Evolution et évaluation de l'alignement dans les prothèses totales de genou

Total Knee Arthroplasty (TKA) is a common orthopedic procedure. When performing a TKA, the aim was to achieve a systematic 180° mechanical alignment (MA). This technique results in a straight limb, reducing joint stress and ultimately improving implant survival. Despite technological advances, the results of TKA remain imperfect. Although long-term survival is very good, up to 20% of patients are not satisfied with their prosthesis. In an attempt to improve these results, new personalized implant alignment proposals have been developed. We started by trying to better understand the coronal femoro-tibial alignment of an osteoarthritic population by showing its important individual variation and its differences with a non-osteoarthritic population. We then detailed the different possibilities of personalized alignment. The goal of kinematic alignment (KA) is to restore the anatomy and soft-tissue balance of the pre-arthritic knee using bony landmarks. Functional alignment, which is only possible with robotic assistance, adapts intraoperatively the positioning of prosthetic implants according to the constitutional anatomy and ligament laxity. We performed a systematic review comparing the results after TKA between KA and MA. KA appeared to be a feasible alternative technique to MA. A new CPAK radiological classification of KA was described considering the coronal alignment and the joint line obliquity following TKA. We compared the coronal alignment obtained with this method to distractive valgus stress radiographs compensating for cartilage wear and ligament laxity. We found similar results indicating that KA assessed with the CPAK classification would anticipate functional alignment for the knee extension space. We compared clinical outcomes after TKA based on whether the different categories of the CPAK classification were restored. We found that MA does not restore the knee phenotype in most cases. Also, we showed less postoperative pain when the joint line obliquity after TKA was maintained compared to preoperatively. Finally, most studies presenting the results of TKA with KA are performed with prostheses that preserve the posterior cruciate ligament. However, we use a posterior-stabilized (PS) TKA. We therefore compared the results between MA and KA using a PS TKA with a plot-cam system. We found an increased risk of aseptic tibial loosening in the kinematic group potentially explained by shear forces exerted on the tibial plot. Several studies have assessed patient walking in order to have a more objective examination of the functional recovery after TKA. The aim was to assess recovery by a gait pattern that resembles closely that of a native knee. We initiated a prospective randomized study comparing gait analysis in medial-pivot TKA patients with MA versus KA. The objectives were to compare the gait analysis, clinical and radiological results for 52 TKRs in each group at a minimum follow-up of 12 months. Thus, we showed that KA resulted in good clinical and radiological outcomes. The KA determined from bone landmarks seems to correspond to the functional alignment in extension. On the other hand, robotic assistance allowed us to realize that ligament behavior was different in flexion and that KA did not achieve good ligament balancing in flexion in all cases. The evaluation of the gait pattern after TKA implanted with robotic assistance according to the functional alignment would be interesting.La prothèse totale de genou (PTG) est une intervention fréquente en orthopédie. Lors de la réalisation de la PTG, l’objectif était d’obtenir un alignement mécanique (AM) systématique à 180°. Cette technique permet d’obtenir un membre rectiligne diminuant les contraintes articulaires et in fine améliorant la survie des implants. Malgré les avancées technologiques, les résultats des PTG restent imparfaits. Bien que la survie soit très bonne à long terme, jusqu’à 20% des patients ne sont pas satisfaits de leur prothèse. Pour tenter d’améliorer ces résultats, de nouvelles propositions personnalisées d’alignement des implants ont été développées. Nous avons commencé par essayer de mieux comprendre l’alignement coronal fémoro-tibial d’une population arthrosique en montrant son importante variation individuelle et ses différences avec une population non arthrosique. Nous avons ensuite détaillé les différentes possibilités d’alignement personnalisé. Le but de l’alignement cinématique (AC) est de restaurer l’anatomie et l’équilibrage du genou pré-arthritique à partir de repères osseux. L’alignement fonctionnel, possible avec assistance robotique, adapte en peropératoire le positionnement des implants prothétiques selon l’anatomie et la laxité ligamentaire constitutionnelles. Nous avons réalisé une revue systématique comparant les résultats après PTG entre AC et AM. L’AC apparaissait comme une technique envisageable et alternative à l’AM. Une nouvelle classification radiologique CPAK d’AC a été décrite considérant l’alignement coronal et l’obliquité de l’interligne après PTG. Nous avons comparé l’alignement coronal obtenu avec cette méthode à des radiographies dynamiques en valgus compensant l’usure cartilagineuse et la laxité ligamentaire. Nous avons trouvé des résultats similaires indiquant que l’AC évalué avec la classification CPAK permettrait d’anticiper l’alignement fonctionnel sur l’espace en extension du genou. Nous avons comparé les résultats cliniques après PTG en fonction de la restauration ou non des différentes catégories de la classification CPAK. Nous avons trouvé que l’AM ne restaure pas le phénotype du genou dans la majorité des cas. Aussi, nous avons montré moins de douleurs post opératoires lorsque l’interligne après PTG était maintenue par rapport au préopératoire. Enfin, la majorité des études présentant les résultats de PTG avec AC sont réalisées avec des prothèses à conservation du ligament croisé postérieur. Or, nous utilisons une PTG postéro-stabilisée (PS). Nous avons donc comparé les résultats entre AM et AC en utilisant une PTG PS par un système plot-came. Nous avons trouvé un risque augmenté de descellement tibial aseptique dans le groupe cinématique potentiellement expliqué par des forces de cisaillement exercées sur le plot tibial. Plusieurs études ont évalué le schéma de marche des patients afin d’obtenir un examen plus objectif sur la récupération fonctionnelle en post opératoire de prothèses de genou. L’objectif était d’évaluer la récupération d’un schéma de marche le plus proche possible de celui d’un genou natif. Nous avons initié une étude prospective randomisée comparant l’analyse de la marche chez des patients opérés de PTG type « medial-pivot » avec AM versus AC. Les objectifs étaient de comparer l’analyse de la marche, les résultats cliniques et radiologiques pour 52 PTG dans chaque groupe à un recul minimum de 12 mois. Nous avons donc montré que l’AC permettait d’obtenir de bons résultats cliniques et radiologiques. L’AC déterminé à partir de repères osseux semble correspondre à l’alignement fonctionnel en extension. En revanche, l’assistance robotique nous a permis de réaliser que le comportement ligamentaire était différent en flexion et que l’AC ne permettait pas d’obtenir un bon équilibrage ligamentaire en flexion dans tous les cas. L’évaluation du schéma de marche après PTG implantées avec assistance robotique selon l’alignement fonctionnel serait intéressante

