Dynamic contrast-enhanced MRI of the patellar bone: How to quantify perfusion.

PURPOSE: To identify the optimal combination of pharmacokinetic model and arterial input function (AIF) for quantitative analysis of blood perfusion in the patellar bone using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). MATERIALS AND METHODS: This method design study used a random subset of five control subjects from an Institutional Review Board (IRB)-approved case-control study into patellofemoral pain, scanned on a 3T MR system with a contrast-enhanced time-resolved imaging of contrast kinetics (TRICKS) sequence. We systematically investigated the reproducibility of pharmacokinetic parameters for all combinations of Orton and Parker AIF models with Tofts, Extended Tofts (ETofts), and Brix pharmacokinetic models. Furthermore, we evaluated if the AIF should use literature parameters, be subject-specific, or group-specific. Model selection was based on the goodness-of-fit and the coefficient of variation of the pharmacokinetic parameters inside the patella. This extends previous studies that were not focused on the patella and did not evaluate as many combinations of arterial and pharmacokinetic models. RESULTS: The vascular component in the ETofts model could not reliably be recovered (coefficient of variation [CV] of vp >50%) and the Brix model parameters showed high variability of up to 20% for kel across good AIF models. Compared to group-specific AIF, the subject-specific AIF's mostly had higher residual. The best reproducibility and goodness-of-fit were obtained by combining Tofts' pharmacokinetic model with the group-specific Parker AIF. CONCLUSION: We identified several good combinations of pharmacokinetic models and AIF for quantitative analysis of perfusion in the patellar bone. The recommended combination is Tofts pharmacokinetic model combined with a group-specific Parker AIF model. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:848-858.

Lateral parapatellar and subvastus approaches are superior to the medial parapatellar approach in terms of soft tissue perfusion.

PURPOSE: The arthrotomy techniques of knee surgery may cause varying degrees of disruption to the tissue blood supply. The aim of this study was to investigate the effects of the medial parapatellar (MPPa), midvastus (MVa), subvastus (SVa) and lateral parapatellar (LPPa) approaches on regional tissue perfusion of the knee. METHODS: In this experimental study, a total of 28 female rabbits were applied with four different arthrotomy techniques as Group MPPa, Group MVa, Group SVa and Group LPPa. The blood supply of the tissue around the knee was examined by scintigraphic imaging including the perfusion reserve and T max, and biochemical alteration of the oxidative stress parameters including malondialdehyde (MDA), fluorescent oxidation products (FlOPs), and histopathological findings were evaluated on tissue samples after 3 weeks. RESULTS: The perfusion reserve was increased in all four groups compared to the healthy, contralateral knees. In the Group LPPa, the vascularity was significantly increased compared to the Group MPPa (p = 0.006). In the examination of biochemical parameters, the increase in MDA levels was statistically significant in the Group MPPa compared with the Group LPPa (p = 0.004), and in the Group MVa compared with the Group LPPa (p = 0.006). The increase in the value of MDA levels was striking in the Group MPPa and Group MVa compared with the control group (p = 0.004, p = 0.004, respectively). The increase in another oxidative stress parameter, the tissue FlOPs levels, was statistically significant in the Group MPPa compared with the control group (p = 0.035). CONCLUSION: The LPPa and SVa caused less oxidative stress and less disruption of the muscle blood supply, in biochemical and scintigraphic parameters, compared to the MPPa and MVa. Therefore, in clinical practice, the SVa is preferable to the MPPa and MVa in total knee arthroplasty and the LPPa should be preferred more frequently in selected cases with critical soft tissue viability.

Infrapatellar fat pad features in osteoarthritis: a histopathological and molecular study.

