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BACKGROUND: Multiple factors contribute to range of motion of the hip joint in the transverse plane: bony anatomy, hip capsule, corresponding ligaments, articular labrum, ligamentum teres, and negative intra-articular pressure. We hypothesized that violation of the negative pressure of the hip and simulation of an effusion would increase range of motion in the transverse plane in a cadaver model. METHODS: Ten hip specimens were obtained and dissected with the femur and iliac wing mounted in a custom joint-testing rig in neutral position. Specimens were tested at 0 and at 90° of flexion with 1.5Nm internal and external rotational torque. Three conditions were assessed: (1) intact specimen, (2) an effusion modeled by a 10ml saline infusion, and (3) a capsular tear. FINDINGS: The modeled effusion decreased rotational range of motion limits in both 0 and 90° of flexion, with a greater effect on the specimens at 0° flexion in external rotation with 4.1° less external rotation (p=0.009). A modeled capsular tear increased rotational motion limits in 0° of flexion in both internal and external rotation and in 90° flexion in internal rotation only (p<0.025). INTERPRETATION: An effusion may decrease the rotation of the hip, and a capsular tear may increase its rotation. This should be considered in hips with traumatic capsular tears or arthroscopic portals.

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CONTEXT: Quadriceps dysfunction is a common consequence of knee joint injury and disease, yet its causes remain elusive. OBJECTIVE: To determine the effects of pain on quadriceps strength and activation and to learn if simultaneous pain and knee joint effusion affect the magnitude of quadriceps dysfunction. DESIGN: Crossover study. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: Fourteen (8 men, 6 women; age = 23.6 ± 4.8 years, height = 170.3 ± 9.16 cm, mass = 72.9 ± 11.84 kg) healthy volunteers. INTERVENTION(S): All participants were tested under 4 randomized conditions: normal knee, effused knee, painful knee, and effused and painful knee. MAIN OUTCOME MEASURE(S): Quadriceps strength (Nm/kg) and activation (central activation ratio) were assessed after each condition was induced. RESULTS: Quadriceps strength and activation were highest under the normal knee condition and differed from the 3 experimental knee conditions (P < .05). No differences were noted among the 3 experimental knee conditions for either variable (P > .05). CONCLUSIONS: Both pain and effusion led to quadriceps dysfunction, but the interaction of the 2 stimuli did not increase the magnitude of the strength or activation deficits. Therefore, pain and effusion can be considered equally potent in eliciting quadriceps inhibition. Given that pain and effusion accompany numerous knee conditions, the prevalence of quadriceps dysfunction is likely high.

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OBJECTIVES: The purpose of this study was to assess the effects of acute joint effusion on balance in patients with knee osteoarthritis. DESIGN: Forty-four female subjects with painful knee osteoarthritis participated in this single-blind, randomized, controlled clinical trial. All subjects were randomly assigned to either the injection or the control group. A volume of 20 ml of normal saline was injected into the knee joint cavity of the test subjects, who performed static and dynamic balance tests twice before and after joint infusion. The subjects in the control group performed the same tests without joint infusion. The outcome variables for static measurement were the mean speeds (millimeter per second) of the movement of the center of pressure in the mediolateral and anteroposterior directions and the mean velocity moment (square millimeter per second) with both eyes opened and eyes closed conditions. For dynamic measurement, time (second) and distance (millimeter) of the center of pressure were used. RESULTS: Significant interaction of the balance-test variables (mean speeds, velocity moment, time, and distance) between the groups and time (P > 0.05) was not found. There were no significant differences between the groups in any of the balance-test variables (P > 0.05). CONCLUSIONS: This study showed that acute joint effusion has no effect on static or dynamic postural sway in patients with knee osteoarthritis.

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OBJECTIVE: The aim of this study was to perform a validation study assessing the correlation between magnetic resonance (MR) findings of temporomandibular joint (TMJ) disk displacement and effusion and some parameters drawn from kinesiographic (KG) recordings of jaw motion, i.e., deflection, deviations, incisures. STUDY DESIGN: Thirty-one patients with TMJ disorders underwent a kinesiographic recording in the same day in which the MR was performed. Regression analysis was performed to assess the correlation between the MR and KG findings. RESULTS: MR findings were not correlated with KG parameters (P > .05). The accuracy of all KG variables for diagnosing MR-detected signs was low. KG deflection ranged from 38.7% to 54.8%, KG deviation from 42% to 54.8%, and KG incisures from 9.6% to 71%. Specificity and positive predictive values were far from acceptable levels for all KG variables. CONCLUSIONS: The findings do not support the usefulness of jaw-tracking devices in dental practices that diagnose and manage temporomandibular disorders.

