The effects of short-term non-weightbearing and immobilization after anterior cruciate ligament reconstruction on articular cartilage: Long-term observation after reloading and remobilization.

Non-weightbearing or immobilization after anterior cruciate ligament (ACL) reconstruction accelerates cartilage degeneration. However, it is unclear whether these adverse effects are reversed by reloading or remobilization. Moreover, it is unknown whether the combination of non-weightbearing and immobilization after ACL reconstruction has synergistic effects on cartilage degeneration.

Does the timing of anterior cruciate ligament reconstruction surgery affect flexion contracture formation in rats?

Background: Anterior cruciate ligament injuries are commonly treated with ligament reconstruction surgery, but post-operative joint contracture is a major complication. The optimal timing for anterior cruciate ligament reconstruction remains controversial, with some clinical studies suggesting that early surgery may increase the risk of joint contractures, while others have found no such association. To clarify this, we investigated the effects of the timing of reconstruction surgery on contracture formation using a rat model.

Effects of sex differences on osteoarthritic changes after anterior cruciate ligament reconstruction in rats.

The prevalence of primary osteoarthritis is higher in females than males. However, it remains unclear if there are sex differences in the incidence of post-traumatic osteoarthritis after anterior cruciate ligament (ACL) reconstruction. In this study, we aimed to investigate the effects of sex on osteoarthritic changes after ACL reconstruction using an animal model.

Long-term effects of non-weight bearing and immobilization after anterior cruciate ligament reconstruction on joint contracture formation in rats.

Purpose: Non-weight bearing improves and immobilization worsens contracture induced by anterior cruciate ligament reconstruction (ACLR), but effect persistence after reloading and remobilization remains unclear, and the combined effects of these factors on ACLR-induced contracture are unknown. We aimed to determine 1) whether the effects of short-term (2-week) non-weight bearing or immobilization after ACLR on contracture would be sustained by reloading or remobilization during a 10-week observation period, and 2) how the combination of both interventions compared to the outcome of either alone.

Methods: We divided 88 ACL-reconstructed male rats into four groups: non-intervention, non-weight bearing, joint immobilization, and both interventions.

The Effects of Corticosteroid Administration and Treadmill Exercise on Marrow Adipose Tissue and Trabecular Bone after Anterior Cruciate Ligament Reconstruction in Rats.

We aimed to investigate the effects of short-term corticosteroid administration after anterior cruciate ligament (ACL) reconstruction on marrow adipose tissue (MAT) and trabecular bone mass, as well as to examine whether treadmill exercise can mitigate MAT increase and trabecular bone deterioration caused by corticosteroid. ACL-reconstructed rats were divided into groups: no intervention, daily treadmill exercise (60 min/day), administration of the steroidal drug dexamethasone (250 μg/kg on days 0-5, 7, and 9 post-operatively), or dexamethasone administration combined with treadmill exercise. Untreated rats were served as controls.

Effects of Weight Bearing on Marrow Adipose Tissue and Trabecular Bone after Anterior Cruciate Ligament Reconstruction in the Rat Proximal Tibial Epiphysis.

The effects of mechanical unloading after anterior cruciate ligament (ACL) reconstruction on bone and marrow adipose tissue (MAT) are unclear. We investigated weight bearing effects on bone and MAT after ACL reconstruction. Rats underwent unilateral knee ACL transection and reconstruction, followed by hindlimb unloading (non-weight bearing), no intervention (low-weight bearing, the hindlimb standing time ratio (STR; operated/contralateral) during treadmill locomotion ranging from 0.

The effects of weight bearing after ACL reconstruction on joint contracture in rats.

Purpose: Joint contractures after anterior cruciate ligament (ACL) reconstruction are a serious problem. Given the uncertain effects of weight bearing after ACL reconstruction on contractures, this study was conducted to examine such effects.

Materials And Methods: To control the amount of weight bearing, ACL-reconstructed rats were reared with either untreated (small weight bearing; weight bearing during locomotion was 54% of pre-surgery at minimum), hindlimb unloading (non-weight bearing), or sustained morphine administration (large weight bearing; weight bearing during locomotion was maintained at 80% or more of pre-surgery) conditions.

