Is the cortical thickness index a valid parameter to assess bone mineral density in geriatric patients with hip fractures?

Predicting fracture classification and prognosis with hounsfield units and femoral cortical index: A simple and cost-effective approach

BACKGROUND

The relationship between bone density and fracture has been widely studied and recognized, and the role of cortical bone in proximal femoral fractures has also been increasingly studied. However, both the determination of bone mineral density (BMD) and the determination of cortical mass are expensive and cumbersome. The purpose of this study is to investigate whether two readily available indicators, Hounsfield Units (HUs) and femoral cortical index (FCI), can be used to predict hip fracture classification and prognosis.

METHODS

A retrospective study was conducted on 110 patients with hip fragility fractures. Cortical index was calculated on fractured and contralateral femur FCI, with HUs calculated on the proximal femur. The correlation of the FCI and HU with diabetes, hypertension, and related indicators, such as albumin, creatinine, and urea nitrogen levels, were also analyzed in the study.

RESULTS

Both the Evans classification of intertrochanteric fractures and the Garden and Pauwels classifications of femoral neck fractures showed that as the severity of the fracture increased, the HUs and FCI decreased. Age and albumin level also had a negative correlation with HUs and FCI. There was also a significant correlation between HUs and FCI.

CONCLUSIONS

The HUs and FCI, which can be easily and quickly obtained, can be used to predict the classification and prognosis of hip fractures.

Deep learning for osteoporosis screening using an anteroposterior hip radiograph image

PURPOSE

Osteoporosis is a common bone disorder characterized by decreased bone mineral density (BMD) and increased bone fragility, which can lead to fractures and eventually cause morbidity and mortality. It is of great concern that the one-year mortality rate for osteoporotic hip fractures could be as high as 22%, regardless of the treatment. Currently, BMD measurement is the standard method for osteoporosis diagnosis, but it is costly and requires special equipment. While a plain radiograph can be obtained more simply and inexpensively, it is not used for diagnosis. Deep learning technologies had been applied to various medical contexts, yet few to osteoporosis unless they were trained on the advanced investigative images, such as computed tomography. The purpose of this study was to develop a deep learning model using the anteroposterior hip radiograph images and measure its diagnostic accuracy for osteoporosis.

METHODS

We retrospectively collected all anteroposterior hip radiograph images of patients from 2013 to 2021 at a tertiary care hospital. The BMD measurements of the included patients were reviewed, and the radiograph images that had a time interval of more than two years from the measurements were excluded. All images were randomized using a computer-generated unequal allocation into two datasets, i.e., 80% of images were used for the training dataset and the remaining 20% for the test dataset. The T score of BMD obtained from the ipsilateral femoral neck of the same patient closest to the date of the performed radiograph was chosen. The T score cutoff value of - 2.5 was used to diagnose osteoporosis. Five deep learning models were trained on the training dataset, and their diagnostic performances were evaluated using the test dataset. Finally, the best model was determined by the area under the curves (AUC).

RESULTS

A total of 363 anteroposterior hip radiograph images were identified. The average time interval between the performed radiograph and the BMD measurement was 6.6 months. Two-hundred-thirteen images were labeled as non-osteoporosis (T score >  - 2.5), and the other 150 images as osteoporosis (T score ≤  - 2.5). The best-selected deep learning model achieved an AUC of 0.91 and accuracy of 0.82.

CONCLUSIONS

This study demonstrates the potential of deep learning for osteoporosis screening using anteroposterior hip radiographs. The results suggest that the deep learning model might potentially be used as a screening tool to find patients at risk for osteoporosis to perform further BMD measurement.

Assessing the utility of osteoporosis self-assessment tool for Asians in patients undergoing hip surgery

Objectives

Diagnosis and treatment of osteoporosis are instrumental in obtaining good outcomes of hip surgery. Measuring bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA) is the gold standard for diagnosing osteoporosis. However, due to limited access to DXA, there is a need for a screening tool to identify patients at a higher risk of osteoporosis. We analyzed the potential utility of the Osteoporosis Self-assessment Tool for Asians (OSTA) as a screening tool for osteoporosis.

Methods

A total of 1378 female patients who underwent hip surgery at 8 institutions were analyzed. For each patient, the BMD of the proximal femoral region was measured by DXA (DXA-BMD), and the correlation with OSTA score (as a continuous variable) was assessed. Receiver operating characteristic (ROC) curve analysis was performed to assess the ability of OSTA score to predict osteoporosis. Lastly, the OSTA score was truncated to yield an integer (OSTA index) to clarify the percentage of patients with osteoporosis for each index.

Results

DXA-BMD showed a strong correlation with OSTA (r = 0.683; P < 0.001). On ROC curve analysis, the optimal OSTA score cut-off value of -5.4 was associated with 73.8% sensitivity and 80.9% specificity for diagnosis of osteoporosis (area under the curve: 0.842). A decrease in the OSTA index by 1 unit was associated with a 7.3% increase in the probability of osteoporosis.

Conclusions

OSTA is a potentially useful tool for screening osteoporosis in patients undergoing hip surgery. Our findings may help identify high-risk patients who require further investigation using DXA.

