C. Trevisan

Dual X-ray absorptiometry for the evaluation of bone density from the proximal femur after total hip arthroplasty: Analysis protocols and reproducibility

SummaryDual X-ray absorptiometry (DXA) instruments are now able to evaluate bone mineral density (BMD) of bone surrounding metal implants. The assessment of BMD around prosthetic components could provide additional information for the follow-up of total hip arthroplasty (THA). In this study, we evaluated the potential application of DXA in the field of THA. BMD was measured in the proximal femur of both THA and THA-free sides in 14 postmenopausal women 6–18 months after THA. The explored segment was divided into seven zones as proposed by Gruen et al. [18]. The precision error of BMD measurements ranged from 1.8 to 6.8% on the THA side and from 1.1 to 2% to the THA-free side. The reduction of BMD of the THA versus the THA-free side was significant in all seven zones (P < 0.01, t-test for paired data). These results showed significant differences in BMD around femoral components of THA with respect to contralateral healthy side, and demonstrate the sensitivity of DXA for detecting these changes.

Regional Migratory Osteoporosis: A Pathogenetic Hypothesis based on Three Cases and a Review of the Literature

Abstract: Regional migratory osteoporosis (RMO) is a migrating arthralgia of the weight-bearing joints of the lower limb which mainly affects middle-aged males. Its aetiology is unknown. The association of RMO with generalised osteoporosis has recently been reported. A concurrent systemic osteoporosis was also reported in some cases of transient osteoporosis of the hip (TOH), a disorder closely related to RMO. In its turn, TOH is considered a reversible stage of avascular necrosis of the hip (AVN), and the aetiopathogenesis of both of them remains strongly debated. We report three cases of RMO associated with generalised severe idiopathic osteoporosis. Three men, in the fourth and fifth decades of life, complained of at least four episodes of arthralgia in the lower limbs, with a migratory pattern, radiographic focal osteoporosis and final clinical resolution. The most striking common feature of these patients was the presence of a severe systemic osteoporosis with a prevailing trabecular involvement. We suggest that a prolonged or exaggerated activation of regional acceleratory phenomena (RAP) is the cause of transient osteoporosis. Bone tissue microdamage due to osteoporosis may be the most frequent noxious stimulus that turns RAP on, and, bone tissue microfracture is the most prevalent consequence. When this pathogenetic pathway is activated, the progression from focal osteoporosis and bone marrow oedema to avascular necrosis is associated with the amount of structural damage.

Periprosthetic bone density around fully hydroxyapatite coated femoral stem

In this study, periprosthetic bone mineral density was measured at scheduled time intervals after surgery by dual energy xray absorptiometry in 21 patients to assess the history of bone density redistribution after femoral stem insertion. Measurements of changes in bone density with time were obtained for the regions of the greater trochanter, the lateral cortex, the tip, the medial cortex, and the calcar. In all regions, bone density decreased during the first 3 months after surgery; this was followed by a prolonged period of 18 to 30 months of bone gain, a subsequent period of steady state, and the final resumption of bone aging processes after the third postoperative year. The greatest loss was observed in the calcar region after 6 months (greater than 50%). The characteristic pattern of time related bone density changes obtained in this study may make it possible to compare other pathologic, design, or stiffness related patterns. This could have clinical relevance in the early diagnosis of pathologic processes and as a means of evaluating prosthetic designs.

Quantification by dual photonabsorptiometry of local bone loss after fracture

Total bone mineral and bone mineral density modifications were evaluated during fracture healing of long bones in patients with traumatic fractures of the lower limbs, using an experimental model based on the dual photonabsorptiometry technique. Seven patients (five males and two females; mean age, 19.5 years; range, 17-23 years) with tibia and fibula midshaft open fractures treated with osteosynthesis were studied. Dual energy gadolinium-153 photonabsorptiometry was used to measure distal leg bone loss at a skeletal segment distant from the fracture to exclude callus formation. Total bone mineral (TBM) and bone mineral density (BMD) of the tibia and fibula both in the fractured leg and in the healthy contralateral leg were measured on Days 10, 20, 30, 40, 60, and 120 after trauma. TBM and BMD of the healthy contralateral leg did not present any significant modifications at the different observation times. Both TBM and BMD of the fractured leg showed a progressive reduction that reached statistical significance starting on Day 30 with maximum reduction on Day 120 when TBM and BMD were reduced to almost one-half the initial value.

Bone mass status in different degrees of chronic renal failure

Bone mineral density (BMD) was evaluated in 69 patients with chronic renal failure (CRF) and in healthy controls matched for age, sex, and, for women, menopausal status. Both appendicular (predominantly cortical) and axial (predominantly trabecular) bone mass were measured. Appendicular BMD was measured by single photon absorptiometry on the distal forearm and axial BMD was measured by dual photon absorptiometry on the lumbar spine. Patients were divided into three groups on the basis of creatinine clearance: group 1, 58 to 36 ml/min; group 2, 30 to 18 ml/min; group 3, 15 to 9 ml/min. Both appendicular and axial BMD decreased with the worsening of renal failure. Parathyroid hormone levels were inversely correlated with the values of appendicular BMD. BMD values were significantly lower in postmenopausal than in premenopausal women. Months of menopause were inversely correlated with axial BMD values. Appendicular BMD was lower in CRF patients than in controls, and both appendicular and axial BMD were significantly lower in postmenopausal uremic women than in postmenopausal healthy women.

