{"id":231,"date":"2024-06-29T03:58:57","date_gmt":"2024-06-29T03:58:57","guid":{"rendered":"https:\/\/orthopaedicsone.com\/viewpoints\/orthopaedicsone-viewpoints-the-case-for-mop-bearings-for-all-tha-patients\/"},"modified":"2024-06-29T03:59:58","modified_gmt":"2024-06-29T03:59:58","slug":"orthopaedicsone-viewpoints-the-case-for-mop-bearings-for-all-tha-patients","status":"publish","type":"page","link":"https:\/\/www.orthopaedicsone.com\/viewpoints\/orthopaedicsone-viewpoints-the-case-for-mop-bearings-for-all-tha-patients\/","title":{"rendered":"The Case for MOP Bearings for All THA Patients"},"content":{"rendered":"

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The Case for MOP Bearings for All THA Patients<\/h3>\n

Over the past few years, alternative bearing surfaces have been introduced to increase the longevity of the implant and reduce the risk of osteolysis secondary to wear debris. Improvements have resulted in an increased choice of implants for patients and their surgeons. Current demographic trends indicate that younger patients are now undergoing total hip replacements while aiming to return to an active lifestyle postoperatively.<\/p>\n

This debate is focused on the advantages and disadvantages of using metal heads on polyethylene acetabuli.<\/p>\n

Metal-on-conventional ultra high molecular weight polyethylene in total hip arthroplasty has produced very good long-term results, with reports of implant survivorship of almost 80% at over 20 years follow-up.<\/sup> Bearing surface wear, leading to osteolysis and aseptic loosening, are the leading causes of late revision total hip arthroplasty, especially in younger, more active patients.2,3<\/sup><\/p>\n

<\/span>Read more…<\/span><\/p>\n

Recently, cross-linked ultra high molecular weight polyethylene has been introduced. Initial in vitro studies showed marked improvement in wear characteristics, with up to 95% reduction in volumetric wear. Current reports looking at mid-term results (6-9 years follow up) are extremely encouraging, with reported linear wear rates of 0.02 +\/- 0.06mm\/year.4,5<\/sup> No osteolytic lesions in the acetabulum or femur have been described. The decreased wear rates with the use of cross-linked polyethylene may reduce the need for revision arthroplasty by reducing the development of osteolysis and late dislocations. The use of highly cross-linked polyethylene liners offers the surgeon a wide choice of implants with regard to head sizes (28 mm to 40 mm), elevated liners (0-10 \u2013 20 Deg), and offset options (standard or lateralized). The risk of dislocation can be further reduced by the use of a large head with an elevated lip liner.<\/p>\n

Enough experience has been gained following a well-performed metal-on-polyethylene (MOP) total hip replacement to recommend its widespread use. The signs of impending failure are well recognized and timely intervention results in a good outcome.<\/p>\n

Out of the hundreds of thousands of MOP hip replacements performed worldwide, only one case report in the literature describes local granuloma formation secondary to poly wear.<\/sup> However, unlike metal-on-metal articulations, no systemic toxicity has been described. Recent reports about metal hypersensitivity and subsequent tissue necrosis secondary to ALVAL (aseptic lymphocytic vasculitis and associated lesions) have been described. This is thought to be due to a delayed type IV hypersensitivity reaction to the metal ions.7,8<\/sup> Outcomes following revision surgery for failure secondary to ALVAL are poorer compared to revisions for other reasons.<\/sup> A common finding in these patients is soft tissue necrosis, which necessitates the use of constrained prostheses.<\/p>\n

In addition, elevated serum metal ion levels are a constant finding in patients with a metal-on-metal bearing. The long-term consequences of this are not known. Patients with chronic diseases such as chronic renal failure have a poor capacity to excrete cobalt and chromium ions. Increased metal ion levels locally, especially chromium, have been shown to induce chromosomal aberrations. Long-term monitoring studies with serial metal ion levels are in progress.<\/p>\n

With increasing cost control measures now becoming common, the MOP bearing is significantly more cost-effective when compared to newer alternate bearing articulations. Current literature justifies the increased cost of newer and more expensive bearing surfaces in younger patients if a 19% reduction in revision rates can be demonstrated.10<\/sup> Long-term results of the newer metal-on-metal articulations are awaited.<\/p>\n

In young patients, it may be acceptable to explore alternative bearing surfaces, but widespread adoption seems unnecessary as MOP bearings have a proven track record without catastrophic complications. The benefits of alternate bearing surfaces in reducing the rates of revision arthroplasty have not yet been conclusively demonstrated. This is even more important in light of promising clinical and laboratory reports of reduced wear and osteolysis with newer, highly cross-linked ultra high molecular weight polyethylene bearings.<\/p>\n

