Aims. This study investigated the effects of transcatheter arterial embolization (TAE) on pain, function, and quality of life in people with early-stage symptomatic knee osteoarthritis (OA) compared to a sham procedure. Methods. A total of 59 participants with symptomatic Kellgren-Lawrence grade 2 knee OA were randomly allocated to TAE or a sham procedure. The intervention group underwent TAE of one or more genicular arteries. The control group received a blinded sham procedure. The primary outcome was knee pain at 12 months according to the Knee injury and Osteoarthritis Outcome Score (KOOS) pain scale. Secondary outcomes included self-reported function and quality of life (KOOS, EuroQol five-dimension five-level questionnaire (EQ-5D-5L)), self-reported Global Change, six-minute walk test, 30-second chair stand test, and adverse events. Subgroup analyses compared participants who received complete embolization of all genicular arteries (as distinct from embolization of some arteries) (n = 17) with the control group (n = 29) for KOOS and Global Change scores at 12 months. Continuous variables were analyzed with quantile regression, adjusting for baseline scores. Dichotomized variables were analyzed with chi-squared tests. Results. Overall, 58 participants provided questionnaire data at 12 months. No significant differences were found for the primary and secondary outcomes, with both groups improving following the procedure. At 12 months, KOOS pain scores improved by 41.3% and 29.4% in the intervention and control groups, respectively. No adverse events occurred. Subgroup analysis indicated that the complete embolization group had significantly better KOOS Sports and Recreation, KOOS Quality of Life, and Global Change scores than the control group; 76.5% of participants who received complete embolization reporting being moderately or much better compared to 37.9% of the control group. Conclusion. TAE might produce benefits above placebo, but only when complete embolization of all genicular arteries is performed. Further comparative studies are required before definitive conclusions regarding the effectiveness of TAE can be made. Level of evidence: I. Cite this article: Bone Jt Open 2023;4(3):158–167

During the medical student’s training in the Anatomy we have studied the arterial constitutions of the superior limb in 100 bodies from the Laboratory of the Descriptive Anatomy of the Medical School, University of Athens. We have examined the brachial artery and the superficial brachial artery. Superficial brachial artery is called the major artery that is found superficially of the middle nerve. Such an artery can either substitute or complete the brachial artery. For reasons of classification we took into account the arteries only and neglected the smaller branches. The superficial brachial artery often origins from the proximal part of the forearm and the clinical interest of this remark consists on the fact that this artery leads to the forearm, in front of the biceps brachial muscle’s aponeurosis. By this way it can easily be mistaken as a vein and an “intravenous” injection can be disastrous. Our results were:. A. Only one brachial artery: 76%. The classic case of the books of Anatomy: the brachial artery is found opposite of the middle nerve, crossing under it at the upper arm: 74%. The middle nerve’s constitution is not the typical one at the armpit, but the artery crosses under it: 2%. B. Presence of one brachial artery only: 10% One brachial artery in front of the two radixes of the middle nerve: 2%. The major artery is found opposite of the radixes of the middle nerve, but crosses in front of it at the arm:4%. The dorsal artery is found behind the middle nerve from the dorsal part but comes over the nerve between the musculocutaneous and the middle nerve: 2%. There is not the typical constitution of the middle nerve from two radixes and the artery is found in front of the middle nerve:2%. C. Two major arterial branches: 14%. The axillary artery is divided in two branches one in frond of and the other behind of the radixes of the middle nerve: 5%. The brachial artery is divided in two branches one of which is found in frond of the middle nerve: 9%

