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metatarsal fractures

Metatarsal fractures

The Sports Injury Doctor

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Metatarsal fractures: Break it like Beckham (and Gary Neville and Danny Murphy)

With the 2002 Soccer World Cup long over and England’s modest success a fading memory, the trio of metatarsal injuries that threatened the national side’s campaign still remain in the mind. The publicity that the three-inch-long bone gained from the injury to England’s captain David Beckham, and subsequently from his team mates, Gary Neville and Danny Murphy (these things always come in threes), was unprecedented. Tabloids and broadsheets alike published daily photographs, layman guides, and professional (and not so professional) opinions on metatarsal fractures. The most striking conclusion to be drawn from reading such articles was the lack of consensus on the management and prognosis of this injury. The treatment and rehabilitation that Beckham (and his beleaguered colleagues) received was over and above that which would be administered to the regular fracture-clinic patient. This article aims to provide an overview of metatarsal fractures and their treatment options, and address discrepancies in management that have arisen as a result of media frenzy and speculation.

Description

The metatarsals as a unit in the forefoot provide a broad plantar (on the sole) surface for load sharing. They are mobile in the sagittal plane (up and down) and individually the metatarsal heads can alter position to cope with uneven ground. This even sharing of weight also protects the skin from injury. Metatarsal fractures are usually caused by the blow of a heavy object dropped onto the forefoot or by a twisting injury. Fractures of the shaft can be caused by twisting of the body with the toes fixed, applying torque to the foot. Avulsion (pull-off) fractures occur particularly at the base of the 5th metatarsal.

Stress fractures are common in the second and third metatarsal necks and at the proximal portion of the shaft of the fifth metatarsal. Athletes and soldiers seem to be more prone to this type of injury. A prospective study of 205 soldiers by Milgrom et al(14) showed 184 stress fractures of the lower extremity, 7.6% of which were of the metatarsals. Up to 20% (11% 2nd metatarsal) of stress fractures in athletes and 23% in military recruits are located in the metatarsals (9,12,13).

Diagnosis

Pain, deformity, crepitus, swelling, bruising and increased pain on weight bearing are the cardinal signs and symptoms. Plain x-rays are the first line of investigation. AP (antero-posterior) and lateral weight-bearing radiographs, if possible, should be obtained. The whole foot must be included to rule out other injuries. Specific films may be taken as well if particular injuries are suspected. CT and MRI scans are occasionally obtained to clarify the diagnosis and treatment. If a stress fracture is diagnosed, an underlying cause must be sought, not forgetting metabolic bone disease. A bone scan or MRI may be helpful in confirming the diagnosis.

Treatment

The first, second and fifth metatarsals are more commonly injured than the others. A brief overview of specific injuries to these bones follows:

First Metatarsal

Shorter and wider than the other metatarsals, it also has a lack of interconnecting ligaments between itself and the second metatarsal. This allows for independent motion. The head of the first metatarsal is thought to bear one third of body weight.

Three types of fracture predominate: avulsion, proximal shaft and mid shaft. Any evidence of instability of the fracture requires operative fixation. Fixation can take the form of a simple lag screw, plate (across the cuneiform) or, in the case of a comminuted fracture, an external fixator device. If the fracture extends into the articular surface then an accurate open reduction and bone grafting may be needed.

If there is no evidence of instability or of any other fracture in the forefoot, then a short leg plaster of paris (POP) cast may be applied for 4-6 weeks, weight bearing as tolerated. The present-day alternative is a removable Aircast boot such as that worn by David Beckham. The position of the foot in the cast must be plantigrade (on the soles) with no dorsal pressure on the first metatarsal. Care of the soft tissues must not be neglected. Active and passive movement of the big toe should be encouraged and an orthoses for the longitudinal arch of the foot may be worn for up to a year after the injury. Complications include transfer metatarsalgia where the fracture heals but excess load is taken in the rest of the foot leading to other problems.

Middle Metatarsals

Significant ligamentous structures link the other metatarsals. The role of the other metatarsals is to provide structural support – no muscular insertions exist. There is thought to be a relative resistance to motion from the second and third metatarsals and this may influence why more stress fractures are seen in these bones. With regard to treatment, emphasis, as with first metatarsal fractures, is on the resulting position of the metatarsal head. There are no fixed criteria for acceptable or unacceptable position of the head, but problems of transfer metatarsalgia and shoewear are common if there are significant changes in the normal position of the head. Normally, 10 degrees of deviation in the dorsal/plantar plane or 3-4mm of translation in any plane requires active correction by manipulation or gravitational traction. An Aircast boot or a below-knee POP with weight bearing as tolerated are the mainstay of conservative closed treatment thereafter.

Multiple adjacent fractures or significant soft tissue injuries require open reduction and fixation with K-wires. A plate may be used if the soft tissues are intact. Traction remains an option if control is difficult to achieve or the fracture extends into the head and metatarsophalangeal joint. Conservative treatment, or to hold position after fixation, is a short leg POP cast or an Aircast boot for 4-6 weeks. This may be removable after the first two weeks. Weight bearing is encouraged on the heel, as tolerated.

