Quantitative evaluation of natural progression of fatty infiltration and muscle atrophy in chronic rotator cuff tears without tear extension using magnetic resonance imaging.

Background: The pathology of and mechanisms underlying muscle degeneration remain unclear. We aimed to quantitatively evaluate the natural changes in fatty infiltration and muscle atrophy in patients with chronic rotator cuff tears using 3-dimensional 2-point Dixon magnetic resonance imaging. Methods: Thirty patients with nonoperatively observed rotator cuff tears without tear extension were evaluated using multiple magnetic resonance imaging examinations with a minimum interval of 2 years. The fatty infiltration ratio (%fat) and muscle volume of the rotator cuff muscles were compared between the 2 examinations in those with supraspinatus (SSP) tear <2 cm (<2 cm SSP group), SSP tear ≥2 cm (≥2 cm SSP group), and massive tear (massive group). The SSP) infraspinatus, and teres minor (ISP + TM), and subscapularis muscles were evaluated. Results: The massive group showed a significantly greater %fat than the <2 and ≥2 cm SSP groups in the SSP (P = .002) and ISP + TM muscles (P < .001). The total muscle volume did not differ among the 3 groups for all rotator cuff muscle components. The %fat values did not change in any rotator cuff components during the follow-up period in all groups. The total muscle volume in the massive group significantly decreased in the SSP (P = .018) and ISP + TM muscles (P = .013). Conclusion: The present results indicate that fatty infiltration of the torn muscle occurs in the early phase after a rotator cuff tear, whereas muscle atrophy appears to progress gradually in chronic rotator cuff tears. Early intervention before muscle degeneration should be considered if the tear involves the infraspinatus tendon.

Gender differences in spinal mobility during postural changes: a detailed analysis using upright CT.

Lumbar spinal alignment is crucial for spine biomechanics and is linked to various spinal pathologies. However, limited research has explored gender-specific differences using CT scans. The objective was to evaluate and compare lumbar spinal alignment between standing and sitting CT in healthy individuals, focusing on gender differences. 24 young and 25 elderly males (M) and females (F) underwent standing and sitting CT scans to assess lumbar spinal alignment. Parameters measured and compared between genders included lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lordotic angle (LA), foraminal height (FH), and bony boundary area (BBA). Females showed significantly larger changes in SS and PT when transitioning from standing to sitting (p = .044, p = .038). A notable gender difference was also observed in the L4-S LA among the elderly, with females showing a significantly larger decrease in lordotic angle compared to males (- 14.1° vs. - 9.2°, p = .039*). Females consistently exhibited larger FH and BBA values, particularly in lower lumbar segments, which was more prominent in the elderly group (M vs. F: L4/5 BBA 80.1 mm2 [46.3, 97.8] vs. 109.7 mm2 [74.4, 121.3], p = .019 in sitting). These findings underline distinct gender-related variations in lumbar alignment and flexibility, with a focus on noteworthy changes in BBA and FH in females. Gender differences in lumbar spinal alignment were evident, with females displaying greater pelvic and sacral mobility. Considering gender-specific characteristics is crucial for assessing spinal alignment and understanding spinal pathologies. These findings contribute to our understanding of lumbar spinal alignment and have implications for gender-specific spinal conditions and treatments.

Alteration of knee joint moment after anterior cruciate ligament reconstruction conditions in subjects with and without meniscal pathology.

