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Metal-on-metal resurfacing:Questions & AnswersWhat are metal-ions? Where do they come from?Metal ions are the soluble (in solution) form of a metal and can be released from wear and/or corrosion ofany metallic implant within the body. Metal ions are present as trace elements within the human body and areessential for life.

What is ALVAL?ALVAL or Aseptic Lymphocytic Vasculitis and Associated Lesions is thought to be a localized lymphocytic drivenhypersensitivity immune response to particulate or metal ion/protein complexes produced from metallic implants 1.Exact incidence is thought to be extremely rare but does not appear to correlate to basic preoperative metalsensitivity tests.

What is the cause and incidence of pseudotumours in total hip replacements?Pseudotumours have been reported in the literature irrelevant of bearing type as an inflammatory response toforeign material within the body resulting in a collection of fluid or soft tissue mass. 2-14 The incidence has beenshown to correlate to implants wearing at a significantly higher rate than expected. 15

Figure 1 - Histological sections showing perivascular agglomerated infiltrates of CD3 and

activated T Lymphocytes (stained brown) in retrieved capsular tissue of a patient withmetal sensitivity post metal-on-metal hip replacement

Figure 2 - CT scan of a pelvis in a conventional metal-on-polyethylene total hip showing a space occupying mass. Biopsyneedle can be seen on the top left.

Figure 3 - AP X-Ray of the pelvis in conventional metal-on-polyethylene hip showing eccentric wear of the liner.

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Does the BHR device release more metal ions than other resurfacing devices?Most of the wear of any metal-on-metal device has been shown to occur during the run in period in the first 6-12 months afterimplantation. 16,17 After the run in period there is a lower steady state of metal ion release. Variation in metal ion release has beenprimarily related to acetabular component position.18,19,20 The recommended acetabular component position for the BHR device isbetween 40-45 deg inclination and 20-25 deg anteversion for longevity of the bearing.

What effect does clearance, head size and activity have on metal ion release?Head size and patient activity have been shown to have no statistical effect on metal ion output.21,22.23

Low clearance has been shown to reduce wear of a metal-on-metal device in laboratory studies but has produced no proven beneficlinically, with variables such as cup design and cup deflection appearing to play a larger role. 24,25

References

Willert HG, Buchhorn GH, Fayyazi A, Flury R, Windler M, Kster G, Lohmann CH. Hip Joints. A Clinical and Histomorphological Study Metal-on-metal Bearings andHypersensitivity in Patients with Artificial.J Bone Joint Surg Am. 2005;87:28-36.Leigh W, OGrady P, Lawson E, Hung N A, BSC, Theis JC, Matheson J, FRACS. Pelvic Pseudotumor An Unusual Presentation of an Extra-Articular Granuloma in a Well-FixeTotal Hip Arthroplasty.J Arthroplasty, 2007: Vol.00Hisatome T, Yasunaga Y, Ikuta Y, Takahashi K, Hidden Intrapelvic Granulomatous Lesions Associated with Total Hip: A Report of Two Cases, J Bone Joint Surg Am.2003;85:708-710.Howie DW, Cain CM, Cornish BL. Pseudo-abscess of the psoas bursa in failed double-cup arthroplasty of the hip. J Bone Joint Surg Br. 1991;73- B(1):29-32Svensson O, Mathiesen EB, Reinholt FP, Blomgren G. Formation of a fulminant soft-tissue pseudotumor after uncemented hip arthroplasty. A case report.J Bone Joint SurAm. 1988;70(8):1238-1242Hattrup SJ, Bryan RS, Gaffey TA, et al. Pelvic mass causing vesical compression after total hip arthroplasty. Case report. Clin Orthop 1988;227:Reigstad A, Rokkum M. An intrapelvic granuloma induced by acetabular cup loosening. Acta Orthop Scand 1992;63:465.DeFrang RD, Guyer WD, Porter JM, et al. Synovial cyst formation complicating total hip arthroplasty: a case report. Clin Orthop Relat Res 1996:163.Matsumoto K, Hukuda S, Nishoka J, et al. Iliopsoas bursal distension caused by acetabular loosening after total hip arthroplasty: a rare complication of total hiparthroplasty. Clin Orthop 1992:144.

