UMEM Educational Pearls

Peritonsillar Abscess 

 

  • Ultrasound can differentiate abscess vs cellulitis and has been shown to increase EP success of drainage as well as lower CT use. If you are concerned about complicated PTA with extension, use your clinical judgment.
  • Let’s give a shout out to Kelsey Johnson and Karl Dachroeden who successfully identified and drained a PTA at bedside as well as Taylor Miller who had a difficult case of phlegmon vs early abscess.

Show References


Category: Orthopedics

Title: Blount's disease

Keywords: Varus, knee (PubMed Search)

Posted: 5/15/2022 by Brian Corwell, MD (Updated: 5/17/2022)
Click here to contact Brian Corwell, MD

4-year-old patient comes to the ED for an unrelated complaint and you notice that his knees appear to be touching while his ankles remain apart.

 

Genu Varum or “knock knees” may be caused by Infantile Blount’s disease

          -A progressive pathologic condition causing genu varum in children between ages 2 to 5

          - Centered at the tibia

          -Bilateral in up to 80%

          -More common in boys

          -Leg length discrepancy

          - Articular incongruity

Risk factors:  Early walkers (<1 year), overweight, large stature, Hispanic and African American

Results in disruption of normal cartilage growth at the MEDIAL aspect of the proximal tibia while LATERAL growth continues normally

May complain of knee soreness or subjective instability

On physical exam

          Focal angulation of the proximal tibia

Lateral thrust during stance phase of walking (brief lateral shift of proximal fibula and tibia)

          No tenderness or effusion

Imaging:   Plain film shows varus deformity of the proximal tibia with medial beaking (beak like appears of bone) and downward slope of the proximal tibia metaphysis (increased metaphyseal-diaphyseal angle)

 

https://paleyinstitute.org/wp-content/uploads/blounts1.jpg

Treatment depends upon the age of the child and the severity

  1. Medial unloader braces (should be started by age 3)

Successful in up to 80%

  1. Surgical correction (tibial osteotomy or growth plate arrest surgery)

Note: In adolescent variant bracing is ineffective and surgery is only treatment

          : Genu varum is normal in children <2 years old and becomes neutral at 14 months

 

DDX: Physiologic varus, Rickets

 

 

 


With the low supply of IV contrast for CT’s remember that you can use your friendly ultrasound to help you diagnose a wide range of pathology. Most often there is a HIGH SPECIFICITY (so if you see it, it is probably there but not a rule out test). Over the next week we will look at  5 cases where residents have diagnosed cool pathology using ultrasound. Just remember that with great power, comes great responsibility
 
 
 
 
 
 
 

 

Appendicitis

  • Ultrasound has a reported high specificity (97.9) for acute appendicitis in moderate to high pre-test probability of patients.

  • Let’s give a shout out to Reed Macy, who diagnosed appendicitis in a male with vomiting and abdominal pain! 

 


A recent prospective cohort study investigated the effect of low-dose droperidol on QTc in an emergency department:

  • 68 patients
  • Droperidol dose: median 1.875 mg (range: 0.625-2.5 mg)
  • Given as a 2-minute bolus
  • 94.1% received for headache management
  • Mean change in QTc: +29.9 ms (SD 15)
  • 17.6% (n=12) experienced QTc interval >=500 ms
  • 4.4% (n=3) had a change >=+60 ms
  • No serious arrhythmias or deaths
  • 13.2% (n=9) had at least one non-serious event (restlessness and/or anxiety)


Low-dose droperidol has a small effect on QTc and most patients remained below 500 ms.

Show References


Category: Pediatrics

Title: Environment Modifications for Autism in the ED

Keywords: autism spectrum disorder, neurodevelopmental disorder (PubMed Search)

Posted: 5/6/2022 by Rachel Wiltjer, DO (Updated: 5/17/2022)
Click here to contact Rachel Wiltjer, DO

 

  • Autism spectrum disorder and other neurodevelopmental disorders can predispose to challenging ED encounters secondary to difficulties with sensory processing and communication
  • Small changes to the environment can help to reduce stress, generally by decreasing stimulation
  • Use quieter areas of the ED when possible, decrease volume of alarms, and consider noise cancelling headphones or white noise if available
  • Consider dimming the lights, turning the monitor/computer screen away from the patient
  • Allow the patient to remain in their own clothing and consider whether restrictive items such as the monitor, pulse oximeter, and blood pressure cuff are necessary (but continue to use them when they are medically appropriate)
  • Offering distraction via electronics, fidget toys, or weighted blanket (or lead apron) may help with managing stress
  • Ask the patient or family which modifications would be helpful for the patient and ask child life for assistance where available

 

Show References


Category: Critical Care

Title: Adding Vasopressin and Steroids to the Code Cocktail? Not so fast...