Introduction: Mönckeberg sclerosis or medial artery calcification (MAC) is a well known phenomenon associated with the diabetic and other altered blood parameters. However its consequence within the foot and specifically the 1st dorsal metatarsal artery has not previously been studied. Materials and Methods: Nearly 1000 foot x-rays were studied over a nine month period in a busy District General Hospital to identify the prevalence of first dorsal metatarsal artery calcification. The electronic medical notes for all the patients were reviewed to confirm which patients were known to be diabetic. The patients with positive findings were then identified and their HbA1c, creatinine, and previous foot interventions recorded. Results: 1.4% of the population studied had medial artery calcification of the 1st dorsal metatarsal artery. 93% were known diabetics and 100% had impaired glucose tolerance (a glucose plasma concentration of > 7.8mmol/l two hours post glucose loading). 79% have required previous podiatric care for foot ulceration and 64% had required surgical intervention for their diabetic feet. MAC has a high positive predictive value (92.9% (95% CI 69.2–98.7)) for diabetes, with a good specificity (99.9% (95%CI 99.4–100)) and low false positive rate (0.1% (05%CI 0.0–0.6)). Discussion: Medial artery calcification in the first dorsal metatarsal artery is characteristic of impaired glucose metabolism, and if seen on routine x-ray should be an indication for screening of the patient. It should also be considered as a foot at risk sign in the established diabetic due to the high incidence of foot ulceration and need for surgical intervention in this group. Conclusion: The prevalence of MAC seen on routine foot x-rays has been demonstrated in a large cohort of patients. The specificity and positive predictive value for diabetes has been calculated and the prevalence of these patients requiring surgical or specialist podiatric care recorded

Osteochondromas are benign chondrogenic lesions arising on the external surface of the bone with aberrant cartilage (exostosis) from the perichondral ring that may contain a marrow cavity also. In a few cases, depending on the anatomical site affected, different degrees of edema, redness, paresthesia, or paresis can take place due to simple contact or friction. Also, depending on their closeness to neurovascular structures, the procedure of excision becomes crucial to avoid recurrence. We report a unique case of recurrent osteochondroma of the proximal humerus enclosing the brachial artery which makes for an important case and procedure to ensure that no relapse occurs. We report a unique case of a 13-year-old female who had presented with a history of pain and recurrent swelling for 5 years. The swelling size was 4.4 cm x 3.7 cm x 4 cm with a previous history of swelling at the same site operated in 2018. CT reports were suggestive of a large well defined broad-based exophytic diaphyseal lesion in the medial side of the proximal humerus extending posteriorly. Another similar morphological lesion measuring approximately 9 mm x 7 mm was noted involving the posterior humeral shaft. The minimal distance between the lesion and the brachial artery was 2 mm just anterior to the posterio-medial growth. Two intervals were made, first between the tumor and the neurovascular bundle and the other between the anterior tumor and brachial artery followed by exostosis and cauterization of the base. Proper curettage and excision of the tumor was done after dissecting and removing the soft tissue, blood vessels, and nerves so that there were very less chances of relapse. Post-operative X-ray was done and post 6 months of follow-up, there were no changes, and no relapse was observed. Thus, when presented with a case of recurrent osteochondroma of the proximal humerus, osteochondroma could also be in proximity to important vasculature as in this case enclosing the brachial artery. Thus, proper curettage and excision should be done in such cases to avoid recurrence

