Dual-energy X-ray absorptiometry of human metatarsals: precision, least significant change and association to ex vivo fracture force

Are Muscle and Fat Loss Predictive of Clinical Events in Pancreatic Cancer? The Importance of Precision Metrics

CONTEXT

Muscle and fat loss from cancer may have prognostic significance. Skeletal muscle and fat areas measured at L3 on a CT scan correlate with body muscle and fat mass. We wished to know if reduced skeletal muscle area or fat on diagnostic CT scans or changes from initial CT scans in patients with pancreatic cancer who died in 2018 and 2019 predicted mortality.

METHOD

Electronic records of 112 patients with locally advanced or metastatic pancreatic cancer were used to extract stage, age, gender, comorbidities, weight, and height at the time of the first CT scan. Survival (in days) was defined from the first CT scan to the death date. Patients had at least one CT scan of the abdomen. I. Two trained medical students read scans independently using TeraRecon software (Durham, NC). Results were averaged, and the differences determined precision. Interclass correlation coefficient (ICC), coefficient of variation, and least significant change determined the precision between readers. Independent prognostic modeling included age and BMI.

RESULTS

An evaluable sample of 104 with an average age of 67, 56 were male. Nearly half had a TNM Stage of IV (45%). The average Charlson Comorbidity index is 7.2. In those undergoing repeat scans, most were in the timeframe of 60-120 days. Changes in visceral fat in men in the unadjusted Cox proportional hazard model and reduced skeletal muscle area in the age-adjusted model of men predicted mortality. In contrast, myosteatosis in women marginally predicted improved survival. ICC's precision between readers was adequate but by least significant change would have missed subtle, clinically important changes.

DISCUSSION

Muscle loss during chemotherapy in men predicted mortality in men but not women. Precision is an important metric when measuring body composition.

CONCLUSION

Muscle loss in men during chemotherapy of pancreatic cancer predicts mortality.

Extended finite element analysis for the 2nd and 3rd metatarsals stress fracture during push-off

Metatarsal stress fractures (MSF), particularly the 2nd and 3rd MSF, are common injuries among athletes. Although there are several practices to reduce foot and ankle injuries, there is no injury prevention program specifically designed to minimize MSF. This is mainly due to the lack of information about the loadings/postures that cause MSF. Therefore, this study aimed to investigate dangerous loadings/postures potentially causing MSF during push-off (PO). The analysis was conducted with Finite Element Modelling (FEM), calibrated with the three-point bending test, and validated with peak plantar pressure (PPP) and fracture force measurement. Extended Finite Element Method was used for MSF simulation such that ten different foot and ankle configurations were designed, with five for each of the 2nd and 3rd MSF under pure vertical loadings. A more complex loading, ankle eversion/inversion during PO, was also examined for the MSF. The average error percentage for the calibration of the model with the three-point bending test was 3.05%. The average error percentages for the validation of the model with PPP and fracture force measurements were 18% and 30%, respectively. The outcomes of pure vertical loadings indicated the higher potential for the 2nd and 3rd MSF at 30% PO and 70% PO, respectively. The results of ankle eversion/inversion loadings represented that the most dangerous posture for MSF was 30° ankle eversion for the 3rd metatarsal at 70% PO. These results provide a guide, including what postures to avoid for the 2nd and 3rd MSF among people who are at high risk of MSF.

Biomarkers of chronic kidney disease-mineral bone disorder (CKD-MBD) in the diabetic foot: A medical record review

AIMS

Determine the prevalence and relative risk of having single and combinations of biomarkers of chronic kidney disease-mineral bone disorder (CKD-MBD) syndrome in the diabetic foot from an electronic medical record (EMR) review.

METHODS

Review of 152 patients with one foot radiograph and diagnoses of both diabetes mellitus (DM) and chronic kidney disease (CKD) stages 1-5. Presence/absence of peripheral neuropathy (PN), targeted serum markers, and both pedal vessel calcification (PVC) and buckling ratio (BR) of 2nd and 5th metatarsals from radiographs were recorded. Prevalence of single and combinations of foot biomarkers are reported as count and percentage. Risk ratios (RR) with 95% confidence intervals (95% CI) were calculated to assess risk of foot biomarkers in each stage of CKD-MBD.

RESULTS

Prevalence and RR of PVC, PN, and BR ≥ 3.5 biomarkers, both single and in combination, all increase with progression of CKD. The RR increases to 9.6 (95 % CI: 3, 26; p < 0.001) when all 3 biomarkers present in stage 5.

CONCLUSIONS

PVC, PN, and BR ≥ 3.5 are prognostic biomarkers of CKD-MBD syndrome in the diabetic foot. Recognition of these foot biomarkers may allow earlier interventions to help reduce nontraumatic lower extremity amputation in individuals with diabetic CKD-MBD.

