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Osteochondritis of the hallux sesamoid bones
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Foot and Ankle Surgery 14 (2008) 175–179 www.elsevier.com/locate/fas
Review
Osteochondritis of the hallux sesamoid bones Ignacio Martı´nez Garrido M.D.*, Marta Navarro Bosch M.D., Marı´a Sa´nchez Gonza´lez M.D., Vicente Vicent Carsı´ Department of Orthopaedics, La Fe Hospital, University of Valencia, Valencia, Spain Received 19 November 2007; received in revised form 5 February 2008; accepted 6 February 2008
Abstract Osteochondritis of the sesamoid bones is an infrequent condition which may affect both the medial and lateral hallux sesamoids. Those cases refractory to conservative treatment can be satisfactorily solved by carrying out its surgical excision. We present a literature review about its causes, pathophysiology, the diagnostic methods and the treatments options. # 2008 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. Keywords: Sesamoid bones; Avascular necrosis; Osteochondritis
Contents 1. 2. 3. 4. 5. 6. 7. 8. 9.
Introduction . . . . . . . . . . . . . . . . . . . . Anatomy and embryologic development . Vascularization . . . . . . . . . . . . . . . . . . Biomechanics . . . . . . . . . . . . . . . . . . . Epidemiology . . . . . . . . . . . . . . . . . . . Aetiology . . . . . . . . . . . . . . . . . . . . . . Diagnosis and differential diagnosis . . . . Treatment . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . Acknowledgement . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . .
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1. Introduction Pain in at the hallux metatarsophalangeal joint may be caused by a number of processes. Sesamoid pathology can present with incapacitating pain in this anatomical region [1]. Among all the affections of the sesamoids, the most uncommon is probably the osteochondritis [2,3]. Osteochondritis of the sesamoids is a rare condition characterized
* Corresponding author at: C./Pedro III El Grande, 26, 38 - 8a, 46005 Valencia, Spain. Tel.: +34 963504935. E-mail address: [email protected] (I.M. Garrido).
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by pain, tenderness to palpation and osseous fragmentation which appears on radiological examination [4]. Renander first described two cases of osteochondopathy of the medial hallucal sesamoid in 1924 [5]. Since then, the literature related to this injury mostly consisted of small series and case reports [6–9]. Surgical excision of one or both sesamoids should only be undertaken in recalcitrant cases, after a bad response to the initial conservative treatment with an accommodative orthosis. The objective of this article is to highlight the diagnostic difficulties with respect to other pathologies that may affect the sesamoids. Differential diagnosis is made with the aid of
1268-7731/$ – see front matter # 2008 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.fas.2008.02.004
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an appropriate radiological study as well as the complementary explorations required.
2. Anatomy and embryologic development The hallucal sesamoid bones, so called by Galen because of their resemblance to the sesame seed [10–12], appear between the 7th and the 10th gestational weeks [13,14] as two islands of mesenchymal cells within the tendon of the flexor hallucis brevis. Chondrification begins by the 12th week of foetal life. Ossification, frequently from multiple centers, occurs earlier in women. It is reported to commence between the sixth and the seventh years [15] and usually is completed by the 12th year [14]. The sesamoid bones with their muscular attachments (that is, the flexor hallucis brevis with its medial and lateral head, the adductor hallucis brevis with its transverse and oblique head, and the abductor hallucis brevis) are part of the hallux sesamoid complex. The conjoined tendons of these intrinsic muscles are strong links between the sesamoids and the first phalanx base. Both sesamoids present dorsal articular surfaces of hyaline cartilage in contact with the plantar cartilage of the metatarsal head. Attachments from the plantar fascia to both sesamoids, the thick intersesamoid ligament, the long flexor hallucis tendon and the first deep intermetatarsal sesamoid ligament are the elements that complete the great toe sesamoid complex.
