Digital and Sesamoid Fractures

Digital and Sesamoid Fractures

Michael S. Downey

Gretchen A. Lawrence

Digital and sesamoid fractures are common injuries affecting patients in all age groups and activity levels, including those who are sedentary. In most circumstances, the fractures are amenable to conservative treatment and generally do not pose a problem. However, many patients who have sustained a digital or sesamoid fracture do not seek timely care for their injury. Inadvertently, these patients convert what would otherwise be a simple, inconvenient setback into a more difficult to treat and complex problem, often prolonging or impairing their full recovery. A certain mindset or misconception exists among many lay people that there is really no specific treatment for digital fractures or “if the toe can move it is not broken,” and this attitude likely contributes to the delay between injury and seeking treatment.

Significant fractures can affect the toes and sesamoids, and may require more prompt attention, particularly if dislocation or displacement occurs or if the fracture is intra-articular or open. In most injuries of this nature, deformity is obvious, and patients tend to seek treatment quickly.


Fractures of the toes are the most common injury of the forefoot seen in emergency rooms, with a reported incidence of 140 cases per 100,000 population per year and with a male to female ratio of 1.6:1 (1,2 and 3). As with any injury, the pathologic forces that cause digital fractures may be directed in any one or a combination of the cardinal body planes. Although most injuries involve a combination of these forces, a predominant plane of force can often be identified. Certain fracture patterns are more frequently observed and can be related to these injury mechanisms. Understanding the predominant plane of injury facilitates the closed or open reduction, realignment, and treatment of digital fractures.


Injury occurring in the sagittal plane and resulting from direct trauma, hyperextension, or hyperflexion of the involved digit is the cause of most digital fractures. Sagittal plane crushing is the most frequent mechanism of injury associated with a fractured hallux. Crush injuries are most often caused by a heavy object, which may be dropped or may fall, or by industrial or motor vehicle accidents. A subungual hematoma is often a component of the injury, and these can require evacuation ranging from dorsal drainage through a pinhole created in the nail plate to total nail avulsion. Protocols for care of the nail injury can be found in Chapter 99. The digital fractures seen in direct traumatic injuries are frequently comminuted and most commonly involve the phalanges of the hallux and the middle and distal phalanges of the lesser digits (4,5 and 6).


Abduction-adduction forces are also common and generally result in transverse or short oblique fractures of the proximal phalanges. The most notorious example of this injury has been termed the bedroom fracture or night-walker fracture because it often results from striking the fifth digit against a bedpost while the patient is walking in the dark (Fig. 103.1). At times, the injury may consist of a dislocation of the interphalangeal joint or the lesser metatarsophalangeal joint (MTPJ). Even though the proximal phalanx of the fifth digit is the most commonly involved, other digits may be injured through abduction or adduction forces. A transverse fracture free from the articular surfaces may be treated with closed reduction, whereas comminuted or open fractures may require surgical intervention.


Rotational or inversion-eversion injuries occurring predominantly in the frontal plane are less frequent and generally are secondary components of transverse or sagittal plane fractures. When spiral fractures of the phalanges occur, closed reduction is more difficult, as is maintaining the reduction once it has been achieved, because of the more unstable nature of the fracture pattern.


The signs and symptoms of digital fractures consist of pain, ecchymosis, and edema that develop within a few hours after injury. The patient experiences acute pain, has difficulties with weight-bearing, and finds wearing shoes that compress the area uncomfortable. In some instances, an obvious clinical deformity is seen in the digit as a result of displacement of the fracture. Occasionally, patients may relate that they relocated the deformed toe themselves after the injury.


The sesamoids are vitally important structures to the normal function and weight-bearing mechanics of the first MTPJ. The sesamoid complex normally transmits up to 50% of body weight and during push-off can transmit loads greater than 300%. These high stresses can lead to both acute and chronic pathologies. Sesamoidal problems may occur in almost anyone from one beginning an exercise program, to the weekend warrior, to the elite-level athlete (16).


The sesamoid bones of the hallux are located at the plantar aspect of the first MPTJ and are embedded within a fibrous tendoligamentous network. No periosteum surrounds the sesamoid, but rather an aponeurosis surrounds the plantar cortex (17,18). A cartilaginous dorsal surface articulates with the first metatarsal head. This is believed to increase the mechanical leverage of the great toe by acting as a fulcrum for the flexor tendons (19).

