The MRI diagnosis and management of incomplete intertrochanteric fractures of the femur

Utility of Pelvis CT to Assess Occult Intertrochanteric Extension of Greater Trochanteric Fractures

OBJECTIVES

To determine whether computed tomography (CT) differences of bone density between the injured and noninjured femora in patients with greater trochanteric fractures can be used to identify intertrochanteric extension (ITE).

METHODS

DESIGN

Retrospective cohort series.

SETTING

Multihospital academic institution.

PATIENT SELECTION CRITERIA

Included were patients for a 7-year period (January 2014-December 2021) with greater trochanteric fractures (OTA/AO 31A1.1) without evident ITE on CT that also underwent pelvis magnetic resonance imaging (MRI) to assess for occult ITE.

OUTCOME MEASURES AND COMPARISONS

The primary outcome measures were CT findings of intertrochanteric (IT) curvilinear density (CL) and subtrochanteric bone density (ST) in the injured femur in patients with greater trochanteric fractures. CT findings (CL and ST) were compared with the patient's MRI, which was the reference standard for occult IT fractures. The MRI determined presence of occult intertrochanteric extension and, if present, MRI determined fracture extension into the IT region were categorized as (1) less than 50% or (2) 50% or greater. Descriptive statistics, sensitivity, specificity, and inter-rater reliability were calculated assessing the presence of the CT findings of CL and ST, compared with reference standard MRI ITE. Sensitivity and specificity for CL and ST were calculated for (1) any degree of MRI ITE (<50% and ≥50%) and (2) only MRI ITE 50% or greater.

RESULTS

Eighty-one patients (54 women, 27 men, mean age 82 years, range 54-102) were included. Fourteen (17%) patients had no MRI ITE, 11 (14%) patients had <50% MRI ITE, and 56 (69%) patients had ≥50% MRI ITE. The presence of CL on CT corresponded to any MRI ITE (<50% and ≥50%) with sensitivity of 55.2%, specificity 100%, positive predictive value (PPV) 100%, and negative predictive value (NPV) 31.8%. In patients with MRI ITE 50% or greater only and CL presence, specificity was 92%, and sensitivity was 62.5%. Presence of ST on CT was associated with any MRI ITE with sensitivity of 34.3%, specificity 100%, PPV 100%, and NPV 24.1%. Patients with MRI ITE 50% or greater and ST presence, specificity was 96% and sensitivity was 39%.

CONCLUSIONS

In patients with apparent isolated greater trochanteric fractures, the presence of curvilinear IT and subtrochanteric density in the medullary bone in the injured femur on pelvis CT was highly predictive of ITE. Patients with these CT findings in the injured femur on pelvis CT can be assumed to have ITE and treated accordingly, obviating the need for MRI. The absence of the curvilinear IT and subtrochanteric densities did not rule out possible ITE, and MRI can be further considered in this population.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Lipohemarthrosis of the Hip Joint in Apparently Isolated Greater Trochanter Fractures

Backgroud

Lipohemarthrosis in the hip joint, a critical indicator for detecting occult femoral neck or acetabular fractures, has not been reported in cases of isolated greater trochanter (IGT) fractures. This study retrospectively reviewed 3-dimensional computed tomography (3D-CT) images of what appeared to be IGT fractures to find out the frequency of lipohemarthrosis and its implication for the necessity of internal fixation.

Methods

From October 2004 to December 2019, 90 cases of suspected IGT fractures were evaluated using 3D-CT. After excluding 6 cases due to inadequate follow-up and 8 cases with poor imaging quality caused by metallic implants, 76 cases were included in the final analysis. The cohort consisted of 48 women and 28 men, with a mean age of 77 years (range, 39-97 years). The 3D-CT images were meticulously reviewed to identify lipohemarthrosis in the affected hip joints. Additionally, magnetic resonance (MR) images were available for 13 cases.

Results

Sixty-three cases were IGT fractures; no cortical disruption was detected in the intertrochanteric area on CT images. Of these, 56 cases were successfully treated conservatively. Lipohemarthrosis was detected in 5 cases (7.9%), of which 2 were successfully managed with conservative treatment. The remaining 13 cases were classified as incomplete intertrochanteric fractures, with anterior cortical disruption identified in the intertrochanteric area on CT images. Lipohemarthrosis was observed in 3 of these cases (21.3%). In all cases evaluated with MR imaging (10 IGT fractures and 3 incomplete intertrochanteric fractures), varying degrees of intramedullary intertrochanteric extension were observed. Among these, lipohemarthrosis was detected in only 2 cases of IGT fracture, where the intramedullary extension did not cross the midline on mid-coronal images. One case was surgically fixed, but the other case was treated conservatively with success. Notably, 4 cases with intertrochanteric extension crossing the midline did not exhibit lipohemarthrosis.

Conclusions

Lipohemarthrosis was more frequently observed in incomplete intertrochanteric fractures than in IGT fractures. However, the presence of lipohemarthrosis alone should not be regarded as an indication for internal fixation.

Quantitative ROI differences for assessment of occult intertrochanteric extension of greater trochanteric fractures on pelvis CT

PURPOSE

To determine if difference in Hounsfield Units (HU) of the medullary bone between the injured and non-injured femurs in patients with greater trochanteric fractures is associated with occult intertrochanteric (IT) extension.

METHODS

Retrospective review was performed of 81 patients (age range 54-102, 54 females and 27 males) who underwent CT and subsequent MRI after identification of a greater trochanteric fracture without evidence of IT extension on radiography and/or CT. Hounsfield units of the injured and non-injured femurs on CT were recorded at the level of the base of the greater trochanter centrally (ROI1) and the level of the upper border of the lesser trochanter posteromedially (ROI2). The difference between the injured and non-injured femur for each ROI1 and ROI2 were calculated. Absence or presence, and if present, extent of IT extension was assessed on MRI. Analysis was performed to determine if there is correlation of difference in density with presence, and extent of occult IT fractures.

RESULTS

81 cases met inclusion criteria, 14 (17%) had no IT extension, 11 (14%) had less than 50% IT extension and 56 (69%) had 50% or greater IT extension. There was statistical significance between presence and absence of IT extension between the injured and non-injured femur for ROI1 (HU) no IT extension median (IQR): 18.8(4-40), ROI1 (HU) present IT extension median (IQR): 65.5(46-90) p < .0001, and for ROI2 no IT extension median (IQR): 3(-8-25.5) and ROI2 present IT extension 51(40.5-76), p < .0001. There was statistical significance of the extent of IT extension: ROI1 less than 50% IT extension median (IQR): 37.5(27.5-57), ROI1 50% or greater IT extension median (IQR): 72.3(53.5-91.3), p < .0001, and for ROI2 less than 50% IT extension median (IQR): 17.5(8-49), and ROI2 50% or greater IT extension median (IQR): 55.8(45.3-81.5), p < .0001. A threshold ROI2 difference of 50 HU resulted in specificity of 92% and sensitivity 60.7% of for IT extension 50% or greater.

