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At least 1,351 records · Page 75Linked to original sources
PubMed2003

Mechanical properties of various z-stent designs: an endovascular stent-grafting perspective.

PURPOSE: To comparatively assess the mechani-cal behavior of various clinically relevant Z-stent designs. METHODS: A total of 16 Z-stents of original, biliary, spiral, and double-skirted designs (n=4 for each) were constructed using similar specifications for all. Stents were then evaluated for stiffness, snap opening force (SOF), flexibility, and displacement force using a novel tensiometer. Differences among the stents were determined using statistical methods. Stents explanted from dog aorta after a mean follow-up of 13 months were examined under a scanning electron microscope for surface defects. RESULTS: Forces required for about 50% reduction in diameter were 1.88 +/- 0.16 N, 3.81 +/- 0.21 N, 2.76 +/- 0.22 N, and 3.35 +/- 0.19 N for original, biliary, spiral, and skirted designs, respectively. Differences among the four designs were statistically significant at almost all points of measurement (P < 0.0001). Biliary and skirted designs showed higher SOF values in the early measurements. Stents explanted from dog aorta after a mean duration of 13 months showed no obvious corrosion or breakage in the wire struts. CONCLUSIONS: Significant differences exist among the various Z-stent designs in terms of their mechanical properties. Understanding them should help to select the appropriate stent for a given lesion. 316L stainless steel shows a favorable long-term tissue interaction.

Angioplasty↗
PubMed2001

Clinical assessment of the osteoarthritis patient.

It is becoming apparent that the disease process of osteoarthritis should be regarded separately from the clinical syndrome of joint pain, use-related stiffness and disability. The latter may best be approached as a chronic regional pain disorder that requires attention to physical, psychological and social factors as well as those related to the disease process. This chapter sets out to look at some of the practical implications of taking this view for the clinical assessment. Starting with the syndrome of hip, knee or hand pain in older adults in the community, we consider what leads people to consult, what the important features to assess might be, the role of imaging in the clinical assessment of osteoarthritis, and finally how a management plan could be formulated. The usefulness of assessing clinical osteoarthritis as a regional pain disorder is uncertain. Even if this were demonstrated, the concept of osteoarthritis as a structural disease should be retained as an integral part.

Adult↗
PubMed2002

Results of a European multicentre iliac stent trial with a flexible balloon expandable stent.

PURPOSE: to determine the 12 months success rate with a balloon expandable, flexible stainless steel stent in iliac artery obstructions. MATERIALS AND METHODS: one-hundred and twenty-six consecutive patients with iliac obstructive disease and who demonstrated an unsatisfactory angioplasty result with a post-dilatation gradient of at least 10 mmHg, or a primary occluded lesion were included in the study. Follow-up was by Doppler sonography, ankle pressures with and without exercise and clinical parameters. RESULTS: after stent placement, the mean percentage diameter stenosis decreased from 79 to 4%, with a mean intra-arterial pressure gradient of 3 mmHg. Primary stent patency was 94% at 6 months and 89% at 12 months. Primary clinical result at 6 months was 88% and at 12 months 81%. Primary assisted clinical result (after re-pta) at 6 and 12 months was 89 and 86%, respectively. The Ankle Brachial Index (ABI) after exercise at 1 month follow-up was reduced from 0.88 to 0.75, with minor deterioration at 6 months to 0.72, and at 12 months to 0.68. The 1, 6, and 12 months follow-up Piek Systolic Velocity (PSV) ratios across the stented lesions remained stable at a mean of 1.4, 1.6, and 1.6, respectively. However, respectively 44, 39 and 34% of the patients still experienced symptoms of claudication. CONCLUSIONS: the results presented here support the suggestion stenting to be an effective device in the treatment of iliac artery obstructive disease. This study also, confirms other study results concerning haemodynamic patency after iliac stenting on the indication of a 10 mmHg pressure gradient after pta and the discrepancy between good haemodynamic patency and clinical result.

