Hes1 marks peri-condensation mesenchymal cells that generate both chondrocytes and perichondrial cells in early bone development.

Bone development starts with condensations of undifferentiated mesenchymal cells that set a framework for future bones within the primordium. In the endochondral pathway, mesenchymal cells inside the condensation differentiate into chondrocytes and perichondrial cells in a SOX9-dependent mechanism. However, the identity of mesenchymal cells outside the condensation and how they participate in developing bones remain undefined. Here we show that mesenchymal cells surrounding the condensation contribute to both cartilage and perichondrium, robustly generating chondrocytes, osteoblasts, and marrow stromal cells in developing bones. Single-cell RNA-seq analysis of Prrx1-cre-marked limb bud mesenchymal cells at E11.5 reveals that Notch effector Hes1 is expressed in a mutually exclusive manner with Sox9 that is expressed in pre-cartilaginous condensations. Analysis of a Notch signaling reporter CBF1:H2B-Venus reveals that peri-condensation mesenchymal cells are active for Notch signaling. In vivo lineage-tracing analysis using Hes1-creER identifies that Hes1+ early mesenchymal cells surrounding the SOX9+ condensation at E10.5 contribute to both cartilage and perichondrium at E13.5, subsequently becoming growth plate chondrocytes, osteoblasts of trabecular and cortical bones, and marrow stromal cells in postnatal bones. In contrast, Hes1+ cells in the perichondrium at E12.5 or E14.5 do not generate chondrocytes within cartilage, contributing to osteoblasts and marrow stromal cells only through the perichondrial route. Therefore, Hes1+ peri-condensation mesenchymal cells give rise to cells of the skeletal lineage through cartilage-dependent and independent pathways, supporting the theory that early mesenchymal cells outside the condensation also play important roles in early bone development.

Association of spinal anomalies with spondylolysis and spina bifida occulta.

PURPOSE: To investigate the association of spinal anomalies with lumbar spondylolysis and spina bifida occulta (SBO). METHODS: A total of 1190 patients with thoracic, abdominal, and pelvic computed tomography scans available were categorized according to the number of presacral (thoracic and lumbar) mobile vertebrae and the presence or absence of lumbosacral transitional vertebrae (LSTV). The prevalence of spondylolysis and SBO and the association of spinal anomalies with these disorders were evaluated. RESULTS: Normal morphology (17 mobile vertebra with no LSTV) was found in 607 men (86.5%) and 419 women (85.9%) and about 14% of patients had anomalies. Spondylolysis was found in 74 patients (6.2%), comprising 54 men (7.7%) and 20 women (4.1%). SBO involving the lumbar spine was found in 9 men (1.3%) and 2 women (0.4%). Spondylolysis was significantly more common in men with 18 vertebrae without LSTV (21.1%) than in those with 17 vertebrae without LSTV (7.2%) (p = 0.002). The prevalence of spinal anomalies was 55.6% in men and 50.0% in women with SBO that included a lumbar level was significantly higher than in both men (13.5%, p < 0.001) and women (4.8%, p = 0.003) without SBO. CONCLUSION: These findings indicate that there is a relationship between spinal anomalies and both spondylolysis and SBO, which may lead to elucidation of the mechanism of onset of spondylolysis and improve its treatment and prognosis. Awareness that patients with SBO involving the lumbar spine have an increased likelihood of a spinal anomaly may help to prevent level errors during spinal surgery.

Role of growth plate (apophyseal ring fracture) in causing modic type changes in pediatric low back pain patients.

