Early Inflammatory Response of Knee Ligaments to Prolotherapy in a Rat Model

Prolotherapy is an alternative injection-based therapy for chronic musculoskeletal pain. Three different proliferants, D-glucose (dextrose), phenol-glucose-glycerine (P2G), and sodium morrhuate, used in prolotherapy are hypothesized to strengthen and reorganize chronically injured soft tissue and decrease pain through modulation of the inflammatory process. Hypothesis—Commonly used prolotherapy solutions will induce inflammation (leukocyte and macrophage infiltration) in medial collateral ligaments (MCLs) compared to needlestick, saline injection, and no-injection controls. Methods—MCLs of 84 Sprague Dawley rats were injected one time at both the tibial and femoral insertions. Immunohistochemistry (IHC) was used to determine the inflammatory response at three locations (tibial and femoral insertions and midsubstance) six, 24, and 72 hours after dextrose injection compared to saline- and no-injection controls and collagenase (positive control) (n=4). QPCR was used to analyze gene expression 24 hours post-injection (n=4). Sodium morrhuate, P2G, and needlestick control were also investigated after 24 hours (n=4). Results—In general, inflammation (CD43+, ED1+, and ED2+ cells) increased after prolotherapy injection compared to no-injection control but did not increase consistently compared to saline an