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BACKGROUND: To date, repair of the lacertus in distal biceps tendon ruptures, recommended by some, has not been evaluated. The goal of these biomechanical experiments was to evaluate the degree to which its repair increases the strength of a distal biceps tendon repair. HYPOTHESIS: An intact or repaired lacertus fibrosus will increase the strength of a distal biceps tendon repair. STUDY DESIGN: Controlled laboratory study. METHODS: Four matched pairs of fresh-frozen human cadaveric upper extremities were prepared by isolating the lacertus fibrosus and the distal biceps tendon. The extremity was placed in a custom-built rig with the distal biceps brachii clamped and affixed to a stepper motor assembly. The distal biceps tendon was sharply removed directly from the radial tuberosity and repaired through a bony tunnel in all specimens. One side of each pair was randomized to also receive repair of the lacertus. The specimens were pulled at a constant rate until failure. RESULTS: The mean failure strength, defined as maximal strength to 15 mm of displacement, was higher in specimens with a repaired lacertus (250.2 N vs 158.2 N; P =.012), as was mean maximum strength (256.8 N v. 164.5 N; P =.0058). Mean stiffness was not significantly different (16.36 N/mm vs 13.8 N/mm; P =.58). All specimens failed due to fracture at the bony bridge. CONCLUSION: Repair of the lacertus strengthened distal biceps tendon repair in a controlled laboratory setting. CLINICAL RELEVANCE: Repair of the lacertus fibrosus as an adjunct to distal biceps tendon repair strengthens the repair in the laboratory setting. Clinical testing is needed to verify that this increased strength improves clinical results. Surgeons should be cautioned to protect the underlying neurovascular structures during repair of the lacertus fibrosus and to avoid an overly tight repair. [ABSTRACT FROM AUTHOR]

When inserting an uncemented hip stem, the objectives are to obtain a close fit of the stem in the canal and anatomic head placement. Our goals were to formulate a set of stems which would satisfy these two objectives, and to test the resulting templates on sequential radiographs of hip replacement patients. Using 98 cases for which a custom primary hip had been designed, thirteen dimensional parameters for a hip stem were defined, most importantly proximal medial width (PMW), proximal lateral width (PLW), head offset (HOF), head height (HHT), mid-stem diameter (BD), and distal diameter (DD). These parameters were analyzed in 155 patients' radiographs, and the resulting data were evaluated to obtain the optimal combinations of parameters. A 14-size stem system was defined and evaluated on the AP radiographs of 103 successive hip replacement patients. For each stem diameter between 11 and 17mm, two pairs of PMW and PLW values, equivalent to 'varus' and 'valgus' shapes, provided the best fit for the population of radiographs. The template analysis showed that out of 103 cases, 93% of offsets were within 4mm of ideal, while 81% of heights were within 1mm of ideal, and 99% were within 4mm of the ideal. Canal fit was within 1.5mm in the proximal-medial Gruen Zone 7 in 58% of the cases. The dimensional parameters of the 14 size system enabled the close matching of the important dimensional parameters simultaneously. The error that did occur could largely be corrected by modular heads and by minor canal broaching. By providing two stem shape variations for each stem diameter, our system achieved an accurate head center position while simultaneously obtaining a sufficiently close fit in the canal. [ABSTRACT FROM AUTHOR]

Background: A high concentration of crosslinked hyaluronic acid (HA) in a smooth, malleable formulation is the hallmark of the new Juvéderm dermal fillers.Objective: To determine the long-term effectiveness and safety of Juvéderm Ultra and Ultra Plus injectable gel.Methods: In the multicenter study approved by the Food and Drug Administration, subjects were randomized to treatment with Juvéderm Ultra or Ultra Plus in one nasolabial fold (NLF) and Zyplast collagen in the other. After optimal correction was achieved (treatment plus up to 2 touch-ups at 2-week intervals), effectiveness was assessed on a 5-point scale through the 6-month study period. An additional poststudy visit provided long-term effectiveness data. Safety was evaluated through subjects' daily diaries for 14 days after treatment.Results: A total of 292 subjects were randomized and treated, 146 in each cohort. A total of 280 subjects completed the 6-month study, and 227 attended the poststudy visit. Clinically significant mean wrinkle correction (>or= 1 point improvement) was still in evidence at >9 months for both Juvéderm formulations but not for the Zyplast control. At >9 months, 75% of Juvéderm Ultra- and 81% of Juvéderm Ultra Plus-treated NLFs maintained a clinically significant correction. Moreover, 78% of NLFs treated with Juvéderm Ultra Plus still had a clinically significant improvement beyond 1 year. Local treatment site reactions were comparable for Juvéderm and Zyplast.Conclusions: These next-generation HA dermal fillers can be reliably expected to provide long-term correction, with Juvéderm Ultra lasting more than 9 months and Juvéderm Ultra Plus lasting for a year or more. [ABSTRACT FROM AUTHOR]