Keywords: in-hospital cardiac arrest, IHCA, resuscitation, code, epinephrine, vasopressin, methylprednisolone (PubMed Search)

Posted: 5/2/2022 by Kami Windsor, MD (Emailed: 5/3/2022)
Click here to contact Kami Windsor, MD

Takeaways

 

Based on prior studies1 indicating possibly improved outcomes with vasopressin and steroids in IHCA (Vasopressin, Steroids, and Epi, Oh my! A new cocktail for cardiac arrest?), the VAM-IHCA trial2 compared the addition of both methylprednisolone and vasopressin to normal saline placebo, given with standard epinephrine resuscitation during in hospital cardiac arrest (IHCA).

The use of methylprednisolone plus vasopressin was associated with increased likelihood of ROSC: 42% intervention vs. 33% placebo, RR 1.3 (95% CI 1.03-1.63), risk difference 9.6% (95% CI 1.1-18.0%); p=0.03.

BUT there was no increased likelihood of favorable neurologic outcome (7.6% in both groups).

Recent publication on evaluation of long-term outcomes of the VAM-ICHA trial3 showed that, at 6-month and 1-year follow-up, there was no difference between groups in:

  • Survival
  • Favorable neurologic outcome (CPC 1 or 2; mRS 0-3)
  • Health-related quality of life (per EQ-5D5L survey)

 

Bottom Line: Existing evidence does not currently support the use of methylprednisolone and vasopressin as routine code drugs for IHCA resuscitation. 

Show More In-Depth Information

Show References


Category: Orthopedics

Title: Panner's disease

Keywords: Elbow, osteochondritis, capitellum (PubMed Search)

Posted: 4/23/2022 by Brian Corwell, MD (Updated: 4/24/2022)
Click here to contact Brian Corwell, MD

9-year-old male left hand dominant, presents with left elbow pain.

 He is a future “star pitcher,” says his coach dad. “Doc, I bet you didn’t know that although only 10% of people throw with their left hand almost a 1/3rd of MLB pitchers are lefties. He is 3x more likely than a righty to pitch in MLB.” “Maybe I’m asking him to throw too much.”

Hx: Lateral elbow pain and “stiffness” worse with activity that is better with rest

PE:  Lateral elbow tenderness (capitellum) with slight (approx. 20 degrees) decreased loss of extension. Minimal swelling noted.

Dx: Panner's disease refers to osteochondrosis of the capitellum (similar to Legg Calve Perthes). Likely due to AVN from repetitive trauma. May also be due to endocrine disturbances.

Affects the dominant elbow of boys between the ages of 5 and 10

Associated with the repetitive trauma of throwing or gymnastics.

Must be differentiated from osteochondrosis dissecans which occurs in the older child >13yo when the ossification of the capitellum is complete

Radiology

The articular surface of the capitellum may appear irregular or flattened with areas of radiolucency (43%). Loose bodies not seen with Panners, much more likely with OCD lesions.

Treatment:  Ice and NSAIDs. Avoid pitching/gymnastics etc. until full radiographic and clinical healing. If significant pain and/or swelling place patient in long arm posterior splint for 7-10 days. Resolution may take several months and up to one year.

 

 


ED Low-Tidal Volume Ventilation

  • Low-tidal volume ventilation (LTVV) reduces mortality in patients with ARDS and may reduce mortality in patients without ARDS.
  • Recent literature has highlighted the importance of initial ED ventilator settings, as these often persist for many hours after ICU admission.
  • But..does the use of LTVV in the ED really make a difference?
  • A recent systematic review and meta-analysis sought to evaluate the use of LTVV in the ED and the impact upon clinical outcomes.
  • In short, the use of LTVV in the ED was associated with an increase in the use of LTVV in the ICU, decreased occurrence of ARDS after admission, shorter ICU and hospital lengths of stay, decreased duration of mechanical ventilation, and decreased mortality.
  • Take Home Point:  The use of LTVV in the ED makes a difference!

