Positioning of total knee arthroplasty with and without navigation support

Background Tibiofemoral forces are important in the design and clinical outcomes of TKA. We developed a tibial tray with force transducers and a telemetry system to directly measure tibiofemoral compressive forces in vivo. Knee forces and kinematics traditionally have been measured under laboratory conditions. Although this approach is useful for quantitative measurements and experimental studies, the extrapolation of results to clinical conditions may not always be valid. Questions/purposes We therefore developed wearable monitoring equipment and computer algorithms for classifying and identifying unsupervised activities outside the laboratory. Methods Tibial forces were measured for activities of daily living, athletic and recreational activities, and with orthotics and braces, during 4 years postoperatively. Additional measurements included video motion analysis, EMG, fluoroscopic kinematic analysis, and ground reaction force measurement. In vivo measurements were used to evaluate computer models of the knee. Finite element models were used for contact analysis and for computing knee kinematics from measured knee forces. A thirdgeneration system was developed for continuous monitoring of knee forces and kinematics outside the laboratory using a wearable data acquisition hardware. Results By using measured knee forces and knee flexion angle, we were able to compute femorotibial AP translation (À12 to +4 mm), mediolateral translation (À1 to 1.5 mm), axial rotation (À3°to 12°), and adduction-abduction (À1°t o +1°). The neural-network-based classification system was able to identify walking, stair-climbing, sit-to-stand, and stand-to-sit activities with 100% accuracy. Conclusions Our data may be used to improve existing in vitro models and wear simulators, and enhance prosthetic designs and biomaterials.

Section: Intraoperative Usementioning

confidence: 99%

“…Current-generation computer-aided surgical navigation systems cannot directly address soft-tissue balance and knee tightness [48,50,51]. An instrumented tibial prosthesis can enhance the value of such navigation tools in achieving reproducible clinical outcomes.…”

Section: Intraoperative Usementioning

confidence: 99%

The 2011 ABJS Nicolas Andry Award: ‘Lab’-in-a-Knee: In Vivo Knee Forces, Kinematics, and Contact Analysis

D’Lima

Patil

Steklov

et al. 2011

“…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%

“…If an outlier in the lower limb mechanical alignment is defined as greater than 3°from the neutral position, the majority of the TKA series performed using the conventional jig-based technique reported a satisfactory alignment rate of approximately 70% [1-3, 5-10, 12, 13, 16-24, 28, 29, 31-34]. However, the results of most of the computer navigation TKA series were much more favorable, reporting satisfactory alignment of 90% to 100% [1,17,22,23,28,29,34]. Some surgeons have suggested this improved predictability of postoperative radiographic alignment with computer navigation TKA occurs with experienced and inexperienced surgeons [30].…”

Section: Introductionmentioning

confidence: 99%

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.