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PubMed2007

Effect of photoactivation protocol and radiant exposure on monomer conversion and flexural strength of a resin composite after water and ethanol storage.

The use of soft-start photoactivation to reduce shrinkage stress has become widespread in restorative dentistry. However, an increased susceptibility to ethanol degradation of polymers formed by pulse-delay photoactivation was reported. It was hypothesized that reductions in flexural strength after ethanol storage were related not only to low curing rates, but also to the radiant exposure employed. A commercial composite was subjected to different curing protocols (continuous at high irradiance, continuous at low irradiance, and pulse-delay) and radiant exposures (6, 12, and 24 J/cm2). After 48 h, differences in degree of conversion were minimal and no differences in strength were detected among specimens stored in water. Ethanol storage caused significant strength reductions in pulse-delay and low irradiance specimens that received 6 J/cm2. The results suggest that when low irradiances or pulse-delay methods are used, a relatively high radiant exposure is necessary to originate a polymer network structure similar to that obtained by continuous high irradiance photoactivation.

Composite Resins↗
PubMed2007

Hydroxyapatite moldable formulation using natural rubber latex as binder.

A simple but efficient processing method for shaping intricate bioceramic green bodies has been developed by using natural rubber latex as binder. Different shapes of hydroxyapatite Ca10(PO4)6(OH)2 (HAP) were molded from a composite formulation containing wet precipitated HAP, natural rubber latex (NRL), and a stabilizer. On controlled heat treatment followed by sintering, dense shapes of HAP contours were obtained. The thermal degradation profile of HAP-NRL composites shows that NRL degrades slowly without any abrupt exotherm. The results of energy dispersive X-ray analysis together with inductively coupled plasma (ICP) analysis indicate that the inorganic residue of NRL does not contain any heavy element. The sintered density of the samples increased with increased HAP content in the formulation and percentage shrinkage reduced accordingly. On varying the HAP content in the formulation from 35 to 95 wt %, the compositions with 85, 90, 92, and 95 wt % HAP showed better flexural strength in the range 40-54 MPa and a flexural modulus value in the range 36-50 GPa. The fracture morphology, as observed by the scanning electron microscope confirms that with increased HAP content in the formulation the sample microstructure attains higher uniformity. The Vickers microhardness for the samples sintered at two different temperatures (1150 and 1250 degrees C) showed that hardness increases with increase in the sintering temperature with a maximum for the highest HAP loaded formulation.

Biocompatible Materials↗
PubMed2001

Relation between the flexibility of the WPD loop and the activity of the catalytic domain of protein tyrosine phosphatase SHP-1.

The conserved WPD loop of protein tyrosine phosphatases play an important role in the catalytic activity and the invariant aspartate residue acts as a general acid/base catalyst in the dephosphorylation reaction. In our previous report, we have demonstrated that the catalytic activities of the PTPs are influenced by the flexibility and stability of the WPD loop in its active "open" conformation [Yang et al., 1998]. Phosphatases with a more flexible WPD loop generally have higher specific activity. In this report, we modify the WPD loop of SHP-1 by alanine-scan mutation of the residues flanking the loop and measure their effects on the catalytic activity of the phosphatase. We show that the S418A, V424A, S426A, E427A, and P428A mutants increase the phosphatase activity, possibly due to the increased flexibility of the WPD loop, whereas the L417A, L417G and P425A mutants decrease its phosphatase activity. In addition, we propose that the two-proline residues in the WPD loop (Pro(420) and Pro(425) in SHP-1) work as pivotal points through a conserved hydrophobic network and allows residues between the pivotal points to have maximum flexibility in enhancing the phosphatase activity. Furthermore, our data suggest that the hydrolysis of the phosphoryl-cysteine intermediate, not its formation, is the rate-limiting step with p-nitrophenyl phosphate as the substrate while both the steps are rate-limiting with phosphotyrosine as the substrate.

Alanine↗
PubMedDate not supplied

Identification of the substrate-binding exosites of two snake venom serine proteinases: molecular basis for the partition of two essential functions of thrombin.