Show References


In 2013, the Pediatric Emergency Care Applied Research Network developed a prediction rule to identify patients who were at low risk of requiring acute intervention after blunt abdominal trauma.  Interventions included laparotomy, embolization, blood transfusion or IV fluids for more than 2 nights with pancreatic or bowel injuries.
If ALL of the following are true, the patient is considered very low risk (0.1%) of needing an acute abdominal intervention:  
- No evidence of abdominal wall trauma or seat belt sign
- GCS 14 or 15
- No abdominal tenderness
- No thoracic wall trauma
- No abdominal pain
- No decreased breath sounds
- No vomiting
 
This prediction rule was externally validated in 2018 showing a sensitivity of 99%.  This rule should be used to decrease the rate of CT scans of the abdomen following blunt trauma.

Show References


Category: Orthopedics

Title: Concussion and Mental Health in Pediatric Patients

Keywords: Concussion, psychiatric, hospitalization (PubMed Search)

Posted: 4/9/2022 by Brian Corwell, MD
Click here to contact Brian Corwell, MD

A recent study investigated the association between concussion and subsequent mental health conditions in a pediatric population.

Retrospective cohort study. Pediatric patients aged 5 to 18 years who presented to an ED, PCP or mental health practitioner from April 2010, to March 2020, in Ontario, Canada. 

Primary outcome: Time to first diagnosis with a mental health condition during follow-up

Secondary outcomes: 1) self-harm 2) psychiatric hospitalization 3) death by suicide.

Mental health conditions: anxiety and neurotic disorders, adjustment reactions, behavioral disorders, mood and eating disorders, schizophrenia, substance use disorder, suicidal ideation, and disorders of psychological development.

Study group, almost 450,000 patients. Age and sex matching between those with concussion and those who experienced an orthopedic injury. 

A significant association (P < .001) was found between concussion and mental health conditions

A significant association emerged between concussion and self-harm and psychiatric hospitalization 

No association with suicide

Conclusion: Concussion was significantly associated with risk of mental illness, psychiatric hospitalization and self-harm but not death by suicide.

Concussed patients had an almost 40% higher rate of mental health conditions compared to controls (adjusted hazard ratio 1.39)

Take home: Screen patients who return to the ED with post concussive symptoms for mental health symptoms/concerns and provide appropriate awareness for parents

 

 

 

Show References


Category: Critical Care

Title: APRV or Low Tidal Volume Strategy for patients with COVID-19

Keywords: APRV, low tidal volume, COVID-19 (PubMed Search)

Posted: 4/5/2022 by Quincy Tran, MD (Updated: 5/17/2022)
Click here to contact Quincy Tran, MD

During the height of the pandemic, a large proportion of patients who were referred to our center for VV-ECMO evaluation were on Airway Pressure Release Ventilation (APRV).  Does this ventilation mode offer any advantage?  This new randomized control trial attempted to offer an answer.

---------------

1.Settings: RCT, single center

2. Patients: 90 adults patients with respiratory failure due to COVID-19

3. Intervention: APRV with maximum allowed high pressure of 30 cm H20, at time of 4 seconds.  Low pressure was always 0 cm H20, and expiratory time (T-low) at 0.4-0.6 seconds. This T-low time can be adjusted upon analysis of flow-time curve at expiration.

4. Comparison: Low tidal volume (LTV)  strategy according to ARDSNet protocol.

5. Outcome: Primary outcome was Ventilator Free Days at 28 days.

6.Study Results:

  • Baseline characteristics were similar. At randomization, PF ratio for APRV group = 140 (SD 42) vs. 149 (SD 50) for LTV group.
  • Median Ventilator Free Day for APRV group: 3.7 [0-15] days vs. 5.2 [0-19] for LTV group ( P = 0.28)
  • APRV group had higher PaO2/FiO2 ratio during first 7 days (mean difference = 26, P<0.001)
  • ICU length of stay for APRV group: 9 [7-16] vs. 12 [8-17] days (P = 0.17)
  • Severe hypercapnia (Pco2 at ≥ 55 along with a pH < 7.15): APRV group = 19 (42%) vs. LTV = 7 (15%), P = 0.009.
  • Death at 28 days: 35 (78%) for APRV group, vs. 27 (60%) for LTV group ( P = 0.07)

7.Discussion:

  • Hypercapnea was transient and was mostly due to implementation of the ventilator settings.  The protocol recommended reduction of T-high to allow more ventilation, but most clinicians did not want to shorten the T-High, but instead opted for higher T-low.
  • Although the number of barotrauma were similar in both group, all 4 cases of barotrauma in the APRV group occurred within a very short period of time (3 weeks), prompted the safety monitoring board to recommend stopping recruitment for COVID-19 patients.