BACKGROUND: The effects of anterior cruciate ligament (ACL) reconstruction on postoperative gait biomechanics remain controversial, and the influence of meniscus pathology on pre- and post-ACL reconstruction biomechanical changes has not yet been studied. Here, we aimed to clarify the difference in knee joint moment between pre- and post-ACL reconstruction conditions in subjects with and without meniscal pathology. METHODS: Twenty-four subjects with unilateral ACL reconstruction injuries participated in this study. A total of 13 of the subjects had concomitant meniscus injuries. Gait analysis was performed preoperatively and at 11 months postoperatively. Three-dimensional knee joint angles and moments were calculated based on motion-capture data. The total joint moment and contribution of individual moments during the stance phase were assessed. For statistical analysis, we compared pre- and postoperative alterations, and differences were assessed in subjects with and without meniscal pathology. RESULTS: Tibial rotation excursion was lower in subjects with meniscal pathology than in those with intact menisci postoperatively. An significant increase in the contribution of the knee flexion moment and a significant decrease in the contribution of the knee adduction moment postoperatively were observed in subjects with intact menisci. CONCLUSIONS: Patients with ACL injury showed different postoperative alterations in joint moments depending on the concomitant meniscal injury.

The tibial tubercle-to-trochlear groove distance changes in standing weight-bearing condition: An upright weight-bearing computed tomography analysis.

BACKGROUND: The tibial tubercle-to-trochlear groove (TT-TG) distance and Insall-Salvati (I/S) ratio are widely used to determine the need for distal realignment in conjunction with medial patellofemoral ligament (MPFL) reconstruction in patients with recurrent patellar dislocation. A TT-TG distance >20 mm and an I/S ratio >1.3 are significant anatomical risk factors for patellar instability. However, these parameters have traditionally been measured using non-weight-bearing (NWB) imaging modalities. As patellar dislocation occurs during weight-bearing actions, these two parameters should be measured under weight-bearing conditions. Thus, this study aimed to measure the TT-TG distance and I/S ratio using upright full-weight-bearing (FWB) computed tomography (CT) scans and compare the data with NWB CT scans. METHODS: This study included 49 knee joints of 26 healthy volunteers. CT images were obtained under both FWB and NWB standing conditions using a 320-detector row upright CT scanner. TT-TGs in the axial plane and I/S ratios in the sagittal plane were measured and compared. RESULTS: The average FWB TT-TG distance was 20.3 ± 3.9 mm, whereas the average NWB TT-TG distance was 12.3 ± 4.7 mm. The TT-TG level was significantly higher in the FWB condition than that in the NWB condition (P < 0.001). The I/S ratios were comparable between the FWB and NWB conditions (P = 0.29). CONCLUSIONS: The TT-TG distance in the standing weight-bearing condition was larger than the conventional TT-TG distance and surpassed the historical cutoff value of TT-TG, which may affect the indication of additional distal realignment in MPFL reconstruction for patellar instability.

Local alternating heat and cold stimulation affects hemodynamics and oxygenation in fatigued muscle tissue and autonomic nervous activity: a single-arm interventional study.

BACKGROUND: Local alternating heat and cold stimulation as an alternative to contrast bath may cause intermittent vasoconstriction and vasodilation, inducing a vascular pumping effect and consequently promoting increased tissue blood flow and oxygenation. This study aimed to examine the effects of local alternating heat and cold stimulation, using a wearable thermal device, on the hemodynamics of fatigued muscle tissue and autonomic nervous activity. METHODS: Twenty healthy individuals experienced fatigue in the periarticular muscles of the shoulder joint due to a typing task. Local alternating heat and cold stimulations were then applied to the upper trapezius muscle. Muscle hardness was measured using a muscle hardness meter, and muscle tissue hemodynamics and oxygenation were evaluated using near-infrared spectroscopy before and after the stimulation. Autonomic nervous activity was also evaluated using heart rate variability. RESULTS: Alternating heat and cold stimulation decreased muscle hardness of the fatigued trapezius muscle from 1.38 ± 0.15 to 1.31 ± 0.14 N (P < 0.01). The concentration of total hemoglobin in the trapezius muscle tissue increased from - 0.21 ± 1.36 to 2.29 ± 3.42 µmol/l (P < 0.01), and the tissue hemoglobin oxygen saturation also increased from 70.1 ± 5.4 to 71.1 ± 6.0% (P < 0.05). Additionally, the heart rate variability parameter, which is an index of sympathetic nervous activity, increased from 3.82 ± 2.96 to 6.86 ± 3.49 (P < 0.01). A correlation was found between increased tissue hemoglobin oxygen saturation and increased parameters of sympathetic nervous activity (r = 0.50, P < 0.05). CONCLUSIONS: Local alternating heat and cold stimulation affected the hemodynamic response in fatigued muscle tissue and autonomic nervous activity. This stimulation is more efficient than conventional contrast baths in terms of mobility and temperature control and has potential as a new versatile therapeutic intervention for muscle fatigue. TRIAL REGISTRATION: UMIN-CTR (UMIN000040087: registered on April 7, 2020, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000045710 . UMIN000040620: registered on June 1, 2020, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000046359 ).

