Computer-assisted Total Knee Arthroplasty Using Patient-specific Templating

Abstract

Current techniques used for total knee arthroplasty rely on conventional instrumentation that violates the intramedullary canals. Accuracy of the instrumentation is questionable, and assembly and disposal of the numerous pieces is time consuming. Navigation techniques are more accurate, but their broad application is limited by cost and complexity. We aimed to prove a new concept of computer-assisted preoperative planning to provide patient-specific templates that can replace conventional instruments. Computed tomography-based planning was used to design two virtual templates. Using rapid prototyping technology, virtual templates were transferred into physical templates (cutting blocks) with surfaces that matched the distal femur and proximal tibia. We performed 45 total knee arthroplasties on 16 cadaveric and 29 plastic knees, including a comparative trial against conventional instrumentations. All operations were performed using patient-specific templates with no conventional instrumentations, intramedullary perforation, tracking, or registration. The mean time for bone cutting was 9 minutes with a surgical assistant and 11 minutes without an assistant. Computer-assisted analyses of six random computed tomography scans showed mean errors for alignment and bone resection within 1.7 degrees and 0.8 mm (maximum, 2.3 degrees and 1.2 mm, respectively). Patient-specific templates are a practical alternative to conventional instrumentations, but additional clinical validation is required before clinical use.

A comparison of conventional and patient-specific instruments in total knee arthroplasty

“…With 90.7 % of knees in the current analysis within the ideal range, our results can be considered amongst the best yet noted. They are in line with other studies of PSI which reported improved alignment [16,30,38]. Although it should be noted that other studies have failed to show a clear advantage for PSI technology [24,32], and that one study with the technology employed in the current analysis observed only a fair rate of accuracy, with higher risk of error >3°in the sagittal plane [11], there does appear to be an overall trend for the superiority of these new technologies over earlier instrumentation methods.…”

“…Patient-specific instrumentation (PSI), which uses anatomical data obtained primarily from pre-operative axial computed tomography (CT) or magnetic resonance imaging (MRI) to create disposable cutting jigs individualized to the patient's unique anatomy, was created with this goal [16].…”

Patient-Specific Modelling in Orthopedics: From Image to Surgery

“…Since then, the number of applications has grown drastically, both in academic and industrial environments. One can now find patient-specific guides for various surgical procedures such as total knee replacement (Hafez et al 2006, Lombardi et al 2008, total hip replacement (Hananouchi et al 2009), hip surface replacement , Raaijmaakers et a. 2010, Kunz et al 2010, intra-and extraarticular radius malunions (Leong et al 2010, Oka et al 2008, and distal femur osteotomy (Victor et al 2011), Fig.…”

“…It can also visually guide a surgical gesture such as the impaction of a hip implant (Blemker et al 2007). It can fully replace a standard instrument, becoming for example a patient-specific cutting block for total knee replacement (Hafez et al 2006). Finally, it can be left in the body, becoming a guiding implant to reposition bone fragments for periacetabular osteotomy (Anaya et al 2011) or distal radius osteotomy (Oka et al 2010).…”

“…This is demonstrated by the routine use of Signature™ (Biomet), Patient Specific Instruments ®(Zimmer), OtisKnee™ (OtisMed), VISIONAIRE™ (Smith & Nephew), PROPHECY ™ (Wright) or TruMatch™ (Depuy) for high number of surgeries. The main goal there is to reduce the OR time and to avoid using intramedullar instruments, which also decreases the risk of infection (Hafez et al 2006). Without the use of a CAS system, a TKR procedure is generally performed in three steps: imaging (e.g.…”