Wear and corrosion at the taper interface in retrieved ASR Xl metal-on-metal total hip arthroplasty
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0128: TRUNNION DESIGN AND FEMORAL HEAD DIAMETER INCREASE CORROSION AT THE TAPER INTERFACE IN RETRIEVED LARGE- DIAMETER METAL-ON-METAL TOTAL HIP ARTHROPLASTY Adam Hexter 1 , Anna Panagiotidou 2 , Gordon Blunn 2 , John Skinner 1 , Alister Hart 1 . 1 London Implant Retrieval Centre, Imperial College London, London, UK; 2 Royal National Orthopaedic Hospital, London, UK Aim: To characterise corrosion at the taper interface in large diameter metal-on-metal total hip arthroplasty and the effect of femoral head diameter. Method: Corrosion was qualitatively assessed using a peer-reviewed grading system for 111 components from three different manufacturers (ASR, BHR, Durom). Unexpectedly a ridged appearance was commonly observed on the female taper surfaces, which corresponded exactly with the ridges of the trunnion surface. A new grading system was created to measure this imprinting phenomenon. Results: 92% of the components experienced corrosion, with at least moderate corrosion seen in 61%. The manufacturer did not influence corrosion both for head components (p¼0.52) and trunnions (p¼0.20). A strong positive correlation (r¼0.776, p¼0.01) was observed between the imprinting scores and corrosion scores. Larger head diameters showed higher corrosion (r¼0.241, p¼0.02). Conclusions: Corrosion affects all manufacturers and is associated with the presence of ridges on the female taper surface. It appears that the rough surface of the trunnion causes extensive mechanical damage at the female taper surface and creates a hostile corrosive environment. Femoral head diameter correlates with corrosion, which is clinically significant considering the increasing use of larger head sizes. Future work must now clarify the optimum trunnion design and femoral head diameter. 0129: WEAR AND CORROSION AT THE TAPER INTERFACE IN RETRIEVED ASR XL METAL-ON-METAL TOTAL HIP ARTHROPLASTY Adam Hexter 1 , Anna Panagiotidou 2 , Gordon Blunn 2 , Johann Henckel 1 , John Skinner 1 , Alister Hart 1 . 1 London Implant Retrieval Centre, London, UK; 2 Royal National Orthopaedic Hospital, London, UK Aim: To quantify wear at the ASR XL taper interface and determine the relationship between taper corrosion and blood metal ions. Method: Corrosion was qualitatively assessed using a peer-reviewed grading system for 52 ASR XL femoral head components. Blood metal ion levels in hips showing at least moderate corrosion was compared with those without moderate corrosion. Profilometry was performed in hips (n¼12) that failed due to debris-induced synovitis in the presence of low bearing surface wear (<10mm/year combined head/ cup). Results: 98% of the components were corroded, with at least moderate corrosion observed in 66%. Corrosion did not influence the levels of blood cobalt (p¼0.16) and chromium (p¼0.12) ions. The median volumetric loss was 3.08mm 3 (range: 0.61-9.44) and the maximum wear depth ranged from 14-85mm. Conclusions: Metal debris is implicated in the formation of soft-tissue reactions and we show that taper wear and corrosion is substantial. Currently there is no other culprit that could account for the higher failure rate of the ASR XL when compared to resurfacing. Greater corrosion did not equate to increased metal ion levels. Future work must determine the relative contributions of the bearing surface and taper interface to material loss and blood metal ions. 0157 WINNER OF ORTHOPAEDIC RESEARCH UK PRIZE: ACCURACY OF DIGITAL TEMPLATING IN TOTAL HIP REPLACEMENT AND POST- OPERATIVE LEG LENGTH INEQUALITY John Kyle 1 , Anthony McWilliams 2 , Richard Grogan 2 . 