Evolution and assessment of alignment for total knee arthroplasties

La prothèse totale de genou (PTG) est une intervention fréquente en orthopédie. Lors de la réalisation de la PTG, l’objectif était d’obtenir un alignement mécanique (AM) systématique à 180°. Cette technique permet d’obtenir un membre rectiligne diminuant les contraintes articulaires et in fine améliorant la survie des implants. Malgré les avancées technologiques, les résultats des PTG restent imparfaits. Bien que la survie soit très bonne à long terme, jusqu’à 20% des patients ne sont pas satisfaits de leur prothèse. Pour tenter d’améliorer ces résultats, de nouvelles propositions personnalisées d’alignement des implants ont été développées. Nous avons commencé par essayer de mieux comprendre l’alignement coronal fémoro-tibial d’une population arthrosique en montrant son importante variation individuelle et ses différences avec une population non arthrosique. Nous avons ensuite détaillé les différentes possibilités d’alignement personnalisé. Le but de l’alignement cinématique (AC) est de restaurer l’anatomie et l’équilibrage du genou pré-arthritique à partir de repères osseux. L’alignement fonctionnel, possible avec assistance robotique, adapte en peropératoire le positionnement des implants prothétiques selon l’anatomie et la laxité ligamentaire constitutionnelles. Nous avons réalisé une revue systématique comparant les résultats après PTG entre AC et AM. L’AC apparaissait comme une technique envisageable et alternative à l’AM. Une nouvelle classification radiologique CPAK d’AC a été décrite considérant l’alignement coronal et l’obliquité de l’interligne après PTG. Nous avons comparé l’alignement coronal obtenu avec cette méthode à des radiographies dynamiques en valgus compensant l’usure cartilagineuse et la laxité ligamentaire. Nous avons trouvé des résultats similaires indiquant que l’AC évalué avec la classification CPAK permettrait d’anticiper l’alignement fonctionnel sur l’espace en extension du genou. Nous avons comparé les résultats cliniques après PTG en fonction de la restauration ou non des différentes catégories de la classification CPAK. Nous avons trouvé que l’AM ne restaure pas le phénotype du genou dans la majorité des cas. Aussi, nous avons montré moins de douleurs post opératoires lorsque l’interligne après PTG était maintenue par rapport au préopératoire. Enfin, la majorité des études présentant les résultats de PTG avec AC sont réalisées avec des prothèses à conservation du ligament croisé postérieur. Or, nous utilisons une PTG postéro-stabilisée (PS). Nous avons donc comparé les résultats entre AM et AC en utilisant une PTG PS par un système plot-came. Nous avons trouvé un risque augmenté de descellement tibial aseptique dans le groupe cinématique potentiellement expliqué par des forces de cisaillement exercées sur le plot tibial. Plusieurs études ont évalué le schéma de marche des patients afin d’obtenir un examen plus objectif sur la récupération fonctionnelle en post opératoire de prothèses de genou. L’objectif était d’évaluer la récupération d’un schéma de marche le plus proche possible de celui d’un genou natif. Nous avons initié une étude prospective randomisée comparant l’analyse de la marche chez des patients opérés de PTG type « medial-pivot » avec AM versus AC. Les objectifs étaient de comparer l’analyse de la marche, les résultats cliniques et radiologiques pour 52 PTG dans chaque groupe à un recul minimum de 12 mois. Nous avons donc montré que l’AC permettait d’obtenir de bons résultats cliniques et radiologiques. L’AC déterminé à partir de repères osseux semble correspondre à l’alignement fonctionnel en extension. En revanche, l’assistance robotique nous a permis de réaliser que le comportement ligamentaire était différent en flexion et que l’AC ne