Metformin mitigates adipogenesis of fibro-adipogenic progenitors after rotator cuff tears via activating mTOR/ULK1-mediated autophagy.

Muscular fatty infiltration is a common issue after rotator cuff tears (RCTs), which impair shoulder function. Females suffer a higher prevalence and a more severe degree of muscular fatty infiltration after RCT when compared with males, with the underlying mechanisms remaining unclear. Fibro-adipogenic progenitors (FAPs) are the primary source of muscular fatty infiltration following RCT. Our findings disclose that gender-specific disparities in muscular fatty infiltration are linked to mTOR/ULK1-mediated autophagy of FAPs. Decreased autophagic activity contributes to adipogenic differentiation in female FAPs after RCT. Furthermore, metformin could enhance mTOR/ULK1-mediated autophagic processes of FAPs, thereby alleviating fatty infiltration and improving shoulder functionality after RCT. Together, our study reveals that gender differences in muscular fatty infiltration arise from distinct autophagic activities. Metformin could be a promising noninvasive intervention to ameliorate muscular fatty infiltration of RCT.NEW & NOTEWORTHY The current study demonstrated that gender-specific disparities in muscular fatty infiltration are attributed to mTOR/ULK1-mediated autophagy of FAPs. Decreased autophagic activity contributes to adipogenic differentiation in female FAPs after RCT. Moreover, metformin could enhance mTOR/ULK1-mediated autophagic processes of FAPs, thereby alleviating fatty infiltration and improving shoulder functionality after RCT. Therefore, metformin could be a promising noninvasive intervention to ameliorate muscular fatty infiltration of RCT.

In Vivo Analysis of Acromioclavicular Kinematics and Distance During Multiplanar Humeral Elevation.

BACKGROUND: Knowledge of acromioclavicular (AC) joint kinematics and distance may provide insight into the biomechanical function and development of new treatment methods. However, accurate data on in vivo AC kinematics and distance between the clavicle and acromion remain unknown. PURPOSE/HYPOTHESIS: The purpose of this study was to investigate 3-dimensional AC kinematics and distance during arm elevation in abduction, scaption, and forward flexion in a healthy population. It was hypothesized that AC kinematics and distance would vary with the elevation angle and plane of the arm. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 19 shoulders of healthy participants were enrolled. AC kinematics and distance were investigated with a combined dual fluoroscopic imaging system and computed tomography. Rotation and translation of the AC joint were calculated. The AC distance was measured as the minimum distance between the medial border of the acromion and the articular surface of the distal clavicle (ASDC). The minimum distance point (MDP) ratio was defined as the length between the MDP and the posterior edge of the ASDC divided by the anterior-posterior length of the ASDC. AC kinematics and distance between different elevation planes and angles were compared. RESULTS: Progressive internal rotation, upward rotation, and posterior tilt of the AC joint were observed in all elevation planes. The scapula rotated more upward relative to the clavicle in abduction than in scaption (P = .002) and flexion (P = .005). The arm elevation angle significantly affected translation of the AC joint. The acromion translated more laterally and more posteriorly in scaption than in abduction (P < .001). The AC distance decreased from the initial position to 75° in all planes and was significantly greater in flexion (P < .001). The MDP ratio significantly increased with the elevation angle (P < .001). CONCLUSION: Progressive rotation and significant translation of the AC joint were observed in different elevation planes. The AC distance decreased with the elevation angle from the initial position to 75°. The minimum distance between the ASDC and the medial border of the acromion moved anteriorly as the shoulder elevation angle increased. CLINICAL RELEVANCE: These results could serve as benchmark data for future studies aiming to improve the surgical treatment of AC joint abnormalities to restore optimal function.

Suppressed Akt/GSK-3ß/ß-catenin signaling contributes to excessive adipogenesis of fibro-adipogenic progenitors after rotator cuff tears.

Muscular fatty infiltration is a common and troublesome pathology after rotator cuff tears (RCT), which mainly derives from fibro-adipogenic progenitors (FAPs). Compared to the RCT, fatty infiltration is not so severe in Achilles tendon tears (ATT). The knowledge of why fatty infiltration is more likely to occur after RCT is limited. In this study, more severe fatty infiltration was verified in supraspinatus than gastrocnemius muscles after tendon injury. Additionally, we revealed higher adipogenic differentiation ability of RCT-FAPs in vitro. Activation of Akt significantly stimulated GSK-3ß/ß-catenin signaling and thus decreased PPARγ expression and adipogenesis of RCT-FAPs, while the inhibition effect was attenuated by ß-catenin inhibitor. Furthermore, Wnt signaling activator BML-284 limited adipogenesis of RCT-FAPs, alleviated muscular fatty infiltration, and improved parameters in gait analysis and treadmill test for RCT model. In conclusion, our study demonstrated that suppressed Akt/GSK-3ß/ß-catenin signaling increased PPARγ expression and thus contributed to excessive adipogenesis in RCT-FAPs. Modulation of Akt/GSK-3ß/ß-catenin signaling ameliorated excessive fatty infiltration of rotator cuff muscles and improved shoulder function after RCT.

