Variation in bone mineral density by anatomical site in patients with proximal humeral fractures

The observation that older men suffer from hip fracture at DXA T-scores higher than older women and a proposal of a new low BMD category, osteofrailia, for predicting fracture risk in older men

The clinical significance of osteoporosis lies in the occurrence of fragility fractures (FFx), and the most relevant fracture site is the hip. The T-score is defined as follows: (BMDpatient-BMDyoung adult mean)/SDyoung adult population, where BMD is bone mineral density and SD is the standard deviation. When the femoral neck (FN) is measured in adult Caucasian women, a cutpoint value of patient BMD of 2.5 SD below the young adult mean BMD results in a prevalence the same as the lifetime risk of hip FFx for Caucasian women. The FN T-score criterion for classifying osteoporosis in older Caucasian men has been provisionally recommended to be - 2.5, but debates remain. Based on a systematic literature review, we noted that older men suffer from hip FFx at a FN T-score approximately 0.5-0.6 higher than older women. While the mean hip FFx FN T-score of around - 2.9 for women lies below - 2.5, the mean hip FF FN T-score of around - 2.33 for men lies above - 2.5. This is likely associated with that older male populations have a higher mean T-score than older female populations. We propose a new category of low BMD status, osteofrailia, for older Caucasian men with T-score ≤  - 2 (T-score ≤  - 2.1 for older Chinese men) who are likely to suffer from hip FFx. The group with T-score ≤  - 2 for older Caucasian men is comparable in prevalence to the group with T-score ≤  - 2.5 for older Caucasian women. However, older men in such category on average have only half the FFx risk as that of older women with osteoporotic T-score.

Deltoid tuberosity index for proximal humerus fracture: reliability and a predictor of systemic osteoporosis in an Asian population

HYPOTHESIS AND BACKGROUND

Fragility fracture of the proximal humerus is a common occurrence. Current literature suggests that poor local bone density is a significant predictor of surgical fixation failure. The deltoid tuberosity index (DTI) is a simple radiographic tool that strongly correlates with local humeral bone mineral density (BMD), aiding surgical planning to consider adjuncts or arthroplasty. However, there is a lack of data in the reliability of assessment of DTI, as well as its correlation to systemic osteoporosis. Our study investigates the reliability of DTI as a predictor of systemic osteoporosis.

METHODS

A retrospective cohort of patients with proximal humeral fracture (PHF) treated at a trauma center in Singapore from August 2017 to July 2018 were recruited. Four raters at different levels of varying clinical seniority measured DTI using shoulder radiographs. The dual-energy x-ray absorptiometry (DEXA) BMD scan of the hip and lumbar spine was used to diagnose osteoporosis. Area under the receiver operating characteristic curve analysis was calculated to study the diagnostic utility of DTI for predicting the risk of osteoporosis.

RESULTS

Our study sample had 87 patients comprising 18 men and 69 women, mainly of Chinese ethnicity (84%), and with a mean age of 69.7 years (standard deviation 9.52, range 39-92). For assessment of DTI, there was good intrarater reliability among 4 raters (correlation coefficient range 0.805-0.843) and excellent interrater reliability between all raters (intraclass correlation coefficient 0.898, 95% confidence interval [CI] 0.784-0.950, P < .001). Based on the BMD, 55.2% (n = 48) had osteoporosis, with a T score <2.5. The highest correlation of DTI to BMD was with femoral neck density at 0.580. The DTI cutoff of 1.6 had the highest combined sensitivity and false positive rate, with areas under the curve of 0.682 (95% CI 0.564-0.799) for the overall population and 0.706 (95% CI 0.569-0.842) for patients aged <75 years.

CONCLUSION

The DTI is a simple and reliable tool and has a strong applicability in clinical practice to enhance preoperative planning in the surgical fixation of PHF. DTI with a cutoff of 1.6 may help prompt clinicians to initiate workup and thus manage underlying osteoporosis.

The correlation between bone mineral density measured at the forearm and at the lumbar spine or femoral neck: a systematic review and meta-analysis

BACKGROUND

Current guidelines for osteoporosis diagnosis do not recommend forearm dual-energy X-ray absorptiometry (DXA) as a standard tool, except in specific cases. This systematic review and meta-analysis investigates the potential correlation between forearm BMD and BMD at the lumbar and/or hip sites.

METHODS

The protocol was registered in PROSPERO (CRD42024568756), and the study adhered to the PRISMA guidelines. Major databases were systematically searched from their inception until August 2024 to identify studies evaluating the ability of forearm DXA scans to detect osteoporosis, particularly in comparison to central sites like the femoral neck and lumbar spine. A meta-analysis was conducted on studies that reported correlation coefficients between these measurements. Quality assessment was conducted independently by 3 reviewers following Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria. Additionally, a narrative synthesis of the main findings across different patient groups was performed.

RESULTS

Thirteen studies were included. Published between 1992 and 2023, these studies involved 5941 participants. Forearm scans exhibited strong correlations with lumbar and femoral sites (pooled effect size 0.603, 95%CI 0.579-0.627 and 0.641, 95%IC 0.600-0.680, respectively) demonstrating good predictive value for central osteoporosis. Despite some result variations, forearm DXA scanning emerged as a valid method, especially when lumbar and femoral measures are challenging.

CONCLUSIONS

A DXA scan of the distal forearm proves to be a valuable supplementary tool for identifying osteoporotic conditions. This could be particularly relevant in older patients, where conducting lumbar or hip scans is often challenging or not feasible.

Clinical Characteristics and Bone Mineral Density Score in Post-Stroke Neuromuscular Deficit

Background

Disuse osteoporosis in hemiparetic patients often results in significant morbidity, decreased quality of life, and different clinical characteristics. The study aimed to investigate the effect of these clinical factors on bone mineral density (BMD).

Methods

This was an analytical observational study with a cross-sectional method evaluating hemiparetic patients at Cipto Mangunkusumo Hospital from 2018 to 2019. BMD (g/cm2) was assessed using dual energy X-ray absorptiometry (DXA) on the spine and both sides of the body. The relationship and correlation between BMD and delta BMD scores with clinical characteristics were analyzed. A linear regression test was used to assess the correlation between variables.

