Joint injection – adenosine, lidocaine and Mg2+ (ALM). Morris et. al. 2021: https://transmedcomms.biomedcentral.com/articles/10.1186/s41231-021-00084-3 This paper1 presents an exciting possibility for reducing arthrofibrosis risk after TKR surgery, using a rat model of knee replacement. A mix of adenosine, lidocaine and Mg2+ (ALM) injected into the joint immediately after closure of the capsule significantly reduced fibrosis, increased range of motion and reduced fibrotic and inflammatory markers. ALM appears to be an effective preventative, at least in heathy joints.
24 healthy male rats had one knee replaced with a custom titanium prosthesis, under anaesthesia. The rats were given an injection into the joint at the end of surgery. Half received ALM, and half had saline injected (the control group) after closure of the capsule.
At 4 weeks post-surgery the knees of ALM treated rats had twice the range of motion compared to the control group knees. ALM knees had significantly decreased synovitis and fibrotic pathology in the joint capsule and Infrapatellar fat pad compared to saline controls. In addition the protein and RNA levels of the major pro-fibrotic and inflammatory mediators were significantly lower in the ALM treated animals.
Please note that this experiment was conducted in healthy animals. Humans with osteoarthritis, fibrosis or other inflammatory conditions may react differently. However, further research indicates that the mix of adenosine, lidocaine and Mg2+ may significantly reduce the major stressors that an operation induces, and therefore reduce the risk of fibrosis.
This study used “blinded” investigators – that is, the surgeons and those that evaluated the outcomes (for example, fibrotic changes) didn’t know which individuals received the treatment, and which were controls. This method is used in good quality research to eliminate or reduce the possibility of bias in the results.
1 Morris, J. L. et al. Intra-articular Adenosine, Lidocaine and Magnesium (ALM) solution decreases postoperative joint fibrosis in an experimental knee implant model. Translational Medicine Communications 6, doi:10.1186/s41231-021-00084-3 (2021).