Stress Fractures of the Femoral Diaphysis

Stress Fractures of the Femoral Diaphysis Benjamin C. Caesar, BSc (Hons), MBBS, FRCS Ed (Orth), and Simon J. Roberts, MA, BM, BCh, FRCS (Orth), FFSEM (UK) Femoral diaphyseal stress fractures are rare in the general population, but are frequently seen in the athletic and military communities. The diagnosis of this problem is frequently missed at first consultation and needs to be considered in all athletes and military recruits who present with vague groin, thigh, or knee pain. The female triad in athletes should be considered in those women who sustain this injury. Management is usually conservative, with a variety of rehabilitation programs suggested, but a pragmatic approach is to manage the patient symptomatically. Surgical intervention is routinely done by intramedullary fixation and is usually only required when the fracture displaces. Oper Tech Sports Med 17:94-99 © 2009 Elsevier Inc. All rights reserved. KEYWORDS stress fracture, femur, athlete

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tress fractures in the general population are rare; the reported incidence in a large epidemiologic study from Edinburgh reported an incidence of 0.5% for spontaneous or stress fractures in all bones over the course of a year in a well-defined population.1 However, stress fractures are considerably more common in the athletic population; the figures from Matheson et al’s2 1987 paper suggest that most of these injuries are sustained in the tibia (49.1%), followed by the tarsals (25.3%), metatarsals (8.8%), femur (7.2%), fibula (6.6%), pelvis (1.6%), sesamoids (0.9%), and spine (0.6%). However, an article in 1994 by Johnson et al3 looked at collegiate level athletes showing 34 stress fractures in 914 athletes, of which 7 (20.6%) were of the femoral diaphysis. The difficulties in ascertaining accurately the incidence figures for these injuries is excellently summarized in a paper by Snyder et al4 in which they highlight the need for large prospective studies to delineate the risks of stress fracture by sport, age, and gender. Stress fractures of the femoral diaphysis can occur anywhere along its length, but interestingly, when comparing the data from athletes and military recruits, the distribution of these fractures differs; athletes predominantly have fractures of the midmedial or posteromedial cortex in the proximal third of the femoral shaft, with distal fractures being rare.3,5 Conversely, Provost and Morris5 reported 51% of Sports Injuries Service, Robert Jones and Agnes Hunt Orthopaedic Hospital NHS Trust, Oswestry, Shropshire, United Kingdom. Address reprint requests to Benjamin C. Caesar, BSc (Hons), MBBS, FRCS Ed (Orth), Department of Orthopaedics, Robert Jones and Agnes Hunt Orthopaedic Hospital NHS Trust, Oswestry, Shropshire, UK SY10 7AG. E-mail: [email protected]

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1060-1872/09/$-see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1053/j.otsm.2009.05.008

femoral shaft stress fractures occur in the distal shaft in military recruits. Stress fractures have been classified into high and low risk by multiple authors,6-8 and femoral diaphyseal fractures are included in the low-risk category along with posteromedial tibia, ribs, ulna shaft, and the first through to fourth metatarsals. These fractures have a favorable natural history and are less likely to recur, fail to unite, or have a significant complication should they progress to complete fracture. However, to prevent complications it is necessary for the clinician to identify these injuries early, as displacement often requires surgical intervention to restore alignment.

Presenting Complaint Early diagnosis may be difficult and requires a high index of suspicion, as patients may present with hip, thigh, or knee pain. Although the location of pain may not always correlate with the area of injury, femoral shaft stress injuries typically cause vague pain in the thigh and may radiate to the hip or knee. The hip range of movement is not typically limited, but may be painful, which is in contrast to femoral neck stress fractures that often demonstrate loss of hip motion as a result of muscle guarding.9 It has been reported that high numbers of femoral stress fractures (up to 75%), both neck and shaft, are missed at initial examination.10

History of Presenting Complaint The pain typically begins after a change in the usual activity regimen or an increase in its intensity. It is usually insidious in onset and related to activity; however, in some cases the

Stress fractures of the femoral diaphysis severity of pain may limit or prevent activity. Some patients may experience it at night. The common belief is that these fractures are injuries sustained by long-distance runners. In a study by Clement,11 95% of those sustaining stress fractures of the femur were runners; however, Koenig et al 12 in their work show that only 52% of these injuries are being sustained in track and crosscountry runners, 25% in lacrosse players, 12% in field hockey players, 12% in rowers, and 4% in American football players. There is a case report in the published data of femoral stress fractures in an equestrian,13 a case report in a professional football player,14 and a case series in lacrosse players.15 The overriding impression from the most recent articles is that the diagnosis should be considered in all athletes, particularly women, as it does not appear to be related as specifically to runners as previously thought. It is particularly important to gain a satisfactory history from the patient to identify any factors that may be contributing to the development of stress fractures. This should include any recent alterations in training regimen,16,17 training surface,16,18 or the time period the patient is using footwear.17 A detailed menstrual history should be taken from women, including age at menarche,19 any history of menstrual disturbance,20-30 and contraceptive use.23 It is also im-

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Figure 2 Plain radiograph of female adolescent athlete with thigh pain.

portant to obtain a detailed history of the patient’s dietary intake and any history of disordered eating.31,32

Physical Examination The presentation may be variable as is the physical examination. Swelling may be found within the thigh but this is not

Figure 1 Fulcrum test. (Courtesy, Physiotherapy Department, Robert Jones and Agnes Hunt Hospital.)