Results

A total of 34 participants were recruited for this study. There was a difference between the healthy and paretic side of BMD of both hip and wrist (P < 0.001), strong positive correlation between the onset of hemiparesis and wrist and hip delta BMD (r = 0.779, P = 0.001 and r = 0.791, P = 0.001), and significant association between delta BMD and age and motor strength. Multivariate analysis shows that the onset of hemiparesis was a strong predictor of delta BMD (aR2 wrist = 0.486, aR2 hip = 0.614). There was a 7.36% decrease in the mean BMD score of the paretic side compared to the non-paretic side.

Conclusion

A low BMD score is prevalent in seven out of 10 patients with post-stroke neuromuscular deficit. Age, limb strength, the onset of hemiparesis, and rehabilitation compliance are associated with decreased BMD among patients with post-stroke neuromuscular deficit.

Comparative Analysis of Bone Mineral Density of the Lumbar Spine, Hip, and Proximal Humerus in Patients with Unilateral Rotator Cuff Tears

Background

The proximal humerus, a common site for osteoporotic fractures, is frequently overlooked in osteoporosis evaluations. This study aimed to evaluate the relationship between the conventional bone mineral density (BMD) measurement (at the lumbar spine and femur) and the BMD measurement at both proximal humeri (the asymptomatic side and the side with a rotator cuff tear [RCT]) in patients with unilateral RCT. Furthermore, we investigated clinical features indicative of osteoporosis in RCT patients and assessed the utility of proximal humerus BMD measurements.

Methods

From April 2020 to September 2020, 87 patients who underwent arthroscopic repairs for unilateral RCTs were examined for age, onset, body mass index, menopause duration, passive range of motion, global fatty degeneration index, and RCT and retraction size. The regions of interest (ROIs) for the conventional BMD included the lumbar spine, femur neck, femur trochanter, and total femur. For the proximal humerus BMD, the ROIs included the head, lesser tuberosity, greater tuberosity (medial, middle, and lateral rows), and total humerus.

Results

The conventional BMD of the lumbar spine, femur neck, femur trochanter, and femur total were 1.090, 0.856, 0.781, and 0.945 g/cm2, respectively. The head, lesser tuberosity, greater tuberosity (medial, middle, and lateral rows), and total BMD of the asymptomatic-side proximal humerus were 0.547, 0.544, 0.697, 0.642, 0.554, and 0.610 g/cm2, respectively. The average of proximal humerus BMD was significantly lower than that of conventional BMD (p < 0.001). All ROIs BMD of the RCT-side proximal humerus were 0.497, 0.507, 0.619, 0.598, 0.517, and 0.560 g/cm2. There was no correlation between the conventional BMD and each proximal humerus BMD. All ROI BMD of the RCT-side proximal humerus was not significant in the multiple regression analysis with age, onset, body mass index, passive range of motion, global fatty degeneration index, and RCT and retraction size (p > 0.05).

Conclusions

The proximal humerus BMD showed a completely different trend from that of conventional BMD and had no significant association with clinical features. Therefore, the proximal humerus BMD needs to be measured separately from the conventional BMD, as it may provide important information before rotator cuff repair surgery.

A comparison between IBEX bone health applied to digital radiographs and dual-energy X-ray absorptiometry at the distal-third and ultra-distal regions of the radius

BACKGROUND

In an ageing population, low impact fragility fractures are becoming increasingly common. However, fracture risk can be reduced where low bone density can be identified at an early stage. In this study we aim to demonstrate that IBEX Bone Health (IBEX BH) can provide a clinically useful prediction from wrist radiographs of aBMD and T-score at the ultra-distal (UD) and distal-third (DT) regions of the radius.

METHODS

A 261-participant single-centre, non-randomised, prospective, study was carried out to compare a) IBEX BH, a quantitative digital radiography software device, to b) Dual-energy X-ray Absorptiometry (DXA). A total of 257 participants with wrist digital radiograph (DR), forearm DXA pairs were included in the analysis after exclusions.

RESULTS

The adjusted R2 value for IBEX BH outputs to the radial areal bone mineral density (aBMD) produced by a GE Lunar DXA system for the UD region is 0.87 (99% Confidence Interval (CI) [0.84, 0.89]). The adjusted R2 value for IBEX BH outputs to aBMD for the DT region is 0.88 (99% CI [0.85, 0.90]). The Area Under the Receiver Operating Characteristic curve (AUC) for the forearm T-score ≤  - 2.5 risk prediction model at the UD region is 0.95 (99% CI [0.93, 0.98]). The AUC for the forearm T-score ≤  - 2.5 risk prediction model at the DT region is 0.98 (99% CI [0.97, 0.99]).

CONCLUSION

From a DR of the wrist, IBEX BH provides a clinically useful i) estimate of aBMD at the two regions of interest on the radius and ii) risk prediction model of forearm T-score ≤  - 2.5 at the UD and DT regions.

Does the proximal humeral bone quality influence alignment after reverse total shoulder arthroplasty with short humeral stems?

PURPOSE

When compared to standard-length humeral stem in reverse total shoulder arthroplasty (RTSA), short humeral stems in RTSA require good proximal humeral metaphyseal bone quality to gain proper and secure fixation during prosthetic implantation. Shorter humeral stems potentially carry more risk of misalignment than standard or long humeral stems. The hypothesis was that misalignment of the short humeral stems is influenced by regional bone quality.

METHODS

RTSA with a short curved humeral stem with neck-shaft angle (NSA) default of 132.5° was reviewed. The study group included 35 cases at a mean age of 75.97 (± 6.23) years. Deltoid-tuberosity index (DTI) was measured to evaluate proximal humeral bone quality. The deltoid tuberosity index was measured at immediately above position of the upper end of the deltoid tuberosity. Stem alignment was given by the angle measured in degrees between the intramedullary humeral shaft axis and the axis of the humeral implant stem.

RESULTS

The patient's mean DTI was 1.37 ± 0.16 (median, 1.32; range, 1.12-1.80). 22 patients had poor bone quality (DTI < 1.4), compared to 13 patients with acceptable bone quality (DTI > 1.4). After RTSA, ten humeral components (29%) were neutrally aligned, whereas 25 humeral components (71%) were misaligned. There was no correlation between misalignment and DTI (r = 0.117; p = 0.504). But there was a strong correlation between misalignment and the patient's own NSA (r = - 0.47; p = 0.004). The postoperative stem position and stem misalignment are not associated with functional outcomes (p > 0.05).

