Genicular Artery Embolization: A Review of Essential Anatomic Considerations.

Genicular artery embolization is increasingly recognized as a safe and effective treatment option for symptomatic knee osteoarthritis and recurrent hemarthrosis after total knee arthroplasty. Genicular arteries are an essential contributor to vascular supply for the knee joint and demonstrate considerable variability. Familiarity with the anatomy and common variations is critical for preprocedural planning, accurate target selection, and minimizing adverse events in transarterial embolization procedures. This review aimed to provide a detailed discussion of the genicular artery anatomy that is relevant to interventional radiologists performing genicular artery embolization.

Classification of Genicular Artery Anatomic Variants Using Intraoperative Cone-Beam Computed Tomography.

PURPOSE: Genicular artery embolization (GAE) is a new treatment option for symptomatic knee osteoarthritis. Genicular arterial anatomy is complex with limited published reports. This study describes the genicular artery anatomy utilizing intraprocedural cone-beam computed tomography (CBCT) during GAE. MATERIALS AND METHODS: This retrospective single-center study was approved by the institutional review board. All patients who underwent GAE between May 2018 and April 2022 were reviewed. Patients with a technically adequate CBCT were included in the analysis. CBCTs were analyzed to determine the presence, course, and branching patterns of the genicular arteries. RESULTS: A total of 222 patients underwent GAE and 205 (92%) were included for analysis. The descending genicular artery was present in 197 (96%) CBCTs with two branches in 152 (77%). The superior medial genicular artery (SMGA) was present in 186 (91%), superior lateral genicular artery (SLGA) in 203 (99%), inferior medial genicular artery (IMGA) in 195 (95%), inferior lateral genicular artery (ILGA) in 196 (95%), and median genicular artery (MGA) in 200 (97%). Four unique branching patterns were identified: common origin of SLGA and MGA (115, 56%), unique origins (45, 22%), trifurcation of SLGA, SMGA, and MGA (32, 15.5%), and common origin of SMGA and MGA (12, 6%). The recurrent ascending tibial was identified in 156 (76%) CBCTs and superior patellar artery in 175 (85%) CBCTs. CONCLUSION: Genicular artery anatomy is complex with numerous common variants. CBCT is a powerful adjunct in GAE to rapidly identify target vessels for embolization and potentially decrease the risk of nontarget embolization.

Cadaveric Classification of the Genicular Arteries, with Implications for the Interventional Radiologist.

PURPOSE: To document and assess the genicular arterial variation in a large multicenter cadaveric sample and to generate an anatomical classification with implications for genicular artery embolization (GAE). MATERIALS AND METHODS: A total of 212 dissected donor body lower limbs from 3 medical school institutions were included. The descending genicular artery (DGA), superior lateral genicular artery, superior medial genicular artery, middle genicular artery, inferior lateral genicular artery, inferior medial genicular artery, and anterior tibial recurrent artery were identified for gross anatomical appearance, location of origin, diameter of vessels, and variation in branching patterns. RESULTS: A total of 198 DGAs, 204 popliteal-origin genicular arteries, and 183 anterior tibial recurrent arteries were adequately preserved and reviewed. Three types (A: 26%, B: 71%, and C: 5%) of DGA branching patterns were proposed along with 6 types (I: 28%, II: 22%, III: 15%, IV: 15%, V: 10%, and VI: 6%) of popliteal-origin genicular artery branching variants. Right versus left comparisons did not reveal clinically significant differences in the vessel distance (P = .30 to .82). CONCLUSIONS: Despite the large number of possible anatomical variations of the genicular arteries, 6 main patterns corresponded to >96% of the cases. The description and classification of the genicular arterial anatomy may provide useful information to the interventional radiologist and add to the technical nuances of GAE.

Magnetic resonance imaging study of safe needling depth and angulation for acupuncture at BL40.