The hallucal sesamoids are included in the tendons of the short flexor and their main function consists of diminishing plantar pressure in the first ray during the last phases of the walking cycle, enlarging the functional length of the first metatarsal, reducing the tensional forces of the first toe flexors and improving its mechanical work [10,11,13,19]. By absorbing most of the weight of the hallux, the hallucal sesamoids help to increase the mechanical impulse of the intrinsic musculature of the first ray [20,21].
5. Epidemiology The abnormalities of the sesamoids of the hallux are more frequent in professional athletes due to the repeated stress supported by the first metatarsophalageal joint [10,22]. Some authors suggest that women are affected more often, mostly between 2nd and 3rd decades of life [13]. There is no agreement in the literature when referring to which of the two sesamoids is affected more frequently by avascular necrosis. Some authors state that both sesamoids are equally affected [11,23,24]. Nevertheless, we can find studies suggesting that the medial sesamoid is affected more frequently [25], and others such as Karasick et al. [19] reflecting a larger rate of lesions in the fibular sesamoid.
6. Aetiology 3. Vascularization In the published studies there is a general agreement on the predominant blood supply to both sesamoids from the medial plantar artery (branch of the posterior tibial artery), entering its proximal poles through the attachment of the flexor hallucis brevis [16,17]. Sobel et al. [16] demonstrated a second major source of vascularity from vessels in the soft tissues at the plantar aspect of the sesamoids, and one minor supply penetrating distally through the capsular attachments. The publication by Pretterklieber and Wanivenhaus [18] describes three different patterns of arterial circulation of the sesamoids: type A (52%) via the medial plantar artery and the plantar arch; type B (24%), predominantly from the plantar arch; and type C (24%) originating only from the medial plantar artery. On the other hand, the vascular investigation by Chamberland et al. [17] explains accurately the effect of the blood supply to the sesamoids on the incidence of avascular necrosis and non-union after fractures.
4. Biomechanics Sesamoids of the metatarsophalangeal joint of the first toe play an important role in the function of the hallux [6].
Despite the fact that the cause of the osteochondritis is not clear, several hypotheses relate it with severe trauma [26] and with previous stress fractures [25]. Some authors also associate it with diminution of the sesamoids blood supply [16,18,27].
7. Diagnosis and differential diagnosis Diagnosis of this lesion requires a high index of suspicion, and a cautious clinical examination directed specifically towards the location of the pain. Accurate localization of pain originated at the sesamoids is difficult and it is often attributed to the first metatarsophalangeal joint [13]. In the early stages, and when there is no associated metatarsophalangeal joint pathology, an important clinical feature is the presence of pain with passive distal push of the involved sesamoid, as are the local signs of swelling and tenderness. Limited and painful dorsiflexion, although frequently seen with sesamoid problems, is more related to diffuse synovitis of the metatarsophalangeal joint. To establish the source of pain, injection of a local anaesthetic in the metatarsophalangeal joint may be used as a diagnostic tool. However, the results of diagnostic injections should be interpreted cautiously. Differential anaesthetic block of the metatarsophalangeal joint can assist
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Table 1 Differential diagnosis in patients with pain at the metatarso-sesamoidal joint Disorders of the great toe sesamoid complex
Comments
Congenital variations Symptomatic partition (Bipartite, tripartite, quadripartite) or abortive partition (hourglass shape) Hypertrophied sesamoid
Usually medial sesamoid affected bilaterally. Fractures and/or diastasis can superimpose following minimal trauma.
