Osteoblast-Derived Matrix Vesicles Exhibit Exosomal Traits and a Unique Subset of microRNA: Their Caveolae-Dependent Endocytosis Results in Reduced Osteogenic Differentiation.

Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellular matrix (ECM). In addition to playing a role in biomineralization, osteoblast-derived MVs were recently suggested to have regulatory duties. The aims of this study were to establish the characteristics of osteoblast-derived MVs in the context of extracellular vesicles like exosomes, assess their role in modulating osteoblast differentiation, and examine their mechanism of uptake. MVs were isolated from the ECM of MG63 human osteoblast-like cell cultures and characterized via enzyme activity, transmission electron microscopy, nanoparticle tracking analysis, Western blot, and small RNA sequencing. Osteoblasts were treated with MVs from two different culture conditions (growth media [GM]; osteogenic media [OM]) to evaluate their effects on the differentiation and production of inflammatory markers and on macrophage polarization. MV endocytosis was assessed using a lipophilic, fluorescent dye and confocal microscopy with the role of caveolae determined using methyl-ß-cyclodextrin. MVs exhibited a four-fold enrichment in alkaline phosphatase specific activity compared to plasma membranes; were 50-150 nm in diameter; possessed exosomal markers CD63, CD81, and CD9 and endosomal markers ALIX, TSG101, and HSP70; and were selectively enriched in microRNA linked to an anti-osteogenic effect and to M2 macrophage polarization. Treatment with GM or OM MVs decreased osteoblast differentiation. Osteoblasts endocytosed MVs using a mechanism that involves caveolae. These results support the hypothesis that osteoblasts produce MVs that participate in the regulation of osteogenesis.

Comparison of 2D, 3D, and radially reformatted MR images in the detection of labral tears and acetabular cartilage injury in young patients.

OBJECTIVE: The purpose of this study was to compare the utility of two-dimensional high-resolution (2D), 3-dimensional with multiplanar reconstruction (3D MPR), and radially reformatted (RR) MRIs when evaluating the complexities of the hip joint in patients with femoroacetabular impingement (FAI). We hypothesized RR would be superior in detecting labral pathology and 2D would be superior in detecting transition zone and acetabular cartilage injury. MATERIALS AND METHODS: 2D, 3D MPR, and RR MRIs of 33 patients, who later underwent surgical treatment for FAI, were evaluated for sensitivity, specificity, and accuracy. Bland-Altman methods were used to estimate agreement between each method and the gold-standard, arthroscopic visualization of the hip joint, regarding the percentage of the hip joint affected by each injury type. RESULTS: 3D MPR and RR groupings were associated with the highest sensitivity and accuracy for labral injury. 3D MPR demonstrated the smallest bias in assessing the percentage of joint affected by labral injury and was the most accurate in identifying acetabular cartilage injury, whereas RR had the smallest mean difference in assessing the percentage of joint affected by acetabular cartilage injury. 2D was the most accurate in identifying transition zone injuries, while RR was superior in assessing the percentage of the joint affected by transition zone injury. CONCLUSIONS: Our results suggest that including both 3D MPR and RR MRI groupings is favorable for accurate joint visualization and well-informed treatment planning, especially given that labral injury is a main source of pain and dysfunction for FAI patients.

No Difference in Return to Sport and Other Outcomes Between Operative and Nonoperative Treatment of Medial Epicondyle Fractures in Pediatric Upper-Extremity Athletes.

OBJECTIVE: Compare outcomes of operative and nonoperatively managed medial epicondyle fractures in upper-extremity athletes. DESIGN: Retrospective chart review and phone survey. SETTING: Level 1, tertiary-referral pediatric hospital. PATIENTS: Propensity scores (probability of operative treatment) were estimated from a logistic regression model that included sex, age, displacement, limb dominance, and injury severity (presence of an additional fracture, nerve injury, or elbow dislocation). These were used to match subjects in the operative group to the nonoperative group. MAIN OUTCOME MEASURES: Return to sport, duration of time required to return to sport, pain, range of motion (ROM), need for physical therapy, and complications were recorded for both groups. RESULTS: Twenty-eight nonoperative subjects were matched to 14 operative subjects. There was no significant difference in the proportion of subjects who returned to the same sport (92.9% in each group), performance at preinjury level of competition, or median time to return to play (P = 0.7106). There was no significant difference in functional limitations in social-/work-related activities (P > 0.9999), pain in the past 30 days (P = 0.0640), need for physical therapy (P = 0.5680), ROM limitations (P = 0.0988), difficulty in sleeping (P = 0.4773), or complications (P = 0.4081). CONCLUSIONS: Our study found no statistical difference in outcomes or complications between operative and nonoperatively treated moderately displaced medial epicondyle fractures in adolescent upper-extremity athletes. Our data show that similar outcomes may be achieved with both treatment groups for medial epicondyle fractures in upper-extremity athletes.

What Are the Effects of Capsular Plication on Translational Laxity of the Glenohumeral Joint: A Study in Cadaveric Shoulders.

