To study the role of dynamic magnetic resonance imaging in assessing the femoral head vascularity in intracapsular femoral neck fractures

Methods to predict osteonecrosis of femoral head after femoral neck fracture: a systematic review of the literature

BACKGROUND

Femoral neck fracture (FNF) is a very common traumatic disorder and a major cause of blood supply disruption to the femoral head, which may lead to a severe long-term complication, osteonecrosis of femoral head (ONFH). Early prediction and evaluation of ONFH after FNF could facilitate early treatment and may prevent or reverse the development of ONFH. In this review paper, we will review all the prediction methods reported in the previous literature.

METHODS

Studies on the prediction of ONFH after FNF were included in PubMed and MEDLINE databases with articles published before October 2022. Further screening criteria were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. This study highlights all the advantages and disadvantages of the prediction methods.

RESULTS

There were a total of 36 studies included, involving 11 methods to predict ONFH after FNF. Among radiographic imaging, superselective angiography could directly visualize the blood supply of the femoral head, but it is an invasive examination. As noninvasive detection methods, dynamic enhanced magnetic resonance imaging (MRI) and SPECT/CT are easy to operate, have a high sensitivity, and increase specificity. Though still at the early stage of development in clinical studies, micro-CT is a method of highly accurate quantification that can visualize femoral head intraosseous arteries. The prediction model relates to artificial intelligence and is easy to operate, but there is no consensus on the risk factors of ONFH. For the intraoperative methods, most of them are single studies and lack clinical evidence.

CONCLUSION

After reviewing all the prediction methods, we recommend using dynamic enhanced MRI or single photon emission computed tomography/computed tomography in combination with the intraoperative observation of bleeding from the holes of proximal cannulated screws to predict ONFH after FNF. Moreover, micro-CT is a promising imaging technique in clinical practice.

Prediction of femoral head avascular necrosis following femoral neck fracture: "pin-tract sign" of 99mTc-HDP pinhole bone scan after metallic fixation

OBJECTIVE

To evaluate the predicting value of ^99mTc-hydroxydiphosphonate (HDP) pinhole bone scan in development of osteonecrosis of femoral head (ONFH) in patients with femoral neck fracture after cannulated screw fixation.

METHODS

Pinhole bone scan of patients with metallically fixed femoral neck fracture from 2001 to 2015 were retrospectively reviewed. Initial pinhole bone scan was obtained within 2-3 weeks after surgery. Findings of initial pinhole bone scan were divided in to 4 groups. Group CU included cold defect in affected femoral head, group HU with no cold defect. Group PP with increased uptake along the inserted screws and group PN with no increased uptake along the inserted screws. More than 6 months of follow-up with pinhole bone scan and clinico-radiological evidence for ONFH was reviewed.

RESULTS

72 patients (mean age 54.01 years, male 22, female 50) were included. 19 patients were in group CU, 53 in group HU. 60 patients were in group PP, 12 in group PN. During the follow-up, 13 patients were diagnosed as ONFH. 9 (47.36%) patients in group CU developed ONFH and 4 (7.5%) in group HU. 4 (6.66%) patients in group PP developed ONFH and 9 (75%) in group PN.

CONCLUSIONS

To predict ONFH of femoral head followed by neck fracture, many imaging techniques with variable results were known. In this study, cold defect in early postoperative pinhole bone scans could predict ONFH, and loss of increased uptake along screw inserted site could be a strong indicative sign of ONFH. Further evaluation with a larger population is necessary.

Micro Perfusion and Quantitative Analysis of the Femoral Head Intraosseous Artery

The present study investigates the feasibility of micro perfusion of femoral head specimens from femoral neck fracture patients by the inferior retinacular arteries and performing intraosseous artery quantitative analysis of the femoral head. Twelve femoral neck fracture patients who had undergone conventional hip replacement surgery were included in this study. Femoral head specimen arteries were first dissected and exposed and then perfused by the inferior retinacular arteries and all the femoral heads underwent micro-CT scanning. After micro-CT scanning, a digital 3-D model was reconstructed to quantify the femoral head intraosseous arteries for comparison with a normal femoral head. The artery length density, artery volume density, and artery length/volume ratio were calculated separately and compared with normal femoral head parameters. Micro-CT scanning displayed the epiphyseal arterial network structure and their fine vascular branches in all 12 femoral neck fractures. Blood was supplied from the inferior retinacular artery to the epiphyseal arterial network then to all the fine blood vessels within the femoral head. No statistical differences were observed in femoral heads' intraosseous artery length densities or volume densities between the normal and femoral neck fracture specimens, while the artery length/volume ratio showed a statistical difference, and the ratio increased from 19 to 46. Micro perfusion of the femoral head by the inferior retinacular arteries is possible and can present the epiphyseal network and their fine arterial branches in pathologic conditions to provide a morphological basis for the study of femoral head disease.

