Assessment of vascularity of the femoral head using gadolinium (Gd-DTPA)-enhanced magnetic resonance imaging

The Duration of Hardware Retention After Radiologic Union of Surgically Treated Femoral Neck Fractures in Children May Predict the Aggravation or Occurrence of Avascular Necrosis of the Femoral Head or Neck After Hardware Removal

BACKGROUND

The incidence of aggravation or occurrence of avascular necrosis (AVN) following hardware removal in surgically treated pediatric femoral neck fractures who achieved radiologic consolidation is unknown. This study aimed to investigate the risk factors for this complication.

METHODS

Seventy-one pediatric (mean age: 9.8±3.9 y) were retrospectively analyzed. Risk factors (age, sex, laterality, severity of initial displacement, type of fracture, time from trauma to reduction, reduction and fixation method, quality of reduction, time required to achieve radiologic union, duration of hardware retention, presence of AVN before hardware removal and follow-up time) were recorded. The severity of AVN was assessed based on radiographs with Ratliff's classification.

RESULTS

Following hardware removal, the aggravation/occurrence of AVN was detected in 11 hips (15.5%). Among the 5 hips (7%) with aggravation of AVN, 1 (1.4%) with type II AVN and 3 (4.2%) with type III AVN exhibited aggravation of type I AVN, while the remaining hip (1.4%; type I) showed enlargement of the involved AVN area. Six hips (8.5%) developed AVN following hardware removal: 2 (2.8%) were classified as type I and 4 (5.6%) as type III. Receiver operating characteristic curve analysis indicated that hardware retention >7 months after union is associated with a decreased rate of aggravation or occurrence of AVN of the femoral neck or head following hardware removal.

CONCLUSIONS

The incidence of aggravation or occurrence of AVN following hardware removal in surgically treated pediatric femoral neck fractures is 15.5%; hardware retention >7 months after radiologic union may reduce the risk of aggravation or occurrence of AVN of the femoral neck or head postimplant removal.

LEVEL OF EVIDENCE

Level III.

Femoral Head Vascularity After Arthroscopic Femoral Osteochondroplasty: An In Vivo Dynamic Contrast-Enhanced MRI Study

Background

A serious concern with surgical procedures around the hip joint is iatrogenic injury of the arterial supply to the femoral head (FH) and consequent development of FH osteonecrosis. Cam-type morphology can extend to the posterosuperior area. Understanding the limit of the posterior superior extension of the femoral osteochondroplasty is paramount to avoid underresection and residual impingement while maintaining FH vascularity.

Purpose/Hypothesis

The aim of this study was to quantify the impact of arthroscopic femoral osteochondroplasty on the FH vascular supply. It was hypothesized that keeping the superior extension of the resection zone anterior to the 12-o'clock position would maintain FH vascularity.

Study Design

Case series; Level of evidence, 4.

Methods

Ten adult patients undergoing arthroscopic femoroacetabular impingement (FAI) surgery were included in the study. Computed tomography (CT) scans were obtained before and after arthroscopic osteochondroplasty to define the extension of resection margins. To quantify FH vascularity, postoperative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was obtained at 2 time points: immediately after surgery and at the 3-month follow-up. Custom MRI analysis software was used to quantify perfusion.

Results

CT scan analysis demonstrated that the superior resection margin was maintained anterior to the 12-o'clock position in half of the patients. The remining 5 patients had a mean posterior extension of 11.4° ± 7.5°. The immediate postoperative DCE-MRI revealed diminished venous outflow in the operative side but no difference in overall FH perfusion. At the 3-month follow-up DCE-MRI, there was no perfusion difference between the operative and nonoperative FHs.

Conclusion

This study provides previously unreported quantitative MRI data on in vivo perfusion of the FH after the commonly performed arthroscopic femoral osteochondroplasty for the treatment of cam-type FAI. Maintaining resection margins anterior to the 12-o'clock position, or even 10° posteriorly, was not observed to impair perfusion to the FH.

A Method to Visualize and Quantify the Intraosseous Arteries of the Femoral Head by Vascular Corrosion Casting

OBJECTIVE

To describe a method to display the three-dimensional distribution of intraosseous arteries in the femoral head by vascular corrosion casting.

METHODS

An experimental study was done to expose the intraosseous arteries of the femoral head by a microperfusion corrosion method between January 2021 and May 2021. Specimens were 23 swine femoral heads (12 female specimens and 11 male specimens, where age of swine ranged from 8 to 12 months, and the weight was approximately 150 kg). The femoral heads were microperfused with the vascular casting resin through retinacular arteries, and the bone of the femoral head was dissolved with 50% sodium hydroxide and 10% hydrochloric acid and rinsed under the microscope until the vessel casts were completely exposed. The distribution and anastomosis of the arteries in the femoral head were observed under direct vision and microscopy. The diameter of the artery in the femoral head was measured at 0.5 cm after its entry into the bone of the femoral head with a microscale under the microscope. The number of internal arteries with diameter ≥0.05 mm was counted. The number and diameter of the main trunk of the epiphyseal arteries in the femoral head between male and female swine were compared.

RESULTS

The vascular casting specimen of the swine femoral head was successfully produced by using epoxy resin as a casting agent, and the three-dimensional intraosseous vascular structures were clearly visible. The number of epiphyseal arteries in male and female swine was 8.55 ± 2.15 and 8.83 ± 2.15 (t = -0.31, p = 0.38), respectively. The diameters of the superior epiphyseal arteries in male and female swine were 0.35 ± 0.09 and 0.31 ± 0.08 mm (t = 1.03, p = 0.16), the diameters of the inferior epiphyseal arteries were 0.47 ± 0.05 and 0.49 ± 0.09 mm (t = -0.57, p = 0.29), and the diameters of the anterior epiphyseal arteries were 0.34 ± 0.08 and 0.33 ± 0.13 mm (t = 0.32, p = 0.37). There was no significant difference in the number and diameter of the main trunk of intraosseous arteries between male and female swine (p > 0.05). The main trunk of intraosseous arteries formed an anastomosis in the center of the femoral head. Among 23 swine femoral head samples, three types of intraosseous anastomosis were observed, including 13 (57%) posterior superior-posterior inferior, seven (30%) posterior inferior-anterior, and three (13%) uniform intraosseous anastomosis.

CONCLUSION

The microperfusion corrosion method can produce the vascular casting specimen of swine femoral head revealing the three-dimensional structure of the intraosseous artery, which clearly shows the origin, course and branches, and diameter, as well as the anastomosis, of nutrient arteries in the femoral head. This method provides a simple and rapid technique for quantifying and visualizing intraosseous arteries.

Vascularity of the early post-natal human distal femoral chondroepiphysis: Quantitative MRI analysis

PURPOSE

Injury to or abnormality of developing distal femoral chondroepiphysis blood supply has been implicated in osteochondritis dissecans development. Progressive decrease in epiphyseal cartilage blood supply occurs in normal development; however, based on animal studies, it is hypothesized that there is greater decrease in regions more prone to osteochondritis dissecans lesions. We aimed to quantify differential regional perfusion of the immature distal femoral chondroepiphysis. We hypothesized there is decreased perfusion in the lateral aspect of the medial femoral condyle, the classic osteochondritis dissecans lesion location.

METHODS

Five fresh-frozen human cadaveric knees (0-6 months old) were utilized. The superficial femoral artery was cannulated proximally and contrast-enhanced magnetic resonance imaging performed using a previously reported protocol for quantifying osseous and soft tissue perfusion. Regions of interest were defined, and signal enhancement changes between pre- and post-contrast images, normalized to background muscle, were compared.

RESULTS

When comparing average normalized post-contrast signal enhancement of whole condyles, as well as distal, posterior, and inner (toward the notch) aspects of the medial and lateral condyles, no significant perfusion differences between condyles were found. In the medial condyle, no significant perfusion difference was found between the medial and lateral aspects.

CONCLUSION

We quantified immature distal femoral chondroepiphysis regional vascularity in the early post-natal knee. In specimens aged 0-6 months, no distinct watershed region was detected. Despite possible limitations, given small sample size, as well as resolution of magnetic resonance imaging and analysis, our results suggest the hypothesized vascular abnormality predisposing osteochondritis dissecans either does not occur universally or occurs after this developmental age.