The venom of the South American snake Bothrops jararaca contains two serine proteinases, bothrombin and the platelet-aggregating enzyme PA-BJ, which share 66% sequence identity. Each of these proteinases possesses one of the two essential procoagulant functions of thrombin-the clotting of fibrinogen and platelet aggregation. Thus, bothrombin clots fibrinogen but has no direct effect on platelets, unless in the presence of exogenous fibrinogen. PA-BJ induces platelet aggregation by interacting with the protease-activated platelet receptor without clotting fibrinogen. On the other hand, thrombin possesses two extended surfaces. One is composed of basic and hydrophobic residues (exosite I) and the other one of basic residues only (exosite II). These exosites are involved in the recognition of physiological macromolecular substrates. In order to identify the corresponding exosites in bothrombin and PA-BJ and understand the molecular basis of the partition of the two procoagulant functions of thrombin among the two snake venom enzymes, we used molecular modeling to obtain models of their complexes with their natural substrates fibrinogen and a fragment of the protease-activated platelet receptor, respectively. In analogy to thrombin, each of the enzymes presents two exosites. Nonetheless, the exosites contain a smaller proportion of basic residues than thrombin does (45-72%), reducing thus the functional diversity of the enzymes. In addition, the composition of exosite I is different in both enzymes. We identify those residues in exosite I that could contribute to the differences in specificity. Finally, allostery does not seem to mediate macromolecular substrate recognition by these enzymes.

Amino Acid Sequence↗
PubMedDate not supplied

The role of flexibility and hydration on the sequence-specific DNA recognition by the Tn916 integrase protein: a molecular dynamics analysis.

The N-terminal domain of the Tn916 integrase protein (INT-DBD) is responsible for DNA binding in the process of strand cleavage and joining reactions required for transposition of the Tn916 conjugative transposon. Site-specific association is facilitated by numerous protein-DNA contacts from the face of a three-stranded beta-sheet inserted into the major groove. The protein undergoes a subtle conformational transition and is slightly unfolded in the protein-DNA complex. The conformation of many charged residues is poorly defined by NMR data but mutational studies have indicated that removal of polar side chains decreases binding affinity, while non-polar contacts are malleable. Based on analysis of the binding enthalpy and binding heat capacity, we have reasoned that dehydration of the protein-DNA interface is incomplete. This study presents results from a molecular dynamics investigation of the INT-DBD-DNA complex aimed at a more detailed understanding of the role of conformational dynamics and hydration in site-specific binding. Comparison of simulations (total of 13 ns) of the free protein and of the bound protein conformation (in isolation or DNA-bound) reveals intrinsic flexibility in certain parts of the molecule. Conformational adaptation linked to partial unfolding appears to be induced by protein-DNA contacts. The protein-DNA hydrogen-bonding network is highly dynamic. The simulation identifies protein-DNA interactions that are poorly resolved or only surmised from the NMR ensemble. Single water molecules and water clusters dynamically optimize the complementarity of polar interactions at the 'wet' protein-DNA interface. The simulation results are useful to establish a qualitative link between experimental data on individual residue's contribution to binding affinity and thermodynamic properties of INT-DBD alone and in complex with DNA.

DNA-Binding Proteins↗
PubMed1997

Laxity and flexibility of the ankle following reconstruction with the Chrisman-Snook procedure.

The effect of reconstruction of the anterior talofibular ligament with the Chrisman-Snook procedure on neutral zone laxity (anterior-posterior displacement at low loads) and flexibility (a measure of the nonlinear load-displacement response) of the ankle was investigated in vitro during the anterior drawer test. Neutral zone laxity was defined as the magnitude of anterior-posterior displacement of the ankle joint at +/- 2.5 N of applied load. The flexibility parameter was defined as the slope of a line between the natural logarithm of the anterior load applied to the ankle and the resulting displacement. After reconstruction with the Chrisman-Snook procedure, the values for neutral zone laxity of the ankle were significantly less than normal at 0 degree of plantar flexion, whereas the flexibility values were significantly greater than normal. This study revealed that, after the Chrisman-Snook procedure, values for ankle flexibility are not restored to normal even if those for neutral zone laxity are reduced to less than normal. The findings suggest that this nonanatomical reconstruction procedure does not reproduce normal kinematics of the ankle joint. This may help explain some of the adverse clinical reports associated with the Chrisman-Snook reconstruction procedure.

