Clinical-like cryotherapy improves footprint patterns and reduces synovial inflammation in a rat model of post-traumatic knee osteoarthritis

Abstract

Cryotherapy is a non-pharmacological treatment commonly used to control inflammation and improve function after acute traumas. However, there are no definitive findings about its effects on chronic joint diseases such as knee osteoarthritis (KOA). The aim of this study was to investigate the effects of clinical-like cryotherapy on functional impairment and synovial inflammation in a rat model of KOA generated by anterior cruciate ligament transection (ACLT). Thirty-two male Wistar rats were randomly divided into four groups (n = 8/group): Control, KOA, KOA + Cryotherapy and KOA + Placebo. The last two groups were submitted to the relevant interventions twice a day for five days (61 to 65), with each session lasting 20 min. Gait test, skin temperature, thermal response threshold and joint swelling were assessed in all groups before ACLT surgery, and pre (60th day) and post (66th day) intervention protocols. On day 66, the animals were euthanized and exsanguinated to remove the synovial membrane for histopathological examination and synovial fluid to determine the leukocyte count and cytokine concentration. After the intervention period (66th day), footprint area only increased in the KOA + Cryotherapy group (P = 0.004; 14%) when compared to KOA and KOA + Placebo, but did not differ from controls. Cryotherapy lowered the synovial fluid leukocyte count (P < 0.0001; ≥95.0%) and cytokine concentration (P < 0.0001; ≥55%) when compared to the KOA and Placebo groups. Synovial score and synovial fibrosis did not differ in the KOA groups. In conclusion, footprint patterns improved in rats with ACLT-induced KOA as a result of clinical-like cryotherapy, which also lowered the synovial fluid leukocyte count and inflammatory cytokine concentration in these rats.

Post-traumatic osteoarthritis following ACL injury

“…Using p16-3MR transgenic mice, Jeon et al [41] demonstrated that selective removal of senescent cells retards OA progression, reduces pain, and creates a pro-regenerative environment. Nonpharmacological treatments such as cryotherapy improve footprint patterns and reduce synovial inflammation [42]. Weight loss is often recommended in treatment programs, as it decreases joint loading and IL-7 levels through biomechanical and inflammatory pathways [11].…”

Clinical-Like Cryotherapy in Acute Knee Arthritis Protects Neuromuscular Junctions of Quadriceps and Reduces Joint Inflammation in Mice

“…Clinical-like cryotherapy reduced signs of joint inflammation in a mouse model of KOA, decreasing the number of leukocytes and levels of cytokines in the synovial fluid [ 14 ]. In a previous study by Castro et al [ 16 ], clinical-like cryotherapy in a mouse model of acute knee arthritis also showed decreased inflammatory signs of joint swelling, neutrophil migration, and levels of cytokines IL-6, IL-1 β , and TNF- α in the synovial fluid [ 16 ].…”

“…Tibiofemoral joint thickness (in mm) was measured two hours after the second clinical-like cryotherapy session and under anesthesia (O 2 2 L/m, 2% isoflurane) using an electronic digital caliper (Digimatic ABSOLUTE 150 mm, Mitutoyo, Japan). The mean of three measures was included in the data analysis [ 14 , 15 , 19 ].…”

Clinical-like cryotherapy in acute arthritis of the knee improves inflammation signs, pain, joint swelling and motor performance in mice

“…Studying the possible effects of cryotherapy in an arthritis model may be useful for clinical practice. The ice pack was considered a welltolerated modality of therapy (7), and it was effective to ameliorate joint and muscle damage in chronic models of transection of the anterior cruciate ligament (8).…”