Chronic fat impingement can result in chronic inflammation and fat pad hypertrophy. Background Lateral Patella dislocations are common injuries seen in the active and young adult populations. Stress and shear forces that follow can result in cartilage damage and the development and evolution of osteoarthritis [57]. Imaging of Osseous Knee Trauma | Musculoskeletal Key also supported our data in a magnetic resonance imaging (MRI) study of 82 patients with the diagnosis of lateral patella dislocation and found that 76% of medial retinacular/MPFL disruption occurred at its patellar insertion site, 49% occurred at the femoral attachment site, 30% showed injury of the MPFL at mid-substance, and 48% . Part of Nontraumatic Knee Pain: A Diagnostic & Treatment Guide In the setting of osseous patellar malalignment, an osseous procedure such as tibial tubercle transfer osteotomy can be performed (Fig. 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. Bookshelf The patella remains laterally subluxed and tilted, and the patient has an abnormally shallow trochlear groove (line). The main morphological features associated with patellar maltracking are trochlear dysplasia, lateralization of the tibial tuberosity, patella alta, and lateral patellar tilt. 1835 31 - 40 27 30.0 41 - 50 22 24.4 50 + 4 4.4 Total 90 100.0 Age Distribution Number Percent Sex Female 19 21.1 Male 71 78.9 At the time the article was created Aditya Shetty had no recorded disclosures. Am J Orthop (Belle Mead NJ) 46:290300, Dejour H, Walch G, Neyret P, Adeleine P (1990) Dysplasia of the femoral trochlea. Both knees are scanned simultaneously. Osteochondral injuries to the inferomedial patella may be the result of impaction during dislocation or shearing with reduction. Lateral Retinacular Release - Surgery Information In effect all three medial layers of the knee thus comprise the medial retinaculum, which is by itself not a discrete, single structure. a Axial PDFS right knee MR image at the level of the trochlear groove. (19a) The corresponding STIR coronal image reveals the large displaced osteochondral fragment (arrow) at the lateral aspect of the lateral femoral condyle. Int Orthop. The patients are then J-braced for 3 to 6 months for all sports activities. Burks RT, Desio SM, Bachus KN, Tyson L, Springer K. Spritzer CE, Courneya DL, Burk DL Jr, Garrett WE, Strong JA. Direct impact to the front of the knee from a fall or other blow is a common cause of tears. [Nov;2019 . Lateral patellar dislocation. Gross anatomy The superficial layer originates from the lowest fibers of the iliotibial band and from an extension of vastus lateralis fascia. A trochlear depth of < 3mm indicates dysplasia. Structures such as the iliotibial band, fibular collateral ligament, and biceps femoris tendon are readily apparent on MRI and are easy to identify. A focused history of the mechanism, number, and circumstances of instability to date is essential. 35 Dislocation typically occurs in the setting of internal rotation of the femur on a fixed, externally rotated tibia. By altering the insertion point of the patellar tendon, these procedures affect the timing and position of patellar engagement in the trochlea and have the ability to biomechanically offload damaged distal articular cartilage, thereby reducing pain and increasing stability simultaneously. Would you like email updates of new search results? (17a) An axial T2 fat-suppressed image in another patient reveals a fluid filled gap (short arrow) at the site of attachment of the medial retinaculum. PDF ORIGINAL RESEARCH Role of Magnetic Resonance Imaging in Evaluation of 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. Medial patellar. Less common predisposing factors to be aware of include laterally tilted patella, VMO dysplasia and generalized joint laxity. no financial relationships to ineligible companies to disclose. Observer Agreement on the Dejour Trochlear Dysplasia Classification: A comparison of true lateral radiographs and axial magnetic resonance images. Bone bruise in acute traumatic patellardislocation: volumetric magnetic resonance imaging analysis with follow-up mean of 12 months. MRI is the imaging modality of choice in the assessment of patellar maltracking, as a virtue of what it can reveal (Table1). b Axial CT image showing tibial tuberosity transfer surgery with screw placement (arrow). The medial patellar retinaculum is part of the anterior third of the medial joint capsule. [Google Scholar] 6. Springer, New York, pp 1529, Cash JD, Hughston JC (1988) Treatment of acute patellar dislocation. J Pediatr Orthop 37:484490, Parikh SN, Lykissas MG, Gkiatas I (2018) Predicting risk of recurrent patellar dislocation. The patella articulates with the trochlear groove of the anterior femur, which has corresponding lateral and medial patellar articular surfaces [6]. As a common knee injury, patellar dislocation has a mean annual incidence of 5.8 in 