Computer-Assisted Navigation Increases Precision of Component Placement in Total Knee Arthroplasty

Background Computer navigation has improved accuracy and reduced the percentage of alignment outliers in TKA. However, the characteristics of outliers and the risk factors for limb malalignment after TKA are still unclear. Questions/Purposes We therefore addressed the following questions: (1) What is the incidence and characteristics of outliers for postoperative limb mechanical axis (hip-knee-ankle [HKA] angle outside the conventional 180°± 3°range) and component alignment in TKA? And (2) what are the preoperative clinical or radiographic risk factors for limb mechanical axis malalignment in TKA? Methods We retrospectively reviewed the clinical and radiographic records of 1500 computer-assisted TKAs to identify outliers for postoperative HKA axis and component alignment and determined risk factors for malalignment. Full-length hip-to-ankle and knee radiographs were used to measure preoperative HKA angle, femoral coronal bowing, joint divergence angle, tibial subluxation, and tibial bone loss and postoperative HKA angle and femoral and tibial component angle. Results The incidence of outliers for postoperative limb mechanical axis, femoral component alignment, and tibial component alignment was 7% (112 of 1500 TKAs), 7%, and 8%, respectively, with 70% of limbs placed in excessive varus and 30% in excessive valgus. Preoperative varus deformity of more than 20°and femoral bowing of more than 5°were associated with increased risk of placing the limb mechanical axis outside the acceptable ± 3°range after computer-assisted TKA. Conclusions The presence of preoperative radiographic risk factors should alert the surgeon to increased chance of malalignment and every measure should be undertaken in such at-risk knees to ensure proper limb and component alignment and soft tissue balance.

Section: Discussioncontrasting

confidence: 66%

Which Factors Increase Risk of Malalignment of the Hip-Knee-Ankle Axis in TKA?

Mullaji

Shetty

Lingaraju

et al. 2013

“…We identified 13 clinical series for comparison with the current navigation series (Table 2). Seven studies were prospective, randomized studies [1,7,23,25,28,29,34] and six were retrospective case-control series [2,12,17,[20][21][22]. We compared the characteristics of the patients and the radiographic results of the current case series with those in the literature.…”

Section: Methodsmentioning

confidence: 99%

“…However, some authors agree this objective may not be practically obtainable in every TKA [15]. Satisfactory position of a TKA prosthesis is commonly accepted to be an alignment within 3°from this ideal [1,6,7,12,17,18,22,23,28,33]. Aseptic loosening of the prosthesis has been reported to be more common in knees implanted in an alignment greater than 3°varus [26].…”

Section: Introductionmentioning

confidence: 99%

“…Because many studies regarding this subject have been performed in high-volume tertiary referral centers, there is concern whether similarly good results can be obtained by the average orthopaedic surgeon [3]. Despite the fact that radiographic alignment of the implanted prosthesis is superior in computer navigation TKA, outliers greater than 3°are still unavoidable in most of the reported series [1,7,8,12,17,22,23]. The potential reasons leading to these outliers are not discussed in adequate detail in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Computer Navigation Did Not Improve Alignment in a Lower-volume Total Knee Practice

Yau

Chiu

Zuo

et al. 2008

Postoperative alignment of the implanted prosthesis in computer-navigated TKA has been reported to be superior to that using the conventional technique. There is an assumption that use of computer navigation techniques can make an inexperienced or occasional TKA surgeon perform more like an expert TKA surgeon. To assess improved accuracy in recreation of mechanical alignment in TKA performed using computer navigation, a retrospective review of the experience of one of the authors (WPY) before and after using computer navigation was performed. We reviewed the radiographic results of 104 TKAs (52 computer navigation, 52 conventional technique) and found the accuracy of postoperative radiographic alignment of the implanted prosthesis was not improved by using computer navigation as judged by (1) overall limb alignment (case: varus 1.3°; control: varus 0.3°); (2) femoral component alignment (case: 90.3°; control: 90.3°); and (3) tibial component alignment (case: 89°; control: 90°). Significant factors that affected postoperative overall mechanical alignment in the current navigation series included severity of the preoperative deformity, amount of error in making bone cuts, and experience of the surgeon in using the computer navigation system. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

“…Computer-assisted navigation offers considerable improvement for more reliably achieving lower extremity alignment than conventional instrumented TKA techniques [1,4,5,7,12,17,19,21]. The importance of this new technique is underscored by the potential for early TKA failure if the surgeon does not create neutral alignment within 3°of the mechanical axis [9,16].…”

Section: Introductionmentioning

confidence: 99%

Femoral Shaft Fracture Resulting From Femoral Tracker Placement in Navigated TKA

Bonutti

Dethmers

Stiehl

2008

Computer-assisted navigation is a surgical tool that may decrease malalignment outliers in TKA. With any new surgical technique, there is the possibility of unexpected complications that raise caution. We report two patients with displaced femoral fractures at optical tracker pin placement sites created for routine performance of navigated TKA. Our experience suggests single bicortical 5-mm pins placed in the femoral shaft have the added risk of creating a stress riser leading to the potential for fracture. Females may have a higher risk for this complication. We believe bicortical pin fixation in the femur or tibia no longer is indicated.