The authors have no acknowledgments.

This protocol follows the guidelines at BronxCare Health System. A written informed consent is necessary from the patient.
1. Identifying anatomical structures
<ol>
	<li>With the patient supine, carefully palpate the knee to locate the patella and use a skin marker to make marks at the four corners of the patella.</li>
	<li>Place an &#34;X&#34; using a skin marker at a site that is one fingerbreadth superolateral to the patella. Avoid infected skin and visible veins.</li>
	<li>If a large effusion is detected on examination and the patella appears to be sitting on fluid, consider a medial approach just posterior to the patella.</li>
</ol>
2. Skin sterilization
<ol>
	<li>Clean the selected needle entry site with three iodine-soaked 2 x 2-inch gauze sponges.</li>
	<li>Allow the antiseptic to dry.</li>
</ol>
3. Anesthetizing
<ol>
	<li>Use an 18-22 G needle to draw 1 mL of 1 percent lidocaine solution into a sterile 3 mL syringe.</li>
	<li>Remove that needle, and place a 5/8-inch 25 G needle on the syringe.</li>
	<li>Apply the topical ethyl chloride stream spray to the injection site from a distance of 9 inches for 10 s.</li>
	<li>Approach the &#34;X&#34; with the needle and infiltrate the skin and subcutaneous tissues with a bleb of lidocaine.</li>
	<li>Keep the area sterile, but if contaminated by inadvertent touching, repeat steps 2.1-2.2.</li>
</ol>
4. Arthrocentesis needle insertion
<ol>
	<li>Place the nondominant hand over the area superomedial to the patella and gently manually compress the fluid laterally.</li>
	<li>Insert a 1.5-inch 18-22 G needle attached to a syringe (at least 3 mL) along the pathway that was anesthetized.</li>
	<li>Advance the needle slowly and pull the plunger back gently until visualization of synovial fluid can be confirmed.</li>
	<li>If the first syringe fills up and further aspirated fluid is desired, switch to another syringe.</li>
</ol>
5. Needle removal
<ol>
	<li>Remove the needle and syringe in one smooth withdrawal motion.</li>
	<li>Place a sterile dressing over the site.</li>
	<li>Apply pressure until any bleeding stops.</li>
	<li>Once hemostasis is achieved, wipe the skin marker and iodine off with an alcohol pad.</li>
	<li>Apply adhesive bandage.</li>
</ol>

