The CNAP device provided feasible estimates of BP in unselected medical ICU patients under routine clinical conditions. Mean arterial pressure met interchangeability criteria for accuracy toward radial arterial pressure, as well as for percentage error, and showed good trending capabilities according to the Critchley predefined criteria.

Purpose Tumours of the calcaneus are exceedingly rare and the correct diagnosis is often missed. X-rays are the standard clinical examination tool and therefore we wanted to discover whether X-rays alone were a sufficient diagnostic tool for these tumours. Diard's classification was applied to define whether different types of lesions were characteristically distributed in the bone and in addition we analysed whether type and/or duration of symptoms were possible indicators of malignancy. Methods Ninety-two patients' files (59 men and 33 women) were retrospectively reviewed. Seventy-five patients with a mean age at surgery of 28 years (range five to 78) were surgically treated. Parameters analysed were sex, age at surgery, side, type and duration of symptoms, tentative diagnosis, biopsy prior to surgery, operative procedure, recurrence rate, revision and localisation of the lesion according to Diard. For each lesion the first documented radiological diagnosis andin cases of malignancy-Enneking's classification was applied.Results Discrepancies between the radiological and definitive histological diagnosis occurred in 38 (41 %) of 92 cases. In eight (osteosarcoma n =5, Ewing's sarcoma n =2, metastases n =1) of 17 malignant cases radiological examination initially gave no evidence of malignancy, resulting in an unplanned excision ("whoops procedure") in three cases of osteosarcoma. Applying Diard's system trabecular area 6 (radiolucent area) was highly affected in 64 (80 %) of 80 investigated plain Xrays, whereas areas 1 and 5 were affected in nine (11 %) and 16 (20 %) cases only. Conclusions In each case of an osteolytic lesion of the calcaneus a malignant tumour must be ruled out, and thus preoperative plain X-rays in two planes alone are not sufficient and should therefore be followed by magnetic resonance imaging. Applying the Diard system different types of lesions are not characteristically distributed in the bone. Increasing pain for more than ten days without previous trauma should always justify further examinations.

The purpose of this study was to determine the concentrations of cobalt, chromium, and molybdenum in the serum of paediatric tumour patients after fixed hinge total knee arthroplasty. Further, these metal ion levels were compared with serum metal ion levels of patients with other orthopaedic devices such as hip and knee prostheses with metal-on-metal or metal-on-polyethylene articulation to find differences between anatomical locations, abrasion characteristics, and bearing surfaces. After an average follow-up of 108 months (range: 67 to 163) of 11 paediatric patients with fixed hinge total knee arthroplasty, the mean concentrations for Co and Cr were significantly increased while Mo was within the limits compared to the upper values from the reference laboratory. Furthermore, these serum concentrations were significantly higher compared to patients with a standard rotating hinge device (P = 0.002 and P < 0.001) and preoperative controls (P < 0.001). On the other hand, the serum levels of patients following MoM THA or rotating hinge arthroplasty using megaprostheses were higher. Therefore, periodic long-term follow-ups are recommended due to the rising concerns about systemic metal ion exposure in the literature. Upon the occurrence of adverse reactions to metal debris the revision of the fixed hinge implant should be considered.

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Abstract-This paper presents a non-invasive measurement method to detect and characterize failures and material imperfections in total joint prostheses based on acceleration measurement. Therefore, a prototype sensor has been developed to fulfill the requirements of a medical-technical sensor. This sensor has been tested on patients with total hip arthroplasty. Special emphasis is put on the real-time processing of measurement data by means of intelligent signal processing as well as reliable and repeatable measurement procedures, including standardized positions for the sensor front-end and a standardized motion-sequence the patient is performing.