Figure 103.7 Traumatic open injury to the fifth digit. Clinical (A) and radiographic (B) appearance. Clinical (C) and radiographic (D) appearance after irrigation, débridement, and K-wire stabilization.

Initially, the sesamoids become identifiable as undifferentiated connective tissue within the tendon of the flexor hallucis brevis by the 8th week of embryonic life, and chondrification arises during the 12th week of gestation. Ossification usually occurs between 6 and 12 years of age. The multiple foci of ossification may or may not coalesce, leading to bipartite, tripartite, or quadripartite sesamoid bones. The incidence of bipartite sesamoids varies widely. In a large series, Kewenter reported a 35.5% incidence in 1,588 feet, and Inge and Ferguson stated a 10.7% incidence in 1,025 feet, with 75% of cases being unilateral. Both studies described numerous variations in partite sesamoids (20,21) (Fig. 103.8).

Figure 103.8 Bipartite tibial sesamoid.

The medial (tibial) and lateral (fibular) hallux sesamoids are enclosed within the medial and lateral tendon slips of the flexor hallucis brevis muscle, with the abductor and conjoined adductor hallucis tendons inserting into the medial and lateral sesamoid complex, respectively. The sesamoids are held in place in their grooves beneath the first metatarsal head by the fibrous plantar plate, which consists of the intersesamoidal ligament, medial and lateral collateral ligaments, medial and lateral metatarsal sesamoidal ligaments (aka tibial and fibular sesamoidal ligaments), and phalangeal sesamoidal ligaments. The plantar fascia blends into the plantar surface of both sesamoids (17). The lateral (fibular) sesamoid is also attached on its plantar surface to the intermetatarsal ligament (Figs. 103.9 and 103.10).

The arterial supply of the hallux sesamoids is variable. Pretterklieber and Wanivenhaus found the number of vessels supplying the sesamoids ranging between one (55%), two (35%), and three (10%) (18) (Fig. 103.11). Rath et al (22) found the first plantar metatarsal artery to be the main source of arterial supply for the sesamoid bones and that more than 90% of feet had both sesamoids supplied by two or three arteries. The supplying arteries penetrated the sesamoid bones on the proximal, plantar, and distal sides (18,22,23).

Figure 103.9 Hallux sesamoid complex anatomy: coronal view. FHB, flexor hallucis brevis; FHL, flexor hallucis longus; l, lateral; m, medial. (Redrawn from Karasick D, Schweitzer M. Disorders of the hallux sesamoid complex: MR features. Skeletal Radiol 1998;27:411-418.)

Figure 103.10 Hallux sesamoid complex anatomy: transverse view. 1, tibial and fibular sesamoid; 2, flexor hallucis brevis tendon medial and lateral slips; 3, flexor hallucis longus tendon; 4, abductor hallucis tendon; 5, adductor hallucis tendon; 6, intersesamoidal ligament. (Redrawn from Jahss MH. The sesamoids of the hallux. Clin Orthop 1981;157:88-97.)


Traumatic injury to the sesamoid bone may result from falls, forced dorsiflexion, or repetitive stress. These injuries have become more common with the rise in sports such as aerobics, yoga, jogging, long-distance running, and speed or power walking. Athletes competing in acceleration-deceleration sports such as football, soccer, tennis, baseball, softball, or jumping activities also often present with sesamoid injuries (24). Sesamoid fractures are usually transverse or comminuted, and one or both of the sesamoids may be involved. They are frequently created from direct force in the sagittal plane, with the tibial sesamoid injured more often because of the increased weight-bearing at the medial aspect of the joint. Sagittal plane injuries tend to crush the sesamoid between the first metatarsal head and the supporting surface.

Many other sesamoid injuries are insidious in onset, and the patient is unable to recall any single, acute traumatic event. Because the sesamoids of the first MTPJ receive the weightbearing forces carried by the first metatarsal head, they have a supportive role comparable to that of the lesser metatarsal heads (20,23,25). Certain biomechanical derangements and foot types (e.g., the cavus foot or the foot with metatarsus primus equinus) are predisposed to chronic repetitive sesamoid trauma and possible fracture (26,27 and 28).

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Jul 26, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Digital and Sesamoid Fractures
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