Effect of a cast on short-term reproducibility and bone parameters obtained from HR-pQCT measurements at the distal end of the radius

\u3cp\u3eBACKGROUND: High-resolution peripheral quantitative computed tomography (HR-pQCT) is a promising tool to assess the fracture-healing process at the microscale in vivo. Since casts are often used during fracture treatment, they might affect the assessment of bone density, microarchitectural, and biomechanical parameters and the short-term reproducibility of those parameters, e.g., as a result of beam-hardening. The aim of this study was to assess the effect of a plaster-of-Paris and/or fiberglass cast on bone parameters and on the short-term reproducibility of the HR-pQCT measurements of those parameters.\u3c/p\u3e\u3cp\u3eMETHODS: The effects of a cast on HR-pQCT-derived bone parameters were evaluated by comparing HR-pQCT scans of fifteen human cadaveric distal radial specimens from one male and fourteen female donors (median age, eighty-four years [range, sixty-two to ninety years] at the time of death) in three conditions: with a plaster-of-Paris cast, with a fiberglass cast, or without a cast. Short-term reproducibility was assessed using duplicate scans of the distal end of the radius in sixteen healthy volunteers without a fracture (nine men and seven women with a median age of twenty-six years; range, twenty-two to thirty-nine years) while wearing and not wearing a fiberglass cast.\u3c/p\u3e\u3cp\u3eRESULTS: Compared with measurements made with no cast, the plaster-of-Paris cast introduced a systematic error in the bone parameters ranging from -2.6% in trabecular separation to -9.8% in cortical thickness. Bone parameters were affected only marginally by fiberglass, with errors between -0.6% and -1.6% in trabecular separation and cortical thickness, respectively. Short-term reproducibility with a fiberglass cast was similar to that with no cast: approximately 1% for bone density parameters, 4% to 5% for microarchitectural parameters, and 3% to 4% for biomechanical parameters.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: A plaster-of-Paris cast has a considerable effect on HR-pQCT measurements. A fiberglass cast only marginally affects the bone parameters, and the short-term reproducibility of HR-pQCT measurements in patients with a fiberglass cast is comparable with that in patients without a cast. In studies on fracture-healing using HR-pQCT, a fiberglass cast is desirable if immobilization is indicated. The use of a plaster-of-Paris cast should be avoided if possible; however, if not avoidable, corrections after the scan are desirable to adjust for the error introduced in the bone parameters.\u3c/p\u3

Distal radius plate of CFR-PEEK has minimal effect compared to titanium plates on bone parameters in high-resolution peripheral quantitative computed tomography: a pilot study

\u3cp\u3eBACKGROUND: Carbon-fiber-reinforced poly-ether-ether-ketone (CFR-PEEK) has superior radiolucency compared to other orthopedic implant materials, e.g. titanium or stainless steel, thus allowing metal-artifact-free postoperative monitoring by computed tomography (CT). Recently, high-resolution peripheral quantitative CT (HRpQCT) proved to be a promising technique to monitor the recovery of volumetric bone mineral density (vBMD), micro-architecture and biomechanical parameters in stable conservatively treated distal radius fractures. When using HRpQCT to monitor unstable distal radius fractures that require volar distal radius plating for fixation, radiolucent CFR-PEEK plates may be a better alternative to currently used titanium plates to allow for reliable assessment. In this pilot study, we assessed the effect of a volar distal radius plate made from CFR-PEEK on bone parameters obtained from HRpQCT in comparison to two titanium plates.\u3c/p\u3e\u3cp\u3eMETHODS: Plates were instrumented in separate cadaveric human fore-arms (n = 3). After instrumentation and after removal of the plates duplicate HRpQCT scans were made of the region covered by the plate. HRpQCT images were visually checked for artifacts. vBMD, micro-architectural and biomechanical parameters were calculated, and compared between the uninstrumented and instrumented radii.\u3c/p\u3e\u3cp\u3eRESULTS: No visible image artifacts were observed in the CFR-PEEK plate instrumented radius, and errors in bone parameters ranged from -3.2 to 2.6%. In the radii instrumented with the titanium plates, severe image artifacts were observed and errors in bone parameters ranged between -30.2 and 67.0%.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: We recommend using CFR-PEEK plates in longitudinal in vivo studies that monitor the healing process of unstable distal radius fractures treated operatively by plating or bone graft ingrowth.\u3c/p\u3

Assessment of bone density, structure, and cortical interruptions of finger joints in patients with rheumatoid arthritis using high-resolution peripheral quantitative CT