Studies examining alcohol and drug education in schools of nursing were reviewed. A paucity of investigations was noted and most evaluations possessed significant methodologic shortcomings. Schools of nursing generally provided minimal exposure to important concepts in the addictions. Few classroom hours were dedicated to alcohol and drug issues and individual courses devoted to substance use disorders were uncommon. Clinical training was a particularly neglected area. Neither the scope nor intensity of clinical instruction was sufficient to ensure that graduating nurses could effectively intervene with chemically dependent patients. Other findings suggested that drug education receives less attention than alcohol education and that schools of nursing provide less chemical dependency training than medical and other professional schools. [ABSTRACT FROM AUTHOR]

BACKGROUND: Topical retinoids are one of the most effective classes of topical drugs used to treat acne vulgaris.The effects of the gel formulation of the topical retinoid tazarotene have been widely reported, but few data on the cream formulation are available. OBJECTIVE: The primary aim of the 2 studies reported in this article was to determine the effects of tazarotene 0.1% cream in patients with facial acne vulgaris. METHODS: Two randomized, double-blind, parallel-group studies were performed. The first was conducted at 14 investigational sites across the United States, and the second took place at 15 sites, with 5 of these providing blood samples for analysis of tazarotenic acid. In both studies, patients aged > or =12 years with facial acne vulgaris were randomized to receive tazarotene or vehicle cream QD for 12 weeks. Lesion counts (noninflammatory, inflammatory, and total) and overall clinical and global assessments were made at weeks 0 (baseline), 4, 8, and 12. Adverse events (AEs) were monitored throughout the study In one of the studies, therapeutic drug monitoring was performed at weeks 4 and 8 in members of the study population who gave consent for blood withdrawal. RESULTS: Eight hundred forty-seven patients were enrolled in the 2 studies (430 males, 417 females; mean age,19 years; age range, 11-52 years [1 patient was entered into the study at age 11 years, in violation of the protocol]). At 12 weeks, the median percentage changes from baseline in all 3 lesion counts were significantly lower with tazarotene than with vehicle (all, P < 0.001), as were the overall clinical and global responses (both, P < 0.001). Treatment-related AEs whose incidence was higher with tazarotene than with vehicle included desquamation, dry skin, erythema, a burning sensation on the skin, and skin irritation (all, P < 0.001) and pruritus (P < 0.01); most (83%-98%) were mild or moderate. Systemic exposure to tazarotenic acid was limited (mean, <0.1 ng/mL) and did not increase with time. CONCLUSIONS: In these 2 studies in adolescent and adult patients with facial acne vulgaris, tazarotene 0.1%cream QD for 12 weeks was effective and well tolerated. Systemic exposure to tazarotenic acid was limited. [ABSTRACT FROM AUTHOR]

