Metatarsal Stress Fracture and Complications
Because of the metatarsals’ location, they are exposed to high stresses during many types of athletics, particularly those involving frequent jumping, pivoting, and repeated changes of direction. The metatarsals are susceptible to chronic stress-induced fractures from a combination of factors including foot anatomy, footwear, playing surface, specific maneuvers, previous injury to surrounding tissue, and more general variables such as frequency of sports activity.
Acute treatment involves the traditional use of rest, ice, compression, and elevation (RICE), the use of crutches, a gradual return to normal activities, and any necessary changes or augmentation to footwear. Generally, recovery is complete after nine weeks but complications from insufficient rest include increased trauma to the area and prolongation of total recovery time. With adequate attention, metatarsal stress fractures heal completely without subsequent recurrence of symptoms unless specific underlying factors continue to impose unusual stresses on the area.
Among stress-related skeletal fracture injuries, metatarsals are not frequently involved and among metatarsal stress fractures, the vast majority involve the second or third metatarsal with only a very small minority involving the fifth metatarsal. As with stress fractures generally, onset of symptoms associated with metatarsal stress fractures are gradual rather than sudden and rarely involve any specific instantaneous motion or acute injury. Rather, they manifest themselves through soreness caused by the same athletic activities responsible for their development and often do not interfere with ordinary ambulation and other non-athletic daily activities.
Metatarsal Stress Fractures: Complications of a Complete Fracture
The ankle is the most primitive and most stable joints in the human body, primarily because it only moves in one direction (i.e. up and down) and without any lateral or rotational motion in any other plane (Iazetti & Rigutti, 2007). While this design is functional for the ankle joint, it renders other tissues of the foot comparatively susceptible to increased chronic stress-related injury from repeated athletic movements, because the ankle does not provide as much assistance in the dissipation of dynamic muscular stresses or, especially, those related to ground-reactive sources in the same manner that other more flexible joints, such as the knee, absorb stress loads (Frankel & Difiori, 2007; Iazetti & Rigutti, 2007).
With accurate diagnosis and adequate acute treatment, rehabilitation, and a gradual return to athletic activity, metatarsal fractures are readily treatable without lasting effects after return to full activity. However, inappropriate return to full activity before healing is complete generally results in prolongation of acute symptoms and retardation of recovery and return to full activity levels. In the most serious cases, premature return to competition, particularly in the absence of a graduated rehabilitation program strategy, can transform a stress fracture into a complete break necessitating a full surgical repair and much more extensive post-repair convalescence and prolonged period of rehabilitation before full recovery.
Definition of Anatomy & Terminology:
The metatarsals are the longest bones of the foot, which in and of itself, predisposes them to the greatest stress loads during ambulation and many athletic movements involving the foot. Each metatarsal connects the bones of one toe to the rest of the foot by strong ligaments and to the muscles responsible for their movement by tendons. Bursa sacks consisting of fluid-filled cushions are positioned directly below the proximal head of each metatarsal to provide some protection against ambulatory stresses but are not always sufficient to protect the metatarsals from stress fractures (Jaukovi?,
Ajdinovi?, Gardasevi?, et al., 2006).
Generally, stress fractures represent the cumulative effects on skeletal bone from repeated load bearing and other mechanical stresses that produce micro-traumas or micro-fractures within the bone tissue (Howe, 2007). In most cases, rest and the elimination of the source of mechanical stresses is sufficient to heal stress fractures without subsequent recurrence or complications. However, in some instances, prolonged exposure to repeated stresses without adequate rest for healing and reparative bone cell formation can eventually produce a complete break in the area of significant micro-trauma (Howe, 2007).
Mechanism of Injury:
In general, the skeletal bones of the legs and lower extremities are exposed to regular mechanical loads that produce high stresses on the internal structure of bone cells (Logan, 2009; Saremi, 2009). Repeated stress and mechanical loading from weight bearing triggers increased bone cell growth and functions as a protective mechanism by increasing bone density and decreasing the relative amount of empty microscopic spaces in-between individual bone cells (Iazetti & Rigutti, 2007). This process varies in different individuals in relation to age, genetic factors, and nutritional intake, particularly with respect to calcium and vitamin D which facilitates calcium absorption into skeletal tissues (Howe, 2007).
Still, among athletic stress fractures, the metatarsals are involved in only approximately one-tenth to one-fifth of all stress fractures with fully four-fifths involving the second and third metatarsals; by contrast, the fifth metatarsal is the site of stress fracture injury least often (Frankel & DiFiori, 2004). The reason becomes obvious when one analyzes the mechanism by which athletes orient their feet during jumps, landings, pivots, and other stress-inducing foot movements. Specifically, the greatest load is borne by the center of the foot in the area of the middle, precisely where the second and third metatarsals are most involved in the generation and dissipation of dynamic forces (Frankel & DiFiori, 2004).