Type 3 bone-disc-bone osteotomy (grade 4+ osteotomy) combined with presurgical halo-pelvic traction: a safe and effective solution to correct severe angular-like kyphoscoliosis.

Background: Treatment of severe angular-like kyphoscoliosis is a technically demanding surgical challenge and requires high-risk spinal osteotomy, such as vertebral column resection. Preoperative halo-pelvic traction is commonly used to decrease the curve magnitude. However, few studies have utilized the potent method of bone-disc-bone osteotomy, which could theoretically provide correction up to 60°. This study aimed to evaluate the safety and effectiveness of type 3 bone-disc-bone osteotomy combined with presurgical halo-pelvic traction to correct severe angular-like kyphoscoliosis. Methods: This was a retrospective cohort study. Patients with severe angular-like kyphoscoliosis who underwent presurgical halo-pelvic traction and type 3 bone-disc-bone osteotomy from January 2017 to December 2019 were consecutively reviewed. Patient demographics and clinical data were recorded. The coronal and sagittal Cobb angles were measured preoperation, post-traction, post-operation, and at the final follow-up. Complications were also recorded. Patients' health-related quality of life was evaluated by the Scoliosis Research Society 22 (SRS-22) questionnaire. Paired Student's t test and one-way analysis of variance were used for comparisons among different groups. Results: Thirty patients (18 females and 12 males) with an average age of 20.2 years (range, 13-33 years) were included. The mean preoperative coronal and sagittal Cobb angles were 123.1°±16.4° (range, 90°-155°) and 120.3°±19.9° (range, 90°-156°), respectively. After 2.9±0.7 months (range, 2-4 months) of halo-pelvic traction, the coronal and sagittal Cobb angles decreased significantly to 81.9°±13.2° and 76.0°±12.6°, respectively. Postoperatively, the scoliotic and kyphotic angles further decreased to 42.4°±12.2° and 33.9°±8.8°, respectively. After a mean follow-up of 2.93±1.05 years, the correction rates were maintained at 64.3%±10.6% and 70.5%±6.3%, respectively. Nine patients experienced positive evoked potential events during surgery. Common complications after surgery included transient lower extremity weakness, pneumonia, and pleural effusion. The self-image scores were significantly improved from 2.66±0.27 to 3.36±0.23 compared to preoperation. Conclusions: This study proposes a novel strategy to correct severe angular-like spinal deformities. The combination of presurgical halo-pelvic traction and type 3 bone-disc-bone osteotomy (grade 4+ osteotomy) achieves substantial correction and satisfactory aesthetic outcomes without serious complications.

The asymmetrical ESR1 signaling in muscle progenitor cells determines the progression of adolescent idiopathic scoliosis.

Adolescent Idiopathic Scoliosis (AIS) is a common pediatric skeletal disease highly occurred in females. The pathogenesis of AIS has not been fully elucidated. Here, we reveal that ESR1 (Estrogen Receptor 1) expression declines in muscle stem/progenitor cells at the concave side of AIS patients. Furthermore, ESR1 is required for muscle stem/progenitor cell differentiation and disrupted ESR1 signaling leads to differentiation defects. The imbalance of ESR1 signaling in the para-spinal muscles induces scoliosis in mice, while reactivation of ESR1 signaling at the concave side by an FDA approved drug Raloxifene alleviates the curve progression. This work reveals that the asymmetric inactivation of ESR1 signaling is one of the causes of AIS. Reactivation of ESR1 signaling in para-spinal muscle by Raloxifene at the concave side could be a new strategy to treat AIS.

Human Muscle-Derived Cells Are Capable of Tenogenic Differentiation and Contribution to Tendon Repair.

