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[The AO/ASIF Flexnail : A flexible intramedullary nail for the treatment of humeral shaft fractures].

BACKGROUND: The use of conventional implants for intramedullary nailing of humeral shaft fractures is associated with specific difficulties. During antegrade implantation structures of the rotator cuff can be affected leading to a reduced functional result of the shoulder. If the nail is implanted in a retrograde manner problems arise due to a relatively large hole close to or within the olecranon fossa, which is necessary for insertion of the nail. Supracondylar fractures as well as persistent elbow pain and loss of function are reported in the literature. To overcome these disadvantages a flexible nail has been developed that can be stiffened and locked after implantation. METHOD: Between October 2000 and February 2002, 34 patients were treated with the flexible nail at our institution; 29 were available for follow-up. Fracture healing was documented on radiographs and clinical outcome was evaluated with use of the Constant as well as the Kwasny score. RESULTS: Median duration until fracture consolidation was 10 weeks. In two patients fracture union was not achieved within the follow-up period. The median outcome measured with the Constant score was 93 points and 2.5 with the Kwasny score. Both values correspond to a very good functional outcome. CONCLUSION: We conclude that the flexible humeral nail is an excellent treatment option for humeral shaft fractures. Damage to the rotator cuff and the distal humerus can be avoided due to its unique flexible construction, improving the functional outcome of intramedullary nailing for the treatment of humeral shaft fractures.

Adolescent↗

[Urological symptoms after laparoscopic hernia repair. Reduction with a variant of polypropylene mesh].

In the context of a prospective, randomized, controlled double-blind study concerning a reduction of postoperative, urogenital affections after laparoscopic hernia repair using a polypropylene mesh, laparoscopic polypropylene implantation was performed in 40 male patients. Twenty patients received a heavyweight, rigid polypropylene mesh (group A) and the remainder a heavyweight, but softer polypropylene mesh (group B). Questionnaires were used to assess the severity of pain, impairment of sexual life, appearance of urogenital affections, and general condition. On the 3rd postoperative day, testicle blood circulation and testicle volumes were documented by ultrasound, and a congestion of the plexus pampiniformis was excluded by ultrasound with 5 MHz. Starting in the 1st postoperative week, a prevalence of affections such as testicular sensitivity to touch, pain upon ejaculation, and a pulling sensation during urination became apparent in group A. In the 12th postoperative week, 20% in group A still described testicular sensitivity to touch and 10% pain upon ejaculation and a pulling sensation during urination but only 5% in group B. It is essential to reduce urogenital affections after laparoscopic hernia repair by strict indications and appropriately adapted polypropylene meshes.

Aged↗

Clinical classification of patellofemoral pain syndrome: guidelines for non-operative treatment.

The patellofemoral pain syndrome (PFPS) remains a challenging musculoskeletal entity encountered by clinicians. Reviewing the literature, conflicting data seem to exist regarding the effect of non-operative treatment in PFPS patients. A possible explanation may be lack of a clear classification system of patients with PFPS. It is our opinion that the term PFPS still is a 'wastebasket', which probably comprises several different entities. Therefore, it seems important to subdivide this broad group of patients into different categories with a specific rehabilitation approach. In this study, we introduce a classification system, which reflects a consensus reached by the European Rehabilitation Panel. This classification system should help the clinicians to identify the cause(s) of patellofemoral pain, and consequently help to select the most appropriate non-operative treatment. The authors are aware that no rehabilitation protocol will work for all PFPS patients, since the underlying mosaic of pathophysiology and tissue-healing responses are unique. Therefore, the aim of this study with a classification system was to guide the clinician through clinical examination in order to develop a non-operative treatment protocol, specific for each individual with PFPS.

Bone Malalignment↗

Development of a strength test battery for evaluating leg muscle power after anterior cruciate ligament injury and reconstruction.

