Evaluation of quantitative CT vertebral bone mineral density measurement and the Singh index in elderly females with hip fractures--a case control study

Plain radiographic indices are reliable indicators for quantitative bone mineral density in male and female patients before total hip arthroplasty

Osteoporosis is underdiagnosed in patients undergoing total hip arthroplasty (THA). Bone mineral density measurement by dual-energy X-ray absorptiometry (DXA) is the gold standard, but indices on plain hip radiographs also seemed to be reliable screening tools in female or Asian ethnicities in previous studies. Given the lack of knowledge about male patients and Caucasian ethnicities, this study was conducted to evaluate plane hip radiographic indices as a screening tool for osteopenia and osteoporosis in Caucasian female and also male patients before undergoing THA. A retrospective analysis of 216 elderly patients with pre-existing DXA before hip arthroplasty was performed and four indices were calculated on plain hip radiographs: Canal-Flare-Index (CFI), Canal-Calcar-Ratio (CCR), Canal-Bone-Ratio (CBR) 7 and 10 cm below the lesser trochanter. They were correlated with femoral neck DXA T-scores by Pearson's correlation and intraclass correlation coefficient, and a ROC analysis was performed. A total of 216 patients (49.5% male) were included. CBR-7 and -10 were highly correlated (p < 0.001) with femoral neck T-score in males (Pearson's correlation CBR-7 r = - 0.60, CBR-10 r = - 0.55) and females (r = - 0.74, r = - 0.77). CBR-7 and -10 also showed good diagnostic accuracy for osteoporosis in the ROC analysis in males (CBR-7: AUC = 0.75, threshold = 0.51; CBR-10: 0.63; 0.50) and females (CBR-7: AUC = 0.87, threshold = 0.55; CBR-10: 0.90; 0.54). Indices such as the Canal Bone Ratio (CBR) 7 or 10 cm below the lesser trochanter on plain hip radiographs are a good screening tool for osteopenia and osteoporosis on plain hip radiographs and can be used to initiate further diagnostics like the gold standard DXA. They differ between male and female patients.

Biomechanical properties and clinical significance of cancellous bone in proximal femur: A review

Trabecular bone plays an important role in the load-bearing capacity of the femur. Understanding the structural characteristics, biomechanics, and mechanical conduction of the trabecular bone is of great value in studying the mechanism of fractures and formulating surgical plans. The past decade has witnessed unprecedented progress in imaging, biomechanics and finite element analysis techniques, translating into a better understanding of trabecular bone. This article reviews the research progress achieved over the years regarding femoral trabecular bone, especially on factors influencing the strength of the proximal femoral cancellous bone and cancellous bone microfractures and provides a comprehensive overview of the latest findings on proximal femoral trabecular bone and their clinical significance.

Revisability of polyetheretherketone suture anchors utilised in primary and revision Bankart repair

BACKGROUND

Polyetheretherketone (PEEK) suture anchors are frequently used in Bankart shoulder stabilisation. This study analyzed the primary stability and revisability of PEEK anchors in-vitro in case of primary Bankart repair and revision Bankart repair after failed primary repair.

METHODS

To simulate primary Bankart repair, 12 anchors (Arthrex PEEK PushLock® 3.5 mm) were implanted in 1, 3, 5, 7, 9 and 11 o'clock positions in cadaveric human glenoids and then cyclically tested. To simulate revision Bankart repair, 12 anchors were implanted in the same manner, over-drilled and 12 new anchors of the same diameter were implanted into the same bone socket as the primary anchors and then cyclically tested. The maximum failure loads (F_max), system displacements, force at clinical failure and modes of failure were recorded.

RESULTS

One primary anchor failed prematurely due to a technical problem. Three out of 12 revision anchors (25%) dislocated while setting the 25 N preload. The F_max, the displacement and clinical failure of the remaining 9 revision anchors were non-significant when compared to the 11 primary repair anchors. The main mode of failure in the primary and revision Bankart surgery group was suture slippage. Anchor dislocations were observed four times in the primary and once in the revision repair groups.

CONCLUSIONS

Revision Bankart repair using PEEK anchors of the same diameter in a pre-existing bone socket is possible but bears high risk of premature anchor failure and can jeopardize the reconstruction. PEEK suture anchor in revision Bankart surgery should be implanted in a new bone socket if possible.