permettait pas d’obtenir un bon équilibrage ligamentaire en flexion dans tous les cas. L’évaluation du schéma de marche après PTG implantées avec assistance robotique selon l’alignement fonctionnel serait intéressante.Total Knee Arthroplasty (TKA) is a common orthopedic procedure. When performing a TKA, the aim was to achieve a systematic 180° mechanical alignment (MA). This technique results in a straight limb, reducing joint stress and ultimately improving implant survival. Despite technological advances, the results of TKA remain imperfect. Although long-term survival is very good, up to 20% of patients are not satisfied with their prosthesis. In an attempt to improve these results, new personalized implant alignment proposals have been developed. We started by trying to better understand the coronal femoro-tibial alignment of an osteoarthritic population by showing its important individual variation and its differences with a non-osteoarthritic population. We then detailed the different possibilities of personalized alignment. The goal of kinematic alignment (KA) is to restore the anatomy and soft-tissue balance of the pre-arthritic knee using bony landmarks. Functional alignment, which is only possible with robotic assistance, adapts intraoperatively the positioning of prosthetic implants according to the constitutional anatomy and ligament laxity. We performed a systematic review comparing the results after TKA between KA and MA. KA appeared to be a feasible alternative technique to MA. A new CPAK radiological classification of KA was described considering the coronal alignment and the joint line obliquity following TKA. We compared the coronal alignment obtained with this method to distractive valgus stress radiographs compensating for cartilage wear and ligament laxity. We found similar results indicating that KA assessed with the CPAK classification would anticipate functional alignment for the knee extension space. We compared clinical outcomes after TKA based on whether the different categories of the CPAK classification were restored. We found that MA does not restore the knee phenotype in most cases. Also, we showed less postoperative pain when the joint line obliquity after TKA was maintained compared to preoperatively. Finally, most studies presenting the results of TKA with KA are performed with prostheses that preserve the posterior cruciate ligament. However, we use a posterior-stabilized (PS) TKA. We therefore compared the results between MA and KA using a PS TKA with a plot-cam system. We found an increased risk of aseptic tibial loosening in the kinematic group potentially explained by shear forces exerted on the tibial plot. Several studies have assessed patient walking in order to have a more objective examination of the functional recovery after TKA. The aim was to assess recovery by a gait pattern that resembles closely that of a native knee. We initiated a prospective randomized study comparing gait analysis in medial-pivot TKA patients with MA versus KA. The objectives were to compare the gait analysis, clinical and radiological results for 52 TKRs in each group at a minimum follow-up of 12 months. Thus, we showed that KA resulted in good clinical and radiological outcomes. The KA determined from bone landmarks seems to correspond to the functional alignment in extension. On the other hand, robotic assistance allowed us to realize that ligament behavior was different in flexion and that KA did not achieve good ligament balancing in flexion in all cases. The evaluation of the gait pattern after TKA implanted with robotic assistance according to the functional alignment would be interesting

Unrestricted kinematic alignment corrects fixed flexion contracture in robotically aligned total knees without raising the joint line in extension

