Fractures of the Fifth Metatarsal

1. Fractures of the Fifth Metatarsal Anna Quinn Harrelson Radiology-USC-SOM

3. Varieties Proximal -Acute fx of the tuberosity (metaphysis); aka “dancer’s fx” • Jone’s Fx (classic) • Stress Fx of the proximal diaphysis • Acute on chronic diaphyseal fxs Distal

4. ClinicalCommon Signs and Symptoms    -Taking a good history is key to diagnosis and treatment. • Sharp pain, especially with standing or walking    -Tenderness, swelling, and later bruising of the foot    -Numbness or paralysis from swelling in the foot, causing pressure on the blood vessels or nerves (uncommon)… • then of course- physical exam is always crucial.

5. Anatomy

7. Avulsion Fracture • This is the most common- You Will See It! • Sometimes also called a Dancer’s Fractures (fx at the base of the 5th metatarsal) • H&P: sudden onset of pain at the base of the 5th metatarsal, usually after forced inversion with the foot and ankle in plantar flexion. Tenderness, ecchymosis and swelling at the site may be present. • Don’t forget to fully evaluate the distal fibula and lateral ligaments for other injuries.

8. Tuberosity avulsion fracture: Note that the radiolucency is perpendicular to the long axis of the fifth metatarsal. Intra-articular involvement is not present in this example.

9. Avulsion Fracture • Differential: Apophysis (normal in age 9-14); Apophysitis (Iselin’s Dz), Accessory Ossicles • Treatment: Nondisplaced: conservative (elastic wrapping, ankle splints, low-profile walking boots and casts), weight-bearing as tolerated, 3-6 wks until sxs abate Comminuted fxs and those involving more than 30% of the cubometatarsal articulation surface should be referred.

10. Apophysis (arrow) of the base of the fifth metatarsal, common in girls nine to 11 years of age and in boys 11 to 14 years of age. Note the oblique orientation with the radiolucency aligned in parallel to the fifth metatarsal diaphysis.

11. Tuberosity avulsion fracture with intra-articular involvement. This example involves greater than 30 percent of the cubo-metatarsal articulation with displacement. These characteristics help define indications for surgical consultation.

12. “Jones Fracture” • Important Not To Miss! • Within 1.5 cm of the tuberosity • H&P: sudden pain at the base of the 5th metatarsal, with difficulty bearing weight on the foot. Often bruising and swelling will be present. • Mechanism is described as a laterally directed force on the forefoot during plantar flexion of the ankle (ex pivot-shifting in football or basketball with the heel off the ground) Lateral radiograph of the foot. A patient stepped off a curb and sustained a fracture of the proximal aspect of the fifth metatarsal. According to Greenspan, this would be termed a "true Jones fracture." 

13. Some people have all the luck! 1902:Sir Robert Jones Injured himself while dancing around a Maypole at a Military Garden Party

14. Classification/Radiographic Appearance Torg’s Classification • Type I: no intramedullary sclerosis, a sharp, well-delineated fx line and minimal cortical hypertrophy • Type II:(delayed unions) have a fx line that involves both cortices with associated periosteal new bone, a widened fx line with adjacent radiolucency related to bone resorption and evidence of intramedullary sclerosis • Type III: (nonunions) wide fx line with periosteal new bone and radiolucency and complete obliteration of the medullary canal at the fracture site by sclerotic bone

15. Fracture of the fifth metatarsal shaft within 1.5 cm of the tuberosity, type II. This type II fracture includes intramedullary sclerosis, widening of the fracture line and cortical hypertrophy. The history is critical in distinguishing acute type II fractures (delayed unions) from stress-type fractures (see Table 1).

16. Why bother with the classification??? • Prior to the system- there were HIGH rates of nonunion due to disruption of the vascular supply which enter the bone at the metaphyseal-diaphyseal region. • Proper classification of Type I or II can be initially treated conservatively in all but athletes or pts who opt for surgery • Anyone with a displaced fx should be referred

18. Treatment of Jone’s Fracture • Type I: non-weight-bearing short leg cast for 6-8 wks with progressive ambulation after cast removal • Type II: same cast worn longer to allow union- if athlete- surgery (medullary curettage and inlay bone grafting or intramedullary screw fixation) • Type III: operate…of course there may certainly be complications

19. Oblique radiograph of the foot. Two years later the patient returns for continued pain. A radiograph reveals nonunion of the fracture, a frequent complication of the Jones fracture. 

20. “Stress Fracture” • A stress fracture is a break in a bone cause by repetitive stress. There is often no recollection of injury. The patient may simply develop a painful forefoot after some activity, such a walking, sports, or stooping down onto the ball of the foot. • Without proper treatment, this may progress to a overt fracture of the bone. Metatarsal stress fracture may not become apparent on x-rays until a few weeks after the injury. • H&P: Occurs predominantly in younger patients and athletes. Athletes present early in the training season. Patients usually have prodromal pain for weeks to months before presentation. • Sharp pain in the forefoot, aggravated by walking Tenderness to pressure on the top surface of a metatarsal bone. Diffuse swelling of the skin over the forefoot.

21. Stress fxs • Causes Decreased density of the bones (eg. osteoporosis) Unusual stress on a metatarsal due to malposition or another forefoot deformity (eg. bunion) Abnormal foot structure or mechanics (eg. flatfoot) Increased levels of activity, especially without proper conditioning ; Obesity • Treatment: stress fxs within 1.5cm of the tuberosity of the 5th metatarsal may require up to 20 wks of non-weight bearing immobilization and may still result in nonunion, muscle atrophy or persistent pain. • Tx Type II and III stress fxs like acute Jones fxs

23. Diagnosis • Radiography is the first and often the only investigation required for the diagnosis of fractures. X-Ray can be used diagnose all acute fractures, dislocations, and established stress fractures. • Bone scanning is more sensitive than plain radiography and indicated when a stress or acute fracture is suspected and radiographs are negative. Bone scanning is not a specific investigation.

24. Diagnosis • Although MRI is more sensitive than radiography and bone scanning, it is used only for the assessment of soft tissue structures and ligamentous injuries. MRI is the most sensitive technique for imaging stress fractures of the foot and can depict bone marrow edema even before increased uptake is seen on bone scans. • CT scanning is useful for finding avulsion fractures and comminuted fractures to assess for intra-articular extension.

25. Limitations of Techniques • Small avulsions can be missed on radiographs. In the early stages of stress fracture, radiographs can be normal, or they may show only subtle periosteal reaction, which can be easily missed. • Radiography cannot be used to assess soft-tissue and ligamentous disruption. • Although CT and MRI are more sensitive than radiography, they are not cost-effective and not indicated for the diagnosis of fractures. • Although bone scanning is sensitive, it can still miss some stress fractures in the early stages.

26. Treatment • Based on Fracture Type and Classification • Most Injuries respond to Conservative management. • Make sure you know when to refer and what you can treat yourself.

27. “foot notes” • http://www.emedicine.com/radio/topic850.htm • http://www.physsportsmed.com/issues/1998/02feb/shapiro.htm • Duke Orthopaedics; Wheeless’ Textbook of Orthopaedics; www.wheelessonline.com • www.aafp.org