Old meets new technology in KAFO design
Jarrod Cahir, one of LOC’s senior orthotists, shares a recent case study that highlights the challenges of KAFO design and manufacturing, and the improvements that a modern KAFO can make to gait and strength.
Recently we had a client attend London Orthotic Consultancy’s Kingston clinic for an assessment of her lower limbs, following her polio diagnosis as a child in Kuwait. This affected the development of her left leg, leading to significantly reduced strength through the hips, knees and ankles, as well as stunting the growth of the foot and limb length. It also meant that she had developed an over reliance on the right leg to compensate and this leg had also become weakened over time. She reported that she needed to hold on to her knee, bent over whilst walking, in order to stabilise her leg with the current brace. On presentation to the clinic she was sitting in a wheelchair, having not walked in over two years, due to deconditioning and the state of her current Knee Ankle Foot Orthosis, or KAFO.
Over the years, orthotic designs and technology have changed dramatically; from the “Forrest Gump style” steel upright callipers - used to hold the leg straight - to modern microprocessor controlled, lightweight carbon fibre devices that lock and unlock during phases of the gait cycle to enable improved biomechanics of gait.
Following an in-depth assessment, which evaluated muscular strength and measured discrepancies between the limbs, various types of orthoses were discussed. We needed to consider what the client was accustomed to as a long time KAFO user, as well as set reasonable goals based on her current clinical presentation. We also needed to evaluate the practicalities of living in Kuwait and our ability to troubleshoot modern technology over a geographical distance. Issues arose throughout this appointment in terms of overcoming a significant language barrier and ensuring effective communication. Nonetheless, a plaster of paris cast was taken of the limb, to ensure the bespoke KAFO could be manufactured.
Above: The patient's old KAFO
Due to the patients’ long history of use, she was most comfortable with keeping the design as simple and similar to her old orthosis as possible. This meant the use of an ischial seat for weight bearing at the top of the device, connected to steel uprights with a calf band that clipped into the outside of the shoes to enable some ankle joint movement. The left shoe was raised to align the pelvis and accommodate for the leg length discrepancy, whilst incorporating a knee joint that remained locked when weightbearing but could be unlocked to enable flexion for sitting. The main difference was the incorporation of carbon fibre around the calf section and thigh, to reduce the overall weight of the orthosis, whilst increasing strength and durability. We also recommended a second brace be manufactured for the right knee, due to effects of deconditioning, however the client felt that this leg would be ok and that her main priority was the left.
A plastic trial fitting took place, to assess the fit prior to carbon fibre manufacture. Modifications were made to increase comfort and congruency of the fit, prior to definitive KAFO fabrication, as it is difficult to modify the carbon fibre once the shape has been finalised.
At the definitive fitting, a final measurement to adjust the height of the shoes was necessary to pull together measurements in order to accommodate the leg length discrepancy. Adjustments to trimlines took place to facilitate greater comfort and accommodate patient requests. The client also requested a different locking mechanism, that we could accommodate, incorporating a pull cord rather than a lever mechanism.
Above: the patient's new KAFO manufactured by LOC
Following the fitting and alignment of the KAFO, our client was able to stand and transfer into her wheelchair and took steps for the first time in two years with the assistance of a walking frame. Further strength and conditioning input will be necessary to further improve gait pattern, and this could be expediated with increased orthotic support on the right side. However, we anticipate with the benefit of a well-fitting orthosis and the right motivation additional improvements will be possible.
Find out more about our full range of bespoke orthotics by visiting the LOC orthotics page.