No evidence of superiority in reducing outliers of component alignment for patient-specific instrumentation for total knee arthroplasty: a systematic review.

Patient-specific instrumentation (PSI) technology has been developed to improve alignment when implanting total knee arthroplasty (TKA) and is a new focus in the orthopaedic community. Current controversial data concerning PSI are discussed. A systematic review to compare PSI with conventional instrumentation and assess the radiographic outcomes was performed. Electronic databases (including PubMed, Medline, Embase, the Cochrane Library and the Science Citation Index database) and conference proceedings from 1950 to 2014 in the English language were searched. Data, including relevant patient characteristics, sample size, radiographic method, PSI system manufacturer and outliers of implant positioning and alignment on radiography were independently extracted from all eligible studies by two of the authors. A total of 2739 TKAs were included (1410 performed with PSI and 1329 with conventional instrumentation). There were more TCA outliers (malalignment >3°) and tibial slope outliers (malalignment >3°) in the PSI group than in the conventional group. The other radiographic outcomes assessed, including coronal, sagittal or rotational alignment outliers did not differ between the two groups. With regard to radiographic outcomes, our findings indicate that PSI technology is not superior in reducing outliers of component alignment.