Emeka Oragui

The Role of Bioreactors in Tissue Engineering for Musculoskeletal Applications

Tissue engineering involves using the principles of biology, chemistry and engineering to design a ‘neotissue’ that augments a malfunctioning in vivo tissue. The main requirements for functional engineered tissue include reparative cellular components that proliferate on a biocompatible scaffold grown within a bioreactor that provides specific biochemical and physical signals to regulate cell differentiation and tissue assembly. We discuss the role of bioreactors in tissue engineering and evaluate the principles of bioreactor design. We evaluate the methods of cell stimulation and review the bioreactors in common use today.

Tourniquet use in upper limb surgery

Tourniquets are compressive devices that occlude venous and arterial blood flow to limbs and are commonly used in upper limb surgery. With the potential risk of complications, there is some debate as to whether tourniquets should continue to be routinely used. In this review, we first look at the different designs, principles, and practical considerations associated with the use of tourniquets in the upper limb. The modern pneumatic tourniquet has many design features that enhance its safety profile. Current literature suggests that the risk of tourniquet-related complications can be significantly reduced by selecting cuff inflation pressures based on the limb occlusion pressure, and by a better understanding of the actual level of pressure within the soft tissue, and the effects of cuff width and contour. The evidence behind tourniquet time, placement, and limb exsanguination is also discussed as well as special considerations in patients with diabetes mellitus, hypertension, vascular calcification, sickle cell disease and obesity. We also provide an evidence-based review of the variety of local and systemic complications that may arise from the use of upper limb tourniquets including pain, leakage, and nerve, muscle, and skin injuries. The evidence in the literature suggests that upper limb tourniquets are beneficial in promoting optimum surgical conditions and modern tourniquet use is associated with a low rate of adverse events. With the improvement in knowledge and technology, the incidence of adverse events should continue to decrease. We recommend the use of tourniquets in upper limb surgery where no contraindications exist.

The importance of correct patient positioning in theatres and implications of mal-positioning.

Patient positioning in theatre pertains to how a patient is transferred and positioned for a specific procedure. Patient safety is a central focus of care within the NHS and every healthcare practitioner must ensure that patients are protected from harm where possible. Mal-positioning of the patient has important implications in terms of associated problems of pressure sores, nerve compressions, deep vein thrombosis and compartment syndrome, and should be avoided.

Advances in meniscal tissue engineering.

Injuries and lesions to the meniscal cartilage of the knee joint are common. As a result of its limited regenerative capacity, early degenerative changes to the articular surface frequently occur, resulting in pain and poor function. Currently available surgical interventions include repair of tears, and partial and total meniscectomy but the results are inconsistent and often poor. Interest in the field of meniscal tissue engineering with the possibilities of better treatment outcomes has grown in recent times. Current research has focused on the use of mesenchymal stem cells, fibrochondrocytes, meniscal derived cells and fibroblast-like synoviocytes in tissue engineering. Mesenchymal stem cells are multipotent cells that have been identified in a number of tissues including bone marrow and synovium. Current research is aimed at defining the correct combination of cytokines and growth factors necessary to induce specific tissue formation and includes transforming growth factor-β (TGF-β), Platelet Derived Growth Factor (PDGF) and Fibroblast Growth Factor 2 (FGF2). Scaffolds provide mechanical stability and integrity, and supply a template for three-dimensional organization of the developing tissue. A number of experimental and animal models have been used to investigate the ideal scaffolds for meniscal tissue engineering. The ideal scaffold for meniscal tissue engineering has not been identified but biodegradable scaffolds have shown the most promising results. In addition to poly-glycolic acid (PGA) and poly-lactic acid (PLLA) scaffolds, new synthetic hydrogels and collagen sponges are also being explored. There are two synthetic meniscal implants currently in clinical use and there are a number of clinical trials in the literature with good short- and medium-term results. Both products are indicated for segmental tissue loss and not for complete meniscal replacement. The long-term results of these implants are unknown and we wait to see whether they will be proved to have benefits in delaying arthritic change and chondral damage.

An Unusual Case of Fibular (Postaxial) Polydactyly: Extrametatarsal Head with Fused Duplication of the Proximal Phalanx

Polydactyly of the foot is a congenital anomaly characterized by the appearance of all or part of 1 or more additional rays. A number of morphologically and anatomically based classifications exist. We present an unusual case of fibular (postaxial) polydactyly characterized by an extrametatarsal head with fused duplication of the proximal phalanx. We describe the method of surgical correction and emphasize the need for careful preoperative planning to achieve a good functional and cosmetic outcome.

Evidence-based practice in arthroscopic knee surgery.

Knee arthroscopy is a minimally-invasive technique that allows intra-articular assessment and treatment of knee joint pathology. It has proven benefits of reduced patient morbidity, earlier recovery and mobilisation, and it is cost-effective. In this paper we review the anatomy of the knee joint, indications and contra-indications to knee arthroscopic use, and consider the main techniques of knee arthroscopy including types of anaesthetic, prophylactic antibiotics, theatre setup and arthroscopic portals, and post-operative care.

Common fractures and injuries of the ankle and foot: functional anatomy, imaging, classification and management.

The ankle and foot are functionally important and complex joints. Bony fractures and ligamentous injuries are common. In this review paper we will discuss the functional anatomy, imaging, classification and the management of common ankle and foot injuries including ankle fractures, Achilles tendon ruptures, Lisfranc joint injuries, calcaneo fractures and fractures of the metatarsals and phalanges.

