Quantitative analysis of distal femoral epiphysis blood supply in healthy infants with superb microvascular imaging: a pilot study

Background/aim: This study aimed to determine the blood supply of the distal femoral epiphysis (DFE) using superb microvascular imaging in newborns and infants, and to investigate the correlation with ossification center (OC) length, sex, and age. Materials and methods: A total of 140 cases were evaluated in this study. The cases were divided into 2 groups of less than 90 days and over 90 days. Cartilage blood supply was measured with vascularity index (%) (VI). Results: The mean OC length and median VI values were measured as 10.20 ± 3.72 mm and 0.80% (0.58­1.50) for boys and 10.03 ± 3.36 mm and 0.70% (0.30­1.40) for girls, respectively. There was no significant difference in OC length and VI between sexes. The mean OC length in Group II was significantly higher than in Group I (12.14 ± 3.14 vs 8.09 ± 2.64) (p < 0.001). The median VI in Group I was higher than in Group II (1.40% vs 0.40%) (p < 0.001). There were positive correlations between age and OC length (r = 0 .716), negative correlations between age and VI (r = ­0.822), and between VI and OC length (r = ­0.657). Conclusion: Quantitative reference values for DFE blood supply and OC length can guide the diagnosis and follow-up of many skeletal diseases.

Vascularized Medial Femoral Condyle Autografts for Osteochondral Lesions of the Talus: A Preliminary Prospective Randomized Controlled Trial.

Talar osteochondral lesions (OCLs) lead to progressive stages of talar destruction. Core decompression with cancellous bone grafting (CBG) is a common treatment for Berndt and Harty stages II and III. However, in a subset of patients, talar revascularization may fail. Surgical angiogenesis using vascularized medial femoral condyle (MFC) autografts may improve on these outcomes. These 2 treatment strategies were directly compared via a prospective preliminary randomized trial including 20 participants with talar core decompression followed by either cancellous (CBG group, n = 10) or vascularized MFC (MFC group, n = 10) bone grafting. Outcome analysis was performed with visual analog scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Lower Extremity Functional Scale (LEFS), and contrast-enhanced magnetic resonance imaging (MRI) scans. At 12 months of follow-up, the mean VAS score was reduced from 6.6 ± 2.5 preoperatively to 4 ± 1.9 in the CBG group and from 5.2 ± 2.9 preoperatively to 1 ± 1.1 in the MFC group (p < .001). The LEFS improved from 53.4 ± 13.1 to 62.6 ± 16.2 CBG and from 53 ± 9.3 to 72.4 ± 7.4 MFC (p = .114). AOFAS improved from 71 ± 12.1 to 84.1 ± 12.5 in CBG and from 70.5 ± 7.4 to 95.1 ± 4.8 in MFC (p = .019). The MRI scans in the CBG group demonstrated 9 partial malperfusions and 1 hypervascularized bone graft, whereas the MFC group had 8 well-vascularized grafts incorporated into the talus and 1 partial malperfusion. Vascularized MFC autografts provide superior pain relief along with improvement of physical function in patients with talar OCL stage II and III compared with CBG. To confirm these promising results, further multicenter randomized controlled trials are required.

Vascular Supply to the Femoral Head in Patients With Healed Slipped Capital Femoral Epiphysis.

BACKGROUND: Slipped capital femoral epiphysis (SCFE) is one of the most common hip disorders. The vascularity of the lateral epiphyseal vessels supplying the femoral head in patients with healed SCFE has not been well defined. The purpose of this study was to characterize the location and number of lateral epiphyseal vessels in young adults with healed SCFE. METHODS: This was a retrospective study of 17 patients (18 hips) with a diagnosis of SCFE and a matched control group of 17 patients (17 hips) with developmental dysplasia of the hip. All patients underwent high-resolution contrast-enhanced magnetic resonance imaging to visualize the path of the medial femoral circumflex artery and the lateral epiphyseal arterial branches supplying the femoral head. RESULTS: There were 5 unstable SCFEs and 13 stable SCFEs with an average slip angle of 31 degrees. (All patients had been treated with in situ pinning and screw removal). Average age at time of magnetic resonance imaging was 24.5 years (range, 15 to 34 y). The lateral epiphyseal vessels reliably inserted on the posterior-superior aspect of the femoral neck from the superior-anterior to the superior-posterior position in both the SCFE and control groups. An average of 2 (±0.8) retinacular vessels were identified in the SCFE group compared with 5.2 (±0.7) retinacular vessels in the control group (P<0.001). CONCLUSIONS: In healed SCFE, the lateral epiphyseal vessels reliably insert in the same anatomic region as patients with hip dysplasia; however, the overall number of vessels is significantly lower.