Cortical Thickness Index and Canal Calcar Ratio: A Comparison of Proximal Femoral Fractures and Non-Fractured Femora in Octogenarians to Centenarians

Background: The cortical thickness index (CTI) is a measure of bone quality and it correlates with the risk of proximal femoral fractures. The purpose of this study was to investigate the CTI in femoral neck, trochanteric fractures and non-fractured femora in geriatric patients and to determine whether there is a correlation between the CTI and the presence of a fracture. Methods: One hundred and fifty patients (fifty femoral neck- (FNFx), fifty trochanteric fractures (TFx) and fifty non-fractured (NFx)) with a mean age of 91 (range 80-104) years were included. Hip radiographs (antero-posterior (ap), lateral) were evaluated retrospectively. Measurements on the proximal femoral inner and outer cortices, including CTI and Dorr's canal calcar ratio (CCR), were assessed for inter-observer reliability (ICC), differences of each fracture and correlation of parameters. Results: The mean ap CTI on the affected side was 0.43, 0.45 and 0.55 for FNFx, TFx and NFx, respectively. There was a significant difference of the ap CTI and CCR comparing the injured and healthy side for both fracture cohorts (p < 0.001). Patients with FNFx or TFx had significantly lower CTI on both sides compared to the NFx group (p < 0.05). There was no difference for CTI (p = 0.527) or CCR (p = 0.291) when comparing both sides in the NFx group. The mean inter-observer reliability was good to excellent (ICC 0.88). Conclusions: In proximal femoral fractures, the CTI and CCR are reduced compared with those in non-fractured femora. Both parameters are reliable and show a good correlation in geriatric patients. Therefore, especially for geriatric patients, the CTI and CCR may help to predict fracture risk and consult patients in daily practice.

Bone remodeling and cortical thinning distal to the femoral stem: a retrospective review

INTRODUCTION

There is a paucity of information on the bone remodeling that occurs distal to the femoral stem following total hip arthroplasty as most previous studies have focused on proximal changes. In this study, we report the cortical thinning that occur distal to the femoral stem after primary total hip arthroplasty.

METHODS

A retrospective review was performed at one institution over a 5-year period. 156 primary total hip arthroplasty procedures were included. The Cortical Thickness Index (CTI) was measured on both operative and non-operative hips at 1 cm, 3 cm and 5 cm below the prosthetic stem tip on anteroposterior radiographic images pre-operatively as well as at 6 months, 12 months and 24 months post-operatively. The difference in average CTI was measured using paired t-tests.

RESULTS

There were statistically significant decreases in CTI distal to the femoral stem at 12 months and 24 months (-1.3% and -2.8%, respectively). Greater losses were seen in female patients, patients older than 75, and patients with BMI less than 35 at 6 months postoperative. There were no differences in CTI at any time point on the non-operative side.

CONCLUSION

The current study demonstrates that patients undergo bone loss as measured by CTI distal to the stem in the first 2 years following total hip arthroplasty. Comparison to the contralateral non-operative side confirms that this change is greater than expected for the natural aging process. A greater understanding of these changes will help optimize post-operative management and direct future innovations in implant design.

Comparative evaluation of radiographic morphologic parameters for predicting subsequent contralateral fragility hip fracture

PURPOSE

Subsequent contralateral fragility hip fracture (SCHF) is one of the most serious conditions in osteoporotic patients due to high morbidity and mortality. This study aimed to investigate the predictive ability of radiographic morphologic parameters for SCHF in patients diagnosed with unilateral fragility hip fractures.

METHODS

We conducted a retrospective observational study of unilateral fragility hip fracture patients between April 2016 and December 2021. Radiographic morphologic parameters, including canal-calcar ratio (CCR), cortical thickness index (CTI), canal-flare index (CFI), and morphological cortical index (MCI), were measured from patients' contralateral proximal femur anteroposterior radiographic study to evaluate the risk of SCHF. Multivariable logistic regression analysis was employed to determine the adjusted predictive ability of the radiographic morphologic parameters.

RESULTS

Of the included 459 patients, 49 (10.7%) experienced SCHF. All radiographic morphologic parameters demonstrated excellent performance in predicting SCHF. After being adjusted by patients' age, BMI, visual impairment status, and dementia, CTI revealed the greatest adjusted odds ratio for SCHF of 35.05 (95% CI 7.34 to 167.39, p < 0.001) followed by CFI (OR = 13.32; 95% CI 6.50 to 27.32, p < 0.001), MCI (OR = 5.60; 95% CI 2.84 to 11.04, p < 0.001), and CCR (OR = 4.50; 95% CI 2.32 to 8.72, p < 0.001).

CONCLUSION

CTI demonstrated the greatest odds ratio for SCHF, followed by CFI, MCI, and CCR. These radiographic morphologic parameters could provide a preliminary prediction for SCHF in elderly patients presenting with unilateral fragility hip fractures.

"Fragment Width Ratio" as a Predictor of Nonunion for Femoral Shaft Fracture With Third Fragments

Previous studies have reported that large fracture fragment with displacement might cause nonunion of femoral shaft fractures. We therefore intended to delineate significant risk factors for developing a nonunion predisposed by a major fracture fragment. We analyzed 61 patients who were operated on using interlocking nails for femoral shaft fractures from 2009 to 2018. We classified patients with modified Radiographic Union Scale for Tibia fractures scores of less than 11 or needing reoperations by 1 year postoperatively as nonunion. We thereafter measured parameters of the displaced fracture fragment and fracture site to identify the significant difference between the union and non-union groups. We also applied the receiver operating characteristic curve to demonstrate a threshold value for the fragment width (FW) ratio. Among 61 patients with complete follow-up, no significant difference was found regarding length, displacement, and angulation of fragments between patients with and without union. Except for higher mean FW (P=.03) and the FW ratio (P=.01) in patients with nonunion, the logistic regression analysis demonstrated that FW ratio significantly affected union (P=.018; odds ratio, 0.21; 95% CI, 0.001-0.522). Although a fracture fragment greater than 4 cm with displacement greater than 2 cm was reported to significantly cause nonunions, our study showed that an FW ratio greater than 0.55 instead of fragment size or displacement was predictive for the occurrence of nonunion adjoining to the fracture site. Fixation of the third fracture fragment should not be ignored for preventing a nonunion. More attention should be paid to achieve a better fixation for a major fracture fragment with an FW ratio greater than 0.55 to avoid the development of non-union following the use of interlocking nail for femoral shaft fracture. [Orthopedics. 202x;xx(x):xx-xx.].

