This is an arthroscopic surgery ( a knee "scope" which is performed through 3 small incisions ( about inch each) around the knee. AJR Am J Roentgenol 194:721727, Kalichman L, Zhang Y, Niu J et al (2007) The association between patellar alignment and patellofemoral joint osteoarthritis features--an MRI study. Med Sci Sports Exerc 35:20432047, Steiner T, Parker RD (2009) Patella: subluxation and dislocation. The Biomechanics of Medial Patellofemoral Ligament Repair Followed by Lateral RetinacularRelease. 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]. Manage cookies/Do not sell my data we use in the preference centre. Anatomy of the lateral aspect of the knee is complex, with numerous structures providing stability. Alimorad Farshchian M. D.. Farshchian's Orthopedic Regenerative Series. Physical Therapy. Surgical management procedures can broadly be categorized as soft tissue procedures (lateral release, medial imbrication, and MPFL repair or reconstruction) and bony procedures (tibial tubercle transfer procedures and trochleoplasty). Careers. Advantages of CT over plain radiography include its cross-sectional capability and ability to generate multiplanar reformations. During this dislocation phase of injury, shearing forces can damage the articular surfaces of either the patella or the lateral femoral condyle. A tight lateral retinaculum can tilt the patella leading to increased pressure on the lateral facet causing pain (Ficat). (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). Trochlear depth of less than 3 mm on MRI has a sensitivity of 100% and a specificity of 96% for trochlear dysplasia.10. It can be divided into nonoperative and operative management. Distal neurovascular examination also needs to be performed [16]. CT of both knees in 20 flexion demonstrating bilateral shallow trochlear groove (arrows) compatible with dysplasia and bilateral lateral patellar subluxation and lateral tilt. Radiology 216:858864, Biedert RM, Tscholl PM (2017) Patella alta: a comprehensive review of current knowledge. It acts as a powerful extensor of the knee. MeSH Radiographics 30:961981, Tscholl PM, Wanivenhaus F, Fucentese SF (2017) Conventional radiographs and magnetic resonance imaging for the analysis of trochlear dysplasia: the influence of selected levels on magnetic resonance imaging. 2). Recent literature does not encourage the use of lateral release, since this can increase patellar instability. It is the percentage of the medial (a) to the lateral (b) trochlear facet length (a/b100%). The adductor magnus tendon (AT) attaches to the adductor tubercle, which lies posterior and superior to the femoral attachment of the MPFL. 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]. Various parameters can be used in assessing and predicting the presence of patellar maltracking. The knee then was flexed 30, 60, 90, and 120, and the transducer recorded changes in tension within the lateral patellofemoral . Lateral trochlear inclination is another quantitative method to diagnose trochlear dysplasia. These morphological risk factors can be assessed using methods similar to those on MRI as detailed in the prior sections of this article. Diagnosis is made clinically with pain with compression of the patella and moderate lateral facet tenderness and sunrise knee radiographs will often show patellar tilt in the lateral direction. The latter distinction is important to recognize among both radiologists and surgeons. . Patellar instability: Assessment on MR images by measuring the lateral trochlear inclination-initial experience. The MPFL is also stripped from the femoral attachment (long arrow). Unable to load your collection due to an error, Unable to load your delegates due to an error. 1-31. 1 Pain is often described as medial because of soft tissue injuries that occur to the medial retinaculum and/or MPFL. Prior lateral patellar dislocation: MR imaging findings. https://doi.org/10.1186/s13244-019-0755-1, DOI: https://doi.org/10.1186/s13244-019-0755-1. 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. The lateral retinaculum provides significant additive support to the medial stabilizers. Eleven gave a history of recurrent patellar dislocation. Value of the tibial tuberosity-trochlear groove distance in patellar instability in the young athlete. b Patellar alta evaluation using the CatonDeschamps index, which is the ratio between a line measured between the inferior margin of the patellar articular surface and the anterior aspect of the tibial plateau (black line) and the greatest length of the patellar articular surface (white line). An increased tibial tubercletrochlear groove (TT-TG) indicates a lateralized tibial tuberosity, or a medialized trochlear groove [38]. 2012;40(4):837-844. Tibial tubercletrochlear groove distance (TT-TG) assessment. 