Association between osteoporotic femoral neck fractures and DXA-derived 3D measurements at lumbar spine: a case-control study

A case-control study assessing the association of DXA-derived 3D measurements at lumbar spine with osteoporotic hip fractures was performed. Stronger association was found between transcervical hip fractures and integral (AUC = 0.726), and cortical (AUC = 0.696) measurements at the lumbar spine compared with measurements at the trabecular bone (AUC = 0.617); although femur areal bone mineral density (aBMD) remains the referent measurement for hip fracture risk evaluation (AUC = 0.838).

PURPOSE

The aim of the present study was to evaluate the association between DXA-derived 3D measurements at lumbar spine and osteoporotic hip fractures.

METHODS

We analyzed a case-control database composed by 61 women with transcervical hip fractures and 61 age-matched women without any type of fracture. DXA scans at lumbar spine were acquired, and areal bone mineral density (aBMD) was measured. Integral, trabecular and cortical volumetric BMD (vBMD), cortical thickness, and cortical surface BMD (sBMD) at different regions of interest were assessed using a DXA-based 3D modeling software. Descriptive statistics, tests of difference, odds ratio (OR), and area under the receiver operating curve (AUC) were used to compare hip fracture and control groups.

RESULTS

Integral vBMD, cortical vBMD, cortical sBMD, and cortical thickness were the DXA-derived 3D measurements at lumbar spine that showed the stronger association with transcervical hip fractures, with AUCs in the range of 0.685-0.726, against 0.670 for aBMD. The highest AUC (0.726) and OR (2.610) at the lumbar spine were found for integral vBMD at the posterior vertebral elements. Significantly, lower AUC (0.617) and OR (1.607) were found for trabecular vBMD at the vertebral body. Overall, total femur aBMD remains the DXA-derived measurement showing the highest AUC (0.838) and OR (6.240).

CONCLUSION

This study showed the association of DXA-derived measurements at lumbar spine with transcervical hip fractures. A strong association between vBMD at the posterior vertebral elements and transcervical hip fractures was observed, probably because of global deterioration of the cortical bone. Further studies should be carried out to investigate on the relative risk of transcervical fracture in patients with long-term cortical structural deterioration.

Evaluation of Risk Factors for Second Hip Fractures in Elderly Patients

Background

Hip fracture is a worldwide public health problem that primarily affects osteoporotic individuals and the elderly. A second hip fracture can occur in elderly patients who have already suffered an initial hip fracture. The aim of this study was to investigate possible risk factors for second hip fractures in elderly patients with hip fractures.

Methods

Between 2010 and 2014, 230 patients who underwent uncemented bipolar hemiarthroplasty for hip fractures were retrospectively analyzed. The patients were divided into two groups: those with a first hip fracture (group 1) and those with a second hip fracture (group 2).

Results

The mean time from the first hip fracture to second hip fracture was 22 months. There were no significant differences in the American Society of Anesthesiologist scores, comorbidities were observed in the two groups. The mean length of hospitalization was not significantly different between the two groups. The mean postoperative functional scores after second hip fractures were significantly lower in group 2 than in group 1.

Conclusions

Although there are not certain risk factors for second hip fractures in elderly patients with hip fractures, to prevent second hip fractures, elderly patients should be provided with physical and medical therapy as well as orthotic support and their functional activity should be maintained.

Are radiographic indices reliable indicators for quantitative bone mineral density and vitamin D status after femoral neck fractures? A retrospective study in 112 elderly patients

BACKGROUND

Radiographic parameters and indices obtained from hip x-rays are a potential tool to promptly estimate bone quality in elderly hip fracture patients. Preoperative decision in whether to use cemented or cement augmented implants might be supported by this information and thus improve patient safety. Subsequently, this study was conducted to evaluate radiographic parameters as a prescreening tool for bone quality.

METHODS

A retrospective analysis of 112 elderly patients with a femoral neck fracture after low-energy trauma was performed (81 % female, 19 % male). Three radiological indices were calculated on hip x-rays: cortical index antero-posterior CTI (ap), cortical index lateral CTI (lat) and canal to calcar ratio CCR. These indices were analyzed for correlations with DXA T-Scores and serum 25-hydroxyvitamin D (25(OH)D) using the Spearman test.

RESULTS

Median age of patients was 80 (IQR 72-86) years. A linear correlation was found for CTI (lat) and T-Score at the total hip (p < 0.001, r = 0.589), femoral neck (p = 0.005, r = 0.405) and the lumbar spine (p = 0.002, r = 0.299). A significant correlation was also indicated between CTI (lat) and 25(OH)D (p = 0.002, r = 0.293). CTI (lat) at a cut-off level of 0.4 showed a sensitivity of 79 % and a specificity of 56 % in predicting a T-score ≤ -2.5 at the total hip. Gender specific analysis revealed a higher sensitivity (100 %) and specificity (73 %) of CTI (lat) at a cut-off level of 0.4 for men. For severe vitamin D deficiency (<10 ng/ml) sensitivity and specificity were 75 % and 65 %.

