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Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients
THEKNE-01926; No of Pages 6 The Knee xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
The Knee
Case report
Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients Bertrand Sonnery-Cottet, Rafael Mortati, Pooler Archbold, François Gadea, Julien Clechet, Mathieu Thaunat ⁎ Hôpital Privé Jean Mermoz, Centre Orthopédique Santy, 24 Avenue Paul Santy, 69008 Lyon, France
a r t i c l e
i n f o
Article history: Received 29 January 2014 Received in revised form 2 May 2014 Accepted 5 July 2014 Available online xxxx Keywords: Meniscus root repair Arthroscopy Knee Open physis
a b s t r a c t Background: Meniscal root avulsion has been predominantly reported in an adult population but little is known about this meniscal lesion in children and adolescents. Purpose: The of this article is to describe the clinical symptoms and a new MRI sign of a medial meniscus posterior root avulsion in skeletally immature patients, and to report the arthroscopic procedure for its reinsertion in the presence of open physes. Case description: We report two skeletally immature patients who had a medial meniscus posterior root avulsion [MMPRA]. Diagnosis of a MMPRA was suspected on MRI by intense T2 hypersignal located at the postero-medial part of the tibial plateau reflecting trabecular bone oedema (“Bone bruise”) at the level of the medial meniscal posterior root attachment. Arthroscopic reduction and fixation of the posterior root of the medial meniscus with transosseous sutures was performed. The patients returned to sport at the end of 6 months without residual symptoms. At one year, the radiographs showed no modification of the physis. Healing of the medial meniscal posterior root was noted on MRI. Clinical relevance: In a skeletally immature patient it is important that this rare meniscal lesion is diagnosed early and adequately treated. We emphasize the importance of the indirect MRI signs that can lead a clinician to suspect the diagnosis of MMPRA. The aim of the surgery was to restore the anatomical footprint of the meniscal root and to re-establish its function thus preventing future chondral damage without damage to the tibial physeal growth plate. Level of evidence: Level IV © 2014 Elsevier B.V. All rights reserved.
1. Introduction The meniscus plays an important role in the biomechanics of the knee, including load distribution, impact absorption, and stabilization [1]. The meniscal root is a key to the normal biomechanical function of the meniscus; it behaves as a strong insertional ligament maintaining hoop tension and allowing axial load dispersion. When a lesion occurs in this ligamentary complex, its biomechanical function is compromised [2,3] and medial meniscal extrusion is observed [4]. Consequently, medial meniscal posterior root tears and radial/flap tears are associated with more severe cartilaginous lesions than other medial meniscal tears [5]. Medial meniscal root pathology is strongly associated with degenerative joint disease (DJD) [6]. Several techniques for posterior meniscal root repair have been published [7–11]. There aim is to restore hoop tension in order to potentially avoid the rapid progression of DJD. Yet, there is little published concerning the clinical and MRI presentation of this rare meniscal lesion in children and adolescents, and in particular the surgical technique of medial meniscus posterior root avulsion (MMPRA) reinsertion in ⁎ Corresponding author. Tel.: +33 437 530 024; fax: +33 437 530 025. E-mail addresses: [email protected], [email protected] (M. Thaunat).
patients with open physes. We report the case of two skeletally immature patients with a MMPRA. The purpose of this article is to describe the clinical symptoms and the importance of subtle MRI findings that can help to make an early diagnosis and treat this lesion. In addition we report the arthroscopic procedure for the reinsertion of the medial meniscus posterior root avulsion in a skeletally immature patient.
1.1. Case report Two young adolescents were successively treated in our department for a similar medial meniscal tear root avulsion in 2011. A 14-year-old male (patient 1) and a 12-year old male (patient 2) suffered a torsional injury to their right knee. The first patient fell and hurt his knee while rollerskating and the second patient felt pain after a torsional injury while playing football. The reason for consultation was in both cases pain and persistent effusion several weeks after the injury. They had no history of a previous knee injury. Following their injury, they both continued to complain of pain in their knee which affected their daily activities of living. Examination revealed in both cases a small joint effusion, normal range of motion (complete extension, 140° of knee flexion) and pain on the medial joint line. There was no increased laxity
http://dx.doi.org/10.1016/j.knee.2014.07.001 0968-0160/© 2014 Elsevier B.V. All rights reserved.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
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B. Sonnery-Cottet et al. / The Knee xxx (2014) xxx–xxx
Fig. 1. Preoperative MR imaging of patient 1,: T2 weighted images with fat suppression. (A) Coronal view. Bone bruise oedema (open arrow) and truncated aspect of the posterior horn of the medial meniscus filled with fluid T2 hypersignal intensity. Note retraction of the avulsed root of the medial meniscus (solid arrow). (B) Coronal slice at the level of the MCL demonstrating minor meniscus extrusion (solid arow) indicative of the root avulsion. (C) Axial view. T2 hypersignal intensity and complete defect of the medial meniscal posterior root attachment (solid arrow). (D) Sagittal view, postero-medial tibial bone bruise oedema (open arrow) and a complete defect of the posterior meniscal root filled with fluid T2.
