Mechanical loading: potential preventive and therapeutic strategy for osteoarthritis

Finding the Goldilocks Zone of Mechanical Loading: A Comprehensive Review of Mechanical Loading in the Prevention and Treatment of Knee Osteoarthritis

In this review, we discuss the interaction of mechanical factors influencing knee osteoarthritis (KOA) and post-traumatic osteoarthritis (PTOA) pathogenesis. Emphasizing the importance of mechanotransduction within inflammatory responses, we discuss its capacity for being utilized and harnessed within the context of prevention and rehabilitation of osteoarthritis (OA). Additionally, we introduce a discussion on the Goldilocks zone, which describes the necessity of maintaining a balance of adequate, but not excessive mechanical loading to maintain proper knee joint health. Expanding beyond these, we synthesize findings from current literature that explore the biomechanical loading of various rehabilitation exercises, in hopes of aiding future recommendations for physicians managing KOA and PTOA and athletic training staff strategically planning athlete loads to mitigate the risk of joint injury. The integration of these concepts provides a multifactorial analysis of the contributing factors of KOA and PTOA, in order to spur further research and illuminate the potential of utilizing the body's own physiological responses to mechanical stimuli in the management of OA.

Ambulatory support moment contribution patterns and MRI-detected tibiofemoral and patellofemoral disease worsening in adults with knee osteoarthritis: A preliminary study

We investigated whether baseline sagittal-plane ankle, knee, and hip contribution to the total support moment (TSM) are each associated with baseline-to-2-year tibiofemoral and patellofemoral tissue damage worsening in adults with knee osteoarthritis. Ambulatory lower-limb kinetics were captured and computed. TSM is the sum of ankle, knee, and hip extensor moments at each instant during gait. Ankle, knee, and hip contributions to TSM were computed as joint moments divided by TSM, expressed as percentages. Participants underwent MRI of both knees at baseline and 2 years later. Logistic regression models assessed associations of baseline ankle contribution to TSM with baseline-to-2-year cartilage damage and bone marrow lesion worsening, adjusted for age, sex, BMI, gait speed, disease severity, and pain. We used similar analytic approaches for knee and hip contributions to TSM. Sample included 391 knees from 204 persons (age[SD]: 64[10] years; 76.5% women). Greater ankle contribution may be associated with increased odds of tibiofemoral cartilage damage worsening (OR = 2.38; 95% CI: 1.02-5.57) and decreased odds of patellofemoral bone marrow lesion worsening (OR = 0.14; 95% CI: 0.03-0.73). The ORs for greater knee contribution were in the protective range for tibiofemoral compartment and in the deleterious range for patellofemoral. Greater hip contribution may be associated with increased odds of tibiofemoral worsening (OR = 2.71; 95% CI: 1.17-6.30). Greater ankle contribution to TSM may be associated with baseline-to-2-year tibiofemoral worsening, but patellofemoral tissue preservation. Conversely, greater knee contribution may be associated with patellofemoral worsening, but tibiofemoral preservation. Preliminary findings illustrate potential challenges in developing biomechanical interventions beneficial to both tibiofemoral and patellofemoral compartments.

Potential influences on optimizing long-term musculoskeletal health in children and adolescents with X-linked hypophosphatemia (XLH)

In recent years, much progress has been made in understanding the mechanisms of bone growth and development over a lifespan, including the crosstalk between muscle and bone, to achieve optimal structure and function. While there have been significant advances in understanding how to help improve and maintain bone health in normal individuals, there is limited knowledge on whether these mechanisms apply or are compromised in pathological states. X-linked hypophosphatemia (XLH) (ORPHA:89936) is a rare, heritable, renal phosphate-wasting disorder. The resultant chronic hypophosphatemia leads to progressive deterioration in musculoskeletal function, including impaired growth, rickets, and limb deformities in children, as well as lifelong osteomalacia with reduced bone quality and impaired muscle structure and function. The clinical manifestations of the disease vary both in presentation and severity in affected individuals, and many of the consequences of childhood defects persist into adulthood, causing significant morbidity that impacts physical function and quality of life. Intervention to restore phosphate levels early in life during the critical stages of skeletal development in children with XLH could optimize growth and may prevent or reduce bone deformities in childhood. A healthier bone structure, together with improved muscle function, can lead to physical activity enhancing musculoskeletal health throughout life. In adults, continued management may help to maintain the positive effects acquired from childhood treatment, thereby slowing or halting disease progression. In this review, we summarize the opinions from members of a working group with expertise in pediatrics, epidemiology, and bone, joint and muscle biology, on potential outcomes for people with XLH, who have been optimally treated from an early age and continue treatment throughout life.

Analgesic Effects of Two Types of Spinal Manipulation in Acute Lumbar Radiculopathy Model Rats

OBJECTIVE

To compare the analgesic effects of two types of spinal manipulation (SM) in acute lumbar radiculopathy (ALR) model rats induced by self-transplantation of autologous nucleus pulposus (ANP), and clarify the therapeutic mechanism.

