Hip arthroscopies are becoming a standard surgical technique, with psoas tenotomy being a relatively common procedure during this operation. A 37-year-old male and a 42-year-old female with internal hip snapping came to our department. Arthroscopic partial psoas tenotomy of the iliopsoas portion of the conjoint tendon was performed, but its results were bad. Patients reported preoperative unilateral low-back pain and weakness when flexing the hip. Unilateral atrophy of the lumbar psoas and fatty multifidus were detected in both cases. Patients at risk of unsatisfactory outcomes after psoas tenotomy should be ideally identified prior to surgery. Warning symptoms, physical examination, and imaging studies should be considered to avoid unsatisfactory results.