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Eleven fresh-frozen cadaveric upper extremities were studied to determine the effect of intra-articular fluid volume on the range of motion of the elbow. The flexion arc of the cadaveric elbows was measured before and after incremental injections of saline solution. Linear regression analysis showed that the relationship between the flexion arc and intra-articular fluid volume is linear up to a total volume of 25 mL. The flexion arc of motion decreased by a mean of 2.1 degrees per milliliter of fluid injected. A mean volume of 10.8 mL of saline solution decreased the flexion arc to the point where surgery has traditionally been recommended for type II radial head fractures. On the basis of these findings, the use of post-aspiration range of motion should be reconsidered as a criterion for surgical treatment of radial head fractures.

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OBJECTIVE: To determine the effects of a simulated knee joint effusion on center of pressure (COP) path and mean power frequency (MPF) during standing. DESIGN: Quasi-experimental design. SETTING: Sports injury research laboratory in a university setting. PARTICIPANTS: Twenty healthy volunteers, 10 of whom (age, 20.1+/-2.4y; height, 168.0+/-8.1cm; weight, 70.4+/-13.3kg) were assigned to an effusion group and 10 of whom (age, 25+/-3.8y; height, 169.4+/-8.9cm; weight, 74.7+/-7.7kg) were assigned to a control group. INTERVENTIONS: COP data were collected before and after a 60-mL injection of sterile saline into the knee joint space. MAIN OUTCOME MEASURES: COP path and mediolateral and anteroposterior MPF. RESULTS: COP path decreased after the effusion (pre-effusion mean, 92.2+/-21.9cm; posteffusion mean, 77.27+/-23.0cm). No change was found within the control group for COP path (P>.05). No differences were detected before or after joint effusion when the MPF was examined (P>.05). CONCLUSIONS: Possible explanations for the improved postural control after the effusion include additional somatosensory feedback, an augmented neural drive to the soleus, and/or increased capsular tension.

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Enthesitis is an inflammatory lesion of the tendon, ligament and capsular insertions into the bone, and it is a fundamental element in the diagnosis of spondyloarthropathies. Sonography is the method of choice for studying periarticular soft tissues because it is capable of detecting both the early (oedema, thickening) and late alterations (erosions and enthesophytes); it is also an inexpensive, biologically harmless and easily repeatable technique. The aim of this study was to compare the prevalence of quadricipital enthesitis in psoriatic arthritis (PsA) and rheumatoid arthritis (RA) patients, and to document any clinical and echostructural differences in this lesion between the two diseases. The results show that enthesitis is more frequent in PsA patients, more than half of whom are asymptomatic. Knee inflammation was found in the PsA patients with enthesitis regardless of the concomitant presence of joint effusion; none of the RA patients suffered from enthesitis alone. Quadricipital enthesitis is more frequent in male patients. There was no significant correlation between the presence of peripatellar psoriatic lesions and enthesitis. Sonographic examinations of patients with enthesitis revealed that those with RA had predominantly inflammatory lesions, whereas PsA patients also showed major new bone deposition.

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We compared the effects of continuous passive motion (CPM) given for a minimum of 20 hours a day to Group 1 patients (n = 15) or a maximum of 5 hours a day to Group 2 patients (n = 8) who received total knee joint replacements. Four variables were analyzed on the third and sixth days after surgery: 1) range of motion, 2) edema-effusion, 3) pain, and 4) length of hospital stay. We found significant improvements in knee extension (p less [corrected] than .001) in the Group 2 patients on Day 6 after surgery. We also found a significant negative correlation between the length of hospital stay and the number of physical therapy treatments received. No between-group differences were found in measurements of 1) total knee excursion, 2) edema-effusion, 3) pain, 4) length of hospital stay, and 5) number of PT treatments received. This lack of differences implies that comparable results can be obtained by using the CPM machine either 20 hours a day or 5 hours a day.

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This study was designed to elucidate the role of effusion in producing the reflex inhibition, and subsequent atrophy, of quadriceps musculature following knee trauma. In particular, consideration was given to determining the extent, threshold and linearity of inhibition of the motoneuron pool induced by experimental introduction of small increments of 0.9% physiological saline (up to 60ml) into the joint space of the knee in ten healthy subjects. Inhibition of the quadriceps muscle motoneuron pool was indirectly assessed through recording Hoffmann (H) reflexes evoked from vastus medialis, lateralis and rectus femoris. All ten subjects showed a significant (p less than 0.05) reduction in H-reflex amplitude following the introduction of saline: vastus medialis reduced to 55.7 +/- 4.3% of its control 0ml value, rectus femoris to 69.1 +/- 6.1% and vastus lateralis to 65.3 +/- 4.0%. Post hoc analyses of the H-reflex amplitudes at each increment of simulated effusion revealed the threshold for reflex inhibition of the vastus medialis to be between 20 and 30ml of saline and for rectus femoris and vastus lateralis to be between 50 and 60ml. These procedures were repeated on eight subjects following an injection of the anesthetic lidocaine (1%) to the intra-articular space of their knee joints but there was no significant reduction in H-reflex amplitude. Linear relationships were found to adequately describe the relationships between the volume of effusion and intra-articular pressure; and volume of effusion and reduction in H-reflex amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

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