Effect of the Number, Size, and Location of Cannulated Screws on the Incidence of Avascular Necrosis of the Femoral Head in Pediatric Femoral Neck Fractures: A Review of 153 Cases

BACKGROUND

The correlation between the number, size, and location of cannulated screws and the incidence of avascular necrosis (AVN) in children with femoral neck fractures treated surgically is uncertain.

METHODS

We retrospectively reviewed 153 children (mean age: 10.6±3.7 y) with femoral neck fractures treated by internal fixation with 2 (n=112) or 3 (n=41) cannulated screws. The severity of initial displacement was divided into incomplete (type I) and complete (type II, angulation <50 degrees; type III, angulation >50 degrees) fractures. The diameter of the screw was measured and recorded as a percentage of the femoral neck width. The distance (D) between the mid-point of each screw at the base (B) of the femoral neck and at the tip (T) of each screw and the superior and anterior cortices of the femoral neck, respectively, were measured on anteroposterior (AP) and lateral (L) radiographs. Values were expressed as the ratio between the measured distance and the width of the femoral neck (BDAP%, TDAP%, BDL%, and TDL%). The correlation between the number, size, and location of the screws and AVN was analyzed.

RESULTS

Patients with type II of initial displacement treated with 2 cannulated screws had a lower AVN rate (21.4%) than those treated with 3 screws (44.8%) (P=0.027). Screw diameter (19%) in patients with AVN was larger than (17%) in patients without AVN (P<0.001); patients with AVN had a lower BDAP% (48.6%) than those without AVN (56.4%) (P<0.001). Screw size and BDAP% were risk factors for AVN (P<0.05). Further, screw diameter >16.5% and BDAP% <51.6% of the femoral neck width were the cutoff values for an increased AVN rate (P<0.05).

CONCLUSIONS

Patients treated with 2 cannulated screws showed a lower rate of AVN than patients treated with 3 screws. Screws of larger size and screws closer to the piriformis fossa on AP radiographs increased the risk of AVN in children with femoral neck fractures treated surgically.

LEVEL OF EVIDENCE

Level III.

The role of the medial buttress plate in the treatment of Pauwels type II and III femoral neck fracture in nonelderly patients: a retrospective study and preliminary results

Background

The purpose of this study was to compare the effectiveness of multiple cannulated screws combined with medial buttress plate or not for the treatment of unstable femoral neck fracture in nonelderly patients.

Methods

Sixty-nine nonelderly patients with Garden type III-IV femoral neck fracture were retrospectively analyzed. The patients were divided into MCS (multiple cannulated screws) group and CMBP (combined with medial buttress plate) group according to the surgical method. Patient’s demographic data, Harris Hip Score, EQ-5D index and complications at a minimum of 2 years follow-up were analyzed.

Results

There were 47 patients in the MCS group (35 male and 12 females) with a mean age of 40.28 ± 12.64 years, whereas 22 patients in the CMBP group (17 male and 5 females) with a mean age of 43.86 ± 12.55 years. In the MCS group, there were 1 (2.1%) avascular necrosis, 5 (10.6%) postoperative nonunion, 5 (10.6%) implant failure, and 2 (4.3%) femoral neck shortening. While 1 (4.5%) implant failure, 2 (9.1%) postoperative nonunion and 2 (9.1%) impingement in the CMBP group. For patients with Pauwels type II and III femoral neck fracture, the CMBP group had higher HHS scores at 3 months after surgery than the MCS group (P < 0.05), whereas there was no statistical significance at 6 months, 1 year, and 2 years (P > 0.05). The same results were found in the EQ-5D index.

Conclusions

In our cohort, we observed better outcomes in the CMBP group at 3 and 6 months, with later results similar between groups. However, there were fewer complications in the CMBP group, without obviously blood-supply disruption, especially in Pauwels type II and III. Further, anatomic reduction and stable fixation may contribute to satisfactory outcomes in the treatment of nonelderly displaced femoral neck fractures.

Quantitative contrast enhanced dual energy CT to predict avascular necrosis: a feasibility study of proximal humerus fractures

BACKGROUND

Avascular necrosis is a delayed complication of proximal humerus fractures that increases the likelihood of poor clinical outcomes. CT scans are routinely performed to guide proximal humerus fracture management. We hypothesized iodine concentration on post-contrast dual energy CT scans identifies subjects who develop avascular necrosis and ischemia due to compromised blood flow.

MATERIALS AND METHODS

55 patients with proximal humerus fractures enrolled between 2014 and 2017 underwent clinical, radiographic and contrast enhanced dual energy CT assessment. Iodine densities of the humeral head and the glenoid (control) were measured on CT. Subjects managed with open reduction internal fixation or conservatively (non-surgical) were followed for up to two years for radiographic evidence of avascular necrosis. Arthroplasty subjects underwent histopathologic evaluation for ischemia of the resected humeral head.

RESULTS

17 of 55 subjects (30.9%) were treated conservatively, 21 (38.2%) underwent open reduction internal fixation and 17 of 55 (30.9%) underwent arthroplasty. Of the 38 subjects treated conservatively or with ORIF, 20 (52.6%) completed 12 months of follow up and 14 (36.8%) 24 months of follow up. At 12 months follow up, two of 20 subjects (10%) and at 24 months 3 of 14 subjects (21.4%) developed avascular necrosis. At 12 months, the mean humerus/glenoid iodine ratio was 1.05 (standard deviation 0.24) in subjects with AVN compared to 0.91 (0.24) in those who did not. At 24 months, subjects with avascular necrosis had a mean humerus/glenoid iodine concentration ratio of 1.06 (0.17) compared to 0.924 (0.21) in those who did not. Of 17 arthroplasty subjects, 2 had severe ischemia and an iodine ratio of 1.08 (0.30); 5 had focal ischemia and a ratio of 1.00 (0.36); and 8 no ischemia and a ratio of 0.83 (0.08).

CONCLUSIONS

Quantifying iodine using dual energy CT in subjects with proximal humerus fractures is technically feasible. Preliminary data suggest higher humeral head iodine concentration may increase risk of avascular necrosis; however, future studies must enroll and follow enough subjects managed with open reduction internal fixation or conservatively for two or more years to provide statistically significant results. Trial Registrations NCT02170545 registered June 23, 2014, ClinicalTrials.gov.

The effect of calcar femoral neck plating on vascularity of the femoral head and neck

Aims

Surgical treatment of young femoral neck fractures often requires an open approach to achieve an anatomical reduction. The application of a calcar plate has recently been described to aid in femoral neck fracture reduction and to augment fixation. However, application of a plate may potentially compromise the regional vascularity of the femoral head and neck. The purpose of this study was to investigate the effect of calcar femoral neck plating on the vascularity of the femoral head and neck.

Methods

A Hueter approach and capsulotomy were performed bilaterally in six cadaveric hips. In the experimental group, a one-third tubular plate was secured to the inferomedial femoral neck at 6:00 on the clockface. The contralateral hip served as a control with surgical approach and capsulotomy without fixation. Pre- and post-contrast MRI was then performed to quantify signal intensity in the femoral head and neck. Qualitative assessment of the terminal arterial branches to the femoral head, specifically the inferior retinacular artery (IRA), was also performed.

Results

Quantitative MRI revealed a mean reduction of 1.8% (SD 3.1%) of arterial contribution in the femoral head and a mean reduction of 7.1% (SD 10.6%) in the femoral neck in the plating group compared to non-plated controls. Based on femoral head quadrant analysis, the largest mean decrease in arterial contribution was in the inferomedial quadrant (4.0%, SD 6.6%). No significant differences were found between control and experimental hips for any femoral neck or femoral head regions. The inferior retinaculum of Weitbrecht (containing the IRA) was directly visualized in six of 12 specimens. Qualitative MRI assessment confirmed IRA integrity in all specimens.

Conclusion

Calcar femoral neck plating at the 6:00 position on the clockface resulted in minimal decrease in femoral head and neck vascularity, and therefore it may be considered as an adjunct to laterally-based fixation for reduction and fixation of femoral neck fractures, especially in younger patients.

Cite this article: Bone Jt Open 2021;2(8):611–617.

