Is TKA Using Patient-specific Instruments Comparable to Conventional TKA? A Randomized Controlled Study of One System

Abstract

Background Patient-specific CT-based instrumentation may reduce implant malpositioning and improve alignment in TKA. However, it is not known whether this innovation is an advance that benefits patients. Questions/purposes We evaluated (1) the precision of patient-specific TKA by comparing the incidence of outliers in postoperative alignment between TKAs using patientspecific instruments and TKAs using conventional instruments, and (2) the reliability of patient-specific instruments by intraoperatively investigating whether the surgery could be completed with patient-specific instruments alone.Methods In this randomized controlled trial, we compared patient-specific TKA instruments from one manufacturer (n = 50) with conventional TKA instruments (n = 50). Postoperative hip-knee-ankle angles, femoral component rotation, and coronal and sagittal alignments of each component were measured. The validity of the patient-specific instrument was examined using crosschecking procedures with conventional instruments during the surgeries. When the procedure could not be completed accurately with patient-specific instruments, the procedure was converted to TKA using conventional instruments, and the frequency of this occurrence was tallied.

Patient-specific computed tomography based instrumentation in total knee arthroplasty: a prospective randomized controlled study

“…As a result, the necessity of performing further high-quality investigations has been previously emphasised by other authors [14,17]. Our study was designed to verify the utility of CT-based Signature™ PSI for precise implant positioning.…”

“…In general, results of studies on PSI are equivocal [8,15,[25][26][27][28]. We believe that results obtained with one particular PSI system are not automatically applicable to other systems and should not be generalised [14,23]. At the moment, several companies offer various PSI systems for TKA.…”

“…In all cases, the same type of uncemented cruciate-retaining prostheses were implanted (Vanguard™ Complete Knee System; Biomet Inc. Warsaw, IN, USA), without resurfacing the patella. The process by which Signature™ instrumentation is produced and used has been described precisely in previous studies [3,13,14,[21][22][23]. Briefly, each patient in group 1 obtained a preoperative CT scan of the knee joint, along with …”

“…One particular modern solution for knee arthroplasty involves systems in which intraoperative navigation is based on single-use guides fashioned for the specific patient. The main idea behind patient-specific instrumentation (PSI) is that knee-joint arthroplasty procedures can be individualised, with benefits including precise realignment of the normal mechanical axis of the operated lower limb, minimised resection of the patient's bony tissue, reduced surgical times, simplified instrumentation, reduced peri-and postoperative blood loss, no need of femoral medullary cavity reaming and a reduced rate of thromboembolic complications [3,[13][14][15][16]. A recently published survey showed a considerable interest in PSI among surgeons, confirmed by the massively increasing numbers of PSI-aided procedures performed in Europe and worldwide; PSI use for TKA increased globally by an average of 1.5 times between 2011 and 2012 [17].…”

“…In the case of CT-based PSI instrumentation, this need is particularly evident, as there is very limited experience with these devices in the world literature. To our knowledge, this is the fifth study to assess radiographic outcomes of TKA performed with CTbased PSI [14,[18][19][20]. The aim of this study was to compare radiological results of TKAs performed with CT-based PSI and conventional technique.…”