- Email: [email protected]
Anatomy of the Portal Tract for Endoscopic Decompression of the First Branch of the Lateral Plantar Nerve
Anatomy of the Portal Tract for Endoscopic Decompression of the First Branch of the Lateral Plantar Nerve Lap Ki Chan, M.B.B.S.(HK), F.H.K.C.O.S., F.H.K.A.M., F.R.C.S.(Edin), Ph.D., Tun Hing Lui, M.B.B.S.(HK), F.H.K.C.O.S., F.H.K.A.M., F.R.C.S.(Edin), and Kwok Bill Chan, M.B.B.S.(HK), F.H.K.C.O.S., F.H.K.A.M., F.R.C.S.(Edin)
Purpose: Our purpose is to study the anatomy of the portal tract for endoscopic decompression of the first branch of the lateral plantar nerve. Methods: The anatomy of the portals and portal tract with endoscopic release of the first branch of the lateral plantar nerve was studied in 12 feet in 6 cadaveric bodies. Results: The proximal portal is located at the fascial opening for the first branch of the lateral plantar nerve and is about 16 mm inferior and 23 mm posterior to the tip of the medial malleolus. The distal portal is located at the inferior edge of the deep fascia of the abductor hallucis muscle and just distal to the medial calcaneal tubercle. The portal tract is deep to the deep surface of the whole width of the deep abductor fascia. In 1 of 12 specimens, the nerve lay superficial to a rod placed between the portals, whereas the nerve was deep to the rod in the remaining 11 specimens. In all specimens the first branch of the lateral plantar nerve, after it pierced the deep fascia of the abductor hallucis at the fascial defect, ran anteriorly and distally, approximately parallel to the direction of the rod. Conclusions: The proximal portal for endoscopic decompression of the first branch of the lateral plantar nerve is located at the fascial opening for the first branch of the lateral plantar nerve. This can be consistently located with the Wissinger rod technique. The portal tract thus created is effective for deep abductor fascia release. However, percutaneous release without endoscopic visualization of the first branch of the lateral plantar nerve is not safe because of the potential risk of nerve injury, because the nerve can be sandwiched between the instrument and the deep abductor fascia without being noticed. Clinical Relevance: The study confirmed the first branch of the lateral plantar nerve can be effectively released endoscopically. Key Words: Heel pain—Plantar—Nerve—Decompression—Endoscopy—Anatomy.
E
ntrapment of the first branch of the lateral plantar nerve is a known but yet commonly overlooked cause of plantar heel pain. Conservative treatment including nonsteroidal anti-inflammatory agents, or-
From the Institute of Medical and Health Sciences Education, Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong (L.K.C.), and Department of Orthopaedics and Traumatology, North District Hospital (T.H.L., K.B.C.), Hong Kong, China. The authors report no conflict of interest. Received March 7, 2008; accepted June 26, 2008. Address correspondence and reprint requests to Tun Hing Lui, M.B.B.S.(HK), F.H.K.C.O.S., F.H.K.A.M., F.R.C.S.(Edin), Ph.D., Department of Orthopaedics and Traumatology, North District Hospital, 9 Po Kin Rd, Sheung Shui, NT, Hong Kong SAR, China. E-mail: [email protected] © 2008 by the Arthroscopy Association of North America 0749-8063/08/2411-8126$34.00/0 doi:10.1016/j.arthro.2008.06.017
1284
thosis, and local steroid injection should be considered first, and if it fails, surgical decompression may be needed. The exact site of entrapment of the first branch of the lateral plantar nerve is where the nerve passes between the deep taut fascia of the abductor hallucis muscle and the medial caudal margin of the medial head of the quadratus plantae muscle.1 Surgical decompression of the nerve requires release of the deep abductor fascia. Classically, this is performed as an open procedure with an extensive medial wound and deep dissection.2 Lui3 described a minimally invasive approach in which the nerve can be decompressed under endoscopic guidance. By this approach, the deep abductor fascia can be released without the need for an extensive wound and dissection of the abductor hallucis muscle. In his method the distal portal is located at the medial border of the plantar
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 24, No 11 (November), 2008: pp 1284-1288
FIRST BRANCH OF LATERAL PLANTAR NERVE
1285
