Metatarsal Fractures (1st to 4th)
Metatarsal fractures are among the most common injuries to the foot. They can either occur in isolation or in conjunction with concomitant other injuries to the foot and other metatarsals.
They are ten times more common than Lisfranc injuries. Fifth metatarsal is reported to be the most commonly injured. These fractures have been reported to occur most commonly in women, particularly elderly women.
Mechanism of injury may be direct, indirect or repetitive trauma. Direct injuries include falls, motor vehicle accidents, crush injuries or a fall of heavy objects. Indirect injuries include falls on plantarflexed and fixed foot or inversion injuries. Repetitive strain can cause stress type fractures.
For clinical purpose, metatarsal fractures are classified by anatomic location as base, shaft and neck fractures.
AP, lateral, and oblique radiographs of the foot are routinely obtained, ideally with the patient bearing weight, however due to initial pain and swelling, weight bearing views may not be possible.
Majority of these fractures heal uneventfully with conservative treatment, however a small percentage may lead to non-union or mal-union resulting in significant disability and pain.
Undisplaced and minimally displaced fractures are treated conservatively with immobilisation for a period of 4 to 6 weeks. Usual options include a wooden-sole shoe, plaster shoe, walker boot or less frequently a below-knee light weight cast. With any of these options weight-bearing is allowed as per comfort.
In case of first metatarsal fractures, more cautious weight-bearing is advised due to higher risk of displacement in view of excessive load bearing on the medial column.
Majority of these fractures heal within 6 weeks and recovery back to normal activities follows soon after. This has generally been observed to result in very satisfactory outcome. However, some of these patients may end up with an incompetence or deformity that either exacerbates metatarsalgia or necessitates late surgery.
Surgical treatment is indicated in:
- Open fractures
- Significantly displaced fractures
- Mal-rotated deformities
- Multiple metatarsal fractures
- Fracture angulation >10◦
Sagittal plane displacement is poorly tolerated as it alters the weight-bearing relationship of the metatarsal heads and may result in painful callus and metatarsalgia. Transverse plane displacement is usually better tolerated but can be associated with interdigital nerve impingement. In case of considering surgery, the concept of restoring length, alignment and rotation should be followed.
Surgical options include closed reduction and K-wire fixation, open reduction and internal fixation or in cases of poor soft tissue envelope external fixation may be used. For oblique or spiral fractures, small lag screw fixation can provide additional stability along with plate fixation. Mini-fragment and low profile plates are preferred to avoid soft tissue irritation.
Closed reduction and intramedullary percutaneous K-wire pinning can be performed by either a retrograde or anterograde technique, the former being more commonly practiced.
There are very few studies which report the outcomes of fractures of the first four metatarsals. A study comparing fixation management with K-wire fixation (21 patients) and casting (36 patients) reported no significant difference in outcomes. 56% patients had metatarsalgia. Poor outcomes were considered associated with comminution, sagittal plane displacement, open fractures, or severe soft tissue injury.
An RCT of 50 patients with minimally displaced lesser metatarsal fractures compared cast immobilization with elastic bandage support. All patients achieved radiographic union at mean follow-up of 3 months. Patients with elastic bandage treatment had significantly higher functional scores and less pain.
Multiple metatarsal fractures have traditionally been an indication for surgical treatment. However, there is little objective evidence to support this approach. Although such fixation has the benefit of restoring the anatomy and stability across the forefoot, but also carries the disadvantage of the wires holding the toes in a non-functional dorsally displaced position for several weeks until adequate bony healing permits hardware removal. Subsequently these patients may have a resultant contracted dorsiflexed toes with little MTP or IP motion, chronic pain, difficulty in shoe wear and toe deformities.
Richter Martinus, Kwon John Y., DiGiovanni Christopher W., Chapter 67 - Foot Injuries, Skeletal Trauma: Basic Science, Management, and Reconstruction (Fifth Edition), edited by Browner Bruce D. MD MHCM FACS,Jupiter Jesse B. MD,Krettek Christian MD FRACS FRCSEd,Anderson Paul A. MD, 2015, Pages 2251-2387.
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