Adolescent↗
PubMed1998

Longitudinal measurement of tibial motion relative to the femur during passive displacements in the cat before and after anterior cruciate ligament transection.

Passive anterior-posterior displacement and medial-lateral rotation of the tibia on the femur in the feline knee were assessed before transection of the anterior cruciate ligament, immediately after transection, and 2 and 4 months after transection. Four anaesthetized experimental and three sham-operated control animals were positioned in a stereotaxic frame. Motions of the tibia relative to the femur were measured with use of 60-Hz video motion analysis, while a strain-gauged system allowed measurement of forces and moments applied to the tibia. Displacement at 15 N of anterior force and 30 degrees of knee flexion increased by an average of 6 mm following transection, and stiffness decreased by an average of 6 N/mm. At 2 and 4 months following transection, there were statistically significant reductions in this abnormal displacement. Stiffness during anterior displacement of the tibia at 30 degrees increased significantly from immediately after transection to 4 months. At 90 degrees, mean anterior displacement decreased from 5.1 mm immediately after transection to 2.9 mm at 4 months. Medial rotation at 30 degrees of knee flexion was significantly decreased from a mean of 16.5 degrees after transection to a mean of 10.7 degrees at 4 months. Changes in medial rotation at 90 degrees, lateral rotation at 90 degrees, and lateral rotation at 30 degrees were not statistically significant. These results indicate a significant change in secondary constraints to tibial motion in response to knee instability.

Animals↗
PubMed2000

Biomechanical consequences of an isolated overload on the human vertebral body.

The biomechanical consequences of an isolated overload to the vertebral body may play a role in the etiology of vertebral fracture. In this context, we quantified residual strains and reductions in stiffness and ultimate load when vertebral bodies were loaded to various levels beyond the elastic regimen and related these properties to the externally applied strain and bone density. Twenty-three vertebral bodies (T11-L4, from 23 cadavers aged 20-90 years) were loaded once in compression to a randomized nominal strain level between 0.37 and 4.5%, unloaded, and then reloaded to 10% strain. Residual strains of up to 1.36% developed on unloading and depended on the applied strain (r2=0.85) but not on density (p = 0.25). Percentage reductions in stiffness and ultimate load of up to 83.7 and 52.5%, respectively, depended on both applied strain (r2 = 0.90 and r2 = 0.32, respectively) and density (r2 = 0.23 and r2 = 0.22, respectively). Development of residual strains is indicative of permanent deformations, whereas percentage reductions in stiffness are direct measures of effective mechanical damage. These results therefore demonstrate that substantial mechanical damage-which is not visible from radiographs-can develop in the vertebral body after isolated overloads, as well as subtle but significant permanent deformations. This behavior is similar to that observed previously for cylindrical cores of trabecular bone. Taken together, these findings indicate that the damage behavior of the lumbar and lower thoracic vertebral body is dominated by the trabecular bone and may be an important factor in the etiology of vertebral fracture.

Adult↗
PubMed2000

Efficacy of monitoring long-bone fracture healing by measurement of either bone stiffness or resonant frequency: numerical simulation.

