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Hallucal sesamoid injury
HALLUCAL SESAMOID INJURY DOUGLAS N. BEAMAN, MD and LILY J. NIGO, MS
The hallucal sesamoid complex is a unique anatomical structure, which can be responsible for significant athletic disability. The medial sesamoid is typically injured due to its position and size. Conditions presented in this paper include sesamoiditis, stress fracture, acute trauma, and nonunion. Surgical techniques applicable to medial sesamoid pathology are evolving, and those discussed include sesamoid excision, bone grafting for nonunions, and sesamoid complex reconstruction with partial sesamoidectomy for trauma. KEY WORDS: hallucal sesamoid injury
The cartilaginous; hallucal sesamoids develop within the tendinous insertional fibers of the flexor hallucis brevis (FHB) muscle during the early fetal stage; chondrification of undifferentiated mesenchymal tissue begins during the fourth month of fetal life. 1 Ossification will often occur from multiple centers that may or may not coalesce by the eighth year of life. Failure of fusion of the distinct centers will result in radiographic appearance of bipartite and multipartite sesamoids. The incidence of bipartite medial sesamoids, bipartite lateral sesamoids, and bilateral bipartism is 7% to 11%, <1%, and 25%, respectivelyJ,2 The sesamoid bones are boat shaped, and the superior surface is smooth, nearly flat, and covered with hyaline cartilage. The inferior surface is concave and completely embedded within the tendinous fibers of the FHB muscle. The medial and lateral sesamoids are firmly bound together by the intersesamoid ligament, underneath which glides the flexor hadlucis longus (FHL) tendon. The medial sesamoid averages 13.5 mm in length and 10 mm in width. The lateral sesamoid averages 9 mm in length and 8 mm in width. 2 The sesamoids articulate with similar, congruent sulci on the inferior and anterior aspects of the metatarsal head. These sulci are concave underneath the first metatarsal head and separated by an osseocartilaginous ridge. The depth of these sulci decreases distally as the articulation changes to the regiLon of metatarsophalangeal contact. The sesamoids are restrained by their strong ligamentous attachments to the metatarsal head, the insertional fibers of the adductor and abductor hallucis muscles, and the intermetatarsal ligament between the lateral sesamoid and the plantar plate of the second metatarsophalangeal joint, completing the sesamoid complex (Fig 1).
FUNCTION The sesamoids have been identified as serving multiple roles including (1) protecting the FHL tendon and first
From the Portland Orthopedic Clinic and Medical Specialty Solutions, Portland, OR. Address reprint requests to Douglas N. Beaman, MD, Portland Orthopedic Clinic, PC, P.O. Box 23200, Portland, OR 97281. Copyright © 1999 by W.B. Saunders Company 1060-1872/99/0701-0002510.00/0
metatarsal head, (2) distributing load transmission to the medial forefoot, and (3) working as a pulley mechanism to increase the strength of the flexor hallucis longus and brevis. The effective tendon moment arm (ETMA) of the FHB was measured in simulated cadaveric studies, s,4 The mechanical advantage of the FHB muscle was significantly diminished by excision of both sesamoids (maximal decrease in ETMA of 29%). A similar study was conducted to evaluate the effects of selective sesamoid resections on the ETMA of the FHL. Significant decreases in the FHL moment arm occurred when the medial sesamoid alone was excised (approximately 10%), when the lateral sesamoid alone was excised (approximately 16%), and when both the medial and lateral sesamoids were excised (approximately 30%). These studies revealed the importance of the FHL as the principal flexor of the first metatarsophalangeal joint.
CLINICAL EVALUATION The patient with sesamoid pathology will describe symptoms of tenderness and localized pain under the first metatarsal head with weightbearing. Activities such as stair climbing and sports tend to increase pain. Occasionally, patients describe the onset of symptoms with acute trauma, but often they cannot recall a particular event leading to symptoms. On examination, the patient with an intrinsic sesamoid injury will have tenderness to direct palpation beneath the metatarsal head. Maximum tenderness may be under the respective sesamoid bone. The exact diagnosis, however, often cannot be made reliably based on palpation alone, because of the close anatomic proximity of the sesamoids and the FHL tendon. Painful restriction of metatarsophalangeal joint (MTP) motion is often associated with sesamoid pathology. Tenosynovitis of the FHL tendon must be considered in the differential diagnosis for tenderness beneath the first metatarsal. The tenderness associated with localized tenosynovitis will be exacerbated by resisted plantarflexion of the hallucal interphalangeal joint. This condition may best be shown by having the patient stand with the hallux extended over an edge while flexing the toe against resistance. Radiographic studies that are useful in the evaluation of
Operative Techniques in Sports Medicine, Vol 7, No 1 (January), 1999: pp 7-13
7
Proximal
Sesamoids,
~
Medial metatarsophalangeallig. Medial metatarsosesamoidlig.
~ Adductorhallucism.,Z~---J~, transverse and obliqueheads
~
Intersesamoid lig. " ~ - Tendinous slipsto sesamoid from abductorhallucis m.
Fig 1. Plantar aspect of the anatomy of the sesamoid complex.