<ol><li>Zhang, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparison+of+two+positions+of+knee+arthrocentesis%3A+how+to+obtain+complete+drainage%5BTitle%5D)+AND+%22American+Journal+of+Physical+Medicine+%26+Rehabilitation%22%5BJournal%5D)">Comparison of two positions of knee arthrocentesis: how to obtain complete drainage.</a> American Journal of Physical Medicine & Rehabilitation. 91 (7), 611-615 (2012).</li>
<li>Roberts, W. N., Hayes, C. W., Breitbach, S. A., Owen, D. S. Jr <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dry+taps+and+what+to+do+about+them%3A+a+pictorial+essay+on+failed+arthrocentesis+of+the+knee%5BTitle%5D)+AND+%22The+American+Journal+of+Medicine%22%5BJournal%5D)">Dry taps and what to do about them: a pictorial essay on failed arthrocentesis of the knee.</a> The American Journal of Medicine. 100 (4), 461-464 (1996).</li>
<li>Weitoft, T., Uddenfeldt, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Importance+of+synovial+fluid+aspiration+when+injecting+intra-articular+corticosteroids%5BTitle%5D)+AND+%22Annals+of+the+Rheumatic+Diseases%22%5BJournal%5D)">Importance of synovial fluid aspiration when injecting intra-articular corticosteroids.</a> Annals of the Rheumatic Diseases. 59 (3), 233-235 (2000).</li>
<li>Thumboo, J., O'Duffy, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+prospective+study+of+the+safety+of+joint+and+soft+tissue+aspirations+and+injections+in+patients+taking+warfarin+sodium%5BTitle%5D)+AND+%22Arthritis+and+Rheumatism%22%5BJournal%5D)">A prospective study of the safety of joint and soft tissue aspirations and injections in patients taking warfarin sodium.</a> Arthritis and Rheumatism. 41 (4), 736-739 (1998).</li>
<li>Salvati, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Frequency+of+the+bleeding+risk+in+patients+receiving+warfarin+submitted+to+arthrocentesis+of+the+knee%5BTitle%5D)+AND+%22Reumatismo%22%5BJournal%5D)">Frequency of the bleeding risk in patients receiving warfarin submitted to arthrocentesis of the knee.</a> Reumatismo. 55 (3), 159-163 (2003).</li>
<li>Ahmed, I., Gertner, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Safety+of+arthrocentesis+and+joint+injection+in+patients+receiving+anticoagulation+at+therapeutic+levels%5BTitle%5D)+AND+%22The+American+Journal+of+Medicine%22%5BJournal%5D)">Safety of arthrocentesis and joint injection in patients receiving anticoagulation at therapeutic levels.</a> The American Journal of Medicine. 125 (3), 265-269 (2012).</li>
<li>Yui, J. C., Preskill, C., Greenlund, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Arthrocentesis+and+joint+injection+in+patients+receiving+direct+oral+anticoagulants%5BTitle%5D)+AND+%22Mayo+Clinic+Proceedings%22%5BJournal%5D)">Arthrocentesis and joint injection in patients receiving direct oral anticoagulants.</a> Mayo Clinic Proceedings. 92 (8), 1223-1226 (2017).</li>
<li>Klauser, A. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clinical+indications+for+musculoskeletal+ultrasound%3A+a+Delphi-based+consensus+paper+of+the+European+Society+of+Musculoskeletal+Radiology%5BTitle%5D)+AND+%22European+Radiology%22%5BJournal%5D)">Clinical indications for musculoskeletal ultrasound: a Delphi-based consensus paper of the European Society of Musculoskeletal Radiology.</a> European Radiology. 22 (5), 1140-1148 (2012).</li>
<li>Rolle, N. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Extractable+synovial+fluid+in+inflammatory+and+non-inflammatory+arthritis+of+the+knee%5BTitle%5D)+AND+%22Clinical+Rheumatology%22%5BJournal%5D)">Extractable synovial fluid in inflammatory and non-inflammatory arthritis of the knee.</a> Clinical Rheumatology. 38 (8), 2255-2263 (2019).</li>
<li>Yaqub, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Can+diagnostic+and+therapeutic+arthrocentesis+be+successfully+performed+in+the+flexed+knee%5BTitle%5D)+AND+%22Journal+of+Clinical+Rheumatology%3A+Practical+Reports+on+Rheumatic+%26+Musculoskeletal+Diseases%22%5BJournal%5D)">Can diagnostic and therapeutic arthrocentesis be successfully performed in the flexed knee.</a> Journal of Clinical Rheumatology: Practical Reports on Rheumatic & Musculoskeletal Diseases. 24 (6), 295-301 (2018).</li>
<li>Jennings, J. M., Dennis, D. A., Kim, R. H., Miner, T. M., Yang, C. C., McNabb, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((False-positive+cultures+after+native+knee+aspiration%3A+True+or+false%5BTitle%5D)+AND+%22Clinical+Orthopaedics+and+Related+Research%22%5BJournal%5D)">False-positive cultures after native knee aspiration: True or false.</a> Clinical Orthopaedics and Related Research. 475 (7), 1840-1843 (2017).</li>
<li>Massey, P. A., Feibel, B., Thomson, H., Watkins, A., Chauvin, B., Barton, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Synovial+fluid+leukocyte+cell+count+before+versus+after+administration+of+antibiotics+in+patients+with+septic+arthritis+of+a+native+joint%5BTitle%5D)+AND+%22Journal+of+Orthopaedic+Science%3A+Official+Journal+of+the+Japanese+Orthopaedic+Association%22%5BJournal%5D)">Synovial fluid leukocyte cell count before versus after administration of antibiotics in patients with septic arthritis of a native joint.</a> Journal of Orthopaedic Science: Official Journal of the Japanese Orthopaedic Association. 25 (5), 907-910 (2020).</li>
<li>Polishchuk, D., Gehrmann, R., Tan, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Skin+sterility+after+application+of+ethyl+chloride+spray%5BTitle%5D)+AND+%22The+Journal+of+Bone+and+Joint+Surgery%22%5BJournal%5D)">Skin sterility after application of ethyl chloride spray.</a> The Journal of Bone and Joint Surgery. 94 (2), 118-120 (2012).</li>
<li>Liu, K., Ye, L., Sun, W., Hao, L., Luo, Y., Chen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Does+use+of+lidocaine+affect+culture+of+synovial+fluid+obtained+to+diagnose+periprosthetic+joint+infection+%28PJI%29%3F+An+in+vitro+study%5BTitle%5D)+AND+%22Medical+Science+Monitor%3A+International+Medical+Journal+of+Experimental+and+Clinical+Research%22%5BJournal%5D)">Does use of lidocaine affect culture of synovial fluid obtained to diagnose periprosthetic joint infection (PJI)? An in vitro study.</a> Medical Science Monitor: International Medical Journal of Experimental and Clinical Research. 24, 448-452 (2018).</li>
<li>Chen, L. X., Clayburne, G., Schumacher, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Update+on+identification+of+pathogenic+crystals+in+joint+fluid%5BTitle%5D)+AND+%22Current+Rheumatology+Reports%22%5BJournal%5D)">Update on identification of pathogenic crystals in joint fluid.</a> Current Rheumatology Reports. 6 (3), 217-220 (2004).</li>
<li>Boumans, D., Hettema, M. E., Vonkeman, H. E., Maatman, R. G., Avan de Laar, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+added+value+of+synovial+fluid+centrifugation+for+monosodium+urate+and+calcium+pyrophosphate+crystal+detection%5BTitle%5D)+AND+%22Clinical+Rheumatology%22%5BJournal%5D)">The added value of synovial fluid centrifugation for monosodium urate and calcium pyrophosphate crystal detection.</a> Clinical Rheumatology. 36 (7), 1599-1605 (2017).</li>
<li>Goldenberg, D. L., Reed, J. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Bacterial+arthritis%5BTitle%5D)+AND+%22The+New+England+Journal+of+Medicine%22%5BJournal%5D)">Bacterial arthritis.</a> The New England Journal of Medicine. 312 (12), 764-771 (1985).</li>
<li>Atkins, B. L., Bowler, I. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+diagnosis+of+large+joint+sepsis%5BTitle%5D)+AND+%22The+Journal+of+Hospital+Infection%22%5BJournal%5D)">The diagnosis of large joint sepsis.</a> The Journal of Hospital Infection. 40 (4), 263-274 (1998).</li>
</ol>

The authors have nothing to disclose.

