Browsing by Author "Ito, Naoaki"
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Item Challenging the assumption of uniformity in patellar tendon structure: Regional patellar tendon morphology and mechanical properties in vivo(Journal of Orthopaedic Research, 2023-04-08) Ito, Naoaki; Scattone Silva, Rodrigo; Sigurðsson, Haraldur B.; Cortes, Daniel H.; Silbernagel, Karin GrävarePatellar tendons are assumed to be uniform in morphology and mechanical properties despite a higher prevalence of tendinopathies observed in the medial region. The purpose of this study was to compare the thickness, length, viscosity, and shear modulus of the medial, central, and lateral regions of healthy patellar tendons of young males and females in vivo. B-mode ultrasound and continuous shear wave elastography were performed on 35 patellar tendons (17 females, 18 males) over three regions of interest. A linear mixed-effects model (α = 0.05) was used to determine differences between the three regions and sexes followed by pairwise comparisons for significant findings. The lateral region (mean [95% confidence interval] = 0.34 [0.31–0.37] cm) was thinner compared with the medial (0.41 [0.39–0.44] cm, p < 0.001), and central (0.41 [0.39–0.44] cm, p < 0.001) regions regardless of sex. Viscosity was lower in the lateral (19.8 [16.9–22.7] Pa-s) versus medial region (27.4 [24.7–30.2] Pa-s, p = 0.001). Length had a region-by-sex interaction (p = 0.003) characterized by a longer lateral (4.83 [4.54–5.13] cm) versus medial (4.42 [4.12–4.72] cm) region in males (p < 0.001), but not females (p = 0.992). Shear modulus was uniform between regions and sexes. The thinner, and less viscous lateral patellar tendon may reflect the lower load the tendon experiences explaining the differences in regional prevalence of developing tendon pathology. Statement of Clinical Significance: Healthy patellar tendons are not uniform in morphology or mechanical properties. Considering regional tendon properties may help guide targeted interventions for patellar tendon pathologies.Item Hop Distance Symmetry Moderately Reflects Knee Biomechanics Symmetry During Landing But Not For Controlled Propulsions(International Journal of Sports Physical Therapy, 2024-08-01) Di Paolo, Stefano; Ito, Naoaki; Seymore, Kayla D.; Sigurðsson, Haraldur B.; Bragonzoni, Laura; Zaffagnini, Stefano; Snyder-Mackler, Lynn; Gravare Silbernagel, KarinBackground Landing with poor knee sagittal plane biomechanics has been identified as a risk factor for Anterior Cruciate Ligament (ACL) injury. However, it is unclear if the horizontal hop test battery reflects knee function and biomechanics. Hypothesis/Purpose To investigate the correlation between clinical limb symmetry index (LSI) and landing and propulsion knee biomechanics during the hop test battery using markerless motion capture. Study Design Cross-sectional biomechanics laboratory study Methods Forty-two participants with and without knee surgery (age 28.0 ± 8.0 years) performed the hop test battery which consisted of a single hop for distance, crossover hop, triple hop, and 6-m timed hop in the order listed. Eight high speed cameras were used to collect simultaneous 3D motion data and Theia 3D (Theia Markerless Inc.) was used to generate 3D body model files. Lower limb joint kinematics were calculated in Visual3D. Correlation (Spearman’s ρ) was computed between clinical LSI and symmetry in peak and initial contact (IC) knee flexion angle during propulsion and landing phases of each movement. Results In the single hop, clinical LSI showed positive correlation with kinematic LSI at peak landing (ρ= 0.39, p=0.011), but no correlation at peak propulsion (ρ= -0.03, p=0.851). In the crossover hop, non-significant correlations were found in both propulsion and landing. In the triple hop, positive correlation was found at peak propulsion (ρ= 0.38, p=0.027), peak landing (ρ= 0.48 – 0.66, p<0.001), and last landing IC (ρ= 0.45, p=0.009). In the timed hop, peak propulsion showed positive correlation (ρ= 0.51, p=0.003). Conclusions Single hop and triple hop distance symmetry reflected landing biomechanical symmetry better than propulsion symmetry. Poor scores on the hop test battery reflect asymmetrical knee landing biomechanics, emphasizing the importance of continuing to use the hop test battery as part of clinical decision making. Level of Evidence 3bItem Location of Measurement Matters: Unveiling Regional Dynamics and Sex Differences in Patellar Tendon Strain In Vivo(Scandinavian Journal of Medicine & Science in Sports, 2024-08-08) Ito, Naoaki; Scattone Silva, Rodrigo; Grävare Silbernagel, KarinPatellar tendinopathy is more prevalent in males versus female athletes and commonly presents in the medial region of the tendon. Separate measures of patellar tendon strain in the medial, central, and lateral regions of the tendon, however, have not been quantified. The purpose was to investigate the differences in tendon strain between the medial, lateral, and central regions of the patellar tendon in healthy men and women. Strain in the medial and lateral regions of the patellar tendon in healthy participants (10 males, 10 females) was evaluated using ultrasound during isometric quadriceps contractions at 20%, 40%, 60%, 80%, and 100% of maximum voluntary contraction (MVIC) in 60° and 90° of knee flexion. Central strain was also measured at 60% MVIC in 90° of knee flexion. Mixed models were used to determine strain between tendon regions and sex at 60% MVIC in 90° of knee flexion. Sequential modeling was used to fit region, sex, %MVIC, and angle to predict strain. The central region had less strain compared with both medial and lateral regions. The lateral region had higher