BONE ASSESSMENT AFTER TOTAL KNEE ARTHROPLASTY BY DUAL-ENERGY X-RAY ABSORPTIOMETRY : ANALYSIS PROTOCOL AND REPRODUCIBILITY

Abstract. Bone quality is important for the success of joint prostheses implantation, and the assessment of bone density after total knee arthroplasty by means of dual-energy X-ray absorptiometry may be useful for monitoring implant stability. The aim of this study is to suggest a validated analysis protocol for the assessment of bone status after total knee arthroplasty. A dedicated densitometric analysis protocol of five regions of interest was designed, and 10 subjects who had received an uncemented knee prosthesis (8 females and 2 males, aged 55–74 years) underwent three consecutive scans in posteroanterior and lateral projections, with repositioning after each scan to test the suitability and reproducibility of the protocol. The reproducibility of the measurement of bone mineral content and density in the femoral and tibial regions ranged, respectively, from 2.1% to 4.1%, from 0.9% to 2.6% for the posteroanterior scans, and from 2.7% to 5.6% and from 2.3% to 4.7% for the lateral scans, depending on the considered region. Our results confirm that the suggested protocol allows precise assessment of bone mineral content and density, and that dual-energy X-ray absorptiometry is reliable for the evaluation of bone mass around prosthetic implants.

Age, time since menopause, and body parameters as determinants of female spinal bone mass: A mathematical model

SummaryThe study of mathematical models to describe bone mass behavior throughout life is a possibility for assessing the main factors of peak bone mass and bone loss.We developed a mathematical model to predict spinal bone mass behavior on a sample of 181 healthy Italian women whose lumbar bone mineral content was determined by Gd-153 dual photon absorptiometry. This model proved to be both efficient, showing the best fit (r=0.7 on spinal bone mineral content) when compared to other previously suggested models, and also reliable as its fit remained the best when applied to a subsequent sample of 519 women whose lumbar spine was measured by dual X-ray photon absorptiometry. This model suggests that body height and body weight (but not age) are determinants of bone mass in premenopausal women. In postmenopausal women, an accelerated phase of bone loss starting at menopause is dependent on age and time since menopause, whereas body mass index acts as a protective factor. This model confirms the influence on spinal bone mass not only of age and time since menopause but also of body size parameters.

Bone Loss and Recovery in Regional Migratory Osteoporosis

Abstract: Regional migratory osteoporosis (RMO) is a migrating arthralgia of the weight-bearing joints of the lower limb associated with focal osteoporosis. Little information is available on a quantitative assessment of systemic or local osteoporosis. In this study, we report three cases of RMO in which spine, hip and whole body serial assessments of bone mass have been evaluated to outline their extent and time course of changes. Systemic osteoporosis, with a prevalent involvement of the mainly trabecular skeletal sites, was present in all the patients, with T-scores below −2.5 at both the lumbar spine and femoral neck. Bone loss in acute episodes ranged from −75.5% to −14.7% and appeared related to the severity of the episode. In acute episodes the demineralizing process affected the whole limb from the hemipelvis to the foot: the bone loss ranged from −33.6% to −3.5% at sites with prevalent trabecular composition and from −19.1% to −1.1% at sites with prevalent cortical composition. Bone recovery was complete in one episode out of six. In the other five cases, the average residual bone loss was 26% (range 13.9–32.7%). Our observations suggest that RMO occurs in subjects with systemic osteoporosis and densitometric assessment may aid in the clinical management.

Graft-tunnel mismatch in endoscopic anterior cruciate ligament reconstruction: Intraoperative and cadaver measurement of the intra-articular graft length and the length of the patellar tendon

Abstract The results of a study conducted on 50 knees endoscopically reconstructed for an anterior cruciate ligament (ACL) lesion with a free bone-patellar tendon-bone graft and 9 cadaver knees are reported. The mean lengths of the patellar tendon (45.48 ± 4.71 mm) and intra-articular ACL graft (20.44 ± 1.98 mm) were measured in the operated knees. The mean length of the tibial bone tunnel (51.62 ± 2.60 mm) was also measured with a tibial guide at 55°. No statistically significant correlation was found between these three measurements. The length of the patellar tendon was weakly correlated with body height. Measurement of the tibial tunnel on the cadaver knees with increasing degrees of inclination revealed a mean length increase of 0.68 mm per degree (confidence limits: 0.49–0.86). Comparison between the tunnel lengths obtained with the guide and those measured with a Kirschner wire showed a mean difference of 2.3 mm. It is thus desirable to make the tunnel about 53 mm long to ensure excellent fixation of a 28 mm bone block with a 25 mm interference screw. Correct measurement of the anatomical structures involved is in any event an essential requirement for proper execution of the surgical technique.

Spinal and forearm bone mass in relation to ageing and menopause in healthy Italian women

Abstract. Most studies concerning bone status have been performed in Nordic and Anglo‐Saxon countries and few data are available on southern European populations.