To determine the dose-response relationship between ambulatory load magnitude during a walking stress test and load-induced changes in serum concentration of cartilage oligomeric matrix protein ...(sCOMP) in healthy subjects.
Design: sCOMP was assessed before and after a 30-min walking stress test performed on three test days by 24 healthy volunteers. In each walking stress test, one of three ambulatory loads was applied in a block randomized crossover design: normal body weight (BW) (100%BW = normal load); reduced BW (80%BW = reduced load); increased BW (120%BW = increased load). Knee kinematics and ground reaction force (GRF) were measured using an inertial sensor gait analysis system and a pressure plate embedded in the treadmill.
Load-induced increases in sCOMP rose with increasing ambulatory load magnitude. Mean sCOMP levels increased immediately after the walking stress test by 26.8 ± 12.8%, 28.0 ± 13.3% and 37.3 ± 18.3% for the reduced, normal or increased load condition, respectively. Lower extremity kinematics did not differ between conditions.
The results of this study provide important evidence of a dose-response relationship between ambulatory load magnitude and load-induced changes in sCOMP. Our data suggests that in normal weight persons sCOMP levels are more sensitive to increased than to reduced load. The experimental framework presented here may form the basis for studying the relevance of the dose-response relationship between ambulatory load magnitude and load-induced changes in biomarkers involved in metabolism of healthy articular cartilage and after injury.
The aim of this study was to document the natural history of development and long-term progression of osteoarthritis (OA) in the feline knee after minimally invasive anterior cruciate ligament (ACL) ...transection.
ACL transections of the left knee joint of 14 skeletally mature cats were performed. Radiographic scores, tibiofemoral and patellofemoral joint space and anterior tibial translation were assessed before, immediately and every 3 months after ACL transection (longest follow-up: 93 months).
After 26 months, all ACL transected knees had developed definite OA. The earliest changes were observed on the tibia plateau starting as early as 2 months after ACL transection, and at 12 months signs of OA were present in more than 80% of cats in the medial and in almost 80% of cats in the lateral compartment. In the first 24 months, medial tibiofemoral joint space decreased by 0.88 mm (95% confidence interval −0.55;−1.21 mm) and lateral tibiofemoral joint space by 0.55 mm (−0.26;−0.85 mm). In the same interval, the joint space in the patellofemoral joint increased by 0.98 mm (0.59; 1.37 mm). Throughout the entire observation period, the anterior tibial translation was on average 5.3 mm greater than in the contralateral knee (4.5; 6.0mm).
Immediate changes in anterior tibial translation during an anterior drawer test clearly showed joint instability that persisted throughout the lifetime of the animals. Degenerative changes were observed on radiographs within 4 months of the injury only in the transected but not the contralateral limb suggesting the role of mechanical instability for the development and progression of knee OA.
The purpose of this study was to determine the long-term impact of surgical repair and subsequent 6-week immobilization of an Achilles tendon rupture on muscle strength, muscle strength endurance and ...muscle activity. 63 patients participated in this study on average 10.8 ± 3.4 years after surgically repaired Achilles tendon rupture and short-term immobilization. Clinical function was assessed and muscle strength, strength endurance and muscle activity were measured using a dynamometer and electromyography. Ankle ROM, heel height during heel-raise tests and calf circumference were smaller on the injured than on the contralateral side. Ankle torques during the concentric dorsiflexion tasks at 60 °/sec and 180 °/sec and ankle torques during the eccentric plantarflexion task and during the concentric plantarflexion task at 60 °/sec for the injured leg were significantly lower than those for the contralateral leg. The total work during a plantarflexion exercise at 180 °/sec was 14.9% lower in the injured compared to the contralateral leg (p < 0.001). Muscle activity for the gastrocnemius muscle during dorsiflexion tasks was significantly higher in the injured than in the contralateral limb. Limited ankle joint ROM and increased muscle activity in the injured leg suggest compensatory mechanisms to account for differences in muscle morphology and physiology caused by the injury.
