Does Subacromial Injection With Glutamate Receptor Antagonist, Ketamine, Attenuate Pain in Rotator Cuff Tendinopathy?

2,5 ml - if well tolerated immediately followed by another 2,5 ml - of an approximately 1 mg/ml ketalar solution (1 ml of ketalar 10 mg/ml + 9 ml of NaCl 9%) injected 2 times with 1-12 weeks between each injection

2,5 ml - if well tolerated immediately followed by another 2,5 ml - of a 9% NaCl solution injected 2 times with 1-12 weeks between each injection