100,000 people and is more prevalent in women. Features that may predispose to patellar dislocation and/or patellar maltracking and can be evaluated with CT include patellar and trochlear morphology and the alignment between the two structures. Imaging, particularly MRI, plays a vital role in the assessment of patellar maltracking. TT-TG distance of more than 20mm is believed to be nearly always associated with patellar instability [27]. Edema and thickening compatible with tears of the MPFL and medial retinaculum (red arrows) are apparent both anteriorly and posteriorly. J Knee Surg 19:307316, Gonaives MB, Jnior LH, Soares LF, Gonaives TJ, Dos Santos RL, Pereira ML (2011) Medial patellofemoral ligament reconstruction to treat recurrent patellar dislocation. It acts as a powerful extensor of the knee. Predisposing factors to patellofemoral dislocation include patella alta, excessive lateral distance between the tibial tubercle and trochlear groove and a congenitally shallow trochlear groove5, any of which significantly increase a patients likelihood for dislocation. Lateral patellar retinaculum. U.S. Army Health Clinic Grafenwoehr U.S. Army Health Clinic Grafenwhr is located on Tower Barracks and provides quality ambulatory care for more than 15,000 Soldiers and their families, while coordinating and facilitating inpatient and specialty care with nearby German host nation medical facilities and DoD partners. PubMed The adductor magnus tendon (AT) attaches to the adductor tubercle, which lies posterior and superior to the femoral attachment of the MPFL. Knee Surg Sports Traumatol Arthrosc 22:26552661, Seitlinger G, Scheurecker G, Hgler R, Labey L, Innocenti B, Hofmann S (2012) Tibial tubercle-posterior cruciate ligament distance: a new measurement to define the position of the tibial tubercle in patients with patellar dislocation. Bull NYU Hosp Jt Dis 67:2229, Dupuy DE, Hangen DH, Zachazewski JE, Boland AL, Palmer W (1997) Kinematic CT of the patellofemoral joint. AJR Am J Roentgenol 195:13671373, Jarraya M, Diaz LE, Roemer FW, Arndt WF, Goud AR, Guermazi A (2018) MRI findings consistent with peripatellar fat pad impingement: how much related to patellofemoral maltracking? Patella instability in children and adolescents. Disadvantages of CT compared to MRI include the use of ionizing radiation, which reduced soft tissue contrast resulting in limited evaluation of the cartilage, tendons, ligaments, muscles, and internal structures of the knee [64]. volume10, Articlenumber:65 (2019) is a term coined for anatomic characteristics that lead to an increased Q angle and an exacerbation of patellofemoral dysplasia. Imaging plays a vital role in detecting not only the secondary damage but also subtle early features that can raise the suspicion for the presence of this entity. Jibri, Z., Jamieson, P., Rakhra, K.S. A typical bone bruise is seen within the anterolateral aspect of the lateral femoral condyle (asterisk). The lateral trochlear articular surface is usually more prominent than its medial portion. Peroneal Tendon Dislocation and Superior Peroneal Retinaculum Injury MeSH 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. Am J Sports Med 45:10591065, Brossmann J, Muhle C, Schrder C et al (1993) Patellar tracking patterns during active and passive knee extension: evaluation with motion-triggered cine MR imaging. 5). The deep layer of the lateral retinaculum contains thickenings that form ligaments providing stabilizing support to the patella. Injury. It is a major factor in patellar instability and was shown to be present in 85% of these patients [21]. Traumatic lateral patellar dislocation is a common injury among young, athletic individuals and is generally transient in nature. (13a) A line is drawn between the cortex of the lateral trochlear facet on the most superior axial image showing cartilage. The patellofemoral joint has two primary functions; firstly, it acts as an anatomic pulley to provide mechanical advantage for the extensor mechanism and, secondly, to reduce friction between the extensor mechanism and the femur. The degree of patellar tilt can be evaluated by measuring the patella tilt angle, which is the angle between the posterior condylar line and the maximal patella width line [47] (Fig. Post WR, Teitge R, Amis A (2002) Patellofemoral malalignment: looking beyond the viewbox. 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. It is not until beyond 90 of flexion that the odd facet engages the medial femoral condyle and plays a role in load sharing along with lateral facet [6, 7]. (7a) A coronal T1-weighted image at the level of the patella demonstrates blending of fibers of the VMO with the MPFL superiorly. A Focal Defect at the Lateral Patellar Retinaculum on Clinical Knee MRI (14a) A fat-suppressed proton density-weighted coronal image following patellar dislocation reveals the classic lateral condylar bone bruise (arrow). In our experience, injuries to the transverse band most often involve the femoral attachment, whereas injuries to the oblique decussation and associated medial retinacular structures are more common at the patellar attachment. Dejour et al. 