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Osteochondroma of the Tibial Sesamoid: A Case Report and Review of the Literature
The Journal of Foot & Ankle Surgery xxx (2017) 1–4
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Case Reports and Series
Osteochondroma of the Tibial Sesamoid: A Case Report and Review of the Literature Kazuo Ouchi, MD 1, Michiyuki Hakozaki, MD 2, Shin-ichi Kikuchi, MD 3, Shoji Yabuki, MD 4, Shin-ichi Konno, MD 5 1
Chief, Division of Foot and Ankle Surgery, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan Associate Professor, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan Chief Director and President, Fukushima Medical University, Fukushima, Japan 4 Professor, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan 5 Professor and Chairman, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan 2 3
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Osteochondroma, one of the most common benign bone tumors, frequently occurs in the metaphysis of the long bones. We report an extremely rare case of osteochondroma that occurred in the tibial sesamoid. The patient was a 62-year-old Japanese male. He presented with a 1-year history of pain and a hard mass on the plantar aspect of the right forefoot sole. The osteochondroma protruded toward the sole from the tibial sesamoid, leading to pain on weightbearing. After tibial sesamoidectomy, the patient’s symptoms were eliminated, and no pain or complications such as hallux valgus occurred after the surgery. Although a potential risk exists of postoperative hallux valgus deformity, tibial sesamoidectomy seems to be an appropriate surgical option for both osteochondroma and bizarre parosteal osteochondromatous proliferation to avoid residual pain or local recurrence. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: bizarre parosteal osteochondromatous proliferation osteochondroma sesamoidectomy tibial sesamoid
Osteochondroma is one of the most common benign bone tumors and accounts for 35% of benign and 8% of surgically treated bone tumors (1). Osteochondroma frequently occurs in the metaphysis of the long bone of the extremities but rarely occurs in the foot or ankle. We describe an exceedingly rare case of osteochondroma of the tibial sesamoid and discuss this case with reference to the published data.
Case Report A 62-year-old Japanese male with no history of major illness presented with a 1-year history of pain and a hard mass on the plantar aspect of the right forefoot sole. He had no history of trauma. The patient visited our hospital because the protrusion had gradually increased in size. The physical examination revealed an approximately 1-cm solid mass on the plantar aspect of the right first metatarsophalangeal Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Kazuo Ouchi, MD, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan. E-mail address: [email protected] (K. Ouchi).
joint. Although a formation of callosity and tenderness were present in that region, no erythema, swelling, or local increased temperature was observed (Fig. 1). He had no hallux valgus deformity, and the range of motion of the great toe was not limited. Plain radiographs of the right foot revealed a bony stalk continuing directly from the tibial sesamoid, projecting in the medial–plantar direction (Fig. 2A and B). Computed tomography showed the bony mass, 5 4 8 mm in size, with continuity with the cortex of the tibial sesamoid (Fig. 2C). Magnetic resonance imaging showed a thin cartilage cap on the top of the bony stalk with low intensity on T1weighted imaging and high intensity on T2-weighted imaging (Fig. 2D and E). From the radiologic findings, we initially suspected that the tumor was an osteochondroma or bizarre parosteal osteochondromatous proliferation (BPOP). We decided to perform surgical treatment because the patient was in severe pain and the bony protrusion toward the sole was prominent. A 3.0-cm midline skin incision was made on the medial and slightly plantar side of the first metatarsophalangeal joint of the right foot. The medial plantar sensory nerve was separated carefully, and linear capsulotomy was performed. The plantar side of the first metatarsal bone was exposed to identify the tibial sesamoid from the metatarsal articular surface. The tibial sesamoid was confirmed by intraoperative fluoroscopic guidance and was excised from the metatarsal articular surface.
