This work was supported by grants from the CIHR Neuromuscular Research Partnership (JNM &#x2013; 90959; to J.A.E.B).

Prior to using this model, investigators must have received approval for the surgical protocol from their institution&#39;s animal use governing body. The model is approved by the Research Ethics Board, Hamilton Health Sciences Corporation, McMaster University (AUP # 10-04-24) and is carried out in strict accordance with the recommendations of the Canadian Council on Animal Care.
1. Mouse Preparation
<ol>
	<li>Weigh the mouse. Induce anesthesia with 5% isoflurane or 2% halothane. The circuit used should ensure adequate scavenging of the anesthetic to protect the surgeon. &#160;After 2-3 min the animal&#39;s respiration will slow. Ensure the blink reflex is absent and pinch the &#160;interdigital spaces in the paw to confirm surgical anesthesia (i.e. no response by the mouse). Apply ophthalmic lubricant to the eye, to prevent drying of the cornea during surgery.</li>
	<li>Shave the lateral thigh and buttock from the sciatic notch to the knee and disinfect with proviodine. Shaving will keep the site of the incision hair free to ensure adequate visualization of the surgical field and to minimize interference with nerve dissection and transection. The sciatic notch, which is superior and posterior to the femur, can be identified by palpation.</li>
</ol>
2. Operative Procedure
<ol>
	<li>Reduce inhalational isoflurane to 2% (halothane 1%) and place the mouse on its side (side intended for surgery facing up), under an operating or dissecting microscope. Alternatively surgery can be performed with surgical loupes since 3.5X magnification is satisfactory for an adult (20-25 g) mouse.</li>
	<li>Don sterile gloves. Identify the sciatic notch by palpation. Using a scalpel, incise the skin of the lateral thigh from the sciatic notch to the knee (approximately 1 cm).</li>
	<li>Gently spread the skin. Identify the biceps femoris muscle, which is the flat superficial muscle of the lateral thigh immediately beneath the skin. Using fine scissors, split the biceps femoris muscle along the muscle fibers and hold open with a spring retractor to expose the sciatic nerve and its branches.</li>
	<li>Identify the sciatic nerve immediately deep to the biceps femoris muscle. It can be identified by its characteristic shiny white color and is approximately 0.8 mm in diameter. It runs from the sciatic notch to the knee, branching into the tibial, peroneal and sural nerves at the level of the popliteal fossa.</li>
	<li>Gently separate the tibial from the peroneal and sural nerve branches with ultrafine forceps and spring microdissecting scissors. The tibial nerve is the largest branch and is usually central. It&#39;s important not to crush the nerve while separating the branches. Holding the nerve just on the outer adventicial layer with the ultrafine forceps, and keeping the nerve slack (not taught), will avoid nerve crush and traction injury.</li>
	<li>For complete and lasting denervation, cut the tibial nerve with microdissecting scissors as distally as possible, carefully avoiding the popliteal vessels. Alternatively, for temporary denervation with expected complete reinnervation in 2-4 weeks, the tibial nerve can simply be crushed with ultrafine forceps for 15 sec instead of transected. (Peripheral nerves regrow following injury and will reinnervate target muscle.)</li>
	<li>If complete denervation is required, suture the end of the transected tibial nerve to the anterior surface of the biceps femoris muscle with 10-0 Nylon and re-approximate the biceps femoris with 5-0 Vicryl to prevent aberrant re-innervation of the gastrocnemius and soleus muscles.</li>
	<li>Close the skin with a running 5-0 Vicryl suture.</li>
</ol>
3. Post Operative Care
<ol>
