Musculoskeletal Clinics: Foot Pain That Causes a Runner to Limp

PATIENT PROFILE: A 17-year-old student complains of worsening pain on the lateral side of his right foot that began 2 weeks earlier and now causes him to limp. His summer job requires that he stand for prolonged periods and go up and down stairs several times daily; for the past few days, he has had great difficulty with both activities. He does not experience electricity-like pain when he first places his foot on the ground in the morning; rather, the pain increases in intensity as the day wears on. There is no numbness or tingling in his heel, and neither dorsiflexion nor plantar flexion of the foot is decreased. The patient has no history of acute trauma and is in good health. He recently increased his running routine from 20 minutes 3 times a week to 60 minutes 5 times a week to try to lose weight. WHAT IS YOUR PRESUMPTIVE DIAGNOSIS AT THIS POINT? A. Tarsal tunnel syndrome. B. Achilles tendon rupture. C. Tibial stress fracture. D. Metatarsal stress fracture. E. Plantar fasciitis. THE CONSULTANT’S CHOICE This young man has most likely sustained a metatarsal stress fracture (D). The history—worsening pain of 2 weeks’ duration in the setting of a substantial recent increase in running but without acute trauma—is typical of patients with stress fractures. The location of the pain—in the foot and not the shin—makes a tibial stress fracture (C) unlikely. Its location on the lateral side of the foot suggests a fifth metatarsal stress fracture. The absence of pain, numbness, and tingling along the medial side of the heel makes tarsal tunnel syndrome (A) unlikely. Pain when the foot first bears weight in the morning, a hallmark of plantar fasciitis (E), is not present here. Achilles tendon rupture (B) is usually accompanied by diminished plantar flexion and pain in the back of the heel; thus, it is unlikely. Figure 1 – The Thompson test detects rupture of the Achilles tendon. To perform the test, squeeze the gastrocnemius on the affected side while the patient kneels on a chair. If the squeeze elicits plantar flexion, as it did in this patient, the Achilles tendon is intact. A focused physical examination is necessary to help confirm the diagnosis. Performance of the Thompson test (Figure 1) reveals an intact Achilles tendon. Palpation of the medial calcaneal tubercle (Figure 2) elicits no tenderness (this maneuver elicits significant tenderness in patients with plantar fasciitis). Tapping posterior to the midpoint of the medial malleolus, over the posterior tibial nerve (Figure 3), does not produce pain or tingling (Tinel sign); these results suggest the absence of tarsal tunnel syndrome. No tenderness is noted when the tibia is palpated, which rules out tibial stress fracture. However, significant tenderness is noted about half an inch distal to the tuberosity of the proximal fifth metatarsal (Figure 4), which makes a fifth metatarsal fracture very likely. WHAT IS MOST IMPORTANT TO DO NOW? A. Have the patient stop running until the pain is gone and then restart his running program. B. Refer the patient for physical therapy. C. Inject the tender area of the foot with lidocaine and a corticosteroid. D. Obtain a radiograph of the foot. THE CONSULTANT’S CHOICE The patient’s history and examination results strongly suggest a fracture of the fifth metatarsal shaft. A delay in diagnosis increases the chances of nonunion. Thus, obtaining a radiograph of the injured foot (D) is the most important next step. Although stress fractures may not be immediately evident on a radiograph, this patient’s injury has been present long enough (2 weeks) that it is probably visible. Moreover, plain films are easily obtained and relatively inexpensive. If findings on a radiograph are negative for fracture but the history and physical examination strongly suggest it, it would be appropriate to order additional imaging studies—a bone scan and MRI scan, in that order.  Stopping the running program (A) is indicated but will do nothing to confirm the diagnosis. Physical therapy (B) may be appropriate once the diagnosis is established but not as an initial strategy. Injection with a corticosteroid and lidocaine (C) has no place in the care of this patient. A radiograph of the patient’s foot reveals a nondisplaced fracture about 1.5 cm distal to the tuberosity of the proximal fifth metatarsal. The fracture line is sharp with no widening, and no sclerosis is present. WHAT WOULD YOU DO NOW? A. Refer the patient to an orthopedic surgeon.  B. Recommend that the patient wear a woode shoe or a short-leg walking cast. C. Recommend that the patient wear a non–weight-bearing cast. D. Order an MRI scan of the injured foot. THE CONSULTANT’S CHOICE A significant number of metatarsal stress fractures heal without surgery; thus, conservative measures should be employed initially. (In high-performance athletes who need to return to high-stress activity sooner, internal fixation with an intramedullary screw [A] may be indicated.) An MRI scan (D) is not needed at this time because the diagnosis is clear from the radiograph. There are 2 types of fifth metatarsal fractures. The most common type is an acute tuberosity avulsion fracture, also called a “dancer’s fracture.” The usual mechanism of injury is similar to that seen in ankle sprains: acute inversion while the foot is plantar-flexed. Radiographically, the fracture is located on the tuberosity and is perpendicular to the long axis of the fifth metatarsal. The treatment of choice for avulsion fractures is a wooden shoe or walking cast (B). In younger patients who are very active, keep in mind that pain in the region of the fifth metatarsal tuberosity may be the result of apophysitis, rather than an avulsion fracture. In girls aged 9 to 11 years and in boys aged 11 to 14 years, an apophysis is present in this area. Apophysitis can be distinguished radiographically from an avulsion fracture by the appearance of a piece of bone that is parallel to the tubercle of the fifth metatarsal and by the absence of a perpendicular line. The second type of fifth metatarsal fracture occurs at the metaphyseal-diaphyseal junction, within the region 1.5 cm distal to the tuberosity. This fracture is called a Jones fracture, after Sir Robert Jones, who first described the injury (which he himself incurred while dancing). Jones fractures can be acute or the result of repeated microtrauma. Some authors treat these as different entities; however, the radiographic appearance and treatment are the same, regardless of the mechanism of injury. It is important to distinguish between dancer’s fractures and Jones fractures because the chance of nonunion is much greater in Jones fractures. (They occur in an area of diminished blood supply, whereas dancer’s fractures occur in an area where the blood supply to the bone is good.) The history is one key to sorting out the diagnosis. Recurring pain, such as this young man complained of, is often typical of a Jones fracture, while a dancer’s fracture is more likely to be associated with an acute injury, such as an ankle sprain. Finally, the location of the fracture on a radiograph can definitively distinguish between the 2 fracture types: dancer’s fractures occur on the tuberosity of the fifth metatarsal, while Jones fractures occur distal to the tuberosity, at the metaphyseal- diaphyseal junction. Jones fractures have been classified into 3 types, based on their radiographic appearance; treatment is determined by type (Table). Outcome of the case. The patient had a type I Jones fracture. He has responded well to 6 weeks in a non–weight-bearing cast (C ), has returned to school, and has resumed running. He has been advised to increase the intensity of his running routine slowly in the future.