The Insall-Salvati index is the most widely accepted measurement and is easily performed on radiographs and MRI examinations. With knee extension and subsequent reduction, the patella bounces back into position and in doing so, the medial patella impacts against the non-weightbearing anterolateral aspect of the lateral femoral condyle, resulting in the characteristic marrow edema pattern. 9). What is the treatment for a patellar retinaculum tear? e-Anatomy, the Anatomy of Imaging - IMAIOS They are best indicated in isolation in the setting of recurrent instability with minimal underlying osseous malalignment (normal TT-TG, minimal trochlear dysplasia). Current Concepts Regarding Patellofemoral Trochlear Dysplasia. Lateral patellar retinaculum | Radiology Reference Article 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). Despite this, there remains considerable variation in surgical technique including graft choice, position, and tension making the literature difficult to compare [8, 15, 79,80,81,82,83,84,85,86]. A Focal Defect at the Lateral Patellar Retinaculum on Clinical Knee MRI The lateral patellar retinaculum is less commonly injured than the medial patellar retinaculum, however it is often disrupted during surgery to correct abnormal lateral patellar tracking or dislocation 3. The patella remains laterally shifted (blue arrow) and an osteochondral injury of the medial patella (arrowheads) is apparent. a Normal trochlea. Advantages of CT over MRI include the reduced cost, larger gantry diameter allowing to fit larger patients, faster acquisition with less potential for claustrophobia, fewer absolute and relative contraindications related to implanted devices, and better cortical bone definition. 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. 2000; 216:858-864. California Privacy Statement, Patellar tilt can also be assessed using the patellofemoral angle (PFA). The Anterolateral Ligament of the Knee: MRI Appearance, Association A commonly used one is the InsallSalvati ratio of patellar tendon length: patellar length. Significantly greater lateral patellar displacement and tilt was found in osteoarthritis patients compared to a control group [3]. 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. On MRI, impingement is usually manifested as high signal intensity within the superolateral aspect of the infrapatellar fat pad on fluid-sensitive sequences (edema) (Fig. Lateral patellar dislocation is a common clinical entity with a characteristic MR appearance. Lateral patellar tilt is a sensitive marker for patellar instability [45]. Patellofemoral Pain Syndrome Exercises - sports injury rehabilitation Provided by the Springer Nature SharedIt content-sharing initiative. MRI and operative studies have revealed that it is almost . 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. Direct impact to the front of the knee from a fall or other blow is a common cause of tears. Eur J Trauma Emerg Surg. It is therefore recommended that radiologists include measurement of TT-TG in reports on patients who undergo MRI for patellar instability. As the knee joint ranges from extension to flexion, the articular surface area of the patella is in contact with the femur changes. Medial patellofemoral ligament injury patterns and associated pathology Jumping. Observer Agreement on the Dejour Trochlear Dysplasia Classification: A comparison of true lateral radiographs and axial magnetic resonance images. 8 Lippacher S, Dejour S, Elsharkawi M, et al. Knee Surg Sports Traumatol Arthrosc 14:264272, McNally EG, Ostlere SJ, Pal C, Phillips A, Reid H, Dodd C (2000) Assessment of patellar maltracking using combined static and dynamic MRI. and transmitted securely. The lateral retinaculum provides significant additive support to the medial stabilizers. Each of the mentioned assessment methods of patella alta has its own advantages and limitations. Stretching exercises for Patellofemoral pain. A tear of the reconstructed MPFL is indicated by fluid interrupting the fibers (27a, long arrow) (27b, arrowheads). The latter distinction is important to recognize among both radiologists and surgeons. (2a) In this case, it is the bone bruise within the anterolateral aspect of the lateral femoral condyle (long arrow) and the edema adjacent to the medial femoral condyle (arrowhead) that are the key to the diagnosis. This can provide a road map for formulating a treatment strategy that would be primarily aimed at stabilizing the patellofemoral joint to halt or slow the progression of articular cartilage loss. Because of the transient and brief nature of lateral patellar dislocations, the diagnosis is frequently unrecognized by both patients and clinicians. A focused history of the mechanism, number, and circumstances of instability to date is essential. Clin Sports Med 21:521546 x, Article It has been suggested that fat impingement occurs between the lateral femoral condyle and the posterior aspect of the patellar tendon [54]. A trochlear depth of < 3mm indicates dysplasia. In patients without osseous malalignment, MPFL reconstruction and plication of the medial restraints is reported to decrease re-dislocation rates to 5%. Normal TD > 5.2mm. These prevailing anatomic indices feature prominently into the probability of recurrence, and understanding their variability and pathophysiology is critical to successful management of these patients. Radiology. 