Background: Noncruciate total knee arthroplasty designs, including ultracongruent, medially congruent, and medial pivot, are gaining increasing attention in total knee arthroplasty surgery. However, there is no consensus for the bearing surface design, whether there should be different medial, lateral, anterior, and posterior laxities, or whether the medial side should be a medial pivot. This study proposes the criterion of reproducing the laxity of the anatomic knee, defined as the displacements and rotations of the femur on the tibia in the loaded knee when shear and torque are applied. The purpose of this study was to determine the ideal tibial radii to achieve that goal., Methods: The femoral component was based on the average knee from 100 mild arthritic knee scans. There were 8 tibial components that were designed with different sagittal radii: antero-medial, antero-lateral, postero-medial, and postero-lateral. Radii were defined as the percent height reduction from full conformity with the femoral profile. Components were 3-dimensional-printed. A test rig was constructed where the tibial component was fixed and shear and torque were applied to the femoral component. Displacements and rotations of the femoral component were measured at 0 and 45° of flexion, the latter representing any flexion angle due to the constant femoral sagittal radius., Results: Displacements ranged from 0 to 11 mm, and rotations ranged from 1 to 11°. Anterior femoral displacements were higher than posterior due to the shallow distal-anterior femoral profile. The final femoral and tibial components with the most closely matched anatomic laxity values were designed and tested., Conclusions: A steeper distal-anterior femoral radius was an advantage. High medial-anterior tibial conformity was important. However, on the lateral side, the posterior sagittal tibial radius had to be shallower than ideal to allow femoral rollback in high flexion. This meant that the posterior laxity displacements on the lateral side were higher than anatomic, and there was no guidance for lateral femoral rollback., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: Soft tissue balancing is an important step in a total knee procedure, carried out manually, or using an indicator. The purpose of this study was to evaluate our design of 3D printed Balancer, and demonstrate how it could be used at surgery., Procedures: When inserted between the femur and tibia, the Balancer displayed the forces acting across the lateral and medial compartments, indicated by pointers at the end of the handle. A loading rig was used to measure the pointer deflections for different forces applied at different locations on the condyle surfaces. Repeatability and reproducibilty were evaluated. The Balancer was tested in six fresh knee specimens using a surgical simulation rig., Main Findings: Pointer deflections of up to 12 millimeters occurred for less than 1 mm displacements at the condyle surfaces. Reproducibility tests showed a standard deviation of 14% at lower loads, reducing to only 4% at higher loads. Mean pointer deflections were within 8% for forces applied at ±10 mm AP, and +5/-3 mm in an ML direction, relative to the neutral contact point. In specimens, most lateral to medial force differences could be corrected by a 2° change in frontal plane angle of the tibial resection. Effects of ligament releases were also demonstrated., Principal Conclusions: The 3D printed Balancer was easy to use, and provided the surgeon with lateral and medial force data over a full range of flexion, enabling possible corrective procedures to be specified., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Since the introduction of the first total knee designs, a frequent design goal has been to reproduce normal knee motion. However, studies of many currently used total knee designs, have shown that this goal has not been achieved. We proposed that Guided Motion total knee designs, could achieve more anatomic motion than present standard designs., Methods: Several Guided Motion knees for application without cruciate ligaments were designed using a computer method where the bearing surfaces were generated by the motion required. A knee testing machine was constructed where physiological forces including compressive, shear and torque were applied during knee flexion. The neutral path of motion and the laxity about the neutral path were measured. This evaluation method was a modification of the ASTM standard Constraint Test., Results: The motions of the Guided Motion knees and a standard PS knee were compared with the anatomic motion of knee specimens determined in an earlier study The Guided Motion knees showed motion patterns which were closer to anatomic than the PS knee., Conclusions: The results provided justification for carrying out further evaluations of functional conditions, using either knee simulators or computer modelling. If anatomic motions could be reproduced in vivo, it is possible that clinical outcomes could be improved., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Obtaining anatomic knee kinematics after a total knee is likely to improve outcomes. We used a crouching machine to compare the kinematics of standard condylar designs with guided motion designs. The standard condylars included femoral sagittal radii with constant radius, J-curve and G-curve; the tibial surfaces were of low and high constraint. The guided motion designs were a medial pivot and a design with asymmetric condylar shapes and guiding surfaces. The machine had a flexion range from 0° to 125°, applied quadriceps and hamstring loading, and simulated the collateral soft tissues. The kinematics of all standard condylar knees were similar, showing only small anterior-posterior displacements and internal-external rotations. The two asymmetric designs showed posterior displacements during flexion, but less axial rotations than anatomic knees. The quadriceps forces throughout flexion were very similar between all designs, reflecting similar lever arms. It was concluded that standard condylar designs, even with variations in sagittal radii, are unlikely to reproduce anatomic kinematics. On the other hand, designs with asymmetric constraint between medial and lateral sides, and other guiding features, are likely to be the way forward. The mechanical testing method could be further improved by superimposing shear forces and torques during the flexion-extension motion, to include more stressful in vivo functional conditions., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: To measure functional outcome, patient reported outcome measures (PROMs) are most often used but biomechanical tests can provide valuable supplementary data. The objective of this study was to investigate instrumented insoles for measuring ground-to-foot forces during basic activities., Methods: Three groups were evaluated: normal controls, preoperative, and postoperative total knees. The Knee Society Scoring System (KSS) Short Form was used, and with foot pressure sensor insoles, a timed-up-and-go (TUG) test and a sit-to-stand (STS) test was used., Results: Comparing preoperative to postoperative and control groups, there were significant differences in most parameters. There were no significant differences between controls and postoperative knees. Of the 33 correlation coefficients between three PROM parameters and six biomechanical parameters for the three groups, only five coefficients were greater than 0.5., Conclusions: The biomechanical data was substantially independent of the PROM data and provided additional functional evaluation. The most useful parameters were the left-right force ratios during sit-to stand (STS) and the timed-up-and-go (TUG) time.

Implant alignment and soft-tissue balancing are important factors in total knee arthroplasty (TKA). The purpose of this study was to design a mechanical balancing device, which measures deflections resulting from forces applied on each condyle to provide numerical data indicating the extent of ligament release needed, or angular changes in the bone cuts required to achieve a balanced knee. Two mechanical devices were designed and 3D printed, Pistol Grip and In-line. The Pistol Grip design consisted of a lever system that indicated the difference between lateral and medial forces with a single pointer. The In-line design allows for the quantification of the absolute force applied on each individual condyle. The two designs were evaluated on a test rig designed to model balance and imbalance conditions in the knee. For the Pistol Grip design maximum pointer deflection indicates a 2 mm change in elevation per condyle and/or a 3 degrees angular change of the condyles which can be corrected by adjusting the ligament lengths equivalent to 2 mm and/or by modifying the proximal or distal femur bone cut by 3 degrees. For the In-line design, maximum pointer deflection represented a 40 N load on the condyle. Our mechanical balancer designs were successful in providing information that can guide surgeons to accurately achieve balance through ligamentous releases and/or modification to bone cuts. The balancer designs are easy to use, do not require any electronics or software, and can be incorporated into the surgical procedure., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Limb alignment is a critically important factor to consider in the management of the patient with knee arthritis. Abnormal alignment is associated with the accelerated progression of osteoarthritis and, if not addressed at the time of surgery, may contribute to early failure of knee replacement implants. The contribution of the hindfoot to overall limb alignment has received limited attention in the context of deformity correction in total knee arthroplasty (TKA). In this review, we present evidence supporting the inclusion of the hindfoot in the consideration of overall limb alignment for TKA and propose a management algorithm.