CONCLUSION

The misalignment of the short curved humeral stem frequently occurs. Poor reginal humeral bone quality does not influence misalignment after RTSA with a short humeral stem. Postoperative stem alignment is associated with the patient's preoperative NSA and method of neck cut. The misalignment does not affect functional outcomes for midterm follow-up. Further long-term follow-up studies are needed to confirm its clinical relevance.

The clinical necessity of a distal forearm DEXA scan for predicting distal radius fracture in elderly females: a retrospective case-control study

BACKGROUND

Recent studies have demonstrated that the distal forearm dual-energy X-ray absorptiometry (DEXA) scan might be a better method for screening bone mineral density (BMD) and the risk of a distal forearm fracture, compared with a central DEXA scan. Therefore, the purpose of this study was to determine the effectiveness of a distal forearm DEXA scan for predicting the occurrence of a distal radius fracture (DRF) in elderly females who were not initially diagnosed with osteoporosis after a central DEXA scan.

METHODS

Among the female patients who visited our institutes and who were over 50 years old and underwent DEXA scans at 3 sites (lumbar spine, proximal femur, and distal forearm), 228 patients with DRF (group 1) and 228 propensity score-matched patients without fractures (group 2) were included in this study. The patients' general characteristics, BMD, and T-scores were compared. The odds ratios (OR) of each measurement and correlation ratio among BMD values of the different sites were evaluated.

RESULTS

The distal forearm T-score of the elderly females with DRF (group 1) was significantly lower than that of the control group (group 2) (p < 0.001 for the one-third radius and ultradistal radius measurements). BMD measured during the distal forearm DEXA scan was a better predictor of DRF risk than BMD measured during the central DEXA (OR = 2.33; p = 0.031 for the one-third radius, and OR = 3.98; p < 0.001 for the ultradistal radius). The distal one-third radius BMD was correlated with hip BMD, rather than lumbar BMD (p < 0.05 in each group).

CONCLUSION

Performing a distal forearm DEXA scan in addition to a central DEXA scan appears to be clinically significant for detecting the low BMD in the distal radius, which is associated with osteoporotic DRF in elderly females.

LEVEL OF EVIDENCE

III; case-control study.

Age- and sex-specific normative values of bone mineral density in the adult glenoid

The objective of this study was to determine the normative bone mineral density (BMD) of cortical and trabecular bone regions in the adult glenoid and its dependence on the subject's age and sex. We analyzed computed tomography (CT) scans of 441 shoulders (310 males, 18-69 years) without any signs of glenohumeral joint pathology. Glenoid BMD was automatically quantified in six volumes of interest (VOIs): cortical bone (CO), subchondral cortical plate (SC), subchondral trabecular bone (ST), and three adjacent layers of trabecular bone (T1, T2, and T3). BMD was measured in Hounsfield unit (HU). We evaluated the association between glenoid BMD and sex and age with the Student's t test and Pearson's correlation coefficient (r), respectively. The lambda-mu-sigma method was used to determine age- and sex-specific normative values of glenoid BMD in cortical (CO and SC) and trabecular (ST, T1, T2, and T3) bone. Glenoid BMD was higher in males than females, in most age groups and most VOIs. Before 40 years old, the effect of age on BMD was very weak in both males and females. After 40 years old, BMD declined over time in all VOIs. This BMD decline with age was greater in females (cortical: r = -0.45, trabecular: r = -0.41) than in males (cortical: r = -0.30; trabecular: r = -0.32). These normative glenoid BMD values could prove clinically relevant in the diagnosis and management of patients with various shoulder disorders, in particular glenohumeral osteoarthritis and shoulder arthroplasty or shoulder instability, as well as in related research.

Can guided wave ultrasound predict bone mechanical properties at the femoral neck in patients undergoing hip arthroplasty?

The bone quality of patients undergoing hip replacement surgery is poorly predicted by radiographs alone. With better bone quality information available to a surgeon, the operation can be performed more safely. The aim of this study was to investigate whether ultrasound signals of cortical bone at peripheral sites such as the tibia and radius can be used to predict the compressive mechanical properties of cortical bone at the femoral neck. We recruited 19 patients undergoing elective hip arthroplasty and assessed the radius and tibia of these patients with the Azalée guided wave ultrasound to estimate the porosity and thickness of the cortex. Excess bone tissues were collected from the femoral neck and the compressive mechanical properties of the cortex were characterised under a mechanical loading rig to determine stiffness, ultimate strength, and density. The correlations between the ultrasound measurements and mechanical properties were analysed using linear regression, Pearson correlation statistics, and multiple regression analysis. Cortical mechanical properties were weakly to moderately correlated with the ultrasound measurements at various sites (R2 = 0.00-0.36). The significant correlations found were not consistent across all 4 peripheral measurement sites. Additionally, weak to moderate ability of the ultrasound to predict mechanical properties at the neck of femur with multiple regression analysis was found (R2 = 0.00-0.48). Again, this was inconsistent across the different anatomical sites. Overall, the results demonstrate the need for ultrasound scans to be collected directly from clinically relevant sites such as the femoral neck due to the inconsistency of mechanical properties across various sites.

Prospective comparative study of quantitative X-ray (QXR) versus dual energy X-ray absorptiometry to determine the performance of QXR as a predictor of bone health for adult patients in secondary care

OBJECTIVES

To evaluate a method of quantitative X-ray (QXR) for obtaining bone health information from standard radiographs aimed at identifying early signs of osteoporosis to enable improved referral and treatment. This QXR measurement is performed by postexposure analysis of standard radiographs, meaning bone health data can be acquired opportunistically, alongside routine imaging.

DESIGN

The relationship between QXR and dual energy X-ray absorptiometry (DEXA) was demonstrated with a phantom study. A prospective clinical study was conducted to establish areal bone mineral density (aBMD) prediction model and a risk prediction model of a non-normal DEXA outcome. This was then extrapolated to a larger patient group with DEXA referral data.

SETTING

Secondary care National Health Service Hospital.

PARTICIPANTS

126 consenting adult patients from a DEXA clinic.

INTERVENTIONS

All participants underwent a DEXA scan to determine BMD at the lumbar spine (L2-L4) and both hips. An additional Antero-Posterior pelvis X-ray on a Siemens Ysio, fixed digital radiograph system was performed for the study.

OUTCOME

Performance of QXR as a risk predictor for non-normal (osteoporotic) BMD.

