vendex and Osteoarthritis

Obesity has been identified as a risk factor for osteoarthritis. For the weight-bearing joints, the combination of increased load and changed joint biomechanics could be regarded as underlying principle for this relation. This systematic review of the literature focused on the differences between obese and normal-weight subjects in biomechanics of the hip, knee and ankle joint during every day movements to summarize differences in joint load due to both higher body weight and differences in movement patterns. A systematic search, up to November 2010, was performed in the Pubmed and Embase databases. This review showed that obese individuals adjust their movement strategy of every day movements. At self-selected speed, obese individuals walked slower, with shorter and wider steps, had longer stance duration and had a greater toe-out angle compared with normal-weight individuals. Obese sit-to-stand movement was characterized by less hip flexion and greater foot displacement. Obese individuals showed altered biomechanics during every day movements. These altered biomechanics could be related to the initiation of osteoarthritis by a change in the load-bearing regions of the articular cartilage in the weight-bearing joints.

Topics: Ankle Joint; Biomechanical Phenomena; Cartilage, Articular; Hip Joint; Humans; Joints; Knee Joint; Movement; Obesity; Osteoarthritis; Posture; Range of Motion, Articular; Risk Factors; Torque; Walking; Weight-Bearing

Numerous studies have described 3D kinematics, 3D kinetics and electromyography (EMG) of the lower limbs during quasi-static or dynamic squatting activities. One study compared these two squatting conditions but only at low speed on healthy subjects, and provided no information on kinetics and EMG of the lower limbs. The purpose of the present study was to contrast simultaneous recordings of 3D kinematics, 3D kinetics and EMG of the lower limbs during quasi-stat ic and fast-dynamic squats in healthy and pathological subjects. Ten subjects were recruited: five healthy and five osteoarthritis subjects. A motion-capture system, force plate, and surface electrodes respectively recorded 3D kinematics, 3D kinetics and EMG of the lower limbs. Each subject performed a quasi-static squat and several fast-dynamic squats from 0° to 70° of knee flexion. The two squatting conditions were compared for positions where quasi-static and fast-dynamic knee flexion-extension angles were similar. Mean differences between quasi-static and fast-dynamic squats were 1.5° for rotations, 1.9 mm for translations, 2.1% of subjects' body weight for ground reaction forces, 6.6 Nm for torques, 11.2 mm for center of pressure, and 6.3% of maximum fast-dynamic electromyographic activities for EMG. Some significant differences (p<0.05) were found in internal rotation, anterior translation, vertical force and EMG. All differences between quasi-static and fast-dynamic squats were small. 69.5% of compared data were equivalent. In conclusion, this study showed that quasi-static and fast-dynamic squatting activities are comparable in terms of 3D kinematics, 3D kinetics and EMG, although some reservations still remain.

Topics: Activities of Daily Living; Adult; Biomechanical Phenomena; Electromyography; Female; Humans; Kinetics; Knee; Lower Extremity; Male; Middle Aged; Motion; Movement; Osteoarthritis; Posture; Radiography; Range of Motion, Articular; Rotation; Torque

Patients with osteoarthritis, joint implants or fractures use crutches in order to reduce lower limb loading. However, insufficient information exists on how much the loading is then in fact reduced. This situation was studied by using seven patients who had instrumented hip implants.. Part I: To investigate the effectiveness of forearm crutches, crutch and hip joint contact forces were measured in seven patients with instrumented hip prostheses. Additionally, the bending moments in the implant neck and torsion around its stem were determined. Reductions of peak loads during 3, 4, and 2-point gaits were compared with loads present when walking without crutches. Part II: This examines joint load reduction during a 4-point gait from one to 12 weeks post-operatively.. Part I: During a 3, 4, and 2-point gait, the joint force was 17, 12, and 13% lower than it was while walking without crutches. The corresponding reductions of the bending moment were 16, 11, and 12%, while the maximum torque decreased by 19, 21, and 10%. Part II: The reductions of contact forces in comparison with walking without crutches were highest during the first 4 weeks after surgery. One and 4 weeks post-operatively, the force maximum was 21 and 8% lower than it was after 3 months. When compared with the initial values of the 1st week, crutch forces decreased by 28% in the 4th week and by 38% in the 3rd month.. Average reductions of the joint load by more than 20% are achieved only during the first 4 post-operative weeks. Because fractures are in most cases relatively stable after 6 weeks, and bone ingrowth into implant interfaces is nearly finished after this time, a single crutch and a 2-point gait can be prescribed during the 5th and 6th post-operative week.

