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. 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. Dr. Frederick Buechel, Jr. MD answered. 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. Pedersen ME, DaCambra MP, Jibri Z, Dhillon S, Jen H, Jomha NM. lateral patellar retinacular sleeve, mak-ing this particular avulsion a rare oc-currence. The axial proton density-weighted image reveals a large osteochondral shearing injury involving the mid to medial patella (arrowheads). Division of Sports Trauma, Department of Orthopaedics, Aarhus University Hospital, Aarhus, Denmark. A study has found that the femoral groove tends to be shallower in osteoarthritis patients compared to those with normal cartilage, regardless of age. Knee Surg Sports Traumatol Arthrosc 14:707712, Ahmad M, Janardhan S, Amerasekera S, Nightingale P, Ashraf T, Choudhary S (2019) Reliability of patellotrochlear index in patellar height assessment on MRI-correction for variation due to change in knee flexion. 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. 8). California Privacy Statement, It thickens as it inserts onto the lateral border of the patella, quadriceps tendon and patellar ligament. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Stretching this ligament keeps the patella in place and the ligament healthy. Soft tissue procedures are designed to repair or tighten stretched and injured soft tissues contributing to patellar stability. This procedure involves removal of cancellous bone beneath the trochlea followed by fixation of the articular surface [88, 89]. AJR Am J Roentgenol. The AIUM Practice Parameter for the Performance of the Musculoskeletal (18a) A 13-year-old female following acute patellar dislocation. Patellar maltracking: an update on the diagnosis and treatment strategies, https://doi.org/10.1186/s13244-019-0755-1, http://creativecommons.org/licenses/by/4.0/. 2021 Dec 8;11(12):1360. doi: 10.3390/life11121360. a Sagittal PD knee MRI showing the method of assessing the InsallSalvati index, calculated as the ratio of the patellar tendon length at its inner aspect (white dashed line) to the greatest diagonal length of the patella (white line). 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. Operative lateral retinaculum release is indicated in refractory cases. This is often secondary to an underlying structural abnormality. The ensuing loss of medial restraint favors future patellar dislocations, especially if additional risk factors are present. 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 (27a) Axial and (27b) coronal fat suppressed proton density-weighted images in a patient who experienced recurrent patellar dislocation following surgery. The latter distinction is important to recognize among both radiologists and surgeons. 1Department of Radiology, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, 149 Sangil-dong, Gangdong-gu, Seoul 134-727, Korea. 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. J Bone Joint Surg Am Volume 90:27512762, Dixit S, Deu RS (2017) Nonoperative treatment of patellar instability. PubMed The radiograph can be helpful in the acute presentation in detecting fractures in the setting of lateral (often transient) patellar dislocation. 1993;161(1):109-13. The purpose of this article is to discuss the clinical and radiologic evaluation of patellar maltracking providing an update on the cross-sectional imaging assessment and also a synopsis of the management options. Traumatic lateral patellar dislocation is a common injury among young, athletic individuals and is generally transient in nature. 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. 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. This distance is the trochlear sulcus depth (TD). 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. Usually, young individuals, particularly women, suffer the consequences of this disorder [2]. MRI, given its superior soft tissue contrast and multi-planar capability, has emerged as the modality of choice in evaluating articular cartilage abnormalities. Epidemiology Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in sports activities. Less than 3-mm trochlear depth is indicative of trochlear dysplasia [24]. Our study focus was to evaluate medial patellofemoral ligament (MPFL) injury patterns and associated knee pathology using Magnetic Resonance Imaging studies. A tear of the retinaculum is mostly seen after dislocation of the patella. J Pediatr Orthop 37:484490, Parikh SN, Lykissas MG, Gkiatas I (2018) Predicting risk of recurrent patellar dislocation. 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. (13a) A line is drawn between the cortex of the lateral trochlear facet on the most superior axial image showing cartilage. Google Scholar, Pfirrmann CW, Zanetti M, Romero J, Hodler J (2000) Femoral trochlear dysplasia: MR findings. Elsevier, Philadelphia, Buckens CF, Saris DB (2010) Reconstruction of the medial patellofemoral ligament for treatment of patellofemoral instability: a systematic review. PubMed Radiology. b Axial MRI at the level of the tibial tuberosity. a Normal trochlea. However, the patella starts to engage with the trochlea by 30 and is typically completely engaged by 45. 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. 2000; 216:858-864. Int Orthop. 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. 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. Knee Surg Sports Traumatol Arthrosc 13:522528, Farr J, Schepsis AA (2006) Reconstruction of the medial patellofemoral ligament for recurrent patellar instability. An official website of the United States government. There is agreement, however, that the MPFL is almost always injured with lateral patellar dislocations4. Guidelines and Gamuts in Musculoskeletal Ultrasound. 2012;40(4):837-844. Rev Bras Ortop 46:160164, LeGrand AB, Greis PE, Dobbs RE, Burks RT (2007) MPFL reconstruction. 