Metatarsal stress fractures are microfractures, affecting the second and third metatarsal diaphyses and are a result of constant stress due to the supporting of weight.
One of the first symptoms described by patients with a metatarsal stress fracture is pain on the front part of the foot, typically felt after strenuous exercise, of which the individual is relieved as soon as they stop the activity. It is initially felt as a widespread painful sensation but then persists at the fracture's region. If the patient continues to engage in physical activity, the time required for the painful sensation to emerge becomes progressively less, thus discouraging the individual from performing any type of physical activity. At its most severe stage, a metatarsal stress fracture will cause pain and discomfort even while resting. Patients typically report a period preceding the aforementioned symptomatology, when they experienced pain on the fifth metatarsal (proximally).
In case of female athletes reporting such symptomatology, the existence of the athletic triad should be investigated (osteoporosis, amenorrhea and athletics [19] [20]).
The most basic difficulty in diagnosing a metatarsal stress fracture is that the plain x-ray often reveals no findings. At the initial stages of the fracture, namely during the first 2-6 weeks, radiographs may still appear normal [19] [21], and half of the cases never produce x-ray findings, even after 3 months have passed. The importance of a plain radiograph lies in its ability to differentiate a fifth metatarsal stress fracture from a true Jones fracture.
On the other hand, the most widely chosen method of imaging to detect a metatarsal stress fracture is the Technetium-99 (99m Tc) diphosphonate 3-phase bone scanning [22] [23], as it displays a 100% sensitivity and a lower specificity. It is able to illustrate a stress fracture even as soon as 24 to 72 hours after symptomatology has first been observed and can additionally distinguish stress fractures from stress reactions.
Lastly, an magnetic resonance imaging (MRI) scan and a single-photon emission computed tomography (SPECT) can also be performed to detect a metatarsal stress fracture, with the MRI featuring greater specificity for the condition [24] [25] [26].
Often, a clinical diagnosis suffices and bone scanning or MRI are reserved when there is a need to make a prompt diagnosis. It is also recommended that women exhibiting metatarsal stress fractures undergo a bone density evaluation, as the fracture may be a first sign of osteoporosis.
Upon the diagnosis of a metatarsal stress fracture, the activity that has led to it should be discontinued. The patient is advised to wear a wooden-sole shoe and remain at rest in order to allow for the healing procedure to start. Elevation of the limb and compresses of ice are also recommended. Should there be no sign of symptom relief, the foot should be placed in a short walking cast. The types of activity allowed during the healing period involve bicycling or aqua running and any other type of physical activity that does not exert pressure on the foot.
Third and second metatarsal stress fractures normally require no other type of intervention and continuity is fully restored. Individual that have suffered a fifth metatarsal stress fracture and typically engage in increased physical activity may have to undergo a reparatory surgical procedure to correct the fracture using bone graft and/or screw fixation [27]. Should the patient be less active, the walking cast can be placed for six to eight weeks and the aforementioned surgical procedure is reserved for those who eventually develop a nonunion [28].
After the treatment plan has come to an end, the patient can resume daily activities and take care not to exert overuse of the affected foot. The activities of cycling and aqua running are also beneficial in this phase.
During the next period of time, physical activity should be increased at a rate of 10% per week, with resting periods inbetween. Any indication of relapse and recurring symptomatology is an sign for rest and less physical exertion.
In case of a persisting lack of continuity, surgical therapy may be applied [27]. Should the nonunion consist of fibrous material that does not cause symptoms and physical restriction, it may remain untreated, but any other case should be addressed surgically. In general, patients may need to be prescribed painkillers at the first stages of the healing process and should be advised not to re-engage in physical activity too soon, for fear of a relapsing stress fracture. The healing period lasts approximately from six to twelve weeks.
Metatarsal stress fractures affecting the first, second, third or fourth metatarsal normally recover to a full extent without any complications.
Regarding the fifth metatarsal, its state of hypoperfusion contributes to its diminished ability to recover its continuity after a stress fracture (nonunion), which is observed at a rate of 35-50% according to literary data.
Metatarsal stress fractures are a result of a repeated action carried out with this region of the body. Should the regional muscles become fatigued, they lose the ability to absorb physical stress and pressure, which are forced on the metatarsal bones [2] [10].
