Evaluation of the hemodynamics of the femoral head compared with the ilium, femoral neck and femoral intertrochanteric region in healthy adults: Measurement with positron emission tomography (PET)

Predictors of Osteonecrosis in Systemic Lupus Erythematosus: A Prospective Cohort Study

OBJECTIVE

We aimed at determining the predictors of osteonecrosis (ON) in a longitudinal lupus cohort.

METHODS

Data were reviewed from the initiation of the cohort in 1987 until October 2019. In total, 2,428 patients were included in the analysis based on 224,295 person-months of follow-up. We used pooled logistic regression to assess the relationship between risk factors and rates of ON events. After identifying a set of variables related to ON incidence, we fit a final multivariable model to identify the most important risk factors for incident ON.

RESULTS

In 18,691 person-years of follow-up after cohort entry, 122 incident ON events were observed (rate = 6.5/1,000 person-years). In the multivariable analysis, African American patients were at twice the risk for ON compared to White patients. Male patients and smokers had an increased risk for ON of ~80% and 50% compared to female patients and nonsmokers, respectively. For every 10-year increase in the age at diagnosis, there was a 20% reduced risk for ON. Patients diagnosed after the 1990s had a 50% reduced risk of ON compared to those diagnosed before the 1990s. A highest daily dosage of prednisone of 40 mg or higher, even when administered for a month or less, significantly increased the risk of ON. Use of pulse methylprednisolone or intramuscular triamcinolone was not associated with an increased risk of ON.

CONCLUSION

African American patients with systemic lupus erythematosus are at double the risk of experiencing ON compared to White patients. Oral prednisone at 20-39 mg for more than 1 month, or 40 mg daily for even 1 month, at any point in the disease course, remained the most important glucocorticoid predictor of ON.

Study of Osteocyte Behavior by High-Resolution Intravital Imaging Following Photo-Induced Ischemia

Ischemic injuries and local hypoxia can result in osteocytes dysfunction and play a key role in the pathogenesis of avascular osteonecrosis. Conventional imaging techniques including magnetic resonance imaging (MRI) and computed tomography (CT) can reveal structural and functional changes within bony anatomy; however, characterization of osteocyte behavioral dynamics in the setting of osteonecrosis at the single cell resolution is limited. Here, we demonstrate an optical approach to study real-time osteocyte functions in vivo. Using nicotinamide adenine dinucleotide (NADH) as a biomarker for metabolic dynamics in osteocytes, we showed that NADH level within osteocytes transiently increase significantly after local ischemia through non-invasive photo-induced thrombosis of afferent arterioles followed by a steady decline. Our study presents a non-invasive optical approach to study osteocyte behavior through the modulation of local environmental conditions. Thus it provides a powerful toolkit to study cellular processes involved in bone pathologies in vivo.

Osteosynthesis of ununited femoral neck fracture by internal fixation combined with iliac crest bone chips and muscle pedicle bone grafting

BACKGROUND

Ununited femoral neck fracture is seen commonly in developing countries due to delayed presentation or failure of primary internal fixation. Such fractures, commonly present with partial or total absorption of femoral neck, osteonecrosis of femoral head in 8-30% cases with upward migration of trochanter posing problem for osteosynthesis, especially in younger individuals. Several techniques for treatment of such conditions are described like osteotomies or nonvascularied cortical or cancellous bone grafting provided varying degrees of success in terms of fracture union but unsatisfactory long term results occurred due to varying incidence of avascular necrosis (AVN) of femoral head. Moreover, in presence of AVN of femoral head neither free fibular graft nor cancellous bone graft is satisfactory. The vascularied bone grafting by deep circumflex iliac artery based on iliac crest bone grafting, free vascularied fibular grafting and muscle pedicle periosteal grafting showed high incidence of success rate. Osteosynthesis is the preferred treatment of choice in ununited femoral neck fracture in younger individuals.

MATERIALS AND METHODS

Of the 293 patients operated during the period from June 1977 to June 2009, 42 were lost to followup. Seven patients with gluteus medius muscle pedicle bone grafting (MPBG) were excluded. Thus, out of 244 patients, 208 (85.3%) untreated nonunion and 36 (14.7%) following failure of primary internal fixation were available for studies. Time interval between the date of injury and operation in untreated nonunion cases was mean 6.5 months and in failed internal fixation cases was mean 11.2 months. Ages of the patients varied from 16 to 55 years. Seventy patients had partial and 174 had subtotal absorption of the femoral neck. Evidence of avascular necrosis (AVN) femoral head was found histologically in 135 (54.3%) and radiologically in 48 (19.7%) patients. The patients were operated by open reduction of fracture, cannulated hip screw fixation, iliac crest bone chips and quadratus femoris MPBG.