Plantarplate Flexor hallucisbrevism., lateral and medialheads for hallucis m. haUucisIongus t. (cut)
sesamoid pathology include standing anteroposterior (AP), lateral axial sesamoid, and nonweightbearing oblique views. Oblique views help with fracture evaluation, and the axial views help identify arthrosis involving the metatarsosesamoid articulation. Small BBs can be taped to the skin at the point of maximum tenderness, to differentiate between problems related to the FHL tendon and those related to the sesamoid bones. The radiographic appearance of a fractured sesamoid includes sharp, jagged, irregular edges often with separation of the fragments. A bipartite sesamoid is characterized by smooth cortical edges and a slightly larger size than a nonpartitioned bone. Preinjury radiographs showing an intact sesamoid can confirm the diagnosis of a fracture. Additional diagnostic tools, such as bone scan, computed tomography (CT), and magnetic resonance imaging (MRI) may be useful to further evaluate the sesamoid complex. A bone scan with magnified views may help delineate the region of pathology when radiographs are normal. However, there is a considerable rate of false 8
positive results. CT can be used to evaluate fractures and nonunions, and to define the extent of arthrosis in the metatarsosesamoid articulation. MRI is helpful in the evaluation of sesamoid stress fractures, osteonecrosis, and infection.
SESAMOIDITIS Sesamoiditis is a clinical entity characterized by pain associated with either sesamoid, but primarily involving the medial sesamoid. There is usually a history of minor or repetitive trauma: Athletes with a cavus foot posture and associated first metatarsal depression may be prone to develop sesamoiditis. When making the diagnosis of sesamoiditis, it is important to rule out other conditions, such as isolated bursitis, flexor tendinosus, or chondromalacia, s-8 Radiographs are normal with sesamoiditis, but a bone scan may show increased uptake of the involved sesamoid. The early phases of osteochondritis or other sesamoid pathology can present as sesamoiditis; radioBEAMAN AND NIGO
graphs are normal until the more advanced stages of an osteochondritic condition. 5 Treatment of sesamoiditis is directed toward relieving the stresses across the sesamoid complex. This can be accomplished with a metatarsal pad, soft arch support, lowering of the heel height, and, occasionally, customfitted orthoses. 9 Shoe modifications include rocker sole and stiffening the sole, which can be accomplished with a flat, removable full-length carbon fiber or plastic insert. Taping the hallux in slight plantar flexion during sports can help alleviate pain. Cross-training is also helpful for athletes involved in impac~ sports, with an emphasis on nonimpact activity such as biking, swimming, and weighttraining. Athletic footwear, i.e., cleats, should be carefully evaluated for any source of sesamoidal pressure. 5 Nonsteroidal anti-inflammatory drugs (NSAIDs) or a local steroid injection can also be beneficial. The surgical treatment of recalcitrant sesamoiditis consists of excision of the involved bone.
STRESS FRACTURES The diagnosis of a sesamoid stress fracture is complicated by the occurrence of bipartition. Stress fractures typically involve the medial sesamoid. Patients present with activityrelated pain accompanied by marked tenderness over the involved bone. Pain is usually reproduced with MTP joint forced dorsiflexion. 1° Plain radiographs are often positive approximately 3 to 6 weeks after onset of symptoms. 11 Treatment consists of a shorbleg walking cast for approximately 4 to 6 weeks;, followed by the use of an orthosis or metatarsal pad. When symptoms persist for a minimum of 6 months with radiographic evidence of non-healing, surgical intervention may be considered. 11,12Bone grafting and excision have both provided satisfactory results. 1A2-16 In theory, bone grafting is preferable to excision because it does not diminish the FHL effective tendon moment arm, like excision does (Fig 2). 3'4
ACUTE TRAUMA Injury to the hallucal sesamoid complex may occur through a direct mechanism, such as a fall from height, crush injury, or sudden loading of the first metatarsophalangeal joint. 2,5,6
The medial sesamoid is more commonly injured than the lateral, because it is exposed to more forces because of its location, and, typically, the injurious force is valgus in nature. Hyperextension of the great toe is a common athletic injury, especially in football. The term "turf toe" refers to a spectrum of injury to the first metatarsophalangeal joint, of which a subset involve damage to the sesamoid complex. 17,18The extent of injury can involve the plantar capsule and ligaments, fracture through one or both sesamoids, or separation of a partite sesamoid, is Metatarsophalangeal joint instability may occur after a turf-toe injury, and can be assessed with a Lachman-type examination of the toe. Metatarsophalangeal joint dislocation is also associated with sesamoid complex disruptionJ 9 Various injury patterns occurring with dislocation have been reported, and include sesamoid fracture, plantar capsule avulsion with proximal migration of the sesamoids, and plantar capsule injury with intersesamoid ligament disruptionJ 9-21 Combinations of injury patterns may occur, and it may be useful to obtain comparison radiographs of the uninjured foot. Treatment of the injured sesamoid complex depends on the nature of the injury. When associated with metatarsophalangeal joint dislocation, sesamoid position should be carefully evaluated on postreduction radiographs. In most cases, the sesamoids spontaneously reduce with reduction of the dislocated joint. Immobilization after reduction should include approximately 3 weeks in a short-leg walking cast followed by use of a stiffened-sole shoe until symptoms subside. This treatment protocol is also appropriate for a sesamoid fracture without significant displacement. Fractures with several millimeters of displacement have been reported to heal with nonsurgical treatment. However, surgical treatment should be considered for those fractures with greater degrees of displacement. This may be accomplished with suture repair or partial sesamoidectomy (Fig 3). Treatment of an athletic injury to the plantar sesamoid complex depends on the severity of the injury. Injuries without sesamoid migration or disruption are typically treated nonsurgically, with joint protection until symptoms resolve. Injuries associated with sesamoid fracture with minimal displacement are also treated nonsurgically. Progressive displacement of a bipartite medial sesamoid has
Fig 2. (A) Lateral radiograph of medial sesamoid nonunion. (B) Union was achieved after autologous bone grafting. The lateral tomogram is useful to evaluate healing of a nonunion. HALLUCAL SESAMOID INJURY
9
Fig 3. (A) Anteroposterior radiograph after reduction of a first metatarsophalangeal joint dislocation with sesamoid complex proximal migration and fracture. (B) Postoperative radiograph. Open plantar plate repair with partial sesamoidectomies and realignment of the sesamoid complex was performed.