	<li>Turn off the inhalational anesthetic but maintain the flow of oxygen. Administer buprinorphine (or substitute) analgesic subcutaneously.</li>
	<li>Transfer the mouse to a clean cage with no bedding while waking from anesthesia. Keep on a warming blanket within the cage and under direct observation until ambulating.</li>
	<li>Transfer and house in soft bottom cage (not wire) with ample soft bedding.</li>
	<li>Inspect the operative limb daily for condition of the surgical wound and the foot for the development of decubitus heel ulcers or evidence of chewing. Minor problems can be managed with topical antibiotics or antiseptics such as proviodine. Endpoint indicators requiring animal euthanasia are weight loss, evidence of poor self care (ruffled fur), and hunched posture. In addition, animals with major wound disruption or ulcers that do not heal in 1-2 weeks with topical antibiotics or appear to have pain should be sacrificed.</li>
</ol>
4. Denervated Gastrocnemius and Soleus Muscle Harvest
<ol>
	<li>At the post-operative time point desired, weigh the mouse and sacrifice with CO2 overdose.</li>
	<li>Shave the medial aspect of both the operative and contralateral control legs and clean with alcohol. Place the mouse under an operating or dissecting microscope, or alternatively use surgical viewing loupes for magnification.</li>
	<li>On the operative limb, incise the medial calf skin with a scalpel from the ankle to the knee and circumferentially around the ankle. Gently pull the skin with forceps off the muscle and proximally toward the thigh. This exposes all the muscles of the leg. Identify the gastrocnemius muscle, which is the calf muscle that runs from the knee to the ankle on the posterior aspect of the leg and lies immediately underneath the skin. Identify the distal insertion of the biceps femoris muscle, proximal to the gastrocnemius muscle on the medial aspect of the knee. At its distal insertion the biceps femoris appears thin and filmy and overlies the most proximal portion of the gastrocnemius. Using scissors and blunt end dissection, gently separate the distal insertion of the biceps femoris from the gastrocnemius muscle.</li>
	<li>At its distal insertion into the calcaneous, the gastrocnemius muscle tapers into the Achilles tendon. Identify the Achilles tendon, which appears white and sinewy. Hold the Achilles tendon with forceps, taking care not to hold or crush the gastrocnemius muscle, and divide the Achilles tendon from the calcaneus insertion using scissors.</li>
	<li>Still holding the tendon, gently lift the gastrocnemius muscle (pale red) off the deep soleus (deeper red), from the distal insertion towards its origin at the knee (the soleus can be harvested separately).</li>
	<li>Dissect the gastrocnemius off the leg by dividing the origin of the gastrocnemius from the medial and lateral femur chondyles using scissors. Very gentle traction on the muscle facilitates this process. Be careful not to crush the muscle.</li>
	<li>The soleus will now be plainly visible, immediately under the site of the gastrocnemius. Lift the soleus from its insertion on the Achilles tendon to its origin on the posterior calf. If the soleus is inadvertently raised with the gastrocnemius, gently separate it from the harvested specimen. The gastrocnemius (light red) and soleus (dark red) remain easily identifiable in the harvested specimen due to their color differences.</li>
	<li>Weigh the muscles separately on a precision scale.</li>
	<li>Split the muscles vertically, half for snap freezing in liquid nitrogen (for subsequent protein and/or RNA extraction), and half for histology (i.e. morphometric assessment, immunohistology) fixing either in 10% formalin, or frozen fixation in isopentane cooled with liquid nitrogen, as desired.</li>
	<li>Repeat from step 4.3 above on the control, un-operated, side to harvest control gastrocnemius and soleus muscles.</li>
</ol>

