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.

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.

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.

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.

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.

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.

Free Omental Flap for Tissue Defect Coverage after Resection of Complicated Venous Malformation in the Area of the Knee.

Venous malformations are the most common slow-flow vascular malformations; they are not prone to volume decrease over time, and invasive treatment is usually required. There are 2 main techniques to address the definitive therapy of these lesions, sclerotherapy and surgical excision, each with its own advantages and disadvantages. We report the case of a 56-year-old man who came to our attention with persistent pain after multiple unsuccessful attempts to treat a large venous malformation located in the area of the right knee. After radical excision of the painful lesion, we covered the resulting major tissue loss (20 cm × 15 cm) with a free omental flap. The arterial and venous anastomoses were on the region above the knee pedicles. The postoperative course was uneventful. A secondary skin grafting was performed. The patient is doing well at 1-year follow-up. The omental flap may be a bailout solution for tissue loss coverage in the knee area when the use of the common fascia-cutaneous or muscular flaps is not possible.

Embolization of the Geniculate Arteries Is an Effective Treatment of Recurrent Hemarthrosis Following Total Knee Arthroplasty That Can Be Safely Repeated.

BACKGROUND: Recurrent hemarthrosis is a late complication in up to 1.6% of patients following total knee arthroplasty (TKA). In the absence of intrinsic coagulopathy, one etiology is bleeding of hypertrophic vascular synovium. The aim of this study is to evaluate the clinical outcome of patients referred to our center for angiographic embolization of geniculate arteries for recurrent hemarthrosis following TKA. METHODS: We retrospectively studied a cohort of patients who were referred for geniculate artery embolization following TKA between August 2011 and September 2016. RESULTS: A total of 24 embolization procedures were performed on 14 patients. Seven (50%) of these 14 patients underwent one embolization procedure. Due to symptom recurrence, 4 patients underwent a repeated procedure and 3 patients a third procedure. All embolization procedures were technically successful at the time of the procedure. Two patients reported an inguinal hematoma that healed without further treatment. At follow-up of mean 26.8 months, clinical success was achieved in 12 of the 14 patients (86%). CONCLUSION: Embolization of the geniculate arteries in our study was a safe and effective treatment of recurrent spontaneous hemarthrosis following TKA. Although we have performed a substantial number of reinterventions, results of this study show that this procedure can be safely repeated without adverse events. Our results indicate that embolization could possibly be the treatment of choice when conservative measures fail and can be repeated in the event of recurrent or persistent symptoms.

Anatomical Features of the Descending Genicular Artery to Facilitate Surgical Exposure for the Subvastus Approach-A Cadaveric Study.

BACKGROUND: The purpose of this cadaveric study was to clarify the proximal limit for the subvastus approach (SVA) in total knee arthroplasty to decrease potential vascular injury. METHODS: Seventy embalmed knees underwent a modified SVA using a 14-cm oblique medial incision. Anatomical features of the descending genicular artery (DGA) were investigated with regard to variation, distance of the vessels from surgical landmarks, and sex differences. RESULTS: The DGA was identified in 62 knees (89%), while it was absent in 8 knees (11%); in the latter, the articular, saphenous, and muscular branches arose separately from the femoral artery. The mean distances from the tibial tuberosity and medial joint line to the origin of the DGA were 15.5 ± 1.6 cm and 12.6 ± 1.6 cm, respectively. Both distances were significantly longer in males than in females (P < .01, respectively). A strong positive correlation was found between the distance from the tibial tuberosity to the origin of the DGA and the distance from the medial joint line to the origin of the DGA (Spearman's correlation coefficient, R2 = 0.72, P < .01). A weak positive correlation was found between the distance from the tibial tuberosity to the origin of the DGA and lower leg length (R2 = 0.13, P < .01). No vascular injuries were observed in this surgical exposure. CONCLUSION: The DGA showed several variations and was absent 11% of the time. An oblique medial incision within 14 cm from the tibial tuberosity followed by arthrotomy is considered a safe zone for the SVA.

Upper and lower extremity reconstructive applications utilizing free flaps from the medial genicular arterial system: A systematic review.

BACKGROUND: Free flaps derived from the medial genicular artery (MGA) system, including the medial femoral condyle (MFC) and medial femoral trochlear (MFT) flaps, are potential reconstructive options to address upper and lower extremity bony pathology. Our primary aim was to comprehensively search the literature to describe the spectrum of pathology treated with these flaps, and to assess patient outcomes to improve our understanding of expected union and complication rates. METHODS: Following PRISMA guidelines, a systematic review using Pubmed and Embase databases with citation cross-referencing was performed to identify all original clinical articles characterizing MGA flap treatment of upper and lower extremity pathology. RESULTS: The initial search identified 173 articles which was narrowed down to 40 meeting inclusion criteria, representing a total of 248 cases: 174 and 74 in the upper and lower extremities, respectively. Sixteen distinct recipient sites were identified with union rates ranging from 66 to 100% (98.7% overall). The majority (83.9%) of patients had undergone prior failed surgery. Major complications (those with limb/flap loss or requiring unplanned reoperation) were more frequent for lower versus upper extremity applications (17.1% vs. 6.2%, respectively). Donor site femoral fracture or persistent knee dysfunction occurred in 0.8% and 0.4% of patients, respectively. CONCLUSIONS: MGA free flaps are a versatile option for upper and lower extremity osseous reconstruction, offering high rates of union with minimal complications for a complex patient population. This study furthers our understanding of patient outcomes following MGA flap reconstruction, which previously was limited to case reports and small case series.

