The authors would like to thank Joao Tomas for his technical assistance with the device and Khaoula Louati for assistance in developing the image analysis methods.

The rat knee immobilization model used has been approved by the University of Ottawa Animal Care and Veterinary Service and the local ethics committee.
1. Animal Preparation
<ol>
	<li>At the end of the predetermined immobilization period, euthanize the rats by administration of carbon dioxide. 
	NOTE: Here we used an immobilization model with a plate and 2 screws (one inserted in the proximal femur and the other in the distal tibia), which avoids violation of any knee joint structures, and maintains a knee-flexed position of 135&#176; as described previously6. Over a period of time, this produces a knee flexion contracture11.</li>
	<li>Cover the area both on and around the surface that the arthrometer will be placed upon with absorbent, water-proof protection pads. Wear gloves, lab coat, and eye protection, while completing the experiment.</li>
	<li>Using a scalpel, divide the skin to expose the plate and screws (see the note following step 1.1); insert the more proximal screw in the proximal femur and insert the more distal screw in the distal tibia. Palpate to locate the screws. Once the screw heads are accessible, remove the screw using a screwdriver. 
	NOTE: During the period of immobilization, the heads of the screws may become covered by soft tissue. If this occurs, use the scalpel to gently remove the tissue and uncover the screw heads.</li>
	<li>Once the screws are removed, remove the plate manually or using forceps from a dissection kit.</li>
	<li>Using scissors and forceps, deglove the lower extremity to remove skin from underlying fascia.</li>
</ol>
2. Animal Positioning on the Motor-driven Arthrometer
NOTE: All testing should be performed at room temperature. Here the arthrometer is powered by a standard North American 120 V input. The adapter output is 12 V and 500 mA.
<ol>
	<li>Position the animal to be tested on its side with the experimental leg (the leg to be tested) facing upwards (Figure 2).
	<ol>
		<li>Secure the femur in the grooved metal clamp that is integrated into the mounting stage of the arthrometer. Punch holes through the muscle using a precision screwdriver to place the clamp distal to the greater trochanter and secure the femur. Adjust the lateral femoral condyle over the center of rotation of the arthrometer (Figure&#160;1, 2).</li>
		<li>Position the movable arm with two upright posts behind the leg, just superior to the calcaneus, to push the knee into passive extension once the electric motor is activated.</li>
		<li>Tighten the femur clamp at its base using a hex key until it is secured.</li>
	</ol>
	</li>
	<li>Ensure the camera is correctly mounted on the arthrometer using a screwdriver and is on Manual Focus. Focus the camera on the femoral condyle.</li>
	<li>Select the direction setting on the arthrometer (clockwise or counterclockwise) depending on the direction of the knee ROM being tested and the position of the rat.</li>
	<li>Activate the arthrometer motor by simultaneously pushing the Power and Start button. 
	NOTE: The necessity of pushing the power and start button simultaneously is a safety feature of the device, which prevents accidental activation.
	<ol>
		<li>Observe that the arthrometer motor will move at a speed of 6.6 RPM and then stop for 2.1 s upon reaching the first pre-set torque.</li>
		<li>NOTE: that when the first torque is reached, the corresponding LED will light up and the digital camera will take a picture of the knee automatically. 
		NOTE: Once the picture is taken, the arthrometer will continue to the next, higher preset torque. Once the four torques have been applied, the arthrometer will stop. Once the rat is positioned on the arthrometer and testing is initiated, the total time for testing one knee is approximately 18.8 s. Times may vary slightly depending on the condition of the joint contracture. The images taken are used to measure the extension at each torque.</li>
	</ol>
	</li>
</ol>
3. Capturing the Angle of Knee Extension Using the Motor-driven Arthrometer
NOTE: Once the motor has stopped at each applied torque, a digital camera is triggered to take a picture. The camera is positioned on the frame such that it is directly above the knee joint being tested and focused on the femoral condyle.
<ol>
	<li>Continue testing with the same knee from the same animal but in a different situation, e.g., after a myotomy of the posterior transarticular muscles is performed to isolate the arthrogenic (non-muscular) component of a contracture, or with a knee from another animal.
	<ol>
		<li>When completing the myotomy, dissect the muscle proximal enough to the knee joint to ensure that the capsule is not cut. 
		NOTE: It is easiest to complete the myotomy when the leg is in extension, following application of torque setting 4 (17.53 N-cm). Then, repeat steps 2.1 through 3.1.</li>
	</ol>
	</li>
	<li>Once both legs have been tested in all conditions (e.g., before and after myotomy), dispose of the animal carcass and all biohazardous materials following institutional protocol, and clean the arthrometer.</li>
</ol>
4. Knee ROM Measurement Analysis
<ol>
	<li>Analyze ROM using ImageJ. 
	NOTE: Here version 1.45s was used.</li>
	<li>Open the file containing the digital image taken by the camera mounted on the rat arthrometer. 
	NOTE: The person performing the analysis should be blinded to the experimental grouping of the animal (e.g., immobilized versus control).</li>
	<li>Select the Angle tool from the main toolbar and trace the femorotibial angle by drawing a femoral line from the middle of the femur clamp to the lateral condyle (aligned with the femoral diaphysis, Figure 2), and a tibial line from the lateral femoral condyle to the lateral malleolus (Figure 2). 
	NOTE: The femoro-tibial angle corresponds to the maximal angle of knee extension reached at each preset torque.</li>
	<li>Use the measuring tool by clicking Analyze| Measure to show the calculated angle produced by the 2 lines drawn above. Use the convention of 0&#176; to mean full extension.</li>
</ol>

