3D visualization and open planning platform in virtual fluoroscopy.

Typically virtual fluoroscopy systems display the tracked instruments as a projected shadow on a number of 2D x-ray images completely missing the depth information of the third dimension. This paper describes an extra tool for 3D reconstruction in virtual fluoroscopy which is useful to clarify the position of instruments or anatomy and can be used in planning and assessing surgical procedure without further x-ray images. Two examples are given: displaced subtrochanteric fracture and slipped upper femoral epiphysis is presented.

Smart tool for force measurements during knee arthroscopy: in vivo human study.

This paper describes the magnitude and patterns of forces obtained by using a probe, equipped with a six-axis force torque sensor, in knee arthroscopy. The probe was used by orthopaedic surgeons and trainees, who performed 11 different tasks in 10 standard knee arthroscopies. The force magnitude and patterns generated are presented; which can support the development of virtual arthroscopy systems with realistic haptic feedback. The results were compared across both groups of surgeons. A difference in the force patterns generated by senior versus junior surgeons was noted which can aid in the development of an objective assessment system for arthroscopy skills. The results could potentially be useful to assess future performance in real arthroscopy.

Factors affecting targeting using the computer assisted orthopaedic surgery system (CAOSS).

An advantage of CAOS over traditional surgery is improved precision of implant position and trajectories in 3D space. However, the implementation of these trajectories often adds an extra step to the operation that increases operative time and requires extra training. This paper reports a study of variation in time-to-task and learning curve in performing a standard task of targeting in 3D space using Hull's CAOSS. It shows that time-to-task can be reduced by replacing a 3D targeting task with multiple independent 2D targeting tasks whilst potentially reducing targeting error. Based on this better understanding of targeting a novel jig was developed for performing dynamic hip Screw (DHS) insertion using CAOSS that would provide improved targeting performance by the surgeon.

Is there an association between body temperature and serum lactate levels in hip fracture patients?

Introduction Hyperlactataemia is associated with adverse outcomes in trauma cases. It is thought to be the result of anaerobic respiration during hypoperfusion. This produces much less energy than complete aerobic glycolysis. Low body temperature in the injured patient carries an equally poor prognosis. Significant amounts of energy are expended in maintaining euthermia. Consequently, there may be a link between lactate levels and dysthermia. Hyperlactataemia may be indicative of inefficient energy production and therefore insufficient energy to maintain euthermia. Alternatively, significant amounts of available oxygen may be sequestered in thermoregulation, resulting in anaerobic respiration and lactate production. Our study investigated whether there is an association between lactate levels and admission body temperature in hip fracture patients. Furthermore, it looked at whether there is a difference in the mean lactate levels between hip fracture patients with low (<36.5°C), normal (36.5-37.5°C) and high (>37.5°C) body temperature on admission, and for patients who have low body temperature, whether there is a progressive rise in serum lactate levels as body temperature falls. Methods The admission temperature and serum lactate of 1,162 patients presenting with hip fracture were recorded. Patients were divided into the euthermic (body temperature 36.5-37.5°C), the pyrexial (>37.5°C) and those with low body temperature (<36.5°C). Admission lactate and body temperature were compared. Results There was a significant difference in age between the three body temperature groups (p=0.007). The pyrexial cohort was younger than the low body temperature group (mean: 78 vs 82 years). Those with low body temperature had a higher mean lactate level than the euthermic (2.2mmol/l vs 2.0mmol/l, p=0.03). However, there was no progressive rise in serum lactate level as admission temperature fell. Conclusions The findings suggest that in hip fracture patients, the body attempts initially to maintain euthermia, incurring an oxygen debt. This would explain the difference in lactate level between the low body temperature and euthermic cohorts. The fact that there is no correlation with the degree of temperature depression and lactate levels indicates that the body does not fuel thermohomeostasis indefinitely with oxygen. Instead, in part, it abandons thermoregulatory mechanisms. Consequently, in this population, active rewarming may be indicated rather than depending on patients' own thermogenic ability.

[Contribution of radiology to the diagnosis and treatment of nasopharyngeal fibroma. Apropos of 6 cases]. / Apport de la radiologie dans le diagnostic et le traitement du fibrome nasopharyngien. A propos de 6 cas.

The authors report about their experience with 6 cases of nasopharyngeal fibroma. They emphasize the interest of CT examinations in the diagnostic study, and above all in the assessment of regional extension. The angiographic study must be as complete as possible, and should include an embolization within 2 to 5 days prior to surgical excision as often as this is possible. Embolization is a simple procedure if performed strictly and carefully in order to avoid any complication.

Simple whiplash?

We describe a case of type-I Arnold-Chiari malformation in a 27-year-old woman who presented on two separate occasions with an apparent whiplash injury. She developed debilitating symptoms after two apparently low velocity vehicle collisions. MRI revealed a type-I Arnold-Chiari malformation. She was referred for consideration of neurosurgical decompression. Type-I Arnold-Chiari malformation is the downward herniation of the cerebellar tonsils through the foramen magnum. It is usually asymptomatic but may present after apparently insignificant trauma with a wide range of possible symptoms. The protean nature of its presentation and the similarity of the symptoms to those of a whiplash injury mean that it is easily overlooked. It is, however, important that it is detected early.

Impending fractures in giant cell tumours of the distal femur: incidence and outcome.

Giant cell tumours are rare bone tumours that are characteristically benign but locally aggressive, most frequently occurring in the distal femur with pathological fractures being common. This paper investigates relationships between tumour size and cortical breach on initial X-rays and subsequent treatment. The X-rays of 54 patients with distal femoral giant cell tumours were reviewed. The volumes of the tumour, distal femur and a ratio between the two parameters were estimated. The presence of a cortical breach, discrete fracture and Campanacci grade was recorded. X-rays revealed intact cortical rim in 20 patients (37%), cortical breach in 22 patients (41%) and discrete fracture in 12 patients (22%). There was a significant difference in the ratio of tumour volume to distal femoral volume between the discrete fracture group and the cortical breach group. No significant differences in rates of local recurrence were demonstrated. Extended curettage was effective for intact and cortical breach groups; however, patients in the fracture group often required radical treatment.