CHAPTER 33 SESAMOID BONES OF TFIE, FIRST METATARSAL: A Literature Review

Micbael Auakian Michael Seiberg, D.PM. Micbael Lemm, DPM. Donald Green, DPM.

The metatarsal sesamoids of the great toe can be Embryological dissections later revealed that the responsible for situations of formidable diagnostic sesamoids are recognizable as islands of connec- and treatment challenge. Due to small size and lim- tive tissue in their normal position under the first ited visualization of these ossicles on routine foot metatarsal head by the eighth week of fetal life. At radiographs, clinicians may ignore them and dis- ten weeks, this connective tissue becomes a pre- count their etiologic significance. However, there is cafiilaginous mass that eventually shows a definite increasing interest for high impact recreational chondrification center. According to Helal,3 and sports activities in the general popuiation. Placentini offered the first anatomic description of Consequently a higher incidence of traumatic the sesamoid bones in 7656. The same author also sesamoid disorders is being seen. In addition, there states that Bizzaro believed sesamoids exist as a is greater awareness of the anatomic, embryologic, result of both phylogeny and ftrnction, and they are pathologic, and biomechanical implications of the not residual tarsal bones. They were thought to be hallucal sesamoids. The understanding of both persistent structures in mammals. traumatic and non-traumatic conditions of these sesamoids has gained new ground. EMBRYOLOGY The purpose of this paper is to review the his- torical accounts, describe the anatomy, embryology, Although chondrification of the sesamoids begins biomechanics, and pathology of the ossa sesamoidea in the 12th u.eek of fetal life, ossification does not halluces, and discuss clinical presentations, and diag- commence until the Bth year, with completion by nostic and treatment modalities of various the 12th year.'Jahss states that ossification of the conditions associated with the hallucal sesamoids. hallucal sesamoids is variable and they usually ossify at age 11 in boys, and earlier in girls.a In his HISTORY update, Laventen5 states that sesamoids ossify at age B in girls and at age 72 in boys. Helal3 finds The sesamoids were named by the anatomist ossification in boys to occur al age 10. Variation in Galen, circa 180 A.D.,because they resembled the the pattern of ossification is also common.' seeds of the herb "sesamum indicum".' Later, Rabbi There are multiple ossification centers, and Uschaia described the tibial sesamoid as "luz", these may or may not coalesce.6 Bipartite, tripartite, representing an indestructible seecl from which the quadripartite, or multipartite sesamoids may be body would be resurrected on the Day of present in the adult. The incidence of bipartite Judgement. For centuries, Uschaia's parable was sesamoids is reported in significant variations. The an accepted explanation for the existence of percentages of bipartite sesamoids range from the sesamoids. 70,70/o to 34.0/0, according to Scranton.6 One author In the beginning of the eighteenth century, reported one bipartite sesamoid in 1000 radi- Nesbitt of London demonstrated that the ossifica- ographed feet. Jahss states that a bipartite sesamoid tion centers of the sesamoids are present beneath is present in approximately 700/o of individuals, and the first metatarsal head by the 12th fetal week.,,3 that most of these occur in the tibial sesamoid. 164 CHAPTER 33

Pafiition of the tibial sesamoid is believed to be constantly occurring and develop within the cap- about ten times more frequent than partition of the sule of the first metatarsophalangeal joint by fibular sesamoid.t Partition of the sesamoids gener- intracartilaginous bone formation." ally occurs slightly more frequently in women then In addition to the four bones mentioned in men.' Bilateral occurrence of this anomaly has above, sk tendons and seven ligaments also con- also been reported with significant variability; the tribute to the first metatarsophalangeal joint. The frequencies range from 73.50/o lo B5o/0.'l only unpaired ligament, the deep transverse liga- The etiology of sesamoid pafiition is ment, also known as the intersesamoid ligament, is unknown. Jahss? states that pafiition is the result of located between the sesamoids'David et a1.'1 made a failure of fusion of the mr-rltiple centers of ossifi- transverse and sagittal sections of six cadaveric cation. One theory, as mentioned by Sobel et a1.,8 specimens of feet to study the anatomical complex views vascular disturbance at or before sesamoid of the first metatarsophalangeal joint. They found ossification as the cause of sesamoid partition. The the stfticture of the intersesamoid ligament to authors present previous observations that lines of resemble the trilateral arrangement of a girder, com- ossification are significantly influenced by the posed of an upper wing and rwo plantar