Effects of Running on Femoral Articular Cartilage Thickness for Anterior Cruciate Ligament Reconstruction Patients and Non-ACLR Control Subjects

Anterior cruciate ligament reconstruction (ACLR) patients are more likely to develop posttraumatic knee osteoarthritis than non-ACLR counterparts. The effect of running on femoral articular cartilage thickness is unclear. PURPOSE: The purpose of this study was to compare how 30 minutes of running influences femoral articular cartilage thickness for ACLR patients and non-ACLR control subjects. We hypothesized that running would deform the femoral articular cartilage more for the ACLR patients than for the control subjects. METHODS: We recruited 20 individuals with primary unilateral ACLR and 20 matched non-ACLR controls. ACLR patients and control subjects were matched based upon age, gender, BMI, and weekly running mileage. The present procedures were approved by the appropriate institutional board and all subjects provided informed consent before data collection. We used ultrasound imaging to measure femoral articular cartilage thickness before and after 30 minutes of running. The ultrasound images were manually analyzed using ImageJ software by the same investigator. Total femoral articular cartilage cross-sectional area of each image was segmented into three regions: medial, lateral, and intercondylar. Deformation due to the run was compared between the ACLR patients and control subjects for each region using independent t tests (P \u3c 0.05, adjusted for multiple comparisons). RESULTS: The 30-minute run resulted in more deformation for the ACLR patients (0.03 ± 0.01 cm) than the matched controls (0.01 ± 0.01 cm) for the medial region (p \u3c 0.01) of the femoral articular cartilage. Identically, the 30-minute run resulted in more deformation for the ACLR patients (0.03 ± 0.01 cm) than the matched controls (0.01 ± 0.01 cm; p \u3c 0.01) for an average of the entire articular cartilage area (medial, lateral, and intercondylar). No significant differences existed between groups for the lateral or intercondylar regions. CONCLUSION: Thirty minutes of running deformed medial and overall femoral articular cartilage more for ACLR patients than non-ACLR control subjects

Femoral Articular Cartilage Quality, but Not Thickness, Is Decreased for Anterior Cruciate Ligament Reconstruction Patients Relative to Control

Anterior cruciate ligament reconstruction (ACLR) patients are at risk of developing posttraumatic knee osteoarthritis (OA). The etiology of posttraumatic knee OA is complex, potentially involving biomechanical and biochemical factors. Changes in femoral cartilage thickness and composition are associated with knee OA, while current research is ambiguous on cartilage in ACLR patients. PURPOSE: This study aimed to compare femoral cartilage thickness and T2 relaxation time (a compositional measure) between ACLR patients and healthy controls in a resting state. We hypothesized that ACLR patients would exhibit thinner femoral cartilage and increased T2 relaxation times. METHODS: Twenty ACLR patients (6-24 months post-surgery) and 20 matched healthy controls were recruited following institutional board approval. Ultrasound and magnetic resonance imaging data were collected on two separate days, allowing cartilage thickness and composition measurements to be made, respectively. Statistical analyses, including independent t-tests and Holm-Bonferroni corrections, were performed on selected regions of interest. RESULTS: The ACLR group showed increased T2 relaxation times in four of eight femoral regions compared to controls. No significant differences in femoral cartilage thickness were observed between the groups. The primary finding from this study is that ACLR patients did not show differences in femoral cartilage thickness (a morphological measure), but displayed prolonged T2 relaxation times (a compositional measure) compared to controls, at rest. This finding suggests that compositional changes precede morphological shifts in femoral cartilage in early post-ACLR periods (6-24 months). CONCLUSION: These early compositional changes may indicate articular cartilage that is more compressible and subject to increased strain on the solid components of the joint. While ultrasound is a more accessible imaging method, magnetic resonance imaging may provide a more accurate and early evaluation of cartilage quality. Further research is needed to develop practical tools for early detection and monitoring of cartilage degradation in ACLR patients before progression into knee osteoarthritis