RESULTS

Interim clinical study data from 78 patients confirmed a receiver operator curve (area under the ROC curve) of 0.893 (95% CI 0.843 to 0.942) for a risk prediction model of non-normal DEXA outcome. Extrapolation of these results to a larger patient group of 11 029 patients indicated a positive predictive value of 0.98 (sensitivity of 0.8) for a population of patients referred to DEXA under current clinical referral criteria.

CONCLUSIONS

This study confirms that the novel QXR method provides accurate prediction of a DEXA outcome.

TRIAL REGISTRATION NUMBER

ISRCTN98160454; Pre-results.

Cortical bone thickness of the distal radius predicts the local bone mineral density

AIMS

The distal radius is a major site of osteoporotic bone loss resulting in a high risk of fragility fracture. This study evaluated the capability of a cortical index (CI) at the distal radius to predict the local bone mineral density (BMD).

METHODS

A total of 54 human cadaver forearms (ten singles, 22 pairs) (19 to 90 years) were systematically assessed by clinical radiograph (XR), dual-energy X-ray absorptiometry (DXA), CT, as well as high-resolution peripheral quantitative CT (HR-pQCT). Cortical bone thickness (CBT) of the distal radius was measured on XR and CT scans, and two cortical indices mean average (CBTavg) and gauge (CBTg) were determined. These cortical indices were compared to the BMD of the distal radius determined by DXA (areal BMD (aBMD)) and HR-pQCT (volumetric BMD (vBMD)). Pearson correlation coefficient (r) and intraclass correlation coefficient (ICC) were used to compare the results and degree of reliability.

RESULTS

The CBT could accurately be determined on XRs and highly correlated to those determined on CT scans (r = 0.87 to 0.93). The CBTavg index of the XRs significantly correlated with the BMD measured by DXA (r = 0.78) and HR-pQCT (r = 0.63), as did the CBTg index with the DXA (r = 0.55) and HR-pQCT (r = 0.64) (all p < 0.001). A high correlation of the BMD and CBT was observed between paired specimens (r = 0.79 to 0.96). The intra- and inter-rater reliability was excellent (ICC 0.79 to 0.92).

CONCLUSION

The cortical index (CBTavg) at the distal radius shows a close correlation to the local BMD. It thus can serve as an initial screening tool to estimate the local bone quality if quantitative BMD measurements are unavailable, and enhance decision-making in acute settings on fracture management or further osteoporosis screening. Cite this article: Bone Joint Res 2021;10(12):820-829.

Trabecular Bone Score Could Not Predict the Bone Mineral Density of Proximal Humerus

Background

Osteoporosis is an important clinical factor for tendon healing after arthroscopic rotator cuff repair (ARCR). Conventional dual energy X-ray absorptiometry (DXA) of the hip and lumbar spine (LS) does not represent proximal humeral bone mineral density (BMD). Theoretically, direct measurement of the BMD of the proximal humerus is the best method; however, it is not popular and is non-standardized. Therefore, we evaluate whether the trabecular bone score (TBS) using LS DXA would represent proximal humeral BMD.

Methods

Conventional hip and LS DXA and proximal humeral BMD were measured in 212 consecutive ARCR patients, and TBS was calculated using LS DXA. Comparative analysis between the affected and contralateral asymptomatic shoulders was done; moreover, correlation analysis was conducted to evaluate the representativity of TBS for proximal humeral BMD. Regression analysis was performed to elucidate the risk factor of intraoperative suture anchor failure (ISAF).

Results

BMDs of the affected shoulder were significantly lower than those of the contralateral side (all P<0.05). TBS failed to present a strong correlation with proximal humeral BMD (correlation coefficients 0.155–0.506, all P<0.05), and the BMD of the greater tuberosity (GT) of the proximal humerus was revealed to be a sole risk factor for ISAF (odds ratio, 0.01, P=0.020).

Conclusions

TBS and conventional hip and LS DXA did not represent proximal humeral BMD. Furthermore, among the various radiological measurements, the BMD of the GT was a sole risk factor of ISAF. Therefore, further research for the direct measurement of proximal humeral BMD is mandatory to predict proximal humeral focal osteoporosis.

Cortical bone thickness predicts the quantitative bone mineral density of the proximal humerus

Cortical thickness determined at the humerus can serve as an easy and reliable screening tool to predict the local bone status when quantitative bone mineral density (BMD) measurements are not available. It can therefore serve as a rapid screening tool in fragility fractures to identify patients requiring further diagnostic or osteoporosis treatment.

INTRODUCTION

Quantitative bone mineral density (BMD) of the humerus is difficult to determine but relevant for osteoporosis and fracture treatment. Dual-energy X-ray absorptiometry (DXA) of the femur and lumbar spine overestimates the humeral BMD and is not ubiquitously available. Therefore, this study evaluated whether the cortical bone thickness (CBT) of the humerus or DXA of the forearm is able to predict humeral BMD.

METHODS

Humeral BMD of 54 upper cadaver extremities (22 pairs, 10 single) (19-90 years) was determined by high-resolution peripheral-quantitative-computed-tomography (HR-pQCT) (volumetric BMD (vBMD)) and DXA (areal BMD (aBMD)) of the proximal humerus and distal forearm. Average and gauge cortical bone thickness (CBTavg/ CBTg) of the humeral diaphysis was determined from standard radiographs (XR) and computed-tomography (CT) and compared to the humeral BMD. Pearson (r) and intraclass-correlation-coefficients (ICC) were used to compare results and rater-reliability.

RESULTS

CBTavg from XR strongly correlated with the humeral BMD (r = 0.78 aBMD (DXA) and r = 0.64 vBMD (HR-pQCT) (p < 0.0001)). The CBTg revealed a weaker correlation (r = 0.57 aBMD and r = 0.43 vBMD). CBT derived from XR strongly correlated to those from the CT (r = 0.82-0.90) and showed an excellent intra- and inter-rater correlation (ICC 0.79-0.92). Distal forearm aBMD correlated well with the humeral aBMD (DXA) (r = 0.77) and paired specimens highly correlated to the contralateral side (humerus r = 0.89, radius r = 0.97).

CONCLUSIONS

The CBTavg can reliably be determined from standard radiographs and allows a good prediction of quantitative humeral bone mineral density (aBMD or vBMD) if measurements are not available. Furthermore, the distal forearm or the contralateral humerus can serve as a side to estimate the BMD if the ipsilateral side is impaired.

