Young Man With Painful Swelling on the Medial Shin

Figure 1

Figure 2

A 19-year-old athlete complains ofpain and swelling of the anteriorpretibial area of his right lower leg. Hehopes to win a football or track scholarshipto college and is concernedbecause his symptoms are impairinghis performance.

History. The symptoms startedabout 6 months earlier when he experienced"shin splints" during thespring track season. He specializedin the 100- and 200-meter dashes.After the season ended, the pain andswelling began to resolve; however,these symptoms returned duringfootball workouts in the fall.

When he made sharp cuts onthe field or accelerated quickly,the pain increased. He was told bythe coach that the injury was a bruiseand was advised to continue practice.With the regular exertion ofpractice and the season's games, thesymptomatic area became moreswollen. He now experiences painwith simple weight bearing.

There is no history of rednessat or drainage from the site, jointpain, fever, or generalized legedema. Although he plays running back and is tackledfrequently, he has had no penetrating or other leg injuryexcept for the usual bruises.

Examination. The patient is muscular and well built.Pulse rate is 60 beats per minute; respiration rate, 18breaths per minute; blood pressure, 110/80 mm Hg. Theonly abnormalities noted are a tender 3 X 4-cm slightlyrubbery soft tissue mass overlying the lateral aspect ofthe middle of the right tibial shaft, and a discrete bonynodule or prominence on the anterolateral tibial surface.The patient rates the pain as 6 on a scale of 1 to 10. Thereis no fluctuation, erythema, or drainage. Knee and anklejoints are normal. No inguinal adenopathy is noted, andthe neurovascular status of both lower legs is normal forhis age and level of conditioning.

Anteroposterior and lateral plain radiographic viewsof the tibia are ordered.

What do the films show-and to what diagnosis dothese findings point in light of the patient's history?

Radiographic findings.

Views of the tibia and fibula demonstrate a prominent focal area of corticalthickening (

Figure 1

). In addition, there is a black line fracture with adjacent periosteal reactionand sclerosis that involves the anterolateral aspect of the distal portion of the middle third of the tibialdiaphysis. These findings, which indicate chronicity and attempted cortical healing, most likelyrepresent a

stress fracture

in light of the patient's history.Mildly prominent anterior soft tissue thickening prompts mention of the much less likely differentialdiagnosis of chronic osteomyelitis, which is characterized by periosteal elevation at the site ofthe bony lesion. However, the typical inflammatory changes of the overlying skin, such as rednessand purulent drainage, are absent in this patient.

Orthopedic consultation.

The patient is instructed to use crutches to avoid weight bearing;an orthopedic evaluation is scheduled for the next day.The orthopedic surgeon prescribes a walking boot for at least 4 to 6 weeks and allows ambulationas tolerated. Physical activity is limited to swimming, exercise-bike riding, and leg-strengtheningexercises; the patient is advised to refrain from running, jumping, and leg pounding activitiesfor the next 4 to 6 weeks.

One-month follow-up.

The patient reports that he has had no pain associated with walkingin the boot, which he has consistently worn while exercising. There is no palpable tenderness atthe fracture site, which is still marked by a bump on the bony anterior part of the tibia. He experiencesno pain with fulcruming of the tibia. Radiographs show that the fracture is starting toheal; however, a defect (lucency) is noted in the anterior cortex of the tibia on the lateral view(

Figure 2

).The patient is allowed to return slowly to strenuous activity. He starts with slow, easy jogging--no more than a mile at a time--and conditioning and strengthening exercises.

Seven-week follow-up.

His physical activity has increased, although he experiences somesoreness when he runs. A minimally tender bony nodule is still present on the tibia. A radiographshows that the stress fracture of the anterior tibial cortex is healing (

Figure 3

). The healing reactionis much more prominent on this film than on the previous one.

Outcome.

The patient slowly returns to full activity over the next 3 weeks and resumesfootball practice 10 weeks after the stress fracture was initially diagnosed. Six months later, thefracture site has remained stable despite his full participation in football training.

IMPLICATIONS FOR PRACTICE

Clinical features.

Stress fractures are frequently occultin the sense that they represent traumatic bone injurybut often are not visible on plain radiographs for upto 2 to 3 weeks after the onset of pain. These fracturesoccur in normal bone that is subjected to abnormal activitylevels. The classic example is the "march fracture."Typically, the patient has gone on a long walk or"march" and has no clear history of preceding trauma.Examination reveals tenderness at the middle of theshaft of the third metatarsal, which is the bone most frequentlyinvolved. Pain and tenderness are the hallmarkpresenting complaints of a fracture. The symptoms areusually well localized to the fracture site but can appear tobe somewhat more generalized or diffuse if there is significantassociated soft tissue injury. Loss of normal functionmay also be noted, but in patients with incomplete fractures(such as stress fractures) the functional impairmentmay be minimal.

Radiographic features.

Initial radiographs are normalin patients with stress fracture, but within 2 weeks acallus appears in the midshaft of the metatarsal. Appropriateimmobilization is required if a fracture is suspectedbased on bony tenderness, even though it is not visualizedon plain films.

Role of bone scanning in this setting.

If immobilizationfor 1 to 2 weeks is not practical or if the diagnosis mustbe rapidly confirmed, radionuclide bone scanning may behighly useful because it generally reveals the metabolic disturbanceat an acute fracture site within 24 hours (Box).This imaging study is helpful in evaluating certain sites,such as the femoral neck and the navicular bone at thewrist, that are notorious for having occult, nondisplacedfractures that do not appear on initial plain films. Bone scanningcan also detect fractures of such structures as thescapula, sternum, sacrum, and portions of the pelvis thatare anatomically difficult to image with plain radiographs.

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KEY TAKE-HOME POINTS

This case illustrates 3 key points in managing stressfractures:

• Suspect stress fracture if a patient who presents with legpain has recently engaged in intensive repetitive activity,such as a long walk, or has started to participate in a highlevelathletic activity, such as football or track.
• Apply immobilization based on the findings of pain andbony tenderness--even if plain films are normal--becauseit may take up to 2 weeks for stress fractures toappear on radiographs.
• When clinical decision making requires prompt confirmationof fracture, such as in a patient with hip pain, considerradionuclide bone scanning.

References:

REFERENCE:1. Stevens C. Special imaging techniques. In: Simon RR, Koenigsknecht SJ, eds.Emergency Orthopedics: The Extremities. 3rd ed. Norwalk, Conn: Appleton &Lange; 1995:chap 5.