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. Lateral release and medial imbrication on their own are generally insufficient, but can be used to augment an MPFL repair or reconstruction or, if there is osseous misalignment, used in conjunction with a bony procedure particularly if there is recurrent instability or demonstrable lateral patellar tilt [73,74,75,76,77,78]. Failure to identify or treat injury to the patellar retinaculum is associated with recurrent patellar instability and contributes to significant morbidity. Patellofemoral friction syndrome: MRI findings of an - Eurorad Int J Sports Med 29:359365, Smith TO, Walker J, Russell N (2007) Outcomes of medial patellofemoral ligament reconstruction for patellar instability: a systematic review. This distance is the trochlear sulcus depth (TD). Because as noted above, the femoral bone bruise occurs as the patella moves forward during reduction, bone bruises at the lateral femoral condyle always course anteriorly from the site of any femoral chondral injury that may be present. TT-TG assessment has its own limitations. Epub 2023 Feb 7. Am J Sports Med 14:3945, Ward SR, Powers CM (2004) The influence of patella alta on patellofemoral joint stress during normal and fast walking. AJR Am J Roentgenol 1997; 168:117-122. The latter distinction is important to recognize among both radiologists and surgeons. Migliorini F, Marsilio E, Cuozzo F, Oliva F, Eschweiler J, Hildebrand F, Maffulli N. Life (Basel). Such patients are generally treated with immobilization for 3 to 6 weeks. ity. Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella. 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. 1. Courtesy of Daniel Bodor, MD, Radsource. 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. Magnetic Resonance Imaging Findings After Acute Patellar Dislocation in Femoral osteochondral injuries, when present, typically involve the lateral weightbearing surface. PMID: 9168713. The Insall-Salvati index is the most widely accepted measurement and is easily performed on radiographs and MRI examinations. 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 ]. Physical Therapy. 2000; 216:858-864. The trochlear groove and patella may have abnormal morphology that predisposes to patellar dislocation. Advantages of CT over plain radiography include its cross-sectional capability and ability to generate multiplanar reformations. Radiology. The common peroneal nerve can be localized in the popliteal fossa or identified posterior to the biceps femoris tendon and followed as it courses around the fibular neck. Between 15 and 45% of patients will develop recurrent patellar instability after acute dislocation, which is both functionally limiting and painful [17,18,19,20]. 2011;39(8):1756-1761. Femoral condylar chondral injuries occur during the dislocation phase due to impaction shearing forces of the patella upon the flexed femur, typically occurring at the weightbearing surface. In order for the patella to engage with the femoral trochlea, a higher degree of flexion than normal is needed. Division of Sports Trauma, Department of Orthopaedics, Aarhus University Hospital, Aarhus, Denmark. It runs obliquely and transversely and inserts on the patella and the patellar tendon, and is composed of two layers. Other structures that blend in this region include the medial patellotibial ligament, the medial patellomeniscal ligament, the investing fascia, and the medial joint capsule. AJR Am J Roentgenol. 5). Understanding the biomechanics of these joints is essential to investigating and appropriately treating patellofemoral joint pathology. As is typical, a bone bruise extends anteriorly (arrowheads) from the site of the chondral defect. The medial patellofemoral ligament is composed of a transverse (T) component arising between the adductor tubercle and medial epicondyle and an oblique decussation that originates from the medial collateral ligament (MCL). (9a) The Insall-Salvati Index is determined by dividing the length of the patellar tendon (PT) by the length of the patella (PL). If the lateral retinaculum tendon is tight enough to pull the patella out of the trochlear groove, a lateral release procedure can loosen the tissue and correct the patellar malalignment. Although varied in presentation, successful management of all patients relies on thorough history taking, physical examination of the entire lower extremity, and appropriate imaging. A thorough examination of the knee is then performed including presence of effusion, localization of pain, assessment of patellar translation, patellar apprehension, presence of a J sign (visual lateralization of the patella as it disengages from the trochlea when extending the knee), and a measurement of the Q angle along with ligamentous and meniscal testing. Medial patellofemoral ligament: cadaveric investigation of anatomy with MRI, MR arthrography, and histologic correlation. Clipboard, Search History, and several other advanced features are temporarily unavailable. Trochlear depth=[(a+b)/2]c, Lateral trochlear inclination measurement on axial MRI. Patellar maltracking: an update on the diagnosis and treatment strategies. 