Prediction of osteoporosis from proximal femoral cortical bone thickness and Hounsfield unit value with clinical significance

Background

Utilizing dual-energy x-ray absorptiometry (DXA) to assess bone mineral density (BMD) was not routine in many clinical scenarios, leading to missed diagnoses of osteoporosis. The objective of this study is to obtain effective parameters from hip computer tomography (CT) to screen patients with osteoporosis and predict their clinical outcomes.

Methods

A total of 375 patients with hip CT scans for intertrochanteric fracture were included. Among them, 56 patients possessed the data of both hip CT scans and DXA and were settled as a training group. The cortical bone thickness (CTh) and Hounsfield unit (HU) values were abstracted from 31 regions of interest (ROIs) of the proximal femur. In the training group, the correlations between these parameters and BMD were investigated, and their diagnostic efficiency of osteoporosis was assessed. Finally, 375 patients were divided into osteoporotic and nonosteoporotic groups based on the optimal cut-off values, and the clinical difference between subgroups was evaluated.

Results

The CTh value of ROI 21 and the HU value of ROI 14 were moderately correlated with the hip BMD [r = 0.475 and 0.445 (p < 0.001), respectively]. The best diagnostic effect could be obtained by defining osteoporosis as CTh value < 3.19 mm in ROI 21 or HU value < 424.97 HU in ROI 14, with accuracies of 0.821 and 0.883, sensitivities of 84% and 76%, and specificities of 71% and 87%, respectively. The clinical outcome of the nonosteoporotic group was better than that of the osteoporotic group regardless of the division criteria.

Conclusion

The CTh and HU values of specific cortex sites in the proximal femur were positively correlated with BMD of DXA at the hip. Thresholds for osteoporosis based on CTh and HU values could be utilized to screen osteoporosis and predict clinical outcomes.

Fracture Risk Assessment Tool Scores and Radiographical Bone Measurements in Total Hip Arthroplasty Patients

BACKGROUND

Osteoporosis is a major risk factor for periprosthetic fractures (PPFx) in total hip arthroplasty (THA) patients but is not routinely screened for in this population. Given the availability of hip x-rays and preoperative screenings, Fracture Risk Assessment Tool (FRAX) scores and radiographic bone measurements are potentially promising, novel risk stratification tools. This study aims to characterize FRAX scores and radiographic bone measurements in THA and PPFx patients.

METHODS

A retrospective chart review for demographic variables and FRAX scores was performed on 250 THA and 40 PPFx patients. Radiographic bone measurements including cortical thicknesses (both antero-posterior [AP] and lateral), canal to calcar ratio, canal flare index, and Dorr classifications were obtained from preoperative x-rays. Correlation between FRAX scores and radiographic bone measurements was investigated with linear regressions. FRAX scores and radiographic bone measurements were compared between the THA and PPFx patients. Multivariate logistic regressions were used to identify factors predicting PPFx.

RESULTS

FRAX scores were significantly correlated with both AP (P < .001) and lateral (P = .007) cortical thicknesses. Compared to THA patients, those with PPFx had significantly higher FRAX scores (P = .003) and lower AP cortical thickness (P = .005). Multivariate logistic regressions demonstrated that FRAX major osteoporotic fracture risk score and AP cortical thickness were independent predictors of PPFx (P = .001 and .024, respectively).

CONCLUSION

Cortical thicknesses are good proxy measurements of osteoporosis-related fracture risk in THA patients. In addition, both major and AP cortical thickness indices are promising tools for identifying patients who are at a high risk of PPFx in the THA population.

Comparison between headless cannulated screws and partially threaded screws in femoral neck fracture treatment: a retrospective cohort study

The choices of the treatments for femoral neck fractures (FNF) remain controversial. The purpose of this study is to evaluate the prognoses of the variable pitch fully threaded headless cannulated screws (HCS) in the fixation of femoral neck fractures and to compare them with those of partially threaded cannulated screws (PCS). Between 1st January 2012 and 31st December 2016, there were 89 patients with the main diagnose of FNF who accepted the treatment of closed reduction cannulated screw fixation in Peking University People’s Hospital. 34 cases of PCS and 23 cases of HCS met the criterion. The characteristics, prognoses and the imaging changes of all cases were described and the differences between the two groups were compared. Statistical analyses were performed using SPSS version 23.0 (SPSS Inc., USA). Mann–Whitney U test, Analysis of Variance and Chi-square test were used. Statistical significance was defined as P value (two sided) less than 0.05. There was no significant difference in the general characteristics, fracture classifications and reduction quality between the two groups. HCS group had a significant lower angle decrease rate (30.4% vs. 58.8%, P = 0.035), femoral neck shortening rate (26.1% vs. 52.9%, P = 0.044) and screw back-sliding rate (21.7% vs. 50.0%, P = 0.032), but a higher screw cut-out rate (21.7% vs. 0.0%, P = 0.008). In non-displacement fracture subgroup, HCS had significant higher Harris Score (92 vs. 90, P = 0.048). Compared with PCS, HCS had a lower screw back-sliding rate, femoral shortening rate, angle decrease rate and similar function score, but would result in more screw cut-outs in displaced FNF. As a conclusion, HCS should not be used in displaced FNF due to its higher screw cut-out rate, and its potential advantage in non-displaced FNF needs to be further proved. Further qualified investigations with a larger scale of patients and longer follow-up are needed in the future.