Topics: Aged; Biomechanical Phenomena; Crutches; Female; Femoral Vein; Forearm; Gait; Hip Joint; Hip Prosthesis; Humans; Male; Middle Aged; Osteoarthritis; Postoperative Period; Torque; Walking; Weight-Bearing

Modern gait analysis is a powerful non-invasive tool for calculating the mechanical factors involved in pathological processes such as knee osteoarthritis (OA). Although very accurate measurements can be made, the clinical applicability and widespread use of gait analysis have been hindered by a lack of appropriate data analysis techniques for reducing and analysing the resulting large volumes of highly correlated gait data. This paper introduces a multidimensional gait data analysis technique that simultaneously considers multiple time-varying and discrete measures, exploiting the correlation structure between and within the measures. The multidimensional analysis technique was used to detect discriminatory mechanical features of knee OA gait patterns that involved interacting changes in several gait measures, at specific time portions of the gait cycle. The two most discriminatory features described a dynamic alignment difference and a loading response difference with knee OA.

Topics: Aged; Aged, 80 and over; Algorithms; Computer Simulation; Female; Gait; Humans; Image Interpretation, Computer-Assisted; Imaging, Three-Dimensional; Knee Joint; Male; Middle Aged; Models, Biological; Models, Statistical; Movement; Multivariate Analysis; Osteoarthritis; Physical Examination; Reproducibility of Results; Sensitivity and Specificity; Torque

Involvement of mechanical factors in osteoarthrosis (OA) has been well documented. For OA of the human lower limb, the impulse imparted at heelstrike has been suggested as a pathogenic factor. It has also been reported that there is a large amount of variation in the level of impulse experienced by different individuals, and it is suggested that those who experience large impulses are at a greater risk of developing OA. The current study investigated gait patterns of 12 normal subjects to establish the gait determinants responsible for producing large impulses at heelstrike. The results suggest that subtle variations in the early part of the swing phase pattern are responsible for large differences in the impulse experienced at heelstrike; the usually reported gait variables mask these variations.

Topics: Acceleration; Adaptation, Physiological; Adult; Computer Simulation; Gait; Heel; Humans; Leg; Models, Biological; Muscle Contraction; Muscle, Skeletal; Osteoarthritis; Pilot Projects; Postural Balance; Reproducibility of Results; Sensitivity and Specificity; Stress, Mechanical; Torque; Weight-Bearing

The goal of this study was to determine whether or not the intraarticular administration of hyaluronic acid can improve functional parameters, such as isokinetic muscle strength or total work and clinical test results in patients with osteoarthritis (OA) of the knee.. As part of a prospective, controlled study 43 patients with osteoarthritic changes of both knees (radiographic Kellgren stage II-III) were followed in a right/left comparison. The influence of intraarticularly injected hyaluronic acid (20mg hyaluronic acid/2ml Hyalart) on functional and clinical parameters was analysed. We used the isokinetic system Cybex 600 for measuring maximal isokinetic muscle strength and total work. A total of 20 males and 23 females fulfilled the inclusion criteria with an age between 55-78 years and underwent five injections of hyaluronic acid (one injection per week). The injected knee represented the treatment group, while the contralateral knee served as the control.. The maximum peak torque of the knee extensors in the treatment group was measured between 57+/-26.15/32.33+/-19.63Nm prior to the injections and 77.17+/-32.54/47.83+/-21.43Nm following the hyaluronic acid therapy (P< 0.01). The analysis of the knee flexors at angular velocities of 60 degrees /s and 180 degrees /s revealed values of 40.44+/-21.58/22.89+/-16.64Nm and 53.55+/-24.26/34.05+/-17.37Nm (P< 0.01) respectively. The evaluation of the total work of the knee flexors and extensors revealed a significant difference (P< 0.01) between the treatment and control group. The Lequesne score was reduced from 13.57+/-1.88 prior to the injections to 7.94+/-2.53 after the treatment (P< 0.01). The pain score was documented with the help of a visual analog scale. The VAS values were reduced at rest from 3.83+/-1.72cm to 1.36+/-1.42cm and during weight bearing from 7.57+/-1.34cm to 3.75+/-1.32cm in the treatment group (P< 0.01).. This controlled prospective clinical trial confirmed that 5 weekly intraarticular injections of HA (Hyalart) in patients with OA of the knee provide pain relief and functional improvements.