Turning and sitting movements during timed up and go tests predict deterioration of physical function in middle-aged adults.

BACKGROUND: Deterioration of physical function in middle-aged adults is a significant challenge that can lead to increased risk of future falls. However, a screening method for the functional decline in middle-aged adults has not been established. RESEARCH QUESTION: To evaluate the relationship between biomechanical parameters assessed by the timed up and go test (TUG) and locomotive syndrome (LS) in middle-aged adults. METHODS: The inclusion criterion was: under 65 years of age. A total of 97 volunteers (mean age 51.1 years) participated in this study. An LS test was performed, including a 2-step test, a stand-up test, and a 25-question Geriatric Locomotive Function Scale. The TUG was measured using inertial measurement units (IMUs) at comfortable and fast speeds. We then determined the minimum values for anterior-posterior acceleration and angular velocity around the medial-lateral axis, as well as the maximum values of angular velocity around the vertical axis for the upper trunk and sacrum in a TUG phase. RESULTS: Angular velocity around the vertical axis for upper trunk and sacrum were significantly smaller in LS than non-LS in the turn phase of both speed conditions. For the fast speed condition, the minimum anterior-posterior acceleration for sacrum was greater in LS than in the non-LS condition for the stand-to-sit phase. Angular velocity around the vertical axis for turning and anterior-posterior acceleration from sitting were associated with detection of LS. SIGNIFICANCE: Turning and sitting movements during TUG should be observed using IMU to screen for physical function decline in middle aged adults.

Morphological features of the non-affected side of the hindfoot in patients with unilateral varus ankle osteoarthritis.

BACKGROUND: The innate shape characteristics of the hindfoot bones alter the loading conditions of the foot and thus may be associated with an increased risk of developing varus ankle osteoarthritis (OA). This study aimed to clarify the innate morphological patterns of the hindfoot bones that may be associated with ankle OA by analyzing the differences between the bone morphology of the non-affected side of patients with unilateral varus ankle OA and that of healthy participants. METHODS: In this case-control study, computed tomography images were used to develop three-dimensional models of three hindfoot bones (distal tibia with fibula, talus, and calcaneus) from 23 non-affected sides of patients with radiography-diagnosed unilateral ankle OA and 22 healthy control participants. Anatomical and sliding landmarks were placed on the surface of each bone, and the principal components (PCs) of shape variation among specimens were independently calculated for each bone, preserving homology between individuals. The PC modes representing 5% or more of the overall variation were statistically compared between the ankle OA and control groups. RESULTS: Significant differences were identified between the OA and control groups in the fifth PC mode for the tibia with fibula (proportion of variance, 5.1%; p =.025), fifth PC mode for the talus (6.7%, p =.031), and third PC mode for the calcaneus (7.4%, p =.001). The hindfoot bones of the participants who developed ankle OA had the following innate morphological characteristics: the lateral malleolar articular surface of the fibula was shifted superiorly, tibial plafond was enlarged posteroinferiorly, posterior width of the talar trochlea was narrower, talonavicular articular surface of the talus was oriented more frontally, anterior-middle talocalcaneal articular surfaces of the talus were more medially shifted and those of the calcaneus were flatter, calcaneal sustentaculum tali was less protruding, and lateral plantar process of the calcaneus was more superiorly positioned. CONCLUSIONS: These distinctive morphological alterations may increase the incidence and progression of varus ankle OA through aberrant anterior translation, internal rotation, and varus tilting of the talus.

