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Open Access Publications from the University of California

Scholarly Works (78 results)

  • Article
  • Peer Reviewed
UC San Francisco Previously Published Works (2016)
Running biomechanics play an important role in the development of injuries. Performing a running biomechanics analysis on injured runners can help to develop treatment strategies. This article provides a framework for a systematic video-based running biomechanics analysis plan based on the current evidence on running injuries, using 2-dimensional (2D) video and readily available tools. Fourteen measurements are proposed in this analysis plan from lateral and posterior video. Identifying simple 2D surrogates for 3D biomechanic variables of interest allows for widespread translation of best practices, and have the best opportunity to impact the highly prevalent problem of the injured runner.
    Cover page: An Evidence-Based Videotaped Running Biomechanics Analysis
    • Thesis
    • Peer Reviewed
    UC San Francisco Electronic Theses and Dissertations (2013)

    The Effects of Recurrent Lateral Ankle Sprains and Postural Control on Biomechanics during Functional Movement

    Timothy J. Gilleran

    Study Design: Cross ±sectional

    Objectives: Study 1: identify relationships between physical and functional impairments and the dynamic postural stability index (DPSI) scores in participants with and without recurrent lateral ankle sprains (RLAS). Study 2: To examine whether participants with recurrent lateral ankle sprain and postural instability (RLAS±PI) are more likely than participants without RLAS±PI to have concurrent evidence of changes in joint biomechanics of the ankle, knee, hip, pelvis and trunk during jump landings.

    Background: Recurrent lateral ankle sprains are common injuries which may lead to changes in postural control and joint biomechanics. The association between DPSI and clinical impairments is currently unknown. Establishing a relationship between a dynamic measure of postural stability and clinical impairments will assist clinicians in prioritizing their examination. The contributions of RLAS and postural instability to lower extremity and trunk biomechanics during functional movements are currently unclear. Understanding the biomechanics of functional movements in subjects with RLAS±PI will inform clinicians and researchers about selected postural control strategies.

    Methods: In study 1, examinations of DPSI scores and clinical impairments were performed on 23 participants (5 male, 18 female, age: 26.8 ± 4.2) with RLAS and 14 participants without RLAS (8 male, 6 female, age: 27.1 ± 3.5). Jump landings were examined using data acquired by a force platform (1000 Hz). Associations of DPS and clinical measures were evaluated using bivariate correlations (p<0.05). Group mean differences of continuous clinical outcome measures were examined using MANCOVA; and categorical data were evaluated with chi square test (p<0.05). In study 2, the landing phase (initial contact to one second) of a jump onto a single limb was examined with a force platform (1000 Hz) and a 10 camera motion capture system (250 Hz) with a full body marker set. Participants included 9 with RLAS-PI (4 female, 5 male, age: 28.1 ± 4.0) and 12 controls (6 female, 5 male, age: 26.2 ± 2.7). Group mean differences in clinical measures, joint kinematics and kinetics were examined using independent t-tests (p<0.05).

    Results: Study 1 identified weak and non-significant correlations between all DPSI scores and clinical tests. Significant group differences in questionnaires, joint stability measures and the Y Excursion Balance Test were identified, but no differences in strength, range of motion, side hop performance, and directional or composite stability indices were identified. Study 2 identified significant group differences in ankle, knee, hip, pelvis, and trunk biomechanics between RLAS±PI and control participants. Compared to controls, participants with RLAS±PI had a significant decrease in dorsiflexion excursion angles (p = 0.034), and increase in knee joint power (p = 0.039) and peak trunk flexion angles (p = 0.038).

    Conclusion: The selected physical and functional impairment measures were not related to this measure of dynamic postural control. RLAS participants perceive significant deficits in their functional ankle stability and disability, but quantitative measures of their functional performance and dynamic postural control were unable to identify group differences. In study 2, the RLAS±PI group utilized different movement strategies to perform the jump landing task successfully. Reduced ankle joint excursions may reflect a "protective stiffening" strategy by the RLAS±PI group, but at a cost to an increasing the vertical rate of loading. As a result of this strategy, we observed proximal movement strategies with the use of increased hip and trunk movement to regain balance after the jump landing. Increases in rate of loading have been attributed to overuse injuries in running and jumping sports.

