra- and inter-session in a sample of standard polypropylene AFOs of different sizes (Codivilla spring). The repeatability of the apparatus in measuring the AFO stiffness was high. The Intra- and Inter-session Coefficient of Variation ranged between 0.02 ÷ 1.3 % and 1.3 ÷ 5 %, respectively. The Intra Class Correlation Coefficient ranged between 0.999 ÷ 1 intra- and 0.993 ÷ 0.997 inter-session. AFOs stiffness was observed to increase with the AFO size. The setup is easy to replicate and can be implemented with any torsion-controlled servo-hydraulic testing machine and has resulted simple to use and flexible enough to adapt to AFOs with different sizes. The frictionless contacts characterizing the apparatus make it possible to measure the ideal AFO stiffness by excluding the effect of the fixation methods to the leg and help to improve the repeatability of measurements.

Case report - coronary vasospasm in transplanted heart: a puzzling phenomenon

Background

Coronary artery spasm (CAS) is an underdiagnosed disease especially in heart transplant patients, and in those patients the etiology and pathophysiology remain largely unknown, although it has been associated with cardiac allograft vasculopathy or graft rejection.

Case presentation

We report the case of a heart-transplant patient whose cardiac graft experienced two coronary vasospasms: the first before transplantation, and the other at one-month of a postoperative course complicated by primary graft failure.

Conclusion

Our case illustrates that a transplanted heart predisposed with coronary vasospasm may suffer from early relapse in the recipient despite of complete post-surgical autonomic denervation. Exacerbated endothelial dysfunction of the donor heart after transplant, with the addition of systemic factors in the recipient may be involved in the genesis of this puzzling phenomenon.

Neutron scattering observation of quasi-free rotations of water confined in carbon nanotubes

The translational and orientational dynamics of water in carbon nanotubes has been studied by quasi-elastic neutron scattering from 300 down to 10 K. Results show that, reducing temperature below 200 K, part of this water behaves as a quasi-free rotor, that is, the orientational energy of such molecules becomes comparable to the rotational energy of water in the gas phase. This novel and unique dynamic behavior is related to the appearance of water molecules characterized by a coordination number of about two, which is promoted by sub-nanometer axial confinement. This peculiar molecular arrangement allows water to show an active rotational dynamics even at temperatures as low as 10 K. The translational mobility shows a behavior compatible with the rotational one.