Dynamic Knee Joint Line Orientation Is Not Predictive of Tibio-Femoral Load Distribution During Walking

Surgical planning in HTO - alternative approaches to the Fujisawa gold-standard

BackgroundPresurgical planning of the correction angle plays a decisive role in a high tibial osteotomy, affecting the loading situation in the knee affected by osteoarthritis. The planning approach by Fujisawa et al. aims to adjust the weight-bearing line to achieve an optimal knee joint load distribution. While this method is accessible, it may not fully consider the complexity of individual dynamic knee-loading profiles. This review aims to disclose existing alternative HTO planning methods that do not follow Fujisawa's standard.MethodsPubMed, Web of Science and CENTRAL databases were screened, focusing on HTO research in combination with alternative planning approaches.ResultsEight out of 828 studies were included, with seven simulation studies based on finite element analysis and multi-body dynamics. The planning approaches incorporated gradual degrees of realignment parameters (weight-bearing line shift, medial proximal tibial angle, hip-knee-ankle, knee joint line orientation), simulating their effect on knee kinematics, contact force/stress, Von Mises and shear stress. Two studies proposed implementing individual correction magnitudes derived from preoperatively predicted knee adduction moments.ConclusionMost planning methods depend on static alignment assessments, neglecting an adequate loading-depending profile. They are confined to their conceptual phases, making the associated planning methods unviable for current clinical use.

Kinematic alignment achieves a tibial joint line angle that is more parallel to the floor in single-leg stance than mechanical alignment : a radiological analysis of a randomized controlled trial

Aims

Previous research on knee kinematics has demonstrated that achieving a tibial joint line angle (TJLA) parallel to the floor in the single-leg stance phase of gait may restore native knee kinematics and optimize compartmental compressive loads in total knee arthroplasty (TKA). However, it is currently unclear which surgical alignment strategy best achieves this. Therefore, this study sought to determine whether kinematically aligned (KA) or mechanically aligned (MA) TKAs produce a TJLA closer to parallel.

Methods

A total of 95 patients were randomized to KA (n = 46) or MA (n = 49). Constitutional joint line obliquity (JLO) was measured from preoperative radiographs; TJLA was measured from postoperative radiographs. The primary outcome was the mean difference in TJLA between KA and MA in single-leg stance. Secondary outcomes included differences in TJLA between apex distal and neutral JLO knees, the proportion of patients with TJLA within approximately 2° of neutral, and changes in constitutional JLO between alignment groups.

Results

In single-leg stance, the mean TJLA was closer to parallel with KA (-2.0° (SD 2.6°)) than MA (-4.5° (SD 1.9°); p < 0.001). Similar mean differences were observed in patients with apex distal JLO (KA -1.4° (SD 2.1°); MA -4.9° (SD 1.8°); p < 0.001) but not neutral JLO (KA -3.7° (SD 2.8°); MA -3.7° (SD 1.9°); p = 0.776). More patients had a TJLA within 2° of parallel with KA (n = 24; 52.2%) than MA (n = 4; 8.2%; p < 0.001), and KA resulted in significantly less change to constitutional JLO.

Conclusion

A TJLA parallel to the floor in single-leg stance is achieved more readily with KA than MA, but is dependent on constitutional JLO. A parallel TJLA during this phase of gait is more likely achieved when alignment is individualized to the patient's native anatomy.

Impact of the external knee flexion moment on patello-femoral loading derived from in vivo loads and kinematics

Introduction

Anterior knee pain and other patello-femoral (PF) complications frequently limit the success of total knee arthroplasty as the final treatment of end stage osteoarthritis. However, knowledge about the in-vivo loading conditions at the PF joint remains limited, as no direct measurements are available. We hypothesised that the external knee flexion moment (EFM) is highly predictive of the PF contact forces during activities with substantial flexion of the loaded knee.

Materials and methods

Six patients (65-80 years, 67-101 kg) with total knee arthroplasty (TKA) performed two activities of daily living: sit-stand-sit and squat. Tibio-femoral (TF) contact forces were measured in vivo using instrumented tibial components, while synchronously internal TF and PF kinematics were captured with mobile fluoroscopy. The measurements were used to compute PF contact forces using patient specific musculoskeletal models. The relationship between the EFM and the PF contact force was quantified using linear regression.

Results

Mean peak TF contact forces of 1.97-3.24 times body weight (BW) were found while peak PF forces reached 1.75 to 3.29 times body weight (BW). The peak EFM ranged from 3.2 to 5.9 %BW times body height, and was a good predictor of the PF contact force (R 2 = 0.95 and 0.88 for sit-stand-sit and squat, respectively).

