Use of MRI for Incomplete Intertrochanteric Fractures
Use of MRI for Incomplete Intertrochanteric Fractures
Abstract & Commentary
Synopsis: MRI is the method of choice for diagnosing incomplete intertrochanteric fractures. This subset of fracture is often treated conservatively.
Source: Schultz E, et al. Incomplete intertrochanteric fractures: Imaging features and clinical management. Radiology 1999;211:237-240.
Imaging work up for hip fracture has changed over the last decade. Several studies confirm that magnetic resonance imaging (MRI) now plays an important role for diagnosing these fractures in the situation where the conventional radiographs are normal or equi-vocal.1-3 It is important to consider the location and extent of the fracture once it is detected. There is a subset of intertrochanteric fractures that are incomplete. The incomplete intertrochanteric fracture is characterized by a fracture line that extends from the greater trochanter into the medullary space but does not disrupt the medial femoral cortex. This retrospective study presents the imaging findings and treatment options for incomplete intertrochanteric fractures.
Thirty-one patients with the MRI diagnosis of incomplete intertrochanteric fracture were included in this study. The mean age of the patients was 82 years with a female preponderance. All but two patients had a history of trauma. Conventional radiographs of the hip were obtained in 30 patients an average of 1.7 days prior to the MRI. The hips were imaged on a 1.5-T unit (Signa; GE Medical Systems, Milwaukee, Wis) in the coronal plane with spin-echo T1-weighted and fat-suppressed fast spin-echo T2-weighted sequences. Twenty-eight hips were also imaged with T1-weighting in the axial plane. Two musculoskeletal radiologists evaluated medial and anterior fracture extent in the coronal and axial planes with attention to whether the fracture crossed the midline of the femoral shaft. Treatment follow-up was recorded.
Incomplete fracture was the prospective diagnosis in only one case. Radiographs were interpreted as normal in 16 patients and demonstrating a greater tuberosity fracture in 10 patients. In two patients, the respective diagnosis from the radiographs was conventional intertrochanteric fracture and possible subtrochanteric fracture. Once the diagnosis of incomplete intertrochanteric fracture was made, 18 patients were treated surgically with a sliding compression screw and 13 were conservatively managed. In these two groups, the average age of the patients, length of fracture, and percentage of separate fractures involving the greater trochanter and crossing the midline of the femur in the axial plane were the same. Fractures crossed the midline in the coronal plane in 50% of the surgical group but in only 23% of the nonsurgical group. Average time from injury to ambulation was two days less in the surgical group, but no difference in functional status was found subjectively between the two groups at clinical follow-up.
Schultz and associates conclude that incomplete intertrochanteric fractures are a subset of intertrochanteric fractures that are definitively diagnosed with MRI. They propose that this type of intertrochanteric fracture be incorporated into more classification systems for hip fractures.
Comment by Lynne S. Steinbach, MD
Radiologists have become accustomed to obtaining MRI for occult hip fractures. In addition, we are now seeing that even when not occult, the intertrochanteric fracture should be further classified as complete or incomplete. Tronzo included the incomplete intertrochanteric fracture in his classification system,4 while other classification systems for intertrochanteric fractures do not include the incomplete form. Although no criteria have been set for the treatment of incomplete intertrochanteric fractures, Schultz et al suggest that incomplete intertrochanteric fractures that do not cross the midline may be treated conservatively, whereas those that cross the midline tend to be treated surgically. We have had some cases in our practice where incomplete fractures that crossed the midline were also treated conservatively and did well. Therefore, this strict dogma may not be universal.
As mentioned by Schultz et al, there are a few limitations to the study. This was a relatively small patient population. A larger series with more treatment options would be welcome. Fifteen orthopedic surgeons were involved in the treatment of these patients, creating a situation of decreased standardization and control. Clinical follow-up was available for only 12 patients, which limits the strength of the conclusions. An inherent weakness in a retrospective study such as this, is that Schultz et al were unable to determine the frequency of incomplete intertrochanteric fractures since some patients with unsuspected incomplete fractures would not have had an MRI for their hip pain.
References
1. Yao L, Lee JK. Occult intraosseous fracture: Detection with MR imaging. Radiology 1988;167:749-751.
2. Deutsch AL, et al. Occult fractures of the proximal femur: MR imaging. Radiology 1989;170:113-116.
3. Rizzo PE, et al. Diagnosis of occult fractures about the hip. J Bone Joint Surg [Am] 1993;75:395-401.
4. Tronzo RG. Symposium on fractures of the hip. I. Special considerations in management. Orthop Clin North Am 1974;5:571-583.
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