to varus and valgus stress on the knee at 0° and 30° of flexion and a firm endpoint to the Lachman test in both cases. By applying a varus stress to the knee in full extension, an extrusion of the middle and anterior segments of the medial meniscus could be palpated at the anteromedial joint line. An excessive anteroposterior drawer was noticed at the level of the medial plateau when the knee was bent at 90° of flexion. An MRI was performed with our standard protocol (axial sagittal and coronal T2 weighted fast spin echo with fat saturation images) with a 1.5 Tesla magnet (Avento, Siemens HealthCare, Erlangen, Germany) (Fig. 1). The radiologist noted in our first case a trabecular
bone oedema (“Bone bruise”) located at the postero-medial part of the tibial plateau. A thorough analysis of MR imaging revealed: - On coronal view, a truncated aspect of the meniscus filled with fluid-like T2 WI hypersignal in the area of the medial meniscal posterior root and a slight medial meniscal extrusion on the coronal slice passing through the MCL (Fig. 1A, B). - On sagittal view, a complete loss of the normal triangular shape of posterior medial meniscus, replaced by fluid like T2 WI hypersignal, giving a “ghost meniscus sign” (Fig. 1 D).
Fig. 2. Preoperative MR imaging of patient 2: T2 weighted images with fat suppression. (A) Coronal view shows bone bruise oedema (open arrow) and minor meniscus extrusion indicative of the root avulsion. (B) Sagittal view, postero-medial tibial bone bruise oedema (solid arrow). (C) Axial view. Defect of the medial meniscal posterior root attachment (arrow head).
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
B. Sonnery-Cottet et al. / The Knee xxx (2014) xxx–xxx
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Fig. 3. Pre-operative arthro CT scan of patient 1, coronal, axial and sagittal demonstrating a medial meniscal posterior root avulsion: complete disruption of the medial meniscus root attachment filled with intra-articular injected contrast (white arrows on each images).
- On axial view, intense T2 WI hypersignal at the level of the medial meniscal posterior root attachment (Fig. 1 C). These MRI findings indicated a medial meniscal posterior root tear [12,13]. Interestingly, a second case was diagnosed few months later in a 12 year-old adolescent (patient 2) and the same meniscal tear patterns were noted on MRI (Fig. 2). This lesion is rare particularly in a skeletally immature patient; therefore, an arthro-CT scan was performed for both patients to confirm our suspicion of an avulsion of the posterior root of medial meniscus (Fig. 3). CT arthrography was performed with intraarticular injection of 12 mL of nondiluted iodinated contrast material (Hexabrix; Guerbet, Roissy, France). Spiral CT was performed with 1- and 2-mm-thick sections (Somatom Plus; Siemens, Erlangen, Germany). Arthro-CT confirmed the posterior root avulsion, demonstrating a diffusion of the injected intra-articular contrast between the tibial bone and the torn medial meniscus root. After confirmation of the diagnosis it was decided for both cases to proceed with an arthroscopic reduction of the posterior root of medial meniscus and its fixation with transosseous sutures as shown in the video (online resource 1). Reinsertion of the meniscus
by limiting the size of the tibial tunnels was essential as the tibial physis was still open. During the arthroscopy we initially prepared the tibial footprint of the meniscal root with an arthroscopic rasp. Then, using a rotator cuff suture hook, we passed 2 non-absorbable sutures (ORTHOCORD TM suture, Depuy Mitek Inc., Norwood, MA) into the root of the medial meniscus (Fig. 4). With the help of an ACL reconstruction tibial guide we drilled two convergent kirschner wires of 2.5 mm diameter into the tibial footprint (Fig. 3). After removal of these two pins, a special eyelet pin (meniscal needle, Mitek), was passed through these small tunnels to retrieve each of the two non-absorbable sutures onto the anterior aspect of the tibia. Finally, after checking the intra-articular reduction of the medial meniscal root, each strand of the two ORTHOCORD TM sutures was knotted on the anterior cortex of the tibia. The knee was immobilized in an extension brace non-weightbearing weight bearing for 6 weeks. One week after surgery, passive and active extension exercises were permitted as tolerated by the patient. The flexion was limited to 90° during 6 weeks. After 6 weeks, gradual weight bearing and flexion over 90° was encouraged. A clinical follow-up was performed at 6 weeks, 3 months, 6 months and one year for both patients. At the 6 month follow-up, no effusion, and no tenderness