A more sports-specific and detailed strength assessment has been advocated for patients after anterior cruciate ligament (ACL) injury and reconstruction. The purpose of this study was to develop a test battery of lower extremity strength tests with high ability to discriminate between leg power development on the injured and uninjured sides in patients after ACL injury and in patients who have undergone ACL reconstruction. Twenty-three patients were tested 6 months after ACL injury and 44 patients were tested 6 months after ACL reconstruction. Twenty-four of the 44 patients were operated on using a hamstrings graft and 20 patients were operated on using a patellar tendon graft. All the patients performed a test battery of three strength tests for each leg in a randomised order. The three strength tests were chosen to reflect quadriceps and hamstring muscular power in a knee-extension and a knee-flexion test (open kinetic chain) and lower-extremity muscular power in a leg-press test (closed kinetic chain). There was a higher sensitivity for the test battery to discriminate abnormal leg power compared with any of the three strength tests individually. Nine out of ten patients after ACL reconstruction and six out of ten of the patients after ACL injury exhibited abnormal leg power symmetry using the test battery. Thus, this test battery had high ability in terms of discriminating between the leg power performance on the injured and uninjured side, both in patients with an ACL injury and in patients who have undergone ACL reconstruction. It is concluded that a test battery consisting of a knee-extension, knee-flexion and leg-press muscle power test had high ability to determine deficits in leg power 6 months after ACL injury and reconstruction. Only a minority of the patients had restored leg muscle power. The clinical relevance is that the test battery may contribute to the decision-making process when deciding whether and when patients can safely return to strenuous physical activities after an ACL injury or reconstruction.

Adult↗

The effect of muscle pain on elbow flexion and coactivation tasks.

The effects of muscle pain on movement can easily be observed in daily life routines. However, the influence of muscle pain on motor control strategies has not been fully clarified. In this human experimental study it was hypothesized that muscle pain affects the motor control of elbow flexion movements, in different combinations of range of motion and target size, by decreased agonistic muscle activity and increased antagonistic muscle activity with consequent implications on kinematic parameters. The effects of experimentally induced muscle pain on movement strategy for: (1) small and large range of motion (ROM) elbow flexion movements towards a wide target, (2) large ROM flexion movements towards a narrow and wide target, and (3) subsequent coactivation of agonistic and antagonistic muscles to elbow flexion were assessed. Muscle pain induced by injections of hypertonic saline (1 ml, 5.8%) in either m. biceps brachii or m. triceps brachii caused similar effects on the movements. For low accurate movements the initial (100 ms) integrated electromyographic (EMG) activity of m. biceps brachii was decreased during muscle pain. In contrast, integrated EMG of the entire m. biceps brachii burst was decreased by muscle pain only for small ROM at a low accuracy, which also showed decreased EMG activity of m. triceps brachii and m. brachioradialis, together with increased activity of m. trapezius. Finally, high accurate movements and post-movement coactivation were generally not modulated by muscle pain. In summary, the present study shows that acute muscle pain can perturb the motor control strategy, which might be highly important in occupational settings where such a change may need compensatory actions from other muscles and thereby eventually contribute to the development of musculoskeletal pain problems.

Adult↗

The influence of artificially increased hip and trunk stiffness on balance control in man.