CONCLUSION

Radiographic indices as the CTI (lat) exhibit a direct correlation to BMD and serum 25OH vitamin D levels. A CTI (lat) cut-off level of 0.4 is recommended for identifying patients at risk of osteoporosis expressed by T-Scores ≤ -2.5 and severe vitamin D deficiency.

The Singh Index does not correlate with bone mineral density (BMD) measured with dual energy X-ray absorptiometry (DXA) or peripheral quantitative computed tomography (pQCT)

The Singh Index (SI), a classification system by which the severity of osteoporosis is assessed based on plain radiographs, is a renowned, simple and inexpensive form of evaluating osteoporosis. The aim of this study was to evaluate the correlation between the SI and bone mineral density (BMD) as measured by dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). The SI was evaluated in 128 cadaveric femora (64 patients, mean age 66.7 years, range 24-89 years) by three independent observers, all blinded to plain radiographs. BMD was also analysed by means of DXA and pQCT in the cadaveric femora. The mean interrater correlation was found to be 0.629. The correlation of the mean BMD measured by DXA (DXA-BMD) and SI was found to be poor, with r = 0.49. The corresponding sensitivity of 45.2 % and specificity of 92.3 % were even poor. The BMD measured by pQCT (pQCT-BMD) also revealed a poor correlation with SI, such that r = 0.337 and r = 0.428 for the trochanteric and neck regions, respectively. Due to the poor correlation of the SI with BMD and the poorer interrater correlation, the SI should be rejected as a tool for evaluating osteoporosis. The SI was found to be too imprecise and is therefore unsuitable for diagnosing osteoporosis and osteopenia.

The relationship between radiological parameters from plain hip radiographs and bone mineral density in a Korean population

The purpose of this study was to investigate the association of the Singh index, cortical thickness index (CTI) and calcar-to-canal (CC) ratio with bone mineral density (BMD) as well as their relationship with physical parameters [age, gender, height, and body mass index (BMI)] in order to assess their potential as an indirect indicator of osteoporosis. BMD, Singh index, CTI and CC ratio as well as the physical parameters were obtained from hip radiographs and clinical records of 140 Korean adults. Linear relationships between the areal BMD of the femoral neck and the parameters as well as between each parameter were obtained. To determine the association between BMD and the radiological parameters, multiple regression analyses were performed after adjusting for the four physical parameters. The CTI was positively associated with BMD (p = 0.040), whereas the Singh index (p = 0.209) and CC ratio (p = 0.655) were not. The CTI was negatively associated with age (p = 0.02) and positively associated with height (p = 0.0001) and BMI (p = 0.001). The CC ratio was also positively associated with age (p = 0.0001) and negatively associated with height (p = 0.033). In conclusion, of three parameters available from plain radiograph (age, height, BMI), only CTI was significantly associated with BMD. CTI can provide a tool for rapid assessment of osteoporosis from plain hip radiographs.

Correlation of plain radiographic indices of the hip with quantitative bone mineral density

Radiographic parameters of the hip can be useful as an indication of bone mineral density at the femoral neck. Measurements available from routine hip radiographs were correlated with DXA values. Although radiographs are not a test for osteoporosis, measurements of cortical thickness provide information useful for referral for osteoporosis assessment.

INTRODUCTION

Plain hip radiographs are widely used for evaluation of hip pathology in osteoarthritis. A purpose of this study was to determine whether there are relationships between radiographic parameters of bone structure and bone mineral density T-scores, as assessed by dual energy x-ray absorptiometry (DXA).

METHODS

Pre-operative radiographs of 32 postmenopausal, osteoarthritic women undergoing hip arthroplasty were evaluated. Radiographic parameters including the Singh index, Dorr classification, canal-to-calcar ratio, and cortical thickness indices (CTI) were measured and compared with T-score, serum 25 hydroxyvitamin D levels, body mass index (BMI), and body weight.

RESULTS

The T-score at the femoral neck for type C bone was significantly lower than that of type A (p = 0.041). The CTIs were correlated positively with T-scores for anteroposterior radiographs (r = 0.5814, p = 0.0005), and for lateral radiographs (r = 0.571, p = 0.0006). A threshold for lateral CTI set at a value of < or =0.40 results in sensitivity of 0.85 and specificity of 0.79 to segregate the osteoporotic and non-osteoporotic patients.

