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Anesthesiology Jan 2022Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface... (Review)
Review
Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. Atelectasis impairs blood oxygenation and reduces lung compliance. It is increasingly recognized that it can also induce local tissue biologic responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability, and susceptibility to infection, factors that can initiate or exaggerate lung injury. Mechanical ventilation of a heterogeneously aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension. Knowledge of such pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management.
Topics: Animals; Diaphragm; Humans; Intraoperative Complications; Lung; Perioperative Care; Pulmonary Atelectasis; Respiration, Artificial
PubMed: 34499087
DOI: 10.1097/ALN.0000000000003943 -
Dental Update 2016Extra-oral appliances are used in orthodontics to apply forces to the jaws, dentition or both and the popularity of these appliances is cyclical. Although the use of... (Review)
Review
Extra-oral appliances are used in orthodontics to apply forces to the jaws, dentition or both and the popularity of these appliances is cyclical. Although the use of retraction headgear for the management of Class II malocclusion has declined over the last 20 years with the refinement of non-compliance approaches, including temporary anchorage devices, headgear still has a useful role in orthodontics. The use of protraction headgear has increased as more evidence of its effectiveness for the treatment of Class lIl malocclusion has become available. This paper describes the mechanics and contemporary uses of headgear in orthodontics for primary care dentists and specialist orthodontists. CPD/CLINICAL RELEVANCE: Extra-oral appliances have specific uses in orthodontic biomechanics. Clinicians using retraction headgear and protraction headgear should be familiar with their clinical indications, the potential problems and how these can be avoided.
Topics: Biomechanical Phenomena; Extraoral Traction Appliances; Humans; Orthodontic Anchorage Procedures; Orthodontic Appliance Design; Stress, Mechanical; Tooth Movement Techniques
PubMed: 27024904
DOI: 10.12968/denu.2016.43.1.74 -
GMS Interdisciplinary Plastic and... 2016Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the... (Review)
Review
Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the knee. Diagnosis is based on the injury mechanism, physical examination and radiological findings. While the clinical diagnosis is often distinct, there are numerous treatment options available. The type of treatment as well as the optimum timing of surgical intervention depends on the underlying fracture type, the associated soft tissue damage, patient factors (i.e. age, bone quality, activity level and compliance) and the stability of the extensor mechanism. Regardless of the treatment method an early rehabilitation is recommended in order to avoid contractures of the knee joint capsule and cartilage degeneration. For non-displaced and dislocated non-comminuted transverse patellar fractures (2-part) modified anterior tension band wiring is the treatment of choice and can be combined - due to its biomechanical superiority - with cannulated screw fixation. In severe comminuted fractures, open reduction and fixation with small fragment screws or new angular stable plates for anatomic restoration of the retropatellar surface and extension mechanism results in best outcome. Additional circular cerclage wiring using either typical metal cerclage wires or resorbable PDS/non-resorbable FiberWires increases fixation stability and decreases risk for re-dislocation. Distal avulsion fractures should be fixed with small fragment screws and should be protected by a transtibial McLaughlin cerclage. Partial or complete patellectomy should be regarded only as a very rare salvage operation due to its severe functional impairment.
PubMed: 26816667
DOI: 10.3205/iprs000080 -
Annual Review of Biomedical Engineering 2015Aging is a complex, multifaceted process that induces a myriad of physiological changes over an extended period of time. Aging is accompanied by major biochemical and... (Review)
Review
Aging is a complex, multifaceted process that induces a myriad of physiological changes over an extended period of time. Aging is accompanied by major biochemical and biomechanical changes at macroscopic and microscopic length scales that affect not only tissues and organs but also cells and subcellular organelles. These changes include transcriptional and epigenetic modifications; changes in energy production within mitochondria; and alterations in the overall mechanics of cells, their nuclei, and their surrounding extracellular matrix. In addition, aging influences the ability of cells to sense changes in extracellular-matrix compliance (mechanosensation) and to transduce these changes into biochemical signals (mechanotransduction). Moreover, following a complex positive-feedback loop, aging is accompanied by changes in the composition and structure of the extracellular matrix, resulting in changes in the mechanics of connective tissues in older individuals. Consequently, these progressive dysfunctions facilitate many human pathologies and deficits that are associated with aging, including cardiovascular, musculoskeletal, and neurodegenerative disorders and diseases. Here, we critically review recent work highlighting some of the primary biophysical changes occurring in cells and tissues that accompany the aging process.
Topics: Aging; Animals; Biomechanical Phenomena; Cell Nucleus; Chromatin; Epigenesis, Genetic; Extracellular Matrix; Humans; Mechanotransduction, Cellular; Mitochondria; Models, Biological; Wound Healing
PubMed: 26643020
DOI: 10.1146/annurev-bioeng-071114-040829 -
The American Journal of Sports Medicine Aug 2018Treatment strategies for Achilles tendon rupture vary considerably, and clinical outcome may depend on the magnitude of tendon elongation after surgical repair. The aim... (Randomized Controlled Trial)
Randomized Controlled Trial
The Ruptured Achilles Tendon Elongates for 6 Months After Surgical Repair Regardless of Early or Late Weightbearing in Combination With Ankle Mobilization: A Randomized Clinical Trial.