Summary Objective To evaluate the hypothesis that a mechanical stimulus (30-min walk) will produce a change in serum concentrations of cartilage oligomeric matrix protein (COMP) that is associated ...with cartilage thickness changes on magnetic resonance imaging (MRI). Methods Serum COMP concentrations were measured by enzyme-linked immunosorbent assay in 17 patients (11 females, age: 59.0 ± 9.2 years) with medial compartment knee osteoarthritis (OA) at study entry immediately before, immediately after, 3.5 h, and 5.5 h after a 30-min walking activity. Cartilage thickness changes in the medial femur and medial tibia were determined from MR images taken at study entry and at 5-year follow-up. Relationships between changes in cartilage thickness and COMP levels, with post-activity concentrations expressed as a percentage of pre-activity levels, were assessed by the calculation of Pearson correlation coefficients and by multiple linear regression analysis, with adjustments for age, sex, and body mass index (BMI). Results Changes in COMP levels 3.5 h and 5.5 h post-activity were correlated with changes in cartilage thickness in the medial femur and tibia at the 5-year follow-up. The results were strengthened after analyses were adjusted for age, sex, and BMI. Neither baseline pre-activity COMP levels nor changes in COMP levels immediately post-activity were correlated with cartilage thickness changes. Conclusions The results of this study support the hypothesis that a change in COMP concentration induced by a mechanical stimulus is associated with cartilage thinning at 5 years. Mechanically-induced changes in mechano-sensitive biomarkers should be further explored in the context of stimulus–response models to improve the ability to assess OA progression.
Summary Objective To test the hypotheses that 1) 14-days of immobilization of young healthy subjects using a 6°-“head-down-tilt-bed-rest”-model (6°-HDT) would reduce cartilage thickness in the knee ...and serum Cartilage oligometric matrix protein (COMP) concentration and 2) isolated whole body vibration training would counteract the bed rest effects. Method The study was performed and designed in compliance with the Declaration of Helsinki and is registered as trial DRKS00000140 in the German Clinical Trial Register (register.germanctr.de). Eight male healthy subjects (78.0 ± 9.5 kg; 179 ± 0.96 cm, 26 ± 5 years) performed 14 days of 6°-HDT. The study was designed as a cross-over-design with two study phases: a training and a control intervention. During the training intervention, subjects underwent 2 × 5-min whole body vibration training/day (Frequency: 20 Hz; amplitude: 2–4 mm). Magnetic resonance (MR) images (slice thickness: 2 mm; in-plane resolution: 0.35 × 0.35 mm; pixels: 448 × 512) were taken before and after the 6°-HDT periods. Average cartilage thicknesses were calculated for the load bearing regions on the medial and lateral articulating surfaces in the femur and tibia. Results While the control intervention resulted in an overall loss in average cartilage thickness of −8% (pre: 3.08 mm ± 0.6 mm post: 2.82 mm ± 0.6 mm) in the weight-bearing regions of the tibia, average cartilage thickness increased by 21.9% (pre: 2.66 mm ± 0.45 mm post: 3.24 mm ± 0.63 mm) with the vibration intervention. No significant differences were found in the weight-bearing regions of the femur. During both interventions, reduced serum COMP concentrations were observed (control intervention: −13.6 ± 8.4%; vibration intervention: −9.9 ± 3.3%). Conclusion The results of this study suggest that articular cartilage thickness is sensitive to unloading and that vibration training may be a potent countermeasure against these effects. The sensitivity of cartilage to physical training is of high relevance for training methods in space flight, elite and sport and rehabilitation after illness or injury.
The purposes of this study were (a) to determine lower extremity anthropometric and sensory factors that are related to differences in comfort perception of shoe inserts with varying shape and ...material and (b) to investigate whether shoe inserts that improve comfort decrease injury frequency in a military population.