Adult↗
PubMedDate not supplied

Endoscopic gastrocnemius recession: preliminary report on 18 cases.

A technique of endoscopic gastrocnemius recession was evaluated. Fifteen patients undergoing 18 procedures were prospectively studied with a minimum follow-up of 1 year. There were 9 women and 6 men (mean age, 44.1 +/- 22.6 years). One patient had an isolated recession; the others had various adjunctive flatfoot or reconstructive procedures. Pre- and postoperative ankle dorsiflexion was evaluated, as was the amount of time before patients could perform a single-leg heel raise postoperatively. The mean preoperative ankle dorsiflexion with the knee extended was -8.7 degrees +/- 3.5 degrees , which improved from a mean 14.9 degrees at 3 months postoperatively to a mean 6.2 degrees +/- 2.6 degrees . At 12 months postoperatively, this value was 3.6 degrees +/- 1.8 degrees , a net postoperative improvement of 12.6 degrees (P < .00001). Patients were able to perform a single-leg heel raise on an average of 13.0 +/- 6.0 weeks. Complications were mostly related to lateral foot dysesthesia in the distribution of the sural nerve (N = 3). Furrowing of the medial leg was noted in 1 patient. No hematomas or neuromas associated with the portal sites were found. These results show endoscopic gastrocnemius recession to be an acceptable method of lengthening the gastrocnemius complex.

Adolescent↗
PubMedDate not supplied

The modified Hohmann osteotomy: an alternative joint salvage procedure for hallux rigidus.

The purpose of this study was to evaluate the effectiveness of the modified Hohmann osteotomy for treatment of hallux rigidus. By allowing plantarflexion of the first metatarsal head, this osteotomy was theorized to protect gliding motion and to decompress the joint. Twenty-two patients (25 procedures) were assessed preoperatively and postoperatively for the first metatarsal plantarflexory osteotomy. The average postoperative follow-up was 12 months, with a range of 6 to 60 months. Postoperative subjective patient questionnaires showed the following: 96% reported excellent subjective ratings with no fair or poor ratings, 80% reported a return to normal activity within 1 to 2 months, no patients reported any significant limitations in their activity or reoccurrence of pain, and no patients reported any need for a revision surgery other than hardware removal. A goniometer was used to measure preoperative and postoperative dorsiflexion and plantarflexion at the first metatarsophalangeal joint. The patient first metatarsophalangeal joint dorsiflexion increased from a mean 17.76 degrees preoperatively to a mean 58.92 degrees postoperatively. The ability to hold a piece of paper under the hallux for purchase power was also evaluated. Only 2 of 25 procedures lacked the purchase power to effectively hold a piece of paper with the hallux. Thus, the modified Hohmann osteotomy provides an excellent alternative joint-salvaging procedure for moderate to severe hallux rigidus.

Adult↗
PubMedDate not supplied

Radiographic investigation of angular and linear measurements including first metatarsophalangeal joint dorsiflexion and rearfoot to forefoot axis angle.

This study investigated intra- and inter-rater reliability of several radiographic angular and linear parameters using 6 subjects. Using standard weight-bearing radiographs, the following measurements were performed: first metatarsal protrusion distance, hallux abductus, first intermetatarsal, calcaneal inclination and lateral intermetatarsal angles. Measurement of lateral stressed dorsiflexion of the first metatarsophalangeal joint and the rearfoot-to-forefoot-axis angle taken using a composite view were also obtained. All parameters were measured independently by 2 raters, and measurements were repeated on 3 separate occasions at weekly intervals. Intrarater reliability of radiographic measurements ranged between R = 0.65-1.00 for lateral stressed dorsiflexion, and between R = 0.91 and 0.99 for the rearfoot to forefoot axis angle. Inter-rater reliability of radiographic measurements ranged from R = 0.82-0.99. Specifically, lateral stressed dorsiflexion showed R = 0.87 with a mean difference of -1.47 (confidence interval [CI]: -3.42, 0.47), indicating no significant difference ( t = 1.54, P = 0.13). The rearfoot-to-forefoot-axis angle showed R = 0.92 with a mean difference of -0.15 (CI: -1.05, 0.74), indicating no significant difference ( t = 0.35, P = 0.73). The 7 angular and linear measurements chosen demonstrated high inter- and intrarater reliability. These results indicate that weight-bearing radiographic first metatarsophalangeal joint dorsiflexion using the lateral stressed dorsiflexion view, and measurement of the rearfoot-to-forefoot-axis angle using a composite view could be measured reliably within and between raters.