BACKGROUND: It has been reported that the harvested hamstring tendon for autograft could be regenerated with well-oriented fibers and uniformly distributed spindle-shaped cells after removal. However, which cell type might participate in the repair process remains unknown. PURPOSE: To investigate the tenogenic differentiation potential of human muscle-derived cells (MDCs) both in vitro and in vivo. STUDY DESIGN: Controlled laboratory study. METHODS: Primary human MDCs and tenocytes were isolated from discarded materials during a peroneus longus tendon-harvesting procedure. Expression of tenogenic genes were evaluated and compared among MDCs, MDCs with tenogenic induction, and tenocytes. RNA sequencing was performed to evaluate the expression profile of differentiated MDCs. Human MDCs were implanted in a tendon injury model to investigate the in vivo tenogenic differentiation potential. Histologic and functional analyses were performed to evaluate the function of MDCs for tendon repair. RESULTS: The relative expression levels (in fold change) of tenogenic genes Col I, MKX, SCX, THBS4, and TNC in MDCs were significantly upregulated 11.5 ± 1.3, 957.1 ± 63.7, 19.1 ± 2.8, 61.9 ± 4.8, and 10.2 ± 2.8 after tenogenic induction, respectively. The expression profile of tenogenically differentiated MDCs was much closer to primary tenocytes. Activation of TGF-ß/Smad3 signaling significantly promoted the tenogenic differentiation ability of MDCs. Transplanted human MDCs were identified in regenerated tendon and expressed tenogenic genes. As for biomechanical properties, the failure loads in the Matrigel, transplantation, and uninjured groups were 7.2 ± 0.5, 11.6 ± 0.3, and 13.9 ± 0.7 N, while the stiffness values were 4.4 ± 1.3 × 103, 7.6 ± 0.8 × 103, and 10.9 ± 1.1 × 103 N/m. Plantarflexion force, histologic morphology, and motor function were also significantly improved after MDC transplantation in a tendon injury model. CONCLUSION: There exist cells with tenogenic differentiation potential in human skeletal muscles. Activation of TGF-ß/Smad3 signaling plays an important role in tenogenic differentiation for human MDCs. Human MDCs contribute to structural and functional repair for the injured tendon. MDCs are a potential cell source to participate in the repair process after tendon injury. CLINICAL RELEVANCE: The MDCs could be a promising cell source to repair tendon injury.

How to select the lowest instrumented vertebra in NF-1 non-dystrophic scoliosis.

PURPOSE: To investigate lowest instrumented vertebra (LIV) selection strategy for neurofibromatosis type 1 (NF-1) non-dystrophic scoliosis. METHODS: Consecutive eligible subjects with NF-1 non-dystrophic scoliosis were included. All patients were followed up at least for 24 months. Enrolled patients with LIV in stable vertebra were divided into stable vertebra group (SV group), and the other patients with LIV above the stable vertebra were divided into above stable vertebra group (ASV group). Demographic data, operative data, preoperative and postoperative radiographic data, and clinical outcome were collected and analyzed. RESULTS: There were 14 patients in SV group (ten males and four females, mean age 13.9 ± 4.1 years) and 14 patients in ASV group (nine males and five females, mean age 12.9 ± 3.5 years). The mean follow-up period was 31.7 ± 17.4 months for patients in SV group and 33.6 ± 17.4 months for patients in ASV group, respectively. No significant differences were found in demographic data between two groups. The coronal Cobb angle, C7-CSVL, AVT, LIVDA, LIV tilt and SRS-22 questionnaire outcome significantly improved at the final follow-up in both groups. However, significantly higher loss of correction rate and increasement of LIVDA were found in ASV group. Two patients (14.3%) in ASV group but none in SV group suffered adding-on phenomenon. CONCLUSIONS: Although patients in both SV and ASV groups obtained improved therapeutic efficacy at final follow-up, the radiographic and clinical outcome seemed more likely to deteriorate in ASV group after surgery. The stable vertebra should be recommended as LIV for NF-1 non-dystrophic scoliosis.

Intensive bracing management combined with physiotherapeutic scoliosis-specific exercises for adolescent idiopathic scoliosis patients with a major curve ranging from 40-60° who refused surgery: a prospective cohort study.