RESULTS

The mean followup is 12.5 years (range 3-35). The union of fractures occurred in 202 (82.8%), delayed union in 18 (7.3%), and established nonunion in 24 (9.8%) patients. Full weight bearing was permitted at 16-22 weeks after union of fractures. Mean Harris hip score at the longest followup was 85.5. Among the complications, superficial wound infection occurred in 20 (8.2%), deep infection in seven (2.9%), and coxa vara in 39 (16%) patients. Preoperative radiodensity of femoral head disappeared mostly after the union of fracture whereas fresh radiodensity of femoral head appeared in 20 (8%) patients; nine (45%) of them developed segmental collapse.

CONCLUSION

Ununited femoral neck fractureis characterized by absorption of femoral neck, posterior cortical defect, smoothening and overriding of fracture surfaces with intervening fibrous tissues associated with or without AVN of femoral head. The above method of osteosynthesis rectified the above pathology and provided satisfactory results with union of fractures in 90.1% patients at long term followup.

PET/CT study of temporal variations in blood flow to the femoral head following low-energy fracture of the femoral neck

Earlier studies on femoral neck fractures have assessed the blood flow in either the pre- or postoperative period and information is lacking regarding changes in vascular flow to the femoral head after injury. Sixty-two adults with low-energy intracapsular femoral neck fractures were studied prospectively. Mean patient age was 57.2 years (range, 45-82 years). All patients underwent positron emission tomography/computed tomography (PET/CT) prior to surgical intervention and 6 weeks after internal fixation. Internal fixation was done using cannulated cancellous titanium screws and serial follow-up radiographs were obtained (at monthly intervals for the first 3 months followed by 3 monthly intervals between radiographs up to 2 years). On the preoperative PET/CT, 13 patients showed intact vascularity, 31 showed total loss of vascularity, and 18 showed partial loss of vascularity of the femoral head. The 6-week postoperative PET/CT scan showed recovery of blood supply in 23 of the 31 patients with total loss of vascularity and 15 of the 18 patients with partial loss of vascularity of the femoral head. Eleven of 62 patients had total or partial avascularity at the 6-week postoperative PET/CT scan and all 11 patients showed evidence of avascular necrosis on plain radiographs at the end of 2 years. The association between the vascular status of the femoral head at 6 weeks and avascular necrosis at the end of 2 years was statistically significant (P<.001). This study shows that the femoral head undergoes temporal variations in blood flow following femoral neck fracture. Decreased or absent vascularity is seen in approximately 75% of the fractures and 80% of the femoral heads with initial vascular compromise seem to regain blood flow within 6 weeks. Thus, prognostication about vascularity based on single-point preoperative imaging is difficult. The 6-week postoperative PET/CT scan seems to be reliable in predicting the future status of the femoral head. However, decision making regarding hemiarthroplasty or internal fixation at the time of injury may have to depend on factors other than the preoperative vascular status of the femoral head.

Fracture of the acetabulum: a retrospective review of ninety-one patients treated at a single institution

Acetabular fracture result in fairly good outcome after the anatomic reduction in the displaced fracture fragments and damaged joint structure, but some patients will inevitably suffer from hip joint problems during their courses after the insult. We retrospectively reviewed 91 patients with acetabular fractures to investigate the causes of clinical failure and relationship among the fracture types, selected treatment options and their courses. Ninety-one patients (73 men and 18 women) with an average age of 49 years (range 18-80) at the time of injury were followed up for an average of 8.6 years (range 2-18). Judet-Letournel classification of fracture type and Matta's rating regimen of functional and radiographic patient' assessment were conducted. Conservative treatment was provided in 20 patients, in which 19 attained excellent/good, and one fair clinical results. All achieved excellent/good radiographic outcome. Surgically treated patients (n = 71) with critical dislodgement of the fracture fragment showed that 64 (90%) attained excellent/good and 7 (10%) fair/poor clinical outcomes. Sixty-three (89%) attained excellent/good and 8 (11%) fair/poor postoperative radiographic outcome. Five patients with poor radiographic outcome after surgery subsequently required total hip arthroplasty, due to the development of hip joint osteoarthritis in 3 and femoral head avascular necrosis in 2. We conclude that displacement of the joint surface should be reduced to less than 3 mm in accordance with the selection of the most appropriate surgical approach for open reduction/fixation in each fracture type; however, comminuted fracture and avascular necrosis of the femoral head may be the cause of poor clinical results.