wings, one position of blood vessels. In light of the obserwa- medial and one lateral. It was also obserued that tions presented above, these researchers conducted there is no symmetry in relation to the dorsoplantar a histologic examination of two specimens with plane passing belween the sesamoids in the axis of bipartite sesamoids. \[hen the findings were the dorsal wing of the ligament. The upper wing, compared to the results of non-partitioned ses- located opposite the sagittal ridge of the metatarsal amoids, they noticed striking differences between head, is the shortest and thickest of the three. The the vascular anatomy of non-partitioned and plantar wings, stated the authors, seem to suppofi bipartite sesamoids. the inferior aspects of the sesamoid bones and to Saxby et al.,e reported on an occurrence of a separate them from the tendon of the flexor hai- bilateral coalition of the hallucal sesamoids in a Iuces longus muscle. On the basis of the authors' 1!-year-old college student. On a dorsoplantar anatomical findings, the intersesamoid ligament acts radiograph, one heart-shaped sesamoid bone was as an axis of cohesion. Between the three wings seen. JahssT states that there has been a report of a defined previously, there are three distinct spaces. congenital absence of the tibial sesamoids associ- The sesamoid bones are lodged in the upper ated with secondary clawing, due to inadequate spaces, while the plantar space forms a groove for function of the flexor halluces brevis muscle. the flexor halluces longus tendon. Agenesis and hypogenesis has also been seen with Medial and lateral sesamophalangeal liga- litt1e to no clinical significance. ments, extending from respective sesamoids to the inferior aspect of the base of the proximal phalanx, ANATOMY are the first of the paired ligaments of the first metatarsophalangeal joint. In this category are also The first metatarsophalangeal joint involves two a par of collateral ligaments, strong rounded cords, different afiicular surfaces, the large distal and dor- each attached to a respective epicondyle on the side sal regions where the proximal phalanx articulates, of the head of the metatarsal bone and extending and the plantar facets where the sesamoid bones forward and downward to reach the corresponding articulate.10. The plantar facets of the first metatarsal side of the base of the proximal phalanx. The third head are separated by a bony riclge callecl the set of paired ligaments is represented by the sus- crista. Thus, the medial and lateral sesamoids are pensory or metatarsoglenoid ligaments. also separated by this ridge. The lateral plantar According to \7ei1 and Hill,'this ligament was facet is angulated inward and upward. It becomes described by Sarrafian as a fan-shaped structure more transversely oriented with dorsiflexion of the that has fibers descending vertically in the posterior first metatarsophalangeal joint as in propulsion. part, and obliquely in the anterior pafi", lhat even- The tibial sesamoid is generally larger than the tually insert on the plantar plate. The significance fibular sesamoid, and is located distal to the fibular of these and the collateral ligaments seems to be sesamoid." The tibial sesamoid is generally more stabilization of the metatarsophalangeal ioint in the elliptical than the fibular sesamoid. Both bones are transverse plane. CHAPTER 33 t65

LaPortal2 states that the ligaments associated with tinues distally to inseft on the lateral aspect of the the sesamoids collectively form a triang:ular mass base of the proximal phalanx. that assists in retaining the sesamoids in their func- Medially, the abductor halluces muscle arises tionally proper locations at the plantar aspect of the from the medial process of the tuberosity of the cal- first metatarsal. He further describes a fibrccartilagi- caneus, the flexor retinaculum, and the plantar nous pad plantarly as a thickening of the plantar aponeurosis. It courses distally along the longitudi- aspect of the joint capsule. Also presented is the fact nal arch and narrows into a tendon which sends its that the plantar aponeurosis sends strong fibrous inferior lateral fibers to unite with the fibers of the slips that pass pafiially into the tibial and fibular medial head of the flexor halluces brevis muscle. It sesamoids. These slips and the previously men- insefis on the tibial sesamoid, as well as on the tioned ligaments form a tunnel through which the medial plantar tubercle of the proximal phalanx of tendon of the flexor halluces longus muscle extends the hallux. The superomedial fibers of the tendon to its inseftion on the distal phalanx of the hallux. blend with the extensor aponeurosis.'3 The flexor There are several extrinsic and intrinsic mus- halluces brevis is made up of lwo separate muscle cles that influence the first metatarsophalangeal bellies and tendons. One is iocated medially, the joint. On the dorsal aspect of the foot, the extensor other