4 Sanders TG, Morrison WB, Singleton BA, Miller MD, Cornum KG. A bone bruise occurs anterior to this site of impaction as the patella reduces with knee extension. Other indicated structures: gracilis (G), semitendinosus (ST), and adductor magnus (AM) tendons. J Comput Assist Tomogr 2001; 25:957-962. 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. PubMed Large tears may require surgical suturing repair. The pattern of bone bruising seen in a transient lateral patellar dislocation is easy to understand if one considers the mechanism of injury. The primary aim of surgery is to repair the knee damage and to correct the anomalies that are predisposing to chronic instability. 5 Carrillon Y, Abidi H, Dejour D, et al. 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. 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. Kamel S, Kanesa-Thasan R, Dave J et al. Diederichs G, Issever A, Scheffler S. MR Imaging of Patellar Instability: Injury Patterns and Assessment of Risk Factors. Accessibility Patellar tilt assessment. Ellas et al. . The VMO blends distally with the MPFL to attach to the medial border of the patella along its upper two thirds. Radiology 1993; 189:905-907. Knee Surg Sports Traumatol Arthrosc 15:13011314, Tom A, Fulkerson JP (2007) Restoration of native medial patellofemoral ligament support after patella dislocation. b The patella tilt angle is measured between the posterior condylar line (dashed line) and the maximal patella width (solid line). 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. 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]. Reference article, Radiopaedia.org (Accessed on 02 May 2023) https://doi.org/10.53347/rID-54735, {"containerId":"expandableQuestionsContainer","displayRelatedArticles":true,"displayNextQuestion":true,"displaySkipQuestion":true,"articleId":54735,"questionManager":null,"mcqUrl":"https://radiopaedia.org/articles/lateral-patellar-retinaculum/questions/2393?lang=us"}. 23,29,37 The causative factors of . 1997 Jun;168(6):1493-9. doi: 10.2214/ajr.168.6.9168713. Am J Sports Med. J Bone Joint Surg Am Volume 90:27512762, Dixit S, Deu RS (2017) Nonoperative treatment of patellar instability. Rev Chir Orthop Reparatrice Appar Mot 76:4554, CAS CAS Knee Surg Sports Traumatol Arthrosc 13:522528, Farr J, Schepsis AA (2006) Reconstruction of the medial patellofemoral ligament for recurrent patellar instability. They are best indicated in isolation in the setting of recurrent instability with minimal underlying osseous malalignment (normal TT-TG, minimal trochlear dysplasia). Patella alta is related to a long patellar tendon and is considered a major factor associated with reduced contact area at the patellofemoral joint and a major contributor to patellar instability [33]. The conditions are presented anatomicallyanterior, lateral, medial, or posteriorwith common etiologies, history and physical exam findings, and diagnosis and treatment options for each (see Table, page 28). {"url":"/signup-modal-props.json?lang=us"}, Shetty A, Saber M, Rasuli B, et al. Sports Med Arthrosc Rev 25:7277, Gillespie H (2012) Update on the management of patellar instability. A patient with acute first-time transient patellar dislocation without osteochondral lesions and severe risk factors for redislocation is generally treated conservatively. A facet ratio of < 40% indicates dysplasia. Patellar tilt can also be assessed using the patellofemoral angle (PFA). 5 a-d). Femoral avulsion of the MPFL is a predictor of chronic instability and may be a surgical indication in some patients with acute injury. In patients without osseous malalignment, MPFL reconstruction and plication of the medial restraints is reported to decrease re-dislocation rates to 5%. Ten patients had examination under anaesthesia with . The medial patellofemoral ligament (MPFL) is a condensation of the medial capsule of the knee joint. The natural history. Acta Orthop Belg 72:6571, Panagopoulos A, van Niekerk L, Triantafillopoulos IK (2008) MPFL reconstruction for recurrent patella dislocation: a new surgical technique and review of the literature. Clin Orthop Relat Res 471:26412648, Laurin CA, Dussault R, Levesque HP (1979) The tangential x-ray investigation of the patellofemoral joint: x-ray technique, diagnostic criteria and their interpretation. Stress and shear forces that follow can result in cartilage damage and the development and evolution of osteoarthritis [57]. These are most often found at the inferomedial patella or the lateral femoral condyle [49, 61, 62]. Insights into Imaging 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. Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patelladue to disruptive changes to the medial patellar retinaculum. Bull NYU Hosp Jt Dis 67:2229, Dupuy DE, Hangen DH, Zachazewski JE, Boland AL, Palmer W (1997) Kinematic CT of the patellofemoral joint. Persistent abnormalities of patellar alignment and abnormalities of trochlear morphology are also common, and should be carefully described. 