Biomechanical comparison of five cannulated screw fixation strategies for young vertical femoral neck fractures

Vertical femoral neck fractures in patients younger than 65 years of age often require hip-conserving surgeries. However, traditional fixation strategies using three parallel cannulated screws often fail in such patients due to an unfavorable biomechanical environment. This study compared different cannulated screw fixation techniques in patients via patient-specific finite element analysis with linear tetrahedral (C3D4) elements. Forty vertical femoral neck fracture models were created based on computed tomography images obtained from eight healthy participants. Five different fixation strategies: alpha, buttress, rhomboid, inverted triangle, and triangle were assessed in walking status. Biomechanical parameters including stiffness, interfragmentary motion in two directions (detachment and shearing), compression force, and maximal implant stress were evaluated. The mean relative coefficient of strain distribution between the finite element analysis and experiment was from 0.78 to 0.94. Stiffness was highest (p < .05) in the buttress group (923.1 N/mm), while interfragmentary motion was lowest (p < .05) in the alpha group. Maximal stress was highest (p < .05) in the buttress group and lowest in the alpha group. Shearing values were significantly lower in the alpha group than in the rhomboid group (p = .004). Moreover, Shearing values were significantly higher (p = .027), while detachment values were significantly lower (p = .027), in the inverted triangle than in the triangle group. Clinical significance: Our results suggest that alpha fixation is the most reliable and biomechanically efficient strategy for young patients with vertical femoral neck fractures. Regular and inverted triangular fixation strategies may be suitable for fractures of different skeletal constructions due to antidetachment/shearing abilities.

Quantitative assessment of the vascularity of the skeletally immature patella: a cadaveric study using MRI

PURPOSE

While predominant blood supply to the adult patella enters inferomedially, little is known about skeletally immature patellar perfusion. Improved knowledge of immature patella vascularity can further understanding of osteochondritis dissecans, dorsal defects of the patella and bipartite patella, and help ensure safe surgical approaches. We hypothesized that the immature patella would exhibit more uniform blood flow. The study purpose was to quantify immature patella regional perfusion in comparison with adults.

METHODS

Ten cadaveric knees were utilized (five immature, five mature). The superficial femoral artery was cannulated proximally. Signal enhancement increases were compared from pre- to post-contrast MRI to assess relative arterial contributions to patella regions (quadrants, anterior/posterior, superior/inferior, medial/lateral, and outer/inner).

RESULTS

Quantitative-MRI analysis revealed similar distribution of enhancement between the immature and mature patella. The inferior pole exhibited significantly higher arterial contribution versus superior pole in both immature and mature groups (p = 0.009; both groups), while the inferomedial quadrant had the highest arterial contribution of all quadrants in both groups. The superolateral quadrant demonstrated the lowest arterial contribution in the immature group and second lowest in the adult group. The patella outer periphery had significantly greater arterial contribution than the inner central region in both immature (p = 0.009) and mature (p = 0.009) groups.

CONCLUSION

Distribution of arterial contributions between the immature and mature patella was similar. Our results highlight the importance of inferior and inferomedial blood supply in both immature and mature patellas. These findings have implications for paediatric and adult patients; surgical damage to inferior patellar vessels should be avoided to prevent associated complications.

Role of preoperative posterior tilt on the outcomes of internal fixation of non-displaced femoral neck fractures: A systematic review and meta-analysis

INTRODUCTION

There has been an increased interest in the role of preoperative posterior tilt, as measured on lateral radiographs, on the outcomes of internal fixation of non-displaced femoral neck fractures (FNF). The goal was to assess the available evidence for this in the literature.

PATIENTS AND METHODS

PRISMA guidelines were followed. PubMed, Embase and Cochrane were searched on June 10th, 2020 for studies assessing the role of posterior tilt on outcomes of internal fixation of non-displaced FNF. Primary outcomes were non-union and fixation failure, avascular necrosis (AVN), treatment failure, and reoperation (excluding symptomatic hardware removal). Outcomes were reported in Odds Ratio (OR) with 95% confidence intervals [CI].

RESULTS

Fourteen studies and 3729 patients were included (mean age 76 years, 72% female, mean follow-up 25 months). Moderate evidence was noted for the following: patients with greater preoperative posterior tilt had an increased risk of non-union and fixation failure (OR 2.4 [1.3 - 4.3]; p = 0.006), no increased risk of AVN (p = 0.550), an increased risk of treatment failure (OR 6.0 [2.2 - 15.9]; p<0.001) and reoperation (OR 2.5 [1.4 - 4.4]; p = 0.002). Furthermore, a greater preoperative tilt of 9.0° [4.1° - 13.9°] for treatment failure and 6.1° [3.7° - 8.5°] (p<0.001) for reoperation were noted in the unsuccessfully treated groups when compared to the successfully treated groups. Four studies found a threshold for posterior tilt ranging from 7° to 20° CONCLUSION: There is moderate evidence that patients with non-displaced FNF and greater tilt have an increased risk of unsuccessful outcomes following internal fixation. Older patients with a preoperative tilt of ≥20° might benefit from arthroplasty surgery, although studies assessing the optimal threshold are needed.

Detection of vascularity of femoral head using sub-millimeter resolution steady-state magnetic resonance angiography-initial experience

OBJECTIVE

The purpose of this study was to use the steady-state (SS) magnetic resonance angiography (MRA) with a sub-millimeter resolution to detect the arteries supplying to the femoral head (FH).

MATERIALS AND METHOD

SS MRA scanning of hips was performed bilaterally in 15 healthy volunteers. A blood pool contrast agent was used. The scanning protocol included a 0.8-mm³ isotropic T1-fast field echo sequence with spectral fat suppression technique. Two highly qualified radiologists independently evaluated the medial circumflex femoral artery (MCFA), the lateral circumflex femoral artery (LCFA), and the three retinacular arteries including superior retinacular artery (SRA), inferior retinacular artery (IRA), and anterior retinacular artery (ARA). The intraosseous branches of the three retinacular arteries were also evaluated. An orthopaedic surgeon was consulted in case of disagreement. Observation by the two radiologists and support from the orthopaedic surgeon served as the end result. Agreement between the two observer radiologists was evaluated.

RESULTS

Interobserver agreement between the two radiologists was found to be substantial to perfect. Of the 30 hips, the LCFA and MCFA were detected in all hips; the SRA and IRA were detected in most hips (100%, 90%), and the ARA was detected in 13 hips (43%). The intraosseous branches of SRA and IRA were detected in 30 and 22 hips (100%, 73%), respectively, while the intraosseous branches of ARA were detected in 11 hips (37%).

CONCLUSION

The main arteries supplying the FH can be detected by the SS MRA, making it a novel method to detect the vascularity of FH.

The effects of dual plating on the vascularity of the distal femur

AIMS

Dual plating of distal femoral fractures with medial and lateral implants has been performed to improve construct mechanics and alignment, in cases where isolated lateral plating would be insufficient. This may potentially compromise vascularity, paradoxically impairing healing. This study investigates effects of single versus dual plating on distal femoral vascularity.

METHODS

A total of eight cadaveric lower limb pairs were arbitrarily assigned to either 1) isolated lateral plating, or 2) lateral and medial plating of the distal femur, with four specimens per group. Contralateral limbs served as matched controls. Pre- and post-contrast MRI was performed to quantify signal intensity enhancement in the distal femur. Further evaluation of intraosseous vascularity was done with barium sulphate infusion with CT scan imaging. Specimens were then injected with latex medium and dissection was completed to assess extraosseous vasculature.

RESULTS

Quantitative MRI revealed a mean reduction of 21.2% (SD 1.3%) of arterial contribution in the lateral plating group and 25.4% (SD 3.2%) in the dual plating group (p = 0.051); representing a mean decrease in arterial contribution of 4.2%. The only significant difference found between both experimental groups was regionally, at the lateral aspect of the distal femur with a mean drop in arterial contribution in the lateral plating group of 18.9% (SD 2.6%) versus 24.0% (SD 3.2%) in the dual plating group (p = 0.048), representing a mean decrease in arterial contribution of 5.1%. Gross dissection revealed complete destruction of periosteal vessels underneath either medial or lateral plates in both groups. The network of genicular branches contributing to the posterior and distal femoral condyles was preserved in all specimens. A medial vascular pedicle was found dividing from the superficial femoral artery at a mean 12.7 cm (SD 1.7) proximal to the medial epicondyle and was undisrupted in the dual plating group.

CONCLUSION

Lateral locking-plate application resulted in mean 21.2% reduction in distal femur vascularity. Addition of medial plates did not further markedly decrease vascularity. As such, the majority of the vascular insult occurred with lateral plating alone. Supplemental medially based fixation did not lead to marked devascularization of the distal femur, and should therefore be considered in the setting of comminution and poor bone stock in distal femoral fractures. Further clinical research is required to confirm the results of this study. Cite this article: Bone Joint J 2020;102-B(4):530-538.