been reported, is This may occur acutely or during initial phases of healing, and can be shown with a stress dorsiflexion AP or lateral radiograph. In the high-performance athlete, early surgical repair of the significantly displaced fracture or diastasis of the partite sesamoid may be warranted. Plantar plate disruption with proximal migration of the sesamoid complex may occur with or without sesamoid fracture. The treatment of this injury scenario remains controversial but when associated with significant displacement, reattachment of the plantar plate may provide a more successful outcome. Late repair may be complicated by scarring and subsequent limitation of motion. In late cases, both nonsurgical care and medial sesamoid excision have provided satisfactory results} °
SURGICAL TECHNIQUES Medial Approach to the Sesamoid Complex The medial approach to the sesamoid complex (Fig 4) allows good visualization of medial sesamoid pathology, as well as visualization of the plantar plate attachment to the proximal phalanx. The incision is placed midline on the medial aspect of the hallux, centered at the level of the
10
metatarsophalangeal joint. The medial plantar nerve runs at the level of the superior aspect of the sesamoid, and should be identified and retracted (usually plantarly). The abductor hallucis tendon is identified as it inserts into the medial sesamoid and medial plantar tubercle of the proximal phalanx. The capsule and abductor tendon are incised on the dorsal aspect of the sesamoid, allowing the articular surface of the sesamoid to be examined. The flexor hallucis longus tendon courses laterally to the medial sesamoid. The flexor hallucis brevis attaches to the proximal, plantar aspect of the sesamoid, with a variable attachment to the abductor tendon. Distally, these structures blend into the plantar plate. 22
SESAMOID EXCISION Indications for medial sesamoid excision include recalcitrant sesamoiditis, nonunion with excessive motion or articular cartilage damage, degenerative joint disease, osteochondritis, and infection. 6 After exposure of the sesamoid, subperiosteal dissection is performed to enable complete excision. The flexor hallucis longus tendon is inspected after sesamoid removal. The defect in the flexor hallucis brevis is then closed with an absorbable suture, typically in a figure-eight or triangular pattern. PostoperaBEAMAN AND NIGO
Dorsal digital n. Sagittal hood
\ Fig 4. The medial anatomy of the first MTP joint and sesamoid complex, Flexor hallucis Iongus t. f
.....- - 7
Medial metatarsophalageal l i g . /
hallucis t.
Medial metatarsosesamoid lig./ Plantar digital n.
tive care includes ambulation in a postoperative shoe for 4 weeks. The dressing is changed weekly, holding the hallux in a neutral to slightly varus and plantarflexed position. A firm-sole shoe with medial arch support is then used, with initiation of motion exercises. Active range of motion is followed by passive motion as tolerated. Strengthening exercises are begun when satisfactory motion has been attained. The reported results after medial sesamoid excision are variable. In several studies, approximately 50% of patients had complete pain relief, 1,15,16 with most having at least partial relief of symptoms. Hallucal weakness has been reported in approximately one half of patients after single sesamoid excision, and, rarely, a hallux valgus deformity can occur after medial sesamoid excision. 15 Double sesamoid excision should be avoided, except in cases of
"~,\\
Medial sesamoid Flexor hallucis brevis t.
infection involving both bones, because the risk of a claw toe deformity. 9
MEDIAL SESAMOID BONE GRAFTING Autologous bone grafting is a reasonable alternative to sesamoid excision in certain cases of sesamoid nonunion. ~2 Stability at the nonunion site without significant displacement, and an intact articular surface are important factors to facilitate the success of this procedure. The bone is exposed as outlined previously, and the articular surface is carefully inspected. If significant cartilage damage is present, then either partial or complete excision is indicated. If the articular surface is intact, the medial aspect of the sesamoid is exposed subperiosteally, and the nonunion is identified, which is typically midline and transverse in
Abductorhallucis t.
I
Dorsal digital n.
Fig 5. The medial aspect of the sesamoid is exposed subperiosteally, Note proximity of the plantar digital nerve.
Plantar digital n./ Medial sesa~
Capsule
i :
HALLUCAL SESAMOID INJURY
! I
11
Plantar digital n. Abductor hallucis t.
Medial sesamoid
Fig 6. Using a small curette, the nonunion fibrous tissue is removed, avoiding the articular surface.