Calcification and ossification have been described in artery wall in pathologic conditions and aging. We previously described the use of cryopreserved arterial allografts as membranes for guiding bone regeneration. We hypothesize that artery is as good as synthetic membranes (e-PTFE, gold-standard in guided bone regeneration) due to the osteogenic potential of cells from its medial layer. A comparative study was made creating 10 mm mid-diaphyseal radial defects in 15 New Zeland rabbits (30 forearms): 10 defects were covered with an e-PTFE membrane and 10 defects with no membrane (control group). Studies: X-rays, CT, MR, morpho-densitometric analysis, electronic and optical microscopy. To demonstrate the cellular arterial stock, cryopre-served and fresh rabbit thoracic aorta specimens were studied. Medial layer was isolated and cultured as explants in normal medium. Cells were harvested and added to a 3-D scaffold based on plasmatic albumin in osteogenic medium. Immunocitochemical study was made. Radial defects surrounded by cryopreserved arterial membranes showed total regeneration in nine of 10 defects versus seven of 10 defects in e-PTFE group (no statistically significant differences were detected between them). No tissue layer was found between bone and artery while a connective tissue layer was observed between e-PTFE and bone. Neither radiological nor histological healing were detected in the control group. Cells cultured had smooth muscle features as they showed immunofluorescence with anti-smooth muscle alpha-actin, anti-calponin and anti-vimentin antibodies. When cells were added to a 3-D matrix, they showed chondro and osteogenic differentiation, as they stained positive for types II and X collagen, alkaline phosphatase and von Kossa. Although no statistically significant differences between artery and e-PTFE groups were detected, histological and cellular findings suggest a superiority of cryopreserved arterial allografts when compared with synthetic membranes of e-PTFE, with a contribution of the cellular stock of the medial layer in the healing process

Despite the expansion of arthroscopic surgery of the shoulder, the open deltopectoral approach to the shoulder is still frequently used, for example in fracture fixation and shoulder replacement. However, it is sometimes accompanied by unexpected bleeding. The cephalic vein is the landmark for the deltopectoral interval, yet its intimate relationship with the deltoid artery, and the anatomical variations in that structure, have not previously been documented. In this study the vascular anatomy encountered during 100 consecutive elective deltopectoral approaches was recorded and the common variants described. Two common variants of the deltoid artery were encountered. In type I (71%) it crosses the interval and tunnels into the deltoid muscle without encountering the cephalic vein. However, in type II (21%) it crosses the interval, reaches the cephalic vein and then runs down, medial to and behind it, giving off several small arterial branches that return back across the interval to the pectoralis major. Several minor variations were also seen (8%). These variations in the deltoid artery have not previously been described and may lead to confusion and unexpected bleeding during this standard anterior surgical approach to the shoulder. Cite this article: Bone Joint J 2013;95-B:657–9

During a wide study of the arterial variations in the Greek population, we examined the arterial trunks, arising from the subclavian and axillary arteries.150 cadavers were examined by the Forensic Service of Athens University. SUBCLAVIAN ARTERY. The focal point of our research was the origin of the inferior thyroid, the suprascapular and the transversal cervical artery. In 6.6% of our cases all three of the mentioned arteries had a common origin. As far as the rest 93.4% is concerned, we came to the following conclusions:. A. There was only one trunk without the participation of the pleurocervical trunk (81.3%). 1. The thyrocervical trunk is formed by the inferior thyroid, the suprascapular and the transversal cervical branches (classical anatomic knowledge) (33.3%). 2. The internal mammary artery arises from the thyrocervical trunk (9.3%). 3. The trunk is formed by the inferior thyroid and the suprascapular artery (26.6%). 4. The trunk is formed by the inferior thyroid, the supra-scapular and the internal mammary artery (6.6%). 5. There are two trunks: the first one is formed by the inferior thyroid and the suprascapular and the second one by the transversal cervical and the internalmammary artery (2.6%). 6. There are two trunks: the first one is formed by the inferior thyroid and the transversal cervical artery and the second one by the suprascapular and the internal mammary artery (4%). B. Participation of the pleurocervical trunk (12%). 1. The transversal cervical artery with the pleurocervical trunk (6%). 2. The pleurocervical trunk arises from the internal mammary artery (2%). 3. The pleurocervical trunk with the suprascapular artery (1.3%). 4. The inferior thyroid artery with the pleurocervical trunk (1.3%). 5. The pleurocervical trunk with the inferior thyroid and the suprascapular artery (1.3%). AXILLARY ARTERY. As far as the axillary is concerned, the 12% of the cadavers follow the basic model. As far as the rest of the cases are concerned, we concluded that:. A. Some branches form common trunks (48%). 1. The lateral thoracic and the dorsothoracic artery form a common trunk (11.3%). 2. The lateral thoracic together with the subscapular artery form a common trunk (9.3%). 3. The subscapular and the posterior circumflex brachial artery (9.3%). 4. Both the circumflex brachial arteries form a common trunk (18%) B. The arteries of the arm arise from the axillary artery (21.3%). 1. The profunda brachial artery arises from the axillary artery (11.3%). 2. The superficial brachial artery arises from the axillary artery (5.3%). 3. The profunda brachial artery arises from the posterior circumflex brachial artery (4.6%) C. Special cases (18.6%). 1. There are supplementary branches in the parries (5.3%). 2. Separate origin of the circumflex scapular artery and the dorsothoracic artery (5.3%). 3. The dorsothoracic artery is short compared to the lateral thoracic artery (2.6%). 4. The posterior circumflex artery arises from the brachial artery (5.3%)