Knee arthrocentesis is a bedside or clinic procedure in which a needle is inserted into the joint capsule, and synovial fluid is aspirated. Before attempting an arthrocentesis, knee swelling by history should be confirmed to be an effusion on physical examination. A knee x-ray can reveal an effusion but is not necessary prior to aspiration. If body habitus complicates the physical examination, ultrasonography can be used to confirm effusion size and to direct insertion of the needle for aspiration8. If a patient has a swollen, painful, and warm knee with restricted movement, then a diagnostic arthrocentesis should be performed promptly to evaluate for septic arthritis. Arthrocentesis is usually performed with the patient supine and the knee extended as fully as it can be to increase intraarticular pressure. Mechanical compression with a knee brace has been shown to improve the success of knee arthrocentesis and fluid yield in rheumatoid arthritis and osteoarthritis9. A fully extended knee can be difficult if the patient has pain and restricted movement. It is possible, though, to aspirate fluid from a flexed knee, especially with an external compression brace. A study of 35 flexed knees with mechanical compression to the superior knee led to successful arthrocentesis fluid yields identical to the extended knee position10. Obvious unilateral knee swelling still should be palpated to detect the presence of fluid. Moderate to large volume knee effusions are easier to detect than small effusions. In a patient with morbid obesity, quadriceps hypertrophy, or osteoarthritic bony changes of the knee, it may be difficult to identify an effusion and so ultrasound can be used to confirm the presence of synovial fluid.
A skin marker is preferred over a pen because pen ink may be erased by iodine or chlorhexidine. An alternative to marking an &#34;X&#34; is to impress the skin with the tip of a ballpoint retractable pen or the sterile end of a needle sheath. Instead of soaking three gauze sponges with iodine solution, three iodine swabs or three chlorhexidine applying devices can be used to sterilize the skin for arthrocentesis. In a study of 166 specimens from native knees disinfected with chlorhexidine and then iodine, there were no false-positive cultures11. This suggests that a positive culture detected from an arthrocentesis performed under sterile conditions is highly suspicious for septic arthritis. Antibiotics can alter the synovial fluid analysis. Among 81 patients with septic arthritis, the average synovial leukocyte count was lower in the group who had received antibiotics prior to arthrocentesis compared to those who had not received antibiotics12. This highlights the importance of aspirating synovial fluid before antibiotics. Ethyl chloride spray is labeled as nonsterile, but a study of 15 healthy adults prepared for mock bilateral shoulder and bilateral knee injections showed that the percentage of positive cultures from the skin did not significantly increase after the application of ethyl chloride13. The burst of ethyl chloride spray to cool the skin as a topical anesthetic is optional. Subcutaneous lidocaine as a local anesthetic can be sufficient prior to an arthrocentesis. One disadvantage of this local anesthesia is the antibacterial property of lidocaine 2% in vitro14. Thus, this theoretically could affect the results of the synovial fluid culture.
The larger bore needle for aspiration should be inserted at the same location as the infiltration of lidocaine. The entire length of this needle need not be inserted into the synovial space. The syringe size for arthrocentesis should be at least 3 mL, but typically a 5 mL syringe would be the minimum to send synovial fluid analysis for cell count, crystal examination, gram stain, and culture. Only a drop of the synovial fluid is required for the wet mount, but an adequate amount of fluid is preferred to extract sediment of a centrifuged specimen for crystal examination and Gram stain15,16,17,18. A knee effusion can contain more than 100 mL of synovial fluid, and so if a large knee effusion is detected, a 50 mL syringe can be used to aspirate.
Even before an arthrocentesis, data gathered from the patient&#39;s history, physical examination, laboratory findings, and imaging can suggest a particular etiology of a knee effusion. Acute onset of knee pain and swelling can be seen in septic arthritis or a gout flare. Chronic knee swelling in an older, obese patient can be due to osteoarthritis. Trauma to the knee can cause hemarthrosis. Physical examination findings such as malar rash or psoriasis can lead one to suspect lupus arthritis or psoriatic arthritis, respectively. Laboratory tests such as an elevator rheumatoid factor and an anti-cyclic citrullinated peptide antibody can be seen in rheumatoid arthritis. The radiographic finding of chondrocalcinosis in the knee can be seen in pseudogout. The diagnostic arthrocentesis can provide key information to supplement the suspected diagnosis for a knee effusion. The arthrocentesis can also be therapeutic by decreasing pain and improving the range of motion of the knee. Arthrocentesis of the knee is a useful procedure in which synovial fluid is aspirated through a needle from the knee joint.