1 James Cook University Hospital, Middlesbrough, UK; 2 Bradford Royal Infirmary, Bradford, UK Aims: We aimed to determine the accuracy of digital templating at pre- dicting implant size for total hip replacement (THR) and to measure and compare pre- and post-operative leg-length inequality (LLI). Methods: The radiographs of 70 patients undergoing THR were analysed. All radiographs were templated pre-operatively using IMPAX AGFA soft- ware. Implant size data was collected from theatre records. LLI was determined using IMPAX software on the pre- and post-operative radiographs. Results: Complete templating data was available for 55 patients. In 34.7% of cases the acetabular cup size was accurately predicted by pre-operative templating, with 74.5% being within +/- 2mm. Digital templating accu- rately predicted the stem size in 32.7% of cases with 65.5% being within +/- 1 stem size. Complete LLI data was available for 67 patients. The mean pre-operative LLI was 5.3 mm (range -11.9mm to +30.3mm) with the mean post-oper- ative LLI being 7.2 mm (range -19.3mm to +25.3mm). 73.1% of patients had a post-operative LLI of <10mm and 89.6% were <15mm. Conclusion: Digital templating in THR is accurate to within one cup size (2mm) in 74.5%of cases and to within one stem size in 65.5% of cases. Mean post-operative LLI is less than the generally acceptable limit of 10mm. 0160: COMPARISON OF LEVELS OF PAIN PERCEIVED WHEN USING PNEUMATIC VERSUS SILICONE RING TOURNIQUETS FOR LOCAL ANAESTHETIC PROCEDURES OF THE UPPER LIMB Oliver Smith, Richard Heasley, Gillian Eastwood, Stephen Royle. Stepping Hill Hospital, Stockport, UK Aim: To compare the level of perceived pain, and therefore tolerance, of the Silicone Ring and Pneumatic tourniquets when applied to the upper arm and to evaluate whether there was a clear benefit of use of either tourniquet in local anaesthetic procedures of the upper limb. Materials and Methods: 30 volunteers, 15 male and 15 female, were recruited. Pain was measured using a VAS pain scale on application and at 1, 5 and 10 minutes. Results: Volunteers experienced significantly more pain on application and at 1 and 5 minutes with the SRT. This difference in pain perceived was most marked upon application. Two volunteers could not tolerate appli- cation of the SRT. Three volunteers experienced bruising of the arm and/or forearm following use of the SRT. There was no difference in pain scores at 10 minutes. Conclusion: Due to the severe pain experienced on application of the SRT it would not be suitable for local anaesthetic procedures in the upper limb. In addition the degree of pain may reduce the patients confidence and adversely affect their experience of the procedure. The PT is more suitable for local procedures. However the SRT may have a role in procedures performed under general anaesthetic. 0164: TRAUMA OPERATION NOTES RE-AUDIT AFTER INSTIGATION OF COMPUTER RECORDS PROGRAMME IQ UTOPIA: HOW DO COMPUTER- GENERATED OPERATION NOTES COMPLY WITH ROYAL COLLEGE OF SURGEONS OF ENGLAND'S GUIDELINES, COMPARED TO HAND- WRITTEN NOTES? Denise Yeung, Naffis Anjarwalla. Wexham Park Hospital, Slough, UK Aim: Assess compliance of computer-documented (IQ Utopia) v hand- written operation notes, to Royal College of Surgeons of England (RCSE) recommendations (re-audit). Method: A cross-sectional sample of computerised operation notes were examined in Wexham Park Hospital in-patients who had Orthopaedic operations (n¼40, March 2011) and compliance was noted and compared to hand-written notes (March 2010). Fourteen categories were audited: hospital number, name, date, consultant, surgeon, procedure, incision, operative diagnosis, findings, complications, tissues removed/added/ altered, serialnumbers,sutures, post-operative care and surgeon's signature. Results: Compliance was achieved in every category with IQ Utopia. Lowest compliance was the surgeon's signature: 80%. Compared to hand- written operation notes from 2010, compliance improved in hospital number (100%), date of operation (100%), incision (97.4%), operative diagnosis (100%), findings (100%), complications (100%), details of tissue removed/added/altered (100%), sutures (100%), post-operative care (100%). Two categories worsened: serial number (95.1% to 85.3%) and signature (98.1% to 80%). Conclusion: Using IQ Utopia resulted in compliance in all categories with the Operative Notes Guidelines as stated by the RCSE. Compliance improved in most categories except in serial number and also signature. It is likely that the implementation of a computer programme to generate operation notes was associated with this improved compliance. Abstracts / International Journal of Surgery 10 (2012) S53–S109 S55 ABSTRACTS