laterally. Each arises from the first metatarsal halluces longus and the extensor halluces brevis and first cuneiform, and each inserts in the plantar cross this joint. The extensor hood or expansion aspect of their respective sesamoids. The tendons fibers run transversely perpendicular to the extensor continue on to insert into the plantar-most aspect tendons at the level of the first metatarsophalangeal of the proximal phalanx on their respective sides. joint. These fibers do connect the extensor tendons The flexor halluces longus is an extrinsic mus- with the sesamoids and the first metatarsal neck. cle whose tendon passes on the plantar surface of On the plantar aspect there are muscles of greater the intersesamoidal ligament belween the rwo influence, the flexor halluces longus, the flexor hal- sesamoid bones, and inserts into the plantar base luces brevis with its two heads, the abductor of the distal phalanx. This muscle does not have halluces, and the adductor halluces with its two attachments to the sesamoid bones and, therefore, heads forming a conjoined tendon. The adductor cannot be considered a sesamoid muscle. halluces muscle has two separate muscle bellies, a large oblique head and a small transverse head. As THE VASCI.]IAR SUPPLY stated by Weil and Hill' the oblique head arises from the bases of the second, third and fourth The arteial supply of the sesamoid bones of the metatarsals, and the sheath of the peroneus longus hallux has been investigated by several researchers. and divides into three components. The medial slip In one study by Pretterklieber and wanivenhaus,'a blends with the flexor halluces brevis and insefts the arterial supply of the hallux sesamoids was on the lateral sesamoid. The central slip, which is investigated in 29 human feet with anatomical dis- the deepest, attaches to the inferior portion of the section. Eight of these feet were subjected to lateral sesamoid. The lateral component inserts on radiographic analysis prior to dissection. These the lateral sesamoid and the plantar lateral aspect investigators found that sesamoid arteries branch- of the base of the proximal phalanx. The oblique off from the digital plantar arteries of the hallux, head then extends in a medial and oblique direc- which in turn are derived from the medial plantar tion and blends with the lateral aspect of the flexor afiery and the plantar arch (type A), the plantar halluces brevis muscle. arch (type B), or the medial plantar afiery (type C). The transverse head of the adductor, however, The respective frequencies of types A, B, or C were which is also known as the adductor transversus 520/o, 240/0, and 240/0. It was further obserwed that muscle, forms a conjoined tendon with the oblique the number of sesamoid arteries varied from one head, originates from the plantar metatarsopha- (55o/o) to three (70o/o), and that the number langeal ligaments 2 through 5, and transverse increased with the size of the sesamoid. metatarsal ligament and runs transversely to blend An earlier study of the dimensions and the with the oblique head. In turn, the conjoined ten- arterial supply of the sesamoids of the hallux by don, along with the flexor halluces brevis tendon, Pretterklieber'5 showed that 530/0 of the medial and partially inserts into the lateral sesamoid, then con- 580/o of the lateral sesamoid bones were supplied I66 CHAPTER 33 by a single afiery G 60o/o of total). Twenty-six The sesamoid bones also act as shock percent of the medial and 32o/o of the lateral absorbers for the first metatarsal. There is indepen- sesamoids received two afieries (= 300/o of total). In dent range of motion of the first ray with the left feet only, three sesamoid arteries were found to metatarsal being elevated in swing and early stance supply 110/o of the medial and 70o/o of the lateral phases of gait. During stance, the first metatarsal sesamoid bones (= 70o/o of total). The number of plantarflexes and becomes increasingly weighrbear- sesamoid arteries corresponded to the "dimensions ing on into propulsion, as weight is shifted from the and compactness (robusticity)" of the sesamoids Tateral surface of the foot medially. Due to their and to other parameters, such as sex, predominant anatomical positions, the sesamoids and the inter- functional foot or "footedness ," and the anthropo- metatarsal ligament also protect the flexor halluces metric dimensions of the individuals. longus as it passes beneath the first metatarsal head. Sobel et al.,' present another view of the David et al.,11 in consideration of the anatom- microvasculature of the hallucal sesamoids. They ical and functional correlations of the sesamoid found that the fibular and tibial sesamoids are apparatus, divided the biomechanical function of equally vascularized. The major supply appeared to the first metatarsophalangeal-sesamoid joint into come from the first plantar metatarsal afiery, which four stages: suspension, fixation, coordination, and