Effect of Osteoporosis on Proximal Humerus Fractures

Introduction:

Proximal humerus fractures (PHF) constitute the majority of the most common osteoporotic fractures. Bone density measurements can affect treatment methods and outcomes. This study was aimed to investigate the effect of osteoporosis values, measured from direct radiographs, on fracture type, surgical outcomes.

Methods:

248 patients over 50 years of age who presented to Mersin City Hospital between 2017 and 2020 with proximal humeral fractures were retrospectively evaluated. The age and gender of the patients and the fracture types were evaluated according to the AO classification system from the direct radiographs obtained at the time of admission were recorded. The Tingart cortical thickness and deltoid tuberosity index (DTI) measurements were used to assess osteoporosis status in all patients. Postoperative and follow-up radiographs of 45 patients, treated with fixed-angle proximal humeral locking plate, were evaluated for radiographic results and their correlations with osteoporosis measurements were examined.

Results:

According to the demographic characteristics of the patients, 171 patients were female and 77 patients were male (F/M: 3/1), and mean age was 69.2 ± 11.66 (50-95). Considering the bone quality parameters in all patients, the mean Tingart value was 5.8 ± 1.6 mm and the mean DTI was 1.43 ± 0.17, where there was a correlation between the Tingart value and DTI (r = 0.810 and p < 0.001). Although there was a statistically significant relationship between the osteoporosis parameters and age and gender (p < 0.001 and p = 0.023, respectively), main AO fracture types were not related to osteoporosis (p < 0.05). In the operated group (n = 48, 19%), 19 patients (42%) showed poor outcomes, which were not associated with age and osteoporosis parameters.

Conclusion:

This study was concluded that osteoporosis parameters differ between genders and age groups in patients with PHF, however osteoporosis is not the main factor affecting the fracture type and surgical outcomes.

Distinct biomarkers for different bones in osteoporosis with rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is known to cause secondary osteoporosis and fragility fractures. This study aimed to identify biomarkers predictive of bone mineral density (BMD) change at three anatomical sites in patients with RA.

Methods

We conducted a prospective longitudinal study in patients with RA. In 2012, we recruited 379 patients from an RA cohort, 329 of whom underwent evaluation of blood and urine biomarkers together with measurement of BMD in the lumbar spine, proximal femur, and distal forearm. The BMD in these three regions was reassessed in 2014. We performed multivariate linear regression analysis to identify those factors associated with BMD change.

Results

The averages of age, body mass index, and disease activity score in 28 joints (DAS28) at baseline were 63.2 (minimum to maximum, 32–85), 21.3 (12.3–30.0), and 3.2 (0.1–5.9), respectively. Univariate analysis showed that the annual BMD change was significantly associated with the use of steroid, bisphosphonate (BP) or vitamin D (VitD), and serum homocysteine in the lumber spine; DAS28, the use of BP or VitD, CRP, and anti-cyclic citrullinated peptide antibody (ACPA) in the proximal femur; and the dosage of MTX, the use of BP or VitD, and serum tartrate-resistant acid phosphatase 5b (TRACP-5b) in the distal forearm, respectively.

Conclusions

Predictive biomarkers for BMD change in RA patients differ at each anatomical site. Practitioners should treat each anatomical site with different markers and prescribe osteoporosis drugs to prevent fractures for RA patients.

The influence of bone mineral density and cortical index on the complexity of fractures of the proximal humerus

OBJECTIVES

The goal of this study is to investigate the relation between indicators of osteoporosis (i.e., bone mineral density (BMD), and Cortical Index (CI)) and the complexity of a fracture of the proximal humerus as a result of a low-energy trauma.

METHODS

A retrospective chart review of 168 patients (mean age 67.2 years, range 51 to 88.7) with a fracture of the proximal humerus between 2007 and 2011, whose BMD was assessed at the Fracture Liaison Service with Dual Energy X-ray Absorptiometry (DXA) measurements of the hip, femoral neck (FN) and/or lumbar spine (LS), and whose CI and complexity of fracture were assessed on plain anteroposterior radiographs of the proximal humerus.

RESULTS

No significant differences were found between simple and complex fractures of the proximal humerus in the BMD of the hip, FN or LS (all p > 0.3) or in the CI (p = 0.14). Only the body mass index was significantly higher in patients with a complex fracture compared with those with a simple fracture (26.9 vs 25.2; p = 0.05).

CONCLUSION

There was no difference in BMD of the hip, FN, LS or CI of the proximal humerus in simple compared with complex fractures of the proximal humerus after a low-energy trauma. Factors other than the BMD and CI, for example body mass index, may play a more important role in the complexity of this fracture.Cite this article: J.W.A.M. den Teuling, B.S. Pauwels, L. Janssen, C.E. Wyers, H. M. J. Janzing, J.P.W. van den Bergh, J. W. Morrenhof. The Influence of bone mineral density and cortical index on the complexity of fractures of the proximal humerus. Bone Joint Res 2017;6:584-589. DOI: 10.1302/2046-3758.610.BJR-2017-0080.

Physiology of ageing of the musculoskeletal system

This review aims to provide a summary of current concepts of ageing in relation to the musculoskeletal system, highlighting recent advances in the understanding of the mechanisms involved in the development of age-related changes in bone, skeletal muscle, chondroid and fibrous tissues. The key components of the musculoskeletal system and their functions are introduced together with a general overview of the molecular hallmarks of ageing. A brief description of the normal architecture of each of these tissue types is followed by a summary of established and developing concepts of mechanisms contributing to the age-related alterations in each. Extensive detailed description of these changes is beyond the scope of this review; instead, we aim to highlight some of the most significant processes and, where possible, the molecular changes underlying these and refer the reader to in-depth, subspecialist reviews of the individual components for further details.

Impact of beverage consumption, age, and site dependency on dual energy X-ray absorptiometry (DEXA) measurements in perimenopausal women: a prospective study

INTRODUCTION

The aim of this study was to determine the best site for bone mineral density (BMD) measurements based on T-scores, age, and beverage consumption.

MATERIAL AND METHODS

In this prospective study, 271 women stratified by age (average age: 61.9 years) underwent dual energy X-ray absorptiometry (DEXA) scanning of their lumbar spine, hips, and forearms. Osteoporosis was defined as a BMD of 2.5 standard deviations or more below the mean peak bone mass based on a reference population of adult women (translated as a T-score ≤ -2.5), as measured by DEXA. Participants were also evaluated regarding alcohol and caffeine consumption by a semiquantitative questionnaire.