Transcript of Wear and corrosion at the taper interface in retrieved ASR Xl metal-on-metal total hip arthroplasty
Abstracts / International Journal of Surgery 10 (2012) S53–S109 S55
ABSTRACTS
0128: TRUNNION DESIGN AND FEMORAL HEAD DIAMETER INCREASECORROSION AT THE TAPER INTERFACE IN RETRIEVED LARGE-DIAMETER METAL-ON-METAL TOTAL HIP ARTHROPLASTY
Adam Hexter 1, Anna Panagiotidou 2, Gordon Blunn 2, JohnSkinner 1, Alister Hart 1. 1 London Implant Retrieval Centre, Imperial CollegeLondon, London, UK; 2Royal National Orthopaedic Hospital, London, UK
Aim: To characterise corrosion at the taper interface in large diametermetal-on-metal total hip arthroplasty and the effect of femoral headdiameter.Method: Corrosion was qualitatively assessed using a peer-reviewedgrading system for 111 components from three different manufacturers(ASR, BHR, Durom). Unexpectedly a ridged appearance was commonlyobserved on the female taper surfaces, which corresponded exactly withthe ridges of the trunnion surface. A new grading system was created tomeasure this imprinting phenomenon.Results: 92% of the components experienced corrosion, with at leastmoderate corrosion seen in 61%. The manufacturer did not influencecorrosion both for head components (p¼0.52) and trunnions (p¼0.20). Astrong positive correlation (r¼0.776, p¼0.01) was observed between theimprinting scores and corrosion scores. Larger head diameters showedhigher corrosion (r¼0.241, p¼0.02).Conclusions: Corrosion affects all manufacturers and is associated withthe presence of ridges on the female taper surface. It appears that therough surface of the trunnion causes extensive mechanical damage atthe female taper surface and creates a hostile corrosive environment.Femoral head diameter correlates with corrosion, which is clinicallysignificant considering the increasing use of larger head sizes. Futurework must now clarify the optimum trunnion design and femoral headdiameter.
0129: WEAR AND CORROSION AT THE TAPER INTERFACE IN RETRIEVEDASR XL METAL-ON-METAL TOTAL HIP ARTHROPLASTY
Adam Hexter 1, Anna Panagiotidou 2, Gordon Blunn 2, JohannHenckel 1, John Skinner 1, Alister Hart 1. 1 London Implant Retrieval Centre,London, UK; 2Royal National Orthopaedic Hospital, London, UK
Aim: To quantify wear at the ASR XL taper interface and determine therelationship between taper corrosion and blood metal ions.Method: Corrosion was qualitatively assessed using a peer-reviewedgrading system for 52 ASR XL femoral head components. Blood metalion levels in hips showing at least moderate corrosion was comparedwith those without moderate corrosion. Profilometry was performedin hips (n¼12) that failed due to debris-induced synovitis in thepresence of low bearing surface wear (<10mm/year combined head/cup).Results: 98% of the components were corroded, with at least moderatecorrosion observed in 66%. Corrosion did not influence the levels of bloodcobalt (p¼0.16) and chromium (p¼0.12) ions. The median volumetric losswas 3.08mm3 (range: 0.61-9.44) and the maximum wear depth rangedfrom 14-85mm.Conclusions: Metal debris is implicated in the formation of soft-tissuereactions and we show that taper wear and corrosion is substantial.Currently there is no other culprit that could account for the higher failurerate of the ASR XL when compared to resurfacing. Greater corrosion didnot equate to increased metal ion levels. Future work must determine therelative contributions of the bearing surface and taper interface tomaterialloss and blood metal ions.