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No conflicts of interest are declared.

The tibial nerve transection model of denervation-induced skeletal muscle atrophy is a commonly employed and well validated model in rats. We have adapted this model for use in mice, which allows the investigator to take advantage of the existence of genetically engineered mice and study the process of muscle atrophy in vivo in the absence of proteins crucial to the regulation of muscle mass7,8. The gastrocnemius and soleus muscles, both denervated in this model, can be easily and rapidly dissected wi...

Skeletal muscle denervation, due to traumatic peripheral nerve injury, disease or pharmacologic intervention, results in the immediate loss of muscle voluntary contractile function. Muscle concomitantly begins to atrophy and this atrophy is reversible if timely, good-quality reinnervation occurs1,2. In the absence of reinnervation, myofiber atrophy progresses, and irreversible biologic changes in the muscle occur with muscle fibrosis and myofiber death. Here we demonstrate the tibial nerve transection model, a model of denervation-induced skeletal muscle atrophy and fibrosis, in mice. This model enables scientists to study the physiologic, cellular and molecular biologic mechanisms that underlie muscle atrophy in vivo in the gastrocnemius and soleus muscles. While historically used predominantly in rats, more recent application of this model to knockout and transgenic mouse lines specifically, allows investigators to assess the role of their particular protein(s) of interest in the induction, development and maintenance, or alternatively the resolution of, muscle atrophy and fibrosis in vivo.
The tibial nerve is a mixed motor-sensory peripheral nerve in the rodent hindlimb, and is one of the three terminal branches of the sciatic nerve. Transection of the tibial nerve denervates the gastrocnemius, soleus and plantaris muscles (and the three small deep flexor muscles of the foot including tibialis posterior, flexor digitorum longus and flexor hallicus longus), and is a well standardized and validated model in rats3,4. The gastrocnemius and soleus muscles can be easily dissected at serial time points post tibial nerve transection, fixed and processed for assessment of muscle histology and muscle fiber morphometrics, or flash frozen for extraction of muscle RNA and protein for the purpose of studying, for example, the cellular signaling networks regulating muscle atrophy. The gastrocnemius muscle is a mixed fiber type muscle (type I and type II, although predominantly type II) and the soleus muscle is composed of a large proportion of type I fibers, thereby providing both fast and slow twitch muscle for assessment5,6. The tibial nerve transection model is suitable for studying the process of denervation-induced muscle atrophy in both the short term (days)7 and long term (weeks to months)4,8.
In contrast to the sciatic nerve transection model (a second model of denervation-induced muscle atrophy commonly used in rodents), tibial nerve transection induces less morbidity in the animal, making it a more attractive model. Transection of the sciatic nerve denervates all the muscles of the leg (below the knee) and foot, impairing the animal&#39;s ability to ambulate2, whereas transection of the tibial nerve leaves the peroneal and sural nerve branches of the sciatic nerve intact, thus preserving their target muscles and sensory territories. The mouse is unable to plantar flex or invert the foot, but is able to ambulate easily and the weight bears equally on both hind limbs, thereby significantly diminishing the morbidity of the model. Gait analysis studies evaluating walking patterns have been performed in rats following tibial and sciatic nerve injuries and demonstrate that footprint and weight bearing is better preserved with tibial injury9,10. In addition, in the tibial nerve transection model, the peroneal nerve can be mobilized at a later time point and transferred as a source of delayed reinnervation, if the study design requires3. In contrast, delayed reinnervation in the sciatic nerve transection model necessitates the use of a nerve graft to the sciatic nerve deficit, very significantly increasing the technical difficulty of the model and limiting its use to skilled surgeons.
While the tibial nerve transection model requires familiarity of the operator with sterile operative technique in animal surgery, both the tibial nerve and calf muscles it innervates are easily accessible and identifiable for manipulation, so that individuals who are not surgeons, or highly experienced with animal surgery, can readily master this model.

<table><tbody><tr><td colspan="4">&lt;strong&gt;Reagents and Materials&lt;/strong&gt;</td></tr><tr><td>10-0 Nylon suture</td><td>Ethicon</td><td>2850G</td><td></td></tr><tr><td>5-0 Vicryl suture</td><td>Ethicon</td><td>J553G</td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Equipment&lt;/strong&gt;</td></tr><tr><td>Spring microdissecting scissors</td><td>Fine Surgical Tools</td><td>15021-15</td><td></td></tr><tr><td>Ultra fine forceps</td><td>Fine Surgical Tools</td><td>11370-40</td><td></td></tr><tr><td>Non locking micro needle holder (driver)</td><td>Fine Surgical Tools</td><td>12076-12</td><td></td></tr><tr><td>Spring retractor</td><td>Fine Surgical Tools</td><td>17000-02</td><td></td></tr></tbody></table>

tibial nerve transection - a standardized model for denervation-induced skeletal muscle atrophy in mice

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. Although originally developed and used extensively in the rat due to its larger size, the tibial nerve in mice is big enough that it can be easily manipulated with either crush or transection, leaving the peroneal and sural nerve branches of the sciatic nerve intact and thereby preserving their target muscles. Thus, this model offers the advantages of inducing less morbidity and impediment of ambulation than the sciatic nerve transection model and also allows investigators to study the physiologic, cellular and molecular biologic mechanisms regulating the process of muscle atrophy in genetically engineered mice. The tibial nerve supplies the gastrocnemius, soleus and plantaris muscles, so its transection permits the study of denervated skeletal muscle composed of fast twitch type II fibers and/or slow twitch type I fibers. Here we demonstrate the tibial nerve transection model in the C57Black6 mouse. We assess the atrophy of the gastrocnemius muscle, as a representative muscle, at 1, 2, and 4 weeks post-denervation by measuring muscle weights and fiber type specific cross-sectional area on paraffin-embedded histologic sections immunostained for fast twitch myosin.