Topics: Aged; Female; Humans; Hyaluronic Acid; Injections, Intra-Articular; Knee Joint; Male; Middle Aged; Muscle, Skeletal; Osteoarthritis; Pain Measurement; Prospective Studies; Torque

To determine if knee joint torques, which are likely relevant to the development and, possibly, progression of knee osteoarthritis, are equivalent between genders during natural, barefoot walking.. Collected stereophotogrammetric and force platform data during comfortable, barefoot walking. Knee joint torques were plotted and statistically compared between genders using both an unpaired t test (p < .05) and an equivalence test (20% delta).. A gait laboratory.. One hundred ten healthy, nondisabled young women and men.. Four knee joint torque parameters normalized for height and weight: (1) peak and (2) duration of sagittal flexor joint torque from early to midstance, and (3) first and (4) second peak coronal (frontal) varus torque values during the stance period.. No statistically significant differences between genders were found, and the values were equivalent between genders for each of the 4 knee joint torque parameters.. These findings support the hypothesis that under similar barefoot conditions women and men have a similar intrinsic biomechanic risk for knee osteoarthritis. Future research to assess the effects of other potential biomechanic factors, such as shoe-wear and activity type, may assist not only in preventing knee joint osteoarthritis, but also in developing new rehabilitative strategies to treat osteoarthritis of the knee.

Topics: Adult; Biomechanical Phenomena; Female; Humans; Knee Joint; Male; Osteoarthritis; Risk Factors; Sex Characteristics; Torque; Walking

We measured the insertion and extraction torque forces in a randomised study of 76 external fixation screws in 19 patients treated by hemicallotasis for osteoarthritis of the medial side of the knee. The patients were randomised to have either standard tapered screws (Orthofix 6/5 mm) or the same screws with hydroxyapatite (HA) coating. One patient had two standard and two HA-coated screws. All patients had an anterior external fixator (Orthofix T-garche), with two screws in the proximal tibial metaphysis parallel to and about 2 cm below the joint surface and two in the tibial diaphysis. The mean torque forces for insertion of the standard screws were 260 Ncm for the proximal to medial screw, 208 for the proximal to lateral screw and 498 and 546 Ncm for the diaphyseal pins. The corresponding forces for the HA-coated pins were not significantly different. The torque forces for the extraction of the standard pins were 2 Ncm for the proximal pins, 277 and 249 Ncm for the distal pins and 482, 478, 585 and 620 Ncm, respectively (p < 0.005) for the HA-coated pins. All 18 of the metaphyseal standard screws were loose at extraction (extraction force < 20 Ncm), but only one of the HA screws in the metaphysis was loose. In the diaphysis the standard screws lost about 40% of their fixation in contrast to the HA-coated screws which retained full fixation strength.

