Bone Density

More is Possible, 25.03.2024

A crucial topic!

Bone Density, in our opinion, is one of the topics, which is incredibly important to people with SCI to prevent breaking bones and keeping passive structures in shape for current and future treatments.

What is bone density, what about Osteoporosis - why is it important and how can we keep bone density on the best possible level - those are difficult questions, even for professionals in the field, but we try at least to give an overview and some recommendations of interventions which can help.

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What is Bone Density?

Bone mineral density (BMD) is the ratio of mineralized bone substance to a defined bone volume. Basically we can say, the denser the bone, the more stable it is and the lower the risk of a bone fracture.

What test procedures exist for measuring bone density and how can the real risk of fractures best be estimated?

CT Method

CT-Method = Computer Tomography

Quantitative digitale Radiographie (QDR, Synonyme DEXA, DPX)

DXA-Method or DEXA-Mehtod  = Dual Energy X-ray

With DXA- or CT-examinations usually the bone mineral content of the lumbar spine respectively of the femur is measured. X-Ray is making “just” 2D-images (two-dimensional-images) and thus can provide important but not conclusive information about the actual condition of your bones.

 It is one marker for bone density but not the only one.

Quantitative Computertomographie (QCT)

pQCT-Methode = Peripheral quantitative computed tomography

With the pQCT-Examination the three-dimensional bone structure can also be displayed, which means that in addition to pure bone density values (as with DXA- oder CT-Examinations), statements can also be made about trabecular bone density respectively fracture stiffness/quality of the bone.

Fine Element Analyses 

The stability of the bone can only be accurately determined with an FNA. The finite element method (FEM) is a technique for solving boundary value problems. It can be explained as a numerical method for solving differential and integral equations. Finite Element Analysis (FEA) is the practical application of FEM. FEA is a calculation instrument for carrying out technical analyses. It can be used for analyzing new product designs as well as as well as for existing designs using the equations of material mechanics. FEA analysis can also be used to measure the human femur.

Bone mineral density due to WHO-Classification

  • T-Score > -1 corresponds to normal bone
  • T-Score ≤ -1 but > -2.5 corresponds to Osteopenia
  • T-Score ≤ 2.5 corresponds to Osteoporosis
  • T-Score ≤ 2.5 with inadequate fracture corresponds to manifest Osteoporosis
  • T-Score ≤ 2.5 with inadequate fracture corresponds to manifest Osteoporosis

Here it is important to say: even if you already have osteoporosis, to have a value of -2.6 is way better than having one of -6 or -7 - it makes sense to stop it and hopefully even reverse it to a certain level!

→Low Bone Density leads to Osteoporosis and this leads in many cases at some point to Bone fractures which causes long lasting problems including stationary stay at a specialized clinic.

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What is Osteoporosis?

Osteoporosis (Greek for porous bone) refers to bone loss or a decrease in bone substance. It can be caused by inactivity, among other things; this form of osteoporosis is typical for people with spinal cord injury.

The lack of mechanical stress on the skeleton leads to bone loss from the first few days after suffering a spinal cord lesion (spinal cord injury). This is shown by increased calcium excretion in the urine. In the first few years after a spinal cord injury, 40 - 60% of bone mass can be lost. [5]

Osteoporosis is an ongoing reduction in bone mass, during the progression of which the bone architecture also changes. Both factors lead to a reduced resistance of the bone and thus to an increased risk of fracture.

Bones can break even under everyday physical stress.

For people with spinal cord injuries, osteoporosis is often the result of a lack of bone load on the extremities.

What are biological factors that may have an impact on osteoporosis risk?

  • Gender - it is not a secret, but women and men aren't the same.
  • Age - it is not a secret either, but bone density decreases over time.

These are factors you can not change but it is still good to know that you can consider those for your prevention tactics.

Possible reasons for osteoporosis

  • Neural (concerning the nerves)
  • Vascular (due to blood vessels or concerning the blood vessels)
  • Hormonal

What strategies can be used to higher bone density and treat osteoporosis?

(Training, Therapie  and Movement)


To prevent bones from degrading, i.e. losing density, alternating load and unload is essential.

Bending forces, for example, bending the lower leg, also have a positive effect on bone density of the upper leg (this happens, for example, during FES cycling).


  • Lokomotion with Lokomat has positive effects on bone density
  • Ekso-Skeletons has positive effects on bone density
  • Rollator-walking has positive effects on bone density
  • Standing combined with other walking-exercises etc. has positive effects on bone density
  • For those who have upper limb disabilities as well, exercises with your upper body are as well very beneficial for bone density in your arms etc.


Direct Muscle Stimulation

With powerful stimulation Equipment such as Stimulette RISE Stimulator  or NEUBIE Electrical Stimulation device with very high Energy to build up muscle fiber and thus muscle mass in denervated or partially denervated muscles.

Stimulette RISE Stimulator 

NEUBIE Electrical Stimulation device


Trials with regular training under functional electrical stimulation of the paralyzed legs on a tricycle have shown positive effects on bone density. For more denervated muscles, use FES-Bikes with higher Energy such as RT300 from Restorative Therapies which has up to 3ms pulse width.

RT300 Leg Arm Core



Adequate calcium intake is the basic therapy for osteoporosis today.

A daily amount of calcium of 1’000 - 2’000 mg is required. For people who already have developed Osteoporosis the amount of Calcium should be at least 1’500 mg per day.

If you use high-dose calcium solutions for treatment, these should not be drunk all at once, but in sips, as osmotic diarrhea can occur in sensitive people - the calcium can also be better absorbed in the body this way.

