| Abstract|| |
We screened 288 patients having one or more risk factors of osteoporosis to assess their bone mineral density (BMD) using Achilles express heel ultradensitometer. WHO criteria were used to classify the patients based on their T scores. There were 125(43.46%) normal, 103(35.76%) osteopaenic and 60(20.83%) osteoporotic cases. The relationship of sex, age, menopause, tobacco and alcohol consumption and chronic bone and joint complaints with BMD were studied. The difference in the frequency distribution of sexes was significant below 60 years of age (p<0.001). Mild to moderate consumption of alcohol and tobacco had no significant effect (p>0.05) on the BMD. Menopause as well as chronic bone and joint complaints had a significant effect on the BMD (p<0.001).
Keywords: Bone mineral density- Osteopaenia- Osteoporosis.
|How to cite this article:|
Rao H, Rao N, Sharma L R. A clinical study of bone mineral density using heel ultra-densitometer in Southern Maharashtra. Indian J Orthop 2003;37:9
|How to cite this URL:|
Rao H, Rao N, Sharma L R. A clinical study of bone mineral density using heel ultra-densitometer in Southern Maharashtra. Indian J Orthop [serial online] 2003 [cited 2019 Sep 18];37:9. Available from: http://www.ijoonline.com/text.asp?2003/37/2/9/48507
| Introduction|| |
In early 1990 a universally accepted definition of osteoporosis was framed which moved this disorder from a disease of fracture to a disease of fracture risk. According to this definition- 'Osteoporosis is a systemic skeletal disease characterised by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture'.  Based on densitometer readings WHO has set definitive criteria for defining osteoporosis using T scores.  T score describes the bone mass of the patient compared to the mean peak bone mass of the normal young adult reference population.
The above criteria are applicable even in the absence of a confirmatory bone biopsy.
In India precise figures on the prevalence of osteoporosis is not available at present, however it is estimated that >61 million Indians have osteoporosis, of these 80% patients are females.  With the increase in life expectancy and already 10% of the population being above 65 years, osteoporosis has become a formidable public health problem. Nordin observed that India has the highest prevalence of osteoporosis and osteopaenia in the world followed by Japan and also that bone loss commences earlier in them.  BMD is the single most valuable predictor of osteoporotic fracture and accounts for about 89% of an individual fracture risk. The relative risk of fracture increases 2 times for each 1SD below normal BMD. 
The pathogenesis of osteoporosis is complex. It is not known whether osteoporosis in Indians is a consequence of lower peak bone mass or an increase in age related loss of bone.  Peak bone mass is attained between ages of 25-35 years and approximately 6% bone loss per decade occurs after the attainment of peak bone mass in Indians.  Factors determining peak bone mass are genetic and non genetic (nutrition, smoking, exercise, hypogonadism). A subclinical calcium and vitamin D deficiency is present in a significant proportion of the general population in India, often before peak bone mass is reached resulting in reduced peak bone mass and a state of continuing deficiency further promotes bone loss.  After menopause there is an acceleration of bone loss averaging 2% per year for next 5-10 years followed by a slower rate of bone loss. Life time losses may reach 30-40% of peak bone mass in females and 20-30% in males.
This study was undertaken to assess the level of BMD in patients with predisposing factors for osteoporosis and to institute appropriate therapy in them. The effect of age, sex, bone and joint complaints, consumption of alcohol and tobacco and menopause on BMD were also studied.
| Material and Methods|| |
Two hundred and eighty eight consecutive patients having one or more of the risk factors for osteoporosis (menopause, smoking, alcohol consumption, tobacco chewing, chronic bone and joint pain, fracture due to trivial trauma, age above 40 years in case of females and above 50 years in males, any history of drug intake deleterious to the bone metabolism) were selected for the study. Patients with a history of recent or old fracture of calcaneum or any pathology in the form of tumor or osteomyelitis of calcaneum which could affect local BMD were excluded from this study.
The instrument used was Achilles express bone ultra-densitometer. This instrument used transducers at fixed position to minimise errors due to contact pressure, change of position and errors due to variable heel width. The patients were classified as per the WHO criteria into normal, osteopaenic, osteoporotic or severely osteoporotic. The measurements were done by the same technician over a period of 2 days.
| Results|| |
One hundred and fifty of our patients (52.08%) were males and 138 (47.91%) were females. The minimum age was 11 years (known case of osteogenesis imperfecta) and maximum age was 84. There were 70 (24.30%) patients below the age of 40 years and 218 (75.70%) were above 40 years. Out of 138 females, 80 (57.97%) were menopausal and 58 (42.02%) were non-menopausal. Mild to moderate consumption of alcohol and tobacco chewing or a combination of these was seen in 66 cases (22.91%). Chronic symptoms related to the musculoskeletal system were seen in 167 (57.98%) cases.
