Normal tolerance limits for side-to-side differences in diameters of major lower limbs arteries of 228 healthy subjects

PURPOSE

To determine reference values and tolerance limits of between-side differences for the calibers of the common femoral artery (CFA), superficial femoral artery (SFA), popliteal artery (PA), dorsalis pedis artery (DPA), and posterior tibial artery (PTA).

MATERIALS AND METHODS

Calibers of arteries, defined as the largest distance between internal hyperechogenic lines of the intima-media complex of the arterial wall, were measured during the diastole phase determined from echo-tracking B mode ultrasound scanning and grey-scale ultrasound in 228 healthy volunteers aged 18-81 years (43.1 ± 16.7).

RESULTS

The mean, 95% confidence and tolerance limits covering 90% of population for left and right side of each artery were: CFA: 8.1 mm, 7.9-8.3 mm, 6.0-10.3 mm; 8.1 mm, 7.9-8.5 mm, 5.9-10.2 mm; SFA: 6.2 mm, 6.0-6.3 mm, 4.7-7.6 mm; 6.1 mm, 6.0-6.3 mm, 4.7-7.6 mm; PA: 6.1 mm, 6.0-6.2 mm, 4.6-7.6 mm; 6.1 mm, 5.9-6.2 mm, 4.5-7.6 mm; DPA: 2.0 mm, 1.9-2.0 mm, 1.2-2.7 mm; 2.0 mm, 1.9-2.0 mm, 1.2-2.8 mm; PTA: 2.1 mm, 2.0-2.1 mm, 1.4-2.8 mm; 2.1 mm, 2.1-2.2 mm, 1.4-2.8 mm, respectively. Tolerance limits for between-side differences and ratios were: CFA - 0.5-0.7 mm, 0.9-1.1; SFA - 0.5-0.6 mm, 0.9-1.1; PA - 0.5-0.5 mm, 0.9-1.1; DPA -0.4-0.4 mm, 0.8-1.2; PTA - 0.4-0.4 mm, 0.8-1.2. Regression analysis showed weight and age dependency of vessels diameters. There are no differences between men and woman in vessels size, except in DPA's, when body weight and age are taken into account in a regression analysis.

CONCLUSIONS

We estimated normal reference tolerance limits of side-to-side differences in diameters of lower limb arteries. The limits can inform an investigator what differences in diameters occur in healthy individuals, and hence can serve as cut-offs in diagnostic and screening strategies.

[Embryology, anatomy and rare pathologies of the popliteal artery: Peculiarities of surgical treatment]

Knowledge of anatomical variations of the division of the popliteal artery and specific lesions of the arterial segment involved is necessary for the surgeon, traumatologist-orthopaedist, vascular surgeon. The article contains a review of recent literature data on the prevalence of different variants of branching patterns of the arteries of the crus, also providing a detailed discussion of embryological development of the arterial system of the lower extremities, in many ways explaining the appearance of rare pathologies of the popliteal artery, such as for example popliteal artery entrapment syndrome. Particular attention is paid to cystic damage of the popliteal artery, describing currently known theories of the development of this rare pathology, this is accompanied by sharing own experience in surgical treatment of the patients involved. Awareness of anatomical variants and peculiarities of embryonic development contributes to decreasing the possibility of iatrogenic damage of the popliteal artery during orthopaedic operations and to appropriate decision-making as to the method of revascularization.

Collateral artery pathways of the femoral and popliteal artery

BACKGROUND

The role of collateral artery circulation in the lower limb is under debate but clinically relevant, particularly when using covered stents for occlusive disease. Covered stents seem to outperform nitinol stents in extensive disease, but collaterals could be essential in case of acute thrombosis. In the present study, we describe the collateral pathways of the deep and superficial femoral artery (DFA, SFA) and the popliteal artery (PA), observed in human cadavers.

METHODS

Ten fresh frozen cadaver legs were selected. The SFA and DFA were separately cannulated and injected with a different colored latex mixture simultaneously. After curing of the latex, the circulation was dissected thus visualizing the main arteries and their collateral vessels. The process was photographed and recorded, and collateral pathways were analyzed using a standardized vessel segmentation. The upper leg was divided in three regions, that is, the femoral triangle (F), the adductor canal (H), and the popliteal fossa (P) that, in turn, were split in three segments (1, 2, and 3, from proximal to distal).

RESULTS

Overall, 113 collateral vessels were found; 69 originated from the DFA, 34 from the SFA, and 10 from the PA. The majority of collaterals originating from the DFA terminated in the SFA (57%). Fifty-six of 113 collaterals (50%) ended in either the distal adductor channel (H3) or the proximal PA (P1). Another 28 collateral arteries (25%) had their origin in this segment (H3, P1) and mostly connected to the P2 and P3 segments. Forty-three collaterals of the DFA and H3 segment had a direct or indirect connection to below the knee muscles.

CONCLUSIONS

The majority of collaterals originate from the DFA, and the greater part of all collaterals has a connection with the H3-P1 segment. This observation may have clinical implications in the planning of endovascular procedures.

Location of the Neurovascular Bundle of the Knee during Flexed and Extended Position: An MRI Study

BACKGROUND

The popliteal vessels and nerve are the structures most at risk during surgery of the posterior knee compartment. Common procedures that could interfere with or otherwise affect these structures include synovectomy, meniscal repair, proximal tibial osteotomy, knee replacement and fixation around the knee joint. Magnetic resonance imaging (MRI) can be used to locate the neurovascular structures from the posterior bony landmark. MRI imaging is routinely studied in the extended knee, but surgery of the posterior knee compartment is most often performed with the knee in a flexed position.

OBJECTIVE

The aim of this study was to investigate the location of the posterior neurovascular bundle relative to the posterior aspect of the femur, tibia, and posterior cruciate ligament during fully extended knee position and 90-degree flexed knee position using MRI.

MATERIAL AND METHOD

MRI images of 26 knees were obtained from 25 patients. Ten left knees, 14 right knees, and 1 bilateral knees were obtained from 18 males and 7 females. Axial plane and sagittal plane studies were used to measure the shortest distance of the popliteal artery, popliteal vein, and tibial nerve to the posterior bony aspect of the knee and the posterior cruciate ligament using a digital ruler tool from the PACS X-ray system. Measurement was performed at joint line level, 1 cm above joint line level, and 1 cm below joint line level in the fully extended knee position and in the 90-degree flexed knee position. At the joint line level, the mediolateral distance of the popliteal artery, popliteal vein, and tibial nerve to the posterior cruciate ligament were also measured.

RESULTS

At 1 cm above joint line level, mean anteroposterior (AP) distance from the distal femoral condyle to the popliteal artery, popliteal vein, and tibial nerve was 1.83+3.35 mm, 6.44+4.55 mm and 10.29+4.41 mm for full knee extension, and 15.60+5.01 mm, 20.63+4.62 mm and 26.24+7.70 mm for 90-degree knee flexion, respectively (p<0.001). At joint line level, mean AP distance from the posterior tibial cortex to the popliteal artery, popliteal vein, and tibial nerve was 5.43+3.22 mm, 8.75+3.72 mm and 13.10+4.15 mm for full knee extension, and 11.64+5.48 mm, 17.59+6.53 mm and 21.52+10.67 mm for 90-degree knee flexion, respectively (p<0.001). At 1 cm below joint line level, mean AP distance from the posterior tibial cortex to the popliteal artery, popliteal vein, and tibial nerve was 1.98+1.95 mm, 4.26+2.74 mm and 8.66+3.85 mm for full knee extension, and 6.91+2.86 mm, 12.34+5.23 mm and 16.58+9.22 mm for 90-degree knee flexion, respectively (p<0.001). At joint line level, mean distance from the posterolateral border of the PCL to the popliteal artery, popliteal vein, and tibial nerve was 11.12+2.62 mm, 11.30+4.05 mm and 15.14+5.05 mm for full knee extension, and 19.89+5.67 mm, 23.87+6.96 mm and 29.41+10.72 mm for 90-degree knee flexion, respectively (p<0.001).