A Narrative Review of Metatarsal Bone Stress Injury in Athletic Populations: Etiology, Biomechanics, and Management

Metatarsal bone stress injuries (BSIs) are common in athletic populations. BSIs are overuse injuries that result from an accumulation of microdamage that exceeds bone remodeling. Risk for metatarsal BSI is multifactorial and includes factors related to anatomy, biology, and biomechanics. In this article, anatomic factors including foot type, metatarsal length, bone density, bone geometry, and intrinsic muscle strength, which each influence how the foot responds to load, are discussed. Biologic factors such as low energy availability and impaired bone metabolism influence the quality of the bone. Finally, the influence of biomechanical loads to bone such as peak forces, load rates, and loading cycles are reviewed. General management of metatarsal BSI is discussed, including acute care, rehabilitation, treatment of refractory metatarsal BSI, and evaluation of healing/return to sport. Finally, we identify future research priorities and emerging treatments for metatarsal BSI.

Accelerated Cortical Osteolysis of Metatarsals in Charcot Neuroarthropathy: A Cross-Sectional Observational Study

Metatarsals are frequent sites of stress and fragility fractures in younger athletic populations and aging older adults. Metatarsal fractures are particularly common in Charcot neuroarthropathy (CN), a complication of diabetes mellitus (DM) and peripheral neuropathy (PN). Neuropathic metatarsal fractures may be caused by an accelerated cortical bone osteolysis and may be reflected as geometric-derived strength estimates from standard foot radiographs. The purpose of this cross-sectional study was to determine geometry and strength-derived estimates of the metatarsals in individuals with DM, PN, and CN compared with younger and older adult controls who were nondiabetic and nonneuropathic. We studied 62 participants: 20 young adult controls (YACs), 22 older adult controls (OACs), and 20 diagnosed with DMPN&CN. From weight-bearing radiographs, we measured the outer diaphysis diameter and inner marrow diameter at the distal, middle, and proximal diaphysis sites of the second and fifth metatarsal. From these diameters, we derived strength estimates of combined cortical width (CCt.Wi), percent cortical area (%Ct.rA), buckling ratio (BR), moment of inertia (MOI), and section modulus (SM) at each site in both metatarsals. DMPN&CN participants had an accelerated cortical thinning, decreased %Ct.Ar, increased BR, and lower MOI and SM compared with OACs and YACs. The OACs showed age-related decreases in CCt.Wi and % Ct.Ar, and increased BR. The BR demonstrated significant group × bone × site interaction with the distal fifth metatarsal in the DMPN&CN group having the lowest bone strength. The BR in the distal fifth metatarsal of DMPN&CN participants was 36% and 49% greater than in the OAC and YAC groups, respectively. DMPN&CN participants have lower metatarsal bone strength estimates compared with younger and older adult controls. Standard foot radiographs demonstrate an accelerated cortical osteolysis in DMPN&CN individuals, particularly in the distal fifth metatarsal diaphysis. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Reliability of analysis of the bone mineral density of the second and fifth metatarsals using dual-energy x-ray absorptiometry (DXA)

Background

Metatarsal fractures, especially of the fifth metatarsal, are common injuries of the foot in a young athletic population, but the risk factors for this injury are not well understood. Dual-energy x-ray absorptiometry (DXA) provides reliable measures of regional bone mineral density to predict fracture risk in the hip and lumbar spine. Recently, sub-regional metatarsal reliability was established in fresh cadaveric specimens and associated with ultimate fracture force. The purpose of this study was to assess the reliability of DXA bone mineral density measurements of sub-regions of the second and fifth metatarsals in a young, active population.

Methods

Thirty two recreationally active individuals participated in the study, and the bone density of the second (2MT) and fifth (5MT) metatarsals of each subject was measured using a Hologic QDR x-ray bone densitometer. Scans were analyzed separately by two raters, and regional bone mineral density, bone mineral content, and area measurements were calculated for the proximal, shaft, and distal regions of the bone. Intra-rater, inter-rater, and scan-rescan reliability were then determined for each region.

Results

Proximal and shaft bone mineral density measurements of the second and fifth metatarsal were reliable. ICC's were variable across regions and metatarsals, with the distal region being the poorest.

Conclusions

Bone mineral density measurements of the metatarsals may be a better indicator of fracture risk of the metatarsals than whole body measurements. A reliable method for measuring the regional bone mineral densities of the metatarsals was found. However, inter-rater reliability and scan-rescan reliability for the distal regions were poor. Future research should examine the relationship between DXA bone mineral density measurements and fracture risk at the metatarsals.