Revascularization of the necrotic femoral head after traumatic open anterior hip dislocation in a child: a case report.

INTRODUCTION: Avascular necrosis of the femoral capital epiphysis is the most serious complication after traumatic dislocation of the hip in children. This case report discusses the localization and revascularization of the necrotic femoral head following rarely experienced traumatic open anterior hip dislocation in children. CASE PRESENTATION: Our patient was an 11-year-old Japanese boy who had open anterior hip dislocation sustained in a traffic accident. Reduction of the hip joint was performed in an emergency operation, and he was evaluated using serial gadolinium-enhanced magnetic resonance imaging. T1-weighted magnetic resonance images showed two bands with low signal intensity in the femoral capital epiphysis on coronal and oblique axial planes, indicating the existence of avascular osteonecrosis of the femoral head. We observed gadolinium enhancement in the central region of the epiphysis, where the area between the two bands with low signal intensity was located. Serial assessment with enhanced magnetic resonance images during a non-weight-bearing period of 1.5 years after injury showed revascularization starting from the central region and converging toward the peripheral region. Although the patient had leg-length discrepancy due to the early epiphyseal closure, non-weight-bearing treatment for the avascular osteonecrosis of the femoral head achieved a favorable outcome without any hip joint dysfunction, pain, or sign of secondary osteoarthritic change within 4.5 years after injury. CONCLUSION: We confirmed the revascularization process of the necrotic lesion in the femoral capital epiphysis in an 11-year-old boy using serial gadolinium-enhanced magnetic resonance imaging. Conservative non-weight-bearing treatment achieved a favorable outcome.

Analysis of Trabecular Microstructure and Vascular Distribution of Capital Femoral Epiphysis Relevant to Legg-Calve-Perthes Disease.

Legg-Calve-Perthes disease is characterized by the capital femoral epiphyseal collapse, which occurs more reliably in the anterior quadrant than the more weight-bearing lateral quadrant. The purpose of this study was to determine whether there is a vascular or microstructural predisposition for anterior femoral epiphyseal collapse in Perthes disease. Thirty-two cadaveric proximal femoral epiphyses from 17 subjects (age 4-14 years old) underwent micro-computed tomography at 10-µm resolution. Each quadrant was analyzed for four markers of trabecular architecture: bone volume fraction (BV/TV), trabecular thickness, trabecular separation (TbSp), and trabecular number (TbN). Vascular channels were then mapped in each quadrant, identified by correlating surface topography with cross-sectional imaging. One-way analysis of variance revealed an overall difference between quadrants (p < 0.001) in BV/TV, TbN, and TbSp. However, post hoc analysis revealed there was no significant difference between the anterior and lateral quadrants for any of the four markers of trabecular architecture. Vascular channel mapping illustrated a predominance of vessels in the posterior half of the epiphysis compared to the anterior half (8.7 ± 4.0 vs. 3.4 ± 3.1 vascular channels, p < 0.001). The lack of microstructural differences between the anterior and lateral quadrants, and the predominance of vascular channels in the posterior half of the epiphysis with posteriorly-based medial femoral circumflex and ligamentum teres vessels suggests that the anterior femoral epiphysis may be a relative vascular watershed region, which predisposes it to collapse after the vascular insult of Perthes disease. Clinical significance: Improved understanding of the pathophysiology of anterior femoral epiphyseal collapse may inform future treatments aimed at revascularization. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1784-1789, 2019.