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. Medial retinacular complex injury in acute patellar dislocation: MR The patellar usually relocates, and the typical bone contusions are the key MRI features to diagnose transient lateral patellar dislocation (Fig. This injury has been described in conjunction with numerous sports activities, particularly snow skiing. Am J Sports Med 40:11191125, Boutris N, Delgado DA, Labis JS, McCulloch PC, Lintner DM, Harris JD (2018) Current evidence advocates use of a new pathologic tibial tubercle-posterior cruciate ligament distance threshold in patients with patellar instability. 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. Arthroscopy 23:305311, Kolowich PA, Paulos LE, Rosenberg TD, Farnsworth S (1990) Lateral release of the patella: indications and contraindications. Because the knee is flexed in dislocation, the patella impacts upon the weightbearing surface of the lateral femoral condyle. An increased tibial tubercletrochlear groove (TT-TG) indicates a lateralized tibial tuberosity, or a medialized trochlear groove [38]. 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. Springer, New York, pp 1529, Cash JD, Hughston JC (1988) Treatment of acute patellar dislocation. Large tears may require surgical suturing repair. {"url":"/signup-modal-props.json?lang=us"}, Moodaley P, Hng J, Hacking C, et al. The VMO blends distally with the MPFL to attach to the medial border of the patella along its upper two thirds. 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 medial patellar retinaculum is part of the anterior third of the medial joint capsule. Specialists of neuroradiology and vascular neurosurgery decided over the modality assignment. 2006;187(5):1332-7. Early detection particularly in the stage preceding the development of significant cartilaginous loss and osteoarthritis is critical. (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. Primary traumatic patellar dislocation | Journal of Orthopaedic Surgery The knee then was flexed 30, 60, 90, and 120, and the transducer recorded changes in tension within the lateral patellofemoral . The trochlea, due to its large surface area and concave contour, is rarely subject to chondral injury in patellar dislocation. Most commonly the patella tracks outwards (laterally) so the muscles on the inside of the thigh need strengthening. Knee 13:266273. The lateral retinaculum provides significant additive support to the medial stabilizers. 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. Radiographics. In effect all three medial layers of the knee thus comprise the medial retinaculum, which is by itself not a discrete, single structure. Chronic fat impingement can result in chronic inflammation and fat pad hypertrophy. 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. Peroneal Tendon Dislocation and Superior Peroneal Retinaculum Injury Despite non-operative management, recurrent patellar instability occurs in between 15 and 45% of patients [17,18,19,20]. Acute Osteochondral Fractures in the Lower Extremities - Approach to Identification and Treatment. Treatment of ruptured intracranial aneurysms yesterday and now 3. What is the treatment for a patellar retinaculum tear? Laxity of the medial stabilizers will lead to increasing instability over time. Kim et al. High resolution magnetic resonance imaging of the patellar retinaculum: normal anatomy, common injury patterns . (28a) A sagittal proton density-weighted image demonstrates the typical hardware location in a patient status post medialization of the tibial tuberosity (arrow). Stretching a Lateral Retinaculum of the Knee | livestrong 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. It is a ratio between the patellar tendon length (along the inner surface of the tendon) and the diagonal patellar height [27]. 0000070933 00000 n 0000192215 00000 n 0000212094 00000 n provided a morphologic classification system for trochlear dysplasia describing four types [26,27,28]. The patients are then J-braced for 3 to 6 months for all sports activities. 6. Perpendicular to this baseline, trochlear depth is calculated by measuring the mean of the maximum AP distance of the medial (a) and lateral (b) femoral condyles minus the distance between the deepest point of the trochlear groove and the line paralleling the posterior condylar surfaces (c). The medial patellofemoral ligament (MPFL) is a condensation of the medial capsule of the knee joint. Provided by the Springer Nature SharedIt content-sharing initiative. The primary aim of surgery is to repair the knee damage and to correct the anomalies that are predisposing to chronic instability. 7,14 While plain radiography is an important tool to diagnose APD, magnetic resonance imaging (MRI . The images should be scrutinized for the presence of chondral or osteochondral injury, especially if displaced as an intra-articular body, as this may affect surgical management. MRI Web Clinic, August 2010. https://radsource.us/patella-alta-and-baja/. Additionally, MRs ability to delineate the extent of injury and predisposing factors is important in patient care and surgical planning. The knee is a complex joint with separate tibio-femoral and the patellofemoral articulations. Edema and thickening compatible with tears of the MPFL and medial retinaculum (red arrows) are apparent both anteriorly and posteriorly. 1). In fact, most patellar maltracking occurs between extension and the first 30 of flexion. 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. 5 a-d). PMID: 9168713. It is the percentage of the medial (a) to the lateral (b) trochlear facet length (a/b100%). 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]. Seventeen patients with patellar retinacular ligament injuries were evaluated with magnetic resonance (MR) imaging. Trochlear depth of less than 3 mm on MRI has a sensitivity of 100% and a specificity of 96% for trochlear dysplasia.10. Various parameters can be used in assessing and predicting the presence of patellar maltracking. 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. 5 Carrillon Y, Abidi H, Dejour D, et al. 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. A lateral patellar sleeve fracture can be misdiagnosed [Crossref] Harvinder Bedi, John Marzo. Axial PDFS left knee MR image, demonstrating the method used for the measurement of trochlear depth. 