Concave impaction deformity of the inferomedial patella is a specific sign of prior LPD. Cite this article. High resolution magnetic resonance imaging of the patellar retinaculum: normal anatomy, common injury patterns . A ratio equal or more than 1.2 indicates patella alta [35] (Fig. A patient with acute first-time transient patellar dislocation without osteochondral lesions and severe risk factors for redislocation is generally treated conservatively. A ratio > 1.3 indicates patella alta. Yu JS, Goodwin D, Salonen D, Pathria MN, Resnick D, Dardani M, Schweitzer M. AJR Am J Roentgenol. Techniques of Medial Retinacular Repair and Reconstruction - LWW Epub 2023 Feb 7. From 10 to 20 of flexion, the patella engages the trochlear groove with the contact area being the inferior most portion of the medial and lateral facets. PubMed Central Sports Med Arthrosc 15:6871, Longo UG, Rizzello G, Ciuffreda M et al (2016) Elmslie-Trillat, Maquet, Fulkerson, Roux Goldthwait, and other distal realignment procedures for the management of patellar dislocation: systematic review and quantitative synthesis of the literature. Materials and methods: Twenty-two male patients (age range 20-45 years) with posttraumatic knee stiffness following distal femoral fractures underwent Thompson's quadricepsplasty where knee flexion range was less than 45. The clinical evaluation of patellar maltracking is often challenging, Imaging can detect subtle features that could lead to early diagnosis, Imaging can detect predisposing factors for patellar maltracking and associated structural changes, Management decisions are made on individual basis with imaging playing a vital role. Surgical management of patellar instability should be guided on an individual patient basis depending on history, physical examination, and radiologic findings as outlined above. The lateral retinaculum provides significant additive support to the medial stabilizers. Clin Sports Med 21:521546 x, Article Part of It can be divided into nonoperative and operative management. PDF ORIGINAL RESEARCH Role of Magnetic Resonance Imaging in Evaluation of 2. (15a) A fat-suppressed proton density-weighted axial image at the level of the upper patella in the same patient demonstrates avulsion of the transverse band of the MPFL at the femoral attachment (arrow) with edema primarily anterior to the adductor magnus tendon (AM). Epub 2011 Nov 9. An official website of the United States government. MR findings were correlated with clinical, surgical, and arthroscopic findings. It was shown that certain features of patellar maltracking (increased sulcus angle, lateral patellar tilt, and a higher patellar tendon to patellar length ratio) are associated with cartilage loss and bone marrow lesions [59]. Peroneal Tendon Dislocation and Superior Peroneal Retinaculum Injury At the time the article was last revised Mohamed Saber had PFA is the angle between a line drawn along the bony lateral patellar facet and another line along the anterior aspect of the femoral condyles. Thus, imaging at positions both less than and greater than 30 can be used to avoid missing maltracking that might be captured at only certain degrees of flexion [64]. Ellas et al. A sliver of fluid undermines a moderately thickened and scarred MPFL at the medial femoral condyle attachment consistent with a chronic partial stripping tear (arrowheads). Operative lateral retinaculum release is indicated in refractory cases. The trochlear groove and patella may have abnormal morphology that predisposes to patellar dislocation. In effect all three medial layers of the knee thus comprise the medial retinaculum, which is by itself not a discrete, single structure. (Figs.1-A 1-A also and1-B). Google Scholar, Fithian DC, Paxton EW, Stone ML et al (2004) Epidemiology and natural history of acute patellar dislocation. Am J Sports Med. a Axial CT image demonstrating MPFL reconstruction (arrow heads). (20a) A fat-suppressed proton density-weighted sagittal image in a patient following patellar dislocation reveals an osteochondral injury with a chondral defect (arrows) at the lateral weightbearing surface of the lateral femoral condyle, a finding seen in only 5% of patients. lateral patellar retinaculum tear or invasion. They are best indicated in isolation in the setting of recurrent instability with minimal underlying osseous malalignment (normal TT-TG, minimal trochlear dysplasia). Google Scholar, Miller TT, Staron RB, Feldman F (1996) Patellar height on sagittal MR imaging of the knee. PubMed TT-TG is a reflection of the clinically measured Q angle. An imbalance of forces acting on the patellofemoral joint due to abnormal bony geometry or altered function of the active and passive soft tissue restraints may result in abnormalities of alignment and tracking of the patella. Structures such as the iliotibial band, fibular collateral ligament, and biceps femoris tendon are readily apparent on MRI and are easy to identify. 