The Value of Using Patient-Specific 3D-Printed Anatomical Models in Surgical Planning for Patients With Complex Multifibroid Uteri.

OBJECTIVES: To compare surgeon responses regarding their surgical plan before and after receiving a patient-specific three-dimensional (3D)-printed model of a patient's multifibroid uterus created from their magnetic resonance imaging. METHODS: 3D-printed models were derived from standard-of-care pelvic magnetic resonance images of patients scheduled for surgical intervention for multifibroid uterus. Relevant anatomical structures were printed using a combination of transparent and opaque resin types. 3D models were used for 7 surgical cases (5 myomectomies, 2 hysterectomies). A staff surgeon and 1 or 2 surgical fellow(s) were present for each case. Surgeons completed a questionnaire before and after receiving the model documenting surgical approach, perceived difficulty, and confidence in surgical plan. A postoperative questionnaire was used to assess surgeon experience using 3D models. RESULTS: Two staff surgeons and 3 clinical fellows participated in this study. A total of 15 surgeon responses were collected across the 7 cases. After viewing the models, an increase in perceived surgical difficulty and confidence in surgical plan was reported in 12/15 and 7/15 responses, respectively. Anticipated surgical time had a mean ± SD absolute change of 44.0 ± 47.9 minutes and anticipated blood loss had an absolute change of 100 ± 103.5 cc. 2 of 15 responses report a change in pre-surgical approach. Intra-operative model reference was reported to change the dissection route in 8/15 surgeon responses. On average, surgeons rated their experience using 3D models 8.6/10 for pre-surgical planning and 8.1/10 for intra-operative reference. CONCLUSIONS: Patient-specific 3D anatomical models may be a useful tool to increase a surgeon's understanding of complex gynaecologic anatomy and to improve their surgical plan. Future work is needed to evaluate the impact of 3D models on surgical outcomes in gynaecology.

Endometriosis Imaging: Enter the Metaverse of Possibilities.

Although laparoscopy has classically been defined as the gold standard for diagnosis of endometriosis, there is now a strong recommendation for the use of advanced imaging in diagnosing the disease. In addition to playing a crucial role in the diagnosis of endometriosis, advanced imaging is also essential for assisting gynaecologic surgeons in planning the surgical management of complex cases of deep endometriosis. This case demonstrates a metaverse of high-level imaging modalities, including advanced ultrasound and magnetic resonance, which were further enhanced with medical virtual reality and used for the assessment of a patient seen in an outpatient tertiary care gynaecology clinic.

Individualized medicine using 3D printing technology in gynecology: a scoping review.

OBJECTIVE: Developments in 3-dimensional (3D) printing technology has made it possible to produce high quality, affordable 3D printed models for use in medicine. As a result, there is a growing assessment of this approach being published in the medical literature. The objective of this study was to outline the clinical applications of individualized 3D printing in gynecology through a scoping review. DATA SOURCES: Four medical databases (Medline, Embase, Cochrane CENTRAL, Scopus) and grey literature were searched for publications meeting eligibility criteria up to 31 May 2021. STUDY ELIGIBILITY CRITERIA: Publications were included if they were published in English, had a gynecologic context, and involved production of patient specific 3D printed product(s). STUDY APPRAISAL AND SYNTHESIS METHODS: Studies were manually screened and assessed for eligibility by two independent reviewers and data were extracted using pre-established criteria using Covidence software. RESULTS: Overall, 32 studies (15 abstracts,17 full text articles) were included in the scoping review. Most studies were either case reports (12/32,38%) or case series (15/32,47%). Gynecologic sub-specialties in which the 3D printed models were intended for use included: gynecologic oncology (21/32,66%), benign gynecology (6/32,19%), pediatrics (2/32,6%), urogynecology (2/32,6%) and reproductive endocrinology and infertility (1/32,3%). Twenty studies (63%) printed 5 or less models, 6/32 studies (19%) printed greater than 5 (up to 50 models). Types of 3D models printed included: anatomical models (11/32,34%), medical devices, (2/32,6%) and template/guide/cylindrical applicators for brachytherapy (19/32,59%). CONCLUSIONS: Our scoping review has outlined novel clinical applications for individualized 3D printed models in gynecology. To date, they have mainly been used for production of patient specific 3D printed brachytherapy guides/applicators in patients with gynecologic cancer. However, individualized 3D printing shows great promise for utility in surgical planning, surgical education, and production of patient specific devices, across gynecologic subspecialties. Evidence supporting the clinical value of individualized 3D printing in gynecology is limited by studies with small sample size and non-standardized reporting, which should be the focus of future studies.

