Are Doppler studies a useful method of assessing neovascularization in human Achilles tendinopathy? A systematic review and suggestions for optimizing machine settings.

Achilles tendinopathy describes a painful condition. The symptoms include localized swelling and tenderness, and the condition is often associated with altered tendon structure and neovascularization. Doppler ultrasound has been used in Achilles neovascularization and despite the lack of standardization and machine settings, recent research has demonstrated a potential relationship between pathology and the presence of neovascularization. This paper is a systematic review of the published studies which have used Doppler ultrasound in the assessment of Achilles neovascularization, and a prospective study to suggest a degree of optimization for future studies.

A review of high frequency oscillation ventilation in the neonate.

In this study the use of high frequency oscillation (HFO) to treat neonates with respiratory failure is analysed. The theories behind gas exchange during HFO are reviewed and its specific application to neonatal care discussed. The mechanical performance of three HFO ventilators currently in use is compared with the views of medical staff operating them on a regular basis. The complex interactions between initial ventilator settings have led to difficulties in accurately comparing performance characteristics and ventilation strategies; each ventilator is seen to have its own strengths and weaknesses that contribute to the ventilator selection made. These interactions together with the specific HFO modes available on each ventilator should be taken into account when using a HFO for the first time or when switching from an alternative ventilation method. Medical staff who care for neonates suggest staff education and training into the variations of HFO will greatly improve its use in neonatal medicine.

Lubrication regime of the contact between fat and bone in bovine tissue.

Fat pads are masses of encapsulated adipose tissue located throughout the human body. Whilst a number of studies describe these soft tissues anatomically little is known about their biomechanics, and surgeons may excise them arthroscopically if they hinder visual inspection of the joint or bursa. By measuring the coefficient of friction between, and performing Sommerfeld analysis of, the surfaces approximating the in vivo conjuncture, this contact has been shown to have a coefficient of friction of the order of 0.01. The system appears to be lubricated hydrodynamically, thus possibly promoting low levels of wear. It is suggested that one of the functions of fat pads associated with subtendinous bursae and synovial joints is to generate a hydrodynamic lubricating layer between the opposing surfaces.

Applications of nanotechnology in orthopaedics.

Nanotechnology is the application of science and engineering at the nanoscale. A diverse range of applications are beginning to emerge in all areas of medicine. We performed a survey from November 2005 to March 2006 using the Internet search engines PubMed, ScienceDirect, ISI Web of Knowledge, and Google Scholar. We report on the role of nanotechnology in orthopaedics, exploring current and potential applications. Nanostructured materials have been proposed as the next generation of orthopaedic implant properties by creating a surface environment more conducive for osteoblast function. Bone substitute materials, whose nanoscale composition emulates the hierarchic organization of natural bone, shows initiation of the desirable formation of an apatite layer. Nanotechnology also has been harnessed to improve the cutting performance and quality of surgical blades. Postoperative infection rates may be reduced by using nanofibrous membrane wound dressings containing antibacterial properties. The most notable application of nanotechnology in orthopaedics may be drug delivery, including nanotherapeutics for treating bone cancer and arthritis. Nanotechnology is being used in orthopaedics, and likely will play a valuable role in future developments.

Literature review of current techniques for the insertion of distal screws into intramedullary locking nails.

The procedure for distal interlocking of intramedullary nails can be difficult and time consuming. Following nail insertion, the problems associated with the location of the distal holes and correct screw placements are well known. Numerous techniques and devices have been proposed to aid distal targeting, in attempts to overcome some of the associated problems. The development of the techniques and devices continues. A review of the literature is therefore timely, in order to provide awareness of the current situation. An overview is presented of the various distal targeting methods reported in the literature.

A model of dynamic sacro-iliac joint instability from malrecruitment of gluteus maximus and biceps femoris muscles resulting in low back pain.