divides into medial and lateral branches. These, in propulsion. These stages are all interdependent of turn, supply the proximal and plantar poftions of each other. According to these researchers, the hor- the sesamoids. izontal position of the sesamoids places them in the Distally, the blood vessels enter the sesamoids most favorable situation for development of a cata- through the distal synovial and capsular attachment, pult effect, where they play the role of the sling. but provide minimal vasculature to the sesamoid. It The suspension stage begins with heel strike was also found that the lateral attachments of the and ends when the metatarsals come in contact sesamoids to the plantar plate and the joint capsule with the ground, as the foot plantarflexes at the were relatively avascular. The authors further sug- ankle. In this period, the sesamoid apparatus, via gested that injury to the proximal or plantar aspects the sesamoid muscles, acts like the collar of a har- of the sesamoids could disrupt the vascular supply ness passed around the first metatarsal by of these bones. If the injury occurs prior to ossifica- coordinating its forefoot contact with that of the tion, this could lead to partite sesamoids. four lesser metatarsals." This is consistent with Root's description of a dorsiflexed first ray at heel BIOMECTIAN]-ICS contact until the forefoot contacts the ground. The "stage of fixation" is characterized by the Recently, there has been more literature regarding fixed position of the sesamoids, whereby the the function of the sesamoids and their impofiance sesamoid apparatus becomes the reference struc- for first metatarsoph alangeal joint biomechanics. 2' 1 1' 16-1e ture around which the later stages will be Root et al.'o described this joint as movement in two organized. As the sesamoid anchorage is achieved, separate planes, transverse and sagittal. Each of the flexor halluces brevis, adductor halluces, and these planes has its own axis. Normally, there is no abductor halluces muscles act by isometric contrac- action in this joint in the frontal plane. The range tion to produce a plantarflexion action opposed to of motion in the transverse plane is very small, and the resistance of the ground. has little importance during gait. In the sagittal Heel-off marks the beginning of the "coordi- plane, the first metatarsophalangeal joint has a sig- nation stage." Having the sesamoids "fixed" to the nificant amount of motion and functions as a ground allows the adductor halluces muscles to ginglymoarthrodial- type j oint. redirect part of the forces transmitted by the dorsi- The sesamoid bones play a significant role in flexed foot to the lateral rays. During this stage, the muscle coordination and in the overall dynamics of first ray is progressively loading. The first metatarsal this joint. \When the first metatarsal plantarflexes head glides posteriorly upon the sesamoids. The during the propulsive phase of gait, the sesamoids arthrodial type of joint motion is seen with the act as a pulley to increase the mechanical advan- shifting of the transverse axis of the first metatar- tage of the flexor halluces brevis muscle.'6 This sophalangeal joint. As the metatarsophalangeal joint muscle, in turn, will stabilize the hallux in the sagit- is extended, the sesamoid-metatarsal complex tal plane against the ground reactive force. rotates, placing the joint in good position for catapult CI]APTER 33 167 action. The sesamoids are placed in the same trans- Nayfa and Sorto believe that "mechanically verse plane, and the flexor halluces longus tendon induced acute or chronic sesamoiditis and plantar is placed under tension.ll keratoma under the tibial sesamoid are most often The mechanical constraints were thus anteri- secondary to limited range of first ray dorsiflexion. orly redirected forming a structure in the shape of They state lhat "a plantarflexed first ray, whether a catapuh that will project the metatarsal head for- congenital or acquired, causes trauma to the tibial ward. The sesamord apparatus forms the sling and sesamoid," and that "sesamoiditis is the most com- the flexor halluces longus acts as the stretcher. mon initial symptom of a plantarflexed first During the propulsion stage, the catapult mecha- metatarsal."" Dennis and McKinney" observed that nism will go into action and the metatarsal head trauma associated with sesamoiditis is most will be projected upward and forward. The great commonly caused by jumping from a height, toe will flex by the tension of the flexor halluces excessive dancing, high-heeled shoes, or an abnor- longus tendon, and the propulsive forces will be mally large sesamoid bone. He1a13 states that transmitted to the distal pulp of the hallux. This osteochondritis of the sesamoid bones has been stage concludes the action of the sesamoid appara- described as "sesamoiditis." tus during the weight-bearing phase of the gait. Diagnosis of "sesamoiditis" is a