Vascularized Fibula Epiphysis Transfer for Pediatric Extremity Reconstruction: A Systematic Review and Meta-analysis.

BACKGROUND: Vascularized fibula epiphysis transfer for pediatric extremity reconstruction intends to preserve growth potential. However, few cases are reported, and outcomes are poorly characterized. METHODS: Systematic review was performed through a MEDLINE search using keywords "pediatric" or "epiphyseal" and "vascularized fibula." Patients were divided into upper extremity or lower extremity groups. Functional and growth outcomes were assessed, and indications, pedicle, complications, and need for secondary surgery were recorded. RESULTS: Twenty publications with 62 patients were included. Mean age was 5.9 years, and mean follow-up was 5.8 years. Indications included sarcoma (60%), congenital deformity (21%), trauma (13%), and infection (6%). Anterior tibial pedicle was most common (63%) and was associated with significantly improved growth outcomes compared with the peroneal pedicle (23%; P < 0.001). Fifty-three patients underwent upper extremity reconstruction, with the most common complication being fracture (35%) and most common secondary surgery flap salvage (7%). Among upper extremity patients, full function was achieved in 25% and impaired function in 75%. Full growth was observed in 63% of patients, partial growth in 31%, and no growth in 4%. Nine patients underwent lower extremity reconstruction, with the most common complication being fracture (22%) and most common secondary surgery derotational osteotomy (22%). Among lower extremity patients, full function was achieved in 44% and impaired function in 56%. Full growth was observed in 56% of patients, partial growth in 22%, and no growth in 22%. CONCLUSIONS: Vascularized fibula epiphysis transfer can accomplish full long-term growth and function. However, complications, revision surgery, and chronic impairment are common.

A simple, precocious, and reliable way to assess future clinical outcome in children with Perthes disease and mild femoral head involvement: correlation between MRI with diffusion-weighted and dynamic gadolinium-enhanced subtraction and Catterall and Herring classifications.

BACKGROUND: In children older than 5 years with a mild form of Legg-Calvé-Perthes disease, the outcome is difficult to predict. In this study, we retrospectively correlated gadolinium-enhanced subtracted (DGS) and diffusion (DWI) MRI findings to the radiographic assessment according to the Catterall and Herring et al. classifications and to the final score according to Stulberg et al.: the aim was to identify a precocious, simple, and objective criterion to differentiate between forms evolving favourably and forms requiring an early surgical treatment in order to avoid femoral head deformity and subsequent osteoarthritis. METHODS: Twelve boys with unilateral mild femoral head involvement (Catterall grade 2 or grade 3) underwent DSG and DWI MR during the early phase of the disease. The absence of enhancement of the external pillar on DSG MRI and the presence of metaphyseal hyperintensity on DWI were considered to be the signs of poor outcome. These findings were correlated with the Catterall and Herring et al. classifications at the initial sclerotic stage and early fragmentation phase and with the Stulberg et al. classifications at least 5 years after the onset of the disease. RESULTS: DSG MRI findings correctly discriminated three out of four patients with a good outcome but underestimated two out of eight patients with a poor outcome. DWI findings correlated with the Catterall and Herring et al. classifications in 12 out of 12 cases. In only one case, DWI findings did not correlate with the Stulberg et al. classification. CONCLUSION: DWI MR provides an objective and accurate prognostic criterion that is relatively easy to recognise. DGS MR findings are less accurate, thus underestimating the gravity of the disease in one-fourth of the patients with a poor outcome.

Restoration of Blood Flow to the Proximal Femoral Epiphysis in Unstable Slipped Capital Femoral Epiphysis by Modified Dunn Procedure: A Preliminary Angiographic and Intracranial Pressure Monitoring Study.

