Developmental process of the modern house shrew's molars: implications for the evolution of the tribosphenic molar in Mesozoic mammals.

Phylogenetically, the tribosphenic molars-prototypes of multi-cusped cheek teeth in marsupial and placental mammals-are derived from the single-cusped conical teeth of reptiles through the addition of cusps. Ontogenetically, mammalian molars are formed through the interface between the dental epithelium and mesenchyme (future enamel-dentin junction), becoming geometrically complex by adding epithelial signaling centers, called enamel knots, which determine future cusp positions. To reevaluate cusp homologies in Mesozoic mammals from an ontogenetic perspective, this study tracked molar development in a living placental mammal species, the house shrew (Suncus murinus), whose molars are morphologically the least derived from tribosphenic prototypes. The development of shrew molars proceeded as if it replayed the evolutionary process of tribosphenic molars. The first formed enamel knots gave rise to the evolutionarily oldest cusps-upper paracone and lower protoconid. The order of formation of other enamel knots and their location in development seemed to trace the order of cusp appearance in evolution. The parallel relationship between ontogeny and phylogeny of mammalian molars, if any, suggests that a change in the timing between developmental events rather than a change in the morphogenetic mechanism itself, should have been a major causal factor for the evolutionary transformation of tooth morphology.

Distinct Inflammatory Macrophage Populations Sequentially Infiltrate Bone-to-Tendon Interface Tissue After Anterior Cruciate Ligament (ACL) Reconstruction Surgery in Mice.

Macrophages are important for repair of injured tissues, but their role in healing after surgical repair of musculoskeletal tissues is not well understood. We used single-cell RNA sequencing (RNA-seq), flow cytometry, and transcriptomics to characterize functional phenotypes of macrophages in a mouse anterior cruciate ligament reconstruction (ACLR) model that involves bone injury followed by a healing phase of bone and fibrovascular interface tissue formation that results in bone-to-tendon attachment. We identified a novel "surgery-induced" highly inflammatory CD9+ IL1+ macrophage population that expresses neutrophil-related genes, peaks 1 day after surgery, and slowly resolves while transitioning to a more homeostatic phenotype. In contrast, CX3CR1+ CCR2+ macrophages accumulated more slowly and unexpectedly expressed an interferon signature, which can suppress bone formation. Deletion of Ccr2 resulted in an increased amount of bone in the surgical bone tunnel at the tendon interface, suggestive of improved healing. The "surgery-induced macrophages" identify a new cell type in the early phase of inflammation related to bone injury, which in other tissues is dominated by blood-derived neutrophils. The complex patterns of macrophage and inflammatory pathway activation after ACLR set the stage for developing therapeutic strategies to target specific cell populations and inflammatory pathways to improve surgical outcomes. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Arthroscopic Bankart Repair and Open Bristow Procedure in the Treatment of Anterior Shoulder Instability With Osseous Glenoid Lesions in Collision Athletes.