Acquired pathologies Trauma related Acute Acute fractures Capsular-ligamentous injuries (sesamoidal subluxation or dislocation) Repetitive stress-related Stress fractures Bursitis Sesamoiditis
Degenerative osteoarthritis affecting the metatarso-sesamoidal joint Systemic arthritis Rheumatoid arthritis Gout Seronegative spondyloarthropathies (psoriasis, Reiter, ankylosing spondylitis) Silicone synovitis Infection Osteomyelitis
Septic arthritis Neoplasms Plantar fibromatosis Synovial sarcoma Localized nodular synovitis Nerve compression Impingement of the plantar medial and lateral digital nerves
the physician in distinguishing between patients with intraarticular or extra-articular problems. Intra-articular block will not completely distinguish osteochondritis or other intrinsic sesamoid injury from problems involving adjacent soft tissues such as insertional tendinopathy of the flexor hallucis brevis. A careful differential diagnosis should be made before treatment. Many diseases can mimic osteochondritis of sesamoid bones; the most important are summarized in Table 1. Imaging techniques are very important for diagnosis of osteochondritis [14,28,29]. Routine X-rays are difficult to
Athletes, ballet dancers. Usually medial sesamoid affected. Athletes, ballet dancers. Forced hyperextension leading to plantar capsular disruption of the metatarso-sesamoid complex. MR imaging required. Often related to cavus foot. Clinical diagnosis by physical examination. Medial sesamoid usually involved. Unremarkable radiographic findings. Injuries typically affecting adjacent soft tissues (tendonitis of flexor hallucis brevis, flexor hallucis longus at the metatarsophalangeal joint, bursitis). Progression of localized trauma, chondromalacia and hallux rigidus. Often related to rotational deformities of the great toe (i.e. severe hallux valgus). Radiographically characterized by symmetric joint space narrowing, juxtaarticular erosions and osteopenia. Gouty tophy may erode sesamoids mimicking osteomyelitis. Periostitis and bone. formation on conventional radiography. Foreign-body granulomatous reactions to silicone implants in the FMTTPJ. Patients with decreased sensation (diabetic neuropathy, myelodysplasia, peripheral neuropathy, sciatic nerve injury). Usually secondary to a plantar puncture wound. Often resulting from sesamoid osteomyelitis.
Giant cell tumor of the tendon sheat. Tinel’s sign occasionally positive.
interpret because of bone overlap. We must pay special attention to the axial view, which shows the typical fragmentation of the affected sesamoid (Fig. 1). Also medial and lateral obliques can be used to visualize the lateral and the medial sesamoid, respectively. Bone scan will help us during the initial stage of the lesion in those cases in which the radiological study does not demonstrate changes of the sesamoids [24]. Currently, MRI is one of the best methods to evaluate the pathology of the sesamoids. The ischemic necrosis developed in the bone during osteochondritis is frequently not visible in X-rays, nevertheless it is always detected in
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Fig. 3. Pathologic specimen revealed cystic resorption and gross irregularity representative of osteochondritis.
8. Treatment
Fig. 1. Radiographic appearance of osteochondritis of the lateral sesamoid in a 27-year-old woman. (A) Antero-posterior radiograph demonstrating enlargement and fragmentation of the symptomatic fibular sesamoid. (B) Axial sesamoid view showing resorptive changes combined with sclerosis of the lateral sesamoid consisting with osteochondritis.
the MRI scan. The coronal images are the ones that offer the best exposition of the sesamoids (Fig. 2). Confirmation of the diagnosis of osteochondritis usually arrives after the histological study of the pathologic specimen. Macroscopically the sesamoidectomy specimen presents a fragmented and irregular aspect, typical of the necrotic bone (Fig. 3).
Fig. 2. Coronal T1-weighted MR image showing inhomogeneous illdefined areas of low signal intensity within the lateral sesamoid. Avascular changes and necrotic subchondral bone are responsible for these findings.
The treatment initially should be conservative, using footwear with a thick sole and insoles that discharge the painful sesamoid [24]. It may be combined with oral nonsteroidal anti-inflammatory drugs and physical therapy. The use of intra-articular steroid injections in the treatment of the osteochondritis is not contraindicated, although it is controversial. Using these medicines imprudently may cause opposite effects, due to the fact that its analgesic and anti-inflammatory properties may hide the importance of the osteochondritis [11]. For the cases in which the conservative treatment fails, the surgical extirpation of the affected sesamoid is indicated. Deformation does not usually appear after the isolated excision of one of the sesamoids as long as attention is paid to careful operative technique. Otherwise, removing both sesamoids may result in a decreased mechanical advantage of the flexor hallucis brevis muscle, and a cock up great toe deformity [1,30]. Fortunately the osteochondritis usually affects only one of the sesamoids and not both simultaneously. Julsrud [22] reported simultaneous osteonecrosis in a young woman treated with dual sesamoid excision and an interphalangeal joint fusion. Reported complications of sesamoid excision include drift of the hallux into either varus – after the resection of the lateral sesamoid – or valgus – after the resection of the medial sesamoid-, not complete pain relief and metatarsophalangeal joint stiffness [12,31]. The key factor to diminish the rate of complication (more than 50% in some series [12]) is probably to re-establish the normal relationship of the remaining conjoined tendon and capsule, thus restoring the off-loading mechanism of the first metatarsophalangeal joint. Some authors prefer a longitudinal plantar skin incision for the isolated excision of the fibular sesamoid [23,26].
