Maury L. Hull

University of California, Davis | UCD · Department of Mechanical Engineering, Department of Biomedical Engineering, Department of Orthopaedic Surgery

Purpose In total knee arthroplasty (TKA) with posterior cruciate ligament (PCL) retention, the medial and lateral insert conformity that restores in vivo native (i.e., healthy) knee tibial rotation and high function without causing stiffness is unknown. The purpose was to determine whether a ball-in-socket (B-in-S) medially conforming (MC) and flat...

The primary aim was to analyze unrestricted kinematic alignment (unKA) total knee arthroplasty (TKA) and determine the frequency of medial deviation of the prosthetic trochlear angle (PTA) of the femoral component relative to the quadriceps vector (QV) that terminates at the anterior inferior iliac spine (AIIS), and whether patients with medial dev...

Radiostereometric analysis (RSA) measures movement (migration) of a baseplate relative to the underlying tibia after total knee arthroplasty (TKA) and has been used extensively to evaluate safety of new implant designs and/or surgical techniques regarding baseplate loosening. Because RSA is a complex methodology which involves various choices that...

Background: The preceding study reported a 10-year follow-up of 222 kinematically aligned (KA) total knee arthroplasties (TKA) performed in 217 patients in 2007. As 35% of tibial components and 8% of limbs were in > 3° varus, the present study assessed whether this adversely affected reoperation, implant survival, and function at 16 years. Methods...

Background: Although retaining the posterior cruciate ligament (PCL) is advantageous in unrestricted kinematically aligned TKA, it is often excised with a medial stabilized implant. The primary objectives were to determine whether PCL retention using an insert with ball-in-socket (B-in-S) medial conformity to maximize A-P stability promotes intern...

Introduction: There are no reports as to whether the condition of the anterior cruciate ligament (ACL) adversely affects the 2 to 3 year function and reoperation risk of a kinematically aligned (KA) total knee arthroplasty (TKA) performed with posterior cruciate ligament (PCL) retention and an intermediate medial conforming (MC) insert. Methods:...

Purpose For a new tibial insert design with ball-in-socket (B-in-S) medial conformity (MC), posterior cruciate ligament (PCL) retention, and flat lateral articular surface (B-in-S MC + PCL), this study determined whether internal tibial rotation and knee flexion were limited and clinical outcome scores were lower during weight-bearing activities re...

Background: One method for assessing the accuracy of manual, patient-specific, navigational, and robotic-assisted total knee arthroplasty (TKA) instrumentation is to use a post-operative computer tomogram and determine the deviation of the femoral component alignment relative to the planned alignment in the native (i.e. healthy) contralateral dist...

Radiostereometric analysis can be used for computing movement of a tibial baseplate relative to the tibia (termed migration) to detect baseplate instability. Quantifying migration in six degrees of freedom requires establishing a coordinate system in which to express the movement. Establishing consistent migration directions among patients and base...

Quantification of clinically meaningful tibiofemoral motions requires a joint coordinate system (JCS) with motions free from kinematic crosstalk errors. Objectives were to use a JCS with literature-backed functional axes (FUNC) and a JCS recommended by the International Society of Biomechanics (ISB) to determine tibiofemoral kinematics of the nativ...

Peer-reviewed studies published up to May 2022 are used to provide a comprehensive understanding of unrestricted kinematically aligned total knee arthroplasty. The intent is to cultivate the curiosity of those interested in this method of personalized alignment. The rationale of unrestricted kinematic alignment is to set the femoral and tibial comp...

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° from vertical. KA sets the femoral component coincident to the patient's...

PurposeVarus alignment of the tibial baseplate and limb > 3° might adversely affect baseplate fixation after total knee arthroplasty (TKA), especially for unrestricted kinematically aligned (KA) TKA which aligns a majority of baseplates in varus. The purposes of this study were to determine whether baseplate migration at 1 year (1) was significantl...

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 surgeo...

As the conformity of a medial ball-in-socket total knee arthroplasty (TKA) provides intrinsic anterior-posterior (A-P) stability, surgeons cannot rely on the manual examination of sagittal laxity to identify the optimal insert thickness. Instead, the present study determined whether measuring tibial axial orientation in extension and 90° flexion wi...