Background Rheumatoid arthritis (RA) is characterized by peri-articular bone loss. In patients with RA, lower bone density and structural integrity, and an increased number of erosions compared to healthy controls (HCs) has been demonstrated using High-Resolution peripheral Quantitative CT (HR-pQCT) (1,2). To further characterize RA-related changes, we recently introduced a method for quantifying small cortical interruptions in finger joints (3).\u3cbr/\u3e\u3cbr/\u3eObjectives To investigate the cortical and trabecular bone density, structure, and cortical interruptions in MCP joints in early and late RA patients compared to HCs using HR-pQCT imaging.\u3cbr/\u3e\u3cbr/\u3eMethods The 2nd and 3rd MCP joint of 70 subjects (mean age 53.1 (SD 9.2) years) were evaluated by HR-pQCT (82μm isotropic voxel size): 38 HCs, 10 early RA (diagnosis ≤2 years ago) and 22 late RA (diagnosis ≥10 years ago). Images were analyzed for cortical interruptions, and for cortical and trabecular bone density and structure. Descriptives were analyzed per joint by one-way ANOVA with Bonferroni post-hoc testing or Kruskal-Wallis with Mann-Whitney post-hoc testing, as appropriate.\u3cbr/\u3e\u3cbr/\u3eResults Significant differences with respect to all parameters were found across the groups (Table 1). In early and late RA, the percentage of joints with at least 1 interruption was higher, and number of trabeculae, cortical thickness, total density and cortical density were lower than in HC. In addition, in late RA, number of interruptions, interruption volume and trabecular separation were higher, and trabecular density was lower than in HC. Bone loss at the cortical and trabecular bone was primarily observed at the rim of the joint (Figure 1, arrow

Prospective follow-Up of cortical interruptions, bone density, and micro-structure detected on HR-pQCT:A study in patients with rheumatoid arthritis and healthy subjects

\u3cp\u3eObjectives: The purpose of the study was to prospectively investigate change (repair or progression) in the number, surface area and volume of cortical interruptions, bone density (vBMD) and micro-structural parameters assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) in finger joints of patients with rheumatoid arthritis (RA) treated with synthetic disease modifying anti-rheumatic drugs (sDMARDs) and/or biologic DMARDs (bDMARDs) over a 1-year follow-up period, and in comparison with healthy subjects (HS). Methods: Thirty-two patients with RA (221 joints, 53% on bDMARDs) and 32 HS (117 joints) were assessed at baseline and after 1 year using semi-automatic analysis of HR-pQCT images. Mean changes (group level) and the proportion of joints (joint level) with changes beyond the least significant change were calculated. Results: At baseline, 530 interruptions were identified in patients, and 136 in HS. The mean of the interruption parameters did not significantly change in either group Mean vBMD decreased more in patients than in HS (− 4.4 versus − 1.1 mgHA/cm\u3csup\u3e3\u3c/sup\u3e, respectively). In patients versus HS, proportionally more joints showed repair in interruption volume (6.6% versus 1.7%, respectively) and loss of vBMD (26.7% versus 12.9%, respectively). In patients on sDMARDs versus patients on bDMARDs, proportionally more joints showed progression in the number of interruptions and loss of vBMD (6.1% versus 1.8% and 31.3% versus 17.2%, respectively). Conclusions: HR-pQCT is able to quantify bone repair and progression. Cortical interruption-, vBMD-, and micro-structure were impaired in RA, of which vBMD and micro-structure further deteriorated, particularly in patients on sDMARDs.\u3c/p\u3

Assessment of cortical interruptions in the finger joints of patients with Rheumatoid Arthritis using HR-pQCT, radiography, and MRI

\u3cp\u3eSmall cortical interruptions may be the first sign of an erosion, and more interruptions can be found in patients with rheumatoid arthritis (RA) compared with healthy subjects. First, we compared the number and size of interruptions in patients with RA with healthy subjects using high-resolution peripheral quantitative CT (HR-pQCT). Second, we investigated the association between structural damage and inflammatory markers on conventional radiography (CR) and MRI with interruptions on HR-pQCT. Third, the added value of HR-pQCT over CR and MRI was investigated. The finger joints of 39 patients with RA and 38 healthy subjects were examined through CR, MRI, and HR-pQCT. CRs were scored using the Sharp/Van der Heijde method. MRI images were analyzed for the presence of erosions, bone marrow edema, and synovitis. HR-pQCT images were analyzed for the number, surface area, and volume of interruptions using a semiautomated algorithm. Descriptives were calculated and associations were tested using generalized estimating equations. Significantly more interruptions and both a larger surface area and the volume of interruptions were detected in the metacarpophalangeal joints of patients with RA compared with healthy subjects (median, 2.0, 1.42 mm\u3csup\u3e2\u3c/sup\u3e, and 0.48 mm\u3csup\u3e3\u3c/sup\u3e versus 1.0, 0.69 mm\u3csup\u3e2\u3c/sup\u3e, and 0.23 mm\u3csup\u3e3\u3c/sup\u3e, respectively; all p < 0.01). Findings on CR and MRI were significantly associated with more and larger interruptions on HR-pQCT (prevalence ratios [PRs] ranging from 1.03 to 7.74; all p < 0.01) in all subjects, and were consistent in patients with RA alone. Having RA was significantly associated with more and larger interruptions on HR-pQCT (PRs, 2.33 to 5.39; all p < 0.01), also after adjustment for findings on CR or MRI. More and larger cortical interruptions were found in the finger joints of patients with RA versus healthy subjects, also after adjustment for findings on CR or MRI, implying that HR-pQCT imaging may be of value in addition to CR and MRI for the evaluation of structural damage in patients with RA.\u3c/p\u3