8600 Rockville Pike Magn Reson Med Sci 17:195202, Elias DA, White LM (2004) Imaging of patellofemoral disorders. Despite the presence of numerous detailed anatomical dissection and MRI based studies of the anatomy2,3, there is much variability in the description of these structures within the literature. The lateral retinaculum or lateral canthus is a complex integration of a number of structures. Our study focus was to evaluate medial patellofemoral ligament (MPFL) injury patterns and associated knee pathology using Magnetic Resonance Imaging studies. Am J Sports Med 14:117120, Smith TO, Donell S, Song F, Hing CB (2015) Surgical versus non-surgical interventions for treating patellar dislocation. 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. Distally, it attaches to the tibial tubercle via the patellar tendon. Am J Sports Med. Infrapatellar (Hoffas) fat pad impingement is recognized as a cause of anterior knee pain. Medial patellofemoral ligament injury patterns and associated pathology Normal TD > 5.2mm. This allows for greater detailed evaluation of the patellar and trochlear morphology, patellofemoral relationship, and status of the joint. At less than 30 of flexion, asymptomatic knees may demonstrate physiologic patellar tilt or subluxation. The AIUM Practice Parameter for the Performance of the Musculoskeletal Anatomy of the lateral aspect of the knee is complex, with numerous structures providing stability. The purpose of this article is to discuss the evaluation of patellar maltracking providing an update on the imaging assessment and also a synopsis on the management options. statement and 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]. MRI has been found to be 85%-92% sensitive for diagnosing MPFL injury (Seeley, 2013). Radiographics. The injury typically occurs from a twisting event with the knee in mild flexion (less than 30). {"url":"/signup-modal-props.json?lang=us"}, Shetty A, Saber M, Rasuli B, et al. 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]. The oblique decussation of the MPFL blends with fibers of the superficial MCL. Lateral patellar dislocation | Radiology Reference Article Imaging, particularly MRI, can detect subtle features that could lead to the diagnosis, probably even more importantly when there is no clear history of patellar dislocation or before its development. The most accepted indication for surgical management of patellar instability is the presence of a large displaced osteochondral fracture or loose body. At the time the article was last revised Joel Hng had The natural history. Surgical indications following patellar dislocation include the presence of a chondral or osteochondral body, significant rupture of the medial stabilizers most importantly the MPFL, a persistent laterally subluxed patella, or a second dislocation injury in a patient with malalignment or dysplasia. Radiology 216:858864, Biedert RM, Tscholl PM (2017) Patella alta: a comprehensive review of current knowledge. 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 ]. MRI, given its superior soft tissue contrast and multi-planar capability, has emerged as the modality of choice in evaluating articular cartilage abnormalities. The most common trochleoplasty procedure described is a combination of lateral trochlear osteotomy and bone graft to heighten the lateral trochlea. Elsevier, Philadelphia, Buckens CF, Saris DB (2010) Reconstruction of the medial patellofemoral ligament for treatment of patellofemoral instability: a systematic review. (5a) An axial T1-weighted image demonstrates the low blending fibers of the VMO and transverse MPFL at their attachment along the upper patella. An increased tibial tubercletrochlear groove (TT-TG) indicates a lateralized tibial tuberosity, or a medialized trochlear groove [38]. What is the diagnosis? A perpendicular line is measured to the most posterior cortex of the central trochlea. PTI of less than 12.5% suggests the presence of patella alta. LTI < 11 degrees indicates dysplasia. Skeletal Radiol 48:387393, Schoettle PB, Zanetti M, Seifert B, Pfirrmann CW, Fucentese SF, Romero J (2006) The tibial tuberosity-trochlear groove distance; a comparative study between CT and MRI scanning. The average annual incidence for patellar dislocation injuries ranged between 5.8 and 7.0 per 100,000 person-years in the civilian population, and up to 29 per 100,000 person-years in the 10-17 year age . a Normal trochlea. The patella itself is shaped