Correlation between plain X-ray measurements and DXA scans, and its possible use as a screening tool for performing DXA scans

PURPOSE

The purpose of this study is to determine if there is a relationship between radiological parameters measured using a plain X-ray and DXA scan score, and whether a plain X-ray can be used as surrogate imaging modality when DXA scan is not readily available.

METHODS

We included all patients who had both a DXA scan and a pelvis X-ray done from 1 January 2013 to 31 December 2017. Bone mineral density had been measured by DXA scanning of the femoral neck and the spine. Osteoporosis was defined by T-score of any site less than -2.5. Cortical thickness indices on the AP radiograph were calculated.

RESULTS

Sixty patients were involved in the study and were divided into two groups. Group A had 22 patients who had a T-Score on their DXA Scans ≤-2.5 SD at the femur neck or the spine with median ± SD (-2.5 ± 0.8, -2.8 ± 1.0), respectively. Group B had 38 patients who had a T-score on their DXA Scans of >-2.5 at the femur neck and the spine with median ± SD (-1.2 ± 0.9, -1.3 ± 1.0), respectively, which was significantly higher than the T-score of osteoporotic (group A) patients (P = .000) at both sites of measurement. The cortical thickness index (CTI) was significantly higher (P = .027) in group B mean ± SD (0.56 ± 0.07), compared with (0.51 ± 0.08) that in group A.

CONCLUSION

DXA imaging remains the gold standard for diagnosing osteoporosis and we advocate the use of CTI to detect the patients who need DXA screening in places where this modality is not readily available.

Relationships between the Bone Expression of Alzheimer's Disease-Related Genes, Bone Remodelling Genes and Cortical Bone Structure in Neck of Femur Fracture

Neck of femur (NOF) fracture is a prevalent fracture type amongst the ageing and osteoporotic populations, commonly requiring total hip replacement (THR) surgery. Increased fracture risk has also been associated with Alzheimer's disease (AD) in the aged. Here, we sought to identify possible relationships between the pathologies of osteoporosis and dementia by analysing bone expression of neurotropic or dementia-related genes in patients undergoing THR surgery for NOF fracture. Femoral bone samples from 66 NOF patients were examined for expression of the neurotropic genes amyloid precursor protein (APP), APP-like protein-2 (APLP2), Beta-Secretase Cleaving Enzyme-1 (BACE1) and nerve growth factor (NGF). Relationships were examined between the expression of these and of bone regulatory genes, systemic factors and bone structural parameters ascertained from plain radiographs. We found strong relative levels of expression and positive correlations between APP, APLP2, BACE1 and NGF levels in NOF bone. Significant correlations were found between APP, APLP2, BACE1 mRNA levels and bone remodelling genes TRAP, RANKL, and the RANKL:OPG mRNA ratio, indicative of potential functional relationships at the time of fracture. Analysis of the whole cohort, as well as non-dementia (n = 53) and dementia (n = 13) subgroups, revealed structural relationships between APP and APLP2 mRNA expression and lateral femoral cortical thickness. These findings suggest that osteoporosis and AD may share common molecular pathways of disease progression, perhaps explaining the common risk factors associated with these diseases. The observation of a potential pathologic role for AD-related genes in bone may also provide alternative treatment strategies for osteoporosis and fracture prevention.

Bone turnover markers in the early stage of rapidly progressive osteoarthritis of the hip

OBJECTIVE

Previous reports have demonstrated that patients with end-stage rapidly progressive osteoarthritis of the hip (RPOH) show significantly higher serum levels of bone turnover markers than those with osteoarthritis (OA). However, the characteristics of bone turnover markers in the early stage of RPOH remain unclear. This study aimed to elucidate the association of bone turnover markers with disease progression in the early stage of RPOH.

METHODS

This study included 29 postmenopausal female patients with joint space narrowing >2 mm demonstrated on a series of radiographs and computed tomography within 1 year following the onset of hip pain. The study also included 9 postmenopausal female patients with hip OA secondary to developmental dysplasia showing femoral head destruction. Cortical thickness index (CTI) associated with bone mineral density of the hip was analyzed. Serum concentrations of tartrate-resistant acid phosphatase-5b (TRACP-5b) and bone alkaline phosphatase (BAP) were evaluated.

RESULTS

RPOH was classified into two types on the basis of the absence (type 1, n=13) or presence (type 2, n=16) of subsequent destruction of the femoral head within 1 year following disease onset. TRACP-5b and BAP significantly increased in RPOH type 2 compared with type 1 and OA. Receiver operating characteristic curve analyses indicated that TRACP-5b and BAP could differentiate RPOH type 2 from type 1 within 1 year following the onset. CTI showed no difference among the RPOH types 1 and 2 and OA.

CONCLUSION

High serum levels of bone turnover markers may be associated with destruction of the femoral head in the early stage of RPOH.

"Ratio of fracture site diameter to isthmus femoral canal diameter" as a predictor of complication following treatment of infra-isthmal femoral shaft fracture with antegrade intramedullary nailing

INTRODUCTION

Fixation of infra-isthmus femoral shaft fracture using antegrade intramedullary (IM) nailing is difficult and is associated with a high complication rate. This study aimed to identify risk factors for complications following this procedure. The ratio of the fracture site diameter to the diameter of the femoral intramedullary canal of the isthmus (FI ratio) was evaluated as a novel parameter to predict complication.

