Rotator-cuff tears (RCTs) are typically associated with chronic pain. The most common treatment for reducing pain is the injection of cortisone into the injury site. An alternative and increasingly used technique is the injection of autologous platelet-rich plasma (PRP). A limitation of cortisone is its pain relief is short-lived, while PRP has the limitation of providing pain relief to only about 50% of patients, making its efficacy questioned, although when it is effective, its efficacy is longer than cortisone. Little is known about what accounts for these limitations. This paper presents results from a patient with RCTs causing excruciating pain who received an injection of PRP into that shoulder resulting in complete pain elimination that was ongoing at 2 years and 2 months. When 7-month severe posttrauma pain associated with the RCT developed in the contralateral shoulder, PRP prepared the same way and injected by the same person who performed the first injection provided no pain relief. However, a subsequent single cortisone injection resulted in complete pain elimination, which was ongoing at >15 months. These observations indicate that PRP can have inconsistent effects in reducing pain, not only between patients but also within the same patient. Further, although the pain relief induced by cortisone is normally not long-lasting, when given following a PRP injection, it can induce complete pain relief lasting >15 months. This paper discusses possible reasons for the variability in PRP efficacy on pain relief and addresses the possibility that when administered together, PRP and cortisone may act in a complementary manner, leading to significantly greater and longer-lasting pain relief.