Serum Metal Ions Level And Related Factors Within5Years After Resurfacing Arthroplasty Of The Hip

Objective:To explore the tendency of serum Co、Cr、Mo ion level within5years after resurfacing arthroplasty of the hip (RSAH), and analyze the related factors.Materials and methods:From2006.9～2013.3,40patients52hips were included in this study,20males,20females, Bilateral28, unilateral12, mean age49. Conserve Plus29hips, ASR5hips, BHR or BMHR18hips. Preoperative randomly selected7patients’ serum samples as a control group. Serum Co, Cr and Mo ions levels preoperative and3、6months and1、2、4、5years postoperative were examined by inductively coupled plasma mass spectrometry (ICP-MS).From all the RSAH patients,there are29patients38hips for at least1year after surgery including12males,17females, mean age52.3,7patients9hips were diagnosed as osteonecrosis of the femoral head,14patients8hips as developmental dysplasia of the hip,2patients3hips as ankylosing spondylitis,2patients3hips as osteoarthritis,2patients3hips as rheumatoid arthritis,1patient1hip as pigmented villonodular synovitis. Bilateral20, unilateral9, BHR or BMHR7hips, ASR5hips, Conserve Plus26hips. Analyze the relationship between metal ion levels and other factors, for example body mass index, the diameter of the femoral head, postoperative Harris hip score, stem shaft angle, neck shaft angle, abduction angle, anteversion, center edge angle.Results:Preoperative Co, Cr, Mo ion mean levels were0.69ng/mL±0.06ng/mL (0.56ng/mL-0.81ng/mL),0.75ng/mL±0.04ng/mL(0.62ng/mL-0.89ng/mL),0.83ng/mL±0.04ng/mL(0.74ng/mL-0.91ng/mL). Co, Cr, Mo ion mean levels continue to rise postoperative. Co ion level reached the peak at6months after operation, which was6.6-fold relative to preoperative, average1.98ng/mL±1.22ng/mL(0.98ng/mL-3.70ng/mL), Cr ion level reached the peak at1year after operation, which was1.5-fold relative to preoperative, average1.15ng/mL±0.30ng/mL(0.89ng/mL-1.66ng/mL), Mo ion level reached the peak at3months after operation, which was10.7-fold relative to preoperative, average8.90ng/m＋2.23ng/mL(5.88ng/mL-11.20ng/mL). Thereafter Co, Cr ion levels were reduced, Mo ion levels fluctuated, but after5years Co, Cr, Mo ion levels were increased again, reaching an average of1.06ng/mL,1.22ng/mL nd8.33ng/mL respectively1.5-fold,1.6-fold and5.0-fold compare with preoperative. Cr ion level in female is significant higher than male (P=0.038). For Co、Cr ions, BHR or BMHR is significant lower than Conserve Plus and ASR (P<0.05). By multiple linear regression analysis showed that postoperative Harris hip score, the prosthesis head diameter, center edge angle will work together to influence Co, Cr ion levels, and were negatively correlated, Establish factors equation: Co ion levels=12.176-0.126*postoperative Harris hip score-0.139*-0.122*prosthetic head diameter center edge angle, Cr ion levels=3.633-0.031*-0.006*postoperative Harris hip score prosthetic head diameter-0.069*center edge angle. There are no relationship among body mass index, stem-shaft angle, neck-shaft angle, acetabular abduction angle and anteversion, abductor moment arm and body moment arm, femoral offset (P>0.05). When unilateral or bilateral replacement, Co, Cr, Mo ion levels no significant difference (P values were0.167,0.699,0.185).Conclusion:Postoperative of RSAH, serum Co, Cr and Mo ions level increased obviously, reached peak at6months1year and3months, Co, Cr ion levels were reduced, Mo ion levels fluctuated. And after5years, Co, Cr, Mo ion levels were increased again. Sex, prosthesis model, postoperative Harris hip score, prosthetic head diameter, center edge angle etc have an impact on the level of metal ions. Body mass index, stem-shaft angle, neck-shaft angle, acetabular abduction angle and anteversion, femoral offset, abductor lever arm and weight arm has no effect on metal ion levels. For Co, Cr ion levels, its impact on the larger factors were postoperative Harris hip score and the center edge angle, and center edge angle and prosthetic head diameter influenced smaller. For women, BHR or BMHR prosthesis, postoperative Harris score, smaller prosthetic head diameter, center edge angle less than10°or greater than40°need close monitoring of metal ion levels change.