Abstract Purpose Mechanically Aligned Total Knee Arthroplasty (MA TKA) typically addresses fixed flexion contractures (FFC) by raising the joint line during extension. However, in unrestricted Kinematically Aligned TKA (KA TKA) utilizing a caliper‐based resection technique, the joint line is not raised. This study aims to determine the efficacy of KA TKA in restoring full extension in patients with FFC without increasing distal femoral resection, considering tibial bone resection and sagittal component positioning. Methods A retrospective study was conducted by a single surgeon, involving patients who underwent primary robotically assisted cruciate retaining unrestricted KA TKA between June 1, 2021, and December 1, 2022. Complete intraoperative resection and alignment data were recorded, including the thickness of distal femoral and proximal tibial bone cuts. Patients with a preoperative FFC ≥ 5° (study group) were compared to those with FFC < 5° (control group). The impact of variations in tibial resection and sagittal component positioning was assessed by comparing the heights of medial and lateral resections, sagittal femoral component flexion, and tibial slope. Group comparisons were analyzed using the Wilcoxon Signed Rank Test, with a significance level set at p < 0.05. Results A total of 48 KA TKA procedures met the inclusion criteria, with 24 performed on women. The mean preoperative FFC in the study group was 11.2° (range: 5–25°), while the control group exhibited 1° (range: 0–4°) (p < 0.001). There were no statistically significant differences observed between the study and control groups in terms of distal femoral resections, both medially (p = 0.14) and laterally (p = 0.23), as well as tibial resection heights, both medially (p = 0.66) and laterally (p = 0.74). The alignment of the femoral component flexion and tibial slope was comparable between the two groups (p = 0.31 and p = 0.54, respectively). All patients achieved within 5 degrees of full extension at closure. Conclusion Robotic arm‐assisted unrestricted KA TKA effectively restores full extension without raising the joint line during extension for patients with a preoperative fixed flexion contracture. Level of evidence III

Kinematic Alignment of Failed Mechanically Aligned Total Knee Arthroplasty Restored Constitutional Limb Alignment and Improved Clinical Outcomes: A Case Report of 7 Patients

Background: Stiffness and mid-flexion instability (MFI) is a recognized complication of mechanically aligned (MA) total knee arthroplasty (TKA). Kinematic alignment (KA) has been proposed as a means by which to restore normal joint motion following TKA and potentially avoid stiffness and MFI. Several studies have documented improved function with KA when compared to MA. The aim of this study was to determine if revising MA TKAs failed for either MFI or stiffness into KA resolves MFI, achieves better range of motion, and improves clinical outcomes. Methods: A retrospective, single surgeon review was performed. All consecutive TKAs revised from MA into KA for MFI (def: &gt;5 mm opening between 10° and 45° of flexion) or stiffness (def: flexion ≤90°) between January 2017 and May 2021 were included. The constitutional limb alignment of the operated knee was “reverse engineered” by measuring the coronal alignment of the contralateral healthy knee or pre-operative x-rays. Femoral Rotation was set at 3 degrees internal to the trans epicondylar axis. All coronal and sagittal angles were digitally measured on pre- and post-operative long leg and maximum flexion radiographs (minimum 12 month follow-up). The Knee Society Score (KSS) and range of motion assessments were collected preoperatively and at final follow-up. Comparisons between groups were done with a paired T test. Significance was set at p &lt; 0.05. Results: Seven patients were included. Two were male, the mean age was 70.1 years (±9.3), mean follow-up was 32 months (±26). Three patients were revised for MFI and 4 for stiffness. Constitutional limb alignment was restored within 2 degrees for all patients. The mean total KSS gain was 65.9 (±18.1). The total KSS was significantly improved in all patients (p &lt; 0.001). The mean maximum flexion gain was 30 deg (±23°) (p = 0.01). MFI was absent in all patients. Conclusion: In a limited series of patients, revision of stiff or unstable TKA from MA to KA resulted in improved range of motion by 30° on averages, resolved instability without the use of constrained liners, improved clinical outcomes with a mean gain of 75 points on the KSS, and restored constitutional limb alignment within 2 degrees in all patients. As these short term results are promising, further study is warranted

