Poller screws, also known as blocking screws, are non-interlocking screws placed outside an intramedullary nail to improve fracture reduction and fixation. They provide a more rigid construct by serving as a surrogate cortex where nail-cortex contact is insufficient. Their placement helps centralize the guidewire in the medullary canal and maintains reduction through a blocking effect. While there is no consensus on their exact placement, they are generally inserted on the concave side of expected deformities to prevent malalignment during nailing.
Deformity: It’s the position of a limb/Joint, from which it cannot be brought back to its normal anatomical position.
Described as abnormalities of :
Length
Angulation
Rotation
Translation
Combination
a simplified version of periprosthetic fractures, easy to learn and understand with lots of images and classification. It includes hip, shaft of femur, knee, shoulder
Deformity: It’s the position of a limb/Joint, from which it cannot be brought back to its normal anatomical position.
Described as abnormalities of :
Length
Angulation
Rotation
Translation
Combination
a simplified version of periprosthetic fractures, easy to learn and understand with lots of images and classification. It includes hip, shaft of femur, knee, shoulder
Intertrochanteric Fractures: Ten Commandments for How to Get Good Results wit...Vivek Jadawala
Shivashankar, B., Keshkar, S. Intertrochanteric Fractures: Ten Commandments for How to Get Good Results with Proximal Femoral Nailing. JOIO 55, 521–524 (2021). https://doi.org/10.1007/s43465-021-00373-x
The Begg light-wire appliance remains unique in the history of orthodontic innovation. Whereas many current self-ligating bracket appliances purport to be low friction or friction free, it is the Begg appliance that best exemplifies low friction, free sliding mechanics.
By creating only a single point of contact between the bracket and the arch-wire Dr Begg was able to greatly decrease resistance to sliding, both by reducing friction between the bracket and the arch-wire and virtually eliminating the binding of the arch-wire in the bracket slot, as is seen in all horizontal slot brackets.
Begg’s bracket design allowed teeth to freely tip mesially and distally as well as lingually and labially. This often gave teeth the appearance of being over tipped during treatment and required considerable diligence by Begg practitioners to keep tooth movement under control.
This freedom of tooth movement allowed unprecedented correction of large overbites and overjets to an edge-to-edge position and rapid closure of extraction spaces by initially tipping the adjacent teeth into the extraction site and uprighting the teeth afterwards.
Individual tooth root correction was managed by the use of fine springs that were designed, and often individually crafted to upright, torque and rotate teeth into their correct positions once the position of tooth crowns had been established.
One key advantage of the appliance set up was the use of light elastic forces for the correction of anterior overbites and overjets. All anchorage could be established intra-orally without headgear, without the need for ancillary appliances such as trans-palatal arches, or needing to set up molar anchorage prior to treatment, as Dr Tweed advocated.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
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2. Learning objectives
• Understand the mechanical effects of poller screws
• Identify fracture patterns requiring poller screw augmentation
• Where to insert ??????
• How to insert ??????
3. Introduction
• Poller screw Aka “blocking screw”
• Non interlocking screw placed outside the nail
• Improve reduction and enhance fixation in intramedullary nailing
4. Etymology
• Term Blocking screw was first introduced by Donald and Seligson in
1983 – as they “block” the nail from malreducing the fracture
• In 1994 - Krettek et al. introduced the term ‘‘Poller screws’’
• Poller – German word meaning ‘‘bollard’’, a tubular structure used to
guide traffic
5. Mechanical characteristics
• More rigid construct
• Effectively serving as a surrogate cortex in areas with insufficient nail-
cortex contact
6. • Narrows the medullary canal
• Centralising the guide wire in the medullary canal
• Indirect fracture reduction
• Maintenance of reduction by “Blocking effect”
7. Adjunct to interlocking screws
• Interlocking screws - length and rotation
• Blocking screws - stability against translation and angulation
8. Metaphyseal / Meta-diaphyseal fractures
• Higher tendency of settling in to mal alignment following intramedullary nailing
1. Wide medullary canal - size discrepancy between diameters of nail and
medullary canal – translation of nail along IL screw possible
2. Poor nail to cortex contact – residual post fixation instability
3. Higher muscular forces acting on the smaller fragment
Krettek C, Schandelmaier P, Tscherne H (1995) Non-reamed interlocking nailing of closed tibial fractsoft tissue injury: Indications, technique and clinical
results. Clin Orthop 315:34- 47
Freedman EL, Johnson EE (1995) Radiographic analysis of tibial fracture malalignment following intramedullary nailing. Clin Orthop 315:25-33
9. • Saggital plane malreduction i.e. recurvatum or procurvatum-
controlled by medio laterally placed interlocking screws
• Coronal plane deformities i.e. varus and valgus are more
common
10. • Oblique fracture patterns or severe comminution
• Guide wire tend to follow the “path of least resistance”
• Tends to migrate to the site with less bone
11. Revision nailing for mal-aligned fracture
• Previously malplaced nail
• Previous tract prevents placement of the new nail into the correct
position as the nail may tend to slip again into the old nail path
• PS is placed to block the incorrect path
12.