clinical chal- lenge because many symptoms of this condition CLINICAL PATHOLOGY, DIAGNOSIS, can be seen with other clinical entities. Usually AIID TREATMENT there is pain with direct palpation of the affected sesamoid. Pain may be elicited with first metatar- The position of the hallux sesamoids relative to sophalangeal joint motion. Dorsiflexion generally both the metatarsophalangeal joint and weight- creates the most pain, but adduction and even bearing pattern of the foot makes them r,,ulnerable plantarflexion of this joint can cause pain. During to injury. During the normal gait cycle, the gait the most significant pain occurs with push-off. sesamoids bear three times the weight of the body, Some researchers state that radiographic evaluation with the medial sesamoid accounting for the major- will show no bony abnormality with sesamoiditis." ity of the forces." Others believe that radiographs or other imaging modalities (bone scan, CT scan, MRI) are important Sesamoiditis for diagnosis. According to Potter et al.,' the supe- rior soft tissue visualization of MR imaging can The term "sesamoiditis" has been used loosely in the prove important for delineation and differentiation literature describe various entities.1,3r,7,10,r8 to clinical of the various entities that may be clinically diag- Tendonitis, synovitis, sesamoid bursitis, and chon- nosed as "sesamoiditis". However, if a bone scan is dromalacia, the region plantar in of the aspect of considered, one must know that acute fracture, the first metatarsophalangeal joint are often clini- stress fracture, and sesamoiditis may all give "sesamoiditis."l cally diagnosed as According to positive results. The differential diagnosis of Dennis McKinney," chondromalacia and of the sesamoiditis includes trauma (acute or repetitive sesamoid is the most common trauma associated stress), afihritis, infection, osteochondritis, tumor, with "sesamoiditis," and that is commonly con- it or callous of the sesamoids. fused stress fractures. with Jahss states that Treatment for "sesamoiditis" may consist of sesamoiditis "consists of persistent local pain and rest with complete non-weight bearing of the tenderness under lateral either the medial or sesamoids. This can be achieved by means of sesamoid."' Also mentioned the monograph are in padding (dancer's pad), shoe accommodations, or the observations that sesamoiditis may occur in foot orthoses. Local cortisone injections and non- inactive patients with "relative depression the of steroidal anti-inflammatory agents may also be first metatarsal head." cases In such "the thin helpful. Persistent and intractable pain may require walled bursa found under the metatarsal head" will excision of the sesamoid bone."," be enlarged. Interestingly, Leventen5 describes "simple Sesamoid Fractures sesamoiditis" as a frequent disorder with symptoms of tenderness under the first metatarsal head, particularly Trauma to the sesamoids may be divided into acute medially, that persist in association with walking. fractures, fracture dislocations, and increasingly common stress injuries associated with activities I68 CHAPTER 33 involving repetitive forces such as high impact aer- may demonstrate swelling in the area. Some obic exercise, dance, or long distance running.' patients will only have pain with dorsiflexion of the Acute fractures are uncommon and are caused by first metatarsophalangeal joint. Although it is possi- falls from a height,' direct force from a object ble for a patient with a sesamoid fracture to have falling onto the joint,l acute hyperextension of the none of these clinical signs, the clinical examination metatarsophalangeal joint,l'Z or penetration injuries. is very important to localize pathology. Howeveq The hyperextension injuries of the first metatar- the diagnosis cannot be based on physical findings sophalangeal joint have been classified into two only. Appropriate diagnostic measures must be basic types."," Type I occurs when there is dorsal taken and follow-up examinations should be con- dislocation. As the hallux dorsiflexes, the plantar ducted. Improper treatment of a sesamoid fracture capsule ruptures at ils attachment on the plantar may lead to prolonged and debilitating pain. aspect of the metatarsal neck. The hallux then rides Radiographic criteria is of great impofiance in over the metatarsal head with the sesamoids still rhe diagnosis of sesamoid fractures.' Radiographs attached to each other and to the base of the prox- should include dorsoplantar (DP), lateral, medial imal phalanx. The medial and lateral conjoined oblique, and possibly lateral oblique and axial tendons remain intact and taut on either side. views of the sesamoid bones. The DP and medial Type II has two subtypes. Type IIA occurs as oblique x-rays are usually the most helpful. The further dislocation occurs at the joint and the inter- sesamoid view is more useful in the oblique sesamoidal ligament ruptures separating the two sesamoid