Running Biomechanics and Knee Cartilage Health in ACLR Patients

Anterior cruciate ligament reconstruction (ACLR) patients are more likely to subsequently suffer from knee osteoarthritis than non-ACLR counterparts. Exercise is thought to influence articular cartilage, however, it is unclear how running biomechanics are associated with femoral cartilage thickness and composition in ACLR patients. PURPOSE: The purpose of this study was to investigate relationships between running biomechanics and measures of femoral articular cartilage condition (thickness and composition) in ACLR patients and control subjects. METHODS: We used ultrasound and MRI (T2 mapping sequence) to measure articular cartilage thickness and composition, respectively, for 20 ACLR patients (age: 23 ± 3 yrs; mass: 70 ± 10 kg; time post-ACLR: 14.6 ± 6.1 months) and 20 matched controls (age: 22 ± 2 yrs; mass: 67 ± 11 kg). After these measures, all participants completed a 30-minute run on a force-instrumented treadmill. Correlational analyses were used to explore relationships between running biomechanics (vertical ground reaction force (vGRF)) and femoral cartilage thickness and composition (T2 relaxation time). The present procedures were approved by the appropriate institutional board and all subjects provided informed consent before data collection was performed. RESULTS: Significant positive correlations existed for the control subjects only between peak vGRF and overall (r = 0.34; p \u3c 0.01), medial (r = 0.23; p \u3c 0.01), lateral (r = 0.39; p = 0.02), and intercondylar (r = 0.31; p \u3c 0.01) femoral thickness. The ACLR patients showed significant negative correlations between T2 relaxation time for the central-medial region of the femoral condyle, and peak vGRF (r = −0.53; p = 0.01) and vertical impulse due to the vGRF (r = −0.46; p = 0.04). CONCLUSION: These findings offer some limited support for the idea that femoral articular cartilage benefits from increase vGRF during running. This is evidenced by the increased thickness for the control subjects and decreased T2 relaxation time (indicative of increased free-flowing water in the cartilage) for the ACLR patients, as running vGRF increased

Eccentric Exercise Facilitates Mesenchymal Stem Cell Appearance in Skeletal Muscle

Eccentric, or lengthening, contractions result in injury and subsequently stimulate the activation and proliferation of satellite stem cells which are important for skeletal muscle regeneration. The discovery of alternative myogenic progenitors in skeletal muscle raises the question as to whether stem cells other than satellite cells accumulate in muscle in response to exercise and contribute to post-exercise repair and/or growth. In this study, stem cell antigen-1 (Sca-1) positive, non-hematopoetic (CD45-) cells were evaluated in wild type (WT) and α7 integrin transgenic (α7Tg) mouse muscle, which is resistant to injury yet liable to strain, 24 hr following a single bout of eccentric exercise. Sca-1+CD45− stem cells were increased 2-fold in WT muscle post-exercise. The α7 integrin regulated the presence of Sca-1+ cells, with expansion occurring in α7Tg muscle and minimal cells present in muscle lacking the α7 integrin. Sca-1+CD45− cells isolated from α7Tg muscle following exercise were characterized as mesenchymal-like stem cells (mMSCs), predominantly pericytes. In vitro multiaxial strain upregulated mMSC stem cells markers in the presence of laminin, but not gelatin, identifying a potential mechanistic basis for the accumulation of these cells in muscle following exercise. Transplantation of DiI-labeled mMSCs into WT muscle increased Pax7+ cells and facilitated formation of eMHC+DiI− fibers. This study provides the first demonstration that mMSCs rapidly appear in skeletal muscle in an α7 integrin dependent manner post-exercise, revealing an early event that may be necessary for effective repair and/or growth following exercise. The results from this study also support a role for the α7 integrin and/or mMSCs in molecular- and cellular-based therapeutic strategies that can effectively combat disuse muscle atrophy

Genetic variation and exercise-induced muscle damage: implications for athletic performance, injury and ageing.

Prolonged unaccustomed exercise involving muscle lengthening (eccentric) actions can result in ultrastructural muscle disruption, impaired excitation-contraction coupling, inflammation and muscle protein degradation. This process is associated with delayed onset muscle soreness and is referred to as exercise-induced muscle damage. Although a certain amount of muscle damage may be necessary for adaptation to occur, excessive damage or inadequate recovery from exercise-induced muscle damage can increase injury risk, particularly in older individuals, who experience more damage and require longer to recover from muscle damaging exercise than younger adults. Furthermore, it is apparent that inter-individual variation exists in the response to exercise-induced muscle damage, and there is evidence that genetic variability may play a key role. Although this area of research is in its infancy, certain gene variations, or polymorphisms have been associated with exercise-induced muscle damage (i.e. individuals with certain genotypes experience greater muscle damage, and require longer recovery, following strenuous exercise). These polymorphisms include ACTN3 (R577X, rs1815739), TNF (-308 G>A, rs1800629), IL6 (-174 G>C, rs1800795), and IGF2 (ApaI, 17200 G>A, rs680). Knowing how someone is likely to respond to a particular type of exercise could help coaches/practitioners individualise the exercise training of their athletes/patients, thus maximising recovery and adaptation, while reducing overload-associated injury risk. The purpose of this review is to provide a critical analysis of the literature concerning gene polymorphisms associated with exercise-induced muscle damage, both in young and older individuals, and to highlight the potential mechanisms underpinning these associations, thus providing a better understanding of exercise-induced muscle damage

