Risk Stratification for Avascular Necrosis of the Femoral Head After Internal Fixation of Femoral Neck Fractures by Post-Operative Bone SPECT/CT

Residual deformity after femoral neck fracture affects the location of osteonecrosis of the femoral head

Aims

The localization of necrotic areas has been reported to impact the prognosis and treatment strategy for osteonecrosis of the femoral head (ONFH). Anteroposterior localization of the necrotic area after a femoral neck fracture (FNF) has not been properly investigated. We hypothesize that the change of the weight loading direction on the femoral head due to residual posterior tilt caused by malunited FNF may affect the location of ONFH. We investigate the relationship between the posterior tilt angle (PTA) and anteroposterior localization of osteonecrosis using lateral hip radiographs.

Methods

Patients aged younger than 55 years diagnosed with ONFH after FNF were retrospectively reviewed. Overall, 65 hips (38 males and 27 females; mean age 32.6 years (SD 12.2)) met the inclusion criteria. Patients with stage 1 or 4 ONFH, as per the Association Research Circulation Osseous classification, were excluded. The ratios of anterior and posterior viable areas and necrotic areas of the femoral head to the articular surface were calculated by setting the femoral head centre as the reference point. The PTA was measured using Palm's method. The association between the PTA and viable or necrotic areas of the femoral head was assessed using Spearman's rank correlation analysis (median PTA 6.0° (interquartile range 3 to 11.5)).

Results

We identified a negative correlation between PTA and anterior viable areas (rho -0.477; p = 0.001), and no correlation between PTA and necrotic (rho 0.229; p = 0.067) or posterior viable areas (rho 0.204; p = 0.132).

Conclusion

Our results suggest that residual posterior tilt after FNF could affect the anteroposterior localization of necrosis.

The Role of Osteogenic Effect and Vascular Function in Bone Health in Hypertensive Rats: A Study of Anti-hypertensive and Hemorheologic Drugs

Vascular dysfunction contributes to the development of osteopenia in hypertensive patients, as decreased blood supply to bones results in tissue damage and dysfunction. The effect of anti-hypertensive medicines on bone mass in hypertensive individuals is inconclusive because of the varied mechanism of their action, and suggests that reducing blood pressure (BP) alone is insufficient to enhance bone mass in hypertension. Pentoxifylline (PTX), a hemorheological drug, improves blood flow by reducing blood viscosity and angiogenesis, also has an osteogenic effect. We hypothesized that improving vascular function is critical to increasing bone mass in hypertension. To test this, we screened various anti-hypertensive drugs for their in vitro osteogenic effect, from which timolol and hydralazine were selected. In adult female spontaneously hypertensive rats (SHRs), timolol and hydralazine did not improve vascular function and bone mass, but PTX improved both. In female SHR animals, PTX restored bone mass, strength and mineralization, up to the level of normotensive control rats. In addition, we observed lower blood vasculature in the femur of adult SHR animals, and PTX restored them. PTX also restored the bone vascular and angiogenesis parameters that had been impaired in OVX SHR compared to sham SHR. This study demonstrates the importance of vascular function in addition to increased bone mass for improving bone health as achieved by PTX without affecting BP, and suggests a promising treatment option for osteoporosis in hypertensive patients, particularly at-risk postmenopausal women.

Perfusion Imaging of the Musculoskeletal System

Perfusion imaging is the aspect of functional imaging, which is most applicable to the musculoskeletal system. In this review, the anatomy and physiology of bone perfusion is briefly outlined as are the methods of acquiring perfusion data on MR imaging. The current clinical indications of perfusion related to the assessment of soft tissue and bone tumors, synovitis, osteoarthritis, avascular necrosis, Keinbock's disease, diabetic foot, osteochondritis dissecans, and Paget's disease of bone are reviewed. Challenges and opportunities related to perfusion imaging of the musculoskeletal system are also briefly addressed.