separations, multi-fragment separations, sesamoids. Type IIB occurs when the dorsiflexion and long term comparison views regarding bone allows the intersesamoid ligament to remain intact density. Fractures may not be seen or differentiated but results in a transverse fracture of one or both on the initial radiographs, thus it is important to sesamoids.'3 Graves et al.'4 presented four cases take repeat films at a later time. The stress dorsi- where plantar plate injury to the first metatar- flexion view of the 1st metatarsophalangeal joint sophalangeal joint occurred resulting in proximal may be helpful in differentiation of a sesamoidal retraction of the sesamoids. There was no history fracture. Both lateral and DP x-rays are taken with of a dislocation, although two of the patients had the hallux dorsiflexed to open up the fracture. associated sesamoid fractures. Differentiation of a sesamoid fracture from a Chronic, repeated low-level trauma may result bipartite or multipartite sesamoid may be difficult. in stress fractures of the hallux sesamoids. Downey" offers the following criteria that can be Individuals with car.us-lype feet, a plantarflexed helpful for differentiation of a fractured sesamoid first metatarsal, or long first metatarsal are at a from a partitioned one. First, the previous radi- greater risk to develop this kind of fracture." This ographs, if available, should show no evidence of injury has been associated with activities involving a sesamoid fracture if such a diagnosis is currently jumping, such as ballet, jogging, basketball, volley- entertained. Second, the lines of separation ball, tennis, racquetball, football, soccer, barefoot between the fragments of the sesamoids that are walking. or exercise. indeed fractured should be irregular, jagged or ser- The clinical manifestation of sesamoid frac- rated, although this by itself is not diagnostic. tures may present as an acute onset of pain or a Transverse separation during sesamoid fractures is more gradual onset of pain beneath the first commonly seen. However, if the fracture lines are metatarcal area. The patient may be able to pin- longitudinally or obliquely oriented, or if the space point the exact time and the activity when the between the fragments is particularly large, a symptoms began." sesamoid fracture is more likely. This also is not In contrast, there may be an insidious onset of pathologic. It would also be helpful to see anatonl- pain which is aggravated by activify and relieved ically abnormal fragment positions, multiple by rest. Sometimes the patient will complain of a irregular fragments, and interrupted peripheral cor- painful lateral calf muscle because of reflex ever- tices. This may not be diagnostic by itself. Bone sion of the foot away from the area of the callous formation may be seen in later stages. sesamoid." Upon clinical examination the patient \fleiss"states that a bone scan (technetium 99) may have tenderness to palpation of the plantar should be performed if it is difficult to determine aspect of the first metatarsophalangeal joint and whether a sesamoid is partitioned or fractured. The CHAPTER 33 169

bone scan will show increased isotope uptake as a agents. Downey'5 prefers a non-weight-bearing result of osteoblastic new bone formation, and the short-leg cast that extends to the end of the hallux, metabolic change at an acute fracture site will be with cast padding material applied in a manner to apparcnt before changes are seen on a regular radi- maintain the first metatarsophalangeal joint in a ograph. On the other hand, the bone scan is slightly plantarflexed position, for four weeks. nonspecific, and the quality of the image limits the An alternative is to use a weight-bearing short- ability to determine the exact structure and topog- leg cast in which the first ray is unweighted. The raphy of the lesion. Acute fracture, stress fracture, hallux still needs to be held in plantarflexion. and sesamoiditis are difficult to differentiare via Padding can be used to protect the soft tissues. A bone scans, as all may be hot. Approximately 24 Jacoby splint to hold the hallux plantarflexed, cou- hours after the injury, an acute fracture may pro- pled with a wooden sole shoe with the first ray duce a metabolic disturbance that results in a unweighted with a korex cutout, is an alternative. positive bone scan. Thus, a negative bone scan will Other conservative measures include adiustments be more helpful in ruling-out an acute fracture, in the patient's shoe to decrease stress in the than a positive bone scan for ruling-in a fracture.2l sesamoid area. A rocker-bottom sole can decrease Routine or computerized tomography may pain by reducing dorsiflexion. A sesamoid pad offer a more detailed assessment of a sesamoid (dancer's pad) can be placed to free the sesamoids fracture, including the alignment of the bone from weightbearing stress. fragments.l This can also demonstrate cortical irreg- In