Association of early physical activity time with pain, activities of daily living, and progression of vertebral body collapse in patients with vertebral compression fractures.

BACKGROUND: Physical activity can reduce pain and improve the ability to perform daily activities in patients with acute low back pain (LBP) due to various non-specific causes. The association between physical activity during the early phase of acute vertebral compression fractures (VCFs) and rehabilitation outcomes is unknown. AIM: The aim of this study was to investigate the effects of early physical activity time (EPAT) on pain following acute VCFs, recovery of the ability to perform activities of daily living (ADLs), and progression of fractured vertebral body collapse. DESIGN: Observational study. SETTING: Inpatient clinic. POPULATION: Sixty-nine patients with acute VCFs being treated conservatively at Nagasaki Memorial Hospital. METHODS: Physical activity was evaluated as the activity time corresponding to 1.8-8.3 metabolic equivalent activities measured by a motion-sensor during the first week after admission; it was defined as EPAT. The verbal rating scale (VRS) (0-4) at rest and during standing and walking and motor functional independence measure (mFIM) were assessed at weeks 0 (baseline), 2, and 4. Loss of vertebral height was measured in week 4. Mini-mental state examinations, trail making test part-A (TMT-A), and geriatric depression scale-15 were administered at baseline. Patients were divided into active (N.=35) and sedentary (N.=34) groups according to their median EPAT value during the first week. RESULTS: The completion times for TMT-A and mFIM scores at baseline as well as the relative functional gains of mFIM from baseline to week 2 or 4 were significantly associated with EPAT. VRS at rest and during standing and walking were not significantly different between the groups at week 2 and 4. Loss of vertebral height was not significantly different between the groups. CONCLUSIONS: EPAT in patients with acute VCF is associated with the recovery of the ability to perform ADLs. However, EPAT is associated with neither pain reduction nor progression of fractured vertebral body collapse. CLINICAL REHABILITATION IMPACT: This observational study indicates that physical activity in the early acute phase of VCF is associated with better recovery from acute VCF and would be an important factor for short-term recovery.

Immobilization-induced hypersensitivity associated with spinal cord sensitization during cast immobilization and after cast removal in rats.

This study examined mechanical and thermal hypersensitivity in the rat hind paw during cast immobilization of the hind limbs for 4 or 8 weeks and following cast removal. Blood flow, skin temperature, and volume of the rat hind paw were assessed in order to determine peripheral circulation of the hind limbs. Sensitization was analyzed by measuring the expression of the calcitonin gene-related peptide (CGRP) in the spinal dorsal horn following cast immobilization. Two weeks post immobilization, mechanical and thermal sensitivities increased significantly in all rats; however, peripheral circulation was not affected by immobilization. Cast immobilization for 8 weeks induced more serious hypersensitivity compared to cast immobilization for 4 weeks. Moreover, CGRP expression in the deeper lamina layer of the spinal dorsal horn increased in the rats immobilized for 8 weeks but not in those immobilized for 4 weeks. These findings suggest that immobilization-induced hypersensitivity develops during the immobilization period without affecting peripheral circulation. Our results also highlight the possibility that prolonged immobilization induces central sensitization in the spinal cord.

Low-level laser irradiation promotes the recovery of atrophied gastrocnemius skeletal muscle in rats.

Low-level laser (LLL) irradiation promotes proliferation of muscle satellite cells, angiogenesis and expression of growth factors. Satellite cells, angiogenesis and growth factors play important roles in the regeneration of muscle. The objective of this study was to examine the effect of LLL irradiation on rat gastrocnemius muscle recovering from disuse muscle atrophy. Eight-week-old rats were subjected to hindlimb suspension for 2 weeks, after which they were released and recovered. During the recovery period, rats underwent daily LLL irradiation (Ga-Al-As laser; 830 nm; 60 mW; total, 180 s) to the right gastrocnemius muscle through the skin. The untreated left gastrocnemius muscle served as the control. In conjunction with LLL irradiation, 5-bromo-2-deoxyuridine (BrdU) was injected subcutaneously to label the nuclei of proliferating cells. After 2 weeks, myofibre diameters of irradiated muscle increased in comparison with those of untreated muscle, but did not recover back to normal levels. Additionally, in the superficial region of the irradiated muscle, the number of capillaries and fibroblast growth factor levels exhibited significant elevation relative to those of untreated muscle. In the deep region of irradiated muscle, BrdU-positive nuclei of satellite cells and/or myofibres increased significantly relative to those of the untreated muscle. The results of this study suggest that LLL irradiation can promote recovery from disuse muscle atrophy in association with proliferation of satellite cells and angiogenesis.