2012 Feb;41(2):137-48. doi: 10.1007/s00256-011-1291-3. 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. AJR Am J Roentgenol 187:13321337, White BJ, Sherman OH (2009) Patellofemoral instability. The vastus medialis oblique (VMO) provides active stability of the patella. (Figs.1-A 1-A also and1-B). Open Orthop J 9:463474, Article Bethesda, MD 20894, Web Policies 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. Osteochondral fractures are common in acute or recurrent transient lateral patellar dislocation, seen in up to 70% of cases. 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]. Therefore, the management of patellar maltracking remains controversial and decisions need to be made on an individual patient basis with surgical management being reserved for those patients with documented recurrent lateral patellar instability. 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 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 authors declare that they have no competing interests. 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]. 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. 8600 Rockville Pike This is an arthroscopic surgery ( a knee "scope" which is performed through 3 small incisions ( about inch each) around the knee. It is the angle between a line tangential to the subchondral bone of the posterior aspect of the femoral condyles and a line along the lateral trochlear facet subchondral bone (Fig. Facet asymmetry is determined by calculating the percentage of the medial to the lateral femoral facet length (Fig. 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. Accessibility Additionally, return to sport can be as low as 45%, leaving many patients searching for further management options [12]. As the knee joint ranges from extension to flexion, the articular surface area of the patella is in contact with the femur changes. Sports Health 3:170174, Stensdotter AK, Hodges PW, Mellor R, Sundelin G, Hger-Ross C (2003) Quadriceps activation in closed and in open kinetic chain exercise. The Anterolateral Ligament of the Knee: MRI Appearance, Association Epub 2023 Feb 7. 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. Lateral trochlear inclination is another quantitative method to diagnose trochlear dysplasia. MRI and CT are superior modalities in looking for predisposing factors associated with patellar maltracking [26,27,28]. In general realignment surgery such as tibial tubercle transfer should be strongly considered in patients with TT-TG > 15mm (borderline) and typically should be performed in patients with TT-TG > 20mm. 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. Significantly greater lateral patellar displacement and tilt was found in osteoarthritis patients compared to a control group [3]. Am J Sports Med 16:244249, Hawkins RJ, Bell RH, Anisette G (1986) Acute patellar dislocations. Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in sports activities. 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]. On the other hand, frank patellar dislocation is a significant risk factor in the development of patellofemoral osteoarthritis with an incidence of 49% at 25years after the patellar dislocation incident in comparison with 8% in a control group without a dislocation history [60]. Terms and Conditions, The anatomy of the medial patellofemoral ligament. 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. What is the diagnosis? Intervention: Taping the knee to promote medial glide . The injured retinaculum had an indistinct, irregular appearance associated with edema and hemorrhage. 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. The rectus femoris (RF), vastus lateralis (VL), and lateral retinaculum (LR) are also indicated. Lateral patellar dislocation. The oblique decussation of the MPFL blends with fibers of the superficial MCL. These morphological risk factors can be assessed using methods similar to those on MRI as detailed in the prior sections of this article. On the other hand, the PTI is significantly altered with knee flexion [37]. Before Twenty-six pelvic limbs were used for gross dissection, and four stifle regions from two animals were used for radiography and magnetic resonance imaging (MRI). The most accepted indication for surgical management of patellar instability is the presence of a large displaced osteochondral fracture or loose body. 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. Acute traumatic instability most commonly occurs in young athletes in their second and third decade at an incidence rate of 29 per 100,000. By using this website, you agree to our Methods: We compared 361 treated cases of aneurysm occlusion after subarachnoid hemorrhage from 1997 to 2003 with 281 cases from 2006 to 2014. A second line is drawn parallel to a line along the posterior femoral condyles. Injury. The MPFL is best seen on axial MRI on the slice just distal to the VMO. 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 VMO is active, not only in full extension but also at 30 degrees and up to 100 degrees of flexion. Distally, it attaches to the tibial tubercle via the patellar tendon. However, the use of this method is not widespread. Epub 2010 Mar 8. Osteochondral injuries to the inferomedial patella may be the result of impaction during dislocation or shearing with reduction. 2023 Apr;47(4):973-981. doi: 10.1007/s00264-023-05707-y. Oper Tech Sports Med 6:247258, Dejour H, Walch G, Nove-Josserand L, Guier C (1994) Factors of patellar instability: an anatomic radiographic study. and transmitted securely. It can be difficult to determine the deepest part of the trochlear groove when assessing the TT-TTG in the presence of trochlear dysplasia; therefore, an alternative method for assessing tibial tubercle position was proposed measuring the distance in reference to the posterior cruciate ligament and not to the trochlea (tibial tubercle-posterior cruciate ligament distance [TT-PCL]), with proposed pathologic threshold of 21mm [42, 43].

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