Adult↗
PubMed2003

A biologic model for assessment of osseous strain patterns and plating systems in the human maxilla.

PURPOSE: This study was conducted to examine a biomechanical model and to help answer fundamental questions that relate to rigid plate fixation in the maxilla. Specifically, we sought to elucidate the principal strain patterns generated in the maxilla secondary to masticatory forces as well as the amount of permanent deformational changes incurred due to these loading forces. MATERIALS AND METHODS: Cadaveric heads with the mandible removed were defleshed and placed in a 2-part testing rig to hold and position the skull for testing in a standard material testing system. Rosette strain gages were attached at predefined points on the skull, and an Instron machine was used to load the skull through the loading port on the tray. A Le Fort I osteotomy was then performed on the skull, and a Walter Lorenz Ultra-Micro plating system was applied by a surgeon to reconnect the upper jaw. A 2-mm gap was left at the line of the osteotomy, and a transducer was attached to measure closure of the gap. Again the skull was loaded with the Instron (Canton, MA) machine. RESULTS: The results indicate a linear relationship exists with both maximum (tensile) and minimum (compressive) strain patterns relative to incremental load placement on the intact maxilla. The strain patterns after the Le Fort I osteotomy and plating were different and less linear. The differential variable reluctance transducer data showed a low rate of closure or transient increase in the gap at low loads (0 to 15 kilopond [kp] range) and a steeper slope of closure during high loads (15 to 60 kp range). It is also evident that axial loading forces cause permanent deformation and failure of osseous plating systems predominantly through bending. CONCLUSIONS: This model provides a foundation of knowledge regarding biomechanical strains in the maxilla subjected to static compressive loads in the force range of mastication. In addition, it serves as a comparative reference to assess rigidity of various craniofacial plating systems and to validate proposed standardized synthetic models. With the advent of increasingly precise surgery and new plating systems, this model can be used to help guide placement and design of plating systems; thereby allowing for ideal stabilization and optimizing surgical outcome.

Aged↗
PubMed2003

Custom modification of the Blom-Singer tracheostoma valve housing.

A technique is presented for modifying the Blom-Singer tracheostoma valve housing to improve peristomal skin adherence for hands-free tracheoesophageal speech production following total laryngectomy. The finished product is thin, flexible, and maintains enhanced tear strength. The edges of a standard housing device for the Blom-Singer valve are trimmed to allow for better accommodation to the tissue surface without distortion. A punch biopsy instrument is used to cut uniform holes around the housing device to allow for permeation of the silicone mixture for better mechanical adherence of the materials.

Adhesives↗
PubMedDate not supplied

Effect of disk fenestration on sagittal kinematics of the canine C5-C6 intervertebral space.