CONCLUSION

Femurs with small radiographic cortical thickness indices had lower T-scores. Finding a radiographic hip cortical thickness index (LAT) with a value of < or =0.40 should be an alert for referral for osteoporosis evaluation and bone mineral density testing.

Assessment of risk factors for second hip fractures in Japanese elderly

In an attempt to identify a cohort with a high risk of suffering a fracture of the contralateral hip (second hip fracture), we assessed patients who had suffered hip fracture. A total of 714 patients (130 men and 584 women) were prospectively followed to determine those who suffered a second hip fracture. Pathologic hip fractures and fractures that emerged from high-energy trauma were excluded from the analysis. Age, gender, Singh Index (SI), fracture type, cognitive impairment, and comorbid medical conditions were investigated as medical predictors. The 714 patients were observed for 1,579.5 person-years (mean: 2.4+/-1.4 years per patient). During the observation period, 45 second hip fractures were identified (bilateral group), giving an overall incidence of 0.029 per person-year. The annual incidence rate declined linearly from the occasion of the initial fracture. Furthermore, the second hip fracture tended to occur increasingly within 8 months after the initial hip fracture. The second hip fracture was of the same type (trochanteric or cervical) in 79% of the trochanteric and 71% of the cervical fractures. There was no significant difference in the incidence of second hip fracture by gender or age. In addition, there was no significant difference in the distribution of SI grades of the unfractured hip at the initial hip fracture between the 669 patients who had not suffered a second hip fracture (unilateral group) and the bilateral group. Cox proportional hazard regression analysis revealed that increased risk of a second hip fracture was associated with senile dementia and Parkinson's disease. We concluded that careful follow-up of hip fracture patients associated with senile dementia and Parkinson's disease might effectively prevent the incidence of a second hip fracture.

Bone fractal analysis

Fractal analysis is a quantitative method used to evaluate complex anatomic findings in their elementary component. Its application to biologic images, particularly to cancellous bones, has been well practiced within the past few years. The aims of these applications are to assess changes in bone and the loss of spongious architecture, indicate bone fragility, and to show the increased risk for fracture in primary or secondary osteoporosis. The applications are very promising to help complete the studies that can define bone density (bone mineral density by dual energy x-ray absorptiometry or quantitative computed tomography), and also have the capacity to distinguish the patients with a high or low risk for fracture. Their extension to the clinical fields, to define a test for fracture risk, is still limited by difficult application to the medical quantitative imaging of bones, between correct application at superficial bones and unreliable application to deep bones. The future evolution and validity do not depend upon fractal methods but upon well-detailed imaging of the bones in clinical conditions.

Osteoporosis and anterior femoral notching in periprosthetic supracondylar femoral fractures: a biomechanical analysis

BACKGROUND

This biomechanical study was designed to evaluate the predictive ability of dual-energy x-ray absorptiometry, cortical bone geometry as determined with computed tomography, and radiography in the assessment of torsional load to failure in femora with and without notching.

METHODS

Thirteen matched pairs of cadaveric femora were randomized into two groups: a notched group, which consisted of femora with a 3-mm anterior cortical defect, and an unnotched group of controls. Each pair then underwent torsional load to failure. The ability of a number of measures to predict femoral torsional load to failure was assessed with use of regression analysis. These measures included dual-energy x-ray absorptiometry scans of the proximal and the distal part of the femur, geometric measures of both anterior and posterior cortical thickness as well as the polar moment of inertia of the distal part of the femur as calculated on computed tomography scans, and the Singh osteoporosis index as determined on radiographs.

RESULTS

The torsional load to failure averaged 98.9 N-m for the notched femora and 143.9 N-m for the controls; the difference was significant (p < 0.01). Although several variables correlated with torsional load to failure, distal femoral bone-mineral density demonstrated the highest significant correlation (r = 0.85; p < 0.001). Moreover, multiple regression analysis showed that a combination of distal femoral bone-mineral density and polar moment of inertia calculated with the posterior cortical thickness (adjusted r (2) = 0.79; p < 0.001) had the strongest prediction of torsional load to failure in the notched group. The addition of other measures of cortical bone geometry, proximal femoral bone-mineral density, or radiographic evidence of osteopenia did not significantly increase the model's predictive ability.

CONCLUSIONS

Femoral notching significantly decreases distal femoral torsional load to failure and is best predicted by a combination of the measures of distal femoral bone-mineral density and polar moment of inertia. Together, these values account for the amount of bone mass present and the stability provided by the cortical shell architecture.

