ABI POLUS
Abi Polus is Senior Clinical Physiotherapist-Haemophilia at the Ronald Sawers Haemophilia Centre, Alfred Health, Melbourne, Victoria.
Why is low bone density and osteoporosis an issue for people with haemophilia? Will that mean they are more likely to have fractures? What can be done about it?
Haemophilia physiotherapist Abi Polus explains bone density in humans, how it is measured and why people with haemophilia are more vulnerable to low bone density and the risk of osteoporosis. She walks through the options for preventing and managing low bone density and osteoporosis in people with haemophilia.
A fracture is a discontinuity in the bone cells caused due to either trauma OR poor structural integrity of the bone.
Osteoporosis is a term that refers to the fragility of a bone, usually due to reduced bone density and affected bone architecture.
Let’s go back a step – what is bone? Bone is a living tissue of cells called osteocytes that are composed of collagen, (plus some carbohydrates, water and proteins), and have (non-living, or inorganic) minerals within.
Mature (fully formed) bone cells are termed osteocytes: these are cells embedded in the bone matrix. Osteoblasts (Bone Builders) are cells that form bones and help lay down new bone matrix, to repair damage and re-model the bone. Osteoclasts (Bone cleaners) are cells that reabsorb the bone that is old or has damage so that new bone (the osteoblasts) can repair and lay down new bone.
Bone cells are in a constant state of turnover throughout life. Bone mass is primarily developed in childhood and adolescence with Peak Bone Mass occurring typically in early 20s for females and late 20s for males. Genetics, diet, exercise and lifestyle at those ages may influence bone density throughout life. Nutrition is important for bone health, with adequate intake of calcium and vitamin D, as well as magnesium, protein, potassium being important. Alcohol and smoking have been proven to negatively affect bone health. As ageing occurs, in general, less osteoblast than osteoclast action occurs. Hormonal changes can also affect bone density, predominantly in females as oestrogen declines.1
Minerals, such as calcium and phosphate ions, are deposited into the bone matrix in high levels as hydroxyapatite (termed ‘calcification’). This allows the bone to have both strength and flexibility, in order to absorb impact and prevent breakage.
Bone density measures the amount of the bone minerals within the bone tissue. Low bone density indicates an increased risk of fracture if the bone is stressed, e.g. during a fall.
Bone mineral density measures the levels of calcium and other minerals in your bones. This is usually measured with a DEXA scan which uses radiation to measure the levels of calcium and you are often given a ‘T-score’ or a ‘Z-score’ These scores measure levels against what a normal level of bone mineral density in a young healthy adult is. This is used in postmenopausal women and men aged over 50 years. There are a few common areas that are measured most often the hip and spine.
Osteopenia is a stage of low bone density. If left and not addressed, it may progress to lower level of bone density called osteoporosis. Osteoporosis is diagnosed in adults if there has been a fracture with minimal trauma or have a low T- or Z- score. If osteoporosis is present the risk of a fracture with minimal trauma is higher. Osteoporosis is suggested to affect up to 10% of the male population, and often is only identified after a fracture.
There is a strong correlation between haemophilia and low bone mass density throughout the age ranges, not just in the older age populations.3,4,5
People with haemophilia may be more vulnerable to low bone mass density and increased osteopenia and osteoporosis. A 2023 study compared men with haemophilia and compared them with age-matched controls without haemophilia and found a significant decrease in bone mass density in those with haemophilia.3 This has also been demonstrated in earlier studies.4,5 It is suggested that may factors may contribute to this which include, but are not limited to, reduced physical activity, haemophilic arthropathy, periods of immobility, muscle atrophy, hepatitis C and/or HIV infection, and vitamin D deficiency.5,6 There has been some research presented that low bone mass density could also be due to the lack of coagulation factor itself on bone metabolism and bleeding into an area may affect the bone architecture.3
There have been some studies looking at haemophilia and bone density and osteoporosis risk. A study in 2012 found that adolescent boys with haemophilia have a lower trabecular (architectural bone cell matrix) density suggesting that peak bone mass may not be achieved in this population at this time. This could be due to lifestyle factors, or enforced rest if bleeds occurred which would decrease weightbearing at an essential time of growth.4 It is interesting that this study was conducted before novel therapies were available, and a more current study may have different results. It is relevant to our current middle-aged and older populations due to lower levels of activity as people with haemophilia were historically encouraged to do less physical activity due to lack of treatment if they were to have an injury (something we have completely changed our suggestions on with the available treatment nowadays).