BACKGROUND
Treatment strategies for Achilles tendon rupture vary considerably, and clinical outcome may depend on the magnitude of tendon elongation after surgical repair. The aim of this project was to examine whether tendon elongation, mechanical properties, and functional outcomes during rehabilitation of surgically repaired acute Achilles tendon ruptures were influenced by different rehabilitation regimens during the early postsurgical period.
HYPOTHESIS
Restricted early weightbearing that permits only limited motion about the ankle in the early phase of tendon healing limits tendon elongation and improves functional outcome.
STUDY DESIGN
Randomized controlled trial; Level of evidence, 1.
METHODS
75 consecutive patients with an acute Achilles tendon rupture were included. They underwent surgical repair, and tantalum beads were placed in the distal and proximal parts of the tendon; thereafter, the patients were randomized into 3 groups. The first group was completely restricted from weightbearing until week 7. The second group was completely restricted from weightbearing until week 7 but performed ankle joint mobilization exercises. The first and second groups were allowed full weightbearing after week 8. The third group was allowed partial weightbearing from day 1 and full weightbearing from week 5. All patients received the same instructions in home exercise guidelines starting from week 9.
RESULTS
The rehabilitation regimen in the initial 8 weeks did not significantly influence any of the measured outcomes including tendon elongation. Achilles tendon elongation and tendon compliance continued for up to 6 months after surgery, and muscle strength, muscle endurance, and patient-reported functional scores did not reach normal values at 12 months.
CONCLUSION
Differences in rehabilitation loading pattern in the initial 8 weeks after the repair of an Achilles tendon rupture did not measurably alter the outcome. The time to recover full function after an Achilles tendon rupture is at least 12 months. Registration: NCT02422004 ( ClinicalTrials.gov identifier).
Topics: Achilles Tendon; Adolescent; Adult; Aged; Ankle; Biomechanical Phenomena; Early Ambulation; Exercise Therapy; Follow-Up Studies; Humans; Middle Aged; Movement; Muscle Strength; Patient Reported Outcome Measures; Rupture; Treatment Outcome; Weight-Bearing; Young Adult
PubMed: 29965789
DOI: 10.1177/0363546518781826 -
Physiological Research Dec 2021Arterial compliance is an important cardiovascular parameter characterizing mechanical and structural properties of arteries and significantly influencing... (Review)
Review
Arterial compliance is an important cardiovascular parameter characterizing mechanical and structural properties of arteries and significantly influencing ventricular-arterial coupling. Decreased arterial compliance is associated with several physiological states and pathological processes. Furthermore, arterial compliance is influenced by other cardiovascular parameters even at short time scales. Today, there are numerous noninvasive methods of estimation arterial compliance in vivo introducing some level of confusion about selection of the best method for particular application and measurement setting. In this review, the most common noninvasive methods of arterial compliance estimation are summarized, discussed and categorized. Finally, interpretation of estimated arterial compliance in the context of other possible confounders is discussed.
Topics: Arteries; Blood Pressure; Compliance
PubMed: 35199538
DOI: 10.33549/physiolres.934798 -
JSLS : Journal of the Society of... 2019Creating and maintaining a pneumoperitoneum to perform laparoscopy is governed by gas laws and the limiting physical constraints of the abdomen. (Review)
Review
BACKGROUND AND OBJECTIVES
Creating and maintaining a pneumoperitoneum to perform laparoscopy is governed by gas laws and the limiting physical constraints of the abdomen.
METHODS
A review of how gas, biomechanical and physical properties affect the abdomen and a systematic structured Medline and PubMed search was conducted to identify relevant studies related to the topic.
RESULTS
Abdominal compliance is a measure of ease of abdominal expansion and is determined by the elasticity of the abdominal wall and diaphragm. It is the change in intra-abdominal volume per change in intra-abdominal pressure. Caution should be exercised with pressures exceeding 12 millimeters mercury since this is defined as intra-abdominal hypertension.
CONCLUSIONS
Abdominal compliance has its limits, is unique for each patient and pressure-volume curves cannot be easily predicted. Using the lowest possible pressure to accomplish the surgical task without compromising surgical outcome is the desired goal. The clinical importance is caution and knowing there is a point where more pressure does not increase working space and only increases pressure.
Topics: Abdominal Cavity; Carbon Dioxide; Compliance; Humans; Insufflation; Laparoscopy; Pneumoperitoneum, Artificial; Pressure
PubMed: 30828242
DOI: 10.4293/JSLS.2018.00080 -
Medicine Feb 2019Hoffa fractures are coronal-plane fractures of the femoral condyle, which are rarer than sagittal-plane condylar fractures. This study aimed to systematically review the... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Hoffa fractures are coronal-plane fractures of the femoral condyle, which are rarer than sagittal-plane condylar fractures. This study aimed to systematically review the clinical knowledge base of Hoffa fractures to facilitate the diagnosis and management of such injuries.