Management of Garden-I and II Femoral Neck Fractures: Perspectives on Primary Arthroplasty

This review compares internal fixation versus arthroplasty in the treatment of nondisplaced femoral neck fractures (FNFs) calling attention to evolving areas of consensus that influence clinical decision-making. The Garden classification system, typically dichotomized into nondisplaced (types I and II) and displaced (types III and IV) fractures, has been used as a guide for surgical decision-making. Conventionally, treatment of nondisplaced FNF in the elderly has been with internal fixation, and treatment of a displaced FNF has been hemi-, or more recently total hip, arthroplasty. Studies over the last decade have raised concern over the appropriate treatment of nondisplaced FNFs due to high rates of reoperation of nondisplaced FNFs treated with internal fixation. Avascular necrosis (AVN), failure of internal fixation, secondary malunion, and pin/nail penetration through the femoral head have all been observed. Several studies have attributed fixation failure to a degree of femoral neck tilt ≥20°, either posteriorly or anteriorly as seen on the lateral X-ray. Because of these observations of fixation failures, the suggestion has been made that arthroplasty be used when the degree of posterior tilt exceeds a threshold of ≥20° tilt with the expectation of diminishing failure of fixation, decreasing the risk of reoperation and preserving function without increasing mortality rate. Frustrating additional analyses are uncertainties over the mechanisms of failure of internal fixation with ≥20° tilt and the persistently substantial 1-year mortality rate after FNF, which has not been influenced by fixation or replacement type. Due to the lack of consensus regarding the determination of the appropriate surgical intervention for nondisplaced FNFs, an improved algorithm for surgical decision-making for these fractures may prove useful.

What is the best method of fixation for minimally displaced subcapital neck of femur fractures? A systematic review

BACKGROUND

Femoral neck fractures are a common cause of morbidity and mortality in the community. Minimally displaced subcapital necks of femoral fractures are usually managed with internal fixation, although there is debate as to which method is superior. This systematic review aimed to compare the outcomes of different fixation methods in the management of this common fracture.

METHODS

This systematic review was conducted in accordance with PRISMA statement guidelines. The databases searched were MEDLINE (Ovid), Cochrane Central Register of Controlled Trials, and EMBASE (Ovid). The study quality and risk of bias were assessed using the Newcastle-Ottawa Quality Assessment Scale, and relevant data were extracted and synthesised.

RESULTS

Nine articles met the inclusion criteria. A total of 819 patients were included in this study. Eight of the nine studies were case series, and one was a randomised control trial. The mean risk of bias was 7.4/9 for non-randomised articles. The fixation methods used in the included studies were dynamic hip screw (DHS), cannulated screws, Smith-Peterson nail, hooknail, Moore's pins, and Knowle's pins. DHS was found to be a superior method of fixation and was supported by a clinical trial. It has high rates of union (99 %), low rates of avascular necrosis (<1 %), and low rates of fixation failure (<1 %).

CONCLUSIONS

Based on the available data, DHS appears to be the superior method of fixation for the minimally displaced subcapital neck of femoral fractures. Given the general low level of evidence currently available, additional clinical trials are needed in this area.

Comparative Study Between Closed Reduction Internal Fixation Alone Versus Closed Reduction Internal Fixation and Addition of Muscle Pedicle Bone Graft for Prevention of Osteonecrosis in Cases of Displaced Femoral Neck Fractures

BACKGROUND

In patients of less than 60 years of age, osteosynthesis is the treatment of choice for displaced femoral neck fractures (Garden 3 and 4). Most of these fractures unite well but chances of osteonecrosis are quite high even after early operations and till date there is no well-defined method of prediction and prevention of osteonecrosis. Vascularized bone graft may prevent the development of osteonecrosis.

MATERIALS AND METHODS

This is a retrospective case control study done in an urban Medical College in eastern India and tried to evaluate efficacy of addition of quadratus femoris muscle pedicle bone graft in cases of osteosynthesis comparing the results of cases treated with closed reduction and internal fixation alone for femoral neck fractures We have taken into consideration 45 consecutive cases from each group with identical demographic background and of very similar age pattern of 20 years to 60 years.For further reference, we will describe Group I for closed reduction and CHS/DHS only, and Group II for closed reduction CHS and quadratus femoris muscle pedicle graft.

RESULTS

Satisfactory bony union occurred in 42 out of 45 follow-up patients in Group 1 (93.3%) and 43 out of 45 patients in Group 2. (95.5%) In 2- to 10-year follow-up period, eight patients (18.6%) developed osteonecrosis in Group I, and in Group 2, in the same period, there were no cases of osteonecrosis.

CONCLUSION

Addition of quadratus femoris muscle pedicle bone graft is a very effective procedure for prevention of osteonecrosis when we attempt osteosynthesis by closed reduction and internal fixation for displaced femoral neck fractures.