Development of noninvasive mechanical tests to monitor fracture healing has been hindered because relationships between bone geometry, measurement conditions, and fracture callus strength are not well understood. Beam theory was used to analyze the effects of fracture length, fracture location, end conditions, and fracture callus stiffness on mechanical properties (resonant frequency, bending stiffness, and torsional stiffness) of healing bone. Actual bone mineral geometry from a human tibia, quantified every 1 mm, was used in the beam analysis. Geometry of the fracture callus segment was uniformly scaled from the values for intact bone. Experimental tests on multisegmented machined rods were used to verify analytical methods. Mechanical properties of the healing bone initially increased very rapidly to 30-70% of the stiffness of intact bone, depending on the configuration. The increases then tapered off dramatically. Lateral bending stiffness was sensitive to changes in callus properties for a larger portion of the healing process than was either torsional stiffness or resonant frequency. Because callus strength increases at half the rate of callus stiffness, measures of whole-bone mechanical properties can provide insight into changes in callus strength until a maximum of less than one-half the strength of intact bone is regained. The analytical method presented is proposed for clinical use to develop individualized models of bone, fracture, and fixation conditions to identify early stages of healing. Because increases in whole-bone mechanical properties are small in the later stages of fracture healing, however, such measures must be used prudently beyond the initial stages.

Biomechanical Phenomena↗
PubMed2000

Comparison of biomechanical and biochemical properties of cartilage from human knee and ankle pairs.

Cartilage was obtained from eight matched knee (tibiofemoral and femoropatellar) and ankle (talocrural) joints of five different donors (both left and right from donors 14, 22, and 38 years of age, and left only from donors 31 and 45 years of age) within 24 hours of death. All cartilage was graded as normal by the macroscopic visual Collins' scale and the histological Mankin scale. Cylindrical disks of cartilage were harvested from 10 sites within the tibiofemoral and femoropatellar joint surfaces and four sites within the talocrural joint, and uniaxial confined compression measurements were performed to quantify a spectrum of physical properties including the equilibrium modulus, hydraulic permeability, dynamic stiffness, streaming potential, electrokinetic coupling coefficient, and electrical conductivity. Matched specimens from the same 14 sites were used for complementary measurements of biochemical composition and molecular interaction, including water content, hypotonic swelling behavior, and sulfated glycosaminoglycan and collagen contents. In comparison of the top 1-mm slices of talar cartilage with the top 1-mm of tibiofemoral cartilage, the talar cartilage appeared denser with a higher sulfated glycosaminoglycan content, lower water content, higher equilibrium modulus and dynamic stiffness, and lower hydraulic permeability. The equilibrium modulus increased with increasing sulfated glycosaminoglycans per wet weight and decreased with increasing water content for all joint surfaces. Multiple linear regression showed that greater than 80% of the variation in the equilibrium modulus could be accounted for by variations in the biochemical parameters (water content, sulfated glycosaminoglycans/wet weight, and hydroxyproline content/wet weight) for each joint surface. Nonhomogeneous depth-dependent changes in the physical properties and biochemical composition of full-thickness distal femoral cartilage were consistent with previous reports. Since the compressive deformation of cartilage during cyclic loading is confined to the more superficial regions, the differences in properties of the upper regions of the talar compared with tibiofemoral or femoropatellar cartilage may be important in the etiology of osteoarthritis.

Adolescent↗
PubMed2000

Polysulphated glycosaminoglycan treatments can mitigate decreases in stiffness of articular cartilage in a traumatized animal joint.

A single, blunt impact to the rabbit patellofemoral joint has been shown to decrease the stiffness of retropatellar cartilage and increase the thickness of the underlying bone. Polysulphated glycosaminoglycan treatments, on the other hand, have been shown to inhibit the degradation of articular cartilage and possibly increase synthesis of collagen and glycosaminoglycans in experimental studies on diseased joints. The aim of the current study was to examine the effect of early treatments with polysulphated glycosaminoglycans on cartilage using an in vivo post-trauma animal model. The study used 24 Flemish Giant rabbits in three groups: control, impacted, and impacted with treatment. Treatment consisted of intramuscular injections the day of insult and every 4 days thereafter for 6 weeks. At 30 weeks after trauma, mechanical tests were performed on the retropatellar cartilage to determine its mechanical stiffness. The patellae were also grossly evaluated for surface lesions on the retropatellar cartilage and histologically processed to measure the thickness of the subchondral bone. The rabbits that received no treatment had a statistically significant decrease in stiffness (modulus) for the cartilage of the impacted patellae compared with that of the contralateral, unimpacted patellae and compared with the cartilage of rabbits in the control group. The degradation in mechanical stiffness, however, was not observed in patellae of rabbits in the group receiving treatment. There was also a significant increase in the underlying thickness of the subchondral plate on the impacted patellae compared with that on the contralateral, unimpacted sides for rabbits in both the treated and nontreated groups. In conclusion, the polysulphated glycosaminoglycan treatments minimized a decrease in mechanical stiffness (modulus) of retropatellar articular cartilage 30 weeks after trauma. The mechanism by which the mechanical stiffness of the cartilage was preserved is unknown.

