Knee locking caused by osteochondroma of the proximal tibia adjacent to the pes anserinus: A case report.

BACKGROUND: Osteochondroma is one of the most common benign bone tumors, and it may cause bone and joint deformities and limited range of motion of an adjacent joint. The pes anserinus region is one of the most frequent sites of osteochondroma, but knee locking caused by osteochondromas in the pes anserinus region is extremely rare. CASE SUMMARY: We describe a 13-year-old Japanese girl's extra-articular knee locking that occurred when the semitendinosus tendon got caught in osteochondroma that had developed in the pes anserinus region. The osteochondroma was surgically resected. The postoperative outcome has been excellent, with no recurrence of knee locking or tumor one-year post-surgery. CONCLUSION: When a young person develops knee locking, the possibility of extra-articular as well as intra-articular locking should be considered. Osteochondroma, one of the causes of extra-articular locking, can be treated with surgery with good postoperative results.

Throwing distance and competitive performance of Boccia players.

[Purpose] This study aimed to clarify the relationship between throwing distance and competitive performance in Boccia players in order to establish a training program based on this evidence. [Participants and Methods] In total, 40 athletes, who competed in the Japan Boccia Championships and are certified players of the Japan Boccia Association, participated in the study. Participants threw the Boccia ball as far as possible, and throwing distances were compared between certified players (Group I, n=8), those who participated in the final round (Group II, n=9), and those who lost in the preliminary round (Group III, n=23). [Results] The maximum throwing distances were 16.38 ± 5.17 m (Group I), 10.67 ± 2.66 m (Group II), and 8.34 ± 2.73 m (Group III). Group I threw the ball significantly farther than Groups II and III. [Conclusion] Boccia is a target sport and throwing farther distances requires more effort. In addition, being able to throw at a longer distance means that Boccia players can throw a stronger ball and use this for various tactics. The results of this study suggest that long-distance throwing training would be effective in improving the competitive performance of Boccia players.

Spinal Injuries in Suicidal Jumpers.

STUDY DESIGN: This was a retrospective case series at a single institution. OBJECTIVE: The study was performed to investigate the characteristics of spinal injuries in survivors of suicidal jumping. SUMMARY OF BACKGROUND DATA: Spinal fracture/dislocation is associated with high-energy trauma such as that induced by motor vehicle accidents. Survivors of suicidal jumping sometimes sustain spinal injuries. However, the characteristics of such spinal injuries are unclear. METHODS: We identified 87 survivors of suicidal jumping who sustained spinal injuries from 2007 to 2016 in our institution. We compared the demographic data, radiological findings, neurological status, associated injuries, treatments, and mental health conditions between these 87 survivors and 204 non-suicidal patients with spinal injury. RESULTS: Suicidal jumpers were predominantly female (67%) and 10 years younger than non-suicidal patients. Mental health problems, mainly schizophrenia and depression, were diagnosed in 77% of suicidal jumpers. Neurological damage from spinal trauma was generally less severe in suicidal jumpers than in non-suicidal patients. Most spinal injuries in suicidal jumpers were located in the thoracic or lumbar spine region (85%). Among comorbid injuries, extremity injuries were highly associated with spine injury in suicidal jumpers. Nearly 70% of suicidal jumpers exhibited extremity injury in contrast to 33% of non-suicidal patients. Approximately, 25% of suicidal jumpers underwent surgical treatment. Surgical treatment was similarly performed on suicidal jumpers and non-suicidal patients regardless of the discrepancy in neurological damage between these two groups. CONCLUSION: Spinal injuries in suicidal jumpers differed from spinal injuries in non-suicidal patients with regard to sex, age, mental health condition, injury location, neurologic damage, and associated injuries. Most survivors of suicidal jumping were young female patients with mental health problems. They tended to have thoracic and lumbar spine trauma rather than cervical trauma with less severe neurological deficits and a higher incidence of accompanying limb injury. LEVEL OF EVIDENCE: 3.

Hounsfield unit of screw trajectory as a predictor of pedicle screw loosening after single level lumbar interbody fusion.