Tibial nerve transection denervates the gastrocnemius, soleus and plantaris muscles of the calf. Here we assess the development of atrophy in the gastrocnemius muscle, as a representative muscle. Gastrocnemius muscle was harvested from 2-3 months old C57Black 6 mice (Jackson Laboratories) denervated for 1, 2, or 4 weeks. Muscle weights progressively decrease (Figure 1), as does the cross-sectional area of type II fast twitch muscle fibers (Figure 2), over time. The gastrocnemius is a mix...

Watch this Scientific Journal Video about Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice at JoVE.com

Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of skeletal muscle atrophy. The model surgical protocol is described and demonstrated in C57Black6 mice. &#160;

The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. ...

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Universidad de Cartagena UDEC

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Medicine

24.3K Views.  St Michaels Hospital. The tibial nerve transection model is a well-tolerated, validated, and reproducible model of skeletal muscle atrophy. The model surgical protocol is described and demonstrated in C57Black6 mice.  

Video: Tibial Nerve Transection - A Standardized Model for Denervation-induced Skeletal Muscle Atrophy in Mice

The Spared Nerve Injury (SNI) Model of Induced Mechanical Allodynia in Mice

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared nerve injury (SNI) model induces symptoms of neuropathic pain such as mechanical allodynia i.e. pain due to tactile stimuli that do not normally provoke a painful response [1]. 
The SNI mouse model involves ligation of two of the three branches of the sciatic nerve (the tibial nerve and the common peroneal nerve), while the sural nerve is left intact [2]. The lesion results in marked hypersensitivity in the lateral area of the paw, which is innervated by the spared sural nerve. The non-operated side of the mouse can be used as a control. The advantages of the SNI model are the robustness of the response and that it doesn&#x2019;t require expert microsurgical skills.
The threshold for mechanical pain response is determined by testing with von Frey filaments of increasing bending force, which are repetitively pressed against the lateral area of the paw [3], [4]. A positive pain reaction is defined as sudden paw withdrawal, flinching and/or paw licking induced by the filament. A positive response in three out of five repetitive stimuli is defined as the pain threshold. 
As demonstrated in the video protocol, C57BL/6 mice experience profound allodynia as early as the day following surgery and maintain this for several weeks.

The Spared Nerve Injury SNI Model of Induced Mechanical Allodynia in Mice

The Spared Nerve Injury animal model is described here as a mouse model of peripheral neuropathic pain following partial denervation of the sciatic nerve by lesioning the tibial and common peroneal nerve branches, leaving the remaining sural nerve intact. Behavioral modification resulting from mechanical allodynia is quantified by von Frey filaments.

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared ...

Reproducible Mouse Sciatic Nerve Crush and Subsequent Assessment of Regeneration by Whole Mount Muscle Analysis

Regeneration in the peripheral nervous system (PNS) is widely studied both for its relevance to human disease and to understand the robust regenerative response mounted by PNS neurons thereby possibly illuminating the failures of CNS regeneration1. Sciatic nerve crush (axonotmesis) is one of the most common models of peripheral nerve injury in rodents2. Crushing interrupts all axons but Schwann cell basal laminae are preserved so that regeneration is optimal3,4. This allows the investigator to study precisely the ability of a growing axon to interact with both the Schwann cell and basal laminae4. Rats have generally been the preferred animal models for experimental nerve crush. They are widely available and their lesioned sciatic nerve provides a reasonable approximation of human nerve lesions5,4. Though smaller in size than rat nerve, the mouse nerve has many similar qualities. Most importantly though, mouse models are increasingly valuable because of the wide availability of transgenic lines now allows for a detailed dissection of the individual molecules critical for nerve regeneration6, 7. Prior investigators have used multiple methods to produce a nerve crush or injury including simple angled forceps, chilled forceps, hemostatic forceps, vascular clamps, and investigator-designed clamps8,9,10,11,12. Investigators have also used various methods of marking the injury site including suture, carbon particles and fluorescent beads13,14,1. We describe our method to obtain a reproducibly complete sciatic nerve crush with accurate and persistent marking of the crush-site using a fine hemostatic forceps and subsequent carbon crush-site marking. As part of our description of the sciatic nerve crush procedure we have also included a relatively simple method of muscle whole mount we use to subsequently quantify regeneration.