Relationship between the neutrophil-to-lymphocyte ratio or platelet-to-lymphocyte ratio and deep venous thrombosis (DVT) following femoral neck fractures in the elderly

Purpose

This study aimed to investigate whether the neutrophil-to-lymphocyte ratio (NLR) or platelet-to-lymphocyte ratio (PLR) was associated with deep venous thrombosis (DVT) following femoral neck fractures in the elderly.

Method

This was a retrospective cohort study and used data extracted from the hospitalization electronic medical record and the laboratory biomarker reports. Patients were included if they were aged above 60 years with a definite diagnosis of femoral neck fracture caused by low-energy trauma. Duplex ultrasound scanning was routinely performed to detect the potential DVT. Two independent multivariate logistic regression models were constructed to identify the association of NLR or PLR with the risk of DVT.

Results

A total of 708 patients with femoral neck fractures were included, and 112 were found to have DVT, indicating an incidence rate of 15.8%. There were significant differences across five subgroups for NLR or PLR, in terms of age (p = 0.020, 0.006), white blood cell (p < 0.001, =0.006), hemoglobin (p < 0.001, <0.001), and albumin (p < 0.001, <0.001). BMI was tested to be significantly different across subgroups for NLR (p = 0.030) and prevalence of cerebrovascular disease for PLR (p = 0.014). The multivariate analyses demonstrated that not NLR but PLR in Q3 (range, 179–238) was associated with an increased risk of DVT, and the risk for the latter was 1.86 (95%CI, 1.07–3.36).

Conclusion

We concluded that a PLR value of 179–238 was associated with a 1.86-fold increased risk of DVT after femoral neck fracture. This study paves the way toward further exploration of inflammatory/immune biomarkers with the risk of DVT in the elderly with trauma.

The Risk of Avascular Necrosis Following the Stabilization of Femoral Neck Fractures: A Systematic Review and Meta-Analysis

Background: Avascular necrosis (AVN) of the femoral head often requires surgical treatment and is often associated with femoral neck fractures. We conducted a systematic review and meta-analysis of recent research on the risk of AVN following the stabilization of fractured femoral neck with implants in PubMed. We assessed the effect of age on AVN incidence among patients aged > 50 and younger, depending on fracture type, Garden stage, Pouwels degree, Delbet stage, and age category. We followed PRISMA guidelines. Relevant studies were defined as research articles describing real-world studies reporting on the risk of AVN following primary surgical fracture stabilization with implants, published between 1 January 2011 and 22 April 2021. Fifty-two papers met the inclusion criteria, with a total of N = 5930 with surgically managed fractures. The pooled mean AVN incidence was significantly higher among patients with displaced fractures (20.7%; 95% CI: 12.8−28.5%) vs. those with undisplaced fractures (4.7%; 95% CI: 3.4−6.0%). No significant correlation was observed between AVN incidence weighted by sample size and time interval from injury to surgery (p = 0.843, R2 = 0.01). In conclusion, the risk of AVN following femoral neck fractures was generally high, especially in patients with displaced fractures. The time from injury to surgery did not correlate with AVN incidence.

Hidden osteonecrosis of the femoral head after healed femoral neck fractures: magnetic resonance imaging study of 58 consecutive patients

INTRODUCTION

Several studies investigated the posttraumatic osteonecrosis of the femoral head (ONFH) after femoral neck fracture (FNF). However, no study has investigated the hidden ONFH after FNF, which is missed by simple radiographs, using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This retrospective study involved 58 consecutive patients who underwent implant removal surgery after internal fixation due to FNF. MRI was used to investigate the incidence of hidden ONFHs, which were not initially revealed on plain radiographs. The comparisons between hidden ONFH and other groups were performed for patent demographics and clinical variables including ONFH location, lesion size, the progression rate of ONFH collapse, and end-stage arthroplasty conversion rate.

RESULTS

Of the 58 patients, 38 exhibited no evidence of ONFH on plain radiograph screening. However, 13 of the 38 patients were confirmed of hidden ONFH via MRI. The collapse progressed in four of the 13 patients, and one of them underwent total hip arthroplasty surgery. No significant differences were found between the hidden and definite ONFH groups in demographics and clinical variables. However, a significant difference exists between the hidden ONFH and the normally healed FNF groups in terms of the Garden type (P < 0.001).