Objective: The infrapatellar fat pad (IFP) is considered a local producer of adipocytokines, suggesting a potential role in OA. The objective of this study was to evaluate the histopathological and molecular characteristics of OA IFPs compared with controls. Methods: The histopathological characteristics of IFPs were evaluated in patients undergoing total knee replacements and in control patients (without OA), considering the following parameters: presence of inflammatory cells, vascularization, adipose lobules dimension and thickness of the interlobular septa. Immunohistochemistry was performed to evaluate VEGF, monocyte chemotactic protein 1 (MCP-1) and IL-6 proteins. Quantitative real time PCR was performed to evaluate the expression levels of adipocytokines in the OA IFPs. Results: OA IFPs showed an increase in inflammatory infiltration, vascularization and thickness of the interlobular septa compared with controls. VEGF, MCP-1 and IL-6 proteins were higher in OA IFPs compared with in controls. Inflammatory infiltration, hyperplasia, vascularization and fibrosis were increased in OA IFP synovial membranes compared with in those of controls. VEGF protein levels were associated with an increased number of vessels in the OA IFPs, while MCP-1 and IL-6 protein levels were associated with higher grades of inflammatory infiltration. Leptin levels were positively correlated with adiponectin and MCP-1expression, while adiponectin positively correlated with peroxisome proliferative activated receptor gamma, MCP-1 and IFP vascularity. MCP-1 showed a positive correlation with peroxisome proliferative activated receptor gamma. IFP lobules dimensions were positively correlated with IL-6 expression and negatively with thickness of interlobular septa. VEGF mRNA levels were positively correlated with increased synovial vascularity. Conclusions: OA IFPs and synovial membranes are more inflamed, vascularized and fibrous compared with those of control patients (without OA).

Abnormal perfusion in patellofemoral subchondral bone marrow in the rat anterior cruciate ligament transection model of post-traumatic osteoarthritis: a dynamic contrast-enhanced magnetic resonance imaging study.

OBJECTIVE: Although anterior cruciate ligament (ACL) injury is a well-recognized risk factor for developing knee post-traumatic osteoarthritis (PTOA), the process in the patellofemoral (PF) joint after ACL injury is still under-researched. Our aim was to investigate the perfusion changes in PF subchondral bone marrow in the rat ACL transection (ACLX) model of PTOA using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). DESIGN: Eighteen male Sprague Dawley rats were randomly separated into three groups (n = 6 each group): a normal control group and groups receiving ACLX and sham-surgery, respectively, in the right knee. Perfusion parameters in the patellar and femoral subchondral bone marrows of all rats were measured on DCE-MRI at 0, 4, 8, and 16 weeks after respective treatment. After the last MRI at week 16, the rats were sacrificed and their right knees were harvested for histologic examination. In addition, to observe the long-term histologic change in PF joints, 9 additional rats (n = 3 in each group) were included and sacrificed at week 32 for histologic examination. RESULTS: In the ACLX group vs the sham and control groups, the perfusion parameters were significantly changed in both patellar and femoral subchondral bone marrows at week 16. Histologic examination revealed cartilage defects in ACLX rats at 32 weeks after surgery. CONCLUSIONS: These data point to a possible functional relationship between subchondral bone marrow perfusion abnormalities and cartilage breakdown in PTOA. Moreover, the perfusion parameters derived from DCE-MRI can potentially serve as biomarkers of early OA.

Quantitative assessment of patellar vascularity following bone-patellar tendon-bone autograft harvest for ACL reconstruction.

PURPOSE: Recent anatomic studies have suggested that the dominant arterial supply of the patella enters through the inferior pole. Based upon these findings, we hypothesized that bone-patellar tendon-bone graft harvest can significantly diminish patellar vascularity. METHODS: Nine matched pair cadaveric knee specimens (mean age 47.4 years) were dissected and cannulated. A single knee was selected to undergo routine graft harvest, and the contralateral knee was left intact to serve as a control. Gadolinium was injected, and magnetic resonance imaging (MRI) signal enhancement was quantified to determine differences in uptake. Each matched pair was subsequently injected with a urethane polymer compound and dissected to correlate vessel disruption with MRI findings. RESULTS: We identified two predominating patterns of vessel entry. In one pattern, the vessel entered the inferomedial aspect (five o'clock/right, seven o'clock/left) of the patella and was disrupted by graft harvest in 2/9 (22.2 %) pairs. In the second pattern, the vessel entered further medial (four o'clock/right, eight o'clock/left) and was not disrupted (7/9, 78.8 %). The mean decrease in gadolinium uptake following disruption of the predominant vessel measured 56.2 % (range 42.6-69.5 %) compared to an average decrease of 18.3 % (range 7.1-29.1 %) when the dominant arterial supply to the inferior pole remained intact (p < 0.04). CONCLUSION: Medial entry of the predominant vessel precluded vessel disruption. Disruption of the dominant arterial supply can result in a significant decrease in patellar vascularity. Modification of graft harvest techniques and areas of surgical dissection should be explored to minimize vascular insult. Further correlation with clinical studies/outcomes is necessary to determine a potential association between vascular insult and anterior knee pain.