2010;30(4):961-81. (7a) A coronal T1-weighted image at the level of the patella demonstrates blending of fibers of the VMO with the MPFL superiorly. Intervention: Taping the knee to promote medial glide . The pattern of bone bruising seen in a transient lateral patellar dislocation is easy to understand if one considers the mechanism of injury. J Orthop Sports Phys Ther 2017;47(10):815. doi:10.2519/ jospt.2017.6616 . 9). Perpendicular to this baseline, trochlear depth is calculated by measuring the mean of the maximum AP distance of the medial (a) and lateral (b) femoral condyles minus the distance between the deepest point of the trochlear groove and the line paralleling the posterior condylar surfaces (c). (27a) Axial and (27b) coronal fat suppressed proton density-weighted images in a patient who experienced recurrent patellar dislocation following surgery. Discussion. 5 Carrillon Y, Abidi H, Dejour D, et al. Knee CT images in the early post-operative period in a 19-year-old male with history of patellar maltracking. At 0 extension, the patellar may lie completely above the level of the trochlea, without direct apposition between the two articular surfaces. The trochlear depth is calculated by measuring the mean of the maximum anteroposterior (AP) distance of the medial and lateral femoral condyles minus the distance between the deepest point of the trochlear groove and the line paralleling the posterior femoral condyles surfaces (Fig. Curr Sports Med Rep 11:226231, Jain NP, Khan N, Fithian DC (2011) A treatment algorithm for primary patellar dislocations. The stifle joint of the pampas deer . J Bone Joint Surg Am 61:5662, Jerabek SA, Asnis PD, Bredella MA, Ouellette HA, Poon SK, Gill TJ 4th (2009) Medial patellar ossification after patellar instability: a radiographic finding indicative of prior patella subluxation/dislocation. Sports Med Arthrosc Rev 25:7277, Gillespie H (2012) Update on the management of patellar instability. Starok M, Lenchik L, Trudell D, Resnick D. Normal patellar retinaculum: MR and sonographic imaging with cadaveric correlation. The lateral retinaculum appears as a hyperechoic band originating from the iliotibial band and the vastus lateralis muscle. Depends on how bad: Small tears are observed and heal. 23,29,37 The causative factors of . Background Lateral Patella dislocations are common injuries seen in the active and young adult populations. PubMed In: Miller M, Thompson S (ed) DeLee and Drezs orthopaedic sports medicine. Materials and methods: Two radiologists independently reviewed 99 knee MR images for the presence of a focal defect at the lateral patellar retinaculum and . Are you sure you want to trigger topic in your Anconeus AI algorithm? Some controversy exists regarding whether female gender is a definite risk factor for patellar instability with certain studies identifying a 33% increased likelihood of first-time dislocation as well as three times high re-dislocation rates than males, whereas others have found roughly equal rates [2, 12,13,14]. 3). Sanders T, Paruchuri N, Zlatkin M. MRI of Osteochondral Defects of the Lateral Femoral Condyle: Incidence and Pattern of Injury After Transient Lateral Dislocation of the Patella. Magnetic resonance imaging (MRI) is a vital tool in evaluating the potential cause(s) of anterior knee pain due to the complexity of the structure and biomechanics of the knee. At the time the article was created Pereshin Moodaley had no recorded disclosures. The osteocartilaginous anatomy of the patellofemoral joint provides additional static stabilization to the joint. Radiology. Bethesda, MD 20894, Web Policies From the inside of the knee the lateral retinaculum is incised, from the inside, allowing the kneecap to untilit itself. HHS Vulnerability Disclosure, Help PubMedGoogle Scholar. 7,14 While plain radiography is an important tool to diagnose APD, magnetic resonance imaging (MRI . It has been shown that there is an association between edema at the superolateral aspect of Hoffas fat pad and a number of patellar maltracking parameters [30, 54, 55].