MATERIALS AND METHODS

Patients who underwent antegrade IM nailing for infra-isthmus femoral shaft fracture between January 2008 and December 2018 and had a minimum of 12 months of follow-up were retrospectively reviewed. The primary outcome was occurrence of complication, including non-union, mal-alignment, fixation failure, or progressive loss of reduction. Logistic regression analysis was performed to identify risk factors of complication. The sensitivity and specificity of FI ratio as a predictor of complication was calculated. A receiver operating characteristic (ROC) curve was generated to establish an FI ratio threshold to predict occurrence of complication following antegrade IM nailing.

RESULTS

Sixty-five patients with a mean age of 47.1 years were included. Using univariate logistic regression analysis, comminuted fracture pattern (p=0.026), distance from screws to fracture site (< 3cm) (p=0.002), and higher FI ratio (p=0.001) were associated with complication. Using multivariate logistic regression analysis, FI ratio was identified as an independent risk factor for complication following antegrade IM nailing (p=0.038). ROC curve indicated that FI ratio ≥ 2 had sensitivity and specificity of 0.72 and 0.72, respectively, in predicting complication.

CONCLUSIONS

Our study indicates that wider intramedullary diameter at the fracture site was associated with higher complication rate following antegrade IM nailing in distal infra-isthmal femoral fractures. The FI ratio could be a reliable predictor of complication after antegrade IM nailing for such fracture, and alternative strategies should be considered for patients with higher FI ratio (≥ 2).

Characterization of rapidly progressive osteoarthritis of the hip in its early stage

OBJECTIVE

This study aimed to characterize the process of disease progression in the early stage of rapidly progressive osteoarthritis of the hip (RPOH) and clarify its association with potential pathological factors of RPOH.

METHODS

This monocentric retrospective study included 41 female patients who met the criteria for RPOH, chondrolysis >2 mm during 12 months from the onset of hip pain based on a series of radiographs and computed tomography. This study also included 9 female patients with osteoarthritis secondary to developmental dysplasia of the hip (DDH) who demonstrated chondrolysis >2 mm during 12 months from the onset of hip pain. Cortical thickness index (CTI) correlated with bone mineral density of the hip, pelvic tilt, and serum concentrations of matrix metalloproteinase (MMP)-3 were analyzed.

RESULTS

RPOH was classified into two types based on the absence (type 1, n=17) and presence (type 2, n=24) of subsequent femoral head destruction within 12 months after the onset of hip pain. MMP-3 significantly increased in RPOH type 2 compared with type 1 and DDH. Increased posterior pelvic tilt was found in RPOH type 2 compared with DDH. Logistic regression and receiver operating characteristic curve analyses indicated that MMP-3 may be associated with differentiation between RPOH types 1 and 2. No difference was found in the CTI between the RPOH types and DDH.

CONCLUSION

Disease progression of RPOH during 12 months after the onset of hip pain could be classified into two distinct types based on the absence (type 1) and presence (type 2) of femoral head destruction in association with MMP-3 and pelvic tilt as biological and mechanical factors, respectively. MMP-3 may be helpful to differentiate these two types in the early stage of RPOH.

Use of Bone Health Evaluation in Orthopedic Surgery: 2019 ISCD Official Position

This position development conference (PDC) Task Force examined the assessment of bone status in orthopedic surgery patients. Key questions included which orthopedic surgery patients should be evaluated for poor bone health prior to surgery and which subsets of patients are at high risk for poor bone health and adverse outcomes. Second, the reliability and validity of using bone densitometry techniques and measurement of specific geometries around the hip and knee before and after arthroplasty was determined. Finally, the use of computed tomography (CT) attenuation coefficients (Hounsfield units) to estimate bone quality at anatomic locations where orthopedic surgery is performed including femur, tibia, shoulder, wrist, and ankle were reviewed. The literature review identified 665 articles of which 198 met inclusion exclusion criteria and were selected based on reporting of methodology, reliability, or validity results. We recommend that the orthopedic surgeon be aware of established ISCD guidelines for determining who should have additional screening for osteoporosis. Patients with inflammatory arthritis, chronic corticosteroid use, chronic renal disease, and those with history of fracture after age 50 are at high risk of osteoporosis and adverse events from surgery and should have dual energy X-ray absorptiometry (DXA) screening before surgery. In addition to standard DXA, bone mineral density (BMD) measurement along the femur and proximal tibia is reliable and valid around implants and can provide valuable information regarding bone remodeling and identification of loosening. Attention to positioning, selection of regions of interest, and use of special techniques and software is required. Plain radiographs and CT provide simple, reliable methods to classify the shape of the proximal femur and to predict osteoporosis; these include the Dorr Classification, Cortical Index, and critical thickness. Correlation of these indices to central BMD is moderate to good. Many patients undergoing orthopedic surgery have had preoperative CT which can be utilized to assess regional quality of bone. The simplest method available on most picture archiving and communications systems is to simply measure a regions of interest and determine the mean Hounsfield units. This method has excellent reliability throughout the skeleton and has moderate correlation to DXA based on BMD. The prediction of outcome and correlation to mechanical strength of fixation of a screw or implant is unknown.

