Lower Leg Pain in a Runner

PATIENT PROFILE:

A 17-year-old girl who is a competitive cross-country runner presentswith exercise-induced pain in the lower left leg that hasbeen present for 2 months. She describes the pain as a feelingof tightness that begins after 20 to 30 minutes of running; thistightness usually resolves within 15 to 30 minutes after shestops. During the past 3 weeks, the tightness has been accompaniedby a cramp-like pain. The patient runs before and afterschool about 12 miles each day. In addition to running, she hasalso begun playing flag football during the past 2 weeks. She isotherwise in good health.The pain is now so severe that she cannot continue running.There is no history of trauma or past injury to the lower leg.The patient'sfather thinksher performance has decreased this year; racetimes have increased and her form and stridelook different.WHAT WOULD YOU DO NOW?

A.

Consider medial tibial stress syndrome(periostitis).

B.

Evaluate for exertional compartmentsyndrome.

C.

Keep tibial stress fracture in the differential.

D.

Check for tennis leg (gastrocnemius tear).

E.

Rule out popliteal tendinitis.

F.

All of the above.

THE CONSULTANT'S CHOICE

All of the conditions listed are worthy of consideration(choice

F

), although some can be ruled out fairlyquickly. Exercise-induced lower leg pain is a common conditionamong competitive and recreational athletes. Shinsplints (a term often used to describe exercise-inducedlower leg pain) account for 10% to 15% of all running injuries

¹

.Because this patient's pain is located in the anteriorportion of the lower leg and is chronic, tennis leg(gastrocnemius tear, choice D) and popliteal tendinitis(choice E) are not likely. Tennis leg has an acute onset,and the pain is located in the popliteal fossa. Poplitealtendinitis is a chronic condition, but the pain is located inthe posterior knee close to the lateral femoral condyle.Choices A, B, and C are all reasonable diagnostic possibiland a focused physical examinationshould help you make the diagnosis.Medial tibial stress syndrome(MTSS, choice A) is caused by tractionon the tibial periosteum by thetibialis posterior, flexor digitorumlongus, and soleus muscles. The posteriorlocation of these muscles leadsto pain on the posterior medial aspectof the tibia

(Figure 1).

Palpationalong the posterior medial portion ofthe tibia from just below the knee tothe medial malleolus will elicit pain.Patients with MTSS may have increasedpronation of the involved footand resisted plantar flexion; standingon tiptoe on the affected side maycause pain.The tibia is the most commonplace for stress fractures (choice C)in recreational athletes--especiallyrunners. These fractures are often associatedwith an abrupt change in distancerun, running surface, intensity,and/or shoes. Examination reveals aprecise rather than a generalized areaof pain. A tuning fork placed over thetibia usually reproduces the pain inthe specified area. It may be painful for the patient to hopon tiptoe.The muscles of the lower limb are divided into 4compartments that are enclosed by relatively noncompliantfascia

(Figure 2).

Muscles can swell with exercise: theresult is pain and compression of the neurovascular structures(choice B). Weakness and neurologic deficits alsomay appear. The anterior compartment is involved 70% ofthe time, and the deep posterior compartment in 25% ofcases. The lateral and the superficial posterior compartmentsare involved in the remaining 5% of injuries.

²

Theanterior compartment contains the extensor componentsof the foot: thus, symptoms of injury would be pain on thelateral side of the lower leg and weakness of dorsiflexion.The deep posterior compartment contains some of theflexor components of the foot; consequently, symptoms includepain on the posterior portion of the lower leg andweakness of plantar flexion.Further questioning of this patient reveals that sheexperiences some foot numbness and dragging of her footat the end of exercise. Her pain is located on the lateral aspectof her leg

(Figure 3)

. Examination after she has runthe 2 miles from her home to the office reveals weaknessof dorsiflexion of the foot and the great toe

(Figure 4)

andtenderness over the muscles of the anterior compartment.Plantar flexion of the great toe and the foot is normal.There is no pinpoint tenderness over the tibia or fibula.The tuning fork test is negative. No pain is noted over theposterior medial aspect of the tibia.At this point, results of the physical examinationseem to point to a compartment syndrome, althoughstress fracture and MTSS remain possibilities. Confirmationis needed.

WHAT WOULD YOU DO NOW?

A.

Order an MRI scan.

B.

Obtain a bone scan.

C.

Obtain a plain radiograph.

D.

Measure compartment pressure.

THE CONSULTANT'S CHOICE

The plain film (choice C) will not be too helpful.Stress fractures are not always visible, and the other diagnosticconsiderations are not visible on a plain radiograph.The lack of pinpoint tenderness and a negative result onthe tuning fork test make a stress fracture unlikely; thus, abone scan (choice B) is not of help in this setting. An MRIscan (choice A) can aid in the diagnosis of MTSS, but it isexpensive overkill for a condition that can be diagnosedclinically. Moreover, the presence of pain on the lateral aspectof the lower leg and the lack of pain over the posteriormedial aspect of the tibia make MTSS unlikely.Foot numbness, dragging of the foot at the end of exercise,and the location of the pain all point toward a diagnosisof anterior compartment syndrome. Measuring thecompartment pressure (choice

D

) is the most appropriatetest to confirm the diagnosis. Imaging is not indicated.Compartment pressure is measured with an indwellingslit catheter placed into the painful area of theleg. Once the catheter is inserted, the patient is asked toexercise, walk, or jog on a treadmill until symptoms arereproduced or the patient is unable to continue. Restingpressure, immediate post-exercise pressure, and continuouspressure measurements for 30 minutes after exerciseare key to confirming the diagnosis. The result is consid-ered positive if the resting pressure is 15 mm Hg or higher,if the immediate post-exercise pressure is 30 mm Hgor higher, or if the pressure at 15 minutes post-exercisefails to return to normal or exceeds 15 mm Hg.

³

This patient'stest indicates that she does have anterior compartmentsyndrome.

WHAT WOULD YOU DO NOW?

A.

Advise the patient to participate in a sportthat does not require running.

B.

Refer her for physical therapy to learnstretching exercises.

C.

Inject the anterior compartment withcorticosteroids.

D.

Refer her for fasciotomy.

THE CONSULTANT'S CHOICE

The symptoms will improve if the patient discontinuesrunning (choice A), but most athletes will not acceptthis as an option. Physical therapy (choice B) may beuseful if muscle weakness is present, but it is usually notof much help with the primary problem. Corticosteroidinjection (choice C) is contraindicated for a compartmentsyndrome. The most effective treatment--and theoption usually chosen by most athletes--is fasciotomy(choice

D

).This patient underwent fasciotomy to decompressthe contents of the compartment. The area was allowed toheal

(Figure 5)

by secondary intent. She was unable toparticipate in sports activities for 3 months after surgery.Now, in college, the patient participates in intramuralflag football and softball and is a recreational jogger.
(She is not involved in other competitive sports by personalpreference.) Two years after surgery, she remainsasymptomatic.

References:

REFERENCES:

1.

Bates P. Shin splints-a literature review. Br J Sports Med. 1985;19:132-137.

2.

Touliopolous S, Hershman EB. Lower leg pain. Diagnosis and treatment ofcompartment syndromes and other pain syndromes of the leg.

Sports Med.

1999;27:193-204.

3.

Pedowitz RA, Hargens AR, Mubarak SJ, Gershuni DH. Modified criteria forthe objective diagnosis of chronic compartment syndrome of the leg.

Am J Sports Med.

1990;18:35-40.