Lightweight corsets were used to produce mid-body stiffening, rendering the hip and trunk joints practically inflexible. To examine the effect of this artificially increased stiffness on balance control, we perturbed the upright stance of young subjects (20-34 years of age) while they wore one of two types of corset or no corset at all. One type, the "half-corset", only increased hip stiffness, and the other, the "full-corset", increased stiffness of the hips and trunk. The perturbations consisted of combined roll and pitch rotations of the support surface (7.5 deg, 60 deg/s) in one of six different directions. Outcome measures were biomechanical responses of the legs, trunk, arms and head, and electromyographic (EMG) responses from leg, trunk, and upper arm muscles. With the full-corset, a decrease in forward stabilising trunk pitch rotation compared to the no-corset condition occurred for backward pitch tilts of the support surface. In contrast, the half-corset condition yielded increased forward trunk motion. Trunk backward pitch motion after forwards support-surface perturbations was the same for all corset conditions. Ankle torques and lower leg angle changes in the pitch direction were decreased for both corset conditions for forward pitch tilts of the support-surface but unaltered for backward tilts. Changes in trunk roll motion with increased stiffness were profound. After onset of a roll support-surface perturbation, the trunk rolled in the opposite direction to the support-surface tilt for the no-corset and half-corset conditions, but in the same direction as the tilt for the full-corset condition. Initial head roll angular accelerations (at 100 ms) were larger for the full-corset condition but in the same direction (opposite platform tilt) for all conditions. Arm roll movements were initially in the same direction as trunk movements, and were followed by large compensatory arm movements only for the full-corset condition. Leg muscle (soleus, peroneus longus, but not tibialis anterior) balance-correcting responses were reduced for roll and pitch tilts under both corset conditions. Responses in paraspinals were also reduced. These results indicate that young healthy normals cannot rapidly modify movement strategies sufficiently to account for changes in link flexibility following increases in hip and trunk stiffness. The changes in leg and trunk muscle responses failed to achieve a normal roll or pitch trunk end position at 700 ms (except for forward tilt rotations), even though head accelerations and trunk joint proprioception seemed to provide information on changed trunk movement profiles over the first 300 ms following the perturbation. The major adaptation to stiffness involved increased use of arm movements to regain stability. The major differences in trunk motion for the no-corset, half-corset and full-corset conditions support the concept of a multi-link pendulum with different control dynamics in the pitch and roll planes as a model of human stance. Stiffening of the hip and trunk increases the likelihood of a loss of balance laterally and/or backwards. Thus, these results may have implications for the elderly and others, with and without disease states, who stiffen for a variety of reasons.

Abdomen↗

Abnormal response to physical activity in femurs after heterozygous inactivation of one allele of the Col2a1 gene for type II collagen in mice.

The objective of this study was to evaluate the influence of heterozygous inactivation of one allele of the type II collagen gene (Col2a1) on biomechanical properties and mineral density of bone under physical loading conditions. C57BL/6-TGN mice with heterozygous knockout (HZK) inactivation of Col2a1 gene and their nontransgenic littermate controls were housed in individual cages with running wheels for 9 and 15 months. The running activity of each mouse was monitored continuously throughout the experiment. Bone mineral density (BMD) of mice femora was measured using dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (pQCT). Biomechanical properties were determined using three-point bending tests. Vertebral bone samples were prepared for quantitative polarized light microscopy and digital densitometry of proteoglycans. The concentration of total collagen and collagen cross-links were analyzed using high-performance liquid chromatograpy (HPLC). The average daily running distance was shorter for the HZK mice between the age of 4 and 15 months as compared with normal runners (P < 0.05). The ultimate breaking force was 14.8% and 23.6% (9 vs. 15 months) lower in HZK-runners than in wild-type runners. BMD of the femur was 6.1% lower in HZK-runners at the age of 9 months (P < 0.05). Physical activity increased cortical BMD in wild-type runners but not in the HZK runners at the age of 9 months. The collagen network of the HZK mice was less organized. There were only minor changes in BMD and mechanical and structural properties between sedentary HZK mice and their wild-type controls. Increased physical activity induced significantly lower bone density, mechanical properties, and organization of collagen fibers in male HZK mice. However, there were no major differences in biomechanical parameters between sedentary HZK and wild-type male mice. This suggests an important guiding role of collagen type II in bone remodelling and maturation.

Animals↗

Association of body composition and physical activity with proximal femur geometry in middle-aged and elderly Afro-Caribbean men: the Tobago bone health study.

Osteoporotic fractures are less prevalent in African Americans than in caucasians, possibly because of differences in bone structural strength. Bone structural adaptation can be attributed to changes in load, crudely measured as lean and fat mass throughout life. The purpose of this analysis was to describe the associations of leg lean mass, total body fat mass, and hours walked per week with femoral bone mineral density (BMD) and bone geometry in a cross-sectional sample of 1,748 men of African descent between the ages of 40 and 79 years. BMD, section modulus (Z), cross-sectional area (CSA), and subperiosteal width were measured from dual energy X-ray absortiometry (DXA) scans using the hip structural analysis (HSA) program. Multiple linear regression models explained 35% to 48% of the variance in bending (Z) and axial (CSA) strength at the femoral neck and shaft. Independent of all covariates including total body fat mass, one standard deviation increase in leg lean mass was significantly associated with a 5% to 8% higher Z, CSA, and BMD (P < 0.010) at the neck and shaft. The number of hours walked per week was not a strong or consistent independent predictor of bone geometry or BMD. We have shown that weight is the strongest independent predictor of femur BMD and geometric strength although the effect appears to be mediated by lean mass since leg lean mass fraction and total body fat mass fraction had significant and opposing effects at the narrow neck and shaft in this group of middle aged and elderly men.