Topics: Adult; Aged; Biocompatible Materials; Bone Nails; Bone Screws; Durapatite; Equipment Design; Female; Fracture Fixation, Internal; Humans; Knee Joint; Male; Middle Aged; Osteoarthritis; Torque

The wrist is essential for hand function. Yet, due to the complexity of the wrist and hand, studies often examine their biomechanical features in isolation. This approach is insufficient for understanding links between orthopaedic surgery at the wrist and concomitant functional impairments at the hand. We hypothesize that clinical reports of reduced force production by the hand following wrist surgeries can be explained by the surgically-induced, biomechanical changes to the system, even when those changes are isolated to the wrist. This study develops dynamic simulations of lateral pinch force following two common surgeries for wrist osteoarthritis: scaphoid-excision four-corner fusion (SE4CF) and proximal row carpectomy (PRC). Simulations of lateral pinch force production in the nonimpaired, SE4CF, and PRC conditions were developed by adapting published models of the nonimpaired wrist and thumb. Our simulations and biomechanical analyses demonstrate how the increased torque-generating requirements at the wrist imposed by the orthopaedic surgeries influence force production to such an extent that changes in motor control strategy are required to generate well-directed thumb-tip end-point forces. The novel implications of our work include identifying the need for surgeries that optimize the configuration of wrist axes of rotation, rehabilitation strategies that improve post-operative wrist strength, and scientific evaluation of motor control strategies following surgery. Our simulations of SE4CF and PRC replicate surgically-imposed decreases in pinch strength, and also identify the wrist's torque-generating capacity and the adaptability of muscle coordination patterns as key research areas to improve post-operative hand function.

Topics: Biomechanical Phenomena; Computer Simulation; Hand; Humans; Models, Biological; Orthopedic Procedures; Osteoarthritis; Torque

Shortening osteotomy of the proximal radius might represent a potential salvage procedure in symptomatic radiocapitellar osteoarthritis, which could decrease radiocapitellar load while preserving the native radial head. In an in-vitro biomechanical investigation, we sought to determine whether shortening osteotomy of the proximal radius (1) decreases the radiocapitellar joint pressure upon axial loading and (2) retains valgus stability of the elbow. In addition, the anatomic configuration of the lesser sigmoid notch was evaluated to assess possible contraindications.. Axial loading (0-400 N) and valgus torque (7.5 N m) over the full range of motion were applied to 14 fresh-frozen specimens before and after shortening osteotomy of the proximal radius by 2.5 mm. Radiocapitellar and ulnohumeral load distribution during axial compression was evaluated using a digital pressure mapping sensor. Valgus displacement was analyzed with a 3D camera system. The inclination angle (α) of the lesser sigmoid notch was assessed via 50 CT scans.. Up to axial loading of 250 N, shortening osteotomy caused a significant decrease in radiocapitellar contact pressures (p < 0.041). Valgus stability of specimens did not differ before and after shortening osteotomy (n.s.). The mean inclination angle (α) of the lesser sigmoid notch was 11.3° ± 6.3°. 46% had an inclination angle of ≤ 10° (type I). 46% had an inclination angle of 11°-20° (type II). In 8%, the inclination angle was >20° (type III).. Shortening osteotomy of the proximal radius can decrease radiocapitellar contact pressures during axial loading of up to 250 N. Primary valgus stability is not relevantly influenced by this procedure. In few patients, shortening osteotomy may cause radioulnar impingement of the radial head at the distal edge of the lesser sigmoid notch due to an inclination angle of >20°. Shortening osteotomy might be a promising treatment option to decrease pain levels in case of isolated radiocapitellar osteoarthritis.

Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Cadaver; Elbow; Elbow Joint; Epiphyses; Female; Humans; Male; Middle Aged; Osteoarthritis; Osteotomy; Pressure; Radius; Range of Motion, Articular; Torque