Evaluation of the Anterior Cruciate Ligament Injury Risk During a Jump-Landing Task Using 3-Dimensional Kinematic Analysis Versus the Landing Error Scoring System.

Background: The Landing Error Scoring System (LESS) has been utilized on the field or in the clinic to identify patients with an increased risk for anterior cruciate ligament (ACL) injuries; however, its validity and efficacy have not been fully confirmed. Purpose: To assess the efficacy of the LESS in identifying the ACL injury risk by examining the correlation between the LESS score and motion patterns on 3-dimensional kinematic analysis. Study Design: Controlled laboratory study. Methods: The jump-landing motion was analyzed for 16 female basketball or badminton players who volunteered to participate in the study. All study participants were aged 19 or 20 years. The sequence of motion was evaluated with the LESS, while kinematic data were simultaneously acquired with a 3-dimensional motion analysis system utilizing the point cluster method. The correlation between the LESS score and knee kinematics was statistically analyzed. Results: When a LESS score ≥6 was defined to be a risk factor for ACL injuries, 7 of the 16 participants (43.8%) were found to exhibit risky motion patterns. Significant correlations were noted between the LESS score and knee valgus (r = 0.87; P < .0001) and internal tibial rotation (r = 0.57; P = .02) at landing. By contrast, a substantial variability was present in knee flexion, showing no correlation with the LESS score. Conclusion: Significant correlations were found between the LESS score and knee valgus and internal tibial rotation during a jump-landing task. Clinical Relevance: The LESS can be regarded as an effective measure to identify risky motion patterns that may increase the likelihood of ACL injuries.

Automatic measurement of the Cobb angle for adolescent idiopathic scoliosis using convolutional neural network.

This study proposes a convolutional neural network method for automatic vertebrae detection and Cobb angle (CA) measurement on X-ray images for scoliosis. 1021 full-length X-ray images of the whole spine of patients with adolescent idiopathic scoliosis (AIS) were used for training and segmentation. The proposed AI algorithm's results were compared with those of the manual method by six doctors using the intraclass correlation coefficient (ICC). The ICCs recorded by six doctors and AI were excellent or good, with a value of 0.973 for the major curve in the standing position. The mean error between AI and doctors was not affected by the angle size, with AI tending to measure 1.7°-2.2° smaller than that measured by the doctors. The proposed method showed a high correlation with the doctors' measurements, regardless of the CA size, doctors' experience, and patient posture. The proposed method showed excellent reliability, indicating that it is a promising automated method for measuring CA in patients with AIS.

Dynamic evaluation of the sternoclavicular and acromioclavicular joints using an upright four-dimensional computed tomography.

In the analysis of the shoulder complex, the sequential changes occurring in the sternoclavicular and acromioclavicular joints during active shoulder motion are challenging to track. This study aimed to investigate the in vivo sternoclavicular and acromioclavicular joint motions during active elevation, including the sequential changes in these joint spaces using upright four-dimensional computed tomography (4DCT). Bilateral shoulders of 12 healthy volunteers upright 4DCT were obtained during active elevation similar to a "hands up" motion. The sternoclavicular and acromioclavicular rotation angles, joint distances, and closest points on the clavicle relative to the thorax and scapula were evaluated during 10°-140° of humerothoracic elevation. During humerothoracic elevation, the clavicle elevated, retracted, and rotated posteriorly relative to the thorax, whereas the scapula rotated upwardly, internally, and posteriorly relative to the clavicle. All the sternoclavicular and acromioclavicular joint rotation angles were significantly different at ≥ 30°-50° of humerothoracic elevation compared with 10° of humerothoracic elevation. The mean sternoclavicular and acromioclavicular joint distances were 2.2 ± 1.1 mm and 1.6 ± 0.9 mm, respectively. The closest points were located on the anteroinferior part of the medial and lateral clavicle in the sternoclavicular and acromioclavicular joints, respectively. Significant differences were observed in the acromioclavicular joint distance and anterior/posterior movements of the closest points in the sternoclavicular and acromioclavicular joints compared with 10° of humerothoracic elevation. Our sternoclavicular and acromioclavicular closest point results indicate that the impingement tends to occur at the anteroinferior part of the medial and lateral aspects of the clavicle and may be related to osteoarthritis.