Another consideration is that ‘normal’ peak bone density may not have ever occurred during the critical times of childhood and adolescence.3 For example, if you had recurrent bleeds in a weightbearing joint and had frequent periods of offloading (not putting weight or only partial weight) through that joint then you may not have laid down the full potential bone mass and density that would be reflected in the figures for an individual who had. When this is tested later on (or now) it may then show a ‘below average’ score, however this may not be due to decreasing bone density, but actually may be normal for you as you never had it. It is of more relevance to see if your bone mass is decreasing over time (problematic) or if it is stable (optimal). In patients who are now ageing, this then has the double impact of potentially less original bone mass density with now less osteoblastic action (laying down bone cells). This is why screening is encouraged.
The World Federation of Hemophilia (WFH) recommends screening for osteoporosis in people with haemophilia with ‘additional risk factors’7, however the 2016 Australian guidelines for the management of haemophilia in Australia advised all people with haemophilia should be screened according to local guidelines.8 Australian national guidelines on osteoporosis prevention state that all post-menopausal women and men over 50 years of age with one major risk factor (of which haemophilia could be counted) should be screened.9 A DEXA scan is recommended for people with haemophilia. These can be arranged through your general practitioner (GP) or rheumatology or orthopaedic clinics via your Haemophilia Treatment Centre. A vitamin D level is also advised as this impacts directly on bone mass density.
An increased risk of falls and of fractures has also been identified in people with haemophilia. Although the majority of fractures in the general population occur in those over 65 years, 81% of fractures in people with haemophilia occur below 50 years with an average of 28-30 years old.4 This is more prevalent in people with severe haemophilia than in those with mild or moderate haemophilia. For this reason we advise bone mass density DEXA scans to identify risks, but also strongly encourage exercise and activities to address risk of falls and maintenance of general fitness. There is a plethora of evidence to demonstrate that healthy and strong muscles, and balance and proprioception work can prevent falls. This includes the WFH guidelines and the Australian guidelines.3 Weight-bearing exercise specifically increases bone mass density and is recommended throughout the age ranges. At any age you can increase osteoclast formation (to increase bone mass density) with weightbearing exercise. Feel free to contact you HTC physiotherapist or local physiotherapist for a program.
In Australia a registry, the haemophilia osteoporosis registry (THOR), has been created so that data in individuals with and without haemophilia can be compared.3
Alongside weight bearing exercises and exercise programs targeting healthy movement and promoting good balance and falls prevention, there are various medications used to prevent osteopenia and osteoporosis if identified as a risk. Cessation of smoking, minimising alcohol and a healthy diet are also advised. If identified early and managed, this can prevent the risk of a fracture if a trauma was to occur.
The medical treatments may include calcium treatments and supplements for vitamin D if deficient.
There are anti-resorptive options these days, which slow down or prevent bone loss. The main differences are the mechanism of action and formulation, e.g. IV (intravenous) annual injection versus a weekly oral tablet. There are numerous options now which give patients choice due to suitability, preference and side effects. Your rheumatologist or GP are best placed to discuss this with you.
The WFH guidelines state that anti-osteoporosis medication should be used with people with haemophilia and osteoporosis and those with osteopenia should commence bisphosphonates as appropriate.6 The 2016 Australian guidelines stated bisphosphonates may be appropriate in some people with haemophilia.7
PREVENTION IS BETTER THAN CURE
Take home messages
It is recommended that children and adolescents should be doing regular, daily weight-bearing exercise to maximise peak bone mass.
Adults should also be doing regular, daily weight-bearing exercise to maintain their bone mass. Balance, proprioception and strength exercises will help to prevent falls and the risk of trauma and potentially fracture.
In addition to lifestyle and nutrition these are all factors we can individually contribute towards better bone health to protect ourselves from fractures.
Bone density should be regular screened in people with haemophilia.
If a decrease in bone mass density is identified it should be medically managed.
With thanks to Dr Ryan Moore, Rheumatology Registrar, The Alfred hospital, Melbourne for the pharmacological advice.
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