eMedicine Specialties > Orthopedic Surgery > Foot & Ankle

Turf Toe

Author: Blake Ohlson, MD, Staff Physician, Department of Orthopedic Surgery, Michigan State University, Kalamazoo Center for Medical Studies
Contributor Information and Disclosures

Updated: Dec 7, 2009

Introduction

Although several variations exist, the classic definition of turf toe is a hyperdorsiflexion injury of the first metatarsophalangeal (MTP) joint, as displayed in the images below. Since approximately the 1980s, turf toe has received increased attention in the media because of its effect on college-level and professional athletes.^1,2,3,4

History of the Procedure

Prior to the advent of artificial playing surfaces in the late 1960s, sprains to the hallux MTP joint were relatively uncommon. As artificial turf became popular in sports such as football, the incidence of MTP joint injuries appeared to increase. During a roundtable discussion in 1975 regarding the benefits and drawbacks of artificial turf, Garrick first suggested the relationship between first MTP joint sprains and the use of synthetic playing surfaces.⁵ One year later, Bowers and Martin introduced the term turf toe to describe a plantar capsuloligamentous sprain of the first MTP joint related to 2 predisposing factors: hard artificial surfaces and soft-soled shoes.⁶

The earliest synthetic surfaces contained a synthetic nylon ribbon that wore away over time. Beneath that was a foam underpad that quickly became packed down, leaving a virtual asphalt-carpet interface. As a consequence, the effect of surface hardness was originally thought to be responsible for turf toe injury.

After the development of artificial turf, many players complained of poor traction with traditional shoes designed for use on grass surfaces. Despite lower rates of injuries, the demand for increased speed and traction in sports (eg, football) led to the development of a more flexible shoe. A softer, soccer-style shoe replaced the traditional multicleated shoe containing a steel plate in the forefoot that was designed for grass surfaces. This shoe allowed a greater degree of motion in the MTP joints and placed significantly more stress across the forefoot.

In 1978, a major study from the University of Arkansas by Coker and colleagues cited turf toe as a major cause of missed games and practices.⁷ However, it was not until 1986 that Clanton and coauthors developed a classification scheme for describing the degree of severity for turf toe injury.⁸ With some minor revisions since its original publication, this system continues to help in guiding treatment, as well as in predicting return to play.

Problem

Turf toe injury is most commonly seen when an axial load is delivered to a foot that is fixed in equinus. The typical scenario, which often occurs in football linemen, involves the fixation of the forefoot on the ground in the dorsiflexed position with the heel raised. An outside force then pushes the foot into further dorsiflexion, resulting in traumatic hyperextension of the hallux MTP joint, as shown in the image below. Although turf toe is most frequently seen in football players, it can occur in athletes in any sport (eg, basketball, soccer, rugby).

Turf toe injury is not limited to damage from hyperextension of the MTP joint. Several variations have been described that account for damage to specific anatomic structures in the capsuloligamentous-sesamoid complex. These include hyperflexion injuries, as well as valgus- and varus-type injuries. Because each mechanism affects different structures, accurate diagnosis is crucial to understanding nonoperative and operative treatment modalities.

Brophy et al found that in professional football players with a history of turf toe, first metatarsophalangeal dorsiflexion was significantly lower in halluces with a turf-toe history (40.6 +/- 15.1º versus 48.4 +/- 12.8º) and peak hallucal pressures were higher.⁹

Frequency

The actual incidence of turf toe has never clearly been defined. In certain sports, such as football and rugby, a predisposition to turf toe injury is higher than it is in other sports. In a study among football players at the University of Arkansas, researchers estimated the incidence to be 6 cases per year. At Rice University, an average of 4.5 cases per year was found among all sports over a 14-year period.

Turf toe ranks as the third most common injury (after knee and ankle traumas) causing loss of playing time among university athletes.¹⁰ While ankle injuries are up to 4 times as common as turf toe, the latter may account for a significantly greater proportion of missed playing time.