OBJECT: This study aims to clarify the clinical potential of Hounsfield unit (HU), measured on computed tomography (CT) images, as a predictor of pedicle screw (PS) loosening, compared to bone mineral density (BMD). METHODS: A total of 206 screws in 52 patients (21 men and 31 women; mean age 68.2 years) were analyzed retrospectively. The screws were classified into two groups depending on their screw loosening status on 3-month follow-up CT (loosening screw group vs. non-loosening screw group). Preoperative HU of the trajectory was evaluated by superimposing preoperative and postoperative CT images using three-dimensional image analysis software. Age, sex, body mass index, screw size, BMD of lumbar, and HU of screw trajectory were analyzed in association with screw loosening. Multivariate logistic regression analysis was performed, and the thresholds for PS loosening risk factors were evaluated using a continuous numerical variable and receiver operating characteristic (ROC) curve analyses. The area under the curve (AUC) was used to determine the diagnostic performance, and values > 0.75 were considered to represent good performance. RESULTS: The loosening screw group contained 24 screws (12%). Multivariate analysis revealed that the significant independent risk factors were not BMD but male sex [P = 0.028; odds ratio (OR) 2.852, 95% confidence interval (CI) 1.120-7.258] and HU of screw trajectory (P = 0.006; OR 0.989, 95% CI 0.980-0.997). ROC curve analysis demonstrated that the AUC for HU of screw trajectory for women was 0.880 (95% CI 0.798-0.961). The cutoff value was 153.5. AUC for men was 0.635 (95% CI 0.449-0.821), which was not considered to be a good performance. CONCLUSIONS: Low HU of screw trajectories was identified as a risk factor of PS loosening for women. For female patients with low HU, additional augmentation is recommended to prevent PS loosening.

Correction to: Attenuation of cortical activity triggering descending pain inhibition in chronic low back pain patients: a functional magnetic resonance imaging study.

Inadvertently, the Fig. 7 was published incorrectly in the original publication of the article. The correct figure should be as below.

Attenuation of cortical activity triggering descending pain inhibition in chronic low back pain patients: a functional magnetic resonance imaging study.

PURPOSE: A considerable portion of chronic low back pain (cLBP) patients lack anatomical abnormality, resist conventional therapeutic interventions, and their symptoms are often complicated with psychological and social factors. Such patients have been reported to show cerebral abnormalities both in anatomy and function by neuroimaging studies. Here we examined differences in cerebral reactivity to a simulated low back pain stimulus between cLBP patients and healthy controls by functional magnetic resonance imaging (fMRI), and their behavioral correlates from a psychophysical questionnaire. METHODS: Eleven cLBP patients and 13 healthy subjects (HS) were enrolled in this study. After psychophysical evaluation on-going pain with McGill Pain Questionnaire Short Form (MPQ), they underwent whole-brain fMRI in a 3-Tesla MRI scanner while receiving three blocks of 30-s mechanical pain stimuli at the left low back with a 30-s rest in between, followed by a three-dimensional anatomical imaging. Functional images were analyzed with a multi-subject general linear model for blood oxygenation level-dependent (BOLD) signal changes associated with pain. Individual BOLD signal amplitudes at activated clusters were examined for correlation with psychophysical variables. Two in the cLBP and five data sets in the HS groups were excluded from analysis because of deficient or artifactual data or mismatch in age. RESULTS: The HS group showed LBP-related activation at the right insular cortex, right dorsolateral prefrontal cortex (DLPFC), left anterior cingulate cortex (ACC), and left precuneus; and deactivation in a large area over the parietal and occipital cortices, including the bilateral superior parietal cortex. On the other hand, the cLBP group did not show any significant activation at those cortical areas, but showed similar deactivation at the bilateral superior parietal cortex and part of the premotor area. An HS > cLBP contrast revealed significantly less activity at the ACC and DLPFC in the cLBP group, which was negatively correlated with higher MPQ scores. CONCLUSIONS: The cLBP patients showed attenuated reactivity to pain at the ACC and DLPFC, known cortical areas mediating affective component, and top-down modulation, of pain. The present results might be associated with possible dysfunction of the descending pain inhibitory system in patients with chronic low back pain, which might possibly play a role in chronification of pain.

