Legal and Ethics
questions 45 and 49 are the same.
very bad where is direct bone healing
After application of a unilateral tibial external fixator, it is observed that the frame does not provide sufficient rigidity across the fracture site. Altering the external fixator in which of the following ways will have the greatest impact on frame stiffness?
Increasing the distance between pins in each fragment
Increasing the pin diameter
Reducing the distance between bone and connecting bar
Increasing the connecting bar diameter
Adding one stacked connecting bar
Excellent illustration "A" in discussion section.
In which of the following scenarios should a physician be relieved of their duties?
After 24 hours of continuous work
A significant error in care is noted
The physician appears fatigued
Physician is recovering from an ankle fracture
Chemical impairment is suspected
maybe clarify relieved i.e. fired or sent home to rest?
Neuropathic (Charcot) Joint of Shoulder & Elbow
"Indium-111 tagged WBC scan may present with false positives as WBCs can accumulate in during the acute and reparative phases of the Charcot process"https://www.presentdiabetes.com/ezines/index.php?action=viewPublication&nopopout=true&confirmOff=true&SearchText=&id=269&keepThis=true&TB_iframe=true&height=700&width=768&full=true
A 25-year-old male sustains an transverse humeral shaft fracture and undergoes open reduction and internal fixation with rigid compression plating. What kind of bone healing would be expected with this type of fracture fixation?
Primary bone healing through haversian remodeling
Secondary healing through callus formation
Primary healing through callus formation
Secondary healing through osteonal cutting cones
Dr. Dean - this question refers to the AO concepts of absolute and relative stability. The concepts remain valid and are still taught by the AO and other well-respected orthopaedic trauma groups. In a perfect world, the compression would be uniform and complete across the fracture, and healing would occur prior to any implant loosening, and therefore direct healing would occur. However, surgeons and/or fractures aren't always perfect, and there may be a bit of comminution at the fracture or an inadequate reduction to allow Haversian remodeling; alternatively, healing may be slow from a patient or surgeon etiology, and micromotion at the fracture would increase as the screws loosen a bit over time, thus leading to a bit of callus formation as expected.
Also, feel free to post links to the articles so the community can freely access them - this helps everyone learn.
Normal Bone Metabolism
((alone, because bone formation and resorption are coupled, it also indirectly decreases bone formation,(( the text above))?? does the estrogen decrease bone formation??
It's actually not correct. Even with rigid internal fixation the majority of healing will be indirect via callous, despite what the dogmatic preachings of AO say. See work of Shenck on this.
Retrograde RIA for femoral bone graft harvest
This is a video of the RIA device for a femoral bone graft harvest. This was done in a retrograde fashion to minimize risks associated with the RIA done in an antegrade fashion (proximal femur fx, abductor injury, etc).
5 out of 5 just for the double canister.
Very nice section. Consider adding to the pathoanatomy section, the concept of sluggish blood flow in metaphyseal sinusoids thought to be a risk factor for pediatric acute hematogenous osteomyelitis
Orthop Surg. 2011 Nov;3(4):268-70.
Charcot arthropathy of shoulder: a case report.Gaskins RB 3rd, Miller BJ, Scarborough MTOrthop Surg. 2011 Nov. doi: 10.1111/j.1757-7861.2011.00152.x. 3. (4). :268-70PMID: 22021145 (Link to Abstract)
RANK/RANKL/OPG Triad Pathway in Charcot Neuroarthropathy
The Receptor Activator for Nuclear Factor kappa B Ligand is believed to be an important molecule of bone metabolism. This is a natural and necessary surface-bound molecule on several types of cells, and serves to activate osteoclasts.Overproduction of RANKL is implicated in a variety of degenerative diseases. In patients with neuropathy, the RANKL/OPG pathway is thought to mediate the development of Neuropathic Osteoarthropathy or "Charcot Joint"An illustrative depiction of the RANKL pathway is as follows:Cellular stress or injury may result in expression of RANK Ligand on the surface of activated ostoblasts and T cells. In this example, an activated T cell is contacting a pre-osteoclast. Because this RANKL presenting cell is in an activated form, RANKL will become expressed, thus activate an uninhibited RANK receptor on the Surface of an Osteoclast.What is important to note, is that osteoprotegerin is a natural inhibitor of RANK and is thought to mediate a protective balance. Denosumab, and several other drugs, are being studied for their effects in preventing further transduction on the RANKL pathway and could prove to be useful in preventing disease progression.As the transduction cascade continues, IkB kinase is activated and subsequently phosphorylates the Inhibitor of kappa B, leaving Nuclear Factor kappa B free to diffuse uninhibited. Upon