(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. Patellofemoral friction syndrome: MRI findings of an - Eurorad Acute traumatic instability most commonly occurs in young athletes in their second and third decade at an incidence rate of 29 per 100,000. Traumatic dislocations are commonly associated with other injuries including that of the MPFL, meniscal pathology, and osteochondral fractures of the femur or patella [15, 16]. Given the lack of history of direct trauma, a reliable diagnosis can be made. Hemarthrosis is rare in lateral patellar sleeve fractures, as the lateral pole is not as vascularized as the inferior pole of the patella that has the most important blood supply of patella [5 ]. As the knee joint ranges from extension to flexion, the articular surface area of the patella is in contact with the femur changes. Patellar maltracking is a disorder that often affects the young active individuals. 8600 Rockville Pike It is a ratio between the patellar tendon length (along the inner surface of the tendon) and the diagonal patellar height [27]. Evaluation of both of these soft tissue structures is critical when one examines a MRI following lateral patellar dislocation, as the extent of soft-tissue injury influences the use of operative repair. PMC In the past two decades dissection studies have shown that it extends from the superomedial border of the patella to the femoral epicondyle, at or immediately above the adductor tubercle. Imaging of patellar fractures | Insights into Imaging | Full Text Patellar dislocation most commonly results from a twisting motion, with the knee in flexion and the femur rotating internally on a fixed foot (valgus-flexion-external rotation) 1. However, the use of this method is not widespread. Bone Contusion Patterns of the Knee at MR Imaging - RadioGraphics The lateral trochlear articular surface is usually more prominent than its medial portion. Intervention: Taping the knee to promote medial glide . Axial PDFS left knee MR image, demonstrating the method used for the measurement of trochlear depth. The two features are associated with patellar maltracking. Radiographics. Transient Lateral Patellar Dislocation - Radsource Medial retinacular complex injury in acute patellar dislocation: MR findings and surgical implications. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Am J Sports Med 16:244249, Hawkins RJ, Bell RH, Anisette G (1986) Acute patellar dislocations. Epidemiology Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in sports activities. (5a) An axial T1-weighted image demonstrates the low blending fibers of the VMO and transverse MPFL at their attachment along the upper patella. Lateral patellar retinaculum. This can provide a road map of developing a treatment strategy that would be primarily aimed at stabilizing the patellofemoral joint and halt the progression of cartilage loss. A trochlear depth of < 3mm indicates dysplasia. and transmitted securely. Each of the mentioned assessment methods of patella alta has its own advantages and limitations. The transverse stabilizers include the medial and lateral retinaculum, the vastus medialis and lateralis muscles, the ilio-tibial band, and the medial patellofemoral ligament (MPFL). Bookshelf Another study noted an association between abnormal trochlear morphology and high-grade patellofemoral cartilage damage [58]. Lateral trochlear inclination is another quantitative method to diagnose trochlear dysplasia. It acts as a powerful extensor of the knee. (11a) The depth of the trochlear groove is measured by drawing a line from the most anterior position of the medial trochlea to the lateral trochlear anterior cortex. It thickens as it inserts onto the lateral border of the patella, quadriceps tendon and patellar ligament. 5). Before The knee is a complex joint with separate tibio-femoral and the patellofemoral articulations. Dr. Frederick Buechel, Jr. MD answered. Adjunctive treatments such as knee aspiration and patellar stabilizing braces have been proposed to decrease swelling and enable early range of motion; however, there is no conclusive evidence for their use [71]. Clin Biomech (Bristol, Avon) 19:10401047, Horton MG, Hall TL (1989) Quadriceps femoris muscle angle: normal values and relationships with gender and selected skeletal measures. