A new medical device to measure a stiffness of soft materials.

An objective in vivo measurement technique for assessing the material properties of soft tissue would be a valuabe tool in diagnosing dermatological pathologies. In order to make advancements in this field, a new hand-held device was designed to measure the stiffness of soft materials. The device measures the reaction forces experienced by the soft tissue under constant indentation deformations at the time of stiffness measurement. Agarose gel samples were prepared in a range of molarities to mimic the stiffness variabilities found in vivo. The stiffness of each gel was evaluated using two different measurement techniques. The first method utilized an industry standard durometer, designed to measure the hardness of materials in shore type 00 scales of soft plastics. The second measurement was taken using an original custom-built soft tissue stiffness meter, designed specifically for the present study. These two devices were compared and a strong correlation was found between them (r²=1.00, Spearman rank test). Additionally, it was observed that gels of different stiffness could be distinguished by both devices. In conclusion, the soft tissue stiffness can be accurately evaluated using the proposed device. The new device should be evaluated on human subjects in future studies, before it can be used to assess soft tissue disorders.

Comparison of screw-fixation stabilities of first metatarsal shaft osteotomies: a biomechanical study.

OBJECTIVES: Although metatarsal shaft osteotomies have become popular in the surgical treatment of moderate or advanced hallux valgus owing to better reduction and stability, they present fixation problems as the angular correction increases. The purpose of this biomechanical study was to evaluate the effects of widely used metatarsal shaft osteotomies and a newly defined osteotomy modification on the stability of screw fixation at greater angular corrections. METHODS: Upon evaluation of known problems of shaft osteotomies, a new osteotomy type was designed that might provide an adequate contact area while allowing a greater angular correction, increased stability, and safer osteosynthesis. In our new modification of the Mau osteotomy, the proximal plantar notch that was defined for the Sammarco's modification to increase the contact area was created more proximally making an angle of about 50 degrees with the osteotomy, and the osteotomy was extended until 5 mm to the distal joint surface, aiming to increase the contact area and intrinsic stability. For biomechanical analysis, 30 standard metatarsal bone models (Sawbones) were divided into five groups equal in number for the following osteotomy methods: Myerson's modification of the Ludloff osteotomy, Mau osteotomy, scarf osteotomy, offset V osteotomy, and the new modification of the Mau osteotomy. Osteotomies were performed with a standard correction of 10 degrees in the intermetatarsal angle, followed by appropriate osteosynthesis with fixation by two Acutrak compression screws. The relationship between osteotomies and osteosynthesis in terms of stability was assessed by the three-point bending test. RESULTS: The mean stiffness of the Ludloff osteotomy was significantly lower than all the other osteotomy groups (p<0.05). Stiffness of the Mau group was significantly greater than three groups (p<0.05), but the difference from the offset V group did not reach significance. Stiffness of the new Mau modification was significantly greater than the scarf group (p=0.016), but did not differ significantly from the offset V group. Osteotomy groups with and without notching had similar stiffness values (p=0.582), whereas single notching was associated with a significantly greater stiffness compared to double notching (p=0.031). CONCLUSION: Our findings suggest that the new modification to the proximal shaft osteotomies moves the center of rotation of angulation more proximally and provides sufficient stability of screw fixation.

A biomechanical study on preloaded compression eVect on headless screws.

INTRODUCTION: Commonly used headless design screws such as Acutrak and Herbert screws have limited compressive effect on short fragment fixation. Therefore, we investigated whether preloaded compression techniques could be helpful in improving the compression effect. METHOD: A prototype of interfragmentary compression screw was designed with a constant pitch to avoid self-compressive effect. Preloaded compression was achieved with a sleeve device before the insertion of the trailer side (the leading side was inserted). Prototype screw test results were compared with those of Acutrak and Herbert screws. Eight pullout and eight compression tests were performed for each of the three screws using homogenous synthetic bone blocks. RESULTS: The mean pullout forces of the Acutrak, Herbert and prototype screws were 67.21, 45.90 and 61.88 N, respectively. Preloaded compression (18.15 N) was higher than the compression produced by Acutrak (15.27 N) and Herbert (15.11 N) screws (p < 0.05). However, at the end of full insertion, half of the power obtained by preloaded compression was lost. CONCLUSION: Preloaded compression technique was successful in attaining maximum compression rate. During trailing-side insertion, constant pitch design failed to keep compression rate. Variable pitches can be useful to preserve or increase compression rate. In addition, sleeve usage may be more advantageous in thin fragment fixation.