CONCLUSION

Patients presenting with greater trochanteric fractures, an asymmetric increased density measured by ROI differences within the medullary space of the IT region between the injured and non-injured femur is associated with occult IT extension.

An Umbrella Review and Updated Meta-Analysis of Imaging Modalities in Occult Scaphoid and Hip and Femoral Fractures

Background: Occult fractures may cause multiple morbidities. If occult fractures were detected earlier, complications may be preventable. This umbrella review and updated meta-analysis will aim to evaluate the use of imaging modalities in detecting occult scaphoid and hip fractures. Methods: The protocol for this study is available in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42024525388). The literature search started and ended on 17 March 2024. We searched seven academic databases: MEDLINE, Cochrane Library, Pubmed, Science Direct, Google Scholar, WHO International Clinical Trials Registry Platform, and The Joanna Briggs Institute (JBI) database. The meta-analysis was conducted with the STATA program using the "midas" command. Results: There are four systematic reviews evaluating occult hip and femoral fractures with 6174 patients and two reviews evaluating occult scaphoid fractures with 1355 patients. The prevalence of occult scaphoid fracture and occult hip and femoral fractures is 23.87% (95% CI 18.25-29.49) and 44.8% (95% CI 39.38-51.4), respectively. Magnetic resonance imaging (MRI) had the best posterior probability of positive likelihood ratio (LR+) with 95% and 96% and negative likelihood ratio (LR-) with 0.15% and 1% for both occult scaphoid and hip fractures, respectively, assuming a 25% baseline. MRI could both confirm and exclude occult hip fractures while it can only confirm occult scaphoid fractures. Bone scans are inappropriate for either type of occult fractures The level of evidence for occult scaphoid fracture is weak while it is suggestive for occult hip fractures. Conclusion: The findings strengthen the use of MRI after an initially negative radiograph fracture for occult hip and femoral fractures, with a CT scan as a viable second option.

Surgical versus conservative treatment of greater trochanteric fractures with occult intertrochanteric fractures: Retrospective cohort study

BACKGROUND

Greater trochanter (GT) fractures are rare and frequently associated with occult intertrochanteric (IT) fractures. No consensus has been reached regarding whether surgical or conservative treatment is preferred for such fractures. The purpose of this study was to evaluate the clinical outcomes of surgical versus conservative treatment for coexistent GT and occult IT fractures.

MATERIALS AND METHODS

Between January 2006 and December 2021, we enrolled patients who were diagnosed with GT fracture on radiography or CT and underwent MRI to reveal occult IT fracture. Eligible patients were divided into two treatment groups: surgical and conservative treatment. The characteristics and outcomes of the patients were compared between the two groups.

RESULTS

Fifty patients were included in this study. There were 29 patients (3 male, 26 female; mean age: 84.45 ± 10.68 years) in the surgical treatment group and 21 patients (3 male, 18 female; mean age: 83.33 ± 9.34 years) in the conservative group, respectively. The demographic and clinical characteristics of the two groups were comparable, including sex, age, body mass index (BMI), percentage of extension into the IT area, days from injury to diagnosis, and activities of daily living (ADL) before injury. All 50 patients healed without displaced fractures, regardless of the percentage of extension into the IT area. There were no significant differences in the modified functional ambulation category scores between the two groups at one week, one month, and three months following the start of the treatment intervention (P = 0.653, 0.923, and 0.577, respectively). The length of hospital stay was 48.4 ± 5.97 days in the surgical treatment group and 50.6 ± 7.55 days in the conservative treatment group (P = 0.422). There was no significant difference in one-year mortality between surgical and conservative treatments (P = 0.219).

CONCLUSIONS

There were no significant differences in any outcome between the surgical and nonsurgical treatment groups. The results of the study suggested that coexistent GT and occult IT fractures may be managed conservatively without developing complete fractures, regardless of extension into the IT area.

A Scientific Proposal for Surgical Decision-Making in Occult Intertrochanteric Fractures Based on Finite Element Analysis

Background In the treatment of femoral intertrochanteric fractures, there is still a lack of consensus on the optimal approach for isolated greater trochanteric fractures and insufficient intertrochanteric fractures. The limited number of patients and restricted access to accurate assessment of fracture extension using magnetic resonance imaging contribute to the unclear treatment strategy. This study aims to utilize finite element (FE) analysis to analyze stress values at the fracture line and investigate their influence on intertrochanteric fracture extension under different loading conditions. The hypothesis is that fracture extension occurs following certain conditions, supporting the need for surgery based on scientific evidence. Methodology Osseous data from a computed tomography (CT) scan was used to create a proximal femur FE model using FEA software. CT scan data were converted to Digital Imaging and Communications in Medicine format and used to generate the FE model. Trabecular bone and cortex were meshed into tetrahedral elements. The model consisted of 1,592,642 elements and 282,530 nodes. Two models were created, namely, healthy proximal femur (HF) and femoral insufficient intertrochanteric fracture (FIF). Material properties were assigned based on CT values and conversion equations. The distal end of the femur was constrained. Stress analysis using the dynamic explicit approach was performed. Von Mises stresses were calculated for the proximal femur. The number of elements exceeding yield stress was counted to predict fracture risk by focusing on fracture line spots. In this study, the distribution of von Mises stress was compared between the HF and the FIF models. Six loading combinations were considered, namely, two weight-bearing conditions (3 W loading simulating for walking and 1/3 W for touch-down standing) and three hip flexion angles (0°, 15°, and 23°). Results Under 3 W loading, no significant stress elevations were observed in the HF model at any flexion angles. However, the FIF model exhibited increased stress at the site of the posterior fracture line extension. This stress-induced element destruction was observed in both cortical and cancellous bone. For the 1/3 W loading condition, only minimal stress elevation was observed in both HF and FIF models. To assess the influence on fracture extension, the number of yielded elements was evaluated along the fracture line edges (greater trochanter and middle of the intertrochanteric ridge). Under 3 W loading, the HF model had only one yielded element, indicating minimal fracture risk. In contrast, the FIF model exhibited a notable presence of yield elements in various regions (total/greater trochanter/shaft) at different flexion angles: 0° (115/16/28), 15° (265/158/23), and 23° (446/233/34). Under the 1/3 W loading condition, neither the HF nor the FIF models showed any yielding elements, regardless of the direction of external force. Conclusions The results demonstrated elevated stress levels at the fracture line in the FIF model, particularly during walking, indicating a higher risk of fracture extension at the flex position. However, under reduced weight-bearing conditions, the stress at the fracture site remained within the yield stress range, suggesting a relatively low risk of fracture extension. These findings hold significant clinical implications for developing surgical protocols that consider patients' compliance with weight-bearing restrictions.

Occult fracture propagation in patients with isolated greater trochanteric fractures: patterns and management

OBJECTIVE

To demonstrate the degrees of occult intertrochanteric extension on MRI in patients with a greater trochanteric fracture on radiography or computer tomography (CT) and whether these patients undergo conservative or surgical management with hardware.

