a Departamento de Ortopedia, Santa Casa de São Paulo, São Paulo, SP, Brasil
b Serviço de Ortopedia e Traumatologia, Hospital Israelita Albert Einstein, Universidade Federal de São Paulo (Unifesp), São Paulo, SP,Brasil
c Instituto de Ortopedia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo, SP, Brasil
d Escola Paulista de Medicina, Universidade Federal de São Paulo (Unifesp), São Paulo, SP, Brasil
Introduction
Knee arthroscopy is among the most commonly performedsurgical procedures for treating sports injuries.1Arthroscopicreconstruction of the anterior cruciate ligament (ACL) aloneaccounts for 75,000 cases per year in the United States.
Use of arthroscopy has grown because it entails less injuryto soft tissues in order to perform the procedure. With pre-cise guides and use of cameras, it is possible to increase thesurgeon's efficacy and diminish the damage to the patient.However, direct viewing of the surrounding structures is nolonger done routinely, which may lead to unexpected injuries.One example of this is the reports of pseudoaneurysms afterarthroscopic procedures have been performed on the knee.
Pseudoaneurysms are caused by incomplete injury to thearterial wall, with extravasation of blood that is contained bythe surrounding tissues. This blood accumulation is organizedin a fibrous capsule with the presence of turbulent flow insideit5(Fig. 1).
Over the course of the natural evolution of pseudoa-neurysms, they may increase in size until they rupture orcause ulceration in the neighboring structures.
Because pseudoaneurysms are a rare complication, a highdegree of suspicion is needed for an early diagnosis to bemade.7The literature of pseudoaneurysms subsequent toarthroscopic procedures on the knee is sparse and only a fewreports exist.
The objective of this study was to review all the casesof pseudoaneurysm in the literature resulting from predom-inantly arthroscopic procedures on the knee (treatmentsrelating to ACL, meniscal injuries, synovectomy and osteo-chondritis) and report on a case of pseudoaneurysm that wetreated.
Method
A bibliographic survey was conducted among scientific articlespublished in Brazilian and foreign periodicals over the last 23years, using the PubMed and Bireme databases. The surveywas conducted in two stages on the PubMed website: firstly,using the terms pseudoaneurysm OR false aneurysm and knee ORcruciate OR arthroscopy; and secondly, using pseudoaneurismaOR falso aneurisma and joelho OR cruzado OR artroscopia. Inthe Bireme database, the terms were used separately. Tencombinations would be needed in order to have a simi-lar search, as follows: pseudoaneurysm knee, pseudoaneurysmcruciate pseudoaneurysm arthroscopy, false aneurysm knee, falseaneurysm cruciate, false aneurysm arthroscopy, pseudoaneurismajoelho, pseudoaneurisma cruzado, pseudoaneurisma artroscopia.
Reports on cases of pseudoaneurysm of the knee sub-sequent to predominantly arthroscopic procedures wereselected (cases relating to ACL, meniscal injuries, synovec-tomy and osteochondritis). Some other articles were foundthrough examining the reference lists of the articles selected.No prospective or retrospective studies on this subject werefound, and not even any case series. The maximum number ofcases reported per article was three.8The review was checkedup to June 24, 2011.
Articles in five languages were found: English (31), French(3), Portuguese (1), German (1) and Serbian (1). The points ofinterest in the article in Serbian were kindly translated intoEnglish for us so that they could be included in this study.
For the purposes of the present study, it was not of inter-est to review the opinions of specialists but, rather, the casereports, given that there was no stronger evidence than this,on this subject, up to the time of this study.
Case report
Our patient was a 17-year-old male who presented a completetear of the ACL subsequent to twisting his right knee whileplaying handball. Arthroscopic reconstruction of the ACL wasperformed using a graft from the flexor tendons of the knee.
Two and a half years later, he twisted his right kneeagain, and this led to a complaint of instability and recurrentepisodes of joint effusion. He sought assistance at the ortho-pedics service of the Sports Traumatology and ArthroscopyCenter, where a diagnosis of a new ACL injury was made. Sur-gical revision of the reconstruction was therefore scheduled.The graft used was from the tendon of the quadriceps muscle.Extensive repair to the femoral intercondylar area was alsoperformed.
On the first postoperative day, the patient complainedabout joint effusion in the knee and about the presence of apulsatile mass in the inferomedial region of the right knee thatwas causing pain and discomfort. An echo Doppler test con-firmed the clinical diagnosis of pseudoaneurysm. The patientwas sent to the vascular surgery department, where emboliza-tion of the pseudoaneurysm was performed. Arteriographyshowed that the pseudoaneurysm was in the inferomedialgenicular artery. The patient then made a good recovery with-out any intercurrences.
Review of the literature
Forty-seven cases in forty articles were surveyed.4,6-43In addi-tion, our single case described above was included in the data.The first case of pseudoaneurysm subsequent to an arthro-scopic procedure on the knee dates back to 1979.13We do notbelieve that any older cases exist, because arthroscopy onlybecame popular in the 1990s.
The first case of pseudoaneurysm subsequent to an arthro-scopic procedure on the knee dates back to 1979.13We do notbelieve that any older cases exist, because arthroscopy onlybecame popular in the 1990s.
From the present investigation, 75% of the patients weremale and 25% were female, and their ages ranged from 13 to69 years. The mean age of the male patients was 32.30 years(14.92) and the median was 31 years. The mean age of thefemale patients was 33.87 years (21.19) and the median was32.50.