Anatomical and biomechanical evaluation of the tension band technique in patellar fractures.

Tension band wiring for patellar fractures is common, but some recent reports refer to disadvantages of this approach. Our anatomical and biomechanical study focused on use of tension band techniques in patellar fractures. The anatomy of the patella and tendon insertion was examined with knee magnetic resonance imaging (MRI) and correlated with the technical requirements of the tension band. Tension band wiring over tendinous tissue was simulated and calculated with a cyclic biomechanical test on cow patellae. According to tension band templating on the MRI section, Kirschner wire insertion was needed for the tension band to turn over the tendinous tissue. The tension band became more stable while turning over less tendinous tissue and more adjacent bone surface. Nevertheless, cyclic loading tests indicate that all tension band applications in this study lose their initial stability. Excessive initial compression by the tension band resulted in bending of the Kirschner wire and thus reduction failure. For optimum stabilisation, tension force transfer should be done directly on bone or at least material that protects the tendon would be useful.

The stiffness characteristics of hybrid Ilizarov fixators.

The use of hybrid Ilizarov models around femoral area is gaining clinical popularity lately. Hybrid systems show different mechanical properties. The purpose of this report is to examine the stiffness characteristics of the C-arch and half-pins on the hybrid Ilizarov fixators. Eight models that included standard Ilizarov and hybrid models were applied to six femoral sawbones. The distal part of fixation was composed of a two-ring frame applied identically to all bones. The difference of the configuration was at the proximal part, where half-pins with or without C-arches were either added to the proximal two-ring frame or replaced the proximal one- or two-ring frame. Osteotomy was performed in the femoral diaphysis and the bone was distracted 2cm. The stability of the system was tested with the axial compression testing machine. Displacements between the adjacent fracture sides were measured with the video extensometer in three dimensions. We found that proximal half-pin applications alone had less stiffness, but half-pins with C-arch had more stiffness than the model including only half-pins. Additional half-pins onto one- or two-ring frames had more longitudinal stiffness, but this system showed weak resistance against transverse displacement.

[Extremity saving surgery and reconstruction for tumors of the scapula]. / Skapula tümörlerinde ekstremite koruyucu cerrahi ve rekonstrüksiyon.

OBJECTIVES: The aim of this study was to evaluate the results of extremity saving surgery and reconstruction with a scapular prosthesis in patients with scapula tumors. METHODS: Seven patients (1 woman, 6 men; mean age 53 years; range 39 to 75 years) underwent partial or total scapulectomy followed by reconstruction with fibular autograft (n=1) or a scapular prosthesis (n=6) for bone or soft tissue scapular tumors. Latissimus dorsi muscle flap was used for the reconstruction of soft tissues. Postoperative adjuvant chemotherapy and/or radiotherapy were used depending on the primary pathology. Functional evaluations were made using the scores of the Musculoskeletal Tumor Society (MSTS). The mean follow-up period was 35 months (range 18 to 53 months). RESULTS: No major surgical complications occurred in the early postoperative period. Two patients died due to distant metastasis. One patient was lost to follow-up in the second year. The first patient of the series in whom an unconstrained prosthesis was used had severe instability. Overall, despite some limitation in the movements of the shoulder (active shoulder abduction: 20 degrees -90 degrees ), elbow and hand functions were near-normal. The mean MSTS functional score was 22 (range 18 to 25); four patients had good or very good results. The results were more satisfactory (abduction: 45 degrees -90 degrees , mean MSTS score 24) in patients with well-controlled primary disease and in whom a constrained prosthesis was used. CONCLUSION: Stability and function can be increased with limb salvage surgery, reconstruction of the scapular triangle with a prosthesis, and re-attachment of preserved muscles to the new scapular body.

[Biomechanical analysis of load transmission characteristics of limited carpal fusions used to treat Kienböck's disease]. / Kienböck hastaligi tedavisinde sinirli karpal füzyonlarin yük aktarma özelliklerinin biyomekanik analizi.