Background: In total knee arthroplasty (TKA), inserts can have different levels of medial and lateral congruency determined by the acuteness of the upslopes of the anterior and posterior articular surfaces. The present study evaluated an insert with different levels of lateral congruency and a medial ball-in-socket congruency to test the hypothesi...

Because model-based radiostereometric analysis (MBRSA) identifies tibial baseplate designs which increase risk of baseplate loosening, and because registration errors for computer-aided-design (CAD) models are large relative to a 6-month stability limit, 3D models more representative of the geometry of implanted baseplates are needed to minimize er...

After starting an orthopedic practice, a surgeon with a fellowship in mechanically aligned (MA) TKA initiated this study to characterize their learning curve after they switched to unrestricted kinematic alignment (KA) TKA using manual instruments. Accordingly, the present study determined for the inexperienced (IE) surgeon the number of cases requ...

Purpose: Because different targets are used for internal-external rotation, an asymmetric baseplate designed for mechanical alignment may lead to under-coverage and concomitant posterior rim loading in the lateral compartment following unrestricted kinematic alignment (KA) TKA. Recognizing that such loading can lead to premature wear and/or subsid...

Radiostereometric analysis is a method to measure implant migration where an ISO standard recommends double examinations (i.e. acquisition of two independent sets of biplanar images on the same day) to compute bias (i.e. mean) and precision (i.e. standard deviation) of differences in repeated migration measurements (termed repeated measurement stat...

Purpose Surgeons performing total knee arthroplasty (TKA) are interested in the accuracy and time it takes to make the four femoral resections that determine the setting of the femoral component. A method for quantifying the error of each resection is the thickness, measured by a caliper, minus the femoral target. The present study tested the hypot...

Background One method to determine tibiofemoral joint kinematics following total knee arthroplasty (TKA) is to quantify movement of the anterior-posterior (AP) position of the flexion facet center (FFC) on each femoral condyle relative to the tibia during knee flexion. The primary objective was to determine how closely AP positions of fixed FFCs ap...

Knowledge of anterior-posterior (AP) movement of the femoral condyles on the tibia in healthy knees serves to assess whether an artificial knee restores natural movement. Two methods for identifying AP positions and hence condylar movements include: 1) the flexion facet center (FFC), and 2) the lowest point (LP) methods. The objectives were to dete...

Manipulation under anesthesia (MUA) for stiffness within 6 to 12 weeks after mechanically aligned total knee arthroplasty (TKA) generally yields better outcome scores than an MUA performed later. However, the timing of MUA after unrestricted, caliper-verified, kinematically aligned (KA) TKA remains uncertain. A retrospective review identified 82 of...

Quantification of clinically meaningful tibiofemoral motions requires a coordinate system where motions are free from kinematic crosstalk errors. The objectives were to 1) develop an algorithm for assigning an optimized joint coordinate system (OPT JCS) that minimizes kinematic crosstalk errors based on a kinematic model of the tibiofemoral joint,...

Knowledge of the anterior-posterior (AP) tibial contact locations is useful in assessing wear of tibial inserts and detecting posterior rim loading. The objectives of this study were to 1) create a new 2D planar model that can determine AP tibial contact locations, 2) use the planar model to determine AP tibial contact locations for cadaveric TKA k...

Background Identifying the center of the talocrural joint is crucial in defining the tibia’s mechanical axis, which is used in a variety of applications such as a reference for measuring alignment variables following total knee arthroplasty. The objectives of this study were to 1) describe a new method for determining the center of the talocrural j...

This chapter reviews differences between the morphology of the prosthetic trochlea for four different femoral components set in kinematic alignment (KA) and the native knee in the same knee model. Trochlear morphology is described along the arc length of the native trochlea by the medial-lateral location of the trochlear groove, the radial distance...

This chapter reviews in vitro and in vivo differences in tibiofemoral kinematics between a low-conforming total knee arthroplasty (TKA) implanted with calipered kinematic alignment (KA) and the native knee. Kinematics are defined by laxities and resting positions of the tibia with respect to the femur and the anterior-posterior (A-P) movements of t...