Reported survivorship for conventional polyethylene varies between 90% at 15 years to over 80% at 20 years. Given the extremely low wear rates with MOP articulations, these survivorship results may be extrapolated to indicate a survivorship in excess of 90% at 25 years.<\/p>\n

All bearings will wear, but by avoiding distant toxicity and high cost, the MOP hip replacement has a good predictable outcome and should outlast most of the patients for whom it is chosen.<\/p>\n

Reprinted with permission from the Summer 2010 issue of COA Bulletin<\/em><\/p>\n

References<\/h3>\n
    \n
  1. Berry DJ, Harmsen WS, Cabanela ME, Morrey BF. Twenty-five-year survivorship of two thousand consecutive primary Charnley total hip replacements: factors affecting survivorship of acetabular and femoral components.<\/em> J Bone Joint Surg Am 2002;84:171-7<\/li>\n
  2. Kim YG, Kim SY, Park BC, Kim PT, Ihn JC, Kim ID. Uncemented Harris-Galante total hip arthroplasty in patients with osteonecrosis of the femoral head. A 10-16-year follow-up study.<\/em> Acta Orthop 2005 Feb;76(1):42-8<\/li>\n
  3. Beaul\u00e9 PE, Campbell P, Mirra J, Hooper JC, Schmalzried TP. Osteolysis in a cementless, second generation metal-on-metal hip replacement.<\/em> Clin Orthop Relat Res. 2001;386:159-65<\/li>\n
  4. McCalden RW, MacDonald SJ, Rorabeck CH, Bourne RB, Chess DG, Charron KD. Wear rate of highly cross-linked polyethylene in total hip arthroplasty; a randomized controlled trial.<\/em> J Bone Joint Surg Am 2009;91:773-782<\/li>\n
  5. Manning DW, Chiang PP, Martell JM, Galante JO, Harris WH. In vivo comparative wear study of traditional and highly cross-linked polyethylene in total hip arthroplasty.<\/em> J Arthroplasty 2005;20:880-6.<\/li>\n
  6. Leigh W, O’Grady P, Lawson EM, Hung NA, Theis JC, Matheson J. Pelvic pseudotumor: an unusual presentation of an extra-articular granuloma in a well-fixed total hip arthroplasty.<\/em> J Arthroplasty 2008;23:934-38<\/li>\n
  7. Davies AP, Willert HG, Campbell PA, Learmonth ID, Case CP. An unusual lymphocytic perivascular infiltration in tissues around contemporary metal-on-metal joint replacements.<\/em> J Bone Joint Surg Am 2005;87:18-27<\/li>\n
  8. Pandit H, Glyn-Jones S, McLardy-Smith P, et al. Pseudotumours associated with metal-on-metal hip resurfacings.<\/em> J Bone Joint Surg Br 2008;90:847-51<\/li>\n
  9. Grammatopoulos G, Pandit H, Kwon YM, et al.Hip resurfacings revised for inflammatory pseudotumour have a poor outcome.<\/em> J Bone Joint Surg Br 2009;91-B:1019-24<\/li>\n
  10. Bozic KJ, Morshed S, Silverstein MD, Rubash HE, Kahn JG. Use of cost-effectiveness analysis to evaluate new technologies in orthopaedics. The case of alternative bearing surfaces in total hip arthroplasty.<\/em> J. Bone Joint Surg Am 2006; 88:706-14
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    The Case for MOP Bearings for All THA Patients Over the past few years, alternative bearing surfaces have been introduced to increase the longevity of the implant and reduce the risk of osteolysis secondary to wear debris. Improvements have resulted in an increased choice of implants for patients and their surgeons. Current demographic trends indicate […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_lmt_disableupdate":"","_lmt_disable":"","_o1_cross_site_relations":[],"_o1_disable_knowledge_graph":"","footnotes":""},"tags":[],"o1_subspecialty":[],"o1_anatomic_region":[],"o1_article_type":[],"class_list":["post-231","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/pages\/231","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/comments?post=231"}],"version-history":[{"count":1,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/pages\/231\/revisions"}],"predecessor-version":[{"id":300,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/pages\/231\/revisions\/300"}],"wp:attachment":[{"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/media?parent=231"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/tags?post=231"},{"taxonomy":"o1_subspecialty","embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/o1_subspecialty?post=231"},{"taxonomy":"o1_anatomic_region","embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/o1_anatomic_region?post=231"},{"taxonomy":"o1_article_type","embeddable":true,"href":"https:\/\/www.orthopaedicsone.com\/viewpoints\/wp-json\/wp\/v2\/o1_article_type?post=231"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}