This study investigates and defines the topographic anatomy of the medial femoral circumflex artery (MFCA) terminal branches supplying the femoral head (FH). Gross dissection of 14 fresh–frozen cadaveric hips was undertaken to determine the extra and intracapsular course of the MFCA’s terminal branches. A constant branch arising from the transverse MFCA (inferior retinacular artery; IRA) penetrates the capsule at the level of the anteroinferior neck, then courses obliquely within the fibrous prolongation of the capsule wall (inferior retinacula of Weitbrecht), elevated from the neck, to the posteroinferior femoral head–neck junction. This vessel has a mean of five (three to nine) terminal branches, of which the majority penetrate posteriorly. Branches from the ascending MFCA entered the femoral capsular attachment posteriorly, running deep to the synovium, through the neck, and terminating in two branches. The deep MFCA penetrates the posterosuperior femoral capsular. Once intracapsular, it divides into a mean of six (four to nine) terminal branches running deep to the synovium, within the superior retinacula of Weitbrecht of which 80% are posterior. Our study defines the exact anatomical location of the vessels, arising from the MFCA and supplying the FH. The IRA is in an elevated position from the femoral neck and may be protected from injury during fracture of the femoral neck. We present vascular ‘danger zones’ that may help avoid iatrogenic vascular injury during surgical interventions about the hip. Cite this article: Bone Joint J 2015;97-B:1204–13

Background. Nutrient arteries appear as radiolucent lines (Fig. 1) on account of their topography and may erroneously suggest fracture lines. Question/purpose. (1) How frequently the nutrient artery canals of the femur are seen after cementless THA and their distribution patterns are; (2) How to distinguish visible nutrient artery canal from fracture lines; and (3) Whether clinical significance of the nutrient artery canals of the femur in patients with primary cementless THA is evident or not. Methods. Between March 2010 and December 2013, 93 patients 102 hips were enrolled for this retrospective analysis. The number, location, direction of obliquity, length of the nutrient artery canals of the femur, the distance between the tip of the greater trochanter and the proximal end of the nutrient artery canal were measured. Results. The nutrient artery canal of the femur in the cortex on preoperative cross-table lateral hip radiograph (NACL) was seen in 32 of 102 hips (31.4%), the nutrient artery canal of the femur in the medullary cavity on preoperative anteroposterior hip radiograph (NAMA) was seen in 17 hips (16.6%), and the nutrient artery canal of the femur in the medullary cavity on preoperative cross-table lateral hip radiograph (NAML) was seen in 5 hips (4.9%). The nutrient artery canal of the femur in the cortex on anteroposterior hip radiograph was not seen at all. Entire visible NACLs coursed upward obliquely from postero-distal to antero-proximal direction. An average length of NACL was 32.6 ± 13.9 mm and an average distance between the tip of the greater trochanter and the proximal end of the NACL, NAMA and NAML was 130.1 ± 15.8 mm, 105.1 ± 13.4 mm and 102.5 ± 7.4 mm, respectively. NACL was seen postoperatively in 37 of 102 hips (36.3%), in 24 of which (23.5% overall) both ends of the nutrient artery canal were distal to the implant tip and in 13 of which (12.8% overall) one of the ends of the nutrient canal was at least proximal to the implant tip. NAMA was seen postoperatively in 8 of 102 hips (7.8%) and NAML was seen postoperatively in 6 hips (5.9%), in 5 of which (4.9% overall) femoral stems fully masked the nutrient artery canal and in 9 of which (8.8% overall) a nutrient artery canal was visible postoperatively, but its proximal end was not defined because of implant shadowing. The length of stems which fully masked the nutrient artery canals postoperatively were at least 150 mm or larger. Six (5.9%) intraoperative periprosthethic femoral fractures were detected (Fig. 2 and 3). One was type TL, one was type A1, three were type B2 and one was type B3. Type B2 fractures showed new or additional radiolucent lines on intraoperative and/or postoperative radiographs by comparison with the preoperative radiographs. Conclusions. The knowledge of radiographic features of the nutrient artery canals of the femur may be useful to distinguish them from intraoperative fractures after cementless THA