OBJECTIVE: To determine the effect that ventral intervertebral disk fenestration has on the sagittal range of motion about the C5-C6 intervertebral space. STUDY DESIGN: A repeated measures in vitro mechanical study of spinal range of motion under controlled loading conditions before and after fenestration. SAMPLE POPULATION: A total of 10 canine cervical vertebral specimens (C4-C7) collected from clinically normal animals within 12 hours of euthanasia. METHODS: Specimens were loaded as cantilever beams fixed at C7. Weights (1 to 5 kg) were progressively applied to C4 to produce flexion or extension in the sagittal plane. Radiographs were taken at each load, 3 times before and 3 times after fenestration of the C5-C6 disk. The positions of radiodense markers embedded in the vertebrae were used to calculate flexion and extension angles and range of motion. RESULTS: Range of motion (difference between flexion and extension) and flexion and extension angles (individually) significantly increased after fenestration (P < .0001). CONCLUSION: Ventral fenestration produces sagittal instability of the C5-C6 disk space. CLINICAL RELEVANCE: In surgical fusion of caudal cervical intervertebral spaces in dogs, radiographically normal disks adjacent to the affected space are often fenestrated to facilitate distraction before surgical stabilization. This study shows that ventral fenestration produces instability of a caudal cervical intervertebral space in the model used. Such instability may contribute to the development of the secondary instability ("domino lesions") seen in some surgically treated dogs.

Animals↗
PubMed2003

Correlation of biomechanical stiffness with plain radiographic and ultrasound data in an experimental mandibular distraction wound.

The aim of this study was to determine the stiffness of a porcine mandibular distraction wound at the end of neutral fixation.Twenty-four Yucatan minipigs underwent unilateral mandibular distraction: zero-day latency, rates of 1, 2, and 4 mm per day, distraction gap of 12 mm. Radiographic and ultrasound bone fill scores at 0, 8, 16 and 24 days of neutral fixation were used to evaluate interval healing. At sacrifice, biomechanical stiffness was determined using an Instron machine to produce a downward force of 2 mm/min at the premolar occlusal surface. Force (kilo-Newton, kN) and displacement (mm) were recorded at a rate of 10,000 points/second. Stiffness across the distraction wound, plain radiographic and ultrasound bone fill scores all increased with duration of neutral fixation and were highest for the 1 mm per day group at all time points. At the end of fixation, even in the most clinically stable group, stiffness across the distraction wound was only 25.5% of control.Despite clinical stability and high bone fill scores by X-ray and ultrasound, the distraction wound did not achieve normal stiffness at the end of neutral fixation in this model. This may have implications for the management of patients who undergo large movements by distraction.

Animals↗
PubMed1999

Proximal segment position after distraction with the MD-DOS device.

We investigated cephalometrically the movement of the proximal segment in the sagittal plane in patients treated with distraction (MD-DOS device) for mandibular lengthening. The proximal segment was anteriorly rotated, whilst the distal segment was posteriorly rotated after the lengthening procedure. Thus the angle of the jaw was advanced half the distance of the advancement of the distal segment. One possible reason for the anterior rotation of 3.3 degrees on average is the repositioning of the proximal segment during application of the anterior fixation unit in the cases where mobilization was complete. Another more plausible reason is the anterior pull by the masticatory muscles and elastic bands being greater than the reactive distraction vector component in concert with a flexible telescopic distraction module and a single posterior screw anchorage. The positional movements of both distal and proximal segments were similar to those observed after mandibular advancement with bilateral sagittal split osteotomies.

Adolescent↗
PubMed2002

Chronic flexion contracture of proximal interphalangeal joint treated with the compass hinge external fixator. A consecutive series of 27 cases.

Twenty-seven chronic flexion contractures of the proximal interphalangeal joint were treated with the Compass((R)) hinge external fixator without open surgery. The fixator was removed after a mean of 33 (range, 14-68) days. The mean time from injury to operation was 4 (range, 1-19) years and all patients were reviewed at a mean follow-up of 21 (range, 12-50) months. The mean extension gain was 38 degrees (range, 0-70 degrees), and the mean flexion-extension arc improved by 42 degrees (range, 0-80 degrees). Complications included superficial pin-track infection in 11 cases and pin loosening in four cases.

Adolescent↗
PubMed1999

Esophageal food bolus obstruction: evaluation of extraction and modified push techniques in 75 cases.