MATERIALS AND METHODS

Retrospective review was performed of 146 patients (104 females, 42 males, ages 33-102) who had follow-up MRI after identification of a greater trochanteric fracture without intertrochanteric extension on radiography or CT. Extent of intertrochanteric extension was recorded. Subsequently, EMR review was performed to see if patients underwent surgery. Specific note was made of hardware type. Analysis was performed to determine if there is a correlation with fracture type and surgical management as well as fracture type and age and gender.

RESULTS

Nineteen patients had horizontal greater trochanter fractures without intertrochanteric extension; none underwent surgery. Seventeen patients had a vertical fracture along the lateral femoral cortex; one underwent surgery. Thirty-three patients had a fracture with intertrochanteric extension less than 50% in the mid coronal plane; 21 underwent surgery. Forty patients had intertrochanteric extension greater than 50% in the midcoronal plane not contacting the medial cortex; 28 underwent surgery. Thirty-seven patients had fractures contacting the medial cortex; 28 underwent surgery. There was significant difference with fractures extending 50% or greater of the midline of the intertrochanteric region undergoing surgical management compared with fractures less than 50% (p < 0.0001).

CONCLUSION

MRI identifies the presence and extent of occult intertrochanteric fractures in patients with greater trochanteric fractures. Description of intertrochanteric fractures on MRI helps determine the patient's treatment course and influence surgical decisions.

Incomplete Intertrochanteric Fracture: A Pattern Analysis Using Multiplanar Reformation Computed Tomography

Background

Incomplete fractures are assumed to occur in the intertrochanteric area as fractures at other sites, but reports of incomplete intertrochanteric fractures (IIFs) are rare. In 1999, Schultz et al. defined isolated greater trochanter fractures (GTFs) as IIFs when intertrochanteric extension is observed on magnetic resonance (MR) images. On multiplanar reformation computed tomography (MPR CT) images acquired for further study of apparently isolated GTFs, we noted incomplete cortical breakage in the intertrochanteric area. We then found that the fracture line was incomplete on plain radiographs in some intertrochanteric fractures. We evaluated IIFs and apparently isolated GTFs using MPR CT and analyzed the fracture patterns of IIFs that were confirmed using MPR CT.

Methods

Between February 2006 and June 2019, 36 cases of IIF were detected using MPR CT in 36 patients. They were 17 women and 19 men with a mean age of 74.7 years (range, 26–94 years). Plain radiographs and MPR CT images were evaluated by two experienced orthopedic surgeons. In addition, MR imaging was performed in 5 cases.

Results

Plain radiographs showed no evidence of fracture in 2 cases, isolated GTF in 7 cases, and IIF in 27 cases. In all cases, incomplete cortical breakage in the intertrochanteric area was confirmed on MPR CT images. Cortical breakage was located in the anterior portion of the intertrochanteric area, whereas the posterior portion remained intact in all cases. The detection rate of cortical breakage was higher on coronal or sagittal images than that on axial images. On MR images of 5 cases, intertrochanteric extensions were found in the medullary space. All extensions originated in the greater trochanter area and extended anteriorly in the axial plane and inferomedially in the coronal plane. On the T1-weighted mid-coronal image, the extension reached or passed the midline in 3 cases, and cortical breakage was detected in only 2 cases.

Conclusions

In all cases of IIF, cortical breakage was detected in the anterior portion of the proximal femur, leaving the posterior cortex intact. This finding is notably different from that of intertrochanteric extension (from posterior to anterior) detected on MR images of isolated GTFs.

The incidence and management of Isolated Greater Trochanteric Fractures - A systematic review of 166 cases

BACKGROUND

Isolated fractures of the greater trochanter are unusual injuries with a wide spectrum of presentation, investigations and management strategies.

AIMS

The objective of this study was to evaluate the incidence and treatment protocols used in the management of Isolated Greater Trochanteric Fractures (IGTF).

METHODS

A systematic literature review of the PubMed and Central Register of Controlled Trials (Cochrane) databases by using the search term 'greater trochanter fracture and hip fracture' was conducted for Randomised Controlled Trials (RCT's), including prospective and retrospective non-experimental studies.

RESULTS

The search yielded 15 studies meeting our inclusion criteria encompassing 166 patients with Isolated Greater Trochanteric Fractures (IGTF). Most of the reports were observational studies due to paucity of coverage on this topic in literature. Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) were the common modalities used to diagnose these injuries. Most of the patients were managed with non-operative methods.

CONCLUSION

This systematic review analyses the consensus of treatment of IGTF based on evidence-based practice. When the IGTF is identified, the majority of studies advocate conservative management to surgery for such cases. Furthermore, large cohort studies with clearly documented outcome follow up are required to establish objective treatment guidelines for IGTF.

Management of isolated greater trochanteric fractures of the hip – Experience from a major trauma centre over a 24-month period

Introduction

Isolated greater trochanteric fractures (IGTfs) of the femur are uncommon. At least 10% of these fractures have an occult intertrochanteric extension. Mobilisation too early without care can lead to fracture propagation, requiring surgical fixation. There is no definite consensus in the literature on how to manage initially diagnosed IGTf with potential occult intertrochanteric extension. We reviewed the management of IGTf in our major trauma centre (MTC) and propose a management flow chart.

Methods

The electronic notes and images for all IGTf admitted under or referred to the orthopaedic team at a MTC, from June 2015 to July 2017, were reviewed. Data were collected on fracture pattern and diagnostic imaging modalities. Periprosthetic fractures were excluded.

Results

1550 neck of femur fracture patients were admitted over the 2-year period; 790 patients (51%) had a fracture around the intertrochanteric region and 49 (3.2%) were diagnosed with a IGTf on plain radiographs. 98% of patients had further imaging after initial plain film radiographs, and 58% of all IGTf were shown to have an intertrochanteric extension. Overall 16/49 patients (32.7%) needed an operation.

Conclusions

An IGTf not crossing the medullary canal into the calcar (i.e >50% of the diameter) does not require surgical fixation and can be managed with analgesia and supervised mobilisation. The 30-day mortalities in both operative and non-operative groups were similar at 2% and 2.2%, respectively. Overall mortality is half of the total neck of femur fracture population (4.1%) in our MTC. We propose a management flow chart for this patient cohort.

MRI-only occult geriatric hip fractures: is displacement common with nonoperative treatment?

INTRODUCTION

Although surgical fixation is routinely recommended for geriatric hip fractures, nonoperative treatment may be an option for certain stable fracture patterns. Occult hip fractures are nondisplaced fractures not evident on radiographs, but display intraosseous edema on MRI. Our aim is to report the rate of nonoperative treatment failure in patients with occult geriatric hip fractures.

METHODS

All nonoperatively treated femoral neck or intertrochanteric femur fractures (AO/OTA 31A and 31B) from 2003 to 2018 were identified. Patients older than 65 years with negative radiographs but a hip fracture evident on MRI were included. Patients who died prior to fracture displacement or union were excluded. Charts and imaging were reviewed for demographic data, fracture type, clinical course, displacement, and whether corrective surgery was performed.

