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Management of Tarsal Tunnel Syndrome
Tarsal Tunnel Syndrome CHAPTER 20
VII
Management of Tarsal Tunnel Syndrome A tarsal tunnel release is performed for intractable refractory pain, burning, tingling, and numbness on the plantar and medial aspect of the foot. These symptoms can be associated with aching in the foot or leg, cramping, and vague sensations of soreness, fatigue, and burning, with or without activities. The common recognized causes of tarsal tunnel syndrome include hyperpronation of the foot, a valgus hindfoot, stress or pressure on the tibial nerve from a mass effect, varicosities, and trauma; in many patients, however, no identifiable cause for their symptoms can be found. Before starting an operation for tarsal tunnel release, I routinely perform electrophysiologic testing. Although a normal test result does not contraindicate the performance of surgery, having confirmation of the clinical condition from an electromyogram (EMG) and nerve conduction studies is certainly useful. The problem arises when the patient has vague symptoms suggestive of a tarsal tunnel syndrome but not confirmed on EMG. The results of tarsal tunnel release are not that predictable; probably approximately 80% of well-selected patients improve satisfactorily. Therefore it is imperative to approach this condition with caution, and certainly to avoid operating on the patient with chronic pain or recurrent tarsal tunnel syndrome. In the latter condition, improvement is extremely difficult to obtain. Patients who have been previously operated on through a short incision over the tarsal canal and who continue to have more distal symptoms may constitute an exception: Perhaps the repeat surgery is indicated in this group of patients, for whom an inadequate release was initially performed. The approach to tarsal tunnel release must include an incision that extends distally over the abductor hallucis muscle. The most frequent error in performing a tarsal tunnel release is to ignore the compression that occurs deep to the abductor hallucis muscle. The more proximal portion of the tibial nerve under the laciniate ligament (the flexor reticulum) is rarely the source of compression other than in patients who have lesions, masses, or varicosities in the tarsal tunnel immediately behind the medial malleolus. The incision is deepened through subcutaneous tissue, and in the more proximal area of the tarsal tunnel the flexor retinaculum is
perforated and opened proximally. Rarely, an entrapment is found in the more proximal aspect of the tarsal tunnel behind the malleolus. The flexor retinaculum (the laciniate ligament) is inspected and released slightly more distally to the level of the medial malleolus, and the nerve is inspected (Figures 20-1 and 20-2). A neurolysis is unnecessary for the success of the tibial nerve release and is not recommended. The less the nerve itself is irritated, the lower the risk for epineurial scarring. The key to the operation is in the identification of the bifurcation of the nerve into the medial and lateral plantar nerves. The nerve is traced distally after release of the laciniate ligament, and then the abductor hallucis muscle is gently pulled distally. Using a retractor is the best way to identify the deep fascia directly underneath the abductor muscle. Once the fascia is identified, the lateral plantar nerve is released by completely splitting the deep fascia under direct vision while retracting the abductor muscle distally. After the dorsal, more proximal aspect of the fascia is released, retraction is performed in the reverse direction: The abductor muscle is identified distally at the inferior margin of the muscle and then is pulled proximally. In this way, definitive release of the entire deep fascia is accomplished. Occasionally, the superficial fascia on the abductor muscle is thick, and it also needs to be released, to allow the abductor muscle to be pulled in both directions. Once the deep fascia of the underlying abductor muscle has been released, a decision can be made about whether to extend the incision more distally, if, for example, additional entrapment of the lateral plantar nerve or the first branch of the lateral plantar nerve, in conjunction with the heel pain syndrome, is present. The medial plantar nerve is released in a similar fashion, again under direct vision as it courses deep to the abductor hallucis muscle but slightly more anteriorly. The abductor muscle is pulled plantarward, the fascia is identified, and the split is made immediately below the flexor digitorum longus tendon. Palpation with the tip of the scissors distally is needed to ensure that the retinaculum has been completely released. 233
234 Reconstructive Foot and Ankle Surgery: Management of Complications
A
B
C
D
E
F
G
H
Figure 20-1 Release of the tarsal tunnel. A, The incision for extensile release of the tarsal tunnel. The dotted line represents an alternative extensile approach to the plantar aspect of the foot for a more complete nerve release. B and C, The retinaculum is exposed (B) and is released with a sharp scissors (C). D, A hemostat is then passed under the deep retinaculum into the medial plantar canal tunnel. E, The medial plantar nerve is completely released. F, The abductor fascia is exposed by pulling down on the abductor muscle with a large retractor. G and H, The lateral plantar nerve is released completely.