strain compared with the medial region regardless of sex. Females had higher strain compared with males, regardless of region. Knee position did not influence tendon strain. Patellar tendon strain differs by region and sex. The varying prevalence between sex and in location of patellar tendinopathy may in part be explained by the unbalanced strains. Differential assessment of regional patellar tendon strain may be of importance for understanding injury risk and recovery with exercise.Item Markerless motion capture: What clinician-scientists need to know right now(Journal of Science and Medicine in Sport Plus, 2022-11-14) Ito, Naoaki; Sigurðsson, Haraldur B.; Seymore, Kayla D.; Arhos, Elanna K.; Buchanan, Thomas S.; Snyder-Mackler, Lynn; Grävare Silbernagel, KarinMarkerless motion capture (mocap) could be the future of motion analysis. The purpose of this report was to describe our team of clinicians and scientists’ exploration of markerless mocap (Theia 3D) and share data for others to explore (link: https://osf.io/6vh7z/?view_only=c0e00984e94a48f28c8d987a2127339d). Simultaneous mocap was performed using markerless and marker-based systems for walking, squatting, and forward hopping. Segment lengths were more variable between trials using markerless mocap compared to marker-based mocap. Sagittal plane angles were most comparable between systems at the knee joint followed by the ankle and hip. Frontal and transverse plane angles were not comparable between systems. The data collection experience using markerless mocap was simpler, faster, and user friendly. The ease of collection was in part offset by the added data transfer and processing times, and the lack of troubleshooting flexibility. If used selectively with proper understanding of limitations, markerless mocap can be exciting technology to advance the field of motion analysis.Item Reliability of Continuous Shear Wave Elastography in the Pathological Patellar Tendon(Journal of Ultrasound in Medicine, 2022-10-27) Ito, Naoaki; Sigurðsson, Haraldur B.; Pohlig, Ryan T.; Cortes, Daniel H.; Grävare Silbernagel, Karin; Sprague, Andrew L.Objectives Patellar tendon injuries occur via various mechanisms such as overuse, or due to surgical graft harvest for anterior cruciate ligament reconstruction (ACLR). Quantified patellar tendon stiffness after injury may help guide clinical care. Continuous shear wave elastography (cSWE) allows for the assessment of viscosity and shear modulus in tendons. The reliability of the measure, however, has not been established in the patellar tendon. The purpose of this study was to investigate the interrater reliability, intrarater reliability, and between-day stability of cSWE in both healthy and pathological patellar tendons. Methods Participants with patellar tendinopathy (n = 13), history of ACLR using bone-patellar tendon-bone autograft (n = 9), and with no history of patellar tendon injury (n = 13) were recruited. cSWE was performed 4 times by multiple raters over 2 days. Intraclass correlations (ICC) and minimum detectable change (MDC95%) were calculated. Results Good to excellent between-day stability were found for viscosity (ICC = 0.905, MDC95% = 8.3 Pa seconds) and shear modulus (ICC = 0.805, MDC95% = 27.4 kPa). The interrater reliability measures, however, were not as reliable (ICC = 0.591 and 0.532). Conclusions cSWE is a reliable assessment tool for quantifying patellar tendon viscoelastic properties over time. It is recommended, however, that a single rater performs the measure as the interrater reliability was less than ideal.Item The role of the graft site tendon after bone-patellar tendon-bone autograft harvest in the recovery after anterior cruciate ligament reconstruction(University of Delaware, 2023) Ito, NaoakiPrevalence of anterior cruciate ligament (ACL) injury and subsequent reconstruction surgery (ACLR) exceeds 200,000 cases a year, impeding young athletes’ participation in sports and long-term knee joint health. The bone-patellar tendon-bone (BPTB) autograft is one of the most common graft types used in the United States and is harvested from the central third of the patellar tendon. Harvesting a graft from the already injured knee, however, comes with a cost. Quadriceps weakness, a key factor to address in rehabilitation after ACL injury, is more profound when compared to other graft types that do not involve the extensor mechanism. Anterior knee pain, especially with kneeling, is also more prevalent due to the additional surgical insult. Such graft site morbidities early after ACLR may exacerbate the already elevated rates of post-traumatic knee osteoarthritis (OA) observed after ACL injury. Recovery of the graft site patellar tendon’s morphology and mechanical properties may in part explain graft site morbidities. The course of recovery of the patellar tendon, its relationship with clinical outcomes, and its influence on movements such as walking gait have been seldom studied. Objectives of this project were to investigate the changes in patellar tendon structure after BPTB graft harvest, assess the influence of tendon structure on clinical outcomes after ACLR, and to investigate whether neuromuscular deficits of the quadriceps are reflected during gait and persist from BPTB graft harvest. We aimed to fulfill our objectives through the following specific aims. ☐ Aim 1: Establish the healing trajectory of the patellar tendon after BPTB autograft harvest. • Aim 2a: Examine the associations between patellar tendon morphology and mechanical properties with clinical and functional outcomes after ACLR using BPTB autograft. • Aim 2b: Evaluate the prognostic value of patellar tendon structure early after BPTB graft harvest to predict