Background: ATX-101 is approved for submental fat reduction., Objective: To characterize the histological effect of ATX-101 injection into subcutaneous fat., Methods: This Phase 1 open-label study enrolled 14 adults to receive injections of ATX-101 into abdominal fat at varying concentrations (0.5%, 1.0%, 2.0%, or 4.0%), volumes (0.2 or 0.4 mL), spacing (0.7, 1.0, or 1.5 cm), and time points before scheduled abdominoplasty (1, 3, 7, or 28 days). During abdominoplasty, tissue was excised and preserved for histology., Results: All injection paradigms resulted in histological changes confined to the subcutaneous layer, which were more prominent at higher concentrations and independent of volume and spacing. Key features at Day 1 after injection were adipocytolysis, blood vessel injury, neutrophilic inflammation, and lysis of locally present neutrophils. At Day 3, inflammation was reduced versus Day 1, and hemorrhage and lipid lake formation (at higher concentrations) were observed. Day 7 samples exhibited prominent adipocytolysis, mild inflammation, lipid-laden macrophages in the septae, and repair of vascular injury. At Day 28, inflammation was largely resolved and prominent features were septal thickening, neovascularization, and atrophy of fat lobules., Conclusion: Subcutaneous injection of ATX-101 induces adipocytolysis and local inflammation with septal thickening and resolution of inflammation by 28 days after injection.

Aims: This aim of this study was to assess the feasibility of designing and introducing generic 3D-printed instrumentation for routine use in total knee arthroplasty., Materials and Methods: Instruments were designed to take advantage of 3D-printing technology, particularly ensuring that all parts were pre-assembled, to theoretically reduce the time and skill required during surgery. Concerning functionality, ranges of resection angle and distance were restricted within a safe zone, while accommodating either mechanical or anatomical alignment goals. To identify the most suitable biocompatible materials, typical instrument shapes and mating parts, such as dovetails and screws, were designed and produced., Results: Before and after steam sterilization, dimensional analysis showed that acrylonitrile butadiene styrene could not withstand the temperatures without dimensional changes. Oscillating saw tests with slotted cutting blocks produced debris, fractures, or further dimensional changes in the shape of Nylon-12 and polymethylmethacrylate (MED610), but polyetherimide ULTEM 1010 was least affected., Conclusion: The study showed that 3D-printed instrumentation was technically feasible and had some advantages. However, other factors, such as whether all procedural steps can be accomplished with a set of 3D-printed instruments, the logistics of delivery, and the economic aspects, require further study. Cite this article: Bone Joint J 2019;101-B(7 Supple C):115-120.

Background: Spacer blocks, tensors, or instrumented tibial trials are current methods of balancing the knee during surgery but there are no current techniques for measuring ligament forces. Our goal was to study the relationship between the collateral ligament forces and the condylar contact forces to determine whether there was equivalence., Methods: A test rig was constructed modeling an artificial knee joint with collateral ligaments. The ligament forces as well as the lateral and medial tibial contact forces were measured during flexion for different positions of the femoral component on the femur, producing a set of forces for the simulated conditions. A regression analysis was used to study the correlation between the ligament and contact forces., Results: The combined medial and lateral ligament and contact forces showed a linear relation with a correlation coefficient of 0.98. For the medial and lateral sides separately, the correlations were 0.85 and 0.88, respectively, with more than 80% of points within a ±25% deviation from the linear relations. This deviation from the linear correlation is linked to differences in medial-lateral femoral-tibial contact point locations at different flexion angles., Conclusion: Within balancing accuracies generally achieved at surgery, the collateral ligament forces were linearly correlated to the condylar contact forces. These forces can also be equally correlated to the distraction forces as well as the moments at which condylar liftoff would occur from varus-valgus moments. This indicated a unification of the different balancing parameters, and hence such quantitative methods can be used interchangeably., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Misalignment and soft-tissue imbalance in total knee arthroplasty (TKA) can cause discomfort, pain, inadequate motion and instability that may require revision surgery. Balancing can be defined as equal collateral ligament tensions or equal medial and lateral compartmental forces during the flexion range. Our goal was to study the effects on balancing of linear femoral component misplacements (proximal, distal, anterior, posterior); and different component rotations in mechanical alignment compared to kinematic alignment throughout the flexion path. A test rig was constructed such that the position of a standard femoral component could be adjusted to simulate the linear and rotational positions. With the knee in neutral reference values of the collateral tensions were adjusted to give anatomic contact force patterns, measured with an instrumented tibial trial. The deviations in the forces for each femoral component position were then determined. Compartmental forces were significantly influenced by 2 mm linear errors in the femoral component placement. However, the errors were least for a distal error, equivalent to undercutting the distal femur. The largest errors mainly increase the lateral condyle force, occurred for proximal and posterior component errors. There were only small contact force differences between kinematic and mechanical alignment. Based on these results, surgeons should avoid overcutting the distal femur and undercutting the posterior femur. However, the 2-3 degrees varus slope of the joint line as in kinematic alignment did not have much effect on balancing, so mechanical or kinematic alignment were equivalent., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: The purpose of the study was to investigate the accuracy of balancing which could be achieved at total knee surgery and its relation to functional outcomes., Methods: During surgery, the forces on the medial and lateral plateaus were measured at 10-15 degrees flexion in 101 patients, using an instrumented tibial trial, with equal forces being targeted. Of the initial 101 cases, 71 cases completed all follow-up visits to 1 year. At each follow-up visit, the function was measured using the Knee Society Scoring System, and varus and valgus laxity angles were measured., Results: The mean medial/(medial + lateral) compartmental force ratio was 0.52, with a standard deviation of 0.09. The total contact force was 217 Newtons, with a standard deviation of 72 Newtons. No correlations were found between the functional scores and the compartmental force ratio or total contact force. However, the mean varus and valgus laxity angles, 2.8 and 2.3 degrees, respectively, were very close to the angles of normal intact knees., Conclusions: The likely reason for the lack of correlation of function was that the large majority of the balancing ratios were within the range 0.4-0.6 but with a wide spread of functional scores typical of total knee study groups. However, the normal varus and valgus angles achieved at follow-up indicated that equal balancing in early flexion was a reasonable surgical target. Using instrumented tibial trials enabled accurate and consistent balancing values to be achieved, as well as normal varus and valgus laxity angles, which may be important in obtaining optimal outcomes.