CONCLUSION

During 90-degree knee flexion, the neurovascular structures move posterolaterally, as compared to fully extended knee position at joint line level and 1 cm above and below joint line level. To prevent neurovascular injury during surgery, surgeons should avoid or be cautious during blind penetration of the midline joint capsule and 90 degree flexed knee position increases the distance of the neurovascular bundle away from the posterior bony aspect.

[THREE-DIMENSIONAL VISUALIZATION RECONSTRUCTION OF MEDIAL SURAL ARTERY PERFORATOR FLAP BASED ON DIGITAL TECHNOLOGY]

OBJECTIVE

To explore the feasibility of three-dimensional (3-D) visualization reconstruction of the medial sural artery perforator flap based on digital technology.

METHODS

A series of Dicom images were obtained from three healthy adult volunteers by dual source CT angiography. Then the Mimics software was used to construct the medial sural artery model and measure the indexes, including the starting position of medial sural artery, external diameters of vascular pedicle, the number of perforators, location perforated deep fascia, and the maximum pedicle length of perforators based on medial sural artery perforator flap.

RESULTS

The 3-D visualization reconstruction models were successfully finished with Mimics software, which can clearly display the distribution, travel, and perforating point. Thirteen perforators were found in 6 legs, which started at the popliteal artery with a mean external diameter of 2.3 mm (range, 1.9-2.7 mm). Each specimen had 1-3 perforators, which located at the site of 6.2-15.0 cm distal to popliteal crease and 2.5-4.2 cm from posterior midline. The maximum pedicle length of medial sural artery perforator flap was 10.2-13.8 cm (mean, 11.8 cm).

CONCLUSION

The 3-D visualization reconstruction models based on digital technology can provide dynamic visualization of the anatomy of the medial sural artery for individualized design of the medial sural artery perforator flap.

[Anatomic features of posterior septum of knee joint and its application in posterior trans-septal portal for arthroscopic surgery]

OBJECTIVE

To summarize the anatomic features of the posterior septum of the knee joint and its application in posterior trans-septal portal for arthroscopic surgery.

METHODS

The literature related to posterior septum of the knee joint and arthroscopic surgery was extensively reviewed and analyzed.

RESULTS

The posterior septum of the knee joint has more mechanoreceptors and blood vessels in the upper part, which are close to arteria popliteal at the tibial plateau level; the posterior compartment is divided into wider posteromedial and narrower posterolateral compartments. A safe arthroscopic trans-septal portal is established, in the knee flexion of 90 degrees, in a lateral-to-medial direction, and with an inserting location below the middle of posterior septum.

CONCLUSION

The establishment method of posterior trans-septal portal is not uniform and all the features of posterior septum should be considered to decrease the complications.

The anatomical basis of the medial sural artery perforator flaps

OBJECTIVES

To study the perforators of the medial sural artery and the possible size of their flap.

METHODS

The external iliac arteries often adult preserved cadavers (males and females) were injected with a mixture of red latex and lead oxide. The skin was reflected and the medial sural artery and its perforators were identified. The diameters and origins of perforators were measured from the central popliteal crease.

RESULTS

The medial sural artery originated from the popliteal artery in 70% and had its external diameter at a mean of 3 +/- 0.02 mm and was accompanied by two venae comitantes. The number of its perforators was at a mean of two perforators. Length of the pedicle of the medial sural artery perforator flap was at a mean of 18 +/- 0.03 cm. The largest of the perforator had an average external diameter of 0.9 mm. The perforators ramified the skin with branches of the artery accompanying the posterior cutaneous nerve and the perforating branches of the peroneal and the posterior tibial arteries. The possible size of the medial sural perforators flap was at an average 8.2 cm x 13.3 cm.

CONCLUSION

The medial sural artery perforator flap has at least one or two perforators with an average size of 8.2 cm x 13.3 cm. Elevation of the flap will not affect the vascularity of the gastrocnemius muscle.

[Anatomic study and clinical application of sural neuro-myocutaneous compound flap transposition]

OBJECTIVE

To investigate the anatomical study and clinical applications of sural neuron-myocutaneous flap transposition for repairing the special patients with soft tissue defect in foot and ankle.

METHODS

The branches, distributions and anastomoses of the vessels and nerves lie in superficial layer of the posterior crural region were observed on 30 sides of adult cadaver lower limb specimens perfused with red latex. Since February 2004, distally based sural neuron-myocutaneous flap was applied for repairing 7 cases of soft tissue defect in foot and ankle.

RESULTS

The nutrient vessels of sural nerve, small saphenous vein and posterior femoral cutaneous nerve anastomosed permanently with the musculocutaneous perforators of medial and lateral head of gastrocnemius. There were 2 - 3 anastomoses found respectively. The musculocutaneous perforators pierced the two heads of gastrocnemius muscle (1.8 +/- 0.5) cm medially and (3.7 +/- 0.9) cm laterally away from the groove of the muscle. The medial anastomoses more closed to the middle groove and their diameters were found larger than the lateral ones. In operation, we routinely observed the compound flap for 15 to 20 minutes and found actively errhysis on the muscle, so the fine blood circulation in the flap was demonstrated. All flap survived after operation and the cases were followed up 2 to 6 months with cured osteomyelitis and satisfied flap outline.

CONCLUSIONS

Distally based sural neuro-myocutaneous flap can live. The operative method is simple. The flap offers an excellent donor site for repairing the soft tissue defect in foot and ankle in special cases.

The femoral artery and its branches in the baboon Papio anubis

The aim of the research was to examine the anatomy of the arterial system in the inguinal region, hip and thigh of Papio anubis. No description of this was found in the available scientific literature, although, at the same time, the baboon is considered to be a good animal model in biomedical research. Macroscopic anatomical research was carried out on 20 hind limbs (10 cadavers: 9 male and 1 female) of adult Papio anubis and the results were then compared with the anatomy of the arterial hind limb systems of other apes as described in the literature. The circulatory system of the whole body was filled with coloured latex via the common carotid artery and internal jugular vein, and traditional methods were then used to prepare the vessels. The arterial system in the hind extremity of Papio anubis was recorded. The anatomical names of human arteries were used as well as the names of those of apes as applied in the literature. The femoral artery was the only artery supplying the hind limb of Papio anubis. It started under the inguinal ligament as a continuation of the external iliac artery. It went down and divided into the popliteal artery, which coursed in the popliteal fossa, and the saphenous artery, which passed on the medial side of the thigh and leg. The number of smaller branches and the way in which they issued from the larger arteries were documented. The external diameter and length of the hind limb arteries were measured. It was observed that the cutaneous branches of the femoral artery supplied the inguinal and genital regions and the abdominal wall, while the deep artery of the thigh was the main vessel of the hip and thigh.

A pulse sequence for rapid in vivo spin-locked MRI

PURPOSE

To develop a novel pulse sequence called spin-locked echo planar imaging (EPI), or (SLEPI), to perform rapid T1rho-weighted MRI.