<ol>
	<li>Clavet, H., H&#233;bert, P. C., Fergusson, D., Doucette, S., Trudel, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Joint+contracture+following+prolonged+stay+in+the+intensive+care+unit.">Joint contracture following prolonged stay in the intensive care unit.</a> Canadian Medical Association Journal. 178 (6), 691-697 (2008).</li><li>Campbell, T. M., Dudek, N., Trudel, G., Silver, J. K., Frontera, W. R., Rizzo, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Essentials of Physical Medicine and Rehabilitation: musculoskeletal disorders, pain, and rehabilitation. , (2015).</li><li>Dehail, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acquired+deforming+hypertonia+and+contractures+in+elderly+subjects:+definition+and+prevalence+in+geriatric+institutions+(ADH+survey).">Acquired deforming hypertonia and contractures in elderly subjects: definition and prevalence in geriatric institutions (ADH survey).</a> Annals of Physical and Rehabilitation Medicine. 57 (3), 11-23 (2014).</li><li>Korp, K., Richard, R., Hawkins, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Refining+the+idiom+&amp;#34;functional+range+of+motion&amp;#34;+related+to+burn+recovery.">Refining the idiom &amp;#34;functional range of motion&amp;#34; related to burn recovery.</a> Journal of Burn Care and Research. 36 (3), 136-145 (2015).</li><li>Elliott, L., Walker, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rehabilitation+interventions+for+vegetative+and+minimally+conscious+patients.">Rehabilitation interventions for vegetative and minimally conscious patients.</a> Neuropsychological Rehabilitation. 15 (3-4), 480-493 (2005).</li><li>Campbell, T. M., Reilly, K., Laneuville, O., Uhthoff, H., Trudel, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+replaces+articular+cartilage+in+the+rat+knee+joint+after+prolonged+immobilization.">Bone replaces articular cartilage in the rat knee joint after prolonged immobilization.</a> Bone. 106, 42-51 (2017).</li><li>Trudel, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+alterations+of+rabbit+Achilles'+tendon+after+immobilization+correlate+with+bone+mineral+density+but+not+with+magnetic+resonance+or+ultrasound+imaging.">Mechanical alterations of rabbit Achilles' tendon after immobilization correlate with bone mineral density but not with magnetic resonance or ultrasound imaging.</a> Archives of Physical Medicine and Rehabilitation. 88 (12), 1720-1726 (2007).</li><li>Harvey, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stretch+for+the+treatment+and+prevention+of+contractures.">Stretch for the treatment and prevention of contractures.</a> Cochrane Database of Systematic Reviews. 1, Cd007455 (2017).</li><li>Trudel, G., Himori, K., Uhthoff, H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contrasting+alterations+of+apposed+and+unapposed+articular+cartilage+during+joint+contracture+formation.">Contrasting alterations of apposed and unapposed articular cartilage during joint contracture formation.</a> Archives of Physical Medicine Rehabilitation. 86 (1), 90-97 (2005).</li><li>Trudel, G., Uhthoff, H. K., Goudreau, L., Laneuville, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+analysis+of+the+reversibility+of+knee+flexion+contractures+with+time:+an+experimental+study+using+the+rat+model.">Quantitative analysis of the reversibility of knee flexion contractures with time: an experimental study using the rat model.</a> BMC Musculoskeletal Disorders. 15, 338 (2014).</li><li>Trudel, G., Uhthoff, H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contractures+secondary+to+immobility:+is+the+restriction+articular+or+muscular?+An+experimental+longitudinal+study+in+the+rat+knee.">Contractures secondary to immobility: is the restriction articular or muscular? An experimental longitudinal study in the rat knee.</a> Archives of Physical Medicine and Rehabilitation. 81 (1), 6-13 (2000).</li><li>Chimoto, E., Hagiwara, Y., Ando, A., Itoi, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progression+of+an+arthrogenic+motion+restriction+after+immobilization+in+a+rat+experimental+knee+model.">Progression of an arthrogenic motion restriction after immobilization in a rat experimental knee model.</a> Upsala Journal of Medical Sciences. 112 (3), 347-355 (2007).</li><li>Ando, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remobilization+does+not+restore+immobilization-induced+adhesion+of+capsule+and+restricted+joint+motion+in+rat+knee+joints.">Remobilization does not restore immobilization-induced adhesion of capsule and restricted joint motion in rat knee joints.</a> Tohoku Journal of Experimental Medicine. 227 (1), 13-22 (2012).</li><li>Abdel, M. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+joint+contracture+on+the+contralateral+unoperated+limb+in+a+rabbit+knee+contracture+model:+a+biomechanical+and+genetic+study.">Effects of joint contracture on the contralateral unoperated limb in a rabbit knee contracture model: a biomechanical and genetic study.</a> Journal of Orthopaedic Research. 30 (10), 1581-1585 (2012).</li><li>Hildebrand, K. A., Sutherland, C., Zhang, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rabbit+knee+model+of+post-traumatic+joint+contractures:+the+long-term+natural+history+of+motion+loss+and+myofibroblasts.">Rabbit knee model of post-traumatic joint contractures: the long-term natural history of motion loss and myofibroblasts.</a> Journal of Orthopaedic Research . 22 (2), 313-320 (2004).</li><li>Klein, L., Player, J. S., Heiple, K. G., Bahniuk, E., Goldberg, V. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isotopic+evidence+for+resorption+of+soft+tissues+and+bone+in+immobilized+dogs.">Isotopic evidence for resorption of soft tissues and bone in immobilized dogs.</a> Journal of Bone and Joint Surgery. American Volume. 64 (2), 225-230 (1982).</li></ol>