Femoral Head Vascularity: Implications Following Trauma and Surgery About the Hip

Traumatic injury and surgical intervention about the hip joint place the arterial supply to the femoral head (FH) at risk. Compromised perfusion may lead to FH ischemia, cell death, and osteonecrosis. Progression to FH collapse may lead to pain, functional impairment, and decreased quality of life, especially in younger patients. This review describes the arterial supply to the FH, analyzes the impact of femoral neck fractures on FH vascularity, and explores the vascular implications of various surgical interventions about the hip, offering specific techniques to minimize iatrogenic damage to the vessels supplying the FH. [Orthopedics. 2019; 42(5):250-257.].

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.

Vascular Anatomy of the Medial Femoral Neck and Implications for Surface Plate Fixation

OBJECTIVES

To describe the inferior retinacular artery (IRA) as encountered from an anterior approach, to define its intraarticular position, and to define a safe zone for buttress plate fixation of femoral neck fractures.

METHODS

Thirty hips (15 fresh cadavers) were dissected through an anterior (Modified Smith-Petersen) approach after common femoral artery injection (India ink, blue latex). The origin of the IRA from the medial femoral circumflex artery and the course to its terminus were dissected. The IRA position relative to the femoral neck was described using a clock-face system: 12:00 cephalad, 3:00 anterior, 6:00 caudad, and 9:00 posterior.

RESULTS

The IRA originated from the medial femoral circumflex artery and traveled within the Weitbrecht ligament in all hips. The IRA positions were 7:00 (n = 13), 7:30 (n = 15), and 8:00 (n = 2). The IRA was 0:30 anterior to (n = 24) or at the same clock-face position (n = 6) as the lesser trochanter. The mean intraarticular length was 20.4 mm (range 11-65, SD 9.1), and the mean extraarticular length was 20.5 mm (range 12-31, SD 5.1).

CONCLUSIONS

The intraarticular course of the IRA lies within the Weitbrecht ligament between the femoral neck clock-face positions of 7:00 and 8:00. A medial buttress plate positioned at 6:00 along the femoral neck is anterior to the location of the IRA and does not endanger the blood supply of the femoral head. The improved understanding of the IRA course will facilitate preservation during intraarticular approaches to the femoral neck and head.

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.

Quantitative and Qualitative Assessment of the Relative Arterial Contributions to the Calcaneus

BACKGROUND

The purpose of this study was to quantitatively and qualitatively assess relative arterial contributions to the calcaneus.

METHOD

Fourteen cadaveric ankle pairs were used. In each specimen, the posterior tibial artery, peroneal artery, and anterior tibial artery were cannulated and used for contrast-enhanced magnetic resonance imaging (MRI) and computed tomography (CT). Quantitative MRI analysis of the pre- and postcontrast MRI scans facilitated assessment of relative arterial contributions. In addition, postcontrast MRIs were used to measure all perfused arterial entry points and scaled to a 3-dimensional calcaneus model. Contrast-enhanced CT imaging was assessed to further delineate the extraosseous arterial course. Two pairs underwent infusion of diluted BaSO₄ through a constant-pressure pump using extended infusion duration.

RESULTS

Quantitative MRI findings indicated the peroneal artery provided 52.6% of the calcaneal arterial supply, 31.6% from the posterior tibial artery, and 15.8% from the anterior tibial artery. The cortical entry points were found in fairly consistent patterns along calcaneal cortical surfaces. All specimens demonstrated intraosseous anastomoses between lateral and medial entry points at common locations.

CONCLUSIONS

The peroneal artery was found to provide the largest calcaneal arterial contribution, followed by the posterior tibial artery and anterior tibial artery. A rich anastomotic arterial network was found supplying the calcaneus.

CLINICAL RELEVANCE

This study provides quantitative and qualitative findings of the relative arterial contribution of the calcaneus. This knowledge can help expand our understanding of calcaneal vascularization, demonstrate the vascular impact of calcaneal fracture and surgery, and facilitate future research on the arterial anatomy of the calcaneal soft tissue envelope.

Quantitative Assessment of Femoral Head Perfusion Following Arthroscopic Femoral Osteochondroplasty: A Cadaveric Study

BACKGROUND

Disruption of the arterial supply to the femoral head, and subsequent development of femoral head osteonecrosis, is of serious concern with intracapsular hip procedures. However, the effect of arthroscopic femoral osteochondroplasty on femoral head perfusion is unknown. We aimed to quantify the effects of both standard and posterosuperior extension of arthroscopic femoral osteochondroplasty on femoral head vascularity. We hypothesized that extension of the superior resection zone posteriorly would negatively affect femoral head perfusion.

METHODS

In 12 cadaveric pelvic specimens, we cannulated the medial femoral circumflex artery (MFCA). One hip per pelvis was randomly selected to be in 1 of 2 experimental groups based on the superior extent of the osteochondroplasty: standard resection (resection anterior to the 12 o'clock [0° of 360°] position) or extended resection (resection extended posterior to the 12 o'clock position). Computed tomography (CT) scans were obtained prior to and following arthroscopic resection to delineate the resection margins. Gadolinium enhancement on magnetic resonance imaging (MRI) was quantified in the femoral head by volumetric analysis using custom software. A polyurethane compound was injected and gross dissection of the vasculature was performed.

RESULTS

Extension of the osteochondroplasty posteriorly (the extended-resection group), to a mean of 41.3° (range, 34° to 47°) posterior to the 12 o'clock position, decreased femoral head perfusion by a mean of 28% (range, 18% to 38%). The standard-resection group demonstrated a mean decrease in femoral head perfusion of 7% (range, 4% to 11%). Correlation analysis demonstrated a significant negative correlation (correlation coefficient, -0.877; p < 0.001; R = 0.747). For every 1° that the superior resection margin extended posteriorly, a corresponding 0.88% decrease in femoral head perfusion was found.

CONCLUSIONS

Femoral head perfusion is almost fully maintained with arthroscopic osteochondroplasty when the superior resection margin is anterior to the 12 o'clock position. Perfusion is also well maintained if the superior resection margin is extended no more than 10° posterior to 12 o'clock. Further posterior extension correlated with greater decreases in femoral head perfusion.

CLINICAL RELEVANCE

Our study provides previously unreported quantitative MRI data on femoral head perfusion following arthroscopic femoral osteochondroplasty for the treatment of cam-type femoroacetabular impingement.

Focal osteonecrosis in the femoral head following stable anatomic fixation of displaced femoral neck fractures

INTRODUCTION

Femoral head (FH) osteonecrosis (ON) and subsequent segmental collapse is a major concern following displaced femoral neck fractures (FNF). We aimed to quantify residual perfusion to the FH following FNF and evaluate the viability of the FH overtime after surgical fixation.

MATERIALS AND METHODS

Twenty-three patients with FNF underwent dynamic contrast-enhanced (DCE)-MRI to estimate bone perfusion in the FH, using the contralateral side as control. Following open anatomic reduction and a length/angle-stable fixation, a special MRI sequence evaluated the FH for ON changes over time at 3 and 12 months after surgery.

RESULTS

We found significant compromise of both arterial inflow [83.1%-initial area under the curve (IAUC) and 73.8%-peak) and venous outflow (243.2%-elimination rate (K _el)] in the FH of the fractured side. The supero-medial quadrant suffered the greatest decrease in arterial inflow with a significant decrease of 71.6% (IAUC) and 68.5% (peak). Post-operative MRI revealed a high rate (87%-20/23) of small ON segments within the FH, and all developed in the anterior aspect of the supero-medial quadrants. Fracture characteristics, including subcapital FNF, varus deformity, posterior roll-off ≥20° and Pauwel's angle of 30°-50° demonstrated a greater decrease in perfusion compared to contralateral controls.

CONCLUSION

FNF significantly impaired the vascular supply to the FH, resulting in high incidence of small ON segments in the supero-medial quadrant of the FH. However, maintained perfusion, probably through the inferior retinacular system, coupled with urgent open anatomic reduction and stable fixation resulted in excellent clinical and radiographic outcomes despite a high rate of small ON segments noted on MRI.

LEVEL OF EVIDENCE

Level I: Prognostic Investigation.

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.

