Arterial and lymphatic supply of the knee integuments

The surgical approach to the anterior knee region carries a risk for postoperative integument infection and skin necrosis. A hypothesis is that surgical approach may damage integumental blood supply and additionally the lymphatic drainage from the foot and leg. The goal of this study was to describe the arteries and lymphatics directly affected by the antero-medial approach. Injection of the femoral a. was used to identify the femoral and popliteal aa. and their branches distributed to the integument of the anterior, medial and lateral aspects of the knee. Lymphatic injection into the plantar aspect of the first toe was also performed to identify the subdermal lymphatics traversing the area. Our results showed that most of the blood supply arises from the medial aspect of the knee integuments. However, subcutaneous arterial anastomoses provide a significant blood-supply when there is interruption of the medial vessels as seen in the medial surgical approach to the knee. Most of the lymphatic drainage originating from the foot crosses the knee region on the medial side, opposite or below the tibial tuberosity. Because the subdermal arterial network is well-developed, the medial approach for knee surgery does not endanger the anterior knee integuments as long as the lateral vascular supply is preserved. However, this approach may interrupt the lymphatic circulation, particularly in the case of an extended incision, which could explain postoperative edema and an increased rate of wound infection.

[The normal arteries of the femur and tibia (roentgenographic study)]

A roentgenographic study of the lower limbs arteries was made on 30 corpses of adults with no vascular pathology. A typical picture of the femur and crus arteries is described. Non-typical variants of the femoral artery radiographic image were seen in the postanterior projection as an imaginary intumescence and "trifurcation"; magus crus (tibial) and mala crus arteries can branch separately or in groups from the popliteal artery. Shadows of crus major brain arteries arranged in layers can be seen in the lateral projection.

Improved 2D time-of-flight angiography using a radial-line k-space acquisition

For flow imaging applications, radial-line k-space acquisition methods offer advantages over conventional 2DFT methods. Specifically, radial-line acquisition methods mitigate artifacts resulting from pulsatile flow while offering a potential reduction in scan times. In this paper, radial-line and 2DFT acquisitions are compared in a two-dimensional time-of-flight angiography sequence. The twisting radial-line (TwiRL) trajectory, a variant of 2D projection reconstruction, is used to represent the family of radial-line trajectories. In both phantom and in vivo studies, the TwiRL images demonstrate improved vessel depiction including a more uniform signal intensity and better delineation of the vasculature in comparison with images obtained via the 2DFT method.

[The peripheral circulation: ECG-gated magnetic resonance angiography]

This work was aimed at comparing magnetic resonance angiography (MRA) with and without ECG gating in the study of peripheral vessels. Ten volunteers, mean age 27.8 years, were examined with MRA of the femoral, popliteal and tibial segments. MRA was performed with a 1.5-T superconductive magnet, a transmit head coil and the TOF 2D technique. In all cases MRA was performed without cardiac gating and with different times of trigger delay (0, 20, 40, 70 and 200 ms). When comparing the different acquisitions, the number of vessels and the signal-to-noise (S/N) ratio were calculated. In the femoral segment, MRA without cardiac gating showed a mean of 7.7 vessels with 2.79 S/N ratio; MRA with 0 ms of trigger delay showed a mean of 13.1 vessels with 1.51 S/N ratio; MRA with 20 ms trigger delay showed a mean of 13.1 vessels with 1.52 S/N ratio; MRA with 40 ms trigger delay showed a mean of 13.2 vessels with 1.52 S/N ratio; MRA with 70 ms trigger delay showed a mean of 13.5 vessels with 1.50 S/N ratio; finally, MRA with 200 ms trigger delay showed a mean of 13.4 vessels with 1.50 S/N ratio. In the popliteal segment, the corresponding values were 6.4 vessels and 2.51 S/N ratio, 11.4 vessels with 1.54 S/N ratio, 11.3 vessels and 1.54 S/N ratio, 11.6 vessels and 1.52 S/N ratio, 11.8 vessels and 1.52 S/N ratio and, finally, 11.9 vessels and 1.52 S/N ratio. In the tibial segment, the corresponding values were 8.5 vessels and 1.84 S/N ratio, 14.4 vessels and 1.14 S/N ratio, 14.5 vessels and 1.17 S/N ratio, 14.5 vessels and 1.14 S/N ratio, 14.3 vessels and 1.17 S/N ratio and, finally, 14.5 vessels and 1.19 S/N ratio. To conclude, MRA with cardiac gating better visualized peripheral vessels whatever the trigger delay.