. Fischer SR, Christ DJ, Roehr BA. Sciatic neuropathy secondary to total hip arthroplasty wear debris. J Arthroplasty 1999;14:771.Korkala O, Syrjanen KJ. Intrapelvic cyst formation after hip arthroplasty with a carbon fibre-reinforced polyethylene socket. Arch Orthop Trauma Surg 1998; 118:113.

. Wang JW, Lin CC. Pelvic mass caused by polyethylene wear after uncemented total hip arthroplasty. J Arthroplasty 1996;11:626.

. Butler RA, Barrack RL. Total hip wear debris presenting as lower extremity swelling. A report of two cases. J Bone Joint Surg Am 2004;86:142.

. Pandit H, Glyn-Jones S, McLardy-Smith P, Gundle R, Whitwell D, Gibbons C.L.M, Ostlere S, Athanasou N, Gill H.S, Murray D, W, Pseudotumours associated with Metal onMetal resurfacings, J Bone Joint Surg Br, 2008; VOL. 90-B, No. 7

. A. J. Hart AJ, Sabah S, Henckel J, Lewis A, Cobb J, Sampson B, Mitchell A, Skinner JA. The painful metal-on-metal hip resurfacing. J Bone Joint Surg Br, 2009; VOL. 91-B,No. 6

. Daniel J, Ziaee H, Pradhan C, Pynsent PB, McMinn DJW. Blood and urine metal ion levels in young and active patients after Birmingham hip resurfacing arthroplasty: Fouryear Results of a Prospective Longitudinal Study.J Bone Joint Surg Br. 2007;89-B(2):169-173.

. Heisel C, Streich N, Krachler M, Jakubowitz E, Kretzer JP. Characterization of the Running-in Period in Total Hip Resurfacing Arthroplasty: An in Vivo and in Vitro Metal IonAnalysis.J Bone Joint Surg Am. 2008;90(Supplement_3):125-133.

. Langton DJ, Jameson SS, Joyce TJ, Webb J, Nargol AVF. Blood metal ion concentrations post hip resurfacing arthroplasty: a comparison study of the articular surfacereplacement and Birmingham hip resurfacing devices.J Bone Joint Surg Br. 2009;91-B(10)

. Langton DJ, Jameson SS, Joyce TJ, Webb J, Nargol AVF. The effect of component size and orientation on the concentrations of metal ions after resurfacing arthroplasty ofthe hip.J Bone Joint Surg Br. 2008;90-B(9):1143-1151

0. De Haan R, Campbell PA, Su EP, De Smet KA. Revision of metal-on-metal resurfacing arthroplasty of the hip: The Influence of Malpositioning of the Components. J BoneJoint Surg Br. 2008;90-B(9):1158-1163.

. Daniel J, Ziaee H, Salama A, Pradhan C, McMinn DJW. The effect of the diameter of metal-on-metal bearings on systemic exposure to cobalt and chromium.J Bone Joint Surg Br. 2006;88-B(4):443-448

2. De Haan R, Campbell P, Reid S, Skipor AK, De Smet K. Metal ion levels in a triathlete with a metal-on-metal resurfacing arthroplasty of the hip. J Bone Joint Surg Br.2007;89-B(4):538-541

3. Heisel C, Silva M, Skipor AK, Jacobs JJ, Schmalzried TP. The Relationship Between Activity and Ions in Patients with Metal-on-Metal Bearing Hip Prostheses. J Bone JointSurg Amv. . 2005;87(4):781-787.

4. Isaac GH, Cobb AG, McLenan-Smith R, Oakeshott RD, OSullivan T, Schmalzried TP. Metal Ion Levels and Component Positioning After Surface Replacement of the Hip.Early Results. ORS Poster Presentation 2008.

5. Isaac GH, Siebel TP, Schmalzried TP, Cobb AG, OSullivan T, Oakeshott RD, Flett M, Vail TP. Development rationale for an articular surface replacement: a science-basedevolution. IMechE 2006 Proc. IMechE Vol. 220 Part H: J.

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