Transverse non-union Perio
cartilage
nature (Fig 5). A small curette is used to remove the n o n u n i o n fibrous tissue, avoiding the articular surface (Fig 6). Slight motion m a y be present, but if gross instability exists at the n o n u n i o n site, excision should be performed. Cancellous bone graft m a y be obtained locally through a small cortical w i n d o w in the medial eminence of the first metatarsal head. The n o n u n i o n is packed with graft, and the periosteal tissue is closed with absorbable suture. Postoperative care includes 4 weeks nonweightbearing, then 4 weeks weightbearing in a shortqeg cast, with the hallux immobilized. After 8 weeks, the rehabilitation program and shoewear is as outlined for sesamoid excision. Plain t o m o g r a p h y is helpful to assess healing, and m a y be performed after 8 weeks to direct further care and activity level. Anderson and McBryde 12have reported n o n u n i o n healing in 19 of 21 patients treated with this technique. Both recalcitrant nonunions occurred in patients with excessive motion at the n o n u n i o n site at the time of bone grafting. There was no demonstrable loss of push-off strength, and all but one patient w h o achieved union were able to return to their preinjury level of athletic participation.
position beneath the metatarsal head. Sutures are used to repair the proximal soft-tissue attachments to the distal capsule/plantar plate. Sutures m a y be placed through the proximal fragment if necessary. It is also possible to use suture anchors into either the proximal phalanx or the retained sesamoid, if it is of sufficient size. Postoperative care includes 6 weeks in a short-leg cast; nonweightbearing for 4 weeks followed by weightbearing as tolerated. Active hallucal metatarsophalangeal flexion is initiated at 4 weeks, and extension at 6 weeks. A stiff-sole shoe or carbon fiber insert is worn after cast removal. For sports, the hallux should be protected with taping to limit dorsiflexion for 4 to 6 months postoperatively. To date, there has not been a report of a significant n u m b e r of patients treated in this manner to document outcome.
PARTIAL MEDIAL SESAMOIDECTOMY
REFERENCES
This procedure is applicable in cases of diastasis of a bipartite medial sesamoid, 18 and of fracture of the sesamoid complex with wide separation of the fragments. A medial exposure is performed, and the sesamoid fragments are visualized. Typically, the proximal fragment has migrated proximally, and the distal fragment is often damaged. The distal fragment is excised subperiosteally, thus retaining the distal capsule and plantar plate complex. The proximal fragment is advanced to its appropriate 12
ACKNOWLEDGMENT The authors thank Robert B. Anderson, MD and Charles L. Saltzman, MD for the use of radiographs, and Susan E. Brust, MS, CMI for the illustrations.
1. Inge GAG Ferguson AB: Surgery of the sesamoid bones of the great toe: An anatomic and clinical study, with a report of forty-one cases. Arch Surg 27:466-489, 1933 2. Feldman F, Pochaczevsk R, Hecht H: The case of the wandering sesamoid and other sesamoid afflictions.Radiology96:275-283, 1970 3. Aper RL, Saltzman CL, Brown TD: The effect of hallux sesamoid resection on the effectivemoment of the flexor hallucis brevis. Foot Ankle Int 15:462-470, 1994 4. Aper RL, Saltzman CL, Brown TD: The effect of hallux sesamoid excision on the flexor hallucis longus moment arm. Clin Orthop 325:209-217, 1996 BEAMAN AND NIGO
5. Jahss MH: The sesamoids of the hallux. Clin Orthop 157:88-97, 1981 6. Coughlin MJ: Sesamoid pain: Causes and surgical treatment, in Greene WB (ed): Instructional Course Lectures, XXXIX. Park Ridge, IL, American Academy of Orthopaedic Surgeons, 1990, pp 23-35 7. Apley AG: Open sesamoid: A re-appraisal of the medial sesamoid of the hallux. Proc R Soc Med 59:120-121, 1966 8. Helal B: The great toe sesamoid bones: The lus or lost souls of Ushaia. Clin Orthop 157:82-87, 1981 9. Axe MJ, Ray RL: Ortlhotic treatment of sesamoid pain. Am J Sports Med 16:411-416, 1988 10. Van Hal ME, Keene JS, Lange TA, et at: Stress fractures of the great toe sesamoids. Am J Sports Med 10:122-128, 1982 11. McBryde AM Jr, Anderson RB: Sesamoid foot problems in the athlete. Clin Sports Med 7:51-60, 1988 12. Anderson RB, McBryde AM: Autogenous bone grafting of hallux sesamoid nonunion. Foot Ankle Int 18:293-296, 1997 13. Ilfeld FW, Rosen V: Osteochondritis of the first metatarsal sesamoid: Report of three cases. Clin Orthop 85:38-41, 1972 14. Kliman MG Gross AE, Pritzker KP, et al: Osteochondritis of the hallux sesamoid bones. Foot Ankle 3:220-223, 1983
HALLUCAL SESAMOID INJURY
15. Mann RA: Sesamoidectomy of the great toe. Foot Ankle 5:277, 1985 (abstr) 16. Brodsky JW: Sesamoid excision for chronic nonunion. Orthop Trans 16:26, 1992 17. Rodeo SA, O'Brien S, Warren RF, et al: Turf-toe: An analysis of metatarsophalangeal joint sprains in professional football players. Am J Sports Med 18:280-285, 1990 18. Rodeo SA, Warren RF, O'Brien SJ, et al: Diastasis of bipartite sesamoids of the first metatarsophalangeal joint. Foot Ankle [nt 14:425434, 1993 19. Jahss MH: Traumatic dislocations of the first metatarsophalangeal joint. Foot Ankle 1:15-21, 1980 20. Graves SC, Prieskorn D, Mann RA: Posttraumatic proximal migration of the first metatarsophalangeal joint sesamoids: A report of four cases. Foot Ankle 12:117-122, 1991 21. Capasso G, Maffulli N, Testa V: Rupture of the intersesamoid ligament of a soccer player's foot. Foot Ankle 10:337-339, 1990 22. Sarrafian SK: Anatomy of the Foot and Ankle: Descriptive, Topographical, Functional. Philadelphia, PA, JB Lippincott, 1983