PURPOSE: We investigated the prevalence of Modic changes (MCs) and associated pathologies in pediatric patients. METHODS: A total of 368 MRI obtained for 240 male and 128 female patients under the age of 18 years with complaints of low back/leg pain were retrospectively examined. All changes in signal intensity in the vertebral endplate and subchondral bone on MRI were defined as MCs. We investigated the relationship between MCs and underlying diseases, including lumbar spondylolysis/spondylolisthesis, and conditions of the growth plate in cases with MCs. The degree of disc degeneration in patients with MCs was evaluated using the Pfirrmann grading system. RESULTS: MCs were identified in six patients (1.6%). In five of the six patients, the signal intensity changes were localized to the anterosuperior endplate of the affected vertebra; the MCs were associated with anterior apophyseal ring fracture and an open growth plate in all these cases. Disc degeneration was classified as Pfirrmann grade I in three patients and grade II and III in one patient each. One patient had type I changes associated with grade IV disc degeneration and herniation and no sign of an open growth plate. CONCLUSION: The prevalence of MCs in pediatrics patients was much lower than the rates reported in adults. Most MCs were associated with an anterior apophyseal ring fracture. If Modic type changes are seen in immature vertebrae of pediatric patients, growth plate lesions such as apophyseal ring fractures should be considered. LEVEL OF EVIDENCE: Diagnostic: individual l cross-sectional studies with consistently applied reference standard and blinding.

[Lumbar Interbody Fusion:How to Achieve Reliable Bone Fusion?]

The goal of surgery for degenerative spine disease is to decompress nerves; however, extensive spinal decompression may compromise spinal stability. Therefore, spinal fusion surgery is performed to immediately stabilize such anatomical disruption during a short hospital stay and to allow quick recuperation. Recently, implants such as pedicle screws and intervertebral cages have been regularly used in lumbar fusion surgery. These implants are used to reconstruct the functional unit of the failed spine, correcting any deformity if necessary and maintaining its fixation until complete bone fusion. In other words, the essence of spinal fusion surgery is not the placement of implants but the induction of bone fusion. Therefore, each case requires a carefully developed surgical plan to achieve sufficient bone fusion for spinal stabilization. In this article, we describe the mechanism and the surgical technique for achieving reliable interbody fusion.

Identification of abnormalities in the lumbar nerve tract using diffusion-weighted magnetic resonance neurography.

INTRODUCTION: Abnormalities of the lumbar nerve tract caused by congenital variations or high nerve root take-off angles are difficult to visualize. Diffusion-weighted magnetic resonance neurography (DW-MRN) has recently been introduced for imaging of the lumbosacral region. The aims of this study were to identify lumbar nerve tract abnormalities caused by congenital variation or a high nerve root take-off angle using DW-MRN and to assess the diagnostic value of this imaging modality. METHODS: A total of 573 magnetic resonance images from 575 patients (261 men, 314 women; mean age 58.5 years) with low back/leg pain were retrospectively analyzed. We classified congenital variations in the lumbar nerve roots using the Neidre and MacNab criteria and investigated nerve roots with a take-off angle of 60° or more. RESULTS AND DISCUSSION: Congenital variations were identified in 8 patients (9 nerve roots, 1.6%). The most commonly identified variation was in the sacral nerve root (n = 5) followed by the L4 (n = 3) and L5 (n = 1) nerve roots. All variations identified were on the left side. There were 3 cases of type 1a variation, 1 of type 1b, 1 of type 2, and 4 of type 3. In total, 210 (36.6%) of the magnetic resonance images showed high nerve root take-off angles at the intervertebral foramen that was caused by disk herniation, spondylolisthesis, or osteophytes with degeneration. Patients with high nerve root take-off angles were significantly older than those without (P < 0.05). These slides can be retrieved under Electronic Supplementary Material.

Age-related changes in axial and sagittal orientation of the facet joints: Comparison with changes in degenerative spondylolisthesis.