Tibial forces in the medial and lateral compartments following calipered kinematically aligned (KA) total knee arthroplasty (TKA) are of high interest for two reasons. One reason is that knowledge of the tibial compartment forces provides a quantitative indication of how well the goal of restoring biomechanical variables characterizing knee functio...

Purpose Excision of the posterior cruciate ligament (PCL) is recommended when implanting a medial pivot (MP) total knee arthroplasty (TKA) to reduce the risk of limiting flexion by over-tensioning the flexion space. The present study determined whether PCL retention (1) limits internal tibial rotation and (2) causes anterior lift-off of the insert...

Introduction In total knee arthroplasty (TKA), the level of conformity, a medial stabilized (MS) implant, needs to restore native (i.e., healthy) knee kinematics without over-tensioning the flexion space when the surgeon chooses to retain the posterior cruciate ligament (PCL) is unknown. Whether an insert with a medial ball-in-socket conformity and...

Most medial stabilized (MS) total knee arthroplasty (TKA) implants recommend excision of the posterior cruciate ligament (PCL), which eliminates the ligament's tension effect on the tibia that drives tibial rotation and compromises passive internal tibial rotation in flexion. Whether increasing the insert thickness and reducing the posterior tibial...

In radiostereometric analysis (RSA), continuous migration denoted as ΔMTPM is the difference between maximum total point motion (MTPM) at 2 years relative to time zero and MTPM at 1 year relative to time zero. Continuous migration has been used to diagnose tibial baseplates as stable versus unstable when compared to a specified stability limit (i.e...

PurposeTibial insert conformity in total knee arthroplasty (TKA) is of interest due to the potential effect on tibiofemoral kinematics. This study determined differences in anterior–posterior movements of the femoral condyles, pivot locations, and internal tibial rotation in different arcs of flexion for two implants with different insert conformit...

Maximum total point motion (MTPM) of a tibial baseplate at 6 months is used to predict long-term aseptic loosening after total knee arthroplasty. However, the propagation of registration error into MTPM for stable baseplates (i.e. baseplates with MTPM < 0.5 mm) manifested as bias (i.e. systematic error) and precision (i.e. random error) has not bee...

Introduction: The calipered kinematically-aligned (KA) total knee arthroplasty (TKA) strives to restore the patient's individual pre-arthritic (i.e., native) posterior tibial slope when retaining the posterior cruciate ligament (PCL). Deviations from the patient's individual pre-arthritic posterior slope tighten and slacken the PCL in flexion that...

Maximum total point motion (MTPM), the point on a baseplate that migrates the most, has been used to assess the risk of tibial baseplate loosening using radiostereometric analysis (RSA). Two methods for determining MTPM for model-based RSA are to use either 5 points distributed around the perimeter of the baseplate or to use all points on the 3D mo...

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 eit...

A common method used to study tibiofemoral joint biomechanics following total knee arthroplasty (TKA) is the lowest point method, which finds the lowest points of each femoral condyle in relation to the plane of the resected tibia. The objectives of this paper were twofold: 1) to use a circle-based model to demonstrate the large inherent error intr...

The change in maximum total point motion (ΔMTPM) is used to predict long-term risk of tibial baseplate loosening, however, effects of registration error on ΔMTPM have not been quantified for marker-based and model-based radiostereometric analysis (RSA). Registration errors for marker-based and model-based RSA were applied to a stable tibial basepla...

Accuracy of model-based radiostereometric analysis (MBRSA) in calculating tibial baseplate migration depends on baseplate shape and orientation relative to the imaging planes. The primary objectives were to introduce a new method for determining the optimal baseplate orientation to minimize bias error during MBRSA and to demonstrate the clinical us...

Patellofemoral complications following total knee arthroplasty can be traced in part to alignment of the femoral component. Kinematic alignment (KA) and mechanical alignment (MA) use the same femoral component but align the component differently. Our objective was to determine differences in trochlear morphology from native for a femoral component...