Any bleeding should be controlled before skin closure. I have found that this incision is prone to inflammation and dehiscence unless the foot is immobilized for a short time. I use nylon sutures in the skin and immobilize the ankle in a splint or short nonarticulated
boot for 2 weeks until the sutures are removed and then allow full weight bearing as tolerated in a boot. Physical therapy and rehabilitation are important to the recovery process after this procedure and should be initiated as soon as tolerated.
Management of Tarsal Tunnel Syndrome 235
20
A
B
C
D
E
F
G
H
I
J Figure 20-2 Tarsal tunnel release in a patient with nerve symptoms only. A, The incision is more vertical than in Figure 20-1. B, Note the bulging appearance of the neurovascular bundle after release of the flexor retinaculum. C, The distal retinaculum is split to expose the branching of the medial and lateral plantar nerves. The abductor hallucis muscle belly is abnormally large, which in this patient may have been the cause of the nerve entrapment. D and E, The muscle is swept off the deep fascia (D) and is released with scissors to free the lateral plantar nerve under the muscle (E). F-H, The muscle is then pulled forward, and the deeper course of the lateral plantar nerve is released under direct vision. I and J, In this patient, the plantar fascia was exposed and release as well.
236 Reconstructive Foot and Ankle Surgery: Management of Complications
SUGGESTED READING Gondring WH, Shields B, Wenger S: An outcomes analysis of surgical treatment of tarsal tunnel syndrome, Foot Ankle Int 24:545–550, 2003. Lau JT, Daniels TR: Effects of tarsal tunnel release and stabilization procedures on tibial nerve tension in a surgically created pes planus foot, Foot Ankle Int 19:770–777, 1998. Lau JT, Daniels TR: Tarsal tunnel syndrome: A review of the literature, Foot Ankle Int 20:201–209, 1999.
Raikin SM, Minnich JM: Failed tarsal tunnel syndrome surgery, Foot Ankle Clin 8:159–174, 2003. Sammarco GJ, Chang L: Outcome of surgical treatment of tarsal tunnel syndrome, Foot Ankle Int 24:125–131, 2003. Skalley TC, Schon LC, Hinton RY, Myerson MS: Clinical results following revision tibial nerve release, Foot Ankle Int 15:360–367, 1994.
VII
Management of Tarsal Tunnel Syndrome A tarsal tunnel release is performed for intractable refractory pain, burning, tingling, and numbness on the plantar and medial aspect of the foot. These symptoms can be associated with aching in the foot or leg, cramping, and vague sensations of soreness, fatigue, and burning, with or without activities. The common recognized causes of tarsal tunnel syndrome include hyperpronation of the foot, a valgus hindfoot, stress or pressure on the tibial nerve from a mass effect, varicosities, and trauma; in many patients, however, no identifiable cause for their symptoms can be found. Before starting an operation for tarsal tunnel release, I routinely perform electrophysiologic testing. Although a normal test result does not contraindicate the performance of surgery, having confirmation of the clinical condition from an electromyogram (EMG) and nerve conduction studies is certainly useful. The problem arises when the patient has vague symptoms suggestive of a tarsal tunnel syndrome but not confirmed on EMG. The results of tarsal tunnel release are not that predictable; probably approximately 80% of well-selected patients improve satisfactorily. Therefore it is imperative to approach this condition with caution, and certainly to avoid operating on the patient with chronic pain or recurrent tarsal tunnel syndrome. In the latter condition, improvement is extremely difficult to obtain. Patients who have been previously operated on through a short incision over the tarsal canal and who continue to have more distal symptoms may constitute an exception: Perhaps the repeat surgery is indicated in this group of patients, for whom an inadequate release was initially performed. The approach to tarsal tunnel release must include an incision that extends distally over the abductor hallucis muscle. The most frequent error in performing a tarsal tunnel release is to ignore the compression that occurs deep to the abductor hallucis muscle. The more proximal portion of the tibial nerve under the laciniate ligament (the flexor reticulum) is rarely the source of compression other than in patients who have lesions, masses, or varicosities in the tarsal tunnel immediately behind the medial malleolus. The incision is deepened through subcutaneous tissue, and in the more proximal area of the tarsal tunnel the flexor retinaculum is