MATERIALS AND METHODS

SLEPI images were used to calculate T1rho maps in two healthy volunteers imaged on a 1.5-T Sonata Siemens MRI scanner. The head and extremity coils were used for imaging the brain and blood in the popliteal artery, respectively.

RESULTS

SLEPI-measured T1rho was 83 msec and 103 msec in white (WM) and gray matter (GM), respectively, 584 msec in cerebrospinal fluid (CSF), and was similar to values obtained with the less time-efficient sequence based on a turbo spin-echo readout. T1rho was 183 msec in arterial blood at a spin-lock (SL) amplitude of 500 Hz.

CONCLUSION

We demonstrate the feasibility of the SLEPI pulse sequence to perform rapid T1rho MRI. The sequence produced images of higher quality than a gradient-echo EPI sequence for the same contrast evolution times. We also discuss applications and limitations of the pulse sequence.

Popliteal artery branching patterns—an angiographic study

AIM

To analyse the variations in branching patterns of the popliteal artery and infrapopliteal vessels using angiography.

MATERIALS AND METHODS

Femoral angiograms of 1037 lower limbs in 568 patients were examined to assess the popliteal artery branching pattern. Variations of the infrapopliteal vessels supplying the foot were assessed in 662 limbs from the same cohort of patients.

RESULTS

Nine hundred and forty-one (90.7%) limbs had the usual branching pattern with anterior tibial artery (AT) arising first followed by the tibial-peroneal trunk (TPT), which then gives rise to the posterior tibial (PT) and peroneal (PR) arteries. Variations in popliteal branching pattern were seen in 96 (9.3%) limbs. The commonest variation is high origin of the AT in 47 (4.5%) limbs or trifurcation of the popliteal artery in 33 (3.2%) limbs with AT, PT and PR arising together with no true TPT. The course of AT with high origin either anterior or posterior to popliteus was almost equal [25 (2.4%) or 22 (2.1%) limbs, respectively]. Eleven limbs (1.1%) had high origin of PT and two (0.2%) had a high origin of the PR. Six hundred and fifty-five (99%) limbs had normal infrapopliteal vessels. Seven (1%) had hypoplasia-aplasia of the infrapopliteal vessels. Five (0.8%) limbs had a hypoplastic PT with the remaining 2 (0.2%) having either a hypoplastic-aplastic AT or hypoplasia-aplasia of both AT and PT.

CONCLUSION

Variations in the branching of the popliteal artery occur in about 10% of patients. Knowledge of these variations is important because of the potential consequences for the management of peripheral vascular disease.

Digital-image analysis of the angiographic patterns of the popliteal artery in patients with aorto-iliac occlusive disease (Leriche syndrome)

Angiographic patterns of the popliteal artery are of great clinical relevance in vascular surgery below the knee. Using radiological, digital and statistical methods the variants and Luminal diameters of the popliteal artery branching in 46 men and 30 women with Lerich syndrome were studied. Statistical analysis did not reveal any gender or syntopic dimorphisms (P > or = 0.05). In subtype IA (87.5%) the anterior tibial artery and the short type of posterior tibioperoneal trunk were found. In subtype IB (2.63%) an arterial trifurcation was observed. In subtype IC (1.97%) the posterior tibial artery and the short type of anterior tibioperoneal trunk were seen. In two subtypes: IIA-1 (1.32%) and IIA-2 (0.66%) the anterior tibial artery and the long type of posterior tibioperoneal trunk were found. In subtype II B (5.92%) the long type of anterior tibioperoneal trunk and the posterior tibial artery were observed. The symmetry of the left and right poptiteal patterns was seen in two most frequent subtypes: I A (r1 = 0.80) and II B (r2 = 0.83). Either the anterior or posterior tibial artery had a smaller diameter than the coexisting tibioperoneal trunk (P<0.01). In a trifurcation the luminal diameters formed a decreasing sequence of the following arteries: anterior tibial, posterior tibial and peroneal. The angiometric analysis of luminal diameters showed the predominant vessel in each subtype: anterior tibioperoneal trunk (IC, IIB), posterior tibioperoneal trunk (IA, IIA-1, IIA-2) and anterior tibial artery (IB).

Proximity of the popliteal artery to the PCL during simulated knee arthroscopy: implications for establishing the posterior trans-septal portal

This study defines the sagittal distance from the posterior cruciate ligament (PCL) to the popliteal artery under simulated arthroscopic conditions. This information is relevant for posterior knee arthroscopy, particularly for the safe establishment of the posterior trans-septal portal. Measurements from the PCL to the popliteal artery were made on sagittal magnetic resonance images obtained in a previous study of 10 fresh-frozen cadaveric knees. The mean sagittal distance from the mid-PCL to the popliteal artery was 29.1 +/- 11 mm (range: 18-55 mm). The mean sagittal distance from the proximal PCL fovea to the popliteal artery was 9.7 +/- 5 mm (range: 3-16 mm). The results of this study provide the arthroscopist working in the posterior compartments of the knee with a more detailed knowledge of the anatomic relationship between the PCL and popliteal artery. This knowledge will help minimize the risk of iatrogenic vascular injury during arthroscopic knee surgery.

Anatomic localization of the popliteal artery at the level of the knee joint: a magnetic resonance imaging study

PURPOSE

The anatomic localization of the popliteal artery in the mediolateral plane at the level of the joint line was investigated on axial knee magnetic resonance imaging (MRI) scans to study anatomic variations.

METHODS

The transverse and central axes were described on axial MRI scans of 334 knees. The distance between the popliteal artery and central axis was measured; the course of the central axis bisected the posterior cruciate ligament in almost all of the cases. The differences in popliteal artery localization according to sex and side were analyzed.

RESULTS

Whereas popliteal artery localization was lateral to the central axis in 94.3% of cases, it was on the central axis in 5.7%. The popliteal artery localization was not seen on the medial side of the central axis. There was no significant effect of sex and side.

CONCLUSIONS

Arthroscopic surgeons performing posterior cruciate ligament reconstruction or interventions on the posterior horns of the menisci should bear in mind that the risk of arterial complication may be greater for cases having the popliteal artery on the central axis. In conclusion, preoperative evaluation of the popliteal artery with MR axial scans, especially in pericapsular arthroscopic procedures, may prevent popliteal artery injuries.

LEVEL OF EVIDENCE

Level III, diagnostic study of nonconsecutive patients.

Prevalence and surgical significance of a high-origin anterior tibial artery

PURPOSE

To assess the prevalence of proximal high-origin anterior tibial artery and its surgical significance.

METHODS

100 knees were prospectively studied using colour Doppler ultrasonography. No patient had a history of lower-limb arterial pathology or previous knee surgery. All ultrasound images were assessed by a single experienced vascular technician to eliminate inter-observer variability.

RESULTS

The mean age of the patients was 56 years (range, 21-96 years). Prevalence of the high-origin anterior tibial arterial pattern was 6%, greater than that reported by previous angiographic or cadaveric studies. In all patients with high-origin anterior tibial artery, the artery was in direct contact with the posterior cortex of the tibia.

CONCLUSION

This highlights the danger of using sharp instruments in knee procedures that involve extension of osteotomy to the posterior tibial cortex, particularly high-tibial osteotomy and total knee replacement. Knowledge of the anatomical variations in the branching of the popliteal artery is important because damage to its branches can be limb- or life-threatening.

