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EFORT (continued)sensitivity reaction of unclear origin to metal after 3years accompanied by relatively high serum metalion levels.Gill Harinderjit (UK) explained the many negativepredictors for MoM HR. A multivariate analysisinvolving 206 patients (124 male, 82 female) and a3 year follow-up was performed to identify majorfactors related to high wear rates and thus a highand potentially harmful level of metal exposure ofthe body. The EBRA method was used for radiologicalassessment of implant position.The study concluded that the selection of an excessivelysmall femoral ball head resulting in a smallhead/neck ratio, as well as an acetabular cup inclinationoutside the recommended range of 40° ±10°, had the greatest influence on metal wear. Inorder to preserve acetabular bone, there is a tendencyto select smaller components. However,this results in a low head/neck ratio and thus in anexcessively restricted range of motion, impingement,edge loading and increased wear.According to Harinderjit, cobalt ions have a moretoxic effect than do chromium ions.Harinderjit cited the results from another study toshow that there is a positive correlation betweennarrowing of the femoral neck by more than 10%after MoM HR and the tendency to select smallercomponents, and that there is thus also a positivecorrelation with female gender and increasedmetal wear.214 patients with an average age of 54.1 (13–73years) who had had MoM HR mainly due to primaryosteoarthritis underwent follow-up after anaverage of 4.3 (2–10) years. 6 different MoM HRimplants were used. Patients with higher wearrates for cobalt and chromium exhibited narrowingof the femoral neck of over 10% significantlymore frequently. Overall, narrowing of the femoralneck occurred in 75% of all cases, while narrowingin excess of 10% occurred in 6% of cases. Therewere multiple reasons for this, including impingement,osteolysis, impaired perfusion and evenchanges in tissue pressure in the environment surroundingthe implant.Therefore, if there is evidence of bone loss in thefemoral neck region upon follow-up, this can beinterpreted as an indicator of increased metal wearand such cases require close monitoring.Large diameter MoM bearing couplesMegan Hadley (UK) reported on new hip simulatorprotocols for the in-vitro measurement of metalwear. Frequently, in-vitro wear measurements arenot reproducible in vivo since testing in the laboratoryis performed under optimal conditions.A hip simulator test was used to analyze 4 groupsof a 36mm MoM bearing couple which varied interms of cup inclination and motion patterns versusa 28mm MoM bearing couple under standardconditions. Both an increase in inclination angleand the use of different gait patterns resulted in significantlylower gravimetric mass loss in the 36mmMoM bearing couple than in the 28mm MoM couple.Hence, even under extreme conditions, a largerhead diameter may significantly reduce the amountof wear.It has yet to be adequately explained whetherrevision of a symptomatic MoM large diameterimplant is followed by a reduction in metal ionlevels (chromium and cobalt) or whether theamount of residual metal debris in the tissueremains at the same level over a prolongedperiod.Darren Ebreo (UK) presented new findings in thisrespect. He started by explaining that the advantagesof large diameter metal ball heads, such aslow wear rate, anatomical reconstruction, protectionagainst dislocation and a high degree of mobility,contrast with the disadvantage of a large numberof metal particles, which have been blamed forhypersensitivity reactions, tissue toxicity, osteolysis,aseptic loosening and carcinogenicity.44 revisions of large diameter MoM implants(38mm THA, HR) were subjected to histologicalanalysis due to presumed metallosis after a meansurvival time of 4.8 (1.4–7) years. In 42 cases, ametal allergy, metal toxicity, or a foreign body reactionwere identified. A return of serum metal ionlevels to within normal limits was observed withinone year after revision.It was shown for the first time that serum metalion levels fall after revision of a symptomatic largediameter MoM implant.CeraNews 1/201214