Fig. 4. Arthroscopic views of patient 1: A. Avulsed medial meniscus root; B. Foot print of the posterior horn of medial meniscus; C. Nonabsorbable sutures passing through the root by rotator cuff hooks; D. Tibial guide for drilling; E. Wires passed parallel to each other in the foot print of tibia; F. Sutured root back to its normal position.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
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Fig. 5. Postoperative MR imaging of patient 1, fat saturated T2 weighted sequences. A) coronal, B) axial and C) sagittal postoperative MRI demonstrating healing of the medial meniscus posterior root: meniscus continuity and insertion present a normal T2 hyposignal intensity (solid arrow). Disruption, previously noticed with fluid like T2 hypersignal filling, is no more longer visible.
over the medial joint line was observed. Clinical examination showed full range of motion, and no meniscal extrusion was noted at palpation during the varus stress test [13]. Six-month postoperative coronal fat suppressed T2 weighted MR image demonstrates the reattached tibial avulsion fracture of the posterior root of the MM. The MM has remained in its normal anatomic position with normalization of the adjacent intrameniscal signal intensity (Fig. 5). Both patients returned to their previous sport activity (soccer for patient 1 and roller skating for patient 2) at the same level at the end of 6 months without residual symptoms. At the one year follow-up, the radiograph showed no modification of the physis in both cases (Fig. 6).
2. Discussion The incidence of medial meniscal root avulsion ranges from 10.1% to 27.8% [14,15]. A possible injury mechanism could be a rotational distortion of the knee. Previously it has been predominantly reported in an adult population. However, the increased practice of sports and the improvement of diagnostic methods have led to a better notification of these lesions [16]. Increased age, female sex predominance, higher Body Mass Index, increased Kellgren Lawrence Grade, greater varus mechanical axis angle, and lower sports activity level have been identified as risk factors for MMPR tear [17]. To our knowledge, only 2 cases have been published to date in skeletally immature patients [18,19].
A MMPRA is suspected to lead to DJD [5,6]. In a recent study investigating the association of isolated medial meniscal tears with articular cartilage degeneration, it was reported that these root tears were associated with more severe articular cartilage damage than the other types of meniscal lesion (longitudinal and vertical tears) [5]. From a biomecanichal point of view, MMPRA leads to a 25% increase in peak contact pressure compared to an intact meniscus; MMPRA have been considered equivalent to total menisectomy [2,3]. Partial menisectomy is one of the treatment options for adult patients. Symptomatic relief has been reported, but does not prevent progression of osteoarthritis [14,15,20]. Therefore, arthroscopic meniscal root repair should be considered as an important treatment option [15,16,21] particularly in children and adolescents. However MMPRA is difficult to diagnose. The clinical symptoms are limited and non-specific. Only one clinical sign of meniscal root avulsion has been described in the literature [22]. By applying a varus stress to the knee in full extension, an extrusion of the middle and anterior segments of the medial meniscus can be palpated at the anteromedial joint line. Moreover, correct diagnosis can be easily missed on MRI as most of radiologists are not familiar with this type of meniscal lesion. In this case, fat saturated MRI sequences allowed us to easily visualize the bone bruise in the posterior medial tibial plateau. This oedema caught our attention and made us strongly investigate the possibility of a meniscal lesion on MRI in this area. Further studies are required to investigate the predictive value of a bone bruise located in the
Fig. 6. One year follow-up of patient 1, no modification of the physis observable on radiograph.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
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Fig. 7. MR imaging of a nondisplaced subchondral fracture of the postero-medial tibial plateau (T2 weighted images with fat suppression) mimicking a posterior medial meniscus root avulsion.