The reliability of a semi-automated algorithm for detection of cortical interruptions in finger joints on high resolution CT compared to microCT

\u3cp\u3eWe developed a semi-automated algorithm for the detection of cortical interruptions in finger joints using high-resolution peripheral quantitative computed tomography (HR-pQCT). Here, we tested its reliability compared to microCT (µCT) as gold standard. Nineteen joints of 10 female anatomic index fingers were imaged by HR-pQCT and µCT (82 and 18 µm isotropic voxel sizes, respectively). The algorithm was applied for detection of cortical interruptions of different minimum diameters (range >0.16 to >0.50 mm). Reliability was tested at the joint level with intra-class correlation coefficient (ICC) for the number of interruptions and interruption surface, and at the level of a single interruption for matching between HR-pQCT and µCT with a fixed interruption diameter (>0.10 mm) on µCT. The positive predictive value (PPV0.10mm) and sensitivity0.10mm were evaluated. The mean number of interruptions per joint depended on the diameter cut-off and ranged from 3.4 to 53.5 on HR-pQCT and from 1.8 to 45.1 on µCT for interruptions >0.50 to >0.16 mm, respectively. Reliability at the joint level was almost perfect (ICC ≥0.81) for both the number and surface of interruptions >0.16 and >0.33 mm. As expected, the PPV0.10mm increased with increasing interruption diameter from 84.9 to 100%, for interruptions >0.16 and >0.50 mm, respectively. However, the sensitivity0.10mm decreased with increasing interruption diameter from 62.4 to 4.7%. This semi-automated algorithm for HR-pQCT in finger joints performed best for the detection of cortical interruptions with a minimum diameter of >0.16 or >0.33 mm, showing almost perfect reliability at the joint level and interruptions matched with those on µCT.\u3c/p\u3

Development of a scoring method to visually score cortical interruptions on high-resolution peripheral quantitative computed tomography in rheumatoid arthritis and healthy controls

\u3cp\u3eOBJECTIVES: To develop a scoring method to visually score cortical interruptions in finger joints on High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT), determine its intra- and inter-reader reliability and test its feasibility.\u3c/p\u3e\u3cp\u3eMETHODS: The scoring method was developed by integrating results from in-depth discussions with experts, consensus meetings, multiple reading experiments and the literature. Cortical interruptions were scored by two independent readers in an imaging dataset with finger joints from patients with rheumatoid arthritis (RA) and healthy controls and assessed for adjacent trabecular distortion. Reliability for the total number of cortical interruptions per joint and per quadrant was calculated using intraclass correlation coefficient (ICC). Feasibility was tested by recording the time to analyze one joint.\u3c/p\u3e\u3cp\u3eRESULTS: In 98 joints we identified 252 cortical interruptions, 17% had trabecular distortion. Mean diameter of the interruptions was significantly larger in patients with RA compared with healthy controls (0.88 vs 0.47 mm, p = 0.03). Intra-reader reliability was ICC 0.88 (95% CI 0.83;0.92) per joint and ICC 0.69 (95% CI 0.65;0.73) per quadrant. Inter-reader reliability was ICC 0.48 (95% CI 0.20;0.67) per joint and ICC 0.56 (95% CI 0.49;0.62) per quadrant. The time to score one joint was mean 9.2 (SD 4.9) min.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: This scoring method allows detection of small cortical interruptions on HR-pQCT imaging of finger joints, which is promising for use in clinical studies.\u3c/p\u3

Contra-lateral bone loss at the distal radius in postmenopausal women after a distal radius fracture:a two-year follow-up HRpQCT study