The effects of weight bearing on muscle atrophy early after ACL reconstruction in rats.

We examined the effects of weight bearing after anterior cruciate ligament (ACL) reconstruction on muscle atrophy in rats. Rats were divided into the following groups: untreated control, ACL reconstruction (amount of weight bearing was small), ACL reconstruction plus hindlimb unloading (nonweight bearing), and ACL reconstruction plus morphine administration (amount of weight bearing was large) groups. At 7 or 14 days after surgery, atrophy of the rectus femoris and gastrocnemius was assessed.

Changes in passive stiffness and length of the semitendinosus muscles in rats with arthritis-induced knee flexion contracture.

Background: Arthritis-induced joint contracture is caused by arthrogenic and myogenic factors. The arthrogenic factor, localized within the joint, is naturally accepted as the cause of contracture. However, the detailed mechanisms underlying arthritis-induced myogenic contracture are largely unknown.

The effects of immobilization duration on joint contracture formation after anterior cruciate ligament reconstruction in rats.

Background: Both myogenic and arthrogenic factors contribute to contracture formation after anterior cruciate ligament reconstruction surgery. However, effects of immobilization duration on myogenic and arthrogenic contractures after surgery are unknown. We examined the effects of immobilization duration on contracture formation.

Effects of joint immobilization and treadmill exercise on marrow adipose tissue and trabecular bone after anterior cruciate ligament reconstruction in the rat proximal tibial epiphysis.

Marrow adipose tissue (MAT) adversely affects bone metabolism under certain conditions. Although mechanical stress is an important factor in regulating MAT and bone mass, how stress from different rehabilitation protocols after anterior cruciate ligament (ACL) reconstruction affects trabecular bone and MAT is unclear. We aimed to examine the effects of joint immobilization and treadmill exercise on trabecular bone and MAT after ACL reconstruction.

The combined effects of treadmill exercise and steroid administration on anterior cruciate ligament reconstruction-induced joint contracture and muscle atrophy in rats.

Rehabilitation protocols to treat joint contracture and muscle atrophy following anterior cruciate ligament (ACL) reconstruction have not been established. In this study, we examined the combined effects of exercise therapy and steroid administration on joint contracture and muscle atrophy following ACL reconstruction. Rats received ACL transection and reconstructive surgery in one knee.

Mechanical properties within and beyond the physiological length of the semitendinosus muscle of knee-immobilized rats.

Background: The effects of immobilization on passive muscle mechanical properties are inconsistent between studies. Here, we investigated the mechanical properties of immobilized muscle by obtaining length-force curves within and beyond the physiological muscle-tendon length in a knee-contractured rat model.

Methods: Unilateral rat knee joints were immobilized using an external fixator for up to 21 days.

The effects of the amount of weight bearing on articular cartilage early after ACL reconstruction in rats.

Purpose: Osteoarthritis that develops after anterior cruciate ligament (ACL) reconstruction is a critical issue. We examined the effects of the amount of weight bearing early after ACL reconstruction on articular cartilage.

Materials And Methods: Rats were divided into groups according to the treatment received: untreated control, ACL reconstruction (ACLR), ACL reconstruction plus hindlimb unloading (ACLR + HU), and ACL reconstruction plus morphine administration (ACLR + M).

Effects of Joint Immobilization and Treadmill Exercise on Articular Cartilage After ACL Reconstruction in Rats.

Background: The development of osteoarthritis after anterior cruciate ligament (ACL) reconstruction (ACLR) is an important issue. However, the appropriate rehabilitation protocol to prevent cartilage degeneration due to postoperative osteoarthritis is unclear.

Purpose: To examine the effects of joint immobilization and treadmill exercise on articular cartilage after ACLR.

Conflicting time-dependent effects of treadmill exercise on joint contracture after anterior cruciate ligament reconstruction in rats.