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. Acute patellar dislocation (APD) is a common injury in children, accounting for up to 16% of acute knee hemarthroses. Objective: The purpose of this study is to retrospectively investigate the frequency of a focal defect at the lateral patellar retinaculum on knee MRI and to determine the variables that are significantly associated with the defect. CT of both knees in 20 flexion demonstrating bilateral shallow trochlear groove (arrows) compatible with dysplasia and bilateral lateral patellar subluxation and lateral tilt. Note the edema in the superolateral aspect of Hoffas fat pad (arrow). Am J Sports Med 45:10121017, Pedersen ME, DaCambra MP, Jibri Z, Dhillon S, Jen H, Jomha NM (2015) Acute osteochondral fractures in the lower extremities - approach to identification and treatment. The technique has been refined, and a better understanding of the anatomical features of both the origin and insertion of the ligament onto the patella has made the operation more reproducible (Fig. The VMO is active, not only in full extension but also at 30 degrees and up to 100 degrees of flexion. Early diagnosis is essential, as chronic maltracking will lead to patellofemoral cartilage damage and osteoarthritis [3]. An official website of the United States government. Abnormalities of the medial retinaculum and MPFL are seen in 82-100% of MRI examinations following patellar dislocation. 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]. Radiology. Methods: We compared 361 treated cases of aneurysm occlusion after subarachnoid hemorrhage from 1997 to 2003 with 281 cases from 2006 to 2014. Initial diagnosis is key to a successful outcome, as these injuries are easily overlooked on plain radiographs with poor results well documented from delayed management. Tibial Tubercle Osteotomy to Aid Exposure for Revision Total Knee Knee Surg Sports Traumatol Arthrosc 15:13011314, Tom A, Fulkerson JP (2007) Restoration of native medial patellofemoral ligament support after patella dislocation. Open Orthop J. VMO dysplasia may play a role in patellofemoral instability. This protocol can help in evaluating for osseous integrity, morphology, and patellofemoral alignment [63] (Fig. 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. Am J Sports Med 33:220230, Nikku R, Nietosvaara Y, Aalto K, Kallio PE (2005) Operative treatment of primary patellar dislocation does not improve medium-term outcome: a 7-year follow-up report and risk analysis of 127 randomized patients. Less commonly, patients can also present after chronic patellar instability secondary to generalized ligamentous laxity with or without anterior knee pain. quadricepsplasty rehab protocol They are best indicated in isolation in the setting of recurrent instability with minimal underlying osseous malalignment (normal TT-TG, minimal trochlear dysplasia). The anatomy of the medial patellofemoral ligament. 7). One of the more common MPFL reconstruction procedures uses a single hamstring tendon graft passed through the medial intermuscular septum at the adductor magnus insertion fixed by an anchor in the femoral condyle and sutured or anchored to the superomedial pole of the patella11. Patellar Fat Pad Abnormalities - Radsource PubMed Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patelladue to disruptive changes to the medial patellar retinaculum. Lateral patellar dislocation is a common clinical entity with a characteristic MR appearance. Google Scholar, Sanders TG, Paruchuri NB, Zlatkin MB (2006) MRI of osteochondral defects of the lateral femoral condyle: incidence and pattern of injury after transient lateral dislocation of the patella. The osteocartilaginous anatomy of the patellofemoral joint provides additional static stabilization to the joint. Acute lateral patellar dislocation at MR imaging: injury patterns of It can not only detect any underlying morphological risk factors but also look for structural damage associated with maltracking including patellofemoral articular cartilage loss, osteochondral defects, or damage to the medial patellar stabilizers [4, 5]. The vastus medialis oblique (VMO) provides active stability of the patella. Clin J Sport Med 15:6266, Colvin AC, West RV (2008) Patellar instability. Tears of the medial retinaculum and the MPFL are commonly present at both the patellar and femoral attachments, though tears of the transverse band of the MPFL are more likely at the femoral attachment. 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. Reconstruction of the MPFL has recently become an increasingly popular procedure for recurrent lateral patellar instability. b Axial MRI at the level of the tibial tuberosity. 2012 Feb;41(2):137-48. doi: 10.1007/s00256-011-1291-3. 