perforated and opened proximally. Rarely, an entrapment is found in the more proximal aspect of the tarsal tunnel behind the malleolus. The flexor retinaculum (the laciniate ligament) is inspected and released slightly more distally to the level of the medial malleolus, and the nerve is inspected (Figures 20-1 and 20-2). A neurolysis is unnecessary for the success of the tibial nerve release and is not recommended. The less the nerve itself is irritated, the lower the risk for epineurial scarring. The key to the operation is in the identification of the bifurcation of the nerve into the medial and lateral plantar nerves. The nerve is traced distally after release of the laciniate ligament, and then the abductor hallucis muscle is gently pulled distally. Using a retractor is the best way to identify the deep fascia directly underneath the abductor muscle. Once the fascia is identified, the lateral plantar nerve is released by completely splitting the deep fascia under direct vision while retracting the abductor muscle distally. After the dorsal, more proximal aspect of the fascia is released, retraction is performed in the reverse direction: The abductor muscle is identified distally at the inferior margin of the muscle and then is pulled proximally. In this way, definitive release of the entire deep fascia is accomplished. Occasionally, the superficial fascia on the abductor muscle is thick, and it also needs to be released, to allow the abductor muscle to be pulled in both directions. Once the deep fascia of the underlying abductor muscle has been released, a decision can be made about whether to extend the incision more distally, if, for example, additional entrapment of the lateral plantar nerve or the first branch of the lateral plantar nerve, in conjunction with the heel pain syndrome, is present. The medial plantar nerve is released in a similar fashion, again under direct vision as it courses deep to the abductor hallucis muscle but slightly more anteriorly. The abductor muscle is pulled plantarward, the fascia is identified, and the split is made immediately below the flexor digitorum longus tendon. Palpation with the tip of the scissors distally is needed to ensure that the retinaculum has been completely released. 233
234 Reconstructive Foot and Ankle Surgery: Management of Complications
A
B
C
D
E
F
G
H
Figure 20-1 Release of the tarsal tunnel. A, The incision for extensile release of the tarsal tunnel. The dotted line represents an alternative extensile approach to the plantar aspect of the foot for a more complete nerve release. B and C, The retinaculum is exposed (B) and is released with a sharp scissors (C). D, A hemostat is then passed under the deep retinaculum into the medial plantar canal tunnel. E, The medial plantar nerve is completely released. F, The abductor fascia is exposed by pulling down on the abductor muscle with a large retractor. G and H, The lateral plantar nerve is released completely.
Any bleeding should be controlled before skin closure. I have found that this incision is prone to inflammation and dehiscence unless the foot is immobilized for a short time. I use nylon sutures in the skin and immobilize the ankle in a splint or short nonarticulated
boot for 2 weeks until the sutures are removed and then allow full weight bearing as tolerated in a boot. Physical therapy and rehabilitation are important to the recovery process after this procedure and should be initiated as soon as tolerated.
Management of Tarsal Tunnel Syndrome 235
20
A
B
C
D
E
F
G
H
I
J Figure 20-2 Tarsal tunnel release in a patient with nerve symptoms only. A, The incision is more vertical than in Figure 20-1. B, Note the bulging appearance of the neurovascular bundle after release of the flexor retinaculum. C, The distal retinaculum is split to expose the branching of the medial and lateral plantar nerves. The abductor hallucis muscle belly is abnormally large, which in this patient may have been the cause of the nerve entrapment. D and E, The muscle is swept off the deep fascia (D) and is released with scissors to free the lateral plantar nerve under the muscle (E). F-H, The muscle is then pulled forward, and the deeper course of the lateral plantar nerve is released under direct vision. I and J, In this patient, the plantar fascia was exposed and release as well.
236 Reconstructive Foot and Ankle Surgery: Management of Complications
SUGGESTED READING Gondring WH, Shields B, Wenger S: An outcomes analysis of surgical treatment of tarsal tunnel syndrome, Foot Ankle Int 24:545–550, 2003. Lau JT, Daniels TR: Effects of tarsal tunnel release and stabilization procedures on tibial nerve tension in a surgically created pes planus foot, Foot Ankle Int 19:770–777, 1998. Lau JT, Daniels TR: Tarsal tunnel syndrome: A review of the literature, Foot Ankle Int 20:201–209, 1999.
Raikin SM, Minnich JM: Failed tarsal tunnel syndrome surgery, Foot Ankle Clin 8:159–174, 2003. Sammarco GJ, Chang L: Outcome of surgical treatment of tarsal tunnel syndrome, Foot Ankle Int 24:125–131, 2003. Skalley TC, Schon LC, Hinton RY, Myerson MS: Clinical results following revision tibial nerve release, Foot Ankle Int 15:360–367, 1994.