BACKGROUND: The major complication of unstable slipped capital femoral epiphysis (SCFE) is avascular necrosis (AVN) of the femoral head. The purpose of this study was to document by angiography the preoperative and postoperative perfusion to the proximal femoral epiphysis following an unstable SCFE. A specific aim was to determine whether blood flow could be restored. A secondary aim was to determine the efficacy of an intracranial pressure (ICP) monitor to assess blood flow within the femoral head intraoperatively. METHODS: Nine patients with an unstable SCFE underwent superselective angiogram of the medial circumflex femoral artery preoperatively, followed by operative fixation with an open reduction using a modified Dunn approach. Femoral head blood flow was evaluated with an ICP monitor. Angiography was repeated postoperatively. Patients were followed radiographically to assess for AVN. RESULTS: Follow-up averaged 22 months. Six patients did not have arterial flow to the femoral head on the preoperative angiogram. Flow was restored postoperatively on angiogram in 4 of the 6 patients. Two patients developed AVN. One had no flow to the femoral head preoperatively or postoperatively on angiogram and complete tearing of the periosteum was noted. In 1 patient, there was no ICP waveform after the initial reduction. After removing more callous and repeating reduction, the waveform returned. Of the 2 patients with AVN, 1 had an ICP waveform after reduction. CONCLUSIONS: This study documents that some patients with unstable SCFE present with reduced femoral head blood supply due to SCFE. It also demonstrates blood flow restoration in 4 patients by angiogram and 5 by ICP monitor after surgical treatment. No patient immediately lost blood flow due to surgery. ICP monitor is a safe intraoperative tool for real-time assessment of femoral head blood flow during open reduction of unstable SCFE. Presence of flow by ICP is not a guarantee that AVN will not develop, but absence of flow was predictive of AVN. LEVEL OF EVIDENCE: Therapeutic level I-prognostic. See Instructions for Authors for a complete description of levels of evidence.

Increased diffusion and decreased perfusion in epiphyses of femoral heads detected via intravoxel incoherent motion after closed reduction in children with developmental dysplasia of the hip.

Background Patients with developmental dysplasia of the hip (DDH) may have decreased blood supply to the femoral heads. Finding a non-invasive method to evaluate whether the femoral heads in patients with DDH are ischemic is paramount for orthopedic surgeons. Purpose To identify whether parameters reflecting perfusion and diffusion in intravoxel incoherent motion (IVIM) sequences can be used to assess ischemia in femoral heads in patients with DDH after closed reduction. Material and Methods Twenty-eight patients with DDH who had undergone closed reduction were enrolled. IVIM data were acquired using a 3-T magnetic resonance scanner, regions of interest were placed on the epiphyses; ADCslow, ADCfast, f, and ADCfast×f were measured. A Mann-Whitney U test was performed to compare ADCslow, ADCfast, f, and ADCfast×f between the lesion and control sides. Receiver operating characteristic curves were generated with respective cut-off values. The lesion sides were classified based on the International Hip Dysplasia Institute (IHDI) classification. ADCslow, ADCfast, f, and ADCfast×f were compared among the groups. Results ADCslow was higher and ADCfast, f, and ADCfast×f were lower on the lesion sides ( P = 0.000-0.002). The optimal cut-off value for ADCfast×f, ADCfast, ADCslow, and f were 0.030, 0.626, 0.000251, and 0.636, respectively. Higher IHDI classification scores on the lesion side were associated with lower ADCfast, f, and ADCfast×f, and higher ADCslow values. Conclusion IVIM is a promising method to investigate the perfusion and diffusion of epiphyses of femoral heads.

Ultrasonographic screening for subclinical osteochondrosis of the femoral trochlea in foals (28-166 days old): a prospective farm study.

