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 The most obvious presentation of patellar maltracking is that of the first time lateral patellar instability or recurrent instability thereafter. A study has found that the femoral groove tends to be shallower in osteoarthritis patients compared to those with normal cartilage, regardless of age. 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. The natural history. The convex articular surface of the patella places it at risk for chondral injury in either the dislocation or the reduction phases of injury. It acts as a powerful extensor of the knee. Lateral patellar compression syndrome is the improper tracking of the patella in the trochlear groove generally caused by a tight lateral retinaculum. Springer, New York, pp 1529, Cash JD, Hughston JC (1988) Treatment of acute patellar dislocation. PubMed Central 8600 Rockville Pike Reconstruction of the MPFL has recently become an increasingly popular procedure for recurrent lateral patellar instability. Patella alta is considered an important factor in patellar instability. 2). (26a) An axial proton density-weighted image reveals trochlear dysplasia (line, indicating facet asymmetry and a shallow trochlear groove), ossification in the medial retinaculum and MPFL attachment anteriorly (short arrow) and diffuse scarring of the medial retinaculum (arrowheads)--these findings indicate chronic patellofemoral instability. From this insertion, it extends posteriorly to blend with the lateral margin of the knee capsule and inferior surface of the lateral tibial condyle 1,2. Specialists of neuroradiology and vascular neurosurgery decided over the modality assignment. 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. The anatomy of the medial patellofemoral ligament. 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. Knee Surg Sports Traumatol Arthrosc 13:522528, Farr J, Schepsis AA (2006) Reconstruction of the medial patellofemoral ligament for recurrent patellar instability. Are you sure you want to trigger topic in your Anconeus AI algorithm? (16a) An axial fat-suppressed T2-weighted image reveals numerous typical findings of recent lateral patellar dislocation. Cite this article. In eight of 17 patients, the mechanism of injury was a patellar tendon tear (n = 1) or valgus hyperextension (n = 7). The lateral trochlear articular surface is usually more prominent than its medial portion. 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. Less common predisposing factors to be aware of include laterally tilted patella, VMO dysplasia and generalized joint laxity. In: Miller M, Thompson S (ed) DeLee and Drezs orthopaedic sports medicine. The patients are then J-braced for 3 to 6 months for all sports activities. Magn Reson Med Sci 17:195202, Elias DA, White LM (2004) Imaging of patellofemoral disorders. Medial patellofemoral ligament: cadaveric investigation of anatomy with MRI, MR arthrography, and histologic correlation. The .gov means its official. 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. 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]. A ratio of >1.3 is considered indicative of patella alta [34] (Fig. The deep layer is comprised of the lateral patellofemoral ligament, patellotibial band and transverse ligament. Edema and thickening compatible with tears of the MPFL and medial retinaculum (red arrows) are apparent both anteriorly and posteriorly. CT of both knees in 20 flexion demonstrating bilateral shallow trochlear groove (arrows) compatible with dysplasia and bilateral lateral patellar subluxation and lateral tilt. The knee then was flexed 30, 60, 90, and 120, and the transducer recorded changes in tension within the lateral patellofemoral . MR findings were correlated with clinical, surgical, and arthroscopic findings. Osteochondral fractures are common in acute or recurrent transient lateral patellar dislocation, seen in up to 70% of cases. A lateral patellar sleeve fracture can be misdiagnosed Clin Sports Med 21:521546 x, Article Patellar dislocation; Knee; Medial patellofemoral ligament; Recurrence; MRI Go to: INTRODUCTION Lateral patellar dislocation (LPD) is a common injury that typically occurs in young, active patients as a result of a variety of activities and accounts for approximately 2-3% of all knee injuries ( 1 ). 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? HHS Vulnerability Disclosure, Help 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. Objective: Must rule out a tight iliotibial band (ITB) and weak quadriceps muscles (Juhn). Additionally, MRs ability to delineate the extent of injury and predisposing factors is important in patient care and surgical planning. CAS Unable to process the form. Kim et al. Quinn described the MRI findings following acute patellar dislocation as contusion or impaction of the medial patellar facet and lateral femoral condyle, along with injury of the medial retinaculum and/or medial patellofemoral ligament (MPFL) (Quinn, 1993). Skeletal Radiol 38:785790, Campagna R, Pessis E, Biau DJ et al (2012) Is superolateral Hoffa fat