8.Conclusion:

APRV was not associated with more ventilator free days or other outcomes among patients with COVID-19, when compared to Low Tidal Volume strategies in this small RCT.

 

Show References


Category: Pharmacology & Therapeutics

Title: To B or Not to B: B52 v 52 for Acute Agitation

Keywords: haloperidol, agitation, sedation (PubMed Search)

Posted: 4/2/2022 by Ashley Martinelli (Updated: 5/17/2022)
Click here to contact Ashley Martinelli

Diphenhydramine (B) has historically been utilized in combination with haloperidol 5mg (5) and lorazepam 2mg (2) in the treatment of acute agitation.  The most common rationale for adding diphenhydramine is prevention of EPS, however literature to support this is lacking.  A recently published paper examined diphenhydramine/haloperidol/lorazepam combination (B52) vs haloperidol/lorazepam combination therapy (52) to compare the need for additional agitation treatments as a surrogate for clinical efficacy.

 

This retrospective, multicentered noninferiority study included 400 emergency medicine patients, 200 per treatment arm. On average, the patients were 40 years old, 64% male, and predominantly Caucasian.  More patients in the B52 group had psychiatric illness listed as their primary cause for agitation compared to the 52 group. The two most frequently reported substances on urine drug screens, if collected, were amphetamines (35%) and cannabinoid (35.5%).

 

Results:

-No difference in the use of additional agitation medications within 2 hours

-More patients in the 52 group were noted to receive anticholinergic medications within 2 days, but indications varied and were not associated with EPS treatment

 

The B52 combination was associated with:

---Increased length of stay 17 h (10-26) vs 13.8 h (9-12), p = 0.03

---Increased use of restraints 43% vs 26.5%, p = 0.001

---Hypotension 16% vs 3.5%, p <0.001

---Use of nasal canula oxygen 3% vs 0%, p < 0.01

 

The addition of diphenhydramine may not be necessary to prevent EPS in patients receiving haloperidol for agitation and is associated with increased length of stay and adverse events, likely due to its additive sedative properties. 

Show References


Category: Pediatrics

Title: Organic Acidemias - What you Need to Know in the ED

Keywords: inborn error of metabolism (IEM), organic acidemia (PubMed Search)

Posted: 4/1/2022 by Rachel Wiltjer, DO (Updated: 5/17/2022)
Click here to contact Rachel Wiltjer, DO

 

  • 2/3’s present in the neonatal period and can mimic conditions such as sepsis, gastroenteritis, and meningitis requiring careful consideration to prompt testing
  • Common symptoms are poor feeding, lethargy, irritability, vomiting, and encephalopathy
  • May be referred in if detected on newborn screen, but not all are tested on the newborn screen
  • Should look on labs for acidosis, elevated anion gap, hyperammonemia, lactic acidosis, ketosis/ketonuria, and hyper/hypoglycemia  
  • Emergent treatment includes: identification and treatment of any underlying triggers (such as infection), stopping any protein intake until situation can be clarified, providing fluids with glucose (requirements of 8-10 mg/kg/min of glucose in neonates), and genetics consultation

 

Show References


Category: Critical Care

Title: Epinephrine versus norepinephrine in cardiac arrest patients with post-resuscitation shock

Keywords: OHCA, shock, epinephine, norepinephrine, cardiac arrest (PubMed Search)

Posted: 3/23/2022 by William Teeter, MD (Updated: 5/17/2022)
Click here to contact William Teeter, MD

The use of catecholamines following OHCA has been a mainstay option for management for decades. Epinephrine is the most commonly used drug for cardiovascular support, but norepinephrine and dobutamine are also used. There is relatively poor data in their use in the out of hospital cardiac arrest (OHCA). This observational multicenter trial in France enrolled 766 patients with persistent requirement for catecholamine infusion post ROSC for 6 hours despite adequate fluid resuscitation. 285 (37%) received epinephrine and 481 (63%) norepinephrine.