5). Objective: This prospective study is designed to detect changes in the treatment of ruptured intracranial aneurysms over a period of 17 years. The most accepted indication for surgical management of patellar instability is the presence of a large displaced osteochondral fracture or loose body. AJR Am J Roentgenol 1997; 168:117-122. (28a) A sagittal proton density-weighted image demonstrates the typical hardware location in a patient status post medialization of the tibial tuberosity (arrow). Osteochondral injuries of the inferomedial patella are seen in up to 70% of patellofemoral dislocations. Methods MRI studies taken at one imaging site between January, 2007 to January, 2008 with the final diagnosis of patella . 4. ADVERTISEMENT: Supporters see fewer/no ads. 2023 Lineage Medical, Inc. All rights reserved, Knee & Sports | Lateral Patellar Compression Syndrome. In these patients, a triad of findings that included focal impaction injuries involving the lateral femoral condyle, osteochondral injuries of the medial patellar facet, and injuries of the medial retinacular ligament were seen. TTTG is the distance between the solid and the dashed lines in (b). James M. Provenzale, Rendon C. Nelson, Emily N. Vinson. ADVERTISEMENT: Supporters see fewer/no ads, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Knee Surg Sports Traumatol Arthrosc 14:235240, Article Chronic fat impingement can result in chronic inflammation and fat pad hypertrophy. The deep layer of the lateral retinaculum contains thickenings that form ligaments providing stabilizing support to the patella. At the time the article was created Pereshin Moodaley had no recorded disclosures. 11 Lind M, Jakobsen B, Lund B, et al. Incidence and concomitant chondral injuries in a consecutive cohort of primary traumatic patellar dislocations examined with sub-acute MRI. Because the knee is flexed in dislocation, the patella impacts upon the weightbearing surface of the lateral femoral condyle. the patellar retinaculum at the dynamic examination (Fig. (3a) Graphical depictions of the mechanism of patellar dislocation: With the knee in flexion, the patella dislocated laterally. There is edema of the medial patella and of the lateral femoral condyle (arrow), consistent with bone contusion due to recent lateral patellar dislocation. Am J Sports Med. Trochlear depth=[(a+b)/2]c, Lateral trochlear inclination measurement on axial MRI. Am J Sports Med 38:181188, Ali S, Bhatti A (2007) Arthroscopic proximal realignment of the patella for recurrent instability: report of a new surgical technique with 1 to 7 years of follow-up. Patellar maltracking occurs as a result of an imbalance in the dynamic relationship between the patella and trochlea. Over 100 different procedures have been described for the treatment of patellar instability, and this reflects the various causes for instability and lack of current gold standard [66, 69, 72]. Medial patellofemoral ligament MRI abnormalities in the - Springer Identifying edema at the superolateral aspect of Hoffas fat pad on MRI should prompt the reporting radiologist to look for features of patellar maltracking. Lateral patellar compression syndrome is the improper tracking of the patella in the trochlear groove generally caused by a tight lateral retinaculum. Patellar instability: Assessment on MR images by measuring the lateral trochlear inclination-initial experience. 3. Less common predisposing factors to be aware of include laterally tilted patella, VMO dysplasia and generalized joint laxity. Significantly greater lateral patellar displacement and tilt was found in osteoarthritis patients compared to a control group [3]. (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). By using this website, you agree to our CAS Guidelines and Gamuts in Musculoskeletal Ultrasound. The MPFL plays a significant role in the stabilization of the medial aspect of the patella.Especially during the early stages of knee flexion, the MPFL is a critical component in patellar tracking and stability within the trochlear groove. 3 Dirim B, Haghighi P, Trudell D et al. AJR 2008: 191:490-498. The MPFL is attached to the region of the adductor tubercle or medial femoral epicondyle extending deep to the vastus medialis obliquus (VMO) and attaching to the superior two thirds of the patella [52]. Sports Med Arthrosc Rev 15:7277, Mikashima Y, Kimura M, Kobayashi Y, Miyawaki M, Tomatsu T (2006) Clinical results of isolated reconstruction of the medial patellofemoral ligament for recurrent dislocation and subluxation of the patella. Patellar fractures are the most common cause of disruption of the extensor mechanism, six times as frequent as soft tissue injuries such as quadriceps or patellar tendon rupture [ 3 ]. In full extension, the patella has little to no contact with the trochlear groove and, therefore, is in a position of higher risk for instability. The marrow