Histopathological Changes of Joint Capsule after Joint Immobility Compared with Aging in Rats

Effects of Neuromuscular Electrical Stimulation and Therapeutic Ultrasound on Quadriceps Contracture of Immobilized Rats

Quadriceps contracture is a condition where the muscle-tendon unit is abnormally shortened. The treatment prognosis is guarded to poor depending on the progress of the disease. To improve the prognosis, we investigated the effectiveness of therapeutic ultrasound and NMES in treating quadriceps contracture in an immobilized rat model. Thirty-six Wistar rats were randomized into control, immobilization alone, immobilization and spontaneous recovery, immobilization and therapeutic ultrasound, immobilization and NMES, and immobilization and therapeutic ultrasound and NMES combination groups. The continuous therapeutic ultrasound (frequency, 3 MHz, intensity 1 W/cm2) and NMES (TENS mode, frequency 50 Hz; intensity 5.0 ± 0.8 mA) were performed on the quadriceps muscle. On Day 15, immobilization-induced quadriceps contracture resulted in a decreased ROM of the stifle joint, reduction in the sarcomere length, muscle atrophy, and muscle fibrosis. On Day 43, therapeutic ultrasound, NMES, and combining both methods improved muscle atrophy and shortening and decreased collagen type I and III and α-SMA protein. The combination of therapeutic ultrasound and NMES significantly reduced the mRNA expression of IL-1β, TGF-β1, and HIF-1α and increased TGF-β3. Therefore, the combination of therapeutic ultrasound and NMES is the most potent rehabilitation program for treating quadriceps contracture.

Development of a novel knee contracture mouse model by immobilization using external fixation

AIMS

Several studies have used animal models to examine knee joint contracture; however, few reports detail the construction process of a knee joint contracture model in a mouse. The use of mouse models is beneficial, as genetically modified mice can be used to investigate the pathogenesis of joint contracture. Compared to others, mouse models are associated with a lower cost to evaluate therapeutic effects. Here, we describe a novel knee contracture mouse model by immobilization using external fixation.

METHODS

The knee joints of mice were immobilized by external fixation using a splint and tape. The passive extension range of motion (ROM), histological and immunohistochemical changes, and expression levels of fibrosis-related genes at 2 and 4 weeks were compared between the immobilized (Im group) and non-immobilized (Non-Im group) groups.

RESULTS

The extension ROM at 4 weeks was significantly lower in the Im group than in the Non-Im group (p < 0.01). At 2 and 4 weeks, the thickness and area of the joint capsule were significantly greater in the Im group than in the Non-Im group (p < 0.01 in all cases). At 2 weeks, the mRNA expression levels of the fibrosis-related genes, except for the transforming growth factor-β1, and the protein levels of cellular communication network factor 2 and vimentin in the joint capsule were significantly higher in the Im group (p < 0.01 in all cases).

CONCLUSION

This mouse model may serve as a useful tool to investigate the etiology of joint contracture and establish new treatment methods.

Effect of metformin treatment and its time of administration on joint capsular fibrosis induced by mouse knee immobilization

Joint contracture leads to major patient discomfort. Metformin, one of the most extensively used oral drugs against type 2 diabetes has recently been found to suppress tissue fibrosis as well. However, its role in suppressing tissue fibrosis in joint contractures remains unknown. In this study, we examined the role of metformin treatment in suppressing joint capsular fibrosis and the most effective time of its administration. Joint capsular fibrosis was induced by immobilizing the knee joints of mice using splints and tapes. Metformin was administered intraperitoneally every alternate day after immobilization. Histological and immunohistochemical changes and expression of fibrosis-related genes were evaluated. Metformin treatment significantly suppressed fibrosis in joint capsules based on histological and immunohistochemical evaluation. Joint capsular tissue from metformin-treated mice also showed decreased expression of fibrosis-related genes. Early, but not late, metformin administration showed the same effect on fibrosis suppression in joint capsule as the whole treatment period. The expression of fibrosis-related genes was most suppressed in mice administered with metformin early. These studies demonstrated that metformin treatment can suppress joint capsular fibrosis and the most effective time to administer it is early after joint immobilization; a delay of more than 2 weeks of administration is less effective.

