A comparison of alignment using patient specific guides, computer navigation and conventional instrumentation in total knee arthroplasty Samuel J. MacDessi a, ⁎, Bob Jang a , Ian A. Harris b , Emma Wheatley c , Carl Bryant c , Darren B. Chen a a Sydney Knee Specialists, St George Private Hospital, Sydney, NSW, Australia b South Western Sydney Clinical School, University of New South Wales, Australia c Bryant Radiology, St George Private Hospital, Sydney, NSW, Australia abstract article info Article history: Received 25 July 2013 Received in revised form 23 September 2013 Accepted 6 November 2013 Keywords: Patient specific guides Alignment Conventional Background: Patient specific guides (PSG) have been introduced as a tool in total knee arthroplasty (TKA) in an attempt to improve limb alignment and reduce operative time compared to other established surgical tech- niques. The purpose of this study was to compare the post-operative radiographic alignment and operative time in patients who underwent TKA surgery with PSG, conventional instrumentation or computer-assisted nav- igation surgery using fully cemented components. Methods: A cohort of 260 patients who underwent TKA surgery using PSG (PSG group, n = 115) was compared to patients who underwent TKA using either conventional instrumentation (CON group, n = 92) or computer- assisted navigation (CAS group, n = 53). Post-operative CT imaging using the Perth CT protocol was used to compare alignment between the three groups. Results: In the PSG and CAS groups, the post-operative hip–knee angle (HKA) was within 3° of neutral alignment in 91.3% and 90.7% of patients, respectively. This compared to 80.4% of patients in the CON group (p = 0.02). There were no significant differences with respect to alignment when comparing individual component position- ing between the PSG and CAS groups apart from tibial slope (Table 3). Total operative time was found to be sig- nificantly reduced in the PSG group (80.2 min) compared to both the CON group (86 min, p = 0.002) and the CAS group (110.2 min, p b 0.0001). Conclusions: The use of PSG resulted in similar alignment accuracy to CAS and superior alignment to CON with significantly shorter operative times. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Patient-specific guides (PSG) derived from pre-operative imaging have been recently introduced as a new strategy for improving compo- nent positioning in total knee arthroplasty (TKA). The other cited bene- fits of these instruments when compared to computer navigation are reduced operative times and inventory in the operating room; both of which may result in cost savings [1–3]. Most major orthopaedic implant manufacturers have introduced different versions of patient-specific guides. These guides rely on either magnetic resonance imaging (MRI), computed tomography (CT) scans with or without long alignment radiographs to produce moulds that conform to the patient's anatomy during surgery, using pre-defined ra- diographic parameters to restore a neutral mechanical alignment to the lower limb. Despite these guides being available for several years, there is a pau- city of data on their accuracy. The few studies available have only looked at plain radiographic outcomes of coronal alignment, with mixed results [4–7]. This is in contrast to the literature evaluating the accuracy of computer-assisted navigation (CAS) surgery, with significant evidence validating CAS as being more accurate than conventional instrumented (CON) techniques by reducing the number of alignment outliers [8–11]. Like other studies on this topic, only coronal plane alignment had been assessed. In addition, no published data exists on comparing the accuracy of patient-specific guides against both conventional instru- mentation and computer-assisted navigation surgery. The aim of this paper is to compare the differences in alignment ac- curacy in patients who have undergone TKA using patient specific guides, conventional instrumentation, or computer-assisted navigation to see which method provides the best alignment accuracy. This is to be determined by examining the post-operative coronal, sagittal and axial alignment and comparing the alignment outliers between the groups. 2. Materials and methods A cohort of patients who underwent TKA surgery using PSG (PSG group) was compared to patients who underwent TKA using either conventional instrumentation (CON group) or computer-assisted The Knee 21 (2014) 406–409 ⁎ Corresponding author at: Sydney Knee Specialists, Suite 8, 19 Kensington St, Kogarah NSW 2217, Australia. Tel.: +61 2 8307 0333; fax: +61 2 8307 0334. E-mail address: samuelmacdessi@sydneyknee.com.au (S.J. MacDessi). 0968-0160/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.knee.2013.11.004 Contents lists available at ScienceDirect The Knee