CONCLUSIONS

A large number of cases with hidden ONFH were confirmed using MRI following healed FNF, and most of them were initially displaced FNF. Thus, the treatment method between internal fixation and hip arthroplasty should be carefully selected, particularly with displaced FNF.

Safety of surgical hip dislocation in femoral head fracture and dislocation (FHFD) and avascular necrosis risk factor analysis of FHFD: midterm results confirmed by SPECT/CT and MRI

Background

The study aim was to report the treatment outcomes of trochanteric flip osteotomy (TFO) with surgical hip dislocation (SHD) for femoral head fracture and dislocation (FHFD) and to investigate the risk factors for avascular necrosis (AVN) of the femoral head.

Methods

The data of 34 patients (29 men, 5 women; mean age 37.9 years) diagnosed with FHFD and treated with TFO with SHD between May 2009 and February 2018 with an average follow-up period of 5.1 years (range 2.8–10.5 years) were analyzed. Clinical outcomes were evaluated using the Merle d'Aubigné–Postel score and Thompson–Epstein Scale. Radiologic outcomes were classified according to the Matta classification. AVN was confirmed using magnetic resonance imaging or single-photon emission computed tomography/computed tomography. The occurrence of complications was examined, and factors influencing complications, AVN.

Results

Regarding the Pipkin’s classification, there were 7 patients with type II, 2 patients with type III, and 25 patients with type IV fractures. Posterior wall fractures accompanied all associated acetabular fractures in the patients with Pipkin type IV fractures. Radiologically, the union of acetabular and femoral head fractures was observed within 6.1 months on average (range 4–10 months) in 32 patients, except two patients who developed femoral head AVN. Clinically, the average Merle d'Aubigné–Postel score was 14.4 points (range 8–17 points), and 22 patients had good or excellent results on the Thompson–Epstein Scale. Two patients developed femoral head AVN with both having displaced femoral neck fractures associated with FHFD. AVN was significantly correlated with femoral neck fractures (P = 0.000).

Conclusion

TFO with SHD is a safe and useful approach for the treatment of FHFD. Particular attention should be paid when treating femoral head fractures associated with displaced femoral neck fractures because of the high risk of AVN development.

KSNM 60 in General Nuclear Medicine: the Old Dream Comes True

Since the establishment of the Korean Society of Nuclear Medicine (KSNM) in 1961 by Professor Munho Lee, the KSNM has been progressing in various medical fields. Many papers have been published in the Korean Journal of Nuclear Medicine (KJNM), the official journal of KSNM, since 1967 and other domestic/international journals. Here, we tried to highlight the academic activities of KSNM members from the perspective of general nuclear medicine. After the introduction of the ⁹⁹Mo/^99mTc generator, general nuclear medicine has widened the field of clinical application with the advancement of imaging technology and emerging new radiopharmaceuticals; however, there have been many ups and downs. Treatment, as well as diagnosis, was a major concern in Korean nuclear medicine. With the recent advent of single-photon emission computed tomography/computed tomography, we hope that our old dream (diagnosis and treatment under the same principle of nuclear medicine) comes true.

Usefulness of Bone SPECT/CT for Predicting Avascular Necrosis of the Femoral Head in Children with Slipped Capital Femoral Epiphysis or Femoral Neck Fracture

OBJECTIVE

This study aimed to investigate the usefulness of bone single-positron emission tomography/computed tomography (SPECT/CT) of the hip in predicting the later occurrence of avascular necrosis (AVN) after slipped capital femoral epiphysis (SCFE) or femoral neck fracture in pediatric patients. The quantitative parameters of SPECT/CT useful in predicting AVN were identified.

MATERIALS AND METHODS

Twenty-one (male:female, 10:11) consecutive patients aged < 18 years (mean age ± standard deviation [SD], 11.0 ± 2.7 years) who underwent surgery for SCFE or femoral neck fracture and postoperative bone SPECT/CT were included. The maximum standardized uptake value (SUV), mean SUV, and minimum SUV of the femoral head were measured. The ratios of the maximum SUV, mean SUV, and minimum SUV of the affected femoral head to the contralateral side were determined. Patients were followed up for > 1 year after the surgery. The SPECT/CT parameters were compared between patients who developed AVN and those who did not. The accuracy of SPECT/CT parameters for predicting AVN was assessed.