13
The hallucal sesamoid complex is a unique anatomical structure, which can be responsible for significant athletic disability. The medial sesamoid is typically injured due to its position and size. Conditions presented in this paper include sesamoiditis, stress fracture, acute trauma, and nonunion. Surgical techniques applicable to medial sesamoid pathology are evolving, and those discussed include sesamoid excision, bone grafting for nonunions, and sesamoid complex reconstruction with partial sesamoidectomy for trauma. KEY WORDS: hallucal sesamoid injury
The cartilaginous; hallucal sesamoids develop within the tendinous insertional fibers of the flexor hallucis brevis (FHB) muscle during the early fetal stage; chondrification of undifferentiated mesenchymal tissue begins during the fourth month of fetal life. 1 Ossification will often occur from multiple centers that may or may not coalesce by the eighth year of life. Failure of fusion of the distinct centers will result in radiographic appearance of bipartite and multipartite sesamoids. The incidence of bipartite medial sesamoids, bipartite lateral sesamoids, and bilateral bipartism is 7% to 11%, <1%, and 25%, respectivelyJ,2 The sesamoid bones are boat shaped, and the superior surface is smooth, nearly flat, and covered with hyaline cartilage. The inferior surface is concave and completely embedded within the tendinous fibers of the FHB muscle. The medial and lateral sesamoids are firmly bound together by the intersesamoid ligament, underneath which glides the flexor hadlucis longus (FHL) tendon. The medial sesamoid averages 13.5 mm in length and 10 mm in width. The lateral sesamoid averages 9 mm in length and 8 mm in width. 2 The sesamoids articulate with similar, congruent sulci on the inferior and anterior aspects of the metatarsal head. These sulci are concave underneath the first metatarsal head and separated by an osseocartilaginous ridge. The depth of these sulci decreases distally as the articulation changes to the regiLon of metatarsophalangeal contact. The sesamoids are restrained by their strong ligamentous attachments to the metatarsal head, the insertional fibers of the adductor and abductor hallucis muscles, and the intermetatarsal ligament between the lateral sesamoid and the plantar plate of the second metatarsophalangeal joint, completing the sesamoid complex (Fig 1).
FUNCTION The sesamoids have been identified as serving multiple roles including (1) protecting the FHL tendon and first
From the Portland Orthopedic Clinic and Medical Specialty Solutions, Portland, OR. Address reprint requests to Douglas N. Beaman, MD, Portland Orthopedic Clinic, PC, P.O. Box 23200, Portland, OR 97281. Copyright © 1999 by W.B. Saunders Company 1060-1872/99/0701-0002510.00/0
metatarsal head, (2) distributing load transmission to the medial forefoot, and (3) working as a pulley mechanism to increase the strength of the flexor hallucis longus and brevis. The effective tendon moment arm (ETMA) of the FHB was measured in simulated cadaveric studies, s,4 The mechanical advantage of the FHB muscle was significantly diminished by excision of both sesamoids (maximal decrease in ETMA of 29%). A similar study was conducted to evaluate the effects of selective sesamoid resections on the ETMA of the FHL. Significant decreases in the FHL moment arm occurred when the medial sesamoid alone was excised (approximately 10%), when the lateral sesamoid alone was excised (approximately 16%), and when both the medial and lateral sesamoids were excised (approximately 30%). These studies revealed the importance of the FHL as the principal flexor of the first metatarsophalangeal joint.
CLINICAL EVALUATION The patient with sesamoid pathology will describe symptoms of tenderness and localized pain under the first metatarsal head with weightbearing. Activities such as stair climbing and sports tend to increase pain. Occasionally, patients describe the onset of symptoms with acute trauma, but often they cannot recall a particular event leading to symptoms. On examination, the patient with an intrinsic sesamoid injury will have tenderness to direct palpation beneath the metatarsal head. Maximum tenderness may be under the respective sesamoid bone. The exact diagnosis, however, often cannot be made reliably based on palpation alone, because of the close anatomic proximity of the sesamoids and the FHL tendon. Painful restriction of metatarsophalangeal joint (MTP) motion is often associated with sesamoid pathology. Tenosynovitis of the FHL tendon must be considered in the differential diagnosis for tenderness beneath the first metatarsal. The tenderness associated with localized tenosynovitis will be exacerbated by resisted plantarflexion of the hallucal interphalangeal joint. This condition may best be shown by having the patient stand with the hallux extended over an edge while flexing the toe against resistance. Radiographic studies that are useful in the evaluation of
Operative Techniques in Sports Medicine, Vol 7, No 1 (January), 1999: pp 7-13
7
Proximal
Sesamoids,
~
Medial metatarsophalangeallig. Medial metatarsosesamoidlig.
~ Adductorhallucism.,Z~---J~, transverse and obliqueheads
~
Intersesamoid lig. " ~ - Tendinous slipsto sesamoid from abductorhallucis m.
Fig 1. Plantar aspect of the anatomy of the sesamoid complex.