Altered movement strategy during functional movement after an ACL injury, despite ACL reconstruction.

Knee joint functional deficits are common after anterior cruciate ligament (ACL) injury, but different assessment methods of joint function seem to provide contradicting information complicating recovery monitoring. We previously reported improved perceived knee function and functional performance (forward lunge ground contact time) in patients with an ACL injury from pre to 10 months post ACL reconstruction without improvement in knee-specific biomechanics. To further investigate this discrepancy, we additionally analyzed knee extensor and flexor muscle strength, and movement quality in the forward lunge (subjective and objective evaluations) and performed a full lower limb biomechanical analysis of the forward lunge movement. We included 12 patients with an ACL injury (tested before and after ACL reconstructive surgery) and 15 healthy controls from the previous study to the current investigation. Outcome measures were obtained pre and ~11 months post ACL reconstruction for the patients and at a single time point for the controls. Objective movement quality in the patients with an ACL injury showed an improvement from their pre reconstruction surgery visit to the post reconstruction visit but this was not observable in the subjective evaluation. Knee extensor muscle strength declined after the ACL reconstruction by 29% (p = 0.002) and both knee extensors (p < 0.001) and flexors (p = 0.027) were weaker in the patients post ACL reconstruction compared to healthy controls. ACL injured patients had an altered movement strategy in the forward lunge with reduced knee extensors contribution and increased hip extensor contribution compared to the controls both before and after the reconstruction. The altered movement strategy was associated with knee extensor muscle strength. This explorative study with a limited sample size found that clinicians should be aware that significant functional deficits in the knee extensor muscles, both in isolated muscle strength testing and during a functional movement, may be present although patients perceive an improvement in their knee function and present good functional performance without obvious movement quality issues.

Females with knee osteoarthritis use a detrimental knee loading strategy when squatting.

BACKGROUND: The purpose of this study was to identify sex differences in lower limb kinematics, kinetics, and muscle activation patterns between individuals with osteoarthritis and healthy controls during a two-legged squat. METHOD: Thirty OA (15 females) and 30 healthy (15 females) participants performed three 2-legged squats. Sagittal and frontal plane hip, knee, and ankle kinematics and kinetics were calculated. Two-way ANOVAs (Sex X OA Status) were used to characterize differences in squatting strategies between sexes and between those with and without knee OA. RESULTS: A greater decrease in sagittal hip, knee, and ankle range of motion and knee joint power was observed in the OA participants compared to the healthy controls. Females with OA had significantly reduced hip and knee adduction angles compared to the healthy females and males with OA. Females also had decreased hip power, hip flexion, and hip adduction moments and knee adduction moments compared to their male counterparts, with the greatest deficits observed in the females with OA. Females with OA also had the highest magnitude of muscle activation for the quadriceps, hamstrings, and gastrocnemius throughout the squat, while males with OA showed increased activation of the vastus lateralis and medial gastrocnemius compared to the healthy males. CONCLUSIONS: OA significantly altered biomechanics and neuromuscular control during the squat, with males employing a hip-dominant strategy, allowing them to achieve a greater lower limb range of motion.

Outpatient hysteroscopy is effective for uterine cavity evaluation following failed office-based endometrial biopsy.