entering the nuclear membrane, Nuclear Factor kappa B will serve as a rapid-acting transcription factor, and will contribute to a variety of changes in gene expression.This gene expression, is correlated with the progression of Preosteoclastic species in becoming activated as osteoclasts. When the overproduction and/or expression of RANKL is seen, increased osteoclastogenesis will arise. Osteoclastogenesis is one of the fundamental elements in normal bone development and maturation.However, in Neuropathic Osteoarthropathy, over abundance of osteoclastic activity will result in osteopenia or bone wasting. With compromised bone strength, osteolysis and fragmentation will be observed.In addition to osseous destruction, the RANKL pathway has been correlated with macroangiopathic disfunction. The RANKL signaling pathway serves a regulatory role in the expression of bone matrix proteins in Vascular smooth muscle cells. A phenomenon that is naturally observed in many patients with Charcot joint destruction is vascular smooth muscle calcification. This presentation is often referred to as Monckeberg's arteriosclerosis.One important note is that neuropathic osteoarthropathy or "Charcot Foot" is seen in nearly every sort of disease that results in peripheral neuropathy. The exact mechanisms of this correlation are still not entirely understood, but neuropathic degeneration itself serves a presumable teleological role in permitting both an increase in blood flow and vascular permeability into the bone as well as a decreased sensation and detection of boney destruction in patients. When considering the supporting evidence of these two factors, the emergence of the indpendent, Neurovascular (French theory) and the Neurotraumatic (German theory), may possibly hold a similar etiology which is reflective of a common underlying cause. Because of the varying causes of peripheral neuropathy, the specific role the RANKL signal pathway merits more investigation at this time, and is needed to fully understand the process of neuropathic osteoarthropathy.When observing Charcot foot on a macro anatomic level, evidence of destruction may be visualized on plain film xray. Vascular calcification is reported in nearly 90% of all diabetics with Charcot foot, and is often seen prior to joint or bone involvement. As Charcot joint progresses through the acute phase, destruction and dislocation will be observed with severe osteopenia. Although this phase will eventually subside, resulting in a coalescence of fragments and overall stability of architecture, the foot is often permanently deformed.Deformations such as these, when accompanied by peripheral neuropathy and possible microangiopathological status, are often what lead to ulceration and infection. Although Neuropathic Osteoarthropathy is not directly responsible for the loss of limb or even death, the "Stairway to Amputation" is a perilous progression that must be curbed in all patients afflicted with this condition.
OPG binds to RANKL not RANK receptorhttps://www.ncbi.nlm.nih.gov/pubmed/17925190
Osteopenia & Osteoporosis
may someone throw some light on the modes of management of osteoporotic fractures in elderly?
Osteoarthritis Cartilage. 2013 Aug;21(8):1092-8. Epub 2013 May 13.
Figure A displays a schematic of the zones of articular hyaline cartilage. Which of the following zones has been shown to contain articular cartilage progenitor cells?
The lamina splendens is a film-like layer on the surface of the articular cartilage that can only be seen with electron microscopy. It is not considered one of the 3 histologic layers of articular cartilage. Its structure and function have not been clearly delineated, and it only serves as a distractor in this question.
It is still a matter of significant debate, and as it has not been tested, it has remained off of the review topic. Interestingly, it does not appear to reform even when autologous chondrocytes implantation yields othewrwise normal-looking cartilage, causing Anders Lindahl to describe the resulting tissue as "hyaline-like". This term has since been hijacked to describe other reparative tissues with much poorer histology, such as after microfracture.The layered structure of the articular surface.Fujioka R, Aoyama T, Takakuwa TOsteoarthritis Cartilage. 2013 Aug. pii: S1063-4584(13)00796-6. doi: 10.1016/j.joca.2013.04.021. 21. (8). :1092-8PMID: 23680879 (Link to Abstract)
Which of the following features of metal-on-metal total hip arthroplasty does not allow for improved fluid film lubrication between the components?
Larger femoral head
Slight clearance of fit between the acetabular cup and the femoral head
Minimal surface roughness of the femoral head
Complete congruence of fit between the acetabular cup and the femoral head
Minimal surface roughness of the acetabular cup
Cool; Thanks Dr. Taylor
Dr. Jones - I've updated the topic to better list the concept of this question. Thanks for the post.
Yes, but there is no discussion of the phenomenon in this question in that section. There is a section called "Forms of Lubrication" but nothing to help answer this question.