BACKGROUND: Extensive osteochondritis dissecans (OCD) lesions of the lateral ridge of the trochlea of the femur (LRTF), the most common OCD-affected site in the stifle, have a poor outcome with surgical debridement and can be career ending. The early detection of osteochondrosis lesions and their conservative management holds the promise to enhance outcome. We hypothesise that ultrasonography is a valuable field screening tool to detect and monitor early subclinical LRTF osteochondrosis. OBJECTIVES: The goals were to 1) describe the normal ultrasonographic features of the LRTF in foals of different ages and 2) screen a foal cohort at the farm for early subclinical osteochondrosis lesions. STUDY DESIGN: Prospective cohort study. METHODS: The LRTF of both hindlimbs of Thoroughbred foals (n = 46, 27-166 days old) were imaged once with ultrasonography and radiography (lateromedial and caudolateral-craniomedial oblique views). Cartilage thickness, ossification front indentation of the chondro-osseous junction and epiphyseal vascularisation were assessed on ultrasonography. Follow-up radiographs were taken as yearlings. RESULTS: The cartilage thickness, ossification front indentation and epiphyseal vascularisation significantly decreased with advancing maturity. Subclinical osteochondrosis lesions, characterised by semicircular indentations in the ossification front (indirect evidence of focal failure of ossification and retained cartilage) were detected in six foals (28-145 days old), both with radiography and ultrasonography. Ultrasonography provided a better overall subjective assessment of the osteochondrosis lesion topography (length, depth and the width) compared with radiography. MAIN LIMITATIONS: Post-mortem validation of lesions was not possible. CONCLUSION: Ultrasonography of the LRTF is a practical, inexpensive and reliable technique to discriminate physiological from pathological events at the LRTF in young foals. It revealed the complex topography of the chondro-osseous junction permitting a rapid, comprehensive assessment of the subclinical osteochondrosis lesions in very young foals.

Management of traumatic bone defects: Metaphyseal versus diaphyseal defects.

Although bone defects after trauma appear in different locations and forms, many clinicians have adopted a single strategy to deal with any defect. In this overview, a distinction is made between metaphyseal, or cancellous defects, and diaphyseal, or cortical defects. The treatment goals and background of these two types of defects are discussed in order to describe the difference in strategy and hence the difference in treatment method.

Epiphyseal Arterial Network and Inferior Retinacular Artery Seem Critical to Femoral Head Perfusion in Adults With Femoral Neck Fractures.

BACKGROUND: A better understanding of the blood supply of the femoral head is essential to guide therapeutic strategies for patients with femoral neck fractures. However, because of the limitations of conventional techniques, the precise distribution and characteristics of intraosseous arteries of the femoral head are not well displayed. QUESTIONS/PURPOSES: To explore the characteristics and interconnections of the intraosseous vessel system between different areas of the femoral head and the possible blood supply compensatory mechanism after femoral neck fracture. METHODS: The three-dimensional (3-D) structures of the intraosseous blood supply in 30 uninjured normal human femoral heads were reconstructed using angiography methods and microCT scans. The data were imported in the AMIRA® and MIMICS® software programs to reconstruct and quantify the extra- and intraosseous arteries (diameter, length). In a separate experiment, we evaluated the residual blood supply of femoral heads in 27 patients with femoral neck fractures before surgery by analyzing digital subtraction angiography data; during the study period, this was performed on all patients in whom hip-preserving surgery was planned, rather than arthroplasty. The number of affected and unaffected subjects included in the three groups (superior, inferior, and anterior retinacular arteries) with different types of fractures (Garden Types I-IV) were recorded and analyzed (Fisher's exact test) to reflect the affected degrees of these three groups of retinacular arteries in patients after femoral neck fractures. RESULTS: The main results of our cadaver study were: (1) the main blood supply sources of the femoral head were connected by three main network structures as a whole, and the epiphyseal arterial network is the most widely distributed and the primary network structure in the femoral head; (2) the main stems of the epiphyseal arteries which were located on the periphery of the intraosseous vascular system have fewer anastomoses than the network located in the central region; (3) compared with the round ligament artery and anterior retinacular artery, the inferior retinacular artery has a relatively large caliber. Digital subtraction angiography of the 27 patients with hip fractures indicated that the inferior retinacular arterial system had a high likelihood of being unaffected after femoral neck fracture (100% [14 of 14] in nondisplaced fractures and 60% [six of 10] in Garden Type III fractures). CONCLUSIONS: The epiphyseal arterial network and inferior retinacular arterial system appear to be two important structures for maintaining the femoral head blood supply after femoral neck fracture. Increased efforts to protect these key structures during surgery, such as drilling and placing internal implants closer to the central region of the femoral head, might be helpful to reduce the effect of iatrogenic injury of the intraosseous vascular system. CLINICAL RELEVANCE: 3-D anatomic evidence of intraosseous arterial distribution of the femoral head and the high frequency with which the inferior retinacular arteries remained patent after femoral neck fracture lead us to consider the necessity of drilling and placing internal implants closer to the central region of the femoral head during surgery. Future controlled studies might evaluate this proposition.