The diagnoses found in the studies investigated includedthe following: meniscal disorders (60.41%), ACL (22.91%), syn-ovitis (6.25%), arthrosis (4.16%) and also osteochondritis andBaker's cyst (Table 1).
The time taken to reach the diagnosis ranged from one to180 days, with a mean of 11.90 days (35.25) and median of 11days.
Resection was the treatment most frequently seen inthe literature, accounting for 75% of the cases, followed byembolization, with 20.83%. Among the cases studied, one wasresolved using a percutaneous prosthesis and the treatmentused was not specified in one other case.
The arteries most affected were the popliteal artery(45.83%) and the inferomedial genicular artery (20.83%)
To detect the pseudoaneurysm, complementary exam-inations were used, such as: echo Doppler, arteriography,computed axial tomography, angiotomy with contrast,
aspiration and even inspection by means of surgery. Thecomplementary examinations most frequently requested inthe studies reviewed here were arteriography (41.66%) andecho Doppler (39.58%).
Among the 48 patients evaluated in the different studies, 34presented pain, 29 had a pulsatile tumor, 11 had edema of thecalf, eight had a non-pulsatile tumor and one had paresthesia(Table 3).
Discussion
Knee arthroscopy is a safe and commonly performed proce-dure, with few complications. The incidence rate of nerve andvascular injuries described subsequent to arthroscopy rangesfrom 0.56% to 0.80% in large series. This low incidence isperhaps one of the reasons why vascular complications aredifficult to diagnose and are diagnosed late.
The greater incidence of pseudoaneurysms found amongmen (75%) is due to the fact that these knee injuries occurin young people practicing sports activities, who are mostlymen. However, the number of women who practice sports isgrowing and the ratio of injuries per hour of sports practice islower among women.
The risk of arterial injury during knee surgery is related toknee anatomy, since the vessels are close to the joint capsule.During knee flexion, the arteries are moved forwards, towardthe posterior capsule, and the popliteal artery is then sepa-rated from the capsule by a thin layer of fat, which may bethe reason why the popliteal artery is so frequently affected.Since the posterior part of the knee is difficult to view dur-ing arthroscopy and use of a tourniquet makes it impossibleto view bleeding immediately, these vascular injuries are noteasily diagnosed. For this reason, the limb circulation shouldbe carefully checked after the surgery.
Rupture of the artery wall is necessary for a pseudoa-neurysm to develop. However, a pseudoaneurysm may formafter arthroscopy without any history of penetration of theknee capsule or vessel wall. One hypothesis for explainingthis relates to the high levels of stress applied to the kneestructures and arteries during the arthroscopic procedure. Forexample, this can be seen in arthroscopic surgery to treatinjuries to the medial meniscus, in which in some cases itis necessary to use a high degree of varus force in order toachieve good viewing. Another hypothesis that is more plau-sible is that partial injury to the artery may occur at the time ofconstructing the access routes for the arthroscopy. The accessportal is opened on the anteromedial and anterolateral faceof the knee, close to the superior genicular arteries. There isalso the access route for graft harvesting, which in the case ofpatellar grafts and grafts from the knee flexor tendons is closeto the inferior genicular arteries.
Knowledge of the vascular anatomy of the knee is essen-tial in order to avoid this type of complication. The followingarteries supply the knee joint: the genicular branches of thefemoral, popliteal and anterior tibial recurrent arteries and thedescending branch of the lateral circumflex femoral artery.The majority of the blood supply for both the ACL and theposterior cruciate ligament comes through ligament branchesof the medial genicular artery (which also supplies the syno-vial membrane and the lateral margin of the menisci) andalso through some terminal branches of the inferomedial andinferolateral genicular arteries. These vessels branch out toform a rich synovial plexus that contributes to a network ofintracapsular vessels that surround the ACL.
Arthroscopic surgery that requires bone tunnels alsorequires the use of guides that ensure that the holes are drilledthrough the bones is the correct places. Tunnel constructionis usually started by means of a steel wire of diameter 2 mm
mm(guidewire). After the surgeon has decided that the positioningis correct, a cannulated drill bit is passed along this guidewirein order to drill the bone. Here, two important points arisewith regard to discussing pseudoaneurysms. The first relatesto soft-tissue penetration, in that these wires are passed intothe soft tissues blindly, which may lead to partial injuries toarteries. The second relates to precision, in that if poor qualitymaterials are used, this may lead to guidewire into unplannedlocations, even if the technique is applied correctly.
Pain was the commonest symptom among the casesreported, but its nonspecific nature sometimes may nothave helped in making the diagnosis. Pulsatile tumors andhemarthrosis with arterial blood were present in many of thecases and their presence led to a high degree of suspicion.In some cases, the tumor was described as non-pulsatile, butnone of the authors of these case studies discussed this.
The diagnosis can be made clinically through the presenceof a painful pulsatile mass of growing size, in association withpalpable fremitus and a systolic heart murmur. The diagno-sis can be confirmed by means of echo Doppler, magneticresonance imaging and arteriography.37The following com-plications of pseudoaneurysms may occur: hemorrhage, painand space occupation effects such as neurological compres-sion, neuralgia, venous compression and thrombosis.
A high degree of suspicion needs to be maintained in orderto avoid delayed diagnosis. The median length of time takento make the diagnosis was found to be 11 days, but it rangedfrom one day to 10 weeks after the initial procedure.
Although rare, pseudoaneurysm is a risk that is inherent toarthroscopic surgery. All patients need to be notified regardingthe vascular risks, even in cases of small-sized procedures.
Conflicts of interest
The authors declare no conflicts of interest.
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