Calcium absorption can be negatively influenced by

  • phosphate-rich foods
  • Foods containing oxalic acid
  • dietary fiber
  • fats

Calcium-containing foods without a lot of phosphate:

  • Milk
  • Cheese (hard and soft cheese)
  • Yoghurt

Calcium-containing foods with "too" much phosphate:

  • Quark
  • Cottage cheese
  • Processed cheese (melted cheese)

Contraindication: Recurrent nephro/urolithiasis. Hypercalcemia [2]


Eating enough proteins has positive effects on bone density

The Swiss Federal Nutrition Commission recommends a protein intake of 0.8g per kilogram of body weight per day for the elderly. It is also reported that 1.5g per kilogram of body weight per day reduces the risk of hip fractures. [3]

Nature and Substitutions

Vitamin D respectively Vitamin D3

Having a sunbath every day for 20min to half an hour would be perfect, but most people don’t have the time or necessary sun when they finally get time to do so - because this, substitution of Vitamin D3 is a good thing for several reasons.

The substitution of Vitamin D3 can help the body to better absorb the calcium in the bones - especially if you suffer from a low D3-level. You can check your D3-level by blood test - various reference values can be used to assess 25(OH)D serum levels. The Robert Koch Institute uses the internationally frequently used classification of the US Institute of Medicine (IOM), which relates to bone health and classifies 25(OH)D serum values as follows:

Whit the following values you can make sure, that you have enough Vitamin D3, without any risk of side effects:

  • 25(OH)D in nmol/l a level of 75 nmol/l  but lower than 125 nmol/l
  • 25(OH)D in ng/mla level of 30 ng/ml but lower than 50 ng/ml

Vitamin D status is determined by measuring 25-hydroxyvitamin D, or 25(OH)D for short, in the blood serum. 25(OH)D is a precursor of active Vitamin D and can be expressed in units of nmol/l or ng/ml (to convert nmol/l to ng/ml, divide the value by 2.5).

Robert Koch Institute Vitamin D [4]

Contraindication: Recurrent nephro/urolithiasis. Hypercalcemia [2]


Estrogens (female sex hormone)

Estrogen substitution after the loss of endogenous Estrogen production is the most important prophylactic measure to prevent osteoporosis. In addition to effective treatment of climacteric (menopause-related) symptoms, this can also significantly reduce morbidity and mortality (probability of disease and mortality) due to arteriosclerosis (hardening of the arteries). Estrogen substitution is particularly necessary in the case of osteoporosis that has already manifested itself in order to prevent further progression.

Indication: Prophylaxis and treatment of osteoporosis in peri-/postmenopausal women

Irrespective of menopausal symptoms, Estrogen substitution should be started as early as possible with the onset of ovarian insufficiency for the best possible prophylaxis of osteoporosis. However, a positive effect can also be expected with later use. Effective prophylaxis requires a therapy duration of many years. There is no limit to the maximum duration of therapy. [2]

This small section is only intended to give you a feel for the subject - the effective indication and therapy can vary and must be considered on an individual basis.

Discuss the issue with your treating physicians and contact a specialized clinic if you are not in regular contact with specialists in this field - a bone density check is certainly never wrong.

Androgens (male sex hormones)

In men with testosterone deficiency, substitution with testosterone prevents premature osteoporosis.

Indication: Testosterone substitution in men with proven testosterone deficiency. [2]

 If you already have osteopenia (impending osteoporosis) or established osteoporosis, it certainly makes sense to measure your testosterone levels. However, if your bone values are normal, you could still have them checked during a routine check-up to take preventative measures if necessary.


The administration of fluorides leads to a thickening of the trabeculae and an increase in bone mass via direct stimulation of the osteoblasts. Studies have shown that in addition to the increase in bone mass, the fracture rate has also decreased in treated patients.

Contraindication: Chronic liver and kidney diseases Pregnancy, breastfeeding, osteomalacia

Discuss the subject with your treating doctor or institution.


Bisphosphonates are a new group of orthotropic drugs - synthetic analogs of endogenous pyrophosphate. Bisphosphonates inhibit osteoclast bone resorption.

Contraindication: Schwangerschaft, Stillzeit Akute Erkrankungen des Gastrointestinaltrakts

Bei Niereninsuffizienz entsprechende Dosisreduktion

Discuss the subject with your treating doctor or institution.


Calcitonin acts by inhibiting bone resorption and possibly also by increasing the formation of new bone. Numerous studies show a preservation or increase in bone mass under therapy with calcitonin.

Contraindication: Pregnancy, breastfeeding

Discuss the subject with your treating doctor or clinic.


Avoid smoking

  1. Smoking restricts the flow of oxygen-rich blood that nourishes bones, muscles and joints and helps them heal.
  2. Smoking affects the body’s ability to absorb calcium, leading to lower bone density and weaker bones.
  3. Nicotine slows the production of the bone-forming cells that are so crucial to healing
  4. Smoking appears to break down estrogen — a key ingredient to building and maintaining a healthy skeleton — more quickly.


Smokers have a higher risk of osteoporosis and fractures

  • Smoking makes osteoarthritis worse
  • Smoking makes you more vulnerable to soft tissue injuries
  • Smoking is linked to low back pain
  • Surgery isn’t as effective and recovery takes longer in smokers.

We are not here to tell you to stop smoking but if you can… ;-) If not reducing  is already helpful and trying to go for the other points we are mentioning in this article might be helpful  as well.

Citation Source Information

[1] Wikipedia

[2] Ludwig-Maximilians-Universität München. Empfehlungen zu Prävention, Diagnostik und Therapie der Osteoporose.

[3] Gesellschaft für Ernährung, 2015.

[4] Robert Koch Institut, 2023.

[5]  Zehnder et al., 2004.