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. Magnetic Resonance Cholangiopancreatography MRI PREMIUM Digestive system Illustrations PREMIUM CT axial male abdomen and pelvis CT PREMIUM CT peritoneal cavity CT PREMIUM MRI female pelvis MRI PREMIUM Female pelvis 5). 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. 1995 Jan;164(1):135-9. doi: 10.2214/ajr.164.1.7998526. 21 Patellar dislocation not only has a high recurrence rate 51 but also readily causes articular cartilage damage, osteochondral fractures, and patellofemoral arthritis, which can ultimately lead to motor dysfunction and pain. This allows for greater detailed evaluation of the patellar and trochlear morphology, patellofemoral relationship, and status of the joint. This results in a slightly superolateral direction of pull on the patella by the quadriceps. Lateral patellar dislocation results in bone contusion at the medial patella and along the lateral aspect of the lateral femoral condyle. PMID: 9168713. Complete dislocation of the knee: spectrum of associated soft-tissue injuries depicted by MR imaging. Methods: We compared 361 treated cases of aneurysm occlusion after subarachnoid hemorrhage from 1997 to 2003 with 281 cases from 2006 to 2014. 8,12,18,28 In knees from cadavers, repair of the medial patellofemoral ligament is not only sufficient, but necessary to restore lateral patellar mobility to within a normal range. Patellar maltracking: an update on the diagnosis and treatment Google Scholar, Nakagawa S, Kadoya Y, Kobayashi A, Tatsumi I, Nishida N, Yamano Y (2003) Kinematics of the patella in deep flexion. Edema and thickening compatible with tears of the MPFL and medial retinaculum (red arrows) are apparent both anteriorly and posteriorly. However, in the setting of osseous malalignment, MPFL reconstruction alone leads to higher rates of recurrent instability. Lateral Patellar Compression Syndrome - Knee & Sports - Orthobullets Am J Sports Med 16:244249, Hawkins RJ, Bell RH, Anisette G (1986) Acute patellar dislocations. 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. Disclaimer. There are several different techniques described in the literature to assess patella alta and many of these are reviewed in detail in the MRI Web Clinic, August 20106. There are numerous techniques reported in literature and commonly used to reconstruct the medial sided soft tissue constraints. Distally, it attaches to the tibial tubercle via the patellar tendon. The most common trochleoplasty procedure described is a combination of lateral trochlear osteotomy and bone graft to heighten the lateral trochlea. (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. Stretching a Lateral Retinaculum of the Knee | livestrong 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. 4. PubMed In: Miller M, Thompson S (ed) DeLee and Drezs orthopaedic sports medicine. In this section, we will emphasize the role of MRI and discuss how CT can also have value when assessing patellar maltracking. It is a geometric abnormality of the trochlear groove that affects its shape and depth mainly at its superior part, which can result in abnormal tracking of the patella along the trochlea. 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. The MPFL is best seen on axial MRI on the slice just distal to the VMO. 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). 5). Patellar sleeve avulsion fracture in a patient with Sinding-Larsen This procedure involves removal of cancellous bone beneath the trochlea followed by fixation of the articular surface [88, 89]. Patella alta assessment. Check for errors and try again. 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 mechanism is commonly a non-contact twisting injury of the lower extremity with the knee extended and external rotation of the foot and is perceived as the knee giving way. The patella will often self-reduce by reflexic contraction of the quadriceps muscles. provided a morphologic classification system for trochlear dysplasia describing four types [26,27,28]. However, the patella starts to engage with the trochlea by 30 and is typically completely engaged by 45. Eur Radiol 22:418428, Sonin AH, Pensy RA, Mulligan ME, Hatem S (2002) Grading articular cartilage of the knee using fast spin-echo proton density-weighted MR imaging without fat suppression. Int Orthop 34:311316, Donell ST, Joseph G, Hing CB, Marshall TJ (2006) Modified Dejour trochleoplasty for severe dysplasia: operative technique and early clinical results. Operative lateral retinaculum release is indicated in refractory cases. Insights Imaging 10, 65 (2019). Patellar maltracking occurs as a result of an imbalance in the dynamic relationship between the patella and trochlea. 