Abstract
BackgroundLeg length (LL) and offset (OS) are important factors in total hip arthroplasty (THA). Because most LL and OS callipers used in THA depend on fixed points on the pelvis and the femur, limb position could affect measurement error. This study was conducted on a THA simulator to clarify the effects of lower limb position and iliac pin position on LL and OS errors and to determine the permissible range of limb position for accurate LL and OS measurement.MethodsAn LL and OS measurement instrument was used. Two pin positions were tested: the iliac tubercle and the top of the iliac crest intersecting with the extension of the femoral axis. First, the limb was moved in one direction (flexion-extension, abduction-adduction, or internal-external rotation), and LL and OS were measured for each pin position. Next, the limb was moved in combinations of the three directions. Then, the permissible range of combined limb position, which resulted in LL and OS measurement error within ±2 mm, was determined for each pin position.ResultsOnly 4° of abduction/adduction caused 5–7 mm error in LL and 2–4 mm error in OS, irrespective of pin position. The effects of flexion–extension and internal–external rotation on LL error were smaller for the top of the iliac crest than for the iliac tubercle, though OS error was similar for both pin positions. For LL, the permissible range of the combined limb position was wider for the top of the iliac crest than for the iliac tubercle.ConclusionTo minimize LL and OS measurement errors in THA, adduction–abduction must be maintained. The iliac pin position in the top of the iliac crest is preferred because it provides less LL measurement error and a wider permissible range of combined limb position for accurate LL measurement.
Highlights
Total hip arthroplasty (THA) has revolutionized patient care in end-stage hip arthritis cases
Leg length and offset errors associated with unidirectional change of limb position The effects of ADD/ABD on LL and OS errors were enormous, irrespective of pin position (Fig. 2)
The effect of FX/EX on LL was larger for Pelvic pin position in the iliac tubercle (P1) than for P2 (Fig. 3)
Summary
Total hip arthroplasty (THA) has revolutionized patient care in end-stage hip arthritis cases. In order to achieve an optimal functional result after THA, it is desirable to properly adjust leg length (LL) and restore offset (OS) within the hip. Surgeons wishing to increase femoral neck OS during THA had three options:(1) increasing the neck length of the modular femoral head, (2) using a stem with a lower neck–shaft angle, or (3) using a femoral stem with a constant neck–shaft angle, but a medialized ‘high-offset’ femoral neck. Leg length (LL) and offset (OS) are important factors in total hip arthroplasty (THA). Because most LL and OS callipers used in THA depend on fixed points on the pelvis and the femur, limb position could affect measurement error. This study was conducted on a THA simulator to clarify the effects of lower limb position and iliac pin position on LL and OS errors and to determine the permissible range of limb position for accurate LL and OS measurement
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