Plantarplate Flexor hallucisbrevism., lateral and medialheads for hallucis m. haUucisIongus t. (cut)
sesamoid pathology include standing anteroposterior (AP), lateral axial sesamoid, and nonweightbearing oblique views. Oblique views help with fracture evaluation, and the axial views help identify arthrosis involving the metatarsosesamoid articulation. Small BBs can be taped to the skin at the point of maximum tenderness, to differentiate between problems related to the FHL tendon and those related to the sesamoid bones. The radiographic appearance of a fractured sesamoid includes sharp, jagged, irregular edges often with separation of the fragments. A bipartite sesamoid is characterized by smooth cortical edges and a slightly larger size than a nonpartitioned bone. Preinjury radiographs showing an intact sesamoid can confirm the diagnosis of a fracture. Additional diagnostic tools, such as bone scan, computed tomography (CT), and magnetic resonance imaging (MRI) may be useful to further evaluate the sesamoid complex. A bone scan with magnified views may help delineate the region of pathology when radiographs are normal. However, there is a considerable rate of false 8
positive results. CT can be used to evaluate fractures and nonunions, and to define the extent of arthrosis in the metatarsosesamoid articulation. MRI is helpful in the evaluation of sesamoid stress fractures, osteonecrosis, and infection.
SESAMOIDITIS Sesamoiditis is a clinical entity characterized by pain associated with either sesamoid, but primarily involving the medial sesamoid. There is usually a history of minor or repetitive trauma: Athletes with a cavus foot posture and associated first metatarsal depression may be prone to develop sesamoiditis. When making the diagnosis of sesamoiditis, it is important to rule out other conditions, such as isolated bursitis, flexor tendinosus, or chondromalacia, s-8 Radiographs are normal with sesamoiditis, but a bone scan may show increased uptake of the involved sesamoid. The early phases of osteochondritis or other sesamoid pathology can present as sesamoiditis; radioBEAMAN AND NIGO
graphs are normal until the more advanced stages of an osteochondritic condition. 5 Treatment of sesamoiditis is directed toward relieving the stresses across the sesamoid complex. This can be accomplished with a metatarsal pad, soft arch support, lowering of the heel height, and, occasionally, customfitted orthoses. 9 Shoe modifications include rocker sole and stiffening the sole, which can be accomplished with a flat, removable full-length carbon fiber or plastic insert. Taping the hallux in slight plantar flexion during sports can help alleviate pain. Cross-training is also helpful for athletes involved in impac~ sports, with an emphasis on nonimpact activity such as biking, swimming, and weighttraining. Athletic footwear, i.e., cleats, should be carefully evaluated for any source of sesamoidal pressure. 5 Nonsteroidal anti-inflammatory drugs (NSAIDs) or a local steroid injection can also be beneficial. The surgical treatment of recalcitrant sesamoiditis consists of excision of the involved bone.
STRESS FRACTURES The diagnosis of a sesamoid stress fracture is complicated by the occurrence of bipartition. Stress fractures typically involve the medial sesamoid. Patients present with activityrelated pain accompanied by marked tenderness over the involved bone. Pain is usually reproduced with MTP joint forced dorsiflexion. 1° Plain radiographs are often positive approximately 3 to 6 weeks after onset of symptoms. 11 Treatment consists of a shorbleg walking cast for approximately 4 to 6 weeks;, followed by the use of an orthosis or metatarsal pad. When symptoms persist for a minimum of 6 months with radiographic evidence of non-healing, surgical intervention may be considered. 11,12Bone grafting and excision have both provided satisfactory results. 1A2-16 In theory, bone grafting is preferable to excision because it does not diminish the FHL effective tendon moment arm, like excision does (Fig 2). 3'4
ACUTE TRAUMA Injury to the hallucal sesamoid complex may occur through a direct mechanism, such as a fall from height, crush injury, or sudden loading of the first metatarsophalangeal joint. 2,5,6
The medial sesamoid is more commonly injured than the lateral, because it is exposed to more forces because of its location, and, typically, the injurious force is valgus in nature. Hyperextension of the great toe is a common athletic injury, especially in football. The term "turf toe" refers to a spectrum of injury to the first metatarsophalangeal joint, of which a subset involve damage to the sesamoid complex. 17,18The extent of injury can involve the plantar capsule and ligaments, fracture through one or both sesamoids, or separation of a partite sesamoid, is Metatarsophalangeal joint instability may occur after a turf-toe injury, and can be assessed with a Lachman-type examination of the toe. Metatarsophalangeal joint dislocation is also associated with sesamoid complex disruptionJ 9 Various injury patterns occurring with dislocation have been reported, and include sesamoid fracture, plantar capsule avulsion with proximal migration of the sesamoids, and plantar capsule injury with intersesamoid ligament disruptionJ 9-21 Combinations of injury patterns may occur, and it may be useful to obtain comparison radiographs of the uninjured foot. Treatment of the injured sesamoid complex depends on the nature of the injury. When associated with metatarsophalangeal joint dislocation, sesamoid position should be carefully evaluated on postreduction radiographs. In most cases, the sesamoids spontaneously reduce with reduction of the dislocated joint. Immobilization after reduction should include approximately 3 weeks in a short-leg walking cast followed by use of a stiffened-sole shoe until symptoms subside. This treatment protocol is also appropriate for a sesamoid fracture without significant displacement. Fractures with several millimeters of displacement have been reported to heal with nonsurgical treatment. However, surgical treatment should be considered for those fractures with greater degrees of displacement. This may be accomplished with suture repair or partial sesamoidectomy (Fig 3). Treatment of an athletic injury to the plantar sesamoid complex depends on the severity of the injury. Injuries without sesamoid migration or disruption are typically treated nonsurgically, with joint protection until symptoms resolve. Injuries associated with sesamoid fracture with minimal displacement are also treated nonsurgically. Progressive displacement of a bipartite medial sesamoid has
Fig 2. (A) Lateral radiograph of medial sesamoid nonunion. (B) Union was achieved after autologous bone grafting. The lateral tomogram is useful to evaluate healing of a nonunion. HALLUCAL SESAMOID INJURY
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Fig 3. (A) Anteroposterior radiograph after reduction of a first metatarsophalangeal joint dislocation with sesamoid complex proximal migration and fracture. (B) Postoperative radiograph. Open plantar plate repair with partial sesamoidectomies and realignment of the sesamoid complex was performed.
