A evolução do conhecimento acerca das funções dos meniscos e do tratamento das suas lesões, impulsionada pelo advento da cirurgia artroscópica, consagrou e popularizou a meniscectomia por esta via, por ser uma técnica menos invasiva, com menor morbidade e menores custos hospitalares, a ponto de torná-la, atualmente, a cirurgia ortopédica mais frequentemente realizada no mundo. Embora a maior parte dos pacientes submetidos a esta intervenção cirúrgica tenha resultados favoráveis e resolução rápida dos sintomas, percebe-se que parte considerável dos pacientes, especialmente os mais idosos, não apresenta uma evolução póscirúrgica satisfatória, apresentando piora dos sintomas e, eventualmente, necessitando de nova cirurgia. Partindo da hipótese que em determinados pacientes a meniscectomia, em vez de tratar, precipita e acentua um desequilíbrio biomecânico do joelho, o autor realizou estudo observacional prospectivo não-controlado com 86 pacientes de ambos os gêneros, com idade superior a 50 anos (média de 60,2 ± 7,1 anos), submetidos à meniscectomia artroscópica para tratamento de lesão do menisco medial de natureza degenerativa, com o objetivo de determinar variáveis demográficas, clínicas, anatômicas e cirúrgicas relacionadas aos resultados desfavoráveis. As avaliações funcionais pré e pós-operatórias foram realizadas utilizandose o Índice do KOOS (Knee Injury and Osteoarthritis Outcome Score), aplicado a todos os pacientes antes da cirurgia e 60 meses depois. Após análise estatística dos resultados obtidos, o autor verificou que 10 fatores podem ser considerados preditivos das meniscectomias mediais artroscópicas neste grupo etário, sendo quatro fatores fortemente associados aos resultados desfavoráveis: lesão da raiz posterior do menisco medial, dor pré-operatória intensa, claudicação antes da cirurgia e tempo decorrido entre o início dos sintomas e a cirurgia; dois fatores foram considerados moderadamente associados aos resultados desfavoráveis: presença de edema de medula óssea na ressonância magnética (RM) préoperatória e duração da cirurgia; quatro fatores foram considerados associados de modo fraco aos resultados desfavoráveis: Índice de Massa Corporal (IMC) >= 30 kg/m2 , varismo do joelho, presença de cisto poplíteo na RM pré-operatória e extensão da ressecção do menisco medial / The evolution of knowledge concerning meniscal functions and the treatment of their injuries, boosted by the development of arthroscopic surgery, has established and popularized arthroscopic meniscectomy due to its less invasiveness, less post-operative morbidity and lower hospital costs, to the point it has become, nowadays, the most frequently performed orthopedic procedure in the world. Although the majority of patients undergoing this operation is quite pleased with the outcomes and with the prompt resolution of their symptoms, it is noticeable that a considerable amount of patients with meniscal injuries, mainly the older, does not have a satisfactory postoperative outcome, with worsening of symptoms after being operated on and occasionally requiring another surgery. Based on observations of his medical practice and on the assumption that meniscectomy, rather than treat, can hasten and accentuate a biomechanical imbalance of the knee in those patients, the author conducted an observational prospective uncontrolled study with 86 patients of both genders, aged over 50 years old (average 60.2 ± 7.1 years), who underwent arthroscopic meniscectomy for the treatment of degenerative medial meniscal lesions, aiming to determine demographic, anatomical, clinical and surgical variables related to poor outcomes. The functional pre and post-operative evaluations were performed using the KOOS index (Knee Injury and Osteoarthritis Outcome Score) applied to all patients before surgery and 60 months later. After statistical analysis of the results, the author found that 10 factors can be considered predictors of arthroscopic medial meniscectomy in this age group: four factors were strongly associated with unfavorable results - posterior root lesion of the medial meniscus, intense pre-operative pain, claudication before surgery and time elapsed between onset of symptoms and surgery; two factors were moderately associated with unfavorable results - bone marrow edema in preoperative magnetic resonance imaging (MRI) and surgery time length; four factors that were weakly associated with poor results - bone mass index (BMI) >= 30 kg/m2, varus knee, poplyteal cyst in pre-operative MRI and extension of meniscal ressection