The authors have no disclosures or conflicts of interest to declare.

The rat knee arthrometer was developed to reproducibly and reliably determine the maximum extension of the rat knee following an intervention. Advantages of this device include the consistent generation of torque across the knee joint with a constant arm length and extension force. Another advantage includes the ability to set the torque at a level that allows repetitive testing on the same joint to evaluate the influence of different articular structures on knee ROM, such as muscle, capsule, or ligament. For example, following testing of the fully intact joint, the posterior transarticular knee muscles could be divided and arthrometer testing repeated in order to determine the arthrogenic contribution to extension limitation11.
Specific mechanical features of the arthrometer that optimize measurement accuracy and precision include the grooved clamp, which is designed to prevent rotation of the femur during testing (Figure 1). The distal two metal upright posts engage the leg posteriorly, pushing the knee into extension in a clockwise direction, and minimize the risk of posterior dislocation of the tibia on the femur during testing (Figure 1). The height of the posts and anterior overhang of the upper upright link ensure that the tibia does not slip off the posts. The ability of the upright posts to rotate and maintain their position on the tibia just proximal to the calcaneus ensures constant torque. Four torques are tested in sequence: 2.53 N-cm, 7.53 N-cm, 12.53 N-cm, and 17.53 N-cm. The highest torque level was determined to be the amount of force that led to capsular failure in normal (unoperated) rat knee joints (i.e., extension surpassing 0&#176;) after division of all transarticular muscle. The lowest torque was the point of resistance to angular motion just above measurable amounts on normal rat knee joints. The middle two torques were set to be approximately midway between the highest and lowest torques.
Other methods for measuring joint ROM at specific torques have been described for both rat and other animal models12,13,14,15,16. Some of the advantages of our model over these other systems include a convenient size that allows benchtop placement of the device without the need for special facilities. Other models may also require disarticulation of the limb being studied while the model presented here does not. Mechanically, the arcing pathway of the post applies the extension force to the distal leg, following the angular progression of the knee, thus maintaining a consistent angle of force application. The stage of the arthrometer allows the placement of the entire rat on the measuring tool, allowing the testing of all in situ articular structures that may contribute to lost ROM without violating joint anatomy. While the ethics protocol for our lab excludes testing on live animals, this would theoretically be possible with appropriate analgesia and post-test sacrificing protocols.
The arthrometer does present some disadvantages. The device was sized to the adult rat knee to ensure that the moveable arm was at a length to ensure it would not slip off the leg and the leg would not slip off the arm. Younger rats, or smaller and larger species would benefit from appropriately-sized components. Additionally, a reprogramming of the optimal moment arm and force (torque) would be required. If, for example a larger or smaller animal was used, adjusting the length of the moment arm and/or amount of force applied to reach optimal torque may be necessary. Other parts of the arthrometer might also need to be resized, according to the size of the animal. While the movements of the arthrometer are user-independent, joint measurement using ImageJ may be subject to human error. We have found however that, using the methods presented here, there is high intra-rater and inter-rater reliability with intraclass correlation coefficients of 0.987 and 0.903, respectively. Because the highest torque often damages the articular structures during testing, a valid inter-rater reliability for the animal placement and activation of the arthrometer is difficult to determine. To avoid measurement error that might be associated with having more than one investigator perform this part of the protocol, we recommend having the same investigator secure the rats to the arthrometer for the duration of a study so that any bias is consistent between experimental and control knees. Because the hamstrings cross both the knee and hip joints, retroversion of the pelvis may occur during testing at torques 1 and 2 prior to myotomy. This may contribute to increases in knee extension for both experimental and control knees at these torques. Finally, results may vary from true in vivo ROM as the protocol was developed to test euthanized rather than live animals.
While we described the use of a device for evaluating the effects of immobility on the rat knee joint, other conditions affecting joint ROM could also be studied. There are numerous examples, some of which include effects of trauma, increased muscular tone secondary to central nervous system insult, or genetic modifications relating to neuromuscular disease. Respective interventions such as stem cell application to the knee joint, neuromuscular junction blockade, or gene therapy treatments that help discover new treatment options could also be assessed using the device.