Psychosocial Stress After a Disaster and Low Back Pain-Related Interference With Daily Living Among College Students: A Cohort Study in Fukushima.

STUDY DESIGN: A cohort study. OBJECTIVE: To investigate the association between psychosocial stress and low back pain (LBP)-related interference with daily living among college students. SUMMARY OF BACKGROUND DATA: Few longitudinal studies have examined the likelihood of developing LBP in the presence of a designated psychosocial stressor. All participants in the present study were suddenly affected by the Great East Japan disaster after enrolment in our cohort study. METHODS: The present study was initiated among 95 students at Fukushima Medical University in January 2011. We assessed psychosocial stress in students using the Japanese version of the Perceived Stress Scale (JPSS). Follow-up surveys were conducted in July 2011 and May 2013, analyzing 94 students. Students were then divided into three groups (improved, -19 to -4; Maintained, -3 to +4; Aggravated, +5 to +22) based on the tertile points of JPSS change from baseline to 4 months after the disaster. LBP-related interference with daily living was assessed using the Brief Pain Inventory (BPI) questionnaire. Linear regression modeling was performed with BPI at 4 months after the disaster as the outcome, and JPSS change, sex, history of LBP, baseline physical activity, and baseline BPI as explanatory variables. RESULTS: We found a significant increase in BPI score for the aggravated stress group (ß coefficient, +0.79; 95% confidence interval, +0.06-+1.53), compared with the improved stress group. History of LBP and higher physical activity were also significantly associated with BPI. CONCLUSION: The present study suggests that perceived psychosocial stress induced by the disaster may be associated with LBP-related interference with daily living among college students in Fukushima. LEVEL OF EVIDENCE: 3.

Sacroiliac joint motion in patients with degenerative lumbar spine disorders.

OBJECT Usually additional anchors into the ilium are necessary in long fusion to the sacrum for degenerative lumbar spine disorders (DLSDs), especially for adult spine deformity. Although the use of anchors is becoming quite common, surgeons must always keep in mind that the sacroiliac (SI) joint is mobile and they should be aware of the kinematic properties of the SI joint in patients with DLSDs, including adult spinal deformity. No previous study has clarified in vivo kinematic changes in the SI joint with respect to patient age, sex, or parturition status or the presence of DLSDs. The authors conducted a study to clarify the mobility and kinematic characteristics of the SI joint in patients with DLSDs in comparison with healthy volunteers by using in vivo 3D motion analysis with voxel-based registration, a highly accurate, noninvasive method. METHODS Thirteen healthy volunteers (the control group) and 20 patients with DLSDs (the DLSD group) underwent low-dose 3D CT of the lumbar spine and pelvis in 3 positions (neutral, maximal trunk flexion, and maximal trunk extension). SI joint motion was calculated by computer processing of the CT images (voxel-based registration). 3D motion of the SI joint was expressed as both 6 df by Euler angles and translations on the coordinate system and a helical axis of rotation. The correlation between joint motion and the cross-sectional area of the trunk muscles was also investigated. RESULTS SI joint motion during trunk flexion-extension was minute in healthy volunteers. The mean rotation angles during trunk flexion were 0.07° around the x axis, -0.02° around the y axis, and 0.16° around the z axis. The mean rotation angles during trunk extension were 0.38° around the x axis, -0.08° around the y axis, and 0.08° around the z axis. During trunk flexion-extension, the largest amount of motion occurred around the x axis. In patients with DLSDs, the mean rotation angles during trunk flexion were 0.57° around the x axis, 0.01° around the y axis, and 0.19° around the z axis. The mean rotation angles during trunk extension were 0.68° around the x axis, -0.11° around the y axis, and 0.05° around the z axis. Joint motion in patients with DLSDs was significantly greater, with greater individual difference, than in healthy volunteers. Among patients with DLSDs, women had significantly more motion than men did during trunk extension. SI joint motion was significantly negatively correlated with the cross-sectional area of the trunk muscles during both flexion and extension of the trunk. CONCLUSIONS The authors elucidated the mobility and kinematic characteristics of the SI joint in patients with DLSDs compared with healthy volunteers for the first time. This information is useful for spine surgeons because of the recent increase in spinopelvic fusion for the treatment of DLSDs.