Signalling Alterations in Bones of Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) Gene Deficient Mice

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with diverse developmental roles, including differentiation of skeletal elements. It is a positive regulatory factor of chondrogenesis and osteogenic differentiation in vitro, but little is known about its in vivo role in bone formation. In our experiments, diaphyses of long bones from hind limbs of PACAP gene-deficient mice showed changes in thickness and increased staining intensity. Our main goal was to perform a detailed morphological and molecular biological analysis of femurs from PACAP knockout (KO) and wild type (WT) mice. Transverse diameter and anterior cortical bone thickness of KO femurs showed significant alterations with disturbed Ca²⁺ accumulation and collagen type I expression. Higher expression and activity of alkaline phosphatase were also observed, accompanied by increased fragility PACAP KO femurs. Increased expression of the elements of bone morphogenic protein (BMP) and hedgehog signalling was also observed, and are possibly responsible for the compensation mechanism accounting for the slight morphological changes. In summary, our results show that lack of PACAP influences molecular and biomechanical properties of bone matrix, activating various signalling cascade changes in a compensatory fashion. The increased fragility of PACAP KO femur further supports the role of endogenous PACAP in in vivo bone formation.

Radiographic predictors for bone mineral loss: Cortical thickness and index of the distal femur

OBJECTIVES

Researchers continue to seek easier ways to evaluate the quality of bone and screen for osteoporosis and osteopenia. Until recently, radiographic images of various parts of the body, except the distal femur, have been reappraised in the light of dual-energy X-ray absorptiometry (DXA) findings. The incidence of osteoporotic fractures around the knee joint in the elderly continues to increase. The aim of this study was to propose two new radiographic parameters of the distal femur for the assessment of bone quality.

METHODS

Anteroposterior radiographs of the knee and bone mineral density (BMD) and T-scores from DXA scans of 361 healthy patients were prospectively analyzed. The mean cortical bone thickness (CBTavg) and the distal femoral cortex index (DFCI) were the two parameters that were proposed and measured. Intra- and interobserver reliabilities were assessed. Correlations between the BMD and T-score and these parameters were investigated and their value in the diagnosis of osteoporosis and osteopenia was evaluated.

RESULTS

The DFCI, as a ratio, had higher reliability than the CBTavg. Both showed significant correlation with BMD and T-score. When compared with DFCI, CBTavg showed better correlation and was better for predicting osteoporosis and osteopenia.

CONCLUSION

The CBTavg and DFCI are simple and reliable screening tools for the prediction of osteoporosis and osteopenia. The CBTavg is more accurate but the DFCI is easier to use in clinical practice.Cite this article: Q-F. He, H. Sun, L-Y. Shu, Y. Zhu, X-T. Xie, Y. Zhan, C-F. Luo. Radiographic predictors for bone mineral loss: Cortical thickness and index of the distal femur. Bone Joint Res 2018;7:468-475. DOI: 10.1302/2046-3758.77.BJR-2017-0332.R1.

Cortical Thickness Index of the Proximal Femur: A Radiographic Parameter for Preliminary Assessment of Bone Mineral Density and Osteoporosis Status in the Age 50 Years and Over Population

BACKGROUND

Bone mineral density (BMD) is the indicator of bone quality in at-risk individuals. Along with the fracture risk assessment tool (FRAX), a quick assessment of BMD from routine radiographs may be useful in the case of lacking X-ray absorptiometry data. This study aimed to investigate the correlation of cortical thickness index (CTI) and canal flare index (CFI) with BMD and FRAX and to evaluate their ability to predict femoral neck BMD (nBMD) and FRAX in the general elderly population.

METHODS

A total of 560 volunteers (age ≥ 50 years) who underwent hip-spine X-ray, BMD scanning and FRAX calculation were retrospectively reviewed. CTI and CFI were measured on anteroposterior radiographs and analyzed for their correlation with BMD and FRAX and for their ability to predict nBMD. The ability of CTI to predict osteoporosis status (OPS) and fracture risk status (FRS) was also investigated and the threshold values were calculated. All the analyses were performed separately on male and female subjects.

RESULTS

Significant differences in CTI, CFI, nBMD and FRAX between males and females were observed. CTI and CFI demonstrated significant positive correlation with nBMD and FRAX (all p < 0.001) in both males and females. CTI, height, and weight significantly predicted nBMD. CTI statistically predicted OPS and FRS, and the values of 0.56 and 0.62 were computed as CTI thresholds for males and females, respectively.

CONCLUSIONS

CTI was significantly correlated with nBMD and it predicted nBMD at good prediction levels. Therefore, CTI may be used as a supportive tool in the assessment of OPS and FRS besides BMD and FRAX in clinical practice.

Injuries of the trochanteric region: can analysis of radiographic indices help in prediction of recurrent osteoporotic hip fractures?

Objective: In a context of bone fragility, primitive and subsequent fractures are a growing problem in the industrialized countries where the mean age of the population is constantly increasing. Among the various factors that favor a fragility fracture, the most important is osteoporosis, a pathology that can be prevented through diagnostic screenings and treated by pharmacological and rehabilitative therapies. The aim of this study is to identify the subjects who are likely to have a higher risk of subsequent fractures of the trochanteric region through a retrospective radiographic evaluation of patients affected by low-energy trochanteric fractures and operated by intramedullary fixation between June 2013 and June 2015, so they can be targeted for prevention interventions. Materials and Methods: Three hundred and sixty-one patients yet alive were analyzed 2 years after surgery. Fifty-one (group 1), characterized by another contralateral trochanteric femoral fracture, were included. All subjects were retrospectively examined with the analysis of contralateral femur X-ray performed at the time of initial trauma in order to detect a condition of bone fragility and a predisposition to fractures by evaluating three radiographic indices (Singh index, Dorr’s classification and Cortical Thickness Index). Patients of group 1 were compared to the other 310 patients (group 2) affected by isolated trochanteric fracture. Results: Group 1 had all radiographic indices worse than group 2. Conclusions: The results observed suggest that orthopedists can use radiographic indices, in particular Cortical Thickness Index, as a valuable, simple and inexpensive screening tool for prevention of recurrent osteoporotic fractures.(www.actabiomedica.it)

Injuries of the trochanteric region: can analysis of radiographic indices help in prediction of recurrent osteoporotic hip fractures?