<p>Uvod: magnetno rezonantni imidžing (MR) je u &scaron;irokoj uporebi u dijagnostici patolo&scaron;kih poremećaja ekstremiteta. Postoji interes da se redukuje vreme trajanja snimanja tokom pregleda kako bi se povećao komfor pacijenata i redukovali problemi koji su u vezi sa klaustrofobijom i artefaktima koji nastaju pri pomeranju pacijenta tokom dugih snimanja. Trodimenzionalne (3D) izovoksel sekvence pokazale su značajne mogućnosti u redukciji vremena snimanja MR pregledom zgloba kolena bez smanjenja kvaliteta dijagnostičkih mogućnosti. Cilj: uporediti dijagnostičke mogućnosti rutinskog, 2D MR protokola, na 3.0 Tesla MR aparatu, sa 3D True fast imaging, TrueFISP, izovoksel sekvencom u detekciji hondralnih o&scaron;tećenja, ruptura prednjeg ukr&scaron;tenog ligamenta (LCA), ruptura meniskusa i abnormalnosti subhondralne kosti, u korelaciji sa artroskopijom, kao referentnim standardom. Materijal i metode: Studija je odobrena od institucionalnog etičkog odbora. Pacijenti su informisani o studiji i potpisali pristanak za uče&scaron;će u istraživanju. 76 zgloba kolena kod 76 pacijenata (34 ženskog pola; prosečne starosti 36 godina) uključeno je u prospektivnu studiju, snimljeno je standardnim 2D MR protokolom snimanja i 3D TrueFISP sekvencom u sagitalnoj ravni. Svim pacijentima je urađena artroskopija u periodu od maksimum 30 dana nakon snimanja. Dva radiologa, nezavisno jedan od drugog, su evaluirala dobijene snimke. Preciznost u detekciji hondralnih o&scaron;tećenja, ruptura LCA i meniskusa, i abnormalnosti subhondralne kostne srži je određena podudarno&scaron;ću radiolo&scaron;kih i artroskopskih nalaza kao i proverom podudaranja ove dve metode snimanja. Rezultati: prosečna senzitivnost i specifičnost 3DTrueFISP sekvence je bila 75%, 94% respektivno, u dijagnostici o&scaron;tećenja hrskavice, 97%, 97% u detekciji ruptura LCA, 65%, 89% u postavljanju dijagnoze ruptura meniskusa, a dobra podudarnost radiolo&scaron;kih nalaza je dobijena u interpretaciji o&scaron;tećenja subhondralne kosti. Standardnim 2D MR protokolom prosečna senzitivnost i specifičnost je bila 70%, 93%, respektivno, u postavljanju dijagnoze hondralnih o&scaron;tećenja, 94% i 100% u postavljanju dijagnoze rupture LCA, 65%, 88% u detekciji ruptura meniskusa. Zaključak: dijagnostičke mogućnosti upotrebom 3DTrueFISP sekvence su uporedive sa standardnim, 2D, MR protokolom u snimanju zgloba kolena.</p> / <p>Introduction: Magnetic resonance imaging (MR) is widely used to assess internal derangements of the extremities. There is an interest in decreasing examination times to improve patient comfort and reduce the problems related to claustrophobia and motion artifacts, which occur more commonly with long examinations. The three-dimensional (3D) isovoxel true FISP sequence facilitates a noticeable reduction in acquisition time for MR imaging of the knee without reducing diagnostic performance. Objective: To compare the diagnostic performance of conventional, 2D, MR protocol, at 3.0 Tesla MR, with 3D water-excitation true fast imaging with steady-state precession, TrueFISP, an isotropic resolution sequence for detecting articular cartilage defects, anterior crucial ligament tears, meniscal tears and subhondral bone changes of the knee joint, with arthroscopy as reference standard. Materials and methods: The study was institutional review board approved. Written informed consent was obtained from all patients. 