Diagnosis of a Medial Tibial Stress Fracture by Ultrasound

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1 CASE REVIEW Joseph J. Piccininni, MSc, Dip ATM, CAT(C), Column Editor Diagnosis of a Medial Tibial Stress Fracture by Ultrasound David C. Berry, PhD, ATC Weber State University Y OU HAVE A STRESS FRACTURE. For some athletes, this can be considered a distressing message from a physician. Depending upon the location and severity of the injury, athletes may be required to halt training for up to 10 weeks. Not wanting to alter their training programs or miss any competition, athletes sometimes choose to work through the pain, often prolonging the recovery time or making the condition worse. The literature is full of examples of stress fractures among college aged athletes (18-26 years of age), but little attention has been devoted to the adult recreational athlete (27 years of age or greater). The purpose of this report is to describe the history of a medial tibial plateau stress fracture in a recreational runner, examine possible causative factors, and discuss the use of therapeutic ultrasound as a diagnostic tool. Case Report A 33-year -old male recreational runner (175 cm, 72.7 kg) training for an endurance event (56-80 km/week) began experiencing severe pain along the medial aspect of the left tibiofemoral joint line approximately 20 minutes into an easy run. The pain continued to increase during the first day and was especially noticeable while descending stairs. After several days of complete rest and resolution of the initial pain, the patient attempted a return to running. After 3 minutes of light jogging, the pain returned in the involved limb. At the outset, the patient was treated for pes anserine bursitis using ice, anti-inflammatory medications, stretching, and therapeutic ultrasound (3MHz at w/cm 2 ). Differential diagnoses included medial meniscus tear, osteochondritis dissecans, and femoral condyle contusion. During the second ultrasound treatment, the patient began complaining of intense localized bone pain along the medial aspect of the proximal tibia, forcing the termination of the ultrasound treatment. The patient was referred to an orthopedic surgeon, who ordered radiographs of the left tibiofemoral joint. The patient was also provided with a prescription of Tylenol 800 mg to help alleviate pain. Initial radiographs did not reveal any pathology. To identify the cause of the pain, the physician ordered a magnetic resonance imaging (MRI) scan. The MRI was unremarkable for soft tissue trauma, but T1-weighted images demonstrated a small linear area of low signal intensity at the proximal aspect of the tibia, parallel to the tibial plateau medially and laterally, but more pronounced along the medial aspect (Figure 1). The physician thought that the MRI results suggested a diagnosis of a minimal non-displaced stress fracture of the left medial tibial plateau. The patient was restricted from running but was allowed to participate in cross-training activities, such as swimming and biking, as long as there was no increase in pain and provided that he applied ice immediately after activity. After four weeks of crosstraining, the patient unsuccessfully tried to resume running. He continued with cross-training for another 4 weeks. Ten weeks after the onset of symptoms, the patient began light jogging on a limited basis, gradually increasing running time and distance until he returned to his normal training regimen Human Kinetics ATT 12(2), pp MARCH 2007 Athletic Therapy Today

2 Discussion Stress fractures are most prevalent in athletes between the ages of 18 and In college-aged runners, 1-21% of all injuries sustained are stress Figure 1 An MRI demonstrating a small linear area of low signal intensity along the medial tibial plateau in a male recreational runner. fractures. 2-3 Lower extremity fractures account for 73-95% of all stress injuries in runners. 3-4 The middle and distal third of the tibia are the most common stress fracture sites, 4 with occasional stress fractures occurring on the tibial plateau. 4-6 The prevalence of stress fractures on the tibial plateau due to activity is actually higher in military recruits (31% of all tibial fractures) 7 than in athletes. Stress fractures in adult recreational athletes, such as in this case, can also develop from running, 3,8-9 with the tibia being the primary bone involved. 5,10 Reports of tibial plateau stress fractures in the nonathletic population are often related to causes other than running (e.g., falling, metabolic disorder). 