This chapter presents the philosophy of kinematic alignment (KA) and the surgical technique for setting the positions of the components using ten calipered measurements, manual instruments, and nine verification checks. The adoption of KA is increasing. Four meta-analyses, three randomized trials, and a national multicenter study showed that patien...

The relative rigid body motions between the femur and the tibia (termed tibiofemoral kinematics) during flexion activities can provide an objective measure of knee function. Physiologic tibiofemoral kinematics are defined as the six relative rigid body motions expressed in a joint coordinate system where the motions about and along the axes conform...

Identifying and correcting varus‐valgus (V‐V) malalignment of the tibial component is important when balancing a kinematically aligned total knee arthroplasty (TKA). Accordingly, the primary objective was to determine whether the tibial forces or V‐V laxities are more sensitive to, and thus more useful for identifying and correcting, V‐V malalignme...

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–p...

PurposeSurgeons performing total knee arthroplasty (TKA) on the osteoarthritic valgus deformity often use a posterior stabilized (PS) and semi-constrained implants to substitute for the release of a contracted posterior cruciate ligament (PCL) instead of a cruciate retaining (CR) implant. Calipered kinematic alignment (KA) strives to retain the PCL...

The objectives were to determine errors in femoral anteversion (FA), femoral offset (FO), and vertical offset (VO) with robot‐assisted total hip arthroplasty (THA) and how consistently these errors are within clinically desirable limits of ± 5° and ± 5 mm. After preoperative planning, robot‐assisted THAs were performed on twelve cadaveric specimens...

Identifying and correcting varus-valgus (V-V) malalignment of the tibial component is important when balancing a kinematically aligned total knee arthroplasty (TKA). Accordingly, the primary objective was to determine whether the tibial forces or V-V laxities are more sensitive to, and thus more useful for identifying and correcting, V-V malalignme...

Purpose Kinematically aligned total knee arthroplasty (KA TKA) strives to restore the native distal and posterior joint lines of the femur. Because the joint lines of a virtually planned femoral component on the native femur can serve as surrogates of those of the native femur, the present study determined position and orientation deviations of the...

Revision of a medial unicompartmental knee arthroplasty (UKA) to a mechanically aligned total knee arthroplasty (MA TKA) is inferior to a primary TKA; however, revision with kinematic alignment (KA) has not been well studied. The present study determined whether patients revised with KA had a higher use of revision components, different postoperati...

Purpose Kinematically aligned (KA) TKA strives to restore native limb and knee alignments without ligament release with the premise that knee function likewise will be closely restored to native to the extent enabled by the components used. This study determined differences in anterior–posterior (AP) tibial contact locations of a KA TKA performed w...

Background: Closely approximating the functional flexion-extension (FE) axis of the tibiofemoral joint in 3D models of the femur is important when computing joint motions which are physiologic. The objectives were to 1) develop methods to approximate the functional FE axis based on fitting circles, a tapered cylinder, and spheres to the posterior c...

Prior studies suggest kinematically aligned (KA) total knee arthroplasty (TKA) provides some clinical benefits. There are no reports of self-reported outcome measures in patients treated with a calipered KA TKA that already had a contralateral mechanically aligned (MA) TKA. We performed a retrospective study and asked the following questions: (1) W...

Purpose Although patellofemoral complications after kinematically aligned (KA) TKA are infrequent, the patellar flexion angle and proximal–distal patellar contact location through flexion, and incidence of patellar loss of contact at full extension are unknown. The present study determined whether the patellar flexion angle and proximal–distal pate...

Introduction There are concerns that postoperative varus or valgus outlier alignment of the tibial component, knee, and limb might adversely affect the long-term results of kinematically aligned (KA) TKA particularly when patients are selected without restrictions based on the severity of the preoperative varus-valgus and flexion deformities. Meth...

Background: Loss of contact between the femoral and tibial implants following total knee arthroplasty (TKA) has been related to accelerated polyethylene wear and other complications. Two methods have been used to detect loss of contact in single-plane fluoroscopy, the condylar lift-off method and the separation method. The objectives were to asses...

