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A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy
G Model
FAS-751; No. of Pages 5 Foot and Ankle Surgery xxx (2014) e1–e5
Contents lists available at ScienceDirect
Foot and Ankle Surgery journal homepage: www.elsevier.com/locate/fas
Case report
A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy Raymond J. Walls MD, FRCS (Tr&Orth)*, Jeremy Y. Chan BS, Scott J. Ellis MD Department of Foot and Ankle Surgery, Hospital for Special Surgery, New York, NY, USA
A R T I C L E I N F O
A B S T R A C T
Article history: Received 4 April 2014 Received in revised form 13 July 2014 Accepted 14 July 2014
Surgical correction of hindfoot varus is frequently performed with a lateral displacement calcaneal osteotomy. It has rarely been associated with iatrogenic tarsal tunnel syndrome in patients with preexisting neurological disease. We report the first case of acute postoperative tarsal tunnel syndrome in a neurologically intact patient with post-traumatic hindfoot varus. Early diagnosis and emergent operative release afforded an excellent clinical outcome. Imaging studies can help outrule a compressive hematoma and assess for possible nerve transection; however it is paramount that a high index of suspicion is utilized with judicious operative intervention to minimize long-term sequelae. ß 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Tarsal tunnel syndrome Calcaneal osteotomy Hindfoot varus
1. Introduction Hindfoot varus is frequently associated with neurological conditions such as Charcot–Marie–Tooth (CMT) disease where the resulting muscle imbalance precipitates a forefoot driven hindfoot deformity [1–3]. Conversely, lower limb trauma can produce deformities that, if not recognized, can accelerate ankle and hindfoot joint degeneration [4,5]. Operative correction of such malunions aims to relieve symptoms and preserve articular cartilage [6]. Progression of established anteromedial ankle arthritis in cavovarus feet can be limited with judicious use of appropriate realignment procedures [7]. In particular, lateral displacement calcaneal osteotomies are often performed to correct symptomatic hindfoot varus [7–9]. Biomechanical studies have also confirmed the benefit such procedures have in the normalization of ankle contact stresses [10,11]. While the amount of correction required is relative to the severity of a deformity, we have anecdotally found that sliding the osteotomy laterally is more difficult when compared to medial calcaneal osteotomies used to correct hindfoot valgus. Indirectly, compression is placed on the medial neurovascular structures and risks, albeit rare, an iatrogenic tibial nerve injury. While such a complication has been reported previously in CMT disease [12], we
* Corresponding author at: Foot and Ankle Service, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA. Tel.: +1 917 780 8720. E-mail address: [email protected] (R.J. Walls).
report the first case of tarsal tunnel syndrome following a lateral calcaneal osteotomy to correct post-traumatic lower limb deformity in a patient without CMT. 2. Case report A 61-year old female presented with a 3-year history of progressive right hindfoot and ankle pain and swelling. Walking duration was limited to 15 min and oral analgesics were required daily. She sustained fractures of her right ankle and distal tibial diaphysis 40 years previously which were managed nonoperatively. Preoperative clinical assessment confirmed a flexible hindfoot varus with subtle forefoot supination. The ankle had a total motion arc of 358. The transverse tarsal joints were tender, especially dorsally over the talonavicular joint, and demonstrated marked irritability when stressed. The forefoot was clinically normal. A detailed neurovascular evaluation did not identify any additional abnormality. Standard weightbearing radiographs confirmed advanced arthritis of the talonavicular and calcaneocuboid joints (Fig. 1). Hindfoot varus was confirmed as a combination of medial tibiotalar degeneration and distal tibial angulation (Fig. 2). Arthrodesis of the talonavicular and calcaneocuboid joints were performed first and augmented with proximal tibial autograft and autogenous iliac bone marrow aspirate. A standard lateral approach was used for the lateral calcaneal osteotomy. A sagittal saw initiated the osteotomy which was carefully completed through the medial cortex using osteotomes. Seven millimeters of translation was used to correct the hindfoot to a clinically neutral
http://dx.doi.org/10.1016/j.fas.2014.07.006 1268-7731/ß 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
e2
Fig. 1. Preoperative AP (A) and lateral (B) weightbearing radiographs of the foot demonstrate advanced arthritis of the talonavicular and calcaneocuboid joints.