I.M. Garrido et al. / Foot and Ankle Surgery 14 (2008) 175–179
Mann and Coughlin [31] recommend a lateral–dorsal approach in the first inter-metatarsian space. The potential disadvantage of this approach is the technical demand [11,23] but it avoids the risk of a painful or hypertrophic plantar scar.
9. Conclusion Despite being an uncommon condition, osteochondritis of the sesamoids should be considered when pain and tenderness appear under the first metatarsophalangeal joint. When conservative treatment fails surgery will confirm the diagnosis and usually leads to a satisfactory outcome.
Acknowledgement We thank Cassandra Rosenblum for her help in the preparation and translation of this manuscript.
References [1] Richardson EG. Hallucal sesamoid pain: causes and surgical treatment. J Am Acad Orthop Surg 1999;7:270–8. [2] Fleischli J, Cheleuitte E. Avascular necrosis of the hallucal sesamoids. J Foot Ankle Surg 1995;34:358–65. [3] Salvi V, Tos L. L’osteochondrosi die sesamoidi. Arch Orthop 1962;75:1294–304. [4] Velkes S, Pritsch M, Horoszowski H. Osteochondritis of the first metatarsal sesamoids. Arch Orthop Trauma Surg 1988;107:369–71. [5] Renander A. Two cases of typical osteochondropathy of the medial sesamoid bone of the first metatarsal. Acta Radiol 1924;3:521–7. [6] Ilfeld FW, Rosen V. Osteochondritis of the first metatarsal sesamoid. Clin Orthop 1972;85:38–41. [7] Zenklusen C, Cornut J, Belgrand L, Pfister JA. Aseptic osteonecrosis of the internal sesamoid bone of the large toe, apropos of 3 case reports in adults. Schweiz Rundsch Med Prax 1990;21(79):971–5. [8] Toussirot E, Jeunet L, Michel F, Kantelip B, Wendling D. Avascular necrosis of the hallucal sesamoids update with reference to two casereports. Joint Bone Spine 2003;70:307–9. [9] Ozkoc G, Akpinar S, Ozalay M, Hersekli MA, Pourbagher A, Kayaselcuk F, et al. Hallucal sesamoid osteonecrosis: an overlooked cause of forefoot pain. J Am Podiatr Med Assoc 2005;95:277–80.