Three dimensional models of the femur and tibia from MRI and CT are used in various studies of knee biomechanics but morphological errors occur. The objectives were to determine the morphological errors in 3D bone models from MRI and CT using clinically-adopted imaging protocols, to determine whether these errors are affected by the method of regis...

Background Four mechanical alignment force targets are used to predict early patient-reported outcomes and/or to indicate a balanced TKA. For surgeons who use kinematic alignment, there are no reported force targets. To date the usefulness of these mechanical alignment force targets with kinematic alignment has not been reported nor has a specific...

We hypothesized that a total knee arthroplasty (TKA) with an intraoperative tibial force greater than the tibial force of the native knee has signs of stiffness as measured by loss of extension and flexion, and anterior translation of the tibia. Intraoperative forces in the medial and lateral tibial compartments were measured during passive motion...

Purpose Kinematic alignment (KA) and mechanical alignment (MA) position the prosthetic trochlea that guides patellar tracking differently. The present study determined whether KA or MA more closely restores the groove location and sulcus angle of the prosthetic trochlea to the native trochlea for three femoral component designs. Methods Ten 3D fem...

Background Alignment in the varus or valgus outlier range of the tibial component, knee, and limb might adversely affect the long-term results of kinematically aligned total knee arthroplasty (TKA) particularly when patients are selected without restricting the degree of preoperative varus-valgus and flexion deformity. Methods A retrospective revi...

Background: The OrthoSensor VERASENSE knee system is a commercially available instrumented tibial insert that provides real-time intraoperative measurements of tibial contact force and contact location to guide surgeons toward improving outcomes in total knee arthroplasty (TKA). However, the device has been used contrary to the manufacturer's reco...

The present study reviewed patients treated with kinematically aligned (KA) TKA and determined whether hitting the mechanical alignment force targets of Gustke, Jacobs, Meere, and Meneghini resulted in better patient reported outcomes and whether there is a force target for KA that separates subjects with better Oxford Knee Scores (OKS) of >34 (goo...

Purpose: The purposes of this study were to quantify the increase in tibial force imbalance (i.e. magnitude of difference between medial and lateral tibial forces) and changes in laxities caused by 2° and 4° of varus-valgus (V-V) malalignment of the femoral component in kinematically aligned total knee arthroplasty (TKA) and use the results to det...

Introduction: We determined (1) the range of the hip-knee-ankle (HKA) angle in the native or pre-arthritic limbs of patients with a contralateral total knee arthroplasty (TKA); and when mechanical alignment is planned (2) the relationships between the HKA angle and the tibial width, and the relative narrowing between the medial and lateral compart...

Purpose: The purposes of this study were to quantify the increase in tibial force imbalance (i.e. magnitude of difference between medial and lateral tibial forces) and changes in laxities caused by 2° and 4° of internal-external (I-E) malalignment of the femoral component in kinematically aligned total knee arthroplasty. Because I-E malalignment w...

Aims The aims of this study were to determine the proportion of patients with outlier varus or valgus alignment in kinematically aligned total knee arthroplasty (TKA), whether those with outlier varus or valgus alignment have higher forces in the medial or lateral compartments of the knee than those with in-range alignment and whether measurements...

Purpose: Following total knee arthroplasty (TKA), high tibial forces, large differences in tibial forces between the medial and lateral compartments, and anterior translation of the contact locations of the femoral component on the tibial component during passive flexion indicate abnormal knee function. Because the goal of kinematically aligned TK...

Knowledge of A-P tibial contact locations provides an objective assessment of the relative motion of the tibia on the femur following total knee arthroplasty, which can be used to compare the effects of different components, surgical techniques, and alignment goals on knee function in vivo. Both the closest point method and the penetration method h...

INTRODUCTION: Measurements of intraoperative medial and lateral tibial compartment forces determine balance after total knee arthroplasty (TKA). Medial compartment forces are high in osteoarthritic knees with varus deformities and lateral compartment forces are high in knees with valgus deformities. Accordingly, we asked: 1) Are the medial and late...

INTRODUCTION: A well-balanced total knee arthroplasty (TKA) is necessary for long-term success. It is unknown whether using an insert 2mm thicker than implanted increases tibial compartment forces, increases anterior position of the tibia, and decreases knee motion. Accordingly, we asked: how much does an insert 2mm thicker than implanted increase...