Arterial Topographic Anatomy Near the Femoral Head-Neck Perforation with Surgical Relevance

BACKGROUND

Knowledge of the vascular supply of the femoral head is crucial for hip-preserving surgical procedures. The critical area for reshaping cam deformity is at the retinacular vessel penetration, an area with ill-defined topographic anatomy. We performed a cadaver study of the extension of the lateral retinaculum near the head-neck junction, distribution of the arterial vascular foramina, and initial intracapital course of these vessels.

METHODS

In 16 fresh proximal parts of the femur without head-neck deformities, the deep branch of the medial femoral circumflex artery was injected with gadolinium for magnetic resonance imaging (MRI) sequences to identify arterial structures.

RESULTS

We found a mean number of 4.5 arterial foramina, showing a predominance from 10 to 12 o'clock. The retinaculum extended 20 mm from 1 to 10 o'clock. The surface distance from the cartilage border to the vascular foramina under the synovial fold was 6.5 mm, and the depth from the same cartilage border to the initial intraosseous vessel pathways was 5.3 mm.

CONCLUSIONS

The data add further precision to the arterial topography at the retinacular foramina, an area that is crucial for the perfusion of the femoral head. It may overlap with the area of anterolateral cam deformity and plays a role in choosing the cuts for subcapital and intracapital osteotomies.

CLINICAL RELEVANCE

The information is taken from normal hips and may not be directly applicable to the deformed hip. Nevertheless, it is a prerequisite for a surgeon to understand the normal anatomy and use those boundaries to prevent mistakes during intra-articular joint-preserving hip surgical procedures.

The relative contribution of the medial and lateral femoral circumflex arteries to the vascularity of the head and neck of the femur: a quantitative MRI-based assessment

AIMS

We aimed to quantify the relative contributions of the medial femoral circumflex artery (MFCA) and lateral femoral circumflex artery (LFCA) to the arterial supply of the head and neck of the femur.

MATERIALS AND METHODS

We acquired ten cadaveric pelvises. In each of these, one hip was randomly assigned as experimental and the other as a matched control. The MFCA and LFCA were cannulated bilaterally. The hips were designated LFCA-experimental or MFCA-experimental and underwent quantitative MRI using a 2 mm slice thickness before and after injection of MRI-contrast diluted 3:1 with saline (15 ml Gd-DTPA) into either the LFCA or MFCA. The contralateral control hips had 15 ml of contrast solution injected into the root of each artery. Next, the MFCA and LFCA were injected with a mixture of polyurethane and barium sulfate (33%) and their extra-and intra-arterial course identified by CT imaging and dissection.

RESULTS

The MFCA made a greater contribution than the LFCA to the vascularity of the femoral head (MFCA 82%, LFCA 18%) and neck (MFCA 67%, LFCA 33%). However, the LFCA supplied 48% of the anteroinferior femoral neck overall.

CONCLUSION

This study clearly shows that the MFCA is the major arterial supply to the femoral head and neck. Despite this, the LFCA supplies almost half the anteroinferior aspect of the femoral neck. Cite this article: Bone Joint J 2016;98-B:1582-8.

Quantitative assessment of patellar vascularity following bone-patellar tendon-bone autograft harvest for ACL reconstruction

PURPOSE

Recent anatomic studies have suggested that the dominant arterial supply of the patella enters through the inferior pole. Based upon these findings, we hypothesized that bone-patellar tendon-bone graft harvest can significantly diminish patellar vascularity.

METHODS

Nine matched pair cadaveric knee specimens (mean age 47.4 years) were dissected and cannulated. A single knee was selected to undergo routine graft harvest, and the contralateral knee was left intact to serve as a control. Gadolinium was injected, and magnetic resonance imaging (MRI) signal enhancement was quantified to determine differences in uptake. Each matched pair was subsequently injected with a urethane polymer compound and dissected to correlate vessel disruption with MRI findings.

RESULTS

We identified two predominating patterns of vessel entry. In one pattern, the vessel entered the inferomedial aspect (five o'clock/right, seven o'clock/left) of the patella and was disrupted by graft harvest in 2/9 (22.2 %) pairs. In the second pattern, the vessel entered further medial (four o'clock/right, eight o'clock/left) and was not disrupted (7/9, 78.8 %). The mean decrease in gadolinium uptake following disruption of the predominant vessel measured 56.2 % (range 42.6-69.5 %) compared to an average decrease of 18.3 % (range 7.1-29.1 %) when the dominant arterial supply to the inferior pole remained intact (p < 0.04).

CONCLUSION

Medial entry of the predominant vessel precluded vessel disruption. Disruption of the dominant arterial supply can result in a significant decrease in patellar vascularity. Modification of graft harvest techniques and areas of surgical dissection should be explored to minimize vascular insult. Further correlation with clinical studies/outcomes is necessary to determine a potential association between vascular insult and anterior knee pain.

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

PURPOSE

Avascular necrosis (AVN) of the femoral head is a major complication after internal fixation of a femoral neck fracture and determines the functional prognosis. We investigated postoperative bone single-photon emission computed tomography/computed tomography (SPECT/CT) for assessing the risk of femoral head AVN.

METHODS

We retrospectively reviewed 53 consecutive patients who underwent bone SPECT/CT within 2 weeks of internal fixation of a femoral neck fracture and follow-up serial hip radiographs over at least 12 months.

RESULTS

Nine patients developed femoral head AVN. In 15 patients who showed normal uptake on immediate postoperative SPECT/CT, no AVN occurred, whereas 9 of 38 patients who showed cold defects of the femoral head later developed AVN. The negative predictive value of immediate postoperative SPECT/CT for AVN was 100 %, whereas the positive predictive value was 24 %. Among 38 patients with cold defects, 1 developed AVN 3 months postoperatively. A follow-up bone SPECT/CT was performed in the other 37 patients at 2-10 months postoperatively. The follow-up bone SPECT/CT revealed completely normalized femoral head uptake in 27, partially normalized uptake in 8, and persistent cold defects in 2 patients. AVN developed in 3.7 % (1/27), 62.5 % (5/8), and 100 % (2/2) of each group, respectively.

CONCLUSIONS

According to the time point of imaging, radiotracer uptake patterns of the femoral head on postoperative bone SPECT/CT indicate the risk of AVN after internal fixation of femoral neck fractures differently. Postoperative bone SPECT/CT may help orthopedic surgeons determine the appropriate follow-up of these patients.

A Vessel-Preserving Surgical Hip Dislocation Through a Modified Posterior Approach: Assessment of Femoral Head Vascularity Using Gadolinium-Enhanced MRI

BACKGROUND

Surgical hip dislocation allows circumferential access to the femoral head and acetabulum and is utilized in the treatment of intra-articular hip disorders. Surgical hip dislocation is currently performed with a trochanteric osteotomy that reliably preserves the femoral head arterial supply; however, trochanteric nonunion or painful hardware requiring removal may occur. In a cadaveric model, using gadolinium-enhanced magnetic resonance imaging (MRI) and gross dissection, we evaluated whether modifications to the posterior approach preserve the femoral head arterial supply after a posterior surgical hip dislocation.

METHODS

In eight fresh-frozen pelvic specimens, a surgical hip dislocation was performed through the posterolateral approach with modifications in the tenotomy of the short external rotators and a capsulotomy designed to preserve the medial femoral circumflex artery (MFCA). Modifications included tenotomies of the quadratus femoris, conjoined tendon of the short external rotators, and obturator externus made 2.5 cm medial to their insertion on the greater trochanter and a T-type capsulotomy originating below the cut edge of the obturator externus tendon and continuing circumferentially along the acetabular rim. After hip dislocation, the MFCA was cannulated and MRI scans were acquired before and after gadolinium enhancement for evaluation of femoral head perfusion, with the contralateral hip, which was left intact, used as a control. Anatomic gross dissection was performed after the injection of polyurethane in the MFCA and confirmed MFCA vessel integrity.

RESULTS

Quantitative MRI showed that the operatively treated hip retained a mean perfusion (and standard deviation) of 95.6% ± 9.7% in the femoral head and 94.7% ± 21.5% in the femoral head-neck junction compared with the control hip (p = 0.66 and p = 0.85, respectively). Dissection after polyurethane injection confirmed that the superior retinacular and inferior retinacular arteries entering the femoral head were intact in all specimens.