Etiology

Bowers and Martin coined the term turf toe to acknowledge the predisposing factor of artificial synthetic surfaces on hallux metatarsophalangeal (MTP) joint sprains.⁶ They found that injuries occurred most frequently in athletes playing on artificial turf who wore flexible, soccer-style shoes. The shoe-surface interface is probably responsible for the higher risk of injury in these athletes. In descending order of importance, causative factors are listed as follows:

• Footwear - Throughout the past several decades, football shoes have evolved from the traditional 7-cleat shoe containing a metal plate in the sole designed for grass surfaces to a more flexible, soccer-style shoe designed for grass surfaces and, finally, to a shoe designed for artificial turf. These changes in shoe type have allowed increased speed at the expense of stability. The absence of a stiff sole places the forefoot, and specifically the MTP joints, at much greater risk of sustaining stress-type injuries. Athletes wearing flexible turf shoes are much more prone to injury than are those wearing shoes containing a stiff forefoot.
• Synthetic surfaces - Artificial grass contains a higher coefficient of friction and tends to lose some of its resiliency and shock absorbency over time. The combination of increased surface friction and a hard undersurface is believed to play a major role in the natural history of the injury. A higher coefficient of friction places the forefoot at greater risk of becoming fixed to the playing surface. Thus, the forefoot becomes more prone to an external force that places the hallux MTP joint in a position of extreme dorsiflexion.
• Ankle range of motion (ROM) - The risk of turf toe appears to be related to the range of ankle motion in the injured person. A greater degree of ankle dorsiflexion has been correlated with the risk of hyperextension to the first MTP joint.
• Miscellaneous - Other factors have been postulated to play a role in turf toe. These include a player's position, weight, and years of participation, as well as hallux interphalangeal degenerative joint disease, pes planus, and prior injury. For the most part, study results regarding these factors are largely inconclusive. Another point worth mentioning, however, is that a number of groups have, after researching the question, found no correlation between MTP joint ROM and the associated risk of turf toe.

Pathophysiology

The normal MTP joint functions with a smooth gliding motion except when in full dorsiflexion, when some compression occurs. Tears of the joint capsule occur at the metatarsal neck rather than at the proximal phalanx because the metatarsal neck is its weakest point of attachment. Once torn, unrestricted motion of the proximal phalanx results in severe compression of the dorsal articular surface of the metatarsal head. This produces the potential for fracture or possibly even for dislocation. Usually, the plantar portion of the ligamentous complex tears, while the plantar plate becomes detached distal to the sesamoids. Rarely, fracture of the sesamoid bone may occur, as shown in the image below.

Other mechanisms of turf toe injury include valgus and varus injuries, as well as hyperflexion-related damage. Valgus injury is a variant of the dorsiflexion-type injury in which the medial ligamentous structures and, in some cases, the medial sesamoid bone are damaged. This most often occurs in the setting of push-off, when internal rotation occurs on a fixed forefoot. Untreated, this may lead to bunion formation and contractures on the lateral side of the joint.

Rarer still, a varus injury may result from external rotation on a fixed forefoot. Patients may present with varus instability resulting from a torn lateral capsule as well as from rupture of the adductor hallucis tendon from the base of the proximal phalanx.

Hyperflexion occurs when the MTP joint is forced into exaggerated plantarflexion. This injury has been referred to as sand toe, as it often occurs in beach volleyball players. The injury has also been known to occur in football players and dancers. A plantar foot with the MTP joints driven into exaggerated hyperflexion can result in tearing of the dorsal capsule. The anatomic structures that are damaged and the injury treatment required are different from those of classic turf toe and should be recognized as such.

The table below shows the classification scheme for tears of the capsuloligamentous complex, including for hyperflexion and dorsiflexion injuries. (See Clinical for a discussion of injury grades.)

Classification Scheme for Tears of the Capsuloligamentous Complex

Open table in new window

Presentation

Physical examination then follows, with attention to the presence and location of pain, swelling, and ecchymosis. The examination may be difficult in the acute stages because of pain; however, all structures, including the collateral ligaments, sesamoids, plantar plate, and dorsal capsule, should be palpated.

ROM testing should be performed by carefully looking for instability, mechanical block, or hypermobility that may suggest tearing of the plantar plate. Instability is assessed by performing the varus or valgus stress test and the dorsoplantar drawer test of the MTP joint. A positive result with the former suggests collateral ligament damage, whereas a positive finding with the latter suggests a plantar capsuloligamentous tear. Finally, examination of all structures is aided by comparison to the contralateral side.