Compromised perfusion in femoral head in normal rats: distinctive perfusion MRI evidence of contrast washout delay

OBJECTIVES

The femoral head is prone to osteonecrosis. This study investigated dynamic contrast-enhanced (DCE) MRI contrast washout features of the femoral head and compared the data with data from other bony compartments in normal rats.

METHODS

7-month-old Wistar rats were used. DCE MRI of the right hip (n=18), right knee (n=12) and lumbar spine (n=10) was performed after an intravenous bolus injection of Gd-DOTA (0.3 mmol kg(-1)). Temporal resolution was 0.6 s for hip and spine, and 0.3 s for knee. The total scan duration was 8 min for hip and spine, and 4.5 min for knee. The regions of interest for enhancement measurement included femoral head, proximal femoral diaphysis, distal femoral diaphysis and epiphysis, proximal tibial epiphysis and diaphysis, and lumbar vertebrae L1-5.

RESULTS

Femoral head showed no enhancement signal decay during the DCE MRI period, while all other bony compartments showed a contrast washin phase followed by a contrast washout phase. In the knee joint, the contrast washout of the proximal tibia diaphysis was slower that of other bony compartments of the knee.

CONCLUSION

Based on the evidence of delayed contrast washout, this study showed that blood perfusion in the femoral head could be compromised in normal rats.

Recovery of the blood flow around the femoral head during early corticosteroid therapy: dynamic magnetic resonance imaging in systemic lupus erythematosus patients

Disturbance of blood supply to the femoral head is a risk factor for corticosteroid-associated osteonecrosis. The aim was to measure blood supply of the proximal femur during corticosteroid therapy in systemic lupus erythematosus (SLE) patients. We repeatedly performed 78 dynamic MRIs of 19 hip joints in 19 SLE patients after initiation of corticosteroid administration for one year. Blood supply of the femoral head (epiphysis, growth plate, and metaphysis), the femoral neck, and the medial circumflex femoral artery were measured in terms of peak percent enhancement. At the first month, blood supply of the growth plate was significantly higher in the pediatric group (<15 years old) than in the adolescent and adult group (>15 years old). At the fourth month, blood supply in every part of the femoral head (epiphysis, growth plate, and metaphysis) was significantly higher in the pediatric group than in the adolescent and adult group. Multiple regression analysis revealed that blood supply to the femoral head depended on the number of days after initiation of corticosteroid administration and the age at the time of dynamic MRI. Blood supply to the femoral head is abundant in pediatric patients and is a function of the number of days after initiation of corticosteroid administration.

Osteonecrosis in children after therapy for malignancy

OBJECTIVE

Osteonecrosis in the growing population of childhood cancer survivors results from disease and treatment. Imagers must be knowledgeable about patient groups at risk for its development, patterns of involvement and potential implications. This review will focus on implications of this potentially life-altering toxicity.

CONCLUSION

Childhood cancer survivors are at increased risk for developing osteonecrosis. Because osteonecrosis is often asymptomatic until late in the process, imaging is critical for its detection and characterization when interventions may be most effective to ameliorate its progression.

Early prediction of femoral head avascular necrosis following neck fracture

Femoral neck fracture puts at risk functional prognosis in young patients and can be life-threatening in the elderly. The present study reviews methods of femoral head vascularity assessment following neck fracture, to address the following issues: what is the risk of osteonecrosis? And what, in the light of this risk, is the best-adapted treatment to avoid iterative surgery? Femoral head vascularity depends on retinacular vessels and especially the lateral epiphyseal artery, which contributes from 70 to 80% of the femoral head vascular supply. Fracture causes vascular lesions, which are in turn the prime cause of necrosis. Other factors combine with this: hematoma tamponade effect, reduced joint space and increased pressure due to lower extremity positioning in extension/internal rotation/abduction during surgery. Head deformity is not due to direct cell death but to the repair process originating from the surrounding living bone. In post-traumatic necrosis, proliferation rapidly invades the head, with significant osteogenesis. Pathologic fractures occur at the boundary between the new and dead bone. Many techniques have been reported to help assess residual hemodynamics and risk of necrosis. Some are invasive: superselective angiography, intra-osseous oxygen pressure measurement, or Doppler-laser hemodynamic measurement; others involve imaging: scintigraphy, conventionnal or dynamic MRI. The future seems to lie with dynamic MRI, which allows a new classification of femoral neck fractures, based on a non-invasive assessment of femoral head vascularity.

