The Detection Of Peripheral Blood Metal Ion Concentration And Related Factors Analysis After Hip Surface Replacement

Objective:Observe the tendency of serum metal ions concentration level after hip resurfacing arthroplasty (RSAH), and analyze the related factors.Materials and methods:A follow-up investigation of29patients’37hips which received the RSAH was carried out. Male12, female17, mean age46.8;21unilateral and8bilateral. Preoperative diagnosis, Developmental Dislocation of the Hip(DDH)12cases16hips; Osteonecrosis of the Femeral Head (ONFH)5cases6hips; Ankylosing spondylitis5cases7hips, Rheumatoid arthritis3cases4hips, osteoarthritis in1case1hip, pigmented villonodular synovitis2cases2hip, hip retraction disease1cases1hip. Wright Conserve Plus prosthesis25hips, ASR-TM from Depuy company3hips, Birmingham hip resurfacing prosthesis from smith&nephew company9hip.Time span was3months to5years. Serum Co, Cr and Mo ions concentrations were examined by inductively coupled plasma mass spectrometry(ICP-MS)and compared with6normal people’s average metal ion value. Record the Harris score, observe the prosthesis position and angle through X-ray and CT.Results:Normal serum concentration of Co was0.63～0.79ng/mL, average0.71ng/mL; Cr concentration was0.62～0.86ng/mL, average0.73ng/mL; Mo concentration was0.74～0.91ng/mL, average0.84ng/mL. Three kinds of metal ions’normal concentration were treated as the basic reference value. The concentrations of serum Co ion reached the peak at1year after operation, which was7.7-fold relative to normal people, average5.46±0.31ng/mL (P<0.01).then Slow down, at4years after the operation,5.6times (4.01±0.06ng/mL) of average level and increased again, at5years,it was6.3times (4.12±0.39ng/mL) high, it was close at postoperation2year(4.18±0.18ng/mL) and5year.Cr ion reached its peak at9months after operation, average5.37±1.01ng/mL,which was7.5-fold relative to normal people (P<0.01), then decreased normal at5year after operation,1.00±0.04ng/mL. Mo ion concentration keeped increased even though a little wave, reach7.8-fold (1.00±0.04ng/mL) relative to normal people after5years (P《0.01).For No-DDH, when the abduction angle of acetabular component was at40°～45°,Co and Mo ion concentration were inferior to the level at <40°and>45°(P=0.011).For DDH, the abduction angle of acetabular component was at45°～50°,Co ion concentration was was inferior to the level at <45°and>50°(P=0.027). For all patients.when the anteversion angle of acetabular component was at15°～20°,Co,Cr and Mo ion concentration were inferior to the concentration at<15°and>20°(P=0.031). When the diameter of the femoral component was greater than48mm,Co ion concentration was4.02±2.12ng/mL,lower than that at <48mm.And the Co ion concentration had negative correlation with the postoperation Harris score.(P<0.05)Conclusion:Postoperative of RSAH, serum Co and Cr ions concentration increased obviously, reached peak at1year and9months, and stabilized after5years.These had close relationship with the position of acetabular component, but none with gender, age, Harris score, BMI, neck-shaft angle, handle-stem angle. Mo ion’s concentration keeped rising in5years, and didn’t have close relationship with above-mentioned factors. Application of icp-ms for determining serum metal ion concentration had lesser error rate and good repeatability.