Adherence of hip and knee arthroplasty studies to RSA standardization guidelines

Peer reviewe

The Effect of Heat Therapy on Skeletal Muscle Satellite Cell Content

Satellite cells are essential for proper muscle repair and adaptation. Studies have shown that exercise can lead to an increase in satellite cell content within muscle tissue. However, it is unknown whether other environmental stressors, such as heat, are also capable of augmenting the satellite cell pool. PURPOSE: The purpose of this study was to quantify changes in satellite cell content before and after 6-weeks (3x/wk) of skeletal muscle heat therapy (HT) or single leg knee extension exercise training (EX). Additionally, a sham heat treatment was used as a control. We hypothesized that HT would result in an increase in satellite cell content, though to a lesser extent than the EX group. METHODS: We randomized 28 sedentary but otherwise healthy, young adults (ages 18-36; n = 13 female, n = 15 male) to receive either HT (2 hr, 3 days/wk, 6-week period), EX (40 min, 3 days/wk, 6-week period), or sham heating sessions (CON; 2hr, 3 days/wk, 6-week period). The HT was administered through pulsed, shortwave diathermy. Muscle biopsies were taken from the vastus lateralis at baseline, after 3 weeks of intervention, and again after 6 weeks of intervention. RESULTS: For the Control Group, satellite cell count per mm2 at baseline = 8.107 (± 0.4799), at 3 weeks = 10.27 (± 0.911), at 6 weeks = 9.84 (± 0.675). For the EX Group, satellite cell count per mm2 at baseline = 9.705 (± 1.27), at 3 weeks = 10.87 (± 1.12), and at 6 weeks = 10.47 (±0.7997). For the HT Group, satellite cell count per mm2 at baseline = 8.535 (± 0.582), at 3 weeks = 11.54 (± 1.43), and at 6 weeks = 10.202 (± 0.940). Statistical analysis indicated a significant main effect of time (p=0.0125), but no significant effect of group (p=0.5504) or the group x time interaction (p=0.8412). CONCLUSION: Our findings suggest that 6 weeks of HT is insufficient to affect the satellite cell content within muscle fibers. This study provides additional insight in the literature about the effects of HT on human subjects

The Effect of Heat Therapy on Skeletal Muscle Satellite Cell Content

Satellite cells are essential for proper muscle repair and adaptation. Studies have shown that exercise can lead to an increase in satellite cell content within muscle tissue. However, it is unknown whether other environmental stressors, such as heat, are also capable of augmenting the satellite cell pool. PURPOSE: The purpose of this study was to quantify changes in satellite cell content before and after 6-weeks (3x/wk) of skeletal muscle heat therapy (HT) or single leg knee extension exercise training (EX). Additionally, a sham heat treatment was used as a control. We hypothesized that HT would result in an increase in satellite cell content, though to a lesser extent than the EX group. METHODS: We randomized 28 sedentary but otherwise healthy, young adults (ages 18-36; n = 13 female, n = 15 male) to receive either HT (2 hr, 3 days/wk, 6-week period), EX (40 min, 3 days/wk, 6-week period), or sham heating sessions (CON; 2hr, 3 days/wk, 6-week period). The HT was administered through pulsed, shortwave diathermy. Muscle biopsies were taken from the vastus lateralis at baseline, after 3 weeks of intervention, and again after 6 weeks of intervention. RESULTS: For the Control Group, satellite cell count per mm2 at baseline = 8.107 (± 0.4799), at 3 weeks = 10.27 (± 0.911), at 6 weeks = 9.84 (± 0.675). For the EX Group, satellite cell count per mm2 at baseline = 9.705 (± 1.27), at 3 weeks = 10.87 (± 1.12), and at 6 weeks = 10.47 (±0.7997). For the HT Group, satellite cell count per mm2 at baseline = 8.535 (± 0.582), at 3 weeks = 11.54 (± 1.43), and at 6 weeks = 10.202 (± 0.940). Statistical analysis indicated a significant main effect of time (p=0.0125), but no significant effect of group (p=0.5504) or the group x time interaction (p=0.8412). CONCLUSION: Our findings suggest that 6 weeks of HT is insufficient to affect the satellite cell content within muscle fibers. This study provides additional insight in the literature about the effects of HT on human subjects