BACKGROUND: Failure to obtain an office-based endometrial biopsy for abnormal uterine bleeding is not uncommon. Although operating room-based procedures are traditionally considered the gold standard assessment tool in these circumstances, outpatient hysteroscopy is a less invasive, more cost-effective, and safer alternative. However, there is no contemporary Canadian literature on the effectiveness of an outpatient approach for this specific population. OBJECTIVE: We aim to evaluate the effectiveness and outcomes of outpatient hysteroscopy for uterine cavity evaluation for patients who have failed an in-office endometrial biopsy attempt. METHODS: We conducted a retrospective cohort study of all patients referred to an academic outpatient hysteroscopy unit between January 2015 and January 2018, who underwent an outpatient hysteroscopy following failed endometrial biopsy. Data were collected from electronic medical records. RESULTS: Of the 407 consecutive patients who underwent an outpatient hysteroscopic procedure, 68 met inclusion criteria. Postmenopausal bleeding was the most common indication for initial biopsy, and most failures were attributed to cervical stenosis. Outpatient hysteroscopies were successfully completed in 96% of cases (n = 65/68). Failure resulted from either anxiety and discomfort (n = 2), or severe intrauterine adhesions (n = 1). Overall, 10% of patients subsequently required an operating room-based hysteroscopy, either to complete a myomectomy or polypectomy, or to allow general anesthesia. Outpatient hysteroscopy identified endometrial hyperplasia and cancer in 4.5% and 3% of patients, respectively. CONCLUSION: Outpatient hysteroscopy following unsuccessful office endometrial biopsy attempts appears to be a feasible, safe, and cost-effective investigation strategy that may prevent the need for an operating room-based procedure in 90% of cases.

A review and guide to creating patient specific 3D printed anatomical models from MRI for benign gynecologic surgery.

BACKGROUND: Patient specific three-dimensional (3D) models can be derived from two-dimensional medical images, such as magnetic resonance (MR) images. 3D models have been shown to improve anatomical comprehension by providing more accurate assessments of anatomical volumes and better perspectives of structural orientations relative to adjacent structures. The clinical benefit of using patient specific 3D printed models have been highlighted in the fields of orthopaedics, cardiothoracics, and neurosurgery for the purpose of pre-surgical planning. However, reports on the clinical use of 3D printed models in the field of gynecology are limited. MAIN TEXT: This article aims to provide a brief overview of the principles of 3D printing and the steps required to derive patient-specific, anatomically accurate 3D printed models of gynecologic anatomy from MR images. Examples of 3D printed models for uterine fibroids and endometriosis are presented as well as a discussion on the barriers to clinical uptake and the future directions for 3D printing in the field of gynecological surgery. CONCLUSION: Successful gynecologic surgery requires a thorough understanding of the patient's anatomy and burden of disease. Future use of patient specific 3D printed models is encouraged so the clinical benefit can be better understood and evidence to support their use in standard of care can be provided.

Bowel surgery for endometriosis: A practical look at short- and long-term complications.

Endometriosis involving the bowel requires a thorough evaluation prior to deciding upon surgical treatment. Patient symptoms, treatment goals, extent and location of disease, surgeon experience, and anticipated risks all play a part in the preoperative decision-making process. Short- and long-term complications after bowel surgery for endometriosis are the focus of this article. Unfortunately, the literature to date has inherent limitations that prevent generalizability. Most studies are retrospective or prospective single-center case series. Publication bias is unavoidable with mainly large volume experts sharing their experience. As a result, there is a need for high-quality prospective studies that standardize inclusion criteria and outcome measures among various centers with an aim to present long-term outcomes. In the meantime, care for those with endometriosis involving the bowel requires a thorough preoperative plan to minimize risks and a need for early diagnosis and management of complications unique to bowel surgery.

Functional muscle synergies to support the knee against moment specific loads while weight bearing.