OBJECTIVES: Although limited carpal fusions used in the treatment of Kienböck's disease are thought to act by decreasing the loads on the lunate, biomechanical studies show that capitohamate fusion acts oppositely to what is expected. This experimental study was designed to resolve this paradox. METHODS: In a biomechanical cadaveric study, load transmissions at the radioulnacarpal joint were investigated under 140 and 210 newtons of load with three wrist postures, namely, neutral, ulnar and radial deviations, in five intact wrists and after scaphotrapeziotrapezoid, capitohamate, and scaphocapitate fusions. RESULTS: Under 140 newtons of load, the loads imposed to the lunate decreased following scaphotrapeziotrapezoid and scaphocapitate fusions, but increased after capitohamate fusion. However, when the load was increased to 210 newtons, there were no differences between intact wrists and limited carpal fusions in respect to the loads exerted on the lunate. In all the situations, the lunate was subjected to a significantly greater load in ulnar deviation. CONCLUSION: These results suggest that limited carpal fusions do not alter load transmission characteristics of the wrist joint under 210 newtons of load. The etiology of the Kienböck's disease seems to be related to an overload in ulnar deviation and the beneficial effect of limited carpal fusions seems to be associated with restricted ulnar deviation of the wrist rather than load transmission characteristics.

Extraarticular pigmented villonodular synovitis of the hip.

Pigmented villonodular synovitis of any joint in the extraarticular region is very rare. Its clinical and radiological differential diagnosis is difficult due to exhibiting findings of any soft tissue tumor. Here we report an extrarticular pigmented villonodular synovitis case of the hip of a five-year-old boy, with its radiological and histopathological aspects. The mass was completely extraarticular and was identified histologically and radiologically as pigmented villonodular synovitis. Six months after marginal excision, the lesion recurred. The physicians can face such cases of pigmented villonodular synovitis presenting with unusual extraarticular location, and the preferred excision should be wide to avoid possible recurrences.

Calcium pyrophosphate dihydrate crystal deposition disease mimicking malignant soft tissue tumor.

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease has multiple clinical features with variable courses creating several pitfalls in clinical diagnosis. There are number of reported cases mimicking malignant skeletal tumors such as chondrosarcoma. However, no case of CPPD disease with radiographic noncalcified soft tissue mass has been reported in the literature. Here we report a case of CPPD disease clinically mimicking soft tissue tumor with its magnetic resonance imaging appearance and histopathology.

Bone mineral density reference values in the normal female and male population of Izmir, Turkey.

In this study we aimed to establish the dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) reference values of healthy Turkish women and men residing in Izmir, western Turkey. We examined 347 women and 119 men (age range 20-80 years) who did not have any known risk factor that might affect bone mass. The BMD measurements were performed by Hologic QDR 4500 W Elite DXA instrument from the lumbar spine (L1-L4) and non-dominant hip. In women the mean BMD (g/cm(2))+/-standard deviation (SD) of the normal reference group between 20 and 39 years of age was 0.963+/-0.121 g/cm(2) in the lumbar spine and 0.891+/-0.119 g/cm(2) in total femoral region. The percentages of annual and total BMD losses in women between 30 and 80 years of age were 0.74 and 29% at spinal level and 0.65 and 26% in femoral region, respectively. The average BMD of the normal men's group between 20 and 39 years of age was 0.996+/-0.111 g/cm(2) in the lumbar spine and 1.025+/-0.110 g/cm(2) in femoral region. The percentages of annual and total BMD losses were 0.33 and 13% at spinal level and 0.50 and 20% in femoral region, respectively. In conclusion, like the values reported from mid-Anatolian region of Turkey, the BMD values of Turkish women and men residing in Izmir, western Anatolia, are also lower than in most European countries with regard to US and preinstalled Hologic values.

Open fractures of the proximal humerus treated with the Ilizarov method: 12 patients followed 3-8 years.

We followed 12 patients who had been treated with the Ilizarov method for open proximal humeral fractures for more than 3 years. No wound infection occurred. Avascular necrosis and nonunion were each detected in 1 patient. According to Neer's criteria, the outcome was excellent or satisfactory in 8 patients.

[Treatment of femoral fractures associated with fibrous dysplasia: a case report]. / Fibröz displazide femur kiriklarinin tedavisi: Olgu sunumu.

Fibrous dysplasia is a rare condition in which bone tissue is replaced by fibro-osseous lesions. A sixteen-year-old male patient with fibrous dysplasia underwent plate fixation for subtrochanteric fracture of the proximal femur. Eighteen months postoperatively, progressive femoral deformity and refracture occurred. Upon failure in three-month conservative treatment, the plate was removed and intramedullary fixation was performed. Control radiographs at the end of 18 months after intramedullary fixation showed complete fracture healing. This case emphasizes that intramedullary fixation should be the first choice to treat femoral fractures and to prevent refractures in patients with fibrous dysplasia.