as an inverted triangle and is embedded in the quadriceps tendon, making it the largest sesamoid bone in the body [6]. AJR Am J Roentgenol. In either case, careful search for possible displaced osteochondral fragments is necessary, as surgery is often indicated in such patients. (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). The TT-TG is evaluated by measuring the distance between the most anterior point of the tibial tuberosity and the deepest point of the trochlear groove using two lines drawn perpendicular to the tangent to the posterior borders of the femoral condyles [31] (Fig. Seven of the nine patients with patellar dislocation injuries had frank osteochondral injuries. Reconstruction of the medial patellofemoral ligament for treatment of patellar instability. A facet ratio of < 40% indicates dysplasia. official website and that any information you provide is encrypted 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. Surgical management of patellar instability should be guided on an individual patient basis depending on history, physical examination, and radiologic findings as outlined above. 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. The pattern of bone bruising seen in a transient lateral patellar dislocation is easy to understand if one considers the mechanism of injury. A ratio equal or more than 1.2 indicates patella alta [35] (Fig. The Anterolateral Ligament of the Knee: MRI Appearance, Association 3. TTTG is the distance between the solid and the dashed lines in (b). Asymmetry of <40% suggests trochlear dysplasia [24]. Radiology 225:736743, Kirsch MD, Fitzgerald SW, Friedman H, Rogers LF (1993) Transient lateral patellar dislocation: diagnosis with MR imaging. It has proven to be both sensitive and specific in the detection of hyaline cartilage abnormalities [4]. MR findings were correlated with clinical, surgical, and arthroscopic findings. Identifying edema at the superolateral aspect of Hoffas fat pad on MRI should prompt the reporting radiologist to look for features of patellar maltracking. Another study noted an association between abnormal trochlear morphology and high-grade patellofemoral cartilage damage [58]. Privacy 0000070933 00000 n 0000192215 00000 n 0000212094 00000 n The patellar dislocations were clinically unsuspected in the initial evaluation of eight of these nine patients. 8). The transverse band attaches to the upper pole of the patella, and this component originates on a bony groove that lies between the adductor tubercle and the medial epicondyle, slightly posterior to the epicondyle. Methods MRI studies taken at one imaging site between January, 2007 to January, 2008 with the final diagnosis of patella . Nearly 50% of all first-time dislocators will sustain further dislocations. Falls. (18a) A 13-year-old female following acute patellar dislocation. The patella remains laterally shifted (blue arrow) and an osteochondral injury of the medial patella (arrowheads) is apparent. Knee 13:266273. Lateral patellar dislocation is a common clinical entity with a characteristic MR appearance. Abnormalities of the medial retinaculum and MPFL are seen in 82-100% of MRI examinations following patellar dislocation. The patella has 4 different planes of motion: flexionextension, mediallateral rotation, mediallateral patellar tilt, and mediallateral patellar shift. Acute lateral patellar dislocation at MR imaging: injury patterns of 4. Knee Surg Sports Traumatol Arthrosc 15:13011314, Tom A, Fulkerson JP (2007) Restoration of native medial patellofemoral ligament support after patella dislocation. Of course, if medial soft tissue restraints are disrupted at the first dislocation, the loss of such restraints makes future dislocations more likely. 9). 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. A tight lateral retinaculum can tilt the patella leading to increased pressure on the lateral facet causing pain (Ficat). Arthroscopy 32:929943, Dejour D, Saggin P (2010) The sulcus deepening trochleoplastythe Lyons procedure. Figure 1: ligaments (Gray's illustrations), View Pereshin Moodaley's current disclosures, see full revision history and disclosures, posterior suprapatellar (prefemoral or supratrochlear) fat pad, anterior suprapatellar (quadriceps) fat pad, accessory anterior inferior tibiofibular ligament, superficial posterior tibiotalar ligament, superficial posterior compartment of the leg (calf), accessory extensor digiti secundus muscle, descending branch of the lateral circumflex. 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]. 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. [Crossref] Harvinder Bedi, John Marzo. Large tears may require surgical suturing repair. Note the edema in the superolateral aspect of Hoffas fat pad (arrow). Axial PDFS left knee MR image, demonstrating the method used for the measurement of trochlear depth.

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