Outcome of hip fracture in older Irish women: a 2-year follow-up of subjects in a case-control study

To assess outcome after hip fracture in older Irish women, 106 consecutive females aged over 50 years admitted to a general hospital with a hip fracture were compared to 89 age- and gender-matched controls from the same catchment area. Interview-based data were collected on socio-demographic factors, mobility and activities of daily living before recruitment and 2 years later. Information was also collected on residence, further falls and fractures and use of health and community support services during the 2-year period. Mortality at 2 years was higher in cases (23.6%) compared to controls (10.1%; P = 0.01). Cases were significantly less mobile and more dependent in the activities of daily living. Of the cases who were community dwellers at baseline, 26.6% were institutionalised at 2 years compared with 9.2% of controls (P = 0.01). During the 2 years cases were significantly more likely to have multiple falls and a further hip or pelvic fracture. Hospital and nursing home admissions and use of physiotherapy, day centre and home help services were also significantly greater among cases. The marked adverse impact of hip fracture reported in this study underlines the importance of public health strategies to prevent these injuries in older people.

Assessment of osteoporosis using standard radiographs of the wrist

BACKGROUND

This study evaluated the ability of the orthopaedic surgeon to radiographically assess bone density in the wrist with sufficient accuracy to determine which patients require treatment for osteoporosis.

METHODS

Thirty-eight patients with unilateral distal radius fractures, 30 of whom were female, were included in this study. The mean age was 55 years (range 45 to 82). Standard radiographs of the fractured and normal wrists were taken. Dual energy x-ray absorptiometry was performed on the normal distal radius of all patients within 1 week of their injury. The radiographs were viewed in blinded randomized fashion on two separate occasions by three orthopaedic surgeons and once by a fourth. The participants were required to determine the presence of osteoporosis. Visual analog scales (VAS) were used to evaluate (1) porosity, (2) cortical thickness, (3) trabecular thickness, and (4) the number of trabeculae in the ultradistal radius.

RESULTS

Intraobserver agreement assessing osteoporosis averaged 81% (kappa of 0.5393). VAS assessment was unreliable for all four parameters. Radiographic determination of osteoporosis had a specificity of 61% and a sensitivity of 61% using x-rays of the uninjured wrist.

CONCLUSION

We conclude that orthopaedic surgeons cannot predict with sufficient accuracy using plain x-rays whether a patient is significantly osteoporotic.

Predictors of first hip fracture and mortality post fracture in older women

BACKGROUND

Hip fracture causes significant morbidity and mortality in older women.

AIM

To document factors contributing to the risk of hip fracture in older women and to assess the effect of hip fracture on subsequent mortality.

METHODS

Case-control study of 89 women with hip fracture and 89 controls, with two-year follow-up. Singh index and bone mineral density were calculated.

RESULTS

Osteoporotic indices did not differ significantly between cases and controls. Significant predictors of risk were sleeping tablets, perception of health as fair/poor and a lower mental status score. Patients were 3.57 times more likely to die in the first year after fracture, with no difference between the groups in year two. After adjustment, hip fracture did not remain significantly associated with mortality. Inability to walk 100 yards alone prior to fracture and lower social class were significantly associated with mortality at 12 months. Age alone was significantly associated at 12-24 months.

CONCLUSIONS

Factors related to falls and fracture may be more discriminatory predictors of hip fracture risk than osteoporosis in older females. Medications for sleep should be prescribed with caution. Hip fracture may have an independent effect on one year mortality, this effect is not seen in the second year.

Optical processing of radiographic trabecular pattern versus bone mineral density of proximal femur as measures of bone strength

The purpose of the present study was to evaluate a noninvasive method that utilizes optical processing to analyze the trabecular pattern on bone radiographs. The trabecular network on proximal femur radiographs of 17 intact cadaveric femora was analyzed by optical Fourier transform, yielding a trabecular bone index (TBI) at several locations. The bone mineral density (BMD) of the proximal femur was measured by dual X-ray absorptiometry. Dimensions of the proximal femur were obtained from the radiograph. The bones were fractured in a "fall configuration" to yield the fracture load. A multiple regression model, combining only radiograph- derived parameters-bone dimensions and the TBI at the intertrochanteric region and at the greater trochanter-yielded a correlation of 0.938 with the fracture load. A model combining the BMD at the greater trochanter and at the neck yielded a correlation of 0.928 with the fracture load. When all the variables were introduced into a combined analysis, the correlation with the fracture load was 0.973. The TBI obtained by optical processing of the trabecular bone pattern on femoral radiographs together with bone dimensions derived from these radiographs may serve as an effective estimate for hip fracture risk.