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Biomedical subjects

E Panagiotopoulos

Publications and source records attributed to E Panagiotopoulos.

25 records · Page 2Linked to original sources
PubMed1994

Pattern of screw loosening in fractures fixed with conventional and functional plates.

Plate fixation depends mainly on the holding power of the screws. In the present study the pattern of screw loosening was investigated. Thirty-two adult female sheep divided into four groups were used. A mid-diaphyseal transverse osteotomy was made on the right radius of each animal, and then plated on the anterior (tension) surface. Half of each group were plated using a standard narrow 7-hole AO Dynamic Compression Plate (DCP), whereas in the remaining animals a 6-hole newly designed sliding plate (SP) was applied. The required torque of tightening intraoperatively, as well as for releasing the screws after killing the animals was recorded with a tension-calibrated screwdriver. The pattern of loosening was similar for all the screws and the three phases could be recognized. An initial loosening was observed 1 month after the operation. A slow recovery of the torque was measured from the second month onwards, becoming highest by the fourth month after the operation, whereas a slow decrease in torque was observed from the fourth to the sixth month. In the SP group, the overall loosening was much lower than the DCP group (P < 0.05), whereas there was no difference in the loosening between the proximally placed screws and the distally placed ones (P > 0.05) for both plates.

Animals↗
PubMed1993

Non-tropical pyomyositis in adults: report of four cases and literature review.

Four cases of non-tropical pyomyositis in adults are presented and 72 cases reported in the literature are reviewed. The diagnosis is often overlooked or delayed because most physicians are not familiar with the entity. Local signs of inflammation fever, leukocytosis and an elevated erythrocyte sedimentation rate are common features. Staphylococcus aureus is the most common pathogen and the thigh muscles are the most common site involved. Computerized tomography is used to establish the diagnosis and surgical incision and drainage in combination with antibiotic therapy is successful in the majority of the cases.

Adult↗
PubMed1993

Recurrence of pigmented villonodular synovitis of the knee 17 years after the initial treatment. A case report.

Pigmented villonodular synovitis (PVNS) is a benign proliferative process involving the synovial membranes bursas or tendon sheaths. The rarity of the process, the absence of well-documented long follow-up examinations, as well as reports on different forms of the disease from multiple anatomic sites has lead to some confusion. This is a case report of a 44-year-old woman with recurrence of PVNS of her right knee, 17 years after the initial limited knee synovectomy. It was proven impossible to differentiate the disease from soft-tissue malignancy despite the use of all the available investigation methods, including nuclear magnetic resonance. Eventually the diagnosis was made by an open biopsy. Marginal excision of the soft-tissue mass from the popliteal fossa was performed initially, followed by a total knee synovectomy within the next two weeks. The patient remains recurrence free 32 months after the operation.

Adult↗
PubMedDate not supplied

Viscoelastic properties of cartilage-subchondral bone complex in osteoarthritis.

OBJECTIVE: This study examines viscoelastic properties of the 'unaffected' tibial condyle in unicompartmental osteoarthritic knees, in order to determine whether to preserve it or not in knee replacement operations. DESIGN: The viscoelastic properties of longitudinal strips of cartilage and subchondral bone from osteoarthritic and healthy knees were studied. METHODS: Nine medial compartment osteoarthritic and nine cadaveric knees, all age- and gender-matched, were studied. Samples from polyethylene and methacrylate cement were also obtained and all then tested in the DMA (Dynamic Mechanical Analysis) testing apparatus. The dynamic modulus of elasticity (E(dyn)) and the loss factor (tan delta) were measured. RESULTS: The medial compartment in osteoarthritic knees had lost its viscoelastic properties, having a significantly higher E(dyn) compared to the lateral one, and lower values of loss factor. In healthy knees there was no significant difference (p=0.18) in viscoelastic properties between both compartments and with the unaffected side of the osteoarthritic knee. Polyethylene and cement appear to have a high modulus of elasticity compared to both the healthy and the osteoarthritic knees. CONCLUSIONS: The 'unaffected' (lateral) tibial condyles in medial compartment osteoarthritic knees seem to preserve their viscoelastic properties; it is worth considering a hemiarthroplasty. The significant modulus of elasticity difference between the condyles-polyethylene-cement results in different deformation in the interface between them and induces micromotion and loosening.

Bone Cements↗
PubMedDate not supplied

Comparative study of callus performance achieved by rigid and sliding plate osteosynthesis based upon dynamic mechanical analysis.

Operative management of long bone fractures is considered to be the treatment of choice all over the world. This could be achieved either by intramedullary nailing or plating. The former allows delivery of stresses into the fracture site, but it requires a well-equipped operating theatre and an experienced surgeon who is, unfortunately, continuously exposed to radiation. On the other hand, plates could easily be applied in every orthopaedic clinic, but the existing ones are rigid and protect the fracture site from stresses to which it is ordinarily exposed. Recently, various experimental attempts have been made to provide plates which allow partial loading on the fracture site and enhance callus formation (secondary fracture healing). Bearing that in mind, a two-part sliding plate (SP) has been developed at the Orthopaedic Clinic of Patras University, which allows intermittent loading into the fracture site. Both the conventional AO rigid plate and SP were applied to osteotomized sheep radii. The dynamic properties of the callus were estimated with its two dynamic mechanical characteristics (dynamic modulus of elasticity and the relative loss factor), whereas its static properties (strength) were evaluated by measuring the ultimate bending strength. A superiority of callus produced by the sliding plate was observed concerning all the parameters under consideration.

Animals↗