fascia just distal to the medial calcaneal tubercle, which is a clear surface anatomic landmark. The proximal portal is less clearly defined and is established by means of the Wissinger rod method. The purpose of this study was to identify the location of the proximal portal and study the portal tract thus created. We hypothesized that the location of the proximal portal is reproducible and the portal tract created is effective for release of the deep abductor fascia. METHODS Twelve fresh-frozen foot and ankle specimens from 6 Chinese adult male cadavers were used for this study. The mean age was 70.2 years (range, 61 to 87 years). None of the cadavers had pathologies, trauma, or any surgery of the foot and ankle region. The technique of endoscopic decompression of the first branch of the lateral plantar nerve described by Lui3 was used in this study. A distal portal was made at the medial edge of the plantar aponeurosis just distal to the medial calcaneal tubercle. The medial edge of the plantar aponeurosis was cut open, and the deep surface of the deep fascia of the abductor hallucis muscle was felt with a hemostat (i.e., “washboard feeling” when the tip of the hemostat rubbed the transverse fibers of the deep fascia). According to the technique described by Lui, a 2.7-mm, 30° arthroscope with an ordinary cannula was introduced from the plantar portal and was advanced dorsally along the course of the first branch of the lateral plantar nerve until the upper border of the fascia was reached. The dorsal portal was then made at this site. By means of blunt dissection of subcutaneous tissue, the first branch of the lateral plantar nerve was identified, and the upper border of the superficial abductor fascia was released; the abductor hallucis muscle was retracted in a plantar direction to expose the superior border of the deep abductor fascia. The superior border of the deep abductor fascia was then released, and the arthroscope could be advanced through the dorsal portal. Finally, the arthroscope was switched to the plantar portal to visualize the deep surface of the deep abductor fascia. Under direct visualization, a retrograde knife was introduced through the dorsal portal, and the deep abductor fascia was released under arthroscopic visualization (Fig 1). In our study a 4-mm metal rod was introduced from the distal portal, immediately deep to and touching the deep fascia of abductor hallucis. As the rod was advanced proximally, the fascial edge was probed with the rod until a sudden “giving way” was felt while the rod passed through the fascial opening
FIGURE 1. Arthroscopic view of release of deep abductor fascia with muscle exposed.
for the first branch of the lateral plantar nerve. The proximal portal was made at this point, and the distance between the proximal portal and the tip of the medial malleolus was recorded. The rod was advanced through the proximal portal and represented the tract for endoscopic decompression of the first branch of the lateral plantar nerve. The dissection was done in layers with the rod left in situ (Fig 2). The relations of the rod to the deep fascia of the abductor hallucis muscle, the first branch of the lateral plantar nerve, and the lateral plantar neurovascular bundle were recorded. RESULTS In all 12 specimens, no macroscopically identifiable neurovascular damage or damage to the abductor hallucis muscle was found. Location of Proximal Portal In all 12 specimens, a fascia defect at a point posterior and inferior to the medial malleolar tip could be felt proximally by the tip of the metal rod. By dissection of the proximal portal wound, the rod was found passing through the oval fascial defect through which the first branch of the lateral plantar nerve
1286
L. K. CHAN ET AL.
FIGURE 2. (A) A 4-mm metal rod was inserted from the distal portal and passed through the proximal portal. Dissection was done with the rod left in situ. (B) The superficial abductor fascia and the abductor hallucis muscle were cut and retracted to expose the deep abductor fascia (a). The rod was found deep to the deep abductor fascia. (C) After incision of the deep fascia, the first branch of the plantar nerve (b) was exposed. (D) A vessel (c) was found to accompany the first branch of the plantar nerve (b). The lateral plantar nerve (d) was anterior and deep to its first branch.