76 knees of 76 patients (34 females; mean age 36 years) were prospectively examined by using a conventional 2D MR protocol and sagittal 3D TrueFISP sequence. All patients underwent arthroscopy within a maximum period of 30 days after imaging. Two blinded readers evaluated the MR images. Accuracy for detection of cartilage defects, anterior cruciate ligament and meniscal tears, and subchondral bone abnormalities interobserver agreement, and intermethod agreement were calculated. Results: Overall sensitivity and specificity of 3DTrueFISP sequence were, respectively, 75%, 94% for diagnosis cartilage defects, 97%, 97%, for a diagnosis ACL tears, 65%, 89% for diagnosis of meniscal tears and with good interobserver agreement in interpretation of subhondral bone abnormalities. The standard MR protocol had overall sensitivities and specificities 70%, 93%, respectively, for diagnosis of cartilage defects, 94% and 100% for diagnosis ACL tears and 65%, 88% for diagnosis meniscal tears. Conclusion: The diagnostic perfomance of knee MR imaging performed by using a 3DTrueFISP sequence is comparable to the diagnostic performance of the conventional, 2D, MR protocol.</p>

Articular cartilage covers the articulating ends of diarthrodial joints. It plays a vital role in the function of the musculoskeletal system by allowing almost frictionless motion to occur between the articular surfaces of a diarthrodial joint. Study of cartilage contact behavior will help to understand the intrinsic biomechanical properties related to cartilage degeneration and related pathology. In order to study the mechanical behavior of the cartilage a FEM based computational model of the knee-joint was developed from MRI data. A heuristic algorithm was developed based on Image processing techniques using Evolve2D toolbox and edge detection. An indigenous path following algorithm to capture minute details of bone and soft tissue curvature was developed using Image Processing Toolbox of Matlab. Parts including femur, tibia, femoral and tibial cartilages, lateral & medial menisci were extracted as a point cloud from each of the slices and rendered into a 3D model using GUI driven CAD package RHINOCEROS 4.0. Commercial FE software HYPERMESH 9.0 was used to develop FE model from geometric model. Cartilage and Menisci were modeled using eight node hexahedral elements and bones were modeled using four node quadrilateral elements. Bones were assumed to be rigid. Cartilage and menisci were assumed to be linearly elastic, isotropic and homogenous. The knee joint was subjected to a uniaxial compressive load with tibia remaining fixed and femur subjected to two primary boundary conditions: 1.Flexion - extension and Varus - Valgus rotation constrained; 2.Only Varus - Valgus rotation constrained. Parameters such as contact area, contact pressure, contact force, centre of contact pressure, mises stress distribution; maximum and minimum principal stresses were studied at maximum compressive load condition and also in intermittent steps. This model considered both geometric and contact non-linearity. From the FE analysis, it was observed that peak contact deformation and contact area on both femoral and tibial medial cartilage was found to be greater than the lateral side under full extension condition. More than 50% of the load transmission was through the medial side - which could be an indication of cartilage degeneration. Deformation of lateral meniscus was more than the medial meniscus under angular constrained conditions. Loading history during intermittent steps suggested that contact area on lateral tibial cartilage increased with load, indicating joint asymmetry. These results indicate the importance of the rotational constraints (boundary conditions) and represent more accurate physiological behavior of knee joint. Role of menisci in this study was analyzed, which indicated that consideration of menisci is essential in biomechanical estimation of load transmission. In conclusion, detailed segmentation to develop geometric model, precise boundary conditions & time dependent behavior of cartilage and menisci helped in understanding knee joint load bearing capacity to a better accuracy and can potentially give rise to designing better cartilage implants.