Size of normal and aneurysmal popliteal arteries: A duplex ultrasound study

OBJECTIVE

To define diameter at three levels along the popliteal artery and its relation to the inflow arteries in the normal state and in popliteal aneurysms.

METHODS

The external diameter of the arteries was determined by duplex ultrasound scanning at the common femoral (CFA), superficial femoral artery (SFA), proximal popliteal artery (PPOP), mid-popliteal artery (MPOP), and distal popliteal artery (DPOP). Examinations were performed in 104 healthy men and 100 women. In addition, patients were screened for the presence of popliteal aneurysms (diameter >10 mm). Findings in healthy male subjects were compared with those with popliteal aneurysms.

RESULTS

Mean arterial diameters in normal men were larger than in women, but the SFA/CFA ratio was smaller in women (0.74 +/- 0.08 vs 0.78 +/- 0.09; P < .001) and the MPOP/SFA ratio was larger (0.98 +/- 0.11 vs 0.94 +/- 0.12; P = .001). In both genders, normal popliteal artery diameter was not uniform throughout its length, with PPOP and MPOP being nearly identical, and DPOP was smaller. MPOP diameter correlated most closely with SFA diameter (r = 0.51; P < .001) and less with height, weight and body surface area (r = 0.2 to 0.3) and was not associated with age or the presence of hypertension. In 27 men with 45 patent, fusiform popliteal aneurysms (10 to 44 mm) the site of maximal dilatation was in the region of the MPOP in 39 cases and near the PPOP in only 6 cases. The DPOP was never the largest segment and only in one case was it >10 mm. Arterial diameter in aneurysm patients was larger than normal at all levels but was greatest near the MPOP level (15.7 +/- 6.9). Popliteal-to-SFA diameter ratios were increased in the aneurysm group at all three levels but were greatest at the MPOP level (1.85 vs 0.94, P < .001). Comparing 15 popliteal aneurysms >20 mm with smaller ones, distal popliteal artery changed to the least extent but did increase in diameter (6.1 +/- 1.2 vs 7.0 +/- 1.4, P < .04). In larger aneurysms the MPOP/SFA ratio increased from 1.54 to 2.5 (P < .001).

CONCLUSION

The diameter of the normal popliteal artery is not uniform throughout its length. In popliteal aneurysms, the region of the MPOP is most commonly the largest diameter. The MPOP/SFA ratio is greater than normal in popliteal aneurysms and increases in larger aneurysms. DPOP does dilate but to a lesser extent then PPOP and MPOP, making endovascular repair anatomically feasible in most popliteal aneurysms.

Laterale Ischiadikusblockaden

In the present study we examined 41 volunteers using magnetic resonance imaging to obtain biometric data of the thigh used for a planned blockade of the sciatic nerve via the lateral approach. At a needle entry point 12 cm proximal to the gap of the knee joint at the posterior border of the M. vastus lateralis, the sciatic nerve lies on average at a depth of 5.2 cm (39% of the femoral diameter at this site) with an angle of 10.9 degrees to the horizontal in a dorsal direction. Here the popliteal artery lies on average at a depth of 6.4 cm (48% of the femoral diameter) with an angle of 4.7 degrees to the horizontal in a ventral direction. At the marked point in the middle between the gap of the knee joint and the trochanter major at the posterior border of the M. vastus lateralis, the sciatic nerve is at an average depth of 6.2 cm (40% of the femoral diameter at this site) with an angle of 8.2 degrees in a dorsal direction. At a marked point 5 cm distal of the trochanter major at the posterior border of the M. vastus lateralis, the sciatic nerve is at a depth of 9.1 cm at a dorsal angle of 15.5 degrees (49% of the femoral diameter). The lateral blockade of the sciatic nerve at different sites of the thigh is a technique which is easy to plan with the presented biometric data. The popliteal artery could be reached only at the distal puncture point using a deep puncture and an angle in the ventral direction.

Anatomical study of the cutaneous perforator arteries and vascularisation of the biceps femoris muscle

We present an anatomical study that describes the distribution of the cutaneous perforators (CP) of both heads of the biceps femoris muscle.

MATERIAL AND METHODS

In this study, we dissected 18 legs from nine cadavers. The study was centered on the biceps femoris muscle and musculocutaneous perforator arteries from both muscular heads. Only perforator arteries with comitant vein diameters of over 0.5 mm were selected. The vascular origin and length were also studied. In all cases, measurements were taken from the bicondyle line.

RESULTS

The measurements taken from the muscle bellies of the biceps gave the following results; for the long head 33.91 cm as medium length (SD = 2.70) and for the short head 23.85 cm as medium length (SD = 2.96). The total number of perforator arteries obtained from the two muscle bellies was 139, with the greatest percentage located in the lower half of the thigh. The majority follow an intramuscular route (80.48%) and less frequently they are septals (19.52%). The lengths of perforator arteries from its origin in the axial vessel of the muscle to the subcutaneous fat were, for the short head 5.01+/-1.33 (3.0-10.0), whereas the same measurement, in the long head was 4.54+/-1.36 (2.5-9.0). The principal vascular origin of the perforator arteries was the popliteal artery in both muscle bellies, whilst the second arterial vessel in importance was the first and second profunda perforator artery.

CONCLUSION

From the results obtained in our work, we can deduce that it is always possible to locate perforator arteries in both muscle bellies; most frequently they have intramuscular distribution and are located in the proximity of the vascular septum. Their most common origins are the popliteal artery and first and second profunda perforator artery. Finally, it is possible to design pedicle and free flaps, with less morbidity and more versatility than musculocutaneous flaps.

A safe zone for the passage of screws through the posterior tibial cortex in tibial tubercle transfer

In tibial tubercle transfer, surgery drills and screws can put the popliteal vessels at risk if the posterior cortex is breached. This complication can be devastating. We have looked at arteriograms of 50 knees and identified a safe zone through which an instrument can be passed with more confidence. In our study we found no vessels directly posterior to the supero-medial aspect of the proximal metaphysis in any knee. Whilst care must still be taken, this area will allow surgeons greater confidence to obtain a stronger bicortical hold with any fixation device.

The blood supply of the common peroneal nerve in the popliteal fossa

We investigated the blood supply of the common peroneal nerve. Dissection of 19 lower limbs, including six with intra-vascular injection of latex, allowed gross and microscopic measurements to be made of the blood supply of the common peroneal nerve in the popliteal fossa. This showed that a long segment of the nerve in the vicinity of the fibular neck contained only a few intraneural vessels of fine calibre. By contrast, the tibial nerve received an abundant supply from a constant series of vessels arising directly from the popliteal and posterior tibial arteries. The susceptibility of the common peroneal nerve to injury from a variety of causes and its lack of response to operative treatment may be explained by the tenuous nature of its intrinsic blood supply.

Vascularization of the peroneal muscles. Critical evaluation in fibular free flap harvesting

This anatomical study was carried out in order to discover the etiology of partial necrosis of the peroneus longus and brevis muscles after fibular osteocutaneous flap harvest. The vascular supply to the lateral compartment peroneal muscles was investigated in 10 fresh cadaveric lower limbs. The peroneal muscles are supplied by two principal sources arteries, the anterior tibial artery (ATA) and the peroneal artery (PA). The ATA is the dominant artery and supplies the proximal and middle thirds of these muscles. The PA is considered to be a supplementary vascular source and supplies the distal thirds of these muscles. After harvesting the PA in a fibular flap, regions of the peroneal muscles preoperatively vascularized by its branches become supplied through the anastomotic "choke" vessels between the ATA and the PA. Primary closure of the cutaneous defect increases the possibility of developing a pseudo-compartment syndrome with necrosis of the more precariously vascularized portions of the peroneal muscles. This complication is difficult to diagnosis early and the reason why we advocate that direct skin closure following composite harvest must be avoided. Moreover, conservation of the inferior and superior lateral branches of the ATA is imperative in order to preserve the peroneal muscles vascularization.