Identifying Patients Who Will Most Benefit from Single Photon Emission Computerized Tomography and Computerized Tomography After Femoral Neck Fracture

Background

Single photon emission computerized tomography and computerized tomography (SPECT/CT) is useful for assessing blood supply within the femoral head after femoral neck fracture, but its use in all femoral neck fracture patients is not feasible. Therefore, the present study aimed to identify the patients for whom SPECT/CT examination will be most beneficial.

Material/Methods

Sixty-five patients with a unilateral femoral neck fracture who underwent SPECT/CT examination of the hip and were treated via closed reduction and internal fixation with three screws were enrolled between January 2009 and March 2011. A decision tree model (C 5.0) was used to identify the factors that best reflect blood supply and to build a flowchart for identifying patients who would benefit from SPECT/CT.

Results

Fracture type was most strongly associated with the Fracture/Normal (F/N) ratio, which reflects the blood supply to the fractured femoral head. Age and the time interval from injury to examination were also associated with the F/N ratio. SPECT/CT examination is most beneficial for patients with a displaced fracture, especially if they are over 58 years old and the time interval from injury to examination is less than 10 days.

Conclusions

Our results indicate that elderly people with a displaced fracture are most likely to benefit from SPECT/CT examination, which can show the blood supply to the femoral head within a relatively short window of time after the injury.

Prognostic value of dynamic MRI positive enhancement integral color mapping in osteosynthesis of undisplaced femoral neck fractures

AIMS

The common treatment for an undisplaced femoral neck fracture is osteosynthesis. Two major complications of osteosynthesis are non-union and late collapse of the femoral head. We speculated that femoral head perfusion is one of the most important factors that affect the outcome of osteosynthesis after femoral neck fracture. We have preoperatively estimated femoral head perfusion by dynamic MRI positive enhancement integral color mapping (PEICM). The purpose of this study was to evaluate the outcomes of undisplaced femoral neck fractures based on PEICM.

PATIENTS AND METHODS

Sixty-eight patients participated in this prospective study. All patients underwent PEICM in a 1.5-Tesla MRI machine using coronal fast spoiled gradient echo imaging sequences with gadopentetate dimeglumine as the contrast agent. Femoral head perfusion was displayed via color mapping using PEICM. Three types were distinguished. For type A, the color was identical to unaffected side indicated normal perfusion. For type B, the color was darker than unaffected side indicated decreased perfusion. For type C, the color was black indicated complete absence of perfusion. All patients underwent osteosynthesis with three cannulated screws. The rates of non-union and late collapse for each type were calculated.

RESULTS

Sixteen patients were classified as Type A, 43 as Type B, and 6 as Type C. The non-union rates were 0% for Type A, 6.7% for Type B, and 50.0% for Type C. The late collapse rates were 0% for Type A, 4.4% for Type B, and 0% for Type C.

CONCLUSION

PEICM precisely detected femoral head perfusion. Primary prosthetic replacement should be considered for older patients with Type C to minimize the chances of revision surgery, even in undisplaced femoral neck fractures.

Three-year outcomes of intracapsular femoral neck fractures fixed with sliding hip screws in adults aged under sixty-five years

INTRODUCTION

Intracapsular femoral neck fractures remain associated with high rates of post-traumatic femoral head necrosis, non-union, and revision surgery.

AIM

Our aim was to identify factors associated with revision surgery in intracapsular femoral neck fractures treated with sliding hip screws (SHS) in adults aged <65 years.

PATIENTS AND METHODS

Consecutive admissions were identified retrospectively from the Royal Victoria Hospital, Belfast, which was the largest volume hospital on the National Hip Fracture Database. Of 2201 hip fractures between 1st August 2008 and 31st December 2010, 97 (4%) intracapsular fractures treated with SHS in adults <65 years were followed for a mean of 2.9 years (range 0-6.6).

RESULTS

Twenty-one (22%) hips were revised to arthroplasty. Avascular necrosis developed in 28 (29%) femoral heads. Eight (8%) fractures proceeded to non-union. Displaced fractures (p<0.001, Fisher's exact [FE]), posterior comminution (p=0.049, FE), chronic respiratory disease (p=0.006, FE) and residual distraction (p=0.011, χ²) were associated with revision to arthroplasty. Multiple regression found displaced fractures (p=0.006) and chronic respiratory disease (p=0.017) significant; in the latter 4 of 6 were revised (67%), including all four patients with chronic obstructive pulmonary disease (COPD). Eleven (11%) individuals required walking aids before injury, which rose to 34 (35%) at one year (p<0.0001, χ²). Eighty-nine (92%) individuals could walk alone outdoors before injury, but only 76 (78%) at one year (p=0.009, χ²).

