Browsing by Author "Nedopil, Alexander J."

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    A Best-Fit of an Anatomic Tibial Baseplate Closely Parallels the Flexion-Extension Plane and Covers a High Percentage of the Proximal Tibia
    (2021) Nedopil, Alexander J.; Zamora, Tomas; Shelton, Trevor; Howell, Stephen M.; Hull, Maury
    There are no reports of in vivo internal-external (I-E) rotational alignment and coverage of the proximal tibia after performing a best-fit method of an anatomically designed and asymmetrically shaped tibial baseplate during calipered kinematically aligned (KA) total knee arthroplasty (TKA). We hypothesized that a best-fit plane sets the anterior-posterior (A-P) axis of the anatomic baseplate closely parallel to the flexion-extension (F-E) plane of the knee and covers a high percentage of the proximal tibia. A total of 145 consecutive primary TKAs were prospectively collected. The calipered KA method and verification checks set the positions and orientations of the components without ligament release in all knees without restrictions on the preoperative deformities. A best-fit method selected one of six trials of anatomic baseplates that maximized coverage and set I-E rotation parallel to and within the cortical edge of the proximal tibia. The angle between the transverse axes of the components (i.e., the deviation of the A-P axis of the anatomic baseplate from the F-E plane of the native knee) and the cross-sectional area (CSA) of the proximal tibia were measured on postoperative computerized tomographic scans. The mean deviation of the anatomic baseplate from the F-E plane was 2-degree external +/- 5degrees. The mean coverage of the proximal tibia was 87 +/- 6% (CSA of baseplate from the manufacturer/CSA of proximal tibiax100). The anatomic baseplate and best-fit method adequately set I-E rotation of the baseplate closely parallel to the F-E plane of the knee and cover a high percentage of the proximal tibia.
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    Six Commonly Used Postoperative Radiographic Alignment Parameters Do Not Predict Clinical Outcome Scores after Unrestricted Caliper-Verified Kinematically Aligned TKA
    (2022) Dhaliwal, Anand; Zamora, Tomas; Nedopil, Alexander J.; Howell, Stephen M.; Hull, Maury L.
    Background: Unrestricted caliper-verified kinematically aligned (KA) TKA restores patient's prearthritic coronal and sagittal alignments, which have a wide range containing outliers that concern the surgeon practicing mechanical alignment (MA). Therefore, knowing which radiographic parameters are associated with dissatisfaction could help a surgeon decide whether to rely on them as criteria for revising an unhappy patient with a primary KA TKA using MA principles. Hence, we determined whether the femoral mechanical angle (FMA), hip-knee-ankle angle (HKAA), tibial mechanical angle (TMA), tibial slope angle (TSA), and the indicators of patellofemoral tracking, including patella tilt angle (PTA) and the lateral undercoverage of the trochlear resection (LUCTR), are associated with clinical outcome scores. Methods: Forty-three patients with a CT scan and skyline radiograph after a KA TKA with PCL retention and medial stabilized design were analyzed. Linear regression determined the strength of the association between the FMA, HKA angle, PTS, PTA, and LUCTR and the forgotten joint score (FJS), Oxford knee score (OKS), and KOOS Jr score obtained at a mean of 23 months. Results: There was no correlation between the FMA (range 2 degrees varus to -10 degrees valgus), HKAA (range 10 degrees varus to -9 degrees valgus), TMA (range 10 degrees varus to -0 degrees valgus), TSA (range 14 degrees posterior to -4 degrees anterior), PTA (range, -10 degrees medial to 14 degrees lateral), and the LUCTR resection (range 2 to 9 mm) and the FJS (median 83), the OKS (median 44), and the KOOS Jr (median 85) (r = 0.000 to 0.079). Conclusions: Surgeons should be cautious about using postoperative FMA, HKAA, TMA, TSA, PTA, and LUCTR values within the present study's reported ranges to explain success and dissatisfaction after KA TKA.
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    Which Asymmetric Tibial Component Is Optimally Designed for Calipered Kinematically Aligned Total Knee Arthroplasty?
    (2022) Nedopil, Alexander J.; Zamora, Tomas; Delman, Connor; Howell, Stephen M.; Hull, Maury L.
    Calipered kinematically aligned (KA) total knee arthroplasty (TKA) restores the patient's prearthritic joint lines and sets internal-external rotation of the tibial component parallel to the flexion-extension (FE) plane, which is not a mechanical alignment (MA) target. Two asymmetric tibial components designed for MA set the tibial component to either a femoral component (FC) target or a tibial tubercle (TT) target. The study determined the optimal asymmetric tibial component to use with KA as the one with smaller IE deviation from the MA target, greater coverage of tibial resection, and lower incidence of cortical overhang. The study included 40 patients treated with bilateral calipered KA TKA with different asymmetric tibial components in opposite knees. A best-fit of a kinematic tibial template to the tibial resection set the template's slot parallel to the knee's FE plane. Each asymmetric tibial component's anterior-posterior (AP) axis was set parallel to the slot. Computer tomography analysis determined the IE deviation (-internal/+external) of each tibial component from its MA target, tibial resection coverage by the baseplate and insert, and incidence of cortical overhang. The patient-reported Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) determined outcomes. The mean IE deviation from the MA target was 2 degrees external for the FC-target asymmetric tibial component and -8 degrees internal for the TT-target asymmetric tibial component ( p <0.001). Tibial resection coverage by the baseplate (insert) was 88% (84%) for the FC target and 84% (79%) for the TT target ( p <0.001 for baseplate and insert). The FC target insert covered 3mm more of the posterolateral resection ( p <0.001). Posteromedial coverage was comparable. The incidence of cortical overhang was 2.5% for each baseplate. There was no difference in FJS and OKS. When performing calipered KA, the more optimal design was the asymmetric tibial component with the FC target because of the smaller deviation from its MA target and the greater coverage of the tibial resection by the baseplate and insert.