COVER ARTICLE PRACTICAL THERAPEUTICS Common Stress Fractures BRENT W. SANDERLIN, LCDR, MC, USNR, Naval Branch Medical Clinic, Fort Worth, Texas ROBERT F. RASPA, CAPT, MC, USN, Naval Hospital Jacksonville, Jacksonville, Florida Lower extremity stress fractures are common injuries most often associated with partic- ipation in sports involving running, jumping, or repetitive stress. The initial diagnosis can be made by identifying localized bone pain that increases with weight bearing or repet- itive use. Plain film radiographs are frequently unrevealing. Confirmation of a stress frac- ture is best made using triple phase nuclear medicine bone scan or magnetic resonance imaging. Prevention of stress fractures is most effectively accomplished by increasing the level of exercise slowly, adequately warming up and stretching before exercise, and using cushioned insoles and appropriate footwear. Treatment involves rest of the injured bone, followed by a gradual return to the sport once free of pain. Recent evidence sup- ports the use of air splinting to reduce pain and decrease the time until return to full par- ticipation or intensity of exercise. (Am Fam Physician 2003;68:1527-32. Copyright© 2003 American Academy of Family Physicians) tress fractures are among the involving repetitive use of the arms, such most common sports injuries as baseball or tennis. Stress fractures of and are frequently managed the ribs occur in sports such as rowing. by family physicians. A stress Upper extremity and rib stress fractures fracture should be suspected in are far less common than lower extremity Sany patient presenting with localized stress fractures.1 bone or periosteal pain, especially if he or she recently started an exercise program Etiology and Pathophysiology or increased the intensity of exercise. Stress fractures of the lower extremity Other possible sources of bone pain, most commonly involve the tibia and including metastatic lesions, should be metatarsal bones.1,2 Stress fractures of the Members of various considered. fibula, the navicula, the pelvis, and the family practice depart- Stress fractures can result from partici- femoral neck of the femur are less com- ments develop articles pation in many activities and sports, mon.1 Although several factors appear to for “Practical Therapeu- tics.” This article is one especially those requiring running and contribute to the development of stress 1-9 in a series coordinated jumping. Athletics, or track and field fractures (Table 1), they generally occur by the Department of sports, account for 50 percent of stress as a result of a repetitive use injury that Family Medicine at fractures in men and 64 percent in exceeds the intrinsic ability of the bone to Naval Hospital Jack- women.1 Participation in some sports repair itself.3,10 sonville, Jacksonville, Fla. Guest editor of the that are not considered to be high- Two competing, but not mutually series is Anthony J. impact, such as platform diving and row- exclusive, theories may explain the devel- Viera, LCDR, MC, USNR. ing (crew), also may cause stress frac- opment of stress fractures. One theory tures, particularly of the metatarsals and holds that during the initial increase in ribs. Hockey, golf, swimming, fencing, exercise activity, the osteoblastic activity and softball have very low reported inci- lags behind osteoclastic activity by a few dences of stress fractures.1 weeks, resulting in a period during which This article reviews common stress bone is more susceptible to injury. Tor- fractures of the lower extremity, espe- sional and bending stress forces from See page 1461 for cially those involving the tibia, fibula, and repetitive use result in microfractures definitions of strength- metatarsal bones. Stress fractures of the that consolidate into stress fractures.2,4,11 of-evidence levels. upper extremity may occur in sports The other theory emphasizes strong and Downloaded from the American Family Physician Web site at www.aafp.org/afp. Copyright© 2003 American Academy of Family Physicians. For the private, noncommercial use of one individual user of the Web site. All other rights reserved. Approximately 60 percent of persons with a stress fracture TABLE 1 have had a previous stress fracture. Risk Factors for Stress Fractures Participation in sports involving running and jumping Rapid increase in physical training program repetitive stress on bone at the insertion point Poor preparticipation physical condition of muscles, resulting in focal bending stresses Female gender beyond the ability of the bone to tolerate.3,4,10 Hormonal or menstrual disturbances Stress fractures often occur in nonathletes Low bone turnover rate or deconditioned persons who begin a new Decreased bone density exercise program, such as military re- Decreased thickness of cortical bone cruits.2,3,4 Women are generally more likely to Nutritional deficiencies (including dieting) develop stress fractures than men. In women, Extremes of body size and composition nonathletes undertaking unusual activity are Running on irregular or angled surfaces