posterior area of the medial tibial plateau as an indirect sign of a potential MMPRA. In this situation we advocate that an Arthro-CT should be used to confirm the diagnosis, as a non-displaced subchondral fracture could mimic this particular aspect on MRI (Fig. 7). Reports on the clinical outcome of meniscal root tear repair are limited and largely involve skeletally mature patients. Nevertheless, the factors that influence the outcome of meniscal root repair in adults have been studied. A higher BMI, a greater varus mechanical axis angle, a higher outerbridge grade cartilage status and a larger preoperative meniscal extrusion negatively impact postoperative outcomes [23]. Our patient has none of these risk factors. In our opinion, all posterior horn avulsions in children or adolescent should be repaired. As advocated by Seil et al. [22], avulsion of the posterior root of the medial meniscus results in a ‘phantom meniscus’ meaning that the majority of the meniscal tissue is still present, but that it is biomechanically inefficient. Such a lesion may lead subsequently to the development of cartilage lesions over a 6-month period. In this age group the surgical technique must take into consideration the presence of an open physis in order to avoid potential iatrogenic growth disturbances. In this case report, the transosseous suture technique with two 2.5 mm tibial tunnels allows the surgeon to minimize physeal damage. They are positioned in the central area of the tibial physis to reduce the risk of growth disturbance [24]. Although we obtained a satisfactory clinical result and recommend this surgical procedure in similar cases of MMPRA we do acknowledge a number of limitations in this report. Our followup is short and late failure is still possible. Further studies with a larger sample are needed to accurately define the prevalence of this lesion, its healing rate and to define the subtle clinical and radiological signs that could aid in an early diagnosis in a skeletally immature population. 3. Conclusion This study reports an unusual case of a skeletally immature patient who presented with a root avulsion of the posterior medial meniscus. This type of injury leads to instability and displacement of the posterior portion of the meniscus, altering meniscal function. This can potentially lead to joint degeneration and osteoarthritis with disastrous consequences for a young patient. We emphasize the importance of the indirect MRI signs that can lead a clinician to suspect the diagnosis of MMPRA and describe the surgical technique for repair of the meniscal root in this population of patients. Our case confirms that a satisfactory outcome can be expected after an arthroscopic reduction of MMPRA
however a longer followup and more patients are needed to confirm this impression. Conflict of interest Bertrand Sonnery Cottet and Mathieu Thaunat are consultants for Arthrex. References [1] Fukubayashi T, Kurosawa H. The contact area and pressure distribution pattern of the knee. A study of normal and osteoarthrotic knee joints. Acta Orthop Scand 1980;51:871–9. [2] Allaire R, Muriuki M, Gilbertson L, Harner CD. Biomechanical consequences of a tear of the posterior root of the medial meniscus. Similar to total meniscectomy. J Bone Joint Surg Am 2008;90:1922–31. [3] Marzo JM, Kumar BA. Primary repair of medial meniscal avulsions: 2 case studies. Am J Sports Med 2007;35:1380–3. [4] Pagnani MJ, Cooper DE, Warren RF. Extrusion of the medial meniscus. Arthroscopy 1991;7:297–300. [5] Henry S, Mascarenhas R, Kowalchuk D, Forsythe B, Irrgang JJ, Harner CD. Medial meniscus tear morphology and chondral degeneration of the knee: is there a relationship? Arthroscopy 2012;28:1124–1134.e2. [6] Lerer DB, Umans HR, Hu MX, Jones MH. The role of meniscal root pathology and radial meniscal tear in medial meniscal extrusion. Skeletal Radiol 2004;33:569–74. [7] Ahn JH, Wang JH, Lim HC, Bae JH, Park JS, Yoo JC, et al. Double transosseous pull out suture technique for transection of posterior horn of medial meniscus. Arch Orthop Trauma Surg 2009;129:387–92. [8] Choi N-H, Son K-M, Victoroff BN. Arthroscopic all-inside repair for a tear of posterior root of the medial meniscus: a technical note. Knee Surg Sports Traumatol Arthrosc 