BACKGROUND AND STUDY AIMS: Endoscopic extraction is the standard method of treating esophageal food bolus obstructions. The efficacy, efficiency, and safety of various techniques used over a 12-year period were evaluated. PATIENTS AND METHODS: Seventy-five procedures with soft food bolus obstruction were analyzed. If endoscopic extraction failed, or it was determined that alternative techniques would be effective, food was pushed into the stomach by: a) the endoscope tip, with or without a guide wire; or b) the wire-guided Savary dilators. The duration of the procedures included therapeutic Savary dilation (in 61 of 75 cases). RESULTS: Food bolus obstruction was associated with peptic strictures (69%), Schatzki's rings (19%), and tight fundoplications (3 %). No narrowing was seen in 9%. Extraction, scope push and Savary push methods were successful in seven of 16, 48 of 48, and 20 of 20 attempts, respectively. The mean duration, including stricture dilation (+/- 1 standard deviation), for the extraction, scope push and Savary push procedures were 32 (+/- 17), 18 (+/- 14) and 27 (+/- 15) mm, respectively. No cases of perforation, hemorrhage, oxygen desaturation, aspiration, or pneumonia occurred. CONCLUSIONS: Management of esophageal food bolus obstructions by modified push methods and esophageal dilation in the same session appears to be effective, efficient and safe. The methods employed should be individualized for each patient. Push methods require experience and judgment.

Adolescent↗
PubMed2001

Sports injuries related to flexibility, posture, acceleration, clinical defects, and previous injury, in high-level players of body contact sports.

One-hundred-and-two high-level players of the field-games soccer, Gaelic football and hurling began a two-year investigation into the intrinsic causes of sports-injuries; 86 completed the study. During the first year all injuries, and the time affected by injury, were recorded. The subjects then underwent flexibility tests, an accurate photogrammetric assessment of posture, measures of speed and acceleration, and a clinical assessment of anatomical and physiological factors thought to be associated with the risk of sports injury. Time affected by injury was then recorded for a further 12-month period. Stepwise multiple-regression analysis revealed that the number of days of injury during the second 12-month period could be predicted from (1) the days of injury during the first 12-month period, (2) posture, (3) acceleration over 10m from a standing start, and (4) the number of musculo-skeletal clinical defects. Flexibility scores were not found to be significant predictors of injury. It is suggested that injury prevention programmes should concentrate on improving posture and the rehabilitation from previous injury rather than flexibility; and that research should be undertaken into the effectiveness of such interventions.

Acceleration↗
PubMed2002

Running economy is negatively related to sit-and-reach test performance in international-standard distance runners.

The purpose of this study was to investigate the relationship between running economy (RE) and lower body flexibility. Thirty-four international-standard male distance runners (mean +/- s, age 27 +/- 5 years; body mass 64.9 +/- 4.2 kg; VO(2)max 72.8 +/- 3.7 ml x kg(-1) x min(-1)) gave written consent to participate in this study. The subjects performed an incremental treadmill test for the assessment of RE, lactate threshold and VO(2)max, and the sit-and-reach test was used to assess their general lower body and trunk flexibility. Running speeds below the lactate threshold were used to explore the relationship between running economy and sit-and-reach test performance. At 16.0 km x h(-1), the VO(2) was 50.6 +/- 3.7 ml x kg(-1) x min(-1) (range: 44.2 to 57.1 ml x kg(-1) x min(-1)). Pearson product moment correlation coefficients revealed no significant relationships between aerobic demand at 16.0 km x h(-1) and age (r = - 0.19), height (r = 0.15), body mass (r = - 0.18), or VO(2)max (r = - 0.004). However, there was a highly significant relationship between aerobic demand at 16.0 km x h(-1) and the sit-and-reach test score (r = 0.68; p < 0.0001). These results suggest that the least flexible runners are also the most economical. It is possible that stiffer musculotendinous structures reduce the aerobic demand of submaximal running by facilitating a greater elastic energy return during the shortening phase of the stretch-shortening cycle.

