Make a Recommendation for a Provisional Case Definition of Atypical Femoral Fractures So That Subsequent Studies Report on the Same Condition
To assist in case finding and reporting, the task force defined major and minor features for complete and incomplete atypical fractures of the femur (see the table below). All major features should be present in order to designate a fracture as atypical and distinguish it from more common hip fractures (i.e., femoral neck, intertrochanteric). Minor features commonly have been described in association with atypical fractures but may or may not be present in individual patients. Although atypical femoral fractures have been reported most prominently in individuals who have been treated with bisphosphonates (BPs), such fractures have been reported in individuals with no history of BP exposure. Therefore, to facilitate studies comparing the frequency of atypical femoral fractures in patients with and without BP therapy, association with BP therapy was included as a minor feature.
Table. Atypical Femoral Fracture: Major and Minor Featuresa
- Located anywhere along the femur from just distal to the lesser trochanter to just proximal to the supracondylar flare
- Associated with no trauma or minimal trauma, as in a fall from a standing height or less
- Transverse or short oblique configuration
- Complete fractures extend through both cortices and may be associated with a medial spike; incomplete fractures involve only the lateral cortex.
- Localized periosteal reaction of the lateral cortexc
- Generalized increase in cortical thickness of the diaphysis
- Prodromal symptoms such as dull or aching pain in the groin or thigh
- Bilateral fractures and symptoms
- Delayed healing
- Comorbid conditions (e.g., vitamin D deficiency, rheumatoid arthritis [RA], hypophosphatasia)
- Use of pharmaceutical agents (e.g., BPs, glucocorticoids [GCs], proton pump inhibitors [PPIs])
aSpecifically excluded are fractures of the femoral neck, intertrochanteric fractures with spiral subtrochanteric extension, pathologic fractures associated with primary or metastatic bone tumors, and periprosthetic fractures.
bAll major features are required to satisfy the case definition of atypical femoral fracture. None of the minor features are required but sometimes have been associated with these fractures.
cOften referred to in the literature as beaking or flaring.
Recommend the Development of Noninvasive Diagnostic and Imaging Techniques with Which to Better Characterize and Diagnose the Disorder
Imaging of the atypical femoral shaft fracture is relatively straightforward. Conventional radiography is the first line of approach, with more sophisticated imaging such as bone scintigraphy, magnetic resonance imaging (MRI), or computed tomography (CT) useful principally for detecting early or subtle prefracture features.
While scintigraphy, MRI, and CT scanning are more costly and less convenient than conventional radiography, these advanced imaging techniques provide superior sensitivity and specificity for detecting early stages of stress or insufficiency fractures and therefore, in selected instances, could improve the clinical management of atypical femoral shaft fractures (see Figures 5A–C in the original guideline document). Even the lower-resolution images of dual-energy X-ray absorptiometry (DXA) occasionally may detect the hypertrophic new bone formation of an evolving proximal subtrochanteric femoral shaft fracture and aid in the differentiation of proximal thigh pain in this condition (see Figure 5D in the original guideline document).
Recommend Clinical Orthopedic and Medical Management of Atypical Femoral Fractures Based on Available Information
Surgical Treatment Strategy for Atypical Subtrochanteric and Femoral Shaft Fractures
Because of the propensity for delayed healing, the morbidity of these fractures is particularly high. The task force recognized that there are no controlled studies evaluating surgical treatment strategies for atypical subtrochanteric and femoral shaft fractures. The recommendations outlined here therefore are opinion-based and represent the consensus of the orthopedic surgeons who served on the task force. The task force developed a hierarchical approach to management that depends on whether the fracture is complete or incomplete.
History of Thigh or Groin Pain in a Patient on BP Therapy
A femoral fracture must be ruled out (Goh et al., 2007; Kwek et al., 2008; Lenart et al., 2009; Neviaser et al., 2008; Capeci & Tejwani, 2009; Odvina et al., 2010; Lenart, Lorich, & Lane, 2008; Das De, Setiobudi, & Shen, 2010). Anteroposterior and lateral plain radiographs of the hip, including the full diaphysis of the femur, should be performed. If the radiograph is negative and the level of clinical suspicion is high, a technetium bone scan or MRI of the femur should be performed to detect a periosteal stress reaction. The advantage of the technetium bone scan is that both legs will be imaged.
Complete Subtrochanteric/Diaphyseal Femoral Fracture
Orthopedic management includes stabilizing the fracture and addressing the medical management (Goh et al., 2007; Kwek et al., 2008; Lenart et al., 2009; Neviaser et al., 2008; Capeci & Tejwani, 2009; Odvina et al., 2010; Lenart, Lorich, & Lane, 2008; Das De, Setiobudi, & Shen, 2010) (see below). Since BPs inhibit osteoclastic remodeling, endochondral fracture repair is the preferred method of treatment. Intramedullary reconstruction full-length nails accomplish this goal and protect the entire femur. Locking plates preclude endochondral repair, have a high failure rate, and are not recommended as the method of fixation. The medullary canal should be overreamed (at least 2.5 mm larger than the nail diameter) to compensate for the narrow intramedullary diameter (if present), facilitate insertion of the reconstruction nail, and prevent fracture of the remaining shaft. The proximal fragment may require additional reaming to permit passage of the nail and avoid malalignment. The contralateral femur must be evaluated radiographically, including scintigraphy or MRI, whether or not symptoms are present (Capeci & Tejwani, 2009).