Effect of low-intensity pulsed ultrasound therapy on a rat knee joint contracture model

[Purpose] Histopathological investigation of the effects of low-intensity pulsed ultrasound (LIPUS) on joint components using a rat knee joint contracture model. [Subjects and Methods] Nineteen, 9-week-old Wistar male rats were divided into a control group (n=6) and an experimental group. Rats in the experimental group underwent cast immobilization of the right rear limb for 8 weeks. They were then randomly divided into a non-treatment group (n=6), which was raised under normal conditions for 4 weeks, and a treatment group (n=7), which underwent LIPUS for 4 weeks. LIPUS irradiation was performed at a frequency of 3 MHz, an intensity of 30 mW/cm², and a pulse rate of 20% duty cycle. Irradiation was performed once daily for 10 min, 5 days per week. At the end of this period, tissue specimens in which the knee sagittal plane could be observed were prepared and observed using an optical microscope. [Results] The extension-limiting angle of the knee joint was significantly less in the treatment group compared with the non-treatment group. The posterior joint capsule was significantly thicker only in the non-treatment group, and the density was 53.5 ± 7.5% for the control group, 77.2 ± 5.7% for the non-treatment group, and 69.2 ± 2.9% for the treatment group, with significant differences existing across all groups. [Conclusion] LIPUS may widen the space between collagen fiber bundles of the joint capsule, thereby improving the range of motion.

Long-term histopathological developments in knee-joint components in a rat model of osteoarthritis induced by monosodium iodoacetate

[Purpose] This study was performed to evaluate the long-term histopathological changes in knee-joint components including synovial membrane and joint capsule in a rat model of osteoarthritis (OA) induced by monosodium iodoacetate (MIA). [Subjects and Methods] Fifty male rats were used. OA was induced through intra-articular injection of MIA, and ten rats were randomly allocated to each of five groups induced with OA for 1, 2, 4, 6, or 8 weeks. At the end of each period, the knee components were examined histopathologically. [Results] After 1 and 2 weeks, chondrocytes were weakly stained. After 4 weeks, fibrillation, fissuring, and eburnation were observed, whereas after 6 weeks, chondrocyte clustering and osteophyte formation were detected. In the synovial membrane, the proliferation of spindle-shaped cells and a multilayered structure of the surface cells were observed at 1 and 2 weeks, but the degree of these changes decreased over time. In the joint capsule, a narrowing of the space between collagen fiber bundles was observed at 4–8 weeks. [Conclusion] The long-term histopathological changes of the joint components observed in a rat model of OA induced by MIA were similar to those detected in OA, but differed at specific times and tissues.

Impact of shoulder internal rotation on ulnar nerve excursion and strain in embalmed cadavers. A pilot study

DESIGN

Laboratory study, repeated-measures design.

OBJECTIVE

To determine if the substitution of shoulder internal rotation for external rotation during the upper limb neurodynamic test (ULNT3) evokes a comparable ulnar nerve excursion and strain in embalmed cadavers. Shoulder external rotation is a primary movement component of the ULNT3. It has been suggested that shoulder internal rotation may provide a similar load to the nervous system. There are no data to either support or negate this claim.

METHODS

Excursion and strain were measured in the ulnar nerve of six embalmed cadavers during the traditional ULNT3 and an experimental maneuver using shoulder internal rotation.

RESULTS

The total means±SD of excursion for the traditional and experimental maneuvers were 2·11±0·89 and 2·09±0·92 mm, respectively. The total means±SD of strain for the traditional and experimental maneuvers were 5·274±2·223 and 5·241±2·308%, respectively. A very strong correlation (r = 0·98) was shown to exist between maneuvers and this relationship was determined to be significant (P = 0·001).

DISCUSSION

The results of this study provide evidence that there is no appreciable difference in excursion or strain when substituting shoulder internal rotation for external rotation during the ULNT3. Patients who exhibit limitation of shoulder external rotation mobility may benefit from this substitution when presenting with signs of ulnar nerve pathodynamics. Further research involving patients will be needed to assess the validity of the experimental maneuver for clinical application.

Influence of ROM Exercise on the Joint Components during Immobilization

[Purpose] The aim of this study was to clarify the effects of the ROM exercise on joint components according to histopathological analysis. [Subjects and Methods] In total, twenty-six 9-week-old adult male Wistar rats were used in this study. The rats were randomly divided into three groups, the immobilization group (n=10), exercise group (n=10), and control group (n=6). The immobilization group and exercise group were anaesthetized and operated on under sterile conditions. The right knee joints in the immobilization group and exercise group were immobilized with external fixation at 120 degrees of flexion. Range of motion exercise was started from the day after immobilization. ROM exercise was performed in the exercise group once a day for 3 minutes, 6 days a week, for 2 weeks. [Result] The joint capsule in the immobilization group and exercise group showed narrowing of the collagen bundles in interstitial spaces but was less dense in the control group. In the immobilized group, a hyperplastic reaction was associated with infiltration into the articular cavity and adhesion to the surface of the articular cartilage. Conversely, in the exercise group, hyperplasia of tissue was localized to the synovial membrane. [Conclusion] This finding may suggest that ROM exercise induces some changes within the joint components and tissue metabolism.