METHODS
We searched Medline, Embase, Cochrane Library, Google Scholar, China National Knowledge Infrastructure, and China Biology Medicine disc, using the terms "Hoffa fracture" and "coronal fracture of femoral condyle."
RESULTS
One hundred five articles on Hoffa fractures were reviewed, and the clinical knowledge base was summarized. High-energy trauma is a common cause of a Hoffa fracture, although low-energy trauma and iatrogenic injury can also lead to these fractures. Commonly used classifications include the Letenneur classification, a computed tomography (CT) classification, the AO classification, and modified AO classification. Radiography can reveal fracture lines. If radiographic findings are negative in questionable cases, CT and magnetic resonance imaging (MRI) should be performed. Nondisplaced fractures can be managed conservatively; however, they involve a high risk of redisplacement. Open reduction and internal fixation are preferred. For young patients with good compliance, simple medial or lateral condylar fractures can be treated via a medial or lateral parapatellar approach. After fracture exposure, headless compression screws can be inserted perpendicularly to the fracture line from posterior to anterior. For bicondylar fractures, a median parapatellar incision can be used. For complex fractures in patients with osteoporosis or a high body mass index, cannulated screws with antigliding plate fixation should be used.
CONCLUSION
Here, we summarized the injury mechanism, diagnosis, classification, and treatment options of Hoffa fractures.
Topics: Biomechanical Phenomena; Disease Management; Femoral Fractures; Femur; Fracture Fixation; Humans; Knee Injuries; Patient Selection; Tomography, X-Ray Computed
PubMed: 30813201
DOI: 10.1097/MD.0000000000014633 -
Sports Health 2017Foot and ankle injuries are common in sports, particularly in cleated athletes. Traditionally, the athletic shoe has not been regarded as a piece of protective equipment... (Review)
Review
BACKGROUND
Foot and ankle injuries are common in sports, particularly in cleated athletes. Traditionally, the athletic shoe has not been regarded as a piece of protective equipment but rather as a part of the uniform, with a primary focus on performance and subjective feedback measures of comfort. Changes in turf and shoe design have poorly understood implications on the health and safety of players.
EVIDENCE ACQUISITION
A literature search of the MEDLINE and PubMed databases was conducted. Keywords included athletic shoewear, cleated shoe, football shoes, and shoewear, and search parameters were between the years 2000 and 2016.
STUDY DESIGN
Clinical review.
LEVEL OF EVIDENCE
Level 5.
RESULTS
The athletic shoe is an important piece of protective sports equipment. There are several important structural considerations of shoe design, including biomechanical compliance, cleat and turf interaction, and shoe sizing/fit, that affect the way an athlete engages with the playing surface and carry important potential implications regarding player safety if not understood and addressed.
CONCLUSION
Athletic footwear should be considered an integral piece of protective equipment rather than simply an extension of the uniform apparel. More research is needed to define optimal shoe sizing, the effect that design has on mechanical load, and how cleat properties, including pattern and structure, interact with the variety of playing surfaces.
Topics: Ankle Injuries; Biomechanical Phenomena; Equipment Design; Foot Injuries; Football; Humans; Shoes
PubMed: 28151702
DOI: 10.1177/1941738117690717 -
Acta Bio-medica : Atenei Parmensis Sep 2021The incidence of pelvic and acetabular fractures is increasing during the years, counting 37 pelvic fractures per 100000 people annually. No weight bearing or toe touch... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND AND AIM OF THE WORK
The incidence of pelvic and acetabular fractures is increasing during the years, counting 37 pelvic fractures per 100000 people annually. No weight bearing or toe touch weight bearing are usually chosen in the initial management to allow fracture and ligamentous healing and avoid fracture displacement and fixation failure. On the other hand, early weight bearing may stimulate fracture healing and allow prompt functional recovery, faster return to work and recreational activities and reduce complications linked to late rehabilitation. Aim of the study is to review the literature about weight bearing indications for pelvic and acetabular fractures to highlight clinical and biomechanical evidence supporting early weight bearing.
METHODS
Two independent reviewers independently extracted studies on early weight bearing of pelvic and acetabular fractures. All selected studies were screened independently based on title and abstract. Then the full text of any article that either judged potentially eligible was acquired and reviewed again. Any disagreement was resolved by discussing the full text manuscripts.
RESULTS
44 studies including reviews, meta-analysis, clinical and biomechanical studies were selected.
CONCLUSIONS
Despite biomechanical data, few clinical evidences can be found to support early weight bearing in pelvic and especially acetabular fractures treatment. The promising results of some clinical experiences, however, should direct further studies to clearly define the indications and limits of early weight bearing in these injuries. Recognizing intrinsic lesion stability and bone and fixation technique quality, together with patient age and compliance, should be the mainstay for post-operative management choice.
Topics: Acetabulum; Fracture Fixation, Internal; Fractures, Bone; Humans; Pelvic Bones; Weight-Bearing
PubMed: 34487095
DOI: 10.23750/abm.v92i4.10787