Elsevier

Bone

Volume 117, December 2018, Pages 1-5
Bone

Full Length Article
Trabecular bone score in adults with cerebral palsy

https://doi.org/10.1016/j.bone.2018.09.001Get rights and content

Highlights

  • Low trabecular bone score is common in young adults with cerebral palsy

  • Trabecular bone score is higher in ambulatory adults than non-ambulatory adults

  • Trabecular bone score is associated with bone mineral density, body mass index and appendicular lean mass

  • These relationships provide insight into bone fragility in cerebral palsy and muscle-bone interactions

Abstract

Context

Bone fragility in cerebral palsy (CP) is secondary to a complex interplay of functional, hormonal, and nutritional factors that affect bone remodelling. A greater understanding of bone microarchitectural changes seen in CP should assist therapeutic decision making.

Objective

To examine the relationship between trabecular bone score (TBS), BMD and fractures in adults with CP; the influence of clinical factors and body composition on bone microarchitecture were explored.

Design

Retrospective cross-sectional study.

Setting and Participants

43 adults (25 male) with CP of median age 25 years (interquartile range 21.4–33.9) who had evaluable dual-energy X-ray absorptiometry imaging of the lumbar spine from a single tertiary hospital between 2005-March 2018.

Results

24/43 (55.8%) of patients had TBS values indicating intermediate or high risk of fracture (<1.31). TBS correlated with areal BMD at the lumbar spine, femoral neck and total body. TBS was significantly associated with arm and leg lean mass, with adjustment for age, gender and height (adjusted R2 = 0.18, p = 0.042 for arm lean mass; adjusted R2 = 0.19, p = 0.036 for leg lean mass). There was no difference in TBS when patients were grouped by fracture status, anticonvulsant use, gonadal status or use of PEG feeding. TBS was lower in non-ambulatory patients compared with ambulatory patients (1.28 vs 1.37, p = 0.019).

Conclusions

Abnormal bone microarchitecture, as measured by TBS, was seen in >50% of young adults with CP. TBS correlated with both areal BMD and appendicular lean mass. Maintaining muscle function is likely to be important for bone health in young adults with CP and needs to be confirmed in further studies.

Introduction

The insult to the brain in cerebral palsy (CP) can occur during the prenatal, perinatal or postnatal period and is non-progressive. However, the resulting motor impairment progresses significantly over time. Up to 75% of individuals lose their ability to mobilise [1] and many become dependent on assistive devices [2] as they progress to adulthood. As life expectancy continues to improve in CP [3], preserving bone and muscle health to maintain mobility and independence is critical. However, assessment and maintenance of musculoskeletal health in CP is limited by function, joint contractures, scoliosis, and cognitive impairment.

Bone mineral density (BMD) as measured by dual X-ray absorptiometry (DXA) is widely available and used as the main surrogate of bone strength. The diagnosis of osteoporosis is based on either BMD criteria or the presence of minimal trauma fracture. Bone strength, however, is determined not only by bone density but other factors such as bone geometry, bone microarchitecture, bone turnover and bone mineralisation [4,5]. Using high-resolution MRI, Modlesky et al. have shown abnormal microarchitecture in the distal femur of non-ambulatory children with CP [6,7]. Trabecular number and thickness were reduced while trabecular separation was increased in children with CP compared with normal controls. The deficits in bone microarchitecture were more marked the greater the distance from the growth plate. The changes in cortical bone that have been demonstrated include a reduction in cortical thickness and cross-sectional area [8]. However, cortical volumetric bone density as measured by peripheral quantitative computed tomography (pQCT) is not different from typically developing children [9]. The smaller bones found in children with CP may account for these findings. In adults with CP, using thoracoabdominal CT scans, trabecular and cortical bone density were found to be reduced compared to age, sex and BMI matched controls [10].

Advanced imaging modalities such as high-resolution MRI and high-resolution pQCT are usually only found in research institutions and these measurements are susceptible to significant motion artefact. The trabecular bone score (TBS) was developed to estimate trabecular microstructure from a 2-dimensional lumbar spine (LS) DXA image. TBS is a textural index that examines pixel grey level variations in the LS image without the need for further imaging [11]. Low TBS is associated with hip fracture in postmenopausal women and men aged >50 years and can be complementary to the FRAX risk assessment tool [12,13].

To date, no studies have investigated the use of TBS in CP. This study aimed to evaluate whether TBS can provide further insights into bone microarchitecture in CP and its use in the clinical setting. To do this, the correlation between TBS and areal measures of spinal, femoral neck and total body BMD and body composition in young adults with CP was determined. The relationships of TBS with fractures and clinical factors relating to function, nutrition and endocrine status were also explored.

Section snippets

Subjects

A retrospective cross-sectional cohort study of 43 consecutive adults with CP who had DXA imaging of the lumbar spine at a single tertiary hospital from 2006-March 2018 was analysed. Medical indications for DXA imaging included suspected low BMD in the setting of immobility, fracture, anticonvulsant use and hypogonadism. The study was approved by the institutional ethics committee (Monash Health HREC).

