chapter 6 and 6a introduction to surgery and anesthesiology

8/2/2019 Chapter 6 and 6a Introduction to Surgery and Anesthesiology

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6 S u r g e r yC o n t e n t s

6.1 Anesthesiology . . . . . . . . . . . . . . . . . . . . . . . 508

by Clifford Gevirtz, MD

6.2 Digital Surgery . . . . . . . . . . . . . . . . . . . . . . . 517

by Keith Springer, DPM

6.3 Hallux Valgus/Lesser Ray Pathology . . . . . . . 535

by Barney Martin, DPM

6.4 Internal and External Fixation . . . . . . . . . . . . 571

by Michael DellaCorte, DPM

Patrick Grisafi, DPM

and David Sands, DPM

6.5 Pediatric Surgery . . . . . . . . . . . . . . . . . . . . . 579

by Renato Giorgini, DPM

and Ellen Sobel, DPM, PhD

6.6 Rearfoot/Cavus/Flatfoot Surgery . . . . . . . . . 589

by Renato Giorgini, DPM

and Ellen Sobel, DPM, PhD

6.7 Soft Tissue Tumors and Surgery . . . . . . . . . . 599

by Nabil Fahim, DPM

and Mark Mandato, DPMΩ

6.8 Complications of Foot Surgery . . . . . . . . . . . 611

by Howard Friedman, DPM

6.9 Traumatology . . . . . . . . . . . . . . . . . . . . . . . . 617

by Aaron Glockenberg, DPM

6.10 Bone Healing and Non-Unions . . . . . . . . . . . . 643

by Susan Belanger, DPM

and Mark Mandato, DPM

Surgery 507



6.1 A n e s t h e s i o l o g yClifford Gevirtz, MD, MPH

Introduction

The progress in surgery over the past 160 years has been made possible by the discovery of anesthesia and the

many refinements in its practice. Where the first century of anesthesia was marked by many hazards, today it is

relatively safe with the risk of death estimated at 1 in 400,000 for minimally invasive procedures. This progress rests

chiefly on a better understanding of the physiology and pharmacology of anesthetic drug as well as much more

sensitive monitoring equipment that can guide the course of an anesthetic.

Definition

General anesthesia has four major components:

• A lack of awarenes

• Hemodynamic stability

• Control of airway and cardiovascular reflexes, and

• A quiet operating field

These four requirements may be met in a very large number of ways, but all four are required for a complete

anesthetic. In the early days of surgery, a fast hand could compensate for any shortcomings in anesthetic technique.

Today’s surgeon has higher expectations and performs vastly more complex procedures on sicker patients. By using

a number of medications and techniques (vide infra) each of the components may be successfully addressed.

Minimum Alvelor Concentration (MAC) is a measure of anesthetic potency. It is defined as the concentration

of an inhalation agent that will prevent movement in 50% of people in response to a defined surgical stimulus (such

as a skin incision). This is equivalent to the ED50 effective dose 50th percentile. This concentration is of limited

clinical use, since a 50% chance of the patient moving upon incision would lead to a lot of embarrassed

anesthesiologists. Rather it is useful since 1.6 MAC of an agent is usually equal to the ED95 or the effective dose in

95% of people. So it is this concentration that is aimed for by combining a fraction of MAC of an agent like

isoflurane with another fraction of a MAC of nitrous oxide. Unfortunately, we often use muscle relaxant to prevent

any possibility of movement rendering this requirement moot. Narcotics are also often added to provide additional

analgesia and to provide for greater hemodynamic stability.

MAC of Various Inhalation Agents

• Halothane 0.8%

• Enflurane 1.6%

• Isoflurane1 1.2%

• Nitrous Oxide 101%

• Sevoflurane 2.05%

• Desflurane 6%L e g e n d – The figures presented are approximate and correspond to expired end-tidal concentrations. Nitrous

Oxide concentration above 100% could only be achieved in a hyperbarbic chamber. MAC changes with age, beinghighest in one year olds and declining slowly with age.

508 The 2005 Podiatry Study Guide



Contra-indications to Elective Anesthesia

• Lack of informed consent

• A myocardial infarction within the past six months

• A CVA within two months

• Pregnancy

• Cocaine use within 48 hours of surgery • Acute Alcohol intoxication (i.e. Alcohol on breath)

• Lack of NPO status

• Uncontrolled Hypertension (diastolic >110)

The above are not absolute and if there is a definite reason for proceeding it needs to be clearly elucidated and

written down.

