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

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. Interventions were performed for 2 weeks, followed by rearing without intervention. Twelve untreated rats were used as controls. At 2, 4, and 12 weeks post-surgery, we assessed range of motion (ROM) and histological changes.

RESULTS

ACLR resulted in persistent loss of ROM, accompanied by synovial shortening, capsule thickening, and osteophyte formation. Two weeks of non-weight bearing increased ROM and reduced osteophyte size, but the beneficial effects disappeared within 10 weeks after reloading. Two-week immobilization decreased ROM and facilitated synovial shortening. After remobilization, ROM partially recovered but remained below non-intervention levels at 12 weeks. When both interventions were combined, ROM was similar to immobilization alone.

CONCLUSIONS

The beneficial effects of 2-week non-weight bearing on contracture diminished within 10 weeks after reloading. The adverse effects of 2-week immobilization on contracture persisted after 10 weeks of remobilization. The effects of the combined use of both interventions on contracture were primarily determined by immobilization.

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. Untreated rats were used as controls. Knee extension range of motions (ROMs) before (includes myogenic and arthrogenic factors) and after myotomy (includes arthrogenic factor only) and fibrotic reactions in the joint capsule were assessed 7 and 14 days post-surgery.

RESULTS

ACL reconstruction significantly reduced ROMs both before and after myotomy and induced fibrosis in the joint capsule accompanying upregulation of fibrosis-related genes (i.e., type I and III collagens and transforming growth factor-β1) at both time points. Morphine administration increased the ROM before myotomy, but not after myotomy 7 days post-surgery. Unloading after ACL reconstruction improved ROMs both before and after myotomy at both time points. In addition, unloading after ACL reconstruction attenuated fibrotic reactions in the joint capsule.

CONCLUSIONS

Our results suggest that morphine administration improves myogenic contractures in parallel with an increase in the amount of weight bearing. Unloading after ACL reconstruction is effective in reducing both myogenic and arthrogenic contractures.

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). ACL reconstruction was performed on the right knee throughout the groups. To assess the amount of weight bearing, one-hindlimb standing time ratio (STR; operated side/contralateral side) during treadmill locomotion was evaluated during the experimental period. At day 7 or 14 post-surgery, cartilage degeneration of the medial tibial plateau was histologically assessed.

RESULTS

In the ACLR group, reduction in weight bearing characterized by significantly reduced STR was observed between day 1 and 7. Reduction in weight bearing was partially attenuated by morphine administration. Compared with the control group, the ACLR group exhibited an increased Mankin score that was accompanied by increased cyclooxygenase-2 expression in the anterior region. In the ACLR + HU group, Mankin scores were significantly higher in the middle and posterior regions, and cartilage thickness in these regions was significantly thinner than those in the ACLR group. In the ACLR + M group, although chondrocyte density in the anterior region was increased, all other parameters were not significantly different from those in the ACLR group.

CONCLUSIONS

Our results suggest that early weight bearing after ACL reconstruction is important to reduce cartilage degeneration.

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.

METHODS

Rats were divided into groups according to treatment received: untreated control, knee immobilization, anterior cruciate ligament reconstruction, and anterior cruciate ligament reconstruction plus immobilization. Extension range of motion before and after myotomy as well as histomorphological knee changes were assessed two or four weeks after experiment commencement. Range of motion before myotomy mainly represents contractures due to myogenic factors. Range of motion after myotomy represents arthrogenic factors.

FINDINGS

Range of motion before and after myotomy was decreased in the immobilization, reconstruction, and reconstruction plus immobilization groups at both timepoints. In the reconstruction plus immobilization group, range of motion before and after myotomy was significantly smaller than in the immobilization and reconstruction groups. Shortening and thickening of the posterior joint capsule was induced in the immobilization and reconstruction groups. In the reconstruction plus immobilization group, capsule shortening was facilitated via adhesion formation, as compared to the immobilization and reconstruction groups.

INTERPRETATION

Our results indicate that immobilization after anterior cruciate ligament reconstruction surgery facilitates contracture formation via exacerbation of both myogenic and arthrogenic contractures within two weeks. Capsule shortening would be one of the main mechanisms for severe arthrogenic contracture observed in the reconstruction plus immobilization group. Periods of joint immobilization after surgery should be minimized to reduce contracture.

Low-level laser therapy attenuates arthrogenic contracture induced by anterior cruciate ligament reconstruction surgery in rats

Therapeutic approaches to treat joint contracture after anterior cruciate ligament (ACL) reconstruction have not been established. Arthrofibrosis accompanied by joint inflammation following ACL reconstruction is a major cause of arthrogenic contracture. In this study, we examined whether anti-inflammatory treatment using low-level laser therapy (LLLT) can prevent ACL reconstruction-induced arthrogenic contracture. Rats underwent ACL transection and reconstruction surgery in their right knees. Unoperated left knees were used as controls. After surgery, rats were reared with or without daily LLLT (wavelength: 830 nm; power output: 150 mW; power density: 5 W/cm2; for 120 s/day). We assessed the passive extension range of motion (ROM) after myotomy at one and two weeks post-surgery; the reduction in ROM represents the severity of arthrogenic contracture. ROM was markedly decreased by ACL reconstruction at both time points; however, LLLT partially attenuated the decrease in ROM. One week after ACL reconstruction, the gene expression of the proinflammatory cytokine interleukin-1beta in the joint capsule was significantly upregulated, and this upregulation was significantly attenuated by LLLT. Fibrotic changes in the joint capsule, including upregulation of collagen type I and III genes, shortening of the synovium, and thickening were caused by ACL reconstruction and seen at both time points. LLLT attenuated these fibrotic changes as well. Our results indicate that LLLT after ACL reconstruction could attenuate the formation of arthrogenic contracture through inhibition of inflammation and fibrosis in the joint capsule. Thus, LLLT may become a novel therapeutic approach for ACL reconstruction-induced joint contracture.

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.

MATERIALS AND METHODS

Rats were divided into groups according to treatment received: untreated control (n = 4), arthrotomy (n = 6), ACL transection (n = 7), ACL reconstruction (n = 8), and ACL reconstruction plus anti-inflammatory drug celecoxib (CBX; 50 mg/kg/day) administration (n = 8). At one-week post-surgery, the muscle fiber cross-sectional area (CSA) in the rectus femoris (RF) and semitendinosus (ST) was measured to assess muscle atrophy. In addition, we examined joint swelling and serum C‑reactive protein (CRP) levels to assess local and systemic inflammation, respectively.

RESULTS

Each additional procedure (i.e., arthrotomy, ACL transection, and ACL reconstruction) gradually decreased the muscle fiber CSAs in the RF and ST on both operated and contralateral sides. The degree of muscle fiber atrophy on the operated side was larger than that detected on the contralateral side. Moreover, ACL reconstruction induced joint swelling on the operated side and tended to increase serum CRP levels. CBX lessened the RF atrophy on both sides and was associated with less joint swelling and a smaller increase CRP level; however, it did not affect ST atrophy on either side.

CONCLUSIONS

Anti-inflammatory treatments after ACL reconstruction may be effective in lessening muscle atrophy in the quadriceps, but not in the hamstrings.