We describe a case of lumbosacral plexopathy caused by an isolated aneurysm of the common iliac artery. The patient presented with worsening low back pain, progressive numbness and weakness of the right leg in the L2-L4 distribution. This had previously been diagnosed as sciatica. A CT scan showed an aneurysm of the right common iliac artery which measured 8 cm in diameter. Despite being listed for emergency endovascular stenting, the aneurysm ruptured and the patient died. It is important to distinguish a lumbosacral plexopathy from sciatica and to bear in mind its treatable causes which include aneurysms of the common and internal iliac arteries

The direct anterior approach (DAA) is a popular minimally invasive approach for total hip arthroplasty (THA). It usually involves ligation of the lateral femoral circumflex artery's ascending branch (a-LFCA), which contributes to the perfusion of the tensor fasciae latae (TFL) muscle. Periarticular muscle status and clinical outcome were assessed after DAA-THA after a-LFCA preservation versus ligation. We evaluated surgical records of 161 patients undergoing DAA-THA with tentative preservation of the a-LFCA by the senior author between May and November 2021. Among 92 eligible patients, 33 (35 hips) featured successful preservation, of which 20 (22 hips, 13 female) participated in the study. From 59 patients with ligated a-LFCA, 26 (27 hips, 15 female) were enrolled, constituting the control group. MRI and clinical examinations were performed at 17–26 months to analyze volume and fatty infiltration of the TFL, gluteus medius and gluteus minimus muscles relative to the contralateral non-THA hip (15 preserved, 18 ligated). Clinical and radiographic data was retrospectively extracted from patient files. Patient-reported outcomes (PROMs) were added from the THA registry. There was a relative difference in TFL muscle volume of -6.27 cm. 3. (−9.89%, p=0.018) after a-LFCA preservation versus -8.6 cm. 3. (=11.62%, p=0.002) after ligation, without group differences (p>0.340). a-LFCA preservation showed lower relative TFL fatty infiltration (p=0.10). Gluteal muscle status was similar between sides and groups. Coxa valga morphology was more frequent in a-LFCA preservation (83%) than ligation (17%). Clinical outcomes showed high patient satisfaction in both groups, without difference in PROMs, but less anterolateral soft-tissue swelling after a-LFCA preservation (p<0.001). Despite excellent clinical results in both groups, preservation of the a-LFCA was associated with less TFL fatty infiltration and soft tissue swelling. Provided there is no compromise of intraoperative access we recommend a-LFCA preservation for DAA-THA