BACKGROUND: Despite facet joints being three-dimensional structures, previous computed tomography and magnetic resonance imaging studies have evaluated facet joint orientation in only the axial plane. Facet joint orientation in the sagittal plane has rarely been studied using these imaging techniques. The aim of this study was to elucidate facet joint orientation in both the axial and sagittal planes on computed tomography. METHODS: A total of 568 patients (343 men, 225 women) (excluding orthopedic outpatients) for whom abdominal and pelvic computed tomography scans were obtained at our hospital between September 2010 and October 2012 were included. Mean age was 63 (range 21-90) years. Patients were divided into a degenerative spondylolisthesis group (67 patients; 30 men, 37 women) and a control group (313 patients; 313 men, 188 women). Facet joint orientation was evaluated in the control group according to patient age (≤50, 51-60, 61-70, or ≥71 years). The findings in the control group were then compared with those in the degenerative spondylolisthesis group. The orientation of the lumbar facet joints at each level was measured in the axial and sagittal planes on computed tomography images. RESULTS: Facet joint angles decreased with age at L4/5 and L5/S1 in women in the axial plane and at L4/5 in men and L3/4 and L4/5 in women in the sagittal plane. The variation in facet joint angle was greatest at L4/5 in women. Patients with degenerative spondylolisthesis showed more sagittally and horizontally oriented facet joints in the axial and sagittal planes; facet tropism showed an association with degenerative spondylolisthesis in the axial plane. CONCLUSIONS: The axial and sagittal orientation of facet joints in the lower lumbar vertebra, especially L4/5, was negatively correlated with age. This finding could help to explain why older people are more prone to degenerative spondylolisthesis.

Surgery in the Standing Position by a Surgeon with Achilles Tendon Rupture.

Unexpected injuries can have a profound effect on a surgeon's performance and thus on patients and surgical departments. Here we describe a technique for performing surgery in the standing position, as done by a surgeon with an Achilles tendon rupture. During his prescribed 45-day non-weight-bearing period for the left ankle after surgery for an Achilles tendon rupture, the surgeon was able to participate in 15 surgeries as an operator or assistant, due to his use of a combination of injured-leg genuflection on a stool and a 'Surgical Body Support' device. Similarly injured surgeons may benefit from such support.

[Cervical spinal dural arteriovenous fistula with rapidly progressive brainstem dysfunction due to venous congestion: a case report].

Spinal dural arteriovenous fistulas(S-dAVFs)are rare vascular malformations of the spine. We experienced a case that presented with rapidly progressive brainstem dysfunction due to venous congestion of cervical dAVFs. A 56-year-old man diagnosed with cervical dAVF four years prior presented with gait disturbance and abnormal thermal nociception on his right side. In addition to the high-intensity lesion from the lower pons to the medulla oblongata on T2-weighted magnetic resonance imaging, diffusion-weighted imaging demonstrated cerebral infarction of the left ventrolateral medulla oblongata. Left vertebral angiography revealed that a feeding artery supplied by the radicular artery at the C4 level formed a fistula with the dilated ascending anterior perimedullary vein. We made a diagnosis of venous congestion due to cervical dAVFs. Numbness on the left upper limb occurred five days after the first symptom. Subsequently, hemiparesis on the left upper limb and swallowing disturbance occurred two weeks after the first symptom. The patient underwent surgical ligation of the dilated abnormal vein, with gradual improvement of his symptoms. Myelopathy due to venous congestion of S-dAVFs usually progresses slowly for several years. However, this case report warns about the possibility that some cases of S-dAVF with rapidly exacerbated symptoms may require prompt therapy.

Morphological Evaluation of Lumbar Facet Joints in Professional Baseball Players.

Background: Many professional baseball players experience low back pain, a major cause of which is lumbar facet joint arthropathy. Purpose: To evaluate the relationship between the dominant hand side and facet joint morphology in baseball movement. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Participants were 25 Japanese professional baseball players (11 pitchers and 14 fielders) with low back pain and lower limb symptoms. Player age, hand dominance, and length of professional playing experience were recorded, and the lateral diameter of all lumbar facet joints was determined from the axial computed tomography scans. We defined the facet joints ipsilateral and contralateral to the dominant hand as dominant and nondominant, respectively. The nondominant-to-dominant (N/D) ratio of the lateral diameter was calculated, and differences between the pitchers and fielders were analyzed using the unpaired t test. Results: The average player age and length of professional playing experience were 26.9 years (range, 19-37 years) and 7.2 years (range, 1-15 years), respectively. The right hand was dominant in 9 pitchers and 5 fielders, while the left hand was dominant in 2 pitchers and 9 fielders. In pitchers, the average lateral facet joint diameter on the nondominant side was significantly larger than on the dominant side at all vertebral levels except L1 to L2 (P < .05 for all). The N/D ratio for each facet joint was 1.06 (L1-L2), 1.11 (L2-L3), 1.10 (L3-L4), 1.12 (L4-L5), and 1.12 (L5-S1). In fielders, the average lateral facet joint diameter on the dominant side was significantly larger than on the nondominant side at L3 to L4 (P < .05), with N/D ratios of 0.98 (L1-L2), 0.96 (L2-L3), 0.94 (L3-L4), 0.97 (L4-L5), and 0.98 (L5-S1). The N/D ratio was significantly larger in pitchers than in fielders at all levels (P < .05 for all). Conclusion: The facet joints of professional baseball players were enlarged asymmetrically, with different tendencies observed between pitchers and fielders. Although pitching and batting are movements that transmit the rotation from the lower limbs to the upper limbs, the effects of rotation and lateral flexion were associated significantly with facet joint hypertrophy.