OBJECTIVE: Externally applied abduction and rotational loads are major contributors to the knee joint injury mechanism; yet, how muscles work together to stabilize the knee against these loads remains unclear. Our study sought to evaluate lower limb functional muscle synergies in healthy young adults such that muscle activation can be directly related to internal knee joint moments. METHODS: Concatenated non-negative matrix factorization extracted muscle and moment synergies of 22 participants from electromyographic signals and joint moments elicited during a weight-bearing force matching protocol. RESULTS: Two synergy sets were extracted: Set 1 included four synergies, each corresponding to a general anterior, posterior, medial, or lateral force direction. Frontal and transverse moments were coupled during medial and lateral force directions. Set 2 included six synergies, each corresponding to a moment type (extension/flexion, ab/adduction, internal/external rotation). Hamstrings and quadriceps dominated synergies associated with respective flexion and extension moments while quadriceps-hamstring co-activation was associated with knee abduction. Rotation moments were associated with notable contributions from hamstrings, quadriceps, gastrocnemius, and hip ab/adductors, corresponding to a general co-activation muscle synergy. CONCLUSION: Our results highlight the importance of muscular co-activation of all muscles crossing the knee to support it during injury-inducing loading conditions such as externally applied knee abduction and rotation. Functional muscle synergies can provide new insight into the relationship between neuromuscular control and knee joint stability by directly associating biomechanical variables to muscle activation.

Forward lunge before and after anterior cruciate ligament reconstruction: Faster movement but unchanged knee joint biomechanics.

The forward lunge (FL) may be a promising movement to assess functional outcome after ACL reconstruction. Thus, we aimed to investigate the FL movement pattern before and after ACL reconstruction with a comparison to healthy controls to determine if differences were present. Twenty-eight ACL injured participants and 28 matched healthy controls were included. They performed FL movements while sagittal plane biomechanics of the knee and electromyography (EMG) of nine leg muscles was assessed. The ACL injured group was tested before and 10 months after surgery. The perceived knee function and activity level was assessed by questionnaires. The ACL injured group performed the FL significantly slower than the controls before surgery (mean difference: 0.41 s [95%CI: 0.04-0.79 s; p<0.05]) while they performed the FL as fast as the controls after surgery (~28% movement time reduction post-surgery). Perceived knee function and activity level improved significantly post-surgery. The knee joint flexion angle, extensor moment, power, angular velocity in the ACL injured group did not differ from pre to post-surgery. For the ACL injured group, the peak knee extensor moment observed both pre and post-surgery was significantly lower when compared to the controls. The EMG results showed minimal differences. In conclusion, at 10 months post-surgery, the FL was performed significantly faster and the movement time was comparable to that of the controls. While the perceived knee function and activity level improved post-surgery, the knee joint biomechanics were unchanged. This may reflect that knee joint function was not fully restored.

Predicting post-operative functional ability from pre-operative measures in ACL-injured individuals.

PURPOSE: This study aimed to quantify the relationship between objective and subjective measures of functional ability and determine if measures in the deficient (ACLd) state were correlated to, and capable of predicting a patient's objective and subjective measures in the reconstructed (ACLr) state. METHODS: Twenty ACL-injured participants completed hop and side cut movements prior to and 10 months post-reconstruction. Their subjective measures (Tegner, Lysholm, IKDC, KOOS, and KNEEs) were related to objective measures of functional ability (peak knee flexion, peak knee extensor moment, stiffness, knee joint center excursion (KJCE), and knee joint center boundary). Correlations were used to determine relationships between variables whereas regressions were used to identify ACLd score's predictive ability of an ACLr score. RESULTS: Relationships between objective and subjective measures were task and ACL status dependent with KJCE and stiffness most commonly being related to subjective scores. The greatest correlation was between knee stiffness and Tegner in the ACLr group during the side cut (r = 0.69). Peak knee flexion angle (adj. R2  = 0.4-0.66) was the best objective predictor between ACLd and ACLr states while KOOS-ADL had the strongest correlations (r = 0.70-0.77) and Tegner had the greatest predictive power (odds ratio: 1.46-1.86) between states in both tasks. CONCLUSION: Objective measures show a wide range of correlation to subjective measures with some being quite strong. Furthermore, objective measures in the ACLd state are more correlated and more often capable of predicting ACLr scores than the subjective measures of functional ability.

Experimental muscle pain of the vastus medialis reduces knee joint extensor torque and alters quadriceps muscle contributions as revealed through musculoskeletal modeling.