edema and medial patellofemoral ligament (MPFL) injury pattern above are virtually pathognomonic of a transient lateral patellar dislocation, as little else will cause such an appearance. Skeletal Radiol. Normal TD > 5.2mm. Am J Sports Med 18:359365, Lattermann C, Toth J, Bach BR Jr (2007) The role of lateral retinacular release in the treatment of patellar instability. The MPFL is composed of a stronger transverse band and a more variable and weaker oblique decussation. The anatomic relationship between the resultant force from the quadriceps and the line of pull of the patellar tendon is termed the Q angle and is normally 1015 of valgus [11]. The superficial layer originates from the lowest fibers of the iliotibial band and from an extension of vastus lateralis fascia. 2. High resolution magnetic resonance imaging of the patellar retinaculum: normal anatomy, common injury patterns . Lateral Patellar Dislocation. Manage cookies/Do not sell my data we use in the preference centre. 6. Romero J, Hodler J. Radiology. Google Scholar, Amis AA, Firer P, Mountney J, Senavongse W, Thomas NP (2003) Anatomy and biomechanics of the medial patellofemoral ligament. The objective of this paper was to describe the anatomy of the stifle joint (Articulatio genus) of the pampas deer (Ozotoceros bezoarticus, Linnaeus, 1758) by dissection and imaging studies. 6). 2012;40(4):837-844. Osteochondral injuries to the inferomedial patella may be the result of impaction during dislocation or shearing with reduction. Because of the transient and brief nature of lateral patellar dislocations, the diagnosis is frequently unrecognized by both patients and clinicians. The femoral attachment of the transverse band of the MPFL is not always discretely visible, and therefore secondary signs on MRI such as fluid, edema, and soft tissue thickening at the attachment indicate MPFL injury. The AIUM Practice Parameter for the Performance of the Musculoskeletal At 0 extension, the patellar may lie completely above the level of the trochlea, without direct apposition between the two articular surfaces. a Axial PDFS right knee MR image at the level of the trochlear groove. Operative lateral retinaculum release is indicated in refractory cases. For first-time dislocators without intra-articular loose bodies or chondral injury, a trial of nonoperative therapy is indicated. Kim et al. A small osseous avulsion (arrowhead) is seen in this region. J Bone Joint Surg Am 85-A:12381242, Article Knee Surg Sports Traumatol Arthrosc 26:27332742, Hingelbaum S, Best R, Huth J, Wagner D, Bauer G, Mauch F (2014) The TT-TG Index: a new knee size adjusted measure method to determine the TT-TG distance. 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. It is reported in surgical literature that 50-75% of recurrent dislocators, have some form of dysplasia, malalignment or generalized joint laxity. MRI has been found to be 85%-92% sensitive for diagnosing MPFL injury (Seeley, 2013). In the setting of osseous patellar malalignment, an osseous procedure such as tibial tubercle transfer osteotomy can be performed (Fig. Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patella due to disruptive changes to the medial patellar retinaculum. Am J Sports Med. Nonoperative treatment is generally recommended in first time dislocators unless there are MRI findings of severe predisposing dysplasia and the presence of a chondral or osteochondral body. At the time the article was created Aditya Shetty had no recorded disclosures. Accessibility Part of Findings typically associated with acute lateral patellar dislocation were also assessed and recorded (present or absent) including characteristic bone bruises and osteochondral injuries involving the patella, lateral trochlear facet, and lateral femoral condyle. Medial Collateral Ligament (MCL) and Medial Supporting - Radiology Key Injury of the superior peroneal retinaculum (SPR) occurs with peroneal dislocation through forceful ankle dorsiflexion and concomitant reflex peroneal muscle contraction. (16a) An axial fat-suppressed T2-weighted image reveals numerous typical findings of recent lateral patellar dislocation. RadioGraphics 2010; 30: 961-981. 23,29,37 The causative factors of . The patella becomes unstable and undergoes a transient, violent lateral displacement. Such patients are generally treated with immobilization for 3 to 6 weeks. 