Anatomo-radiological study of the popliteal artery during knee flexion

We studied the morphological modifications of the popliteal artery during knee flexion. An anatomical, radiological study consisted of analysis of lateral arteriographs in different degrees in joint flexion followed by dissection to reveal the anatomical structures involved in the morphological adaptation of the popliteal artery to joint movement. In five non-atheromatous volunteers, 15 MRI angiographic sequences were done at the level of the knee in extension and flexion. The arteriographs and angio MRI showed that as joint flexion increased tortuosities appeared in the supra-articular upper popliteal artery while the middle and lower parts of the popliteal artery kept an even curve retracted from the posterior surface of the joint. Dissection seemed to show that this arterial adaptation occurred between two fixed points, one proximal (the adductor canal) and the other distal (the origin of the anterior tibial artery). Angio MRI seems to be a future route for the assessment of the limb vessels. The contrasting behaviour of the different segments of the popliteal artery allows us to understand better the pathophysiology of trauma and malpositions of the popliteal arterial trunk.

Nonlinear excitation profiles for three-dimensional inflow MR angiography

An RF excitation pulse for three-dimensional (3D) time-of-flight (TOF) MR angiography (MRA) with a nonlinear excitation profile was numerically calculated under the condition of uniform vessel signal across the excitation volume (slab), and the superiority of the optform pulse as compared with conventional RF pulses and TONE pulses was demonstrated. For this purpose we acquired MRA of the lower leg and of the carotid and vertebral arteries in a 30-year-old healthy volunteer. Although the flow velocity ranges in these two anatomic locations are different by about a factor of 10, in both cases the corresponding optform pulse provided the best signal homogeneity at the highest level.

Variations in the vascular pedicle of the rat gracilis muscle flap

The rat gracilis muscle is a reliable model for microsurgical research. Exploration of 364 inguinal regions and preparation of 80 free gracilis muscle flaps in Sprague-Dawley and Lewis rats revealed six distinct origins of the dominant arterial pedicle and four variations of the venous pedicle. Popliteal, external iliac, and truncus pudendoepigastricus associations are described for the first time in this study. The total incidence of atypical variation of arterial pedicle origin is 20.7 percent. The most common origin of muscular branch arteries are the superficial epigastric artery (53.3 percent), femoral artery (22.0 percent), popliteal artery (14.6 percent), and the external iliac arteries (5.5 percent). Muscular branch veins drain most frequently into the femoral vein (79.1 percent). Gracilis muscle flaps prepared from rats weighing 329 +/- 45 g weighed an average of 0.64 +/- 0.13 g, and their volume averaged 0.87 +/- 0.12 ml. Muscular branch artery and vein diameters (external) averaged 0.21 +/- 0.05 mm and 0.54 +/- 0.06 mm, respectively. This new anatomic information is essential for reproducible microsurgery research using the rat gracilis muscle.

Popliteal artery entrapment syndrome. Anatomic and embryologic bases, diagnostic and therapeutic considerations following a series of 15 cases with a review of the literature

We report 15 examples of popliteal artery entrapment syndrome observed in 11 patients. The anatomical causes were as follows: in one case, the popliteal artery presented an aberrant course medially to the medial head of the gastrocnemius muscle. In 5 cases, there was a small fibrous band linking the medial head of the gastrocnemius muscle to the lateral condyle and crossing behind the popliteal artery; in 5 cases this anomaly was also found in association with an abnormally high and/or internal insertion of the medial head of gastrocnemius muscle. In the last 4 cases, there was a muscular insertion anomaly associated with muscular hypertrophy causing arterial compression. Arteriography performed in the 11 patients showed evocative signs of the diagnosis in all cases where the artery was patent. Two popliteal arteries were occluded. CT scan and MRI examination of the popliteal fossa enabled us to define the muscular origin of the popliteal compression. All of the patients were operated upon; two received a reversed saphenous bypass and all of the others were treated by liberation of the popliteal artery and/or vein by a posterior approach. Follow-up in all patients at long term showed good prognosis. All of the patients were able to take up their previous physical activities without sequelae. Our review of the literature, which is based on 374 cases of popliteal artery entrapment observed in 280 patients, made it possible to define the frequency of the various anomalies observed, their symptoms and the different therapeutic possibilities. The multiple anatomical classifications as well as the arterial and muscular embryology are also described.