13. Where to insert ??????
• Precise placement is necessary for optimal reduction
• False placement can exaggerate the deformity and may damage
reamer tip or nail
• Requires good pre - operative planning
14. • Stedtfeld et al
• Blocking screw in the short fragment close to the fracture on the
concave side of the axial deformity
• Around 1 cm below the fracture line
• 5 to 6 mm away from the centre of the medullary canal i.e. close to
the nail
Establishes third point of three-point fixation in the shorter fragment
15. • Why concave ?????????
• It is the site where the bone fails in compression hence causing more
comminution and bone loss
• Guide wire has the tendency to displace toward more comminuted
site
16. • Most of the other authors also have the same opinion ie to place it on the
cancave side of the expected deformity while avoiding the convex side
• Another description available in the literature is to place your blocking
screws where you don’t want your nail to go
Krettek C, Stephan C, Schandelmaier P, Richter M, Pape HC, Miclau T. The use of Poller screws as blocking screws in stabilising
tibial fractures treated with small diameter intramedullary nails. J Bone Joint Surg Br 1999;81:963–8.
Ricci WM, O’Boyle M, Borrelli J, Bellabarba C, Sanders R. Fractures of proximal third of the tibial shaft treated with
intramedullary nails and blocking screws. J Orthop Trauma 2001;15:264–70.
17. • More recently a new technique has been described by Hannah et al
• More objective description regarding site and sequence of screw
placement
• A. Hannah et al. / Injury, Int. J. Care Injured 45 (2014) 1011–1014
18. • Draw a line down the long axis
of the displaced, flared segment
of bone
• Then draw a second line along
the plane of the fracture
ensuring to bisect the first line
19. As nearly all
metaphyseal fractures
having a degree of
obliquity, this should
create 4 angles; 2 acute
and 2 obtuse
20. • For correct reduction the screws need to be placed in the acute angles on
the smaller metaphyseal fragment
21. • When the nail comes into contact with the screw the
course of the nail should be deflected so that the displaced
segment becomes reduced in the desired direction
22. • If a second screw is necessary
• should be placed in the other acute angle which will be nearer to the
isthmus
• It will have less effect but will potentiate the effect of the first screw
23.
24. Poller screw in Internal lengthening Nail
The short metaphyseal bone fragment
Deformities are usually predictable
Can be pre operative, intraoperative or post operative during lengthening
25. Reverse rule of thumb
• By Muthusamy et al
• To Decide the ideal locations of the blocking screws
1. Assess the deformity
2. Envision trying to manually correct the deformity by holding the bone with both
hands
Thumbs of both hands are placed on the convex side of the deformity near the
apex
Index fingers are placed away from the deformity on the concave side
3. Insert the blocking screws on the side of the nail OPPOSITE to where the thumbs
and index fingers are placed on the bone
26.
27. How to place ?????
• Ideally blocking screw should be placed before placing the
intramedullary guide wire
• Reaming should be done after the placement of blocking screw so
that reamer reams through the centre of the medullary canal
28. Complications
• Ill placed screw may cause damage to the reamers and the nail
• There is also a risk of screw bending, breakage and difficulty in
removal
• Difficulty in changing position of the screw
29. • A. Shahulhameed et al - 3.9 mm steinman pin in place of screw during
the process of nailing which was replaced by 5 mm interlocking screw
once nailing with desired reduction was done
• If the Steinman pin is correctly placed it will spin while reaming as the
reamer comes in contact with the Steinman pin
• Actual reduction of fragments can be seen in the fluoroscopy while
the reamers pass across the Steinman pin
30. • If the position of the Steinman pin is not satisfactory it is changed to a
more accurate position
• Fluoroscopic images during the reaming process are performed to
confirm the correct trajectory of the reamers
31. • The canal is reamed to 1.5 mm above the size of the nail
• Nail is introduced
• Proximal and distal locking is performed
• The Steinman pin is then removed and a 5-mm interlocking screw is
inserted in its place as a poller screw
32. Advantages
• It is easier to change the position of pin if found unsatisfactory during
reaming
• Steinman pin has a smooth surface so damage to the reamers and nail is
minimal
• The diameter of the Steinman pin is 3.9 mm which is ideal for a 5-mm
locking screw
• Because the poller screw is inserted at the end of the procedure the risk of
bending or breakage of the screws is also avoided
36. Take home messages
• Useful in preventing mal alignment in meta – diaphyseal fractures
• No clear consensus regarding accurate placement of blocking screw
• Proper pre operative planning and estimation of probable deforming forces
• Placement of poller screw where you don’t want your nail to go
• Most commonly the concave side but not universally true
• Depends on fracture pattern and comminution