10-year results with MoM THAin 1,121 patientsFabian von Knoch (Switzerland) reported on radiologicaland clinical results from 1,270 MoM THA(28mm, high carbon).Between 1994 and 2004, 1,121 patients (57%male, 43% female) underwent surgery mainly totreat primary osteoarthritis (80%) in one institution.After a mean follow-up of 6.8 years, theprobable survival rate was determined (using theKaplan-Meier method). This was 91% after 10years for the acetabular cup and 96% for thefemoral stem. The reasons for revision includedaseptic loosening in 63 cases (5%), infections in 8cases, periprosthetic fractures in 8 cases, dislocationin 8 cases, pain of unclear origin in 7 cases andacetabular cup fractures in 4 cases. The study didnot identify any significant influence on longevityfrom demographic factors, implantation factors, orsurgi cal techniques.Von Knoch concluded that the second generationMoM bearing couple does not offer any majoradvantages over other bearing couples, but is associatedwith the risk of potentially harmful metal ionlevels and can therefore only be recommended withprovisos.Ultrasound diagnostics for MoMbearing couples with ARMDFor a conversant user, ultrasound is a reliable, noninvasiveand cost effective method for the detectionof ARMD.According to Singisetti, diagnostic ultrasound isused routinely in his clinic as a screening methodfor patients with complaints of an unclear natureafter MoM implantation.8.5-year results with MoM, MoP andCoC bearing couples in a hip systemIngrid Milosev (Slovenia) reported on results withMoM (low carbon), MoP and CoC (BIOLOX ® forte)bearing couples implanted in 474 patients in 487THA performed between 01/2000 and 12/2002.The modular acetabular cup and femoral stem wereidentical in all cases. After a mean follow-up of 8.5(6.9–9.9) years, the overall revision rate was 3.7%.The revision rate was 8.7% for MoM, 4.1% for CoCand 1.5% for MoP. The MoM group had the highestrevision rate due to aseptic loosening.In the CoC group, patients mainly experiencedsecondary insert fractures due to improper handlingwhen the liner was inserted into the cup.To conclude, the MoP bearing couple can be recommendedas a solution for older, less active patients,while the CoC couple is recommended for youngeractive patients.It was noted from the audience that the CoC THAused in this study was one with a sandwich design.Various diagnostic imaging procedures areused to investigate complaints of an unclearnature after MoM implantation. The efficacyof diagnostic ultrasound in cases of ARMDhas been demonstrated for the first time in arecent study.Kiran Singisetti (UK) started by explaining theproblems associated with ARMD. The complexpathogenetic mechanisms require further research,but diagnostic assessment also presents difficulties.Ultrasound diagnostics was evaluated in a studywhich involved 35 patients in whom ARMD wasconfirmed clinically and histologically after MoMbearing couple implantation. Extra-articular fluidaccumulation was present in 33 (94.3%) of thepatients; in most cases this was found in combinationwith iliopsoas and trochanteric bursitis. Extraarticularechogenic responses were detected in 31(88.6%) of the patients. Over a period of severalmonths, progression of the changes was observedin 5 patients, while 1 patient was found to haveconverted from non-echogenic to echogenic jointeffusion.Immunological reactions: comparisonof MoM and CoP bearing couplesHypersensitivity reactions to metal wear arereported as a cause of osteolysis associated withMoM bearing couples. Evidence-based data fora correlation of this nature remains insufficientfor low-carbon MoM bearing couples.In this respect, studies of retrieved implants conductedby Thomas Repantis (Greece) have providednew findings. He analyzed retrieved implantsfrom 20 MoM bearing couples (low carbon) and 13CoP bearing couples for a hypersensitivity immuneresponse in the periprosthetic tissue. The reason forall of the revisions was aseptic loosening. Controlsamples from primary implantations and tissue samplesfrom the revisions were subjected to histologicaland immunohistochemical analysis.The 13 CoP bearing couples did not exhibit anyparti cular reactions.The 20 MoM bearing couples (low carbon) exhibitedextensive necrotic areas and fibrin exudates,which were not to be found in either the CoP bearingcouples or the control samples. Diffuse perivas-CeraNews 1/201215
Page 1 and 2: CeraNewsThe Orthopaedic Landscape I
Page 3 and 4: What is is the motive behind the la
Page 5: ScienceWhat’s New in Hip Arthropl
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Page 16: EFORT (continued)cular lymphocytic
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Page 24 and 25: AwardHeinz Mittelmeier Research Awa
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