Objective: The objective of this study was to measure the dimensions and the angulations of the femur and tibia for arthritic knees that were scheduled for total knee surgery. The purpose was to provide information for the design of surgical instruments such as cutting guides. Instruments made using three-dimensional printing were a particular consideration because of the variations in sizing that are possible., Materials and Methods: Sixty-six frontal plane EOS radiographs were obtained of patients with osteoarthritis who were under consideration for total knee arthroplasty. The images were imported into computer-assisted design software. The anatomic and mechanical axes and the joint lines were constructed for the femur and tibia. The angles between the axes and lines and key dimensions including the femoral canal diameters were measured., Results: The angle between the anatomic and mechanical axes was 5.5° ± 1.4°, the femoral joint line sloped 2.2°, and the tibial joint line 4.3° to the mechanical axes. The values were similar to non-arthritic knees except for a higher tibial slope. The femoral canal diameter at 150 mm from distal was 19 ± 5 mm., Conclusions: In a total knee replacement procedure, aligning perpendicular to the mechanical axis results on average about 2° more valgus and 2° to 3° tilt of the joint line. Instruments could be calibrated for individual patients, but the maximum variations based on long-term follow-up should be recognized. A multi-diameter system is needed for the femoral intramedullary rod to limit errors to 1° or less.

Accuracy of component and limb alignment are critical parameters for the long-term success of unicompartmental knee implants. In this study, we performed a laboratory evaluation of an instrumentation system which was designed for an early intervention (EI) type of unicompartmental knee. The accuracy of fit was evaluated by implanting in 20 sawbones full leg models. The overall alignment of the limb was compared pre- and postoperatively. The accuracy of placement of each component on its bone was measured. The mean overall alignment angle in the frontal plane was within 1° of target with less than 1° standard deviation. The components were positioned in frontal and sagittal planes with maximum errors of 2°. The angular accuracy was better than in studies reported in the literature for manual instruments, and almost approached the accuracy of computer-assisted systems. The position of the femoral component in the recess was within 1 mm in most cases but the sagittal flexion angle was variable with a standard deviation of 6°. Evaluation of a surgical technique in this way was a valuable method for determining accuracy and for highlighting any deficiencies in the system which could then be corrected., Competing Interests: Peter S. Walker, PhD has been assigned shares in Genovel Inc. through the Office of Industrial Liaison, NYU Langone Medical Center. He is also a consultant for Zimmer on total knee design., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Ligament balancing during total knee replacement (TKR) is receiving increased attention due to its influence on resulting joint kinematics and laxity. We employed a novel in vitro technique to measure the kinematics and laxity of TKR implants during gait, and measured how these characteristics are influenced by implant shape and soft tissue balancing, simulated using virtual ligaments. Compared with virtual ligaments that were equally balanced in flexion and extension, the largest changes in stance-phase tibiofemoral AP and IE kinematics occurred when the virtual ligaments were simulated to be tighter in extension (tibia offset 1.0 ± 0.1 mm posterior and 3.6 ± 0.1° externally rotated). Virtual ligaments which were tight in flexion caused the largest swing-phase changes in AP kinematics (tibia offset 2.3 ± 0.2 mm), whereas ligaments which were tight in extension caused the largest swing-phase changes in IE kinematics (4.2 ± 0.1° externally rotated). When AP and IE loads were superimposed upon normal gait loads, incremental changes in AP and IE kinematics occurred (similar to laxity testing); and these incremental changes were smallest for joints with virtual ligaments that were tight in extension (in both the stance and swing phases). Two different implant designs (symmetric versus medially congruent) exhibited different kinematics and sensitivities to superimposed loads, but demonstrated similar responses to changes in ligament balancing. Our results demonstrate the potential for pre-clinical testing of implants using joint motion simulators with virtual soft tissues to better understand how ligament balancing affects implant motion., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Total knee designs that attempt to reproduce more physiological knee kinematics are gaining attention given their possible improvement in functional outcomes. This study examined if a total knee designed for anatomic motion, where the soft tissue balancing was intended to replicate anatomical tibiofemoral contact forces, can more closely reproduce the laxity of the native knee., Methods: In an ex-vivo setting, the laxity envelope of the knees from nine lower extremity specimens was measured using a rig that reproduced surgical conditions. The rig allowed application of a constant varus/valgus (V/V) and internal-external (I/E) torque through the range of motion. After testing the native knee, total knee arthroplasty (TKA) was performed using the Journey II bi-cruciate substituting implant. Soft tissue balancing was guided by targeting anatomical compressive forces in the lateral and medial tibiofemoral joints with an instrumented tibial trial. After TKA surgery, the laxity tests were repeated and compared to the native condition., Results: The TKA knee closely reproduced the coronal laxity of the native knee, except for a difference at 90° of flexion for valgus laxity. Looking at the rotational laxity, the implant constrained the internal rotation relative to the native knee at 45 and 60° of flexion. The forces on the tibial trial for the neutral path of motion showed higher values on the medial side as the knee flexed., Conclusions: This study suggested that when using an anatomically-designed knee, the soft tissue balancing should also aim for anatomical contact forces, which will result in close to normal laxity patterns., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The design of a total knee replacement implant needs to take account the complex surfaces of the knee which it is replacing. Ensuring design performance of the implant requires in vitro testing of the implant. A considerable amount of time