Danger to the popliteal artery in high tibial osteotomy

We report a case in which the popliteal artery was divided during upper tibial osteotomy performed with the knee in 90 degrees of flexion. This position is believed to allow it to fall safely back from the tibia, but we could find no published confirmation. We used duplex ultrasonography in ten healthy volunteers to measure the distance from the popliteal artery to the posterior surface of the tibia at various degrees of flexion of the knee. Our results showed that in 12 of 20 knees the popliteal artery was closer to the tibia in 90 degrees of knee flexion than in full extension. Surgeons performing upper tibial osteotomy should be aware that flexing the knee does not protect the popliteal artery from injury.

Blood supply of subcutaneous tissue in the leg and its clinical application

The vascular anatomy of the subcutaneous or adipose layer of the leg is described. The major arteries of the distal thigh and leg were injected with either a colored latex or an India ink and gelatin mixture to demonstrate the principal sources of blood supply to the skin and the superficial tissues of the leg. Microdissection and the technique of Spalteholz for dehydrating and clearing the tissues (rendering them transparent) facilitated the study of the direct and indirect arterial branches which form the three principal networks: the deep fascia, the subcutaneous or adipose layer, and the skin or the dermoepidermic layer. The results are of practical importance since the fascio-subcutaneous tissue layer can be used as a flap for covering soft tissue defects of the leg.

Popliteal vascular compression in a normal population

PURPOSE

Positional popliteal artery obstruction is believed to be an important factor contributing to popliteal artery entrapment syndromes. This study was undertaken to define the positional anatomy and physiologic condition of the vessels in the popliteal fossa in groups of highly trained and normally active young men and women. We postulate that at least some symptom-free individuals can occlude the popliteal artery with leg positioning.

METHODS

Seventy-two limbs were evaluated in 36 subjects. Symptom-free subjects were recruited in four groups: normally active men, normally active women, male competitive runners, and female competitive runners. All subjects underwent noninvasive testing that included resting segmental limb pressures and Doppler waveforms and color-flow duplex imaging with the leg in the neutral position and then with knee extension with active and passive dorsiflexion and plantar flexion of the foot. Subjects unable to occlude the popliteal artery with positioning were then exercised, and studies were repeated. Magnetic resonance imaging, with magnetic resonance angiography, was conducted on 14 subjects, with each leg studied in the neutral position and with active positioning.

RESULTS

Positional popliteal arterial occlusion occurred in 38 of 72 limbs (53%). No intergroup comparisons were statistically significant. The response of each leg was symmetric in 89% of subjects. No subject who could not occlude the popliteal artery at rest was able to do so with exercise. Magnetic resonance imaging disclosed normal anatomy in all subjects and showed the location of popliteal occlusion to be at the level of the soleal sling, with positional compression by the soleus muscle, the lateral head of the gastrocnemius, the plantaris, and popliteus muscles.

CONCLUSION

Popliteal arterial occlusion can be induced in 53% of subjects with simple leg positioning caused by myofascial compression. This must be considered when evaluating patients for intervention on the basis of physiologic testing of the popliteal vessels.

MR gradient echo imaging of intravascular blood oxygenation: T2* determination in the presence of flow

The T2* relaxation time of blood varies with its oxygen saturation. To evaluate the feasibility of imaging intravascular blood oxygenation in humans using a conventional 1.5T MR system, we have implemented a method to measure T2* of blood despite the presence of pulsatile flow. The method was tested in a) stationary and flow phantoms, b) blood samples at different levels of oxygen saturation, and c) a human hypoxia model. Our results demonstrate the ability of cardiac-triggered, flow compensated gradient echo imaging to obtain reproducible T2* measurements of flowing blood in vivo.

The surgical anatomy of the popliteal artery

The popliteal artery is a common recipient site for above or below knee bypass grafts. It is also frequently affected by penetrating and blunt trauma involving the lower extremity. Exposure of this artery is, therefore, often required in both emergent and elective vascular procedures. In close proximity to the artery, within the confines of the popliteal fossa, are the tibial nerve, common peroneal nerve, and the popliteal vein. An understanding of the normal anatomy and the important variations in the popliteal bifurcation patterns is essential. In this report, we have combined data from new cadaver dissections with prior anatomical data to describe the anatomy of the popliteal fossa and important vascular anomalies.