BACKGROUND: Traumatic anterior shoulder instability in collision sports athletes often involves osseous glenoid lesions, which make surgical treatment challenging. High redislocation rates have been seen in collision sports athletes treated using arthroscopic Bankart repair. PURPOSE: To investigate the effectiveness of a combined arthroscopic Bankart repair and open Bristow procedure for the treatment of traumatic anterior shoulder instability in collision sports athletes, with a focus on osseous glenoid lesions. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: We reviewed 149 shoulders in 141 competitive collision sports athletes (mean ± standard deviation age, 20.1 ± 4.1 years; 8 bilateral cases) who underwent a combined arthroscopic Bankart repair and open Bristow procedure with minimum 2 years of follow-up. Osseous Bankart lesions were arthroscopically reduced and fixed using a coracoid graft. RESULTS: Clinical outcomes as indicated by mean Rowe score improved significantly from 50.0 preoperatively to 98.9 postoperatively (P < .001) at a median follow-up of 3.4 years (range, 2.5-7 years). There were 2 recurrent dislocations (1.3%), both of which had nonunion of the transferred coracoid. Osseous Bankart lesions were observed in 85 shoulders, and osseous glenoid lesions ≥10% of the diameter of the nonoperative side were found in 58 shoulders, including 24 off-track cases. Clinical outcomes were not significantly different between patients with a glenoid defect ≥10% and <10%. Nonunion of the transferred coracoid was observed in 16 shoulders (10.7%), which had inferior Rowe scores; however, we could not define any risk factors for nonunion, including patient characteristics or bone morphology. Postoperative computed tomography performed in 29 patients >1 year after surgery showed successful repair of the osseous glenoid lesions, with a restored glenoid articular surface in all cases. Significant pre- to postoperative increases were seen in glenoid diameter (mean, 13.1% [95% CI, 9.9%-16.3%]; P < .001) and area (mean, 10.6% [95% CI, 8.5%-12.7%]; P < .001). CONCLUSION: A combined arthroscopic Bankart repair and open Bristow procedure improved bone morphology and was a reliable surgical method for treating collision sports athletes with traumatic anterior shoulder instability involving osseous glenoid lesions.

Post-operative pain control following arthroscopic rotator cuff repair: peri-articular injection versus interscalene brachial plexus block.

PURPOSE: To compare post-operative pain relief with peri-articular injection (PI) versus interscalene brachial plexus block (IBPB) after arthroscopic rotator cuff repair (ARCR) surgery. METHODS: We retrospectively reviewed 121 consecutive patients undergoing ARCR surgery divided into two groups: the PI group and the IBPB group. We compared complications and self-reported pain score measured using a Numerical Rating Scale (NRS) during the initial 24 hours after surgery. RESULTS: The NRS scores recorded in the recovery room (0), 0.5, and four hours post-operatively were higher in the PI group (n = 38) than the IBPB group (n = 52) (2.1 vs. 0.8, p = 0.014; 1.4 vs. 0.5, p = 0.0069; and 1.3 vs. 0.5, p = 0.012, respectively). However, the NRS scores recorded at 16, 20, and 24 hours post-operatively were lower in the PI group than in the IBPB group (1.4 vs. 3.1, p < 0.0001; 1.4 vs. 3.2, p < 0.0001; and 1.7 vs. 3.2, p = 0.00046, respectively). The incidences of post-operative nausea and temporary numbness in the upper arm were significantly lower in the PI group than in the IBPB group (7.9% vs. 33%, p = 0.0052; and 13% vs. 85%, p < 0.0001, respectively). CONCLUSIONS: Although IBPB provided superior pain control during the initial few hours after ARCR surgery, PI was superior from 16 to 24 hours post-operatively. The rates of side effects, such as nausea and temporary arm numbness, were also lower in the PI group than in the IBPB group.

Craniofacial abnormality with skeletal dysplasia in mice lacking chondroitin sulfate N-acetylgalactosaminyltransferase-1.

Chondroitin sulfate (CS) proteoglycan is a major component of the extracellular matrix and plays an important part in organogenesis. To elucidate the roles of CS for craniofacial development, we analyzed the craniofacial morphology in CS N-acetylgalactosaminyltransferase-1 (T1) gene knockout (KO) mice. T1KO mice showed the impaired intramembranous ossification in the skull, and the final skull shape of adult mice included a shorter face, higher and broader calvaria. Some of T1KO mice exhibited severe facial developmental defect, such as eye defects and cleft lip and palate, causing embryonic lethality. At the postnatal stages, T1KO mice with severely reduced CS amounts showed malocclusion, general skeletal dysplasia and skin hyperextension, closely resembling Ehlers-Danlos syndrome-like connective tissue disorders. The production of collagen type 1 was significantly downregulated in T1KO mice, and the deposition of CS-binding molecules, Wnt3a, was decreased with CS in extracellular matrices. The collagen fibers were irregular and aggregated, and connective tissues were dysorganized in the skin and calvaria of T1KO mice. These results suggest that CS regulates the shape of the craniofacial skeleton by modulating connective tissue organization and that the remarkable reduction of CS induces hypoplasia of intramembranous ossification and cartilage anomaly, resulting in skeletal dysplasia.