Figure 3 Bone scintigraphy of same patient.

B.C. Caesar and S.J. Roberts

96 always present. The area of maximal tenderness is often more difficult to assess in the thigh as compared with other stress fractures because of the significant overlying muscle bulk. The muscle size, tone, and strength are usually unaffected by the stress reaction or fracture. Femoral neck stress fractures are often painful on palpation around the groin and on passive movement of the hips at extremes of movement33 and this may help delineate a femoral neck from a femoral shaft fracture. Patients with stress fractures of the femur often present with an antalgic gait. A bending stress may accentuate the pain associated with these fractures, and a fulcrum test, as described by Johnson et al,3 will cause the patient pain and apprehension during the maneuvre when the location of

the stress injury is reached, as demonstrated in Figure 1. Approximately 70% of patients with a positive hop test have a femoral stress fracture.34

Imaging Studies Initial imaging of the femur is usually undertaken using plain radiographs looking for radiolucent lines, cortical disruption, periosteal reaction, or early formation of callus. However, only 10% of these injuries demonstrate changes on plain radiograph at 1 week.2,35 Periosteal bone formation is at its most prominent at 6 weeks.20 Radiographs typically only demonstrate late changes and infrequently show a radiolu-

Figure 4 (A-C) Selected MRI images of the same adolescent.

Stress fractures of the femoral diaphysis cent fracture line35, and this can lead to problems with early recognition and, therefore, failure to appropriately manage these injuries leading to displacement and subsequent surgical intervention.21,22 Technetium bone scans and MRI are the 2 modalities that are able to demonstrate the early changes seen in stress fractures. Bone scanning has been considered the gold standard for some time and is able to demonstrate the spectrum of changes within the bone that lead to development of stress reactions or fractures.23 However, despite its high sensitivity, bone scintigraphy lacks specificity as infection, osteonecrosis, and tumors can all mimic stress injury.24 MRI is extremely sensitive in the detection of soft tissue, and bone and marrow changes associated with stress injuries. It allows depiction of abnormalities weeks before the development of a radiographic lesion and has comparable sensitivity and superior specificity to scintigraphy.25 In addition to bony changes, it also details information about the surrounding muscular or ligamentous insults associated with, or responsible for the symptoms.26 The use of plain radiography, scintigraphy, MRI, and CT for the same adolescent female athlete is demonstrated in Figures 2-5. With the obvious difficulties in clearly demonstrating the lesion on plain radiographs, a bone scan was undertaken that demonstrated the area of obvious increased uptake, the MRI scan subsequently showed the significant marrow edema, and finally a CT scan was used that did show the breech in the femoral cortex and the callus formation around it. There are several grading systems for stress injuries, the first is from the article by Arendt and Griffiths27 which considers the plain radiographic, scintigraphic, and MRI findings. The newer system by Kiuru et al28 is based on the extent of bone involvement on MRI and is easier to use in routine practice, as shown in Table 1.

97 Table 1 Magnetic Resonance Imaging Grading of Stress Injuries28 Grade

MRI Findings

I II III IV V

Endosteal edema Periosteal and endosteal edema Muscle, periosteal and endosteal edema Fracture line Callus at the endosteal and/or periosteal surface of cortical bone

Data from Kiuru MJ, Pihlajamaki HK, Ahovuo JA: Fatigue stress injuries of the pelvic bones and proximal femur: Evaluation with MR imaging. Eur Radiol 13:605-611, 2003.

Management After the diagnosis of a femoral shaft stress reaction or stress fracture has been made, it is important for these injuries to be managed appropriately. A number of basic principles were outlined by Raasch and Hergan29 in a review in 2006 on the fundamentals of treatment of stress fractures; in the first place, one must understand why the injury occurred in the first instance, and then consider the extrinsic and intrinsic factors that may have contributed to the injury. The extrinsic factors include the training regimen, equipment, and nutritional habits of the patient, whereas the intrinsic factors include anatomical variations, such as limb length discrepancies, muscle endurance, and hormonal factors. Many of these factors will be picked up during the detailed history, and the time spent during rehabilitation should also focus on these underlying factors to prevent recurrence.