passes. The rod was in close contact with the nerve at this point. The mean inferior and posterior distances of the proximal portal from the tip of the medial malleolus were 16 mm (range, 13 to 20 mm) and 23 mm (range, 20 to 28 mm), respectively (Table 1). First Branch of Lateral Plantar Nerve and Its Relations
abductor hallucis muscle. The rod was confirmed to make contact with the deep surface of the whole width of the deep fascia. In 1 of 12 specimens, the nerve lay superficial to the rod (Fig 3), whereas the nerve was deep to the rod in the remaining 11 specimens. In all specimens the first branch of the lateral plantar nerve, after it pierced the deep fascia of the abductor hallucis at the fascial
The distal portal was confirmed upon dissection to be located at the inferior edge of the deep fascia of the TABLE 1.
Distance Between Proximal Portal and Tip of Medial Malleolus
Specimen No.
Distance Inferior to Tip of Medial Malleolus (mm)
Distance Posterior to Tip of Medial Malleolus (mm)
1 2 3 4 5 6 7 8 9 10 11 12
14 18 15 20 16 17 17 13 13 20 15 13
22 28 25 21 28 21 26 20 25 20 21 24
FIGURE 3. In this specimen the rod passed through the fascial opening (a) for the first branch of the lateral plantar nerve. The inferior part of the deep abductor fascia was cut open with the superior part (b) left intact. The first branch of the lateral plantar nerve (c) was found to be superficial to the rod.
FIRST BRANCH OF LATERAL PLANTAR NERVE defect, ran anteriorly and distally, approximately parallel to the direction of the rod. Finally, in all specimens, the first branch of the lateral plantar nerve was accompanied by a vessel. Moreover, the lateral plantar nerve lay deeper and more anterior to the first branch of the lateral plantar nerve. DISCUSSION Surgical decompression of the first branch of the lateral plantar nerve requires release of the deep abductor fascia. Classically, an open procedure is required, and the superficial abductor fascia is released and the abductor hallucis muscle mobilized to visualize the deep abductor fascia. An endoscopic approach3 has the advantage of minimizing the soft-tissue dissection and the potential wound complications. The distal portal has a clear surface landmark (medial calcaneal tubercle). However, the proximal portal was established with an inside-out Wissinger technique, and no clear surface landmark was indicated.3 Baxter and Thigpen4 and Henricson and Westlin5 reported that the first branch of the lateral plantar nerve passes through a fascial opening in the deep fascia of the abductor hallucis. In our study the fascial opening could be constantly located by the tip of the metal rod in all specimens, and the proximal portal was then located at this fascial opening. This was about 16 mm inferior and 23 mm posterior to the tip of the medial malleolus. Therefore the proximal portal can be made either by means of the Wissinger technique or by measurement from the tip of the medial malleolus. This proves our hypothesis that the proximal portal is reproducible. At the proximal portals, the instrument or the arthroscope was very close to the first branch of the lateral plantar nerve, so we agree with Lui3 that blunt dissection of the proximal portal wound, to identify and protect the first branch of the lateral plantar nerve and release of the upper border of the deep abductor fascia, is needed before instrumentation is introduced through this portal. In all specimens the portal tracts were deep to the deep abductor fascia and spanned the whole width of the fascia. This implied that the whole fascia can be adequately released through this approach. This proves our hypothesis that the portal tract thus created is effective for release of the deep abductor fascia. However, the first branch of the lateral plantar nerve was sandwiched between the fascia and the metal rod in 1 specimen. This means that the nerve can be transected in case of percutaneous release with the retrograde knife introduced through the portal wounds
1287
