Can T1-rho MRI detect acetabular cartilage degeneration in femoroacetabular impingement?: a pilot study.

Advanced MRI cartilage imaging such as T(1)-rho (T1ρ) for the diagnosis of early cartilage degradation prior to morpholgic radiological changes may provide prognostic information in the management of joint disease. This study aimed first to determine the normal T1ρ profile of cartilage within the hip, and secondly to identify any differences in T1ρ profile between the normal and symptomatic femoroacetabular impingement (FAI) hip. Ten patients with cam-type FAI (seven male and three female, mean age 35.9 years (28 to 48)) and ten control patients (four male and six female, mean age 30.6 years (22 to 35)) underwent 1.5T T1ρ MRI of a single hip. Mean T1ρ relaxation times for full thickness and each of the three equal cartilage thickness layers were calculated and compared between the groups. The mean T1ρ relaxation times for full cartilage thickness of control and FAI hips were similar (37.17 ms (SD 9.95) and 36.71 ms (SD 6.72), respectively). The control group demonstrated a T1ρ value trend, increasing from deep to superficial cartilage layers, with the middle third having significantly greater T1ρ relaxation values than the deepest third (p = 0.008). The FAI group demonstrated loss of this trend. The deepest third in the FAI group demonstrated greater T1ρ relaxation values than controls (p = 0.028). These results suggest that 1.5T T1ρ MRI can detect acetabular hyaline cartilage changes in patients with FAI.

Macromolecule and water magnetization exchange modeling in articular cartilage.

Magnetization exchange effects between the matrix macromolecules (e. g., collagen and proteoglycan) and water were examined in normal, deuterated, and proteoglycan-depleted articular cartilage. Relaxation results (T(2), T(1rho), and T(1)) suggested that a four-site exchange scheme provided an accurate model for articular cartilage relaxation and interspin group coupling details. Magnetization exchange within the collagen-bulk-water, proteoglycan-collagen, and collagen fibrillar water-collagen cartilage subsystems were quantified. Although collagen-bulk-water was the largest of the cartilage coupling subsystems ( approximately 90% signal) and is exploited in MRI, the rates of magnetization transfer (MT) within the latter subsystems were appreciably larger. Magnetization exchange rates for proteoglycan-collagen and collagen fibrillar water-collagen were 120 s(-1) and 4.4 s(-1), respectively. The observation of these latter two exchange subsystems suggested potential clinical MRI-MT applications in detecting molecular abnormalities associated with osteoarthritis.

Effect of the posterior cruciate ligament in knee-joint proprioception in total knee arthroplasty.

The primary purpose of the study was to examine the role of the posterior cruciate ligament (PCL) in knee-joint proprioception after total knee arthroplasty (TKA). Knee-joint proprioception was measured in 10 patients with nonsacrificed PCL TKAs and 10 with sacrificed PCL TKAs. Knee-joint proprioception was evaluated through reproduction of static knee angles using a Penny and Giles electrogoniometer. The primary variable was absolute angular error (AAE). AAE was defined as the absolute value of the difference between the test angle and the patient's perceived version of the test angle. Proprioception deficit was compared to the WOMAC questionnaire which evaluates pain, stiffness, and physical function of the lower extremity. No significant difference was found between the nonsacrificed PCL TKA (4.33 degrees +/- 1.52 degrees) and sacrificed PCL TKA (4.38 degrees +/- 1.39 degrees) AAE values (P > .4). Furthermore, no significant differences were observed in the WOMAC questionnaire scores for all three parameters between the two types of knee prosthesis (P > .35). The current findings suggest that the preservation of the PCL in TKA may not improve knee-joint proprioception and subsequently may not improve TKA functional performance.

Effect of age and activity on knee joint proprioception.