1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.10.007
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K. Ouchi et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–4
cavity of the sesamoid (Fig. 3B). These findings were consistent with osteochondroma. Hypercellularity, enlargement of chondrocytes (bizarre) in the cartilage tissue, and proliferation of spindle cells, which are the characteristic findings in BPOP (2,3), were not observed (Fig. 3D). On the day after surgery, the patient started to walk with a heel gait. Walking with full weightbearing was permitted 1 week postoperatively. The patient’s right foot pain had disappeared at 8 months after surgery. At 5 years after surgery, the patient was free of pain and local recurrence and had no impairments in his activities of daily living. The Japanese Society of Surgery of the Foot hallux metatarsophalangeal–interphalangeal scale (4,5) improved from 64 points before surgery to 100 points after surgery. The hallux valgus angle was 16 preoperatively and 16 at 5 years after the surgery, showing no occurrence of postoperative hallux valgus (Fig. 4A and B).
Fig. 1. A bony protrusion in the plantar region of the patient’s right first metatarsal head (arrow).
Because the sesamoid was buried in the flexor hallucis brevis, the attached surrounding soft tissue was excised by a sharp dissection. The tumor protruded prominently toward the plantar side; therefore, the sesamoid was detached circumferentially and carefully to avoid damage to the flexor hallucis longus tendon. After excision of the tibial sesamoid, the defect was reduced with 2-0 absorbable suture. Grossly, the surgical specimen consisted of a bony pedicle and a thin cartilage cap (7 4 mm) that was directly connected to the sesamoid (Fig. 3A). The microscopic examination revealed the hyaline cartilage cap with matured trabecular-appearing bone (Fig. 3B and C). The lesion contained bone marrow and continued to the medullary
Discussion Osteochondroma occurring in the foot and toe is unusual and accounted for 1.2% of all osteochondromas in a Mayo Clinic series (3). In particular, osteochondroma occurring in the foot is an exceedingly rare condition. To the best of our knowledge, only 1 case has been reported to occur from the tibial sesamoid (6), with 1 additional case of extraskeletal osteochondroma developing around the tibial sesamoid (7) in the English literature. In contrast, BPOP is a more frequent osteochondroma-like lesion in the hand and foot, especially in the vicinity of the tibial sesamoid (7–10). The radiologic distinction between osteochondroma and BPOP is frequently difficult, in particular, in small lesions. Although both osteochondroma and BPOP are benign lesions, osteochondroma will nearly always be cured by complete excision of the cartilage cap, and
Fig. 2. (A) Dorsoplantar and (B) axial plain radiographs of the right great toe showing a bony protrusion on the plantar side of the tibial sesamoid (arrow). (C) Coronal computed tomography scan showing a distinct bony protrusion continuous with the sesamoid on the plantar side of the tibial sesamoid (arrow). Magnetic resonance imaging scans showing a thin cartilage cap with (D) low intensity on T1-weighted image and (E) high intensity on T2-weighted image on the surface of the bony protrusion (arrows).
K. Ouchi et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–4
3
Fig. 3. (A) Gross view of surgical specimen showing a bony pedicle with a thin cartilage cap directly connected to the sesamoid. (B) A Loupe image showing the hyaline cartilage cap with matured trabecular-appearing bone that contained bone marrow and directly continued (arrow) to the medullary cavity of the sesamoid (original magnification 12.5; hematoxylin-eosin stain). (C) Low-power appearance showing the junction between the hyaline cartilage and bony stalk (original magnification 40; hematoxylin-eosin stain). (D) High-power view showing the intertrabecular spaces containing fatty and hematopoietic mallow (original magnification 200; hematoxylin-eosin stain).
Fig. 4. Plain radiographs of the right great toe 5 years after surgery. (A) Weightbearing dorsoplantar view showing no occurrence of postoperative hallux valgus. (B) Axial view showing no local recurrence.