position and two 4.5 mm cannulated screws provided stable fixation. The total tourniquet time was 150 min at 250 mm Hg. On the first postoperative day, the patient reported a mild burning sensation in her heel that radiated to the plantar forefoot. Pregabalin was prescribed at a dose of 50 mg three times daily for three days as was the standard protocol for all patients undergoing foot and ankle surgery. Sufficient improvement was reported by the patient on the third postoperative day to allow discharge. However, due to complaints of persistent burning pain and the onset of plantar forefoot paraesthesia, the patient returned to the office for follow-up five days after surgery. The presence of hypoaesthesia over the heel extending through the plantar forefoot and increased burning pain radiating into the foot raised concern for an acute tarsal tunnel syndrome. Urgent MRI evaluation ruled out a compressive hematoma and demonstrated continuity of the tibial nerve and its lateral calcaneal branch in the region of the osteotomy (Fig. 3). An independent assessment by a neurologist concurred with the presumptive clinical diagnosis of tarsal tunnel syndrome based predominantly on sensory examination, but found it difficult to assess motor function in the immediate postoperative period. Open exploration and release of the tarsal tunnel was performed emergently on the eighth postoperative day. The inferior flexor retinaculum was fully released permitting complete decompression of the neurovascular bundle and all branches of the tibial nerve. All structures were considered intact although the lateral calcaneal branch was more hyperaemic in the region of the osteotomy (Fig. 4). Postoperatively, there was complete resolution of the plantar burning sensation reported immediately on waking from the anesthesia. At 3 months postoperatively, there was resolution of heel symptoms. By 6 months, only a small area of hypoaesthesia remained at the lateral aspect of the forefoot and the calcaneal osteotomy had healed with an improvement in axial alignment (Fig. 5). 3. Discussion Neurovascular injuries following calcaneal osteotomies are recognized as potential complications; however, the actual rate
of occurrence is unknown [13–15]. To our knowledge, there is currently only one published case of tibial nerve palsy following a lateral calcaneal osteotomy in the setting of Charcot–Marie– Tooth disease [12]. We are reporting the first described case of tarsal tunnel syndrome following a lateral calcaneal osteotomy which was instead performed to correct post-traumatic hindfoot varus. The osteotomy is typically performed via a lateral approach with the surgeon blind to the exact location of the key medial atrisk structures. Green et al. [15] examined the local anatomy in the setting of a medializing calcaneal osteotomy. Their cadaveric study identified between two and six neurovascular structures crossing the osteotomy site of which the majority were branches of the lateral plantar nerve and the posterior tibial artery. The most common structures were the calcaneal branch of the lateral plantar nerve (86%) and Baxter’s nerve (95%), whereas the medial plantar nerve did not cross in any specimen. When evaluating our patient in the postoperative period, we considered three possible etiologies: iatrogenic nerve transection, tarsal tunnel syndrome secondary to either a compressive hematoma or a decrease in dimensions of the canal as a result of the lateral translation, and finally acute spinal radiculopathy. As standard practice, we carefully complete all osteotomies in a controlled fashion with an osteotome to minimize the possibility of direct neurovascular transection. Although possible, we felt transection was unlikely and this suspicion was confirmed by postoperative MRI and again at the time of operative decompression. In our patient all symptoms were localized to the foot, were predominantly sensory, and were considered attributable to local pathology. The MRI did not demonstrate any hematoma; therefore, we believed the dimensions of the tarsal tunnel may have been affected by the translation. Krause et al. [12] analyzed the dimensions of the tarsal canal following a 10 mm lateral calcaneal translation, noting compression of the tibial nerve between the flexor retinaculum and the posteromedial process of the talus. Bruce et al. have also recently demonstrated that lateral and not medial calcaneal osteotomies significantly reduce tarsal tunnel volume in a cadaveric model [16]. As a result, they suggest
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
e3
Fig. 3. Axial proton density MRI image at the level of the calcaneal osteotomy demonstrating the position of the main nerve branches and flexor tendons: TP, tibialis posterior; FHL, flexor hallucis longus; FDL, flexor digitorum longus; MPN, medial plantar nerve; LPN, lateral plantar nerve.
