Osteoporosis is a disease of bone that leads to an increased risk of fracture. In osteoporosis the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of noncollagenous proteins in bone is altered. Given its influence is the risk of fragility fracture, osteoporosis may significantly affect life expectancy and quality of life.1

Risk factors for osteoporotic fracture can be split between non-modifiable and modifiable. The most important nonmodifiable risk factors for osteoporosis are advanced age (in both men and women) and female sex; estrogen deficiency following menopause is correlated with a rapid reduction in bone mineral density, while in men a decrease in testosterone levels has a comparable (but less pronounced) effect. While osteoporosis occurs in people from all ethnic groups.2

The techniques used to assess the risk of fractures include clinical assessment of risk factors and physical measurement of skeletal mass. Skeletal mass can be measured by semi-quantitative techniques for assessing the trabecular morphology of the femoral neck (i.e. the Singh index), radiogrammetry, radiographic absorptiometry, quantitative computed tomography, ultrasonography, or by energy absorptiometry (e.g. dual energy X-ray absorptiometry (DEXA) or single energy X-ray absorptiometry (SEXA)3,4,5 The, Singh index which describes trabecular patterns in the proximal femur, is accepted indicator of osteopenia and osteoporosis and may be used as an predictor for hip fractures.3,4 Present study was aimed to study porosity of bone and its relation to fractures around hip by using Singh index.

Present study was prospective, observational study, conducted in department of Orthopaedics at Yenepoya Medical College, Mangalore, India. Study duration was of one & half years (December 2016 to July 2018). Study was approved by institutional ethical committee.

Inclusion criteria

• All the patients coming to the Orthopaedics OPD and casualty with a fractures around hip, willing to participate in present study

Exclusion criteria

• Pathological fractures

Study was explained to participants in local language & written informed consent was taken. Relevant clinical data (demographic- age, sex, place, occupation) including history was obtained from the patient. A detailed clinical examination was performed for all the patients and X ray Hip joint AP view will be done. Singh index was used to study the trabecular patterns of the hip joint.

90 patients with fractures around hip underwent antero-posterior digital radiographs of pelvis with both hip joints with hip joints in abduction and 150 internal rotation. The series of radiographs of normal hip are assessed by observer 1, twice with one month apart and observer 2 using Singh index for grading of osteoporosis. The inter- and intra-observer reliability and intraclass correlation coefficients of the evaluations by both the observer was tested (kappa value) and postulates were deduced.

Data was collected and compiled using Microsoft Excel, analysed using SPSS 23.0 version. Frequency, percentage, means and standard deviations (SD) was calculated for the continuous variables, while ratios and proportions were calculated for the categorical variables. Difference of proportions between qualitative variables were tested using chi- square test or Fisher exact test as applicable. P value less than 0.5 was considered as statistically significant.

In this series of 90 patients, most of fractures around hip are seen in elderly group of patients with age more than 60 years i.e. almost around 58% and about 41 % in the age group below 60 years. Most of the hip fractures are commonly seen in females with 53 % and in males with 47 %. Fracture neck femur is most commonly seen that is about 50 % followed by intertrochanteric fractures with 43% and then subtrochanteric fractures i.e. 7%.

Table 1: General characteristics

Most of the fractures around hip have Singh index of osteoporosis of Grade 3 that is 53.3 %. When radiographs were evaluated by observer 1 after one month apart, showed most of the fractures around hip have Singh index of osteoporosis of Grade 3 which is 62.2 % followed by Grade 2 (17.8 %) then Grade 4 (15.6%)

Table 2: Distribution of cases on the basis of Singh index by observer 1

Table 3: Cross tabulation between observer 1 Singh index at initial evaluation & after 1 month

Intraclass correlation coefficient between observer 1 Singh index and Singh index after one month apart was 0.811 with p value 0.00. Overall intra-observer agreement was 0.68 (kappa value) with p value 0.00.

Table 4: Intraclass correlation coefficient between observer 1 Singh index and observer 1 Singh index after one month.