Location of the Popliteal Artery in Knee Extension on Magnetic Resonance Imaging.

The goal of this study was to define the course of the popliteal artery (PA) and determine any variability among different patient demographics; by identifying risk factors for injury, surgeons can decrease patient morbidity and mortality. Ninety-four adult magnetic resonance imaging studies of the knee were reviewed. In extension, the artery is at most 7.87 mm posterior and 4.83 mm lateral to the midline below the tibial plateau. Proximally, the artery is more anterior and midline. With increasing body mass indexes, the artery is more posterior at any level. At the femur, 1 cm above the distal articular surface, the artery was more posterior in younger patients; 1 cm below the joint line, it was more posterior in elder patients. Attention should be given during total knee arthroplasty, revision surgery, lateral meniscal repair, posterior cruciate ligament reconstruction, high tibial osteotomy, and fixation of tibial tubercle fractures. Proximally, the PA is more anterior and midline, placing it at significant risk during these procedures. (Journal of Surgical Orthopaedic Advances 27(4):325-328, 2018).

Marked regional endothelial dysfunction in mottled skin area in patients with severe infections.

BACKGROUND: Mottling around the knee, reflecting a reduced skin blood flow, is predictive of mortality in patients with septic shock. However, the causative pathophysiology of mottling remains unknown. We hypothesized that the cutaneous hypoperfusion observed in the mottled area is related to regional endothelial dysfunction. METHODS: This was a prospective, observational study in a medical ICU in a tertiary teaching hospital. Consecutive adult patients with sepsis admitted to ICU were included. After resuscitation, endothelium-dependent vasodilation in the skin circulation was measured before and after iontophoresis of acetylcholine (Ach) in the forearm and the knee area. We analyzed the patterns of induced vasodilatation according to the presence or absence of mottling and vital status at 14 days. RESULTS: We evaluated 37 septic patients, including 11 without and 26 with septic shock. Overall 14-day mortality was 22%. Ten patients had mottling around the knee (10/37, 27%). In the knee area, the increased skin blood flow following iontophoresis of Ach was lower in patients with mottled skin as compared to patients without mottled skin (area under curve (AUC) 3280 (2643-6440) vs. 7980 (4233-19,707), both P < 0.05). In the forearm area, the increased skin blood flow following iontophoresis of Ach was similar in patients with and without mottled skin. Among patients with septic shock, the increased skin blood flow following iontophoresis of Ach in the knee area was significantly lower in non-survivors as compared to survivors at 14 days (AUC 3256 (2600-4426) vs. 7704 (4539-15,011), P < 0.01). In patients with septic shock, the increased skin blood flow in the forearm area following iontophoresis of Ach was similar in survivors and non-survivors at 14 days. CONCLUSION: Mottling is associated with regional endothelial dysfunction in patients with septic shock. Endothelial dysfunction in the knee skin area was more pronounced in non-survivors than in survivors.

Treatment of Isolated Below the Knee Deep Vein Thrombosis.

The natural history of isolated distal deep-vein thrombosis (IDDVT) is still uncertain, as well as the real clinical risks associated with the disease and the need for its diagnosis and treatment. While more and more IDDVTs are diagnosed in everyday clinical practice, their appropriate therapeutic management is, unfortunately, far from straightforward, and different recommendations on how patients with diagnosed IDDVT should be treated are present between expert professionals and even among international guidelines. The present article aims at briefly reviewing the issue of IDDVT therapy in general, particularly focusing on the different approaches to the treatment of the disease that have been suggested by recent guidelines, those that are currently adopted in clinical practice, and necessary future directions.

Low-Voltage, High-Pitch Computerized Tomography Angiography of the Infrarenal Aorta and Lower Extremity Vessels: Assessment of Radiation Dose, Image Quality With Hybrid Iterative Reconstruction, and Efficacy of Test Injection Using a Monitoring Scan at Knee Level.