Material Risks

• Death (1 in 400,000)

• Allergic Reactions to Medication

• Post-Operation Nausea and vomiting

• Pain at the Site of Surgery • Ocular Injury

• Dental Injury

Contraindications to Regional Anesthesia

• Lack of Consent

• Infection at the Site of Injection

• Thrombocytopenia (less than 100,000 platelets/cc)

• Coagulopathy

• Pre-existing Neurologic Disorder

The presence of an infection at the site of injection will lower the pH of the surrounding tissues. Local

anesthetics will not work well because the pka of all local anesthetics is above 7.4. As the pH falls, less unionizedanesthetic will diffuse into the nerves producing less conduction blockade. The pressure of injection may also the

further spread of bacteria or form a tract for deeper passage.

The hazards of thrombocytopenia and coagulopathy are the resultant hemorrhage if an artery or vein is

punctured. In a compartment in the leg or foot, the presence of a large hematoma may compromise the perfusion

within that compartment.

Caution must be exercised in the presence of pre-existing neuralogic disease; because if the disease gets worse,

the anesthesia can be blamed. While there is little evidence of neurotoxity of local anesthetics, many practitioners

may place blame for the progression of the disease on the anesthetic inappropriately.

Surgery | Anesthesiology 509



Intravenous Induction Agents

Thiopentone (Thiopental or Pentathlon®)

Thiopentone (thiopental or pentathlon®) is a rapidly acting barbiturate used for the induction of anesthesia.

Following induction, the anesthetic is continued with another agent such as isoflurane, which will last longer.

Thiopentone can be used as the sole anesthetic agent for very brief procedures such as simple reduction of a

dislocation or removal of a pin, which can be accomplished in a minute or two of operating time.An intravenous injection causes loss of consciousness within 30 seconds and lasts for five to seven minutes.

Among the adverse effects, myocardial depression along with a decrease in tone can cause significant hypotension

especially in patients with hypovolemia.

Contra-indications include porphyria, low circulating blood volume (such as after hemorrhage), and severe

active asthma. The rapid recovery from thiopentone is due to redistribution of the drug from the brain into muscle

and skin.

Ketamine

Ketamine is a unique drug in that it has hypnotic, analgesic, as well as amnesic effects. Because of these

combined effects, it is frequently used alone, especially in countries where other drugs may be too expensive or in

short supply.The anesthetic state produced is frequently called “dissociative anesthesia,” which implies that the patient is

detached from their surroundings. Unlike other forms of anesthetic, the patient’s eyes often remain open and

constantly move from side to side (nystagmus).

Unlike other general anesthetics, it will elevate blood pressure and is not generally a myocardial depressant. It is

especially useful in trauma cases, where there may be hypovolemia as well as in the field, as the patient will continue

to breathe on his or her own. Ketamine produces some bronchodilation making it a useful anesthetic drug for

asthmatic patients.

It is also unusual in the fact that it often produces “emergence delirium” especially in those patients who are not

given a benzodiazepene as either premedication or with co-induction.

This delirium can be quite dramatic and is successfully treated with benzodiazepenes. The delirium as well as

vivid nightmares may last up to 24 hours after awakening.

Propofol

Propofol has emerged as the most popular intravenous induction agent in the U.S. It is in a class of drugs

known as alkylphenols. It is a short-acting, rapidly metabolized intravenous anesthetic. The drug is highly fat-

soluble and dissolves very poorly in water. For this reason it is dissolved into Intralipid®, a fat containing nutritional

supplement used primarily as a caloric supplement in the ICU setting. This is also the reason that careful asepsis

must be carefully maintained during handling as it makes an excellent culture medium for bacteria. Several patients

have died due to sloppy techniques in drawing up this agent into syringes.

Blood concentrations of propofol fall rapidly after bolus administration due to its rapid elimination. It has a

very short distribution half-life of two to four minutes and its total body clearance exceeds liver blood flow, which

means it is rapidly cleared from the body.The popularity of propofol centers on the rapid recovery and lack of lingering side effects. There is also

minimal hypotension/myocardial depression compared to the barbiturates. Propofol may also be administered by

injection, which allows for rapid and accurate control of the depth of anesthetic and/or sedation. There is also less

nausea and vomiting postoperatively.