206 military personnel volunteered for this study. The shoe inserts varied in arch and heel cup shape, hardness, and elasticity in the heel and forefoot regions. A no insert condition was included as the control condition. Measured subject characteristics included foot shape, foot and leg alignment, and tactile and vibration sensitivity of the plantar surface of the foot. Footwear comfort was assessed using a visual analog scale. Injury frequency was evaluated with a questionnaire. The statistical analyses included Student's t-tests for repeated measures, ANOVA (within subjects), MANOVA (within insert combinations), and chi-square tests.
The average comfort ratings for all shoe inserts were significantly higher than the average comfort rating for the control condition. The incidence of stress fractures and pain at different locations was reduced by 1.5-13.4% for the insert compared with the control group. Foot arch height, foot and leg alignment, and foot sensitivity were significantly related to differences in comfort ratings for the hard/soft, the viscous/elastic, and the high arch/low arch insert combinations.
Shoe inserts of different shape and material that are comfortable are able to decrease injury frequency. The results of this study showed that subject specific characteristics influence comfort perception of shoe inserts.
Abstract Anthropometric characteristics, particularly body mass, are important factors in the development and progression of varus/valgus angular deformities of the knee and have long-term ...implications including increased risk of osteoarthritis. However, information on how excessive body weight affects the biomechanics of dynamic activities in children is limited. The purpose of this study was to test the hypothesis that during stair-walking lower extremity joint moments normalized to body mass in obese children are greater than those in normal-weight children. Eighteen obese children (10.5 ± 1.5 years, 148 ± 10 cm, 56.6 ± 8.4 kg) and 17 normal-weight children (10.4 ± 1.3 years, 143 ± 9 cm, 36.7 ± 7.5 kg) were recruited. A Vicon system and two AMTI force plates were used to record and analyze the kinematics and kinetics of ascending and descending stairs. Significant differences in spatio-temporal, kinematic and kinetic parameters during ascending and descending stairs between obese and normal-weight children were detected. For stair ascent, greater hip abduction moments (+23%; p = 0.001) and greater knee extension moments (+20%; p = 0.008) were observed. For stair descent, smaller hip extension moment (−52%; p = 0.031), and greater hip flexion moments (+25%; p = 0.016) and knee extension moments (+15%, p = 0.008) were observed for obese subjects. To date, it is unclear if and how the body may adapt to greater joint moments in obese children. Nevertheless, these differences in joint moments may contribute to a cumulative overloading of the joint through adolescence into adulthood, and potentially result in a greater risk of developing knee and hip osteoarthritis.
BackgroundDue to demographic changes, an increasing number of individuals depends on permanent walking aids. The use of forearm crutches is associated with pressure load on hands and forearms which ...can lead to overuse symptoms such as pain, skin bruises or nerve compression. We have recently shown that the main pressure on the forearm during forearm crutch walking is located along the ulnar bone.ObjectivesTo clinically evaluate a recently developed anatomic cuff for forearm crutches.MethodsA clinical pilot study was performed. The design was prospective, longitudinal and uncontrolled with a 4 weeks follow up. Nine patients permanently using conventional forearm crutches for degenerative joint or spine impairment were included. Participants used the forearm crutches with novel anatomically shaped cuffs (Ulnar Pro, Rebotec, Quakenbrueck, Germany) and an anatomic handgrip. The SF36v2 health survey and a questionnaire accessing pain, paraesthesia, comfort and sense of security based on 9-point Likert-scale were used to assess clinical improvement from baseline to the 4-week study end point.ResultsPain (p=.005) and paraesthesia (p=.003) over the ulna decreased and comfort (p=0.003) and sense of security (p=0.004) increased with the anatomic cuff compared to the previously used conventional cuff. Similarly, physical functioning (p=.021), role physical (p=.005), bodily pain (p=.005) and general health (p=.012) measured using the SF36 survey improved.ConclusionsThe anatomic cuff appears superior to conventional cuffs in terms of reduced pain and increased comfort at the forearm. This result is clinically relevant for short and long term users of forearm crutches to reduce discomfort and complications.Disclosure of InterestA. Arnieri: None declared, A. Mündermann: None declared, T. Hügle Consultant for: Dr. Hügle was involved in the development of the anatomic cuff.
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