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K. Ouchi et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–4
BPOP frequently recurs (>50%) (3) and requires strict postoperative monitoring. Histopathologically, osteochondroma can be differentiated from BPOP in that BPOP is parosteal and attaches to the surface of the cortex of the underlying bone, and osteochondroma contains bone marrow that directly continues to the medullary cavity of the underlying bone. In the present case, we were able to diagnose the lesion as an osteochondroma from the histologic findings. The standard surgical procedure for osteochondroma is simple tumor resection at the base of the bony pedicle. In our patient’s case, however, because the tumor was located on the plantar side of the sesamoid, the possibility of postoperative plantar pain after simple tumorectomy was a concern. Moreover, from the radiologic findings, we could not rule out the possibility of BPOP, which has a high recurrence rate (2,3). Therefore, we performed tibial sesamoidectomy together with tumor resection. Although the postoperative risk of hallux valgus as a complication of excision of the tibial sesamoid is still controversial (11,12), our patient did not develop hallux valgus deformity after the surgery. In conclusion, we report what we believe to be the second case of osteochondroma of the tibial sesamoid. The associated pain was eliminated by excision of the tibial sesamoid. Although a potential risk exists of postoperative hallux valgus deformity, the tibial sesamoidectomy seems to be an appropriate surgical option for both osteochondroma and BPOP to avoid residual pain and local recurrence. References
2.
3.
4.
5.
6. 7.
8.
9.
10.
11. 12.
e JVMG, Heymann D, Wuyts W. Osteochondroma. In: WHO Classification of 1. Bove Tumours of Soft Tissue and Bone, ed 4, pp. 250–251, edited by CDM Fletcher,
JA Bridge, PCW Hogendoorn, F Mertens, International Agency for Research on Cancer, Lyon, 2013. Sciot R, Mandahl N. Subungual exostosis and bizarre parosteal osteochondromatous proliferation. In: WHO Classification of Tumours of Soft Tissue and Bone, ed 4, pp. 259–260, edited by CDM Fletcher, JA Bridge, PCW Hogendoorn, F Mertens, International Agency for Research on Cancer, Lyon, 2013. Uni KK, Inwards CY. Osteochondroma (osteocartilaginous exostosis). In: Dahlin’s Bone Tumors, ed 6, pp. 9–21, edited by KK Uni, CY Inwards, Lippincott Williams & Wilkins, Philadelphia, 2010. Niki H, Aoki H, Inokuchi S, Ozeki S, Kinoshita M, Kura H, Tanaka Y, Noguchi M, Nomura S, Hatori M, Tatsunami S. Development and reliability of a standard rating system for outcome measurement of foot and ankle disorders I: development of standard rating system. J Orthop Sci 10:457–465, 2005. Niki H, Aoki H, Inokuchi S, Ozeki S, Kinoshita M, Kura H, Tanaka Y, Noguchi M, Nomura S, Hatori M, Tatsunami S. Development and reliability of a standard rating system for outcome measurement of foot and ankle disorders. II: interclinician and intraclinician reliability and validity of the newly established standard rating scales and Japanese Orthopaedic Association rating scale. J Orthop Sci 10:466–474, 2005. Mowad SC Sr, Zichichi S, Mullin R. Osteochondroma of the tibial sesamoid. J Am Podiatr Med Assoc 85:765–766, 1995. Okada A, Hatori M, Hashimoto Y, Lee E. Painful extraskeletal osteochondroma under the tarsal sesamoid: a case report and review of literature. Eur J Orthop Surg Traumatol 22:215–220, 2012. Harty JA, Kelly P, Niall D, O’Keane JC, Stephens MM. Bizarre parosteal osteochondromatous proliferation (Nora’s lesion) of the sesamoid: a case report. Foot Ankle Int 21:408–412, 2000. Noguchi M, Ikoma K, Matsumoto N, Nagasawa K. Bizarre parosteal osteochondromatous proliferation of the sesamoid: an unusual hallux valgus deformity. Foot Ankle Int 25:503–506, 2004. Berber O, Dawson-Bowling S, Jalgaonkar A, Miles J, Pollock RC, Skinner JA, Aston WJ, Briggs TW. Bizarre parosteal osteochondromatous proliferation of bone: clinical management of a series of 22 cases. J Bone Joint Surg Br 93:1118– 1121, 2011. Nayfa TM, Sorto LA Jr. The incidence of hallux abductus following tibial sesamoidectomy. J Am Podiatry Assoc 72:617–620, 1982. Canales MB, DeMore M III, Bowen MF, Ehredt DJ Jr, Razzante MC. Fact or fiction? Iatrogenic hallux abducto valgus secondary to tibial sesamoidectomy. J Foot Ankle Surg 54:82–88, 2015.