Animals↗
PubMed2000

Effects of harvest and selected cartilage repair procedures on the physical and biochemical properties of articular cartilage in the canine knee.

This study utilizes a canine model to quantify changes in articular cartilage 15-18 weeks after a knee joint is subjected to surgical treatment of isolated chondral defects. Clinical and experimental treatment of articular cartilage defects may include implantation of matrix materials or cells, or both. Three cartilage repair methods were evaluated: microfracture, microfracture and implantation of a type-II collagen matrix, and implantation of an autologous chondrocyte-seeded collagen matrix. The properties of articular cartilage in other knee joints subjected to harvest of articular cartilage from the trochlear ridge (to obtain cells for the cell-seeded procedure) were also evaluated. Physical properties (thickness, equilibrium compressive modulus, dynamic compressive stiffness, and streaming potential) and biochemical composition (hydration, glycosaminoglycan content, and DNA content) of the cartilage from sites distant to the surgical treatment were compared with values measured for site-matched controls in untreated knee joints. No significant differences were seen in joints subjected to any of the three cartilage repair procedures. However, a number of changes were induced by the harvest operation. The largest changes (displaying up to 3-fold increases) were seen in dynamic stiffness and streaming potential of patellar groove cartilage from joints subjected to the harvest procedure. Whether the changes reported will lead to osteoarthritic degeneration is unknown, but this study provides evidence that the harvest procedure associated with autologous cell transplantation for treatment of chondral defects may result in changes in the articular cartilage in the joint.

Animals↗
PubMed2000

Loosening of sacral screw fixation under in vitro fatigue loading.

Sacral screw fixation is frequently used for fusion of the lower lumbar spine, but sacral screws appear to offer less secure fixation than lumbar pedicle screws, and failure due to loosening under fatigue loading is common. The aim of this study was to examine in vitro the stability of medial and lateral bicortical and unicortical sacral screw fixation under a physiologically relevant fatigue-loading pattern. Bone mineral density, screw insertion torque, and screw-fixation stiffness were measured prior to cyclic loading between 40 and 400 N compression at 2 Hz for 20,000 cycles. The screw-fixation stiffness was measured every 500 cycles, and the axial pullout strength of the screws was recorded following loading. All of the lateral insertions loosened under the applied loading, but some of the medial insertions remained stable. Medial insertions proved stiffer and stronger than lateral insertions, and bicortical fixations were stronger than unicortical fixations. Bone mineral density and insertion torque were correlated with screw stiffness and pullout strength, although better correlation was found for insertion torque than bone mineral density. Bone mineral density is a good preoperative indicator of sacral screw-fixation strength, and insertion torque is a good intraoperative indicator. An insertion torque greater than 1.5 Nm is suggested as an indicative value for a stable medial unicortical insertion, whereas an insertion torque greater than 2 Nm suggests a stable medial bicortical insertion. It appears that, apart from the choice of technique (screw orientation and depth), minimizing the load on the screws during the initial part of the fusion process is also critical to maintain stability of the fused section and to obtain a solid fusion mass.

Adult↗
PubMed2000

Structural properties of the subscapularis tendon.