BACKGROUND: Current guidelines for brace management of adolescent idiopathic scoliosis (AIS) are mostly recommended for curves between 25° to 40°. For AIS patients with curves >40°, surgery is often considered since bracing may be less effective; however, there are still some patients and families who refuse operation. Therefore, further research is necessary to determine optimal bracing management in this group. To date, few protocols for such have been reported in literature. AIM: The aim of this study was to introduce and evaluate the effectiveness of the treatment protocol comprising of intensive bracing management and physiotherapeutic scoliosis-specific exercises (PSSE) in AIS patients with a major curve of 40-60° who refuse surgery. DESIGN: This is a prospective cohort study. SETTING: The study was carried out in an outpatient clinic. POPULATION: 10-18-year-old AIS patients having 40-60°curves and a Risser grade of 0-3, but firmly refusing surgery were eligible. Patients who had a proximal thoracic curve or had undergone any other form of treatment previously were excluded from the study. METHODS: A total of 82 patients were recruited and received the treatment. The primary outcome was defined as "success" when the main curve was below 50° upon reaching skeletal maturity, and "failure" if otherwise. The secondary outcome was defined as improved (>5° reduction), unchanged (≤5° change) or progressed (>5° increase) based on the evolution of the main curve. The per protocol (PP) and intent to treat (ITT) analyses were performed to quantify success rates, while the dropouts were considered as failures. Risk factors associated with bracing failure were identified and a receiver operating characteristic (ROC) curve was used to determine the cut-off value. RESULTS: A total of 77 patients completed the treatment, while 5 dropped out. The average main curve was 47.40±5.93° at baseline and 38.56±11.85° at last follow-up (P<0.001). Our management was successful in 83% and 78% of patients based on the PP and ITT analyses, respectively. When compared with the curve magnitude at baseline, 65% patients improved, 30% remained unchanged, and 5% progressed when using a 5° threshold. Univariate comparison and logistic regression analysis demonstrated that patients with successful outcomes had a significantly smaller baseline curve, larger Risser Stage, and larger in-brace correction (IBC) rate. CONCLUSIONS: For AIS patients with 40-60° curves who refused surgery, our intensive bracing management along with PSSE was practical and effective, achieving success in 78% of patients based on an ITT analysis. A larger baseline curve, smaller Risser Stage, and smaller IBC rate were associated with treatment failure. CLINICAL REHABILITATION IMPACT: Our intensive management provides new insights into improving the effectiveness of bracing in patients with AIS who refuse surgery. This is a promising option for patients with 40-60° curves, since their scoliosis may be treated using a non-surgical technique instead of surgery in the future.

Arthroscopic repair of degenerative medial meniscus tears in patients aged over 45 years resulted in favorable clinical outcomes and low clinical failure rates at a minimum 2-year follow-up.

PURPOSE: This study aimed to investigate clinical and radiological results of arthroscopic repair for isolated medial degenerative meniscus tears (DMTs) in patients over 45 years old at a minimum 2-year follow-up. METHODS: From 2013 to 2017, patients aged over 45 years with isolated medial DMT refractory to conservative management or with true mechanical symptoms who had undergone arthroscopic repair were retrospectively reviewed. Arthroscopic meniscus repair was performed using all-inside or all-inside and inside-out technique in combination with bone marrow venting procedure. Tear patterns were classified according to arthroscopic findings. Magnetic resonance imaging (MRI) and outcome evaluations, including Lysholm score, Tegner activity score, and International Knee Documentation Committee (IKDC) score, were evaluated preoperatively and at the final follow-up. International Cartilage Repair Society grades of the medial compartments and MRI signal at tear sites were assessed preoperatively and at the final follow-up. A grade 0 to 2 signal at the repair site suggested a healed meniscus, whereas a grade 3 signal suggested an unhealed meniscus. Clinical failure was determined according to Barrett criteria. RESULTS: Twenty-seven patients (mean age, 57.7 ± 7.4 years) were enrolled. The mean follow-up was 52.0 ± 15.6 months. Among tear patterns, 48% were complex tears, 30% were horizontal tears, and 22% were other patterns. The mean Lysholm score and IKDC score significantly improved from 53 ± 25 to 89 ± 15 (p < 0.001) and 34 ± 24 to 72 ± 15 (p < 0.001) at the final follow-up, respectively. The median Tegner activity score significantly improved from 1 (range 1-4) to 4 (range 2-7, p < 0.001). Three (11%) patients were considered clinical failures, and five patients (19%) had cartilage lesion progression. At the final follow-up, MRI showed grade 0 in one (4%) patient, grade 1 in nine (33%) patients, grade 2 in six (22%) patients, and grade 3 in eleven (41%) patients. CONCLUSION: Arthroscopic repair of isolated medial DMT refractory to conservative management or with true mechanical symptoms in patients aged over 45 years had good to excellent clinical outcomes with low clinical failure rates, despite unhealed menisci being observed on MRI in 41% of patients at a mean 4.3-year follow-up. Arthroscopic repair could be a treatment option for these patients. LEVEL OF EVIDENCE: IV.

How to select the lowest instrumented vertebra in Lenke 5/6 adolescent idiopathic scoliosis patients with derotation technique.