The major disadvantages of propofol include: it is relatively expensive, may sting when it goes into small veins

and patients may be disinhibited. There have also been reports of vivid sexual dreams while on infusions of

propofol. (Remember, always, always have a chaperon when working with the patients)




Benzodiazepines

Benzodiazepines are drugs that produce five principal pharmacological effects:

• Sedation

• Anxiolysis

• Anticonvulsant actions

• Skeletal muscle relaxation and• Anterograde (encoding of new information) amnesia

Benzodiazepines appear to produce all their pharmacological effects by facilitating the actions of gamma-

aminobutyric acid (GABA), which is the principal inhibitory neurotransmitter in the CNS.

The principal benzodiazepines used in anesthetic are midazolam (versed®) and diazepam (valium®). They are

used as premedication to allay anxiety and as part of co-induction with another induction agent. The result of using

a benzodiazepines along with propofol or thiopentone is a major synergy in action where by the closes of both

agents may be reduced significantly. This results in less hypotension upon induction and a smoother course

throughout the anesthetic.

The amnesia properties are especially highly valued as they may prevent any intraoperative awareness by the

patient.

Flumazenil

This is a benzodiazepine specific antagonist, which will fully reverse the effects of benzodiazepines. It has

minimal effect on the hemodynamics of the patient, but unfortunately will last only 20-30 minutes in usual clinical

dosage. It is a very useful agent if a patient been over sedated by a benzodiazepine. This is especially true in the

elderly who are extremely sensitive to the effects of benzodiazepines. It is contraindicated in patients who are

physically dependent on benzodiazepenes or who use benzodiazenes to control epilepsy.

Opoid Agonists and Antogonists

Opoid Agonist Opoid Agonist – Antogonist Antogonist

Morphine Pentazocine Naloxone

Fentanyl Butorphanol NaltrexoneSufentanyl Nalbuphene Nalmefene

Alfentanyl Dezocine

Remifentanyl

Hydomorphone

Oxymorphone

Methadone

Opoid receptors are classified as mu, delta, kappa and sigma. The molucular structure of these molucles has

been determined and much about how they function has been defined.

Mu receptors are principally responsible for analgesia at the level of spinal cord. A subclass of the MU (M2)

receptor is responsible for respiratory depression, which is seen with larger doses of opioid. Delta receptors respondto endogenously produced opioid-like compounds known as enkephalins and these receptors modulate the activity

of the mu receptor. The kappa and signa reptors are responsible for the dysphoria that is often seen during narcotic

administration.

Since these receptor are widely distributed throughout the body, many side effects can occur, namely, nausea

and vomiting, ileus, respiratory depression, miosis, as well as bradycardia and hypothermia.




By administering opioids and activating these receptors, the perception of pain can be modified or eliminated.

It is the goal of a good physician to be “painless” and the proper administration of these drugs goes a long way in

fulfilling this issue.

However, when added to other anesthetics, the “blend” produces a smooth anesthetic with fewer episodes of

hypertension and tachycardia.

Neuromuscular Blocking Drugs

The major effect of neuromuscular blocking drugs (NMB) is to interrupt the transmission of nerve impulses at

the neuromuscular junction, i.e. by interfering with the effect or acetylcholine in the cleft between the nerve and the

motor end plate.

There are two classes of NMB drugs: depolarizing which, mimics the action of acetycholine and

nondepolarizing which, interfere with the actions of acetylcholine. NMB drugs only effect skeletal muscle and not

the smooth muscle of the gut.

The only member of the depolarizing NMBs is succinylcholine, which assembles two acetylcholine molucules

chemically linked. The molecule cannot be broken down by the enzyme acetylcholine. When the succinylcholine

binds at the receptor site, the underlying muscle contracts and then relaxes, but follow-on stimuli can’t get through

until the succinylcholine diffuses away.

Classes of Neuromuscular Blocking DrugsD e p o l a r i z i n g SuccinylcholineN o n d e p o l a r i z e r PancuroniumL o n g D u r a t i o n ( > 6 0 m i n u t e s ) Pipecuronium

CurareI n t e r m e d i a t e - A c t i n g ( 3 0 - 6 0 m i n u t e s ) Cis-atracurium

Atracurium

Rocuronium

VecuroniumS h o r t - A c t i n g ( l e s s t h a n 3 0 m i n u t e s ) Mivacurium

Succinycholine has a very fast onset of action (within 60 seconds) and indeed its main use today is to secure the

airway during emergencies. Its use is contraindicated in patients with pre-existing paralysis, burns, elevated serum

potassium, or in malignant hyperthermia suspects. The main side effects include a marked elevation in serum

potassium, salivation, and mylgia (from uncoordinated contraction within muscles i.e. the muscle tears at itself)

In contrast, the non-depolarizing agent’s block nerves transmission, but there is no contraction of the effected

muscle.