    Key words: recurrent lateral ankle sprain, postural control, biomechanics

      Cover page: The Effects of Recurrent Lateral Ankle Sprains and Postural Control on Biomechanics during Functional Movement
      • Article
      • Peer Reviewed
      UC San Francisco Previously Published Works (2023)
      BACKGROUND: Although T1ρ and T2 have emerged as early indicators for hip osteoarthritis (OA), there is little information regarding longitudinal changes across the cartilage in the early stages of this disease. PURPOSE: To characterize the variability in 2-year hip cartilage T1ρ and T2 changes and investigate associations between these patterns of change and common indicators of hip OA. STUDY TYPE: Prospective. POPULATION: A total of 25 women (age: 51.9 ± 16.3 years old; BMI: 22.6 ± 2.0 kg/m2 ) and 17 men (age: 55.8 ± 14.9 years old; body mass index (BMI): 24.4 ± 3.8 kg/m2 ) who were healthy or with early-to-moderate hip OA. FIELD STRENGTH/SEQUENCE: A 3 T MRI (GE), 3D combined T1ρ /T2 magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots. ASSESSMENT: Principal component (PC) analysis of Z-score difference maps of 2-year changes in hip cartilage T1ρ and T2 relaxation times, participant hip disability and osteoarthritis outcome scores (HOOS) and functional tests at 2-year follow-up. STATISTICAL TESTS: Shapiro-Wilk test, unpaired t-tests, Kruskal Wallis tests, Pearson or Spearman (ρ) correlations. Significance was set at P < 0.05. RESULTS: Women (-6.40 ± 14.48) had significantly lower T1ρ PC1 scores than men (10.05 ± 26.15). T1ρ PC4 was significantly correlated with HOOSsport , HOOSsymptoms , HOOSpain , HOOSadl , and HOOSqol at 2-year follow-up (ρ: [0.36, 0.50]). T1ρ PC2 and PC4 were significantly correlated with 30-second chair test (ρ = -0.39 and ρ = 0.24, respectively) and side plank (ρ = -0.32 and ρ = 0.21). T1ρ and T2 PC2 were significantly correlated with 40 m walk test (ρ = 0.34 and ρ = 0.31) and 30-second chair rise test (ρ = -0.39 and ρ = -0.32). DATA CONCLUSION: Men exhibited accelerated T1ρ increases across the femoral cartilage compared to women, suggesting sex should be considered when evaluating early hip OA. Participants with poorer HOOS and function exhibited greater T1ρ and T2 increases in superior and anterior femoral cartilage and greater T1ρ increases in the anterior femoral cartilage. These patterns of short-term relaxometry increases could indicate hip OA progression. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 3.
        Cover page: Local Patterns in 2-Year T1ρ and T2 Changes of Hip Cartilage Are Related to Sex and Functional Data: A Prospective Evaluation on Hip Osteoarthritis Participants.
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2021)

        Study design

        Case-control.

        Objective

        To examine whether patients with patellar tendinopathy (PT) display greater patellar mobility and different lower body kinematics than patients without PT.

        Background

        PT is a common overuse condition of the patellar tendon that can cause pain and impair function. Subjects with overuse knee problems display different hip and knee functional mechanics, specifically valgus collapse. Patellar hypermobility has not been specifically studied as a possible risk factor for PT.

        Methods

        11 patients with PT and 11 controls without PT, age 18 to 40, were studied. Using a patellofemoral arthrometer (PFA), maximal lateral and medial patellar displacement was measured. 3-D motion analysis was performed to determine lower extremity joint motions during single-leg step down and drop vertical jump tests.

        Results

        Patients with PT had significantly increased lateral patellar mobility compared to controls (12.21 ± 3.33 mm vs. 9.19 ± 1.92 mm, P = .017). PT patients showed significantly greater peak hip adduction with both drop vertical jump (2.7° ± 6.3° vs. -5.6° ± 4.2°; P = .003) and step down (17.0° ± 3.8° vs. 12.5° ± 4.4°, P = .024). PT patients demonstrated increased peak ankle external rotation with drop vertical jump (-21.1° ± 5.9° vs. -14.8° ± 5.5°, P = .023) and step down (-15.6° ± 5.5° vs. -9.0° ± 6.0°, P = .017).

        Conclusions

        Patients with PT exhibit increased lateral patellar mobility, hip adduction, and ankle external rotation. The effects of increased patellar mobility deserve further study in the development, management, and prevention of PT.
          Cover page: Patellar mobility and lower limb kinematics during functional activities in individuals with and without patellar tendinopathy
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2017)

          Purpose

          To study the local distribution of hip cartilage T1ρ and T2 relaxation times and their association with changes in patient reported outcome measures (PROMs) using a fully automatic, local, and unbiased method in subjects with and without hip osteoarthritis (OA).