Injuries are graded as follows:

• Grade 1 injury - Localized tenderness with minimal swelling and no ecchymosis
• Grade 2 injury - More widespread tenderness with mild to moderate swelling and ecchymosis
• Grade 3 injury - Severe and diffuse tenderness and swelling, moderate to severe ecchymosis, and painful ROM

Although most cases are managed conservatively, the treating physician should be alert to the presence of hallux malalignment, traumatic bunion deformity, diminished flexor strength, clawing of the great toe, generalized synovitis, or advanced degenerative joint disease. Clinical findings such as these often indicate that surgical intervention is required.

Indications

Most metatarsophalangeal (MTP) joint injuries can be managed nonsurgically. However, in instances in which the injury is refractory to conservative treatment, surgery should be considered as an option.

Complications of turf toe injury that may necessitate surgical intervention include the following:

• Sesamoid fracture
• Separation of a bipartite sesamoid bone
• Proximal migration of the sesamoids
• Instability with accompanying persistent pain or synovitis
• Hallux rigidus
• Cartilage flap or loose body within the hallux MTP joint

Relevant Anatomy

To understand how turf toe injury occurs, a thorough understanding of all anatomic structures in and around the metatarsophalangeal (MTP) joint is critical. Unlike a simple hinged joint, the hallux MTP joint functions more like a hammock or an acetabulum. It contains multiple centers of motion, including sliding, rolling, and compression.

Like the glenoid cavity of the shoulder, the shallowness of the articular surface of the proximal phalanx provides little stability to the joint. The capsuloligamentous-sesamoid complex contributes most of the stability observed in the MTP joint. This complex is made up of collateral ligaments, along with the plantar plate, flexor hallucis brevis, adductor hallucis, and abductor hallucis, as shown in the image below.

• The medial and lateral collateral ligaments are composed of an MTP and a metatarsosesamoid ligament. They originate on either side of the metatarsal head and fan out distally to attach to the proximal phalanx.
• The plantar plate is a strong, fibrous structure that is firmly attached to the proximal phalanx and is loosely attached to the metatarsal neck through the joint capsule. It blends with the sesamoids and tendons of the flexor hallucis brevis to provide structural support.
• The sesamoid bones play a crucial role in providing stability to the MTP joint complex and in enhancing the tendon moment arm of the flexor hallucis brevis.
• The flexor hallucis brevis originates on the cuboid and lateral cuneiforms before splitting into medial and lateral heads that extend beneath the first metatarsal bone. Tendon fibers envelop the sesamoid bones just proximal to an insertion point at the base of the proximal phalanx. The flexor hallucis brevis plays an integral role in providing push-off strength for the hallux.
• The abductor and adductor hallucis tendons contribute additional stability through their insertions on the medial and lateral plantar portions, respectively, of the capsuloligamentous complex.

Proper function of the MTP joint is essential to normal foot biomechanics. The great toe typically bears twice the load of the lesser toes, and during normal gait, it withstands 40-60% of the body weight. This load increases severalfold with running or jumping, and it may approach nearly 8 times an individual's body weight with a running jump.

The normal MTP joint is in approximately 16 º of dorsiflexion relative to the longitudinal axis of the first metatarsal, and it has a passive arc of motion in the range of 3-43 º plantarflexion and 40-100 º dorsiflexion. During normal gait, this angle is 60 º on average, but it may decrease to 25-30 º dorsiflexion in a stiff-soled shoe without affecting gait.

As mentioned earlier, in high-performance activities, such as professional and college-level sports, the drive has been to produce lighter, softer-soled shoes that provide increased MTP joint motion. An increase in speed and flexibility occurs at the expense of stability, with greater stresses across the forefoot.

Contraindications

Contraindications to surgical intervention are nonspecific and include those that apply to any surgical procedure. Contraindications include active local infection or open dermatologic lesions, advanced dysvascularity, and minimal or absent pain and dysfunction.

Patients with turf toe injuries are typically young and healthy. Therefore, they are unlikely to have local or systemic conditions that preclude surgery.

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