addition, systemic anti-inflammatory med- ularities and help to distinguish bone tumors or ications may be prescribed." These may be helpful osteomyelitis. if pain is associated with synovitis. Injection of Magnetic resonance imaging may also be used extra articular corticosteroids, although controver- in disclosing a sesamoid fracture by identification sial due to their adverse effects on bone healing, of bone marrow edema.l There will be low signal may relieve pain from local inflammation. In more intensity on T1-weighted images and high signal chronic injuries, or in injuries that are seen several intensity on long TVTE images. This diagnostic months after the acute incident, a bone scan is sug- modality is expensive, and it can be considered in gested to evaluate the vascular supply of the instances when additional information regarding affected sesamoid and the potential to heal with the regional soft tissues and tendons is required. conseruative measures. If a cold cleft is noted at the MRI may be useful in determining osteomyelitis of fracture site, surgery will be necessary. 'When the sesamoid and/or the first metatarsal head. conselative treatment fails, surgical Intra-articular injections of local anesthetics intelention is of great impoftance. Richardson'6 into the first metatarsophalangeal joint can help reporls that prolonged conservative therapy with a to differentiate belween an intra-articular and an short-leg cast or molded supports is ineffective. exlra-articular problem." Sesamoid iniury will not Earlier, Para'l reported in his monograph that " the respond to this form of therapy. treatment of choice in fractures of the sesamoids of The treatment of fractured sesamoids is a sub- the foot is surgical excision." According to Downey'Z5 ject of controversy. \7eiss'l indicates that a less one report indicates that more than 300/o of all aggressive treatment with a padded shoe and stiff sesamoid fractures will eventually require surgery. sole, or reduction in activity is adequate treatment Most authors will recommend excision of a frac- for fractured sesamoids. Others are convinced that tured sesamoid if pain and discomfort persist after true sesamoid fractures are resistant to therapy." six months.a,21 There are those who believe'5lhal "in most sesamoid If the distal fragment of the fractured sesamoid fractures, conserwative ffeatment should be aggres- is small, partial sesamoidectomy of only this frag- sive" and that "conservative measures frequently fail ment catl be performed." As a result, the if the treatment is delayed or inadequate." complications associated with a total removal will If conservative measures are attempted, three be avoided. Conversely, if patial sesamoidectomy general principles are employed 1. Unweighting fails to reduce pain, or if the sesamoid fracture is in the sesamoids. 2. Resist distraction forces on the multiple pieces, total excision of the bone may sesamoid (prevent dorsiflexion forces on the first be required. metatarsophalangeal). 3. Use of anti-inflammatory A plantar-medial approach is most often used I7O CHAPTER 33 to remove a medial sesamoid.25 After a 3-6 cen- of the periosteal tendinous covering and excised en timeter incision is made extending from the first toto. The periosteal tissue is approximated and the metatarsophalangeal joint proximally, it is deep- wound is closed in layers. ened with care to avoid proper digital branches of Success with surgical excision is commonly the medial plantar and the medial dorsocutaneous reflected in the literature. However, complications newe. Next, the joint capsule is incised around the of neuralgia, hallux rigidus, hammertoe, and hallux margin of the sesamoid. This will allow the abductovalgus are also seen." Nayfa and Softo" sesamoid to be freed from the attachments of the presented a study where 11 patients under.went a intrinsic tenoligamentous complex with minimum total of 19 tibial sesamoidectomies, and after an damage to these structures. However, if damage average of 2B.B months, they obserued occurrence has occurred, it must be carefully repaired. of hallux abductus deformity in 42.1,0/o of the cases. Other methods of surgical intervention have This points to the need to tighten and repair the been advocated. For example, Leventen5 writes that void left by excision of the sesamoid to re-establish "refractory sesamoiditis may be a good indication musculotendinous balance. for doing a pafiial excision of the plantar one-half After the removal of a fractured sesamoid, the of the involved bone, thereby avoiding disruption residual imbalance of this musculoligamentous of the mechanics of the great toe joint." Long-term complex becomes important. Splints and orthosis studies of this approach have not been well docu- may be beneficial in the long-term management of mented. Marcinko and Elleby'?8 suggest removal of the first metatarsophalangeal joint. only the distal fragment of the fractured