RESULTS

Six patients developed AVN. There was a significant difference in the ratio of the mean SUV among patients who developed AVN (mean ± SD, 0.8 ± 0.3) and those who did not (1.1 ± 0.2, p = 0.018). However, there were no significant differences in the ratios of the maximum and minimum SUV between the groups (all p = 0.205). For the maximum, mean, and minimum SUVs, no significant differences were observed between the groups (p = 0.519, 0.733, and 0.470, respectively). The cutoff mean SUV ratio of 0.87 yielded a 66.7% sensitivity and 93.2% specificity for predicting AVN.

CONCLUSION

Quantitative bone SPECT/CT is useful for evaluating femoral head viability in pediatric patients with SCFE or femoral neck fractures. Clinicians should consider the high possibility of later AVN development in patients with a decreased mean SUV ratio.

Value of SPECT/CT in the diagnosis of avascular necrosis of the head of femur: A meta-analysis

INTRODUCTION

To evaluate the diagnostic value of single photon emission computed tomography/computed tomography (SPECT/CT) in patients with avascular necrosis (AVN) of the femoral head.

METHODS

A search of the databases PubMed, ScienceDirect, and Google Scholar was undertaken using targeted index word. Studies satisfying inclusions and exclusions criteria were identified and additional related literature sources were considered. Analysis included pooled sensitivity and specificity, odds ratio (OR), and receiver operating characteristic (ROC) analysis.

RESULTS

Seven studies were identified that specifically related to the diagnostic accuracy of SPECT/CT in the detection or characterisation of AVN of the femoral head. These were included in the meta-analysis. The pooled sensitivity and specificity were 94% (95% confidence interval of 87-97%) and 75% (95% confidence interval of 68-81%) respectively, the OR was 44.5 (with a 95% confidence interval of 18.2-108.6), and the area under the SROC was 93.73% (with a 95% confidence interval of 89.2%-98.3%).

CONCLUSION

This meta-analysis provides strong evidence of the high diagnostic efficacy of SPECT/CT in the evaluation of AVN of the femoral head.

IMPLICATIONS FOR PRACTICE

In the absence of or contraindication to MRI, SPECT/CT is able to provide a suitable alternative for diagnosis of AVN of the head of femur.

Tissue Engineering Strategies for Treating Avascular Necrosis of the Femoral Head

Avascular necrosis (AVN) of the femoral head commonly leads to symptomatic osteoarthritis of the hip. In older patients, hip replacement is a viable option that restores the hip biomechanics and improves pain but in pediatric, adolescent, and young adult patients hip replacements impose significant activity limitations and the need for multiple revision surgeries with increasing risk of complication. Early detection of AVN requires a high level of suspicion as diagnostic techniques such as X-rays are not sensitive in the early stages of the disease. There are multiple etiologies that can lead to this disease. In the pediatric and adolescent population, trauma is a commonly recognized cause of AVN. The understanding of the pathophysiology of the disease is limited, adding to the challenge of devising a clinically effective treatment strategy. Surgical techniques to prevent progression of the disease and avoid total hip replacement include core decompression, vascular grafts, and use of bone-marrow derived stem cells with or without adjuncts, such as bisphosphonates and bone morphogenetic protein (BMP), all of which are partially effective only in the very early stages of the disease. Further, these strategies often only improve pain and range of motion in the short-term in some patients and do not predictably prevent progression of the disease. Tissue engineering strategies with the combined use of biomaterials, stem cells and growth factors offer a potential strategy to avoid metallic implants and surgery. Structural, bioactive biomaterial platforms could help in stabilizing the femoral head while inducing osteogenic differentiation to regenerate bone and provide angiogenic cues to concomitantly recover vasculature in the femoral head. Moreover, injectable systems that can be delivered using a minimal invasive procedure and provide mechanical support the collapsing femoral head could potentially alleviate the need for surgical interventions in the future. The present review describes the limitations of existing surgical methods and the recent advances in tissue engineering that are leading in the direction of a clinically effective, translational solution for AVN in future.

Development and validation of a predictive nomogram for postoperative osteonecrosis of the femoral head with cannulated screws fixation

Background

Osteonecrosis of the femoral head (ONFH) remains a major complication of femoral neck fractures. Early interventions require preliminary prediction and detection. In this study, we aimed to evaluate the perioperative variables of postoperative ONFH in femoral neck fracture patients with closed reduction and cannulated screw fixation. We also established and validated an individualized nomogram for the prediction of postoperative ONFH.