BACKGROUND: Voluntary activation deficit of the quadriceps muscle group is a common symptom in populations with knee joint injury. Musculoskeletal modeling and simulations can improve our understanding of pathological conditions; however, they are mathematically complex which can limit their clinical application. A practical subject-specific modeling framework is introduced to evaluate knee extensor inhibition and muscle force contributions to isometric knee joint torques in healthy adults with and without experimentally induced quadriceps muscle pain. METHODS: A randomized cross-over placebo controlled study design was used. Subject-specific maximum knee joint extension torque and quadriceps electromyographic data from 13 uninjured young adults were combined in a modeling framework to determine optimal muscle strength scaling parameters and ideal torque. Strength deficit ratios (experimental torque/ideal torque) and individual muscle contribution to experimental torque was computed before and after intramuscular hypertonic (pain inducing) and isotonic (sham) saline was injected to the vastus medialis. FINDINGS: Decreased experimental knee extension torque (-8%) and vastus medialis electromyography (-26%) amplitude pre- to post- hypertonic injection was observed. Correspondingly, significant decreases in the knee extensor strength deficit ratio (-18%) and percent contribution of vastus medialis to experimental torque (-24%) was observed pre- to post- hypertonic injection. No differences were observed with isotonic injections, confirming the validity of the model. INTERPRETATION: Our practical method to estimate strength ratios can be easily implemented within a musculoskeletal modeling framework to improve the validity of model estimates. This, in turn, can increase our understanding of the relationship between neuromuscular deficits and functional outcomes in patient populations.

Assessment of objective dynamic knee joint control in anterior cruciate ligament deficient and reconstructed individuals.

BACKGROUND: There is a lack of objective dynamic knee joint control measures that can be related to the status of the anterior cruciate ligament (ACL). The purpose of this study was to introduce two novel measures and apply a third to determine how dynamic knee joint control changes in relation to ACL status during dynamic movements. METHODS: Twenty patients (13 male) were tested pre- (ACLd) and 10-months post- (ACLr) ACL reconstructive surgery and matched to an uninjured participant (CON). Kinetic and kinematic data were synchronously recorded with a force platform and motion capture system. Three objective control measures including dynamic angular stiffness, knee joint center excursion (KJCE), and knee joint center boundary (KJCB) were assessed for each participant when completing the side cut and hop tasks. RESULTS: During the side cut, stiffness was found to be significantly lower in ACLd (0.06 ±â€¯0.01 Nm/kg/°) and ACLr (0.07 ±â€¯0.02 Nm/kg/°) compared to CON (0.08 ±â€¯0.02 Nm/kg/°), while there were no differences in stiffness during the hop. No significant differences were observed in the KJCE during the side cut, while KJCE was significantly greater (p = 0.006) during the hop in CON compared to the ACLd. There were no differences in KJCB. CONCLUSIONS: These high-functioning ACL injured in both ACLd and ACLr phases, aside from reduced stiffness, were able to complete both tasks with similar dynamic control as the CON. Although improvements in self-perceived control between ACLd and ACLr have been observed, this lack of improvement in objective control demonstrates a gap between a patient's self-efficacy and the level of control.

Anterior cruciate ligament reconstruction improves subjective ability but not neuromuscular biomechanics during dynamic tasks.