Arthrocentesis is performed to successfully aspirate synovial fluid from a joint such as a knee, shoulder, elbow, wrist, or ankle. A patient with a newly detected knee effusion can undergo a diagnostic arthrocentesis to determine the nature of the effusion. Before proceeding to attempt an arthrocentesis, knee swelling by history must be confirmed on physical examination to assess whether an effusion exists. With the patient supine, the knees can be compared on inspection to see if the swelling is unilateral. The knee with the effusion may appear larger than the other knee. With a large effusion (at least 20 mL), convexity can be seen proximal to the patella. With a small effusion (5-10 mL), pressing the fluid superolaterally with one hand can allow the other hand to palpate a fluid bulge. Palpating the fluid can help decide if a successful arthrocentesis is probable. In addition to the supine position, arthrocentesis of the knee can also be done on a patient in the sitting position, but there is a higher chance that less synovial fluid would be aspirated1. Synovial fluid from the knee can be aspirated from a medial or lateral approach, but the latter is preferred in complicated circumstances2. A knee effusion is not always tender on exam and thus does not necessarily cause an antalgic gait. An urgent arthrocentesis before antibiotic treatment is indicated if septic arthritis is suspected. An orthopedic surgeon can perform a knee joint aspiration to diagnose a prosthetic joint infection in a patient who had a knee arthroplasty.
In addition to evaluating for infection, arthrocentesis can assist in identifying diagnoses, such as crystal-induced arthritis (gout or pseudogout), rheumatoid arthritis, spondyloarthritis, reactive arthritis, psoriatic arthritis, hemarthrosis, or osteoarthritis. The findings on synovial fluid analysis can lead to the appropriate treatment. In a patient with pain and restricted movement of the knee due to an effusion, aspirating the fluid can improve these symptoms. Furthermore, arthrocentesis of a knee prior to an intra-articular steroid injection has been shown to reduce the risk for arthritis relapse in rheumatoid arthritis3. There is no absolute contraindication to arthrocentesis of a knee, but the needle should be inserted away from any cellulitis to not introduce any infection into the joint. Moreover, arthrocentesis has been shown to be generally safe in patients on anticoagulation with warfarin or direct oral anticoagulants4,5,6,7. With the proper technique and clinical indication, a patient can undergo this procedure with minimal risks.

<table><tbody><tr><td>Alcohol prep pad</td><td>Medline</td><td>MDS090670Z</td><td>sterile 2-ply pad</td></tr><tr><td>Eclipse needle</td><td>BD</td><td>DGW60702</td><td>25G x 5/8&quot;</td></tr><tr><td>Ethyl Chloride instant topical anesthetic spray</td><td>Gebauer&#039;s</td><td>P/N 0386-0008-03</td><td>non-flammable</td></tr><tr><td>Lidocaine HCl injection</td><td>Fresenius Kabi Usa, Llc</td><td>NDC 63323-492-27</td><td>1% single dose vial</td></tr><tr><td>Plastic bandage</td><td>Curad</td><td>CUR02278RB</td><td>4-sided seal</td></tr><tr><td>Plastipak 3 mL syringe</td><td>BD</td><td>309651</td><td>sterile</td></tr><tr><td>Plastipak 5 mL syringe</td><td>BD</td><td>309649</td><td>sterile</td></tr><tr><td>Povidone iodine topical solution</td><td>Major</td><td>NDC 0904-1103-09</td><td>topical antiseptic</td></tr><tr><td>Precision glide needle</td><td>BD</td><td>305196</td><td>18G x 1 1/2&quot;</td></tr><tr><td>Sterile gauze sponge</td><td>CARING</td><td>PRM2208</td><td>2 in. x 2 in.</td></tr><tr><td>Sterile regular tip surgical skin marker</td><td>MEDLINE</td><td>DYNJSM01</td><td></td></tr><tr><td>Surgical gloves</td><td>TRIUMPH</td><td>MSG2265</td><td>sterile &amp;amp; powder-free</td></tr></tbody></table>

knee arthrocentesis in adults

Arthrocentesis of the knee is a procedure in which a needle is inserted into the knee joint, and synovial fluid is aspirated. An arthrocentesis can be diagnostic or therapeutic. Synovial fluid may be removed for testing to determine the nature of the knee effusion. If septic arthritis is suspected, urgent arthrocentesis before initiation of antibiotic treatment is indicated. Moreover, arthrocentesis can also aid in diagnosing crystal-induced arthritis such as gout or pseudogout, or non-inflammatory arthritis such as osteoarthritis. Identifying the cause of the knee effusion can guide treatment. Furthermore, removing fluid from a knee can reduce intraarticular pressure to decrease pain and improve range of motion. There is no absolute contraindication to performing this procedure, but in selecting the needle entry site, an area of skin that is infected should be avoided. Therefore, caution should be exercised when a patient presents with suspected cellulitis over the knee joint to avoid the potential risk of causing iatrogenic septic arthritis. A knee that has undergone arthroplasty should be assessed for arthrocentesis by an orthopedic surgeon. Arthrocentesis of the knee is typically performed with the patient supine. The site for needle insertion is marked, and then the skin is disinfected. After a local anesthetic is administered, a needle is inserted along the pathway that was anesthetized. Synovial fluid is aspirated, and then the needle is withdrawn. Pressure is applied until any bleeding stops. The synovial fluid can be analyzed for infection and inflammation but cannot directly confirm a diagnosis of internal derangement or autoimmune causes of arthritis. In addition to the history and physical examination, laboratory findings and imaging can clarify the etiology of a knee effusion.