Findings

  • Deaths from refractory shock (35% vs. 9%, P<0.001) and Recurrent cardiac arrest (9% vs. 3%, P<0.001) were higher in the epinephrine group
  • In both univariate/multivariate analyses, use of epinephrine was significantly associated with:
    • All-cause mortality during the hospital stay (83% vs. 61%, P<0.001) / (OR 2.6, 95%CI 1.4–4.7, P=0.002)
    • Cardiovascular-specific mortality (44% vs. 11%, P<0.001) / (aOR 5.5, 95%CI 3.0–10.3, P<0.001)
    • Frequency of unfavorable neurological outcomes (37% vs. 15%, P<0.001) / (aOR 3.0, 95%CI 1.6–5.7, P=0.001)
  • While propensity scoring and match analysis largely confirmed these findings, further regression did not associate epinephrine with all-cause mortality.

Limitations:

  • Epinephrine arm: significantly longer time to ROSC, lower blood pH at admission, higher rates of unshockable rhythm, higher levels of arterial lactate at admission, lower LV ejection fraction, and higher levels of myocardial dysfunction.
  • Propensity matching always has the potential for confounders.

Summary:

Norepinephrine may be a better choice for persistent post-arrest shock. However, this study is not designed to sufficiently address confounders to recommend abandoning epinephrine altogether, but it does give one pause. 

Show References


In emergency departments in the US, the diagnosis of pneumonia is often made on chest xray.  In the outpatient setting, national guidelines focus on the clinical diagnosis of pneumonia and recommend against radiographs.  This study aimed to develop and validate a clinical tool that could be used to determine the risk of radiographic pneumonia.
The criteria in the Pneumonia Risk Score (PRS) evaluate for the presence of fever, rales, and wheeze and take into account age and triage oxygen saturation.  When developing this protocol, the investigators compared the patients who had pneumonia on chest xray with both clinical judgment and the PRS.  The PRS outperformed clinical judgment in predicting which patients would have pneumonia on chest xray.
Children who have a score of 2 or less were unlikely to have pneumonia on chest xray and would qualify for observation without an xray or empiric antibiotics use.  Children who had a score of 5 or greater were likely to have radiographic pneumonia and could be empirically treated with antibiotics. If the PRS score was 6, the specificity was 99.9%
This link https://links.lww.com/INF/E552. takes you to the excel spreadsheet where you can enter the patients clinical data and gives you a present probability of radiographic pneumonia.  (In case the link does not work, it is also found in the supplemental digital content.)
Bottom line: PRS outperforms clinical judgment when determining if pneumonia will be present on the pediatric chest xray.

Show References


Category: Critical Care

Title: Acute liver failure

Posted: 3/15/2022 by Duyen Tran, MD (Updated: 5/17/2022)
Click here to contact Duyen Tran, MD

Acute liver failure is defined as new and rapidly evolving hepatic dysfunction associated with neurologic dysfunction and coagulopathy (INR >1.5). Most common cause of death in these patients are multiorgan failure and sepsis. Drug-induced liver injuy most common cause in US, with viral hepatitis most common cause worldwide.

Management of complications associated with acute liver failure

  • Hepatic encephlopathy: Administer lactulose orally or via enema if risk of aspiration. Goal is to slow progression to severe encephalopathy and minimize development of cerebral edema.
  • Coagulopathy: Reverse if significant bleeding or if patient needs to have invasive procedure. FFP and 4-factor PCC not indicated in absence of bleeding. Additionally these patients may be vitamin-K deficient for which vitamin K can be given.
  • Consider empiric antibiotics due to increased susceptibility to infection.
  • Renal dysfunction: correct hypovolemia with fluid resuscitation. May require RRT, continuous preferred for hemodynamic stability.
  • If persistent hypotension despite adequate volume resuscitation and pressors, IV hydrocortisone indicated as adrenal insufficiency is common in these patients.
  • Early consultation with liver transplant center. King's College Criteria and MELD score are most commonly used prognostic tools.

Show References


Treatment of Hamstring Strains in Athletes

 

28 year old athlete presents to the ED and diagnosed with a hamstring strain

Localized swelling, moderate pain and a small limp. Incomplete tearing of the muscle

He is worried that he will miss the remainder of his season and when he returns will reinjure the same hamstring

Consider referral to sports medicine/orthopedics

A recent study looked at use of ultrasound guided hematoma aspiration followed by platelet-rich plasma (PRP) treatment on recovery in acute hamstring injuries

55 male athletes between ages 18 -32 weighing between 170 and 260lbs

27 with treatment protocol plus rehabilitation and 28 treated conservatively (rehabilitation)

All had Grade 2 hamstring injuries diagnosed on MRI

                Partial muscle tear (<50% cross sectional area)