RESULTS

Of 15 final study patients, there were 6 femoral neck and 9 intertrochanteric fractures. Two fractures displaced, both requiring surgery (2/15; 13.3%). Both displacements occurred in the femoral neck group (2/6; 33%) compared to none in the intertrochanteric cohort (0/9; 0%). This trend did not reach statistical significance (p = 0.14).

CONCLUSION

Thirty-three percent (2/6, 33%) of femoral neck fractures displaced and required surgery. The remainder of the cohort (13/15, 87%) healed without complication, including all of the intertrochanteric fractures (9/9, 100%). Although this difference did not reach statistical significance, the results may better inform treatment discussions for geriatric patients with occult hip fractures diagnosed by MRI.

LEVEL OF EVIDENCE

Level III.

Computed tomography-based diagnosis of occult fragility hip fractures offer shorter waiting times with no inadvertent missed diagnosis

PURPOSE

Surgical delay due to the wait for advanced cross-sectional imaging in occult fragility hip fracture management is not well studied. Our study aims to investigate computed tomography (CT) as an alternative to the gold standard magnetic resonance imaging (MRI) in occult hip fracture workup to decrease surgical delay.

METHODS

We conducted a retrospective review of all CTs and MRIs performed between 2015 and 2017 for patients with clinically suspected fragility hip fractures and negative plain radiographs to investigate surgical delay resulting from the wait for advanced imaging and representations due to missed fractures.

RESULTS

A total of 243 scans (42 CTs and 201 MRIs) were performed for occult hip fracture workup over the study timeframe, of which 49 patients (20%) had occult hip fractures [CT: 6 (14%), MRI: 43 (21%), p = 0.296)]. There were no readmissions for fracture in the 12 months following a negative scan. The CT group had shorter waiting times (CT: 29 ± 24 h, MRI: 44 ± 32 h, p = 0.004) without significantly reducing surgical delay (CT: 82 ± 36 h, MRI: 128 ± 58 h, p = 0.196). The MRI group had a higher number of patients with a cancer history (p = 0.036), reflective of the practice for workup of possible metastases as a secondary intention.

CONCLUSION

Advanced cross-sectional imaging wait times in occult hip fracture workup contribute significantly to surgical delay. Modern CT techniques are not inferior to MRI in detecting occult fractures and may be a suitable alternative in the absence of a cancer history if MRI cannot be obtained in a timely fashion or is contraindicated. Clinicians should utilize the more readily available imaging modality to reduce surgical delay.

Greater trochanteric fractures with lntertrochanteric extension identified on MRI: What is the rate of displacement when treated nonoperatively?

INTRODUCTION

. Despite the ability of MRI to identify intertrochanteric (IT) fracture extension for greater trochanteric (GT) fractures, there is no consensus about which fractures require operative intervention. Previous studies have suggested GT fractures with >50% extension into the IT region might benefit from fixation. We sought to evaluate the rate at which GT fractures with IT extension displaced, requiring operative fixation.

PATIENTS AND METHODS

. This is a Retrospective Chart Review performed at a Level 1 Trauma Center. Patients included all nonoperatively treated GT fractures (OTA/AO 31A1.1) with IT extension identified on MRI between 2010 and 2017 at our institution. Patients lost to follow up prior to radiographic evidence of healing or fracture displacement were excluded. Patient charts and imaging were reviewed for demographic data, treatment plan, percent extension into the IT region (as determined from coronal MRI images), and clinical and radiographic evidence of fracture healing. Percent extension into the IT region was measured using coronal T1-weighted MRI images. The primary outcome measures were fracture displacement requiring operation and nonunion.

RESULTS

. Seventeen patients met initial inclusion criteria, with two subsequently excluded due to no radiographic follow-up. Of the 15 patients, zero had displacement of their IT fracture. None required operative intervention. All 15 patients healed their fractures. Fourteen of 15 (93%) had IT extension of 50% or less across the IT region. One patient had initial IT extension of 60%, this patient also healed without displacement.

DISCUSSION

. Incomplete intertrochanteric femur fractures are a relatively newer diagnosis that have become more prevalent with the increased usage and availability of MRI. Currently, there is no consensus on the ideal treatment of these injuries. To our knowledge, this is the largest series of its kind to help guide treatment of these GT fractures with IT extension.

CONCLUSIONS

. Fractures with less than 50% extension into the IT region have a low likelihood of future displacement and high union rates when treated nonoperatively.

LEVEL OF EVIDENCE

. IV.

Use of Advanced Imaging for Radiographically Occult Hip Fracture in Elderly Patients: A Systematic Review and Meta-Analysis

Background The overall rate of hip fractures not identified on radiographs but that require surgery (ie, surgical hip fractures) remains unclear in elderly patients who are suspected to have such fractures based on clinical findings. Moreover, the importance of advanced imaging in these patients has not been comprehensively assessed. Purpose To estimate the frequency of radiographically occult hip fracture in elderly patients, to define the higher-risk subpopulation, and to determine the diagnostic performance of CT and bone scanning in the detection of occult fractures by using MRI as the reference standard. Materials and Methods A literature search was performed to identify English-language observational studies published from inception to September 27, 2018. Studies were included if patients were clinically suspected to have hip fracture but there was no radiographic evidence of surgical hip fracture (including absence of any definite fracture or only presence of isolated greater trochanter [GT] fracture). The rate of surgical hip fracture was reported in each study in which MRI was used as the reference standard. The pooled rate of occult fracture, diagnostic performance of CT and bone scanning, and strength of evidence (SOE) were assessed. Results Thirty-five studies were identified (2992 patients; mean age, 76.8 years ± 6.0 [standard deviation]; 66% female). The frequency of radiographically occult surgical hip fracture was 39% (1110 of 2835 patients; 95% confidence interval [CI]: 35%, 43%) in studies of patients with no definite radiographic fracture and 92% (134 of 157 patients; 95% CI: 83%, 98%) in studies of patients with radiographic evidence of isolated GT fracture (moderate SOE). The frequency of occult fracture was higher in patients aged at least 80 years (44%, 529 of 1184), those with an equivocal radiographic report (58%, 71 of 126), and those with a history of trauma (41%, 977 of 2370) (moderate SOE). CT and bone scanning yielded comparable diagnostic performance in the detection of radiographically occult hip fracture (P = .67), with a sensitivity of 79% and 87%, respectively (low SOE). Conclusion Elderly patients with acute hip pain and negative or equivocal findings at initial radiography have a high frequency of occult hip fractures. Therefore, the performance of advanced imaging (preferably MRI) may be clinically appropriate in all such patients. © RSNA, 2020 Online supplemental material is available for this article.

Use of computed tomography and magnetic resonance imaging for occult neck of femur fractures: A single-centre study

OBJECTIVE

Neck of femur (NOF) fractures are common and serious injuries in the elderly. When a NOF fracture is suspected but is not clearly visible on radiographs, guidelines recommend magnetic resonance imaging (MRI), or computed tomography (CT) if MRI is not available/contraindicated. The aim of our study was to review the use of CT and subsequent MRI for suspected NOF fractures in patients with negative or equivocal radiographs.