PURPOSE: To introduce and evaluate our lowest instrumented vertebra (LIV) selection criteria for Lenke type 5/6 adolescent idiopathic scoliosis (AIS) patients with de-rotation technique. METHODS: There were 53 eligible Lenke 5/6 AIS patients with minimum 2-year follow-up enrolled in current study. The LIV selection criteria were: (1) the first vertebra touching the central sacral vertical line (CSVL) or the most cephalad vertebra which can return to stable zone under lateral bending position; (2) vertebral rotation no more than grade II by Nash-Moe rotation evaluation; (3) the lowest instrumented vertebra disc angle (LIVDA) could be reversed on lateral bending position. Demographic data, operation data and radiographic data were obtained and analyzed. RESULTS: Both clinical evaluation and radiographic data showed satisfactory outcome. The thoracolumbar/lumbar curve was improved from 53.4 ± 11.0° preoperatively to 6.9 ± 2.6° at the final follow-up. Two patients (3.8%) with adding on and two patients (3.8%) with coronal decompensation were identified at the final follow-up. LIV translation, LIV tilt and LIV disc angle were gradually improved after operation. The preoperative LIV tilt was positively correlated with Cobb angle (p = 0.010) and AVT (p = 0.030) at the final follow-up, and preoperative LIVDA was positively correlated with Cobb angle (p = 0.033) at the final follow-up. CONCLUSION: In Lenke 5/6 scoliosis, the current LIV selection criteria with de-rotation technique contribute to satisfactory correction rate of 87.1% and minimal alignment complications of 7.6%. LIV could be spontaneously and progressively improved after operation. Preoperative LIV tilt and LIVDA could predict postoperative correction and coronal balance.

Efficacy and safety for combination of t-EMG with O-arm assisted pedicle screw placement in neurofibromatosis type I scoliosis surgery.

BACKGROUND: Due to the characteristics of neurofibromatosis type I (NF-1) scoliosis, the precise placement of pedicle screws still remains to be a challenge. Triggered screw electromyography (t-EMG) has been proved to exhibit high sensitivity to identify mal-positioned pedicle screws, but no previous study assessed the combination of t-EMG with O-arm-assisted pedicle screw placement in NF-1 scoliosis surgery. OBJECTIVE: To evaluate efficacy and safety for combination of t-EMG with O-arm-assisted pedicle screw placement in NF-1 scoliosis surgery. MATERIALS AND METHODS: From March 2018 to April 2020, sixty-five NF-1 scoliosis patients underwent t-EMG and O-arm-assisted pedicle screw fixation were retrospectively reviewed. The channel classification system was applied to classify the pedicle morphology based on pedicle width measurement by preoperative computed tomography scans. The minimal t-EMG threshold for screw path inspection was used as 8 mA, and operative screw redirection was also recorded. All pedicle screws were verified using a second intraoperative O-arm scan. The correlation between demographic and clinical data with amplitude of t-EMG were also analyzed. RESULTS: A total of 652 pedicle screws (T10-S1) in 65 patients were analyzed. The incidence of an absent pedicle (channel classification type C or D morphology) was 150 (23%). Overall, abnormal t-EMG threshold was identified in 26 patients with 48 screws (7.4%), while 16 out of the 48 screws were classified as G0, 14 out of the 48 screws were classified as G1, and 18 out of the 48 screws were classified as G2. The screw redirection rate was 2.8% (18/652). It showed that t-EMG stimulation detected 3 unacceptable mal-positioned screws in 2 patients (G2) which were missed by O-arm scan. No screw-related neurological or vascular complications were observed. CONCLUSIONS: Combination of t-EMG with O-arm-assisted pedicle screw placement was demonstrated to be a safe and effective method in NF-1 scoliosis surgery. The t-EMG could contribute to detecting the rupture of the medial wall which might be missed by O-arm scan. Combination of t-EMG with O-arm could be recommended for routine use of screw insertion in NF-1 scoliosis surgery.

Risk factors for neurological complications in severe and rigid spinal deformity correction of 177 cases.

BACKGROUND: Difficult procedures of severe rigid spinal deformity increase the risk of intraoperative neurological injury. Here, we aimed to investigate the preoperative and intraoperative risk factors for postoperative neurological complications when treating severe rigid spinal deformity. METHODS: One hundred seventy-seven consecutive patients who underwent severe rigid spinal deformity correction were assigned into 2 groups: the neurological complication (NC, 22 cases) group or non-NC group (155 cases). The baseline demographics, preoperative spinal cord functional classification, radiographic parameters (curve type, curve magnitude, and coronal/sagittal/total deformity angular ratio [C/S/T-DAR]), and surgical variables (correction rate, osteotomy type, location, shortening distance of the osteotomy gap, and anterior column support) were analyzed to determine the risk factors for postoperative neurological complications. RESULTS: Fifty-eight patients (32.8%) had intraoperative evoked potentials (EP) events. Twenty-two cases (12.4%) developed postoperative neurological complications. Age and etiology were closely related to postoperative neurological complications. The spinal cord functional classification analysis showed a lower proportion of type A, and a higher proportion of type C in the NC group. The NC group had a larger preoperative scoliosis angle, kyphosis angle, S-DAR, T-DAR, and kyphosis correction rate than the non-NC group. The results showed that the NC group tended to undergo high-grade osteotomy. No significant differences were observed in shortening distance or anterior column support of the osteotomy area between the two groups. CONCLUSIONS: Postoperative neurological complications were closely related to preoperative age, etiology, severity of deformity, angulation rate, spinal cord function classification, intraoperative osteotomy site, osteotomy type, and kyphosis correction rate. Identification of these risk factors and relative development of surgical techniques will help to minimize neural injuries and manage postoperative neurological complications.