Undersampled elliptical centric view-order for improved spatial resolution in contrast-enhanced MR angiography

Although contrast-enhanced MR angiography (CE-MRA) has been successfully developed into a routine clinical imaging technique, there is still need for improved spatial resolution in a given acquisition time. Undersampled projection reconstruction (PR) techniques maintain spatial resolution with reduced scan times, and the elliptical centric (EC) view order provides high quality arterial phase images without venous contamination. In this work, we present a hybrid elliptical centric-projection reconstruction (EC-PR) technique to provide spatial resolution improvement over standard EC in a given time. The k-space sampling was performed by undersampling the periphery of the k(Y)-k(Z) phase encoding plane of an EC view order in a PR like manner. The sampled views were maintained on a rectilinear grid, and thus reconstructed by standard 3DFT. The non-sampled views were compensated either by zero-filling or performing a 2D homodyne reconstruction. Compared to a fully sampled k-space, the EC-PR sequence acquired in the same scan time provides a resolution improvement of about two, as shown by point spread function analysis and phantom experiments. The hypothesis that EC-PR provides improved resolution while retaining diagnostically adequate SNR was tested in 11 CE-MRA studies of the popliteal and carotid arteries and shown to be true (P < 0.03).

The persistence of the sciatic artery

The persistent sciatic artery (PSA) is a rare anatomical variant where the internal iliac artery and the axial artery of the embryo provide the major supply of the lower limb, the superficial femoral artery being usually poorly developed or absent. We describe an extremely large right PSA in a 79-year-old male cadaver during a medical gross anatomy course, with simultaneous existence of a hypoplastic superficial and deep femoral artery. The PSA, which was a continuation of the anterior division of the right internal iliac artery, entered the buttock through the greater sciatic foramen situated in the gluteal region laterally to the sciatic nerve and in the mid thigh medially to the same nerve, becoming in the popliteal fossa the popliteal artery. Neither the superficial nor the deep femoral artery had communication with the popliteal artery. Because the PSA in our study was the only blood supply to the lower limb, we present the embryologic origins and the clinical anatomy of this artery.

The popliteal artery, an unusual muscular artery with wall properties similar to the aorta: implications for susceptibility to aneurysm formation?

OBJECTIVE

The popliteal artery is, after the aorta, the most common site for aneurysm formation. Why the popliteal artery is more susceptible than other peripheral muscular arteries is unknown. An important factor may be differences in arterial wall composition as compared with other peripheral muscular arteries, which in turn affect wall properties. These are however unknown. We studied the mechanical wall properties of the popliteal artery in healthy subjects.

MATERIAL AND METHODS

An ultrasound echo-tracking system was used to measure pulsatile changes in popliteal diameter in 108 healthy subjects (56 female, 52 male; age range, 9-82 years). In combination with blood pressure, stiffness (beta), strain, cross-sectional artery wall compliance coefficient (CC), and distensibility coefficient (DC) were calculated. Intima-media thickness (IMT) was registered with a Philips P700 ultrasound scanner.

RESULTS

The popliteal diameter increased with age, and was larger in male subjects than in female subjects (P<.001). Fractional diameter change (strain) decreased with age (P<.001), and strain values were lower in male subjects than in female subjects (P<.01). Accordingly, stiffness increased with age (P<.001), with higher stiffness values in male subjects (P<.01). DC decreased with age (P<.001), with lower DC values in male subjects (P<.01). CC decreased with age, with no difference between genders (P<.001). IMT increased with age (P<.001), with higher IMT values in male subjects (P<.001). The increase in IMT did not affect distensibility.

CONCLUSION

The wall properties of the popliteal artery are affected by age and gender, not only with an increase in diameter, but also with an age-related decrease in distensibility, with male subjects having lower distensibility than in female subjects. This seems not to be the behavior of a true muscular artery, but of a central elastic artery, such as the aorta, and might have implications for susceptibility to arterial dilatation, as well as the association of aneurysm formation between the aorta and the popliteal artery.

CLINICAL RELEVANCE

The popliteal artery is, after the abdominal aorta, the most common location for aneurysm formation in the arterial system. Why it is more susceptible than other arteries is unknown. This study shows that the wall function of the popliteal artery differs from other peripheral arteries, and instead show striking similarities to the abdominal aorta, indicating that the functional arrangement of arterial wall components are similar in the two arteries. This may have implications for the susceptibility to aneurysm formation, as well as the association of dilating disease between the popliteal artery and the abdominal aorta.

Time-resolved 3D contrast-enhanced MRA of an extended FOV using continuous table motion

A method is presented for acquiring 3D time-resolved MR images of an extended (>100 cm) longitudinal field of view (FOV), as used for peripheral MR angiographic runoff studies. Previous techniques for long-FOV peripheral MRA have generally provided a single image (i.e., with no time resolution). The technique presented here generates a time series of 3D images of the FOV that lies within the homogeneous volume of the magnet. This is achieved by differential sampling of 3D k-space during continuous motion of the patient table. Each point in the object is interrogated in five consecutive 3D image sets generated at 2.5-s intervals. The method was tested experimentally in eight human subjects, and the leading edge of the bolus was observed in real time and maintained within the imaging FOV. The data revealed differential bolus velocities along the vasculature of the legs.

Contrast-enhanced MR angiography of the run-off vasculature: intraindividual comparison of gadobenate dimeglumine with gadopentetate dimeglumine

PURPOSE

To compare intraindividually gadobenate dimeglumine (Gd-BOPTA) with gadopentetate dimeglumine (Gd-DTPA) for multi-station MR Angiography of the run-off vessels.

MATERIALS AND METHODS

Twenty-one randomized healthy volunteers received either Gd-BOPTA or Gd-DTPA as a first injection and then the other agent as a second injection after a minimum interval of 6 days. Each agent was administered at a dose of 0.1 mmol/kg bodyweight followed by a 25-mL saline flush at a single constant flow rate of 0.8 mL/second. Images were acquired sequentially at the level of the pelvis, thigh, and calf using a fast three-dimensional (3D) gradient echo sequence. Source, subtracted source, maximum intensity projection (MIP), and subtracted MIP image sets from each examination were evaluated quantitatively and qualitatively on a segmental basis involving nine vascular segments.

RESULTS

Significantly (P < 0.05) higher signal-to-noise and contrast-to-noise ratios were noted for Gd-BOPTA compared to Gd-DTPA, with the more pronounced differences evident in the more distal vessels. Qualitative assessmentrevealed no differences in the abdominal vasculature, a preference for Gd-BOPTA in the pelvic vasculature, and markedly better performance for Gd-BOPTA in the femoral and tibial vasculature. Summation of individual diagnostic quality scores for each segment revealed a significantly (P = 0.0001) better performance for Gd-BOPTA compared to Gd-DTPA.

CONCLUSION

Greater vascular enhancement of the run-off vasculature is obtained after Gd-BOPTA, particularly in the smaller more distal vessels. Enhancement differences are not merely dose dependent, but may be due to different vascular enhancement characteristics of the agents.