The results were tabulated and analysed statistically. Test of significance (chi square test and Z test) were applied wherever necessary. In our study 125 (43.46%) cases had normal BMD, 103 (35.76%) had osteopenia and 60 (68.33%) had osteoporosis [Table I]. The difference in the frequency distribution of males and females in the different BMD sub groups (normal, osteopaenia, osteoporosis) was significant (p<0.001) by chi square test. The percentage distribution of males and females in different BMD sub groups is shown in [Table 2]. The 'Z' test of significance was applied in each age group to assess any difference in males and female T score (mean SD) falling within the same BMD sub group and it showed no significant difference (Z= -1.96 to 1.96) in any group. However significant difference were noted in the frequency distribution of males and females in the age groups of 41-50 (p<0.05) and 51-60 (p<0.001) however in >60 years age group no significant difference (p>0.05) was seen. The frequency distribution of menopausal and non-menopausal women in different BMD sub groups is shown in [Table 3]. The difference in the frequencies were statistically significant (p<0.001). [Table 4] shows frequency distribution of patients with and without history of alcohol and tobacco consumption in different BMD sub groups, 48.48% of former group had BMD deficiency and 51.51% had normal BMD, 59% of the latter group had BMD deficiency and 40.99% had normal BMD. These differences were not statistically significant (p>0.05) implying mild to moderate consumption of alcohol and tobacco had no effect on the BMD. Of the symptomatic cases 47.30% were normal and 52.70% had BMD deficiency [Table 5]. Similarly in the asymptomatic group 27.54% were normal and 62.46% had BMD deficiency. These differences were significant (p<0.001).
| Discussion|| |
Conventional radiographs are the classical modality for diagnosis and grading of osteoporosis, however it is relatively insensitive and bone loss is apparent only when the bone mass has decreased by 30-50%. Ultrasonic densitometers have been introduced which are safer as they do not involve radiation and are portable. DEXA is still the gold standard for measuring bone density. These devices allow skeletal integrity to be assessed both centrally and peripherally with an accuracy of 95% and precision error of <1% and relatively low radiation.
Bone ultradensitometers are based on the principle that when ultrasound waves are transmitted through the tissues they are attenuated, change in shape, intensity and speed.  Two most common measurements i.e. BUA (broad band ultrasound attenuation) and SOS (speed of sound) are combined to give a composite index known as stiffness index expressed as T score which has a coefficient of variation (r value=0.85) in relation to BMD of heel by DXA.  In India unfortunately there is no centralised data on the prevalence of osteopenia and osteoporosis. There are only isolated reports on the prevalence [Table 6]. ,
The cases in our study were selected on the basis of presence of risk factors of osteoporosis unlike other studies. The male: female ratio was higher in our study. This could be attributed to higher incidence of risk factors like alcohol and tobacco consuming habits in males. In our study the incidence of osteopenia and osteoporosis was higher in males as compared to other series and in females it was lower.
We agree with the observations of Nordin  that in Indians bone loss occurs at a younger age group. In our study in the 31-40 years age group 48.38% females and 29.16% males were osteopenic while 8.33% females and 3.63% males were osteoporotic. This is a strong reflection of attainment of peak bone mass. The role of genetics and nutrition in the peak bone mass has been emphasized. 
Shridharl has reported that 6% of apparently healthy Indians <50 yrs have osteopenia. In our series 49.58% asymptomatic patients had osteopenia and 13.23% had osteoporosis. These differences could be due to selective screening of cases. The difference in the frequency distribution of symptomatic and asymptomatic cases in different BMD subgroups [Table 5] was significant (p<0.001) implying that chronic bone and joint complaints could be a clinical indicator of osteoporosis however in case of osteopenia this was not so. Chronic heavy smoking, heavy alcohol consumption, tobacco chewing are known risk factors for lowering BMD. In our study there were only mild to moderate consumption in 22.91% cases and there was no significant difference between alcohol and tobacco consumers and non consumers with relation to BMD.
In the menopausal group 33.75% were osteopaenic and 47.5% were osteoporotic and further 92.68% osteoporotic women were menopausal. In the non menopausal group 46.55% were osteopenic and 5.17% were osteoporotic and further 50% of the osteopenics women were non-menopausal [Table 3]. These differences are significant (p<0.001). These findings emphasise the role of menopause in osteoporosis and point to other factors in the causation of osteopenia in females. Though menopause has a direct bearing on osteoporosis the age of menarchy, regularity of cycle, repeated pregnancy and low peak bone mass contribute to osteopenia in non menopausal women. After 60 yrs senile osteoporosis uniformly affected both the sexes without any statistically significant difference. (p>0.05).
The major complication of osteoporosis is pathological fracture occuring most commonly in the vertebral bodies, neck of femur and the distal end of radius. There is an inverse relationship between BMD and risk of fractures. The complications are preventable by early detection and correction of the deficient levels of BMD by appropriate therapy and avoiding risk factors wherever possible.
On the basis of our study we conclude that osteopenia commenced in younger age group (31-40) in both the sexes indicating a low peak bone mass. The incidence of osteopenia and osteoporosis was higher in females. Above 60 yrs males and females were equally affected by osteoporosis. Menopausal patients had significantly lower BMD. Patients with chronic bone and joint complaints had higher incidence of osteoporosis suggesting that it could be a clinical indicator of osteoporosis. Mild to moderate consumption of alcohol and tobacco does not significantly affect BMD. A detailed menstrual history and also a nutritional survey estimating the dietary intake of calcium, magnesium, oxalates and phytates would help in our better understanding of the causative factors of osteopenia and osteoporosis in this region particularly in the younger age group.
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Lecturer in Orthopaedics, Krishna hospital, Karad, Dist. Satara 415110. Maharashtra.
Source of Support: None, Conflict of Interest: None
[Table I], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]