Extra-articular location of the three-dimensional mechanical axis in advanced knee osteoarthritis: an upright computed tomography study.

PURPOSE: One of the most widely used benchmarks of lower-limb alignment is the mechanical axis (MA), which passes through the centers of the femoral head and the ankle in the weight-bearing position. However, where the MA passes through three-dimensionally (3D) is unclear. We investigated the MA in 3D (3D-MA) in knee osteoarthritis (OA) using upright computed tomography (CT). MATERIALS AND METHODS: This study included 66 varus OA knees from 38 patients [age 70.0 (64.8-77.0) years; median (interquartile range)]. The 3D-MA was determined using upright CT data and compared among Kellgren-Lawrence (KL) grades. Further, correlations between the 3D-MA and other parameters were evaluated. RESULTS: The 3D-MA was located at 5.3 (1.3-14.4)% medially and 7.1 (0.7-15.3)% posteriorly on the tibial plateau in KL-1, and was translated medioposteriorly with increased KL grade. The 3D-MA in KL-3 [30.6 (22.6-42.6)% medially and 50.9 (45.8-80.2)% posteriorly] and KL-4 [56.7 (48.5-62.9)% medially and 92.3 (50.2-127.1)% posteriorly] was located extra-articularly. The mediolateral position of the 3D-MA correlated with the femorotibial angle [correlation coefficient (CC) = - 0.85, p < 0.001], and the anteroposterior position of the 3D-MA correlated with the knee flexion angle (CC = - 0.93, p < 0.001). CONCLUSION: Our analysis demonstrated that the 3D-MA in low-grade OA knees passes slightly medial and posterior to the knee center, and the 3D-MA is translated medioposteriorly with the progression of knee OA. Further, the 3D-MA is translated medially with varus progression and posteriorly with the progression of knee flexion contracture.

Three-dimensional joint surface orientation does not correlate with two-dimensional coronal joint line orientation in knee osteoarthritis: Three-dimensional analysis of upright computed tomography.

BACKGROUND: Two-dimensional (2D) coronal joint line orientation on radiography under weight-bearing conditions has been widely used in evaluating knee osteoarthritis (OA). However, the effects of tibial rotation remain unknown. The present study aimed to newly define three-dimensional (3D) joint surface orientation relative to the floor as an unchangeable 3D angle unaffected by tibial rotation using upright computed tomography (CT), and to investigate correlations between 3D and 2D parameters in knee OA. METHODS: Sixty-six knees in 38 patients with varus knee OA underwent standing hip-to-ankle digital radiography and upright CT. The 2D parameters measured on radiographs included femorotibial angle (FTA), tibial joint line angle (TJLA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). The 3D inner product angle between vectors of the tibial joint surface and the floor from CT was defined as the 3D joint surface-floor angle. RESULTS: Mean 3D joint surface-floor angle was 6.0 ± 3.6°. No correlation was identified between 3D joint surface-floor angle and 2D joint line parameters, even though FTA correlated substantially with 2D joint line parameters. No significant differences in 3D joint surface-floor angle were identified among Coronal Plane Alignment of the Knee (CPAK) types. CONCLUSIONS: The 3D joint surface orientation did not correlate with 2D coronal joint line orientation and was unaffected by CPAK classification types. This finding suggests that current 2D evaluations should be reconsidered for a better understanding of true knee joint line orientation.