been reported, is This may occur acutely or during initial phases of healing, and can be shown with a stress dorsiflexion AP or lateral radiograph. In the high-performance athlete, early surgical repair of the significantly displaced fracture or diastasis of the partite sesamoid may be warranted. Plantar plate disruption with proximal migration of the sesamoid complex may occur with or without sesamoid fracture. The treatment of this injury scenario remains controversial but when associated with significant displacement, reattachment of the plantar plate may provide a more successful outcome. Late repair may be complicated by scarring and subsequent limitation of motion. In late cases, both nonsurgical care and medial sesamoid excision have provided satisfactory results} °
SURGICAL TECHNIQUES Medial Approach to the Sesamoid Complex The medial approach to the sesamoid complex (Fig 4) allows good visualization of medial sesamoid pathology, as well as visualization of the plantar plate attachment to the proximal phalanx. The incision is placed midline on the medial aspect of the hallux, centered at the level of the
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metatarsophalangeal joint. The medial plantar nerve runs at the level of the superior aspect of the sesamoid, and should be identified and retracted (usually plantarly). The abductor hallucis tendon is identified as it inserts into the medial sesamoid and medial plantar tubercle of the proximal phalanx. The capsule and abductor tendon are incised on the dorsal aspect of the sesamoid, allowing the articular surface of the sesamoid to be examined. The flexor hallucis longus tendon courses laterally to the medial sesamoid. The flexor hallucis brevis attaches to the proximal, plantar aspect of the sesamoid, with a variable attachment to the abductor tendon. Distally, these structures blend into the plantar plate. 22
SESAMOID EXCISION Indications for medial sesamoid excision include recalcitrant sesamoiditis, nonunion with excessive motion or articular cartilage damage, degenerative joint disease, osteochondritis, and infection. 6 After exposure of the sesamoid, subperiosteal dissection is performed to enable complete excision. The flexor hallucis longus tendon is inspected after sesamoid removal. The defect in the flexor hallucis brevis is then closed with an absorbable suture, typically in a figure-eight or triangular pattern. PostoperaBEAMAN AND NIGO
Dorsal digital n. Sagittal hood
\ Fig 4. The medial anatomy of the first MTP joint and sesamoid complex, Flexor hallucis Iongus t. f
.....- - 7
Medial metatarsophalageal l i g . /
hallucis t.
Medial metatarsosesamoid lig./ Plantar digital n.
tive care includes ambulation in a postoperative shoe for 4 weeks. The dressing is changed weekly, holding the hallux in a neutral to slightly varus and plantarflexed position. A firm-sole shoe with medial arch support is then used, with initiation of motion exercises. Active range of motion is followed by passive motion as tolerated. Strengthening exercises are begun when satisfactory motion has been attained. The reported results after medial sesamoid excision are variable. In several studies, approximately 50% of patients had complete pain relief, 1,15,16 with most having at least partial relief of symptoms. Hallucal weakness has been reported in approximately one half of patients after single sesamoid excision, and, rarely, a hallux valgus deformity can occur after medial sesamoid excision. 15 Double sesamoid excision should be avoided, except in cases of
"~,\\
Medial sesamoid Flexor hallucis brevis t.
infection involving both bones, because the risk of a claw toe deformity. 9
MEDIAL SESAMOID BONE GRAFTING Autologous bone grafting is a reasonable alternative to sesamoid excision in certain cases of sesamoid nonunion. ~2 Stability at the nonunion site without significant displacement, and an intact articular surface are important factors to facilitate the success of this procedure. The bone is exposed as outlined previously, and the articular surface is carefully inspected. If significant cartilage damage is present, then either partial or complete excision is indicated. If the articular surface is intact, the medial aspect of the sesamoid is exposed subperiosteally, and the nonunion is identified, which is typically midline and transverse in
Abductorhallucis t.
I
Dorsal digital n.
Fig 5. The medial aspect of the sesamoid is exposed subperiosteally, Note proximity of the plantar digital nerve.
Plantar digital n./ Medial sesa~
Capsule
i :
HALLUCAL SESAMOID INJURY
! I
11
Plantar digital n. Abductor hallucis t.
Medial sesamoid
Fig 6. Using a small curette, the nonunion fibrous tissue is removed, avoiding the articular surface.