without any arthroscopic guide. On the other hand, under arthroscopic guidance, the whole fascia can be visualized and the fascia can be differentiated from the nerve by fiber orientation. Thus we can ensure that no nerve has been entrapped before the fascia release.3 Rondhuis and Huson1 suggested that the site of entrapment of the first branch of the lateral plantar nerve is between the deep fascia of the abductor hallucis and the medial caudal margin of the medial head of the quadratus plantae. However, several other authors suggested that another potential site of entrapment is where the first branch of the lateral plantar nerve passes through the deep fascia of the abductor hallucis.4,5 There are therefore 2 potential sites where the first branch of the lateral plantar nerve can be compressed. A complete decompression of the nerve must include both of these sites. In our study we showed that the endoscopic approach can deal with both sites of potential nerve compression. Interestingly, a vessel was found to accompany the first branch of the lateral plantar nerve in all specimens. It is possible to have an ischemic component rather than pure static compression of the nerve by the fascia. This is consistent with the clinical presentation that early-morning pain is not common with isolated nerve entrapment, which tends to cause more pain at the end of the day or after prolonged activity. Finally, the lateral plantar nerve was found deep to its first branch in all specimens and should not be damaged during endoscopic release. The limitation of the study is that the actual procedure was not performed; therefore we do not know whether any nerves would have been damaged. CONCLUSIONS The proximal portal for endoscopic decompression of the first branch of the lateral plantar nerve is located at the fascial opening for the first branch of the lateral plantar nerve. This can be consistently located with the Wissinger rod technique. The portal tract thus created is effective for deep abductor fascia release. However, percutaneous release without endoscopic visualization of the first branch of the lateral plantar nerve is not safe because of the potential risk of nerve injury, because the nerve can be sandwiched between the instrument and the deep abductor fascia without being noticed. REFERENCES 1. Rondhuis JJ, Huson A. The first branch of the lateral plantar nerve and heel pain. Acta Morphol Neerl Scand 1986;24:269-279.
1288
L. K. CHAN ET AL.
2. Baxter DE, Pfeffer GB. Treatment of chronic heel pain by surgical release of the first branch of the lateral plantar nerve. Clin Orthop Relat Res 1992:229-236. 3. Lui TH. Endoscopic decompression of the first branch of the lateral plantar nerve. Arch Orthop Trauma Surg 2007;127:859-861.
4. Baxter DE, Thigpen MC. Heel pain: Operative results. Foot Ankle 1984;5:16-25. 5. Henricson AS, Westlin NE. Chronic calcaneal pain in athletes: Entrapment of the calcaneal nerve? Am J Sports Med 1984;12:152154.
Articles in Press are now available at the Arthroscopy Web site www.arthroscopyjournal.org Visit the Web site today and sign up to receive e-mail alerts with links to new Articles in Press, Tables of Contents as each issue publishes, as well as Citation Alerts and Search Alerts.
Purpose: Our purpose is to study the anatomy of the portal tract for endoscopic decompression of the first branch of the lateral plantar nerve. Methods: The anatomy of the portals and portal tract with endoscopic release of the first branch of the lateral plantar nerve was studied in 12 feet in 6 cadaveric bodies. Results: The proximal portal is located at the fascial opening for the first branch of the lateral plantar nerve and is about 16 mm inferior and 23 mm posterior to the tip of the medial malleolus. The distal portal is located at the inferior edge of the deep fascia of the abductor hallucis muscle and just distal to the medial calcaneal tubercle. The portal tract is deep to the deep surface of the whole width of the deep abductor fascia. In 1 of 12 specimens, the nerve lay superficial to a rod placed between the portals, whereas the nerve was deep to the rod in the remaining 11 specimens. In all specimens the first branch of the lateral plantar nerve, after it pierced the deep fascia of the abductor hallucis at the fascial defect, ran anteriorly and distally, approximately parallel to the direction of the rod. Conclusions: The proximal portal for endoscopic decompression of the first branch of the lateral plantar nerve is located at the fascial opening for the first branch of the lateral plantar nerve. This can be consistently located with the Wissinger rod technique. The portal tract thus created is effective for deep abductor fascia release. However, percutaneous release without endoscopic visualization of the first branch of the lateral plantar nerve is not safe because of the potential risk of nerve injury, because the nerve can be sandwiched between the instrument and the deep abductor fascia without being noticed. Clinical Relevance: The study confirmed the first branch of the lateral plantar nerve can be effectively released endoscopically. Key Words: Heel pain—Plantar—Nerve—Decompression—Endoscopy—Anatomy.