RESULTS

A significant discrepancy was observed in the classification of osteoporosis at different locations, with hip and forearm showing the best correlation (Pearson's r = 0.627, p < 0.001). In addition, for participants over 50 years of age, hip and forearm showed the best correlation. Significant correlations were also noted between forearm T-scores and caffeine consumed and, to a lesser extent, the level of alcohol consumption. In the group ≤ 50 years of age, lumbar spine and forearm T-scores were only associated with alcohol consumption. In the group over 50 years of age, hip and forearm T-scores were only associated with caffeine consumption.

CONCLUSIONS

Bone mineral density measurements at the hip and forearm correlated with caffeine consumption in elderly Taiwanese women. This is an important finding since age and caffeine consumption are known risk factors for osteoporosis.

Deltoid Tuberosity Index: A Simple Radiographic Tool to Assess Local Bone Quality in Proximal Humerus Fractures

BACKGROUND

Osteoporosis may complicate surgical fixation and healing of proximal humerus fractures and should be assessed preoperatively. Peripheral quantitative CT (pQCT) and the Tingart measurement are helpful methods, but both have limitations in clinical use because of limited availability (pQCT) or fracture lines crossing the area of interest (Tingart measurement). The aim of our study was to introduce and validate a simple cortical index to assess the quality of bone in proximal humerus fractures using AP radiographs.

QUESTIONS/PURPOSES

We asked: (1) How do the deltoid tuberosity index and Tingart measurement correlate with each other, with patient age, and local bone mineral density (BMD) of the humeral head, measured by pQCT? (2) Which threshold values for the deltoid tuberosity index and Tingart measurement optimally discriminate poor local bone quality of the proximal humerus? (3) Are the deltoid tuberosity index and Tingart measurement clinically applicable and reproducible in patients with proximal humerus fractures?

METHODS

The deltoid tuberosity index was measured immediately above the upper end of the deltoid tuberosity. At this position, where the outer cortical borders become parallel, the deltoid tuberosity index equals the ratio between the outer cortical and inner endosteal diameter. In the first part of our study, we retrospectively measured the deltoid tuberosity index on 31 patients (16 women, 15 men; mean age, 65 years; range, 22-83 years) who were scheduled for elective surgery other than fracture repair. Inclusion criteria were available native pQCT scans, AP shoulder radiographs taken in internal rotation, and no previous shoulder surgery. The deltoid tuberosity index and the Tingart measurement were measured on the preoperative internal rotation AP radiograph. The second part of our study was performed by reviewing 40 radiographs of patients with proximal humerus fractures (31 women, nine men; median age, 65 years; range, 22-88 years). Interrater (two surgeons) and intrarater (two readings) reliabilities, applicability, and diagnostic accuracy were assessed.

RESULTS

The correlations between radiograph measurements and local BMD (pQCT) were strong for the deltoid tuberosity index (r = 0.80; 95% CI, 0.63-0.90; p < 0.001) and moderate for the Tingart measurement (r = 0.67; 95% CI, 0.42-0.83; p < 0.001). There was moderate correlation between patient age and the deltoid tuberosity index (r = 0.65; p < 0.001), patient age and the Tingart measurement (r = 0.69; p < 0.001), and patient age and pQCT (r = 0.73; p < 0.001). The correlation between the deltoid tuberosity index and the Tingart measurement was strong (r = 0.84; p < 0.001). We determined the cutoff value for the deltoid tuberosity index to be 1.44, with the area under the curve = 0.87 (95% CI, 0.74-0.99). This provided a sensitivity of 0.88 and specificity of 0.80. For the Tingart measurement, we determined the cutoff value to be 5.3 mm, with the area under the curve = 0.83 (95% CI, 0.67-0.98), which resulted in a sensitivity of 0.81 and specificity of 0.85. The intraobserver reliability was high and not different between the Tingart measurement (intraclass correlation coefficients [ICC] = 0.75 and 0.88) and deltoid tuberosity index (ICC = 0.88 and 0.82). However, interobserver reliability was higher for the deltoid tuberosity index (ICC = 0.96; 95% CI, 0.93-0.98) than for the Tingart measurement (ICC = 0.85; 95% CI, 0.69-0.93).The clinical applicability on AP radiographs of fractures was better for the deltoid tuberosity index (p = 0.025) because it was measureable on more of the radiographs (77/80; 96%) than the Tingart measurement (69/80; 86%).

CONCLUSIONS

The deltoid tuberosity index correlated strongly with local BMD measured on pQCT and our study evidence shows that it is a reliable, simple, and applicable tool to assess local bone quality in the proximal humerus. We found that deltoid tuberosity index values consistently lower than 1.4 indicated low local BMD of the proximal humerus. Furthermore, the use of the deltoid tuberosity index has important advantages over the Tingart measurement regarding clinical applicability in patients with proximal humerus fractures, when fracture lines obscure the Tingart measurement landmarks. However, further studies are needed to assess the effect of the deltoid tuberosity index measurement and osteoporosis on treatment and outcome in patients with proximal humerus fractures.

LEVEL OF EVIDENCE

Level IV, diagnostic study.

The measurement of bone mineral density of bilateral proximal humeri using DXA in patients with unilateral rotator cuff tear

We propose that the measurement of the bone mineral density (BMD) of the proximal humerus be standardized using the dual energy X-ray absorptiometry (DXA) in patients supposed to undergo rotator cuff repair surgery as well as those with the fracture of the proximal humerus as the BMD of the proximal humerus is decreased in these patients.

INTRODUCTION

We propose that the measurement of the BMD of the proximal humerus be standardized using the DXA in patients who are supposed to undergo rotator cuff repair surgery as well as those with the fracture of the proximal humerus.

METHODS

We conducted the prospective study in 213 patients with unilateral rotator cuff tear but without contralateral shoulder pain or disease. In these patients, we preoperatively measured the BMD of the bilateral proximal humeri with a repeat measurement in 20 patients. We predefined three regions of interest (ROIs) in the proximal humerus with the consideration of the rotator cuff repair surgery as well as proximal humeral fractures.

RESULTS

The measurement of the BMD of the proximal humerus using the DXA showed excellent reliability (intraclass correlation coefficient > .90). BMD values of all three ROIs in the affected shoulder were significantly lower than those in asymptomatic shoulder (all p < 0.05). In female patients, the BMD values of ROIs in bilateral shoulder were significantly lower than those in male patients (all p < 0.001). In multiple regressions, however, there were no significant correlations between other clinical characteristics, except for the gender, and the BMD of GT in the affected shoulder.