Fig. 2. The hindfoot varus deformity is demonstrated as a combined effect of medial tibiotalar degeneration and distal tibial malunion on this AP, weightbearing radiograph of the ankle.
prophylactic release of the tarsal tunnel when a large lateral translation is performed. In the case report from Krause et al. [12] a mother and son suffering from CMT type two underwent corrective procedures for bilateral pes cavovarus. Postoperatively, both patients developed a tibial neuropraxia on their left side with sensory disturbances in the distribution of the medial and lateral plantar nerves. EMG and nerve conduction studies were performed in both cases, but as there were preexisting sensorimotor conduction abnormalities from their CMT, the authors reported difficulty in confirming new
changes. Both patients were offered a tarsal tunnel release, but only the mother consented for the procedure, achieving full recovery by 12 weeks. The son declined further surgery and had persistent symptoms at 18 months. The authors suggested that patients with underlying sensorimotor neuropathy may have an increased risk of neuropraxia following a lateralizing calcaneal osteotomy and advocate routine release of the inferior flexor retinaculum in this cohort [12]. We performed a limited 7 mm lateral calcaneal translation in a patient with post-traumatic hindfoot varus. There was no prior history of a neurological disorder. In addition, our patient’s prior injuries were low energy, managed conservatively, and not associated with any neurological symptoms. While we appreciate that small lateral shifts may also reduce the tarsal tunnel volume [16], we propose that post-traumatic scarring of the soft tissues surrounding the tibial nerve caused tethering which precipitated the development of tarsal tunnel syndrome. An alternative option in our case could have been to use the Malerba Z-shaped triplaner calcaneal osteotomy which is considered a very powerful tool for the correction of hindfoot varus [13,14]. Rotation of the tuberosity can allow a smaller translation to be performed. We believe that this can reduce compression of
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 e4
R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
Fig. 4. Clinical photograph taken intraoperatively at the time of the tarsal tunnel release: TN, tibial nerve; MPN, medial plantar nerve; LPN, lateral plantar nerve; CB, calcaneal branch of the lateral plantar nerve; PTA, posterior tibial artery.
the tibial nerve in the tarsal tunnel and obviate the need for a secondary medial incision to release the flexor retinaculum in routine cases. As our experience with this osteotomy has grown, it has become our preferred technique to correct hindfoot varus. Caution must still be exercised when performing this osteotomy as the medial neurovascular structures are still at risk of transection [14]. On review of our case, an argument could be made for performing a supramalleolar osteotomy (SMO) rather than calcaneal lateralization to correct lower limb varus. It has been demonstrated that lateralizing calcaneal osteotomies and supramalleolar osteotomies are equivalent in redistributing forces in cavovarus deformities [17]. While we had considered both options preoperatively, we elected to perform a calcaneal osteotomy as we felt it would permit a more rapid recovery and is more commonly performed in our practice. An alternative technique to correct the ankle/hindfoot varus in the setting of transverse tarsal arthritis is to rotate the hindfoot relative to the midfoot through the talonavicular joint with subsequent fusion of the talonavicular and calcaneocuboid joints. This has the potential advantage of obviating the need for a lateralizing calcaneal osteotomy, and in turn the risk for a tibial nerve complication. However this approach may require a subsequent dorsiflexion osteotomy of the first metatarsal to realign the medial column and was not our operation of choice. Finally, had the subtalar joint been arthritic, a triple arthrodesis could have been considered, simultaneously permitting coronal alignment correction. However this was not the case for our patient and its preservation has allowed us to maintain some hindfoot motion.
Fig. 5. Postoperative weightbearing AP (A), lateral (B) and axial hindfoot (C) radiographs taken 6 months postoperatively demonstrating arthrodesis of the calcaneocuboid and talonavicular articulations and improved coronal hindfoot alignment.
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
4. Conclusion Tarsal tunnel syndrome is a rare complication following lateral translational calcaneal osteotomies. It has only been reported previously in patients with pre-existing sensorimotor disease. Our report describes this complication in a neurologically intact patient with post-traumatic hindfoot varus. Increased awareness of this condition is needed to encourage prompt diagnosis, and to allow emergent operative release of the tarsal tunnel to maximize patient outcomes. We now advocate the triplanar calcaneal osteotomy (Malerba) as an alternative method to correct hindfoot varus, which may lower the risk of neurovascular compromise. Alternatively, prophylactic tarsal tunnel release may be considered at the time a lateralizing calcaneal osteotomy is performed. Conflict of interest No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. The authors received no financial support for the research, authorship, and/or publication of this article. Acknowledgement No sponsors or external enterprises provided funding for this study. References [1] Leeuwesteijn AE, de Visser E, Louwerens JW. Flexible cavovarus feet in Charcot–Marie–Tooth disease treated with first ray proximal dorsiflexion osteotomy combined with soft tissue surgery: a short-term to mid-term outcome study. Foot Ankle Surg 2010;16:142–7.
