Survivorship analysis of 3234 primary knee arthroplasties implanted over a 26-year period A study of eight different implant designs N.R. Pradhan a, * , A. Gambhir b , M.L. Porter a a Centre of Hip Surgery, Wrightington Hospital, Hall Lane, Appley Bridge, Wigan WN6 9EP, Lancashire, UK b Department of Orthopaedics, Centre of Hip Surgery, Wrightington Hospital, Hall Lane, Appley Bridge, Wigan WN6 9EP, Lancashire, UK Received 1 November 2003; received in revised form 6 June 2004; accepted 6 June 2005 Abstract We conducted a survivorship analysis of 3234 primary total knee replacements performed at our hospital between 1969 and 1995. Each knee replacement was entered once only. Revision was defined as the end point. Data were collected both from patient records and by postal questionnaire. Eight types of knee prostheses were evaluated with best-case and worst-case scenarios compared over a 5-, 10- and 15-year period. The evidence suggests that the ‘‘Condylar type devices’’ which include the Total Condylar, Press Fit Condylar (PFC), Kinematic, Kinemax and Anatomic Modular Knee (AMK) have very similar survivorship curves and in the main have performed well up to a 10-year period. The LCS mobile bearing knee performed well at 5 years. The earlier design prostheses had a poor result in terms of survivorship and are hence were discontinued. D 2005 Elsevier B.V. All rights reserved. Keywords: Primary total knee replacement 1. Introduction The first knee replacement was performed at our hospital using the Gunston prosthesis in 1969. Since then 3609 primary and revision knee replacements have been per- formed at our hospital up to the end of 1995 using a variety of implants. Some new experimental knee designs such as the Gunston and the Load angle inlay (LAI) were implanted. The choice of prosthesis then was largely dependent on availability of prosthesis and individual surgeon choice. Better understanding of the kinematics of the knee and changes in design led to various knee implants being available. In this study we report on the longevity of the implant survival and observe differences in survival patterns between the commonly used prostheses. 2. Material and methods An existing research database contained a catalogue of total knee replacements. This information was transferred to an access database and modified accordingly to contain finite details of relevant data for our study. A total of 3264 primary knee replacements were performed at our hospital from 1969 to 1995. All relevant data from the patient case notes were collected. A written protocol was produced and followed. If patients were lost to follow-up or had been discharged prior to January 1996, an attempt was made to trace these patient by contacting the General Practitioner and the National Statistical Organisation (NSO) at Southport, UK. Survivorship Analysis using the Kaplan Meier method was used to calculate survivorship curves [2,3]. Failure was defined as any revision procedure or removal of any implants. 0968-0160/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.knee.2005.06.004 * Corresponding author. Tel.: +44 1257256477; fax: +44 1257256461. E-mail addresses: npradhan@bigfoot.com, n.pradhan@wiganlhs-tr.nwest.nhs.uk (N.R. Pradhan). The Knee 13 (2006) 7 – 11 www.elsevier.com/locate/knee