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Case Reports and Series
Osteochondroma of the Tibial Sesamoid: A Case Report and Review of the Literature Kazuo Ouchi, MD 1, Michiyuki Hakozaki, MD 2, Shin-ichi Kikuchi, MD 3, Shoji Yabuki, MD 4, Shin-ichi Konno, MD 5 1
Chief, Division of Foot and Ankle Surgery, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan Associate Professor, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan Chief Director and President, Fukushima Medical University, Fukushima, Japan 4 Professor, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan 5 Professor and Chairman, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan 2 3
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 4
Osteochondroma, one of the most common benign bone tumors, frequently occurs in the metaphysis of the long bones. We report an extremely rare case of osteochondroma that occurred in the tibial sesamoid. The patient was a 62-year-old Japanese male. He presented with a 1-year history of pain and a hard mass on the plantar aspect of the right forefoot sole. The osteochondroma protruded toward the sole from the tibial sesamoid, leading to pain on weightbearing. After tibial sesamoidectomy, the patient’s symptoms were eliminated, and no pain or complications such as hallux valgus occurred after the surgery. Although a potential risk exists of postoperative hallux valgus deformity, tibial sesamoidectomy seems to be an appropriate surgical option for both osteochondroma and bizarre parosteal osteochondromatous proliferation to avoid residual pain or local recurrence. Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: bizarre parosteal osteochondromatous proliferation osteochondroma sesamoidectomy tibial sesamoid
Osteochondroma is one of the most common benign bone tumors and accounts for 35% of benign and 8% of surgically treated bone tumors (1). Osteochondroma frequently occurs in the metaphysis of the long bone of the extremities but rarely occurs in the foot or ankle. We describe an exceedingly rare case of osteochondroma of the tibial sesamoid and discuss this case with reference to the published data.
Case Report A 62-year-old Japanese male with no history of major illness presented with a 1-year history of pain and a hard mass on the plantar aspect of the right forefoot sole. He had no history of trauma. The patient visited our hospital because the protrusion had gradually increased in size. The physical examination revealed an approximately 1-cm solid mass on the plantar aspect of the right first metatarsophalangeal Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Kazuo Ouchi, MD, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan. E-mail address: [email protected] (K. Ouchi).
joint. Although a formation of callosity and tenderness were present in that region, no erythema, swelling, or local increased temperature was observed (Fig. 1). He had no hallux valgus deformity, and the range of motion of the great toe was not limited. Plain radiographs of the right foot revealed a bony stalk continuing directly from the tibial sesamoid, projecting in the medial–plantar direction (Fig. 2A and B). Computed tomography showed the bony mass, 5 4 8 mm in size, with continuity with the cortex of the tibial sesamoid (Fig. 2C). Magnetic resonance imaging showed a thin cartilage cap on the top of the bony stalk with low intensity on T1weighted imaging and high intensity on T2-weighted imaging (Fig. 2D and E). From the radiologic findings, we initially suspected that the tumor was an osteochondroma or bizarre parosteal osteochondromatous proliferation (BPOP). We decided to perform surgical treatment because the patient was in severe pain and the bony protrusion toward the sole was prominent. A 3.0-cm midline skin incision was made on the medial and slightly plantar side of the first metatarsophalangeal joint of the right foot. The medial plantar sensory nerve was separated carefully, and linear capsulotomy was performed. The plantar side of the first metatarsal bone was exposed to identify the tibial sesamoid from the metatarsal articular surface. The tibial sesamoid was confirmed by intraoperative fluoroscopic guidance and was excised from the metatarsal articular surface.
1067-2516/$ - see front matter Ó 2016 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2016.10.007
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K. Ouchi et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–4
cavity of the sesamoid (Fig. 3B). These findings were consistent with osteochondroma. Hypercellularity, enlargement of chondrocytes (bizarre) in the cartilage tissue, and proliferation of spindle cells, which are the characteristic findings in BPOP (2,3), were not observed (Fig. 3D). On the day after surgery, the patient started to walk with a heel gait. Walking with full weightbearing was permitted 1 week postoperatively. The patient’s right foot pain had disappeared at 8 months after surgery. At 5 years after surgery, the patient was free of pain and local recurrence and had no impairments in his activities of daily living. The Japanese Society of Surgery of the Foot hallux metatarsophalangeal–interphalangeal scale (4,5) improved from 64 points before surgery to 100 points after surgery. The hallux valgus angle was 16 preoperatively and 16 at 5 years after the surgery, showing no occurrence of postoperative hallux valgus (Fig. 4A and B).
