Hip-Knee-Ankle-Foot Orthosis in SCI
Intensive ambulatory training with KAFOs for low thoracic SCI requires a large amount of determination and motivation from the patients (Senthilvelkumar et al. 2023). Patients can usually walk short distances, at slow average velocities and greatly increased energy expenditure (Senthilvelkumar et al. 2023). Despite these challenges, walking is beneficial for them due to many physiological and psychological benefits (Senthilvelkumar et al. 2023).
Unlike the other orthotic devices (locked stance-KAFO, walkabout orthoses, reciprocating gait orthosis) for persons with low thoracic SCI, the polypropylene solid AFO with aluminum uprights is a relatively lightweight orthosis, as bilateral KAFOs weigh approximately 3 kgs (6.5 lbs.) (Senthilvelkumar et al. 2023). Though ambulation with knees locked in full extension increases the energy cost, it provides safety as the positive drop lock enables the persons to lock and unlock the knees as needed during standing, walking, and sitting on a chair (Senthilvelkumar et al. 2023). Additionally, polypropylene KAFO can be worn underneath clothes and is cosmetically more acceptable than other devices (Senthilvelkumar et al. 2023).
Few people use orthotic walking as the primary mode of walking (Senthilvelkumar et al. 2023) as there are challenges such as the functional use of hands, fear of falls, difficulty negotiating steps and uneven terrain, difficulty donning and doffing orthosis, the appearance, and bulkiness of the orthoses, as well as the need for substantial energy expenditure (3–9 times that of those without SCI), which leads to early fatigue (Senthilvelkumar et al. 2023). Because the legs are paralyzed, the primary contributors to walking are the upper extremity and trunk muscles, so selective strengthening of the trunk and upper extremity muscles improves gait performance and postpones fatigue and shoulder pain (Baniasad et al. 2018; Senthilvelkumar et al. 2023). Under these circumstances, patients who wish to ambulate with KAFOs should be given precise information regarding the advantages and disadvantages of orthotic ambulation rather than an adulated impression (Senthilvelkumar et al. 2023).
Discussion
Exploring the maximum walking potential of people with SCI through restorative or compensatory gait training programs is common. One of the reasons why is that most of the barriers to community reintegration are related to the wheelchair inaccessibility of homes, public buildings, and transportation (Senthilvelkumar et al. 2023).
A large case series by Senthilvelkumar et al. (2023) included 430 patients with motor complete (AIS A and B) and low thoracic SCI who were trained to walk independently using KAFOs and elbow crutches for two hours per day, six days a week. After 12 weeks of training, 84.9% (n = 365) of people achieved walking using orthoses and walking aids either with a walker (WISCI II level 9, n = 105) or elbow crutches (WISCI II level 12, n = 260) (Senthilvelkumar et al. 2023). Additionally, younger adults (<30 years) with traumatic SCI and an injury level of T10 and below could perform better than others with orthotic gait training (Senthilvelkumar et al. 2023). This method of walking requires high energy and the risk of falls is high, so the selection of the ideal candidate is crucial (Senthilvelkumar et al. 2023).
Literature suggests that a walking speed of 0.59 m/s (35.4 m/min) is essential for independent and safe community walking following SCI (van Silfhout et al. 2017). Participants in Senthilvelkumar et al. (2023) showed an average speed of 0.297 m/s (only half of the expected walking speed for successful community walking). However, these values were taken at the time of discharge, and walking velocity generally improves over time.
Various designs of sliding medial linkages have been used within KAFOs to assist standing and walking in patients with SCI, including the Moorong (sliding-type medial hip joint) and the Primewalk (sliding-type medial hip joint) (Seyyedzadeh et al. 2021). A new type of KAFO with a medial linkage mechanism has been developed by Bani et al. (2015). This type of mechanism incorporates two gears that enable the extension of one limb to provide flexion to the contralateral limb and vice versa; it is also sensitive to pelvic motion, enabling the user to activate hip flexion and extension (Seyyedzadeh et al. 2021). In a prospective controlled trial, three patients with low thoracic and incomplete SCI underwent two weeks of gait training (trunk, upper-limb and lower-limb stretching, standing and walking) with these two types of KAFO. Using the KAFO with the medial linkage mechanism, as compared to the SM, was associated with reciprocating gait motion showed improvements in walking speed (10MWT), walking distance (6MWT), and reduced the physiological cost index, but not donning nor doffing (Seyyedzadeh et al. 2021). These results should be taken with caution as the sample size was small, and neither statistical analyses nor the order of interventions were mentioned.
Conclusions
There is level 4 evidence (from 1 case series: Senthilvelkumar et al. 2023) that patients with motor complete low thoracic SCI using KAFOs and elbow crutches could achieve walking (although not at speeds sufficient for community ambulation).