In this report we describe a method to crush mouse sciatic nerve. This method uses readily available hemostatic forceps and easily and reproducibly produces complete sciatic nerve crush. In addition, we describe a method to prepare muscle whole mounts suitable for analysis of nerve regeneration after sciatic nerve crush.

Regeneration in the peripheral nervous system (PNS) is widely studied both for its relevance to human disease and to understand the robust regenerative ...

Neuroscience

Facial Nerve Axotomy in Mice: A Model to Study Motoneuron Response to Injury

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and either cut or crush it to induce peripheral nerve injury. Advantages of this surgery are its simplicity, high reproducibility, and the lack of effect on vital functions or mobility from the subsequent facial paralysis, thus resulting in a relatively mild surgical outcome compared to other nerve injury models. A major advantage of using a cranial nerve injury model is that the motoneurons reside in a relatively homogenous population in the facial motor nucleus in the pons, simplifying the study of the motoneuron cell bodies. Because of the symmetrical nature of facial nerve innervation and the lack of crosstalk between the facial motor nuclei, the operation can be performed unilaterally with the unaxotomized side serving as a paired internal control. A variety of analyses can be performed postoperatively to assess the physiologic response, details of which are beyond the scope of this article. For example, recovery of muscle function can serve as a behavioral marker for reinnervation, or the motoneurons can be quantified to measure cell survival. Additionally, the motoneurons can be accurately captured using laser microdissection for molecular analysis. Because the facial nerve axotomy is minimally invasive and well tolerated, it can be utilized on a wide variety of genetically modified mice. Also, this surgery model can be used to analyze the effectiveness of peripheral nerve injury treatments. Facial nerve injury provides a means for investigating not only motoneurons, but also the responses of the central and peripheral glial microenvironment, immune system, and target musculature. The facial nerve injury model is a widely accepted peripheral nerve injury model that serves as a powerful tool for studying nerve injury and regeneration.

We present a surgical protocol detailing how to perform a cut or crush axotomy on the facial nerve in the mouse. The facial nerve axotomy can be employed to study the physiological response to nerve injury and test therapeutic techniques.

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and ...

Cutaneous Surgical Denervation:  A Method for Testing the Requirement for Nerves in Mouse Models of Skin Disease

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies have suggested that nerves may also modulate skin disorders including atopic dermatitis, psoriasis and cancer. Here, we describe protocols for testing the requirement for nerves in maintaining a cutaneous mechanosensory organ, the touch dome (TD). Specifically, we discuss methods for genetically labeling, harvesting and visualizing TDs by whole-mount staining, and for performing unilateral surgical denervation on mouse dorsal back skin. Together, these approaches can be used to directly compare TD morphology and gene expression in denervated as well as sham-operated skin from the same animal. These methods can also be readily adapted to examine the requirement for nerves in mouse models of skin pathology. Finally, the ability to repeatedly sample the skin provides an opportunity to monitor disease progression at different stages and times after initiation.

This article includes detailed protocols for genetic labeling of mouse skin, surgical denervation, skin biopsy and visualizing labeled epithelia by whole-mount &#946;-galactosidase staining. These methods can be used to test the requirement for nerves in mouse models of normal and pathological skin.

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies ...

Maximum Isometric Tetanic Force Measurement of the Tibialis Anterior Muscle in the Rat

Traumatic nerve injuries result in substantial functional loss and segmental nerve defects often necessitate the use of autologous interposition nerve grafts. Due to their limited availability and associated donor side morbidity, many studies in the field of nerve regeneration focus on alternative techniques to bridge a segmental nerve gap. In order to investigate the outcomes of surgical or pharmacological experimental treatment options, the rat sciatic nerve model is often used as a bioassay. There are a variety of outcome measurements used in rat models to determine the extent of nerve regeneration. The maximum output force of the target muscle remains the most relevant outcome for clinical translation of experimental therapies. Isometric force measurement of tetanic muscle contraction has previously been described as a reproducible and valid technique for evaluating motor recovery after nerve injury or repair in both rat and rabbit models. In this video, we will provide a step-by-step instruction of this invaluable procedure for assessment of functional recovery of the tibialis anterior muscle in a rat sciatic nerve defect model using optimized parameters. We will describe the necessary pre-surgical preparations in addition to the surgical approach and dissection of the common peroneal nerve and tibialis anterior muscle tendon. The isometric tetanic force measurement technique will be detailed. Determining the optimal muscle length and stimulus pulse frequency is explained and measuring the maximum tetanic muscle contraction is demonstrated.

