Prophylactic treatment of osteoporosis after SCI: promising research, but not yet indicated

Characteristics Associated with Bone Loss after Spinal Cord Injury: Implications for Hip Region Vulnerability

BACKGRUOUND

In individuals with spinal cord injury (SCI), bone loss progresses rapidly to the area below the level of injury, leading to an increased risk of fracture. However, there are limited data regarding SCI-relevant characteristics for bone loss and the degree of bone loss in individuals with SCI compared with that in non-SCI community-dwelling adults.

METHODS

Data from men with SCI who underwent dual-energy X-ray absorptiometry at the National Rehabilitation Center (2008 to 2020) between 12 and 36 months after injury were collected and analyzed. Community-dwelling men were matched 1:1 for age, height, and weight as the control group, using data from the Korea National Health and Nutrition Examination Survey (KNHANES, 2008 to 2011).

RESULTS

A comparison of the SCI and the matched control group revealed significantly lower hip region T-scores in the SCI group, whereas the lumbar spine T-score did not differ between groups. Among the 113 men with SCI, the paraplegia group exhibited significantly higher Z-scores of the hip region than the tetraplegia group. Participants with motor-incomplete SCI showed relatively preserved Z-scores of the hip region compared to those of the lumbar region. Moreover, in participants with SCI, the percentage of skeletal muscle displayed a moderate positive correlation with femoral neck Z-scores.

CONCLUSION

Men with SCI exhibited significantly lower bone mineral density of the hip region than community-dwelling men. Paraplegia rather than tetraplegia, and motor incompleteness rather than motor completeness were protective factors in the hip region. Caution for loss of skeletal muscle mass or increased adiposity is also required.

Regulation of Bone by Mechanical Loading, Sex Hormones, and Nerves: Integration of Such Regulatory Complexity and Implications for Bone Loss during Space Flight and Post-Menopausal Osteoporosis

During evolution, the development of bone was critical for many species to thrive and function in the boundary conditions of Earth. Furthermore, bone also became a storehouse for calcium that could be mobilized for reproductive purposes in mammals and other species. The critical nature of bone for both function and reproductive needs during evolution in the context of the boundary conditions of Earth has led to complex regulatory mechanisms that require integration for optimization of this tissue across the lifespan. Three important regulatory variables include mechanical loading, sex hormones, and innervation/neuroregulation. The importance of mechanical loading has been the target of much research as bone appears to subscribe to the "use it or lose it" paradigm. Furthermore, because of the importance of post-menopausal osteoporosis in the risk for fractures and loss of function, this aspect of bone regulation has also focused research on sex differences in bone regulation. The advent of space flight and exposure to microgravity has also led to renewed interest in this unique environment, which could not have been anticipated by evolution, to expose new insights into bone regulation. Finally, a body of evidence has also emerged indicating that the neuroregulation of bone is also central to maintaining function. However, there is still more that is needed to understand regarding how such variables are integrated across the lifespan to maintain function, particularly in a species that walks upright. This review will attempt to discuss these regulatory elements for bone integrity and propose how further study is needed to delineate the details to better understand how to improve treatments for those at risk for loss of bone integrity, such as in the post-menopausal state or during prolonged space flight.

Parasport: Effects on Musculoskeletal Function and Injury Patterns

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Sports participation can improve gait, muscle strength, and functional abilities in patients with a wide variety of disabilities. Para athletes are also at substantial risk for injury during sports participation.

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Ambulant athletes with cerebral palsy are at risk for soft-tissue injuries about the knee as well as foot and ankle injuries. Wheelchair athletes are at risk for osteoporotic fractures and shoulder girdle injuries. Limb-deficient athletes are prone to low back pain and overuse injuries of the contralateral extremity.

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Para athletes are vulnerable to abuse during sports participation, and physicians should promptly report any possible abuse or mistreatment.

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Orthopaedic surgeons should understand disability and sport-specific risk factors for injury in para athletes in order to initiate early management and injury prevention protocols.

S1 Guidelines on Bone Impairment in Spinal Cord Injury

During the acute and chronic phase of spinal cord injury (SCI) bone turnover and structure are affected. Bone mineral density of lower limbs is decreased up to 28%-50% below that of age-matched peers at 12-18 mo post injury. Coexisting secondary etiologies of osteoporosis may be present, and during ageing additional loss of bone occurs. All these compose a complex canvas of bone impairment after spinal cord injury and make the therapeutical approach challenging. The risk of fragility fractures is increased after the 2nd decade post SCI affecting the functionality and quality of life of individuals with SCI. Diagnostic flaws, lack of a ranking system to categorize the degree of bone impairment similar to the one of World Health Organization, and evidence-based clinical guidelines for management in SCI requires interdisciplinary cooperation and appropriate planning of future research and interventions. Spinal Cord Section of Hellenic Society of Physical Rehabilitation Medicine convened an expert panel working group on bone and spinal cord injury at the Pan-Hellenic Congress 2018 of PRM in Athens Greece, to establish an evidence-based position statement for bone loss in individuals with SCI of traumatic or non-traumatic etiology. This was reviewed by an International Task Force and used to create S1 Guidelines. This first version S1 guideline will work towards to provide help with prophylactic basic osteoporosis therapy diagnostic and therapeutic decisions in acute and chronic phase and rehabilitation countermeasures against osteoporosis related with spinal cord injury.