tibial In some cases both sesamoids are removed sesamoid. They report promising results, but a long- resulting in significant muscle imbalance across the term evaluation of this approach may be essential. first metatarsophalangeal joint. In these situations, a After removal of the sesamoid, the capsule, the fusion of the interphalangeal joint of the hallux is superficial fascia, and the skin are closed in layers. usually necessary. This may be combined with a Subsequently, the foot is immobilized in a non- Jone's tenosuspension of the extensor halluces weight-bearing cast for 3 weeks. Gradual return to longus tendon.'3,'5 full weight bearing is expected after this period. A modified McKeever arthrodesis of the first Fractured fibular sesamoids are best removed metatarsophalangeal joint is an alternative proce- from a dorsal approach if the sesamoid is in the dure when both sesamoids are removed. Stroh et interspace.'?5 The incision extends 3-6 centimeters al." presented such a case. The authors state that from the web space proximally. Next, the incision after two years of follow-up obseruation, the is deepened. The adductor halluces is identified. A patient had a stable, pain-free metatarsophalangeal linear incision is made above the adductor attach- fusion site. ments to the fibular sesamoids. A small amount of In geriatric populations, a Keller arthroplasty soft tissue is left attached to the sesamoids to grasp of the first metatarsophalangeal joint may be per- it as it is shelled out from the soft tissue attach- formed if both sesamoids are surgically removed." ments. The intrinsic ligamentous complex and the Patients in this age group tend to be more sedentary tendon of the flexor halluces longus muscle are and they place low demands on their first metatar- protected from any possible damage. The post- sophalangeal joint. Attachment of the flexor halluces operative care is essentially the same as for tibial longus tendon to the proximal phalangeal stump sesamoidectomy. helps to prevent cocking of the hallux in stance. If the fibular sesamoid is located under the Lengthening of the extensor halluces longus helps to first metatarsal head, a planlar approach is advo- prevent cocking of the hallux in swing phase. cated. A 3-6 centimeter incision is made in the first Sesamoidectomies are also performed for the interspace lateral to the fibular sesamoid. The inci- treatment of chronic neuropathic ulcerations.'e A sion is carried deep. The nerve that lies plantar and minimal incision surgical approach was used by lateral to the sesamoid is retracted laterally. The Bartelro to treat "medial sesamoiditis," intractable capsule and periosteal tissue are incised and plantar keratosis, and "lateral sesamoid problems." reflected medially and laterally. Once again, a small Long term follow-up statistics on this approach are amount of soft tissue is left attached to the not available, however. Theoretically, large, non- sesamoids to grasp it. The sesamoid is shelled out displaced sesamoid fractures may be treated with CHAPTER 33 171 bone grafting to reconstitute the bone and preserve 12 months. One group of investigators, according the biomechanical integrity of the sesamoid to Dennis and McKinney, found typical radi- apparatus.'?l Tension banding techniques to loop ographic changes within six months. the superficial aspect of the sesamoids are also the- Rest and immobilization constitute the main oretically possible to create compression across the methods of conserwative treatment of this condi- fracture site. This is similar to techniques used to tion. These measures frequently fail to alleviate the fk transverse patellar fractures. discomfort, and surgical extirpation of the offend- ing sesamoid becomes a necessity. OSTEOCHONIDRITIS ARTHRITIS Though rare in the foot, osteochondritis or avascu- lar necrosis of the sesamoids may be debilitating.r, The hallux sesamoids form a pafi of a true synovial Historically, this condition has been described as joint, and thus may be subject to both inflammatory "sesamoiditis," "osteomalacia," "osteitis fibrosa," and degenerative afihritides. Sesamoid involvement "juvenile necrotic osteopathy," "traumatic osteitis," in rheumatoid arthritis, in seronegative spondy- "Kohler's, Schlatter's, or Renander's disease of the loarthridities such as Reiter's, and in crystal deposition sesamoids," "sesamoid insufficiency," and "osteo- diseases such as gout, have been described.' chondropathy".3 Ilfeld and Rosen describe the histological findings of the specimen obtained from TUMORS three cases of osteochondritis.3l They state that the bone was irregulady osteosclerotic, and marrow Sesamoid neoplasias are tate. There have been spaces between trabeculae were quite vascular and reports of xanthomatous tumors involving the contained sparse fatty elements. It was also noted sesamoids.'o Ribalta et aL.,3'repoft on an occurrence that the cartilaginous surfaces showed marked of chondromlo