Nonoperative Management Most athletes with femoral shaft stress fractures are managed nonoperatively with good results.3,5,15 This course of management is not one of complacency; it requires a period of rest to allow bone repair to predominate. There are many different regimes in the published data. The 2 most quoted are the Arendt and Griffiths’29 protocol that ascribes periods of rest for athletes with stress reactions on the basis of MRI grading of their injury, as shown in Table 2. A more recent publication from Ivkovic et al30 demonstrating their treatment regimen in 7 top level athletes showed a return to full sporting activity between 12 and 18 weeks, with no recurrence of discomfort or pain over the course of 48-96 months of follow-up; their regimen is shown Table 3. The case report by Webb et al14 of a professional football player in the United States quoted Ivkovic et al, but were Table 2 Protocol Based on MRI Grading27 Grade Grade Grade Grade

Figure 5 CT scan demonstrating the lucent line and callus.

1 2 3 4

3 wk rest 3-6 wk rest 12-16 wk rest > 16 wk rest

Data from Arendt EA, Griffiths HJ: The use of MR imaging in the assessment and clinical management of stress reactions of bone in high-performance athletes. Clin Sports Med 16:291-306, 1997.

B.C. Caesar and S.J. Roberts

98 Table 3 Protocal for Femoral Shaft Stress Fractures in Athletes30 Symptomatic phase (3 wk) Asymptomatic phase (3 wk) Basic phase (3 wk) Resuming phase (3 wk)

Walking with crutches, nonweight-bearing on affected leg Normal walking, swimming, gym (upper limbs and unaffected leg) All limbs (low weight), running in straight line (alternate days), static bicycle Gradual return to normal training

Data from Ivkovic A, Bojanic I, Pecina M: Stress fractures of the femoral shaft in athletes: A new treatment algorithm. Br J Sports Med 40:518-520, 2006; discussion: 520.

Complications of Treatment With nonoperative treatment, there is the potential complication of displacement and, therefore, the need for surgical intervention. There are no reported series looking at return to sport after operative management of femoral shaft fractures, but the series by Salminen et al31 did report that 2 of the military recruits were excused military service for 2 years after their surgery. This cohort’s mean time to union was 3.5 months and the recruits who stayed in the military returned to light duties at an average of 6 weeks after surgery.

Conclusions unable to find a standardized protocol for professional football. They felt they were able to accelerate the return to play of their patient using a period of non–weight-bearing until the patient was asymptomatic, which lasted a week, and immediate commencement of a bone stimulator, which was continued for 3 weeks. At 10 days, he began to ride a static bicycle and then progressed to treadmill running at 2 weeks. At 17 days postdiagnosis, a functional field progression was begun and the player remained asymptomatic, progressing through various activities during practice over the next week. He participated in a game at 4 weeks postinjury, without recurrence of his symptoms despite an MRI at 5 weeks that showed no change from his presenting MRI. Only at 2 months there was some resolution of the MRI findings. Webb et al felt that a tailored regimen for the athlete, not based on a defined timetable, allowed earlier progression on the basis of symptomatology rather than imaging. This a sensible and pragmatic approach to this injury in the face of any compelling evidence to the contrary. However, caution must be exercised to avoid the risk of fracture displacement, which would then almost inevitably lead onto operative intervention.

Operative Management Fortunately this is rarely required in the management of femoral shaft stress fractures. In an article by Salminen et al,31 which is one of the few on the subject and based on military recruits, the incidence was calculated over a 20-year period to be 1.5 per 100,000 person-years in military service. In this series, the injuries were stabilized either using plate and screw constructs or intramedullary nailing, depending on the site and nature of the fracture. In 2 case reports by Luchini et al,32 both long-distance runners who had acute displace femoral diaphyseal fractures underwent intramedullary nailing. The operative techniques for these procedures are well described33 and currently most of these femoral diaphyseal injuries would be managed using intramedullary nailing except in patients with narrow medullary canals, previously placed hardware, an associated vascular injury, proximal or distal extensions, lack of fluoroscopy, or an associated femoral neck fracture.

Femoral diaphyseal stress fractures are rare events in the general population but are much more common in the athletic population. A high index of suspicion is required to ensure early diagnosis. After suspicion is raised of the injury, a detailed history, focused examination, and the appropriate imaging modalities are required to make the diagnosis and commence a patient-tailored rehabilitation program. It is important to consider contributory factors, such as hormonal or dietary imbalances during this period. In the unlikely event of displacement of the fracture, surgical intervention is usually required and this is commonly done using intramedullary devices, although in some series various plate and screw devices have been used. In most cases, athletes with femoral shaft fractures can expect to return to their previous level of competition if they are compliant with the treatment program.

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