pad edema a consequence of impingement between lateral femoral condyle and patellar ligament? The radiograph can be helpful in the acute presentation in detecting fractures in the setting of lateral (often transient) patellar dislocation. AJR Am J Roentgenol. Patients with patella alta may also benefit from tibial tuberosity advancement. A 2015 Cochrane Review concluded that there is no significant increase in functional scores between nonoperative and operative management; however, surgical management does result in a significantly lower risk of recurrent dislocation at the cost of surgical complications [19]. (7a) A coronal T1-weighted image at the level of the patella demonstrates blending of fibers of the VMO with the MPFL superiorly. The VMO blends distally with the MPFL to attach to the medial border of the patella along its upper two thirds. Recurrent dislocations and chronic patellofemoral joint instability will lead to significant cartilage damage and severe arthritis if left untreated. 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. 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. 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. The patella remains laterally subluxed and tilted, and the patient has an abnormally shallow trochlear groove (line). Medial patellofemoral ligament injury following acute transient dislocation of the patella: MR findings with surgical correlation in 14 patients. The deep layer of the lateral retinaculum contains thickenings that form ligaments providing stabilizing support to the patella. The trochlea, due to its large surface area and concave contour, is rarely subject to chondral injury in patellar dislocation. Bethesda, MD 20894, Web Policies The patella becomes unstable and undergoes a transient, violent lateral displacement. Other structures that blend in this region include the medial patellotibial ligament, the medial patellomeniscal ligament, the investing fascia, and the medial joint capsule. LTI < 11 degrees indicates dysplasia. J Bone Joint Surg Am 89:17491755, PubMed Curr Rev Musculoskelet Med 11:253260, Article 2021;50(7):1399-409. It is reported in surgical literature that 50-75% of recurrent dislocators, have some form of dysplasia, malalignment or generalized joint laxity. J Bone Joint Surg Am Volume 90:27512762, Dixit S, Deu RS (2017) Nonoperative treatment of patellar instability. 23,29,37 The causative factors of . the patellar retinaculum at the dynamic examination (Fig. Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patella due to disruptive changes to the medial patellar retinaculum. (13a) A line is drawn between the cortex of the lateral trochlear facet on the most superior axial image showing cartilage. Lateral trochlear inclination is another quantitative method to diagnose trochlear dysplasia. Am J Sports Med 16:244249, Hawkins RJ, Bell RH, Anisette G (1986) Acute patellar dislocations. is a term coined for anatomic characteristics that lead to an increased Q angle and an exacerbation of patellofemoral dysplasia. Clin Orthop Relat Res 144:1626, Elias DA, White LM, Fithian DC (2002) Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella. PMC Physical Therapy. MRI has been found to be 85%-92% sensitive for diagnosing MPFL injury (Seeley, 2013). . High resolution magnetic resonance imaging of the patellar retinaculum: normal anatomy, common injury patterns, and pathologies. A commonly used one is the InsallSalvati ratio of patellar tendon length: patellar length. Migliorini F, Marsilio E, Cuozzo F, Oliva F, Eschweiler J, Hildebrand F, Maffulli N. Life (Basel). Dr. Frederick Buechel, Jr. MD answered. The distance (double-headed arrow) from the deepest point of the trochlea (line B) to the middle of the tibial tubercle (line A) is measured, again by using the posterior plane of the condyles as the reference line (line C). AJR Am J Roentgenol. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. The main morphological features associated with patellar maltracking are trochlear dysplasia, lateralization of the tibial tuberosity, patella alta, and lateral patellar tilt. The tight structures of the knee such as the lateral retinaculum need to be stretched and mobilized. Observer Agreement on the Dejour Trochlear Dysplasia Classification: A comparison of true lateral radiographs and axial magnetic resonance images. Value of the tibial tuberosity-trochlear groove distance in patellar instability in the young athlete. (18a) A 13-year-old female following acute patellar dislocation. Please enable it to take advantage of the complete set of features! J Orthop Sports Phys Ther 2017;47(10):815. doi:10.2519/ jospt.2017.6616 . a Axial PDFS right knee MR image at the level of the trochlear groove. Given the lack of history of direct trauma, a reliable diagnosis can be made. In order for the patella to engage with the femoral trochlea, a higher degree of flexion than normal is needed. Google Scholar, Miller TT, Staron RB, Feldman F (1996) Patellar height on sagittal MR imaging of the knee. (23a) In this patient with recurrent patellofemoral dislocations, there are findings of subchondral degeneration (arrow) from recurrent impaction and chondral shearing injuries to the inferolateral femoral condyle. AJR Am J Roentgenol. Because the knee is flexed in dislocation, the patella impacts upon the weightbearing surface of the lateral femoral condyle. (22a) In this patient with an acute first time patellar dislocation injury, typical bone bruises were not apparent. 