BACKGROUND: Surgical treatment for shoulder instability generally involves labral repair with a capsular plication or imbrication. Good results are reported in both open and arthroscopic procedures, but there is no consensus on the amount or location of capsular plication that is needed to achieve stability and anatomic anterior, posterior, and inferior translation of the joint. QUESTIONS/PURPOSES: (1) What are the separate and combined effects of increasing plication magnitude and sequential additive plications in the anterior, posterior, and inferior locations of the joint capsule on glenohumeral joint translation in the anterior, posterior, and inferior directions? (2) What plication location and magnitude restores anterior, posterior, and inferior translation to a baseline level? METHODS: Fourteen cadaveric shoulders were dissected down to the glenohumeral capsule and underwent instrumented biomechanical testing. Each shoulder was loaded with 22 N in anterior, posterior, and inferior directions at 60° abduction and neutral rotation and flexion and the resulting translation were recorded. Testing was done over baseline (native), stretched (mechanically stretched capsule to imitate a lax capsule), and 5-mm, 10-mm, and 15-mm plication conditions. Individually, for each of the 5-, 10-, and 15-mm increments, plications were done in a fixed sequential order starting with anterior plication at the 3 o'clock position (Sequence I), then adding posterior plication at the 9 o'clock position (Sequence II), and then adding inferior plication at the 6 o'clock position (Sequence III). Each individual sequence was tested by placing 44 N (10 pounds) of manual force on the humerus directed in an anterior, posterior, and inferior direction to simulate clinical load and shift testing. The effect of plication magnitude and sequence on translation was tested with generalized estimating equation models. Translational differences between conditions were tested with paired t-tests. RESULTS: Translational laxity was highest with creation of the lax condition, as expected. Increasing plication magnitude had a significant effect on all three directions of translation. Plication location sequence had a significant effect on anterior and posterior translation. An interaction effect between plication magnitude and sequence was significant in anterior and posterior translation. Laxity in all directions was most restricted with 15-mm plication in anterior, posterior, and inferior locations. For anterior translational laxity, at 10-mm and 15-mm plication, there was a progressive decrease in translation magnitude (10-mm plication anterior only: 0.46 mm, plus posterior: 0.29 mm, plus inferior, -0.12 mm; and for 15-mm anterior only: -0.53 mm, plus posterior: -1.00 mm, plus inferior: -1.66 mm). For posterior translational laxity, 10-mm and 15-mm plication also showed progressive decrease in magnitude (10-mm plication anterior only: 0.46 mm, plus posterior: -0.25 mm, plus inferior: -1.94; and for 15-mm anterior only: 0.14 mm, plus posterior: -1.54 mm, plus inferior: -3.66). For inferior translational laxity, tightening was observed only with magnitude of plication (anterior only at 5 mm: 0.31 mm, at 10 mm: -1.39, at 15 mm: -3.61) but not with additional plication points (adding posterior and inferior sequences). To restore laxity closest to baseline, 10-mm AP/inferior plication best restored anterior translation, 15-mm anterior plication best restored posterior translation, and 5 mm posterior with or without inferior plication best restored inferior translation. CONCLUSIONS: Our results suggest that (1) a 10-mm plication in the anterior and posterior or anterior, posterior, and inferior positions may restore anterior translation closest to baseline; (2) 10-mm anterior and posterior or 15-mm anterior plications may restore posterior translation closest to baseline; and (3) 5-mm anterior and posterior or anterior, posterior, and inferior plications may restore inferior translation closest to baseline. Future studies using arthroscopic techniques for plication or open techniques via a true surgical approach might further characterize the effect of plication on glenohumeral translation. CLINICAL RELEVANCE: This study found that specific combinations of plication magnitude and location can be used to restore glenohumeral translation from a lax capsular state to a native state. This information can be used to guide surgical technique based on an individual patient's degree and direction of capsular laxity. In vivo testing of glenohumeral translation before and after capsular plication will be needed to validate these cadaveric results.

Pelvic Osteotomies in the Child and Young Adult Hip: Indications and Surgical Technique.

Pelvic osteotomies are used for hip preservation in children and young adults to improve femoral head coverage and stabilize the hip joint. Redirectional osteotomies aim to reduce the overall volume and redirect the acetabulum. These include Salter, Pemberton, Dega, and San Diego osteotomies. Reorientation osteotomies aim to reorient the acetabulum and include periacetabular and triple osteotomies. Salvage osteotomies aim to enlarge the acetabulum and medialize the hip center. These include shelf and Chiari osteotomies. The standard anterior approach and surgical technique for the eight pelvic osteotomies used by hip preservation surgeons are described along with each osteotomy's history, indications, and outcomes.

No difference in outcomes in a matched cohort of operative versus nonoperatively treated displaced medial epicondyle fractures.

The purpose of our study was to compare the treatment outcomes and complications between operatively and nonoperatively treated displaced medial epicondyle fractures. Pediatric patients treated for an acute, displaced medial epicondyle fracture between 2005 and 2015 were retrospectively reviewed. A total of 22 operative participants were matched to 22 nonoperative participants, with an average displacement of 9.7 mm in both groups. There was no statistical difference in average length of immobilization, median time to full pronation/supination and flexion/extension, proportion of patients needing physical therapy, and complications. There were no statistical differences in outcomes between operative and nonoperatively treated, moderately displaced, pediatric medial epicondyle fractures. This suggests that operative and nonoperative interventions show equivalent outcomes for these injuries.