6,11-13 Pathophysiology Clinicians need to consider that there is no single etiology associated with the development of a stress fracture. The development of stress factures is a multifactorial process that adversely affects the ability of bone tissue to positively adapt to the repetitive loads encountered during activity. 14 Fractures typically develop after one initiates an exercise program 15 or as a result of extrinsic and/or intrinsic risk factors (Tables 1 and 2). 3,16,17 Clinicians should pay particular attention Table 1. Intrinsic Risk Factors Associated With the Development of a Stress Fracture Risk Factor Anatomic factors Muscular fatigue Physiologic factors Bone characteristics Clinical Presentation/Activity Excessive subtalar pronation Hindfoot varus and forefoot varus Pes planus and pes cavus Genu varus and varum Leg- length discrepancies Excessive Q-angle Weak or fatigued muscles unable to dissipate mechanical stress effectively Bone may fail on tensile, compressive, or on both sides Rapid bone turn-over rate Poor flexibility Overall conditioning Obesity & poor nutrition Menstrual disturbance Bone cysts Geometry Low mineral density Athletic Therapy Today MARCH

3 Table 2. Extrinsic Risk Factors Associated With The Development of a Stress Fracture Risk Factor Training errors Training surface Shoe type Unaccustomed activities Clinical Presentation/Activity Abrupt increases in frequency, duration, or intensity High total mileage Change in training technique Aggressive increases in total mileage in runners Stairs, sloped or banked surfaces, curbs and irregular surface (grass, sand, and gravel) increase strain Abrupt changes in surfaces that increase external loading Footwear should have good shock absorption properties. Running shoes lose ability to absorb shock after miles. Insoles and orthotics Sedentary lifestyle to intrinsic risk factors (e.g., age, bone composition, and bone density) when dealing with adult recreational athletes, because stress fractures occurring as a result of physical activity appear less common than those occurring from other causes. Therapeutic Ultrasound Considering stress fracture reactions on a continuum, 18 the earlier a clinician can recognize and respond to a stress reaction, the more quickly an athlete can return to full participation. In this case, while being treated with a course of therapeutic ultrasound for what was believed to be pes anserine bursitis, the patient reported increased periosteal pain along the tibial-plateau border. The periosteal pain prompted further diagnostic testing, which demonstrated a small nondisplaced stress fracture of the tibial plateau. This early identification of a stress reaction resulted in a conservative treatment plan that slightly altered the patient s training regimen but still allowed for tissue healing. Mechanics of Therapeutic Ultrasound The increase in periosteal pain associated with the use of ultrasound occurs when the bone tissue molecules respond to acoustic energy. Acoustic energy is mechanical in nature and is transmitted through body tissues as energized molecules jostle against one another, exchanging kinetic energy and creating waves of energy until the waves disperse within the tissue The kinetic energy produced by the energized molecules travel in two modes. Longitudinal waves are associated with the cyclic compression and decompression of molecules in the direction the waves travel. 20 Transverse waves occur when the energized molecules move at a right angle to the direction of the longitudinal wave propagation. 20 In human tissue, longitudinal waves readily pass through soft tissue. When the acoustic interface changes (soft tissue-bone), some longitudinal waves are reflected and become transverse waves. These waves are generated along the outer surface of the bone, which is covered by the periosteum. 20 The periosteum is a highly vascular structure, which also contains an abundance of free nerve endings that generate pain signals when stimulated. 11 The distribution of acoustic energy depends on the frequency of the sound wave and the density of the tissue. 19 The interface between soft tissue and bone is highly reflective. If the path of incoming longitudinal waves and transverse waves coincide, the resultant energy is the sum of the two waves Two waves that are in-phase produces a summated energy level, resulting in a standing wave, which produces heating of the tissue. 21 In the presence of damaged bone, the heating of the periosteum can produce intense pain within the sensitized tissue. Therapeutic Ultrasound as a Screening Tool Use of therapeutic ultrasound to identify stress reactions has been reported with mixed opinions in the 18 MARCH 2007 Athletic Therapy Today

