Q1:  What happens to the bones in a person’s legs after spinal cord injury (SCI)?

A:  Shortly after an SCI occurs, because of the abrupt stopping of standing and walking and weight-bearing through the legs, there is a rapid breakdown of calcium stores located within bone tissue.  This breakdown of calcium occurs due to an increase of the cells within bone tissue that breakdown bone and a decrease in the cells within bone tissue that build bone.  This abnormal relationship between bone breakdown and bone building leads to a rapid decrease in bone mineral density (BMD) over first 2 years after SCI and continues at a slower rate over a lifetime. The BMD of a specific bone defines the quantity of bone mineral concentrated into a specific area or volume of bone tissue.  As the BMD value of a specific bone gets lower, the risk of fracture at that bone goes higher, and can result in the diagnosis of a disease known as Osteoporosis.  People with SCI are at high risk for osteoporosis and fractures that commonly occur at the “spongey” end regions of the bones around the hips and knees while performing routine activities of daily living.  Unlike the bone loss that occurs from regular aging, the pattern of bone loss in SCI is different because the skeleton above the SCI level remains mostly unaffected by the injury, while marked bone loss occurs in the regions below the SCI.

Q2:  Is bone health a priority for people living with SCI?

A:  Yes, healthy bones are a priority for people with SCI and are necessary to protect internal organ systems and allow for successful participation in weight-bearing activities that are known to have long-term health benefits.  Persons with SCI who have low BMD at the hip and knee regions are at high risk of a fracture when a low impact fall occurs from a wheelchair during a car transfer or when stretching too far during a physical therapy or exercise session.  A fracture in persons living with SCI can lead to other medical complications such as infection, delayed healing at the fracture site, pressure injuries, and deep vein blood clots.  These conditions may result in hospitalization, limited mobility in a wheelchair, and loss of independence to perform activities of daily living such as dressing and maintaining personal hygiene.

Q3:  How is BMD and bone health assessed?

A:  The BMD test most commonly performed is known as a dual-energy X-ray absorptiometry (DXA) study and should be used to assess BMD at the hip and knee regions in persons with SCI.   A DXA study is normally prescribed by a doctor and should be performed as soon as possible after SCI and repeated every 1-2 years to monitor change in BMD and determine if a patient has Osteoporosis and is at increased risk for fracture.  To further understand the risk for fracture in persons living with SCI, a doctor may prescribe blood tests to rule out other causes of osteoporosis such as kidney disease and hormonal imbalances as well as to understand the quantity of calcium and vitamin D in the body.  Calcium and vitamin D are vital nutrients necessary for maintaining healthy bones so it is important to understand if any deficiencies are present.  Persons with SCI should speak to their physicians about including these tests as part of their annual physical exam.

Q4:  Is calcium and vitamin D essential for bone health?

      A:  Yes, adequate calcium and vitamin D intake is essential to building and maintain strong bones.  In persons living with SCI, 7 out of 10 people with SCI do not get enough calcium and 1 out of every 3 people with SCI are vitamin D deficient.  How much calcium a person with SCI needs is based on their age-group, blood calcium levels, and their history of kidney stones.  A persons can get the correct amount of calcium from food and/or supplements, but it is better to get it from food.  Blood vitamin D levels should be obtained annually to determine if a person with SCI has sufficient levels.  Vitamin D can be produced by your body from sunlight exposure, but most people find it difficult to achieve an adequate blood vitamin D level from sunlight alone.  Persons with SCI should consult their physicians about the best way to obtain sufficient amounts of calcium and vitamin D.  For more information about dietary assessment and recommendations for optimal bone health please see https://osteoconnections.com/patientmaterials/.

Q5:  Can exercise improve bone health?

A:  Yes, persons with SCI can benefit from performing exercises that require weight-bearing during standing and/or electrical stimulation induced muscle contractions of the legs. Electrical stimulation induced strength training exercises during functional exercises such as cycling or rowing may help increase BMD of the legs.  For these improvements in BMD to occur, these exercises must be performed 30-60 minutes, 3-5 days a week, for at least a year.  These exercises are also recommended to help maintain BMD at the hip and knee regions over a lifetime.  These improvements are specific to the site of the bone where muscle contraction is the strongest— with this improvement in BMD diminished once the exercise is stopped.  Persons with SCI should consult with their healthcare provider before beginning these exercises.

Q6:  Are there drug therapies are available to prevent and treat bone loss in SCI?

A:  Yes, there have been drugs used in clinical trials that have stopped BMD loss at the hip and knee regions during the first year of SCI.  These drugs work by inhibiting the cells that promote breakdown of calcium stores within bone tissue before the BMD loss occurs. There is also preliminary evidence that these medications can be effective in restoring BMD at the hip and knee regions in individuals with long standing SCI.  While these medications have been approved by the Food and Drug Administration as safe and effective, many of these medications have side effects and may not be good for persons with SCI that have other chronic medical conditions.  Persons with SCI should consult with their physicians about the best medication available to prevent or treat BMD loss.

For additional information about this topic there is a new guideline published by the Paralyzed Veterans of America called “Bone Health and Osteoporosis Management in Individuals with SCI” (www.pva.org/publications) and has been used to answer many of these questions.  The information in this document has also been summarized in “the Bare Bones Podcast Series” (https://www.scifragments.ca/episodesfull) and may prove helpful to both clinicians and persons living with SCI.