The effect of infrapatellar fat pad resection on outcomes post-total knee arthroplasty: a systematic review.

INTRODUCTION: The infrapatellar fat pad (IPFP) is resected in approximately 88 % of total knee arthroplasty (TKA) surgeries. The aim of this review is to investigate the impact of the IPFP resection on clinical outcomes post-TKA. MATERIALS AND METHODS: A systematic search of five major databases for all relevant articles published until May, 2015 was conducted. Studies comparing the effect of IPFP resection and preservation on outcomes post-TKA were included. Each study was then assessed individually for level of evidence and risk of bias. Studies were then grouped into post-operative outcomes and given a level of evidence ranking based on the collective strength of evidence. RESULTS: The systematic review identified ten studies suitable for inclusion, with a total of 10,163 patients. Within these ten studies, six post-operative outcomes were identified; knee pain, vascularisation of the patella, range of motion (ROM), patella tendon length/patella infera, wound complications and patient satisfaction. Moderate evidence increased knee pain with IPFP resection post-TKA was found. Conflicting evidence was found for patella vascularisation and patellar tendon length post-TKA. Moderate evidence for no difference in ROM was found. One low quality study was found for wound complications and patient satisfaction. CONCLUSIONS: This systematic review is limited by the lack of level one randomised controlled trials (RCTs). There is however moderate level evidence that IPFP resection increases post-operative knee pain. Further level one RCTs are required to produce evidence-based guidelines regarding IPFP resection. Systematic Review Level of Evidence: 3.

Bone marrow changes related to disuse.

OBJECTIVES: To evaluate bone marrow changes on knee magnetic resonance imaging (MRI) in patients with 3- to 6-week-long period of unloading. METHODS: MRI knee examinations were performed in 30 patients (14 men, 16 women; aged 20-53 years) at baseline and 5-10 weeks after immobilisation of the ipsilateral lower extremity; subsets of patients were examined at additional time-points. Ten volunteers (4 men, 6 women; aged 20-50 years) were studied as control cohort at two time-points. Bone marrow signal abnormalities were analysed according to: (1) severity, (2) signal alteration relative to hyaline cartilage, (3) morphology, (4) increased vascularity in the knee joint and (5) T1-signal alteration. Spearman's rank correlation test (SRC) and Kendall's tau (KT) were used to compare individual scores. RESULTS: All 30 patients presented abnormal bone marrow findings after unloading, which reached a peak at 10-25 weeks (P <0.001). These findings decreased within 1 year (P < 0.001). High scores of severity were associated with confluent and patchy patterns of bone marrow (SCR = 0.923, P < 0.001 and KT = 0.877, P <0.001). CONCLUSIONS: Signal abnormalities of the bone marrow related to unloading are consistent findings and most prominent 10-25 weeks following immobilisation when both confluent and patchy hyperintense patterns are present.

Radiologically hyperdense zones of the patella seem to be partial osteonecroses subsequent to fracture treatment.

The blood supply to the proximal patella is provided primarily via intraosseous vessels from the inferior patella. Two vascular systems within the patella are distinguished: Tiny arteries penetrate the middle third of the anterior patellar surface via vascular foramina and continue in a proximal direction. Additional vessels enter the patella at its distal pole, between the patellar ligament and the articular surface, and also run proximally. As a result of the double vascular supply to the distal portion and the vulnerable blood supply to the proximal part, localized osteonecroses subsequent to fracture may occur within the patella and nearly exclusively affect the upper portion of the patella. Such focal regions of osteonecrosis may appear radiographically as localized regions of hyperdensity within the patella. The aim of this study was to investigate the extent to which radiologically hyperdense areas, possibly representing localized osteonecrosis, may occur subsequent to surgical treatment of a patella fracture and the influence that they have on the outcome of the fracture. Retrospective analysis of 100 patients who had been treated operatively for a patella fracture from January 1998 to December 2008 was conducted. The subjective pain rating, clinical scores, and patient satisfaction scores were recorded. Existing X-rays were assessed with regard to possible increased radiological dense areas. After an average of 60.61 ( ± 33.88) months, it was possible to perform a clinical follow-up on 60 patients aged 45.48 ( ± 18.51) years. Radiographic follow-up of all patients revealed that nine patients (9%) exhibited a hyperdense area in the proximal patella portion. X-rays showed radiopaque areas between 1 and 2 months after surgery. In seven cases, the radiological finding disappeared after six months. In two patients with persisting radiologically dense areas, bone necrosis was verified by means of magnetic resonance imaging (MRI) examination and a histological assessment, respectively. The clinical outcome of these patients with a hyperdense area on the patella, in this small series, was not shown to be worse than those who demonstrated normal healing. Radiologically hyperdense areas subsequent to patella fracture may represent partial osteonecrosis caused by localized vascular compromise. This was confirmed by MRI and histological examinations in two patients with persistent hyperdense lesions. The clinical outcome of patients with hyperdense zones seems to be poorer than that of patients without such findings, but no statistical difference was shown in this small series. It is possible that earlier surgical treatment and thus a shorter ischemic period as well as tissue-conserving operative techniques could prevent the occurrence of partial necroses. This hypothesis would require further study.