Fig. 1. A bony protrusion in the plantar region of the patient’s right first metatarsal head (arrow).
Because the sesamoid was buried in the flexor hallucis brevis, the attached surrounding soft tissue was excised by a sharp dissection. The tumor protruded prominently toward the plantar side; therefore, the sesamoid was detached circumferentially and carefully to avoid damage to the flexor hallucis longus tendon. After excision of the tibial sesamoid, the defect was reduced with 2-0 absorbable suture. Grossly, the surgical specimen consisted of a bony pedicle and a thin cartilage cap (7 4 mm) that was directly connected to the sesamoid (Fig. 3A). The microscopic examination revealed the hyaline cartilage cap with matured trabecular-appearing bone (Fig. 3B and C). The lesion contained bone marrow and continued to the medullary
Discussion Osteochondroma occurring in the foot and toe is unusual and accounted for 1.2% of all osteochondromas in a Mayo Clinic series (3). In particular, osteochondroma occurring in the foot is an exceedingly rare condition. To the best of our knowledge, only 1 case has been reported to occur from the tibial sesamoid (6), with 1 additional case of extraskeletal osteochondroma developing around the tibial sesamoid (7) in the English literature. In contrast, BPOP is a more frequent osteochondroma-like lesion in the hand and foot, especially in the vicinity of the tibial sesamoid (7–10). The radiologic distinction between osteochondroma and BPOP is frequently difficult, in particular, in small lesions. Although both osteochondroma and BPOP are benign lesions, osteochondroma will nearly always be cured by complete excision of the cartilage cap, and
Fig. 2. (A) Dorsoplantar and (B) axial plain radiographs of the right great toe showing a bony protrusion on the plantar side of the tibial sesamoid (arrow). (C) Coronal computed tomography scan showing a distinct bony protrusion continuous with the sesamoid on the plantar side of the tibial sesamoid (arrow). Magnetic resonance imaging scans showing a thin cartilage cap with (D) low intensity on T1-weighted image and (E) high intensity on T2-weighted image on the surface of the bony protrusion (arrows).
K. Ouchi et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–4
3
Fig. 3. (A) Gross view of surgical specimen showing a bony pedicle with a thin cartilage cap directly connected to the sesamoid. (B) A Loupe image showing the hyaline cartilage cap with matured trabecular-appearing bone that contained bone marrow and directly continued (arrow) to the medullary cavity of the sesamoid (original magnification 12.5; hematoxylin-eosin stain). (C) Low-power appearance showing the junction between the hyaline cartilage and bony stalk (original magnification 40; hematoxylin-eosin stain). (D) High-power view showing the intertrabecular spaces containing fatty and hematopoietic mallow (original magnification 200; hematoxylin-eosin stain).
Fig. 4. Plain radiographs of the right great toe 5 years after surgery. (A) Weightbearing dorsoplantar view showing no occurrence of postoperative hallux valgus. (B) Axial view showing no local recurrence.