The utility of biomechanical models and simulations to examine clinical problems is currently limited by the need for extensive amounts of experimental data describing how a given procedure or disease affects the musculoskeletal system. Methods capable of predicting how individual biomechanical parameters are altered by surgery are necessary for the efficient development of surgical simulations. In this study, we evaluate to what extent models based on limited amounts of quantitative data can be used to predict how surgery influences muscle moment arms, a critical parameter that defines how muscle force is transformed into joint torque. We specifically examine proximal row carpectomy and scaphoid-excision four-corner fusion, two common surgeries to treat wrist osteoarthritis. Using models of these surgeries, which are based on limited data and many assumptions, we perform simulations to formulate a hypothesis regarding how these wrist surgeries influence muscle moment arms. Importantly, the hypothesis is based on analysis of only the primary wrist muscles. We then test the simulation-based hypothesis using a cadaveric experiment that measures moment arms of both the primary wrist and extrinsic thumb muscles. The measured moment arms of the primary wrist muscles are used to verify the hypothesis, while those of the extrinsic thumb muscles are used as cross-validation to test whether the hypothesis is generalizable. The moment arms estimated by the models and measured in the cadaveric experiment both indicate that a critical difference between the surgeries is how they alter radial-ulnar deviation versus flexion-extension moment arms at the wrist. Thus, our results demonstrate that models based on limited quantitative data can provide novel insights. This work also highlights that synergistically utilizing simulation and experimental methods can aid the design of experiments and make it possible to test the predictive limits of current computer simulation techniques.

Topics: Adult; Aged; Cadaver; Computer Simulation; Female; Humans; Male; Middle Aged; Models, Anatomic; Muscle, Skeletal; Osteoarthritis; Radius; Range of Motion, Articular; Scaphoid Bone; Torque; Ulna; Wrist Joint

Robots are very useful tools in orthopedic research. They can provide force/torque controlled specimen motion with high repeatability and precision. A method to analyze dissipative energy outcome in an entire joint was developed in our group. In a previous study, a sheep knee was flexed while axial load remained constant during the measurement of dissipated energy. We intend to apply this method for the investigation of osteoarthritis. Additionally, the method should be improved by simulation of in vivo knee dynamics. Thus, a new biomechanical testing tool will be developed for analyzing in vitro joint properties after different treatments.. Discretization of passive knee flexion was used to construct a complex flexion movement by a robot and simulate altering axial load similar to in vivo sheep knee dynamics described in a previous experimental study.. The robot applied an in vivo like axial force profile with high reproducibility during the corresponding knee flexion (total standard deviation of 0.025 body weight (BW)). A total residual error between the in vivo and simulated axial force was 0.16 BW. Posterior-anterior and medio-lateral forces were detected by the robot as a backlash of joint structures. Their curve forms were similar to curve forms of corresponding in vivo measured forces, but in contrast to the axial force, they showed higher total standard deviation of 0.118 and 0.203 BW and higher total residual error of 0.79 and 0.21 BW for posterior-anterior and medio-lateral forces respectively.. We developed and evaluated an algorithm for the robotic simulation of complex in vivo joint dynamics using a joint specimen. This should be a new biomechanical testing tool for analyzing joint properties after different treatments.

Topics: Algorithms; Animals; Biomechanical Phenomena; Body Weight; Computer Simulation; Hindlimb; Joints; Movement; Osteoarthritis; Reproducibility of Results; Robotics; Sheep; Torque

A large external knee adduction torque during gait has been correlated with the progression of knee osteoarthritis (OA). Though foot path changes (e.g. toeing out) can reduce the adduction torque, no method currently exists to predict whether an optimal foot path exists for a specific patient. This study evaluates a patient-specific optimization cost function to predict how foot path changes influence both adduction torque peaks. Video motion and ground reaction data were collected from a patient with knee OA performing normal, toe out, and wide stance gait. Joint and inertial parameters in a dynamic, 27 degree-of-freedom, full-body gait model were calibrated to the patient's normal gait data. The model was then used in gait optimizations that predicted how the patient's adduction torque peaks would change due to changes in foot path. The cost function tracked the patient's normal gait data using weight factors calibrated to toe out gait and tested using wide stance gait. For both gait motions, the same cost function weights predicted the change in both adduction torque peaks to within 7% error. With further development, this approach may eventually permit the design of patient-specific rehabilitation procedures such as an optimal foot path for patients with knee OA.