The bone morphogenetic protein-2/7 heterodimer is a stronger inducer of bone regeneration than the individual homodimers in a rat spinal fusion model.

BACKGROUND CONTEXT: Bone morphogenetic proteins (BMPs) are a group of dimeric growth factors that belong to the transforming growth factor super family and are capable of eliciting new bone formation. Previous studies have suggested that the coexpression of two different BMP genes in a cell can result in the production of BMP heterodimers that are more potent than homodimers. However, because of the difficulty in optimizing the level of BMP gene expression, the coexpression of two different BMP genes also produces BMP homodimers as a by-product. These homodimers could, in theory, interact with the heterodimers. PURPOSE: To elucidate the effects of a BMP-2/7 heterodimer, which were investigated in depth using purified BMP-2/7 heterodimers, BMP-2 homodimers, and BMP-7 homodimers in a rat spinal fusion model. METHODS: Bilateral posterolateral fusion at L4-L5 was performed in four different groups: control group animals were implanted with collagen carriers alone; BMP-7 group animals with collagen carriers+1 µg of BMP-7 homodimer; BMP-2 group animals with collagen carriers+1 µg of BMP-2 homodimer; and BMP-2/7 group animals with collagen carriers+1 µg of the BMP-2/7 heterodimer. The following assessments were performed: bone microstructural analysis of the fusion mass and tissue volume (TV) with microcomputed tomography (micro-CT); fusion assessment with manual palpation testing and three-dimensional CT images; and bone histomorphometrical analysis of the fusion mass. RESULTS: The fusion scores, as determined by radiography, and the TV of the newly formed bone, as determined by micro-CT, were significantly higher in the BMP-2/7 heterodimer group than the other groups (p<.0001). The microstructural indices of the newly formed bone did not differ between the groups. Moreover, histologic analysis of the fused spines revealed that the formation of the trabecular bone bridging the transverse process was the highest in this group. CONCLUSIONS: This study demonstrated that BMP-2/7 heterodimer is a stronger inducer of bone regeneration than BMP-2 or -7 homodimers. The use of a purified BMP-2/7 heterodimer may represent an efficient alternative to the current clinical use of BMP-2 or -7 homodimers. Further studies as to the side effects of BMP-2/7 heterodimer are required.

3D morphometric analysis of laminae and facet joints in patients with degenerative spondylolisthesis.

OBJECTIVE: To clarify the three-dimensional (3D) morphometric characteristics of the spine in patients with degenerative spondylolisthesis (DS). METHODS: 3D morphometric analyses of laminae and facets were performed and compared for a DS group, an age-matched spinal canal stenosis (LCS) group, and a control group of young persons without spinal disease. 3D facet sagittal angles (3D-FSAs), 3D facet axial angle (3D-FAAs), and 3D-FAA tropism at L3 and at L4 were measured by extracting the 3D inferior articular process. The 3D lamina inclination angles (3D-LIAs) of L3 and L4 were also measured by extracting the ventral surface of the laminae. RESULTS: The 3D-FSAs at L4 in the DS group were significantly higher than for the other groups, but the difference in 3D-FSAs at L3 was not statistically significant among the groups. The 3D-FAAs at L4 in the DS group were significantly lower than in the control group. There was no significant difference in other factors. CONCLUSIONS: 3D morphometric analysis clarified that DS is significantly correlated with horizontalization (higher 3D-FSA), but is not correlated with sagittalization (lower 3D-FAA) and tropism (3D-FAA tropism) of facet joints or horizontalization of laminae (3D-LIA). There were no morphometric characteristics at the cranial adjacent segment of DS.

