RESUMO
BACKGROUND:It has been demonstrated that shortening of femoral eccentricity would lead to decreased abductor muscle strength,and overlengthening eccentricity would increase the risk of femoral neck prosthesis fracture and the compressive stress of cemented femoral stem prosthesis after artificial hip replacement,which easily causes prosthetic loosening and subsidence.OBJECTIVE:To investigate the importance of eccentricity adjustment in the artificial hip replacement for treatment of femoral neck fracture in elderly patients.DESIGN,TIME AND SETTING:An observational study was performed at the Department of Orthopedics,First Affiliated Hospital of Tianjin University of Traditional Chinese Medicine between January 2004 and December 2005.PARTICIPANTS:A total of 30 patients with femoral neck fracture,12 males and 18 females,averaging 73.8 years of age (range 62-90 years old),received treatment at the Department of Orthopedics,First Affiliated Hospital of Tianjin University of Traditional Chinese Medicine and were recruited into this study.METHODS:All patients underwent artificial hip replacement operated by the same team of surgeons.Prior to surgery,some indices on the uninjured side were determined through the anteroposterior radiographs of pelvis using X-Caliper measurement tool,including rotation center of femoral head,rotation center of hip joint,collodiaphyseal angle,femoral transverse eccentricity,abduction moment arm,and moment arm of gravity.These indices were precisely calculated using trigonometric function.The angle of osteotomy plane was determined.Proper prosthesis was selected and eccentricity was adjusted.Following artificial hip placement,a comparison was made between uninjured and injured sides.MAIN OUTCOME MEASURES:Eccentricity and hip joint function.RESULTS:The eccentricity on uninjured side of 30 patients averaged 38.7 mm (range 22-57 mm) prior to surgery and that on the injured side averaged 39.2 mm (range 21-59 mm) after surgery.Limb discrepancy ranged 1.8-8.7 mm,with a mean of 3.4 mm,after surgery.There were 26 patients (86.7%) presenting long limbs and 4 patients (13.3%) showing short limbs after surgery.All patients were followed-up 0.5-2.5 years old.Harris hip score results were excellent in 10 patients,good in 19 patients,and fair in 1 patient,with an excellent and good rate of 97%.CONCLUSION:In treatment of femoral neck fracture,eccentricity adjustment during artificial hip replacement is closely associated with hip joint function after surgery.