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[10] Mc Bryde Jr AM, Anderson RB. Sesamoid foot disorders in the athlete. Clin Sports Med 1988;7:51–60. [11] Coughlin MJ. Sesamoids and accessory bones of the foot. In: Coughlin MJ, Mann RA, editors. Surgery of the foot and ankle, vol. 1. St. Louis, Missouri: Mosby; 1999. p. 437–500. [12] Inge GAL, Ferguson AB. Surgery of the sesamoid bones of the great toe. Arch Surg 1933;27:466–88. [13] Wuelker N, Wirth CJ. The great toe sesamoids. Foot Ankle Surg 1996;2:167–74. [14] Karadaglis D, Grace D. Morphology of the hallux sesamoids. Foot Ankle Surg 2003;9:165–7. [15] Kewenter Y. Die sesambeine des 1. metatarsophalangealgelenks des menschen. Acta Orthop Scand Suppl 1936;2:1–113. [16] Sobel M, Hashimoto J, Arnozcky S, et al. The microvascularute of the sesamoid complex; its clinical significance. Foot Ankle 1992;13:359– 63. [17] Chamberland PD, Smith JW, Fleming LL. The blood supply to the great toe sesamoids. Foot Ankle 1993;14:435–42. [18] Pretterklieber M, Wanivenhaus A. The arterial supply of the sesamoid bones of the hallux: the course and source of the nutrient arteries as an anatomical basis for surgical approaches to the great toe. Foot Ankle 1992;13:27–31. [19] Karasick D. Disorders of the hallux sesamoid complex. Skeletal Radiol 1998;27:411–8. [20] Dedmond BT, Cory JW, McBryde Jr A. The hallucal sesamoid complex. J Am Acad Orthop Surg 2006;14:745–53. [21] Kanatli U, Ozturk AM, Ercan NG, Ozalay M, Daglar B, Yetkin H. Absence of the medial sesamoid bone associated with metatarsophalangeal pain. Clin Anat 2006;19:634–9. [22] Julsrud M. Osteonecrosis of the tibial and fibular sesamoids in an aerobics instructor. J Foot Ankle Surg 1997;36:31–5. [23] Jahss MS. Disorders of the foot and ankle: medical and surgical management, 2nd ed., Philadelphia: WB Saunders; 1991. p. 1062–75. [24] Leventen MD, Edward O. Sesamoid disorders and treatment and update. Clin Orthop 1991;269:236–40. [25] Kliman ME, Gross AE, Pritzker KP, et al. Osteochondritis of the hallux sesamoid bone. Foot Ankle 1983;3:220–3. [26] Helal B. The great toe sesamoid bone: the lus or lost souls of Ushaia. Clin Orthop 1981;157:82–7. [27] Jahss ML. The sesamoids of the hallux. Clin Orthop 1981;157:88–97. [28] Grace DL. Sesamoid problems. Foot Ankle Clin 2000;5:609–27. [29] Taylor JA, Sartoris DJ, Huang GS, Resnick DL. Painful conditions affecting the first metatarsal sesamoid bones. Radiographics 1993;13:817–30. [30] Aper RL, Saltzman CL, Brown TD. The effect of hallux sesamoid resection on the effective moment of the flexor hallucis brevis. Foot Ankle Int 1994;15:462–70. [31] Mann RA, Coughlin MJ, Baxter D, et al. Sesamoidectomy of the great toe. In: American Orthopaedic Foot and Ankle Society, 15th annual meeting; 1985.
Foot and Ankle Surgery 14 (2008) 175–179 www.elsevier.com/locate/fas
Review
Osteochondritis of the hallux sesamoid bones Ignacio Martı´nez Garrido M.D.*, Marta Navarro Bosch M.D., Marı´a Sa´nchez Gonza´lez M.D., Vicente Vicent Carsı´ Department of Orthopaedics, La Fe Hospital, University of Valencia, Valencia, Spain Received 19 November 2007; received in revised form 5 February 2008; accepted 6 February 2008
Abstract Osteochondritis of the sesamoid bones is an infrequent condition which may affect both the medial and lateral hallux sesamoids. Those cases refractory to conservative treatment can be satisfactorily solved by carrying out its surgical excision. We present a literature review about its causes, pathophysiology, the diagnostic methods and the treatments options. # 2008 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. Keywords: Sesamoid bones; Avascular necrosis; Osteochondritis
Contents 1. 2. 3. 4. 5. 6. 7. 8. 9.
Introduction . . . . . . . . . . . . . . . . . . . . Anatomy and embryologic development . Vascularization . . . . . . . . . . . . . . . . . . Biomechanics . . . . . . . . . . . . . . . . . . . Epidemiology . . . . . . . . . . . . . . . . . . . Aetiology . . . . . . . . . . . . . . . . . . . . . . Diagnosis and differential diagnosis . . . . Treatment . . . . . . . . . . . . . . . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . . . . . Acknowledgement . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . .
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1. Introduction Pain in at the hallux metatarsophalangeal joint may be caused by a number of processes. Sesamoid pathology can present with incapacitating pain in this anatomical region [1]. Among all the affections of the sesamoids, the most uncommon is probably the osteochondritis [2,3]. Osteochondritis of the sesamoids is a rare condition characterized
* Corresponding author at: C./Pedro III El Grande, 26, 38 - 8a, 46005 Valencia, Spain. Tel.: +34 963504935. E-mail address: [email protected] (I.M. Garrido).
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by pain, tenderness to palpation and osseous fragmentation which appears on radiological examination [4]. Renander first described two cases of osteochondopathy of the medial hallucal sesamoid in 1924 [5]. Since then, the literature related to this injury mostly consisted of small series and case reports [6–9]. Surgical excision of one or both sesamoids should only be undertaken in recalcitrant cases, after a bad response to the initial conservative treatment with an accommodative orthosis. The objective of this article is to highlight the diagnostic difficulties with respect to other pathologies that may affect the sesamoids. Differential diagnosis is made with the aid of
1268-7731/$ – see front matter # 2008 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.fas.2008.02.004
176
I.M. Garrido et al. / Foot and Ankle Surgery 14 (2008) 175–179
an appropriate radiological study as well as the complementary explorations required.
2. Anatomy and embryologic development The hallucal sesamoid bones, so called by Galen because of their resemblance to the sesame seed [10–12], appear between the 7th and the 10th gestational weeks [13,14] as two islands of mesenchymal cells within the tendon of the flexor hallucis brevis. Chondrification begins by the 12th week of foetal life. Ossification, frequently from multiple centers, occurs earlier in women. It is reported to commence between the sixth and the seventh years [15] and usually is completed by the 12th year [14]. The sesamoid bones with their muscular attachments (that is, the flexor hallucis brevis with its medial and lateral head, the adductor hallucis brevis with its transverse and oblique head, and the abductor hallucis brevis) are part of the hallux sesamoid complex. The conjoined tendons of these intrinsic muscles are strong links between the sesamoids and the first phalanx base. Both sesamoids present dorsal articular surfaces of hyaline cartilage in contact with the plantar cartilage of the metatarsal head. Attachments from the plantar fascia to both sesamoids, the thick intersesamoid ligament, the long flexor hallucis tendon and the first deep intermetatarsal sesamoid ligament are the elements that complete the great toe sesamoid complex.
The hallucal sesamoids are included in the tendons of the short flexor and their main function consists of diminishing plantar pressure in the first ray during the last phases of the walking cycle, enlarging the functional length of the first metatarsal, reducing the tensional forces of the first toe flexors and improving its mechanical work [10,11,13,19]. By absorbing most of the weight of the hallux, the hallucal sesamoids help to increase the mechanical impulse of the intrinsic musculature of the first ray [20,21].
5. Epidemiology The abnormalities of the sesamoids of the hallux are more frequent in professional athletes due to the repeated stress supported by the first metatarsophalageal joint [10,22]. Some authors suggest that women are affected more often, mostly between 2nd and 3rd decades of life [13]. There is no agreement in the literature when referring to which of the two sesamoids is affected more frequently by avascular necrosis. Some authors state that both sesamoids are equally affected [11,23,24]. Nevertheless, we can find studies suggesting that the medial sesamoid is affected more frequently [25], and others such as Karasick et al. [19] reflecting a larger rate of lesions in the fibular sesamoid.
6. Aetiology 3. Vascularization In the published studies there is a general agreement on the predominant blood supply to both sesamoids from the medial plantar artery (branch of the posterior tibial artery), entering its proximal poles through the attachment of the flexor hallucis brevis [16,17]. Sobel et al. [16] demonstrated a second major source of vascularity from vessels in the soft tissues at the plantar aspect of the sesamoids, and one minor supply penetrating distally through the capsular attachments. The publication by Pretterklieber and Wanivenhaus [18] describes three different patterns of arterial circulation of the sesamoids: type A (52%) via the medial plantar artery and the plantar arch; type B (24%), predominantly from the plantar arch; and type C (24%) originating only from the medial plantar artery. On the other hand, the vascular investigation by Chamberland et al. [17] explains accurately the effect of the blood supply to the sesamoids on the incidence of avascular necrosis and non-union after fractures.