Myofiber necroptosis promotes muscle stem cell proliferation via releasing Tenascin-C during regeneration.

Necroptosis, a form of programmed cell death, is characterized by the loss of membrane integrity and release of intracellular contents, the execution of which depends on the membrane-disrupting activity of the Mixed Lineage Kinase Domain-Like protein (MLKL) upon its phosphorylation. Here we found myofibers committed MLKL-dependent necroptosis after muscle injury. Either pharmacological inhibition of the necroptosis upstream kinase Receptor Interacting Protein Kinases 1 (RIPK1) or genetic ablation of MLKL expression in myofibers led to significant muscle regeneration defects. By releasing factors into the muscle stem cell (MuSC) microenvironment, necroptotic myofibers facilitated muscle regeneration. Tenascin-C (TNC), released by necroptotic myofibers, was found to be critical for MuSC proliferation. The temporary expression of TNC in myofibers is tightly controlled by necroptosis; the extracellular release of TNC depends on necroptotic membrane rupture. TNC directly activated EGF receptor (EGFR) signaling pathway in MuSCs through its N-terminus assembly domain together with the EGF-like domain. These findings indicate that necroptosis plays a key role in promoting MuSC proliferation to facilitate muscle regeneration.

A Retrospective Study of Surgical Correction for Spinal Deformity with and without Osteotomy to Compare Outcome Using Intraoperative Neurophysiological Monitoring with Evoked Potentials.

BACKGROUND This study aimed to evaluate the effects of different combined evoked potentials monitoring modes for non-osteotomy and osteotomy surgery of spinal deformity, and to select individualized modes for various surgeries. MATERIAL AND METHODS We retrospectively reviewed a total of 188 consecutive cases undergoing spinal deformity correction. All patients were classified into 2 cohorts: non-osteotomy (Group A) and osteotomy (Group B). According to intraoperative evoked potential monitoring mode, Group A was divided into 2 sub-groups: A1 [spinal somatosensory evoked potential (SSEP)/motor evoked potential (MEP), n=67)] and A2 [SSEP/MEP/descending neurogenic evoked potential (DNEP), n=52]. Group B was classified as B1 (SSEP/MEP, n=27) and B2 (SSEP/MEP/DNEP, n=42). The demographics, surgical parameters, and evoked potential events of different combined monitoring modes were analyzed within each group. RESULTS The baselines of SSEP/MEP/DNEP in all cases were elicited successfully. Three cases with evoked potential (EP) events (2 with MEP changes and 1 with SSEP/MEP change) were noted in Group A1 and 1 with SSEP change in Group A2, with no neurological complications. Thirteen cases in Group B1 were positive for MEP intraoperatively, including 16 EP events (13 with MEP change and 3 with both SSEP+MEP changes), with no neural complications. In Group B2, 15 cases had 21 EP events, including 12 with MEP change and 2 with SSEP+MEP changes, with no complications. Postoperative neurological complications were observed in 5 of the 7 cases with SS4EP/DNEP changes. CONCLUSIONS Intraoperative simultaneous SSEP/MEP can effectively reflect neurological function in non-osteotomy spinal surgery patients. Simultaneous SSEP/MEP/DNEP can effectively avoid the unnecessary interference by false-positive results of MEP during osteotomy.

Fiber Type-Specific Morphological and Cellular Changes of Paraspinal Muscles in Patients with Severe Adolescent Idiopathic Scoliosis.