Transverse non-union Perio
cartilage
nature (Fig 5). A small curette is used to remove the n o n u n i o n fibrous tissue, avoiding the articular surface (Fig 6). Slight motion m a y be present, but if gross instability exists at the n o n u n i o n site, excision should be performed. Cancellous bone graft m a y be obtained locally through a small cortical w i n d o w in the medial eminence of the first metatarsal head. The n o n u n i o n is packed with graft, and the periosteal tissue is closed with absorbable suture. Postoperative care includes 4 weeks nonweightbearing, then 4 weeks weightbearing in a shortqeg cast, with the hallux immobilized. After 8 weeks, the rehabilitation program and shoewear is as outlined for sesamoid excision. Plain t o m o g r a p h y is helpful to assess healing, and m a y be performed after 8 weeks to direct further care and activity level. Anderson and McBryde 12have reported n o n u n i o n healing in 19 of 21 patients treated with this technique. Both recalcitrant nonunions occurred in patients with excessive motion at the n o n u n i o n site at the time of bone grafting. There was no demonstrable loss of push-off strength, and all but one patient w h o achieved union were able to return to their preinjury level of athletic participation.
position beneath the metatarsal head. Sutures are used to repair the proximal soft-tissue attachments to the distal capsule/plantar plate. Sutures m a y be placed through the proximal fragment if necessary. It is also possible to use suture anchors into either the proximal phalanx or the retained sesamoid, if it is of sufficient size. Postoperative care includes 6 weeks in a short-leg cast; nonweightbearing for 4 weeks followed by weightbearing as tolerated. Active hallucal metatarsophalangeal flexion is initiated at 4 weeks, and extension at 6 weeks. A stiff-sole shoe or carbon fiber insert is worn after cast removal. For sports, the hallux should be protected with taping to limit dorsiflexion for 4 to 6 months postoperatively. To date, there has not been a report of a significant n u m b e r of patients treated in this manner to document outcome.
PARTIAL MEDIAL SESAMOIDECTOMY
REFERENCES
This procedure is applicable in cases of diastasis of a bipartite medial sesamoid, 18 and of fracture of the sesamoid complex with wide separation of the fragments. A medial exposure is performed, and the sesamoid fragments are visualized. Typically, the proximal fragment has migrated proximally, and the distal fragment is often damaged. The distal fragment is excised subperiosteally, thus retaining the distal capsule and plantar plate complex. The proximal fragment is advanced to its appropriate 12
ACKNOWLEDGMENT The authors thank Robert B. Anderson, MD and Charles L. Saltzman, MD for the use of radiographs, and Susan E. Brust, MS, CMI for the illustrations.
1. Inge GAG Ferguson AB: Surgery of the sesamoid bones of the great toe: An anatomic and clinical study, with a report of forty-one cases. Arch Surg 27:466-489, 1933 2. Feldman F, Pochaczevsk R, Hecht H: The case of the wandering sesamoid and other sesamoid afflictions.Radiology96:275-283, 1970 3. Aper RL, Saltzman CL, Brown TD: The effect of hallux sesamoid resection on the effectivemoment of the flexor hallucis brevis. Foot Ankle Int 15:462-470, 1994 4. Aper RL, Saltzman CL, Brown TD: The effect of hallux sesamoid excision on the flexor hallucis longus moment arm. Clin Orthop 325:209-217, 1996 BEAMAN AND NIGO
5. Jahss MH: The sesamoids of the hallux. Clin Orthop 157:88-97, 1981 6. Coughlin MJ: Sesamoid pain: Causes and surgical treatment, in Greene WB (ed): Instructional Course Lectures, XXXIX. Park Ridge, IL, American Academy of Orthopaedic Surgeons, 1990, pp 23-35 7. Apley AG: Open sesamoid: A re-appraisal of the medial sesamoid of the hallux. Proc R Soc Med 59:120-121, 1966 8. Helal B: The great toe sesamoid bones: The lus or lost souls of Ushaia. Clin Orthop 157:82-87, 1981 9. Axe MJ, Ray RL: Ortlhotic treatment of sesamoid pain. Am J Sports Med 16:411-416, 1988 10. Van Hal ME, Keene JS, Lange TA, et at: Stress fractures of the great toe sesamoids. Am J Sports Med 10:122-128, 1982 11. McBryde AM Jr, Anderson RB: Sesamoid foot problems in the athlete. Clin Sports Med 7:51-60, 1988 12. Anderson RB, McBryde AM: Autogenous bone grafting of hallux sesamoid nonunion. Foot Ankle Int 18:293-296, 1997 13. Ilfeld FW, Rosen V: Osteochondritis of the first metatarsal sesamoid: Report of three cases. Clin Orthop 85:38-41, 1972 14. Kliman MG Gross AE, Pritzker KP, et al: Osteochondritis of the hallux sesamoid bones. Foot Ankle 3:220-223, 1983
HALLUCAL SESAMOID INJURY
15. Mann RA: Sesamoidectomy of the great toe. Foot Ankle 5:277, 1985 (abstr) 16. Brodsky JW: Sesamoid excision for chronic nonunion. Orthop Trans 16:26, 1992 17. Rodeo SA, O'Brien S, Warren RF, et al: Turf-toe: An analysis of metatarsophalangeal joint sprains in professional football players. Am J Sports Med 18:280-285, 1990 18. Rodeo SA, Warren RF, O'Brien SJ, et al: Diastasis of bipartite sesamoids of the first metatarsophalangeal joint. Foot Ankle [nt 14:425434, 1993 19. Jahss MH: Traumatic dislocations of the first metatarsophalangeal joint. Foot Ankle 1:15-21, 1980 20. Graves SC, Prieskorn D, Mann RA: Posttraumatic proximal migration of the first metatarsophalangeal joint sesamoids: A report of four cases. Foot Ankle 12:117-122, 1991 21. Capasso G, Maffulli N, Testa V: Rupture of the intersesamoid ligament of a soccer player's foot. Foot Ankle 10:337-339, 1990 22. Sarrafian SK: Anatomy of the Foot and Ankle: Descriptive, Topographical, Functional. Philadelphia, PA, JB Lippincott, 1983
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