As is the case with other substances under load-bearing stresses (i.e. both anatomical tissues and inanimate materials), microscopic irregularities in the internal structure can present local areas of weakness and increased susceptibility to damage from repeated stress (Barsom, 2005). In that regard, the relative inflexibility of the human ankle (compared with other joints), the small size of the metatarsal bones, and the nature of the specific stresses associated with various athletic movements can result in the eventual development of fault lines representing a linear connection of bone cells that feature microscopic irregularities and micro-fractures of individual cells (Logan, 2009; Iazetti & Rigutti, 2007).
Plyometric action is particularly significant in relation to the formation of stress fractures in the metatarsal bones because the rapid acceleration, deceleration and angular stresses associated with jumping, landing, (and quick changes in direction in which the proximal head of the metatarsals provide the fulcrum for the movement) subject the tissues involved to as much as five times the body weight of the athlete (Frankel & DiFiori, 2007).
Poor technique such as in terms of insufficient incorporation of the knee and hip joints during plyometric movements increase the point load on the metatarsal primarily by eliminating links in the natural shock-absorbing mechanism of coordinated movements involving multiple joints. Similarly, insufficient flexibility in the ankle, knee, and hips also contribute to higher loading under the dynamic stresses of athletic movements involving jumping and rapid changes of direction. Frequently, poor form or balance transfers higher loads to the fifth metatarsal in particular, where, in some circumstances, it is exposed to stresses ordinarily shared between the middle metatarsals in a manner that reduces the load on each individual bone (Iazetti & Rigutti, 2007).
On the other hand, ironically, more-highly-skilled athletes and those with higher natural proportions of fast-twitch muscle fibers are at somewhat increased risk of developing metatarsal stress fractures (Laker, Saint-Phard, Tyburski, et al., 2007). Plyometric analysis reveals that highly skilled athletes tend to spend less time on the ground (or other playing surface) during sports-specific acceleration, deceleration such as that associated with jumps and changes of direction. Their greater skill level, neuromuscular efficiency, and ability to generate mechanical energy allows them to spend less time generating the energy necessary to propel them in their direction of travel. Because less time is available for acceleration and deceleration, the tissues responsible for absorbing the stresses under the load experience higher mechanical stress by virtue of the reduced time available for its dissipation or absorption (Barsom, 2005). In principle, however, this is not a contradiction when one considers the mechanical reasons that account for the increased stresses involved. In that respect, highly-skilled athletes typically subject the metatarsals to greater loads solely by virtue of the compressed time available for load dissipation; but the specific anatomical structures under the load are not affected by that variable. Meanwhile, poor technique transfers increased loads to different regions of the foot from those that are more anatomically efficient and ordinarily subject to those stresses produced in good form (Frankel & DiFiori, 2007).
Anatomical variation also contributes to the relative susceptibility of athletes to metatarsal fractures. Specifically, wider metatarsal regions allow for correspondingly greater surface area available to distribute the mechanical loads to which the foot is subjected during plyometric motion and instantaneous stops, starts, and changes in the direction of intended movement. Similarly, athletes with longer feet in relation to their body weight are predisposed to metatarsal stresses (Vu, McDiarmid, Brown, et al., 2006) because of the increased leverage on the fulcrum area exerted by comparatively longer levers (Barsom. 2005). Flat-footedness is also believed to contribute to the development of metatarsal fractures because that condition also reduces the natural shock-absorbing function of the arch structure of the foot (Cullen & Hadded, 2004).
Partly because anatomical variation contributes to the development of metatarsal fractures, footwear is particularly important to mitigating any existing predisposing factors to the condition. While conflicting data as to the effect of hard surfaces call into question the assumption that surface density is directly related to metatarsal problems (Laker, Saint-Phard, Tyburski, et al., 2007), the insufficient cushioning properties of athletic footwear likely increases the overall risk nevertheless.