Robotic-assisted minimally invasive repair surgery for progressive spondylolysis in a young athlete: a technical note.

Presently, the invasiveness of direct repair surgery for lumbar spondylolysis is relatively high. Thus, high school and junior high school students who play sports often cannot return to sports before graduation because of the invasiveness. The use of a robotic system enabled an accurate and minimally invasive procedure. Robotic-assisted minimally invasive direct pars repair surgery is useful for young patients with progressive spondylolysis.

Hedgehog activation promotes osteogenic fates of growth plate resting zone chondrocytes through transient clonal competency.

The resting zone of the postnatal growth plate is organized by slow-cycling chondrocytes expressing parathyroid hormone-related protein (PTHrP), which include a subgroup of skeletal stem cells that contribute to the formation of columnar chondrocytes. The PTHrP-Indian hedgehog feedback regulation is essential for sustaining growth plate activities; however, molecular mechanisms regulating cell fates of PTHrP+ resting chondrocytes and their eventual transformation into osteoblasts remain largely undefined. Here, in a mouse model, we specifically activated Hedgehog signaling in PTHrP+ resting chondrocytes and traced the fate of their descendants using a tamoxifen-inducible Pthrp-creER line with patched-1-floxed and tdTomato reporter alleles. Hedgehog-activated PTHrP+ chondrocytes formed large, concentric, clonally expanded cell populations within the resting zone ("patched roses") and generated significantly wider columns of chondrocytes, resulting in hyperplasia of the growth plate. Interestingly, Hedgehog-activated PTHrP+ cell descendants migrated away from the growth plate and transformed into trabecular osteoblasts in the diaphyseal marrow space in the long term. Therefore, Hedgehog activation drives resting zone chondrocytes into transit-amplifying states as proliferating chondrocytes and eventually converts these cells into osteoblasts, unraveling a potentially novel Hedgehog-mediated mechanism that facilitates osteogenic cell fates of PTHrP+ skeletal stem cells.

Prospective Registration Study for Establishing Minimal Clinically Important Differences in Patients Undergoing Surgery for Spinal Metastases.

STUDY DESIGN: Multicenter, prospective registry study. OBJECTIVE: To clarify minimal clinically important differences (MCIDs) for surgical interventions for spinal metastases, thereby enhancing patient care by integrating quality of life (QoL) assessments with clinical outcomes. SUMMARY OF BACKGROUND DATA: Despite its proven usefulness in degenerative spinal diseases and deformities, the MCID remains unexplored regarding surgery for spinal metastases. METHODS: This study included 171 (out of 413) patients from the multicenter "Prospective Registration Study on Surgery for Metastatic Spinal Tumors" by the Japan Association of Spine Surgeons. These were evaluated preoperatively and at 6 months postoperatively using the Face scale, EuroQol-5 Dimensions-5 Levels (EQ-5D-5L), including the visual analog scale (VAS), and performance status. The MCIDs were calculated using an anchor-based method, classifying participants into the improved, unchanged, and deteriorated groups based on the Face scale scores. Focusing on the improved and unchanged groups, the change in the EQ-5D-5L values from before to after treatment was analyzed, and the cutoff value with the highest sensitivity and specificity was determined as the MCID through receiver operating characteristic curve analysis. The validity of the MCIDs was evaluated using a distribution-based calculation method for patient-reported outcomes. RESULTS: The improved, unchanged, and deteriorated groups comprised 121, 28, and 22 participants, respectively. The anchor-based MCIDs for the EQ-5D-5L index, EQ-VAS, and domains of mobility, self-care, usual activities, pain/discomfort, and anxiety/depression were 0.21, 15.50, 1.50, 0.50, 0.50, 0.50, and 0.50, respectively; the corresponding distribution-based MCIDs were 0.17, 15,99, 0.77, 0.80, 0.78, 0.60, and 0.70, respectively. CONCLUSION: We identified MCIDs for surgical treatment of spinal metastases, providing benchmarks for future clinical research. By retrospectively examining whether the MCIDs are achieved, factors favoring their achievement and risks affecting them can be explored. This could aid in decisions on surgical candidacy and patient counseling.

