Although these and other studies have shown positive effects of proliferant therapy on mechanical properties of ligaments as well as subjective improvements in pain and function, most have suffered from small sample size, inadequate controls, and inconsistency of study design and methodology. Kim et al reviewed and critically analyzed three randomized, controlled studies on the use of dextrose, glycerin, and phenol prolotherapy for chronic low back pain. They found inconclusive data to support its use due to the lack of adequate controls, heterogeneity in patient diagnoses, and variations in solutions injected. Nevertheless, clinical use of prolotherapy warrants further investigation.