Intermittent administration of teriparatide enhances graft bone healing and accelerates spinal fusion in rats with glucocorticoid-induced osteoporosis.

BACKGROUND CONTEXT: There has been no study regarding the effect of intermittent administration of teriparatide (TPTD [recombinant human parathyroid hormone (1-34)]) on spinal fusion in patients with glucocorticoid-induced osteoporosis (GIOP). PURPOSE: To elucidate the effect of intermittent administration of TPTD on spinal fusion in rats with GIOP. STUDY DESIGN: An experimental animal study of rats under continuous glucocorticoid (GC) exposure undergoing spinal fusion surgery and administration of TPTD or saline. METHODS: Male 8-week-old rats (n=18) were administered 5 mg/kg methylprednisolone (MP) for 12 weeks. After 6 weeks of MP administration, the rats underwent posterolateral spinal fusion (L4-L5) with iliac crest autograft. Then, five times a week, they were given either saline or 40 µg/kg TPTD for 6 weeks. The following assessments were performed: time-course bone microstructural analysis of the fusion mass and adjacent vertebrae (L6), with in vivo microcomputed tomography (µCT); fusion assessment, with manual palpation testing and three-dimensional CT images; and bone histomorphometrical analysis of the fusion mass. RESULTS: In the TPTD group, values for bone volume and other bone microstructural parameters at the fusion mass increased and peaked 4 weeks after surgery, and these values were significantly greater than those for the control (CNT) group at 4 and 6 weeks after surgery. Fusion assessment showed that fusion rate was higher in the TPTD group than in the CNT group (CNT group: 56%, TPTD group: 89%). Bone histomorphometry revealed that values for bone formation parameters were significantly higher in the TPTD group than in the CNT group. CONCLUSIONS: Under continuous GC exposure in a rat model of spinal fusion, intermittent TPTD administration accelerated bone modeling and remodeling predominantly by stimulating bone formation at the fusion mass and increasing the fusion rate. Intermittent TPTD administration also improved bone microarchitecture of adjacent vertebrae.

Effect of Intermittent Administration of Teriparatide (Parathyroid Hormone 1-34) on Bone Morphogenetic Protein-Induced Bone Formation in a Rat Model of Spinal Fusion.

BACKGROUND: Although clinical bone morphogenetic protein (BMP) therapy is effective at enhancing bone formation in patients managed with spinal arthrodesis, the required doses are very high. Teriparatide (parathyroid hormone 1-34) is approved by the U.S. Food and Drug Administration to treat osteoporosis and is a potent anabolic agent. In this study, intermittent administration of parathyroid hormone 1-34 combined with transplantation of BMP was performed to elucidate the effect of parathyroid hormone 1-34 on the fusion rate and quality of newly formed bone in a rat model. METHODS: A total of forty-eight male Sprague-Dawley rats underwent posterolateral lumbar spinal arthrodesis with one of three different treatments with recombinant human (rh) BMP-2: (1) 0 µg (control), (2) 2 µg (low dose), or (3) 50 µg (high dose). Each of the rhBMP-2 treatments was studied in combination with intermittent injections of either parathyroid hormone 1-34 (180 µg/kg/wk) or saline solution starting two weeks before the operation and continuing until six weeks after the operation. Osseous fusion was assessed with use of radiographs and a manual palpation test. Microstructural indices of the newly formed bone were evaluated with use of micro-computed tomography. The serum markers of bone metabolism were also quantified. RESULTS: The fusion rate in the group treated with 2 µg of rhBMP-2 significantly increased (from 57% to 100%) with the administration of parathyroid hormone 1-34 (p < 0.05). The fusion rates in the other groups did not change significantly with the administration of parathyroid hormone 1-34. The bone volume density of the newly formed bone significantly increased in both the 2-µg and 50-µg rhBMP-2 treatment groups with the administration of parathyroid hormone 1-34 (p < 0.01). Micro-computed tomography scans of the newly formed bone clearly demonstrated an abundance of trabecular bone formation in the group treated with parathyroid hormone 1-34. In addition, serum levels of osteocalcin were significantly increased in the parathyroid hormone 1-34 treatment group. CONCLUSIONS: Intermittent administration of parathyroid hormone 1-34 significantly increased fusion rates in the group treated with low-dose rhBMP-2, and it improved the quality of the newly formed bone in both the high and low-dose groups in a rat model of rhBMP-2-induced spinal fusion. CLINICAL RELEVANCE: Our results suggest that the combined administration of rhBMP-2 and parathyroid hormone 1-34 may lead to efficient bone regeneration.