Having full range of motion (ROM) of the joints is critical for health and well-being1. A loss in joint passive ROM is called a contracture2. Joint contractures may arise from numerous conditions, including prolonged bedrest, paralysis, joint arthroplasty, burns, infection, and neurologic conditions1,3,4,5. A contracture of the knee can be disabling as it accelerates joint degeneration, increases the risk of falls and detrimentally affects a person&#39;s ability to perform basic functional tasks including walking, sitting, and climbing stairs6,7.
Once established, contractures of the knee are difficult to treat, and therefore determining which patients are at the highest risk of developing this condition is essential for prevention and avoidance of contracture-associated morbidity8. Experiments are designed to evaluate 1) the conditions causing or influencing knee joint contractures, 2) the severity of contractures, 3) their temporal progression, 4) the tissues involved in the contracture, 5) their reversibility as well as 6) the usefulness of various preventive and curative interventions on knee joint ROM. For all of these experiments, a valid, objective, precise and reproducible method for measuring the ROM is critical. Other ancillary measures (energy expenditure, histomorphometry, gene expression and protein content) are useful markers to understand the pathophysiology of joint contractures, but the mechanical limitation is what limits the patient and leads to disability. Some of the challenges in this area of research includes the heterogeneous methods by which knee ROM may be tested experimentally, as well as a lack of quantitative data9. The use of a variety of different experimental methods leads to results that are not comparable from laboratory to laboratory. This has led to controversy regarding the conditions (such as immobilization or joint arthroplasty) that cause joint contractures10. An automated method of experimentally measuring joint ROM following an intervention is therefore needed.
Here, we describe a user-independent, valid, precise and reproducible protocol for evaluating the rat knee ROM using a custom-built arthrometer linked to a digital camera to precisely measure the knee ROM in extension. We tested the effect of various periods of immobilization on knee ROM. We then describe the methods for measuring ROM at pre-specified torques on the resulting digital images using fixed bony landmarks. Overall, these methods reliably measure rat knee ROM and provide quantitative data.

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		<tr height="64">
			<td height="64" style="height:64px;width:251px;">Arthrometer</td>
			<td style="width:205px;">The Ottawa Hospital Rehabilitation Centre - Rehabilitation Engineering&#160;</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;"></td>
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			<td style="width:119px;">EOS-500D</td>
			<td style="width:167px;">Commonly known as EOS Rebel T1i</td>
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			<td height="22" style="height:22px;width:251px;">ImageJ</td>
			<td style="width:205px;">National Institutes of Health</td>
			<td style="width:119px;">Version 1.45s</td>
			<td style="width:167px;"></td>
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			<td style="width:167px;">Kit Includes:&#160; Forceps: medium points, nickel-plated 
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			&#160;Bent dissecting needle: stainless steel with plastic handle 
			&#160;Straight dissecting needle: stainless steel with plastic handle 
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			<td style="width:205px;">Stanley</td>
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			<td>RCA</td>
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</table>

using a knee arthrometer to evaluate tissue-specific contributions to knee flexion contracture in the rat