Implications of the Onset of Sweating on the Sweat Lactate Threshold.

The relationship between the onset of sweating (OS) and sweat lactate threshold (sLT) assessed using a novel sweat lactate sensor remains unclear. We aimed to investigate the implications of the OS on the sLT. Forty healthy men performed an incremental cycling test. We monitored the sweat lactate, blood lactate, and local sweating rates to determine the sLT, blood LT (bLT), and OS. We defined participants with the OS during the warm-up just before the incremental test as the early perspiration (EP) group and the others as the regular perspiration (RP) group. Pearson's correlation coefficient analysis revealed that the OS was poorly correlated with the sLT, particularly in the EP group (EP group, r = 0.12; RP group, r = 0.56). Conversely, even in the EP group, the sLT was strongly correlated with the bLT (r = 0.74); this was also the case in the RP group (r = 0.61). Bland-Altman plots showed no bias between the mean sLT and bLT (mean difference: 19.3 s). Finally, in five cases with a later OS than bLT, the sLT tended to deviate from the bLT (mean difference, 106.8 s). The sLT is a noninvasive and continuous alternative to the bLT, independent of an early OS, although a late OS may negatively affect the sLT.

In Vivo Metacarpophalangeal Joint Kinematics After Silicone Implant Arthroplasty in Patients With Rheumatoid Arthritis.

PURPOSE: The aim of this study was to determine the potential mechanism of implant fracture using 3-dimensional motion analysis of patients with rheumatoid arthritis. METHODS: Active flexion motion in 9 hands (34 fingers) of 6 female patients with rheumatoid arthritis who previously underwent hinged silicone metacarpophalangeal joint arthroplasty was examined using 4-dimensional computed tomography. Positions of the proximal phalanges relative to the metacarpals were quantified using a surface registration method. The deformation of the silicone implant was classified in the sagittal plane in the maximum flexion frame. The longitudinal bone axis of the proximal phalanx and the helical axis of the proximal phalanx were evaluated in 3-dimensional coordinates based on the hinge of the silicone implant. RESULTS: Nineteen fingers were classified into group 1, in which the silicone implant moved volarly during flexion without buckling of the distal stem. Twelve fingers were classified into group 2, in which the distal stem of the silicone implant buckled. Three fingers were classified into group 3, in which the base of the distal stem had already fractured. Quantitatively, the longitudinal bone axes of the proximal phalanges were displaced from dorsal to volar in the middle stage of flexion and migrated in the proximal direction in the late phase of flexion. The helical axes of the proximal phalanges were located on the dorsal and proximal sides of the hinge, and these tended to move in the volar and proximal directions as the metacarpophalangeal joint flexed. CONCLUSIONS: Volar and proximal translation of the proximal phalange was observed on 4-dimensional computed tomography. CLINICAL RELEVANCE: Proximal displacement of the bone axis late in flexion appears to be a contributing factor inducing implant fractures, because the pistoning motion does not allow the implant to move in the proximal direction.

Three-dimensional shoulder kinematics: Upright four-dimensional computed tomography in comparison with an optical three-dimensional motion capture system.

