Study Guide: Diagnostic Anesthesia for Lameness Evaluation of the Hindlimb in the Horse

Which two additional nerves are innervated in the pelvic limb compared to the thoracic limb, and which nerve block is this generally associated with?

The two additional nerves innervated in the pelvic limb are the medial and lateral dorsal metatarsal nerves. The nerve block this is generally associated with is the low 6 point block.

How does the communicating branch of the thoracic limb differ from that of the pelvic limb?

The ramus communicans in the pelvic limb is often rudimentary or nonexistent and is located further distally that the ramus in the forelimb.

Which nerves does the lateral plantar nerve give off, and what area is innervated by these branches?

The lateral plantar nerve gives off the deep branch of the lateral planter nerve which then splits into medial and lateral plantar metatarsal nerves. In addition, it gives off tertiary nerves that supply sensation to the proximal aspect of the suspensory ligament.

What is the anesthetic complication associated with anesthetizing the deep branch of the lateral plantar nerve?

An anesthetic complication associated with anesthetizing the deep branch of the lateral plantar nerve could be potential inadvertent injection of nearby structures including: lateral plantar nerve, tarsal metatarsal joint, and tarsal sheath of DDFT

Which two nerves, if anesthetized, desensitize the limb from the tarsus distally?

The two nerves that desensitize the limb from the tarsus distally are the tibial and peroneal nerves.

Which nerves does the tibial nerve give off, and what areas are innervated by these branches?

The tibial nerve is located medially and branches off into the medial and lateral plantar nerves. The lateral plantar nerve then branches off into the deep branch of the lateral plantar nerve that supplies sensation to the proximal aspect of the suspensory.

What are two potential complications of the tibial nerve block?

Potential complications of the tibial nerve block could be failure of block if needle fails to penetrate the deep crural fascia between the subcutis and nerve. On the other hand, the needle could strike the nerve causing the horse to react.

What area does the peroneal nerve innervate?

The peroneal nerve is located on the lateral aspect of the crus. It innervates the distal joints of the tarsus.

What is the anesthesia challenge when differentiating suspensory desmitis from osteoarthritis of the distal tarsal joints?

It is often difficult to distinguish lameness attributable to proximal suspensory desmitis from lameness caused by osteoarthritis of the distal tarsal joints, considering that lameness caused by proximal suspensory desmitis may improve after anesthesia of the TMT joint and

lameness caused by osteoarthritis of the distal tarsal joints may improve after anesthesia of the deep branch of the lateral plantar nerve. Therefore, when there is confusion concerning the site of pain in the hock region, performing the tibial and peroneal nerve blocks separately may clarify the cause of lameness

True or False: Lameness caused by proximal suspensory desmitis may improve after anesthesia of the TMT joint.

True

True or False: Lameness caused by osteoarthritis of the distal tarsal joints may improve after anesthesia of the deep branch of the lateral plantar nerve.

True

What is the potential complication of anesthetizing the peroneal nerve, and which nerve block causes more severe issues?

A potential complication of the anesthetizing the peroneal nerve could be motor denervation causing extensor muscle paralysis causing buckling at the fetlock joint. Blocking the common peroneal nerve often causes more severe buckling of the MTP joint.

Which joints does the tarsocrural joint communicate with?

The tarsocrural joints communicates directly with the proximal intertarsal joint and the talocalcaneal joints.

What is the incidence of direct communication between the distal intertarsal and tarsometatarsal joints?

The incidence of direct communication between the distal intertarsal and tarsometatarsal joints varies between 8.3% to 70%.

What is the incidence of functional communication between the distal intertarsal and tarsometatarsal joints when mepivacaine HCl or methylprednisolone acetate is injected into the TMT joint?

The TMT and DIT joints have been shown in all horses to communicate functionally (i.e., by diffusion) when mepivacaine HCl or methylprednisolone acetate was injected into the TMT joint

What are the two approaches to the distal intertarsal joints, and what is one disadvantage of each technique? REVIEW

The distal intertarsal joint can be approached medially or dorsolaterally.

Why might the gait of some horses with lameness caused by proximal suspensory desmitis or stress remodeling of the plantar cortex of MTIII improve after local anesthetic is injected into the tarsometatarsal joint?

The gait of some horses with lameness caused by proximal suspensory desmitis or stress remodeling of the plantar cortex of MTIII may improve after injecting local anesthetic solution into the TMT joint. This is because local anesthetic may leak from the needle puncture or diffuse from the medial and lateral outpouchings of the joint on the plantar surface of MTIII to cause perineural anesthesia of the plantar metatarsal nerves, which lie in close proximity to these outpouchings.

What are the three joints or compartments of the stifle joint?

The 3 compartments of the stifle joint include: femoropatellar, lateral femorotibial, and medial femorotibial.

How does the femoropatellar joint communicate with the femorotibial joints?

The femoropatellar joint communicates 65% of the time with the medial femorotibial and rarely communicated with the lateral femorotibial.

What are two approaches to the femoropatellar joint?

The femoropatellar joint can be approached through the intrapatellar ligament approach or lateral cul de sac approach.

What are two approaches to the medial femorotibial joint?

The medial femorotibial is accessed: between medial patellar and medical collateral femorotibial ligament or between medial patellar ligament and tendon or sartorious

What is the one approach to the lateral femorotibial joint, and what is the advantage of this technique?

Approach to the lateral femorotibial joint via centesis of LFT bursa of the long digital extensor tendon is advantageous because the diverticulum avoid the contact of the needle with the meniscus, thus avoiding pain or trauma to the meniscus.