is required to produce components and evaluate them inside an experimental setting. Numerous adjustments in the design of an implant and testing each individual design can be time consuming and expensive. Our solution is to use the OpenSim simulation software to rapidly test multiple design configurations of implants. This study modeled a testing rig which characterized the motion and laxity of knee implants. Three different knee implant designs were used to test and validate the accuracy of the simulation: symmetrical, asymmetric, and anatomic. Kinematics were described as distances measured from the center of each femoral condyle to a plane intersecting the most posterior points of the tibial condyles between 0 and 135° of flexion with 15° increments. Excluding the initial flexion measurement (∼0°) results, the absolute differences between all experimental and simulation results (neutral path, anterior-posterior shear, internal-external torque) for the symmetric, asymmetric, and anatomical designs were 1.98 mm ± 1.15, 1.17 mm ± 0.89, and 1.24 mm ± 0.97, respectively. Considering all designs, the accuracy of the simulation across all tests was 1.46 mm ± 1.07. It was concluded that the results of the simulation were an acceptable representation of the testing rig and hence applicable as a design tool for new total knees., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Introduction: Patients with primary axillary hyperhidrosis (AHH) suffer from a variety of symptoms. Improved patient-reported outcome (PRO) measures are needed to better assess and categorize the severity of AHH symptoms experienced by patients because the widely used Hyperhidrosis Disease Severity Scale (HDSS) is a single-item measure that cannot capture the broad scope of disease impact., Methods: The Hyperhidrosis Disease Severity Measure-Axillary (HDSM-Ax) was developed for determining the severity of excessive sweating in patients with primary focal AHH based on face-to-face concept elicitation interviews with 58 AHH patients, a literature review, and expert clinical input. Two waves of face-to-face cognitive interviews (n=26 and n=27) were conducted to evaluate HDSM-Ax clarity and relevance. Additional interviews (n=5) were conducted to confirm content. Adding Rasch Measurement Theory (RMT) analyses allowed for an iterative streamlined approach to documenting content validity and other cross-sectional measurement properties of the new HDSM-Ax measurement., Results: The 11-item HDSM-Ax PRO scale (0-4 scale per item; 0-44 total scale) represents an AHH symptom range of 0 (no sweating) to 44 (worst possible sweating). Content validity of the HDSM-Ax was documented by showing that chronologically-grouped interviews demonstrated saturation in AHH symptom severity concepts. Cognitive debriefing interviews provided evidence that item content is complete, comprehensible, meaningful, and relevant. RMT-based exploration indicated that targeting of the HDSM-Ax was adequate, suggesting good matching between items and persons; item fit was adequate, suggesting a clinically cohesive scale; and items appeared to be stable between subgroups, thereby supporting a summary score., Conclusions: The HDSM-Ax is a well-developed measure of AHH severity based on patient-reported signs and symptoms. It is a superior measure to the HDSS and can be used in clinical research and clinical practice to quantify changes in symptom severity in response to treatment. J Drugs Dermatol. 2018;17(7):707-714.

Proper tension of the knee's soft tissue envelope is important during total knee arthroplasty; incorrect tensioning potentially leads to joint stiffness or instability. The latter remains an important trigger for revision surgery. The use of sensors quantifying the intra-articular loads, allows surgeons to assess the ligament tension at the time of surgery. However, realistic target values are missing. In the framework of this paper, eight non-arthritic cadaveric specimens were tested and the intra-articular loads transferred by the medial and lateral compartment were measured using custom sensor modules. These modules were inserted below the articulating surfaces of the proximal tibia, with the specimens mounted on a test setup that mimics surgical conditions. For both compartments, the highest loads are observed in full extension. While creating knee flexion by lifting the femur and flexing the hip, mean values (standard deviation) of 114N (71N) and 63N (28N) are observed at 0° flexion for the medial and lateral compartment respectively. Upon flexion, both medial and lateral loads decrease with mean values at 90° flexion of 30N (22N) and 6N (5N) respectively. The majority of the load is transmitted through the medial compartment. These observations are linked to the deformation of the medial and lateral collaterals, in addition to the anatomy of the passive soft tissues surrounding the knee. In conclusion, these findings provide tangible clinical guidance in assessing the soft tissue loads when dealing with anatomically designed total knee implants., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The anterior-posterior (AP) stability of the knee is an important aspect of functional performance. Studies have shown that the stability increases when compressive loads are applied, as indicated by reduced laxity, but the mechanism has not been fully explained. A test rig was designed which applied combinations of AP shear and compressive forces, and measured the AP displacements relative to the neutral position. Five knees were evaluated at compressive loads of 0, 250, 500, and 750N, with the knee at 15° flexion. At each load, three cycles of shear force at ±100N were applied. For the intact knee under load, the posterior tibial displacement was close to zero, due to the upward slope of the anterior medial tibial surface. The soft tissues were then resected in sequence to determine their role in AP laxity. After anterior cruciate ligament (ACL) resection, the anterior tibial displacement increased significantly even under load, highlighting its importance in stability. Meniscal resection further increased displacement but also the vertical displacement increased, implying the meniscus was providing a buffering effect. The PCL had no effect on any of the displacements under load. Plowing cartilage deformation and surface friction were negligible. This work highlighted the particular importance of the upward slope of the anterior medial tibial surface and the ACL to AP knee stability under load. The results are relevant to the design of total knees which reproduce anatomic knee stability behavior., (Copyright © 2017. Published by Elsevier Ltd.)