PURPOSE: The purpose of this study was to identify high-functioning anterior cruciate ligament-deficient patients and assess the effects of reconstruction on their self-reported functionality, muscle activations and biomechanical properties. METHODS: Twenty young and active patients participated pre- (11.5 ± 14.3 months post-injury) and again 10.5 ± 1.7 months post-reconstruction and were individually matched to 20 healthy controls. Participants completed hop and side cut movements while patient-related outcome measures, lower limb electromyography, kinetic, and whole body kinematic data were collected. One-dimensional statistical parametric mapping was used to test for group differences (healthy vs deficient; deficient vs reconstructed; reconstructed vs healthy). RESULTS: When comparing healthy to anterior cruciate ligament-deficient participants, all questionnaires indicated significant lower subjective function while the only substantial biomechanical difference between these participants was a decreased knee extensor moment in both the hop (peak difference: 0.63 Nm/kg, p < 0.001) and side cut (peak difference: 0.76 Nm/kg, p < 0.001). When comparing patients' pre- and post-reconstruction, no biomechanical differences were observed whereas only half of the questionnaires (Tegner, Lysholm, KNEES-ADL, KNEES-Slackness, KNEES-Looseness, KNEES-Sport Behaviour, IKDC, and KOOS-QoL) indicated higher function in the reconstructed state. When comparing the reconstructed patients to the healthy participants, all questionnaires were still significantly higher in the healthy controls. The reconstructed group also had a smaller flexion angle (peak difference: 14.5°, p = 0.007) and knee extensor moment (peak difference: 0.62 Nm/kg, p < 0.001) during the hop and a smaller knee extensor moment (peak difference: 0.90 Nm/kg, p < 0.001) during the side-cut task. CONCLUSION: At 10-months post-reconstruction, the current results indicate that in high-functioning anterior cruciate ligament-deficient patients, reconstruction had little impact on objective measures of functional ability during dynamic tasks although self-reported function was improved. LEVEL OF EVIDENCE: Therapeutic prospective cohort study, Level II.

Differences in EMG-moment relationships between ACL-injured and uninjured adults during a weight-bearing multidirectional force control task.

Anterior cruciate ligament injury (ACLi) reduces mechanical knee joint stability. Differences in muscle activation patterns are commonly identified between ACLi individuals and uninjured controls (CON); however, how and which of these differences are adaptations to protect the knee or adversely increase risk of joint instability remain unclear. Since the neuromuscular system integrates activity of all muscles crossing the knee to create a moment-of-force that opposes an external load, this study sought to quantify differences in individual muscle electromyography (EMG)-moment relationships between ACLi and CON. Participants isometrically modulated ground reaction forces during a standing force matching protocol to elicit combinations of sagittal, frontal and transverse plane moments. Partial least squares regressions determined which internal joint moment(s) predicted activation of 10 leg muscles for each group. Compared to CON, ACLi demonstrated greater contribution of rectus femoris to knee extension, semitendinosus and gastrocnemii to knee flexion, and lateral gastrocnemii to knee external rotation moments. ACLi also showed lower contributions of biceps femoris to knee flexion, medial gastrocnemius to internal rotation, and varied hip muscle contributions to frontal plane hip moments. Between group differences in EMG-moment relationships during static conditions suggest neuromuscular contributions to sagittal plane stability increases after ACL injury, while knee stability during knee abduction and external rotation is reduced. Clinical Significance: Clinical assessments of ACLi should account for deficits in frontal and rotational plane stability by including tasks that elicit such loads. Improving hamstring muscle balance, hip abductor and gastrocnemius function may benefit ACLi rehabilitation interventions and should be studied further. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

A hierarchy in functional muscle roles at the knee is influenced by sex and anterior cruciate ligament deficiency.

BACKGROUND: Sex-related neuromuscular differences have been linked to greater risk of anterior cruciate ligament injuries in females. Despite this, it remains unclear if sex-related differences are present after injury. This study sought to determine if sex differences are present in the functional roles of knee joint muscles in an anterior cruciate ligament deficient population. METHODS: An isometric, weight-bearing, force-generation protocol required injured and healthy males and females to modulate ground reaction forces. Electromyography was used to classify the functional role of 10 lower limb muscles in their contribution to knee joint stability during various loading directions. These roles were compared between the four groups at 12 loading directions using a directional analysis. FINDINGS: Functional muscle roles were different between groups, except for injured males and healthy females. Healthy males had either joint actuators or specific joint stabilisers, but no general stabilisers; the vastus medialis and lateralis of injured males and healthy females were classified as general stabilisers while injured females added the gluteus medialis and medial gastrocnemius as general stabilisers. INTERPRETATION: A population-based hierarchy in functional muscle roles was discovered. Healthy males demonstrated the most specific muscle roles, which can be viewed as more adaptive to variable loading conditions. The more generalised stabilisation strategies seen in injured males and females would alter joint loading which may be detrimental to the knee joint health over time. In summary, (1) these injuries alter muscle roles; (2) these alterations are sex-specific; (3) rehabilitation might be optimised if sex-differences are considered.