e5
[2] Beals TC, Nickisch F. Charcot–Marie–Tooth disease and the cavovarus foot. Foot Ankle Clin 2008;13:259–74. [3] Ward CM, Dolan LA, Bennett DL, Morcuende JA, Cooper RR. Long-term results of reconstruction for treatment of a flexible cavovarus foot in Charcot–Marie– Tooth disease. J Bone Joint Surg Am 2008;90:2631–42. [4] Lesiak AC, Vosseller JT, Rozbruch SR. Osteotomy, arthrodesis, and arthroplasty for complex multiapical deformity of the leg. HSS J 2012;8:304–8. [5] Stuermer EK, Stuermer KM. Tibial shaft fracture and ankle joint injury. J Orthop Trauma 2008;22:107–12. [6] Probe RA. Lower extremity angular malunion: evaluation and surgical correction. J Am Acad Orthop Surg 2003;11:302–11. [7] Krause FG, Henning J, Pfander G, Weber M. Cavovarus foot realignment to treat anteromedial ankle arthrosis. Foot Ankle Int 2013;34:54–64. [8] Vienne P, Scho¨niger R, Helmy N, Espinosa N. Hindfoot instability in cavovarus deformity: static and dynamic balancing. Foot Ankle Int 2007;28:96–102. [9] Maskill MP, Maskill JD, Pomeroy GC. Surgical management and treatment algorithm for the subtle cavovarus foot. Foot Ankle Int 2010;31: 1057–63. [10] Krause FG, Sutter D, Waehnert D, Windolf M, Schwieger K, Weber M. Ankle joint pressure changes in a pes cavovarus model after lateralizing calcaneal osteotomies. Foot Ankle Int 2010;31:741–6. [11] Steffensmeier SJ, Saltzman CL, Berbaum KS, Brown TD. Effects of medial and lateral displacement calcaneal osteotomies on tibiotalar joint contact stresses. J Orthop Res 1996;14:980–5. [12] Krause FG, Pohl MJ, Penner MJ, Younger AS. Tibial nerve palsy associated with lateralizing calcaneal osteotomy: case reviews and technical tip. Foot Ankle Int 2009;30:258–61. [13] Malerba F, De Marchi F. Calcaneal osteotomies. Foot Ankle Clin 2005;10: 523–40. [14] Vermeulen K, Neven E, Vandeputte G, Van Glabbeek F, Somville J. Relationship of the Scarf valgus-inducing osteotomy of the calcaneus to the medial neurovascular structures. Foot Ankle Int 2011;32:S540–4. [15] Greene DL, Thompson MC, Gesink DS, Graves SC. Anatomic study of the medial neurovascular structures in relation to calcaneal osteotomy. Foot Ankle Int 2001;22:569–71. [16] Bruce BG, Bariteau JT, Evangelista PE, Arcuir D, Sandusky M, DiGiovanni CW. The effect of medial and lateral calcaneal osteotomies on the tarsal tunnel. Foot Ankle Int 2014;35:383–8. [17] Schmid T, Zurbriggen S, Zderic I, Gueorguiev B, Weber M, Krause FG. Ankle joint pressure changes in a pes cavovarus model: supramalleolar valgus osteotomy versus lateralizing calcaneal osteotomy. Foot Ankle Int 2013;34: 1190–7.