Errors during a robot-assisted THA may result in a femoral cavity with position and orientation different than planned. This can lead to a femoral component placement that inaccurately sets a patient's femoral anteversion (FA), femoral offset (FO), and vertical offset (VO). The objectives of this study were to determine the position and orientation...

Purpose: Eight patients treated with kinematically-aligned (KA) total knee arthroplasty (TKA) presented with tibial component failure. We determined whether radiographic measurements and clinical characteristics are different between patients with and without tibial component failure to identify mechanisms of failure and strategies to reduce the r...

Analysis of anterior–posterior (A–P) tibial contact locations following total knee arthroplasty (TKA) provides an objective assessment of the relative motion of the tibia on the femur during activities of daily living. Determining A–P tibial contact locations using single-plane fluoroscopy requires input in the form of the relative 3D position and...

Previous reports of tibial force sensors have neither characterized nor corrected errors in the computed contact location between the femoral and tibial components in total knee arthroplasty (TKA) that are theoretically caused by the curved articular surface of the tibial component. The objectives were to experimentally characterize there errors an...

Contact force imbalance and contact kinematics (i.e. motion of the contact location in each compartment during flexion) of the tibiofemoral joint are both important predictors of a patient's outcome following total knee arthroplasty (TKA). Previous tibial force sensors (TFS) have limitations in that they either did not determine contact force and c...

This study calculated the frequency of occurrence of gap imbalances between medial and lateral compartments at 0° flexion and within a compartment between 0° and 90° flexion, and changes in limb and knee alignment from native after computer simulation of TKA with the knee set 5° or 7° valgus at 0° flexion. TKA was simulated on forty-nine 3D bone mo...

Purpose: After reconstructing a torn ACL with a soft tissue allograft, the long-term healing process of graft maturation following the short-term healing process of graft incorporation into the bone tunnels might lead to recurring instability and concomitant decreases in the activity level, function, and patient satisfaction. Relying on roentgen s...

IntroductionThirteen patients presented with patellofemoral instability out of 3212 knees treated with kinematically aligned total knee arthroplasty (KA TKA) during a nine year period. We determined the clinical characteristics and post-operative radiographic parameters associated with patellofemoral instability, and whether re-operation and patien...

Kinematic alignment is a method of aligning implants in total knee arthroplasty (TKA) that strives to restore the native flexion-extension (F-E) and longitudinal rotation (LR) axes of the tibiofemoral joint. The anterior cruciate ligament (ACL) is typically resected at the time of TKA, which might change the position and orientation of these axes f...

Background: Kinematically aligned total knee arthroplasty uses a femoral component designed for mechanical alignment (MA) and sets the component in more internal, valgus, and flexion rotation than MA. It is unknown how much kinematic alignment (KA) and flexion of the femoral component reduce the proximal and lateral reach of the trochlea; two redu...

Internal and external malrotation of the femoral and tibial components is associated with poor function after total knee arthroplasty (TKA). We determined the degree of malrotation for both components in kinematically aligned TKA and whether this malrotation compromised function. Seventy-one patients (mean age 68 years) were followed after TKA. Mal...

BACKGROUND: Gap-balancing is an alignment method for total knee arthroplasty with the goal of creating uniform tension in the periarticular soft-tissue restraints and equal laxities throughout the arc of flexion. However, there is little evidence that achieving equal laxities prevents either overly tight or overly loose soft-tissue restraints after...

Patient-to-patient differences should be accounted for in both clinical evaluations and computational models of knee laxity. Accordingly, the objectives were to determine how variable the laxities are between knees by determining the range of the internal-external (I-E), varus-valgus (V-V), anterior-posterior (A-P), and compression-distraction (C-D...

We report the six year implant survivorship, tibial component alignment and knee and limb function measured by the Oxford Knee Score and Western Ontario and McMaster Universities Osteoarthritis Index ((WOMAC) score after kinematically aligned total knee arthroplasty (TKA) and tested the hypothesis that varus alignment of the tibial component, knee,...