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J R Soc Med. 1992 April; 85(4): 208–210.
PMCID: PMC1294725

The Ring total knee replacement--a comparison of survivorship.


Long term results of joint replacement are frequently expressed as survivorship; it therefore becomes increasingly important to have the ability to make valid comparisons between survivorship tables in order to determine accurately the statistical significance of published differences. We present a statistical method for direct comparison of survivorship tables. We have applied this technique to evaluate the survivorship of the unconstrained, uncemented Ring total knee replacement first implanted in 1975 and compare this to contemporaneous constrained prostheses. There is a significant improvement in survival, which suggests a beneficial long-term effect on the bone/implant interface of this changing design concept.

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Selected References

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  • Tew M, Waugh W. Estimating the survival time of knee replacement. J Bone Joint Surg Br. 1982;64(5):579–582. [PubMed]
  • Lettin AW, Kavanagh TG, Craig D, Scales JT. Assessment of the survival and the clinical results of Stanmore total knee replacements. J Bone Joint Surg Br. 1984 May;66(3):355–361. [PubMed]
  • Kershaw CJ, Themen AE. The Attenborough knee. A four- to ten-year review. J Bone Joint Surg Br. 1988 Jan;70(1):89–93. [PubMed]
  • Mantel N. Evaluation of survival data and two new rank order statistics arising in its consideration. Cancer Chemother Rep. 1966 Mar;50(3):163–170. [PubMed]
  • Ring PA. Uncemented surface replacement of the knee joint. Clin Orthop Relat Res. 1980 May;(148):106–111. [PubMed]
  • Reissis N, Dendrinos G, Reissis E, Ring PA. The Ring total knee replacement. Arch Orthop Trauma Surg. 1988;107(5):309–315. [PubMed]
  • Dorey F, Amstutz HC. The validity of survivorship analysis in total joint arthroplasty. J Bone Joint Surg Am. 1989 Apr;71(4):544–548. [PubMed]
  • Hungerford DS, Krackow KA. Total joint arthroplasty of the knee. Clin Orthop Relat Res. 1985 Jan-Feb;(192):23–33. [PubMed]

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