In vivo 3D kinematic changes in the cervical spine after laminoplasty for cervical spondylotic myelopathy.

OBJECT: Cervical laminoplasty is an effective procedure for decompressing the spinal cord at multiple levels, but restriction of neck motion is one of the well-known complications of the procedure. Although many authors have reported on cervical range of motion (ROM) after laminoplasty, they have focused mainly on 2D flexion and extension on lateral radiographs, not on 3D motion (including coupled motion) nor on precise intervertebral motion. The purpose of this study was to clarify the 3D kinematic changes in the cervical spine after laminoplasty performed to treat cervical spondylotic myelopathy. METHODS: Eleven consecutive patients (6 men and 5 women, mean age 68.1 years, age range 57-79 years) with cervical spondylotic myelopathy who had undergone laminoplasty were included in the study. All patients underwent 3D CT of the cervical spine in 5 positions (neutral, 45° head rotation left and right, maximum head flexion, and maximum head extension) using supporting devices. The scans were performed preoperatively and at 6 months after laminoplasty. Segmental ROM from Oc-C1 to C7-T1 was calculated both in flexion-extension and in rotation, using a voxel-based registration method. RESULTS: Mean C2-7 flexion-extension ROM, equivalent to cervical ROM in all previous studies, was 45.5° ± 7.1° preoperatively and 35.5° ± 8.2° postoperatively, which was a statistically significant 33% decrease. However, mean Oc-T1 flexion-extension ROM, which represented total cervical ROM, was 71.5° ± 8.3° preoperatively and 66.5° ± 8.3° postoperatively, an insignificant 7.0% decrease. In focusing on each motion segment, the authors observed a statistically significant 22.6% decrease in mean segmental ROM at the operated levels during flexion-extension and a statistically insignificant 10.2% decrease during rotation. The most significant decrease was observed at C2-3. Segmental ROM at C2-3 decreased 24.2% during flexion-extension and 21.8% during rotation. However, a statistically insignificant 37.2% increase was observed at the upper cervical spine (Oc-C2) during flexion-extension. The coupling pattern during rotation did not change significantly after laminoplasty. CONCLUSIONS: In this first accurate documentation of 3D segmental kinematic changes after laminoplasty, Oc-T1 ROM, which represented total cervical ROM, did not change significantly during either flexion-extension or rotation by 6 months after laminoplasty despite a significant decrease in C2-7 flexion-extension ROM. This is thought to be partially because of a compensatory increase in segmental ROM at the upper cervical spine (Oc-C2).

Kinematics of the thoracic spine in trunk lateral bending: in vivo three-dimensional analysis.