Skeletal immaturity, rostral sparing, and disparate hip morphologies as biomechanical causes for Legg-Calvé-Perthes' disease.

Legg-Calvé-Perthes' (Perthes') disease is a developmental disease of the hip joint that may result in numerous short and long term problems. The etiology of the disease remains largely unknown, but the mechanism is believed to be vascular and/or biomechanical in nature. There are several anatomical characteristics that tend to be prevalent in children with Perthes' disease, namely: skeletal immaturity, reduced height, and rostral sparing. We present an overview of the literature, summarizing the current understanding of the pathogenesis, particularly related to how the formation of the vasculature to the femoral epiphysis places children aged 5-8 at a higher risk for Perthes' disease, how skeletal immaturity and rostral sparing could increase the probability of developing Perthes' disease, and how animal models have aided our understanding of the disease. In doing so, we also explore why Perthes' disease is correlated to latitude, with populations at higher latitudes having higher incidence rates than populations closer to the Equator. Finally, we present five hypotheses detailing how Perthes' disease could have a biomechanical cause. Clin. Anat. 29:759-772, 2016. © 2016 Wiley Periodicals, Inc.

Neovascularization of osteoporotic metaphyseal bone defects: A morphometric micro-CT study.

PURPOSE: Neovascularization is essential for bone regeneration in fractures. This study aimed to investigate the microvascular morphology and distribution in the non-injured femur and the neovascularization of the metaphyseal critical size defect in a small animal model of osteoporosis. MATERIALS AND METHODS: Female rats (n=7) were ovariectomized (OVX) and received a multideficiency diet. Three months after OVX, a 5mm wedge shaped critical size defect was cut at the distal femoral metaphysis and stabilized with a T-shaped mini-plate. After six weeks, the animals were euthanized, and femora were removed and decalcified for micro-CT measurement of fracture neovascularization. RESULTS: No fracture healing was observed along the critical size defects. In the non-injured bone, micro-vessel distribution showed a specific pattern, thereby enabling a differentiation between epi-, meta- and diaphysis. Micro-CT based morphometry revealed a significant reduction of the vascular volume fraction as well as the vascular thickness (p<0.001) in the critical size defect compared to the intact contralateral femur. Blood volume related vascular surface (vascular surface/volume) increased significantly (p<0.001). Connectivity density and tissue volume related vascular surface (vascular surface density) did not change significantly. CONCLUSIONS: Micro-CT based vascular morphometry demonstrated differences between epi-, meta- and diaphysis in the non-injured bone as well as differences between the critical size defect and the non-injured metaphysis. As angiogenesis is a crucial prerequisite that precedes osteogenesis, our results may influence further evaluation of osteoconductive or osteogenic biomaterials in this small animal model of osteoporosis.

Vascularized proximal fibula epiphyseal transfer for distal radius reconstruction in children: A systematic review.