Normal knee range of motion (ROM) is critical to well-being and allows one to perform basic activities such as walking, climbing stairs and sitting. Lost ROM is called a joint contracture and results in increased morbidity. Due to the difficulty of reversing established knee contractures, early detection is important, and hence, knowing risk factors for their development is essential. The rat represents a good model with which the effect of an intervention can be studied due to the similarity of rat knee anatomy to that of humans, the rat's ability to tolerate long durations of knee immobilization in flexion, and because mechanical data can be correlated with histologic and biochemical analysis of knee tissue.
Using an automated arthrometer, we demonstrate a validated, precise, reproducible, user-independent method of measuring the extension ROM of the rat knee joint at specific torques. This arthrometer can be used to determine the effects of interventions on knee joint ROM in the rat.

The amount of knee extension determined for various periods of immobility are summarized for increasing durations of immobility and show that more severe contractures were produced following increasing lengths of immobilization. Representative results using ImageJ are shown in Figure 3.
The ability to measure maximum extension of rat knees in a valid, precise and reproducible, user-independent manner that reduces bias in the data. In the example provided, we evaluated the maximum knee extension following 16 weeks of immobilization for 7 rats, comparing the immobilized (experimental) limb to the non-immobilized contralateral limb. The limb chosen for immobilization alternated from one rat to the next (e.g., rat 1 had the right knee immobilized, rat 2 the left). The investigator measuring the angles was blinded to which side was immobilized during measurements. The results are presented in Figure 3. For the immobilized knee, the ability for maximum extension was reduced compared to the contralateral. Division of transarticular muscles eliminates the myogenic component of the flexion contracture. Following myotomy, the maximal extension capability for the experimental and contralateral knee increased; however, the experimental knee continued to demonstrate a flexion contracture (Figure 3).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58084/58084fig1.jpg" /> 
Figure 1: Rat knee arthrometer. (A) Entire apparatus (B) Representative image of animal within arthrometer (C) Electronics display and clamps for arthrometer. (D) Enlarged image of electronics display. Numbers indicate the various torques being applied: torque 1 = 2.53 N-cm, torque 2 = 7.53 N-cm, Torque 3 = 12.53 N-cm, torque 4 = 17.53 N-cm. (E) Enlarged image of the femoral clamp and tibial pushing apparatus. The femoral clamp is fixed to the stage. The tibial moving arm has 2 upright posts that fix the distal lower extremity and move the knee into extension. Arrowhead and chevron indicate the femur clamp and the moveable arm, respectively. <a href="https://www.jove.com/files/ftp_upload/58084/58084fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/58084/58084fig2.jpg" /> 
Figure 2: Arthrometer and experimental rat for evaluation.&#160;(A) Knee extension of the posterior limb is measured using the tibial line drawn from the lateral femoral condyle to the lateral malleolus and the femoral line drawn from the lateral condyle to the middle of the femur clamp. Arrowhead and chevron indicate the femur clamp and the moveable arm, respectively. (B) High magnification images of the femoral condyle and (C) High magnification of lateral malleolus.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/58084/58084fig3.jpg" /> 
Figure 3: Immobilized and contralateral rat knee range of motion following 16 weeks immobilization. For both knees, after testing knee extension with all articular structures intact (n=7), a myotomy of the trans-articular muscles was performed to determine the arthrogenic limitation on ROM. Data are presented as mean degrees from full extension (using the convention 0&#176; = full extension) with error bars representing standard deviation. * represents p &#60; 0.01 using the independent-samples T-test.&#160;<a href="https://www.jove.com/files/ftp_upload/58084/58084fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Using a Knee Arthrometer to Evaluate Tissue-specific Contributions to Knee Flexion Contracture in the Rat at JoVE.com

Using a Knee Arthrometer to Evaluate Tissue-specific Contributions to Knee Flexion Contracture in the Rat

The goal of the protocol is to measure the extension range of motion of the rat knee. The effects of various diseases that increase the stiffness of the knee joint and the effectiveness of treatments can be quantified.

Normal knee range of motion (ROM) is critical to well-being and allows one to perform basic activities such as walking, climbing stairs and sitting. Lost ...

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6.6K Views.  Elizabeth Bruyère Hospital. The goal of the protocol is to measure the extension range of motion of the rat knee. The effects of various diseases that increase the stiffness of the knee joint and the effectiveness of treatments can be quantified.