There are three subclasses of non-depolarizing drugs based on duration of action: long, intermediate or short

acting. Two drugs, atracurium and cis-atracrurium have unique methods of self degradation and are not reliant

upon the liver or kidney to be cleared from the body. These compounds may undergo “Hoffman Elimination” where

the molecule breaks into two non-active metabolities or ester hydrolysis where again the result is two non-activemetabolities. These mechanisms make these drugs an excellent choice in renal and/or liver failure.




Pharmacology of Local Anesthetic Agents

Local anesthetic agents are defined as drugs, which are used clinically to produce reversible loss of sensation in a

circumscibed area of the body.

There are two classes of local anesthetic drugs:

• Esters

• AmidesThe ester agents includes cocaine, tetracaine, procaine and chloroprocaine. The amide agents include lidocaine,

mepivacaine, prilocaine, bupivacaine and ropivacaine. There are important practical differences between these two

groups of local anesthetic agents. Esters are relatively unstable in solution and are rapidly hydrolyzed in the body by

plasma cholinesterase as well as other esterases. One of the major breakdown products is para-aminobenzoate

(PABA) that is associated with allergic phenomena and hypersensitivity reactions. In contrast, the amides are

relatively stable in solution, are slowly metabolized in the liver and hypersensitivity reactions are extremely rare. In

clinical practice, the amides are most commonly used.

Mode of Action

Local anesthetics block the sodium channel, imparing sodium ion flux across the cell wall membrane. This

results in a decrease in the rate and degree of depolarization of the nerve membrane. This prevents the nerve fromreaching the threshold potential for transmission and electrical impulse is not propagated down the nerve.

Vasoconstrictors

Epinephrine is used to prolong the duration of the anesthetic by vasoconstriction, so that the concentration of

the local anesthetic remains high.

• A 1:1000 solution of Epinephrine contains 1 mg/ml

• A 1:200,000 solution contains 5 mcg/ml

Epinephrine containing solutions should not be used for infiltration around end arteries e.g. ring block of the

toes, as the intense vasoconstriction may lead to severe ischemia and necrosis. This is especially true where there is

also compromised perfusion as in advanced atherosclerosis.

Intravenous Regional Anesthetic (Bier Block)The local anesthetic is injected into a vein on the dorsum of the foot after the limb has been exsanguinated

using an Esmach bandage. A tourniquet applied to calf is inflated, 100 mmhg above the systotic blood pressure

preventing new blood from entering the limb and retaining the local anesthetic below the tourniquet. The site of

action is most probably the unmyelinated nerve fibers, reached by retrograde spread in the vascular bed. Lidocaine is

the most commonly used drug. The block is clinically useful for 20 to 30 minutes but the patients may complain of

tourniquet pain. This can be treated with sedation or by inflating a second cuff over the anesthetized area.

If the tourniquet should fail prematurely, a bolus of local anesthetic may reach the central circulation causing

signs of toxicity. With lidocaine, this is usually a very self-limited problem. However, bupivicaine is no longer used

since death from cardiac standstill has been reported. Contra-indications to Bier Block include a previous history of

deep venous thrombosis, phlebitis, or cellulitis of the leg.

Nerve Block for the Lower Extremity

For surgical procedures above the knee one has to block the femoral, lateral femoral cutaneous, obturator,

peroneal, and the sciatic nerve. Procedures below the knee require blocking of the femoral and the sciatic.

The recently introduced so called three-in-one block works very well for the anterior aspect of the knee, and if

the sciatic nerve block is added to it, then one may get a nice lower extremity block that will affect the lower

extremity all the way down to the toes.




There are two main plexuses: one is the lumbar plexus, and the second is the lumbar sacral plexus. The lumbar

plexus comes from the ventral rami of these nerves from the lumbar plexus. The superior portion of the lumbar

plexus and the first lumber nerves together with a portion of the 12th thoracic divide into upper and lower

branches. The upper branch form the iliohypogastric and ilioinguinal nerves. The lower branch with contribution

from the L2 nerve lead to the formation of the genitol femoral nerve. The lumbar plexus forms three main nerves

that leave the pelvis anteriorly to innervate the lower extremity and these are the femoral, obturator, and femoral

cutaneous nerves.