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
FAS-751; No. of Pages 5 Foot and Ankle Surgery xxx (2014) e1–e5
Contents lists available at ScienceDirect
Foot and Ankle Surgery journal homepage: www.elsevier.com/locate/fas
Case report
A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy Raymond J. Walls MD, FRCS (Tr&Orth)*, Jeremy Y. Chan BS, Scott J. Ellis MD Department of Foot and Ankle Surgery, Hospital for Special Surgery, New York, NY, USA
A R T I C L E I N F O
A B S T R A C T
Article history: Received 4 April 2014 Received in revised form 13 July 2014 Accepted 14 July 2014
Surgical correction of hindfoot varus is frequently performed with a lateral displacement calcaneal osteotomy. It has rarely been associated with iatrogenic tarsal tunnel syndrome in patients with preexisting neurological disease. We report the first case of acute postoperative tarsal tunnel syndrome in a neurologically intact patient with post-traumatic hindfoot varus. Early diagnosis and emergent operative release afforded an excellent clinical outcome. Imaging studies can help outrule a compressive hematoma and assess for possible nerve transection; however it is paramount that a high index of suspicion is utilized with judicious operative intervention to minimize long-term sequelae. ß 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Tarsal tunnel syndrome Calcaneal osteotomy Hindfoot varus
1. Introduction Hindfoot varus is frequently associated with neurological conditions such as Charcot–Marie–Tooth (CMT) disease where the resulting muscle imbalance precipitates a forefoot driven hindfoot deformity [1–3]. Conversely, lower limb trauma can produce deformities that, if not recognized, can accelerate ankle and hindfoot joint degeneration [4,5]. Operative correction of such malunions aims to relieve symptoms and preserve articular cartilage [6]. Progression of established anteromedial ankle arthritis in cavovarus feet can be limited with judicious use of appropriate realignment procedures [7]. In particular, lateral displacement calcaneal osteotomies are often performed to correct symptomatic hindfoot varus [7–9]. Biomechanical studies have also confirmed the benefit such procedures have in the normalization of ankle contact stresses [10,11]. While the amount of correction required is relative to the severity of a deformity, we have anecdotally found that sliding the osteotomy laterally is more difficult when compared to medial calcaneal osteotomies used to correct hindfoot valgus. Indirectly, compression is placed on the medial neurovascular structures and risks, albeit rare, an iatrogenic tibial nerve injury. While such a complication has been reported previously in CMT disease [12], we
* Corresponding author at: Foot and Ankle Service, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA. Tel.: +1 917 780 8720. E-mail address: [email protected] (R.J. Walls).
report the first case of tarsal tunnel syndrome following a lateral calcaneal osteotomy to correct post-traumatic lower limb deformity in a patient without CMT. 2. Case report A 61-year old female presented with a 3-year history of progressive right hindfoot and ankle pain and swelling. Walking duration was limited to 15 min and oral analgesics were required daily. She sustained fractures of her right ankle and distal tibial diaphysis 40 years previously which were managed nonoperatively. Preoperative clinical assessment confirmed a flexible hindfoot varus with subtle forefoot supination. The ankle had a total motion arc of 358. The transverse tarsal joints were tender, especially dorsally over the talonavicular joint, and demonstrated marked irritability when stressed. The forefoot was clinically normal. A detailed neurovascular evaluation did not identify any additional abnormality. Standard weightbearing radiographs confirmed advanced arthritis of the talonavicular and calcaneocuboid joints (Fig. 1). Hindfoot varus was confirmed as a combination of medial tibiotalar degeneration and distal tibial angulation (Fig. 2). Arthrodesis of the talonavicular and calcaneocuboid joints were performed first and augmented with proximal tibial autograft and autogenous iliac bone marrow aspirate. A standard lateral approach was used for the lateral calcaneal osteotomy. A sagittal saw initiated the osteotomy which was carefully completed through the medial cortex using osteotomes. Seven millimeters of translation was used to correct the hindfoot to a clinically neutral
http://dx.doi.org/10.1016/j.fas.2014.07.006 1268-7731/ß 2014 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
e2
Fig. 1. Preoperative AP (A) and lateral (B) weightbearing radiographs of the foot demonstrate advanced arthritis of the talonavicular and calcaneocuboid joints.
