Advertisement for orthosearch.org.uk
Results 1 - 2 of 2
Results per page:
Applied filters
Include Proceedings
Dates
Year From

Year To
Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 443 - 443
1 Sep 2009
van Aken J Verdonschot N Huizenga H Kooloos J Tanck E
Full Access

Bone metastases occur in about 15% of all cancer cases. Pathological fractures that result from these tumours most frequently occur in the femur. It is extremely difficult to determine the fracture risk with the current X-ray methods, even for experienced physicians. The purpose of this study was to assess whether the use of a predictive finite element model could improve the prediction of strength in comparison to an clinical assessment.

Eight human cadaver femora, with and without simulated metastases, were CT-scanned. A solid calibration phantom was included in each scan. From the scans, eight finite element (FE) models were generated using brick elements. The non-linear mechanical properties were based on bone density. After scanning, laboratory experiments were performed. The femora were loaded under compression until failure. During the experiments the failure forces and the course of failure were registered. These experiments were simulated in the FE-models, in which plastic deformation simulated failure of the bones. Six experienced physicians, were asked to rank the femora on strength using X-rays (AP and ML) and additional information on gender and age.

The results showed a strong Pearson’s correlation (r2 = 0.92) between the experimental failure force and predicted failure force. The Spearman’s rank correlations between experiment and predictions ranged between ρ=0.58 and ρ=0.8 for the physicians, whereas it was significantly higher (ρ=0.92) for the FE-model

This study showed that femur specific FE models better predicted femoral failure risk under axial loading than experienced physicians. When the model is further improved by adding, for example, other loading conditions, it can be clinically implemented to predict in vivo fracture risk for patients suffering, for example, bone metastases or osteoporosis.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 368 - 368
1 Mar 2004
Boonstra M Jenniskens A Barink M Kooloos J Verdonschot N De Waal Malefijt M
Full Access

Aims: The purpose of this study is to validate a novel, quantitative functional test for TKA patients using commonly used subjective questionnaires as standard. Methods: Electrogoniometry was used to get information about the stability of rising from a chair. Thirteen pre Ðoperative TKA patients were measured while rising from a chair at two different heights. Using phaseplots (relationship between joint angle and joint velocity), the relative phase between the hip and knee was calculated. Instability was deþned as the standard deviation over ten trials for every patient and each height. An independent physician administered the WOMAC, KSS and SF-36 questionnaires. The instability factor of rising was correlated (using Spearmanñs Rho) to the outcomes of the questionnaires. Results: The stability of rising correlated moderately high with the questionnaires. Best correlations were calculated for instability and the WOMAC and SF-36 physical functioning (0.45 and 0.56, respectively). The worst correlation was with the KSS pain score (0.05). In general, the correlations for the lowest chair height were slightly higher. Conclusions: As there is no gold standard for functional evaluation of the TKA, a chair rise protocol has been developed. In this study the stability of rising correlates moderately high with the WOMAC, KSS and SF-36 questionnaires. The stability of rising from a lower chair seems to discriminate better than rising from a higher chair. This test will be used as a quantitative functional follow up of TKA patients.