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 lateral patellar retinaculum can also be assessed in this position. PTI of less than 12.5% suggests the presence of patella alta. Because the knee is flexed in dislocation, the patella impacts upon the weightbearing surface of the lateral femoral condyle. Am J Sports Med 2009 37: 2355-2362. The MPFL is composed of a stronger transverse band and a more variable and weaker oblique decussation. The TT-TG distance can be influenced by the degree of knee flexion (reduces with flexion), and it is also smaller upon weight bearing [41]. Crossref, Medline, Google Scholar; 32 Starok M, Lenchikl L, Trudell D, Resnick D. Normal patellar retinaculum: MR and sonographic imaging with cadaveric correlation. AJR Am J Roentgenol. The .gov means its official. Department of Medical Imaging, The Ottawa Hospital, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada, Zaid Jibri,Kawan S. Rakhra&Marcos L. Sampaio, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada, Zaid Jibri,Paul Jamieson,Kawan S. Rakhra,Marcos L. Sampaio&Geoffrey Dervin, Division of Orthopaedic Surgery, The Ottawa Hospital, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada, You can also search for this author in Complete dislocation of the knee: spectrum of associated soft-tissue injuries depicted by MR imaging. The patellar apprehension test is used to assess for lateral instability and is positive when pain or discomfort occurs with lateral translation of the patella. Other structures combine to form the region referred to as the medial retinaculum (MR) more anteriorly. Lateral patellar compression syndrome is the improper tracking of the patella in the trochlear groove generally caused by a tight lateral retinaculum. Osteochondral injuries of the inferomedial patella are seen in up to 70% of patellofemoral dislocations. 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. Knee 10:215220, Terry GC, Hughston JC, Norwood LA (1986) The anatomy of the iliopatellar band and iliotibial tract. 2012 Feb;41(2):137-48. doi: 10.1007/s00256-011-1291-3. Our study focus was to evaluate medial patellofemoral ligament (MPFL) injury patterns and associated knee pathology using Magnetic Resonance Imaging studies. Trauma itself rarely causes patellofemoral dislocations without predisposing factors such as trochlear dysplasia, patella alta and lateralization of the tibial tuberosity. Lateral patellar dislocation. The clinical evaluation can be more challenging in the absence of a dislocation history, and in this scenario, imaging can have a critical role. (28a) A sagittal proton density-weighted image demonstrates the typical hardware location in a patient status post medialization of the tibial tuberosity (arrow). Kirsch M, Fitzgerald S, Friedman H, Rogers L. Transient Lateral Patellar Dislocation: Diagnosis with MR Imaging. 5). MRI and operative studies have revealed that it is almost . Skeletal Radiol 30:484495, Tsujimoto K, Kurosaka M, Yoshiya S, Mizuno K (2000) Radiographic and computed tomographic analysis of the position of the tibial tubercle in recurrent dislocation and subluxation of the patella. In a series of 474 patients with anterior knee pain, patellar tilt or subluxation was present in 40% of the cases on axial MRI [46]. ity. (19a) The corresponding STIR coronal image reveals the large displaced osteochondral fragment (arrow) at the lateral aspect of the lateral femoral condyle. Arthroscopy 22:643649, Carrillon Y, Abidi H, Dejour D, Fantino O, Moyen B, Tran-Minh VA (2000) Patellar instability: assessment on MR images by measuring the lateral trochlear inclination-initial experience. 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. Do a thorough work-up of the patient at the clinic to determine the need for a redesign total knees arthroplasty (Figs. In order for the patella to engage with the femoral trochlea, a higher degree of flexion than normal is needed. Several methods have been used to assess patella alta. 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. This treatment generally consists of the use of anti-inflammatory medications, a short period of immobilization (36weeks) followed by a progressive physiotherapy regimen with focus on range of motion, closed chain exercises, and vastus medialis obliquus strengthening [16, 65,66,67,68,69,70]. Lateral patellar tilt is a sensitive marker for patellar instability [45]. Falls. ADVERTISEMENT: Supporters see fewer/no ads. These measurements are not routinely recorded in the MRI report, but in select situations may be helpful in quantifying low-grade versus high-grade dysplasia. It is composed of Lockwood's ligament (inferior suspensory ligament), the lateral extension or horn of the levator aponeurosis, the continuations of the pretarsal and preseptal muscles, and the check ligament of the lateral rectus muscle. Magnetic Resonance Imaging Characteristics of the Medial Patellofemoral Ligament Lesion in Acute Lateral Patellar Dislocations Considering Trochlear