CONCLUSIONS

In a cadaveric model using gadolinium-enhanced MRI, we found that standardized modifications to the posterior approach, specifically with regard to the location of the short external rotator tenotomy and capsulotomy, successfully preserved the femoral head arterial supply after posterior surgical hip dislocation.

CLINICAL RELEVANCE

While further research is necessary before these modifications can be recommended for widespread clinical use, the results of this study suggest the extracapsular vascular anatomy can be safely preserved during posterior surgical hip dislocation.

The origin of the medial circumflex femoral artery: a meta-analysis and proposal of a new classification system

Background and Objectives. The medial circumflex femoral artery (MCFA) is a common branch of the deep femoral artery (DFA) responsible for supplying the femoral head and the greater trochanteric fossa. The prevalence rates of MCFA origin, its branching patterns and its distance to the mid-inguinal point (MIP) vary significantly throughout the literature. The aim of this study was to determine the true prevalence of these characteristics and to study their associated anatomical and clinical relevance.

Methods. A search of the major electronic databases Pubmed, EMBASE, Scopus, ScienceDirect, Web of Science, SciELO, BIOSIS, and CNKI was performed to identify all articles reporting data on the origin of the MCFA, its branching patterns and its distance to the MIP. No data or language restriction was set. Additionally, an extensive search of the references of all relevant articles was performed. All data on origin, branching and distance to MIP was extracted and pooled into a meta-analysis using MetaXL v2.0.

Results. A total of 38 (36 cadaveric and 2 imaging) studies (n = 4,351 lower limbs) were included into the meta-analysis. The pooled prevalence of the MCFA originating from the DFA was 64.6% (95% CI [58.0–71.5]), while the pooled prevalence of the MCFA originating from the CFA was 32.2% (95% CI [25.9–39.1]). The CFA-derived MCFA was found to originate as a single branch in 81.1% (95% CI [70.1–91.7]) of cases with a mean pooled distance of 50.14 mm (95% CI [42.50–57.78]) from the MIP.

Conclusion. The MCFA’s variability must be taken into account by surgeons, especially during orthopedic interventions in the region of the hip to prevent iatrogenic injury to the circulation of the femoral head. Based on our analysis, we present a new proposed classification system for origin of the MCFA.

The terminal branches of the medial femoral circumflex artery: the arterial supply of the femoral head

This study investigates and defines the topographic anatomy of the medial femoral circumflex artery (MFCA) terminal branches supplying the femoral head (FH). Gross dissection of 14 fresh-frozen cadaveric hips was undertaken to determine the extra and intracapsular course of the MFCA's terminal branches. A constant branch arising from the transverse MFCA (inferior retinacular artery; IRA) penetrates the capsule at the level of the anteroinferior neck, then courses obliquely within the fibrous prolongation of the capsule wall (inferior retinacula of Weitbrecht), elevated from the neck, to the posteroinferior femoral head-neck junction. This vessel has a mean of five (three to nine) terminal branches, of which the majority penetrate posteriorly. Branches from the ascending MFCA entered the femoral capsular attachment posteriorly, running deep to the synovium, through the neck, and terminating in two branches. The deep MFCA penetrates the posterosuperior femoral capsular. Once intracapsular, it divides into a mean of six (four to nine) terminal branches running deep to the synovium, within the superior retinacula of Weitbrecht of which 80% are posterior. Our study defines the exact anatomical location of the vessels, arising from the MFCA and supplying the FH. The IRA is in an elevated position from the femoral neck and may be protected from injury during fracture of the femoral neck. We present vascular 'danger zones' that may help avoid iatrogenic vascular injury during surgical interventions about the hip.

BLEEDING OF FEMORAL HEAD DURING TOTAL HIP ARTHROPLASTY FOR OSTEOARTHROSIS

Objective: To evaluate the bleeding of the femoral head on hip osteoarthritis in patients who underwent total hip arthroplasty. Methods: One hundred and three hips affected by primary hip osteoarthritis were evaluated. After surgical dislocation, the femoral head was divided into four quadrants, and micro perforations were made in order to observe and assess the presence of bleeding, as early type (EB), late type (LB) or without bleeding (WB). Results: We observed early bleeding (EB) in the upper quadrant in 16 hips (15.5%), late bleeding in 14 hips (13.6%) and no bleeding (WB) in 73 hips (70.9%). The anterior quadrant showed EB in 24 hips (23.3%), LB in 7 hips (6.8%) and WB in 72 hips (69.9%). The lower quadrant presented EB in 40 hips (38.8%), LB 14 hips (13.6%) and WB in 49 hips (47.6%). The posterior quadrant showed EB in 39 hips (37.9%), LB 19 hips (18.4%) and WB in 45 hips (43.7%). Comparing BMI and gender, we found no association between these parameters

(p> 0.05). Conclusions: The inferior and posterior quadrant had the highest bleeding levels, following the path of the medial circumflex artery. Level of Evidence III, Therapeutic Study.

A novel surgical approach for the treatment of tumors in the lesser trochanter

The proximal femur is a common location for the development of primary benign bone tumors. However, there is currently no surgical technique designed specifically for treating tumors located in the lesser trochanter. In the present study, a novel procedure was developed for directly exposing the lesser trochanter for surgical intervention. This technique may be particularly suited to treating tumors that extend toward the lateral and anterior forward of the lesser trochanter. The new approach involved passing through the femoral triangle, separating the femoral nerve and femoral vessels (artery and vein) and resecting the tumor between the iliopsoas and pectineal muscles. The procedure was performed on six patients with various types of tumor, including one case with osteoid osteoma, one case with non-osteogenic fibroma, one case with osteoma, one case with liposarcoma and two cases of osteochondroma. The preliminary results indicated that the surgical durations were short (60-100 min), blood loss was minimal (30-200 ml) and that pain relief was achieved following surgery. Only one patient continued to experience mild pain, scoring 18 mm on a visual analog scale. The other patients were fully relieved of pain. Sensory dysfunction was experienced by one patient following surgery, with persistent numbness and paresthesias in the distribution of the femoral nerve. No cases of deep vein thrombosis, femur head necrosis, hip joint degeneration disease or local recurrence were identified in any patients during the follow-up period. In order to clarify the virtual tissue, such vessels, nerves and the available space in our approach area, we collected 20 cadaveric specimens and performed anatomical examinations in and around the formal triangle. The spaces between the femoral artery and femoral nerve were measured and analyzed, with the results demonstrating that a definite space existed. Therefore, the novel approach presented in the study may be useful in the resection of benign tumors and the preoperative palliative resection of malignant tumors. The technique may be particularly suited to tumors extending toward the lateral and anterior of the lesser trochanter.

The effect of antegrade femoral nailing on femoral head perfusion: a comparison of piriformis fossa and trochanteric entry points

INTRODUCTION

Piriformis fossa entry antegrade femoral nailing is a common method for stabilizing diaphyseal femur fractures. However, clinically significant complications such as chronic hip pain, hip abductor weakness, heterotopic ossification and femoral head osteonecrosis have been reported. A recent cadaveric study found that piriformis entry nailing damaged either the deep branch of the medial femoral circumflex artery (MFCA) or its distal superior retinacular artery branches in 100% of specimens and therefore recommended against its use. However, no study has quantitatively assessed the effect of different femoral entry points on femoral head perfusion.

MATERIALS AND METHODS

Twelve fresh-frozen cadaveric lower extremity specimens were randomly allocated to either piriformis fossa or trochanteric entry nailing using a 13-mm reamer. The contralateral hip served as an internal matched control. All specimens subsequently underwent gadolinium-enhanced fat-suppressed gradient-echo sequence MRI to assess femoral head perfusion. Gross dissection was also performed to assess MFCA integrity and distance to the opening reamer path.

RESULTS

MRI quantification analysis revealed near full femoral head perfusion with no significant difference between the piriformis and trochanteric starting points (95 vs. 97%, p = 0.94). There was no observed damage to the deep MFCA in either group. The mean distance from the reamer path to the deep MFCA was 3.2 mm in the piriformis group compared to 18.5 mm in the trochanteric group (p = 0.001). Additionally, there was a significantly greater number of mean terminal superior retinacular vessels damaged by the opening reamer in the piriformis cohort (1 vs. 0; p = 0.007).

CONCLUSIONS

No statistically significant difference in femoral head perfusion was found between the two groups. Therefore, we cannot recommend against the use of piriformis entry femoral nails. However, we caution against multiple errant starting point attempts and recommend meticulous soft tissue protection during the procedure.

