This in vivo study aimed at investigating the effects of dynamic compression on the growth plate. Rats (28 days old) were divided into three dynamically loaded groups, compared with two groups (control, sham). A device was implanted on the 6th and 8th caudal vertebrae for 15 days. Controls (n ¼ 4) did not undergo surgery. Shams (n ¼ 4) were operated but not loaded. Dynamic groups had sinusoidal compression with a mean value of 0.2 MPa: 1.0 Hz and AE0.06 MPa (group a, n ¼ 4); 0.1 Hz and AE0.2 MPa (group b, n ¼ 4); 1.0 Hz and AE0.14 MPa (group c, n ¼ 3). Growth rates (mm/day) of dynamic groups (a) and (b) were lower than shams (p < 0.01). Growth plate heights, hypertrophic cell heights and proliferative cell counts per column did not change in dynamic (a) and (b) groups compared with shams (p > 0.01). Rats from dynamic group (c) had repeated inflammations damaging tissues; consequently, their analysis was unachievable. Increasing magnitude or frequency leads to growth reduction without histomorphometric changes. However, the combined augmentation of magnitude and frequency alter drastically growth plate integrity. Appropriate loading parameters could be leveraged for developing novel growth modulation implants to treat skeletal deformities. ß
Recent findings suggest that vertebral osteophytes increase the resistance of the spine to compression. However, the role of vertebral osteophytes on the biomechanical response of the spine under fast dynamic compression, up to failure, is unclear. Seventeen human spine specimens composed of three vertebrae (from T5-T7 to T11-L1) and their surrounding soft tissues were harvested from nine cadavers, aged 77 to 92 years. Specimens were imaged using quantitative computer tomography (QCT) for medical observation, classification of the intervertebral disc degeneration (Thomson grade) and measurement of the vertebral trabecular density (VTD), height and cross-sectional area. Specimens were divided into two groups (with (n = 9) or without (n = 8) substantial vertebral body osteophytes) and compressed axially at a dynamic displacement rate of 1 m/s, up to failure. Normalized force-displacement curves, videos and QCT images allowed characterizing failure parameters (force, displacement and energy at failure) and fracture patterns. Results were analyzed using chi-squared tests for sampling distributions and linear regression for correlations between VTD and failure parameters. Specimens with substantial vertebral body osteophytes present higher stiffness (2.7 times on average) and force at failure (1.8 times on average) than other segments. The presence of osteophytes significantly influences the location, pattern and type of fracture. VTD was a good predictor of the dynamic force and energy at failure for specimens without substantial osteophytes. This study also showed that vertebral body osteophytes provide a protective mechanism to the underlying vertebra against severe compression fractures.
This literature review investigated the subtle cavovarus foot with a search in Pubmed and Google Scholar using the following keywords: Subtle cavovarus foot, cavovarus foot or cavus foot and one or more of the following: Associations, injuries, ankle sprains, ankle instability, sports, plantar pressure, dynamic pedobarography, Tekscan and footprint, from January 1980 to February 2019. Subtle cavovarus foot can alter foot and ankle biomechanics but reference values are lacking for dynamic pedobarography assessment. Subtle cavovarus foot is associated with peroneal tendinopathy, metatarsal stress fractures, and recurrent lateral ankle sprains, potentially leading to chronic ankle instability due to altered walking central control patterns. Treatment includes flexible/semi-rigid orthotics to laterally offload the foot, or surgery in rigid cases. Subtle cavovarus foot is associated with chronic foot and ankle pathologies. Unfortunately, diagnosis is often difficult or delayed. Early conservative management, with appropriate foot orthotics, favors a safer return to sports.
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