At least 50% of the U.S. population has a leg-length inequality (LLI) >= 5mm. LLI can be defined by both type and magnitude. There are two types of LLI, structural and functional. Magnitude of LLI has been classified as either mild, moderate, or severe. LLI is a common condition that has been associated with various spinal, pelvic, and lower extremity dysfunctions. Diagnosis of LLI with imaging tests, which is the gold standard, can be expensive, potentially harmful, and may be contraindicated for some patient populations. Non-imaging tests for LLI are inexpensive, innocuous, and pragmatic. However, evidence reveals high variability in validity and reliability of non-imaging tests for LLI. Iliac crest height difference (ICHD) has been demonstrated to be a good estimate for LLI and may be a useful measure for identifying individuals who are at risk for injury. If ICHD is a risk factor for injury, there is a paucity of evidence guiding conservative treatment. The purpose of our study was three-fold: First, to investigate the validity and reliability of ICHD, innominate rotation difference (IRD), and LLI measurements. Second, to investigate whether ICHD is a risk factor for injury among runners; if so, then to determine an optimal cutoff ICHD magnitude associated with increased injury risk. Third, to observe changes in pain and function among individuals with running-related low back, pelvic or lower extremity pain who receive LLI correction.