E
ntrapment of the first branch of the lateral plantar nerve is a known but yet commonly overlooked cause of plantar heel pain. Conservative treatment including nonsteroidal anti-inflammatory agents, or-
From the Institute of Medical and Health Sciences Education, Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong (L.K.C.), and Department of Orthopaedics and Traumatology, North District Hospital (T.H.L., K.B.C.), Hong Kong, China. The authors report no conflict of interest. Received March 7, 2008; accepted June 26, 2008. Address correspondence and reprint requests to Tun Hing Lui, M.B.B.S.(HK), F.H.K.C.O.S., F.H.K.A.M., F.R.C.S.(Edin), Ph.D., Department of Orthopaedics and Traumatology, North District Hospital, 9 Po Kin Rd, Sheung Shui, NT, Hong Kong SAR, China. E-mail: [email protected] © 2008 by the Arthroscopy Association of North America 0749-8063/08/2411-8126$34.00/0 doi:10.1016/j.arthro.2008.06.017
1284
thosis, and local steroid injection should be considered first, and if it fails, surgical decompression may be needed. The exact site of entrapment of the first branch of the lateral plantar nerve is where the nerve passes between the deep taut fascia of the abductor hallucis muscle and the medial caudal margin of the medial head of the quadratus plantae muscle.1 Surgical decompression of the nerve requires release of the deep abductor fascia. Classically, this is performed as an open procedure with an extensive medial wound and deep dissection.2 Lui3 described a minimally invasive approach in which the nerve can be decompressed under endoscopic guidance. By this approach, the deep abductor fascia can be released without the need for an extensive wound and dissection of the abductor hallucis muscle. In his method the distal portal is located at the medial border of the plantar
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 24, No 11 (November), 2008: pp 1284-1288
FIRST BRANCH OF LATERAL PLANTAR NERVE
1285
fascia just distal to the medial calcaneal tubercle, which is a clear surface anatomic landmark. The proximal portal is less clearly defined and is established by means of the Wissinger rod method. The purpose of this study was to identify the location of the proximal portal and study the portal tract thus created. We hypothesized that the location of the proximal portal is reproducible and the portal tract created is effective for release of the deep abductor fascia. METHODS Twelve fresh-frozen foot and ankle specimens from 6 Chinese adult male cadavers were used for this study. The mean age was 70.2 years (range, 61 to 87 years). None of the cadavers had pathologies, trauma, or any surgery of the foot and ankle region. The technique of endoscopic decompression of the first branch of the lateral plantar nerve described by Lui3 was used in this study. A distal portal was made at the medial edge of the plantar aponeurosis just distal to the medial calcaneal tubercle. The medial edge of the plantar aponeurosis was cut open, and the deep surface of the deep fascia of the abductor hallucis muscle was felt with a hemostat (i.e., “washboard feeling” when the tip of the hemostat rubbed the transverse fibers of the deep fascia). According to the technique described by Lui, a 2.7-mm, 30° arthroscope with an ordinary cannula was introduced from the plantar portal and was advanced dorsally along the course of the first branch of the lateral plantar nerve until the upper border of the fascia was reached. The dorsal portal was then made at this site. By means of blunt dissection of subcutaneous tissue, the first branch of the lateral plantar nerve was identified, and the upper border of the superficial abductor fascia was released; the abductor hallucis muscle was retracted in a plantar direction to expose the superior border of the deep abductor fascia. The superior border of the deep abductor fascia was then released, and the arthroscope could be advanced through the dorsal portal. Finally, the arthroscope was switched to the plantar portal to visualize the deep surface of the deep abductor fascia. Under direct visualization, a retrograde knife was introduced through the dorsal portal, and the deep abductor fascia was released under arthroscopic visualization (Fig 1). In our study a 4-mm metal rod was introduced from the distal portal, immediately deep to and touching the deep fascia of abductor hallucis. As the rod was advanced proximally, the fascial edge was probed with the rod until a sudden “giving way” was felt while the rod passed through the fascial opening
FIGURE 1. Arthroscopic view of release of deep abductor fascia with muscle exposed.