When same radiographs evaluated by Observer 2, most of the fractures around hip have Singh index of osteoporosis of Grade 3 which is 56.6 %, followed by Grade 4 (18.9 %) then Grade 2 (13.3 %).

Table 5: Distribution of cases on the basis of Singh index by observer 2

Table 6: Cross tabulation between Singh index of observer 1 and observer 2

Overall inter-observer agreement was 0.568 (kappa value) with p value 0.00. Intra-class correlation coefficient between observer 1 Singh index and observer 2 Singh index was 0.705 with p value 0.00.

Table 7: Intraclass correlation coefficient between observer 1 and observer 2

After using Statistical Package For Social Sciences (SSPS) analysis, the grade of osteoporosis was related to the type of fractures around hip and also to the age of the patient (p value <0.05), whereas gender was not related to the grade of osteoporosis since p value >0.05.

Table 8: Significance of age, sex and type of fracture with Singh index

The Singh index, which describes trabecular patterns in the proximal femur, is accepted indicator of osteopenia and osteoporosis and may be used as a predictor for hip fractures.3 This pattern of trabecular bone loss has been characterized by Singh, who devised a scale from 6 to 1 to describe the degree of trabecular bone loss from the proximal femur (Singh index). Each grade of the index was characterized by particular degrees of bone loss from the various trabecular groups in the proximal femur. The Singh index is an inexpensive simple method of assessing bone density at a site where fractures occur.

In our study we had a series of 90 cases who had sustained fractures around hip were studied. We found out that the degree of osteoporosis had a relation with age at which the particular fracture occurred p value being 0.03. There was high relation of degree of osteoporosis with type of fractures (p value 0.00) around hip, but there was no relation with the gender of the patient. Over all inter- observer agreement was 0.56 (kappa value) and intra-observer agreement was 0.68 (kappa value) with p value 0.00. Intraclass correlation coefficient in intra-observer agreement ranged from 0.726 and 0.872 with p value 0.00. Fracture neck femur mostly seen in grade 3 and grade 2 of Singh index and intertrochanteric fractures were seen in grade 4 and grade 3 of Singh index. There is moderate inter-observer agreement and a good intra-observer agreement. Agreement is good in severe osteoporosis than mild to moderate osteoporosis.

In a retrospective study conducted by Supradeeptha Challa and Satyaprasad J6, 87 patients who had sustained fractures around the hip, were studied. They concluded that the grade of osteoporosis was not related to age, gender and laterality in the osteoporotic patients (p >0.05) overall mean intra-observer agreement was 0.49±0.1 and inter-observer agreement was 0.21±0.2 (kappa value). Older patients with Singh index of Grade 5 or less are more prone to intertrochanteric fractures in the hip region. The risk of femoral neck fractures increases in patients with advanced osteoporosis.

In the study conducted by Syed Imran Bukhari et al.,7 involving 120 post-menopausal women, x-ray pelvis with both hips were undertaken in all patients. This study concluded that overall inter-observer agreement among the observers was 69.5% with p value.000, which is significant. 95% Confidence interval was 0.587 to 0.779. The kappa value ranged from.171 to.261 with a slight to fair agreement. Interobserver reliability of Singh index for grading of osteoporosis is very useful method for grading of osteoporosis.

In another study conducted by Soontrapa S et al.,5 the bone mineral density of the left femur neck was measured with DEXA.Singh index of osteoporosis was applied and both inter-observer and intra-observer reliability was measured (kappa value). Intra-observer reliability was 0.1 and inter-observer reliability was 0.0 which had poor agreement. This study concluded that the Singh index has poor reliability and poor diagnostic value in screening of femoral neck osteoporosis.

In a study conducted by Lizaur-Utrilla et al.,8 in patients older than 60 years of age with stable trochanteric fractures concluded that there was no correlation between type of trochanteric fractures and gender. Stable trochanteric fractures occurred more frequently in the better bone quality.