We examined the time-dependent differences in the effects of treadmill exercise on joint contracture after anterior cruciate ligament (ACL) reconstruction. Rats received ACL reconstructive surgery. After surgery, rats were reared with or without treadmill exercise (60 min/day) starting at 3 days (when inflammatory reactions are active) or 14 days (when inflammatory reactions have subsided) post-surgery.

Bilateral muscle atrophy after anterior cruciate ligament reconstruction in rats: Protective effects of anti-inflammatory drug celecoxib.

Background: Muscle atrophy after anterior cruciate ligament (ACL) reconstruction occurs bilaterally and contributes to a decrease in muscle strength. However, effective treatment strategies for ACL reconstruction-induced muscle atrophy have not been established. We examined the effects of anti-inflammatory drug on muscle atrophy after ACL reconstruction.

Interactive effects of exercise and sleep on frailty severity in community-dwelling older adults: a cross-sectional study.

This study examined the effects of the interaction between exercise and sleep on frailty severity in community-dwelling older adults. This was a cross-sectional study. Data were collected in July 2019.

Effects of Each Phase of Anterior Cruciate Ligament Reconstruction Surgery on Joint Contracture in Rats.

Background: Although anterior cruciate ligament reconstruction surgery is known to cause joint contracture, the mechanisms of this process are unknown. We aimed to assess the effects of transection of this ligament and each phase of reconstruction surgery on contracture formation.

Materials And Methods: Rats were divided into groups according to treatment received: sham (arthrotomy), ligament transection, ligament transection plus bone drilling, and ligament reconstruction.

A rat model of hip joint contracture induced by mono-articular hip joint immobilization.

Background: To elucidate the formation process and therapeutic targets of hip flexion contracture, we developed a rat model of hip flexion contracture induced by hip mono-articular immobilization.

Methods: Kirschner wires inserted into the femur and hip bone were anchored at the hip in a flexed position in the immobilization groups and unanchored in the sham groups for up to four weeks. Age-matched untreated rats were used as controls.

The Natural History of Medial Meniscal Tears in the ACL Deficient and ACL Reconstructed Rat Knee.

Objective: The process of anterior cruciate ligament (ACL) injury-induced meniscal tear formation is not fully understood. Clinical studies have shown that ACL reconstruction (ACLR) reduces the development of secondary meniscal tears, but it is difficult to gain insight into the protective effects of ACLR from clinical studies alone. Using rat ACL transection (ACLT) and ACLR models, we aimed to reveal (1) the formation process of meniscal tears secondary to ACLT and (2) the protective effects of ACLR on secondary meniscal tears.

Formation process of joint contracture after anterior cruciate ligament reconstruction in rats.

Knee joint contracture is often induced by anterior cruciate ligament reconstruction (ACLR). However, the temporal and spatial arthrofibrotic changes following inflammatory events, which occur in parallel with the formation of joint contractures after ACLR, are unknown. This study aimed to reveal: (a) time-dependent changes in myogenic and arthrogenic contractures; and (b) the process of arthrofibrosis development after ACLR.

Morphological and biomechanical adaptations of skeletal muscle in the recovery phase after immobilization in a rat.

Background: Range of motion restriction following immobilization is spontaneously recovered at least in part by remobilization. However, the mechanisms underlying how muscles change with range of motion recovery are poorly understood. This study aimed to reveal morphological and biomechanical changes in the knee flexor semitendinosus muscle that contribute to knee joint contracture following the relief of immobilization.

Three-week joint immobilization increases anterior-posterior laxity without alterations in mechanical properties of the anterior cruciate ligament in the rat knee.

Background: Although knee immobilization may deteriorate the mechanical parameters of the anterior cruciate ligament, such as stiffness and failure strength, it is unknown whether it induces laxity in the whole joint. We examined the effects of immobilization on anterior-posterior joint laxity and mechanical properties of the anterior cruciate ligament, as well as histological and gene expression profiles of the joint capsule in rat knee joints.

Methods: Unilateral rat knees were immobilized using an external fixator.