New Technologies in Knee Arthroplasty: Current Concepts

Total knee arthroplasty (TKA) is an effective treatment for severe osteoarthritis. Despite good survival rates, up to 20% of TKA patients remain dissatisfied. Recently, promising new technologies have been developed in knee arthroplasty, and could improve the functional outcomes. The aim of this paper was to present some new technologies in TKA, their current concepts, their advantages, and limitations. The patient-specific instrumentations can allow an improvement of implant positioning and limb alignment, but no difference is found for functional outcomes. The customized implants are conceived to reproduce the native knee anatomy and to reproduce its biomechanics. The sensors have to aim to give objective data on ligaments balancing during TKA. Few studies are published on the results at mid-term of these two devices currently. The accelerometers are smart tools developed to improve the TKA alignment. Their benefits remain yet controversial. The robotic-assisted systems allow an accurate and reproducible bone preparation due to a robotic interface, with a 3D surgical planning, based on preoperative 3D imaging or not. This promising system, nevertheless, has some limits. The new technologies in TKA are very attractive and have constantly evolved. Nevertheless, some limitations persist and could be improved by artificial intelligence and predictive modeling

Current role of intraoperative sensing technology in total knee arthroplasty

PURPOSE: Sensors have been introduced within the last 10years to quantify soft tissue balancing during total knee arthroplasty (TKA) and to give the surgeon objective data. These devices are fairly new and their impact on patient outcome remains uncertain. The aim of this systematic review was to summarize all the relevant surgical and clinical results of sensors for TKA. METHODS: A PRISMA systematic review was conducted using five databases (PubMed, EMBASE, MEDLINE, GOOGLE SCHOLAR, and the COCHRANE LIBRARY) to identify all available literature that described the surgical and clinical results of sensors for TKA between 2000 and 2021. The main investigated outcome criteria were intraoperative data, postoperative functional and clinical outcome, knee range of motion, complications and revision rates. RESULTS: Twenty-seven articles were finally included. The maximum reported follow-up was 26months. A balanced knee with sensor corresponded to a mediolateral difference inferior to 15lb and a stable posterior drawer test. The standard assessment of knee balance was a poor predictor of the true soft tissue balance when compared to sensor data. At least 60% of TKA needed an additional rebalancing procedure with the sensor, after conventional gap balancing. Achieving a quantitatively balanced knee resulted in a significantly higher patient satisfaction score. But the prospective comparative studies found no demonstrable improvement in clinical outcome, range of motion or complication rate at one year postoperatively for patients undergoing TKA using sensor-guided balancing compared with routine techniques. CONCLUSION: Even though the use of the intraoperative sensing technology was not related to an improvement in clinical outcome, the current studies showed that using sensors facilitates the reproduction of natural joint stability, and improves the rate of achieving a balanced knee. Sensor use in complex cases could be particularly valuable, but their use in standard practice remains to be defined

Autologous osteochondral transplantation for focal femoral condyle defects: Comparison of mosaicplasty by arthrotomy vs. arthroscopy

BACKGROUND: While many studies have reported the outcomes of open mosaicplasty, data on arthroscopic mosaicplasty are scarce. Only two cadaver studies have compared arthrotomy and arthroscopy. Moreover, the patello-femoral joint, which is the main donor site, has never been assessed using a specific functional score. The objective of this in vivo study was to compare arthrotomy and arthroscopy for mosaicplasty using both a global functional knee score and a specific score of the patello-femoral joint.HYPOTHESIS: The arthroscopic technique results in better functional patello-femoral outcomes.MATERIAL AND METHODS: We retrospectively compared two groups of 17 patients who underwent mosaicplasty for focal condylar cartilage defects, at our department between 2009 and 2019. Functional outcomes were assessed using the Kujala score and the Lysholm score, at least 1 year after surgery. The return to sports was assessed using the Tegner score.RESULTS: Mean follow-up was 67.4±15.9 months in the arthrotomy group and 45.2±35.1 months in the arthroscopy group (

Autologous osteochondral transplantation for focal femoral condyle defects: Comparison of mosaicplasty by arthrotomy vs. arthroscopy

BACKGROUND: While many studies have reported the outcomes of open mosaicplasty, data on arthroscopic mosaicplasty are scarce. Only two cadaver studies have compared arthrotomy and arthroscopy. Moreover, the patello-femoral joint, which is the main donor site, has never been assessed using a specific functional score. The objective of this in vivo study was to compare arthrotomy and arthroscopy for mosaicplasty using both a global functional knee score and a specific score of the patello-femoral joint.HYPOTHESIS: The arthroscopic technique results in better functional patello-femoral outcomes.MATERIAL AND METHODS: We retrospectively compared two groups of 17 patients who underwent mosaicplasty for focal condylar cartilage defects, at our department between 2009 and 2019. Functional outcomes were assessed using the Kujala score and the Lysholm score, at least 1 year after surgery. The return to sports was assessed using the Tegner score.RESULTS: Mean follow-up was 67.4±15.9 months in the arthrotomy group and 45.2±35.1 months in the arthroscopy group (