Note: Grade 2 hamstring injuries are often associated with INTERmuscle hematoma and subsequent scarring. This can lead to persistent pain/discomfort and reinjury

Average return to play time was 32.4 days in the standard of care group

Average return to play time was 23.5 days in the intervention group (P<0.001)

Recurrence rate of hamstring strain was 28.6% in the standard of care group

Recurrence rater of hamstring strain was <4% in the intervention group (P=0.025)

 

Athletes with grade 2 hamstring injuries treated with hematoma aspiration and PRP injection into the strain had significantly shorter return-to-play and much lower recurrence rate that athletes treated with rehabilitation alone

 

Show References


Category: Pediatrics

Title: SCIWORA in Pediatric Trauma Patients

Keywords: SCIWORA, trauma, pediatrics, myelopathy (PubMed Search)

Posted: 3/4/2022 by Natasha Smith, MD
Click here to contact Natasha Smith, MD

Pediatric spines are elastic in nature.

SCIWORA is a syndrome with neurological deficits without osseous abnormality on XR or CT.

Many patients with SCIWORA have myelopathy.

Mechanism of injury: Most commonly caused by hyperextension or flexion. Other possible mechanisms include rotational, lateral bending, or distraction.

Population: More common in younger children. This comprises 1/3 of pediatric trauma cases that have neuro deficits on exam. 

Severity depends on degree of ligamentous injury. It can be mild to severe, and cases have the potential to be unstable. 

Management: Immobilize cervical spine and consult neurosurgery. Patients often need prolonged spinal immobilization.

If the patient is altered and an adequate neurological exam cannot be obtained, a normal CT or XR of the cervical spinal is not sufficient to rule out spinal cord injury. It is important to continue monitoring neurological status. One possible etiology is spinal cord hemorrhage, and serial exams are essential. 

Show References


How to set the correct PEEP remains one of the most controversial topics in critical care.  In fact, just on UMEM Pearls there are 55 hits when one searches for PEEP, including this relatively recent pearl on PEEP Titration.  

A recent Systematic Review and Network Meta-Analysis looked at existing trials on this issue.  They found that:

1) Higher PEEP strategies were associated with a mortality benefit compared to lower PEEP strategies

2) Lung Recruitment Maneuvers were associated with worse mortality in a dose (length of time of the maneuver) dependent fashion.

This fits with recent literature and trends in critical care and bolsters the feeling many intensivists are increasingly having that we may be under-utilizing PEEP in the average patient.  

Bottom Line: As an extremely broad generalization, we would probably benefit the average patient by favoring higher PEEP strategies, and avoiding lung recruitment maneuvers.  Do keep in mind that it is probably best to continue lower PEEP strategies in patient populations at high risk of negative effects of PEEP (e.g. COPD/asthma, right heart failure, volume depleted with hemodynamic instability, bronchopleural fistula) until these groups are specifically studied.

Show References


Category: Orthopedics

Title: Imaging of Knee OA

Keywords: knee osteoarthritis, plain film (PubMed Search)

Posted: 2/26/2022 by Brian Corwell, MD (Updated: 5/17/2022)
Click here to contact Brian Corwell, MD

The knee is one of the most commonly affected joints from osteoarthritis (OA).

Patients will complain of knee pain, swelling and stiffness.

This leads to disability as it interferes with walking, using stairs at home and getting in and out of chairs and the bath without assistance.

Increasing incidence due to aging of the general population and rising rates of obesity.

Patients frequently present to the ED for knee pain and imaging is often obtained.

Diagnosis of knee OA can be made with an appropriate history and imaging that shows osteophytes and joint space narrowing.

The best views for knee OA include 1) PA weight-bearing & 2) 45 degree of knee flexion

https://d3i71xaburhd42.cloudfront.net/6f8ce215fb4bcd153a478187c9a6a2ae652a5fc4/250px/1-FigureI-1.png

 

Note: Weight-bearing radiographs will demonstrate greater joint space narrowing than non-weight-bearing radiographs

Of the 3 compartments of the knee, the medial tibiofemoral compartment is most commonly affected > patellofemoral compartment > lateral tibiofemoral compartment.

 

Examples of knee OA

https://roberthowells.com.au/wp-content/uploads/2016/04/A00212F02.jpg

 

https://orthoinfo.aaos.org/link/e7e6933819db4020bc2f3822c45c538f.aspx