Evaluation of motor recovery remains the benchmark outcome measure in experimental peripheral nerve studies. The isometric tetanic force measurement of the tibialis anterior muscle in the rat is an invaluable tool to assess functional outcomes after reconstruction of sciatic nerve defects. The methods and nuances are detailed in this article.

Traumatic nerve injuries result in substantial functional loss and segmental nerve defects often necessitate the use of autologous interposition nerve ...

Modified Spared Nerve Injury Surgery Model of Neuropathic Pain in Mice

Spared nerve injury (SNI) is an animal model that mimics the cardinal symptoms of peripheral nerve injury for studying the molecular and cellular mechanism of neuropathic pain in mice and rats. Currently, there are two types of SNI model, one to cut and ligate the common peroneal and the tibial nerves with intact sural nerve, which is defined as SNIs in this study, and another to cut and ligate the common peroneal and the sural nerves with intact tibial nerve, which is defined as SNIt in this study. Because the sural nerve is purely sensory whereas the tibial nerve contains both motor and sensory fibers, the SNIt model has much less motor deficit than the SNIs model. In the traditional SNIt mouse model, the common peroneal and the sural nerves are cut and ligated separately. Here a modified SNIt surgery method is described to damage both common peroneal and sural nerves with only one ligation and one cut with a shorter procedure time, which is easier to perform and reduces the potential risk of stretching the sciatic or tibial nerves, and produces similar mechanical hypersensitivity as the traditional SNIt model.

The modified surgery is a simplified method for mouse or rat spared nerve injury model that requires only one ligation and one cut to injure both common peroneal and sural nerves.

Spared nerve injury (SNI) is an animal model that mimics the cardinal symptoms of peripheral nerve injury for studying the molecular and cellular ...

Traumatic Peripheral Nerve Injury in Mice

Traumatic peripheral nerve injury (TPNI) is a common cause of morbidity following orthopedic trauma. Reproducible and precise methods of injuring nerve and denervating muscle have long been a goal in musculoskeletal research. Many traumatically injured limbs have nerve trauma that defines the long-term patient outcome. Over several years, precise methods of producing microsurgical nerve injuries have been developed, including crush, lacerations, and nerve-gap grafting, allowing for reproducible outcome assessments. Moreover, newer methods are created for calibrated crush injuries that offer clinically relevant correlations with outcomes used to assess human patients. The principles of minimal manipulation to ensure low variability in nerve injury allow for adding still more associated tissue injuries into these models. This includes direct muscle crush and other components of limb injury. Finally, atrophy assessment and precise analysis of behavioral outcomes make these methods a complete package for studying musculoskeletal trauma that realistically incorporates all the elements of human traumatic limb injury.

The present protocol describes traumatic peripheral nerve injuries (TPNIs), including precisely calibrated crush, strictly aligned and misaligned laceration, as well as grafted and non-grafted gaps of the sciatic nerve in mice. Custom-designed sensors are developed to gauge nerve trauma, induced with commonly available tools to ensure reproducible post-TPNI outcomes.

Traumatic peripheral nerve injury (TPNI) is a common cause of morbidity following orthopedic trauma. Reproducible and precise methods of injuring nerve ...