BACKGROUND CONTEXT: In vivo three-dimensional kinematics of the thoracic spine in trunk lateral bending with an intact rib cage and soft tissues has not been well documented. There is no quantitative data in the literature for lateral bending in consecutive thoracic spinal segments, and there has not been consensus on the patterns of coupled motion with lateral bending. PURPOSE: To demonstrate segmental ranges of motion (ROMs) in lateral bending and coupled motions of the thoracic spine. STUDY DESIGN: In vivo three-dimensional biomechanics study of the thoracic spine. PATIENT SAMPLE: Fifteen healthy male volunteers. OUTCOME MEASURES: Computed analysis by using voxel-based registration. METHODS: Participants underwent computed tomography of the thoracic spine in three supine positions: neutral, right maximum lateral bending, and left maximum lateral bending. The relative motions of vertebrae were calculated by automatically superimposing an image of vertebrae in a neutral position over images in bending positions, using voxel-based registration. Mean values of lateral bending were compared among the upper (T1-T2 to T3-T4), the middle-upper (T4-T5 to T6-T7), the middle-lower (T7-T8 to T9-T10), and the lower (T10-T11 to T12-L1) parts of the spine. RESULTS: At lateral bending, the mean ROM (±standard deviation) of T1 with respect to L1 was 15.6°±6.3° for lateral bending and 6.2°±4.8° for coupled axial rotation in the same direction as lateral bending. The mean lateral bending of each spinal segment with respect to the inferior adjacent vertebra was 1.4°±1.3° at T1-T2, 1.3°±1.2° at T2-T3, 1.4°±1.3° at T3-T4, 0.9°±0.9° at T4-T5, 0.8°±1.0° at T5-T6, 1.1°±1.1° at T6-T7, 1.7°±1.2° at T7-T8, 1.3°±1.2° at T8-T9, 1.6°±0.7° at T9-T10, 1.8°±0.8° at T10-T11, 2.3°±1.0° at T11-T12, and 2.2°±0.8° at T12-L1. The smallest and the largest amounts of lateral bending were observed in the middle-upper and the lower parts, respectively. There was no significant difference in lateral bending between the upper and the middle-lower parts. Coupled axial rotation of each segment was generally observed in the same direction as lateral bending. However, high variability was found at the T2-T3 to T5-T6 segments. Coupled flexion was observed at the upper and middle parts, and coupled extension was observed at the lower part. CONCLUSIONS: This study revealed in vivo three-dimensional motions of consecutive thoracic spinal segments in trunk lateral bending. The thoracolumbar segments significantly contributed to lateral bending. Coupled axial rotation generally occurred in the same direction with lateral bending. However, more variability was observed in the direction of coupled axial rotation at T2-T3 to T5-T6 segments in the supine position. These results are useful for understanding normal kinematics of the thoracic spine.

Kinematics of the thoracic spine in trunk rotation: in vivo 3-dimensional analysis.

STUDY DESIGN: In vivo 3-dimensional (3D) study of the thoracic spine. OBJECTIVE: To demonstrate axial rotations (ARs) and coupled motions of the thoracic spine. SUMMARY OF BACKGROUND DATA: In vivo 3D kinematics of the thoracic spine in trunk rotation with intact thorax and soft tissues has not been well-known.There were no quantitative data of AR in the consecutive thoracic spinal segments. Patterns of coupled motion with AR have been controversial. METHODS: Thirteen healthy volunteers underwent 3D computed tomography of the thoracic spine in 3 positions; neutral, right, and left maximum trunk rotation. Relative motions of vertebrae were calculated by automatically superimposing the vertebrae in a neutral position over images in rotational positions, using voxel-based registration. Motions were represented with 6 degrees of freedom by Euler angles and translations on the local coordinate system. RESULTS: Mean (± SD) relative rotational angles of T1 with respect to L1 to 1 side were 24.9° ± 4.9° in maximum trunk rotation. AR of each thoracic segment with respect to the inferior adjacent vertebra to 1 side was 1.2° ± 0.8° at T1-T2, 1.6° ± 0.7° at T2-T3, 1.4° ± 0.9° at T3-T4, 1.6° ± 0.8° at T4-T5, 1.8° ± 0.7° at T5-T6, 1.9° ± 0.6° at T6-T7, 2.3° ± 0.7° at T7-T8, 2.5° ± 0.8° at T8-T9, 2.7° ± 0.6° at T9-T10, 2.6° ± 0.8° at T10-T11, 1.3° ± 0.7° at T11-T12, and 0.5° ± 0.4° at T12-L1. Significantly larger segmental AR was observed at the middle thoracic segments (T6-T11) than at the upper (T1-T6) and lower (T11-L1) segments. At the upper thoracic segments, coupled lateral bending with AR was observed in the same direction as AR. However, at the middle and lower thoracic segments, coupled lateral bending occurred both in the same and opposite directions. CONCLUSION: In vivo 3D ARs and coupled motions of the consecutive thoracic spinal segments in trunk rotation were investigated accurately for the first time.