Delayed Systemic Treatment with Cannabinoid Receptor 2 Agonist Mitigates Spinal Cord Injury-Induced Osteoporosis More Than Acute Treatment Directly after Injury

Nearly all persons with spinal cord injury (SCI) will develop osteoporosis following injury, and further, up to 50% of all persons with SCI will sustain a fracture during their lives. The unique mechanisms driving osteoporosis following SCI remain unknown. The cannabinoid system modulation of bone metabolism through cannabinoid 1/2 (CB1/2) has been of increasing interest for the preservation of bone mass and density in models of osteoporosis. Using a thoracic vertebral level 8 (T8) complete transection in a mouse model, we performed daily treatment with a selective CB2 receptor agonist, HU308, compared with SCI-vehicle-treated and naïve control animals either immediately after injury for 40 days, or in a delayed paradigm, following 3 months after injury. The goal was to prevent or potentially reverse SCI-induced osteoporosis. In the acute phase, administration of the CB2 agonist was not able to preserve the rapid loss of cancellous bone. In the delayed-treatment paradigm, in cortical bone, HU308 increased cortical-area to total-area ratio and periosteal perimeter in the femur, and improved bone density in the distal femur and proximal tibia. Further, we report changes to the metaphyseal periosteum with increased presence of adipocyte and fat mass in the periosteum of SCI animals, which was not present in naïve animals. The layer of fat increased markedly in HU308-treated animals compared with SCI-vehicle-treated animals. Overall, these data show that CB2 agonism targets a number of cell types that can influence overall bone quality.

A pulse survey: assessment and management of bone loss in spinal cord injury

STUDY DESIGN

An online survey OBJECTIVES: To describe current clinical practices regarding osteoporosis assessment and management in people with Spinal Cord Injury (SCI) and compare them to recommended diagnostic tests and interventions.

SETTING

An international collaboration surveying professionals working in SCI Medicine.

METHODS

Online cross-sectional survey regarding clinical practice trends in the assessment and treatment of osteoporosis in people with SCI. Assessment of whether discrete professional characteristics influenced practices and if those practices were consistent with recommendations from professional organizations.

RESULTS

Eighty-two professionals working in SCI Medicine completed the survey. Respondents were equally likely to test for bone loss during the post-acute phase (between 4- and 18-months post injury) and after low impact fracture (41.46% and 42.68%, respectively) and more likely to test during the chronic phase (51.22%). The majority of respondents (n = 56, 70%) assessed bone density with DXA at the hip, and many (48.78%, n = 40) prescribed simultaneous mobilization, vitamin D and calcium to prevent bone loss in the acute, post-acute and chronic phases. A number of evaluations and interventions were inconsistent with best practice recommendations.

CONCLUSIONS

Given that reported practices for detection and treatment of osteoporosis in SCI are inconsistent and not data-driven, there is need for dissemination and adoption of existing clinical practice guidelines.

Spinal Cord Injury as a Model of Bone-Muscle Interactions: Therapeutic Implications From in vitro and in vivo Studies

Spinal cord injuries (SCIs) represent a variety of conditions related to the damage of the spinal cord with consequent musculoskeletal repercussions. The bone and muscle tissues share several catabolic pathways that lead to variable degrees of disability in SCI patients. In this review article, we provide a comprehensive characterization of the available treatment options targeting the skeleton and the bone in the setting of SCI. Among the pharmacological intervention, bisphosphonates, anti-sclerostin monoclonal antibodies, hydrogen sulfide, parathyroid hormone, and RANKL pathway inhibitors represent valuable options for treating bone alterations. Loss phenomena at the level of the muscle can be counteracted with testosterone, anabolic-androgenic steroids, and selective androgen receptor modulators. Exercise and physical therapy are valuable strategies to increase bone and muscle mass. Nutritional interventions could enhance SCI treatment, particularly in the setting of synergistic and multidisciplinary interventions, but there are no specific guidelines available to date. The development of multidisciplinary recommendations is required for a proper clinical management of SCI patients.