Dosage-Adjusted Resistance Training in Mice with a Reduced Risk of Muscle Damage

Progressive resistance training (PRT), which involves performing muscle contractions against progressively greater external loads, can increase muscle mass and strength in healthy individuals and in patient populations. There is a need for precision rehabilitation tools to test the safety and effectiveness of PRT to maintain and/or restore muscle mass and strength in preclinical studies on small and large animal models. The PRT methodology and device described in this article can be used to perform dosage-adjusted resistance training (DART). The DART device can be used as a standalone dynamometer to objectively assess the concentric contractile torque generated by the ankle dorsiflexors in mice or can be added to a pre-existing isokinetic dynamometry system. The DART device can be fabricated with a standard 3D printer based on the instructions and open-source 3D print files provided in this work. The article also describes the workflow for a study to compare contraction-induced muscle damage caused by a single bout of DART to muscle damage caused by a comparable bout of isometric contractions (ISOM) in a mouse model of limb-girdle muscular dystrophy type 2B/R2 (BLAJ mice). The data from eight BLAJ mice (four animals for each condition) suggest that less than 10% of the tibialis anterior (TA) muscle was damaged from a single bout of DART or ISOM, with DART being less damaging than ISOM.

The present protocol describes a unique technique called dosage-adjusted resistance training (DART), which can be incorporated into precision rehabilitation studies performed in small animals, such as mice.

Progressive resistance training (PRT), which involves performing muscle contractions against progressively greater external loads, can increase muscle ...

Surgery and Behavioral Testing in the Tibial Neuroma Transposition Model in Rats

The tibial neuroma transposition (TNT) is a rat model in which allodynia at the neuroma site (tibial nerve) can be independently evaluated from allodynia at the plantar surface of the hind paw innervated by the intact sural nerve. This TNT model is suitable to test therapies for neuroma pain, such as the potential superiority of certain surgical therapies that are already used in the clinic, or to evaluate new drugs and their effect on both pain modalities in the same animal. In this model, a distal lesion (neurotmesis) is made in the tibial nerve, and the proximal nerve end is transposed and fixed subcutaneously and pretibially to enable assessments of the neuroma site with a 15 g Von Frey monofilament. To assess allodynia over the sural nerve, Von Frey monofilaments can be used via the up-down method on the plantar lateral region of the hind paw. After cutting the tibial nerve, mechanical hypersensitivity develops at the neuroma site within 1 week after surgery and persists at least until 12 weeks after surgery. Allodynia at the sural innervated plantar surface develops within 3 weeks after surgery compared to the contralateral limb. At 12 weeks, a neuroma forms on the proximal end of the severed tibial nerve, indicated by dispersion and swirling of axons. For the TNT model surgery, multiple critical (micro)surgical steps need to be followed, and some surgery practice under terminal anesthesia is advised. Compared to other neuropathic pain models, such as the spared nerve injury model, allodynia over the neuroma site can be independently tested from sural nerve hypersensitivity in the TNT model. However, the neuroma site can be tested only in rats, not in mice. The tips and directions provided in this protocol can help research groups working on pain successfully implement the TNT model in their facility.

This protocol describes the tibial neuroma transposition model, which entails a lesion of the tibial nerve with subsequent transposition of the proximal nerve end toward a subcutaneous pretibial or lateral position. Behavioral testing of neuroma pain and plantar hyperalgesia is quantified using Von Frey monofilaments.

The tibial neuroma transposition (TNT) is a rat model in which allodynia at the neuroma site (tibial nerve) can be independently evaluated from allodynia ...

In vivo Measurement of Knee Extensor Muscle Function in Mice

Skeletal muscle plasticity in response to countless conditions and stimuli mediates concurrent functional adaptation, both negative and positive. In the clinic and the research laboratory, maximal muscular strength is widely measured longitudinally in humans, with knee extensor musculature the most reported functional outcome. Pathology of the knee extensor muscle complex is well documented in aging, orthopedic injury, disease, and disuse; knee extensor strength is closely related to functional capacity and injury risk, underscoring the importance of reliable measurement of knee extensor strength. Repeatable, in vivo assessment of knee extensor strength in pre-clinical rodent studies offers valuable functional endpoints for studies exploring osteoarthritis or knee injury. We report an in vivo and non-invasive protocol to repeatedly measure isometric peak tetanic torque of the knee extensors in mice across time. We demonstrate consistency using this novel method to measure knee extensor strength with repeated assessment in multiple mice producing similar results.

Quantification of knee extensor maximal strength is imperative to understand functional adaptations to aging, disease, injury, and rehabilitation. We present a novel method to repeatedly measure in vivo knee extension isometric peak tetanic torque.

Skeletal muscle plasticity in response to countless conditions and stimuli mediates concurrent functional adaptation, both negative and positive. In the ...