Absorptiometry, Photon↗

Effect of zoledronate on bone quality in the treatment of aseptic loosening of hip arthroplasty in the dog.

Periprosthetic bone loss, which is a direct cause of aseptic loosening in total hip arthroplasty (THA), can be suppressed by bisphosphonates. It is unknown how the quality of this bone is affected in the presence of both wear debris (from implant) and bisphosphonates. The objective of this study was to evaluate the effect of zoledronate (ZLN) on bone quality in the presence of wear debris [polyethylene (PE) particles] in a canine model of uncemented THA. Thirty dogs underwent THA, and aseptic loosening was induced via implantation of PE particles packed into the femoral component. For 26 weeks until sacrifice, two groups (each n = 10) received weekly injections of ZLN (low dose 2 mug/kg, high dose 10 mug/kg) and the third group (control) received saline. Histological and radiographic examinations were performed to evaluate the degree of implant reaction. Histomorphometry (static/dynamic) was performed to evaluate bone turnover. Back-scattered electron imaging was used to quantify the newly formed bone and to evaluate the mineralization distribution. Density fractionation and X-ray diffraction were used to evaluate mineral properties, while four-point bending was used to determine mechanical properties. A dose-dependent presence of newly formed subperiosteal bone was found, which appeared to be less mineralized than the adjacent cortical bone. The high-dose ZLN group showed decreased cortical porosity and turnover and increased mineralization profile, failure strength, and modulus. We conclude that ZLN affects some of the material properties of cortical bone and allows the newly formed subperiosteal bone to remain and therefore affect the overall quality of the bone.

Animals↗

Evolutionary conservation of protein backbone flexibility.

Internal protein dynamics is essential for biological function. During evolution, protein divergence is functionally constrained: properties more relevant for function vary more slowly than less important properties. Thus, if protein dynamics is relevant for function, it should be evolutionary conserved. In contrast with the well-studied evolution of protein structure, the evolutionary divergence of protein dynamics has not been addressed systematically before, apart from a few case studies. X-Ray diffraction analysis gives information not only on protein structure but also on B-factors, which characterize the flexibility that results from protein dynamics. Here we study the evolutionary divergence of protein backbone dynamics by comparing the C(alpha) flexibility (B-factor) profiles for a large dataset of homologous proteins classified into families and superfamilies. We show that C(alpha) flexibility profiles diverge slowly, so that they are conserved at family and superfamily levels, even for pairs of proteins with nonsignificant sequence similarity. We also analyze and discuss the correlations among the divergences of flexibility, sequence, and structure.

Amino Acid Sequence↗

Significant roentgenographic parameters for evaluating the flexibility of acute thoracolumbar burst fractures. An in vitro study.

Plain lateral radiographs in a neutral position were studied in ten acute thoracolumbar burst fractures produced by high speed impact on three vertebrae human cadaveric spine segments. Six linear geometric parameters were measured on each film. The ratio of each value in the neutral injured to the intact condition was correlated linearly with the motion parameters obtained from post-traumatic three-dimensional flexibility data (neutral zone NZ; range of motion ROM). Anterior unit height (vertebra+adjacent discs) had the highest correlation with the neutral zone and flexibility in all directions, especially flexion-extension (NZ, R2 = 0.93; flexion ROM, R2 = 0.86; extension ROM, R2 = 0.79) lateral bending (NZ, R2 = 0.83; ROM, R2 = 0.90) and right axial rotation (NZ, R2 = 0.53; ROM, R2 = 0.86). The deformation ratio (average height to depth) correlated most with the neutral zone in left axial rotation (R2 = 0.91) and right lateral bending (R2 = 0.92). Due to the high correlations obtained, these parameters should be evaluated in clinical situations to assess their effectiveness in predicting the instability of burst fractures. Ultimately, prospective clinical studies are required to verify their clinical utility.