4 literature Moss and Mowatt s 24 examination of tibial shaft stress fractures with radiographs and ultrasound (.75 MHz, intensity 1.0 and 2.0 W/cm 2 ) demonstrated that ultrasound was successful in identifying 96% of the radiographically confirmed fractures. Giladi et al. 21 compared the results of radiography and ultrasound testing (intensity 2.0 W/cm 2 ) to the result of a bone scan, which was used as the gold standard for stress fracture diagnosis. Both extremities of 53 soldiers who were suspected of having a tibial stress fracture were evaluated (106 diagnostic tests), 51 of which were diagnosed as having a stress fracture. Ultrasound testing identified 38 of the 51 confirmed tibial stress fractures (sensitivity = 75%), whereas radiographs identified only 11 of the 51 (sensitivity = 22%). Furthermore, ultrasound testing demonstrated a 71% accuracy rate (38 true positives and 37 true negative), compared to 62% for radiographs (11 true positives and 55 true negatives). Giladi et al. further suggests that the use of ultrasound closer to the onset of pain (2-3 weeks vs. later) improves the accuracy of the diagnosis from 71% to 80%. The increased accuracy might precede restoration of normalcy within the periosteum, which does not occur until about 20 days after tissue remodeling begins. 3,15,25 Thus, the first 3 weeks may be the best time interval for use of ultrasound as a screening tool for identification of a stress reaction. Nitz and Scoville 22 used ultrasound to detect medial tibial plateau stress fractures in military recruits. After a clinical evaluation, ultrasound was applied at an intensity of W/cm 2 to the anterior surface of the knee for a maximum of 30 seconds. Eighty-nine percent of recruits who experienced pain with ultrasound were found to have radiographic evidence of a medial tibial plateau fracture. 22 Nitz and Scoville 22 reported that ultrasound accurately detected medial tibial stress fractures 92.6% of the time. They concluded that ultrasound was a simple, inexpensive, and reliable tool to determine the presence or absence of stress fractures within the first 3 weeks of pain onset. More recently, an examination of therapeutic ultrasound to identify stress fractures by Romani et al. 23 has refuted the findings of other studies. Using continuous ultrasound (1 MHZ, increasing intensity from W/cm 2 every 30 seconds), a visual analog scale, and MRI results, subjects were classified into one of three groups on the basis of an MRI classification scale for bone remodeling and stress fracture identification: no fracture, transition, stress fracture. 26 None of the subjects found to have a stress fracture according to the MRI were correctly identified by the use of continuous ultrasound (1 MHz, increasing intensity from 0 to 2.9 W/cm 2 every 30 s), thus having a sensitivity of 0%. Romani et al. noted several methodology differences between their study and others. They suggest that differences in research methodology and ultrasound frequencies require further study, particularly for at-risk patients. Conclusion The most common cause of tibial plateau stress fractures in college-age athletes has been attributed to physical activity. Reports of the same type of stress fracture in adult athletes have attributed it to causes other than physical activity. Few published reports of tibial plateau fracture among post-college aged athletes can be found in the literature. Although therapeutic ultrasound is recommended as a screening tool, any positive findings in the presence of other clinical signs and symptoms should result in prompt referral to a physician. Early recognition of a stress reaction, and a complete assessment of intrinsic and extrinsic risk factors, allows clinicians to make the appropriate referral and modification to an athlete s training regimen. These modifications help insure a quick and safe return to sports participation. References 1. Sallis RE, Jones K. Stress fractures in athletes: how to spot this underdiagnosed injury. Postgrad Med. 1991;89(6): Bennell KL, Malcolm SA, Thomas SA, Wark JD, Brukner PD. The incidence and distribution of stress fractures in competitive track and field athletes. A twelve-month prospective study. Am J Sports Med. 1996;24(2): Perron AD, Brady WJ, Keats TA. Principles of stress fracture management. Postgrad Med. 2002;10: McBryde, A. Stress fractures in runners. In: D Ambrosia R, Drez. D, eds. Prevention and Treatment of Running Injuries. 2nd ed. Thorofare, NJ: Slack Incorporated; Crossley K, Bennell KL, Wrigley T, Oakes BW. Ground reaction forces, bone characteristics, and tibial stress fracture in male runners. Med Sci Sports Exerc. 1999;31(8): Couture C, Karlson KA. Tibial stress injuries. Phys Sportsmed. 2002;30: Harolds JA. Fatigue fractures of the medial tibial plateau. South Med J. 1981;74(5): Matheson GO, Clement DB, McKenzie DC, Taunton JE, Lloyd-Smith DR, MacIntyre JG. Stress fractures in athletes. A study of 320 cases. Am J Sports Med. 1987;15: Brunker P, Bradshaw C, Bennell K. Managing common stress fractures: let risk level guide treatment. Phys Sportsmed. 1998;26(8): Athletic Therapy Today MARCH