OBJECTIVES: The objectives of this study were to identify the mean safe needling depth and angle at BL40 between subjects, taking into account variables including sex and body mass index (BMI). METHODS: One hundred and twenty-four participants who had undergone magnetic resonance imaging (MRI) examination of the knee region for clinical indications were included in this study. BL40 needling sites were localized by World Health Organization (WHO) standards and were measured by MRI. As much as 70% of the value of AN (from the needle insertion point to the popliteal artery) was considered to represent the safe depth, and angle alpha between the BL40 straight line and the AN line was regarded as the safe angle. RESULTS: Overall, mean safe depth regardless of BMI and sex was 18.51 ± 3.56 mm (95% confidence interval (CI), 17.88%-19.14%). Mean safe depth was 17.24 ± 3.14 mm in the low and normal BMI group, 18.76 ± 2.90 mm in the overweight group, and 22.01 ± 3.71 mm in the obese group. Thirteen patients (10.5%) had internal deviation of angle alpha (95% CI, 5.6%-15.3%), while 111 patients (89.5%) had external deviation (95% CI, 84.7%-94.4%). The mean internal and external deviations of angle alpha were 8.78° ± 2.92° (95% CI, 7.01°-10.55°) and 9.75° ± 3.46° (95% CI, 9.10°-10.41°), respectively. CONCLUSION: We would suggest that, when using a straight needle insertion at BL40, it is safe to advance a 25-mm needle approximately 12.5 mm, and 17.5 mm should be safe for patients with BMI greater than 28 kg/m2. Practitioners should decrease the depth of penetration when treating patients of low body weight or height.

Acute Surgical Management of Vascular Injuries in Hip and Knee Arthroplasties.

With an increasing number of total hip and knee arthroplasties being done at surgical centers and vascular surgeons often not immediately available in this setting, it is critical for orthopaedic surgeons to be comfortable with the acute surgical management of vascular injuries. Although they are fortunately uncommon in primary total hip and knee arthroplasties, damage to a major artery or vein can have potentially devastating consequences. Surgeons operating both in a hospital and an ambulatory surgical setting should be familiar with techniques to gain proximal control of massive bleeding because the principles can be helpful in primary and revision arthroplasties. In this study, we review the vascular anatomy around the hip and knee and the surgical management of these potentially catastrophic complications.

Management of Complications during Below-the-Knee Endovascular Treatment: A Technical Note.

We retrospectively reviewed the cases in which complications occurred during below-the-knee (BTK) endovascular treatments that were performed at our hospital from 2005 to 2014. Several interesting cases have been described herein. All the patients had diabetes and non-healing wounds on their feet and/or rest pain in their foot or leg, and therefore, endovascular treatment was performed for the BTK arteries of the affected lower extremity. The complications that occurred during the procedure were classified into six categories-vascular spasm, flow limiting dissection, perforation, broken guidewire, distal thromboembolism, and unusual puncture site bleeding. Each complication has its own solutions and management. We discuss these different classes of complications and describe how cases of each type were managed.

Low Rank and Sparse Decomposition of Ultrasound Color Flow Images for Suppressing Clutter in Real-Time.

In this work, a novel technique for real-time clutter rejection in ultrasound Color Flow Imaging (CFI) is proposed. Suppressing undesired clutter signal is important because clutter prohibits an unambiguous view of the vascular network. Although conventional eigen-based filters are potentially efficient in suppressing clutter signal, their performance is highly dependent on proper selection of a clutter to blood boundary which is done manually. Herein, we resolve this limitation by formulating the clutter suppression problem as a foreground-background separation problem to extract the moving blood component. To that end, we adapt the fast Robust Matrix Completion (fRMC) algorithm, and utilize the in-face extended Frank-Wolfe method to minimize the rank of the matrix of ultrasound frames. Our method automates the clutter suppression process, which is critical for clinical use. We name the method RAPID (Robust mAtrix decomPosition for suppressIng clutter in ultrasounD) since the automation step can substantially streamline clutter suppression. The technique is validated with simulation, flow phantom and two sets of in-vivo data. RAPID code as well as most of the data in this paper can be downloaded from RAPID.sonography.ai.

MR Features of Juxta-Articular Venous Malformations of the Knee to Predict the Clinical Outcome of Sclerotherapy.