Contrast-enhanced peripheral MR angiography at 3.0 Tesla: initial experience with a whole-body scanner in healthy volunteers

PURPOSE

To report preliminary experience with contrast-enhanced magnetic resonance angiography (CE-MRA) of the peripheral arteries on a 3.0 T whole-body scanner equipped with a prototype body coil.

MATERIALS AND METHODS

Four healthy volunteers were imaged on the 3.0 T system and, for comparative purposes, two of the subjects were also imaged on a commercially available 1.5 T whole-body system. To investigate field strength influence on objective image quality, signal-to-noise (SN) and contrast-to-noise (CN) ratios were calculated for named vessels from the infrarenal aorta to the ankles at both field strengths. Comparable imaging protocols were used at both field strengths. In addition, two reviewers, blinded for field strength, gave subjective image quality scores (three-point scale).

RESULTS

SN and CN ratios were approximately equal on both systems (variation < or =9%) for the iliac and proximal upper leg stations. For the popliteal and lower leg stations SN ratios were 36% and 97% higher, and CN ratios were 44% and 127% higher, at 3.0 T. Subjective image quality at 3.0 T was substantially better for the distal upper and lower legs.

CONCLUSION

Contrast-enhanced peripheral MRA is possible at 3.0 T when an imaging protocol similar to a current state-of-the-art 1.5 T protocol is used. Objective and subjective image quality at 3.0 T is comparable for the iliac and upper legs but better for the popliteal and lower leg arteries.

The effect of knee flexion on the popliteal artery and its surgical significance

Total knee replacement and high tibial osteotomy are common orthopaedic operations with low complication rates. Such surgery is in close proximity to the popliteal artery (PA), the behaviour of which during flexion of the knee is poorly understood. We used Duplex ultrasonography to determine the distance of the PA from the posterior tibial surface at 0 degrees and 90 degrees of flexion in 100 knees. When the knee was flexed the PA was closer to the posterior tibial surface at 1 to 1.5 cm below the joint line in 24% and at 1.5 to 2 cm below the joint line in 15%. There was a high branching anterior tibal artery in 6% of knees. We provide an anatomical account to help to explain our findings by using cadaver dissections, arteriography and static MRI studies.

Vascular risk associated with a posterior approach for posterior cruciate ligament reconstruction using the tibial inlay technique

This study evaluated the risk to the popliteal artery associated with the tibial inlay technique in posterior cruciate ligament (PCL) reconstruction. Barium was injected into the femoral arteries of eight fresh-frozen cadaveric knees and anteroposterior (AP) radiographs were obtained. Dissection of the fascia overlying the gastrocnemius muscle, identification of the interval between the medial head of the gastrocnemius and the semimembranosus, and lateral retraction of the medial head of the gastrocnemius (the Burks and Schaffer approach) was performed. Subsequently, a bicortical screw was placed from posterior to anterior through the tibia as is performed in the tibial inlay technique. A second AP radiograph was obtained. The distance from the center of the screw to the edge of the popliteal artery was measured using digital calipers. The closest any screw came to the popliteal artery was 18.1 mm, and the average distance was 21.1 mm (21.1 +/- 4.6 mm, range: 18.1-31.7 mm). When this distance was calculated as a percentage of the tibial plateau width, the smallest value was 19.2% (24% +/- 4.9%, range: 19.2%-35.1%). A posterior approach for a tibial inlay PCL reconstruction procedure appears safe with respect to the popliteal artery.

Transverse ligament of the knee in humans

The purpose of this study was to trace the histological structure of the transverse ligament of the knee and its relation to the inferior lateral genicular artery. Investigations were carried out on 20 lower limbs (10 males, and 10 females) from the Department of Anatomy. It was found that close to the attachment of the transverse ligament to the menisci, bundles of fibres pass in vertical, oblique and horizontal directions, occupying a wide area on the anterior margin of the menisci. These fibres intermingle with bundles of the fibrocartilage of the menisci. In the area of the lateral attachment the inferior lateral genicular artery passes anteriorly to the transverse ligament, giving off numerous branches to the ligament. The medial part of the transverse ligament presents a thick rounded structure, surrounded by loose connective tissue. The fibres are arranged irregularly in bundles running horizontally on a tortuous course and with single spindle-like cells with darkly stained nuclei. The cells are not found at the ends of the ligament. Numerous blood vessels are observed between the bundles of fibres and on the periphery of the ligament.

High-resolution gadolinium-enhanced 3D MRA of the infrapopliteal arteries. Lessons for improving bolus-chase peripheral MRA

Peripheral magnetic resonance angiography (MRA) is growing in use. However, methods of performing peripheral MRA vary widely and continue to be optimized, especially for improvement in illustration of infrapopliteal arteries. The main purpose of this project was to identify imaging factors that can improve arterial visualization in the lower leg using bolus chase peripheral MRA. Eighteen healthy adults were imaged on a 1.5T MR scanner. The calf was imaged using conventional three-station bolus chase three-dimensional (3D) MRA, two dimensional (2D) time-of-flight (TOF) MRA and single-station Gadolinium (Gd)-enhanced 3D MRA. Observer comparisons of vessel visualization, signal to noise ratios (SNR), contrast to noise ratios (CNR) and spatial resolution comparisons were performed. Arterial SNR and CNR were similar for all three techniques. However, arterial visualization was dramatically improved on dedicated, arterial-phase Gd-enhanced 3D MRA compared with the multi-station bolus chase MRA and 2D TOF MRA. This improvement was related to optimization of Gd-enhanced 3D MRA parameters (fast injection rate of 2 mL/sec, high spatial resolution imaging, the use of dedicated phased array coils, elliptical centric k-space sampling and accurate arterial phase timing for image acquisition). The visualization of the infrapopliteal arteries can be substantially improved in bolus chase peripheral MRA if voxel size, contrast delivery, and central k-space data acquisition for arterial enhancement are optimized. Improvements in peripheral MRA should be directed at these parameters.

Flexion of the knee increases the distance between the popliteal artery and the proximal tibia: MRI measurements in 15 volunteers

We determined which angle of flexion best prevents popliteal artery injury during knee surgery. We took MRIs of the knee in the lateral position with the knee in 0 degrees, 45 degrees, 90 degrees, and 120 degrees of flexion in 15 volunteers. The shortest distance between the posterior cortex of the tibia and the popliteal artery was measured at various levels from the knee joint to 60 mm distally. At the level of the joint and 15 mm distally, the distance between the tibia and artery increased with increasing knee flexion. More distally, no significant difference was noted with increasing flexion. Flexion of the knee may minimize injury to the popliteal artery in procedures between the level of the joint and 15 mm distal to the joint.

The popliteal region: an anatomical study and a new approach to the tibial attachment of the posterior cruciate ligament

Surgical treatment of posterior cruciate ligament injuries is gaining more and more importance. The central posterior approach according to Abbott (1945) has been considered a standard, with various complications involved owing to the local anatomic conditions. This study is intended to present a modified dorsomedial approach to the posterior capsule of the knee joint that is better adapted to the anatomic conditions. As a basis, the popliteal region was dissected in 150 knee joints, and the course of the popliteal artery with its branches as well as the bifurcation of the sciatic nerve were identified. The medial joint line served as a reference point. It has been shown that the knee joint arteries and the two sural arteries arose at relatively constant levels. At least one of the meniscofemoral ligaments was found in all of the knee joints examined; the anterior ligament was present in a slightly higher percentage than the posterior ligament. The modified dorsomedial approach to the posterior joint capsule was evaluated in 50 knee joints. Dissection was achieved by blunt division of the medial head of the gastrocnemius muscle, with careful preservation of the proximal vascular supply of that muscle. It was necessary to expose neither the popliteal artery and vein nor the tibial nerve. The tibial attachment of the posterior cruciate ligament could be exposed in every knee. The advantage of the new approach to the posterior cruciate ligament described in this study consists in the preservation of the central neurovascular bundle and the excellent exposure of the tibial attachment.