Proximal vertebral body fracture after 4-level fusion using l1 as the upper instrumented vertebra for lumbar degenerative disease: report of 2 cases with literature review.

Some cases with lumbar degenerative diseases require multi-level fusion surgeries. At our institute, 27 and 4 procedures of 3- and 4-level fusion were performed out of a total 672 posterior lumbar interfusions (PLIFs) on patients with lumbar degenerative disease from 2005 to 2010. We present 2 osteoporotic patients who developed proximal vertebral body fracture after 4-level fusion. Both cases presented with gait disability for leg pain by degenerative lumbar scoliosis and canal stenosis at the levels of L1/2-4/5. After 4-level fusion using L1 as the upper instrumented vertebra, proximal vertebral body fractures were found along with the right pedicle fractures of L1 in both cases. One of these patients, aged 82 years, was treated as an outpatient using a hard corset for 24 months, but the fractures were exacerbated over time. In the other patient, posterolateral fusion was extended from Th10 to L5. Both patients can walk alone and have been thoroughly followed up. In both cases, the fracture of the right L1 pedicle might be related to the subsequent fractures and fusion failure. In consideration of multi-level fusion, L1 should be avoided as an upper instrumented vertebra to prevent junctional kyphosis, especially in cases with osteoporosis and flat back posture.

[A case of a paraspinal arteriovenous fistula presenting with retroperitoneal hemorrhage treated by staged transarterial and transvenous embolization].

We report a rare case of a paraspinal arteriovenous fistula(AVF)treated by combined transarterial and transvenous embolization(TAE/TVE). A 72-year-old woman was admitted after a traffic accident. Abdominal enhanced CT disclosed pre-existing large varices at the L3-L4 level in the right retroperitoneum with multiple feeding arteries and veins draining into the extradural venous plexus in the spinal canal. The lesion was diagnosed as a paraspinal AVF. Four days later, the patient went into a state of shock. Emergency abdominal CT showed retroperitoneal hemorrhage due to rupture of the varix. TAE of the feeders from the right L1-L4 arteries was performed, and rebleeding from the varix was prevented. Three months later, follow-up CTA showed regrowth of the AVF, and TVE was performed. Two microcatheters were navigated transvenously into the varix, and detachable coils were delivered into the small compartment just downstream to the shunts, leading to complete obliteration. We conclude that transarterial flow reduction followed by occlusion of the venous side of the shunts is effective to achieve cure of a complex and high-flow paraspinal AVF.

Facet Joint Morphology and Tropism in Adolescents: Association with Lumbar Disc Herniation and Spondylolysis.