PURPOSE: To analyze and correlate preinterventional magnetic resonance (MR) imaging findings with clinical symptoms after percutaneous sclerotherapy of venous malformations (VMs) adjacent to the knee. MATERIALS AND METHODS: Twenty-five patients (mean age, 24 y; range, 7-55 y; 11 female) with 26 VMs adjacent to the knee undergoing sclerotherapy (direct puncture, diagnostic angiography, sclerosant injection) were identified, and MR imaging findings were analyzed. The VM involved the synovium of the knee joint in 19 of 26 cases (76%). These lesions were associated with joint effusion (3 of 19; 16%), hemarthrosis (4 of 19; 21%), or synovial thickening (16 of 19; 84%). Follow-up ended 6-8 weeks after the first or second sclerotherapy session if complete pain relief was achieved or 3 months after the third sclerotherapy session. Treatment outcomes were categorized as symptom improvement (complete or partial pain relief) or poor response (unchanged or increased pain). RESULTS: Forty-nine percutaneous sclerotherapy sessions were performed. Despite the absence of signs of knee osteoarthritis, patients with a VM involving the synovium (8 of 14; 57%) showed a poor response to sclerotherapy (1 of 8 [13%] pain-free after 1 sclerotherapy session). Among patients with VMs with no associated joint alteration and no synovial involvement (6 of 14; 43%), 5 of 6 (83%) showed improvement of symptoms after 1 sclerotherapy session (P < .05). CONCLUSIONS: Juxta-articular VMs of the knee are frequently associated with hemarthrosis and synovial thickening. Patients with signs of osteoarthritis and synovial involvement of the VM on presclerotherapy MR imaging deserve special consideration, as these findings predict worse clinical symptoms after sclerotherapy.

Anatomical Study of the Descending Genicular Artery Chimeric Flaps.

Purpose: With increasing use of the chimeric flap of the descending genicular artery, the authors systematically investigated the anatomy of its branches in cadavers. Methods: Fifteen fresh cadaveric thighs were studied by anatomical dissection. The branches of the descending genicular arteries were skeletonized along their courses to the femoral arteries. Branches' lengths and diameters were measured to simulate the combined application of the skin, muscle, bone, osteochondral and osteocutaneous flaps with tendon enthesis. Results: The descending genicular artery was noted in 11 thighs, with an average diameter of 1.94 ± 0.36 mm and an average length of 10.69 ± 4.41 mm. In addition, the saphenous artery was noted in all 15 thighs, and the average diameter of the original part was 1.35 ± 0.18 mm. Branches arose from the saphenous artery to supply the skin above the knee, the anterior of tibia, the sartorius muscle and the pes anserinus. The average diameter of the osteoarticular artery was 1.80 ± 0.46 mm which divaricated into a periosteal branch to supply the bone above the medial femoral epicondyle and a few articular branches to supply the bone and the cartilage of the medial femoral condyle. Conclusions: This study systematically investigated the anatomy of the descending genicular artery and its branches. Based on the anatomical features of descending genicular artery, chimeric flap offers combination therapy with other tissue flaps. Besides, considering its long chimeric arm, chimeric flap could be used to repair not only local complex injuries but also defects in different locations. Clinical Relevance: The descending genicular artery chimeric flap is a clinical option for reconstructing compound tissue defects of limbs.

Knee extension with blood flow restriction: Impact of cuff pressure on hemodynamics.

INTRODUCTION: Blood flow restriction (BFR) exercise has emerged as a method of increasing muscle size and strength with low intensity resistance training. While the cuff pressures used during BFR are typically a percentage of resting arterial occlusion pressure (AOP), the impact these cuff pressures have on blood flow during lower body exercise is unknown. PURPOSE: To determine how various cuff pressures impact blood flow and tissue perfusion during exercise. METHODS: Eleven healthy male participants completed four sets of knee extension (30 reps per set at 30% max torque) with 0%, 60%, 80%, and 100% of arterial occlusion pressure (AOP) was applied to the proximal portion of the thigh. Femoral artery blood flow, tissue oxygenation, and central hemodynamics were continuously recorded before, during, and after exercise. Electromyography (EMG) amplitude was recorded from the vastus lateralis during exercise. RESULTS: Blood flow increased during exercise compared to rest across all cuff pressures (p < 0.001), however compared to 0%, the absolute blood flow was reduced by 34 ± 17%, 45 ± 22%, and 72 ± 19% for 60, 80, and 100% AOP, respectively. Furthermore, each cuff pressure resulted in similar relative changes in blood flow before, during, and after exercise. During exercise, tissue saturation index (TSI) decreased as cuff pressure increased (p ≤ 0.005) with the exception of 80 to 100% AOP. Deoxyhemoglobin increased (p ≤ 0.001) with cuff pressure. CONCLUSION: Our data indicate that while BFR knee extension elicits an absolute hyperemic response at cuff pressures up to 100% resting AOP, the relative reductions in blood flow are consistent across rest, exercise and recovery.