A prospective randomized study compared&#160;complete aspiration of synovial fluid from the knee and intra-articular injection with corticosteroid alone. It demonstrated that aspirating as much synovial fluid as possible can reduce the risk for recurrence of arthritic symptoms when treating rheumatoid arthritis patients with intra-articular corticosteroids. Figure 1 shows the reduction in the proportion of relapses in the arthrocentesis group3.
A retrospective chart review of arthrocenteses and joint injections compared the incidence of clinically significant bleeding in patients receiving warfarin with an international normalized ratio &#8805;2.0 and those whose anticoagulation was adjusted to an international normalized ratio &#60;2.0. Table 1 shows no statistically significant difference in bleeding between the two groups6.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63135/63135fig01.jpg" /> 
Figure 1: Proportion of arthritis relapse with or without arthrocentesis. The proportion of relapses in the arthrocentesis group was significantly reduced (p = 0.0009) and at the end of 6 months, there were 23% relapses in the arthrocentesis group and 47% in the no arthrocentesis group (p=0.001). Ninety-five knees were randomized to arthrocentesis and 96 had no arthrocentesis before triamcinolone hexacetanoide (20 mg) was injected into the inflamed knee joint. This figure is adapted with permission from Weitoft et al.3. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63135/63135fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Complications</td>
			<td>Group A (INR &#8805; 2) (n = 456)</td>
			<td>Group B (INR &#60; 2) (n = 184)</td>
			<td>P Value</td>
		</tr>
		<tr>
			<td>Clinically significant bleeding (early)</td>
			<td>1&#8197;(0.2%)</td>
			<td>0</td>
			<td>NS</td>
		</tr>
		<tr>
			<td>Clinically significant bleeding (late)</td>
			<td>0</td>
			<td>0</td>
			<td>NS</td>
		</tr>
		<tr>
			<td>Infection of joint (late)</td>
			<td>1&#8197;(0.2%)</td>
			<td>0</td>
			<td>NS</td>
		</tr>
		<tr>
			<td>Pain of joint causing physician visit</td>
			<td>3&#8197;(0.7%)</td>
			<td>0</td>
			<td>NS</td>
		</tr>
		<tr>
			<td colspan="4">INR=international normalized ratio; NS=not significant.</td>
		</tr>
	</tbody>
</table>
Table 1: Early and late complications between two groups. Procedure-related complications were defined as early (within 24 h) and late (within 30 days) clinically significant bleeding in or around a joint, infection of joint related to the arthrocentesis, and pain requiring a physician visit excluding chronic pain. Four patients accounted for 5 complications. This table has been modified with permission from Ahmed et al.6.

Watch this Scientific Journal Video about Knee Arthrocentesis in Adults at JoVE.com

Knee Arthrocentesis in Adults

Here the protocol describes arthrocentesis of the knee, a procedure in which a needle is inserted into the knee joint, and synovial fluid is aspirated. Synovial fluid may be removed for testing to determine the nature of the knee effusion. Arthrocentesis of the knee is typically performed with the patient supine.

Arthrocentesis of the knee is a procedure in which a needle is inserted into the knee joint, and synovial fluid is aspirated. An arthrocentesis can be ...

Nanyang Technological University

Research

JoVE Journal

Medicine

7.3K Views.  BronxCare Health System. Dit protocol beschrijft de artrocentese van de knie, een procedure waarbij een naald in het kniegewricht wordt ingebracht en synoviale vloeistof wordt geaspireerd. Een artrocentese kan diagnostisch of therapeutisch zijn. Synoviale vloeistof kan worden verwijderd voor testen om de aard van de effusie te bepalen.Het verwijderen van vocht uit een knie kan de pijn verminderen. Met de patiënt in rugligging voorzichtig palpeert u de knie om de patella te lokaliseren en gebruikt u een huidma...

Video: Knee Arthrocentesis in Adults

Novel Diagnostics in Revision Arthroplasty: Implant Sonication and Multiplex Polymerase Chain Reaction

In orthopedic patients, foreign body-associated infections, especially periprosthetic joint infections (PJIs), are a devastating complication of arthroplasty. Infection requires complex treatment, may result in long hospitalization and causes considerable costs. Multiple surgical revisions can be necessary in these patients, with a loss in function as well as in quality of life.
The routine preoperative diagnostics include blood examination for C-reactive protein (CRP) and other biomarkers, as well as joint aspirate analysis for cell count, differentiation, and culture. Intraoperative specimens for histology and microbiology are also standard procedure. The microbiological examination of removed implants with sonication, in combination with the implementation of molecular biology techniques in microbiology, represent two novel techniques currently employed to enhance the differential diagnostics of PJI.
We present here the step-wise procedure of analyzing joint aspirate and sonication fluid, using a cartridge-based multiplex polymerase chain reaction (PCR) system. Results were matched against conventional cultures and consensus criteria for PJI. Conventional microbiological cultures from tissue biopsies, joint aspirate and sonication fluid showed a sensitivity of 66.7%, 66.7%, and 88.9%, respectively, and a specificity of 82.3%, 54.6%, and 61.5%, respectively. The PCR diagnostic of the sonication fluid and the joint fluid showed a sensitivity of 50.0% and 55.6%, respectively, and both a specificity of 100.0%. Both PCR diagnostics combined had a sensitivity of 66.7% and a specificity of 100.0%. The multiplex PCR therefore presents a rapid diagnostic tool with moderate sensitivity but high specificity in diagnosing PJI.

Differential diagnostics in painful arthroplasty is crucial for treatment success. Joint aspiration is routinely performed preoperatively. Multiplex polymerase chain reaction of the joint aspirate and the sonication fluid, a feasible tool for quick pathogen detection from these samples is described.

In orthopedic patients, foreign body-associated infections, especially periprosthetic joint infections (PJIs), are a devastating complication of ...