Fifth Metatarsal

Injury to the fifth metatarsal is common in sporting or athletic pursuits. Fractures are broadly divided into two groups: proximal base fractures and distal spiral fractures. The former is further subdivided by location (zones 1-3) and history of prodromal symptoms.

Zone 1 injuries are typically avulsion (pull off) fractures. The usual mechanism of injury involves sudden inversion of the hindfoot with weight on the lateral metatarsals. This leads to tension on the plantar aponeurosis which inserts into the proximal part of the base of the fifth metatarsal. This type of injury can involve the lateral ankle ligaments and therefore these must be assessed to exclude injury. A direct blow to the area can also result in a comminuted fracture in zone 1. Tenderness over the fracture site and adequate radiographic projections determine the diagnosis. If symptoms are slight, a crepe bandage or similar support for 2-3 weeks is indicated. If symptoms are marked, then a below-knee walking plaster cast or an Aircast boot for 4-6 weeks will suffice. Zone 2 injuries are true Jones fractures (these are specific eponymous 5th-metatarsal base fractures that have a high non- union rate). Adduction of the forefoot leads to a fracture at the proximal metaphyseal-diaphyseal junction. The fracture may extend into the metatarsocuboid joint but is classically distal to the intermetatarsal joint. Non-union is common, and is most often associated with early weight bearing; because of this, treatment with 6-8 weeks of a below-knee POP cast, non-weight bearing, is recommended. In the professional athlete, internal fixation with an intramedullary AO cancellous screw may be considered. Delayed or non-union should be treated with medullary curettage and bone grafting.

Two fractures predominate in zone 3: proximal diaphyseal stress fractures are rare but common in athletes. The remainder are called “dancers’” fractures; rotational force while axially loading with the foot in the plantigrade position is the mechanism of injury. These, if minimally displaced, heal well with conservative management, ie, a non-weight bearing POP cast for up to three months is necessary but weight bearing may commence when the patient is pain free – a plaster bootie can be used and can be converted to an Aircast boot when the fracture becomes less painful. If significant displacement has occurred, then similar fixation options as previously discussed need to be implemented.

Stress fractures

Stress fractures of the metatarsals most frequently involve the second and third, being the longest and the narrowest. The first metatarsal accounts for 7-8%, the fourth and fifth 3%(10). A stress fracture is not the result of a single occurrence, but rather an ongoing process. They are rare before adolescence as is bilateral presentation. Stress fractures are common in army recruits, ballet dancers and athletes through overuse. In sedentary individuals, the cause is usually related to unaccustomed activity. Mechanisms may involve repetitive stress, usually as a result of frequent impact weight-bearing exercise eventually yielding to a fracture due to continued loading. Biomechanical abnormalities, such as excessive pronation, hypersupination, lower extremity malalignment, external or internal femoral rotation and limb- length discrepancy can all lead to an alteration in normal gait, which can then lead to stress fractures. A history of prodromal (or warning) symptoms for weeks or months may be volunteered. There may be redness and swelling as well as pain but this is not always the case. Pain on palpation will usually determine the site of injury. Weight bearing and continued loading will reproduce the pain. Initial radiographs are likely to be normal; callus may be seen on radiographs 2-3 weeks post fracture. A bone scan or MRI will aid diagnosis. When in doubt the clinician should always suspect a stress fracture, even without radiographic evidence, until proven otherwise.

What causes them?

Much work has been conducted to examine the aetiology of stress fractures. Insufficient remodelling of stressed bone, which leads to fatigue related trabecular microfractures, is a popular theory(2,4,6). Local bone deformation has been regarded as an indicator of stress fracture risk, measured by strain gauges for many years (7). The latest model of a strain gauge is a dorsal staple(3). Human studies conducted using this type of gauge revealed that the second metatarsal dorsal strain is significantly higher than other metatarsals(5,8). Excess-bending moments resulting from inactivity or fatigue of the toe flexor muscles are commonly mentioned in the aetiology of metatarsal overuse injuries(5,15,16,17). The most recent in vivo study conducted by Arndt et al (1) using the strain gauge staple, concluded that increased extension loading and fatigue of plantar musculature may influence dorsal second metatarsal strain while maximum tension strains decrease.

First and middle metatarsal stress fractures can be located at any point along the shaft and may involve articular surfaces. Fifth metatarsal stress fractures normally involve the proximal 1.5 cm of the shaft of the metatarsal. The tendency to non-union is common and a similar management policy as with Jones fractures should be borne in mind.