Pulmonary hypertension could be a risk for deep vein thrombosis in lower extremities after joint replacement surgery.

OBJECTIVE: A background of Pulmonary Hypertension (PH) indicates a progressive elevation of pulmonary vascular resistance, leading to overfilling, elevation of venous pressure, congestion in various organs, and edema in the venous system. This study aimed to investigate whether PH is a risk factor for deep vein thrombosis (DVT) of the lower extremities after hip and knee replacement surgery. METHODS: A total of 238 patients who received joint replacement of lower extremities in our department of orthopedics from January 2009 to January 2012 were examined by echocardiography and Color Doppler flow imaging (CDFI) of the lower extremities. Based on pulmonary artery pressure (PAP), the patients were divided into a normal PAP group (n=214) and PH group (n=24). All the patients were re-examined by CDFI during post-operative care. RESULTS: Among the 238 patients, 18 had DVT in the lower extremities after the operation. DVT total incidence rate was 7.56% (18/238). In the PH group, 11 patients had DVT (45.83%, 11/24), but in the normal PAP group, only 7 had DVT (3.27%, 7/214). The incidence of DVT was significantly lower in the normal PAP group than in the PH group (P<0.01). In addition, there was a positive correlation between PAP and the incidence of DVT. CONCLUSION: PH could be a high-risk factor for the occurrence of DVT in patient's lower extremities after joint replacement surgeries.

Noncontrast free-breathing respiratory self-navigated coronary artery cardiovascular magnetic resonance angiography at 3 T using lipid insensitive binomial off-resonant excitation (LIBRE).

BACKGROUND: Robust and homogeneous lipid suppression is mandatory for coronary artery cardiovascular magnetic resonance (CMR) imaging since the coronary arteries are commonly embedded in epicardial fat. However, effective large volume lipid suppression becomes more challenging when performing radial whole-heart coronary artery CMR for respiratory self-navigation and the problem may even be exacerbated at increasing magnetic field strengths. Incomplete fat suppression not only hinders a correct visualization of the coronary vessels and generates image artifacts, but may also affect advanced motion correction methods. The aim of this study was to evaluate a recently reported lipid insensitive CMR method when applied to a noncontrast self-navigated coronary artery CMR acquisitions at 3 T, and to compare it to more conventional fat suppression techniques. METHODS: Lipid insensitive binomial off resonant excitation (LIBRE) radiofrequency excitation pulses were included into a self-navigated 3D radial GRE coronary artery CMR sequence at 3 T. LIBRE was compared against a conventional CHESS fat saturation (FS) and a binomial 1-180°-1 water excitation (WE) pulse. First, fat suppression of all techniques was numerically characterized using Matlab and experimentally validated in phantoms and in legs of human volunteers. Subsequently, free-breathing self-navigated coronary artery CMR was performed using the LIBRE pulse as well as FS and WE in ten healthy subjects. Myocardial, arterial and chest fat signal-to-noise ratios (SNR), as well as coronary vessel conspicuity were quantitatively compared among those scans. RESULTS: The results obtained in the simulations were confirmed by the experimental validations as LIBRE enabled near complete fat suppression for 3D radial imaging in vitro and in vivo. For self-navigated whole-heart coronary artery CMR at 3 T, fat SNR was significantly attenuated using LIBRE compared with conventional FS. LIBRE increased the right coronary artery (RCA) vessel sharpness significantly (37 ± 9% (LIBRE) vs. 29 ± 8% (FS) and 30 ± 8% (WE), both p < 0.05) and led to a significant increase in the measured RCA vessel length to (83 ± 31 mm (LIBRE) vs. 56 ± 12 mm (FS) and 59 ± 27 (WE) p < 0.05). CONCLUSIONS: Applied to a respiratory self-navigated noncontrast 3D radial whole-heart sequence, LIBRE enables robust large volume fat suppression and significantly improves coronary artery image quality at 3 T compared to the use of conventional FS and WE.