Preparation, Procedures and Evaluation of Platelet-Rich Plasma Injection in the Treatment of Knee Osteoarthritis

Knee osteoarthritis (KOA) is one of the most frequently encountered diseases in the orthopedic department. Existing non-surgical treatments have a limited effect on the repair of cartilage and on bone regeneration. Platelet-rich plasma (PRP) is an autologous bioactive substance that can repair cartilage injury and accelerate bone regeneration effectively. However, reporting of PRP preparation protocols in clinical studies is highly inconsistent, with the majority of studies providing insufficient information to allow the protocol to be reproduced. We describe a repeatable method of preparing PRP visually, the treatment of KOA using PRP intra-articular injection, and methods of evaluating the outcome. PRP was prepared using manual double centrifugation. The PRP layer was extracted from peripheral blood and used for knee joint cavity injection. Evaluations included assessments of blood platelet concentrations and clinical outcomes. Preparation of PRP by manual centrifugation requires less apparatus and is less costly than plasma filtration or centrifugation using equipment. The centrifugation time of our double centrifugation method was 6 and 5 minutes for the respective centrifugations at forces of 800 and 1400 x g, respectively, to allow for the consistent preparation of standardized PRP. However, a manual method is susceptible to operator error, and PRP batch preparation is not available. Intra-articular injection of PRP proved to be an effective treatment for knee osteoarthritis. The entire treatment procedure took less than 30 minutes, the blood platelet concentration of PRP could be standardized, and treatment was proven to be effective when evaluated by follow-up.

Knee osteoarthritis is frequently seen in the orthopedic department. We introduce in detail the entire knee osteoarthritis treatment process with platelet-rich plasma injection, including preparation, procedures, and evaluation.

Knee osteoarthritis (KOA) is one of the most frequently encountered diseases in the orthopedic department. Existing non-surgical treatments have a limited ...

An Effective Surgical Strategy for Anteromedial Osteoarthritis of the Knee with Simultaneous Popliteal Cysts Drainage

Unicompartmental knee arthroplasty (UKA) is an established treatment option for anteromedial osteoarthritis, and popliteal cysts are a common finding in the knee among patients with chronic osteoarthritis pain. The two are so closely related that popliteal cysts are commonly discovered during the unicompartmental knee arthroplasty preoperative examination. However, only a few reports exist on the management and outcome of popliteal cysts in the patients receiving UKA for knee osteoarthritis (OA) and popliteal cysts. As such, it is crucial to evaluate different treatment strategies and their management of popliteal cysts. In this paper, we evaluate a surgical strategy for patients with knee anteromedial osteoarthritis and symptomatic popliteal cysts. These patients were treated with UKA and internal drainage of the popliteal cyst. The results shown here, spanning 1-year post-operation follow-up, demonstrated that UKA and internal drainage is an effective surgical protocol for treating anteromedial osteoarthritis with symptomatic popliteal cysts.

Popliteal cysts are frequently found during the pre-operative examination of patients with osteoarthritis being prepared for the unicompartmental knee arthroplasty. These symptomatic cysts usually require treatment. To do this, a unicompartmental knee arthroplasty was performed with internal drainage of the popliteal cyst under the same anesthetic.

Unicompartmental knee arthroplasty (UKA) is an established treatment option for anteromedial osteoarthritis, and popliteal cysts are a common finding in ...

FSN Therapy for Knee Osteoarthritis Pain Management

Fu's Subcutaneous Needling for Knee Osteoarthritis Pain

Fu's subcutaneous needling (FSN) is a new acupuncture and dry needling technique based on traditional Chinese medicine. It rapidly produces long-lasting effects in soft tissue injuries, particularly in painful musculoskeletal conditions, by providing stimulation primarily in the subcutaneous area. Osteoarthritis (OA) is the most common joint disease in adults worldwide and is often accompanied by a painful syndrome of structural changes in the peripheral joints of the knee. However, the etiology of OA pain is not fully understood, though myofascial trigger points (MTrPs) are commonly found in the lower limb muscles (so-called "tightened muscles") of patients with knee OA. 
FSN has been used in many fields for the treatment of acute pain problems and can relieve muscle contraction from MTrPs, thereby improving the local circulation. This study recruited patients with pain from knee OA into an FSN group or a transcutaneous electrical nerve stimulation (TENS) group with three treatment sessions and a follow-up over the course of 2 weeks. The results showed that FSN was effective in treating soft tissue pain around the knee with OA. This study aimed to establish and visualize three key technical indicators during FSN therapy, including the FSN needle insertion point and layer; the frequency and duration of the swaying movement; and the manipulation of the reperfusion approach. These findings have great potential for future applications in myofascial pain treatment, especially for pain management. Following this protocol could enhance FSN skills.

Author Spotlight: Fu's Subcutaneous Needling for Knee Osteoarthritis Pain  

We present a protocol for using Fu's subcutaneous needling for knee osteoarthritis pain, which combines swaying movement and reperfusion approach techniques. This protocol has great potential for future applications in myofascial pain treatment and could enhance Fu's subcutaneous needling (FSN) manipulation skills.

Fu's subcutaneous needling (FSN) is a new acupuncture and dry needling technique based on traditional Chinese medicine. It rapidly produces long-lasting ...

