Manual Therapy Facilitates Homeostatic Adaptation to Bone Microstructural Declines Induced by a Rat Model of Repetitive Forceful Task

Abstract

The effectiveness of manual therapy in reducing the catabolic effects of performing repetitive intensive force tasks on bones has not been reported. We examined if manual therapy could reduce radial bone microstructural declines in adult female Sprague–Dawley rats performing a 12-week high-repetition and high-force task, with or without simultaneous manual therapy to forelimbs. Additional rats were provided 6 weeks of rest after task cessation, with or without manual therapy. The control rats were untreated or received manual therapy for 12 weeks. The untreated TASK rats showed increased catabolic indices in the radius (decreased trabecular bone volume and numbers, increased osteoclasts in these trabeculae, and mid-diaphyseal cortical bone thinning) and increased serum CTX-1, TNF-α, and muscle macrophages. In contrast, the TASK rats receiving manual therapy showed increased radial bone anabolism (increased trabecular bone volume and osteoblast numbers, decreased osteoclast numbers, and increased mid-diaphyseal total area and periosteal perimeter) and increased serum TNF-α and muscle macrophages. Rest, with or without manual therapy, improved the trabecular thickness and mid-diaphyseal cortical bone attributes but not the mineral density. Thus, preventive manual therapy reduced the net radial bone catabolism by increasing osteogenesis, while rest, with or without manual therapy, was less effective.

Blocking CCN2 Reduces Established Bone Loss Induced by Prolonged Intense Loading by Increasing Osteoblast Activity in Rats

“…This would be consistent with findings from another study in which we examined the effects of 6 weeks of rest, with or without a manual therapy treatment, after a 12‐week task period. [ 31 ] We found that rest (alone or combined with manual therapy) effectively rescued the osteoclastic response but did not improve osteoblastic numbers or activity or already established task‐induced loss in trabecular bone volume fraction. [ 31 ] Only the anti‐CCN2 treatment during rest improved the task‐induced trabecular bone loss.…”

“…[ 31 ] We found that rest (alone or combined with manual therapy) effectively rescued the osteoclastic response but did not improve osteoblastic numbers or activity or already established task‐induced loss in trabecular bone volume fraction. [ 31 ] Only the anti‐CCN2 treatment during rest improved the task‐induced trabecular bone loss.…”

“…HRHF task reach outcomes (mean number of reaches/min, mean grasp force in centi‐Newtons [cN] of force, mean grasp duration in milliseconds [ms], and mean reach impulse) were recorded continuously, as previously described. [ 20 , 31 ] Data are provided for task weeks 1, 3, 6, 9, 12, and 18. These data could not be generated for FRC rats as they did not perform the task, nor could these data be assessed in the rats resting after task cessation.…”

“…After fixation, forelimb bones from 10 age‐matched FRC, 10 HRHF‐Untreated, 5 HRHF‐Rest/IgG, and 6 HRHF‐Rest/anti‐CCN2 rats were stored in phosphate‐buffered saline (PBS) with sodium azide until they underwent microCT scanning using previously described instrumentation and methods. [ 20 , 31 ] MicroCT scanning and analysis was performed, as previously described, in metaphyseal and diaphyseal regions of the radius, [ 31 ] by an individual who was blinded to group assignment, according to published guidelines. [ 35 ] The metaphyseal trabecular bone region of interest was delineated from 150 to 250 μm below the center of the distal growth plate.…”