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. MRI has been found to be 85%-92% sensitive for diagnosing MPFL injury (Seeley, 2013). Knee Surg Sports Traumatol Arthrosc 15:13011314, Tom A, Fulkerson JP (2007) Restoration of native medial patellofemoral ligament support after patella dislocation. AJR Am J Roentgenol 169:211215, Buchner M, Baudendistel B, Sabo D, Schmitt H (2005) Acute traumatic primary patellar dislocation: long-term results comparing conservative and surgical treatment. Nontraumatic Knee Pain: A Diagnostic & Treatment Guide The authors declare that they have no competing interests. Chronic fat impingement can result in chronic inflammation and fat pad hypertrophy. 2021 Dec 8;11(12):1360. doi: 10.3390/life11121360. eCollection 2015. Created for people with ongoing healthcare needs but benefits everyone. AIM: To describe the sonographic appearances of the medial retinacular (MPFR) complex of the knee in patients with acute and recurrent patellar dislocation.MATERIALS AND METHODS: Thirty patients were scanned within 2-4 weeks of an acute episode of lateral patellar dislocation. 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. 1997 Jun;168(6):1493-9. doi: 10.2214/ajr.168.6.9168713. In fact, most patellar maltracking occurs between extension and the first 30 of flexion. Both MRI and ultrasound are accurate imaging modalities in the detection of MPFL injuries [5, 50, 51]. AJR Am J Roentgenol. Radiology 189:905907, Warren LF, Marshall JL (1979) The supporting structures and layers on the medial side of the knee: an anatomical analysis. The ensuing loss of medial restraint favors future patellar dislocations, especially if additional risk factors are present. Patellar tendon lateral femoral condyle friction syndrome is one of several entities that result in anterior knee pain and in which abnormalities of the patellar fat pads are found on MR imaging. Failure to identify or treat injury to the patellar retinaculum is associated with recurrent patellar instability and contributes to significant morbidity. Early detection particularly in the stage preceding the development of significant cartilaginous loss and osteoarthritis is critical. 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. Fluid extending into the VMO myotendinous junction is generally seen in the setting of coexisting MPFL/retinacular tears. A typical bone bruise is seen within the anterolateral aspect of the lateral femoral condyle (asterisk). 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 ]. MRI, given its superior soft tissue contrast and multi-planar capability, has emerged as the modality of choice in evaluating articular cartilage abnormalities. Several methods have been used to assess patella alta. Thus, to assess for maltracking specifically, a multi-stage CT with a variable number of repeated acquisitions at variable degrees of flexion can also be performed [57]. quadricepsplasty rehab protocol Division of Sports Trauma, Department of Orthopaedics, Aarhus University Hospital, Aarhus, Denmark. Distal neurovascular examination also needs to be performed [16]. Twenty-seven knees in 21 patients were studied and the mean age of the patients at surgery was 19 years. The pages that follow contain general guidance on the diagnosis and treatment of chronic nontraumatic knee pain. (PDF) Magnetic Resonance Imaging Characteristics of the Medial 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% . 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. Knee 10:215220, Terry GC, Hughston JC, Norwood LA (1986) The anatomy of the iliopatellar band and iliotibial tract. CAS Although edema can be seen in other peripatellar fad pads on MRI, there is no clear association between patellar maltracking and prefemoral fat pad edema or with that at the suprapatellar fat pad [56]. Curr Rev Musculoskelet Med 11:253260, Article Pediatric Lateral Patellar Retinacular Sleeve Avulsion - JOSPT Trochlear geometry, including slope of the lateral wall and depth, is an important factor. Epub 2010 Mar 8. volume10, Articlenumber:65 (2019) Prior lateral patellar dislocation: MR imaging findings. Traumatic lateral patellar dislocation is a common injury among young, athletic individuals and is generally transient in nature. During this dislocation phase of injury, shearing forces can damage the articular surfaces of either the patella or the lateral femoral condyle. 3 Dirim B, Haghighi P, Trudell D et al. This is the ratio between a line measured between the inferior margin of the patellar articular surface and the anterior aspect of the tibial plateau and the greatest length of the patellar articular surface. Acta Orthop Scand 68:419423, Deie M, Ochi M, Sumen Y, Adachi N, Kobayashi K, Yasumoto M (2005) A long-term follow-up study after medial patellofemoral ligament reconstruction using the transferred semitendinosus tendon for patellar dislocation. Medial retinacular complex injury in acute patellar dislocation: MR findings and surgical implications. It has been shown that ossification in the medial patellar stabilizers correlates with prior injury to these structures [53]. Patellar Fat Pad Abnormalities - Radsource 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. Rev Bras Ortop 46:160164, LeGrand AB, Greis PE, Dobbs RE, Burks RT (2007) MPFL reconstruction. (27a) Axial and (27b) coronal fat suppressed proton density-weighted images in a patient who experienced recurrent patellar dislocation following surgery. 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. 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.