A new technique of endoprosthetic replacement for osteosarcoma of proximal femur with intra-articular extension

INTRODUCTION Osteosarcoma is the most common primary malignant tumour of bone and commonly involved sites are the distal femur, proximal tibia, and humerus. Osteosarcoma of proximal femur usually arises at the metaphysis and articular cartilage acts as a relative barrier to tumour spread, with extension into the hip joint being extremely rare. PRESENTATION OF CASE A previously fit and well sixteen-year-old male presented with a 2month history of right hip pain and a limp. Plain radiographs and magnetic resonance imaging (MRI) showed an expansile lesion in the right femoral neck, extending 16cm distally from the proximal femoral articular surface through the intertrochanteric region into the upper right femoral shaft. There was also clear evidence of intra-articular extension into the acetabulum. DISCUSSION Endoprosthetic replacement following resection is a good treatment option for proximal femoral tumours due to the low complication rate and achievement of good postoperative function. However, treatment of a proximal femoral lesion with intra-articular involvement by prosthetic reconstruction is challenging. We report a patient who presented with osteosarcoma of the proximal femur extending into the hip joint and describe the technique of en-bloc extra-articular resection of the acetabulum and proximal femur with reconstruction using a custom made prosthesis. CONCLUSION We conclude that extra-articular resection and endoprosthetic reconstruction using a coned hemi-pelvic implant with fluted stem and a modular femoral implant is a useful treatment option in the management of a proximal femoral lesion involving the hip-joint. It allows adequate tumour clearance and stable reconstruction for rapid post-operative recovery with early mobilisation.

An unusual presentation of phaeochromocytoma (case presentation).

The Discussion and Diagnosis can be found on page 1510. CASE A previously well 11-year-old boy of Somali origin presented to the Emergency Department with a 1-day history of fever and left loin pain and no relevant past medical or family history. Physical examination revealed mild tenderness in the left upper quadrant, and his blood pressure was 136 ⁄ 74 mmHg. Otherwise, physical examination was unremarkable. Urinalysis was performed and was strongly positive for leucocytes and erythrocytes. Laboratory investigations revealed an elevated C-reactive protein of 173 mg ⁄ L. A plain abdominal radiograph and ultrasound scan of the urinary tract did not reveal any abnormality. A diagnosis of acute pyelonephritis was made and antibiotic therapy commenced by way of intravenous ceftriaxone. His fever persisted and a repeat ultrasound was performed. This time, a left paraspinal mass, distinct from the left kidney, was identified. A computed tomography (CT) scan was performed owing to diagnostic uncertainty and confirmed the presence of a soft tissue mass anterior to the left kidney (Figure 1). The differential diagnosis included an infected mesenteric cyst, an infected pancreatic cyst or an adrenal mass.

An unusual presentation of phaeochromocytoma (Discussion and Diagnosis)

The Case Presentation can be found on page 1404. DISCUSSION An exploratory laparotomy was performed, and a left irregular suprarenal mass was identified and resected (Fig. 2). During intraoperative handling of the mass, the patient became hypertensive and required labetalol. Subsequently, he became hypotensive on removal of the mass that responded to fluid resuscitation. Post-operative recovery was uneventful. Antibiotics were discontinued on day 4, and the patient was discharged home on day 6. Histological examination of the lesion confirmed a pheochromocytoma. Subsequent follow-up with 123-I-metaiodobenzylguanidine (MIBG) scintigraphy did not show any abnormal uptake of the radiolabelled isotope, and CT thorax confirmed the absence of metastatic disease. A pheochromocytoma is a neuroendocrine tumour of the sympathetic nervous system. Ten percentage are malignant, and 10% occur outside the adrenal gland. The incidence of pheochromocytoma in children is 1 in 500 000 persons (1). The signs and symptoms of a pheochromocytoma are those of sympathetic nervous system hyperactivity. In adults, the classic triad of headaches, sweating and palpitations is usually accompanied by hypertension (2). The most frequent presentation in children is sustained hypertension with visual disturbances (3). In comparison with adults, pheochromocytomas in children have a higher incidence of bilaterality, familial association and extra-adrenal location (4,5). The fact that extra-adrenal tumours are more common in children may reflect a higher incidence of familial disease. It may also be due to failure of atrophy of the sympathetic paraganglia in the organ of Zuckerkandl, which is usually the major source of catecholamines in the foetus and up to 3 years of age (6). The biochemical diagnosis of pheochromocytoma depends on demonstrating high levels of catecholamines or their metabolites in the blood or urine. A 24-h urine collection for metanephrines (a metabolite of epinephrine) is a useful screening test, with a sensitivity and specificity of 98%. Normal levels on three separate occasions virtually exclude the disease (1). The measurement of vanillylmandelic acid (an end-stage metabolite of epinephrine and norepinephrine) in a 24-h urine collection is less reliable and may miss a pheochromocytoma in up to 35% of cases (4). Raised levels of plasma free metanephrines are considered to be the test of first choice and confirm the diagnosis (7). Patients with fever and pheochromocytoma are significantly more likely to have a comorbid event, larger tumour, necrosis within the tumour, higher urinary metanephrine levels, longer duration of hospitalization and be non-white (2). The tumour is then localized by CT ⁄ MRI and scintigraphy using mIBG which is selectively taken up by adrenergic cells. The treatment of choice for all pheochromocytomas where possible is surgical excision under cover of alpha and beta adrenoceptor blockade to avoid the effects of excessive catecholamine release into the circulation (8). To our knowledge, there are no reports in the literature of children with pheochromocytoma presenting with pyrexia of unknown origin and haemodynamic stability. The left upper quadrant pain our patient presented with can be attributed to the mass-related effect of the tumour in the left Acta Pædiatrica ISSN 0803–5253