BACKGROUND Paraspinal muscle (PSM) has been suggested to have a role in adolescent idiopathic scoliosis (AIS). Few studies have investigated the fiber type-specific changes of PSM in detail. MATERIAL AND METHODS Bilateral multifidus muscles were harvested from the apical vertebra level (T7-T10) of 12 AIS patients and 6 control individuals. Immunohistological staining was performed to evaluate the muscle fiber type composition, fiber type-specific cross-sectional area (CSA), myonuclei density, and the total and activated satellite cell (SC) density. The correlations between these characteristics and curve initiation/severity were analyzed. RESULTS In comparison with the PSM in convexity and the control group, PSM in concavity showed a significant reduction of CSA (concavity, 2601.1±574.1 µm²; convexity, 3732.1±545.1 µm²; control, 3426.5±248.4 µm²), myonuclei density (concavity, 2.0±0.3 myonuclei/fiber; convexity, 2.5±0.4 myonuclei/fiber; control, 2.2±0.2 myonuclei/fiber), and activated SC density (concavity, 0.7±0.4 cells/100 fibers; convexity, 1.5±0.7 cells/100 fibers; control, 1.2±0.3 cells/100 fibers) for fiber type I. The Cobb angle was positively correlated with the bilateral ratio of CSA (convexity/concavity) for both fiber types. The apical vertebral translation was positively correlated with bilateral difference of myonuclei density (type I), total SC density (types I and II), and activated SC density (type I). CONCLUSIONS The fiber type-specific pathological changes on the concave side seemed to be more severe. Some fiber type-specific characteristics (CSA, myonuclei density, total/activated SC density) were closely associated with curve severity. More attention should be paid to PSM physiotherapy treatment on the concave side.

Satisfactory functional and MRI outcomes at the foot and ankle following harvesting of full thickness peroneus longus tendon graft.

AIMS: To evaluate the donor site morbidity and tendon morphology after harvesting whole length, full-thickness peroneus longus tendon (PLT) proximal to the lateral malleolus for ligament reconstructions or tendon transfer. METHODS: A total of 21 eligible patients (mean age 34.0 years (standard deviation (SD) 11.2); mean follow-up period 31.8 months (SD 7.7), and 12 healthy controls (mean age, 26.8 years (SD 5.9) were included. For patients, clinical evaluation of the donor ankle was performed preoperatively and postoperatively. Square hop test, ankle strength assessment, and MRI of distal calf were assessed bilaterally in the final follow-up. The morphological symmetry of peroneal tendons bilaterally was evaluated by MRI in healthy controls. RESULTS: Among the patients, the mean pre- and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score and Karlsson-Peterson score were 98.7 (SD 2.5; p = 0.480) and 98.5 (SD 2.4; p = 0.480), and 98.3 (SD 2.4; p = 0.162) and 97.9 (SD 2.5; p = 0.162), respectively. There was no significant difference between square hop test bilaterally (p = 0.109) and plantar flexion peak force bilaterally (p = 0.371). The harvested limb had significantly less eversion peak force compared to the contralateral limb (p < 0.001). Evidence of probable tendon regeneration was observed in all the patients by MRI and the total bilateral peroneal tendon index (mean ratio of harvested side cross-sectional area of peroneal tendon compared with the contralateral side) was 82.9% (SD 17.4). In 12 healthy controls, peroneal tendons (mean 99.4% (SD 4.3) were found to be morphologically symmetrical between the two sides. CONCLUSION: The current study showed satisfactory clinical foot and ankle outcomes after full-thickness PLT harvesting and indicated the regenerative potential of PLT after its removal. Level of Evidence: Level IV, therapeutic retrospective case series. Cite this article: Bone Joint J 2020;102-B(2):205-211.

Trans-coracoacromial Ligament Glenohumeral Injection With Arthroscopic Confirmation.

PURPOSE: To arthroscopically evaluate the trans-coracoacromial ligament glenohumeral (GH) injection technique by understanding intra-articular needle-tip placement and potential misplacement and complications. METHODS: The technique relies on the palpation of 3 bony landmarks: anterolateral corner of the acromion, superolateral border of the coracoid tip, and curved depression of the distal clavicle. The skin entry site lies on the line connecting the curved depression of the distal clavicle and superolateral border of the coracoid tip, two-thirds of the way from the former and one-third of the way from the latter. The direction of the needle is perpendicular to the triangle formed by the 3 bony landmarks. The technique is used to insufflate the GH joint at the start of shoulder arthroscopy procedures with patients in the beach-chair position. Saline solution is injected, and the position of the needle tip in the GH joint is evaluated arthroscopically. An injection is considered successful if saline solution can be injected and the needle tip can be visualized intra-articularly. RESULTS: This study enrolled 195 patients undergoing shoulder arthroscopy. Successful needle placement in the GH joint occurred in 179 patients (91.8%); placement occurred through the rotator interval in 122 of these, adjacent or through the long head of the biceps tendon in 41, through the upper subscapularis or anterior supraspinatus in 13, and through the anterior labrum in 3. Regarding the 16 failures (8.2%), the needle position did not allow saline solution to be injected because of high resistance in 3 patients whereas the needle tip was not visualized in 13. The needle tip was presumed to rest within the subscapularis muscle or tendon or the labrum in 10 failed injections. CONCLUSIONS: The trans-coracoacromial ligament injection technique showed a high success rate (91.8%) in anesthetized patients about to undergo arthroscopy, whereas the failed injections mainly occurred because the needle was inserted into the subscapularis or labrum. This technique can be used for awake patients with different diagnoses in multiple settings. LEVEL OF EVIDENCE: Level IV, diagnostic study.