MRI for the diagnosis of scapular dyskinesis: a report of two cases.

Scapular dyskinesis describes the altered position of the scapula and/or abnormal movements of the scapulothoracic joint. It is caused by bony anatomical variations, bursitis, tumors, and muscular pathological conditions including loss of innervation and fibrosis. Scapular dyskinesis is just as often subclinical as it is symptomatic, and as the periscapular anatomical changes may not result in patient symptoms, a precise diagnosis of the etiology and pathophysiology has been a challenge. Scapular bony prominence is a common etiology of scapular dyskinesis, but does not always result in morbidity. We report a case of a 39-year-old man in whom an extensive MRI with fluid-sensitive imaging sequences covering the whole of the scapula was beneficial in diagnosing the inflammation adjacent to the bony deformity, which confirmed the etiology of scapular dyskinesis. Furthermore, in a 41-year old man without any anatomical variances, a similar MRI showed inflammation at the subscapular fossa that suggested altered scapular kinematics. An arthroscopic debridement of the lesion improved the symptoms. MRI in conjunction with plain radiographs, CT and physical examination enabled a precise diagnosis of the etiology. Fluid-sensitive MR images are important in defining the presence of inflammation, and are beneficial in determining the pathological significance of findings through other diagnostic measures.

Combined Arthroscopic Bankart Repair and Coracoid Process Transfer to Anterior Glenoid for Shoulder Dislocation in Rugby Players: Evaluation Based on Ability to Perform Sport-Specific Movements Effectively.

PURPOSE: To evaluate the outcomes of a combination of an arthroscopic Bankart repair and an open Bristow procedure in relation to the subjective quality of performance in movements that are typical in rugby. METHODS: Forty shoulders in 38 players who underwent surgery for traumatic anterior instability of the shoulder were reviewed. In all cases, arthroscopic Bankart repair was followed by a Bristow procedure, with preservation of the repaired capsular ligaments, during the same operation. The mean age at the time of surgery was 21 years. Patients were asked to describe common rugby maneuvers (tackle, hand-off, jackal, and saving) preoperatively and postoperatively as "no problem," "insufficient," or "impossible." RESULTS: There were no recurrent dislocations at a mean follow-up of 30.5 months. The mean Rowe score improved significantly from 65.0 (range, 55 to 75) to 97.5 (range, 95 to 100) (P < .001) after surgery. Preoperatively, regarding the tackling motion, none of the patients reported having no problem, whereas the ability was described as insufficient for 23 shoulders and impossible for 17 shoulders. Postoperatively, no problem with tackling was reported for 36 shoulders, whereas insufficiency was reported for 4. The results for the hand-off, jackal, and saving maneuvers were similar (P < .001). No patient rated any of the motions as impossible postoperatively. CONCLUSIONS: This combined surgical procedure clearly is effective in preventing recurrent dislocation in rugby players; however, some players complained of insufficiency in the quality of their play when they were tackling or performing other rugby-specific movements. LEVEL OF EVIDENCE: Level IV, case series.

Quantitative and qualitative analyses of subacromial impingement by kinematic open MRI.