METHODS

A retrospective review of adult patients with negative or equivocal plain radiographs with suspected NOF fractures presenting between 1 July 2015 and 30 June 2017 was performed. Review of CT and subsequent MRI studies was performed with documentation of reported findings, time intervals from plain radiographs to CT and MRI and final outcomes.

RESULTS

A total of 184 CT studies in 181 patients were reviewed; median age was 82 years (interquartile range 71-89 years) with 110 (60.8%) female patients. CT reported 20 occult fractures; all proceeded to surgery. MRI was performed in 23 patients and revealed additional four NOF fractures missed by CT. An additional fifth fracture missed by CT was confirmed by follow-up radiographs. Median time was approximately 4 h from radiographs to CT and approximately 56 h from radiographs to MRI.

CONCLUSION

Access to CT for evaluation of suspected occult NOF fractures is much quicker compared to MRI. When CT results are negative with on-going clinical suspicion of an occult fracture, MRI should be performed in a time efficient manner.

Time-Dependent Magnetic Resonance Imaging Changes in Occult Femoral Neck Fracture During Conservative Treatment: A Case Report

CASE

A 53-year-old woman presented to the emergency department with persistent left hip pain after a fall while riding a bicycle. Although x-ray imaging revealed no evidence of fracture, an abnormal intensity vertical line along the left femoral neck was observed in the magnetic resonance imaging (MRI). Furthermore, 2 weeks after injury, MRI revealed a newly developed abnormal intensity oblique band at the femoral neck. After discussing several treatment options with the patients, she chose the conservative treatment.

CONCLUSION

Careful follow-ups and MRI were undertaken 6 times within 32 weeks. Bone union was observed 32 weeks after the injury, and no bone displacement was observed.

Value of CT to detect radiographically occult injuries of the proximal femur in elderly patients after low-energy trauma: determination of non-inferiority margins of CT in comparison with MRI

PURPOSE

To determine the margins of non-inferiority of the sensitivity of CT and the sample size needed to test the non-inferiority of CT in comparison with MRI.

MATERIALS AND METHODS

During a 2-year period, elderly patients with suspected radiographically occult post-traumatic bone injuries were investigated by CT and MRI in two institutions. Four radiologists analyzed separately the CT and MRI examinations to detect post-traumatic femoral injuries. Their sensitivities at CT (SeCT) and MRI (SeMRI) were calculated with the reference being a best valuable comparator (consensus reading of the MRI and clinical follow-up). ROC analysis followed by an exact test (Newcombe's approach) was performed to assess the 95% confidence interval (CI) for the difference SeCT-SeMRI for each reader. A sample size calculation was performed based on our observed results by using a one-sided McNemar's test.

RESULTS

Twenty-nine out of 102 study participants had a post-traumatic femoral injury. SeCT ranged between 83 and 93% and SeMRI ranged between 97 and 100%. The 95% CIs for (SeCT-SeMRI) were [- 5.3%, + 0.8%], (p^R1 = 0.1250), [- 4.5%; + 1.2%] (p^R2 = 0.2188), [- 3.4%; + 1.1%] (p^R3 = 0.2500) to [- 3.8%; + 1.6%] (p^R4 = 0.3750) according to readers, with a lowest limit for 95% CIs superior to a non-inferiority margin of (- 6%) for all readers. A population of 440 patients should be analyzed to test the non-inferiority of CT in comparison with MRI.

CONCLUSION

CT and MRI are sensitive for the detection of radiographically occult femoral fractures in elderly patients after low-energy trauma. The choice between both these modalities is a compromise between the most available and the most sensitive technique.

KEY POINTS

• The sensitivity of four separate readers to detect radiographically occult post-traumatic femoral injuries in elderly patients after low-energy trauma ranged between 83 and 93% at CT and between 97 and 100% at MRI according to a best valuable comparator including MRI and clinical follow-up. • CT is a valuable alternative method to MRI for the detection of post-traumatic femoral injuries in elderlies after low-energy trauma if a 6% loss in sensitivity can be accepted in comparison with MRI. • The choice between CT and MRI is a compromise between the most available and the most sensitive technique.

The Frequency of Occult Intertrochanteric Fractures among Individuals with Isolated Greater Trochanteric Fractures

Purpose

Isolated greater trochanteric (GT) fractures are often identified using plain radiography of patients with post-traumatic hip pain. In many cases, the fracture extends to form an occult intertrochanteric fracture. We conducted a study to determine the frequency of occult intertrochanteric fractures in patients diagnosed with isolated GT fractures using plain radiographs.

Materials and Methods

Among 3,017 individuals who visited our emergency department with a trauma-induced pertrochanteric femur fracture between July 2004 and March 2018, 100 patients diagnosed with isolated GT fractures using plain radiographs were retrospectively analyzed. Patients were divided into two groups, those with: i) isolated GT fractures (group A) and ii) occult intertrochanteric fractures (group B). In addition, plain radiographs, magnetic resonance imaging results, and treatment methods were further analyzed in each group. If surgery treatment was needed, it was performed by one surgeon, and in all cases, a 2-hole dynamic hip screw was used.

Results

Among the 100 cases of isolated GT fractures diagnosed using plain radiograph, additional examinations revealed that 10 (10.0%) were suffering from isolated GT fractures alone, while the remaining 90 (90.0%) were further diagnosed with occult intertrochanteric fracture. Gender, age, mechanism of injury, and bone mineral density did not correlate with fracture type.

Conclusion

In our analysis, 90% of injuries initially diagnosed as isolated GT fractures were found to extend into occult intertrochanteric fractures upon further examination with additional imaging modalities. Therefore, additional evaluation should be performed to test for the potential presence of occult intertrochanteric fractures and to establish appropriate treatment plans.

Outcomes of Magnetic Resonance Imaging Detected Occult Neck of Femur Fractures: Do They Represent a Less Severe Injury with Improved Outcomes?

Purpose

Occult hip fractures in the elderly can be missed on standard radiographs and are a known cause of morbidity. These are generally diagnosed on either magnetic resonance imaging (MRI) or computed tomography scan, depending upon local hospital policy. While there is an abundance of literature on hip fractures in general, little is known about the clinical outcome of patients with occult hip fractures. The aim of this study was to review the demographics, injury characteristics, management and clinical outcome of patients diagnosed with occult femoral neck fractures on MRI.

Materials and Methods

Using an existing hospital database, a retrospective analysis of all patients with occult hip fractures diagnosed by MRI scan from 2005 to 2014 was conducted.

Results

Sixty-four patients (23 males and 41 females) were included. The mean duration of hospitalisation was 16 days. A significantly higher percentage of patients were discharged to their pre-existing residence compared to National Institute for Health and Care Excellence (NICE) commissioning guidelines (66% vs. 45%). The 30- and 60-day mortalities were 3% and 10%, respectively. Mortality was lower in patients who underwent internal fixation (n=3/31) compared with those undergoing replacement (hemi/total hip arthroplasty) (n=5/12) (P=0.056).

