Lateral hip pain is a common complaint in patients with a history of lower back pain from spinal disease. These patients often are diagnosed and treated for trochanteric bursitis because of localized pain and tenderness in the lateral hip. We presumed numerous scintigraphic features could provide diagnostic criteria for diagnosing gluteus medius tendinitis and trochanteric bursitis. A study was designed to assess the scintigraphic criteria for diagnosis of trochanteric bursitis and to evaluate the relationship of trochanteric bursitis to gluteus medius tendinitis and lumbar degenerative disease in predicting relapse after injection. We evaluated 97 patients with greater trochanteric pain syndrome to find a correlation between trochanteric bursitis, gluteus medius tendinitis, and spinal degenerative disease using scintigraphy and magnetic resonance imaging. We also evaluated predictors for responding to trochanteric injection of local anesthetic/glucocorticoid injection. We found a correlation between lumbar degenerative disease, gluteus medius tendinopathy, and trochanteric bursitis. Of these, 30 of 48 patients (63%) responded to injection of local anesthetic and glucocorticoids. The major predictor of relapse of pain after injection in 18 patients was the presence of moderate to severe lumbar degenerative disease seen on scintigraphic imaging. We propose a mechanistic model of the greater trochanteric pain syndrome to explain the interrelationship and response to therapy. Scintigraphy can provide sensitive and specific diagnoses of gluteus medius tendinitis and trochanteric bursitis.