CONCLUSIONS

It is imperative that the bone quality of the proximal humerus be accurately evaluated prior to surgery in patients who are supposed to undergo rotator cuff repair using suture anchors as well as in those with proximal humeral fractures. This is because the BMD of the proximal humerus is decreased in these patients.

Measurement of volumetric bone mineral density in proximal humerus using quantitative computed tomography in patients with unilateral rotator cuff tear

BACKGROUND

The first purpose of this study was to reveal the clinically important region-specific volumetric bone mineral density (vBMD) of the proximal humerus in patients with unilateral rotator cuff tear (RCT), and the second was to evaluate the relationship between vBMD of the proximal humerus and BMD of the hip and lumbar spine measured using conventional dual-energy X-ray absorptiometry. Finally, we assessed whether any clinical factor could predict local osteoporosis of the proximal humerus.

METHODS

The study enrolled 65 patients who underwent arthroscopic repair of a unilateral RCT between April 2010 and July 2011 and had computed tomography scans of bilateral proximal humeri. Considering the suture bridge technique for RCT repair to be the leading treatment, region-specific BMD was measured in 7 volumetric blocks in the proximal humerus. Image and quantification processing was used to calculate the vBMD of each block.

RESULTS

The vBMD values in all 7 blocks of the symptomatic shoulder were significantly lower than those of the asymptomatic contralateral shoulder (P < .05). Regardless of RCT, the greater tuberosity showed significant location-dependence in vBMD value; that is, the vBMD value was the highest in the posterolateral portion and the lowest in the medial portions. No significant correlation was found between vBMD of the greater tuberosity and clinical factors except female gender.

CONCLUSION

The present study demonstrated the regional and bilateral differences in vBMD within the greater tuberosity in patients with unilateral RCT. Aside from female gender, no other clinical factors presented as risk factors for a higher possibility of osteoporosis.

Bone mineral density of the trapezium in osteoarthritic trapeziometacarpal joints

The aim of this study was to test the precision and reliability of measurements of the bone mineral density (BMD) of the trapezium in patients with osteoarthritic trapeziometacarpal joints using dual-energy X-ray absorptiometry scans and to assess whether there is an acceptable correlation between the BMD of the trapezium and that of the distal radius, for which normative data exist. We included 66 patients (52 women, 14 men) diagnosed with Eaton-Glickel stage II-IV osteoarthritis and a mean age of 59 years (range 40-77) in a prospective study. We found good intra- and inter-observer agreement of BMD measurements. Reliability was also good in repeated measurements. There was an indication of an increase in BMD with progression in the Eaton-Glickel stage. There was only a moderate correlation between the BMD of the trapezium and that of the radius.

Proximal humerus cortical bone thickness correlates with bone mineral density and can clinically rule out osteoporosis

BACKGROUND

Bone mineral density measurements with dual-energy x-ray absorptiometry (DXA) are commonly used to diagnose osteoporosis and assess fracture risk. This study describes the association between radiographic measures of proximal humeral cortical bone thickness and bone mineral density measured by DXA. The study also assesses the discriminative capability of clinical cortical bone thickness measurements at the proximal humerus to differentiate patients with osteoporosis.

METHODS

Patients (N = 108) with shoulder radiographs and DXA studies were evaluated. Cortical bone thickness was assessed with 2 techniques, the gauge method and the average method. Pearson correlations were used to describe the relationship between cortical bone thickness measurement techniques and femoral and lumbar DXA. Sensitivity, specificity, and negative predictive value for predicting osteoporosis were determined for several cortical bone thickness thresholds. Rater reliability of measures was assessed with intraclass correlation coefficients.

RESULTS

The intra-rater and inter-rater reliability of measures was excellent (intraclass correlation coefficient > 0.85). Average cortical bone thickness measurements at the proximal humerus strongly correlated with DXA femur measurements (r = 0.64, P < .0001) and moderately correlated with DXA lumbar measurements (r = 0.49, P < .0001). Gauge cortical thickness measurements also correlated with DXA femur measurements (R = 0.53, P < .0001) and DXA lumbar measurements (R = 0.35, P < .001). An average proximal humerus cortical thickness measurement of 6 mm was identified as a potential threshold value for predicting osteoporosis, with a sensitivity of 93%, specificity of 52%, and negative predictive value of 95%.

CONCLUSIONS

Average cortical bone thickness measurements obtained from standard anteroposterior shoulder radiographs are correlated with DXA. Furthermore, they provide a clinically relevant, rapid, sensitive, and inexpensive method for ruling out osteoporosis.

Anatomically reproducible assessment of volumetric bone mineral density--based on clinical computed tomography

Local distribution and quality of bone mineral density (BMD) in the proximal humerus are important for rotator cuff repair, internal fixations, and arthroplasty. The current study aimed to develop a volumetric BMD (vBMD) measurement technique that can specify the volumetric region of interest in an anatomically reproducible manner and ensures fair comparison of vBMD among intrasubjective or intersubjective measurements. Computed toed into three-dimensional (3D) polygon models. A standardized volumetric block was asmographic images of 10 intact shoulders (from six women and four men, age range 46-69 years) were reconstruct signed, and it included whole insertion areas of the supraspinatus and infraspinatus tendons on the greater tuberosity. For standardizing a bone block, a mathematical method for reproducible landmark assignment and reproducible local coordinate system was developed. After converting the polygonal standardized volumetric block into 3D tetrahedron finite element models, its vBMD was calculated. The repeatability and reproducibility standard deviations of the vBMD measurement method were found to be less than 2%. The current study developed a vBMD measurement technique that can specify the vROI in an anatomically reproducible manner and ensures fair comparison of BMD among intrasubjective or intersubjective measurements, with less than 2% reproducibility error.

[Volar locking plating for distal radial fractures. Is osteoporosis associated with poorer functional results and higher complications rates?]

BACKGROUND

The purpose of this prospective study was to compare the functional and radiological results and complication rates after locking plate osteosynthesis of unstable distal radial fractures in elderly patients as a function of the bone mineral density (BMD). The hypothesis that reduced BMD is accompanied by poorer function and a higher rate of complications was investigated.