Arthroscopic Double Posteromedial Approach for PCL Cyst Excision

Arthroscopic Excision of Posterior Cruciate Ligament Cysts Using a Double Posteromedial Approach

Cruciate ligament cysts of the knee are a rare condition. Posterior cruciate ligament cysts of the knee are less common than anterior cruciate ligament cysts. In patients with asymptomatic isolated cruciate ligament cysts of the knee, conservative treatment is recommended. Symptomatic cruciate ligament cysts of the knee are mostly manifested as knee hyperflexion pain, straightening pain, knee discomfort after standing for a long time or walking for a long time, etc., which seriously affects the quality of life, surgical treatment can be performed. The surgical treatments can be divided into ultrasound-guided cyst puncture and fluid extraction procedure and arthroscopic cystectomy. Cysts are mostly lobulated with a multi-layer cyst wall, cyst fluid extraction does not remove the cyst wall completely but simply extracts cyst fluid, leading to a high recurrence rate. Arthroscopic surgery can completely remove the cyst wall with little trauma, a low recurrence rate, and fast postoperative recovery, so arthroscopic resection is the most common and preferred method of treatment. Since posterior cruciate ligament cysts mostly occur posterior to the ligament, we remove the cyst wall by adding a double posteromedial approach to the knee joint, and the cyst wall is removed under direct vision, which is simple to operate, the cyst wall is completely cleared, the trauma is small, the postoperative recovery is fast, and there is no recurrence. Here, 8 posterior cruciate ligament cysts were removed with complete postoperative symptom relief, no surgical complications, and no recurrence at 1-year follow-up.

Author Spotlight: Double Posteromedial Approach for Treating Posterior Cruciate Ligament Cysts

We present a surgical approach to treat posterior cruciate ligament cysts by an arthroscopic double posteromedial approach.

Cruciate ligament cysts of the knee are a rare condition. Posterior cruciate ligament cysts of the knee are less common than anterior cruciate ligament ...

Managing Knee Osteoarthritis Using Ultrasound-Guided Acupotomy

Clinical Effects of Ultrasound-Guided Acupotomy in Knee Osteoarthritis Treatment

The protocol presented here demonstrates the operation method of ultrasound-guided acupotomy for knee osteoarthritis (KOA), including patient recruitment, preoperative preparation, manual operation, and postoperative care. The purpose of this protocol is to relieve pain and improve knee function in patients with KOA. A total of 60 patients with KOA admitted between June 2022 and June 2023 were treated with ultrasound-guided acupotomy. Pathological changes and knee function scores were compared before and after the treatment. After 1 week of treatment, the synovial thickness of the suprapatellar bursae was significantly lesser than before treatment (p &lt; 0.05), the Hospital for Special Surgery Knee Score (HSS) was significantly higher than before treatment (p &lt; 0.05), the Visual analogue scale (VAS) was significantly lower than those of the control group (p &lt; 0.05) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were significantly lower than those of the control group (p &lt; 0.05). Therefore, ultrasound-guided acupotomy for the treatment of KOA can reduce synovial thickness, relieve pain, improve knee joint function, and have a remarkable curative effect.

Author Spotlight: Minimally Invasive Ultrasound-Guided Acupotomy in Knee Osteoarthritis Treatment

This paper introduces the operation method of ultrasound-guided acupotomy for knee osteoarthritis, which can reduce synovial thickness and improve knee joint function. It has the advantages of precise target, low treatment risk, few complications, and high safety.

The protocol presented here demonstrates the operation method of ultrasound-guided acupotomy for knee osteoarthritis (KOA), including patient recruitment, ...

Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty (TKA) is a common surgical intervention. Experiments using primary human OA tissues obtained from TKA provide the capability to investigate disease mechanisms ex vivo. While OA was previously thought to impact mainly the cartilage, it is now known to impact multiple tissues in the joint. This protocol describes patient selection, sample processing, tissue homogenization, RNA extraction, and quality control (based on RNA purity, integrity, and yield) from each of seven unique tissues to support disease mechanism investigation in the knee joint. With informed consent, samples were obtained from patients undergoing TKA for OA. Tissues were dissected, washed, and stored within 4 h of surgery by flash freezing for RNA or formalin fixation for histology. Collected tissues included articular cartilage, subchondral bone, meniscus, infrapatellar fat pad, anterior cruciate ligament, synovium, and vastus medialis oblique muscle. RNA extraction protocols were tested for each tissue type. The most significant modification involved the method of disintegration used for low-cell, high-matrix, hard tissues (considered as cartilage, bone, and meniscus) versus relatively high-cell, low-matrix, soft tissues (considered as fat pad, ligament, synovium, and muscle). It was found that pulverization was appropriate for hard tissues, and homogenization was appropriate for soft tissues. A proclivity for some subjects to yield higher RNA integrity number (RIN) values than other subjects consistently across multiple tissues was observed, suggesting that underlying factors such as disease severity may impact RNA quality. The ability to isolate high-quality RNA from primary human OA tissues provides a physiologically relevant model for sophisticated gene expression experiments, including sequencing, that can lead to clinical insights that are more readily translated to patients.

Primary tissues obtained from patients following total knee arthroplasty provide an experimental model for osteoarthritis research with maximal clinical translatability. This protocol describes how to identify, process, and isolate RNA from seven unique knee tissues to support mechanistic investigation in human osteoarthritis.

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty ...