position and two 4.5 mm cannulated screws provided stable fixation. The total tourniquet time was 150 min at 250 mm Hg. On the first postoperative day, the patient reported a mild burning sensation in her heel that radiated to the plantar forefoot. Pregabalin was prescribed at a dose of 50 mg three times daily for three days as was the standard protocol for all patients undergoing foot and ankle surgery. Sufficient improvement was reported by the patient on the third postoperative day to allow discharge. However, due to complaints of persistent burning pain and the onset of plantar forefoot paraesthesia, the patient returned to the office for follow-up five days after surgery. The presence of hypoaesthesia over the heel extending through the plantar forefoot and increased burning pain radiating into the foot raised concern for an acute tarsal tunnel syndrome. Urgent MRI evaluation ruled out a compressive hematoma and demonstrated continuity of the tibial nerve and its lateral calcaneal branch in the region of the osteotomy (Fig. 3). An independent assessment by a neurologist concurred with the presumptive clinical diagnosis of tarsal tunnel syndrome based predominantly on sensory examination, but found it difficult to assess motor function in the immediate postoperative period. Open exploration and release of the tarsal tunnel was performed emergently on the eighth postoperative day. The inferior flexor retinaculum was fully released permitting complete decompression of the neurovascular bundle and all branches of the tibial nerve. All structures were considered intact although the lateral calcaneal branch was more hyperaemic in the region of the osteotomy (Fig. 4). Postoperatively, there was complete resolution of the plantar burning sensation reported immediately on waking from the anesthesia. At 3 months postoperatively, there was resolution of heel symptoms. By 6 months, only a small area of hypoaesthesia remained at the lateral aspect of the forefoot and the calcaneal osteotomy had healed with an improvement in axial alignment (Fig. 5). 3. Discussion Neurovascular injuries following calcaneal osteotomies are recognized as potential complications; however, the actual rate
of occurrence is unknown [13–15]. To our knowledge, there is currently only one published case of tibial nerve palsy following a lateral calcaneal osteotomy in the setting of Charcot–Marie– Tooth disease [12]. We are reporting the first described case of tarsal tunnel syndrome following a lateral calcaneal osteotomy which was instead performed to correct post-traumatic hindfoot varus. The osteotomy is typically performed via a lateral approach with the surgeon blind to the exact location of the key medial atrisk structures. Green et al. [15] examined the local anatomy in the setting of a medializing calcaneal osteotomy. Their cadaveric study identified between two and six neurovascular structures crossing the osteotomy site of which the majority were branches of the lateral plantar nerve and the posterior tibial artery. The most common structures were the calcaneal branch of the lateral plantar nerve (86%) and Baxter’s nerve (95%), whereas the medial plantar nerve did not cross in any specimen. When evaluating our patient in the postoperative period, we considered three possible etiologies: iatrogenic nerve transection, tarsal tunnel syndrome secondary to either a compressive hematoma or a decrease in dimensions of the canal as a result of the lateral translation, and finally acute spinal radiculopathy. As standard practice, we carefully complete all osteotomies in a controlled fashion with an osteotome to minimize the possibility of direct neurovascular transection. Although possible, we felt transection was unlikely and this suspicion was confirmed by postoperative MRI and again at the time of operative decompression. In our patient all symptoms were localized to the foot, were predominantly sensory, and were considered attributable to local pathology. The MRI did not demonstrate any hematoma; therefore, we believed the dimensions of the tarsal tunnel may have been affected by the translation. Krause et al. [12] analyzed the dimensions of the tarsal canal following a 10 mm lateral calcaneal translation, noting compression of the tibial nerve between the flexor retinaculum and the posteromedial process of the talus. Bruce et al. have also recently demonstrated that lateral and not medial calcaneal osteotomies significantly reduce tarsal tunnel volume in a cadaveric model [16]. As a result, they suggest
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
e3
Fig. 3. Axial proton density MRI image at the level of the calcaneal osteotomy demonstrating the position of the main nerve branches and flexor tendons: TP, tibialis posterior; FHL, flexor hallucis longus; FDL, flexor digitorum longus; MPN, medial plantar nerve; LPN, lateral plantar nerve.
Fig. 2. The hindfoot varus deformity is demonstrated as a combined effect of medial tibiotalar degeneration and distal tibial malunion on this AP, weightbearing radiograph of the ankle.