OBJECTIVES: Our aim was to assess image quality and radiation dose of low-voltage high-pitch computed tomography angiography of the infrarenal aorta and lower extremities and evaluate the efficacy of test injection technique using a monitoring scan at knee level. METHODS: A total of 60 patients with suspected peripheral arterial disease were divided into 2 groups: group 1 (30 patients, 80 kVp, high pitch [3.2], and hybrid iterative reconstruction [sinogram-affirmed iterative reconstruction]) and group 2 (30 patients, 120 kVp, low pitch [1.0], and filtered back projection reconstruction). The test injection technique at knee level was used to determine the scan delay time in group 1. The image quality and radiation exposure were compared. RESULTS: There were significant differences between the 2 groups in mean (SD) arterial attenuation (80 vs 120 kVp: 507.78 [103.01] vs 317.54 [62.03] Hounsfield units, P < 0.001), mean (SD) signal-to-noise ratio (51.04 [20.29] vs 34.66 [9.94], P < 0.001), and contrast-to-noise ratio (44.83 [17.93] vs 28.26 [9.60], P < 0.001). No difference in subjective image quality was found between the 2 groups (all P > 0.05). The imaging time was significantly shorter in group 1 (2.70 [0.11] vs 14.65 [0.90s], P < 0.001). The mean (SD) effective dose was significantly lower in the 80 kVp group (0.76 [0.06] vs 4.29 [0.63] mSv, P < 0.001). CONCLUSIONS: The 80-kVp high-pitch computed tomography angiography of the lower limbs using sinogram-affirmed iterative reconstruction yields reduction of radiation exposure as well as obtains acceptable image quality if acquisition protocols are used in conjunction with the test injection technique using monitoring scan at knee level to determine the delay time.

Exercises with partial vascular occlusion in patients with knee osteoarthritis: a randomized clinical trial.

PURPOSE: The objective of this study was to evaluate whether women with knee osteoarthritis performing a rehabilitation programme consisting of low-load exercises combined with PVO exhibited the same results in changes in quadriceps strength, pain relief, and functional improvement when compared to women receiving a programme consisting of high-load exercises without PVO. METHODS: Thirty-four women (mean age, 61 years) with a diagnosis of knee osteoarthritis were randomly assigned to a conventional or occlusion group. The women in the conventional group (n = 17) performed a 6-week quadriceps strengthening and stretching programme using a load around 70 % of the 1-repetition maximum (RM). The women in the occlusion group (n = 17) performed the same programme, however, only using a load around 30 % of the 1-RM, while PVO was induced. The PVO was achieved using a pressure cuff applied to the upper third of the thigh and inflated to 200 mmHg during the quadriceps exercise. An 11-point Numerical Pain Rating Scale (NPRS), the Lequesne questionnaire, the Timed-Up and Go (TUG) test, and muscle strength measurement using a hand-held dynamometer were used as outcome measures at baseline (pretreatment) and at the end of the 6-week of treatment. Pain, using the NPRS, was also assessed when performing the quadriceps exercises during the exercise sessions. RESULTS: At baseline, demographic, strength, pain, and functional assessment data were similar between groups. Patients from both the conventional and occlusion groups had a higher level of function (Lequesne and TUG test), less pain (NPRS), and higher quadriceps strength at the 6-week evaluation when compared to baseline (all P < 0.05). However, the between-group analysis showed no differences for all outcomes variables at posttreatment (n.s.). Patients in the occlusion group experienced less anterior knee discomfort during the treatment sessions than those in the high-load exercise group (P < 0.05). CONCLUSION: A rehabilitation programme that combined PVO to low-load exercise resulted in similar benefits in pain, function, and quadriceps strength than a programme using high-load conventional exercise in patients with knee osteoarthritis. However, the use of PVO combined with low-load exercise resulted in less anterior knee pain during the training sessions. LEVEL OF EVIDENCE: I.

Soft Tissue Reconstruction and Flap Coverage for Revision Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty is a successful operation for treatment of arthritis. However, devastating wound complications and infections can compromise the knee joint, particularly in revision situations. METHODS: Soft tissue loss associated with poor wound healing and multiple operations can necessitate the need for reconstruction for wound closure and protection of the prosthesis. RESULTS: Coverage options range from simple closure methods to complex reconstruction, including delayed primary closure, healing by secondary intention, vacuum-assisted closure, skin grafting, local flap coverage, and distant microsurgical tissue transfer. CONCLUSION: Understanding the advantages and pitfalls of each reconstructive option helps to guide treatment and avoid repeated operations and potentially devastating consequences such as knee arthrodesis or amputation.

Knee MRI: Vascular Pathology.

OBJECTIVE: Patients who undergo knee MRI for presumed musculoskeletal disease can have unexpected vascular findings or pathology in the imaged field. Some vascular processes are limb threatening and affect treatment planning and patient outcome. CONCLUSION: Unexpected vascular findings on knee MRI can range from incidental to symptomatic and can include such processes as variant anatomy, aneurysm, traumatic injury, and neoplasm. The assessment for vascular pathology should be a key component of every radiologist's search pattern when evaluating knee MRI.