Case 25 – Running MT
A 42 year old long distance runner presents with right foot pain. Pain is worse with weight bearing. He has a PMHx of stress fracture. No recent change in training, runs about 70km/week. Pain began when he was on a 30 km trail run and stepped on a rock with his right foot.
On exam, swelling over right foot and point tenderness on palpation of second metatarsal shaft. Pain also elicited with the application of axial load to the second toe. No changes in sensation or pedal pulses. No signs of compartment syndrome.
Figure 1: AP view of the right foot showing a distal shaft fracture on the second metatarsal
Figure 2: Oblique x-ray of the right foot showing a distal shaft fracture on the second metatarsal
Figure 3: Lateral view of the right foot. Fracture is more difficult to visualize due to metatarsal overlap. z
The metatarsals are numbered from first (the largest) to fifth (the smallest). Metatarsal fractures can be categorized into fractures of the first metatarsal, central metatarsals, and fifth metatarsal. Central metatarsal fractures will be discussed here.
Most fractures are minimally displaced due to the splinting by adjacent metatarsals and abundant ligamentous and muscle attachments. The central metatarsals (second, third and fourth) articulate with all cuneiforms and the cuboid, respectively (see figure 4). There are also a series of three ligaments that attach each metatarsal to its neighbour, except there is no such connection between the first and second metatarsal bases. The second metatarsal is linked to the medical cuneiform by the Lisfranc ligament.
Initial assessment should include an inspection for signs of skin damage. Wounds may indicate open fracture, while tenting may appear over a displaced fracture. Common findings include swelling and ecchymosis. On exam, palpation along each metatarsal for point tenderness can reveal fracture site. Applying axial load to each metatarsal can differentiate fractures from soft tissue injury. Pain is produced with axial loading if metatarsal is fractured. The Lisfranc joint area should also be palpated. Tenderness in this area may indicate a Lisfranc injury, which requires referral to an orthopedist. Finally, signs of compartment syndrome should be considered: disproportionate pain, pallor, parenthesis, or tense swelling. Pain with passive flexion and extension of toes is an early sign. Compartment syndrome is rare but a dangerous potential complications of metatarsal fractures that requires emergent surgical release.
Standard radiographic imaging should include AP, lateral and oblique views. The AP and oblique views are generally the most useful. Occasionally, fracture lines may not be detectable on initial radiographs but become visible afterwards. Therefore, patients should be managed as though the fracture is present if they have the clinical presentation and imaging should be repeated one to two weeks after the initial injury.
Immediate surgical referral is indicated for all open fractures and fractures associated with vascular compromise or nerve damage. Other indications include fractures involving multiple metatarsals, displaced fractures near metatarsal head, intraarticular fractures, displaced fractures of the first metatarsal, unstable fractures of the first metatarsal, tarso-metatarsal ligament complex injury (Lisfranc injury).
Diagnosis: Non-displaced shaft fracture of the second metatarsal
Immobilization in a posterior splint, no weight bearing, elevation for first 24 hours. Follow-up visit in three to five days. If pain is still being experienced with minimal weight bearing, a short-leg walking cast may be necessary once swelling is reduced. If not, issue a firm, supportive shoe with progressive weight bearing. Repeat radiographs in seven to ten days to ensure fracture remains non-displaced. If fracture position is good, cast should be worn for another three to four weeks with progressive weight bearing. Once cast is removed, range of motion, stretching, and strengthening exercises should be initiated.
Figure 4: Superior view of the bone anatomy of the right foot.
Lucas Nguyen (Aug 6, 2019 PR ND)