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Periacetabular osteotomy (PAO) is a surgical procedure to correct acetabular orientation in developmental dysplasia of the hip (DDH). It changes the position of the acetabulum to increase femoral head coverage and distribute the contact pressure over the cartilage surface. The success of PAO depends significantly on the surgeon's experience. Using computed tomography data from patients with DDH, we developed a 3D finite element (FE) model to investigate the optimal position of the acetabulum following PAO. A virtual PAO was performed with the acetabulum rotated in increments from the original center edge (CE) angle. Contact area, contact pressure, and Von Mises stress in the femoral and pelvic cartilage were analyzed. Five dysplastic hips from four patients were modeled. Contact area, contact pressure, and Von Mises stress in the cartilage all varied according to the change of CE angle through virtual PAO. An optimal position could be achieved for the acetabulum that maximizes the contact area while minimizing the contact pressure and von Mises stress in the pelvic and femoral cartilage. The optimal position of the acetabulum was patient dependent and did not always correspond to what would be considered a ''normal'' CE angle. We demonstrated for the first time the interrelation of correction angle, contact area, and contact pressure between the pelvic and femoral cartilage in PAO surgery. Keywords: developmental dysplasia of the hip; periacetabular osteotomy; finite element Developmental dysplasia of the hip (DDH) is an abnormal development of the acetabulum, the femoral head or both. It affects between 1% and 3% of newborn babies and was shown to be the cause of 29% of hip replacements in people under the age of 60. 1 Apart from the pain and discomfort associated with DDH, lack of treatment may lead to osteoarthritis and significant disability. In childhood, early diagnosis and treatment may allow appropriate bony development and avoid complicated and hazardous surgical procedures. However in adults, osteotomy is often the most appropriate treatment. The success largely depends on the surgeon's experience. [2][3][4][5][6][7][8] The diagnosis of DDH is based on the center edge (CE) angle formed by a vertical line passing through the center of the femoral head and a line from the center of the head to the edge of the acetabulum (Fig. 1). The CE angle in a normal hip is >258. A hip with a CE angle <208 may be diagnosed as DDH. 9,10 The periacetabular osteotomy (PAO) to correct DDH depends on the clinical condition of the patient and the severity of the disease. 8 Bernese PAO is a type of pelvic osteotomy described by Ganz et al. 11 that changes the position of the acetabulum to increase coverage of the head, stabilizing the joint and reducing contact pressure. [4][5][6][7][8][9][10]12 The advantages of the Ganz PAO over other pelvic osteotomies are: the cuts are reproducible and can be performed with one incision; post-operatively the posterior column is intact and patients do not need a cast or brace;...

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Current gold standard lower extremity cutaneous wound management is not always effective. Cutaneous wounds generate a "current of injury" which is directly involved in wound healing processes. Application of exogenous electrical stimulation has been hypothesised to imitate the natural electric current that occurs in cutaneous wounds.The aim of this extensive review was to provide a detailed update on the variety of electrical stimulation modalities used in the management of lower extremity wounds.Several different waveforms and delivery methods of electrical stimulation have been used. Pulsed current appears superior to other electrical modalities available. The majority of studies support the beneficial effects of pulsed current over conservative management of lower extremity cutaneous wounds. Although it appears to have no benefit over causal surgical intervention, it is a treatment option which could be utilised in those patients unsuitable for surgery. Other waveforms and modalities appear promising; however, they still lack large trial data to recommend a firm conclusion with regards to their use. Current studies also vary in quantity, quality and protocol across the different modalities. The ideal electrical stimulation device needs to be noninvasive, portable and cost-effective and provides minimal interference with patients' daily life. Further studies are necessary to establish the ideal electrical stimulation modality, parameters, method of delivery and duration of treatment. The development and implementation of newer devices in the management of acute and chronic wounds provides an exciting direction in the field of electrotherapy. K E Y W O R D Selectrotherapy, humans, skin wounds

Optical coherence tomography enabled accurate assessment of healing tissue comparable with histological analysis of biopsy specimens. This noninvasive tool is highly suited to wound assessment and may represent a diagnostic alternative to punch biopsies.

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Biofilms are major contributors to delayed wound healing and there is a need for clinically relevant experimental models to assess theranostics. Microorganisms release volatile organic compounds (VOCs) and the ability to identify these in infected cutaneous wounds could lead to efficient non-invasive diagnosis. The aims here were to develop and assess bacterial biofilm formation and identify their VOC profiles in an in vitro model and validate in human ex vivo incisional and excisional cutaneous wound models. Biofilm development was assessed using multiple microscopy techniques with biofilm-forming deficient controls and quantified using metabolic and biomass assays; and VOC production measured by gas chromatography-mass spectrometry. The production of most VOCs was affected by biofilm development and model used. Some VOCs were specific either for planktonic or biofilm growth. The relative abundance of some VOCs was significantly increased or decreased by biofilm growth phase (P < 0.05). Some Staphylococcus aureus and Pseudomonas aeruginosa VOCs correlated with biofilm metabolic activity and biomass (R ≤ −0.5; ≥0.5). We present for the first time bacterial biofilm formation in human ex vivo cutaneous wound models and their specific VOC profiles. These models provide a vehicle for human skin-relevant biofilm studies and VOC detection has potential clinical translatability in efficient non-invasive diagnosis of wound infection.

Limited utility of in vitro tests and animal models of human repair, create a demand for alternative models of cutaneous healing capable of functional testing. The adult human skin Wound Healing Organ Culture (WHOC) provides a useful model, to study repair and enable evaluation of therapies such as the photodynamic therapy (PDT). Thus, the aim here was to identify the optimal WHOC model and to evaluate the role of PDT in repair. Wound geometry, system of support, and growth media, cellular and matrix biomarkers were investigated in WHOC models. Subsequently, cellular activity, extracellular matrix remodeling, and oxidative stress plus gene and protein levels of makers of wound repair measured the effect of PDT on the optimized WHOC. WHOCs embedded in collagen and supplemented DMEM were better organized showing stratified epidermis and compact dermis with developing neo-epidermis. Post-PDT, the advancing reepithelialization tongue was 3.5 folds longer, and was highly proliferative with CK-14 plus p16 increased (p < 0.05) compared to controls. The neo-epidermis was fully differentiated forming neo-collagen. Proliferating nuclear antigen, p16, COLI, COLIII, MMP3, MMP19, and a-SMA were significantly more expressed (p < 0.05) in dermis surrounding the healing wound. In conclusion, an optimal model of WHOC treated with PDT shows increased reepithelialization and extracellular matrix reconstruction and remodeling, supporting evidence toward development of an optimal ex vivo wound healing model.An ideal wound healing model of adult human skin should not only resemble a wound made and evaluated within a system that resembles and incorporates all adult human skin components, processes, and functions but also allow for functional testing of therapies ex vivo and enable evaluation of the effect of these processes in cutaneous repair.