          Materials and methods

          The 3 Tesla MRI studies of the hip were obtained for 37 healthy controls and 16 subjects with radiographic hip OA. The imaging protocol included a three-dimensional (3D) SPGR sequence and a combined 3D T1ρ and T2 sequence. Quantitative cartilage analysis was compared between a traditional region of interest (ROI)-based method and a fully automatic voxel-based relaxometry (VBR) method. Additionally, VBR was used to assess local T1ρ and T2 differences between subjects with and without OA, and to evaluate the association between T1ρ and T2 and 18-month changes PROMs.

          Results

          Results for the two methods were consistent in the acetabular (R = 0.79; coefficients of variation [CV] = 2.9%) and femoral cartilage (R = 0.90; CV = 2.6%). VBR revealed local patterns of T1ρ and T2 elevation in OA subjects, particularly in the posterosuperior acetabular cartilage (T1ρ : P = 0.02; T2 : P = 0.038). Overall, higher T1ρ and T2 values at baseline, particularly in the anterosuperior acetabular cartilage (T1ρ : Rho = -0.42; P = 0.002; T2 : Rho = -0.44; P = 0.002), were associated with worsening PROMS at 18-month follow-up.

          Conclusion

          VBR is an accurate and robust method for quantitative MRI analysis in hip cartilage. VBR showed the capability to detect local variations in T1ρ and T2 values in subjects with and without osteoarthritis, and voxel based correlations demonstrated a regional dependence between baseline T1ρ and T2 values and changes in PROMs.

          Level of evidence

          1 J. MAGN. RESON. IMAGING 2017;45:1523-1533.
            Cover page: Longitudinal study using voxel‐based relaxometry: Association between cartilage T1ρ and T2 and patient reported outcome changes in hip osteoarthritis
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2015)

            Objective

            To investigate the changes in running biomechanics after training in form-focused running using ChiRunning versus not-form focused training and self-directed training in untrained individuals.

            Design

            Pilot study-randomized controlled trial.

            Setting

            Research institution with tertiary care medical center.

            Participants

            Seventeen subjects (9 men, 8 women) with prehypertension.

            Methods

            Twenty-two participants were randomized to 3 study arms but 17 completed the study. The study arms were: (1) group-based Form-Focused running using ChiRunning (enrolled, n = 10; completed, n = 7); (2) group-based conventional running (enrolled, n = 6; completed, n = 4); and (3) self-directed training with educational materials (enrolled, n = 6; completed, n = 6). The training schedule was prescribed for 8 weeks with 4 weeks of follow-up. All subjects completed overground running motion analyses before and after training. ClinicalTrials.gov identifier for this study is NCT0158718.

            Outcomes

            Ankle, knee, hip joint peak moments, and powers; average vertical loading rate (AVLR); impact peak; cadence; stride length; strike index; and stride reach. Paired t tests were used to compare differences within groups over time.

            Results

            Form-focused group reduced their Stride Reach (P = .047) after the training but not the other groups. Form-focused group showed a close to significant reduction in knee adduction moment (P = .051) and a reduction in the peak ankle eversion moment (P = .027). Self-directed group showed an increase in the running speed (P = .056) and increases in ankle and knee joint powers and moments.

            Conclusions

            There are differences in the changes in running biomechanics between individuals trained in running form that emphasizes mid-foot strike, greater cadence, and shorter stride compared with those not trained in the these techniques. These differences may be associated with reduced lower extremity stress in individuals trained in this running form, but more studies are needed to confirm these findings in larger samples.
              Cover page: Effects of Form‐Focused Training on Running Biomechanics: A Pilot Randomized Trial in Untrained Individuals
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2015)

              Study design

              Controlled laboratory study, longitudinal design.

              Objective

              To examine whether baseline knee flexion moment or impulse during walking is associated with the progression of osteoarthritis (OA) with magnetic resonance imaging of the patellofemoral joint (PFJ) at 1 year.

              Background

              Patellofemoral joint OA is highly prevalent and a major source of pain and dysfunction. The biomechanical factors associated with the progression of PFJ OA remain unclear.