Topics: Adult; Biomechanical Phenomena; Biomedical Engineering; Computer Simulation; Gait; Humans; Knee Joint; Male; Models, Biological; Osteoarthritis; Torque

The aim of this prospective study was to determine muscle rehabilitation in total ankle replacement (TAR) for unilateral severe ankle osteoarthritis.. Fifteen patients were assessed before and after TAR in 3-month intervals up to 1 year. Clinically, the pain score, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, ankle range of motion for dorsiflexion and plantarflexion (ROM DF/PF) and the calf circumference difference between the affected and contralateral healthy leg were measured. Radiographic assessment consisted of osteoarthritis grading abd evaluation of TAR loosening or migration. Biochemically, isometric maximal voluntary torque for ankle dorsiflexion and plantarflexion was measured simultaneously with surface electromyography (EMG; mean frequency and intensity) of the anterior tibial, medial gastrocnemius, soleus, and peroneus longus muscles. Data were compared to a group of 15 age-matched and gender-matched normal subjects.. From preoperative to 12 months after TAR, improvement was noted in pain scores (from 6.8 to 0.8 points), AOFAS ankle scores (33.7 to 93.3 points), and ROM DF/PF significantly (16.0 to 31.0 degrees). The difference in mean calf circumference between legs decreased not significantly from 2.1 cm to 1.7 cm. The mean DF torque (16.4 to 23.1 Nm) and PF torque (15.8 to 21.6 Nm) of the affected ankle increased significantly. Compared to the contralateral healthy side, the mean EMG intensity recovered.. TAR surgery improved muscle function (torque, EMG intensity) in osteoarthritic ankles. However, after 1 year, patients did not reach the level of the contralateral healthy leg, and the EMG frequency remained unchanged.

Topics: Adult; Aged; Ankle Joint; Arthroplasty, Replacement; Electromyography; Female; Humans; Male; Middle Aged; Muscle, Skeletal; Osteoarthritis; Prospective Studies; Torque

To investigate the clinical outcome of thumb carpometacarpal arthroplasty with entire-thickness flexor carpi radialis (FCR) ligament reconstruction and tendon interposition and to investigate the isokinetic wrist flexion/extension torque and flexion fatigue strength of the surgically treated wrist compared with the nonsurgically treated wrist.. Thirty-nine patients with osteoarthritis who had unilateral thumb carpometacarpal arthroplasty with the entire FCR tendon were studied prospectively with a minimum follow-up period of 24 months. Preoperative Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire score, grip, pinch, and postoperative DASH score, grip, pinch, and Biodex (Shirley, NY) isokinetic wrist flexion/extension torques were recorded. The nonsurgically treated extremity served as the control for each patient with unilateral ligament reconstruction and tendon interposition. Peak torque ratios and fatigue were measured for the control and surgically treated extremities with the Biodex.. Postoperative DASH scores were 12 +/- 4 and were improved significantly from preoperative scores of 43 +/- 4. The surgically treated extremity showed a significantly lower wrist flexion-to-extension peak torque ratio than the control extremity. The control extremity had 2.5 times greater wrist flexion fatigue resistance than the surgically treated side. After surgery the surgically treated extremity had significantly improved grip strength and thumb-index tip pinch compared with the preoperative status.. Our data show conclusively that wrist flexion extension torque ratio decreases and wrist flexion fatigue resistance decreases when the entire FCR tendon is harvested even though the final outcome is favorable and uniformly based on traditional DASH, grip, and pinch scores.

Topics: Adult; Aged; Aged, 80 and over; Arthroplasty; Biomechanical Phenomena; Carpometacarpal Joints; Disability Evaluation; Female; Follow-Up Studies; Hand Strength; Humans; Male; Middle Aged; Muscle Fatigue; Osteoarthritis; Prospective Studies; Range of Motion, Articular; Tendons; Thumb; Torque; Wrist Joint