Three-dimensional steady-state MR angiography of the lower extremities

Volume steady-state black-blood magnetic resonance imaging was evaluated as a method for depicting lower extremity vasculature. In steady-state imaging, flow has low signal intensity because motion destroys the coherence of transverse magnetization. To optimize image contrast, computations and measurements were obtained for the three-dimensional (3D) GRASS (gradient-recalled acquisition in the steady state) and 3D SSFP (steady-state free precession) sequences and a range of TRs and flip angles to determine optimal vessel-muscle contrast. The best results were achieved with a 3D GRASS sequence with a TR msec/TE msec of 25/5 and a flip angle of 30 degrees. Coronal images of the femoral and popliteal vessels were obtained in healthy volunteers with various fields of view and voxel sizes. Inflow of unsaturated spins from outside the image region, yielding high signal intensity, could be a potential drawback in steady-state black-blood imaging; however, problems can be avoided by using coronal acquisitions and large fields of view. Steady-state black-blood imaging depicts vessels with high accuracy and is faster and free of flow artifacts.

Persistent sciatic artery. Case report

A case of a persistent sciatic artery in a 60-year-old Japanese man is reported. The right persistent sciatic artery (5 mm in diameter) was joined to the internal iliac artery proximally and to the popliteal artery distally. The terminal vessel of the femoral artery (3 mm in diameter) was connected to the sciatic artery at the popliteal fossa.

Magnetic resonance measurement of blood flow in peripheral vessels after acute exercise

Velocity-encoded Cine magnetic resonance imaging (MRI) was used to measure blood flow in the anterior tibial artery (AT), posterior tibial artery (PT), and popliteal artery of adult human subjects (mean age 29 yr) before and after 90 s of ankle dorsiflexion exercise. Before exercise, mean flow, peak systolic velocity, and end-diastolic velocity in AT were 8.1 +/- 1.6 (SE, n = 6) ml/min, 26.9 +/- 2.6 cm/s, and -0.6 +/- 0.4 cm/s, respectively. After exercise, mean flow and peak systolic velocity in AT increased by 19-fold and 3-fold, respectively, and end-diastolic velocity increased to 8.7 +/- 1.1 cm/s. Flow in popliteal artery above its bifurcation was similar to the sum of flows in AT and PT, both before and after exercise. Flow in AT declined exponentially after exercise with a mean half-time of 4 min. The results demonstrate the utility of MR phase-encoded flow-velocity measurements for physiological studies of peripheral vascular dynamics after exercise.

Microvascular transplant of the gastrocnemius muscle in rats

The rat gastrocnemius muscle can serve as a vascularized, innervated muscle transplant model. To establish the anatomic and technical details of this model, we performed ten gastrocnemius transplants and collected data on muscle weight, dimension, and vessel caliber from each muscle. The muscle, consisting of medial and lateral heads, is supplied by pairs of sural vessels averaging 0.2 mm in diameter. These vessels, however, can be taken in continuity with the femoral vessels (averaging 1.0-1.6 mm in diameter), which are used for transplantation. The muscles weighed an average of 2.8 g, and the average pedicle length was 24 mm. Eight of ten transplanted muscles were viable with intact circulation at 72 hr. The gastrocnemius transplant was technically reliable, and the muscle bulk and contour could allow biochemical and functional studies. Donor site morbidity limits this model to transplantation studies.

Gadolinium-enhanced magnitude contrast MR angiography of popliteal and tibial arteries

To evaluate the efficacy of gadopentetate dimeglumine in MR angiography of the lower extremities, a flow phantom, seven healthy volunteers, and seven patients with peripheral vascular disease were studied with a magnitude contrast (MC) technique. The combination of an MC rephase-dephase gradient-refocused-echo pulse sequence, a 40-cm-long transmit-receive coil, and intravenous administration of a bolus of gadopentetate dimeglumine improved MR angiographic quality in the phantom, volunteers, and patients. Gadolinium enhancement decreased deleterious saturation effects and improved images of the popliteal and tibioperoneal arteries in the volunteers and patients. However, in some cases, venous overlap, imaging artifacts, and suboptimal visualization of subtle lesions limited interpretation. The authors conclude that gadolinium enhancement combined with an MC subtraction pulse sequence appreciably improves MR angiography of lower extremity arteries.