A design concept was formulated for implants to treat medial osteoarthritis of the knee, using a metal plate resurfacing of the tibia plateau and a plastic bearing embedded in the distal end of the femur. A finite element analysis was carried out to determine whether a metal backing would be needed for the femoral component, and to what extent the stress and strain distribution in the trabecular bone surrounding the implant would match the normal intact condition. The CT scans from three knees scheduled for unicompartmental replacement were selected to generate computer models with variable bone densities in each element to cover a range of density patterns. Loading conditions were defined for a range of flexion angles, from loads at the center to the end of the component. A 2-peg fixation design was analyzed for both an all-plastic and a metal-backed construction. For the metal-backed, the interface von Mises stresses were close to intact values at the same level in the bone, although there was a 34 percent increase for loading at the end of the component. However, the all-plastic gave stresses elevated up to 109 percent. The maximum principal strain values for metal-backed in the trabecular bone below the implant were variable between specimens but close to intact under all conditions. In contrast the all-plastic showed strains up to 81 percent increased. The metal pegs showed load transfer, but the loads transmitted by the plastic pegs was small, as evidenced by the low interface stresses. The conclusion was that metal-backing was necessary to avoid excessive bone stresses and strains, while metal peg fixation was evidently an advantage., (Copyright © 2016. Published by Elsevier Ltd.)

Background: Balancing is an important part of a total knee procedure, and in recent years, more emphasis has been given to quantifying the process., Methods: During 101 total knee surgeries, initial bone cuts were made using navigation. Lateral and medial contact forces were determined throughout flexion using an instrumented tibial trial. Balancing was defined as a ratio of the medial and total force, the target being 0.5 (equal lateral and medial forces). Based on the initial values, surgical corrections were selected to achieve balancing. The most common corrections were soft tissue releases (63 incidences), including MCL, posterolateral corner, posteromedial corner, and changing tibial insert thicknesses (34 incidences)., Results: After final balancing, the mean ratio was 0.52 ± 0.14, between 0.35 and 0.65 being achieved in 80% of cases. In 84% of cases, only 0-2 corrections were required. The average total force on the condyles was 215 ± 86 N., Conclusion: Our study provides data to surgeons on the results to expect when balancing a knee, which can enhance both accuracy and consistency of the procedure., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: The purpose of this study was to use MRI to determine if a loss of meniscal intra-substance integrity, as determined by T2* relaxation time, is associated with an increase of Kellgren-Lawrence (KL) grade, and if this was correlated with risk factors for cartilage degeneration, namely meniscal extrusion, contact area and anterior-posterior (AP) displacement., Methods: Eleven symptomatic knees with a KL 2 to 4 and 11 control knees with a KL 0 to 1 were studied. A 3 Tesla MRI scanner was used to scan all knees at 15° of flexion. With a 222N compression applied, a 3D SPACE sequence was obtained, followed by a spin echo 3D T2* mapping sequence. Next, an internal tibial torque of 5Nm was added and a second 3D SPACE sequence obtained. The MRI scans were post-processed to evaluate meniscal extrusion, contact area, AP displacement and T2* relaxation time., Results: KL grade was correlated with T2* relaxation time for both the anterior medial meniscus (r=0.79, p<0.001) and the posterior lateral meniscus (r=0.55, p=0.009). In addition, T2* relaxation time was found to be correlated with risk factors for cartilage degeneration. The largest increases in meniscal extrusion and decreases in contact area were noted for those with meniscal tears (KL 3 to 4). All patients with KL 3 to 4 indicated evidence of meniscal tears., Conclusions: This suggests that a loss of meniscal integrity, in the form of intra-substance degeneration, is correlated with risk factors for cartilage degeneration., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Considerable debate remains over which anterior cruciate ligament (ACL) reconstruction technique can best restore knee stability. Traditionally, femoral tunnel drilling has been done through a previously drilled tibial tunnel; however, potential nonanatomic tunnel placement can produce a vertical graft, which although it would restore sagittal stability, it would not control rotational stability. To address this, some suggest that the femoral tunnel be created independently of the tibial tunnel through the use of an anteromedial (AM) portal, but whether this results in a more anatomic footprint or in stability comparable to that of the intact contralateral knee still remains controversial., Questions/purposes: (1) Does the AM technique achieve footprints closer to anatomic than the transtibial (TT) technique? (2) Does the AM technique result in stability equivalent to that of the intact contralateral knee? (3) Are there differences in patient-reported outcomes between the two techniques?, Methods: Twenty male patients who underwent a bone-patellar tendon-bone autograft were recruited for this study, 10 in the TT group and 10 in the AM group. Patients in each group were randomly selected from four surgeons at our institution with both groups demonstrating similar demographics. The type of procedure chosen for each patient was based on the preferred technique of the surgeon. Some surgeons exclusively used the TT technique, whereas other surgeons specifically used the AM technique. Surgeons had no input on which patients were chosen to participate in this study. Mean postoperative time was 13 ± 2.8 and 15 ± 3.2 months for the TT and AM groups, respectively. Patients were identified retrospectively as having either the TT or AM Technique from our institutional database. At followup, clinical outcome scores were gathered as well as the footprint placement and knee stability assessed. To assess the footprint placement and knee stability, three-dimensional surface models of the femur, tibia, and ACL were created from MRI scans. The femoral and tibial footprints of the ACL reconstruction as compared with the intact contralateral ACL were determined. In addition, the AP displacement and rotational displacement of the femur were determined. Lastly, as a secondary measurement of stability, KT-1000 measurements were obtained at the followup visit. An a priori sample size calculation indicated that with 2n = 20 patients, we could detect a difference of 1 mm with 80% power at p < 0.05. A Welch two-sample t-test (p < 0.05) was performed to determine differences in the footprint measurements, AP displacement, rotational displacement, and KT-1000 measurements between the TT and AM groups. We further used the confidence interval approach with 90% confidence intervals on the pairwise mean group differences using a Games-Howell post hoc test to assess equivalence between the TT and AM groups for the previously mentioned measures., Results: The AM and TT techniques were the same in terms of footprint except in the distal-proximal location of the femur. The TT for the femoral footprint (DP%D) was 9% ± 6%, whereas the AM was -1% ± 13% (p = 0.04). The TT technique resulted in a more proximal footprint and therefore a more vertical graft compared with intact ACL. The AP displacement and rotation between groups were the same and clinical outcomes did not demonstrate a difference., Conclusions: Although the AM portal drilling may place the femoral footprint in a more anatomic position, clinical stability and outcomes may be similar as long as attempts are made at creating an anatomic position of the graft., Level of Evidence: Level III, therapeutic study.