              Methods

              Three-dimensional gait analyses were performed at baseline. Magnetic resonance imaging of the knee (high-resolution, 3-D, fast spin-echo sequence) was used to identify PFJ cartilage and bone marrow edema-like lesions at baseline and a 1-year follow-up. The severity of PFJ OA progression was defined using the modified Whole-Organ Magnetic Resonance Imaging Score when new or increased cartilage or bone marrow edema-like lesions were observed at 1 year. Peak external knee flexion moment and flexion moment impulse during the first and second halves of the stance phase of gait were compared between progressors and nonprogressors, and used to predict progression after adjusting for age, sex, body mass index, and presence of baseline PFJ OA.

              Results

              Sixty-one participants with no knee OA or isolated PFJ OA were included. Patellofemoral joint OA progressors (n = 10) demonstrated significantly higher peak knee flexion moment (P = .01) and flexion moment impulse (P = .04) during the second half of stance at baseline compared to nonprogressors. Logistic regression showed that higher peak knee flexion moment during the second half of the stance phase was significantly associated with progression at 1 year (adjusted odds ratio = 3.3, P = .01).

              Conclusion

              Peak knee flexion moment and flexion moment impulse during the second half of stance are related to the progression of PFJ OA and may need to be considered when treating individuals who are at risk of or who have PFJ OA.
                Cover page: Higher Knee Flexion Moment During the Second Half of the Stance Phase of Gait Is Associated With the Progression of Osteoarthritis of the Patellofemoral Joint on Magnetic Resonance Imaging.
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2013)

                Background

                The purpose of this investigation is to evaluate the T(1ρ) relaxation times of articular cartilage surrounding focal defects in the tibiofemoral joint.

                Methods

                Quantitative cartilage assessment was performed using 3T MRI with T(1ρ) mapping in 19 healthy individuals and 44 OA patients. Sagittal T2-weighted fast spin echo (FSE) images were acquired for lesion assessment. Differences were determined using analysis of variance (ANOVA).

                Results

                Cartilage lesions were found in 37% of controls, and 93% of OA patients. Meniscal tears were found in 16% of controls and 57% of OA patients. We observed no difference in T(1ρ) relaxation times when comparing cartilage immediately surrounding a focal defect, and the remaining cartilage within that compartment. The medial femoral condyle (MFC) had the highest incidence of cartilage defects. MFC and medial meniscus posterior horn T(1ρ) were higher in subjects having multiple focal lesions (p = 0.048, pb 0.001 respectively) and extensive full thickness lesions (p = 0.009, pb 0.001 respectively) compared to subjects with no MFC defects. Significant elevations in T(1ρ) of the adjacent compartment (medial tibia) and medial meniscus were observed in subjects with MFC lesions.

                Conclusion

                Increased relaxation times in the involved compartment as well as the adjacent compartment and associated meniscus underscore the interdependence of these structures at bearing load. However, no differences in cartilage composition immediately surrounding a defect were noted. Finally, an association was observed between cartilage defects and meniscal damage in advanced disease.

                Clinical relevance

                Cartilage defects were not associated with degeneration in the immediately adjacent cartilage.
                  Cover page: T1rho MRI relaxation in knee OA subjects with varying sizes of cartilage lesions
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2017)

                  Background

                  The factors that contribute to the abnormal knee kinematics after anterior cruciate ligament (ACL) injury and ACL reconstruction remain unclear. Bone shape has been implicated in the development of hip and knee osteoarthritis, although there is little knowledge about the effects of bone shape on knee kinematics after ACL injury and after ACL reconstruction. QUESTIONS/QUESTIONS: (1) What is the relationship between bony morphology with alterations in knee kinematics after ACL injury? (2) Are baseline bone shape features related to abnormal knee kinematics at 12 months after ACL reconstruction?

                  Methods

                  Thirty-eight patients (29 ± 8 years, 21 men) were prospectively followed after acute ACL injury and before ligamentous reconstruction. Patients were excluded if there was a history of prior knee ligamentous injury, a history of inflammatory arthritis, associated meniscal tears that would require repair, or any prior knee surgery on either the injured or contralateral side. In total, 54 patients were recruited with 42 (78%) patients completing 1-year followup and four patients excluded as a result of incomplete or unusable imaging data. MR images were obtained for the bilateral knees at two time points 1 year apart for both the injured (after injury but before reconstruction and 1 year after reconstruction) and contralateral uninjured knees. Kinematic MRI was performed with the knee loaded with 25% of total body weight, and static images were obtained in full extension and in 30° of flexion. The side-to-side difference (SSD) between tibial position in the extended and flexed positions was determined for each patient. Twenty shape features, referred to as modes, for the tibia and femur each were extracted independently from presurgery scans with the principal component analysis-based statistical shape modeling algorithm. Spearman rank correlations were used to evaluate the relationship between the SSD in tibial position and bone shape features with significance defined as p < 0.05. Each of the shape features (referred to as the bone and mode number such as Femur 18 for the 18th unique femoral bone shape) associated with differences in tibial position was then investigated by modeling the mean shape ± 3 SDs.