Anatomical considerations in adult femoral neck fractures: how anatomy influences the treatment issues?

Femoral neck fractures in physiologically young adults are relatively uncommon. The reported incidence of avascular necrosis and nonunion rates remain relatively high despite the advancement in understanding and surgical management. Understanding the normal femoral neck anatomy and its relationship to presenting fracture pathology in young adults could help to lessen reported high complication rates to provide better clinical outcomes.

Treatment of neglected femoral neck fracture

Intra-capsular femoral neck fractures are seen commonly in elderly people following a low energy trauma. Femoral neck fracture has a devastating effect on the blood supply of the femoral head, which is directly proportional to the severity of trauma and displacement of the fracture. Various authors have described a wide array of options for treatment of neglected/nonunion (NU) femoral neck fracture. There is lack of consensus in general, regarding the best option. This Instructional course article is an analysis of available treatment options used for neglected femoral neck fracture in the literature and attempt to suggest treatment guides for neglected femoral neck fracture. We conducted the "Pubmed" search with the keywords "NU femoral neck fracture and/or neglected femoral neck fracture, muscle-pedicle bone graft in femoral neck fracture, fibular graft in femoral neck fracture and valgus osteotomy in femoral neck fracture." A total of 203 print articles were obtained as the search result. Thirty three articles were included in the analysis and were categorized into four subgroups based on treatment options. (a) treated by muscle-pedicle bone grafting (MPBG), (b) closed/open reduction internal fixation and fibular grafting (c) open reduction and internal fixation with valgus osteotomy, (d) miscellaneous procedures. The data was pooled from all groups for mean neglect, the type of study (prospective or retrospective), classification used, procedure performed, mean followup available, outcome, complications, and reoperation if any. The outcome of neglected femoral neck fracture depends on the duration of neglect, as the changes occurring in the fracture area and fracture fragments decides the need and type of biological stimulus required for fracture union. In stage I and stage II (Sandhu's staging) neglected femoral neck fracture osteosynthesis with open reduction and bone grafting with MPBG or Valgus Osteotomy achieves fracture union in almost 90% cases. However, in stage III with or without AVN, the results of osteosynthesis are poor and the choice of treatment is replacement arthroplasty (hemi or total).

Osteonecrosis of the femoral head with collapsed medial lesion

A 60-year-old female experienced the gradual onset of left hip pain without any triggering event. Radiographs showed vertical sclerosis in the center of the femoral head and the lesion inside the boundary demonstrated diffuse bony sclerosis. No collapse was observed at the weight-bearing portion on radiograph. However, computed tomography showed a subchondral collapse at the medial lesion. On T2-weighted magnetic resonance imaging, the necrotic lesion showed diffuse high-intensity signals that indicated a prominent repair process. Bone biopsy diagnosed osteonecrosis with associated prominent appositional bone and vascular granulation tissue.

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.

Regional analysis of femoral head perfusion following displaced fractures of the femoral neck

PURPOSE

To assess regional variations in the arterial and venous blood supply to the femoral head following displaced fracture of the femoral neck using dynamic contrast enhanced (DCE)-MRI quadrant analysis.

MATERIALS AND METHODS

A total of 27 subjects with displaced femoral neck fractures were enrolled in the study. Quadrant specific DCE-MRI perfusion analysis was performed on a 1.5 Tesla MRI scanner. Simultaneous imaging of control and displaced fractured hips was done for comparison.

RESULTS

Quadrant specific decreases were found in the arterial (A (0.52 versus 0.27; P = 5.7E-13), Akep (1.0/min(-1) versus 0.41/min(-1) ; P = 1.3E-9) and venous (kel (0.05/min(-1) versus -0.02/min(-1) ; P = 5.1E-5) supply to the femoral head between control and injured sides using a two-factor analysis of variance test. The fractional perfusion (initial area under the curve) in the supero/inferolateral quadrants was 49% min/54% min, in the supero/inferomedial quadrants was 43% min/46% min and for the total femoral head was 39% min on the fracture versus control sides.

CONCLUSION

Quadrant specific decreases in arterial and venous perfusion on the fracture side were observed when compared with control.

Assessment of femoral head and head-neck junction perfusion following surgical hip dislocation using gadolinium-enhanced magnetic resonance imaging: a cadaveric study

BACKGROUND

The purpose of the present study was to quantify perfusion to the femoral head and head-neck junction using gadolinium-enhanced magnetic resonance imaging following three surgical dislocations of the hip (trochanteric flip osteotomy, standard posterior approach, and modified posterior approach).

METHODS

The medial femoral circumflex artery was cannulated in fifty fresh-frozen cadaveric hips (twenty-five pelvic specimens). One hip on each pelvic specimen was randomly chosen to undergo one of the three surgical dislocations, and the contralateral hip was used as a control. Gadolinium enhancement on the magnetic resonance imaging scan was quantified in both the femoral head and head-neck junction by volumetric analysis using custom magnetic resonance imaging analysis software. A polyurethane compound was then injected, and gross dissection was performed to assess the extraosseous vasculature.

RESULTS

Magnetic resonance imaging quantification revealed that the trochanteric flip osteotomy group maintained almost full perfusion (mean, 96% for the femoral head and 98% for the head-neck junction). The standard posterior approach almost completely compromised perfusion (mean, 4% for the femoral head and 8% for the head-neck junction). Six specimens in the modified posterior approach group demonstrated partial perfusion (mean, 32% in the femoral head and 26% in the head-neck junction). Three specimens in the modified posterior approach group demonstrated almost full perfusion (mean, 96% in the femoral head and 97% in the head-neck junction). Gross dissection revealed that all specimens in the standard posterior approach group and seven of ten in the modified posterior approach group sustained disruption of the ascending branch of the medial femoral circumflex artery. All specimens in the standard posterior approach group demonstrated disruption of the inferior retinacular artery. The inferior retinacular artery remained intact in nine of ten specimens in the modified posterior approach group. One specimen in the modified posterior approach group that had disruption of both the ascending medial femoral circumflex artery and inferior retinacular artery demonstrated a substantial decrease in perfusion (7% in the femoral head and 5% in the head-neck junction).

CONCLUSIONS

The trochanteric flip osteotomy preserves the vascular supply to the femoral head and head-neck junction. The standard posterior approach disrupts the vascular supply and should be completely abandoned for surgical hip dislocation. Despite reduced enhancement, substantial perfusion of the femoral head and head-neck junction was present in the modified posterior approach group, likely because of the preservation of the inferior retinacular artery. The modified posterior approach produced variable results, indicating that improvement to the modified posterior approach is needed.

CLINICAL RELEVANCE

Our study provides previously unreported quantitative magnetic resonance imaging data on the perfusion to the femoral head and head-neck junction during common surgical approaches to the hip.

Increased post-operative ischemia in the femoral head found by microdialysis by the posterior surgical approach: a randomized clinical trial comparing surgical approaches in hip resurfacing arthroplasty

BACKGROUND

Hip resurfacing arthroplasty (HRA) is associated with osteonecrosis of the femoral head and femoral neck fracture, which may be caused by a decrease in the perfusion of the bone initiated at surgery. Several studies have demonstrated a decreased blood flow during surgery depending on the choice of surgical approach. We investigated the effect of the surgical approach on the blood flow and metabolism in the femoral head and neck in HRA by Laser Doppler flowmetry (LDF) and microdialysis.

MATERIALS AND METHODS

We conducted a randomized clinical trial on 38 patients, allocated to HRA by either the posterior (Post) or the antero-lateral (AntLat) surgical approach. LDF was performed during surgery and microdialysis after surgery to assess the concentration of the following metabolic markers: glucose, lactate, pyruvate and glycerol.

RESULTS

At 44-50 h after surgery, the mean lactate/pyruvate (L/P) and lactate/glucose (L/G) ratio was higher in the Post group compared to the AntLat group; L/P 195.3 (SEM 123) in Post and 128.5 (108.0) in AntLat; L/G 16.9 (6.5) in Post and 8.9 (3.7) in AntLat (p L/P = 0.02 and p L/G = 0.03). There was no difference in the LDF measurements (p = 0.74).

INTERPRETATION

HRA in the posterior approach results in increased post-operative ischemia in the femoral head and neck although during surgery, no difference in the blood flow was found. Still, the antero-lateral approach also causes considerable ischemia and other possible explanations, such as damage to the retinacular vessels during surgery or altered microcirculation because of heating from the cementation process, needs to be investigated.