more likely to develop stress fractures than Inappropriate footwear athletes, except for those athletes who exer- Inadequate muscle strength cise to the point of amenorrhea.1-3,5,12 In both Poor flexibility men and women, stress fractures tend to “Type A” behavior recur. Approximately 60 percent of persons with a stress fracture have had a previous Information from references 1-9. stress fracture.13 Tibial fractures are the most common lower extremity stress fracture,1,3 accounting for site.14 Anterior stress fractures of the tibia usu- approximately one half of all stress fractures in ally result from tension stress and have a children and adults.1,14 Stress fractures of the higher incidence of nonunion than antero- tibia are especially common in sports involv- medial fractures. ing running and jumping.2,3 In children, tibial Metatarsal fractures represent approxi- stress fractures usually occur in the anterior mately 25 percent of stress fractures.1 These proximal one third of the bone, whereas in fractures most often involve the distal second adults, the junction of the middle and distal and third metatarsals and are least common in one thirds seems to be the most prevalent the fifth metatarsal.3 Second and third meta- tarsal fractures are common in military recruits marching for the first time in combat boots (hence the term “march fracture”), and The Authors in ballet dancers involved in dancing on the 3,15,16 BRENT W. SANDERLIN, LCDR, MC, USNR, is a family physician at Naval Branch Med- tips of their toes (i.e., “en pointe”). Fifth ical Clinic, Fort Worth. He received his osteopathic degree from Texas College of metatarsal stress fractures are less common Osteopathic Medicine at the University of North Texas Health Science Center, Fort Worth, and completed a residency in family practice at Naval Hospital Jacksonville, and must be distinguished from Jones frac- 15 Jacksonville, Fla. tures or avulsion fractures. Fifth metatarsal ROBERT F. RASPA, M.D., is currently a faculty member in the family practice residency fractures are more common in patients with program at St. Vincent’s Medical Center, Jacksonville, Fla. He is a retired captain of the varum stresses of the foot or knee (genu U.S. Navy Medical Corps. He received his medical degree from West Virginia Univer- varum). The latter are more prone to sity School of Medicine, Morgantown, and completed a residency in family practice at 15 Naval Hospital Pensacola, Pensacola, Fla. nonunion. In adults, approximately 10 percent of stress Address correspondence to Brent W. Sanderlin, LCDR, MC, USNR, Naval Branch Med- ical Clinic, Naval Air Station, Fort Worth JRB, 1711 Doolittle Ave., Fort Worth, TX fractures occur in the fibula (20 percent in 14 76127. Reprints are not available from the authors. children). They most commonly occur in 1528 AMERICAN FAMILY PHYSICIAN www.aafp.org/afp VOLUME 68, NUMBER 8 / OCTOBER 15, 2003 Stress Fractures A stress fracture may not be evident on initial or delayed radiographs; magnetic resonance imaging or bone scan may be necessary for diagnosis. senting only about 5 percent of all stress frac- tures.1 They are, however, extremely impor- tant because they are difficult to diagnose and have a high incidence of fracture nonunion, complete fractures, or avascular necrosis, which may result in an unrecoverable injury.3 Femoral stress fractures are more common in endurance athletes.1 Diagnosis Stress fractures of the lower extremity pre- sent as localized dull pain not associated with trauma that worsens during exercise or weight bearing.2,17 Localized swelling or periosteal thickening may occur at the pain site. The dif- ferential diagnosis includes “shin splints” (periosteitis), compartment syndromes, and nerve or artery entrapment syndromes.2 Ten- derness to palpation typically is present at the injury site and is the hallmark of a stress frac- ture.2,17 In femoral fractures, patients usually FIGURE 1. Stress fracture of the distal second metatarsal. Initial radiographs are often complain of pain in the groin, anterior thigh, unhelpful and do not show evidence of frac- or knee, as well as painful range of motion of ture. The diagnosis can be retrospective when the hip.3 based on callus formation. Plain film radiographs generally should be obtained in the initial evaluation but may not reveal a stress fracture soon after the symp- the distal one third (especially in children) but tom onset (Figure 1).17 Evidence of a fracture also may occur in the proximal one third of may never appear on plain radiographs or the fibula.3,14 may not appear for two to 10 weeks after Navicular fractures are the most common symptom onset.3,17 Repeat radiographs ob- stress fractures of tarsal bones, with calcaneus tained during the convalescent phase reveal fractures accounting for almost all of the the fracture in approximately 50 percent of remainder.1 These fractures are often associ- cases. The appearance of what has been called ated with jumping and sprinting sports such “the dreaded black line” (a transverse fracture as athletics or basketball.