Autologous osteochondral transplantation for focal femoral condyle defects: Comparison of mosaicplasty by arthrotomy vs. arthroscopy

BACKGROUND: While many studies have reported the outcomes of open mosaicplasty, data on arthroscopic mosaicplasty are scarce. Only two cadaver studies have compared arthrotomy and arthroscopy. Moreover, the patello-femoral joint, which is the main donor site, has never been assessed using a specific functional score. The objective of this in vivo study was to compare arthrotomy and arthroscopy for mosaicplasty using both a global functional knee score and a specific score of the patello-femoral joint.HYPOTHESIS: The arthroscopic technique results in better functional patello-femoral outcomes.MATERIAL AND METHODS: We retrospectively compared two groups of 17 patients who underwent mosaicplasty for focal condylar cartilage defects, at our department between 2009 and 2019. Functional outcomes were assessed using the Kujala score and the Lysholm score, at least 1 year after surgery. The return to sports was assessed using the Tegner score.RESULTS: Mean follow-up was 67.4±15.9 months in the arthrotomy group and 45.2±35.1 months in the arthroscopy group (

The Trochlear Groove of a Femoral Component Designed for Kinematic Alignment Is Lateral to the Quadriceps Line of Force and Better Laterally Covers the Anterior Femoral Resection Than a Mechanical Alignment Design

Background: A concern about kinematically aligned (KA) total knee arthroplasty (TKA) is that it relies on femoral components designed for mechanical alignment (MAd-FC) that could affect patellar tracking, in part, because of a trochlear groove orientation that is typically 6&deg; from vertical. KA sets the femoral component coincident to the patient&rsquo;s pre-arthritic distal and posterior femoral joint lines and restores the Q-angle, which varies widely. Relative to KA and the native knee, aligning the femoral component with MA changes most distal joint lines and Q-angles, and rotates the posterior joint line externally laterally covering the anterior femoral resection. Whether switching from a MAd- to a KAd-FC with a wider trochlear groove orientation of 20.5&deg; from vertical results in radiographic measures known to promote patellar tracking is unknown. The primary aim was to determine whether a KAd-FC sets the trochlear groove lateral to the quadriceps line of force (QLF), better laterally covers the anterior femoral resection, and reduces lateral patella tilt relative to a MAd-FC. The secondary objective was to determine at six weeks whether the KAd-FC resulted in a higher complication rate, less knee extension and flexion, and lower clinical outcomes. Methods: Between April 2019 and July 2022, two surgeons performed sequential bilateral unrestricted caliper-verified KA TKA with manual instruments on thirty-six patients with a KAd- and MAd-FC in opposite knees. An observer measured the angle between a line best-fit to the deepest valley of the trochlea and a line representing the QLF that indicated the patient&rsquo;s Q-angle. When the trochlear groove was lateral or medial relative to the QLF, the angle is denoted + or &minus;, and the femoral component included or excluded the patient&rsquo;s Q-angle, respectively. Software measured the lateral undercoverage of the anterior femoral resection on a Computed Tomography (CT) scan, and the patella tilt angle (PTA) on a skyline radiograph. Complications, knee extension and flexion measurements, Oxford Knee Score, KOOS Jr, and Forgotten Joint Score were recorded pre- and post-operatively (at 6 weeks). A paired Student&rsquo;s T-test determined the difference between the KA TKAs with a KAd-FC and MAd-FC with a significance set at p &lt; 0.05. Results: The final analysis included thirty-five patients. The 20.5&deg; trochlear groove of the KAd-FC was lateral to the QLF in 100% (15 &plusmn; 3&deg;) of TKAs, which was greater than the 69% (1 &plusmn; 3&deg;) lateral to the QLF with the 6&deg; trochlear groove of the MAd-FC (p &lt; 0.001). The KAd-FC&rsquo;s 2 &plusmn; 1.9 mm lateral undercoverage of the anterior femoral resection was less than the 4.4 &plusmn; 1.5 mm for the MAd-FC (p &lt; 0.001). The PTA, complication rate, knee extension and flexion, and clinical outcome measures did not differ between component designs. Conclusions: The KA TKA with a KAd-FC resulted in a trochlear groove lateral to the QLF that included the Q-angle in all patients, and negligible lateral undercoverage of the anterior femoral resection. These newly described radiographic parameters could be helpful when investigating femoral components designed for KA with the intent of promoting patellofemoral kinematics