Conclusion

Patients with occult hip fractures diagnosed on an MRI scan are more likely to be discharged to their pre-existing residence and have lower mortality rates compared to NICE guidelines and National Hip Fracture Database (NHFD).

Fragility fractures of the proximal femur: review and update for radiologists

Proximal femoral fragility fractures are common and result in significant morbidity and mortality along with a considerable socioeconomic burden. The goals of this article are to review relevant proximal femoral anatomy together with imaging, classification, and management of proximal femoral fragility fractures, and their most common complications. Imaging plays an integral role in classification, management and follow-up of proximal femoral fragility fractures. Classification of proximal femoral fragility fractures is primarily based on anteroposterior hip radiographs. Pertinent imaging features for each category of proximal femoral fractures that would guide management are: differentiating nondisplaced from displaced femoral neck fractures, distinguishing stable from unstable intertrochanteric fractures, and determining the morphology and comminution of subtrochanteric fractures. Treatment of proximal femoral fragility fractures is primarily surgical with either arthroplasty or internal fixation. Intramedullary nailing is used in the treatment of some types of proximal femoral fragility fractures and may be associated with unique complications that become evident on postoperative follow-up radiographs.

Diagnostic strategy for elderly patients with isolated greater trochanter fractures on plain radiographs

Background

Isolated greater trochanter (GT) fractures are relatively rare and few studies have assessed the appropriate diagnostic and therapeutic strategies for these fractures. When initial plain radiographs show an isolated GT fracture, underestimation of occult intertrochanteric extension may result in displacement of a previously non-displaced fracture. This study examined the clinical results and value of different diagnostic strategies in elderly patients with isolated GT fractures on plain radiographs.

Methods

Between January 2010 and January 2015, 30 patients with initial plain radiographs showing isolated GT fractures were examined using MRI, bone scanning and/or CT for suspected occult intertrochanteric extension. We assessed the sensitivity, specificity, and positive and negative predictive value of each test. In addition, we noted the location of the fracture or soft-tissue injury on MRI in addition to treatment results.

Results

All 30 patients had osteoporosis and fractures caused by minor trauma. MRI revealed isolated GT fractures in nine patients and occult intertrochanteric fractures in 21 patients. Using the MRI-based diagnosis as a reference, the results showed that plain radiographs, bone scans, and CT scans can be used for supplementary examination but they are not appropriate as confirmatory tests for these fractures. However, in patients with both isolated GT fractures seen on plain radiographs and increased uptake in only the GT area on bone scans, MRI revealed isolated GT fractures. The fractures were treated surgically in 20 patients and conservatively in 10 patients with satisfactory clinical results.

Conclusions

We confirmed that MRI-based examination is useful in all symptomatic elderly patients whose plain radiographic findings reveal isolated GT fractures. However, we suggest that there is a need to establish a diagnostic strategy through increased understanding of the available diagnostic methods. We believe that surgical treatment should be considered in patients with occult intertrochanteric fractures that are detected on MRI.

How can MRI change the treatment strategy in apparently isolated greater trochanteric fracture?

INTRODUCTION

The purpose of this study was to evaluate the proportion of greater trochanter (GT) fractures with occult extension to the intertrochanteric region on magnetic resonance imaging (MRI) among apparently isolated GT fractures and to investigate the use of MRI for formulating a treatment strategy in patients with isolated GT fractures.

PATIENTS AND METHODS

This retrospective cohort study reviewed 37 patients with isolated GT fractures on plain radiography. Surgical or conservative treatment was decided according to MRI findings. We divided patients into 3 groups according to the extension of the fracture line. In group 1, the fracture line was within the lateral one-third in the coronal plane. In group 2, the fracture line extended from the lateral one-third to the medial one-third. In group 3, the fracture line extended over the medial one-third and/or to the medial cortex of the femur. Conservative treatment was performed in groups 1 and 2, and surgical treatment was performed in group 3. The clinical results, radiography findings, and MRI findings were investigated.

RESULTS

MRI revealed hidden intertrochanteric fractures (groups 2 [n = 10] and 3 [n = 4]) in 38% of apparently isolated GT fractures on radiography. No displacement was found in groups 1 (n = 23) and 2. Of the 4 patients in group 3, 3 were treated surgically and achieved good functional results and 1 refused to undergo surgery and finally developed complete intertrochanteric fracture. This patient presented 5 days later with increased hip pain, and radiography demonstrated displacement of the fracture, prompting surgical intervention.

CONCLUSIONS

The evaluation of apparently isolated GT fractures using MRI can be useful to diagnose the extent of the occult fracture and determine the treatment strategy.

Magnetic resonance imaging for verifying hip fracture diagnosis why, when and how?

INTRODUCTION

Hip fractures are commonly diagnosed by plain radiography. When a patient presents with negative radiographs and high clinical suspicion of fracture, guidelines recommend proceeding with magnetic resonance imaging (MRI) to diagnose the patient. The aim of this study was to assess the use of MRI in diagnosing hip fractures following trauma to the hip and describe clinical outcome after MRI-diagnosed hip fractures. The perspective was to develop new recommendations for MRI use.

MATERIALS AND METHODS

616 patients at a university hospital fulfilled the inclusion criteria of having an MRI scan of the hip following trauma between the years of 2005 and 2014. Data was collected from the patients' medical records.

RESULTS

The annual number of MRIs increased over the ten-year period. Out of 616 MRI scans 228 (37%) showed fracture of the hip with a dominance of trochanteric fractures, 185 (30%) revealed pelvic fracture and 183 (29%) were negative. No patient with acute pelvic fracture had associated fracture of the hip. The main reason to proceed with MRI was a strong clinical suspicion of fracture in patients with negative initial radiographs. Amongst the 228 patients with fracture, 187 (82%) were treated operatively. Of patients with hip fracture, 90 (39%) patients suffered a general complication and 11 (5%) had hip complications. The complication rate of patients with fracture on MRI was compared to that of a cohort of general hip fracture patients at our hospital. No significant difference in twelve months' survival or general complications could be found, but the MRI group had a significantly lower hip complication rate.

CONCLUSION

The diagnosis set by MRI, with high share of pelvic fractures or no fracture, reflects the difficulty in differential diagnosing this group of patients. The rate of occult hip fractures was low and patients with pelvic fractures already known from X-ray did not have additional hip fractures. We found an increase in the annual number of MRIs during the 10-year-period. MRI-diagnosed hip fracture patients do not suffer more complications than the regular hip fracture patient.