Pulmonary hypertension could be a risk for deep vein thrombosis in lower extremities after joint replacement surgery

SUMMARY A background of Pulmonary Hypertension (PH) indicates a progressive elevation of pulmonary vascular resistance, leading to overfilling, elevation of venous pressure, congestion in various organs, and edema in the venous system. This study aimed to investigate whether PH is a risk factor for deep vein thrombosis (DVT) of the lower extremities after hip and knee replacement surgery. METHODS A total of 238 patients who received joint replacement of lower extremities in our department of orthopedics from January 2009 to January 2012 were examined by echocardiography and Color Doppler flow imaging (CDFI) of the lower extremities. Based on pulmonary artery pressure (PAP), the patients were divided into a normal PAP group (n=214) and PH group (n=24). All the patients were re-examined by CDFI during post-operative care. RESULTS Among the 238 patients, 18 had DVT in the lower extremities after the operation. DVT total incidence rate was 7.56% (18/238). In the PH group, 11 patients had DVT (45.83%, 11/24), but in the normal PAP group, only 7 had DVT (3.27%, 7/214). The incidence of DVT was significantly lower in the normal PAP group than in the PH group (P<0.01). In addition, there was a positive correlation between PAP and the incidence of DVT. CONCLUSION PH could be a high-risk factor for the occurrence of DVT in patient's lower extremities after joint replacement surgeries.

RESUMO OBJETIVO A hipertensão pulmonar (HP) indica elevação progressiva da resistência vascular pulmonar, levando ao excesso de enchimento, elevação da pressão venosa, congestão em vários órgãos e edema no sistema venoso. Este estudo teve como objetivo investigar se a HP é um fator de risco para trombose venosa profunda (TVP) das extremidades inferiores após cirurgia de prótese de quadril e joelho. MÉTODOS Um total de 238 pacientes que receberam a substituição da articulação das extremidades inferiores em nosso departamento de ortopedia de janeiro de 2009 a junho de 2012 foi examinado por ecocardiograma e fluxo de imagem Doppler colorido (CDFI) dos membros inferiores. De acordo com a pressão arterial pulmonar (PAP), os pacientes foram divididos em grupo PAP normal (n=214) e grupo PH (n=24). Todos os pacientes foram reexaminados por CDFI durante os cuidados pós-operatórios. RESULTADOS Entre os 238 pacientes, 18 pacientes tiveram TVP nas extremidades inferiores após a operação. A taxa de incidência total de TVP foi de 7,56% (18/238). No grupo PH, 11 pacientes tiveram TVP (45,83%, 11/24), mas no grupo PAP normal, apenas sete pacientes tiveram TVP (3,27%, 7/214). A incidência de TVP foi significativamente menor no grupo PAP normal do que no grupo PH (P<0,01). Além disso, houve uma correlação positiva entre a PAP e a incidência de TVP. CONCLUSÃO A HP poderia ser um fator de alto risco para a ocorrência de TVP nas extremidades inferiores do paciente após cirurgias de substituição articular.

Vascular coverage of the anterior knee region - an anatomical study.

Descriptions of vessel angiosomes or perforasomes throughout the human body are quite frequent, and led to the development of flaps nowadays commonly used to surgically cover skin and soft tissue defects. In these procedures, the surgeon requires a profound anatomical knowledge of the respective blood vessels and the extent of the perfused area to define the size of the graft. In the region of the knee joint, descriptions of flaps based on the superior lateral genicular artery and descending genicular artery are quite frequent. In contrast, information regarding other popliteal branches is scarce or non-existent. The aim of this study was to provide a concise and complete overview on the extent and variability of the perforator angiosomes of the femoral and popliteal arteries in the anterior knee region. Twenty lower extremities were dissected, the respective perforators identified and perfused with dye. All resulting angiosomes were marked and documented. A total of 84 angiosomes were identified in all specimens, with an average of 4.2 (3-6) angiosomes per specimen. The average size of the angiosomes was 97.04 ± 72.30 cm2 (8.61-360.41 cm2 ), their source vessels had an average diameter of 1.42 ± 0.54 mm (0.60-3.25 mm). The complex and highly variable distribution of perforator angiosomes of the anterior knee region and especially of its less frequently investigated distal part was demonstrated. Based on these results, the planning of existing perforator flaps in this region and the development of flaps including the inferior medial or inferior lateral genicular arteries may be facilitated.