METHODS

Totally 108 male Sprague-Dawley rats were randomly divided into 6 groups by a random number table (18 rats in each group), including a blank group with no interference, a sham operation group with a surgery by making a local soft tissue incision on the left side of L5-6 vertebral segment, a model group with ALR of L5 extraforaminal nerve by ANP self-transplantation without other interference, a sham manipulation (SMA) group with simulating physical rotation, as well as a mobilization (MOB) group with simulating low-velocity and variable-amplitude rotation and a manipulation (MAN) group with simulating high-velocity and low-amplitude rotation. The interventions in SMA, MOB, and MAN groups started 1 day after modeling followed by another 5 treatments at days 3, 5, 8, 10 and 12. Rats in the other 3 groups did not receive any special intervention. Behavioral pain tests of 50% mechanical pain withdrawal threshold (50% PWT) and paw withdrawal latency (PWL) were conducted 1 day before operation followed by another 10 tests on days 1-7, 10, 12 and 14. Immunohistochemical expression of nitric oxide synthase (NOS) was investigated on days 5 and 12 after operation.

RESULTS

After 3 experimental SM interventions, 50% PWT and PWL were higher in the MAN group than the SMA group on days 6 and 7, and higher on days 10, 12 and 14 postoperatively (P<0.05 or P<0.01), while the same indices were significantly higher in the MOB group than MAN group on days 1-4 (P<0.05 or P<0.01). The expression of NOS was lower in the MAN and MOB groups than SMA group on day 12 postoperatively (P<0.01).

CONCLUSIONS

Both manipulation and mobilization produced better results than sham interference in relieving pain by reducing neuroinflammation possibly. At the early period, compared with manipulation, mobilization presented less sensitive response to pain until later visit. SM may inhibit the overexpression of NOS, thereby alleviating severe radiculopathy.

Translational relevance of the goat as a preclinical model of the human labrum and chondrolabral junction-histological study

The purpose of this study was to evaluate the histologic features of the caprine labrum, with emphasis on the chondrolabral junction, with the goal of informing the feasibility of the goat as an animal model. The left hip joint of six adolescent Spanish goats (Capra pyrenaica) was harvested and subjected to anatomical and histological assessments. Human acetabular and femoral head samples, collected during total hip arthroplasty, served as comparison samples. The caprine labrum was found to consist of mostly type I collagen with uniform crimp, with an average crimp length of 20.8 µm. Upon histological assessment, acetabular articular chondrocytes were found to express substance-P, especially near or in the chondrolabral junction. And the majority of nonvascular cells expressed α-smooth muscle actin (SMA), with no notable elastin and laminin expression. Human labrum demonstrated similar staining patterns. Overall, the goat hip was found to be homologous to the human hip, demonstrating potential as a useful animal model for future studies. This is the first report of a crimped collagen structure in the labrum. Crimped type I collagen at the chondrolabral junction imparts an extension-recovery property which allows for toleration of stress without permanent deformation, underlying the importance of its preservation during surgery. The high expression of substance-P reflects the degree to which the labrum is innervated. Finally, the expression of α-SMA with contractile characteristics could indicate the potential for chondrocyte (i.e., myochondrocytes) modeling of the extracellular matrix. Statement of Clinical Significance: Establishment of a large animal model and deeper knowledge of the histological composition of the hip joint will enhance our study of the acetabular labrum, including repair techniques. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1070-1080, 2020.

Effect of Acupotomy on FAK-PI3K Signaling Pathways in KOA Rabbit Articular Cartilages

Objective

By observing the needle-knife of KOA rabbit morphology, knee joint cartilage p-FAK, p-PI3K, Aggrecan gene, and protein expression, to study the effect of needle-knife to promote cartilage cell synthesis metabolism mechanism.

Method

49 male New Zealand rabbits, randomly divided into normal group (Z), model group (M), model-inhibitors (MP), needle-knife group (D), needle-knife inhibitors group (DP), electroacupuncture group (E), and electroacupuncture inhibitors (EP). RT-PCR and Western Blot were used to test each animal cartilage p-FAK, p-PI3K, and Aggrecan gene and protein expression level.

Results

Compared with N group, p-FAK and p-PI3K protein and mRNA expression of M group, D group, and E group increased (P < 0.05), while the protein and mRNA expression of Aggrecan reduced (P < 0.05). Compared with M group, p-FAK, p-PI3K, Aggrecan protein, and mRNA of E and D group increased (P < 0.05). Compared with E group, p-FAK, p-PI3K, Aggrecan protein, and mRNA expression of D group increased (P < 0.05); after adding inhibitors, p-FAK, p-PI3K, Aggrecan protein, and mRNA expression reduced (P < 0.05).

Conclusion

Needle-knife therapy can promote the repairment of cartilage cells by activating FAK-PI3K signaling pathways, promoting the synthesis of cartilage cell metabolism.