A comparison of patellar vascularity between the medial parapatellar and subvastus approaches in total knee arthroplasty.

A complication of total knee arthroplasty is patellar avascular necrosis. Surgical approaches for total knee arthroplasty include the medial parapatellar approach (MPa) and, less commonly, the subvastus approach (SVa). The argument that SVa retains better patellar vascularity than the MPa was investigated on 20 participants, (SVa, n = 10; MPa, n = 10) 18 months postoperatively. Outcomes were a radionuclide bone imaging technique, a new bone vascularity scale, and an anterior knee pain numerical assessment scale. Results indicated no significant difference between groups on imaging (P = .935), the components of the bone vascularity scale, or anterior knee pain (P > .999). The SVa appears to offer no benefit over the MPa in terms of patellar vascularity or anterior knee pain.

Anterior knee pain after total knee arthroplasty: does it correlate with patellar blood flow?

PURPOSE: Total knee arthroplasty (TKA) disturbs patellar blood flow, an unintended accompaniment to TKA that may be a cause of postoperative anterior knee pain. We examine whether disrupted patellar blood flow correlates with anterior knee pain following TKA. METHODS: In 50 patients (21 men, 29 women) undergoing TKA, we compared patellar blood flow at flexions 0° to 30°, 60°, 90°, and 110° before and after medial parapatellar arthrotomy to pre- and postoperative anterior knee pain scores by means of a laser Doppler flowmeter (LDF) probe. Anterior knee pain was assessed using the pain intensity numeric rating scale (NRS) of 0-10 (0-no, 10-worst pain). Based on the NRS pain values, patients were divided into two main groups: group A (n = 34) with no pain or discomfort (NRS range 0-4) and group B (n = 16) with anterior knee pain (NRS range 5-10). RESULTS: Patients of group B demonstrated a significant decrease in blood flow before arthrotomy at flexions from 0° to 90°, and 110° and from 0° to 60°, 90°, and 110° after arthrotomy. For group A, a significant decrease in blood flow was detected at flexions from 0° to 90°, and 110° before and after arthrotomy. For both groups, medial arthrotomy did not have a statistically significant influence on patellar blood flow (margin of significance P < 0.05). Prior to TKA, 16 of the 50 patients of group B (32%) complained of anterior knee pain (mean NRS 7.1 ± 1.7). At 2-year follow-up, pain significantly decreased (NRS 3.1 ± 2.1) and only 4 of the 16 patients (25%) complained of moderate anterior pain (average NRS 5.7 ± 0.5), while 8 of 16 (50%) patients reported discomfort (mean NRS 3.5 ± 1.8) around the patella. Patients in group A also demonstrated a significant decrease in pain intensity (from NRS 1.5 ± 1.4 preoperatively to NRS 0.4 ± 1.5 at 2-year follow-up). Statistical analysis demonstrated no statistically significant correlation between pre-arthrotomy/post-arthrotomy patellar blood flow and the presence of preoperative and postoperative anterior knee pain. Only the degree of flexion had an influence on patellar blood flow. CONCLUSION: Medial arthrotomy had no direct significant effect on patellar blood flow, and the diminished blood flow did not correlate with postoperative anterior knee pain. However, a significant correlation was revealed between patellar blood flow and the degree of flexion: in almost a quarter of patients, blood flow dropped to zero at flexions of 100° and above.

Changes to patellar blood flow after minimally invasive total knee arthroplasty.