Acceleration↗

Biomechanical study of the Grosse-Kempf femoral nail.

We have carried out a biomechanical study of the forces acting on the Grosse-Kempf intramedullary nail to determine those which most affect its structure. We have used finite element analysis to assess the distribution of compression, flexion and torsion forces. The qualitative and quantitative distribution of the tension on the surface of the nail has been observed. We have shown that the torsional force is most important and it is exerted in the posterior part of the nail where there is a change from the unslotted to the slotted section.

Bone Nails↗

A flexible stent with small intestinal submucosa covering for direct intrahepatic portocaval shunt: experimental pilot study in swine.

The suitability of the flexible sandwich Zilver stent-graft (SZSG) with a biologically active tissue layer (small intestinal submucosa) for creation of the intravascular ultrasound (IVUS)-guided direct intrahepatic portocaval shunt (DIPS) was explored in six young swine in a search for a flexible system to replace the rigid polytetrafluoroethylene (PTFE) stent originally used by this group with limited success. The portal vein was punctured from the inferior vena cava through the caudate lobe of the liver using IVUS guidance. After balloon dilation of the puncture tract, DIPS was successfully created in all animals with use of an SZSG 9 mm in diameter and 6 cm or 8 cm long. Only one DIPS remained well patent at 14 days when the animal had to be killed because of encephalopathy. DIPS in the other five animals were found to be either severely stenosed (3 animals) or occluded (2 animals) at 4 weeks due to accelerated formation of neointimal hyperplasia (NIH) in the liver parenchymal portion of the shunt and superimposed thrombosis. The lack of high pressure in the portal system contributed to early endograft closure. The flexible stent and the covering fail badly. The reason for this could be due to either component. More work is required to find a reliable flexible system with long-term patency. Exploration of the IVUS-guided direct extrahepatic portocaval shunt is suggested.

Animals↗

Development of a new intravascular low-profile device for exclusion of aortic aneurysm: an experimental pilot study.

PURPOSE: To present a new intravascular device for the treatment of aorto-iliac aneurysms. METHODS: This new device was tested in five dogs with abdominal aortic aneurysm created experimentally by over-dilation of a balloon-expandable stent with a 16 or 18 mm wide PTA balloon catheter. The design of the device is based on a self-expanding aortic stent which consists of two stretchable circular frames filled with a textile Dacron mesh membrane that is suspended horizontally into the infrarenal abdominal aorta proximally to the aneurysm. The frames are part of a preshaped double helical structure that is introduced longitudinally through a catheter in a parallel fashion and forming the desired shape at the vessel site to be occluded. Two iliac stent-grafts are introduced in a low-profile status through the membrane sealing the aneurysm sac and holding the stent-grafts in place. After stent-graft expansion, a new bifurcation located more proximally than the natural one is created. The follow-up of the dogs was performed clinically and angiographically, and specimens were evaluated histomorphologically. RESULTS: The membrane device can be introduced through a 9 Fr vascular sheath. Technical success was achieved in four of five dogs. Nine of ten stent-grafts could be fixed securely within the membrane, thus preventing dislocation. Aneurysms were excluded immediately, and blood flow to the external iliac arteries was restored by the stent-grafts. At 6-9 months follow-up of technically successful implanted devices, there were no endoleaks, no migration, no stenoses at contact sites between the implant material and vascular wall, and no stenosis or occlusion of the stent-grafts. At microscopic evaluation, the interspace between the membranes was filled with thrombotic material, thus ensuring exclusion of the aneurysm. CONCLUSION: This new device was found to be flexible, low profile and useful in excluding abdominal aortic aneurysm in the experimental setting.

Animals↗

Mechanical properties of metallic stents: how do these properties influence the choice of stent for specific lesions?

