OSTEOPOROSIS

WHAT IS OSTEOPOROSIS ?

Osteoporosis is a bone condition characterised by low bone mass and changes to the internal structure/architecture of the bone.  These changes cause increased bone fragility and therefore, increased susceptibility to fracture.  

Our bones are constantly being remodelled.  Bone is formed (by cells called osteoblasts), and bone is lost, also known as resorption (by cells called osteoclasts).  In normal circumstances, the amount of bone formation equals the amount of bone resorption.  In osteoporosis, this ratio is altered, and the amount of bone loss is greater than bone formation.  

 

Osteoporosis is asymptomatic until a fracture occurs (we don’t experience symptoms such as pain and stiffness).  Often, the first an individual becomes aware they have osteoporosis is following an osteoporotic fracture, most commonly after a fall.  There are risk factors (which we will look at shortly) that can increase our suspicions that an individual might be predisposed to osteoporosis.  

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 PREVALENCE

  • Approximately 3.5 million individuals in the UK have osteoporosis

  • Nearly two-thirds of Australians over 50 suffer from low bone mass (osteopenia). 70% of whom are women, 30% men.  

  • It is estimated that 200 million individuals have osteoporosis worldwide

  • With an ageing population and longer lifespans, this number is expected to increase

Fracture is the most serious clinical consequence of osteoporosis: 

  • Osteoporotic fracture predominantly affects white post-menopausal women

  • Worldwide, osteoporosis causes >8.9 million fractures annually

  • Hip fractures are the most devastating in terms of morbidity and mortality. Hip fracture rates in men are approximately half of that in women. However, mortality rates following hip fracture are substantially higher in men than in women.

  • Since 1990, the number of fractures has continued to increase as the population ages. It is estimated that the annual worldwide hip fracture occurrence will increase by up to >6 times by 2050.

Many osteoporotic fractures are considered to be preventable. On an individual and  population level, the impact to life, resources, time, and finances that could be spared if we reduced the fracture rates in the UK are substantial. 

DIAGNOSIS

The most widely used diagnostic scan for osteoporosis is DEXA (dual-energy x-ray absorptiometry).  A DEXA scan gives us information on our bone mineral density (BMD), usually at the spine, hip, and forearm.  These sites are chosen as they are the most commonly fractured.   

 

The World Health Organisation (WHO) has devised thresholds for categorising individuals based on bone mineral density T-scores.  The T-score compares your BMD results to those of the young adult mean (how many standard deviations away from the peak bone mineral density of healthy young adults you are). Race and sex-specific T-scores are typically used.    

BMD T-score:   

RISK FACTORS

Normal:   -1.0 or above 

Osteopenia (low bone mass):   -1.0 to -2.4

Osteoporosis:  less than or equal to -2.5

(The further into the minus scores we go, the lower the bone mineral density)

There are fracture risk assessments that your Doctor can use if they are concerned you are at higher risk of fracture (these don’t just consider bone density; they look at several risk factors for fracture).

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Some of the risk factors for osteoporosis are modifiable (most notably, physical activity, exercise and nutrition).  Other risk factors are unmodifiable (age, genetics, and family history).

  • Ageing (age-related bone loss is very evident in adults who are inactive)

  • Female sex, particularly post menopausal women (women typically lose bone more rapidly, particularly during the first years after menopause due to estrogen deficiency)

  • White ancestry 

  • Family history of osteoporosis

  • Sedentary lifestyle / lack of physical activity and exercise 

  • Low BMI (body mass index) and/or low body weight 

  • Inadequate nutritional absorption of calcium and/or vitamin D

  • High alcohol intake 

  • Smoking 

  • Low sex hormones - oestrogen / testosterone

  • Prior fragility fracture (particularly hip or spine)

  • Family history of fragility fracture (particularly maternal history)

  • History of use of certain medications - eg, corticosteroids, male hormone suppressants (eg ADT when treating prostate cancer), chemotherapy 

  • Inflammatory diseases such as rheumatoid arthritis 

TREATMENT & MANAGEMENT

The overall treatment plan will depend on various factors including age, current bone mineral density scores, general health, fracture risk (including falls risk), medical history, and possible side effects of medications. 

Non-pharmacological management comes first.  This is achieved by addressing modifiable lifestyle factors including:

  • appropriate exercise and physical activity (we will look at specifics in the next section)

  • nutrition - calcium, vitamin D, and general nutritional intake 

  • smoking cessation and alcohol moderation 

Once these modifiable lifestyle factors have been addressed, and should it be determined as appropriate, medications will be discussed with your GP and possible referral to a specialist.   

Let us now look at the evidence-based recommendations for exercise prescription for osteoporosis.

Role of appropriately prescribed exercise:

Exercise is a primary modifiable factor for the development and maintenance of optimal bone strength throughout life. It is a vital strategy in the prevention and management of osteoporosis, if appropriately prescribed.

Bone is a dynamic tissue, and therefore, like our muscles and our cardiovascular system, if an appropriate amount of strain is placed on it, our skeleton adapts by becoming stronger and reinforcing itself. For bone to respond, relatively high strains need to be placed on the skeleton (relatively few repetitions are required). For example, it is now recognised that walking and other low intensity activities do not place enough stimulus on bone to induce adaptations and improvements in bone strength (walking is, of course, beneficial for many other components of health). 

Current best evidence indicates that the most osteogenic (bone forming) exercise protocols include progressive resistance training and jumping/impact activity.  Balance training is key for those at increased risk of falls.  

Progressive resistance / strength training

  • Minimum of 2 days per week

  • High intensity (80-85% of 1 repetition maximum. Very hard)

  • Loads to be progressively increased over time 

  • Compound, multi-joint exercises that focus on major muscle groups, particularly those attaching to the hip and spine

Impact / jumping exercises

  • Performed on 3+ days per week  

  • Sports and activities such as jogging, tennis, volleyball, basketball etc

  • Jumping and landing exercises at home or in the gym

Balance training 

  • Although balance training does not have a positive impact on bone formation, it is absolutely key for those with low bone mass who have an increased risk of falling.

  • Most osteoporotic fractures occur as a result of falling.  If we reduce the risk of falls, we immediately reduce the risk of fracture.  

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                                                                                                                                                                                                              Progressive resistance training and impact activities have been found to be safe and efficacious in those with known osteoporosis, however, appropriate caution needs to be taken. The exercise prescription should take into account each individual’s current bone mass, activity history, functional status, and clinical risk factors for falls and fracture. 

 For some individuals, a period of lower intensity training/activity may be required initially, and where certain recommended          activities (such as jumps) are not appropriate, alternative exercises can be prescribed.  Keys to the safety of such exercise    interventions are:

  • a graduated introduction of loading 

  • close ongoing supervision 

  • a focus on correct technique 

 

 It’s never too late to start, and no matter the starting point, we all have the capacity for progress.

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