Transcoracoacromial Ligament Glenohumeral Injection Technique Using Bony Surface Landmarks.

Intra-articular glenohumeral injection is an important technique used to diagnose and treat shoulder disorders. However, it is frequently performed as an image-guided technique with the use of fluoroscopy, ultrasound, computed tomography, or magnetic resonance. The purpose of this Technical Note is to describe a transcoracoacromial ligament glenohumeral injection technique that uses anatomic surface landmarks to avoid the need for radiographic guidance. After identification of the anterolateral corner of acromion, the superior lateral border of the coracoid tip, and the curved depression of the distal clavicle, the needle entry site is determined at the trisection point between the distal and middle thirds of the line formed by the superior lateral border of the coracoid tip and the curved depression of the distal clavicle. The needle is first inserted perpendicular to the triangular plane of the 3 points and is then advanced toward the humeral head. This injection technique is highly accurate and reproducible and can be done in the outpatient clinic without the use of imaging guidance, reducing the costs and barriers of intra-articular glenohumeral injections for patients.

Transcoracoacromial Ligament Glenohumeral Injection Technique: Accuracy of 116 Injections in Idiopathic Adhesive Capsulitis.

PURPOSE: To describe a transcoracoacromial ligament glenohumeral injection technique that does not require radiographic guidance and to explore the accuracy of this injection technique in patients with idiopathic adhesive capsulitis. METHODS: From February 2015 to April 2017, 89 consecutive patients (116 injections) with idiopathic adhesive capsulitis were included in the study. All of them received unguided glenohumeral injection via the transcoracoacromial ligament technique, and postprocedural fluoroscopic images were used to determine accuracy. The anterolateral corner of acromion, the superior lateral border of coracoid tip, and the curved depression of distal clavicle were identified. The needle entry site was located at the trisection point between the distal third and middle third of the superior lateral border of coracoid tip-curved depression of the distal clavicle line; needle trajectory was perpendicular to the plane formed by the 3 points, and the needle was advanced toward the humeral head. An injection was rated a success if the first fluoroscopic picture showed intra-articular contrast; it was rated a failure if contrast was not intra-articular or the needle needed to be redirected more than 2 times. RESULTS: Out of 116 injections, 111 (95.7%) were successful. For 5 failed injections, there was 1 shoulder with more than 3 redirections and 4 shoulders with no intra-articular contrast (the needle hit the coracoid process in 1 shoulder, the needle rested in the anterior glenoid labrum in 2 shoulders, and the needle was inserted into the subscapularis in 1 shoulder). CONCLUSIONS: The transcoracoacromial ligament glenohumeral injection technique is highly accurate and reproducible in patients with idiopathic adhesive capsulitis. LEVEL OF EVIDENCE: Level IV, therapeutic retrospective case series.

Predictors of Pain and Discomfort Associated with CT Arthrography of the Shoulder.

RATIONALE AND OBJECTIVES: The objective of this study was to investigate predictors of pain associated with computed tomographic arthrography of the shoulder. MATERIALS AND METHODS: Before shoulder arthrography, all participants were assessed with the Hospital Anxiety and Depression Scale (HADS) and the World Health Organization Quality of Life Short Version Instrument (WHOQOL-BREF). The participants were nonrandomized into two groups: the anesthesia group, who underwent prior local infiltration anesthesia before shoulder arthrography, and the nonanesthesia group, who did not undergo prior local infiltration anesthesia. The pain levels at intraprocedure, at 1, 2, 6, and 12 hours, and at 1 and 2 days after injection were assessed by using a visual analog scale. Univariate and multivariate generalized linear model analyses were conducted. RESULTS: Sixty participants in the anesthesia group and 60 participants in the nonanesthesia group were included. The pain level at intraprocedure (3.37 ± 1.94 in the anesthesia group and 3.20 ± 1.34 in the nonanesthesia group) was the highest of the whole pain course. The psychological domain (P = .0013) of WHOQOL-BREF, gender (P = .042), body mass index (P = .0001), and the total number of reinsertion and redirection of needle (P< .0001) were independent predictors of arthrography-related pain. CONCLUSIONS: The pain associated with shoulder computed tomographic arthrography depends on the psychological domain of WHOQOL-BREF, gender, body mass index, and the total number of reinsertion and redirection of needle.