CONCLUSIONS

Displaced fractures in individuals with chronic respiratory disease should be considered high risk for revision to arthroplasty. Posterior cortex deficiency should be evaluated prior to choice of operation. Fracture biology and revascularisation play a greater role than operation timing. A significant proportion of individuals do not recovery pre-morbid mobility by one year.

Assessment of Osteonecrosis in the Presence of Instrumentation for Femoral Neck Fracture Using Contrast-Enhanced MAVRIC Sequence

BACKGROUND

Evaluating postoperative femoral neck facture (FNF) with metal fixation hardware is commonly performed using radiographs. MRI has greater sensitivity and specificity to evaluate osteonecrosis (ON) but is often challenging due to the image distortion caused by metallic hardware.

QUESTIONS/PURPOSES

The aim of this study is to compare fast spin-echo (FSE) and multi-acquisition variable-resonance image combination (MAVRIC) sequences in assessing ON following metallic fixation of FNF and determining feasibility of semi-quantitative perfusion using MAVRIC.

METHODS

Radiography and MRI were performed at 3 and 12 months postoperatively, using FSE and pre- and post-gadolinium contrast MAVRIC sequences in 21 FNF patients. The presence and volume of ON were recorded. Signal intensity (SI) enhancement was measured on the MAVRIC sequences within the center and rim of ON; with the ilium and femoral diaphysis as controls. The detection rate of ON between MAVRIC and FSE images was evaluated as the difference of percent enhancement across the defined regions of interest.

RESULTS

ON was detected in 0% of radiographs, in 67% of FSE, and in 76% of MAVRIC images at 3 months follow-up, with similar results at 12 months. MAVRIC images had larger ON volume than FSE images at both time points. A significant percentage SI enhancement was only detected in the ON rim.

CONCLUSION

Radiographs could not detect ON following metallic fixation of FNF. MAVRIC is more sensitive than FSE for determining the volume of ON. SI measurements using MAVRIC may provide an indirect assessment of perfusion.

Vascular evaluation after cervical hip fractures in children: a case series of eight children examined by scintigraphy after surgery for cervical hip fracture and evaluated for development of secondary radiological changes

Femoral neck fractures in children and young adults are rare, but have a high risk of avascular necrosis (AVN) and subsequent gradual collapse of the femoral head. In 2006, we initiated the use of scintigraphy for the diagnosis of vascular impairment after a cervical fracture in children. In the present retrospective case study, we evaluated the effect of the remaining postoperative circulation in the femoral head after fracture in terms of the development of AVN and secondary degenerative changes of the hip joint. Eight children, four girls and four boys [mean age 11.5 years (7-16)], had been operated for a cervical or a basocervical hip fracture between 2006 and 2012. The femoral head circulation was evaluated postoperatively with scintigraphy and all children had been followed radiographically for a minimum of 1 year. The Ficat classification was used to stage the AVN and the Stulberg classification was used to stage the sphericity of the femoral head at follow-up. In two patients, the femoral head had normal circulation postoperatively and they also had normal radiographs at follow-up. In two patients, the entire femoral head was avascular postoperatively and at follow-up, one patient had normal radiographs and one had both subchondral sclerosis and flattening. These two patients had been treated with bisphosphonates and prolonged non-weight-bearing. Four patients had postoperatively retained circulation in parts of the femoral head. Three of these four patients had normal radiographs at follow-up. Evaluation of the remaining circulation after surgery may help to predict the outcome and guide the postoperative regime in children with a femoral neck fracture.

Functional imaging of the musculoskeletal system

Functional imaging, which provides information of how tissues function rather than structural information, is well established in neuro- and cardiac imaging. Many musculoskeletal structures, such as ligaments, fascia and mineralized bone, have by definition a mainly structural role and clearly don't have the same functional capacity as the brain, heart, liver or kidney. The main functionally responsive musculoskeletal tissues are the bone marrow, muscle and nerve and, as such, magnetic resonance (MR) functional imaging has primarily addressed these areas. Proton or phosphorus spectroscopy, other fat quantification techniques, perfusion imaging, BOLD imaging, diffusion and diffusion tensor imaging (DTI) are the main functional techniques applied. The application of these techniques in the musculoskeletal system has mainly been research orientated where they have already greatly enhanced our understanding of marrow physiology, muscle physiology and neural function. Going forwards, they will have a greater clinical impact helping to bridge the disconnect often seen between structural appearances and clinical symptoms, allowing a greater understanding of disease processes and earlier recognition of disease, improving prognostic prediction and optimizing the monitoring of treatment effect.