PURPOSE: To assess selected balloon-expandable and self-expanding stents for radial force, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement. METHODS: Force-strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radio-opacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of the stent on its delivery system to track over angles of 90 degrees and 60 degrees. RESULTS: The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity. CONCLUSION: There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed.

Alloys↗

Lumbar lordosis in acute and chronic low back pain patients.

Postural changes are sometimes a risk factor for low back pain. Abnormal posture creates a strain on ligaments and muscles that indirectly affects the curvature of the lumbar spine. This study was planned to investigate the relationship between the angles of the lower lumbar spine and spinal mobility in acute and chronic low back pain patients. Fifty patients (25 female, 25 male) with chronic low back pain and fifty (30 female, 20 male) with acute low back pain were included the study. Both groups were subjected to lumbosacral radiography in the lateral position while standing. Patients were assessed by parameters including spinal mobility, sacral inclination angle, lumbosacral angle, and sacral horizontal angle. Spinal mobility included the maximal range of motion of lumbar flexion and extension. The value of the sacral inclination angle was significantly higher and correlated with lumbar extension in chronic low back pain patients ( P<0.005, r=0.32). There was no statistical difference or correlation in lumbosacral and sacral horizontal angles and spinal mobility between the two groups ( P>0.05). Chronic low back pain affects the lower lumbar spine and limits the maximal range of;lumbar extension.

Acute Disease↗

Investigation of the effect of GaAs laser therapy on cervical myofascial pain syndrome.

Low-energy laser therapy has been applied in several rheumatoid and soft tissue disorders with varying rates of success. The objective of our study was to investigate the effect of laser therapy on cervical myofascial pain syndrome with a placebo-controlled double-blind prospective study model. It was performed with a total of 53 patients (35 females and 18 males) with cervical myofascial pain syndrome. In group 1 (n = 23), GaAs laser treatment was applied over three trigger points bilaterally and also one point in the taut bands in trapezius muscle bilaterally with a frequency of 1000 Hz for 2 min over each point once a day for 10 days during a period of 2 weeks. In group 2 (n = 25), the same treatment protocol was given, but the laser instrument was switched off during applications. All patients in both groups were instructed to perform daily isometric exercises and stretching just short of pain for 2 weeks at home. Evaluations were performed just before treatment (week 0), immediately after (week 2), and 12 weeks later (week 14). Evaluation parameters included pain, algometric measurements, and cervical lateral flexion. Statistical analysis was done on data collected from three evaluation stages. The results were evaluated in 48 patients (32 females, 16 males). Week 2 and week 14 results showed significant improvement in all parameters for both groups. However, comparison of the percentage changes both immediately and 12 weeks after treatment did not show a significant difference relative to pretreatment values. In conclusion, the results of our study have not shown the superiority of GaAs laser therapy over placebo in the treatment of cervical myofascial pain syndrome, but we suggest that further studies on this topic be done using different laser types and dosages in larger patient populations.

Arsenicals↗

PASSCLAIM - Physical performance and fitness.

OBJECTIVE: The aim of the EC Concerted Action PASSCLAIM was to develop a set of methods and procedures for assessing the scientific support for function-enhancing and health-related claims for foods and food components. This paper presents a critical review of the existing methods to evaluate the different aspects of physical performance and fitness needed to support claims on foods and food ingredients intended to enhance specific physiological functions. DESIGN AND RESULTS: Based on an inventory of labelling claims on available sport nutrition products, seven physiological functions in the field of physical performance and fitness were identified: 1) strength and power, 2) endurance, energy supply and recovery, 3) hydration/re-hydration, 4) flexibility, 5) tissue growth, 6) free radical scavenger capacity and 7) immune function. For each function the existing methodology was reviewed critically and judged on suitability to generate scientific support for physiological function claims on foods. CONCLUSIONS: A database of methods including advantages and disadvantages of use has been generated for considering the scientific support of claims on foods and food ingredients relating to physical performance and fitness. It will contribute to the formulations of guidelines for assessing the scientific support of enhanced function or reduced disease risk claims on foods.

Biomarkers↗