PURPOSE: Quantitative and qualitative kinematic analyses of subacromial impingement by 1.2T open MRI were performed to determine the location of impingement and the involvement of the acromioclavicular joint. METHODS: In 20 healthy shoulders, 10 sequential images in the scapular plane were taken in a 10-s pause at equal intervals from 30° to maximum abduction in neutral and internal rotation. The distances between the rotator cuff (RC) and the acromion and the acromioclavicular joint were measured. To comprehend the positional relationships, cadaveric specimens were also observed. RESULTS: Although asymptomatic, the RC came into contact with the acromion and the acromioclavicular joint in six and five cases, respectively. The superior RC acted as a depressor for the humeral head against the acromion as the shoulder elevated. The mean elevation angle and distance at the closest position between the RC and the acromion in neutral rotation were 93.5° and 1.6 mm, respectively, while those between the RC and the acromioclavicular joint were 86.7° and 2.0 mm. When comparing this distance and angle, there was no significant difference between the RC to the acromion and to the acromioclavicular joint. The minimum distance between the RC and the acromion was significantly shorter than that between the greater tuberosity and the acromion. The location of RC closest to the acromion and the acromioclavicular joint differed significantly. CONCLUSION: Although asymptomatic, contact was found between the RC and the acromion and the acromioclavicular joint. The important role of the RC to prevent impingement was observed, and hence, dysfunction of the RC could lead to impingement that could result in a RC lesion. The RC lesions may differ when they are caused by impingement from either the acromion or the acromioclavicular joint.

Penetrating injury to the cauda equina: a case report and review of the literature.

STUDY DESIGN: Case report. OBJECTIVE: To report a rare case of a penetrating injury to the cauda equina, secondary to a stab wound. SUMMARY OF BACKGROUND DATA: Penetrating injuries affecting the cauda equina by stab wounds, not by gunshot wounds, are of extremely rare occurrence compared with penetrating spinal cord injuries and have been previously reported only in 2 studies since 1969. METHODS AND RESULTS: A 43-year-old man was presented with a stab wound to the right lumbar region, with immediate paralysis of the left lower extremity accompanied by loss of perineal sensation. Magnetic resonance imaging suggested rupture of the cauda equina nerves at the L3 to L4 level. The patient was taken immediately for surgery for irrigation and debridement. We identified several cut ends of the cauda equina nerves and attempted to repair them, but had to determine that accurate matching of the severed ends would be problematic. At 2 years follow-up, there were no significant improvements in the neurological status. The patient was ambulatory with an ankle-foot orthosis, and had already returned back to work. CONCLUSIONS: We could not repair the cauda equina rootlets. However, similar to other central nervous system penetrating injuries, the priorities of treatment included an emphasis on infection control and sealing of the duro-cutaneous fistula, and we could easily manage both by the emergency surgery. Although there were no improvements in the neurological function, there were no complications and the patient returned to a reasonably good function.

Effect of sequence-directed nucleosome disruption on cell-type-specific repression by alpha2/Mcm1 in the yeast genome.

In Saccharomyces cerevisiae, a-cell-specific genes are repressed in MATalpha cells by alpha2/Mcm1, acting in concert with the Ssn6-Tup1 corepressors and the Isw2 chromatin remodeling complex, and nucleosome positioning has been proposed as one mechanism of repression. However, prior studies showed that nucleosome positioning is not essential for repression by alpha2/Mcm1 in artificial reporter plasmids, and the importance of the nucleosome positioning remains questionable. We have tested the function of positioned nucleosomes through alteration of genomic chromatin at the a-cell-specific gene BAR1. We report here that a positioned nucleosome in the BAR1 promoter is disrupted in cis by the insertion of diverse DNA sequences such as poly(dA) . poly(dT) and poly(dC-dG) . poly(dC-dG), leading to inappropriate partial derepression of BAR1. Also, we show that isw2 mutation causes loss of nucleosome positioning in BAR1 in MATalpha cells as well as partial disruption of repression. Thus, nucleosome positioning is required for full repression, but loss of nucleosome positioning is not sufficient to relieve repression completely. Even though disruption of nucleosome positioning by the cis- and trans-acting modulators of chromatin has a modest effect on the level of transcription, it causes significant degradation of the alpha-mating pheromone in MATalpha cells, thereby affecting its cell type identity. Our results illustrate a useful paradigm for analysis of chromatin structural effects at genomic loci.