PURPOSE: Reconstruction of the distal radius in children is cumbersome, requiring simultaneous restoration of joint function and axial growth. Vascularized proximal fibular epiphyseal transfers (VFET) have been popularized over non-vascularized transfers and prosthesis. This systematic review aims to evaluate the effectiveness of VFET and its associated complications. METHODS: Electronic database of PubMed MEDLINE was searched between 1970 and 2014. Studies reporting VFET for distal radius reconstruction in children (<15 years old) with clear reporting of technique (vascular pedicle) and objective outcome measures were included. Outcomes of interest were rate of graft growth, bone union and complications. A one-way Analysis of Variance (ANOVA) test was used to compare growth rates between pedicle types. RESULTS: Fourteen studies met the inclusion criteria, representing 25 patients. Pedicles used were anterior tibial (44%), peroneal (16%), or bi-pedicled (40%) anastomosed in antegrade (64%) or reverse flow (36%) fashion. Among all pedicle types, best results were achieved using anterior tibial artery with reversed flow, yielding average growth rate of 0.83 cm/year (P = 0.01). Recipient complications included four premature epiphyseal plate closures, a flap loss, and six wrist radial deviations. Donor complications included six common peroneal nerve palsies (five temporary, a permanent), and a talocalcaneal instability. Overall complication rates between pedicle types were comparable (P = 0.062). CONCLUSION: VFET may be a surgical option capable of restoring joint function and axial growth potential in select patients. The reverse flow technique based on the anterior tibial artery may result in superior outcomes. However, the overall complication rate is high and permanent peroneal nerve palsy may result. LEVEL OF EVIDENCE: IV © 2015 Wiley Periodicals, Inc. Microsurgery 36:705-711, 2016.

Lateral Femoral Condyle Flap: An Alternative Source of Vascularized Bone From the Distal Femur.

PURPOSE: To elucidate the vascular anatomy of the superolateral geniculate artery (SLGA) and its supply to the periosteum of the lateral femoral condyle (LFC) and to provide guidelines for flap design and describe an illustrative case. METHODS: Thirty-one fresh cadaveric limbs were dissected. The vascular anatomy of the SLGA and its distal branches to skin, muscle, and periosteum were identified. Fluoroscopic images were taken during continuous perfusion of a radiopaque contrast dye into the SLGA. Intra-arterial injections of latex rubber were performed in 12 cadaver limbs. The vascular territory was traced from the SLGA to its distal branches, and surrounding soft tissues were dissected. RESULTS: The SLGA originated from the popliteal artery 4.9 ± 1.2 cm (range, 2.8-7 cm) from the knee joint and its pedicle diameter was 1.8 ± 0.5 mm (range, 1-3 mm). SGLA pedicle-specific fluoroscopic angiography demonstrated a dense filigree of vessels over the lateral distal femur. Arterial latex injections confirmed that the SLGA supplied the periosteum of the LFC and distal femur shaft. The proximal-most extent of periosteal perfusion was 11.7 ± 2.1 cm (range, 9.3-14.1 cm) from the knee joint. The average pedicle length of LFC osteoperiosteal flaps was 4.8 ± 0.9 cm (range, 3.5-6.3 cm). CONCLUSIONS: The LFC flap consistently demonstrated almost 12 cm of femur length perfusion based on the SLGA pedicle. The anatomy of this flap enables chimeric designs combining soft tissue, bone, and cartilage. CLINICAL RELEVANCE: The vascularized LFC flap is an option for reconstruction of osseous defects of the upper extremity.

Effect of arterial deprivation on growing femoral epiphysis: quantitative magnetic resonance imaging using a piglet model.

OBJECTIVE: To investigate the usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion MRI for the evaluation of femoral head ischemia. MATERIALS AND METHODS: Unilateral femoral head ischemia was induced by selective embolization of the medial circumflex femoral artery in 10 piglets. All MRIs were performed immediately (1 hour) and after embolization (1, 2, and 4 weeks). Apparent diffusion coefficients (ADCs) were calculated for the femoral head. The estimated pharmacokinetic parameters (Kep and Ve from two-compartment model) and semi-quantitative parameters including peak enhancement, time-to-peak (TTP), and contrast washout were evaluated. RESULTS: The epiphyseal ADC values of the ischemic hip decreased immediately (1 hour) after embolization. However, they increased rapidly at 1 week after embolization and remained elevated until 4 weeks after embolization. Perfusion MRI of ischemic hips showed decreased epiphyseal perfusion with decreased Kep immediately after embolization. Signal intensity-time curves showed delayed TTP with limited contrast washout immediately post-embolization. At 1-2 weeks after embolization, spontaneous reperfusion was observed in ischemic epiphyses. The change of ADC (p = 0.043) and Kep (p = 0.043) were significantly different between immediate (1 hour) after embolization and 1 week post-embolization. CONCLUSION: Diffusion MRI and pharmacokinetic model obtained from the DCE-MRI are useful in depicting early changes of perfusion and tissue damage using the model of femoral head ischemia in skeletally immature piglets.