Iliohypogastric Nerve

The iliohypogastric originates from L1 (with a small contribution from T12), sweeps around the body, comes

parallel to the iliac crest, perforates the transversus abdominus and innervates the abdominal wall muscles. Along

the course, which perforates the internal and external oblique muscle at midiliac and gives sensory innervation to

the posterior, lateral gluteal area of the hip. The anterior branch does not enter the inguinal canal but continues and

perforates the internal and external oblique muscles and the apenerosis and innervates the suprapubic area just

below the umbilicus in the lower quadrant of the abdominal wall. In cases of iliohypogastric nerve entrapment there

is a cutaneous hypersensitivity on the painful side in the lower quadrant of the abdominal wall. The technique for

blocking the iliohypogastric nerve is by the use of a 22 gauge one and a half inch short-bevel needle approximately 1

to 2 cm medial and superior to the anterior superior iliac spine having the patient tense the abdominal wall and popthrough the external oblique muscle, pointing the direction of the needle parallel to the iliac crest and deposit 10 ml

of local anesthetic into this tissue plane.

Ilioinguinal Nerve

The ilioinguinal nerve is made up of mainly L1 nerve root with a small contribution from T12. It runs parallel

and inferior to the iliohypogastric nerve. It differs from the iliohypogastric because it perforates the internal oblique

muscle and follows the spermatic cord inside the inguinal canal. It has cutaneous innervation over the upper and

medial thigh as well as the scrotum, the labia majora, and the mons pubis. The technique of injection for surgical

procedure, in addition to the above describe; for the iliohypogastric nerve, one proceeds with injection of 5 to 10 ml

of appropriate anesthetic solution along the superior margin of the pubis as well as equal value beneath the external

oblique apeneurosis. The surgeon may have to infiltrate the spermatic cord if the blocking of the ilioinguinal and

hypogastric nerves do not provide appropriate pain relief.Genital Femoral Nerve

The genital femoral nerve originates from L1 and L2. After leaving the spinal canal, it enters the psoas muscle

and divides into a genital branch and a femoral branch. The genital branch innervates the cremaster muscle and

provides cutaneous innervation of the scrotum-labia and adjoining thigh area. The femoral branch continues

outside the inguinal canal and perforates the femoral sheath at the saphenous opening and provides continuous

innervation to the femoral triangle. The nerve block used most commonly at the time of inguinal surgery. The

technique for blocking this nerve for the genital branch is just lateral to the symphysis pubis where a 22-gauge

needle is passed through the inguinal ligament and 3 to 5 ml of local anesthetic is deposit. For the femoral branch,

the same needle and same volume is used by placing the needle through the inguinal ligament in the mid-inguinal

nerve area, each time making sure that the aspiration is negative prior to injection.

Lateral Femoral Cutaneous Nerve

The lateral femoral cutaneous nerve originates from L2 and L3. It travels along the psoas and divides into

anterior and posterior branches. The anterior gives cutaneous innervation to the anterior-lateral aspect of the thigh

and the posterior branch provides cutaneous innervation to the lateral buttock. Indications include cutaneous block

for skin grafts, donor site and repeat injections in chronic pain management for meralgia parathesica. The block is

carried out by placing a 22-gauge needle anterior and inferior to the anterior superior iliac spine just below the

inguinal ligament and injects in the direction of the iliac crest in a fan-like manner and deposit 10 to 15 ml of local

anesthetic solution.




Obturator Nerve

The obturator passes down behind the psoas muscle and enters the obturator canal, and through that goes into

the thigh where it sends branches to the adductor muscle group, the hip and medial aspect of the knee as well as the

lower medial aspect of the thigh above the knee. To block the nerve, a 10 cm 22-gauge needle is used. Injecting

approximately 2 cm below the public tubercle and contact is made with the superior ramus of the pubis, and then

the needle is passed in a posterior-lateral direction to obtain a paresthesia.

Femoral Nerve Block

The femoral nerve exits the psoas muscle and descends between iliacus muscle and the psoas muscles, passes

beneath the inguinal ligament, and where it leaves the pevis, it divides into several branches. It innervates the

muscles and skin of the anterior thigh, knee, and hip joint and down to the medial ankle. The femoral nerve has a

sheath surrounding it and lends itself for large volume injection and by proximally spreading the medications, the

other branches of the lumbar plexus can also be blocked. The block can be done by palpating the femoral artery and

using a nerve stimulator for evidence of motor contraction followed by 10 to 12 ml of local anesthetic injection

usually gives a good anterior thigh block, however, the groin often is missed because the genital femoral is involved

in the upper thigh area.