Clinical anatomy of the popliteal blood vessels

The surgical management of venous injuries in the popliteal fossa is a contested issue. The basic options are ligation or repair. Most anatomy textbooks briefly describe a single popliteal vein, and the literature contains few references on venous patterns in this region. Although the primary objective of this study was to analyze venous variability in 52 dissected cadaveric popliteal fossae and 63 venograms, data were also collected on the popliteal artery. Nine groups (A-I) were designated regarding the manner of formation of the popliteal vein. These groupings were based primarily on differences in the union of the anterior tibial, posterior tibial, and fibular (peroneal) veins to form medial and lateral (popliteal) veins, and whether these two veins fused to form a singular popliteal vein proximal or distal to the transverse plane at the level of the distal edge of the femoral condyles (FC). In the majority of the dissections and venograms, multiple veins crossed the FC, and the medial vein was larger in diameter than the lateral vein. Two patterns of popliteal artery termination were observed based on differences in the site of origin of the fibular artery. The results were compared with anatomy and vascular surgery textbook descriptions and sparse literature reports on vascular variations in the popliteal fossa. It is hoped that these data will benefit surgeons performing procedures in this region.

High and low lateral approaches to the popliteal artery

Using a series of 20 dissections and two anatomic transverse sections of a lower limb, the authors investigated the lateral approaches to the popliteal artery. The high lateral approach (above the knee) is not very aggressive and gives access to the retro-genicular part of the popliteal artery. After cutaneous and fascial incision, a simple gap between the vastus lateralis and biceps femoris mm. allows easy exposure of the popliteal vessels after backward retraction of the sciatic nerve. The low lateral approach to the artery (below the knee) is very aggressive for the vessels, nerves, and ligaments of the area. It involves the resection of the upper fourth of the fibula and the isolation and protection of the common peroneal nerve Nevertheless, these lateral approaches must be known and used when classic approaches (medial and posterior) are impossible.

Proximity of the posterior cruciate ligament insertion to the popliteal artery as a function of the knee flexion angle: implications for posterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to determine if an optimal knee flexion angle existed that would minimize the risk of neurovascular injury from the passage of transtibial hardware during posterior cruciate ligament (PCL) reconstruction.

TYPE OF STUDY

Cadaveric.

MATERIALS AND METHODS

Fourteen fresh-frozen cadaveric knees were mounted in a Plexiglas apparatus that could be set at 5 different knee flexion angles (0 degrees, 45 degrees, 60 degrees, 90 degrees, and 100 degrees ) while joint distention was maintained. Each knee underwent magnetic resonance imaging in the axial and sagittal planes at each of the 5 flexion angles to determine the distance between the PCL tibial insertion and popliteal artery.

RESULTS

The mean distance, over all 5 flexion angles, between the PCL insertion and the popliteal artery in the axial plane was 7.6 mm, whereas the mean distance in the sagittal plane was 7.2 mm. There was a significant increase in distance with progressive flexion in both planes. Maximum mean distances were noted at 100 degrees of flexion in both the axial (9.9 mm) and sagittal (9.3 mm) planes. An artificial line mimicking the path of a transtibial drill passed through the popliteal artery in 10 of 10 cases at the 0 degrees, 45 degrees, 60 degrees, and 90 degrees angles, and in 6 of 10 cases at the 100 degrees angle.

CONCLUSIONS

The results of this study suggest that increasing knee flexion reduces, but does not completely eliminate, the risk of arterial injury during arthroscopic PCL reconstruction.

Large skin arteries of the leg and foot in man

The anatomical method with Computer Digital Image Analysis system served to examine large skin arteries of the crus and the foot in 152 human specimens. Their sources were: 1. popliteal artery (rr. gastrocnemii:medialis--62.89%, lateralis--78.95%), 2. anterior tibial artery (a. peronealis lateralis superior--97.37%, a. peronealis lateralis inferior--62.50%, a. collateralis inferior lateralis--78.95%), 3. posterior tibial artery (r. circumflexus fibulae--75.66%, r. soleus lateralis--48.03%, r. musculi flexoris hallucis longi--84.87%), 4. peroneal artery (r. perforans--86.84%) and 5. medial plantar artery (r. profundus--89.47%). The following ones characterized themselves with the longest course: a. peronealis lateralis superior (112 +/- t21 mm), r. gastrocnemius medialis (93 +/- 11 mm) and r. soleus lateralis (91 +/- 8 mm). The largest flaps supplied successively: r. gastrocnemius medialis (8530 +/- 1125 mm2), a. peronealis lateralis superior (7920 +/- 1227 mm2), r. profundus a. plantaris medialis (7580 +/- 1820 mm2), r. gastrocnemius lateralis (7320 +/- 1320 mm2), r. soleus lateralis (7140 +/- 1630 mm2) and a. collateralis inferior lateralis (6220 +/- 1981 mm2).

Morphologic change of the internal elastic lamina in Buerger's disease

Morphologic features and pathogenesis of arterial changes occurring in Buerger's disease (thromboangiitis obliterans) are still controversial. This study describes histopathologic features of medium sized arteries from patients with Buerger's disease, particularly of the internal elastic lamina in relation to the immunologic mechanism of the injury. Seventeen segments of occluded arteries (femoral or popliteal arteries) from 17 patients with Buerger's disease were analyzed by histopathological and immunohistochemical methods. The most characteristic features were total luminal obliteration, together with a varying degree of recanalization and deposition of hemosiderin pigments. Detailed analysis, however, showed marked undulation and multiplication of the internal elastic lamina (100%) associated with basophilic degeneration and delicate linear calcification (47%). Lymphocytic infiltration along the internal elastic lamina was seen in 71% and was associated with localized edema. Lymphocytes along the lamina were consistently positive for T cell marker. Mild to moderate fibrosis was present at the media in 24%. Adventitial changes included mild, nonspecific and irregular fibrosis seen in 53%. Immunologic injury to the internal elastic lamina associated with T-lymphocytic infiltration might be the initial morphogenetic mechanism of the thrombotic occlusion and organization of medium-sized arteries in Buerger's disease.

Real-time color flow MRI

A real-time interactive color flow MRI system capable of rapidly visualizing cardiac and vascular flow is described. Interleaved spiral phase contrast datasets are acquired continuously, while real-time gridding and phase differencing is used to compute density and velocity maps. These maps are then displayed using a color overlay similar to what is used by ultrasound. For cardiac applications, 6 independent images/sec are acquired with in-plane resolution of 2.4 mm over a 20 cm field of view (FOV). Sliding window reconstruction achieves display rates up to 18 images/sec. Appropriate tradeoffs are made for other applications. Flow phantom studies indicate this technique accurately measures velocities up to 2 m/sec, and accurately captures real-time velocity waveforms (comparable to continuous wave ultrasound). In vivo studies indicate this technique is useful for imaging cardiac and vascular flow, particularly valvular regurgitation. Arbitrary scan planes can be quickly localized, and flow measured in any direction.