The sensitivity of ct scans in diagnosing occult femoral neck fractures

Non-displaced hip fractures can be difficult to diagnose on plain film radiographs. When there is ongoing clinical suspicion of an occult fracture, further imaging is obtained. We investigated the sensitivity of computed tomography (CT) scans in detecting these fractures and the delays to surgery that three-dimensional imaging causes. We identified 78 CT scans performed for possible hip fractures over the past 3 years with the presence and absence of a fracture recorded. Based on subsequent imaging, the accuracy of CT scans was determined. CT scanning yielded sensitivity was 86% and specificity 98% for occult hip fracture (OHF). The median delay to definitive diagnosis was 37h. Our results demonstrate that CT scan does not bear sufficient sensitivity to detect all OHFs. We therefore recommend that MRI should be offered when a fracture is suspected. CT scans should be reserved for when MRI is not available, but a negative scan should be confirmed with subsequent MRI.

Diagnostic Imaging Strategies for Occult Hip Fractures: A Decision and Cost-Effectiveness Analysis

OBJECTIVE

Hip fractures cause significant morbidity and mortality. Determining the optimal diagnostic strategy for the subset of patients with potential occult hip fracture remains challenging. We determined the most cost-effective strategy for the diagnosis of occult hip fractures from the choices of performing only computed tomography (CT), performing only magnetic resonance imaging (MRI), performing CT and if negative performing MRI (MRI-selective strategy) or discharging the patient without advanced imaging.

METHODS

We developed a decision-analytic model to compare outcomes and costs of different diagnostic strategies for the diagnosis of an occult hip fracture from a societal perspective. Model inputs were derived from charge data, Medicare reimbursements, and the literature. Strategies with an incremental cost-effectiveness ratio (ICER) below $100,000 per quality-adjusted life-year (QALY) gained were considered cost-effective. We tested the robustness of our results using probabilistic sensitivity analysis.

RESULTS

Compared to a CT strategy, MRI provides an additional 0.05 QALY at an incremental cost of $1,227 and ICER of $25,438/QALY. For facilities without MRI capability, if the cost of transfer is below $1,228, transferring the patient to a MRI-capable facility is the most cost-effective strategy. Above this cost, employing a CT and if negative transfer to a MRI-capable facility strategy was more cost-effective. When the cost of a transfer reached more than $4,039, it became more cost-effective to only obtain a CT.

CONCLUSION

MRI is a cost-effective strategy for the diagnosis of an occult hip fracture. For facilities without MRI capability, the most cost-effective strategy depends on the cost of the interfacility transfer.

Occult Intertrochanteric Fracture Mimicking the Fracture of Greater Trochanter

PURPOSE

Occult intertrochanteric fractures are misdiagnosed as isolated greater trochanteric fractures in some cases. We investigated the utility of three-dimensional computed tomography (3D-CT) and magnetic resonance imaging (MRI) in the diagnosis and outcome management of occult intertrochanteric fractures.

MATERIALS AND METHODS

This study involved 23 cases of greater trochanteric fractures as diagnosed using plain radiographs from January 2004 to July 2013. Until January 2008, 9 cases were examined with 3D-CT only, while 14 cases were screened with both 3D-CT and MRI scans. We analyzed diagnostic accuracy and treatment results following 3D-CT and MRI scanning.

RESULTS

Nine cases that underwent 3D-CT only were diagnosed with isolated greater trochanteric fractures without occult intertrochanteric fractures. Of these, a patient with displacement received surgical treatment. Of the 14 patients screened using both CT and MRI, 13 were diagnosed with occult intertrochanteric fractures. Of these, 11 were treated with surgical intervention and 2 with conservative management.

CONCLUSION

Three-dimensional CT has very low diagnostic accuracy in diagnosing occult intertrochanteric fractures. For this reason, MRI is recommended to confirm a suspected occult intertrochanteric fracture and to determine the most appropriate mode of treatment.

The validity of investigating occult hip fractures using multidetector CT

OBJECTIVE

10% of all hip fractures are occult on plain radiography, requiring further investigation to ascertain the diagnosis. MRI is presently the gold standard investigation, but frequently has disadvantages of time delay, resulting in increased hospital stay and mortality. Our aim was to establish whether multidetector CT (MDCT) is an appropriate first-line investigation of occult femoral neck (NOF) fractures.

METHODS

From 2013, we elected to use MDCT as the first-line investigation in patients believed to have an NOF fracture with negative plain films. These were reported by consultant musculoskeletal radiologists. We retrospectively analysed the data of consecutive patients presenting to the University Hospital of Wales, over 30 months with a clinical suspicion of a hip fracture.

RESULTS

1443 patients were admitted during the study period. 209 (14.5%) patients had negative plain films requiring further investigation to exclude an NOF fracture, of which 199 patients had a CT. 93 patients had no fracture and 20 patients had isolated greater trochanter fractures. None of these patients progressed to develop an intracapsular femoral neck fracture at 4-month follow-up, although one patient sustained an extracapsular fracture following a high-energy fall whilst admitted. 26 femoral neck fractures were diagnosed on CT, whilst the remaining 60 patients were diagnosed with other pelvic ring fractures.

CONCLUSION

When interpreted by experienced radiologists, MDCT has both sensitivity and specificity of 100%.

ADVANCES IN KNOWLEDGE

We recommend the use of MDCT as a safe and appropriate first-line investigation for NOF fractures.

Is magnetic resonance imaging necessary in isolated greater trochanter fracture? A systemic review and pooled analysis

BACKGROUND

Isolated fractures of the greater trochanter (GT) of the femur are uncommon and few studies have assessed the diagnosis and appropriate therapeutic schedule for these fractures. The current data regarding assessment of isolated fractures of the GT are limited to a few reviews based on the experience of a single institution. Therefore, we asked the following questions: (1) what proportion of cases has an associated extension of the fracture into the intertrochanteric region in isolated GT fracture and (2) what are the treatment options and outcomes of GT fractures with occult intertrochanteric fractures.

METHODS

We conducted a systematic review of published studies that evaluated patients who displayed isolated GT fracture on routine radiographic examination and underwent a magnetic resonance imaging (MRI) scan because of the suspicion of extension into the intertrochanteric region. A structured literature review of multiple databases (PubMed, EMBASE, CINAHL, and Cochrane systematic reviews) referenced articles from 1950 to 2015.

RESULTS

A total of 110 patients were identified from 7 published studies. MRI documented isolated GT fractures diagnosed on initial radiographs in only 11 of 110 patients (10%). In 99 patients (90%), MRI examinations revealed extension of the fracture into the intertrochanteric region. Surgical fixation was necessary for 61 patients, with a pooled percentage of 55%. No complications were observed after surgery.

CONCLUSIONS

Our study has helped to elucidate further the assessment of isolated fracture of the GT. We believe that MRI is a reasonable option for patients presenting with isolated GT fracture on plain radiographs.

Multiplanar reformation computed tomogram is better than MR imaging in decision making for apparently isolated fractures of the greater trochanter

OBJECTIVES

We evaluated isolated fractures of the greater trochanter (IFGT) on plain radiographs with multiplanar reformation computed tomography (MPR CT).

DESIGN

Retrospective review of patients.

SETTING

University teaching hospital.

PATIENTS

This study included 27 consecutive patients with apparently IFGT.