OBJECTIVE

In a context of bone fragility, primitive and subsequent fractures are a growing problem in the industrialized countries where the mean age of the population is constantly increasing. Among the various factors that favor a fragility fracture, the most important is osteoporosis, a pathology that can be prevented through diagnostic screenings and treated by pharmacological and rehabilitative therapies. The aim of this study is to identify the subjects who are likely to have a higher risk of subsequent fractures of the trochanteric region through a retrospective radiographic evaluation of patients affected by low-energy trochanteric fractures and operated by intramedullary fixation between June 2013 and June 2015, so they can be targeted for prevention interventions.

MATERIALS AND METHODS

Three hundred and sixty-one patients yet alive were analyzed 2 years after surgery. Fifty-one (group 1), characterized by another contralateral trochanteric femoral fracture, were included. All subjects were retrospectively examined with the analysis of contralateral femur X-ray performed at the time of initial trauma in order to detect a condition of bone fragility and a predisposition to fractures by evaluating three radiographic indices (Singh index, Dorr's classification and Cortical Thickness Index). Patients of group 1 were compared to the other 310 patients (group 2) affected by isolated trochanteric fracture.

RESULTS

Group 1 had all radiographic indices worse than group 2.

CONCLUSIONS

The results observed suggest that orthopedists can use radiographic indices, in particular Cortical Thickness Index, as a valuable, simple and inexpensive screening tool for prevention of recurrent osteoporotic fractures.

Humeral head circle-fit method greatly increases reliability and accuracy when measuring anterior-posterior radiographs of the proximal humerus

Measurements made on routine A-P radiographs can predict strength/quality of the proximal humerus, as shown in terms of two easy-to-measure parameters: Cortical index (CI) and mean-combined cortical thickness (MCCT). Because of high variability inherent when using established methods to measure these parameters, we describe a new orientation system. Using digitized radiographs of 33 adult proximal humeri, five observers measured anatomical reference locations in accordance with: (i) Tingart et al. (2003) method, (ii) Mather et al. (2013) method, and (iii) our new humeral head Circle-Fit method (CFM). The Tingart and Mather methods measure CI and MCCT with respect to upper and lower edges of 20 mm tall rectangles fit to a proximal diaphyseal location where endosteal (Tingart) or periosteal (Mather) cortical margins become parallel. But high intra- and inter-observer variability occurs when placing the rectangles because of uncertainty in identifying cortical parallelism. With the CFM an adjustable circle is fit to the humeral head articular surface, which reliably and easily establishes a proximal metaphyseal landmark (M1) at the surgical neck. Distal locations are then designated at successive 10 mm increments below M1, including a second metaphyseal landmark (M2) followed by diaphyseal (D) locations (D1, D2 ⋯D6). D1 corresponds most closely to the proximal edges of the rectangles used in the other methods. Results showed minimal inter-observer variations (mean error, 1.5 ± 1.1 mm) when the CFM is used to establish diaphyseal locations for making CI and MCCT measurements when compared to each of the other methods (mean error range, 10.7 ± 5.9 to 13.3 ± 6.7 mm) (p < 0.001). © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2313-2322, 2017.

[Imaging features of hip joint in patients with ankylosing spondylitis undergoing total hip arthroplasty]

Objective

To study the imaging features of the hip joint by measuring the imaging parameters of spine, pelvis, and hip joint before and after total hip arthroplasty (THA) in patients with ankylosing spondylitis (AS) undergoing THA so as to provide reference for selection of operation methods and prosthesis.

Methods

Between January and July 2015, 38 patients (56 hips) with AS underwent primary THA as AS group, and 36 patients (45 hips) with osteonecrosis of the femoral head underwent THA as control group. There was no significant difference in side ( χ2=1.14, P=0.95). The acetabular abduction angle (ABA), acetabular anteversion angle (AVA), center collum diaphyseal (CCD), offset, height from rotation center to lesser trochanter (HRCLT), femoral intertrochanteric distance (FID) were measured by CT three-dimensional morphology. The canal flare index (CFI), cortical thickness index (CTI), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were measured by X-ray film before operation. The AVA, ABA, and the filling ratio were measured on the postoperative X-ray film.

Results

There was no significant difference in preoperative AVA and ABA and postoperative ABA between 2 groups ( P>0.05), but significant difference was found in postoperative AVA ( t=6.71, P=0.00). The mean PI, SS, and PT in AS group were 48.37° (range, 41-58°), 5.64°(range, 2-11°), and 12.85° (range, 5-26°), respectively. There was significant difference in CCD, CFI, and CTI between 2 groups ( t=3.63, P=0.04; t=5.12, P=0.02; t=3.91, P=0.04), but offset, HRCLT, and FID all showed no significant difference ( t=0.41, P=0.36; t=0.33, P=0.56; t=0.59, P=0.12). On the basis of the Noble classification, medullary cavity of the femur was rated as chimney type, ordinary type, and champagne flute type in 32, 18, and 6 hips of AS group, and in 4, 28, and 13 hips of control group respectively. Filling ratio of distal segment in AS group was significantly lower than that in control group ( t=5.64, P=0.02), but there was no significant difference in the filling ratio of middle and proximal segments between 2 groups ( t=0.29, P=0.61; t=0.55, P=0.13).