Adult↗
PubMed2003

Muscle elastic properties during wrist flexion and extension in healthy sedentary subjects and volley-ball players.

The aim of this study was to determine the effects of gender and chronic hyperactivity (training) on musculo-tendinous stiffness and joint flexibility and to examine in vivo whether those stiffness parameters were correlated. Thus, maximal isometric voluntary contraction, series elastic stiffness during wrist flexion and wrist extension, and wrist flexibility were investigated in healthy sedentary subjects and in women volley-ball players. Maximal isometric contraction and flexibility were measured classically with specific ergometers. Moreover, muscle stiffness measurements were performed thanks to the use of quick-release movements of the wrist, which had previously been maintained in isometric contraction, allowing the calculation of a musculo-tendinous stiffness index. Despite significant differences in maximal voluntary contraction between wrist flexors and wrist extensors for each of the groups tested and between men and women, no significant gender, function or training effects were found upon musculo-tendinous stiffness indices. Flexibility assessments in both women groups demonstrated that active to passive ratios for wrist flexion remain unchanged whereas a significant training-induced increase for wrist extension was observed. Moreover, no significant relationship between women active joint flexibility and musculo-tendinous stiffness indices was found (r(2): 0.0004 - 0.0319, p > 0.05) whatever the muscle function tested. Collectively, the present results suggest that neural factors rather than morphological changes (i. e. muscle architecture and fiber composition) may explain predominantly the functional consequences observed in wrist extension associated with volley-ball training. Moreover, both musculo-tendinous stiffness and joint flexibility give different information about wrist functional status.

Adult↗
PubMed2004

A simple method for field measurements of leg stiffness in hopping.

A new method to measure the leg stiffness in hopping and bouncing, with simple technical equipment and under field conditions, is introduced and validated. The leg stiffness (K (N)) was calculated from only contact and flight times measured by a contact mat. It was compared to the reference stiffness (K (R)) obtained from force platform measurements. Eight subjects performed, first, submaximal hopping movements at different frequencies (1.8 to 4 Hz, by step 0.2 Hz) and, second, maximal hopping. In sub maximal hopping K (N) was significantly correlated with K (R) (r = 0.94; p < 0.001) and the difference between K (N) and K (R) ranged from -7.2 % to 6.9 % (at 1.8 and 3.6 Hz respectively) with a limit of agreement of -1.5 kN x m (-1). In maximal hopping K (N) was also related to K (R) (r = 0.98, p < 0.001) and the inter individual rank order was respected (R = 0.87). It was concluded that the new method could be applied to study extensively intra individual and inter individual variations of leg stiffness in respectively sub maximal and maximal hopping and thus to simplify further investigations in field conditions of the role of stiffness regulation in the optimization of human locomotion.

Adult↗
PubMed2004

[Peak torque and proprioception at the ankle of dancers in professional training].

The ankle is a frequent site of injury for dancers. The aim of the controlled study was to examine the proprioceptive and sensorimotor control of the ankle in a group of dancers in professional training and to compare it with persons unused to physical training. The purpose was to investigate whether dance training influences the torque ratio of plantar flexion to dorsiflexion (PF/DF) and the proprioceptive performance compared to controls. 42 dancers (31 f, 11 m) in professional training and 40 sex- and age-matched controls performed a isokinetic peak torque test, a passive angle-reproduction test (Biodex System 3), and a single-limb-standing test. The female dancers showed a significantly higher peak torque ratio PF/DF at 30 degrees/s. The difference between male dancers and the controls did not reach a significant level. The dancers did not demonstrate lower absolute errors in passive angle-reproduction (5 degrees and 25 degrees PF) than controls. In the single-limb-standing test, the dancers achieved significantly better results than controls. Dancers could profit from special training of the dorsiflexors. In view of the balance deficits, coordinative exercises should be integrated into school and recreational sports more frequently.

Adolescent↗