0157 WINNER OF ORTHOPAEDIC RESEARCH UK PRIZE: ACCURACY OFDIGITAL TEMPLATING IN TOTAL HIP REPLACEMENT AND POST-OPERATIVE LEG LENGTH INEQUALITY
John Kyle 1, Anthony McWilliams 2, Richard Grogan 2. 1 James CookUniversity Hospital, Middlesbrough, UK; 2Bradford Royal Infirmary,Bradford, UK
Aims: We aimed to determine the accuracy of digital templating at pre-dicting implant size for total hip replacement (THR) and to measure andcompare pre- and post-operative leg-length inequality (LLI).Methods: The radiographs of 70 patients undergoing THR were analysed.All radiographs were templated pre-operatively using IMPAX AGFA soft-ware. Implant size data was collected from theatre records. LLI was
determined using IMPAX software on the pre- and post-operativeradiographs.Results: Complete templating data was available for 55 patients. In 34.7%of cases the acetabular cup size was accurately predicted by pre-operativetemplating, with 74.5% being within +/- 2mm. Digital templating accu-rately predicted the stem size in 32.7% of cases with 65.5% being within +/-1 stem size.Complete LLI data was available for 67 patients. The mean pre-operativeLLI was 5.3 mm (range -11.9mm to +30.3mm) with the mean post-oper-ative LLI being 7.2 mm (range -19.3mm to +25.3mm). 73.1% of patients hada post-operative LLI of <10mm and 89.6% were <15mm.Conclusion: Digital templating in THR is accurate to within one cup size(2mm) in 74.5%of cases and towithin one stem size in 65.5% of cases. Meanpost-operative LLI is less than the generally acceptable limit of 10mm.
0160: COMPARISON OF LEVELS OF PAIN PERCEIVED WHEN USINGPNEUMATIC VERSUS SILICONE RING TOURNIQUETS FOR LOCALANAESTHETIC PROCEDURES OF THE UPPER LIMB
Oliver Smith, Richard Heasley, Gillian Eastwood, Stephen Royle. SteppingHill Hospital, Stockport, UK
Aim: To compare the level of perceived pain, and therefore tolerance, ofthe Silicone Ring and Pneumatic tourniquets when applied to the upperarm and to evaluate whether there was a clear benefit of use of eithertourniquet in local anaesthetic procedures of the upper limb.Materials and Methods: 30 volunteers, 15 male and 15 female, wererecruited. Pain was measured using a VAS pain scale on application and at1, 5 and 10 minutes.Results: Volunteers experienced significantly more pain on applicationand at 1 and 5 minutes with the SRT. This difference in pain perceived wasmost marked upon application. Two volunteers could not tolerate appli-cation of the SRT. Three volunteers experienced bruising of the arm and/orforearm following use of the SRT. There was no difference in pain scores at10 minutes.Conclusion: Due to the severe pain experienced on application of the SRTit would not be suitable for local anaesthetic procedures in the upper limb.In addition the degree of pain may reduce the patients confidence andadversely affect their experience of the procedure. The PT is more suitablefor local procedures. However the SRT may have a role in proceduresperformed under general anaesthetic.
0164: TRAUMA OPERATION NOTES RE-AUDIT AFTER INSTIGATION OFCOMPUTER RECORDS PROGRAMME IQ UTOPIA: HOW DO COMPUTER-GENERATED OPERATION NOTES COMPLY WITH ROYAL COLLEGE OFSURGEONS OF ENGLAND'S GUIDELINES, COMPARED TO HAND-WRITTEN NOTES?
Denise Yeung, Naffis Anjarwalla. Wexham Park Hospital, Slough, UK
Aim: Assess compliance of computer-documented (IQ Utopia) v hand-written operation notes, to Royal College of Surgeons of England (RCSE)recommendations (re-audit).Method: A cross-sectional sample of computerised operation notes wereexamined in Wexham Park Hospital in-patients who had Orthopaedicoperations (n¼40,March 2011) and compliancewas noted and compared tohand-written notes (March 2010). Fourteen categories were audited:hospital number, name, date, consultant, surgeon, procedure, incision,operative diagnosis, findings, complications, tissues removed/added/altered, serialnumbers, sutures, post-operativecareandsurgeon's signature.Results: Compliance was achieved in every category with IQ Utopia.Lowest compliance was the surgeon's signature: 80%. Compared to hand-written operation notes from 2010, compliance improved in hospitalnumber (100%), date of operation (100%), incision (97.4%), operativediagnosis (100%), findings (100%), complications (100%), details of tissueremoved/added/altered (100%), sutures (100%), post-operative care(100%). Two categories worsened: serial number (95.1% to 85.3%) andsignature (98.1% to 80%).Conclusion: Using IQ Utopia resulted in compliance in all categories withthe Operative Notes Guidelines as stated by the RCSE. Complianceimproved in most categories except in serial number and also signature. Itis likely that the implementation of a computer programme to generateoperation notes was associated with this improved compliance.