for the first branch of the lateral plantar nerve. The proximal portal was made at this point, and the distance between the proximal portal and the tip of the medial malleolus was recorded. The rod was advanced through the proximal portal and represented the tract for endoscopic decompression of the first branch of the lateral plantar nerve. The dissection was done in layers with the rod left in situ (Fig 2). The relations of the rod to the deep fascia of the abductor hallucis muscle, the first branch of the lateral plantar nerve, and the lateral plantar neurovascular bundle were recorded. RESULTS In all 12 specimens, no macroscopically identifiable neurovascular damage or damage to the abductor hallucis muscle was found. Location of Proximal Portal In all 12 specimens, a fascia defect at a point posterior and inferior to the medial malleolar tip could be felt proximally by the tip of the metal rod. By dissection of the proximal portal wound, the rod was found passing through the oval fascial defect through which the first branch of the lateral plantar nerve
1286
L. K. CHAN ET AL.
FIGURE 2. (A) A 4-mm metal rod was inserted from the distal portal and passed through the proximal portal. Dissection was done with the rod left in situ. (B) The superficial abductor fascia and the abductor hallucis muscle were cut and retracted to expose the deep abductor fascia (a). The rod was found deep to the deep abductor fascia. (C) After incision of the deep fascia, the first branch of the plantar nerve (b) was exposed. (D) A vessel (c) was found to accompany the first branch of the plantar nerve (b). The lateral plantar nerve (d) was anterior and deep to its first branch.
passes. The rod was in close contact with the nerve at this point. The mean inferior and posterior distances of the proximal portal from the tip of the medial malleolus were 16 mm (range, 13 to 20 mm) and 23 mm (range, 20 to 28 mm), respectively (Table 1). First Branch of Lateral Plantar Nerve and Its Relations
abductor hallucis muscle. The rod was confirmed to make contact with the deep surface of the whole width of the deep fascia. In 1 of 12 specimens, the nerve lay superficial to the rod (Fig 3), whereas the nerve was deep to the rod in the remaining 11 specimens. In all specimens the first branch of the lateral plantar nerve, after it pierced the deep fascia of the abductor hallucis at the fascial
The distal portal was confirmed upon dissection to be located at the inferior edge of the deep fascia of the TABLE 1.
Distance Between Proximal Portal and Tip of Medial Malleolus
Specimen No.
Distance Inferior to Tip of Medial Malleolus (mm)
Distance Posterior to Tip of Medial Malleolus (mm)
1 2 3 4 5 6 7 8 9 10 11 12
14 18 15 20 16 17 17 13 13 20 15 13
22 28 25 21 28 21 26 20 25 20 21 24
FIGURE 3. In this specimen the rod passed through the fascial opening (a) for the first branch of the lateral plantar nerve. The inferior part of the deep abductor fascia was cut open with the superior part (b) left intact. The first branch of the lateral plantar nerve (c) was found to be superficial to the rod.