Methods

We included 470 patients with ONFH from two hospitals [First Affiliated Hospital of University of Science and Technology of China (n=360) and Southern Branch of the First Affiliated Hospital of the University of Science and Technology of China (n=110)]. We evaluated the prognostic value of multiple perioperative variables using a Cox regression model in the training cohort. We developed a nomogram for the prediction of ONFH using a logistic regression model. We assessed the performance of this nomogram in a validation cohort and evaluated its clinical value.

Results

Of the 470 patients who met the inclusion criteria, 141 (30.0%) developed postoperative ONFH. We found alcohol use [odds ratio (OR), 1.743, 95% confidence interval (CI), 1.042-2.901, P=0.033], cerebrovascular disease (OR, 5.357, 95% CI, 2.318-13.13, P<0.001), interval to surgery (OR, 5.273, 95% CI, 2.724-10.43, P<0.001), Garden classification (OR, 23.17, 95% CI, 6.812-145.3, P<0.001), Garden index (OR, 5.935, 95% CI, 2.670-14.184, P<0.001), interval to partial weight-bearing (OR, 0.053, 95% CI, 0.006-0.296, P=0.002), and six-month Harris hip score (OR, 0.856; 95% CI, 0.792-0.919, P<0.001) were independent predictors of postoperative development of ONFH. Based on these variables, we developed a nomogram that showed good discrimination in both the training [area under the curve (AUC) =0.865] and the validation cohort (AUC =0.877). The favorable performance of this nomogram was also confirmed in the validation cohort.

Conclusions

We developed and validated an easy-to-use nomogram for predicting postoperative ONFH. This nomogram can aid decision-making of intraoperative interventions and postoperative rehabilitation plans for patients, surgeons, and osteo-rehabilitative physicians.

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.

Computed Tomography (CT) Protocols Associated with Cardiac and Bone Single-Photon Emission Computed Tomography/CT (SPECT/CT) in Korea

PURPOSE

Single-photon emission computed tomography/computed tomography (SPECT/CT) is an advanced hybrid nuclear medicine technology that generates both functional and anatomical images in a single study. As utilization of SPECT/CT in Korea has been increasing, the purpose of this study was to survey its application of cardiac and skeletal SPECT/CT imaging for protocol optimization.

METHODS

We surveyed CT protocols established for cardiac and skeletal SPECT/CT. We searched the guidelines for the CT protocols for SPECT/CT and reviewed the literature recently published.

RESULTS

Among 36 hybrid SPECT scanners equipped with four or more multi-channel detector CTs (MDCTs), 18 scanners were used to perform cardiac studies at both very low current CT (30-80 mA; 11.1%) and ultra-low current CT (13-30 mA; 88.9%). Among the 33 canners, very low current (≤ 80 mA) CT or low current CT (80-130 mA) was used in 23.5%, and 41.8% for spine disorders, and in 36.4% or 30.3% for foot/ankle disorders, respectively. In the CT reconstructions, slice thickness of 5 mm for cardiac studies was most commonly used (94.4%); thinner slices (0.6-1.0 mm) for spine and foot/ankle studies were used in 24.2% and 45.5%, respectively. We also reviewed the international guidelines.

CONCLUSIONS

The results and current recommendations will be helpful for optimizing CT protocols for SPECT/CT. Optimization of SPECT/CT protocols will be required for generating the proper strategy for the specific lesions and clinical purpose.

Minimum Standardized Uptake Value from Quantitative Bone Single-Photon Emission Computed Tomography/Computed Tomography for Evaluation of Femoral Head Viability in Patients with Femoral Neck Fracture

Purpose

Bone single-photon emission computed tomography/computed tomography (SPECT/CT) has been widely used for evaluation of femoral head viability in patients with femoral neck fracture. The current study aimed to investigate utility of standardized uptake value (SUV) from quantitative bone SPECT/CT for assessment of femoral head viability.

Methods

From March 2015 to November 2018, quantitative bone SPECT/CT was performed in 9 patients with non-viable femoral head post femoral neck fracture and in 31 controls. Maximum (SUVmax), mean (SUVmean), and minimum standardized uptake values (SUVmin) were measured over femoral head and neck. Mann-Whitney U test with Bonferroni correction was used to compare SUVs of ipsilateral and contralateral femurs from femoral neck fracture patients with those of control femurs.