MAIN OUTCOME MEASUREMENTS

The clinical results, X-ray, computed tomography, magnetic resonance imaging, bone scintigraphy findings were investigated.

RESULTS

Four of 27 cases demonstrated anterior cortical breakage or extensive damage of the trabecular bone in the intertrochanteric area on MPR CT images. Surgical fixation was necessary for these 4 cases. The other 23 cases, in which no structural damage was detected, were treated conservatively, and the results were satisfactory without progression to a complete intertrochanteric fracture. All 9 cases evaluated with magnetic resonance imaging demonstrated extension into the intertrochanteric area. In 5 cases, the extension crossed the midline on the mid-coronal image. Two of the cases were treated surgically because of anterior cortical breakage and extensive trabecular impaction on MPR CT, respectively. However, the other 3 cases and 4 cases with mild intertrochanteric extension were treated conservatively without problem.

CONCLUSIONS

The evaluation of IFGT with MPR CT was shown to be valuable for determining the optimal treatment method.

Investigation of occult hip fractures: the use of CT and MRI

Aim. At present there is no data looking at modern multislice computerised tomography (CT) in the investigation of occult hip fracture. The aim of this study was to retrospectively compare the reports of patients sent for magnetic resonance imaging (MRI) or CT with negative radiographs and a clinical suspicion of a fractured neck of femur. Methods. All patients presenting to the hospital with a clinical suspicion of a hip fracture but initial negative radiographs over a three-year period were included. Patients were either investigated with an MRI scan or CT scan. The presence of a fracture, the requirement for surgery, and any further requirement for imaging were recorded. Results. Over three years 92 patients were included of which 61 were referred for a CT and 31 for an MRI. Thirty-four patients were found to have a fracture. Of these, MRI picked up a fracture in 36% and CT in 38% of referrals. Discussion. Up to 10% of proximal femur fractures may be missed on initial radiographs. Current guidelines state patients should be offered MRI if hip fracture is suspected despite negative hip radiographs. Our findings show that modern multislice CT may be comparable with MRI for detecting occult fracture.

Radiographically occult femoral and pelvic fractures are not mutually exclusive: a review of fractures detected by MRI following low-energy trauma

OBJECTIVES

The purpose of this study was to review the MRI examinations of a large group of low-energy trauma patients in whom pelvic MRI had detected radiographically occult fractures, in order to characterize prevailing fracture patterns and determine how often co-existing proximal femoral and pelvic fractures were observed.

METHODS

All patients having pelvic MRI over 5 years were identified. Word-search software selected 269 MRI reports containing the term ‘fracture’. Further scrutiny identified 168 with diagnosis of fracture. MRI request and imaging record review identified 102 low-energy trauma cases that had MRI for clinical suspicion of fracture despite normal radiographs. Sixty-six cases were excluded for the following reasons: no expressed clinical suspicion of occult fracture; history suggesting high-energy trauma;skeletal co-morbidity hindering acute fracture identification;interval more than 2 weeks between radiographs and MRI. The 102 study MRI examinations, which employed a limited two-sequence protocol, were reviewed. Any fracture that had not been appreciated on radiographs was recorded and characterized as femoral, pelvic, or co-existing femoral and pelvic fractures.

RESULTS

The 102 study cases had a median age of 82 years.The median interval between pelvic radiographs and MRI was 3 days. MRI showed undiagnosed femoral fracture in 48/102 cases (47.1%), sacral fracture in 41/102 (40.2%),and pubic fracture in 55/102 (53.9%). In 11/102 cases(10.8%), MRI showed undiagnosed fractures of both proximal femur and pelvic ring (seven sacral, six pubic bone, two other site fractures). In 10/11 cases with coexisting femoral and pelvic fractures, the femoral fracture was incomplete.

CONCLUSIONS

Limited pelvic MRI found a high prevalence of radiographically occult femoral and pelvic fractures in low-energy trauma patients, with clinical suspicion of fracture despite normal radiographs. Co-existing occult femoral and pelvic ring fractures were commonly observed, and in such cases, the femoral fracture was likely to be incomplete and multiple pelvic fractures were typically present.

Review article: Magnetic resonance imaging and computed tomography in the diagnosis of occult proximal femur fractures

Electronic databases of MEDLINE, EMBASE, CINAHL, and the Cochrane Library as well as the Google Scholar search engine were used. Studies written in the English language highlighting the use of magnetic resonance imaging (MRI) and computed tomography in diagnosing occult proximal femoral fractures despite negative or equivocal plain radiographs were included. Two reviewers independently extracted data from each article. Raw frequencies for each of the details investigated were calculated. 15 prospective and 7 retrospective studies from 1989 to 2009 were included in this systematic review. A total of 996 patients (mean age, 75 years; standard deviation, 5 years) with suspected occult proximal femur fractures underwent MRI for further assessment. 350 (35%) of the patients tested positive for proximal femoral fractures, of whom 295 (84%) underwent further treatment/surgical interventions. MRI also detected other fractures and soft-tissue injuries. MRI was superior to other imaging modalities in diagnosing occult proximal femoral fractures and should be performed within 24 hours of injury. Early diagnosis and management may avoid substantial displacement and complications, and improve overall mortality and morbidity.

The use of MRI to detect occult fractures of the proximal femur: a study of 102 consecutive cases over a ten-year period

An MR scan was performed on all patients who presented to our hospital with a clinical diagnosis of a fracture of the proximal femur, but who had no abnormality on plain radiographs. This was a prospective study of 102 consecutive patients over a ten-year period. There were 98 patients who fulfilled our inclusion criteria, of whom 75 were scanned within 48 hours of admission, with an overall mean time between admission and scanning of 2.4 days (0 to 10). A total of 81 patients (83%) had abnormalities detected on MRI; 23 (23%) required operative management. The use of MRI led to the early diagnosis and treatment of occult hip pathology. We recommend that incomplete intertrochanteric fractures are managed non-operatively with protected weight-bearing. The study illustrates the high incidence of fractures which are not apparent on plain radiographs, and shows that MRI is useful when diagnosing other pathology such as malignancy, which may not be apparent on plain films.

Are occult fractures of the hip and pelvic ring mutually exclusive?

We have evaluated retrospectively the relationship of bony injuries seen on 106 consecutive MR scans in elderly patients of a mean age of 81.4 years (67 to 101) who were unable to bear weight after a low-energy injury.

There were no visible fractures on plain radiographs of the hip but eight patients (7.5%) had fractures of the pubic ramus. In 43 patients (40.5%) MRI revealed a fracture of the femoral neck and in 26 (24.5%) there was a fracture of a pubic ramus. In 17 patients (16%) MRI showed an occult sacral fracture and all of these had a fracture of the pubic ramus. No patient with a fracture of the femoral neck had an associated fracture of the pelvic ring or vice versa. Occult fracture of the hip and of the pelvic ring appear to be mutually exclusive and if an acute fracture of the pubic ramus is diagnosed radiologically further investigations are not needed to rule out an occult fracture of the hip.