Video: Using a Knee Arthrometer to Evaluate Tissue-specific Contributions to Knee Flexion Contracture in the Rat

The Measurement and Treatment of Suppression in Amblyopia

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current estimates put the prevalence of amblyopia at approximately 1-3%1-3, the majority of cases being monocular2. Amblyopia is most frequently caused by ocular misalignment (strabismus), blur induced by unequal refractive error (anisometropia), and in some cases by form deprivation.
Although amblyopia is initially caused by abnormal visual input in infancy, once established, the visual deficit often remains when normal visual input has been restored using surgery and/or refractive correction. This is because amblyopia is the result of abnormal visual cortex development rather than a problem with the amblyopic eye itself4,5 . Amblyopia is characterized by both monocular and binocular deficits6,7 which include impaired visual acuity and poor or absent stereopsis respectively. The visual dysfunction in amblyopia is often associated with a strong suppression of the inputs from the amblyopic eye under binocular viewing conditions8. Recent work has indicated that suppression may play a central role in both the monocular and binocular deficits associated with amblyopia9,10 .
Current clinical tests for suppression tend to verify the presence or absence of suppression rather than giving a quantitative measurement of the degree of suppression. Here we describe a technique for measuring amblyopic suppression with a compact, portable device11,12 . The device consists of a laptop computer connected to a pair of virtual reality goggles. The novelty of the technique lies in the way we present visual stimuli to measure suppression. Stimuli are shown to the amblyopic eye at high contrast while the contrast of the stimuli shown to the non-amblyopic eye are varied. Patients perform a simple signal/noise task that allows for a precise measurement of the strength of excitatory binocular interactions. The contrast offset at which neither eye has a performance advantage is a measure of the "balance point" and is a direct measure of suppression. This technique has been validated psychophysically both in control13,14 and patient6,9,11 populations.
In addition to measuring suppression this technique also forms the basis of a novel form of treatment to decrease suppression over time and improve binocular and often monocular function in adult patients with amblyopia12,15,16 . This new treatment approach can be deployed either on the goggle system described above or on a specially modified iPod touch device15.

Amblyopia is a developmental disorder of the visual cortex that is often accompanied by strong suppression of one eye. We present a new technique for measuring and treating interocular suppression in patients with amblyopia that can be deployed using virtual reality goggles or a portable iPod Touch device.

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current ...

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

Limited evidence exists to precisely estimate efficacy and safety differences between parenteral nutrition (PN) prepared using olive-oil-based three-chamber bags (3CBs) and soybean-oil-based compounded bags (CoBs) in hospitalized adult patients. We designed a multicenter, randomized, prospective, open-label, noninferiority protocol to compare the efficacy, safety, and distribution of olive-oil-based 3CBs and soybean-oil-based CoB formulations in adult Chinese patients requiring PN during surgical intervention. Subjects were randomized to receive either one of the study treatments using an interactive voice or web-based recognition system in accordance with the randomization code. Randomization was further stratified based on the study site and surgical category. Both treatment groups received similar amounts of calories and protein. In addition, the two study treatments contained a similar composition of the amino-acid component. The only difference between the two PN formulations was the lipid constitution. The duration of administration of study treatments was a minimum of 5 days up to a maximum of 14 days after the surgical procedure. The primary efficacy endpoint was serum prealbumin levels on day 5 of the study. Noninferiority was proved if the anti-log of the lower bound of the 95% confidence interval (CI) of the treatment difference was at least 0.80. Other efficacy measures included treatment preparation time; duration to achieve tolerability of oral nutrition; associated infectious complications; length of hospitalization; and laboratory assessment of markers of nutrition, inflammation, metabolism, and oxidative stress. A total of 458 patients were enrolled in the study. The results showed that olive-oil-based 3CBs were non-inferior to soybean-based CoBs, besides being well tolerated. The infection rate was found to be significantly lower in the olive-oil-based 3CB group. Thus, this study may be used as a reference for future research on lipid emulsion and 3CBs.

Here, we present a protocol for a study comparing the efficacy, safety, and delivery of olive-oil-based 3CB and soybean-oil-based CoB formulations in adults requiring parenteral nutrition. The results revealed that olive-oil-based 3CBs is non-inferior and well tolerated compared to soybean formulations.

Limited evidence exists to precisely estimate efficacy and safety differences between parenteral nutrition (PN) prepared using olive-oil-based ...

The Lower Body Positive Pressure Treadmill for Knee Osteoarthritis Rehabilitation

Here, based on a clinician&rsquo;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in addition to a clinical, functional assessment methodology, including details for further encouragement of the development of non-drug surgical intervention strategies in knee osteoarthritis patients. However, we only present the effect of LBPP training in improvement of pain and knee function in one patient through three-dimensional gait analysis. The exact, long-term effects of this approach should be explored in future studies.

