Citations

Gluteus minimus disorders are a potential source of greater trochanteric or anterior hip pain. Disorders of the gluteus minimus tendon most commonly occur in conjunction with gluteus medius tendon abnormalities but can also occur in isolation. Understanding the sonoanatomy of the gluteus minimus muscle‐tendon unit is a prerequisite for recognizing and characterizing gluteus minimus tendon disorders, which, in turn, guides treatment for patients with greater trochanteric or anterior hip pain syndromes.

ObjectiveTo assess the biologic effects of lidocaine on the viability, proliferation, and function of human adipose tissue–derived mesenchymal stromal/stem cells (MSCs) in vitro.MethodsAdipose‐derived MSCs from three donors were exposed to lidocaine at various dilutions (2 mg/mL to 8 mg/mL) and exposure times (0.5 to 4 hours). Cell number and viability, mitochondrial activity, and real‐time reverse‐transcriptase quantitative polymerase chain reaction (RT‐qPCR) were analyzed at 0 (immediate effects) or 24 and 48 hours (recovery effects) after treatment with lidocaine.ResultsTrypan blue staining showed that increasing concentrations of lidocaine decreased the number of observable viable cells. 3‐[4,5,dimethylthiazol‐2‐yl]‐5‐[3‐carboxymethoxy‐phenyl]‐2‐[4‐sulfophenyl]‐2H‐tetrazolium (MTS) assays revealed a concentration‐ and time‐ dependent decline of mitochondrial activity and proliferative ability. Gene expression analysis by RT‐qPCR revealed that adipose‐derived MSCs exposed to lidocaine express robust levels of stress response/cytoprotective genes. However, higher concentrations of lidocaine caused a significant downregulation of these genes. No significant differences were observed in expression of extracellular matrix (ECM) markers COL1A1 and DCN except for COL3A1 (P < .05). Levels of messenger RNA (mRNA) for proliferation markers (CCNB2, HIST2H4A, P < .001) and MKI67 (P < .001) increased at 24 and 48 hours. Expression levels of several transcription factors— including SP1, PRRX1, and ATF1—were modulated in the same manner. MSC surface markers CD44 and CD105 demonstrated decreased expression immediately after treatment, but at 24 and 48 hours postexposure, the MSC markers showed no significant difference among groups.ConclusionLidocaine is toxic to MSCs in a dose‐ and time‐ dependent manner. MSC exposure to high (4‐8 mg/mL) concentrations of lidocaine for prolonged periods can affect their biologic functions. Although the exposure time in vivo is short, it is essential to choose safe concentrations when applying lidocaine along with MSCs to avoid compromising the viability and potency of the stem cell therapy.

Scapular position has been hypothesized to influence rotator cuff function, but no current methods exist to reliably measure shoulder rotation strength in different scapular positions. The purpose of this study was to develop a reliable technique to measure isokinetic (ISOK) and isometric (ISOM) shoulder rotation strength with the scapula protracted. Ten healthy volunteers(5 male, 5 female, ages 20--41) completed two to three ISOM and five ISOK (90 degrees/second) internal rotation (IR) and external rotation (ER) repetitions in a position of scapular protraction with the shoulder abducted 45 degrees in the scapular plane. Subjects returned 24--72 hours later to repeat testing. All torque measurements in the protracted position exhibited excellent intersession reliability (ICCs > 0.97). Shoulder rotational torque can be measured in the protracted scapula position with excellent reliability using the new technique described. Establishing the reliability of the protracted technique is a necessary prerequisite for the completion of future studies examining quantitative differences in rotational torque generation between the neutral and protracted scapula positions in the functional shoulder position of 45 degrees of scapular plane abduction.

AbstractBackgroundThe plantaris tendon (PT) has been implicated in the pathogenesis of symptoms in a subset of patients with Achilles region pain syndromes and traditionally has been managed via open surgical resection. Although the PT can be visualized on ultrasound, a minimally invasive technique for sonographically guided PT release has not been formally described.ObjectiveTo validate a technique to perform sonographically guided PT release in an unembalmed cadaveric model.DesignProspective, cadaveric laboratory investigation.SettingProcedural skills laboratory in a tertiary medical center.SubjectsTwenty unembalmed cadaveric knee–ankle–foot specimens (10 right, 10 left) obtained from 16 donors (6 male, 10 female) ages 55‐96 years (mean 82.6 years) with body mass indexes of 14.1‐33.2 kg/m2 (mean 23.3 kg/m2).MethodsAfter simulated local anesthesia and sonographically guided hydrodissection of the plantaris tendon–Achilles tendon interval, a single experienced operator performed sonographically guided PT release on each specimen using an in‐plane, lateral‐to‐medial approach, a commercially available, disposable 3.0‐mm hook knife, and either a 17‐5 MHz or 15‐7 MHz linear array transducer. Each specimen was subsequently dissected to assess for PT release and iatrogenic injury.Main OutcomeStatus of the PT, Achilles tendon, and regional neurovascular structures as determined by dissection.ResultsAll 20 PT releases were completed in a single attempt through a 3‐ to 5‐mm incision. Dissection confirmed complete PT release in all specimens without damage to the adjacent Achilles tendon or regional neurovascular structures.ConclusionSonographically guided PT release is technically feasible and can be performed while avoiding injury to the Achilles tendon and regional neurovascular structures. Additional research is warranted to further define the role of sonographically guided PT release in patients with suspected PT‐mediated Achilles region pain syndromes.Level of EvidenceIV

