News-Screen Osteologie

Measurement of skin thickness has been proposed as a method of predicting low bone mineral density (BMD) and the consequent risk of osteoporotic fracture in postmenopausal women. The Episcan I-100 device is a new type of ultrasound device that uses high-frequency (20 MHz) ultrasound to measure skin thickness using a small probe placed on the skin. The aims of this study were to investigate whether there is any correlation between skin thickness as measured by ultrasound and BMD as measured by dualenergy X-ray absorptiometry, to establish whether patients with osteoporotic fractures have reduced skin thickness, and to investigate the relationship between skin thickness and clinical risk factors for osteoporosis. Short-term precision based on duplicate measurements on 132 patients gave a coefficient of variation of 3.2%. Small but statistically significant correlations between skin thickness measurements and BMD measurements at axial and peripheral sites were observed (r = 0.21–0.29, P < 0.0001). An odds ratio of 1.42 was found for identifying patients with a prevalent fracture at any skeletal site, suggesting that skin thickness measurements can discriminate patients with fractures. ROC analyses also demonstrated the ability of skin thickness measurements to discriminate fracture patients from controls. When measured by the decrease in Z-score, clinical risk factors for low BMD were found to affect skin thickness measurements to a similar extent as spine and hip BMD measurements. Skin thickness measurements have limited utility in identifying patients with low bone mass. Does Bone Quality Predict Loosening of Cemented Total Hip Replacements? Nixon M et al. J Bone Joint Surg Br 2007; 89: 1303–8. Abstract We matched 78 patients with a loose cemented Charnley Elite Plus total hip replacement (THR) by age, gender, race, prosthesis and time from surgery with 49 patients with a well-fixed stable hip replacement, to determine if poor bone quality predisposes to loosening. Clinical, radiological, biomechanical and bone mineral density indicators of bone quality were assessed. Patients with loose replacements had more pain, were more likely to have presented with atrophic arthritis and to have a history of fragility fracture, narrower femoral cortices and lower periprosthetic or lumbar spine bone mineral density (all t-test, p < 0.01). They also tended to be smokers (chi-squared test, p = 0.08). Vitamin-D deficiency was common, but not significantly different between the two groups (t-test, p = 0.31) In this series of cemented hip replacements performed between 1994 and 1998, aseptic loosening was associated with poor bone quality. Patients with a THR should be screened for osteoporosis and have regular radiological surveillance.We matched 78 patients with a loose cemented Charnley Elite Plus total hip replacement (THR) by age, gender, race, prosthesis and time from surgery with 49 patients with a well-fixed stable hip replacement, to determine if poor bone quality predisposes to loosening. Clinical, radiological, biomechanical and bone mineral density indicators of bone quality were assessed. Patients with loose replacements had more pain, were more likely to have presented with atrophic arthritis and to have a history of fragility fracture, narrower femoral cortices and lower periprosthetic or lumbar spine bone mineral density (all t-test, p < 0.01). They also tended to be smokers (chi-squared test, p = 0.08). Vitamin-D deficiency was common, but not significantly different between the two groups (t-test, p = 0.31) In this series of cemented hip replacements performed between 1994 and 1998, aseptic loosening was associated with poor bone quality. Patients with a THR should be screened for osteoporosis and have regular radiological surveillance. Die aseptische Lockerung einer zementierten Hüftendoprothese ist mit einer verminderten Knochendichte assoziiert Alle 127 Patienten hatten zementierte Hüftprothesen (Charnley Elite Plus, DePuy International, Leeds, UK), die im University Hospital Leicester zwischen 1994 und 1998 implantiert wurden. Die postoperativen und die aktuellsten Röntgenaufnahmen wurden in Bezug auf Prothesenlockerung nach der Klassifikation von Dall (bis 10 Punkte leichte Lockerung, über 10 Punkte relevante Lockerung) untersucht. Bei 75 Patienten wurde des Weiteren die Knochendichte mittels Osteodensitometrie bestimmt. Von den 127 Patienten wiesen 49 keine Lockerung auf (38 %), 43 (34 %) hatten eine leichte Lockerung, 35 (28 %) hatten eine relevante Lockerung. Patienten mit Prothesenlockerung hatten häufiger eine Anamnese mit Frakturen (25 %) gegenüber den Patienten ohne Prothesenlockerung (8 %). Die mittlere periprothetische Knochendichte war signifikant niedriger bei Patienten mit Lockerung versus jenen ohne Lockerung. Auch die Knochendichte an der Lendenwirbelsäule (< 2 SD) war bei Patienten mit Lockerung häufiger erniedrigt. Kommentar Knochendichte und Knochenqualität scheinen Faktoren zu sein, die Prothesenlockerung mit anderen Faktoren (z. B. Raucher-Status) beeinflussen. Eine osteologische Abklärung vor der Prothesenimplantation sowie auch Verlaufskontrollen werden aufgrund dessen von den Autoren empfohlen. News-Screen Osteologie