Right knee swelled and felt like it dislocated; Right knee swelled and felt like it dislocated; Pain in groin; Felt like a muscle cramp; Blood clot as well as fluid on that knee/blood clot right leg; Muscle tear; the pain went to his knee; Pain in the arm opposite that he received the injection; his other leg "got messed up"; Blood clot as well as fluid on that knee; Knee was stiff as a board; He could not walk on either of his knees for a couple of days; Inflammation in the calf; His leg was stiff; This is a spontaneous report from a contactable consumer (patient). A 67-year-old male patient received the first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, Batch/Lot Number: ER8730), via an unspecified route of administration, administered in left arm on 30Mar2021 10:45 as single dose for COVID-19 immunization. Medical history included knee surgery, dislocated shoulder (he has dislocated that shoulder in the past several times but had no recent issues), carpal tunnel syndrome and, rheumatoid arthritis, all from an unknown date and unknown if ongoing. There were no concomitant medications. In Mar2021, the patient experienced pain in the arm opposite where he received the injection. He reported he like had a muscle tear that it has an intense excruciating pain. He took three aspirin and put a heating pad on it that didn't touch it. He then reported that the pain went to his knee and it "got all blow up" and stated that that knee had to be drained. He then stated that the calf on his other leg "got messed up" and was found to have a blood clot as well as fluid on that knee. He reported that it was as stiff as a board and that he could not walk on either of his knees for a couple of days. He reported that he still has problems with the one knee that "blew up" and had to be drained but stated that the inflammation in the calf where blood clot was has receded and is back to normal. He stated that he had to visit the emergency room twice and see an orthopedic surgeon for these issues and has been prescribed Xarelto to take to treat the blood clot. In the morning his leg was stiff. It was also reported that the patient's right knee swelled and felt like it dislocated on 16Apr2021, blood clot on right leg on 12Apr2021, and pain in groin on 13Apr2021. The pain in his groin went down, but his calf swelled to twice the size and it felt like a horse because he was favoring it. It felt like a muscle cramp. The orthopedic saw him for his left knee and he was seen in the Emergency Room for his right and they called his primary doctor. He tried to work and paid the price with his left knee. He has been taking Tylenol and icing it. The last two days (unspecified date) he has been babying it, the weather has been not so great, so he is laying low and give it a rest, but knows he is supposed to get up and move around so he has been doing that and elevating it. He would like to know if, based on these symptoms he experienced after the vaccine, he should get the second dose of the vaccine, which he states he is supposed to get on Tuesday. The outcome of the events "Right knee swelled and felt like it dislocated", and "Pain in groin" was recovering, and for other events was unknown.