The objective of this work is to propose a biomechanical model of sacro-iliac joint dysfunction as a cause of low back pain. Sacro-iliac joint is known to be a source of low back pain. We also know that it is a very stable joint with little mobility. Surrounding lower limb and back muscles contribute a major part of this stability. Gait analysis studies have revealed an orderly sequence of muscle activation when we walk - that contributes to efficient stabilisation of the joint and effective weight transfer to the lower limb. Gluteus maximus fibres-lying almost perpendicular to the joint surfaces are ideally oriented for this purpose. Biceps femoris is another important muscle that can also influence joint stability by its proximal attachment to sacrotuberous ligament. Altered pattern of muscle recruitment has been observed in patients with low back pain. But we do not know the exact cause-effect relationship. Because of its position as a key linkage in transmission of weight from the upper limbs to the lower, poor joint stability could have major consequences on weight bearing. It is proposed that sacro-iliac joint dysfunction can result from malrecruitment of gluteus maximus motor units during weight bearing. This results in compensatory biceps over activation. The resulting soft tissue strain and joint instability may manifest itself in low back pain. If our hypothesis holds true, it may have positive implications for patients with sacro-iliac joint dysfunction - who could be offered a definite diagnosis and targeted physiotherapy. It may be possible to identify patients early in a primary care setting and offer direct physio referral. They could benefit from exercises to improve strengthening and recruitment of the affected muscles.

Subdural haemorrhage sustained in a baby-rocker? A biomechanical approach to causation.

An unconscious 8 weeks old infant was admitted to hospital and found to have bilateral, subdural and retinal haemorrhages. He died the following day. The explanation for the subdural haemorrhage put forward by his carers was that the infant had been in a baby-rocker and that the carers had seen the rocker being rocked vigorously by their 14 months old daughter on two separate occasions. This paper describes the biomechanics of an infant model in the particular baby-rocker used and determines the maximum forces generated, comparing them with the 'forces' thought to be compatible with the causation of subdural haemorrhage.

The potential and limitations of utilising head impact injury models to assess the likelihood of significant head injury in infants after a fall.

The use of engineering principles in assessing head injury scenarios is of increasing significance in investigations into suspected child abuse. A fall scenario is often given as the history for a head injury to an infant. This paper addresses the basic engineering principles and factors to be considered when calculating the severity of a head impact after free-fall. The application of head injury models (HIMs) to ascertain the forces involved in childhood head injuries from impact is also discussed. Previous studies including Duhaime et al. [J. Neurosurg. 66 (1987) 409] and Nokes et al. [Forensic Sci. Int. 79 (1995) 85] have utilised HIMs for this purpose: this paper reviews those models most widely documented.The HIM currently considered the 'state-of-the-art' is the head injury criterion (HIC) and it is suggested that this model should be utilised for assessing head impact injury in child abuse cases where appropriate.

A biomechanical reconstruction of a wound caused by a glass shard--a case report.

During the course of a criminal trial, an investigating pathologist is commonly asked how much force was required to produce an injury. This subjective opinion is based on the pathologist's previous experience of dealing with wounds inflicted with similar weapons. However, in the case of stab wounds inflicted by broken glass, it is unlikely that two glass fragments would be physically similar. In the case studied, two theories were examined: that a wound resulted from a thrown glass fragment or that it had been caused as a stab injury by the glass held in the bare hand. The investigation involved quantifying the energy required for human tissue penetration, comparison of sharpness, a biomechanical analysis of throwing actions and testing of the hypothesis that if the glass shard were used as a stabbing implement it would result in a cut to the hand.The investigation utilised a scientific methodology that reduced the need for speculative (though informed) opinion from the pathologist by producing quantitative results.

A novel approach to forensic investigation: three-dimensional kinematic and kinetic motion analysis.