\u3cp\u3eOpposite to the fracture side, bone mineral density (BMD) measured by DXA at the contra-lateral side does not change after a distal radius fracture. However, it is unknown if also bone micro-architecture and strength at the contralateral side are unaffected. Therefore, the aim of this study was to assess BMD, micro-architecture and bone mechanical properties at the contra-lateral side during two years follow-up after a distal radius fracture using high resolution peripheral quantitative computed tomography (HRpQCT). The contra-lateral distal radius of 15 postmenopausal women (mean age 64 ± 8 years) with a distal radius fracture treated by cast immobilization was scanned by HRpQCT at baseline, 3 months and 2 years post-fracture. BMD and cortical and trabecular micro-architecture were measured and biomechanical parameters were estimated using micro finite element analysis (μFEA). Additionally, markers of bone resorption and formation were measured at each visit. Bone parameters and turnover markers across the three visits were analysed using a linear mixed-effect model with Bonferroni correction. Two years post-fracture, a significant decrease from baseline was found in cortical BMD (− 4.2%, p < 0.001), failure load (− 6.1%, p = 0.001), stiffness in compression (− 5.7%, p = 0.003) and bending (− 6.4%, p = 0.008), and bone formation (− 47.6%, p = 0.010). No significant changes from baseline were observed in total and trabecular BMD, nor in cortical or trabecular micro-architecture and neither in bone resorption. Results were similar between patients with or without adequate anti-osteoporosis drug treatment. We found a significant decline in BMD in the cortical but not the trabecular region, and a reduction in bone strength and stiffness at the contra-lateral side two years after a distal radius fracture. These changes exceeded the changes that may be expected due to aging, even in the presence of adequate anti-osteoporosis treatment.\u3c/p\u3

Vascular channels in metacarpophalangeal joints:a comparative histologic and high-resolution imaging study

\u3cp\u3eWe evaluated whether cortical interruptions classified as vascular channel (VC) on high-resolution peripheral quantitative computed tomography (HR-pQCT) could be confirmed by histology. We subsequently evaluated the image characteristics of histologically identified VCs on matched single and multiplane HR-pQCT images. Four 3-mm thick portions in three anatomic metacarpophalangeal joint specimens were selected for histologic sectioning. First, VCs identified with HR-pQCT were examined for confirmation on histology. Second and independently, VCs identified by histology were matched to single and multiplane HR-pQCT images to assess for presence of cortical interruptions. Only one out of five cortical interruptions suggestive for VC on HR-pQCT could be confirmed on histology. In contrast, 52 VCs were identified by histology of which 39 (75%) could be classified as cortical interruption or periosteal excavation on matched single HR-pQCT slices. On multiplane HR-pQCT images, 11 (21%) showed a cortical interruption in at least two consecutive slices in two planes, 36 (69%) in at least one slice in two planes and five (10%) showed no cortical interruption. Substantially more VCs were present in histology sections than initially suggested by HR-pQCT. The small size and heterogeneous presentation, limit the identification as VC on HR-pQCT.\u3c/p\u3

An automated algorithm for the detection of cortical interruptions on high resolution peripheral quantitative computed tomography images of finger joints

\u3cp\u3eOBJECTIVES: To introduce a fully-automated algorithm for the detection of small cortical interruptions (≥0.246mm in diameter) on high resolution peripheral quantitative computed tomography (HR-pQCT) images, and to investigate the additional value of manual correction of the automatically obtained contours (semi-automated procedure).\u3c/p\u3e\u3cp\u3eMETHODS: Ten metacarpophalangeal joints from seven patients with rheumatoid arthritis (RA) and three healthy controls were imaged with HR-pQCT. The images were evaluated by an algorithm according to the fully- and semi-automated procedure for the number and surface of interruptions per joint. Reliability between the fully- and semi-automated procedure and between two independent operators was tested using intra-class correlation coefficient (ICC) and the proportion of matching interruptions. Validity of single interruptions detected was tested by comparing it to visual scoring, as gold standard. The positive predictive value (PPV) and sensitivity were calculated.\u3c/p\u3e\u3cp\u3eRESULTS: The median number of interruptions per joint was 14 (range 2 to 59) and did not significantly differ between the fully- and semi-automated procedure (p = 0.37). The median interruption surface per joint was significantly higher with the fully- vs. semi-automated procedure (respectively, 8.6mm2 vs. 5.8mm2 and 6.1mm2, p = 0.01). Reliability was almost perfect between the fully- and semi-automated procedure for both the number and surface of interruptions (ICC≥0.95) and the proportion of matching interruptions was high (≥76%). Also the inter-operator reliability was almost perfect (ICC≥0.97, proportion of matching interruptions 92%). The PPV ranged from 27.6% to 29.9%, and sensitivity from 69.7% to 76.3%. Most interruptions detected with the algorithm, did show an interruption on a 2D grayscale image. However, this interruption did not meet the criteria of an interruption with visual scoring.\u3c/p\u3e\u3cp\u3eCONCLUSION: The algorithm for HR-pQCT images detects cortical interruptions, and its interruption surface. Reliability and validity was comparable for the fully- and semi-automated procedures. However, we advise the use of the semi-automated procedure to assure quality. The algorithm is a promising tool for a sensitive and objective assessment of cortical interruptions in finger joints assessed by HR-pQCT.\u3c/p\u3