prophylactic release of the tarsal tunnel when a large lateral translation is performed. In the case report from Krause et al. [12] a mother and son suffering from CMT type two underwent corrective procedures for bilateral pes cavovarus. Postoperatively, both patients developed a tibial neuropraxia on their left side with sensory disturbances in the distribution of the medial and lateral plantar nerves. EMG and nerve conduction studies were performed in both cases, but as there were preexisting sensorimotor conduction abnormalities from their CMT, the authors reported difficulty in confirming new
changes. Both patients were offered a tarsal tunnel release, but only the mother consented for the procedure, achieving full recovery by 12 weeks. The son declined further surgery and had persistent symptoms at 18 months. The authors suggested that patients with underlying sensorimotor neuropathy may have an increased risk of neuropraxia following a lateralizing calcaneal osteotomy and advocate routine release of the inferior flexor retinaculum in this cohort [12]. We performed a limited 7 mm lateral calcaneal translation in a patient with post-traumatic hindfoot varus. There was no prior history of a neurological disorder. In addition, our patient’s prior injuries were low energy, managed conservatively, and not associated with any neurological symptoms. While we appreciate that small lateral shifts may also reduce the tarsal tunnel volume [16], we propose that post-traumatic scarring of the soft tissues surrounding the tibial nerve caused tethering which precipitated the development of tarsal tunnel syndrome. An alternative option in our case could have been to use the Malerba Z-shaped triplaner calcaneal osteotomy which is considered a very powerful tool for the correction of hindfoot varus [13,14]. Rotation of the tuberosity can allow a smaller translation to be performed. We believe that this can reduce compression of
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 e4
R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
Fig. 4. Clinical photograph taken intraoperatively at the time of the tarsal tunnel release: TN, tibial nerve; MPN, medial plantar nerve; LPN, lateral plantar nerve; CB, calcaneal branch of the lateral plantar nerve; PTA, posterior tibial artery.
the tibial nerve in the tarsal tunnel and obviate the need for a secondary medial incision to release the flexor retinaculum in routine cases. As our experience with this osteotomy has grown, it has become our preferred technique to correct hindfoot varus. Caution must still be exercised when performing this osteotomy as the medial neurovascular structures are still at risk of transection [14]. On review of our case, an argument could be made for performing a supramalleolar osteotomy (SMO) rather than calcaneal lateralization to correct lower limb varus. It has been demonstrated that lateralizing calcaneal osteotomies and supramalleolar osteotomies are equivalent in redistributing forces in cavovarus deformities [17]. While we had considered both options preoperatively, we elected to perform a calcaneal osteotomy as we felt it would permit a more rapid recovery and is more commonly performed in our practice. An alternative technique to correct the ankle/hindfoot varus in the setting of transverse tarsal arthritis is to rotate the hindfoot relative to the midfoot through the talonavicular joint with subsequent fusion of the talonavicular and calcaneocuboid joints. This has the potential advantage of obviating the need for a lateralizing calcaneal osteotomy, and in turn the risk for a tibial nerve complication. However this approach may require a subsequent dorsiflexion osteotomy of the first metatarsal to realign the medial column and was not our operation of choice. Finally, had the subtalar joint been arthritic, a triple arthrodesis could have been considered, simultaneously permitting coronal alignment correction. However this was not the case for our patient and its preservation has allowed us to maintain some hindfoot motion.
Fig. 5. Postoperative weightbearing AP (A), lateral (B) and axial hindfoot (C) radiographs taken 6 months postoperatively demonstrating arthrodesis of the calcaneocuboid and talonavicular articulations and improved coronal hindfoot alignment.
Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006
G Model
FAS-751; No. of Pages 5 R.J. Walls et al. / Foot and Ankle Surgery xxx (2014) e1–e5
4. Conclusion Tarsal tunnel syndrome is a rare complication following lateral translational calcaneal osteotomies. It has only been reported previously in patients with pre-existing sensorimotor disease. Our report describes this complication in a neurologically intact patient with post-traumatic hindfoot varus. Increased awareness of this condition is needed to encourage prompt diagnosis, and to allow emergent operative release of the tarsal tunnel to maximize patient outcomes. We now advocate the triplanar calcaneal osteotomy (Malerba) as an alternative method to correct hindfoot varus, which may lower the risk of neurovascular compromise. Alternatively, prophylactic tarsal tunnel release may be considered at the time a lateralizing calcaneal osteotomy is performed. Conflict of interest No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. The authors received no financial support for the research, authorship, and/or publication of this article. Acknowledgement No sponsors or external enterprises provided funding for this study. References [1] Leeuwesteijn AE, de Visser E, Louwerens JW. Flexible cavovarus feet in Charcot–Marie–Tooth disease treated with first ray proximal dorsiflexion osteotomy combined with soft tissue surgery: a short-term to mid-term outcome study. Foot Ankle Surg 2010;16:142–7.
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Please cite this article in press as: Walls RJ, et al. A case of acute tarsal tunnel syndrome following lateralizing calcaneal osteotomy. Foot Ankle Surg (2014), http://dx.doi.org/10.1016/j.fas.2014.07.006