title: The Assessment of Limb Length Discrepancy Before Total Hip Arthroplasty.
abstract: BACKGROUND
  The clinical relevance of limb length discrepancy (LLD) after total hip arthroplasty gains attention as the number of total hip arthroplasties increases. Although several techniques are commonly used to assess LLD using a pelvic radiograph, their accuracy is not well established. This study measures LLD using different techniques viewing the pelvis and compares the measurements with the true LLD.
  
  
  METHODS
  Pelvic landmarks used included the femoral head, lesser trochanter, acetabular teardrop, ischial tuberosity, and tibial plafond. The true LLD was determined by finding the difference in distance between the lowest point of the ischial tuberosity and the tibial plafond as well as the top of the femoral head to the center of the tibial plafond for each lower limb.
  
  
  RESULTS
  Using pelvic landmarks to assess LLD is significantly different (P < .001) from the true LLD. The difference in distance from the center of the tibial plafond to the ischial tuberosity was not significantly different from the measurement from the top of the femoral head to the center of the tibial plafond (P = .08). Also, using the acetabular teardrop as a landmark has less reliability when compared to the ischial tuberosity.
  
  
  CONCLUSIONS
  Owing to the extensive variety of pathologies that are associated with LLD, preoperative planning should include an assessment of any preexisting LLD. Although it may be reasonable to compare pelvic measurements preoperatively and postoperatively to assess for changes, the data from this study do not support the estimation of the true LLD using a pelvic radiograph.
authors.affiliation: Department of Orthopaedic Surgery, University of California, Irvine Medical Center, Orange, California.
authors.forename: Shane C
authors.initials: SC
authors.lastname: Tipton
authors.affiliation: Department of Radiology, University of California, Irvine Medical Center, Orange, California.
authors.forename: John K
authors.initials: JK
authors.lastname: Sutherland
authors.affiliation: Department of Orthopaedic Surgery, University of California, Irvine Medical Center, Orange, California.
authors.forename: Ran
authors.initials: R
authors.lastname: Schwarzkopf
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D005270:Femur Head / Q000000981:diagnostic imaging / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007512:Ischium / Q000000981:diagnostic imaging / Q000601:surgery; D007592:Joint Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D007870:Leg Length Inequality / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery
keywords: hip joint; leg length discrepancy; pelvic radiograph; preoperative planning; total hip arthroplasty