Topographic anatomy and general distribution of LFCA is well described in anatomy textbooks. Its contribution to the vascularization of specific anatomic structures in the hip region is poorly defined. The purpose of this study was to demonstrate the importance of LFCA in hip circulation, especially in the vascularization of hip abductors. The LFCA was specifically studied in 30 hips from 26 fresh cadavers after injection of common iliac artery or aorta with colored silicone for a more extensive hip vascular study. 24 hours after intra-arterial setting of silicone, dissection was performed through the anterior iliofemoral approach to expose the artery and its branches from the origin to the terminal distribution. In all specimens, the ascending branch of the LFCA was found as consistent supplier of gluteus minimus, gluteus medius, and tensor fasciae latae muscles by a variable number of branches. The proximal part of the abductor muscles was mainly supplied by the superior gluteal artery. We conclude, that ligating the ascending branch of the LFCA during anterior approach to the hip joint is likely to affect the vascularity and function of the abductor muscles especially in situations when perfusion of these muscles by the superior gluteal artery is compromised

The brachial artery is rarely injured after closed dislocation of the elbow. We describe an unusual variation of this injury, namely, a delayed thrombosis of the brachial artery after a closed dislocation sustained during a low-energy fall. This has not previously been described in the English literature, but may be more common than this suggests. We stress the importance of a thorough neurovascular examination and vigilance in regard to this potentially disastrous complication

Aims. We aimed to quantify the relative contributions of the medial femoral circumflex artery (MFCA) and lateral femoral circumflex artery (LFCA) to the arterial supply of the head and neck of the femur. Materials and Methods. We acquired ten cadaveric pelvises. In each of these, one hip was randomly assigned as experimental and the other as a matched control. The MFCA and LFCA were cannulated bilaterally. The hips were designated LFCA-experimental or MFCA-experimental and underwent quantitative MRI using a 2 mm slice thickness before and after injection of MRI-contrast diluted 3:1 with saline (15 ml Gd-DTPA) into either the LFCA or MFCA. The contralateral control hips had 15 ml of contrast solution injected into the root of each artery. Next, the MFCA and LFCA were injected with a mixture of polyurethane and barium sulfate (33%) and their extra-and intra-arterial course identified by CT imaging and dissection. Results. The MFCA made a greater contribution than the LFCA to the vascularity of the femoral head (MFCA 82%, LFCA 18%) and neck (MFCA 67%, LFCA 33%). However, the LFCA supplied 48% of the anteroinferior femoral neck overall. Conclusion. This study clearly shows that the MFCA is the major arterial supply to the femoral head and neck. Despite this, the LFCA supplies almost half the anteroinferior aspect of the femoral neck. Cite this article: Bone Joint J 2016;98-B:1582–8

We studied 12 consecutive patients with facet joint dislocation in the cervical spine to assess the incidence, site and clinical sequelae of occlusion of the extracranial vertebral artery. Intra-arterial digital subtraction angiography was performed after the orthopaedic management of the dislocations. This demonstrated vertebral artery occlusion (one bilateral) in five of the seven patients with bilateral dislocations and in four of the five patients with unilateral dislocations. Two of the nine patients with vertebral artery occlusion had neurological deficits above the level of the injury, all of which resolved spontaneously within two months. In our experience, a distraction-flexion injury appears to be the most common cause of closed traumatic vertebral artery occlusion

1. Two cases of rupture of the axillary artery without dislocation of the shoulder or fracture of the neck of the humerus are reported, and the etiology is discussed. 2. The treatment of a ruptured axillary artery is primary repair, and not ligation. 3. In the repair of the artery the complete clearance of distal thrombus is most important; retrograde flushing is advised for this purpose