Discussion

The novel combination of in vivo TF contact forces and internal patellar kinematics enabled a reliable assessment of PF contact forces. The results of the regression analysis suggest that PF forces can be estimated based solely on the EFM from quantitative gait analysis. Our study also demonstrates the relevance of PF contact forces, which reach magnitudes similar to TF forces during activities of daily living.

Bioelectronic Medicines-A Novel Approach of Therapeutics in Current Epoch

BACKGROUND

Bioelectronic medicines aim to diagnose and treat a wide range of illnesses and ailments, including cancer, rheumatoid arthritis, inflammatory bowel disease, obesity, diabetes, asthma, paralysis, blindness, bleeding, ischemia, organ transplantation, cardiovascular disease, and neurodegenerative diseases. The focus of bioelectronic medicine is on electrical signaling of the nervous system. Understanding the nervous system's regulatory roles and developing technologies that record, activate, or inhibit neural signaling to influence particular biological pathways.

OBJECTIVE

Bioelectronic medicine is an emerging therapeutic option with the interconnection between molecular medicine, neuroscience, and bioengineering. The creation of nerve stimulating devices that communicate with both the central and peripheral nervous systems has the potential to completely transform how we treat disorders. Although early clinical applications have been largely effective across entire nerves, the ultimate goal is to create implantable, miniature closed-loop systems that can precisely identify and modulate individual nerve fibers to treat a wide range of disorders.

METHODOLOGY

The data bases such as PubMed, and Clinicaltrial.gov.in were searched for scientific research, review and clinical trials on bioelectronic medicine.

CONCLUSION

The field of bioelectronic medicine is trending at present. In recent years, researchers have extended the field's applications, undertaken promising clinical trials, and begun delivering therapies to patients, thus creating the groundwork for significant future advancements. Countries and organizations must collaborate across industries and regions to establish an atmosphere and guidelines that foster the advancement of the field and the fulfillment of its prospective advantages.

Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Paradoxical Change in Subchondral Bone Density in the Medial Compartment of the Proximal Tibial Articular Surface After High Tibial Osteotomy: A Detailed Subchondral Bone Density Analysis

BACKGROUND

High tibial osteotomy (HTO) aims to realign the varus knee to alleviate stress in the medial compartment. However, detailed information on the impact of HTO on stress distribution across the tibiofemoral joint surface still needs to be completely elucidated.

PURPOSE/HYPOTHESIS

The present study aimed to analyze the subchondral bone density distribution to validate the alignment threshold causing paradoxical changes. We hypothesized that there would be a paradoxical stress change in the medial compartment beyond a specific threshold for lower limb realignment after HTO.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective clinical study of 32 knees from 30 patients who underwent medial opening-wedge HTO between 2015 and 2019 was conducted at Hokkaido University Hospital. The subchondral bone density across the tibiofemoral joint was analyzed using computed tomography-osteoabsorptiometry before and after HTO. The high-density area (HDA) within the medial and lateral compartments and their subregions, which were quartered in the coronal plane, was specifically examined.

RESULTS

The hip-knee-ankle angle, medial proximal tibial angle (MPTA), joint line obliquity (JLO), and joint line convergence angle significantly changed after HTO (P < .01). The HDA of the medial compartment to the total HDA ratio decreased from 83% to 77%. Paradoxically, the HDA in the most central subregion of the medial compartment increased from 24% to 30%. There were significant differences between MPTA and JLO in patients with and without paradoxical changes in the HDA. MPTA and JLO cutoff values causing paradoxical changes in the HDA were 94° and 4°, respectively.

CONCLUSION

There was a paradoxical stress increase in the M4 region at the medial compartment associated with the MPTA and JLO beyond specific thresholds. Therefore, surgical planning should be cautiously performed to prevent overcorrection, which can lead to adverse stress distribution changes.

Asymmetric gap balancing improves knee kinematic following primary total knee arthroplasty

PURPOSE

The purpose of this study was to demonstrate closer-to-normal knee kinematics following primary total knee arthroplasty (TKA) performed establishing asymmetric gap balancing intraoperatively.