Reduced bone perfusion in proximal femur of subjects with decreased bone mineral density preferentially affects the femoral neck

Using dynamic contrast enhanced MR imaging, this study investigated perfusion of the proximal femur in subjects with normal BMD, low bone mass and osteoporosis. Study cohort comprised healthy elderly Hong Kong Chinese volunteers consisting of 107 males (74.4+/-4.2 years, mean+/-SD) and 135 females (73.9+/-4.3 years). Right proximal femur BMD measurement by DXA and MR perfusion imaging (maximum enhancement, E(max) and enhancement slope, E(slope)) of the femoral head, neck, and proximal shaft were carried out within a one month interval. Normal BMD, low bone mass and osteoporotic subjects accounted for 46.7%, 44.9%, and 8.4% of males; and 32.6%, 43.7%, and 23.7% of females. Perfusion indices showed that femoral head perfusion was less perfused compared to the femoral shaft (E(max) and E(slope) indices of head region=28% of shaft region). Compared with normal BMD subjects, E(max) of femoral head, neck, and proximal femur shaft were reduced by 15+/-5% (mean+/-standard error); 40+/-4%; 15+/-5% respectively for low bone mass subjects, and 36+/-4%; 50+/-6%; 47+/-6% respectively for osteoporotic subjects. E(slope) of femoral head, neck, and proximal femur shaft were reduced by 17+/-7%; 41+/-5%; 4+/-7% for low bone mass subjects and 50+/-5%, 62+/-5%, 34+/-8% for osteoporotic subjects. In low bone mass and osteoporotic subjects there was a tendency for perfusion in the femoral neck to reduce to a greater degree relative to that in the femoral head and shaft.

The management of ununited fractures of the femoral neck using internal fixation and muscle pedicle periosteal grafting

We describe a series of 20 patients with ununited fractures of the femoral neck following neglected trauma or failed primary internal fixation who were seen at a mean of 7.5 months (2 to 18) following injury. Open reduction and internal fixation of the fracture was performed in all patients, together with a myoperiosteal flap on the quadratus femoris muscle pedicle. Union occurred at a mean of 4.9 months (2 to 10) in all patients. The mean follow-up was for 70 months (14 to 144). There was no further progression in six of seven patients with pre-operative radiological evidence of osteonecrosis of the femoral head. One patient had delayed collapse and flattening of the femoral head ten years after union of the fracture, but remained asymptomatic. This study demonstrates the orthopaedic application of myoperiosteal grafting for inducing osteogenesis in a difficult clinical situation.

Prediction of avascular necrosis of the femoral head by measuring intramedullary oxygen tension after femoral neck fracture

OBJECTIVE

To measure the intramedullary oxygen tension of the proximal femur after a femoral neck fracture and to evaluate the usefulness of that monitoring for prediction of subsequent avascular necrosis.

DESIGN

Prospective case series with comparison group.

SETTING

University hospital.

INTERVENTION

Measurement of intramedullary oxygen tension of the femoral head and neck during internal fixation using the Hansson hook-pin system.

MAIN OUTCOME MEASUREMENTS

Intramedullary oxygen tension was measured directly during surgery in 17 patients with 18 femoral neck fractures treated by internal fixation between October 2000 and February 2002. The intramedullary oxygen tension was measured by using polarographic oxygen electrodes and an oxygen monitor at four points: (A) 1 cm distal from the joint surface; (B) 1 cm proximal from the fracture site; (C) 1 cm distal from the fracture site; and (D) 1 cm proximal from the lateral wall. The presence or absence of avascular necrosis was evaluated by magnetic resonance imaging (MRI) at 2, 6, and 12 months after surgery.

RESULTS

MRI evaluation showed 11 fractures healed without complications, and 7 fractures developed avascular necrosis. We found significant differences in the distribution of intramedullary oxygen tension of the femoral head between points A (1 cm from the joint surface) and B (1 cm proximal from the fracture site) in those patients who developed avascular necrosis (P = 0.039); that is the oxygen tension was lower at point A than at point B. In contrast, in those patients who did not develop avascular necrosis there was no significant differences between point A and B were found (P = 0.059). The sensitivity and specificity for prediction of avascular necrosis were 1.0 and 0.82 (Fischer exact probability test, P = 0.002), respectively, when the cut-off level of oxygen tension differences between points A and B was set at 3.1 mm Hg.

CONCLUSION

We believe that this method of measuring intramedullary oxygen tension is simpler and less invasive than other currently used methods and has the possibility for intraoperatively identifying a risk group that can develop a late segmental collapse of the femoral head secondary to avascular necrosis.