Here, based on a clinician&#8217;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in addition to a clinical, functional assessment methodology, including details for further encouragement of the development of non-drug surgical intervention strategies in knee osteoarthritis patients. However, we only present the effect of LBPP training in improvement of pain and knee function in one patient through three-dimensional gait analysis. The exact, long-term effects of this approach should be explored in future studies.

Here, based on a clinician&rsquo;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in ...

A Non-Invasive Method for Generating the Cyclic Loading-Induced Intra-Articular Cartilage Lesion Model of the Rat Knee

The pathophysiology of primary osteoarthritis (OA) remains unclear. However, a specific subclassification of OA in relatively younger age groups is likely correlated with a history of articular cartilage damage and ligament avulsion. Surgical animal models of OA of the knee play an important role in understanding the onset and progression of post-traumatic OA and aid in the development of novel therapies for this disease. However, non-surgical models have been recently considered to avoid traumatic inflammation that could affect the evaluation of the intervention. 
In this study, an intra-articular cartilage lesion rat model induced by in vivo cyclic compressive loading was developed, which allowed researchers to (1) determine the optimal magnitude, speed, and duration of load that could cause focal cartilage damage; (2) assess post-traumatic spatiotemporal pathological changes in chondrocyte vitality; and (3) evaluate the histological expression of destructive or protective molecules that are involved in the adaptation and repair mechanisms against joint compressive loads. This report describes the experimental protocol for this novel cartilage lesion in a rat model.

Here, we present the cyclic loading-induced intra-articular cartilage lesion model of the rat knee, generated by 60 cyclic compressions over 20 N, resulting in damage to the femoral condylar cartilage in rats.

The pathophysiology of primary osteoarthritis (OA) remains unclear. However, a specific subclassification of OA in relatively younger age groups is likely ...

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.

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 ...

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 ...

In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty

Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage anteromedial osteoarthritis (AMOA). The key to UKA is the flexion-extension gap balance, which is closely related to postoperative complications such as bearing dislocation, bearing wear, and arthritis progression. The traditional gap balance assessment is performed by indirectly sensing the tension of the medial collateral ligament by a gap gauge. It relies on the surgeon's feel and experience, which is imprecise and difficult for beginners. To accurately assess the flexion-extension gap balance of UKA, we developed a wireless sensor combination consisting of a metal base, a pressure sensor, and a cushion block. After osteotomy, the insertion of a wireless sensor combination allows the real-time measurement of intra-articular pressure. It accurately quantifies the flexion-extension gap balance parameters to guide further femur grinding and tibia osteotomy, to improve the accuracy of gap balance. We conducted an in vitro experiment with the wireless sensor combination. the results showed that there was a difference of 11.3 N after applying the traditional method of flexion-extension gap balance performed by an experienced expert.

In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty

This protocol presents a cadaveric study of a wireless sensor used in medial unicompartmental knee arthroplasty. The protocol includes the installation of an angle measuring device, standardized Oxford unicompartmental knee arthroplasty osteotomy, preliminary assessment of flexion-extension balance, and application of the sensor to measure flexion-extension gap pressure.

Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage anteromedial osteoarthritis (AMOA). The key to UKA is the ...

Standardized Tuina Manipulation for Knee Osteoarthritis in Rats

Tuina Manipulation to Reduce Inflammation and Cartilage Loss in Knee Osteoarthritis Rats

Clinical trials suggest that Tuina manipulation is effective in treating knee osteoarthritis (KOA), while further studies are required to discover its mechanism. Therefore, the manipulation of animal models of knee osteoarthritis is critical. This protocol provides a standard process for Tuina manipulation on KOA rats and a preliminary exploration of the mechanism of Tuina for KOA. The press and kneading manipulation method (a kind of Tuina manipulation that refers to pressing and kneading the specific area of the body surface) is applied on 5 acupoints around the knee joint of rats. The force and frequency of the manipulation were standardized by finger pressure recordings, and the position of the rat during manipulation is described in detail in the protocol. The effect of manipulation can be measured by pain behavior tests and microscopic findings in synovial and cartilage. KOA rats showed significant improvement in pain behavior. The synovial tissue inflammatory infiltration was reduced in the Tuina group, and the expression of tumor necrosis factor (TNF)-&#945; was significantly lower. Compared to the control group, chondrocyte apoptosis was less in the Tuina group. This study provides a standardized protocol for Tuina manipulation on KOA rats and preliminary proof that the therapeutic effects of Tuina may be related to reducing synovial inflammation and delayed chondrocyte apoptosis.