Standard surgical exposure reduces blood flow to the patella during total knee arthroplasty (TKA). Reduction of patellar blood flow has resulted in patellofemoral complications including osteonecrosis and patellar fracture, necessitating revision surgery. In TKA, avoiding patellar eversion is one type of minimally invasive surgery (MIS) technique. This study is the first to measure patellar blood flow during MIS TKA with the knee in both extension and 90 degrees of flexion followed by lateral retraction and then eversion of the patella. Patellar blood flow was measured using laser Doppler flowmetry in 40 patients during MIS TKA. A significant reduction in flow was noted when the leg was flexed from full extension to 90 degrees . Eversion of the patella reduced patellar blood flow. MIS TKA without patellar eversion may be useful for preventing a reduction in patellar blood flow.

Anatomical landmark of descending genicular artery for minimidvastus approach of the knee.

OBJECTIVE: To determine the anatomical course of descending genicular artery and to identify a safety zone for minimidvastus approach. MATERIAL AND METHOD: Forty-eight knees from twenty-four fresh cadavers were dissected to identify the descending genicular artery, and to measure the distance between such artery and superomedial pole of the patella as well as the entry angle of such artery to the perpendicular line of the vertical axis of the patella. RESULTS: The average distance between the descending genicular artery and superomedial pole of the patella was 8.1 millimeters (0-19 millimeters) and the average entry angle of such artery to the patella was 44.5 degrees (32-60 degrees). CONCLUSION: The safety zone for splitting the vastus medialis in minimidvastus approach was the angle of not more than 32 degrees from the perpendicular line of the vertical axis of the patella. However, there is no safety zone in term of the distance between the dissected vastus medialis and the superiormedial border of the patella.

Qualitative and quantitative analysis of patellar vascular anatomy by novel three-dimensional micro-computed-tomography: Implications for total knee arthroplasty.

BACKGROUND: The blood supply of the patella is highly related to patellofemoral complications in total knee arthroplasty. The purpose of this study was to determine (1) the dominant blood supply for the patella and (2) the anatomic characteristics of the extraosseous and intraosseous vascularity of the patella. METHODS: In 13 fresh cadaveric knees, the femoral arteries were cannulated and perfused with a lead-based contrast agent. Patellae were harvested and scanned with a micro-computed-tomography scanner. The three-dimensional microarchitecture of the vascularity was reconstructed and evaluated. For the volumetric analysis, the vessel densities of the anterior, central and subchondral sides were compared. RESULTS: A well-anastomosed prepatellar vascular network was found to cover the anterior surface of the patella, with main arteries from multiple directions, yielding 18.8 ±â€¯3.1 (standard deviation) intraosseous branches into the patella. Along the intraosseous branches of the prepatellar vascular network, vessel density decreased (P < 0.001) by 0.54 ±â€¯0.29% on the anterior side, 0.40 ±â€¯0.24% on the central side and 0.23 ±â€¯0.19% on the subchondral side. Arteries in the infrapatellar fat pad produced 5.1 ±â€¯1.8 intraosseous branches, mainly located in the distal apex. Almost no arteries penetrated into the patella from the quadriceps tendon, patellar ligament or medial/lateral retinaculum. CONCLUSION: The prepatellar vascular network is the dominant blood supply. Close exposure and extensive dissection around the patella should be avoided to preserve the prepatellar vascular network. The infrapatellar fat pad was recommended to be preserved when a lateral reticulum release was performed.

Patellar blood flow during knee arthroplasty surgical exposure: Intraoperative monitoring by laser doppler flowmetry.

Patellofemoral complications following knee arthroplasty are a well-known problem. Patellar ischemia has been suspected to be causative for fracture, anterior knee pain, and patella component failure. The purpose of this study was to assess the influence of knee arthroplasty surgical dissection on patellar blood flow. Patellar blood flow was measured by means of intraosseous laser Doppler flowmetry (LDF) in 10 patients undergoing total knee arthroplasty by a standard medial parapatellar approach. The initial blood flow was 121.6 +/- 114.7 AU. The signal significantly decreased by 71% (p = 0.0051) when the knee was flexed and lost the pulsatile signal pattern in 80%. After arthrotomy, the signal was 100.1 +/- 120.3 AU in extension. The lowest signal was found in flexion and eversion of the patella (mean, 18 +/- 10.7 AU) and all signals lost pulsatility. As compared to the initial values, completion of the soft tissue dissection did not lead to a significant change of the blood flow signal (121.3 +/- 104.8; p = 0.6835). Flexion of the knee joint markedly reduced patellar perfusion. Standard medial parapatellar approach did not significantly change patellar blood flow. This study does not support the theory of postoperative patellar ischemia as a cause of anterior knee pain or patellofemoral problems.