Dysplasia, Patella Alta, and Tibial Tuberosity-Trochlear Groove Distance Am J Sports Med 28:472479, Lewallen L, McIntosh A, Dahm D (2015) First-time patellofemoral dislocation: risk factors for recurrent instability. PubMed Central The rectus femoris (RF), vastus lateralis (VL), and lateral retinaculum (LR) are also indicated. At 0 extension, the patellar may lie completely above the level of the trochlea, without direct apposition between the two articular surfaces. Osteochondral injuries to the inferomedial patella may be the result of impaction during dislocation or shearing with reduction. Lateral Patellar Dislocation. The stability of the patella is dependent on both osseous anatomy and the integrity of longitudinal and transverse soft tissue stabilizers. For CT evaluation of the patellofemoral joint, patients are positioned supine, with mild external rotation of up to 15 with padding as needed to facilitate a relaxed state of the quadriceps musculature. Int Orthop. Areas of scarring and osteochondral lesions become more common as the frequency of patellar dislocation increases. J Knee Surg 28:303309, Hevesi M, Heidenreich MJ, Camp CL et al (2019) The recurrent instability of the patella score: a statistically based model for prediction of long-term recurrence risk after first-time dislocation. Soft tissue procedures are designed to repair or tighten stretched and injured soft tissues contributing to patellar stability. Guidelines and Gamuts in Musculoskeletal Ultrasound. Correspondingly, the patella must shift slightly medially during early flexion to engage the trochlear groove. Although you may feel that being asked to make the specific diagnosis of lateral patellar dislocation from a single image is unrealistic, the coronal view in fact reveals a classic and highly characteristic appearance, allowing the diagnosis to be made with confidence. 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. 4. Google Scholar, Diederichs G, Issever AS, Scheffler S (2010) MR imaging of patellar instability: injury patterns and assessment of risk factors. Patellar maltracking occurs as a result of an imbalance in the dynamic relationship between the patella and trochlea. Anatomical and radiology atlas of the abdomen and pelvis based on anatomical diagrams and cross-sectional CT and MRI imaging. 7). Additionally, MRs ability to delineate the extent of injury and predisposing factors is important in patient care and surgical planning. In eight of 17 patients, the mechanism of injury was a patellar tendon tear (n = 1) or valgus hyperextension (n = 7). A newer method to assess for patella alta is the patellotrochlear index (PTI), which is measured in the midsagital MRI as the ratio of the length of trochlear cartilage engaged with the patella to the patellar cartilage length [36]. Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella Injury to the medial retinaculum, MPFL, and VMO may be identified at MR imaging after acute LPD. AJR Am J Roentgenol. Isacsson A, Olsson O, Englund M, Frobell RB. Early diagnosis is essential, as chronic maltracking will lead to patellofemoral cartilage damage and osteoarthritis [3]. Surgical repair is most commonly directed to MPFL reconstruction and to distal realignment in the subset of patients who have significant osseous malalignment. (12a) At an axial image 3 cm proximal to the femoral-tibial joint space, the lengths of the medial and lateral trochlear facets are obtained. At less than 30 of flexion, asymptomatic knees may demonstrate physiologic patellar tilt or subluxation. In acute patellar dislocation, CT may demonstrate osseous impaction or fractures of the medial margin of the patella (with or without involvement of the articular surface) and/or the lateral surface of the lateral femoral condyle and intraarticular fragments. Incidence and concomitant chondral injuries in a consecutive cohort of primary traumatic patellar dislocations examined with sub-acute MRI. James M. Provenzale, Rendon C. Nelson, Emily N. Vinson. The discrimination between low-grade and high-grade dysplasia is important because prognosis and treatment may depend upon the severity of trochlear dysplasia. 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. First, a line is drawn paralleling the posterior femoral condyles surfaces. Understanding the biomechanics of these joints is essential to investigating and appropriately treating patellofemoral joint pathology. Curr Sports Med Rep 11:226231, Jain NP, Khan N, Fithian DC (2011) A treatment algorithm for primary patellar dislocations. The patella articulates with the trochlear groove of the anterior femur, which has corresponding lateral and medial patellar articular surfaces [6]. Trochleoplasty is rarely performed in this country and is reserved for significant dysplasias or when other surgical options have been insufficient in restoring patellofemoral stability.

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