4. Biomechanics Sesamoids of the metatarsophalangeal joint of the first toe play an important role in the function of the hallux [6].
Despite the fact that the cause of the osteochondritis is not clear, several hypotheses relate it with severe trauma [26] and with previous stress fractures [25]. Some authors also associate it with diminution of the sesamoids blood supply [16,18,27].
7. Diagnosis and differential diagnosis Diagnosis of this lesion requires a high index of suspicion, and a cautious clinical examination directed specifically towards the location of the pain. Accurate localization of pain originated at the sesamoids is difficult and it is often attributed to the first metatarsophalangeal joint [13]. In the early stages, and when there is no associated metatarsophalangeal joint pathology, an important clinical feature is the presence of pain with passive distal push of the involved sesamoid, as are the local signs of swelling and tenderness. Limited and painful dorsiflexion, although frequently seen with sesamoid problems, is more related to diffuse synovitis of the metatarsophalangeal joint. To establish the source of pain, injection of a local anaesthetic in the metatarsophalangeal joint may be used as a diagnostic tool. However, the results of diagnostic injections should be interpreted cautiously. Differential anaesthetic block of the metatarsophalangeal joint can assist
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Table 1 Differential diagnosis in patients with pain at the metatarso-sesamoidal joint Disorders of the great toe sesamoid complex
Comments
Congenital variations Symptomatic partition (Bipartite, tripartite, quadripartite) or abortive partition (hourglass shape) Hypertrophied sesamoid
Usually medial sesamoid affected bilaterally. Fractures and/or diastasis can superimpose following minimal trauma.
Acquired pathologies Trauma related Acute Acute fractures Capsular-ligamentous injuries (sesamoidal subluxation or dislocation) Repetitive stress-related Stress fractures Bursitis Sesamoiditis
Degenerative osteoarthritis affecting the metatarso-sesamoidal joint Systemic arthritis Rheumatoid arthritis Gout Seronegative spondyloarthropathies (psoriasis, Reiter, ankylosing spondylitis) Silicone synovitis Infection Osteomyelitis
Septic arthritis Neoplasms Plantar fibromatosis Synovial sarcoma Localized nodular synovitis Nerve compression Impingement of the plantar medial and lateral digital nerves
the physician in distinguishing between patients with intraarticular or extra-articular problems. Intra-articular block will not completely distinguish osteochondritis or other intrinsic sesamoid injury from problems involving adjacent soft tissues such as insertional tendinopathy of the flexor hallucis brevis. A careful differential diagnosis should be made before treatment. Many diseases can mimic osteochondritis of sesamoid bones; the most important are summarized in Table 1. Imaging techniques are very important for diagnosis of osteochondritis [14,28,29]. Routine X-rays are difficult to
Athletes, ballet dancers. Usually medial sesamoid affected. Athletes, ballet dancers. Forced hyperextension leading to plantar capsular disruption of the metatarso-sesamoid complex. MR imaging required. Often related to cavus foot. Clinical diagnosis by physical examination. Medial sesamoid usually involved. Unremarkable radiographic findings. Injuries typically affecting adjacent soft tissues (tendonitis of flexor hallucis brevis, flexor hallucis longus at the metatarsophalangeal joint, bursitis). Progression of localized trauma, chondromalacia and hallux rigidus. Often related to rotational deformities of the great toe (i.e. severe hallux valgus). Radiographically characterized by symmetric joint space narrowing, juxtaarticular erosions and osteopenia. Gouty tophy may erode sesamoids mimicking osteomyelitis. Periostitis and bone. formation on conventional radiography. Foreign-body granulomatous reactions to silicone implants in the FMTTPJ. Patients with decreased sensation (diabetic neuropathy, myelodysplasia, peripheral neuropathy, sciatic nerve injury). Usually secondary to a plantar puncture wound. Often resulting from sesamoid osteomyelitis.
