Bone microarchitecture and estimated failure load are deteriorated whether patients with chronic kidney disease have normal bone mineral density, osteopenia or osteoporosis.

INTRODUCTION: Measurement of bone mineral density (BMD) is recommended in patients with chronic kidney disease (CKD). However, most persons in the community and most patients with CKD have osteopenia, suggesting fracture risk is low. Bone loss compromises bone microarchitecture which increases fragility disproportionate to modest deficits in BMD. We therefore hypothesized that patients with CKD have reduced estimated failure load due to deterioration in microarchitecture irrespective of whether they have normal femoral neck (FN) BMD, osteopenia or osteoporosis. METHODS: We measured distal tibial and distal radial microarchitecture in 128 patients with CKD and 275 age- and sex-matched controls using high resolution peripheral quantitative computed tomography, FN-BMD using bone densitometry and estimated failure load at the distal appendicular sites using finite element analysis. RESULTS: Patients versus controls respectively had: lower tibial cortical area 219 (40.7) vs. 237 (35.3) mm2, p = 0.002, lower cortical volumetric BMD 543 (80.7) vs. 642 (81.7) mgHA/cm3 due to higher porosity 69.6 (6.19) vs. 61.9 (6.48)% and lower matrix mineral density 64.2 (0.62) vs. 65.1 (1.28)%, lower trabecular vBMD 92.2 (41.1) vs. 149 (43.0) mgHA/cm3 due to fewer and spatially disrupted trabeculae, lower FN-BMD 0.78 (0.12) vs. 0.94 (0.14) g/cm2 and reduced estimated failure load 3825 (1152) vs. 5778 (1467) N, all p < 0.001. Deterioration in microarchitecture and estimated failure load was most severe in patients and controls with osteoporosis. Patients with CKD with osteopenia and normal FN-BMD had more deteriorated tibial microarchitecture and estimated failure load than controls with BMD in the same category. In univariate analyses, microarchitecture and FN-BMD were both associated with estimated failure load. In multivariable analyses, only microarchitecture was independently associated with estimated failure load and accounted for 87% of the variance. CONCLUSIONS: Bone fragility is likely to be present in patients with CKD despite them having osteopenia or normal BMD. Measuring microarchitecture may assist in targeting therapy to those at risk of fracture.

Risk of Arterial Injury During Hip Internal Fixation.

BACKGROUND: Injury to femoral arterial vessels is a risk with internal fixation of the hip. Understanding the anatomy of proximate vessels, particularly medial vessels not directly visualized, may reduce intraoperative and postoperative complications. METHODS: We analyzed 47 patients (29 men and 18 women) using a computed tomographic (CT) angiogram of the lower limbs. The mean age of our patients was 69 years (range, 46 to 88 years). The distance from the tip of the greater trochanter to the profunda femoris and its perforators within 5 mm of the medial femoral shaft was measured along the length of the expected placement of typical dynamic hip screw constructs and other proximal femoral fracture fixation methods. RESULTS: All patients were found to have 2 perforator vessels within 5 mm of the medial femoral shaft along the line of dynamic hip screw insertion (up to 200 mm from the tip of the greater trochanter). The first perforator was found at a mean distance of 112.6 mm (median, 110 mm) in women and at 123.4 mm (median, 122 mm) in men (p = 0.0066) from the tip of the greater trochanter. The second perforator appeared at a mean distance of 159.7 mm (median, 159 mm) in women and 178.9 mm (median, 180 mm) in men (p = 0.0028) from the tip of the greater trochanter. CONCLUSIONS: Surgeons should be aware of the presence of 2 arteries within 5 mm of the medial femoral shaft during femoral internal fixation procedures. We suggest avoiding the overdrilling of the medial cortex and the insertion of overlong screws along the femoral shaft from 110 to 120 mm in women and 120 to 130 mm in men (as measured from the tip of the greater trochanter) to prevent vascular injury during proximal femoral fracture fixation. CLINICAL RELEVANCE: This article can assist orthopaedic surgeons in planning for procedures involving internal fixation of the hip and may reduce vascular complications from such procedures.