The aim of the study is to evaluate the test-retest reliability of measures of isokinetic and isometric leg strength and joint function among individuals exhibiting symptoms of mild osteoarthritis. Reliable procedures are needed to assess the effectiveness of an intervention on osteoarthritic symptoms.. Test-retest reliability of two leg strength protocols was assessed using the intraclass correlation coefficient (R). Testing was completed on two occasions separated by 7 days. Eighteen subjects (9 male and 9 female; 54.1+/-11 years) completed an isokinetic testing trial, which consisted of a set of 5 maximal repetitions of the quadriceps and hamstrings at 60 deg/s followed by a set of 15 maximal contractions at 180 deg/s with a 2-min rest between sets and an isometric testing trial, which consist of 3 maximal contractions of the quadriceps for 6 s with a 30-s rest between contractions at 30, 45, and 80 degrees of knee flexion for a total of 9 isometric contractions. A 90-s rest occurred between angles.. Most of the isokinetic variables showed moderate to high intraclass reliability (ICC). Two of the calculated isokinetic variables (work fatigue at 180 degrees /s for extension and for flexion) showed low intraclass reliability (ICC=0.78, resp. ICC=0.6). All calculated ICC values of the isometric variables were moderate to high.. Test-retest reliability of isokinetic and isometric leg strength was high, allowing the intervention protocol to monitor changes in leg strength and joint function among those exhibiting symptoms of mild osteoarthritis.

Topics: Biomechanical Phenomena; Exercise; Female; Humans; Isometric Contraction; Knee Joint; Leg; Male; Middle Aged; Muscle Strength; Muscle, Skeletal; Osteoarthritis; Reproducibility of Results; Torque

Osteoarthritic patients show only a weak association between radiographic signs of joint disease and joint pain and disability. Conversely, muscle weakness is one of the earliest and most common symptoms of patients with osteoarthritis (OA). However, while many experimental models of osteoarthritis include a component of muscular weakness, no model has isolated this factor satisfactorily. Therefore, the purpose of this study was to develop and validate an experimental animal model of muscle weakness for future use in the study of OA. Botulinum Type-A toxin (BTX-A) was uni-laterally injected into the quadriceps musculature of New Zealand white rabbits (3.5 units/kg). Isometric knee extensor torque at a range of knee angles and stimulation frequencies, and quadriceps muscle mass, were quantified for control animals, and at one- and six-months post-repeated injections, in both, the experimental and the contralateral hindlimb. Ground reaction forces were measured in all animals while hopping across two force platforms. Isometric knee extension torque and quadriceps muscle mass was systematically decreased in the experimental hindlimb. Vertical ground reaction forces in the push off phase of hopping were also decreased in the experimental compared to control hindlimbs. We conclude that BTX-A injection into the rabbit musculature creates functional and absolute muscle weakness in a reproducible manner. Therefore, this model may be used to systematically study the possible effects of muscle weakness on joint degeneration, either as an isolated intervention, or in combination with other interventions (anterior cruciate ligament transection, meniscectomy) known to create knee joint degeneration.

Topics: Animals; Botulinum Toxins; Disease Models, Animal; Knee Joint; Muscle Weakness; Muscle, Skeletal; Osteoarthritis; Rabbits; Torque

The posteromedial aspect of the olecranon process is a site of impingement and subsequent osteophyte development in throwing athletes. Treatment with débridement, with resection of osteophytes and varying amounts of normal olecranon bone, is common. We found no reports in the literature concerning the effects of resecting different amounts of normal bone from the posteromedial aspect of the olecranon. We hypothesized that excessive resection would increasingly alter elbow kinematics and that an optimum amount of olecranon resection could be identified.. We investigated the kinematic effects of increasing valgus and varus torques and posteromedial olecranon resections, in twelve cadaveric elbows, with use of an electromagnetic tracking device. Two valgus and two varus torques were applied, and three sequential resections were performed in 3-mm steps from 0 mm to 9 mm. Statistical analyses included paired t tests, 95% confidence intervals, a one-factor analysis of variance with repeated measures, and a post hoc test when significance was established.. Sequential partial resection of the posteromedial aspect of the olecranon resulted in stepwise increases in valgus angulation with valgus torque. Clear differences were seen at each level of resection. A pattern of increased valgus angulation also was seen in association with increased valgus torque. Increased valgus torque resulted in a trend toward increased axial internal rotation of the ulna, whereas increased osseous resection resulted in a decrease in the absolute degree of internal rotation or, in some specimens, increased external rotation.. Although no single critical amount of olecranon resection was identified, valgus angulation of the elbow increased in association with all resections, with a marked increase occurring in association with a 9-mm resection. Our findings challenge the rationale of removing any amount of normal olecranon bone in throwing athletes as doing so may increase strain on the medial collateral ligament. The implications for the professional throwing athlete are important, and we recommend that bone removal from the olecranon be limited to osteophytes, without the removal of normal bone.

Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Cadaver; Elbow Joint; Female; Humans; Male; Middle Aged; Orthopedic Procedures; Osteoarthritis; Torque

A simulation model and trajectory matching method were developed to investigate the differences between two swing phase gait patterns; one giving rise to a large impulse at heelstrike, the other giving a small impulse. Subtle changes in the kinematics of the swing leg dramatically reduced the vertical contact velocity of the ankle at the moment of heelstrike. Phasing of the hip flexor muscles at the start of swing was responsible for the level of impulse observed at heelstrike.

Topics: Adaptation, Physiological; Computer Simulation; Gait; Heel; Humans; Leg; Models, Biological; Muscle Contraction; Muscle, Skeletal; Osteoarthritis; Postural Balance; Stress, Mechanical; Torque; Weight-Bearing

Impaired joint position sense (JPS) has been shown in anterior cruciate ligament (ACL) deficient and osteoarthritic knees. The relation between JPS and function is uncertain. The aim of this study was to determine further if ACL deficient knees show abnormal JPS and the effect of exercise therapy on JPS, and also to assess the relation between JPS, functional stability, and strength.. Fifty patients (46 men and four women, mean age 26.3 years) with unilateral ACL deficient knees were assessed on admission and after rehabilitation (5 hours a day for four weeks). JPS was assessed by reproduction of passive positioning using a visual analogue incorporating a goniometer. Knee stability was analysed by self report questionnaire (score 0-280) and functional activity test (single leg hop and figure of eight run). Isokinetic dynamometry was performed to evaluate quadriceps and hamstring peak torque strength. Controls were either age and sex matched individuals or the contralateral knee. Statistical analysis was by Wilcoxon signed rank test and Spearman rank order correlation coefficient.. JPS was impaired in ACL deficient knees. The mean (SD) errors in reproducing angles were 9.4 (3.1) degrees and 7.1 (2.3) degrees for the ACL deficient knee and control knee respectively (P < 0.0005). There was no improvement in JPS after rehabilitation (9.4 (3.1) degrees and 8.5 (3.2) degrees before and after rehabilitation respectively, P = 0.14). There was improvement as ascertained from the questionnaire (on admission 202 (32.1), after rehabilitation 243 (25.4), P < 0.0001) and functional activity testing (hop: on admission 148.7 (37.3) cm, after rehabilitation 169.8 (31.1) cm, P < 0.0005; figure of eight: on admission 48.4 (16.6) seconds, after rehabilitation 41.6 (3.4) seconds, P < 0.0001). Quadriceps strength improved (peak torque on admission 198.5 (58.9) Nm, after rehabilitation 210.5 (54.2) Nm, P < 0.05), but not hamstring strength (peak torque on admission 130.6 (28.1) Nm, after rehabilitation 135.5 (27.7) Nm, P = 0.24). JPS did not correlate with the functional activity tests (hop and figure of eight run), the responses to the questionnaire, or strength. There was no correlation between the responses to the questionnaire and functional activity tests or muscle strength.. JPS was impaired in ACL deficient knees. Although knee stability improved with exercise therapy, there was no improvement in JPS. The role of JPS in the stability of ACL deficient knees remains unclear.

Topics: Adult; Anterior Cruciate Ligament Injuries; Case-Control Studies; Exercise Therapy; Female; Humans; Joint Instability; Knee Injuries; Knee Joint; Male; Muscle Contraction; Muscle, Skeletal; Osteoarthritis; Proprioception; Running; Rupture; Self-Assessment; Stress, Mechanical; Tendons; Torque; Weight-Bearing