Long bone fractures are a commonly presented paediatric injury. Whilst the possibility of either accidental or non-accidental aetiology ensures significant forensic relevance, there remain few clinical approaches that assist with this differential diagnosis. The aim of this current study was to generate a reproducible model of spiral fracture in immature bone, allowing investigation of the potential relationship between the rotational speed and the angle of the subsequent spiral fracture.

Seventy bovine metacarpal bones were harvested from 7 day old calves. Sharp dissection ensured removal of the soft tissue, whilst preserving the periosteum. The bones were then distributed evenly before eleven groups, before being aligned along their central axis within a torsional testing machine. Each group of bones were then tested to failure at a different rotational speed (0.5, 1, 15, 20, 30, 40, 45, 60, 75, 80 and 90 degrees s-1). The angle of spiral fracture, relative to the long axis, was then measured, whilst the fracture location, the extent of comminution and periosteal disruption, were all recorded.

Sixty-two out of 70 specimens failed in spiral fracture, with the remaining tests failing at the anchorage site. All bone fractures centred on the narrowest waist diameter, with 5 specimens (all tested at 90 degrees s-1) demonstrating comminution and periosteal disruption. The recorded spiral fracture angles ranged from 30 - 45 degrees, and were dependant on the rotational speed.

This study has established a relationship between the speed of rotation and the angle of spiral fracture in immature bovine bone. It is anticipated that further study will enable investigation of this trend in paediatric bone, ultimately providing an additional diagnostic tool for clinicians trying to verify the proposed mechanism of injury.

Frictional resistance to tendon gliding is minimised by surrounding loose areolar tissues. During periods of prolonged immobilisation, for example post tendon-repair, adhesions can form between the two adjacent tissues, thereby limiting function. Whilst agents applied during surgery are recognised to succeed in adhesion prevention, they have also been reported to provide some reduction in friction during in vitro tendon-bony pulley investigations. This study investigated the effectiveness of common anti-adhesion agents in lubricating the tendon-surrounding tissue contact by comparison with a control study. By using a validated apparatus and with reference to the Stribeck curve, it was determined that the natural in vivo contact is likely to be lubricated by a film of synovial-like fluid. Application of all anti-adhesives generated a similarly efficient lubricating system, and hence administration of these agents should be encouraged to all regions of the tendon disrupted during surgery. Minimising frictional resistance to gliding will reduce the likelihood of tendon ‘gapping’ - and subsequently failure - at the repair site.

Paratenonitis describes inflammation of the paratenon and commonly presents as an overuse injury. The paratenon is the connective tissue sheath that surrounds tendons - including tendo Achilles, and serves to minimise friction with the outer layer of the tendon, the epitenon. Whilst this conjunction allows the tendon to glide smoothly on muscular contraction, the presentation of paratenonitis typically follows periods of frequent, repetitive musculoskeletal movements; hence, paratenonitis commonly afflicts the elite and, albeit to a lesser extent, amateur athlete. The extent to which friction at the epitenon-paratenon juncture contributes to this tendinopathy remains unclear, and this study is therefore concerned with the coefficient of friction and the lubrication regime.

By using a specially designed and validated apparatus, the in vivo paratenon-epitenon conjunction was approximated using bovine flexor tendon paratenon and a glass disc; this is being an equivalent experimental set-up to that used in other studies exploring soft tissue contacts. Bovine synovial fluid was used to lubricate the conjunction at 37 deg C, and the frictional characteristics were analysed over a range of sliding speeds and loads.

The coefficient of friction was found to generally lie between 0.1 – 0.01. This range suggests that a system of mixed lubrication applies - where the synovial fluid is causing partial separation of the two surfaces. However, when the data is plotted in the form of a Stribeck curve, the trend suggests that boundary lubrication prevails - where lubrication is determined by surface-bound proteins.

The coefficient of friction at the epitenon-paratenon interface appears to be approximately one order of magnitude greater than that typically reported within the healthy synovial joint. Additionally, the synovial joint is thought to exhibit some fluid film lubrication (i.e. total surface separation), whereas the epitenon-paratenon lubrication regime appears to vary only between the inferior mixed and boundary systems - depending on the specific biomechanical conditions. This data would suggest that the coefficient of friction at the epitenon-paratenon interface is relatively high and thus is potentially significant in the incidence of paratenonitis. Such a hypothesis could be of particular interest to sports-medicine and orthopaedic specialists.

This study aimed to explore the relationship between the geometry of the tuberosity located superior to the Achilles tendon enthesis and the thickness of its fibro-cartilaginous periosteum. The tuberosity acts as a pulley for the tendon during dorsiflexion of the foot and is thus compressed by the overlying tendon. This can result in pressure-related injuries which account for a significant number of Achilles-related problems among sportsmen or women. We postulated that variations in the contact area between the tendon and the tuberosity (and consequently the pressure exerted by the tendon) affects the periosteum thickness. Here, we report four methods of portraying the two dimensional geometry of the superior tuberosity. Material was obtained from 10 elderly dissecting room cadavers donated to the Cardiff University for anatomical examination and prepared for routine histology. Serial sagittal sections were collected at 1 mm intervals, and stained with Masson’s trichrome, toluidine blue and haematoxylin & eosin. In the first method, the area of the bursal cavity was measured between the deep surface of the tendon and the tuberosity within a 9mm radius of the proximal part of the attachment site. The second technique was similar, though used the long axis of the tendon as a reference, rather than its deep surface. The third technique measured the area of the tuberosity within 20 degrees of the tendon long axis. The final technique measured the cumulative gradient of the first 5 mm of the tuberosity, with reference to the tendon long axis. The periosteum thickness was measured at 500 μm intervals from the proximal part of the enthesis and mean values calculated. A good correlation was seen between all techniques, with the tuberosities having the most localised area of contact with the tendon, showing the thickest periosteum.