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]. 1 Pain is often described as medial because of soft tissue injuries that occur to the medial retinaculum and/or MPFL. no financial relationships to ineligible companies to disclose. ANTERIOR KNEE PAIN Duke Radiology Case Review. The pattern of bone bruising seen in a transient lateral patellar dislocation is easy to understand if one considers the mechanism of injury. 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. Open Orthop J. The ensuing loss of medial restraint favors future patellar dislocations, especially if additional risk factors are present. The lateral patellar retinaculum is a fibrous expansion comprising of superficial and deep layers. 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. Operative lateral retinaculum release is indicated in refractory cases. Epub 2011 Nov 9. California Privacy Statement, It was shown that certain features of patellar maltracking (increased sulcus angle, lateral patellar tilt, and a higher patellar tendon to patellar length ratio) are associated with cartilage loss and bone marrow lesions [59]. The knee is a complex joint with separate tibio-femoral and the patellofemoral articulations. Patients who experience multiple patellar dislocations are more likely to have anatomical variants of the trochlea, patellar alta, or tibial tubercle lateralization. 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. Patellar maltracking occurs as a result of imbalance of this relationship often secondary to anatomic morphologic abnormality. PFA of 0 or if it opens medially (negative value) is considered abnormal indicating lateral patellar tilt [27, 48]. Most, however, agree regarding the importance of the MPFL and its role as the strongest restraint to lateral patellar displacement. However, the use of this method is not widespread. The lateral patellar retinaculum (LPR) is located on the anterolateral aspect of the knee joint and extends to the femur transversely and obliquely from the lateral margin of the patella [].It plays an important role in patellar stability, and patellar instability can be caused by abnormal tension or tightness in the LPR [].The LPR is a complex structure composed of various merging fascial layers. Treatment is nonoperative with physical therapy focusing on quadriceps stretching and strengthening. 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. These are most often found at the inferomedial patella or the lateral femoral condyle [49, 61, 62]. Lastly, a sulcus-deepening procedure known as trochleoplasty may be indicated in the patient with significant trochlear dysplasia and recurrent instability. Another method is the CatonDeschamps index. 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. 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. Eur J Trauma Emerg Surg. Knee Surg Sports Traumatol Arthrosc 15:13011314, Tom A, Fulkerson JP (2007) Restoration of native medial patellofemoral ligament support after patella dislocation. Injury. Early detection particularly in the stage preceding the development of significant cartilaginous loss and osteoarthritis is critical. The ratio of the medial to the lateral facet length defines trochlear facet asymmetry (MT/LT) *100%. The close association of the MR with the MCL is also apparent. This short surgical video demonstrates an arthroscopic lateral release as seen from inside the knee. Arthroscopy 23:305311, Kolowich PA, Paulos LE, Rosenberg TD, Farnsworth S (1990) Lateral release of the patella: indications and contraindications. Am J Sports Med. 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. (1a) A single fat-suppressed proton density-weighted coronal image. 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. 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. When the knee moves slightly out of place or becomes tilted in the joint, it can cause tension and pain in the lateral retinaculum. Federal government websites often end in .gov or .mil. However, in the setting of osseous malalignment, MPFL reconstruction alone leads to higher rates of recurrent instability. The lateral retinaculum or lateral canthus is a complex integration of a number of structures. For first-time dislocators without intra-articular loose bodies or chondral injury, a trial of nonoperative therapy is indicated. The literature in this field has been extremely heterogeneous, and this has made clinical guidelines difficult to produce. 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). The trochlear groove and patella may have abnormal morphology that predisposes to patellar dislocation. 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].