Proper fitting, particularly in the lateral dimension (i.e. width) is directly related to increased susceptibility to metatarsal problems because it further (artificially) contracts the overall surface areas available to dissipate and absorb dynamic forces by squeezing the metatarsals closer to each other as well (Cullen & Hadded, 2004). Finally, excessive roominess in athletic footwear can also contribute to stress fractures and other debilitating foot problems by allowing the foot to develop momentum within the shoe and resulting in momentarily high loads when the foot rapidly decelerates against the walls of the shoe
Injury Treatment in the Acute Phase:
As always, the primary treatment for athletic injuries involving inflammation or trauma begins with rest, ice, compression, and elevation (RICE), all designed to minimize the accumulation of blood and synovial fluid that retards healing by inhibiting the supply of oxygenated blood to the injured tissue and by requiring the its gradual breakdown and re-absorption. Metatarsal stress fractures are associated with significant bone marrow edema (Frankel & DiFiori, 2007) and therefore benefit tremendously from rest and icing in particular.
As in all injuries involving stress fractures to bone, rest and the elimination of weight bearing is crucial (Howe, 2007). Metatarsal fractures heal well provided the athlete suspends participation in any activity that subjects the metatarsals to continued stress of the kind that precipitated the trauma in the first place. Crutches and walking boots are generally sufficient and the patient may continue to ambulate during the healing process. Generally, pain is an appropriately accurate indication in this regard and should be heeded as evidence that the region has been exposed to continual stress capable of delaying or interfering with proper healing (Iazetti & Rigutti, 2007).
During the first phase of rehabilitation, the immediate goals include reduction of the stresses responsible for the development of stress fractures, minimization and reduction of swelling, and pain control. For that purpose, crutches in conjunction with a walking boot are often used for the first week. Usually, the athlete may continue self ambulating provided it does not cause pain. As with athletic injuries in general, continued (or recurring) pain is treated as an indication that the previous phase of rehabilitation has not been sufficient for recovery; therefore continued pain in subsequent phases necessitates a return to this phase of treatment. Generally, a walking boot is used for the first two to three weeks, followed by several weeks of light non-weight-bearing training. The absence of continued or recurring pain in this phase allows a gradual return to athletic activity although not at a strenuous level and only with deliberate limitation of any plyometric stresses (Frankel & Difiori, 2007).
The second phase of rehabilitation consists of a gradual return to light plyometric loading at about six weeks, subject to any discomfort. Provided the patient experiences no discomfort or swelling, exercises are begun to restore neuromuscular control, range of motion, and muscular strength, all of which deteriorate very quickly during any period of immobilization such as associated with the walking cast (Vu, McDiarmid, Brown, et al.,
2006). One of the most productive rehabilitation exercises in this phase consists of reverse (i.e. backwards) stair climbing, because the motion of raising the front of the foot targets the muscles on the front of the shins and also increases flexibility of the ankle joint lost during immobilization in the walking boot (Frankel & Difiori, 2007).
Criteria for Full Return to Athletic Competition
The final phase of rehabilitation transitions to the evaluation phase in which the athlete is evaluated for stability and balance while simultaneously building up cardiovascular and respiratory conditioning to pre-injury levels. At this stage, resumption of training is limited only by recurrence of symptoms, which must be heeded by the return to the previous phase of rehabilitation. Generally, once the athlete can perform a balance test on a narrow block and when vigorous plyometric action produces no discomfort, the athlete is cleared for competition. During this period, the area of injury should no longer produce any pain, even through manual palpitation of the area. Any tenderness in that regard indicates the need to dial back rehabilitation until such tenderness resolves completely. Because of anatomical location of the metatarsal bones, external bracing or taping is not helpful in the manner that it is in connection with toe or ankle injuries.
If the athlete ignores the symptoms associated with metatarsal stress fracture and continues subjecting the injured bones to the stresses associated with high-level athletic activity of the type responsible for the development of the stress fractures, the consequences can be devastating. Instead of a relatively simple period of reduced activity followed by low-level rehabilitation and the likely return to competition with eight or nine weeks, the athlete who ignores the pain associated with stress fractures of the metatarsals (or masks it with analgesics) risks the progression of many micro-
fractures into a complete fracture of the bone necessitating surgical repair, a much longer period of immobilization, and prolonged recovery and rehabilitation. Certain complete
fractures of the fifth metatarsal do not necessarily require surgery, but others do, depending on the precise location of the break and the available blood supply to that area because natural healing without surgical intervention can be much more lengthy (Vu,
McDiarmid, Brown, et al., 2006).
Metatarsal stress fractures are an easily manageable athletic injury that usually require little more than RICE intervention. However, failure to reduce activity and allow healing can result in the development of a complete fracture, often requiring surgical repair and prolonged healing. Therefore, one of the sports trainer’s responsibilities is to monitor athletes who report metatarsal pain and to provide appropriate medical guidance throughout the entire cycle of the injury from initial diagnosis through each phase of immobilization, rehabilitation, post-injury assessment, and return to competition.
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