Anatomic variations in femoral head circulation

The purpose of this cadaveric study was to clearly define the blood supply to the femoral head to help further reduce the incidence of iatrogenic avascular necrosis (AVN). Thirty-five hips of twenty-eight fresh cadavers were injected with colored silicone. Anterior and posterior dissection was performed to assess the vessels contributing to femoral head vascularity. The medial femoral circumflex artery (MFCA) was found to be the main blood supply to the hip in twenty-nine specimens; the inferior gluteal artery (IGA) was found to be the main blood supply in six. The MFCA consistently provided at least one smaller-calibre inferomedial retinacular artery. The foveal artery provided no significant vascular contribution in any specimen. The quantity and calibre of superior retinacular vessels demonstrated their dominance in head vascularity, although inferior retinacular arteries were consistently present. To reduce the risk of iatrogenic AVN, branches of both the IGA and MFCA traversing the interval between the quadratus femoris and piriformis muscles must be protected during surgery. Since all intracapsular vessels penetrated the capsule near its distal attachment, distal capsulotomy carries a significantly higher risk of AVN than proximal capsulotomy, particularly posterolaterally and inferomedially.

The distribution of vascular foramina at the femoral head/neck junction: implications for resurfacing arthroplasty

Reaming for resurfacing arthroplasty may endanger the blood supply at the head-neck junction, possibly predisposing to osteonecrosis and femoral neck fracture. The current study hypothesizes that reaming endangers femoral head vasculature. Vascular foramina were identified on 16 cadaveric femora and registered on computed tomographic models. Virtual reaming was performed after templating of resurfacing components. Almost half (41.8%) of foramina was located in the anterosuperior quadrant. Loss of foramina after reaming averaged 28% (P = .03), with up to 34.6% and 33.1% loss in the anterosuperior and posterosuperior quadrants, respectively. Reaming for resurfacing arthroplasty endangers a substantial number of vascular foramina. Notching or malpositioning of components may worsen injury to the vascular supply and could subsequently increase the risk of implant failure.

Imaging the vascularisation of the femoral head by CT angiography

The femoral head receives its blood supply primarily from the medial femoral circumflex artery, with its deep branch being the most important.

In a previous study, we performed classical anatomical dissections of 16 hips. We have extended our investigation with a radiological study, in which we aimed to visualise the arteries supplying the femoral head in healthy individuals. We analysed 55 CT angiographic images of the hip.

Using 64-row CT angiography, we identified three main arteries supplying the femoral head: the deep branch of the medial femoral circumflex artery and the posterior inferior nutrient artery originating from the medial femoral circumflex artery, and the piriformis branch of the inferior gluteal artery. CT angiography is a good method for visualisation of the arteries supplying the femoral head. The current radiological studies will provide information for further investigation of vascularity after traumatic dislocation of the hip, using CT angiography.

Magnetic resonance imaging of the postoperative hip

Magnetic resonance imaging (MRI) is ideally suited to imaging the patient with painful hip arthroplasty due to its superior soft tissue contrast, multiplanar capabilities, and lack of ionizing radiation. MRI is the most accurate imaging modality in the assessment of periprosthetic osteolysis and wear-induced synovitis, and can also assess regional tendons and neurovascular structures. This article discusses the technical aspects of MRI around metallic implants as well as the appearance of potential complications following hip arthroplasty, including osteolysis, wear-induced synovitis, infection, hemarthrosis, fracture, loosening, component displacement, heterotopic ossification, tendinopathy, and neurovascular impingement. The specific complication of metal hypersensitivity following metal-on-metal prostheses is reviewed.

DSA observation of hemodynamic response of femoral head with femoral neck fracture during traction: a pilot study

OBJECTIVE

To investigate the early influence of traction on blood supply to the femur head after femoral neck fractures using digital subtraction angiography (DSA).

DESIGN

Prospective case series.

SETTING

University Level I trauma center.

PATIENTS

Nine patients who sustained a unilateral femoral neck fracture underwent selective femoral artery DSA within 2-23 days after their injury.

INTERVENTION

DSA of the medial and lateral circumflex femoral artery was performed for all 9 fractured hips before traction. Repeat DSA study of the femoral head circulation was performed after the addition of 3 kg of traction in 7 patients and 5 kg of traction in 6 patients. For comparison, DSA was also performed on the uninjured hip in 8 of the 9 patients.

MAIN OUTCOME MEASURE

Blood circulation of the femoral head was evaluated by observing morphology of the feeding arteries, perfusion volume, venous drainage, and the circulation time of the microvasculature.

RESULTS

Femoral neck fracture damaged the retinaculum artery and led to femoral head hemodynamic disorder in all 9 cases. Application of linear traction and repeat DSA decreased femoral head perfusion (faint arterial imaging and delayed venous display) in all patients' retinaculum arteries except the inferior branch compared with the pretraction imaging. These findings were more pronounced as the traction was increased from 3 to 5 kg. These findings were significant (P < 0.05).

CONCLUSIONS

Traction impairs blood perfusion to the femoral head. Blood flow in the retinacular arteries was reduced and venous drainage impeded. Traction may be one of the major causes of femoral head osteonecrosis after femoral neck fracture.

Anatomy of the medial femoral circumflex artery with respect to the vascularity of the femoral head

We performed a series of 16 anatomical dissections on Caucasian cadaver material to determine the surgical anatomy of the medial femoral circumflex artery (MFCA) and its anastomoses. These confirmed that the femoral head receives its blood supply primarily from the MFCA via a group of posterior superior nutrient arteries and the posterior inferior nutrient artery. In terms of anastomoses that may also contribute to the blood supply, the anastomosis with the inferior gluteal artery, via the piriformis branch, is the most important. These dissections provide a base of knowledge for further radiological studies on the vascularity of the normal femoral head and its vascularity after dislocation of the hip.

Quantitative assessment of the vascularity of the talus with gadolinium-enhanced magnetic resonance imaging

BACKGROUND

The purpose of this study was to quantify the various arterial contributions to the talus with use of magnetic resonance imaging (MRI).

METHODS

The arterial anatomy of the talus was studied in ten pairs of fresh-frozen cadaver limbs with use of gadolinium-enhanced MRI in addition to gross dissection following latex injection. MRI proved useful to confirm the presence of specific arterial branches in situ as well as to demonstrate the rich anastomosis network in and around the talus. We further examined the MRI studies to delineate the quantitative contribution of each of the three main arteries to the talus and to each quadrant of the talus (anteromedial [0], anterolateral [1], posterolateral [2], and posteromedial [3]).

RESULTS

The peroneal artery contributed 16.9% of the blood supply to the talus; the anterior tibial artery, 36.2%; and the posterior tibial artery, 47.0%. The contribution of the anterior tibial artery was greatest in quadrant 0, whereas the contribution of the posterior tibial artery was greatest in quadrants 1, 2, and 3. The peroneal artery did not make the greatest contribution in any quadrant.

CONCLUSIONS

In contrast to the findings in previous studies, we found that a substantial portion of the talar blood supply can enter posteriorly, which helps to explain why all talar neck fractures do not result in osteonecrosis. This finding, along with a very rich and redundant intraosseous pattern of anastomosis with contributions from all three vessels in each quadrant of the talus, may explain the low occurrence of osteonecrosis in association with talar neck fractures.

Noninvasive methods of measuring bone blood perfusion

Measurement of bone blood flow and perfusion characteristics in a noninvasive and serial manner would be advantageous in assessing revascularization after trauma and the possible risk of avascular necrosis. Many disease states, including osteoporosis, osteoarthritis, and bone neoplasms, result in disturbed bone perfusion. A causal link between bone perfusion and remodeling has shown its importance in sustained healing and regrowth following injury. Measurement of perfusion and permeability within the bone was performed with small and macromolecular contrast media, using dynamic contrast-enhanced magnetic resonance imaging in models of osteoarthritis and the femoral head. Bone blood flow and remodeling was estimated using (18)F-Fluoride positron emission tomography in fracture healing and osteoarthritis. Multimodality assessment of bone blood flow, permeability, and remodeling by using noninvasive imaging techniques may provide information essential in monitoring subsequent rates of healing and response to treatment as well as identifying candidates for additional therapeutic or surgical interventions.