BackgroundTransplantation of mesenchymal stem cells (MSCs) is a promising therapy for degenerative spine conditions. However, cell therapy for painful spine degeneration presently requires use of contrast agents during fluoroscopy‐guided injections, and the effects of these agents on MSCs represents a gap in knowledge.ObjectiveTo investigate the biological effects of contrast media (CM) that are coinjected with MSCs.DesignProspective observational study.SettingAcademic medical center.ParticipantsPatient‐derived clinical‐grade culture expanded MSCs.InterventionsIohexol (Omnipaque300) was reduced to 12.5%, 25%, 50%, and 100% of the stock solution and incubated with MSCs for 30 minutes, 4 hours, and 48 hours. We also used complete media and 12.5%, 25%, 50%, 100% of phosphate‐buffered saline as a control group.Main Outcome MeasuresWe examined cytotoxicity of iohexol at different concentrations and exposure duration, as well as the potential for recovery over time. Cell counts, mitochondrial activity, and quantitative real time reverse‐transcriptase polymerase chain reaction of related genes were analyzed immediately after exposure (day 0) and after 2 days of exposure (day 2).ResultsHuman MSCs exhibit a time‐ and concentration‐dependent cytotoxic response to iodinated CM. A brief, 30‐minute exposure did not affect MSCs function and viability. However, extended treatment with iohexol for 4 hours at 50% or higher concentration had a significant impact on both viability and gene expression in MSCs.ConclusionsIohexol is cytotoxic to MSCs in a time‐and concentration‐dependent manner. Hence, the concentration of CM that accompanies MSC injections should be carefully considered during MSC therapy for disk‐degenerative diseases.Level of EvidenceIII.

Inflammatory etiologies are becoming increasingly recognized as explanations of some neuropathies, especially those occurring in the perioperative period. Although “brachial neuritis” is known to affect extraplexal nerves, accessory nerve palsy following median sternotomy has been attributed to stretch on the nerve. To better elucidate stretch as a potential cause, a cadaveric study was performed. Two patients who developed accessory nerve palsy following median sternotomy are presented to illustrate features consistent with the diagnosis of a perioperative inflammatory neuropathy. Five adult unembalmed cadavers underwent exposure of the bilateral accessory nerves in the posterior cervical triangle. A median sternotomy was performed and self‐retaining retractors positioned. With the head in neutral, left rotation and right rotation, retractors were opened as during surgery while observing and recording any accessory nerve movements. The self‐retaining sternal retractors were fully opened to a mean inter‐blade distance of 13 cm. Regardless of head position, from the initial retractor click to maximal opening there was no gross movement of the accessory nerve on the left or right sides. Opening self‐retaining sternal retractors does not appear to stretch the accessory nerve in the posterior cervical triangle. Based on our clinical experience and cadaveric results, we believe that inflammatory conditions, (i.e., idiopathic brachial plexitis) can involve the accessory nerve, and might be triggered by surgical procedures. Clin. Anat. 31:417–421, 2018. © 2017 Wiley Periodicals, Inc.

The purpose of this study was to determine whether 8 weeks of ankle disk training alters ankle muscle onset latency of patients with a history of lateral ankle sprain. The training was completed by eight minimally symptomatic subjects with a history of nonrehabilitated, unilateral, inversion ankle sprain sustained between 6 and 16 months before entry into the study. Ankle inversion perturbations monitored by fine-wire electromyography were performed in four lower extremity muscles (anterior tibialis, posterior tibialis, peroneus longus, and flexor digitorum longus) of all subjects on both the injured (experimental) and noninjured (control) legs. Testing was performed at study entry and after 8 weeks of ankle disk training on the previously injured ankle. Results revealed a statistically significant decrease in the anterior tibialis onset latency in both the experimental (67.6 ± 20.3 to 51.7 ± 17.6) and control (65.5 ± 9.8 to 53.8 ± 23.7) ankles after the training period. These findings indicate that muscle onset latency decreases in specific ankle muscle groups after ankle disk training in previously injured ankles. Both the experimental and control ankles demonstrated a significant change, which raises the question as to whether a proprioceptive cross-training effect occurred.

Fracture of the lateral process of the talus is an injury unique to snowboarders and is of particular clinical relevance because it masquerades as an anterolateral ankle sprain and is difficult to detect on standard radiographic views. Misdiagnosis can lead to long-term morbidity in a young and active population, with ensuing severe degeneration of the subtalar joint. To date, the precise mechanism of injury has not been established, making it difficult to identify potential preventive strategies in equipment design or snowboarding technique. Fracture of the lateral process of the talus in snowboarders has been thought to result from pure dorsiflexion and inversion combined with axial loading. We hypothesized, however, that external rotation is a key component of the mechanism of injury. Ten cadaveric ankles were mounted on a materials testing machine in a position of fixed dorsiflexion and inversion. All ankles were loaded to failure axially, with or without combined external rotation. No fractures occurred after axial loading in dorsiflexion and inversion, but six of eight specimens sustained fractures of the lateral process of the talus when similarly loaded with external rotation added, supporting our hypothesis. Further study is needed to evaluate the relationship between various types of snowboarding equipment and fracture mechanism.