5 10. Morrison C. A practical approach to stress fractures. Orthop Nurs. 2000;9(6): Gilbert RS, Johnson HA. Stress fractures in military recruits. A review of twelve years of experience. Mil Med. 1996;131: Mizuta H. An unusual stress fracture of the lateral tibial plateau. Arch Orthop Trauma Surg. 1993;12(2): Engber WD. Stress fractures of the medial tibial plateau. J Bone Joint Surg Am.1977;59-A: Zioupos P. Accumulation of in-vivo fatigue microdamage and its relation to biomechanical properties in ageing human cortical bone. J Micros. 2001;21: Romani WA, Gieck JH, Perrin DH, Saliba EN, Kahler DM. Mechanisms and management of stress fractures in physically active persons. J Athl Train. 2002;37(3): Nordin M, Frankel VH. Basic Biomechanics of the Musculoskeletal System 3rd ed. Philadelphia, Pa: Lippincott Williams & Wilkins; Bennell K, Matheson G, Meeuwisse W, Brunker PD. Risk factors for stress fractures. Sports Med. 1999;28(2): Arendt EA, Griffiths HJ. The use of MR imaging on the assessment and clinical management of stress reactions of bone in high-performance athletes. Clin Sports Med. 1997;16(2): Starkey C. Therapeutic Modalities. 3rd ed. Philadelphia, Pa: F.A. Davis Co; 2004; Nussbaum E. Therapeutic ultrasound. In: Behrens, BJ, Michlovitz, S, eds. Physical Agents: Theory and Practice for the Physical Therapy Assistant. Philadelphia, Pa: Slack Incorporated; 1996; Giladi, M, Ziv Y, Aharonson Z, Nili E, Danon YL. Comparison between radiography, bone scan, and ultrasound in the diagnosis of stress fractures. Mil Med. 1984;149(8): Nitz, AJ, Scoville CR. Use of ultrasound in early detection of stress fractures of the medial tibial plateau. Mil Med 1980;145(12): Romani WA, Perrin DH, Dussault RG, Ball DW, Kahler DM. Identification of tibial stress fractures using therapeutic continuous ultrasound. J Orthop Sports Phys Ther. 2000;30(8): Moss A, Mowatt AG. Ultrasonic assessment of stress fractures. BMJ. 1983;286: Johansson C, Ekenman I, Tornkvist H, Eriksson E. Stress fractures of the femoral neck in athletes: The consequence of a delay in diagnosis. Am J Sports Med. 1990;18(5): Fredericson M, Bergman AG, Hoffman KL, Dillingham MS. Tibial stress reaction in runner: Correlation of clinical symptoms and scintigraphy with a new magnetic resonance imagining grading system. Am J Sports Med. 1995;23: David C. Berry is with the Department of Health Promotion and Human Performance at Weber State University in Ogden, UT. Book and DVD package bring PNF stretching to life For a complete description or to order, call: (800) US (800) CDN 44 (0) UK (08) AUS (09) NZ (217) International Or visit The third edition of Facilitated Stretching is now revised, reorganized, and packaged with a DVD surpassing its popular predecessor as the best source for the latest PNF (proprioceptive neuromuscular facilitation) stretching techniques. The third edition contains all the great features of the previous edition, plus the following: A companion DVD that demonstrates live stretching techniques from the book for a clearer understanding New stretching routines for a variety of popular activities including running, golfing, swimming, cycling, and throwing and racket sports General stretches and stretches for older participants Stretching activities with added strength work using stability balls and elastic bands Stretching and strengthening tips for dealing with and even preventing common soft-tissue injuries With Facilitated Stretching, Third Edition, you have a cutting-edge tool packed with the latest PNF stretching techniques to help you assess current muscle function, improve range of motion, increase strength, reduce overuse injuries, and enhance performance Paperback with DVD Approx. 194 pp ISBN $24.95 ($29.95 CDN, UK incl. VAT, EURO, $43.95 AUS, $52.90 NZ) *Prices subject to change HUMAN KINETICS The Information Leader in Physical Activity P.O. Box 5076 Champaign, IL USA /06 20 MARCH 2007 Athletic Therapy Today