Intraosseous innervation of the human patella: a histologic study.

BACKGROUND: The soft tissue structures surrounding the human knee joint have been the subject of extensive anatomic study. The detailed histologic findings within the bone of the human patella, however, have not been systematically studied. While the nerves supplied to the periarticular soft tissues have been very well documented, the nerves supplied to the interior of the bony patella have never been described. HYPOTHESIS: This study tests the hypothesis that the patella contains an intraosseous nerve network. Further, the authors investigate the anatomic location of these intraosseous nerves to better understand their possible clinical relevance. STUDY DESIGN: Descriptive laboratory study. METHODS: Ten matched pairs of cadaveric patellae (left and right patellae from the same individual; 20 total) were prepared for evaluation by hematoxylin and eosin staining using a technique that allows the creation of complete, large histologic sections of individual patellae. The matched specimens were dissected free of soft tissue and then sectioned using a diamond-wafering saw into 3-mm sagittal (left patella) and transverse (right patella) sections. Sections were then decalcified and whole-mounted into paraffin blocks for further sectioning using a large-format microtome. All 20 specimens were prepared for evaluation. Age at death averaged 80 years (range, 64-91). All specimens demonstrated at least grade II chondromalacia. RESULTS: Nineteen of 20 (95%) specimens demonstrated intraosseous nerves. Of 248 sections studied, 116 (47%) demonstrated intraosseous nerves, with 227 individual nerves identified. The density of intraosseous nerves was greatest in the medial and central portions of the patella, with a significant paucity identified laterally. CONCLUSION: The primary intraosseous innervation of the patella derives from a medially based neurovascular bundle. CLINICAL RELEVANCE: A better understanding of the nerves within the human bony patella may improve understanding the patho-physiology of anterior knee pain syndromes.

Intraosseous blood flow of the everted or laterally-retracted patella during total knee arthroplasty.

Patellofemoral problems are relatively common sequelae of total knee arthroplasty (TKA), and many factors contribute to these complications. Vascular compromise has been identified as a possible contributing factor, and was selected for further investigation in the present study. Laser Doppler Flowmetry was used to quantify patella intraosseous blood flow in vivo during TKA surgery without the use of a tourniquet. Flow was measured after medial parapatellar arthrotomy, and compared to flow during patella eversion and lateral retraction. Patella blood flow during eversion was reduced to 13% of baseline values (p<0.05). A significantly greater proportion of flow was preserved during lateral retraction (53%), although the reduction from baseline was still significant (p<0.05). A statistically significant difference in flow (60% of baseline) was also noted when the leg was flexed from full extension to 90 degrees (p<0.05) with the patella in its normal anatomical alignment. In this study, we have demonstrated the sensitivity of the patella blood supply to knee flexion angle and patella dislocation technique, particularly to patella eversion. These may be important findings with regard to surgical technique for TKA.

[Remote outcomes of endoscopic dissection of crural perforating veins in chronic venous insufficiency].

We studied the long-term results following endoscopic dissection of crural perforating veins (EDCPV) in chronic venous insufficiency. The study comprised a total of 36 patients (41 lower limbs) who had endured the intervention concerned. The term having passed from the time of the operation till the moment of assessing the obtained outcomes varied from I to 10 years. Ultrasonographic angioscanning within the zone of the previous intervention revealed 38 perforating veins on 3.1 of the postoperative lower limbs (75.6 %). Amongst the veins revealed, most frequently encountered were Cockett's perforants (the so-called Cockett II) in the typical place - the lower third along the medial surface of the crus (29 cases). In five cases, perforants were revealed in the middle third of the crus, which located in the close proximity from the edge of the tibia (Cockett III). Perforants on the posterior crural surface were revealed on four extremities. Only 22 veins on 20 lower limbs (48.8%) turned out incompetent. The median access to perform EDPCV was used in 28 cases (68.3%); within the zone of the operative intervention performed we found 24 perforating veins, with 15 of these being incompetent. After EDPCV performed from the posterior or posterior-medial approaches on 13 limbs (317%), we revealed 14 perforating veins (of these, 7 - incompetent). Despite this, the patients regarded the effect obtained as either good or satisfactory in 79% of cases. The obtained findings suggest that thorough diagnosis of perforating reflux and improvement of the technique of endoscopic dissection thereof should be required. Along with it, it is also necessary to attentively examine the problem of the true role of the low vein-venous shunt in the pathogenesis of vein chronic diseases.

