Improved Accuracy of Alignment With Patient-specific Positioning Guides Compared With Manual Instrumentation in TKA

Abstract

Background Coronal malalignment occurs frequently in TKA and may affect implant durability and knee function. Designed to improve alignment accuracy and precision, the patient-specific positioning guide is predicated on restoration of the overall mechanical axis and is a multifaceted new tool in achieving traditional goals of TKA. Questions/purposes We compared the effectiveness of patient-specific positioning guides to manual instrumentation with intramedullary femoral and extramedullary tibial guides in restoring the mechanical axis of the extremity and achieving neutral coronal alignment of the femoral and tibial components. Methods We retrospectively reviewed 569 TKAs performed with patient-specific positioning guides and 155 with manual instrumentation by two surgeons using postoperative long-leg radiographs. For all patients, we assessed the zone in which the overall mechanical axis passed through the knee, and for one surgeon's cases (105 patient-specific positioning guide, 55 manual instrumentation), we also measured the hip-knee-ankle angle and the individual component angles with respect to their mechanical axes. Results The overall mechanical axis passed through the central third of the knee more often with patient-specific positioning guides (88%) than with manual instrumentation (78%). The overall mean hip-knee-ankle angle for patient-specific positioning guides (180.6°) was similar to manual instrumentation (181.1°), but there were fewer ± 3°hip-knee-ankle angle outliers with patient-specific positioning guides (9%) than with manual instrumentation (22%). The overall mean tibial (89.9°versus 90.4°) and femoral (90.7°versus 91.3°) component angles were closer to neutral with patient-specific positioning guides than with manual instrumentation, but the

The Mark Coventry Award: Custom Cutting Guides Do Not Improve Total Knee Arthroplasty Clinical Outcomes at 2 Years Followup

“…Our study supports prior studies demonstrating CCGs to confer no additional benefit in achieving a neutral mechanical alignment postoperatively [10,17,28,41]. Again, although prior reports to this regard are mixed [23,24], CCGs do not consistently demonstrate a radiological advantage. However, this study solely focused on measurement of alignment in the coronal plane and not sagittal or rotational alignment as has been previously reported [40].…”

“…Numerous potential benefits of CCGs exist compared with both standard and computer-assisted surgical instrumentation, including their ease of use; a decrease in operative times and instrument trays; the ability to preoperatively plan for component size, alignment, and position; and an improvement in postoperative alignment versus the use of standard alignment methods [4,18,23]. However, to date the majority of reports have not confirmed these proposed benefits [6,11,33,37,39,41].…”

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

“…Indeed, as hypothesized there was a substantial difference in the number of knees ±3°beyond the ideal alignment (21.2 % for the SI group, 9.3 % for the PMCB group). Our rates with PMCB compare favorably to the average 10.2 % rate resulting from computer-assisted navigation in prior studies, and substan- tially improves on the 28.2 % rate encountered with conventional instrumentation [30]. An overview of studies reporting frontal plane alignment within this range for both conventional instrumentation and PMCB are provided in Tables 3 and 4.…”

“…To avoid these complications, achieving a postoperative alignment within the range of 0°±3°of the mechanical axis is recommended [20,33]. Manual intramedullary/extramedullary guides are not thought to be capable of consistently achieving axes in this range [30,41], and though computer-assisted navigation has shown superior results in comparison with conventional instrumentation [30], it is also limited by increased surgical times and no clear superiority in improving short-term clinical outcomes [8].…”

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength

“…HKAs with a positive value were in varus and those with a negative value were in valgus. The coronal alignment of the femoral and tibial components in the frontal plane was also measured (Figure 2), with the femoral component angle being defined as the angle medially between the distal surfaces of the femoral component and the femoral mechanical axis, and the tibial component angle being defined as the medial angle between the tibial component plateau and the tibial mechanical axis (Ng et al 2012). The measurements were performed using a radiology viewer (Cedara I-Reach 4.4; Cedara Software Corp., Mississauga, ON, Canada).…”