The subscapularis muscle is an important mover and stabilizer of the glenohumeral joint. The purpose of this study was to measure regional variations in the structural properties of the subscapularis tendon in two joint positions. Subscapularis tendons from cadaveric shoulders were divided into four sections superiorly to inferiorly and tested to failure at 0 or 60 degrees of glenohumeral abduction. Arm position had a significant influence on stiffness in the inferior and superior portions (p < 0.05). The inferior region showed a higher stiffness in the hanging-arm position (0 degrees) than at 60 degrees of abduction (27.4+/-17.7 compared with 9.5+/-5.9 N/mm). Meanwhile, stiffness of the superior portion was higher at 60 degrees of abduction than in the hanging-arm position (208.7+/-60.9 compared with 147.2+/-32.3 N/mm). In the hanging-arm position (0 degrees) and at 60 degrees of abduction, the superior and midsuperior portions failed at significantly higher loads (superior: 623.2+/-198.6 and 478.2+/-206.6 N at 0 and 60 degrees of abduction, respectively; midsuperior: 706.2+/-164.6 and 598.4+/-268.4 N, respectively) than did the inferior portion (75.1+/-54.2 and 30.3+/-13.0 N, respectively). Likewise, stiffness of the superior and midsuperior portions was significantly higher than that of the inferior region in both positions. Higher stiffness and ultimate load in the superior tendon region may explain the infrequent extension of rotator cuff tears into the subscapularis tendon. Conversely, the significantly lower ultimate load and stiffness in the inferior tendon region could facilitate anterior dislocation of the humeral head when this portion stabilizes the joint in a dislocated position. Therefore, repair of torn inferior portions of the subscapularis tendon should be considered in surgery for glenohumeral instability.

Aged↗
PubMed2006

Regenerative properties of fetal sheep tendon are not adversely affected by transplantation into an adult environment.

Tendon injuries account for a significant number of musculoskeletal afflictions each year. While new surgical techniques and rehabilitation protocols have led to improved clinical outcomes, postsurgical scarring remains the most problematic aspect of tendon repair. In contrast to this typical pattern of fibrosis, recent studies have shown that fetal tendon is capable of healing without scar. However, whether this regenerative healing pattern is intrinsic to the fetal tissue itself or the result of its environment is not known. Thus, the objective of this study is to examine the influence of an adult environment on healing in adult and fetal tendons. We hypothesized that injured fetal tendon tissue transplanted into an adult environment would retain a regenerative healing pattern after injury, demonstrating normal histological and mechanical properties. Our results support this hypothesis. Histological analyses revealed considerable alterations in adult tendon transplants after injury while fetal transplants showed no abnormalities. The injured adult tendons also demonstrated elevated levels of TGF-beta1, bFGF, and CD44 at the wound site, whereas the fetal specimens showed little or no such changes in response to injury. The data from our biomechanical studies further corroborate these observations, with significant decreases in the stiffness, modulus, and almost all viscoelastic properties in wounded versus unwounded adult tendons, and fetal specimens showing no differences in mechanical properties between the wounded and unwounded groups. Thus, the results of our investigation demonstrate that the adult environment is not an impediment to scarless repair and that this capability is intrinsic to the fetal tendon itself. Our study also begins to provide insight into the mechanisms controlling this regenerative response.

Age Factors↗
PubMed2001

Ring flexibility within tricyclic antidepressant drugs.

The internal flexibility of the central seven-membered ring of a series of tricyclic antidepressant drugs (TCAs), imipramine [1], amitriptyline [2], doxepin [3], and dothiepin [4], has been investigated by (1)H and (13)C nuclear magnetic (NMR) techniques. Two dynamic processes were examined: ring inversion and bridge flexing. (1)H NMR line-shape analysis was used to obtain ring inversion barriers for 2-4. These studies yielded energy barriers of 14.3, 16.7, and 15.7 +/- 0.6 kcal/mol for the hydrochloride salts of doxepin, dothiepin, and amitriptyline, respectively. The barriers for the corresponding free bases were lower by 0.6 kcal/mol on average. (13)C T(1) relaxation measurements were used to determine the degree of bridge flexing associated with the central seven-membered ring for all four compounds. By fitting the T(1) data to a two-state jump model, lifetimes and amplitudes of rapid bridge flexing motions were determined. The results show that imipramine has the fastest rate of bridge flexing, followed by amitriptyline, doxepin, and dothiepin. The pharmacological profiles of the TCAs are complex and they interact with many receptor sites, resulting in numerous side effects and a general lack of understanding of their precise mode of action in different anxiety-related disorders. They all have similar three-dimensional structures, which makes it difficult to rationalize their differing relative potency in different assays/clinical settings. However, the clear finding here that there are significantly different degrees of internal mobility suggests that molecular dynamics should be an additional factor considered when trying to understand the mode of action of this clinically important family of molecules.