Development of a mouse model of ischemic osteonecrosis.

BACKGROUND: Availability of a reliable mouse model of ischemic osteonecrosis could accelerate the development of novel therapeutic strategies to stimulate bone healing after ischemic osteonecrosis; however, no mouse model of ischemic osteonecrosis is currently available. QUESTIONS/PURPOSES: To develop a surgical mouse model of ischemic osteonecrosis, we asked, (1) if the blood vessels that contribute to the blood supply of the distal femoral epiphysis are cauterized, can we generate an osteonecrosis mouse model; (2) what are the histologic changes observed in this mouse model, and (3) what are the morphologic changes in the model. METHODS: We performed microangiography to identify blood vessels supplying the distal femoral epiphysis in mice, and four vessels were cauterized using microsurgical techniques to induce ischemic osteonecrosis. Histologic assessment of cell death in the trabecular bone was performed using terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) and counting the empty lacunae in three serial sections. Quantitation of osteoclast and osteoblast numbers was performed using image analysis software. Morphologic assessments of the distal femoral epiphysis for deformity and for trabecular bone parameters were performed using micro-CT. RESULTS: We identified four blood vessels about the knee that had to be cauterized to induce total ischemic osteonecrosis of the distal femoral epiphysis. Qualitative assessment of histologic sections of the epiphysis showed a loss of nuclear staining of marrow cells, disorganized marrow structure, and necrotic blood vessels at 1 week. By 2 weeks, vascular tissue invasion of the necrotic marrow space was observed with a progressive increase in infiltration of the necrotic marrow space with the vascular tissue at 4 and 6 weeks. TUNEL staining showed extensive cell death in the marrow and trabecular bone 24 hours after the induction of ischemia. The mean percent of TUNEL-positive osteocytes in the trabecular bone increased from 2% ± 1% in the control group to a peak of 98% ± 3% in the ischemic group 1 week after induction of ischemia (mean difference, 96%; 95% CI, 81%-111%; p < 0.0001). The mean percent of empty lacunae increased from 1% ± 1% in the control group to a peak of 78% ± 15% in the ischemic group at 4 weeks (mean difference, 77%; 95% CI, 56%-97%; p < 0.0001). Quantitative analysis showed that the mean number of osteoclasts per bone surface was decreased in the ischemic group at 1, 2, and 4 weeks (p < 0.0001, < 0.0001, and p = 0.02, respectively) compared with the control group. The mean number of osteoclasts increased to a level similar to that of the control group at 6 weeks (p = 0.23). The numbers of osteoblasts per bone surface were decreased in the ischemic group at 1, 2 and 4 weeks (p < 0.0001 for each) compared with the numbers in the control group. The mean number of osteoblasts also increased to a level similar to that of the control group at 6 weeks (p = 0.91). Mean bone volume percent assessed by micro-CT was lower in the ischemic group compared with the control group from 2 to 6 weeks. The mean differences in the percent bone volume between the control and ischemic groups at 2, 4, and 6 weeks were 5.5% (95% CI, 0.9%-10.2%; p = 0.01), 5.3% (95% CI, 0.6%-9.9%; p = 0.02), and 6.0% (95% CI, 1.1%-10.9%; p = 0.008), respectively. A deformity of the distal femoral epiphysis was observed at 6 weeks with the mean epiphyseal height to width ratio of 0.74 ± 0.03 in the control group compared with 0.66 ± 0.06 in the ischemic group (mean difference, 0.08; 95% CI, 0.00-0.16; p = 0.03). CONCLUSION: We developed a novel mouse model of ischemic osteonecrosis that produced extensive cell death in the distal femoral epiphysis which developed a deformity with time. CLINICAL RELEVANCE: The new mouse model may be a useful tool to test potential therapeutic strategies to improve bone healing after ischemic osteonecrosis.