The continual weight and pressure caused by activity that allows for little rest time, thus rendering the location unable to heal, causes damage of microscopic extent. This happens because the actual force exerted on the foot is not adequate to cause an actual fracture. In the majority of the cases, metatarsal stress fractures are triggered by an unusual increase of athletic activity, either in frequency or duration; the metatarsal region is suddenly subject to new levels of pressure to which it was formerly unaccustomed and the balance between the force exerted and the force it is able to absorb is disturbed. Abruptly increased physical activity may lead to stress fractures even in individuals who are not professional athletes.
Data on metatarsal stress fractures is limited to professional athletes or soldiers, as there are no formal studies regarding the general population. This type of fracture is considered to be the second most frequent type of damage sustained by athletes [11].
More specifically, the vast majority of metatarsal stress fractures affect the 2nd and 3rd metatarsal at a rate of nearly 90% [11] [12] [13], and amongst the sub-category of professional athletes, they constitute 10-20% of the injuries they sustain [14] [15]. As far as military personnel is concerned, 23% of the injuries reported are indeed metatarsal stress fractures [16].
The activity of walking exerts greater pressure on the second and the third metatarsal shafts, which accounts for these bones' greater susceptibility to stress fractures. Furthermore, another less possible location of microfracture is the fifth metatarsal, which is required to absorb more stress if a person raises the medial margin of the foot excessively when walking. It is also considerably hypoperfused and therefore challenging to treat, as its ability to recover is substantially impaired physiologically [17] [18].
It is important for doctors, athletes, coaches and parents to be informed of the existence of metatarsal stress fractures as they are a silent threat to the continuity of the foot bones. Professional athletes and coaches should take extra care in order to adapt training schedules in such a way, so as to include breaks and periods of rest. Upon the manifestation of any symptom similar to such a condition, the individual should rest and resume activity at a slower rate, building up the strenuous activity gradually, rather than abruptly.
The second and third metatarsal are the metatarsal locations most prone to stress fractures. This type of fracture makes up 20% of the total lower extremity fractures caused by exertion of stress [1] [2]. They are frequently observed in patients whose routine and occupation exerts great levels of stress on that region, like athletes, runners, soldiers and other military recruits, ballet dancers, as well as patients suffering from neuropathic conditions and rheumatoid arthritis [3] [4] [5]. Metatarsal bone fractures are challenging to treat conservatively and may also require surgery, as the bone continuity between the fragments may not be completely restored otherwise [6] [7] [8].
Metatarsal stress fractures may occur proximally, namely at the metatarsal base, or distally. They are caused either by prolonged exertion of stress on the area or by a sudden increase of the stress. Symptomatology usually includes tenderness at the location of the fracture and, possibly, pain due to axial loading of the metatarsal head [9]. Should such a microfracture be left untreated, symptoms deteriorate and it is also possible that it will lead to a clinically evident fracture.
Stress fractures are not actual disruptions of a bone's continuity, but micro-damage sustained from repetitive activity that stresses the mid-foot, or metatarsal bones.
In contradistinction to true fractures which happen when an instance of extreme force is exerted on the foot, in the sense of a severe fall or blow, stress fractures are formed silently, over a period of time. The foot relies on its musculature to protect underlying structures when a person engages in physical activity; should a person overuse the muscles, the latter become fatigued and the pressure is transferred to the metatarsal bones themselves. If these circumstances happen repeatedly, as in professional athletes, ballet dancers, people who walk long distances carrying weight or wearing inappropriate shoes, the metatarsal bones sustain considerable damage.
A person who has sustained a metatarsal stress fracture typically feels widespread pain at the front of the foot when they engage in physical activity. The pain stops when they rest, but upon resuming the activity, the pain is experienced earlier than before. If the condition remains undiagnosed and therefore untreated, an individual may be unable to perform any type of physical exercise at all.
X-rays typically show nothing abnormal during the first 2-6 weeks during which a person feels pain. The stress fracture can be definitively diagnosed at an early stage by performing a bone scan; however, most of the times, a clinical diagnosis suffices.
Treatment includes avoidance of physical exercise, rest, icy compresses and foot elevation, alongside a walking cast or crutches to help support a person's weight. Surgical procedures are performed in cases of fifth metatarsal fractures or fractures of the 2nd and 3rd metatarsal that have failed to heal, even though the latter happens rarely.