Amitriptyline↗
PubMed1995

Plastic hollow waveguides: properties and possibilities as a flexible radiation delivery system for CO2-laser radiation.

BACKGROUND AND OBJECTIVES: One significant inconvenience of the CO2 laser is the lack of flexible fibers essential for endoscopic applications. The goal of this study is to test the feasibility of hollow waveguides in view of a practical use in medicine. STUDY DESIGN/MATERIALS AND METHODS: Various types of plastic hollow waveguides for flexible delivery of CO2 laser radiation were examined. The transmission losses, divergence angle, damage threshold, and input and output beam profiles were determined. The interaction process between radiation transmitted through these guides with soft as well as hard tissues was studied. RESULTS: Plastic hollow waveguides can transmit high power (up to 50 W) with low losses (straight guide 1 dB/m) even through bendings. The divergence angle is < 13 degrees. Cutting quality and extent of thermal damage are comparable to incisions performed with a free laser beam. CONCLUSION: The results of this study show good cutting quality and durability of these flexible plastic hollow waveguides, which render possible to deliver CO2 radiation in the power range needed for most surgical applications with affordable transmission losses. Plastic hollow waveguides are, therefore, a real alternative to replace the mirror arms.

Animals↗
PubMed2000

Effects of a three-month therapeutic exercise programme on flexibility in subjects with low back pain.

BACKGROUND AND PURPOSE: Spinal and muscle flexibility have been studied intensively and used clinically as outcome measurements in the rehabilitation of subjects with low back pain. The results of previous studies are contradictory and there is a lack of longitudinal data on the effects of long term therapeutic exercise on flexibility. METHOD: A controlled experimental study was conducted to determine the effects of progressive therapeutic exercise on spinal and muscle flexibility. Eighty-six chronic low back pain subjects fulfilled the inclusion criteria and were divided into three study groups: (1) intensive training group, (2) home exercise group and (3) control group. The intervention period lasted three months and measurements were performed at both the beginning of the study and immediately after intervention. Follow-up measurements were carried out six and 12 months after baseline. Spinal flexibility was measured with lumbar flexion, extension, spinal lateral flexion and rotation, and muscle flexibility was measured with measurements of erector spinae, hamstring and iliopsoas muscles. Also self-reported outcomes of the Oswestry Index and Borg Scale--Back Pain Intensity were used. Associations between change (pre- to post-treatment) were determined for the dependent variables. RESULTS: The results showed no correlation between flexibility, the Oswestry Index or back pain intensity. After the first three-month period lumbar flexion, extension and spinal rotation decreased among all subjects. Spinal rotation and erector spinae muscle flexibility improved significantly with intensive training. At the nine-month follow-up, erector spine flexibility was still greater than at baseline. Hamstring flexibility increased among the intensive training and home exercise groups from pre- to post-intervention. However, the degree of hamstring flexibility gained during training was subsequently lost following the period without programmed exercise in both training groups. Self-reported outcome variables showed positive changes among the three study groups after the completion of intervention period, but these changes were only able to be maintained during subsequent follow-ups for the intensive training and home exercise groups. CONCLUSIONS: The findings suggest that flexibility does not play an important role in coping with chronic low back pain for subjects whose functional limitations are not severe. Also, it appears that the achieved gains in spinal and muscle flexibility may not be able to be maintained without continued exercise.

Case-Control Studies↗