30 Correctly diagnosing APD can be difficult as the displaced patella usually relocates spontaneously, with fewer than 10% of patients presenting with fixed lateral dislocation. The knee is a complex synovial joint that can be affected by a range of pathologies: Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 3). The VMO blends distally with the MPFL to attach to the medial border of the patella along its upper two thirds. Early detection particularly in the stage preceding the development of significant cartilaginous loss and osteoarthritis is critical. Imaging of Osseous Knee Trauma | Musculoskeletal Key It has been suggested that fat impingement occurs between the lateral femoral condyle and the posterior aspect of the patellar tendon [54]. Rev Chir Orthop Reparatrice Appar Mot 76:4554, CAS Arthroscopy 35:537543, Mountney J, Senavongse W, Amis AA, Thomas NP (2005) Tensile strength of the medial patellofemoral ligament before and after repair or reconstruction. Patellar maltracking occurs as a result of imbalance of this relationship often secondary to anatomic morphologic abnormality. It is the percentage of the medial (a) to the lateral (b) trochlear facet length (a/b100%). The convex articular surface of the patella places it at risk for chondral injury in either the dislocation or the reduction phases of injury. High resolution magnetic resonance imaging of the patellar retinaculum: normal anatomy, common injury patterns, and pathologies. It should be noted that these procedures are mostly contraindicated in the patient with open physes due to growth arrest of the tibial tubercle apophysis. Excessive lateralization of the tibial tuberosity allows the patella to be pulled laterally in flexion and is considered to be a risk factor for instability. The decreased patellar contact area decreases stability particularly in shallow degrees of flexion and thus predisposes to lateral patellar subluxation. (4a) This 3D graphic view of the medial knee with the crural fascia and sartorius (S) muscle incised and reflected demonstrates the main medial contributors to patellar stability. The MCL is composed of the superficial layer (layer 2 of the medial supporting structures) and the deep layer (layer 3 of the medial . This site needs JavaScript to work properly. Lateral patellar compression syndrome is the improper tracking of the patella in the trochlear groove generally caused by a tight lateral retinaculum. Stretching a Lateral Retinaculum of the Knee | livestrong As an example, although the InsallSalvati ratio is one of the most commonly used methods and does not depend on the degree of knee flexion, it is affected by the patellar shape particularly its inferior point and measurement does not change after tibial tubercle distalization procedure [25]. The knee then was flexed 30, 60, 90, and 120, and the transducer recorded changes in tension within the lateral patellofemoral . Most, however, agree regarding the importance of the MPFL and its role as the strongest restraint to lateral patellar displacement. b Trochlear dysplasia (9 inclination), Facet asymmetry assessment for trochlear dysplasia on axial MRI. Patellar tilt assessment. Medial retinacular complex injury in acute patellar dislocation: MR findings and surgical implications. 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. Am J Knee Surg 13:8388, Izadpanah K, Weitzel E, Vicari M et al (2014) Influence of knee flexion angle and weight bearing on the Tibial Tuberosity-Trochlear Groove (TTTG) distance for evaluation of patellofemoral alignment. MRI plays a crucial role in quantification and characterization of these predisposing anatomic variations which are key to addressing the patient?s patellar instability operatively. Created for people with ongoing healthcare needs but benefits everyone. As the knee progresses through greater flexion, the contact surface becomes more proximal on the patella. A Scientometric Analysis of Studies on Patellar Dislocation On the other hand, the PTI is significantly altered with knee flexion [37]. Ten patients had examination under anaesthesia with . Am J Sports Med. {"url":"/signup-modal-props.json?lang=us"}, Shetty A, Saber M, Rasuli B, et al. Clin Radiol 59:543557, Ali SA, Helmer R, Terk MR (2010) Analysis of the patellofemoral region on MRI: association of abnormal trochlear morphology with severe cartilage defects. Stress and shear forces that follow can result in cartilage damage and the development and evolution of osteoarthritis [57]. To provide the highest quality clinical and technology services to customers and patients, in the spirit of continuous improvement and innovation. (9a) The Insall-Salvati Index is determined by dividing the length of the patellar tendon (PT) by the length of the patella (PL). Objective: Must rule out a tight iliotibial band (ITB) and weak quadriceps muscles (Juhn).
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