                  Results

                  Two of the 20 specific femur bone shape features (Femur 10, Femur 18) and two of the 20 specific tibial bone shape features (Tibia 19, Tibia 20) were associated with an increasingly anterior SSD in the tibial position for the patients with ACL injury before surgical treatment. The shape features described by these modes include the superoinferior height of the medial femoral condyle (Femur 18; ρ = 0.33, p = 0.040); the length of the anterior aspect of the lateral tibial plateau (Tibia 20; ρ = -0.35, p = 0.034); the sphericity of the medial femoral condyle (Femur 10; ρ = -0.52, p < 0.001); and tibial slope (Tibia 19; ρ = 0.34; p = 0.036). One year after surgical treatment, there were two of 20 femoral shape features that were associated with SSD in the tibial position in extension (Femur 10, Femur 18), one of 20 femoral shape features associated with SSD in the tibial position in flexion (Femur 10), and three of 20 tibial shape features associated with SSD in the tibial position in flexion (Tibia 2, Tibia 4, Tibia 19). The shape features described by these modes include the sphericity of the medial femoral condyle (Femur 10; ρ = -0.38, p = 0.020); the superoinferior height of the medial femoral condyle (Femur 18; ρ = 0.34, p = 0.035); the height of the medial tibial plateau (Tibia 2; ρ = -0.32, p = 0.048); the AP length of the lateral tibial plateau (Tibia 4; ρ = -0.37, p = 0.021); and tibial slope (Tibia 19; ρ = 0.34, p = 0.038).

                  Conclusions

                  We have observed multiple bone shape features in the tibia and the femur that may be associated with abnormal knee kinematics after ACL injury and ACL reconstruction. Future directions of research will include the influence of bony morphology on clinical symptoms of instability in patients with and without ACL reconstruction and the long-term evaluation of these shape factors to better determine specific contributions to posttraumatic arthritis and graft failure.

                  Level of evidence

                  Level II, therapeutic study.
                    Cover page: Variations in Knee Kinematics After ACL Injury and After Reconstruction Are Correlated With Bone Shape Differences.
                    • Article
                    • Peer Reviewed
                    UC San Francisco Previously Published Works (2019)

                    Background

                    Mapping of T1ρ relaxation time is a quantitative magnetic resonance (MR) method and is frequently used for analyzing microstructural and compositional changes in cartilage tissues. However, there is still a lack of study investigating the link between T1ρ relaxation time and a feasible constitutive relation of cartilage which can be used to model complicated mechanical behaviors of cartilage accurately and properly.

                    Methods

                    Three-dimensional finite element (FE) models of ten in vitro human tibial cartilage samples were reconstructed such that each element was assigned by material-level parameters, which were determined by a corresponding T1ρ value from MR maps. A T1ρ-based fibril-reinforced poroviscoelastic (FRPE) constitutive relation for human cartilage was developed through an inverse FE optimization technique between the experimental and simulated indentations.

                    Results

                    A two-parameter exponential relationship was obtained between the T1ρ and the volume fraction of the hydrated solid matrix in the T1ρ-based FRPE constitutive relation. Compared with the common FRPE constitutive relation (i.e., without T1ρ), the T1ρ-based FRPE constitutive relation indicated similar indentation depth results but revealed some different local changes of the stress distribution in cartilages.

                    Conclusions

                    Our results suggested that the T1ρ-based FRPE constitutive relation may improve the detection of changes in the heterogeneous, anisotropic, and nonlinear mechanical properties of human cartilage tissues associated with joint pathologies such as osteoarthritis (OA). Incorporating T1ρ relaxation time will provide a more precise assessment of human cartilage based on the individual in vivo MR quantification.
                      Cover page: T 1ρ -based fibril-reinforced poroviscoelastic constitutive relation of human articular cartilage using inverse finite element technology
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