MATERIAL AND METHOD

Two age-, sex-, BMI-matched groups of patients underwent medially stabilized TKA because of isolated knee disease. Group A (12 patients) underwent "unrestricted" kinematic alignment (uKA) according to Howell while group B (15 patients) received robot-assisted "simplified" KA (sKA) with an alignment goal (Hip-Knee-Ankle axis-HKA) ± 5° respect to the mechanical axis. Intraoperatively, in group B, the flexion gap at 90° was first set at an average of 1.5 mm (0-5 mm; SD 4.4 mm) tighter in the medial compartment with respect to the lateral; in the same way, the extension gap was then set at an average of 2.0 mm (0-4.5 mm; SD 3.1 mm) tighter in the medial compartment with respect to the lateral. All patients, including a non-arthritic cohort (group C: 5 controls) underwent gait analysis using an instrumented treadmill (WalkerView-WV) equipped with an instrumented belt armed with a 3D video camera. The WV software evaluated multiple spatiotemporal and kinematic parameters, including: (1) contact time (s); (2) knee ROM during gait cycle; (3) step length percentage with respect to total gait (%) and pure step length (cm). Statistical analyses included t-Test and ANOVA and were conducted by using SPSS.

RESULTS

At the final FU, significant differences were noted during gait between the two TKA groups (uKA-sKA) and the controls. Both TKA groups showed superior mean contact time on the surgical knee (uKA 1 s; sKA 0.97 s) as compared to the controls (0.72 s) (P = 0.002) while no differences were found between them (P = 0.11). TKA groups showed a lower, maximum ROM in the surgical knee (mean uKA 36º; mean sKA 49º) relative to the controls (mean 57º) (P < 0.05) but a statistical difference was found between them (P = 0.003). Both TKA groups showed a higher step length percentage with respect to the total gait and a shorter step length on the surgical side (uKA: mean 8.28% and mean step length 35.5 cm; sKA: mean 8.38% and mean step length 34.6 cm) in comparison to the controls (mean 3.38%; mean step length 71.4 cm) (P < 0.05) while no statistical differences were found between them.

CONCLUSION

To our knowledge, this was the first study to exhibit the kinematic advantages of a slightly asymmetric gap balancing during KA TKA. Combining a medially-stabilized implant design and a surgical technique aiming to obtain a tighter medial compartment represents a promising approach to improve outcomes after TKA.

Medial and lateral knee contact forces during walking, stair ascent and stair descent are more affected by contact locations than tibiofemoral alignment in knee osteoarthritis patients with varus malalignment

Introduction: Knee OA progression is related to medial knee contact forces, which can be altered by anatomical parameters of tibiofemoral alignment and contact point locations. There is limited and controversial literature on medial-lateral force distribution and the effect of anatomical parameters, especially in motor activities different from walking. We analyzed the effect of tibiofemoral alignment and contact point locations on knee contact forces, and the medial-lateral force distribution in knee OA subjects with varus malalignment during walking, stair ascending and stair descending. Methods: Fifty-one knee OA subjects with varus malalignment underwent weight-bearing radiographs and motion capture during walking, stair ascending and stair descending. We created a set of four musculoskeletal models per subject with increasing level of personalization, and calculated medial and lateral knee contact forces. To analyze the effect of the anatomical parameters, statistically-significant differences in knee contact forces among models were evaluated. Then, to analyze the force distribution, the medial-to-total contact force ratios were calculated from the fully-informed models. In addition, a multiple regression analysis was performed to evaluate correlations between forces and anatomical parameters. Results: The anatomical parameters significantly affected the knee contact forces. However, the contact points decreased medial forces and increased lateral forces and led to more marked variations compared to tibiofemoral alignment, which produced an opposite effect. The forces were less medially-distributed during stair negotiation, with medial-to-total ratios below 50% at force peaks. The anatomical parameters explained 30%-67% of the variability in the knee forces, where the medial contact points were the best predictors of medial contact forces. Discussion: Including personalized locations of contact points is crucial when analyzing knee contact forces in subjects with varus malalignment, and especially the medial contact points have a major effect on the forces rather than tibiofemoral alignment. Remarkably, the medial-lateral force distribution depends on the motor activity, where stair ascending and descending show increased lateral forces that lead to less medially-distributed loads compared to walking.

Bioelectronic multifunctional bone implants: recent trends

The concept of Instrumented Smart Implant emerged as a leading research topic that aims to revolutionize the field of orthopaedic implantology. These implants have been designed incorporating biophysical therapeutic actuation, bone-implant interface sensing, implant-clinician communication and self-powering ability. The ultimate goal is to implement revist interface, controlled by clinicians/surgeons without troubling the quotidian activities of patients. Developing such high-performance technologies is of utmost importance, as bone replacements are among the most performed surgeries worldwide and implant failure rates can still exceed 10%. In this review paper, an overview to the major breakthroughs carried out in the scope of multifunctional smart bone implants is provided. One can conclude that many challenges must be overcome to successfully develop them as revision-free implants, but their many strengths highlight a huge potential to effectively establish a new generation of high-sophisticated biodevices.