Arteriographic study of the rabbit lower limb

The rabbit hind limb has been used extensively as an orthopaedic model in the investigation of fracture pathology and healing and the effects of vascular abnormalities. However, a detailed description of the normal arterial supply appears to be absent from the literature. A study of the entire arterial vasculature has been undertaken using a lead oxide injection technique developed for this and other orthopaedic studies. This technique has proved reliable and inexpensive, giving high-quality arteriography, which is easily interpreted. Accurate description of the arterial anatomy is possible without the need for repeated dissection. The rabbit lower limb shows some interesting variations in blood supply, particularly below the knee. The foot has three distinct patterns of blood supply, depending on the presence or absence of the peroneal artery and the degree of dominance of the dorsalis pedis artery. This arrangement has not previously been described and differs from the situation in other mammals. The arteriographic technique and the anatomical description have allowed the interpretation of changes occurring in the vasculature after injury in a fracture model.

The surgical approach to lateral meniscal repair

Peripheral lateral meniscal tears are amenable to meniscal repair. Rasp abrasion and fibrin clot deposition along with vascular access channels are advances that, one hopes will increase healing rates of meniscal repairs. A basic principle that is not emphasized in the literature is how to perform the surgical approach to the lateral meniscus for safe placement of a meniscal repair retractor. This article reviews the anatomical planes of which the surgeon must be cognizant to facilitate retractor placement.

Comparative copper coil-induced thrombogenicity of the internal mammary, left anterior descending coronary, and popliteal arteries in dogs

The internal mammary artery (IMA) is the graft of choice for coronary artery bypass surgery because of its resistance to atherosclerosis. Studies to elucidate the mechanism of this phenomenon have focused on vasoactive properties of the vessel wall; however, low thrombogenicity might also contribute to the protection of the IMA against atherosclerosis. To test this hypothesis, copper coils 3 mm long were introduced in 14 heparinized dogs into both the IMA and the left anterior descending coronary artery (LAD) (n = 7) or into both the IMA and the popliteal artery (POP) (n = 7). Arterial patency was monitored angiographically at 15-minute intervals for 4 hours. Occlusion occurred in all LADs and POPs and in 10 of the 14 IMAs. Spontaneous reflow after occlusion occurred in all IMAs and was followed by cyclic reocclusion and reflow in two animals. Short periods of reflow followed by reocclusion occurred in two of the seven LADs and three of the seven POPs. The patency status, categorized as persistent occlusion, reflow followed by reocclusion, reflow without reocclusion, or persistent patency, was significantly different between IMA and LAD (p less than 0.02) and between IMA and POP (p less than 0.04) but not between LAD and POP. Patent arteries at the end of the 4-hour period were observed in all of the 14 IMAs versus none of the seven LADs and two of the seven POPs (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

The osteocutaneous fibula flap: an anatomic study

Recent studies related to the fibula flap have disagreed regarding the anatomy of the cutaneous branches of the peroneal artery. To clarify this issue, various dissections of 35 injected fresh cadaver legs were done. Identifiable skin branches were found in 23 of 25 dissections. Skin branches from the proximal third of the peroneal artery always travelled an intramuscular course. Skin branches from the distal two-thirds of the peroneal artery were usually affixed to the posterior crural septum. Legs with peroneal artery skin branches had from three to seven branches (average: 4.7); each branch contributed to the fibular periosteal blood supply. The most reliably found skin branch was located within 2 cm of the fibula midpoint. These findings reinforce the fact that a large skin island supplied by branches of the peroneal artery can be harvested with the fibula flap, and that the most reliable cutaneous vessels are found in the lower two-thirds of the leg, run posterior to the fibula in the posterior crural septum, and are always associated with muscular side branches.

Popliteal and tibioperoneal arteries: feasibility of two-dimensional time-of-flight MR angiography and phase velocity mapping

To assess the feasibility of using magnetic resonance (MR) angiography and velocity-encoded cine MR imaging to evaluate morphology and function in the popliteal and tibioperoneal arteries, the profiles of blood flow velocity measured with velocity-encoded cine MR were compared with those measured with color-coded sonography. Two-dimensional time-of-flight MR angiography was performed in the popliteal and tibioperoneal arteries of 10 healthy subjects; velocity-encoded cine MR and color-coded sonography were performed above and below the trifurcation. The velocity waveforms acquired with velocity-encoded cine MR and color-coded sonography correlated well and showed a typical triphasic pattern. At peak systole in the popliteal artery, spatial maximum and spatial mean velocities measured with velocity-encoded cine MR were 42.29 cm/sec +/- 9.55 (standard deviation) and 27.7 cm/sec +/- 5.8, respectively; the peak velocity measured with color-coded sonography was 44.2 cm/sec +/- 12.3. It is concluded that use of both MR angiography and velocity-encoded cine MR should be considered for identification of arterial stenoses and assessment of the hemodynamic importance of peripheral vascular stenoses.