Non-invasive continuous estimation of blood flow changes in human patellar bone.

A photoplethysmographic (PPG) technique to assess blood flow in bone tissue has been developed and tested. The signal detected by the PPG consists of a constant-level (DC) component-which is related to the relative vascularization of the tissue-and a pulsatile (AC) component-which is synchronous with the pumping action of the heart. The PPG probe was applied on the skin over the patella. The probe uses near-infrared (804 nm) and green (560 nm) light sources and the AC component of the PPG signals of the two wavelengths was used to monitor pulsatile blood flow in the patellar bone and the overlying skin, respectively. Twenty healthy subjects were studied and arterial occlusion resulted in elimination of PPG signals at both wavelengths, whereas occlusion of skin blood flow by local surface pressure eliminated only the PPG signal at 560 nm. In a parallel study on a physical model with a rigid tube we showed that the AC component of the PPG signal originates from pulsations of blood flow in a rigid structure and not necessarily from volume pulsations. We conclude that pulsatile blood flow in the patellar bone can be assessed with the present PPG technique.

Histopathological abnormalities in painful bipartite patellae in adolescents.

The purpose of this study was to clarify the etiology of painful bipartite patella in adolescents by histopathological examination of excised specimens. We performed excision of a fragment of painful bipartite or tripartite patella from six patients (six knees). The articular cartilage, interposed tissue, bone, and bone marrow of the excised specimens were histologically examined. The articular cartilage was intact in all but two patellae. The predominant composition of the interposed tissue was fibrous tissue in one patient; fibrous tissue and fibrocartilage in four patients; and fibrous tissue, fibrocartilage, and hyaline cartilage in one patient. In the interposed tissue, diffuse degenerative and necrotic fibrocartilage was observed in four patients and focal necrotic fibrocartilage was seen in two patients. In all patients, the central region of the interposed tissue almost completely lacked blood vessels. Other histological features of the interposed tissue included necrosis of the trabecular bone in three patients, irregularly shaped spicules of immature bone in three patients, and fragments of hyaline cartilage in two patients. In all patients the bone marrow adjacent to the interposed tissue showed numerous small blood vessels, and trabecular bone surfaces and the fibrocartilage surface adjacent to this bone marrow was scalloped and lined with numerous osteoclasts. The striking histopathological features of the interposed tissue were fibrous tissue and necrosis of the fibrocartilage. These abnormalities may ultimately lead to the failure of an accessory ossification center to unite with the main portion of the patella.

Neovascularisation and pain in jumper's knee: a prospective clinical and sonographic study in elite junior volleyball players.

BACKGROUND: The nature of tendon neovascularisation associated with pain over time has not been studied. OBJECTIVE: To prospectively study the patellar tendons in elite junior volleyball players. METHODS: The patellar tendons in all students at the Swedish National Centre for high school volleyball were evaluated clinically and by ultrasonography (US) and Power Doppler (PD) sonography. RESULTS: Altogether 120 patellar tendons were followed for 7 months. At inclusion, jumper's knee was diagnosed clinically in 17 patellar tendons. There were structural changes on US in 14 tendons, in 13 of which PD sonography showed neovascularisation. There were 70 clinically normal tendons with normal US and PD sonography, 24 clinically normal tendons with abnormal US but normal PD sonography, and nine clinically normal tendons with abnormal US and neovascularisation on PD sonography. At 7 month follow up, jumper's knee was diagnosed clinically and by US in 19 patellar tendons, in 17 of which there was neovascularisation. Three of nine clinically normal tendons with structural changes and neovascularisation at inclusion developed jumper's knee. Two of 24 tendons clinically normal at inclusion, with abnormal US but normal PD sonography, developed jumper's knee with abnormal US and neovascularisation on PD sonography. A total of 20 clinically normal tendons with normal US and PD sonography at inclusion developed structural tendon changes and 12 of these also developed neovascularisation. CONCLUSIONS: The clinical diagnosis of jumper's knee is most often associated with neovascularisation in the area with structural tendon changes. The finding of neovessels might indicate a deterioration of the condition.