Following a domestic incident, a five-year-old child was pronounced dead on arrival at hospital. The subsequent post-mortem examination found that the cause of death was peritonitis as a result of a rupture of the duodenum. During the police interview, the main suspect alleged that the injury occurred whilst playing a game which involved standing on the child's abdomen and chest. A reconstruction of the game was performed using 3-dimensional kinematic and kinetic motion analysis to investigate the feasibility of the statement as described by the defendant. Presented is a summary of the investigation together with a description of kinematic and kinetic methods employed.

Subjective assessment of blunt impacts.

An important role of an eyewitness to an assault is to effectively quantify the degree of force used; yet evidence of this form is often subjective and relies on personal opinion. Twelve subjects were asked to strike a load cell with a wooden bat, using varying degrees of force. The strikes were recorded by video camera and 50 people observed the video and were asked to grade the strikes. On average 44% accurately assessed the severity of the strikes, whilst 26% over-estimated. Results suggest that the evidence of eyewitnesses should be treated with caution.

Observation on the recent examination of bones from St David's Cathedral.

Bones discovered in 1866 walled up in St David's Cathedral, West Wales were thought possibly to be those of St David and his companion St Justinian, both of whom died in the late 6th or early 7th century. Examination and radio carbon dating of the bones suggested that these were not from St David nor St Justinian. Some of the bones could be the remains of St Caradoc, a 12th century hermit. It is likely, however, that the bones are remains of clergy who, for reasons not yet understood, were re-interred into the wall.

Dynamics of stab wounds: force required for penetration of various cadaveric human tissues.

It is often said that once the skin has been penetrated no further force is required to produce penetration of underlying tissues. This experimental study has used technology which was not available to earlier investigators to examine this issue in detail. The results confirm the importance of skin penetration but indicate that the penetration of other tissues may also require significant force.

The use of low-frequency vibration measurement in orthopaedics.

This paper reviews the literature regarding the use of applying conventional low-frequency vibration analysis as a possible diagnostic tool in the orthopaedic field. Although a considerable number of investigations have been carried out, including the effects of soft tissue, the technique has not been widely accepted clinically. The application of ultrasound appears to be a more realistic alternative.

The use of ultrasonics in orthopaedics--a review.

Ultrasonic testing of bones has been used with varying degrees of success for more than 40 years to determine mechanical properties of bone tissue and strength of whole bones. Ultrasound has also been used in an effort to develop non-invasive techniques for monitoring fracture healing in long bones. Despite early promising results, clinically useful methods have yet to be developed. This paper provides a comprehensive review of the literature of determining mechanical properties of bone and the monitoring of fracture healing.

Biomechanics of judicial hanging: a case report.

A prisoner in Washington State in the United States of America appealed against sentence of death by hanging on the grounds that it was 'cruel and unusual' and hence contravened the Eighth Amendment of the US Constitution. The man weighed 184 kg (406 lb) and it was suggested that the 'drop' proposed to effect judicial hanging might result in decapitation. This hypothesis was tested by applying simple biodynamic principles to the available data from past hangings. It was concluded that decapitation was a significant possibility.

Postmortem electrical excitability of skeletal muscle: preliminary investigation of an animal model.

Presented is a preliminary study of the feasibility of using an animal model to investigate the postmortem time-dependent decay in muscular response, when subjected to electrical stimulation and to develop an animal model for the assessment of the use of electrical excitability as a method for determining the postmortem period of a human corpse. Analysis of the results shows a correlation between the rate of decay of muscular response with the postmortem interval.

Determination of fracture healing by transverse vibration measurement: a preliminary report.

We present results from seven patients with closed mid-shaft tibial fractures and question the hypothesis that transverse wave response ratio analysis could be used to assess the progress of healing fractures. No correlation could be found between the response ratio and the post-fracture time as an indicator of bone fracture healing.

Examination of the eye as a means to determine the early postmortem period: a review of the literature.

Reported are various techniques to determine the early postmortem period by examining the eye. These include corneal opacity, retinal vessel segmentation, pupil reaction, retinal changes and intraocular pressure. All are subjective, requiring experience to implement the techniques.