Mechanical evaluation of total knees is frequently required for aspects such as wear, strength, kinematics, contact areas, and force transmission. In order to carry out such tests, we developed a crouching simulator, based on the Oxford-type machine, with novel features including a synthetic knee including ligaments. The instrumentation and data processing methods enabled the determination of contact area locations and interface forces and moments, for a full flexion-extension cycle. To demonstrate the use of the simulator, we carried out a comparison of two different total knee designs, cruciate retaining and substituting. The first part of the study describes the simulator design and the methodology for testing the knees without requiring cadaveric knee specimens. The degrees of freedom of the anatomic hip and ankle joints were reproduced. Flexion-extension was obtained by changing quadriceps length, while variable hamstring forces were applied using springs. The knee joint was represented by three-dimensional printed blocks on to which the total knee components were fixed. Pretensioned elastomeric bands of realistic stiffnesses passed through holes in the block at anatomical locations to represent ligaments. Motion capture of the knees during flexion, together with laser scanning and computer modeling, was used to reconstruct contact areas on the bearing surfaces. A method was also developed for measuring tibial component interface forces and moments as a comparative assessment of fixation. The method involved interposing Tekscan pads at locations on the interface. Overall, the crouching machine and the methodology could be used for many different mechanical measurements of total knee designs, adapted especially for comparative or parametric studies., (© IMechE 2016.)

The goal of this study was to determine knee motions in specimens under combined input forces over a full range of flexion, so that the various flexion angles and loading combinations encountered in functional conditions would be contained. The purpose was that the data would act as a benchmark for the evaluation of TKR designs using the same testing methodology. We measured the neutral path of motion and laxity about the neutral path. The femur was flexed in a continuous movement, rather than at discrete flexion angles, using optical tracking. The motion of the femoral circular axis relative to the tibia was determined, as well as the contact patches on the tibial surfaces. The neutral path of motion was independent of compressive load, and consisted of a relatively constant medial contact and steady posterior displacement laterally, in agreement with previous studies. The anterior-posterior laxities of the lateral and medial condyles were similar whether AP forces or torques were applied. The lateral laxity was predominantly anterior with respect to the neutral path, while on the medial side, the laxity was less than lateral and predominantly posterior of the neutral path. Contact on the anterior surface of the medial tibial plateau only occurred in some cases in 5° hyperextension and at 0° flex when an anterior femoral shear or an external femoral torque were applied. The method can be regarded as a development of the ASTM constraint standard, with the addition of the benchmark, for the evaluation of total knee designs., (Copyright © 2015 Elsevier Ltd. All rights reserved.)