Biology

Arthroscopic Repair of Medial Meniscus Posterior Root Tear with Adjustable Titanium Plate Fixation

Medial meniscus injury is one of the most prevalent knee disorders, with posterior root tears occurring in approximately 10% to 21% of affected individuals. A posterior root tear disrupts the meniscus's continuous annular structure, compromising its ability to absorb pressure and protect the knee's articular cartilage. If left untreated, this can result in increased stress on the cartilage, leading to conditions such as varus deformity and accelerated joint degeneration. Partial removal (resection) of the medial meniscus further exacerbates these issues, often leading to quicker joint deterioration. Repairing medial meniscus posterior root tears (MMPRTs) plays a crucial role in restoring the meniscus's structural integrity and improving knee biomechanics. Studies have shown that compared to partial medial meniscectomy or conservative treatments, repairing MMPRTs enhances clinical outcomes and significantly delays the onset of arthritis. This article details a surgical procedure that uses a single-suture, double-loop, adjustable titanium plate fixation technique under arthroscopy for effective MMPRT repair.

This article describes a surgical approach to repairing a medial meniscus posterior root tear (MMPRT) using a single-suture, double-loop, adjustable titanium plate internal fixation under arthroscopy.

Medial meniscus injury is one of the most prevalent knee disorders, with posterior root tears occurring in approximately 10% to 21% of affected ...

Glycemic Impact on Knee Osteoarthritis Symptoms on Physical, Radiographic, and Inflammatory Markers among Individuals Aged 50 and Over with Diabetes

This study explores hyperglycemia&#39;s influence on knee osteoarthritis (KOA) related symptoms, physical performance, physical activity level, radiographic severity, and inflammation in older adults. Prolonged hyperglycemic states contribute to advanced glycation end-product (AGE) formation, which worsens KOA symptoms. Capillary blood glucose (CBG) and glycated hemoglobin A1C (HbA1C) levels are commonly used in laboratory tests for glycemic assessment, offering distinct advantages and limitations. Participants were divided into good and poor glycemic control groups based on their CBG and HbA1C levels. KOA clinical severity and physical activity were measured using the knee injury and osteoarthritis outcome score (KOOS) and international physical activity questionnaire. Physical performance was measured with hand grip strength, gait speed, time-up-and-go (TUG), and 5 times sit-to-stand (5STST). Knee X-rays were performed, and serum enzyme-linked immunosorbent assay (ELISA) analysis was conducted for IL-1&#946;, IL-4, CRP, NF-&#954;B, and AGE. Three hundred recruited participants (mean age [SD] = 66.40 years (5.938) with CBG, of fasting blood sugar &#62; 7.0 mmol/L and random blood sugar &#62; 11.1 mmol/L, (N = 254) were compared with KOOS pain (p=0.008) and symptoms (p=0.017) and 5STST (p=0.015); while HbA1c &#62; 6.3% (N = 93) was compared with 5STST (p=0.002), and AGEs (p=0.022) based on Mann Whitney U test. Logistic regression revealed significant associations between glycemic control&#160;and lower limb muscle strength, radiological severity, laboratory markers, and between glycemic status and KOOS pain and symptoms. However, these associations did not remain significant after adjusting for BMI. Poor glycemic status alone was associated with better function in sport and recreation domains after antidiabetic medication adjustment, suggesting anti-inflammatory and analgesic effects that masked the effect of high blood sugar. Future studies could explore the predictive ability of glycemic assessment for poor knee function and physical performance while accounting for the effects of the medication.

Here, we present a protocol to assess glycemic control using capillary blood glucose (CBG) and glycated hemoglobin A1C (HbA1C) levels. This study investigates the impact of hyperglycemia on knee osteoarthritis (KOA) symptoms, physical performance, physical activity level, radiographic severity, and inflammation in older adults with diabetes.

This study explores hyperglycemia&#39;s influence on knee osteoarthritis (KOA) related symptoms, physical performance, physical activity level, ...

Knee Exam

Source: <a href="https://www-jove-com.remotexs.ntu.edu.sg/author/Robert+E._Sallis">Robert E. Sallis</a>, MD. Kaiser Permanente, Fontana, California, USA
The knee is a hinged joint that connects the femur with the tibia. It is the largest joint in the body, and due to its location in the middle of the lower leg, it is subjected to a variety of traumatic and degenerative forces. Examination of the knee can be quite complex, owing to the fact it is an inherently unstable joint held together by various ligaments and supported by menisci, which act as shock absorbers and increase the contact area of the joint. In addition, the patella lies in front of the knee, acting as a fulcrum to allow the forceful extension of the knee needed for running and kicking. As the largest sesamoid bone in the body, the knee is a common source of pain related to trauma or overuse.
When examining the knee, it is important to remove enough clothing so that the entire thigh, knee, and lower leg are exposed. The exam begins with inspection and palpation of key anatomic landmarks, followed by an assessment of the patient's range of motion (ROM). The knee exam continues with tests for ligament or meniscus injury and special testing for patellofemoral dysfunction and dislocation of the patella. The opposite knee should be used as the standard to evaluate the injured knee, provided it has not been previously injured.

Knee Exam: Ligament, Meniscal and Patella Tests

Source: Robert E. Sallis, MD. Kaiser Permanente, Fontana, California, USA
The knee is a hinged joint that connects the femur with the tibia. It is the ...

Knee Arthrocentesis in Adults

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