In a study by Fuji9 demonstrated that the rate of femoral neck fractures was higher with moderate or severe osteoporosis and rate of intertrochanteric fracture (extracapsular) fractures was higher in patients with borderline or mild osteoporosis. In the study conducted by Ameet Julka et al.,4 on 30 consecutive patients concluded that there was correlation between the Singh index and age (p value <0.01). In another study by M.R. Salamat, et al.,3 concluded the poor reliability of Singh index and no significant correlation between the Singh index and age (r = -0.1 and p = 0.26).

In our study we had a correlation between the Singh Index and age (p value 0.03). Higher grades of osteoporosis was found in age group above 60 years and lower grades of osteoporosis was found in age group below 60 years.

In our study we had 6 cases of subtrochanteric fracture of which 5 were males and 1 was female patients (mean age being 40 years =). After evaluating with Singh index there were 4 cases of grade 5 (66.6 %) and 2 cases of grade 4 (23.33 %). This highlighted fact that in young and strong bone greater force is required to break subtrochanteric region. This postulates that subtrochanteric fractures are purely due to high velocity injury and are associated with higher grades of osteoporosis of Singh index.

To summarize, our study had inter-observer agreement of 0.56 (kappa) which is moderate agreement and intra-observer agreement of 0.68 which is good agreement. This concludes that Singh index can be used for the grading of osteoporosis in hip fractures.

Fracture neck femur and Intertrochanteric fractures were detected mid-range between grade 4 to grade 2 (Singh Index). Higher grades of osteoporosis (Grade 3 to Grade 1) were seen in the age group above 60 years while lower grades (Grade 6 to Grade 3) of osteoporosis were seen in the age group below 60 years. Age of the patient have a relation to the degree of osteoporosis. Gender of the patient did not have any relation to the degree of osteoporosis. Singh Index was found to be a reliable tool for grading of osteoporosis in a hip region.

1. Pramudito J.T., Soegijoko S., Mengko T.R., Muchtadi F.I., Wachjudi R.G., Trabecular Pattern Analysis of Proximal Femur Radiographs for Osteoporosis Detection. Journal of Biomedical & Pharmaceutical Engineering, 2007, 1, 45-51
2. Melton L.J., "Epidemiology worldwide". Endocrinol. Metab. Clin. North Am., 2003, 32,1–13.
3. Salamat M, Rostampour N, Zofaghari S, Hoseyni-Panah H, Javdan M. Comparison of Singh index accuracy and dual energy X-ray absorptiometry bone mineral density measurement for evaluating osteoporosis. Int J Radiat Res. 2010; 8 (2) :123-128.
4. Ameet Julka, S Shrivastava, R Pandey, P Bhargav, A Ajmera. To evaluate the utility of Singh index as an indicator of osteoporosis and a predictor of fracture neck femur. J. Anat. Soc. India 61(2) 192-198 (2012).
5. Soontrapa Suppasin, Soontrapa Sukree,,Srinakarin Jiraporn, Chowchuen Prathana,Singh Index screening for femoral neck osteoporosis. J Med Assoc Thai 2005;88(Supp. 5):S13-6.
6. Supradeeptha Challa, Satyaprasad J. Reliability of Singh index in grading of osteoporosis using digital radiographs in elderly patients with proximal femoral fractures. International journal of development research.2013;11:159-61.
7. Bukhari SI, Qadir RI, Khan S, Khan A. Assessment of interobserver reliability of singh index for grading of osteoporosis. J Med Sci 2017; 25: (1) (Supplement) 175-178
8. Lizaur-utrilla, A., Orts, A.P., Del Campo,F. S.,Barrio,J. A., & Carbonell,P.G. (1987). Epidemiology of trochanteric fractures of the femur in Alicante, Spain, 1974-1982. Clinical Orthopaedics and Related Research.
9. Fujii M. Experimental study on the mechanism of femoral neck fractures. Nihon Seikeigeka Gakkai Zasshi. 1987; 61(5): 531-41.