New Generation Ceramic On Ceramic Total Hip Arthroplasty

Background: Advancement in bearing surfaces has expanded prosthetic headoptions from traditional sizes of22,26,28,32mm to diameter as large as60mm.In our series36mm and40mm diameter ceramic femoral head was used withceramic on ceramic bearing surfaces. Aim of our study is to observe the effect oflarge diameter ceramic femoral head with ceramic on ceramic bearing in primarytotal hip arthroplasty(THA)Method:In the year between2009to2012, total112(102patients) primary total hipreplacement were performed in our institution by using large diameter(36and40mm) ceramic femoral head with ceramic on ceramic bearing surface. Equalnumber of patients who were operated using conventional small diameterceramic head(control group) were chosen for comparison. Out of102patients(112hips)54were male(58hips) and48were female.(54hips)10patients had bilateral THA. Mean age of our patient cohort was51.20±13.28(minimum21years and maximum:81years). The major causes were avascularnecrosis(37%), Osteoarthritis(35%), Rheumatoid arthritis(12%),trauma(8%),DDH(3%), others(5%). All patients were operated by using posterolateralapproach. Average time of surgery40minutes and mean blood loss250ml. Allthe patients had scheduled follow-up at6weeks,6months and one year and thenevery year. The average follow-up was18months. The patients were evaluatedby using x-ray, Harris Hip Score (HHS), UCLA activity score, SF-12score andobserving post-operative complications. Results:Average Harris Hip Score improved from51.73±6.64to86.01±2.86six weeksafter the operation and to96.78±1.37(range92to100) at the final follow up(p<0.05) in the trial group and from45.63±9.17(range26–69) to91.02±6.59(range59–100) in the control group. There was no significant difference in the Harris HipScore (p-0.39) in two groups. Pain score improved from a mean of14Preoperatively to39postoperatively in the trial group and from13to42in thecontrol group. The Short form (SF-12) physical score in the trial group was52±1.07and mental score was58.95±2.85at the final follow up. The UCLAactivity score was6.883±1.637at the final follow up in Dec2012.There were no case of dislocation in the study group whereas in control groupwho received conventional28and32mm diameter femoral head, number ofdislocation increased to four (3.57%) which was statistaticallysignificant(p0.05).2out of112(1.78%) patients developed class-I (BrookerClassification) heterotrophic ossification.2patient (1.78%) developed squeakingsound but was benign and occasional. None of the patient had to undergorevision or aseptic loosening. There were no cases of acetabular or femoralosteolysis till the end of follow up.Conclusion:Large diameter ceramic femoral head with ceramic on ceramic bearing surfacenot only significantly reduces the incidence of dislocation but also improvesoverall functional outcome. Long term studies will be required to determine thetrue efficacy of this new bearing surface.