Conclusion

Compared with patients having osteonecrosis of the femeral head, there is no significant difference in preoperative AVA and ABA, but postoperative AVA significantly increase in patients with AS. Because AS patients have mainly chimney type medullary cavity of the femur, the filling ratio of middle and distal segment is lower when tapered stems are used, and the filling ratio of anatomic stems is higher.

Hip fractures in the elderly: The role of cortical bone

INTRODUCTION

Osteoporosis is characterised by poor bone quality arising from alterations to trabecular bone. However, recent studies have also described an important role of alterations to cortical bone in the physiopathology of osteoporosis. Although dual-energy X-ray absorptiometry (DXA) is a valid method to assess bone mineral density (BMD), real bone fragility in the presence of comorbidities cannot be evaluated with this method. The aim of this study was to evaluate if cortical thickness could be a good parameter to detect bone fragility in patients with hip fracture, independent of BMD.

METHODS

A retrospective study was conducted on 100 patients with hip fragility fractures. Cortical index was calculated on fractured femur (femoral cortical index [FCI]) and, when possible, on proximal humerus (humeral cortical index [HCI]). All patients underwent densitometric evaluation by DXA.

RESULTS

Average value of FCI was 0.43 and of HCI was 0.25. Low values of FCI were found in 21 patients with normal or osteopenic values of BMD, while low values of HCI were found in three patients with non-osteoporotic values of BMD.

DISCUSSION AND CONCLUSION

Cortical thinning measured from X-Ray of the femur identifies 21% additional fracture cases over that identified by a T-score <-2.5 (57%). FCI could be a useful tool to evaluate bone fragility and to predict fracture risk even in patients with normal and osteopenic BMD.

Cortical Bone Thickness of the Distal Part of the Tibia Predicts Bone Mineral Density

BACKGROUND

Poor bone density may affect surgical planning, treatment outcome, and postoperative protocols. Many patients with foot and ankle problems have not undergone a dual x-ray absorptiometry (DXA) scan, which is currently the gold standard for determining bone density. The purpose of this study was to determine if the cortical bone thickness (CBT) of the distal part of the tibia measured on radiographs correlated with bone mineral density.

METHODS

After exclusion criteria were applied, 167 consecutive adult patients (mean age and standard deviation [SD], 62 ± 11.62 years) who had had standardized ankle radiographs and a DXA scan within 6 months of each other were included in this retrospective study. The CBT was measured with both the gauge and the average method on standardized anteroposterior, lateral, and hindfoot alignment radiographs. The relationship between CBT in the distal part of the tibia and DXA findings in the hip, proximal part of the femur, and lumbar spine was assessed with Pearson correlations. The interrater and intrarater reliability of CBT measurements was assessed with intraclass correlation coefficients. Subgroup analysis was performed to determine the ability of CBT thresholds to predict osteoporosis.

RESULTS

Average CBT measurements on the anteroposterior, lateral, and hindfoot alignment views strongly correlated with DXA findings in the proximal part of the femur (r = 0.70, 0.64, and 0.55, respectively; p < 0.0001), the hip (r = 0.74, 0.67, and 0.53; p < 0.0001), and the lumbar spine (r = 0.61, 0.60, and 0.47; p < 0.0001). The interrater and intrarater reliability of the CBT measurements was excellent. Use of a 3.5-mm average CBT of the distal part of the tibia on the anteroposterior view as the threshold value for predicting osteoporosis (T score less than -2.5) had a sensitivity of 100%, a specificity of 25%, an accuracy of 33%, a positive predictive value of 19%, and a negative predictive value of 100%.

CONCLUSIONS

Measurement of the average CBT of the distal part of the tibia is a quick and reliable method for obtaining information on bone quality. CBT measured on standard ankle radiographs correlated strongly with DXA results and may prove to be a useful screening tool for osteoporosis.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Femoral cortical index: an indicator of poor bone quality in patient with hip fracture

BACKGROUND

Osteoporosis is a common disease in elderly, characterized by poor bone quality as a result of alterations affecting trabecular bone. However, recent studies have described also an important role of alterations of cortical bone in the physiopathology of osteoporosis. Although dual-energy X-ray absorptiometry (DXA) is a valid method to assess bone mineral density, in the presence of comorbidities real bone fragility is unable to be evaluated. The number of hip fractures is rising, especially in people over 85 years old.

AIMS

The aim is to evaluate an alternative method so that it can indicate fracture risk, independent of bone mineral density (BMD). Femoral cortical index (FCI) assesses cortical bone stock using femur X-ray.

METHODS

A retrospective study has been conducted on 152 patients with hip fragility fractures. FCI has been calculated on fractured femur and on the opposite side. The presence of comorbidities, osteoporosis risk factors, vitamin D levels, and BMD have been analyzed for each patient.

RESULTS

Average values of FCI have been 0.42 for fractured femurs and 0.48 at the opposite side with a statistically significant difference (p = 0.002). Patients with severe hypovitaminosis D had a minor FCI compared to those with moderate deficiency (0.41 vs. 0.46, p < 0.011). 42 patients (27.6%) with osteopenic or normal BMD have presented low values of FCI.

DISCUSSION AND CONCLUSION

A significant correlation among low values of FCI, comorbidities, severe hypovitaminosis D. and BMD in patients with hip fractures has been found. FCI could be a useful tool to evaluate bone fragility and to predict fracture risk even in the normal and osteopenic BMD patients.