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.

Postural stability and plantar pressure parameters in healthy subjects: variability, correlation analysis and differences under open and closed eye conditions.

Introduction: The "postural control system" acts through biomechanical strategies and functional neuromuscular adaptations to maintain body balance under static and dynamic conditions. Postural stability and body weight distribution can be affected by external sensory inputs, such as different visual stimuli. Little information is available about the influence of visual receptors on stabilometric and plantar pressure parameters. The aim of this study was to analyze variability, correlations, and changes in these parameters under open- (OE) and closed-eye (CE) conditions. Methods: A total of 31 stabilometric and plantar pressure parameters were acquired in 20 young and healthy adults during baropodometric examination performed in bipedal standing under both visual conditions. Variability of parameters was evaluated via the coefficient of variation, correlation analysis via Pearson's R2, and statistical differences via the Wilcoxon test. Results: High intra-subject repeatability was found for all plantar pressure parameters and CoP-speed (CV < 40%) under OE and CE conditions, while CoP-sway area (CoPsa) and length surface function (LSF) showed larger variability (CV > 50%). Mean and peak pressures at midfoot and total foot loads showed the least number of significant correlations with other parameters under both visual conditions, whereas the arch-index and rearfoot loads showed the largest number of significant correlations. The limb side significantly affected most plantar pressure parameters. A trend of larger LSF and lower CoPsa and mean and peak pressures at the right forefoot was found under the CE condition. Discussion: The present study provides a deeper insight into the associations between postural stability and foot load. Interesting postural adaptations, particularly with respect to different visual stimuli, the effect of the dominant side, and the specific role of the midfoot in balance control were highlighted.

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.

Functional and clinical evaluation at 5-year follow-up of a three-component prosthesis and osteochondral allograft transplantation for total ankle replacement.

BACKGROUND: Severe ankle arthritis is a life-limiting condition which often requires surgery. Ankle arthroplasty via artificial or "biological" reconstruction is a viable option in those patients who are not comfortable with arthrodesis. More functional studies are needed to compare the performance and outcomes of the two function-preserving arthroplasties. METHODS: In this study two groups of 10 patients affected by severe ankle arthritis were treated either with a 3-component ankle prosthesis or with bipolar fresh osteochondral allograft transplantation. Patients were evaluated pre-operatively and at 5-year follow-up. The American Orthopaedic Foot and Ankle Society score was used for clinical evaluation, and gait analysis for functional assessment. Activation pattern of lower limb muscles was obtained by surface electromyography (EMG). In each group, kinematic, kinetic, and EMG data were compared between pre-op and follow-up assessments, and also versus corresponding data from a 20 healthy subject control group. The median clinical score significantly increased between pre-op and follow-up from 53 to 74.5 in the transplantation and from 28.5 to 80 in the prosthesis group. Spatio-temporal parameters showed a statistically significant improvement in cadence and cycle time. Improvement of gait speed was also observed only in the prosthesis group. EMG patterns at follow-up were strongly correlated with the corresponding control data for both groups. Although no significant amelioration in the joints' range of motion was detected in either surgical procedure, preservation of the functional conditions at medium-term, along with significant improvement of the clinical score, may be considered a positive outcome for both techniques.

Multi-segment foot mobility in a hinged ankle-foot orthosis: the effect of rotation axis position.

Hinged ankle-foot orthoses are prescribed routinely for the treatment of ankle joint deficits, despite the conflicting outcomes and the little evidence on their functional efficacy. In particular, the axis of rotation of the hinge is positioned disregarding the physiological position and orientation. A multi-segment model was utilized to assess in vivo the effect of different positions for this axis on the kinematics of foot joints. A special custom-made hinged orthosis was manufactured via standard procedures for a young healthy volunteer. Four locations for the mechanical axis were obtained by a number of holes where two nuts and bolts were inserted to form the hinge: a standard position well above the malleoli, at the level of the medial malleolus, at the level of the lateral malleolus, and the physiological between the two malleoli. The shank and foot were instrumented with 15 reflective markers according to a standard protocol, and level walking was collected barefoot and with the orthosis in the four mechanical conditions. The spatio-temporal parameters observed in the physiological axis condition were the closest to normal barefoot walking. As expected, ankle joint rotation was limited to the sagittal plane. When the physiological axis was in place, rotations of the ankle out-of-sagittal planes, and of all other foot joints in the three anatomical planes, were found to be those most similar to the natural barefoot condition. These preliminary measures of intersegmental kinematics in a foot within an ankle-foot orthosis showed that only a physiological location for the ankle mechanical hinge can result in natural motion at the remaining joints and planes.

Functional evaluation of patients treated with osteochondral allograft transplantation for post-traumatic ankle arthritis: one year follow-up.

Severe post-traumatic ankle arthritis poses a reconstructive challenge in active patients. Whereas traditional surgical treatments, i.e. arthrodesis and arthroplasty, provide good pain relief, arthrodesis is associated to functional and psychological limitations, and arthroplasty is prone to failure in the active patient. More recently the use of bipolar fresh osteochondral allografts transplantation has been proposed as a promising alternative to the traditional treatments. Preliminary short- and long-term clinical outcomes for this procedure have been reported, but no functional evaluations have been performed to date. The clinical and functional outcomes of a series of 10 patients who underwent allograft transplantation at a mean follow-up of 14 months are reported. Clinical evaluation was performed with the AOFAS score, functional assessment by state-of-the-art gait analysis. The clinical score significantly improved from a median of 54 (range 12-65) pre-op to 76.5 (range 61-86) post-op (p=0.002). No significant changes were observed for the spatial-temporal parameters, but motion at the hip and knee joints during early stance, and the range of motion of the ankle joint in the frontal plane (control: 13.8°±2.9°; pre-op: 10.4°±3.1°, post-op: 12.9°±4.2°; p=0.02) showed significant improvements. EMG signals revealed a good recovery in activation of the biceps femoris. This study showed that osteochondral allograft transplantation improves gait patterns. Although re-evaluation at longer follow-ups is required, this technique may represent the right choice for patients who want to delay the need for more invasive joint reconstruction procedures.

Repeatability of a multi-segment foot protocol in adult subjects.

Despite the numerous protocols for multi-segment kinematic analysis of the foot, the literature is scarce regarding relevant measures of reliability. The aim of the present work was to assess the inter-trial, inter-session and inter-examiner variability of one of these protocols by an established method. The kinematics of the joints of the foot of two volunteers were analyzed by four examiners with different degrees of experience in three sessions, two-to-four weeks apart. In each session the data of five trials of level walking were collected and the rotations in the three anatomical planes between foot segments were calculated. The mean value over stance phase duration of the standard deviation of these rotations was calculated for groups of trials according to the statistical method as in Schwartz et al. [6]. For each rotation, the inter-examiner variability was larger than the inter-session, and the latter larger than the inter-trial. The inter-session variability was found in the same order of magnitude for standard lower limb protocols for the two expert examiners, but much higher for the inexperienced examiners.