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K. Ouchi et al. / The Journal of Foot & Ankle Surgery xxx (2017) 1–4
BPOP frequently recurs (>50%) (3) and requires strict postoperative monitoring. Histopathologically, osteochondroma can be differentiated from BPOP in that BPOP is parosteal and attaches to the surface of the cortex of the underlying bone, and osteochondroma contains bone marrow that directly continues to the medullary cavity of the underlying bone. In the present case, we were able to diagnose the lesion as an osteochondroma from the histologic findings. The standard surgical procedure for osteochondroma is simple tumor resection at the base of the bony pedicle. In our patient’s case, however, because the tumor was located on the plantar side of the sesamoid, the possibility of postoperative plantar pain after simple tumorectomy was a concern. Moreover, from the radiologic findings, we could not rule out the possibility of BPOP, which has a high recurrence rate (2,3). Therefore, we performed tibial sesamoidectomy together with tumor resection. Although the postoperative risk of hallux valgus as a complication of excision of the tibial sesamoid is still controversial (11,12), our patient did not develop hallux valgus deformity after the surgery. In conclusion, we report what we believe to be the second case of osteochondroma of the tibial sesamoid. The associated pain was eliminated by excision of the tibial sesamoid. Although a potential risk exists of postoperative hallux valgus deformity, the tibial sesamoidectomy seems to be an appropriate surgical option for both osteochondroma and BPOP to avoid residual pain and local recurrence. References
2.
3.
4.
5.
6. 7.
8.
9.
10.
11. 12.
e JVMG, Heymann D, Wuyts W. Osteochondroma. In: WHO Classification of 1. Bove Tumours of Soft Tissue and Bone, ed 4, pp. 250–251, edited by CDM Fletcher,
JA Bridge, PCW Hogendoorn, F Mertens, International Agency for Research on Cancer, Lyon, 2013. Sciot R, Mandahl N. Subungual exostosis and bizarre parosteal osteochondromatous proliferation. In: WHO Classification of Tumours of Soft Tissue and Bone, ed 4, pp. 259–260, edited by CDM Fletcher, JA Bridge, PCW Hogendoorn, F Mertens, International Agency for Research on Cancer, Lyon, 2013. Uni KK, Inwards CY. Osteochondroma (osteocartilaginous exostosis). In: Dahlin’s Bone Tumors, ed 6, pp. 9–21, edited by KK Uni, CY Inwards, Lippincott Williams & Wilkins, Philadelphia, 2010. Niki H, Aoki H, Inokuchi S, Ozeki S, Kinoshita M, Kura H, Tanaka Y, Noguchi M, Nomura S, Hatori M, Tatsunami S. Development and reliability of a standard rating system for outcome measurement of foot and ankle disorders I: development of standard rating system. J Orthop Sci 10:457–465, 2005. Niki H, Aoki H, Inokuchi S, Ozeki S, Kinoshita M, Kura H, Tanaka Y, Noguchi M, Nomura S, Hatori M, Tatsunami S. Development and reliability of a standard rating system for outcome measurement of foot and ankle disorders. II: interclinician and intraclinician reliability and validity of the newly established standard rating scales and Japanese Orthopaedic Association rating scale. J Orthop Sci 10:466–474, 2005. Mowad SC Sr, Zichichi S, Mullin R. Osteochondroma of the tibial sesamoid. J Am Podiatr Med Assoc 85:765–766, 1995. Okada A, Hatori M, Hashimoto Y, Lee E. Painful extraskeletal osteochondroma under the tarsal sesamoid: a case report and review of literature. Eur J Orthop Surg Traumatol 22:215–220, 2012. Harty JA, Kelly P, Niall D, O’Keane JC, Stephens MM. Bizarre parosteal osteochondromatous proliferation (Nora’s lesion) of the sesamoid: a case report. Foot Ankle Int 21:408–412, 2000. Noguchi M, Ikoma K, Matsumoto N, Nagasawa K. Bizarre parosteal osteochondromatous proliferation of the sesamoid: an unusual hallux valgus deformity. Foot Ankle Int 25:503–506, 2004. Berber O, Dawson-Bowling S, Jalgaonkar A, Miles J, Pollock RC, Skinner JA, Aston WJ, Briggs TW. Bizarre parosteal osteochondromatous proliferation of bone: clinical management of a series of 22 cases. J Bone Joint Surg Br 93:1118– 1121, 2011. Nayfa TM, Sorto LA Jr. The incidence of hallux abductus following tibial sesamoidectomy. J Am Podiatry Assoc 72:617–620, 1982. Canales MB, DeMore M III, Bowen MF, Ehredt DJ Jr, Razzante MC. Fact or fiction? Iatrogenic hallux abducto valgus secondary to tibial sesamoidectomy. J Foot Ankle Surg 54:82–88, 2015.