Data collection and clinical measures

GMFCS grades the severity of gross motor function impairments based on the ability to mobilise

Results

The clinical characteristics of patients are summarised in Table 1. The majority had severe functional limitations with a GMFCS of IV or V, and nearly half required anticonvulsant therapy. Lumbar spine, total body and femoral neck BMD were obtained in 43, 35 and 30 patients respectively. Of the 43 patients, 22 (51.2%) had low BMD (Z score ≤ −2) at the lumbar spine and 12/30 (40%) had low BMD at the femoral neck. 16 (37.2%) of 43 CP adults had a TBS of 1.23–1.31, regarded as having an

Discussion

TBS is a surrogate measure of trabecular architecture and has been shown in ex vivo studies to correlate with trabecular number, connectivity, thickness and separation [18,19]. This is the first study to investigate TBS in adults with CP. We found over 50% of our cohort had an intermediate or high risk TBS, supporting the notion that abnormal bone microarchitecture in CP contributes to bone fragility. Our findings are consistent with previous MRI studies showing trabecular changes in

Grants

This research is supported by a Cerebral Palsy Alliance Research Foundation Grant. AT is supported by a Research Training Program scholarship from the Australian Government. FM is supported by an Endocrine Society of Australia Ken Wynne Post-Doctoral Grant. PW is supported by an NHMRC Early Career Fellowship. Hudson Institute is supported by the Victorian Government's Operational Infrastructure Support program.

Disclosure statement

The authors have nothing to disclose.

References (36)

  • C.D. Rubin

    Emerging concepts in osteoporosis and bone strength

    Curr. Med. Res. Opin.

    (2005 Jul)
  • C.M. Modlesky et al.

    Underdeveloped trabecular bone microarchitecture is detected in children with cerebral palsy using high-resolution magnetic resonance imaging

    Osteoporos. Int.

    (2008 Feb)
  • C.M. Modlesky et al.

    Underdevelopment of trabecular bone microarchitecture in the distal femur of nonambulatory children with cerebral palsy becomes more pronounced with distance from the growth plate

    Osteoporosis International

    (2015 Feb)
  • T. Al Wren et al.

    Bone density and size in ambulatory children with cerebral palsy

    Dev. Med. Child Neurol.

    (2011 Feb)
  • B.C. Silva et al.

    Trabecular bone score: a noninvasive analytical method based upon the DXA image

    J. Bone Miner. Res.

    (2014 Mar)
  • E.V. McCloskey et al.

    A meta-analysis of trabecular bone score in fracture risk prediction and its relationship to FRAX

    J. Bone Miner. Res.

    (2016 May)
  • E.V. McCloskey et al.

    Adjusting fracture probability by trabecular bone score

    Calcif. Tissue Int.

    (2015 Jun)
  • R. Palisano et al.

    Development and reliability of a system to classify gross motor function in children with cerebral palsy

    Dev. Med. Child Neurol.

    (1997 Apr)
  • Cited by (6)

    • Collagen-binding peptide reverses bone loss in a mouse model of cerebral palsy based on clinical databases

      2021, Annals of Physical and Rehabilitation Medicine
      Citation Excerpt :

      Non-ambulatory individuals with CP exhibit abnormal bone change owing to limited mechanical loading showing profound underdevelopment of trabecular microarchitecture [32]. Furthermore, chronic limitations in physical mobility aggravate abnormal symptoms over time, thereby resulting in atypical fractures [33]. Therefore, we expected evidence of skeletal bone loss in patients with CP in this study because these patterns were recently demonstrated [3,34].

    • Incidence of osteoarthritis, osteoporosis and inflammatory musculoskeletal diseases in adults with cerebral palsy: A population-based cohort study

      2019, Bone
      Citation Excerpt :

      Peak bone mass is established through childhood to early adulthood [6] and clinically significant osteopenia appears to be common in children and adolescents with CP [7]. A number of small studies have indicated abnormal bone microarchitecture in adults with cerebral palsy [8–10] and a recent systematic review found evidence to suggest this is also present in ambulatory people with CP [11]. Moreover, there is recent cross-sectional evidence that adults with CP have higher prevalence of fractures as compared to adults without CP, even after adjusting for osteoporosis [12].

    • Pubertal abnormalities in adolescents with chronic disease

      2019, Best Practice and Research: Clinical Endocrinology and Metabolism
      Citation Excerpt :

      Despite advancement of modern therapies for paediatric chronic diseases, abnormalities in puberty are still frequently encountered [Table 1]. Recent recognition of difficulty in maintaining adult sex hormone levels in some young people with neuromuscular disorders and cerebral palsy has further highlighted a need for vigilance with long term care [1–3]. Abnormalities of puberty in chronic disease states may present as:

    • Causes and prevention options for sarcopenia in children

      2022, Rossiyskiy Vestnik Perinatologii i Pediatrii
    View full text