Results

As for femoral head viability, SUVmax and SUVmean were not significantly decreased in non-viable femoral heads compared to those in controls. Only the SUVmin was significantly reduced in non-viable femoral heads (mean ± standard deviation, 0.57 ± 0.38) than in controls (0.95 ± 0.26, p = 0.006) and contralateral femoral heads (1.36 ± 0.59, p = 0.008). The cutoff SUVmin of 0.61 (g/mL) yielded a sensitivity of 77.8% and specificity of 87.1% for detection of non-viable femoral heads (p = 0.006). Contralateral femoral necks of the femoral neck fracture patients showed significantly higher SUVmean and SUVmin (3.17 ± 1.20 and 1.64 ± 0.63) than those of controls (2.32 ± 0.53 and 1.04 ± 0.27; p = 0.021 and p = 0.002, respectively), which seemed to reflect weight bearing effect or metabolic derangement.

Conclusions

The non-viable femoral heads from the femoral neck fracture showed significantly reduced SUVmin. Quantitative bone SPECT/CT holds promise for objective evaluation of femoral head viability.

Incidence and severity of femoral head avascularity after femoral neck or intertrochanteric fractures on preoperative bone single photon emission computed tomography/computed tomography: preliminary study

OBJECTIVE

The aim of the present study was to evaluate the incidence and degree of femoral head avascularity depending on the types of femoral neck or intertrochanteric fractures using preoperative bone single photon emission computed tomography (SPECT)/computed tomography (CT).

PATIENTS AND METHODS

A total of 131 patients with femoral neck or intertrochanteric fractures who underwent preoperative bone SPECT/CT were enrolled. Femoral head avascularity was evaluated using bone SPECT/CT images. Visual scores ranged from 1 to 5 based on visually assessed diagnostic confidence: 1=definitely avascular femoral head, 2=likely avascular, 3=equivocal, 4=likely not avascular, and 5=definitely not avascular. In quantitative analysis, contralateral, ipsilateral, and size ratios were measured.

RESULTS

Among 131 patients, 39 of 54 (72.22%) with femoral neck fractures and 23 of 77 (29.87%) with intertrochanteric fractures showed avascular femoral heads. The incidence of femoral head avascularity was significantly higher in patients with femoral neck fracture than those with intertrochanteric fracture. While the incidence and severity of femoral head avascularity increased with higher Garden stage in femoral neck fracture, neither was related to AO/Orthopaedic Trauma Association classification of intertrochanteric fracture. In addition, the number of bony fragments around intertrochanteric fractures was not a significant predictor of femoral head avascularity.

CONCLUSION

Although avascular femoral head on bone SPECT/CT does not directly indicate avascular necrosis, assessing the incidence and severity of femoral head avascularity using qualitative and quantitative parameters could give clinically useful information related to the classification. Additional studies with larger sample sizes would be a next step to expand the clinical role of bone SPECT/CT.

SPECT/CT in Postoperative Painful Hip Arthroplasty

Consecutive milestones in hip arthroplasty design and surgical technique have contributed to the successful and cost-effective intervention this procedure has become today in maintaining mobility and quality of life in patients with osteoarthritis, fracture, or other hip conditions. With the increasing prevalence of hip joint replacements, the need for improved diagnostic imaging tools to guide revision surgery has risen in parallel. Over the last few years, promising data have emerged on the potential role of bone SPECT/CT imaging in the assessment of patients with recurrent pain after arthroplasty. This review summarizes the trends in hip arthroplasty surgery (partial vs total arthroplasty; cemented vs cementless arthroplasty; resurfacing arthroplasty) and prosthesis design (bearing materials; stem designs) over the last decade. In particular, the impact on the biomechanics and interpretation of bone SPECT/CT findings is discussed, with emphasis on integrative reporting in the following frequently encountered conditions: lysis/aseptic loosening, septic loosening, heterotopic ossification, periprosthetic fracture, tendinopathies, and adverse local tissue reactions. Based on the available literature data, bone SPECT/CT is increasingly being used as second-line imaging modality when conventional investigations are nondiagnostic. Further outcome research is warranted to examine whether this technique could be used earlier in patient management.