Linear combination steady-state free precession MRI

A new, fast, spectrally selective steady-state free precession (SSFP) imaging method is presented. Combining k-space data from SSFP sequences with certain phase schedules of radiofrequency excitation pulses permits manipulation of the spectral selectivity of the image. For example, lipid and water can be resolved. The contrast of each image depends on both T1 and T2, and the relative contribution of the two relaxation mechanisms to image contrast can be controlled by adjusting the flip angle. Several potential applications of the technique, referred to as linear combination steady-state free precession (LCSSFP), are demonstrated: fast musculoskeletal, abdominal, angiographic, and brain imaging.

Popliteal vessels in knee surgery. A magnetic resonance imaging study

Popliteal artery injury during surgery of the knee is rare but can have devastating consequences. The position of knee flexion has been thought to be protective for the popliteal artery, allowing it to fall back from the knee joint. No prior study has provided in vivo cross sectional evidence of the behavior of the popliteal vessels during knee flexion with the effect of gravity. Magnetic resonance imaging was used in nine volunteers to measure the distance of the popliteal artery and veins from the posterior proximal tibia at two levels corresponding to the levels of osteotomy in total knee arthroplasty and in high tibial osteotomy. Scans were taken with the knee in full extension and at 90 degrees flexion with the patient in the supine position, allowing for the effect of gravity. Considerable variation in behavior of the vein and the artery was observed at the high tibial osteotomy cross sectional level and the total knee arthroplasty cross sectional level. In two knees at the high tibial osteotomy cross sectional level and in two knees at the total knee arthroplasty cross sectional, level the artery moved closer to the posterior tibia with knee flexion. Even with the effect of gravity included, knee flexion does not guarantee removal of the popliteal vessels from potential harm during surgery of the knee.

Midvastus approach in total knee arthroplasty: a description and a cadaveric study determining the distance of the popliteal artery from the patellar margin of the incision

Total knee arthroplasty (TKA), one of the most efficacious procedures in orthopedics, requires complete exposure of the knee joint for precise instrumentation. Although most orthopedic surgeons agree that TKA is easily performed using a medial parapatellar approach, a large segment of the patellar blood flow is disrupted by this exposure. The southern or subvastus approach addresses these concerns; however, the procedure has the disadvantage of inadequate exposure in certain patients. A compromise between these two approaches, a midvastus approach, has been described. To decrease potential neurovascular injury, this cadaveric study of the midvastus approach determines the proximity of the incision to the popliteal vascular bundle and addresses the innervation pattern of the vastus medialis oblique. A midvastus arthrotomy was performed on 19 female and 15 male adult cadaveric knees. The midpoint of the superior pole of the patella and the superomedial patellar prominence were marked. After determining the midpoint between the 2 previously mentioned landmarks, an incision was made from that point paralleling the fibers of the vastus medialis oblique medially to the popliteal vascular bundle. The length of the incision was measured three times using calipers; measurements were averaged for each individual specimen, then by gender, and, finally, overall. Ninety-five percent confidence intervals were determined. Differences were assessed by an independent t-test with an alpha level of significance at .05. In addition, the terminal branches of the femoral nerve innervating the vastus medialis oblique were dissected in 5 cadavers. The femoral nerve branched extensively to innervate the vastus medialis oblique. The average distance between the patella and the popliteal vessels was 8.8 +/- 1.4 cm. The average distance in males, 9.5 +/- 1.4 cm, was significantly greater than the distance in females, 8.3 +/- 1.2 cm (P < .02). The distance appeared proportionate to the size of the extremity. The midvastus approach is a viable alternative for primary TKA in selected patients who are not obese and who have not had previous arthrotomy or osteotomy. The average distance (8.8 cm) and corresponding range (6.5 cm minimum to 12.3 cm maximum) are sufficient to suggest a maximal safe distance for sharp dissection of 4.5 cm from the patellar margin in an adult. For additional exposure, the muscle can be safely split further with blunt dissection.

Voxel sensitivity function description of flow-induced signal loss in MR imaging: implications for black-blood MR angiography with turbo spin-echo sequences

The conditions in which the image intensity of vessels transporting laminar flow is attenuated in black-blood MR angiography (BB-MRA) with turbo spin-echo (TSE) and conventional spin-echo (CSE) pulse sequences are investigated experimentally with a flow phantom, studied theoretically by means of a Bloch equation-voxel sensitivity function (VSF) formalism, and computer modeled. The experiments studied the effects of: a) flow velocity, b) imaging axes orientation relative to the flow direction, and c) phase encoding order of the TSE train. The formulated Bloch equation-VSF theory describes flow effects in two-dimensional (2D)- and 3D-Fourier transform magnetic resonance imaging. In this theoretical framework, the main attenuation mechanism instrumental to BB-MRA, i.e., transverse magnetization dephasing caused by flow in the presence of the imaging gradients, is described in terms of flow-induced distortions of the individual voxel sensitivity functions. The computer simulations predict that the intraluminal homogeneity and extent of flow-induced image intensity attenuation increase as a function of decreasing vessel diameter, in support of the superior image quality achieved with TSE-based BB-MRA in the brain.

Effects of interleaf order for spiral MRI of dynamic processes

The effects of the temporal order in which spiral interleaves are collected are discussed, in the context of artifacts from moving or changing objects. Simulations and in vivo experiments demonstrate the properties of four different ordering methods. Specific applications discussed include cardiac and interventional magnetic resonance imaging, as well as inflow and contrast-enhanced magnetic resonance angiography.

[Anatomical and clinical studies on the free posterior leg flap pedicled with the lateral popliteal cutaneous artery]

OBJECTIVE

To investigate the feasibility of free transference of the posterior leg flap which is supplied by the lateral popliteal cutaneous artery.

METHODS

Anatomical dissection is performed in twenty-two freshly amputated adult lower extremities.

RESULTS

The discovery rate of the lateral popliteal cutaneous artery is 100%. The vessel is 20.0 +/- 5.7 cm in length with an exterior diameter of 1.28 +/- 0.25 mm at the junction of the popliteal artery. The course of the artery is constant, and it is usually accompanied by the lateral sural cutaneous nerve. Seven operations using this free flap have been performed successfully.

CONCLUSION

The flap is suitable for repairing medium-sized soft tissue defects or for functional reconstruction.

Factors predicting the diameter of the popliteal artery in healthy humans

PURPOSE

To determine the relevance of popliteal dilatations, knowledge of the normal popliteal artery diameter is essential. This study investigates the diameter of the popliteal artery in healthy males and females.

METHODS

We measured the diameter of the popliteal artery in 121 healthy volunteers (59 males and 62 females), ages 8 to 81, with echo-tracking B-mode ultrasonography. We analyzed the influence of age, sex, height, weight, body surface area (BSA) and systolic blood pressure with a multiple regression model.

RESULTS

The popliteal artery increased steadily in diameter throughout life. From 25 years on, the diameter was larger in males than in females. If corrected for BSA, this difference decreased from 17% to 7%. This study found a correlation between popliteal artery diameter and BSA (r=0.47 and r=0.61, respectively, p < 0.0001). Age, followed by BSA, was the most influencing factor on popliteal diameter in both males and females (r=0.62 and r=0.66, respectively, p < 0.0001). We used age and BSA in creating a model for prediction of popliteal artery diameter.

CONCLUSIONS

The diameter of the popliteal artery increases with age, initially during growth, but also in adults. This is related to age, body size and sex, with males having larger arteries than females. It is now possible to predict the normal popliteal arterial diameter, and nomograms are presented for use in the study of aneurysmal arterial disease.