Author Spotlight: Understanding the Mechanism of Tuina Manipulation in Rats 

We present a protocol for Tuina manipulation performed on plaster-immobilized-induced knee osteoarthritis rats. Based on the preliminary results, it suggested that the efficacy of the method relied on the reduction of inflammation and cartilage loss.

Clinical trials suggest that Tuina manipulation is effective in treating knee osteoarthritis (KOA), while further studies are required to discover its ...

Standardized Tuina Protocol for Rat DRG Compression Model

Analgesic Effect of Tuina on Rat Models with Compression of the Dorsal Root Ganglion Pain

Neuropathic pain is a prevalent condition that affects 6.9%-10% of the population and results from nerve damage due to various etiologies, such as lumbar disc herniation, spinal canal stenosis, and intervertebral foramen stenosis. Although Tuina, a traditional Chinese manual therapy, has shown analgesic effects in clinical practice for the treatment of neuropathic pain, its underlying neurobiological mechanisms remain unclear. Animal models are essential for elucidating the basic principles of Tuina. In this study, we propose a standardized Tuina protocol for rats with compression of the dorsal root ganglion (DRG), which involves inducing DRG compression by inserting a stainless steel rod into the intervertebral foramen, performing Tuina manipulation with specific parameters of location, intensity, and frequency in a controlled environment, and assessing the behavioral and histopathological outcomes of Tuina treatment. This article also discusses the potential clinical implications and limitations of the study and suggests directions for future research on Tuina.

Author Spotlight: Analgesic Effect of Tuina on Rat Models with Compression of the Dorsal Root Ganglion Pain  

This article presents a manipulation for treating chronic compression of the dorsal root ganglion in rats using Tuina therapy, along with a method for evaluating its effectiveness based on pain behavior and histopathological results.

Neuropathic pain is a prevalent condition that affects 6.9%-10% of the population and results from nerve damage due to various etiologies, such as lumbar ...

Treating Knee Osteoarthritis with Tuina in a Rabbit Model

Tuina Intervention in Rabbit Model of Knee Osteoarthritis

Knee osteoarthritis (KOA) is mainly characterized by degenerative changes in the knee joint's cartilage and surrounding soft tissues. The efficacy of Tuina in treating KOA has been confirmed, but the underlying mechanism needs to be investigated. This study aims to establish a scientifically feasible KOA rabbit model treated with Tuina to reveal the underlying mechanisms. For this, 18, 6-month-old normal-grade male New Zealand rabbits were randomly divided into sham, model, and Tuina groups, with 6 rabbits in each group. The KOA model was established by injecting 4% papain solution into the knee joint cavity. The Tuina group was intervened with Tuina combined with the knee joint rotary correction method for 4 weeks. Only the standard grasping and fixation were performed in sham and model groups. At the end of the 1-week intervention, the knee joint range of motion (ROM) was observed, and cartilage hematoxylin-eosin (HE) staining was done. The study shows that Tuina could inhibit chondrocyte apoptosis, repair cartilage tissue, and restore knee joint ROM. In conclusion, this study demonstrates the scientific feasibility of Tuina treatment for KOA model rabbits, highlighting its potential application in the study of KOA and similar knee joint-related conditions.

Author Spotlight: Using a Rabbit Model to Explore the Efficacy of Tuina in Treating Knee Osteoarthritis 

The protocol describes a method for Tuina intervention in a rabbit model of knee osteoarthritis.

Knee osteoarthritis (KOA) is mainly characterized by degenerative changes in the knee joint's cartilage and surrounding soft tissues. The efficacy of ...

Using a Knee Arthrometer to Evaluate Tissue-specific Contributions to Knee Flexion Contracture in the Rat

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Chapters in this video

The Measurement and Treatment of Suppression in Amblyopia

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

The Lower Body Positive Pressure Treadmill for Knee Osteoarthritis Rehabilitation

A Non-Invasive Method for Generating the Cyclic Loading-Induced Intra-Articular Cartilage Lesion Model of the Rat Knee

Knee Arthrocentesis in Adults

Fu's Subcutaneous Needling for Knee Osteoarthritis Pain

In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty

Tuina Manipulation to Reduce Inflammation and Cartilage Loss in Knee Osteoarthritis Rats

Analgesic Effect of Tuina on Rat Models with Compression of the Dorsal Root Ganglion Pain

Tuina Intervention in Rabbit Model of Knee Osteoarthritis