Treatment

The treatment depends on the time the diagnosis was made. In cases of fresh injury, rest, ice, elevation and compression (RICE) are very helpful as well as anti-inflammatory medication. An Aircast boot may be used if weight bearing is to be allowed, but an elastic bandage and non-weight bearing status are adequate. Both types of immobilisation plus total rest and refrainment from exercise/sport for 4-8 weeks are necessary. Metaphyseal fractures heal faster than articular or cortical injuries. The patient can begin rehabilitation when pain free but may not necessarily return to sporting activity at that stage. The patient must have a full range of motion, have redeveloped muscle flexibility and developed strength, endurance, proprioception, agility and cardiovascular reserve before returning to full competition. The reason underlying the stress fracture should be determined and preventative measures for future injury instituted. A good training programme, the use of proper footwear, impact surfaces and orthoses can be important preventative measures to decrease the recurrence of stress fractures. The predictive value of bone-mineral density of the calcaneus for fracture of the metatarsals has been studied. Lidtke & Patel (11) reported a positive correlation between calcaneal density and the four-point bending strength of each of the five metatarsals. However, no correlation between density and fractures has been established. This may be a useful predictive tool for the future. In the athlete, a stress fracture is invariable indicative of overuse and, as such, signals the need to investigate training habits, equipment, mechanics and athletic techniques.

Too many matches

It is interesting to note that the three injured England squad members played significantly more games than the average for their respective clubs; this is partly complicated by the success of the clubs, thus imposing more games on the players in a regular season. Moreover, although the exact type of fractures sustained by these players remains unknown, the relative innocuousness of the challenges or tackles that led to the injuries has been demonstrated clearly on television. The theory of repetitive loading compounded by muscle fatigue leading to a predisposition for stress fractures, seems well-founded in these circumstances. Similarly, the three injuries occurred towards the end of the football season, in which, with the possible exception of David Beckham, the players were fully involved, to an extent which may have left them vulnerable to stress fractures. Further work is indicated with regard to screening vulnerable athletes. It is possible that there is an argument for rest intervals in order for bone strains to decline, but this is merely a hypothesis at this stage. The recent calls by Sven Goran Eriksson and Arsene Wenger to the Football Association to insert a winter break into the football season may prove to have a scientific basis after all.

Summary

Metatarsal fractures are common sports injuries. A low threshold for the diagnosis and treatment of stress fractures is necessary. Very few of these fractures require surgical intervention, but rest and immobilisation are invariably necessary.

Rahul Patel and Fares Haddad

References

  1. Arndt A, Ekenman I, Westblad P, Lundberg A. Effects of fatigue and load variation on metatarsal deformation measured in vivo during barefoot walking. J.Biomech. 2002;35:621-8.
  2. Buckwalter JA, Brandser EA. Stress and insufficiency fractures. Am.Fam.Physician 1997;56:175-82.
  3. Butterman GR, Janevic JT, Lewis JL, Lindquist CM, Wood KB, and Schendel MJ. Description and application of instrumented staples for measuring in vivo bone strain. Journal of Biomechanics 27, 1087-1094. 1994.
  4. Carter DL, Caler WE, Spengler DM, and Frankel VH. Fatigue behaviour of adult cortical bone: the influence of mean strain and strain range. Acta Orthopaedica Scandinavica 52, 481-490. 1981.
  5. Donahue SW, Sharkey NA. Strains in the metatarsals during the stance phase of gait: implications for stress fractures. J.Bone Joint Surg.Am. 1999; 81:1236-44.
  6. Fazzalari NL. Trabecular microfracture. Calcif.Tissue Int. 1993; 53 Suppl 1: S143-S146.
  7. Fries G. (Measurement of tension using expansion measuring strips). Z.Orthop.Ihre Grenzgeb. 1972; 110: 863-6.
  8. Gross TS. Bunch RP. A mechanical model of metatarsal stress fracture during distance running. Am.J.Sports Med. 1989; 17:669-74.
  9. Hulkko A. Stress fractures in athletes. PhD Thesis, University of Oulu, Finland. 1988.
  10. Levy JM. Stress fractures of the first metatarsal. AJR Am.J.Roentgenol. 1978; 130:679-81.
  11. Lidtke RH, Patel D, Muehleman C. Calcaneal bone mineral density and mechanical strength of the metatarsals. J.Am.Podiatr.Med.Assoc. 2000; 90:435-40.
  12. Matheson GO, Clement DB, McKenzie DC, Taunton JE, Lloyd-Smith DR, MacIntyre JG. Stress fractures in athletes. A study of 320 cases. Am.J.Sports Med. 1987; 15:46-58.
  13. McBryde AM, Jr. Stress fractures in runners. Clin.Sports Med. 1985; 4:737-52.
  14. Milgrom C, Giladi M, Stein M, Kashtan H, Margulies JY, Chisin R et al. Stress fractures in military recruits. A prospective study showing an unusually high incidence. J.Bone Joint Surg.Br. 1985; 67:732-5.
  15. Sharkey NA, Ferris L, Smith TS, Matthews DK. Strain and loading of the second metatarsal during heel-lift. J.Bone

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