clinical and functional outcomes at later stages in rehabilitation. • Aim 3a: Identify deficits in quadriceps neuromuscular function during gait after ACLR using BPTB autograft compared to alternative graft types 5 months after ACLR. • Aim 3b: Determine whether quadriceps neuromuscular function during gait improves from 5 months to 24 months after ACLR using BPTB autograft. ☐ In aims 1 and 2, we collected patellar tendon structure and clinical data from patients after ACLR using BPTB at three critical timepoints (1-month, 3-4 months, 6-9 months) during rehabilitation. Aim 1 characterized the healing trajectory of both morphological (cross-sectional area, thickness, and length using B-mode ultrasound) and mechanical (shear modulus and viscosity using continuous shear wave elastography) properties in the medial, lateral, and central (graft site) regions of the patellar tendon. Through this aim we learnt that there is initial hypertrophy in the patellar tendon after graft harvest, which is most exaggerated in the central third, followed by a uniform reduction in size over the course of rehabilitation reflecting remodeling of the tendon. Tendon elongation was also seen in all three regions, with the medial and lateral region staying elongated over the course of rehabilitation and the central region shortening, likely attributed to bony healing at the graft site. Findings in mechanical properties were less clear. Viscosity was higher in the medial compared to the central and lateral regions primarily in the uninvolved limb, but a more uniform viscosity was observed in the involved limb. The viscosity in the involved limb also reduced over time in all three regions. Shear modulus was greater in the involved compared to uninvolved limb across all three regions initially after surgery, and shear modulus reduced from 1 month to 3-4 months, but only in the central region. Findings from this aim provide clinicians with a reference point for the expected healing trajectory of the patellar tendon after graft harvest. ☐ In aim 2, patellar tendon structural measures collected in aim 1 were used to predict quadriceps function (strength and inhibition) and patient reported outcome measures (Knee Outcome Survey – Activities of Daily Living Scale [KOS-ADLS] and International Knee Documentation Committee 2000 [IKDC]). Through this aim we learnt that patellar tendon hypertrophy early on after surgery is a major predictor of quadriceps strength later in rehabilitation. Presenting with greater cross-sectional area was also predictive of less quadriceps inhibition 3-4 months after ACLR. High viscosity at the 3-4 month timepoint, when the remodeling phase of tendon healing takes place, was predictive of quadriceps strength later on. By 6-9 months from surgery, patients with more symmetrical thickness, or likely better remodeled tendons, also demonstrated better quadriceps strength index. No structural variables were predictive of patient reported outcome measures. Findings from aim 2 support the use of ultrasound imaging to quantify patellar tendon structure early after ACLR as an early prognostic biomarker for quadriceps function. ☐ In aim 3, we quantified quadriceps neuromuscular function during walking gait in athletes after ACLR using BPTB autograft and compared them against those with grafts that did not insult the extensor mechanism. Quadriceps neuromuscular function was quantified using the extensor latency metric which measures the delay in peak external knee flexion moment (measured via motion capture and inverse dynamics) from peak quadriceps activation (measure via electromyography) during the weight acceptance phase of gait. Athletes were followed up 5 and 24 months after ACLR to assess whether BPTB autograft specific quadriceps neuromuscular deficits persist. Athletes after ACLR using BPTB autograft walked with longer latency in their involved limb compared to those who received alternative graft types. No changes in latency were seen, indicating that prolonged extensor latency persisted from rehabilitation until 2 years after surgery when most athletes were actively participating in sport. Neuromuscular changes identified in this aim may in part explain the elevated rates of developing post-traumatic OA after ACLR using the BPTB autograft compared to alternative graft types. Prolonged extensor latency may also influence knee biomechanics during other activities than gait, by impeding efficient control of the knee joint. This aim outlined how patellar tendon graft harvest may impede knee function for a prolonged period of time after ACLR. Early intervention to promote better healing of the graft site tendon may be necessary to preserve and recover neuromuscular function of the quadriceps after ACLR using BPTB autograft. ☐ This dissertation revealed the healing trajectory and influence of patellar tendon graft harvest over the course of rehabilitation. The influence of graft harvest was also shown to influence gait biomechanics 2 years after ACLR when athletes are commonly back to participating in their sport. Work from this dissertation supports the use of B-mode ultrasound early after ACLR to quantify healing of the patellar tendon, and to possibly implement treatments for those who may benefit from targeted interventions. Patellar tendon graft site morphology guided care may optimize recovery of quadriceps function, and possibly subsequent alterations in movement patterns such as gait and the development of post-traumatic knee OA. Future studies will investigate the impact of implementing an imaging guided graft site tendon loading protocol to investigate if we can optimize our current care to improve overall outcomes after ACLR using BPTB autograft.