Orthopedic Complications

Orthopedic complications are common in children with neuromuscular dysfunction of any etiology, and pediatric SCI is no exception. Orthopedic complications of SCI may include scoliosis, hip dysplasia, contractures, and fractures.

Scoliosis refers to an abnormal spinal curvature involving both vertebral rotation about the long axis of the spine as well as curvature in the coronal plane. Scoliosis is diagnosed once the coronal curvature is at least ten degrees (Murphy et al. 2015). The implications of scoliosis vary dramatically based on the degree of abnormality, with some patients being completely asymptomatic, and others being significantly affected by abnormal positioning, unequal weight-bearing in seated, and even restrictive lung disease related to rotation of the thoracic cage.

Hip dysplasia refers to a condition in which the components of the hip joint (one or both of the proximal femur and/or acetabulum) become abnormally shaped such that the joint can more easily slide apart. The degree of joint displacement, as measured by the amount of the femoral head not covered by the acetabulum (migration percentage), determines whether the joint is described as subluxed (partially displaced) or dislocated (completely displaced) (Miller et al. 2017). Neuromuscular hip dysplasia is distinct from congenital hip dysplasia (also called developmental dysplasia of the hip) in that the hips of those with neuromuscular hip dysplasia were normal at birth but become dysplastic over time. The pathophysiology underlying this is not well understood, though abnormal muscle tone and strength and a lack of typical weight-bearing through the joint likely all contribute to the development of hip dysplasia across pediatric neuromuscular disorders, including SCI.

Muscle and joint contractures (causing fixed limitations in range of motion) can occur for a number of different reasons.  In pediatric SCI, contractures are most likely related to immobility and increased muscle tone (spasticity), causing shortening of muscles, tendons, and peri-articular connective tissue.  Fractures may be more likely to occur in this population due to reduced BMD below the level of the injury (discussed elsewhere in this review).

Discussion

Scoliosis is a major potential complication of pediatric SCI. Estimates of the incidence of progressive scoliosis related to paralysis range from 46 to 98% (Mehta et al. 2004). A review of the studies presented here suggests that more precise estimates of the frequency of scoliosis in pediatric SCI can be made if one considers the age of the individual at the time of injury. This is perhaps best demonstrated in the observational study by Dearolf et al. (1990), where children were divided into two groups based on their age when they were injured: the preadolescent group and the skeletally mature group. In the preadolescent group, without treatment, 96.5% developed scoliosis. Spinal curves progressed rapidly (at a rate of 10.6 degrees per year on average), and degree of curvature was not related to the level or completeness of injury. Of the patients who underwent bracing, about half stabilized, and half still went on to need surgery (and it was noted that 2 of the 12 braced patients developed significant pressure sores with bracing). Overall, 33% of this group required spinal surgery to manage the degree of scoliosis, with the authors carefully noting that if individuals in this group who were within one year of reaching skeletal maturity at the time of injury were excluded from analysis, that number rose to approximately 60% requiring surgical management. In contrast, only 48% of individuals who were skeletally mature at the time of injury had scoliosis without treatment. Curve progression was much slower (5.4 degrees per year) and only 18% went on to require surgery. In any instance of very rapid progression (>15 degrees in 6 months), it is suggested that evaluation for syringomyelia be considered (Dearolf et al. 1990). Kulshrestha et al. (2020), Mulcahey et al. (2013) and Vogel et al. (2002c) also reported that age at time of injury appeared to be the most important predictor of progressive paralytic scoliosis amongst children with SCI.

Bracing for scoliosis in the setting of SCI was discussed in a number of studies. In their chart review of 123 patients, Mehta et al. (2004) found that those braced when curves were smaller (less than 20 degrees) were less likely to go on to require surgery, or at least were able to prolong the time to surgery. This raises an interesting question around early bracing, in contrast to conventional treatment protocols, which dictate that bracing should be considered for scoliotic curves between 20-40 degrees (Mehta et al. 2004). Dearolf et al. (1990) found bracing to be effective for a small number of preadolescent individuals with scoliosis, though the rationale for who was and who was not braced was not well described. In younger patients, delaying the need for surgery may be desirable, so as to avoid spinal instrumentation before skeletal maturity is reached. There is a limited role for bracing larger curves (>40 degrees) (Dearolf et al. 1990; Mehta et al. 2004) and older (skeletally mature) patients (Dearolf et al. 1990), as successful management of scoliosis is less likely in these cases. Two studies examined the impact of bracing with a thoracolumbosacral orthosis on function amongst children with SCI. Sison-Williamson et al. (2007) demonstrated that use of a thoracolumbosacral orthosis resulted in reduced anterior/posterior and medial/lateral reach. Chafetz et al. (2007) demonstrated that, while some functions were not significantly impacted by thoracolumbosacral orthosis use, there was a significant impact on dressing and transfer time, and that patients preferred not to have the thoracolumbosacral orthosis on for certain tasks (such as reaching to the floor, dressing the lower body, and certain transfers).  These functional implications, coupled with the risk of pressure ulceration with thoracolumbosacral orthosis use (Dearolf et al. 1990) serve as a reminder that bracing should be considered as any other intervention, with considerations given to potential risks and benefits of treatment.

In comparison to scoliosis, information about other orthopedic complications of pediatric SCI is relatively limited. In one observational study, hip subluxation was documented in 40-50% of individuals who were injured before the age of 10 (Vogel et al. 2002c), with younger age at time of injury and longer duration of SCI found to significantly impact hip position. No information about rate of subluxation in older age categories was provided. A single interventional study assessed the impact of FES cycling, passive leg cycling, and surface stimulation without cycling on hip position (as measured by migration percentage) (Johnston, Betz, et al. 2009). None of the interventions were found to have an impact on hip subluxation at six months, though it could certainly be argued that the follow-up interval would be too short to observe a significant effect. Information regarding contracture and fractures in SCI was similarly limited.  Vogel et al. (2002c) observed ankle contractures in 16% of their sample of 216 individuals with chronic pediatric SCI, while elbow contractures were documented in 7.5% of the sample.  There were no associations between ankle fractures and any of the study variables, though elbow fractures were significantly associated with tetraplegia and lower American Spinal Injury Association motor scores, and Functional Independence Measure total and motor scores. Vogel et al. (2002c) also documented 45 pathologic fractures in 35 individuals with pediatric SCI (representing fracture(s) in 16% of the overall sample). Fractures were significantly associated with older age at the time of the study, longer duration of SCI, and cervical level injury. BMD amongst individuals with pediatric SCI was found by Moynahan et al. (1996) to be reduced by 56-65% as compared to peer controls, with greater reductions noted in those with a documented history of fracture.

Conclusion

Orthopedic complications of pediatric SCI are common. The risk of scoliosis requiring intervention is particularly high amongst those who experienced their injury at least one year prior to reaching skeletal maturity. While bracing with thoracolumbosacral orthosis does have some negative implications for function and skin health, bracing may delay or eliminate the need for invasive spine surgery, particularly if it is used before curves are overly large (certainly before 40 degrees, with some literature suggesting it could be instituted at less than 20 degrees) and while individuals are still skeletally immature. Hip subluxation is also relatively frequent, again with rates appearing to be higher amongst those who are injured at a younger age. Very little is known about effective rehabilitation-based intervention to slow the progression of hip subluxation. Contractures and fractures also occur at significant rates in this population, but there is no available literature regarding interventional strategies to reduce their incidence.