Cutaneous angiosome of the chimeric SLGA perforator flap: Anatomical study and clinical considerations.

BACKGROUND: The superior lateral genicular artery (SLGA) is the basis for a chimeric perforator flap in the lateral knee region, which may include bone, cartilage, fascia, and/or skin. To the best of our knowledge, a detailed description of the corresponding perforator-based skin area is missing in the literature. The aim of this study was to describe the extent and possible variations of the cutaneous angiosome of the SLGA. METHODS: In an anatomical study on 21 fresh frozen lower limbs, the SLGA was injected with toluidine blue. The anatomy of the vessel and its perforators was explored, and the skin containing the cutaneous angiosome was harvested and photo-documented. Evaluation of the images was performed using ImageJ software. In addition, the versatility of the SLGA perforator flap is illustrated as both a pedicled local and a free tissue transfer. RESULTS: For each vessel, there were 1.75 ± 0.9 (range 1-3) perforators at an average position of 47.3 ±â€¯21.3 mm lateral to the superolateral patella and 42.5 ±â€¯18.7 mm proximal to the knee joint. The angiosome area was 222.8 ±â€¯57.6 cm2 with a length of 20.9 ±â€¯3.0 cm and a width of 15.4 ±â€¯3.0 cm. At the longitudinal axis of the highest perforator density, the proximal end and the distal end of perfusion averaged 13.4 ±â€¯4.1 cm proximal and 2.5 ±â€¯2.0 cm distal to the knee joint, respectively. CONCLUSION: Our results show that the SLGA supplies a constant angiosome over the anterolateral proximal knee joint. Its description and visualization will guide surgeons in preoperative planning and further extend the use of this versatile chimeric perforator flap.

Impact of Knee Scooter Flexion Position on Venous Flow Rate.

BACKGROUND:: The knee scooter is a commonly used mobility device in the setting of unilateral below-knee immobilization. The bent-knee posture has been shown to decrease venous flow in a seated position, but the knee scooter differs as the patient is weightbearing through the affected extremity. Our goal was to investigate the effects of knee scooter positioning on popliteal venous flow. METHODS:: Duplex ultrasonography was performed to obtain venous diameter and flow velocity of the popliteal vein on healthy subjects over the age of 18 without immobilization. Measurements were performed on the left knee of each subject while standing and with the same knee flexed on the knee scooter, by 2 physicians trained in ultrasound techniques. Mean velocity, peak velocity, vessel diameter, and volumetric flow rate were calculated and t tests were performed for each variable. A power analysis was performed, determining that 9 subjects would provide 80% power with an alpha of 0.05. A total of 13 subjects participated in the study. Mean age was 33 (range 20-56) years, with 6 females and 7 males. RESULTS:: Measurements of subjects while standing and on the knee scooter demonstrated a significant decrease in mean velocity (6.5 vs 3.2 cm/s, P < .01) and volumetric flow rate (227.8 vs 106.2 mL/min, P < .01) while subjects were using the scooter. Vessel diameter (0.82 vs 0.78 cm, P = .15) and peak velocities (19.8 vs 14.7 cm/s, P = .19) were not significantly different between standing and kneeling positions. CONCLUSION:: Our findings demonstrated a statistically significant decrease in volumetric flow rate in subjects using a knee scooter device with a flexed knee. Although venous stasis is a known risk factor for DVT, flow rate thresholds for increased thrombus formation are not well defined. The duration of scooter use, or flexed knee positioning, may have some effect on the degree of stasis. This finding should caution orthopedists to consider the risk attributed to the knee scooter as part of their overall patient assessment. LEVEL OF EVIDENCE:: Level II, therapeutic, comparative study.