Mason Stolycia

Research investigating ankle function during walking in a controlled ankle motion (CAM) boot has either placed markers on the outside of the boot or made major alterations to the structure of the CAM boot to uncover key landmarks. The aim of this study was to quantify joint kinematics and kinetics using “in-boot” skin markers whilst making only minimal structural alterations. Seventeen healthy participants walked at their preferred walking speed in two conditions: (1) in standard athletic trainers (ASICS patriot 8, ASICS Oceania Pty Ltd, USA), and (2) using a hard-cased CAM boot (Rebound® Air Walker, Össur, Iceland) fitted on the right foot. Kinematic measurements revealed that CAM boots restrict sagittal plane ankle range of motion to less than 5°, and to ∼3° in the frontal plane, which is a reduction of 85% and 73% compared to standard footwear, respectively (p < 0.001). This ankle restriction resulted in a reduction of ankle joint total limb work contribution from 38 ± 5% in normal footwear to 13 ± 4% in the CAM boot (p < 0.001). This study suggests that CAM boots do restrict the ankle joint’s ability to effectively perform work during walking, which leads to compensatory mechanisms at the ipsilateral and contralateral hip and knee joints. Our findings align with previous research that employed “on-boot” kinematic measurements, so we conclude that in-boot approaches do not offer any benefit to the researcher and instead, on-boot measurements are suitable.

Introduction Controlled ankle motion (CAM) boots are a below-knee orthotic device prescribed for the management of foot and ankle injuries to reduce ankle range of motion (RoM) and offload the foot and ankle whilst allowing continued ambulation during recovery. There is a lack of clarity within the current literature surrounding the biomechanical understanding and effectiveness of CAM boots. Aims To summarise the biomechanical effects of CAM boot wear as an orthotic for restricting ankle RoM and offloading the foot. Methods A systematic literature review was conducted in accordance with the PRISMA 2020 guidelines. All papers were independently screened by two authors for inclusion. Methodological quality was appraised using Joanna Briggs Critical Appraisal checklists. A narrative synthesis of all eligible papers was produced. Results Thirteen studies involving 197 participants (113 male and 84 female) were included. All studies were quasi-randomised and employed a within-study design, of which 12 studies included a control group and a range of CAM boots were investigated. CAM boots can be seen to restrict ankle RoM, however, neighboring joints such as the knee and hip do have kinetic and kinematic compensatory alterations. Plantar pressure of the forefoot is effectively redistributed to the hindfoot by CAM boots. Conclusion The compensatory mechanisms at the hip and knee joint during CAM boot wear could explain the secondary site pain often reported in patients, specifically at the ipsilateral knee and contralateral hip. Although CAM boots can be used to restrict ankle motion, this review has highlighted a lack of in-boot kinematic analyses during CAM boot use, where tracking markers are placed on the anatomical structure rather than on the boot, or through video fluoroscopy, urging the need for a more robust methodological approach to achieve this. There is a need for studies to assess the biomechanical alterations caused by CAM boots in populations living with foot and ankle pathologies. Future research, adopting a longitudinal study design, is required to fully understand the effectiveness of CAM boots for rehabilitation.

Hinged controlled ankle motion boots are used to incrementally increase ankle joint range of movement during rehabilitation following Achilles’ tendon rupture. This increased movement should induce mechanical stress on the tendon via cycles of stretching and shortening. However, research has yet to determine how this permitted range of movement influences tendon length change. Eight healthy individuals (age: 23 ± 2 y; stature = 1.70 ± 0.09 m; body mass = 67.7 ± 13.7 kg) walked at a self-selected speed on an instrumented, motorised treadmill in a hinged controlled ankle motion boot with three pre-established ankle ranges of movement: 0, 15, and 30°, which were all compared with walking in normal footwear. Kinematic and kinetic measurements were obtained using motion capture and the treadmill. Triceps surae mechanical characteristics, including Achilles’ tendon stretch, were obtained with B-mode ultrasonography. Achilles’ tendon stretch significantly (p < 0.001) increased as boot range of movement increased and was strongly correlated with measured ankle joint range of movement when the boot was set to a 15 or 30° range of movement (r ≥ 0.84, p ≤ 0.009). Increasing controlled ankle motion boot range of movement also increased ankle joint mechanical work done and total mechanical work done by the boot-wearing limb, which led to an increase in self-selected walking speed (all p < 0.001). These findings provide preliminary evidence that hinged controlled ankle motion boots have the capacity to provide a controlled mechanical stimulus to the Achilles’ tendon when range of movement is increased. This has possible clinical application for the early management of Achilles’ tendon rupture, potentially improving healing and functional outcomes if it can be translated into a patient population.

Background Controlled ankle motion (CAM) boots are often prescribed during the rehabilitation of lower limb injuries and pathologies to reduce foot and ankle movement and loading whilst allowing the patient to maintain normal daily function. Research question The aim of this study was to quantify the compensatory biomechanical mechanisms undergone by the ipsilateral hip and knee joints during walking. In addition, the compensatory mechanisms displayed by the contralateral limb were also considered. Methods Twelve healthy participants walked on an instrumented treadmill at their preferred walking speed. They underwent kinematic and kinetic analysis during four footwear conditions: normal shoes (NORM), a Malleo Immobil Air Walker on the right leg (OTTO), a Rebound® Air Walker on the right leg with (EVEN) and without (OSS) an Evenup Shoelift™ on the contralateral leg. Results CAM boot wear increased the relative joint contribution to total mechanical work from the ipsilateral hip and knee joints (p < 0.05), which was characterised by increased hip and knee abduction during the swing phase of the gait cycle. EVEN increased the absolute work done and relative contribution of the contralateral limb. CAM boot wear reduced walking speed (p < 0.05), which was partially compensated for during EVEN. Significance The increased hip abduction in the ipsilateral leg was likely caused by the increase in effective leg length and limb mass, which could lead to secondary site complications following prolonged CAM boot wear. Although prescribing an even-up walker partially mitigates these compensatory mechanisms, adverse effects to contralateral limb kinematics and kinetics (e.g., elevated knee joint work) should be considered.