Purpose of the study: We report a case of complete unilateral absence of the radial artery in the forearm and reviewed the pertinent literature. Case report: An 18-year-old girl was admitted for multiple fractures after a car accident. She presented with a comminuted fracture of the left distal humerus, an open grade I fracture according to the Gustilo classification involving the right ulna and radius, a mediodiaphyseal fracture of the right femur and an open grade II fracture of the proximal and distal left tibia. After open reduction and internal fixation of the bones of the right forearm, she presented transient ischemia of her right hand, the radial pulse not being detectable at the end of surgery. An arteriography showed a complete absence of the right radial artery, which was thought to be caused by arterial thrombosis. Surgical exploration evidenced the complete absence of the radial artery. Discussion: Absence of the radial artery is observed in radial preaxial hemimelia, in specific genetic and chromosomal disorders (Fanconi’s anemia, Holt-Oram syndrome) and in association with other malformations. Unilateral absence of the radial artery has been described in association with other vascular abnormalities such as a larger anterior interosseous artery or the presence of a medial artery. Our case presented an isolated anatomical variation of the radial artery. This vascular anomaly was asymptomatic and discovered fortuitously. The incidence of this anatomic anomaly may be underestimated in the general population

Rupture of an aneurysm of the common iliac artery is a rare cause of pain in the hip. We describe an elderly hypertensive patient with an aneurysmal rupture of the left common iliac artery who presented with unilateral hip pain masquerading as septic arthritis

Introduction: The aim of this study was to investigate if steroids enhance the vasoconstrictive effect of endothe-lin-1 (ET-1) on femoral arteries. Materials and Methods: Ten female Wistar rats 59 to 88 days of age and 238 to 310 g of body weight, were used. Forty femoral artery segments were harvested. These arterial segments were mounted as ring preparations on a small vessel myograph. Two vessels from each animal were randomized to incubation with methylprednisolone 5 μg/ml [1] while the other 2 vessels were incubated with placebo. The arteries were stimulated cumulatively with endothelin-1. Isometric wall tension was quantified by the EC50; the vasoconstrictor concentration resulting in half maximal contraction. Results: Thirty-eight arteries could be harvested in total; 20 were randomized to steroid treatment while 18 served as controls. The endothelin-1 dose-response curve displayed a stronger contraction for the steroid group in relation to the controls with increasing doses of ET-1. The EC50 of 4.4*10. −8. M ± 1.8*10. −8. M for the steroid vessels was lower compared to 5.9*10. −8. M ± 3.4*10. −8. M for the controls (mean ±SD; n.s.). Discussion: Endothelin-1 is a potent vasoconstrictor. This study showed that incubation with methylprednisolone enhanced ET-1 mediated contraction of femoral arteries which can diminish blood flow within the vascular bed supplying the femoral head. This may be a relevant cofactor in the early pathogenesis of steroid-associated femoral head necrosis

Total knee replacements and high tibial osteotomies are commonly performed orthopaedic operations with low complication rates. Both of these procedures involve surgery in close proximity to the popliteal artery with the use of power tools and sharp instruments. The behaviour of the popliteal artery during knee flexion, in particular the change in distance between itself and the posterior tibial cortex, is poorly understood. Many previous studies have been on stiff embalmed knees or with the patient lying supine, so as to subject the popliteal artery to an anterior pull from gravity. We used duplex ultrasonography on 100 healthy knees to determine the distance of the popliteal artery from the posterior tibial surface at 0 and 90 degrees of flexion. One observer was used throughout. At 1–1.5cm below the joint line, we found the artery was closer to the posterior tibial surface in 24% of knees when the knee was flexion. This was also the case for 15% of knees at 1.5–2cm below the joint line. These two levels were chosen as they represent the usual positions for the tibial cuts performed in total knee replacement and tibial osteotomy. We provide an anatomical account to help explain our findings using cadaveric dissections, arteriography and static MRI studies. The first of our explanations for this posterior movement of the artery is the increase in the antero-posterior thickness of the popliteus muscle during knee flexion. We also observed a posterior pull on the popliteal artery from the sural vessels. 6% of the knees had a high branching anterior tibial branch. We highlight this anatomical variant as an example of an extremely vulnerable vessel. We review the existing literature regarding the popliteal artery dynamics, and conclude that 90 degrees of knee flexion is the safer position for tibial procedures, but repeat the warning that the surgeon must still take great care