STUDY DESIGN: Cross-sectional, observational. OBJECTIVE: To investigate the incidence of bidirectional lumbar facet tropism and its relationship with lumbar spine disease in adolescents. SUMMARY OF BACKGROUND DATA: There is limited information on facet joint asymmetry in the sagittal plane in adolescents. MATERIALS AND METHODS: The orientation of all lumbar facet joints was measured in the bidirectional planes on computed tomographic images for 191 patients with low back pain. The patients were divided into four groups according to age (<15 or ≥15 y) and sex. The facet joint angle and tropism rate were compared among the groups. Facet tropism was defined as a difference in bilateral angle of >10° in the axial plane and >5° in the sagittal plane. Facet joint orientation was compared among groups using one-way analysis of variance and Tukey's honestly significant difference test or Games-Howell post hoc test and the incidence of facet tropism using the Kruskal-Wallis test with Bonferroni correction. The association of facet tropism with disease was investigated further by analyzing facet joint orientation and the incidence of facet tropism in 116 patients with single-level lumbar disease. RESULTS: Facet tropism was observed in 8.7% of axial views and 7.5% of sagittal views. The incidence of axial facet tropism was significantly higher in male patients aged ≥15 years, especially at L4/5. Facet joint morphology in the axial plane was more coronal at L3/4 and L4/5 in male patients ≥15 years than in those <15 years. Facet joint morphology in the sagittal plane was unchanged at around 15 years of age in both sexes. Axial facet tropism was found at L4/5 in 55.6% of patients with herniated nucleus pulposus. There was a significant difference in sagittal facet orientation in patients with spondylolysis at L5. The facet angle was significant larger in patients with L5 spondylolysis at L3/4 and L4/5. CONCLUSION: Facet tropism in adolescents is similar in the axial and sagittal planes. Facet tropism and specific morphology may be related to lumbar disc herniation and spondylolysis in this age group.

Clinical Outcome of Full Endoscopic Trans Kambin's Triangle Lumbar Interbody Fusion: A Systematic Review.

Full-endoscopic (FE) lumbar interbody fusion (LIF) is now a widely used type of minimally invasive surgery (MIS). Although FE-LIF includes LIF with foraminoplasty via a Kambin's triangle approach (FE-KLIF) and LIF with foraminotomy via an interlaminar approach, these techniques are rarely discussed separately. This review evaluates the outcomes and complications of FE-KLIF reported in the literature. The PubMed, Medline, Embase, Web of Science, and Cochrane Library databases were searched for studies reporting the outcomes of FE-KLIF. Of 464 publications assessed, 11 met our inclusion criteria. Although the most frequently treated level was L4/5, L5/S1 was also treated. FE-KLIF was performed under local anesthesia and sedation or under epidural anesthesia without general anesthesia. Visual analog scale and Oswestry Disability Index scores were improved postoperatively in all uncontrolled studies; however, there was no significant difference in these scores in studies that compared FE-KLIF with posterior LIF (PLIF) or MIS-transforaminal LIF (TLIF). There was also no significant difference in the fusion rate between FE-KLIF and PLIF or MIS-TLIF. In terms of complications, although there were no reports of hematoma, dural tear and surgical site infection were reported in 1 paper each, with transient nerve disorders reported in 5 studies (frequency, 1.8%-23.5%). This review indicates that FE-KLIF is a feasible and viable surgical option for lumbar degenerative disease. However, the amount and level of evidence is low for the studies included in this review, and the data on long-term outcomes remain limited.

Advantages of Full-endoscopic Trans-Kambin's Triangle Lumbar Interbody Fusion for Degenerative Spondylolisthesis: Illustrative Cases.

Various approaches to lumbar interbody fusion have been described. The usefulness of full-endoscopic trans-Kambin's triangle lumbar interbody fusion has recently been reported. This technique has several advantages in patients with degenerative spondylolisthesis, including the ability to improve symptoms without decompression surgery. Moreover, given that the entire procedure is performed percutaneously, it can be performed without increasing the operation time or surgical invasiveness, even in obese patients. In this article, we discuss these advantages and illustrate them with representative cases.

Successful treatment of intractable pseudomeningocele with FXIII deficiency by surgery and FXIII replacement therapy: A case report.

