Is There A Better Way To Prevent Fractures In Patients With Cerebral Palsy?

Jayson N. Atves, DPM, CO, AACFAS coauthored this DPM Blog.

It may come as no surprise that patients with cerebral palsy, whether they are young or old, have a sustained predilection for fractures throughout their lifetime with minimal to no precipitating trauma. This knowledge, however, has done little to prevent fracture and refracture in this population, especially when it comes to the lower extremities.

All too often we bear witness to fractures in these patients in rather predictable patterns and locations. Perhaps unremarkably, given this insight, we often appreciate identical fractures in one limb just a short time after healing an inciting fracture on the opposite limb. However, regardless of timing or laterality, the manifestation of fracture obviously places quite an additional demand on not only the cerebral palsy patient and physician, but on a support system that may already necessitate personalized care on an assortment of levels. Simply put, the predilection for fracture in the cerebral palsy patient effectively stresses the patient and family as well as the health care system as a whole.

That said, there must be a better way to prevent such injuries in these patients. After all, we can see the proverbial writing on the wall when these patients present with a pathological deformity and fragile bone stock, either of which places them at a much higher risk index for fracture. Yet, despite our best efforts to supportively brace or medicinally treat, time and time again we see fractures in the exact locations we had originally feared these patients had injured.

Why People With Cerebral Palsy Have A Predilection For Fractures

Primarily defined as a permanent disorder in the development of posture and movement, cerebral palsy may present as a wide spectrum of musculoskeletal impairments. Ultimately, this may result in a marked imbalance between antagonistic muscle groups that manifests in joint contracture and mal-joint positioning, be it during ambulation or even while at rest. Additionally, the aging of such patients may ultimately produce a decreasingly ambulatory individual, which only adds to the possibility of decreased bone integrity.

As evidenced in a 15-year Swedish population cohort of over 500 patients, children with more severely involved cerebral palsy had a higher risk of fracture in comparison to the typical developing child.¹ This is unsurprising given that cerebral palsy places undue stresses on malpositioned extremities and can have deleterious effects on bone quality. Given the more severe forms and extents of increasingly global involvement that cerebral palsy produces, it can become difficult to control the deformity and the resultant forces borne by these patients as well as the decreasing density of their bone.

In fact, Mergler and colleagues found that limited ambulation, feeding difficulties, previous fracture, anticonvulsant use and lower body fat mass were associated with low bone mineral density in patients with cerebral palsy.² Al Wren and coworkers found that children with cerebral palsy not only have less bone density within their tibias but that their tibias are smaller in size overall, regardless of the severity of involvement.³ More to the point, though, is that this “dual threat” of pathological bone and predisposed positioning for fracture is perhaps the most glaring fact that we see in these patients every time they enter the office.

However, even if one has access to bone mineral density measurement modalities such as a dual energy X-ray absorptiometry (DXA) scan, it is difficult to obtain clinically relevant measurements in this population given possible motion during scanning or joint contracture or indwelling hardware, all of which may hinder reliable DXA measurements. Additionally, research has found that measurements of bone mineral density in the lumbar spine do not accurately predict subsequent fracture risk in the long bones.⁴

A Closer Look At Fracture Treatment Options

The use of bisphosphonates has seen some promise, just as it has in the elder osteoporotic population. Pamidronate is a nitrogen-containing bisphosphonate that clinicians widely use to prevent bone loss and osteoporosis. For cerebral palsy, physicians have used pamidronate in intravenous fashion as a prophylactic and therapeutic agent in the aim of establishing more quality bone density.  

In their 2009 systematic review of the interventions for low bone mineral density in cerebral palsy children, Hough and colleagues found increases in bone mineral density in small but diverse cohorts of children with cerebral palsy with treatments of bisphosphonates.⁵ However, it was unclear whether the small sample sizes or variable responses to treatments accounted for the non-significant findings.

Bachrach and coworkers found that one-year intravenous pamidronate treatment lowered the rate of fractures and provided a protective effect against fractures after treatment ended with the effect lasting four years or greater for a majority of the patients.⁶

There remain no quality studies of the prophylactic use of supportive bracing or standing frames for use in controlling joint contracture and maintaining or increasing bone mineral density, respectively. Intuitively, the patient with spastic cerebral palsy needs supportive bracing at baseline in order to more adequately disperse aberrant pressures and forces within the lower extremities. However, there has yet to be an outcomes-based assessment of this kind of prophylaxis.

In Conclusion

It is well established that patients with cerebral palsy have an increased predilection for fractures, especially about the lower extremities. A biomechanical predisposition secondary to musculoskeletal tonicity and poor bone mineral density with progression from the sequelae of aging and decreasing ambulation place these patients at a much greater probability of fracture in what can only be described as pathological patterns. Despite this understanding, our current prophylaxis of fracture, especially refracture, in this population is underwhelming at best.  

We should make it our goal to prevent, not merely treat, fracture in this population of patients we know are greatly predisposed. A more refined relationship between supportive bracing, formalized therapy and prophylactic or therapeutic medical management seems to be the most promising approach.

However, the foot and ankle field offers specialized care for patients with cerebral palsy as it has been built upon biomechanical expertise. These patients require this attention to detail that other physicians may not be able or willing to provide. We can and must improve at proactively screening and addressing the abnormal stresses borne by these challenging patients. We must break the predisposition of abnormal stresses in abnormal bone if we have any hope of successfully preventing fractures.

Only with a thorough knowledge of these patients and their plight as well as a comprehensive understanding of the various facets of their predisposition and the applications available for correction can we properly establish a manner of true screening and prophylaxis for the patient with cerebral palsy.

Dr. Atves is a Fellow at the Pennsylvania Intensive Lower Extremity Fellowship at Premier Orthopaedic in Malvern, PA.

Dr. Miller is the Director of the Pennsylvania Intensive Lower Extremity Fellowship at Premier Orthopaedic in Malvern, PA.

References

1. Uddenfeldt Wort U, Nordmark E, Wagner P, Duppe H, Westbom L. Fractures in children with cerebral palsy: a total population study. Dev Med Child Neurol. 2013; 55(9):821-827.
2. Mergler S, Evenhuis HM, Boot AM, DeMan SA, Bindels-DeHeus KGCB, Huijbers WA, Penning C. Epidemiology of low bone mineral density and fractures in children with severe cerebral palsy: a systematic review. Dev Med Child Neurol. 2009; 51(10):773-778.
3. Al Wren T, Lee DC, Kay RM, Dorey FJ, Gilsanz V. Bone density and size in ambulatory children with cerebral palsy. Dev Med Child Neurol. 2010; 53(2):137-141.
4. Henderson RC. Bone density and other possible predictors of fracture risk in children and adolescents with spastic quadriplegia. Dev Med Child Neurol.  1997. 39(4):224–227.
5. Hough JP, Boyd RN, Keating JL. Systematic review of interventions for low bone mineral density in children with cerebral palsy. Pedeatrics. 2010; 125(3):e670-e678.
6. Bachrach S, Kecskeemethy HH, Harcke HT, Hossain J. Decreased fracture incidence after 1 year of pamidronate treatment in children with spastic quadriplegic cerebral palsy. Dev Med Child Neurol. 2010; 52(9):837-842.