Giant cell tumor of the tendon sheat. Tinel’s sign occasionally positive.
interpret because of bone overlap. We must pay special attention to the axial view, which shows the typical fragmentation of the affected sesamoid (Fig. 1). Also medial and lateral obliques can be used to visualize the lateral and the medial sesamoid, respectively. Bone scan will help us during the initial stage of the lesion in those cases in which the radiological study does not demonstrate changes of the sesamoids [24]. Currently, MRI is one of the best methods to evaluate the pathology of the sesamoids. The ischemic necrosis developed in the bone during osteochondritis is frequently not visible in X-rays, nevertheless it is always detected in
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Fig. 3. Pathologic specimen revealed cystic resorption and gross irregularity representative of osteochondritis.
8. Treatment
Fig. 1. Radiographic appearance of osteochondritis of the lateral sesamoid in a 27-year-old woman. (A) Antero-posterior radiograph demonstrating enlargement and fragmentation of the symptomatic fibular sesamoid. (B) Axial sesamoid view showing resorptive changes combined with sclerosis of the lateral sesamoid consisting with osteochondritis.
the MRI scan. The coronal images are the ones that offer the best exposition of the sesamoids (Fig. 2). Confirmation of the diagnosis of osteochondritis usually arrives after the histological study of the pathologic specimen. Macroscopically the sesamoidectomy specimen presents a fragmented and irregular aspect, typical of the necrotic bone (Fig. 3).
Fig. 2. Coronal T1-weighted MR image showing inhomogeneous illdefined areas of low signal intensity within the lateral sesamoid. Avascular changes and necrotic subchondral bone are responsible for these findings.
The treatment initially should be conservative, using footwear with a thick sole and insoles that discharge the painful sesamoid [24]. It may be combined with oral nonsteroidal anti-inflammatory drugs and physical therapy. The use of intra-articular steroid injections in the treatment of the osteochondritis is not contraindicated, although it is controversial. Using these medicines imprudently may cause opposite effects, due to the fact that its analgesic and anti-inflammatory properties may hide the importance of the osteochondritis [11]. For the cases in which the conservative treatment fails, the surgical extirpation of the affected sesamoid is indicated. Deformation does not usually appear after the isolated excision of one of the sesamoids as long as attention is paid to careful operative technique. Otherwise, removing both sesamoids may result in a decreased mechanical advantage of the flexor hallucis brevis muscle, and a cock up great toe deformity [1,30]. Fortunately the osteochondritis usually affects only one of the sesamoids and not both simultaneously. Julsrud [22] reported simultaneous osteonecrosis in a young woman treated with dual sesamoid excision and an interphalangeal joint fusion. Reported complications of sesamoid excision include drift of the hallux into either varus – after the resection of the lateral sesamoid – or valgus – after the resection of the medial sesamoid-, not complete pain relief and metatarsophalangeal joint stiffness [12,31]. The key factor to diminish the rate of complication (more than 50% in some series [12]) is probably to re-establish the normal relationship of the remaining conjoined tendon and capsule, thus restoring the off-loading mechanism of the first metatarsophalangeal joint. Some authors prefer a longitudinal plantar skin incision for the isolated excision of the fibular sesamoid [23,26].
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Mann and Coughlin [31] recommend a lateral–dorsal approach in the first inter-metatarsian space. The potential disadvantage of this approach is the technical demand [11,23] but it avoids the risk of a painful or hypertrophic plantar scar.
9. Conclusion Despite being an uncommon condition, osteochondritis of the sesamoids should be considered when pain and tenderness appear under the first metatarsophalangeal joint. When conservative treatment fails surgery will confirm the diagnosis and usually leads to a satisfactory outcome.
Acknowledgement We thank Cassandra Rosenblum for her help in the preparation and translation of this manuscript.
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