Incomplete Subtrochanteric/Femoral Shaft Fractures
Prophylactic reconstruction nail fixation is recommended for incomplete fractures accompanied by pain (Goh et al., 2007; Kwek et al., 2008; Lenart et al., 2009; Neviaser et al., 2008; Capeci & Tejwani, 2009; Odvina et al., 2010; Lenart, Lorich, & Lane, 2008; Das De, Setiobudi, & Shen, 2010). If the patient has minimal pain, a trial of conservative therapy, in which weight bearing is limited through the use of crutches or a walker, may be considered. However, if there is no symptomatic and radiographic improvement after 2 to 3 months of conservative therapy, prophylactic nail fixation should be strongly considered because these patients may progress to a complete fracture. For patients with incomplete fractures and no pain, weight bearing may be continued but should be limited and vigorous activity avoided. Reduced activity should be continued until there is no bone edema on MRI.
Medical Management of Atypical Subtrochanteric/Femoral Shaft Fractures
There are also no controlled studies evaluating medical treatment strategies for atypical subtrochanteric and femoral shaft fractures. The recommendations outlined here therefore are opinion-based and represent the consensus of the clinicians who served on the task force. The task force considered two main aspects of medical management.
Decisions to initiate pharmacologic treatment, including BPs, to manage patients with osteoporosis should be made based on an assessment of benefits and risks. Patients who are deemed to be at low risk of osteoporosis-related fractures should not be started on BPs. For patients with osteoporosis in the spine and normal or only moderately reduced femoral neck or total-hip bone mineral density (BMD), one could consider alternative treatments for osteoporosis, such as raloxifene or teriparatide, depending on the severity of the patient's condition. It is apparent that therapy must be individualized and clinical judgment must be used because there will not always be sufficient evidence for specific clinical situations. BP therapy should be strongly considered to protect patients from rapid bone loss and increased fracture rates associated with clinical scenarios such as organ transplantation, endocrine or chemotherapy for breast or prostate cancer, and initiation of aromatase inhibitors and glucocorticoids (GCs). However, long-term BP therapy may not always be necessary in these clinical conditions (Cohen et al., 2006; Hershman et al., 2010). More research is needed to determine the most effective dose and duration of BPs in patients with secondary causes of rapid bone loss.
The optimal duration of BP treatment is not known. Based on current case reports and series, the median BP treatment duration in patients with atypical subtrochanteric and femoral shaft fractures is 7 years. For patients without a recent fracture and with femoral neck T-scores greater than –2.5 after the initial therapeutic course, consideration may be given to a "drug holiday" from BPs. Because some patients with atypical femoral fractures while on BPs were on concomitant therapy with GCs, estrogen, tamoxifen, or proton pump inhibitors (PPIs), continued BP therapy should be reevaluated, particularly in those deemed to be at low or only modestly elevated fracture risk. Whether discontinuation of BPs after 4 to 5 years in the lower-risk group will lead to fewer atypical subtrochanteric fractures is not known.
If BPs are discontinued, there are no data to guide when or whether therapy should be restarted. However, patients should be followed by clinical assessment, bone turnover markers, and BMD determination. Restarting osteoporosis therapy, either with BPs or with a different class of agent, can be considered in patients who appear to be at increasing fracture risk. Models to help assess risk in previously treated patients, after 1 or more years off therapy, are needed to help guide these therapeutic decisions. It seems apparent that there can be no general rule and that decisions to stop and/or restart therapy must be individualized.
More than half of patients reported with atypical femoral fractures have had a prodrome of thigh or groin pain before suffering an overt break. Thus it is important to educate physicians and patients about this symptom and for physicians to ask patients on BPs and other potent antiresorptive agents about thigh or groin pain. Complaints of thigh or groin pain in a patient on BPs require urgent radiographic evaluation of both femurs (even if pain is unilateral). If plain radiographs are normal or equivocal and clinical suspicion is high, MRI or radionuclide scintigraphy should be performed to identify stress reaction, stress fracture, or partial fracture of either femur. Other disorders, such as forms of osteomalacia, also should be considered (Whyte, 2009).
For patients with a stress reaction, stress fracture, or incomplete or complete subtrochanteric or femoral shaft fracture, potent antiresorptive agents should be discontinued. Dietary calcium and vitamin D status should be assessed, and adequate supplementation should be prescribed.
In the absence of evidence-based approaches, teriparatide should be considered in patients who suffer these fractures, particularly if there is little evidence of healing by 4 to 6 weeks after surgical intervention.