Pseudomeningocele is an extradural cystic collection of cerebrospinal fluid (CSF) and is rare and typically asymptomatic. However, pseudomeningocele is sometimes associated with symptoms. Whether symptomatic pseudomeningocele is best treated conservatively or surgically remains controversial. Factor XIII (FXIII) is a blood coagulation factor that also promotes fibroblast proliferation during wound healing. Although treatment of postsurgical CSF leakage with FXIII has been reported, there have been no reports on surgical treatment and FXIII replacement therapy of pseudomeningocele with FXIII deficiency. We report a case of pseudomeningocele with FXIII deficiency that was successfully treated by surgery and FXIII replacement therapy. The patient presented with symptoms of intracranial hypotension syndrome that had started a few months after laminectomy for thoracic ossification of the ligamentum flavum 2 years earlier. Magnetic resonance imaging and delayed computed tomography myelography confirmed a diagnosis of pseudomeningocele. Epidural blood patch treatment was performed twice but did not result in improvement. Furthermore, the FXIII level decreased to 56%, so the patient was also diagnosed as having acquired FXIII deficiency. We elected to treat the patient by surgery with FXIII replacement therapy. The dural injury was repaired using an artificial dura mater patch, fibrin glue, and polyglycolic acid sheets. The FXIII level was 74%-135% during the perioperative period. The patient had a good postoperative course. Postoperative magnetic resonance images showed resolution of the pseudomeningocele. There was no recurrence during 6 months of follow-up. Perioperative FXIII replacement may be a useful treatment for pseudomeningocele with FXIII deficiency.

Low Back Pain and Lumbar Degeneration in Japanese Professional Baseball Players.

Background: Baseball is one of the most popular sports in Asia. It is known that baseball can easily lead to back pain. However, there has been no survey of low back pain (LBP) and lumbar disc degeneration in Japanese professional baseball players to date. Purpose: To investigate the cause of LBP and lumbar degeneration in professional Japanese baseball players. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively reviewed the medical records of Japanese professional baseball players with LBP who visited our hospital. Data were collected from July 2018 to April 2021. We also investigated whether the results differed between players in their 20s and 30s or between pitchers and fielders. Data analysis was performed using the chi-square test. Results: We surveyed 32 professional baseball players. The most frequent causes of LBP among players in their 20s (n = 21) were lumbar disc herniation (LDH; 57%) and spondylolysis (24%). Of the players with spondylolysis, 50% had adult-onset spondylolysis. Players in their 30s (n = 11) most commonly had discogenic pain (55%) as well as LDH and facet joint arthritis (each 18%). The incidence of lumbar intervertebral disc degeneration was significantly higher in players in their 30s (91%) than those in their 20s (14%), as was the incidence of Schmorl nodes and Modic type 1 changes. There was no significant difference in the cause of LBP or the incidence of lumbar intervertebral disc degeneration between pitchers and fielders (P = .59). Conclusion: Among professional baseball players in their 20s, lumbar degeneration was less common, and they most frequently developed diseases less related to degeneration, such as LDH. However, among players in their 30s, lumbar degeneration was more advanced, and degenerative diseases such as discogenic pain occurred more frequently. Research on training methods could lead to the prevention of LBP. Our data may be applicable to other professional athletes and will contribute to diagnosis and treatment.

Comparison between O-arm Navigation and Conventional Fluoroscopic Guidance in Corrective Posterior Fixation for Cervical Spinal Injury.

Purpose : To compare the effectiveness of O-arm navigation with that of conventional fluoroscopic guidance in corrective posterior fixation for cervical spinal injury. Methods : This retrospective comparative study involved 11 consecutive patients who underwent corrective posterior fixation using O-arm navigation or conventional fluoroscopy for cervical spinal injury between February 2016 and May 2021. Patient-specific characteristics (age and sex), number of screws, number of pedicle screws, accuracy of pedicle screw insertion, number of vertebral bodies fixed, operating time, and length of hospital stay were analyzed using the t-test. A P-value < 0.05 was considered statistically significant. Results : Corrective posterior fixation was performed under O-arm navigation in 5 patients and under conventional fluoroscopic guidance in 6. A significantly greater number of pedicle screws was used in the O-arm group (6.4 vs 2.7, P = 0.046). According to the Neo classification for pedicle screw placement, there were no grade 2 or 3 breaches. No other items showed a significant difference between the groups (P > 0.05). Conclusion : O-arm navigation can improve the accuracy of cervical pedicle screw insertion. Its introduction could expand the indications for use of pedicle screws in posterior fixation of cervical spinal injury beyond those that are possible using conventional fluoroscopy. J. Med. Invest. 69 : 273-277, August, 2022.