FIRST BRANCH OF LATERAL PLANTAR NERVE defect, ran anteriorly and distally, approximately parallel to the direction of the rod. Finally, in all specimens, the first branch of the lateral plantar nerve was accompanied by a vessel. Moreover, the lateral plantar nerve lay deeper and more anterior to the first branch of the lateral plantar nerve. DISCUSSION Surgical decompression of the first branch of the lateral plantar nerve requires release of the deep abductor fascia. Classically, an open procedure is required, and the superficial abductor fascia is released and the abductor hallucis muscle mobilized to visualize the deep abductor fascia. An endoscopic approach3 has the advantage of minimizing the soft-tissue dissection and the potential wound complications. The distal portal has a clear surface landmark (medial calcaneal tubercle). However, the proximal portal was established with an inside-out Wissinger technique, and no clear surface landmark was indicated.3 Baxter and Thigpen4 and Henricson and Westlin5 reported that the first branch of the lateral plantar nerve passes through a fascial opening in the deep fascia of the abductor hallucis. In our study the fascial opening could be constantly located by the tip of the metal rod in all specimens, and the proximal portal was then located at this fascial opening. This was about 16 mm inferior and 23 mm posterior to the tip of the medial malleolus. Therefore the proximal portal can be made either by means of the Wissinger technique or by measurement from the tip of the medial malleolus. This proves our hypothesis that the proximal portal is reproducible. At the proximal portals, the instrument or the arthroscope was very close to the first branch of the lateral plantar nerve, so we agree with Lui3 that blunt dissection of the proximal portal wound, to identify and protect the first branch of the lateral plantar nerve and release of the upper border of the deep abductor fascia, is needed before instrumentation is introduced through this portal. In all specimens the portal tracts were deep to the deep abductor fascia and spanned the whole width of the fascia. This implied that the whole fascia can be adequately released through this approach. This proves our hypothesis that the portal tract thus created is effective for release of the deep abductor fascia. However, the first branch of the lateral plantar nerve was sandwiched between the fascia and the metal rod in 1 specimen. This means that the nerve can be transected in case of percutaneous release with the retrograde knife introduced through the portal wounds
1287
without any arthroscopic guide. On the other hand, under arthroscopic guidance, the whole fascia can be visualized and the fascia can be differentiated from the nerve by fiber orientation. Thus we can ensure that no nerve has been entrapped before the fascia release.3 Rondhuis and Huson1 suggested that the site of entrapment of the first branch of the lateral plantar nerve is between the deep fascia of the abductor hallucis and the medial caudal margin of the medial head of the quadratus plantae. However, several other authors suggested that another potential site of entrapment is where the first branch of the lateral plantar nerve passes through the deep fascia of the abductor hallucis.4,5 There are therefore 2 potential sites where the first branch of the lateral plantar nerve can be compressed. A complete decompression of the nerve must include both of these sites. In our study we showed that the endoscopic approach can deal with both sites of potential nerve compression. Interestingly, a vessel was found to accompany the first branch of the lateral plantar nerve in all specimens. It is possible to have an ischemic component rather than pure static compression of the nerve by the fascia. This is consistent with the clinical presentation that early-morning pain is not common with isolated nerve entrapment, which tends to cause more pain at the end of the day or after prolonged activity. Finally, the lateral plantar nerve was found deep to its first branch in all specimens and should not be damaged during endoscopic release. The limitation of the study is that the actual procedure was not performed; therefore we do not know whether any nerves would have been damaged. CONCLUSIONS The proximal portal for endoscopic decompression of the first branch of the lateral plantar nerve is located at the fascial opening for the first branch of the lateral plantar nerve. This can be consistently located with the Wissinger rod technique. The portal tract thus created is effective for deep abductor fascia release. However, percutaneous release without endoscopic visualization of the first branch of the lateral plantar nerve is not safe because of the potential risk of nerve injury, because the nerve can be sandwiched between the instrument and the deep abductor fascia without being noticed. REFERENCES 1. Rondhuis JJ, Huson A. The first branch of the lateral plantar nerve and heel pain. Acta Morphol Neerl Scand 1986;24:269-279.
1288
L. K. CHAN ET AL.
2. Baxter DE, Pfeffer GB. Treatment of chronic heel pain by surgical release of the first branch of the lateral plantar nerve. Clin Orthop Relat Res 1992:229-236. 3. Lui TH. Endoscopic decompression of the first branch of the lateral plantar nerve. Arch Orthop Trauma Surg 2007;127:859-861.
4. Baxter DE, Thigpen MC. Heel pain: Operative results. Foot Ankle 1984;5:16-25. 5. Henricson AS, Westlin NE. Chronic calcaneal pain in athletes: Entrapment of the calcaneal nerve? Am J Sports Med 1984;12:152154.
Articles in Press are now available at the Arthroscopy Web site www.arthroscopyjournal.org Visit the Web site today and sign up to receive e-mail alerts with links to new Articles in Press, Tables of Contents as each issue publishes, as well as Citation Alerts and Search Alerts.