Three in One Block

This block usually covers the three nerves, which are lateral femoral cutaneous nerve, obturator, and femoralnerves. Additionally, rarely, the genital femoral, a fourth nerve, is covered, but that is more of an added bonus rather

than a reliable component of the three in one block.

The easiest way to do the block is by the use of a doppler for identifying the femoral artery, marking the

femoral artery, the ilioinguinal ligament is easily palpable, and the point chosen for injection is 1cm inferior to the

ilioinligament, and 1 cm lateral to the femoral artery. The needle is passed beneath the ilioniginual ligament in a

slightly cephalad and lateral direction, and between 35 and 40 ml of local anesthetic is injected.

Saphenous Nerve Block

Saphenous nerve is the terminal branch of the femoral nerve and travels in close relationship with the femoral

vessels. It enters the adductor canal (Hunter’s canal), and this approximately four to six inches above the knee on the

medial side underneath the sartorius muscle is often a site for severe nerve entrapment. The nerve also gives

branches to the medial side as far as the metatarsal phalangeal joint. The nerve communicates with the superficialperoneal nerve, contributes filaments to the subsartorial plexus, to the infrapatellar area and forms the patellar

plexus in connection with the lateral femoral cutaneous nerve. Additionally, it communicates with branches to the

obturator to give cutaneous branches to the medial side of the upper leg. To block the nerve, a number of sites are

possible, but the clinically most relevant and most effective location has been the injection of Hunter’s canal. Here

the patient is asked to tense the sartorius muscle and the needle is passed beneath the sartorius, into Hunter’s canal,

and 10ml of local anesthetic is injected in order to free up the entrapment.

The S c i a t i c N e r v e B l o c k is often carried out by use of a nerve stmulator and 20 to 25ml of local anesthetic is

deposited. The patient is able to lie on the side, and the technique can be quite useful for tibial and ankle fractures,

as the painful side can be uppermost. The technique is drawing a line from the poterior-superior iliac spine at mid

point of the greater trochanter, perpendicularly from this line one goes caudomedially for 5cm. At this point the

needle is inserted until pareshesia is found. Once a brief paresthesia is present, 20 to 25 cc of local anesthetic isinjected.

Popliteal Fossa Block

The popliteal fossa boundaries include the semitendinosus medially, the biceps femoris laterally, and the

semimembranous cephalad. The distal boundarary is by the gastrocnemius muscles medially and laterally. Above the

popliteal fossa the sciatic nerve may already have divided but commonly the nerves will run a predictable course.

The tibial nerve, which is the larger of the two, continues straight down in a straight line underneath the politeal

fascia. Also it will pass between the gastrocnemius muscle. The common peroneal nerve that has a course laterally




following the tendon of the biceps femuris muscle and travel around the head of the fibula, in order to divide in

superficial and deep peroneal nerves. To block the nerves, one has the patient assume a prone position, flex the knee

joint, and approximately 5 cm above the crease aim with needle slightly medially and laterally. A nerve stimulator

will be most helpful in localizing the nerve. At this site, 10ml of local anesthetic can be injected, and expect to have

pain relief for procedure involving the foot. The common peroneal nerve is easily blocked as it wraps around the

neck of the fibula. Here medication is injected in 5 to 7 ml volume, making sure that the injection is not going to be

done into the nerve itself.

Ankle Block

The main nerves innervating the ankle and the foot include the tibial nerve, the sapheneous nerve, the

superficial peroneal nerve, sural nerve, and the deep peroneal nerve. Even though there are multiple nerves

innervating the foot, the success of these blocks are remarkably good when one carries out ring block around the

ankle in addition to the specific blocks for individual nerves. The tibialis nerve innervates the sole of the foot, and

this can be blocked above the medial malleolus. Anterior to the Achilles tendon, the needle is advanced until a

paresthesia is obtained or bony contact is made. The medication is injected in 5 to 7 ml volume in a fan-like manner

as the needle is withdrawn. On the medial aspect of the Achilles tendon, close to the subcutaneous area, in the

direction of the lateral malleolus, one can block the sural nerve. The suprficial peroneal nerve branches are blocked

by subcutaneous infiltration on the anterior side from the medial to the lateral malleolus. The sole of the footinnervated by the tibial nerve, which divides into medial and lateral branches, and the deep peroneal nerve will

innervate the space between the first and second toes. To block the deep perineal nerve, one place a needle medial to

the tendon of the tibialis anterior muscle above the ankle joints. The volume of injected material is approximately 5

ml at each site.


chapter 6 and 6a introduction to surgery and anesthesiology

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