PATIENTS AND METHODS

A total of 65 consecutive patients with unstable distal radial fractures, AO 23-A2 (n=1), -A3 (n=29), -C1 (n=2), -C2 (n=28) and -C3 (n=5) were included with a mean age of 69 years (range, 52-86 years). Standardized clinical and radiological follow-up was performed 6 weeks, 3 and 12 months postoperatively. All patients underwent dual x-ray absorptiometry of the contralateral distal radius within 6 weeks postoperatively and 3 groups could be differentiated: group I (n=27) osteoporosis, group II (n=27) osteopenia and group III (n=11) normal BMD. Data on the DASH and QAL scores as well as the range of motion, grip strength and radiological parameters were collected. According to the BMD a detailed analysis of complications was performed.

RESULTS

Exemplary the 12 months results of DASH and the range of motion are shown here: the DASH 12 months postoperatively was DASH(total)=6 (0-64) P, DASH(group I)=7 (0-32.5) P, DASH(group II)=11 (1-63) P, DASH(group III)=2 (0-23) P, no significance. The range of motion increased significantly in all 3 groups (except pronation in groups I and III) from 6 weeks to 3 and 12 months postoperatively and 12 months postoperatively showed means for dorsal extension 55° (25-75), palmar flexion 55° (35-75), ulnar abduction 35° (20-45), radial abduction 20° (5-40), supination 90° (60-90) and pronation 85° (65-90) in the total sample. The comparison of DASH and range of motion was not significantly different at each time of follow-up between all 3 groups. A group-specific analysis of implant and BMD dependent complications showed 2/27 (7%) secondary intra-articular screw perforations in group I, 1/27 (4%) in group II and 0/11 in group III.

CONCLUSION

The hypothesis that a reduced BMD is accompanied by a poorer function and a higher rate of complications was refuted. Analysis of complications showed a trend to more BMD-dependent complications in the osteoporosis group.

Nondisplaced proximal humeral fractures: high incidence among outpatient-treated osteoporotic fractures and severe impact on upper extremity function and patient subjective health perception

BACKGROUND

Although most proximal humeral fractures are attributed to osteoporosis, they are usually not considered individually in osteoporotic studies because of their lower incidence. The purpose of this study was to evaluate the incidence of nondisplaced proximal humeral fractures in comparison with other outpatient-treated osteoporotic fractures, as well as to assess their functional impact and effects on patient-perceived quality of life.

MATERIALS AND METHODS

In this multicenter, cross-sectional, prospective study, all osteoporotic fractures in postmenopausal women aged 50 years or older treated nonoperatively in 358 trauma centers were recorded during a 3-month period. Fractures were considered osteoporotic if caused by a low-energy trauma. Pathologic fractures were excluded. The incidence of proximal humeral fractures in relation to other osteoporotic fractures was calculated. Patients were interviewed by telephone 6 months after the fracture with the Disabilities of the Arm, Shoulder and Hand and EuroQoL 5D questionnaires.

RESULTS

This study comprised 5,147 women (mean age, 72.6 ± 7.5 years) with 5,268 fractures. Of these, 912 (17.5%) had had proximal humeral fractures. The mean Disabilities of the Arm, Shoulder and Hand score was 26.6 ± 25.7. Of the women, 67.3% had pain or discomfort and disclosed significant reductions in functional capacity, especially with regard to self-care (44.5%), daily life activities (56.5%), and anxiety or depression (32.7%).

CONCLUSION

Nondisplaced proximal humeral fractures are among the most common fractures associated with osteoporosis, and they can be a major cause of functional disability and reduction in subjective patient-perceived health.

Cervical spine bone mineral density as a function of vertebral level and anatomic location

BACKGROUND CONTEXT

Bone mineral density (BMD) measurements acquired from quantitative computed tomography scans have been shown to correlate with bone mechanical properties such as strength, stiffness, and yield load. There are currently no reports of BMD as a function of anatomic location within each vertebra.

PURPOSE

The overall objective of this study was to characterize BMD in the cervical spine as a function of level and anatomic location.

STUDY DESIGN

Cervical spine BMD was evaluated in vivo using a clinically relevant age group.

PATIENT SAMPLE

Twenty-two subjects (13 women and 9 men) were included with an average age of 48 ± 7 years (range, 35-61 years). Ten subjects were recently diagnosed with cervical radiculopathy (age 49 ± 8 years; six women and four men; and two smokers and eight nonsmokers), and 12 subjects were asymptomatic controls (age 46 ± 6 years; seven women and five men; and three smokers, three quit smoking, and six nonsmokers).

OUTCOME MEASURES

Physiologic measures included overall BMD for C3-C7, average BMD within 11 anatomically defined regions of interest for each vertebra, and density distribution (by volume) within each anatomic region and vertebral level.

METHODS

Subject-specific three-dimensional bone models were created from high-resolution computed tomography scans of the subaxial cervical spine (C3-C7). Custom software calculated the average BMD within 11 anatomically defined regions of interest for each three-dimensional bone model. Bone mineral density values for each voxel of bone tissue were binned into 50 mg/cc ranges to determine the density distribution by volume. Repeated-measures analysis of variance was used to test for differences within subjects by level (C3-C7) and anatomic location. The correlation between BMD in the central vertebral body and the pedicle and lateral mass regions was tested using Pearson correlation.

RESULTS

Average BMDs by level were 476, 503, 507, 473, and 414 mg/cm(3) for C3-C7, respectively. C3 and C6 BMDs were significantly less than those of C4 and C5 (p<.007). C7 BMD was significantly less than those of all other levels (all p<.001). Control and female subjects showed a trend toward higher BMD than radiculopathy and male subjects across all levels (p value: .06-.17). Wide variation in BMD was observed over anatomical regions, with the pedicles having significantly higher BMD than all other anatomic locations and the anterior portion of the central vertebral body having significantly lower BMD than all other anatomic locations. There was a significant positive correlation between central vertebral body BMD and lateral mass BMD at each level. Bone mineral density distribution by volume plots revealed women had a higher volume of very high-density bone than men but only in the posterior elements.

CONCLUSIONS

This study has characterized BMD in the cervical spine according to vertebral level and anatomic location within each vertebral level using live subjects from a clinically relevant age group. The results indicate significant differences in BMD according to vertebral level and among anatomical regions within each vertebra. The results suggest to the surgeon and device manufacturer that surgical procedures involving instrumentation attached to C7 may require a modification in instrumentation or in surgical technique to attain results equivalent to more superior levels. The results suggest to the basic scientist that computational models may be improved by taking into account the wide variation in BMD over different anatomical regions.