Falls lead to significant morbidity and mortality in persons older than 65 years of age. Impaired proprioception may be a contributing factor to falls, and this may be influenced by the level of habitual physical activity. The primary purpose of this study was to investigate knee joint proprioception among young volunteers and active and sedentary elderly volunteers. Knee joint proprioception was measured through reproduction of static knee angles using a Penny and Giles electrogoniometer. The secondary purpose of this investigation was to test the reproducibility of the Penny and Giles electrogoniometer in measuring static knee angles. Sixteen young subjects (age range, 19-27 years) and 24 elderly subjects (age range, 60-86 years) participated. Subjects were given a screening history and physical examination to exclude neuromuscular or vestibular disorders or lower limb injuries. Knee joint proprioception was measured two times during one week. The elderly group was separated into active and sedentary subgroups based on their level of activity during the past year. The electrogoniometer was placed laterally across the dominant knee joint. From the prone position each subject attained one of ten randomly predetermined knee joint angles from 10 degrees to 60 degrees. The subject then returned to the starting position and reproduced the test angle. The absolute angular error (the absolute difference between the test angle and subject perceived angle of knee flexion) was determined. A positive correlation was found between control visits for all subjects (r = 0.88), and significant differences were observed between young (mean, 2.01 +/- 0.46 degrees) and active-fold (mean, 3.12 +/- 1.12 degrees; P < 0.001), young and sedentary-old (mean, 4.58 +/- 1.93 degrees; P < 0.001), and active-old and sedentary-old (P < 0.03). These findings demonstrate that the Penny and Giles electrogoniometer is a reproducible device for measuring knee joint angles in both young and elderly subjects. Furthermore, we found that proprioception is diminished with age and that regular activity may attenuate this decline. One strategy to reduce the incidence of poor proprioception and fall with ageing may be regular exercise.

Effects of fatigue on knee proprioception.

OBJECTIVE: To investigate the effects of muscular fatigue on knee joint proprioception. DESIGN: Prospective study. SETTING: Exercise physiology laboratory. PARTICIPANTS: Sixteen (eight men and eight women) healthy volunteers ages 19-27 years, with no history of neuromuscular disorders, vestibular disorders, or lower limb injuries (e.g., ligament/meniscus tear). INTERVENTION: Three separate fatigue protocols [ramp test (RT), continuous test (CT), and interval test (IT)] were performed. All tests consisted of lower limb cycling on a computer-driven cycle ergometer (Lode). The RT was used to calculate the maximal aerobic power (VO2max) and determine the work rates for the CT and IT. Work rate for the RT increased 20/25 W/min to maximal exhaustion. The CT consisted of cycling at 80% VO2max until maximal exhaustion. The IT consisted of cycling alternately at 120% VO2max and at 40% VO2max for 30 s each to the point of maximal exhaustion. MAIN OUTCOME MEASURE: In the standing position, subjects were instructed to perform a two-legged squat to specific knee flexion angles. The absolute angular error (AAE) was measured for each test angle using an electrogoniometer (Penny & Giles, Blackwood, Gwent, U.K.) placed laterally across the dominant knee joint. AAE was defined as the absolute difference between test angle and subject perceived angle of knee flexion. RESULTS: A statistically significant increase in AAE after the RT (1.0 +/- 0.66 degree, p < 0.01), CT (0.70 +/- 0.66 degree, p < 0.03), and IT (1.24 +/- 0.79 degrees, p < 0.01) protocols was observed in the male subjects. Female subjects reported a statistically significant increase in AAE after the CT (0.73 +/- 0.73 degree, p < 0.03) and IT (1.1 +/- 0.89 degrees, p < 0.01) protocols and a nonsignificant increase in AAE (0.19 +/- 0.70 degree, p > 0.5) after the RT protocol. CONCLUSION: These findings suggest that exercising to fatigue may produce a change in subjects' reproduction ability of knee joint angles. This may represent a decline in proprioceptive function after heavy exercise bouts. Whether this suggested proprioceptive decline is at the clinical significance level (e.g., significantly altering joint stability and motion) cannot be determined from the present findings.