Neuromuscular adaptations in older males and females with knee osteoarthritis during weight-bearing force control.

BACKGROUND: Females exhibit significantly greater incidence, prevalence, and severity of osteoarthritis (OA) compared to males. Despite known biological, morphological, and functional differences between males and females, there has been little sex-related investigation into sex-specific biomechanical and neuromuscular responses to OA. OBJECTIVE: To identify sex-related differences in OA-affected adults and within-sex differences between healthy and OA-affected adults' muscular activation patterns during lower limb loading. METHODS: Thirty adults with OA and 36 controls completed a standing ground reaction force (GRF) matching protocol requiring participants to expose equal body weight to each leg and modulate horizontal GRFs while maintaining constant joint positions. Electromyography was plotted as a function of GRF direction to depict muscle activation patterns. Muscles were classified as a general joint stabilizer, specific joint stabilizer or moment actuator by quantifying activation patterns with a test of asymmetry, specificity index and mean direction of activity. Lower limb kinematics and kinetics were also recorded. RESULTS: In general, muscle roles as it relates to joint stability did not differ between groups. Compared to controls, both males and females with OA demonstrated greater rectus femoris activity and reduced knee rotation moments. Females with OA had significantly greater biceps femoris and gastrocnemius activity during respective lateral, and anterior-medial loading directions compared to males with OA. CONCLUSIONS: We identified fundamental differences in muscular stabilization strategies in older adults with OA as well as sex-related changes in neuromuscular function that may influence joint loading conditions and provide insight into the greater incidence of knee OA in females.

Predicting the Functional Roles of Knee Joint Muscles from Internal Joint Moments.

INTRODUCTION: Knee muscles are commonly labeled as flexors or extensors and aptly stabilize the knee against sagittal plane loads. However, how these muscles stabilize the knee against adduction-abduction and rotational loads remains unclear. Our study sought 1) to classify muscle roles as they relate to joint stability by quantifying the relationship between individual muscle activation patterns and internal net joint moments in all three loading planes and 2) to determine whether these roles change with increasing force levels. METHODS: A standing isometric force matching protocol required subjects to modulate ground reaction forces to elicit various combinations and magnitudes of sagittal, frontal, and transverse internal joint moments. Surface EMG measured activities of 10 lower limb muscles. Partial least squares regressions determined which internal moment(s) were significantly related to the activation of individual muscles. RESULTS: Rectus femoris and tensor fasciae latae were classified as moment actuators for knee extension and hip flexion. Hamstrings were classified as moment actuators for hip extension and knee flexion. Gastrocnemius and hamstring muscles were classified as specific joint stabilizers for knee rotation. Vastii were classified as general joint stabilizers because activation was independent of moment generation. Muscle roles did not change with increasing effort levels. CONCLUSIONS: Our findings indicate muscle activation is not dependent on anatomical orientation but perhaps on its role in maintaining knee joint stability in the frontal and transverse loading planes. This is useful for delineating the roles of biarticular knee joint muscles and could have implications in robotics, musculoskeletal modeling, sports sciences, and rehabilitation.

An approach for improving repeatability and reliability of non-negative matrix factorization for muscle synergy analysis.

The aim of this study was to evaluate non-negative matrix factorization (NMF) and concatenated NMF (CNMF) to analyze and reliably extract muscle synergies. NMF and CNMF were used to extract knee joint muscle synergies from surface EMGs collected during a weight bearing, force matching task. Repeatability and between subject similarity were evaluated for each method using intra-class correlation coefficients (ICCs). High repeatability was found for CNMF (>0.99; 0.99-1.0) compared to NMF (>0.26; range 0.26-0.98). Reasonable consistency across subjects was improved using the CNMF over the NMF approach. CNMF was found to be a more reliable approach than NMF and suitable for between subject comparison of muscle synergies.