Although shoulder kinematics have been analyzed by various methods, dynamic shoulder motion is difficult to track. This study aimed to validate the shoulder kinematic analysis using upright four-dimensional computed tomography (4DCT) and to compare the results with optical three-dimensional motion capture. During active elevation, bilateral shoulders of 10 healthy volunteers were tracked using 4DCT and motion capture. The scapulothoracic and glenohumeral rotations and the scapulohumeral rhythm (SHR) at each position were calculated, and the differences between 4DCT and motion capture were compared. During 10-140° of humerothoracic elevation, the scapulothoracic joint showed upward rotation, internal rotation, and posterior tilting, and the glenohumeral joint showed elevation, external rotation, and anterior plane of elevation in both analyses. In scapulothoracic rotations, the mean differences between the two analyses were -2.6° in upward rotation, 13.9° in internal rotation, and 6.4° in posterior tilting, and became significant with humerothoracic elevation ≥110° in upward rotation, ≥50° in internal rotation, and ≥100° in posterior tilting. In glenohumeral rotations, the mean differences were 3.7° in elevation, 9.1° in internal rotation, and -8.8° in anterior plane of elevation, and became significant with humerothoracic elevation ≥110° in elevation, ≥90° in internal rotation, and ≥100° in anterior plane of elevation. The mean overall SHRs were 1.8 in 4DCT and 2.4 in motion capture, and the differences became significant with humerothoracic elevation ≥100°. The 4DCT analysis of in vivo shoulder kinematics using upright computed tomography scanner is feasible, but the values were different from those by skin-based analysis at the elevated arm positions.

Changes in the lumbar intervertebral foramen between supine and standing posture in patients with adult spinal deformity: a study with upright computed tomography.

OBJECTIVE: To quantitatively assess the impact of supine and standing positions on the morphological changes in the lumbar intervertebral foramen (LIF) in patients with adult spinal deformity (ASD) using upright CT and conventional supine CT. MATERIALS AND METHODS: Thirty patients with ASD were prospectively enrolled in this study. All subjects underwent standing whole spine posterior/anterior radiographs, lateral radiographs, and whole spine CT, both in the supine and upright standing positions. Two orthopedic surgeons independently measured nine radiographic parameters in the radiograph and the lumbar foraminal area (FA) and height (FH) in supine and upright CT. Statistical analyses were performed to evaluate the risk of LIF decrease when standing upright compared to the supine position. The chi-squared, t test, Pearson's coefficients, intra- and inter-rater reliabilities, and ROC curves were calculated. The level of significance was set at p < 0.05. RESULTS: Among the 300 LIFs, both the lumbar FA and FH were either increased or decreased by > 5% in approximately 30% of LIFs each. The FA decreased in the lower lumbar spine. The concave side had a significantly higher rate of decreased FA and FH than the convex side (p < 0.05 and < 0.05, respectively). ROC analysis showed that narrowing of the intervertebral disc (cutoff > 0.05°) is a risk factor for decreased FA and FH. CONCLUSIONS: This study describes the details of the changes in the neuroforamen using a novel upright CT. In patients with ASD, approximately 30% of LIFs either increased or decreased in size by > 5% when standing. The risk factors for LIF decrease are the lower lumbar spine, concave side, and narrow side of the disc wedge.

Constant Load Pedaling Exercise Combined with Electrical Muscle Stimulation Leads to an Early Increase in Sweat Lactate Levels.

A novel exercise modality combined with electrical muscle stimulation (EMS) has been reported to increase cardiovascular and metabolic responses, such as blood lactate concentration. We aimed to examine the effect of constant load pedaling exercise, combined with EMS, by non-invasively and continuously measuring sweat lactate levels. A total of 22 healthy young men (20.7 ± 0.8 years) performed a constant load pedaling exercise for 20 min at 125% of the pre-measured ventilatory work threshold with (EMS condition) and without (control condition) EMS stimulation. Blood lactate concentration was measured by blood samples obtained from the earlobe every minute. Sweat lactate was monitored in real time using a sensor placed on the forearm. The sweat lactate threshold (sLT) was defined as the point of increase in sweat lactate. sLT occurred significantly earlier in the EMS condition than in the control condition. In the single regression analysis, the difference in sLT between the two conditions, as the independent variable, was a significant predictor of the difference in blood lactate concentrations at the end of the exercise (p < 0.05, r = −0.52). Sweat lactate measurement may be a noninvasive and simple alternative to blood lactate measurement to determine the effectiveness of exercise combined with EMS.