2008;16:891–3. [9] Jung Y-H, Choi N-H, Oh J-S, Victoroff BN. All-inside repair for a root tear of the medial meniscus using a suture anchor. Am J Sports Med 2012;40:1406–11. [10] Kim J-H, Shin D-E, Dan J-M, Nam K-S, Ahn T-K, Lee D-H. Arthroscopic suture anchor repair of posterior root attachment injury in medial meniscus: technical note. Arch Orthop Trauma Surg 2009;129:1085–8. [11] Kopf S, Colvin AC, Muriuki M, Zhang X, Harner CD. Meniscal root suturing techniques: implications for root fixation. Am J Sports Med 2011;39:2141–6. [12] Choi S-H, Bae S, Ji SK, Chang MJ. The MRI findings of meniscal root tear of the medial meniscus: emphasis on coronal, sagittal and axial images. Knee Surg Sports Traumatol Arthrosc 2012;20:2098–103. [13] Koenig JH, Ranawat AS, Umans HR, Difelice GS. Meniscal root tears: diagnosis and treatment. Arthroscopy 2009;25:1025–32. [14] Bin S-I, Kim J-M, Shin S-J. Radial tears of the posterior horn of the medial meniscus. Arthroscopy 2004;20:373–8. [15] Ozkoc G, Circi E, Gonc U, Irgit K, Pourbagher A, Tandogan RN. Radial tears in the root of the posterior horn of the medial meniscus. Knee Surg Sports Traumatol Arthrosc 2008;16:849–54. [16] Kozlowski EJ, Barcia AM, Tokish JM. Meniscus repair: the role of accelerated rehabilitation in return to sport. Sports Med Arthrosc 2012;20:121–6. [17] Hwang B-Y, Kim S-J, Lee S-W, Lee H-E, Lee C-K, Hunter DJ, et al. Risk factors for medial meniscus posterior root tear. Am J Sports Med 2012;40:1606–10. [18] Griffith CJ, LaPrade RF, Fritts HM, Morgan PM. Posterior root avulsion fracture of the medial meniscus in an adolescent female patient with surgical reattachment. Am J Sports Med 2008;36:789–92.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
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[19] Matava MJ, Kim Y-M. Tibial avulsion fracture of the posterior root of the medial meniscus in a skeletally-immature child — a case report. Knee 2011;18:62–5. [20] Han SB, Shetty GM, Lee DH, Chae DJ, Seo SS, Wang KH, et al. Unfavorable results of partial meniscectomy for complete posterior medial meniscus root tear with early osteoarthritis: a 5- to 8-year follow-up study. Arthroscopy 2010;26:1326–32. [21] Kim SB, Ha JK, Lee SW, Kim DW, Shim JC, Kim JG, et al. Medial meniscus root tear refixation: comparison of clinical, radiologic, and arthroscopic findings with medial meniscectomy. Arthroscopy 2011;27:346–54.
[22] Seil R, Dück K, Pape D. A clinical sign to detect root avulsions of the posterior horn of the medial meniscus. Knee Surg Sports Traumatol Arthrosc 2011;19:2072–5. [23] Moon H-K, Koh Y-G, Kim Y-C, Park Y-S, Jo S-B, Kwon S-K. Prognostic factors of arthroscopic pull-out repair for a posterior root tear of the medial meniscus. Am J Sports Med 2012;40:1138–43. [24] Seil R, Pape D, Kohn D. The risk of growth changes during transphyseal drilling in sheep with open physes. Arthroscopy 2008;24:824–33.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
Contents lists available at ScienceDirect
The Knee
Case report
Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients Bertrand Sonnery-Cottet, Rafael Mortati, Pooler Archbold, François Gadea, Julien Clechet, Mathieu Thaunat ⁎ Hôpital Privé Jean Mermoz, Centre Orthopédique Santy, 24 Avenue Paul Santy, 69008 Lyon, France
a r t i c l e
i n f o
Article history: Received 29 January 2014 Received in revised form 2 May 2014 Accepted 5 July 2014 Available online xxxx Keywords: Meniscus root repair Arthroscopy Knee Open physis
a b s t r a c t Background: Meniscal root avulsion has been predominantly reported in an adult population but little is known about this meniscal lesion in children and adolescents. Purpose: The of this article is to describe the clinical symptoms and a new MRI sign of a medial meniscus posterior root avulsion in skeletally immature patients, and to report the arthroscopic procedure for its reinsertion in the presence of open physes. Case description: We report two skeletally immature patients who had a medial meniscus posterior root avulsion [MMPRA]. Diagnosis of a MMPRA was suspected on MRI by intense T2 hypersignal located at the postero-medial part of the tibial plateau reflecting trabecular bone oedema (“Bone bruise”) at the level of the medial meniscal posterior root attachment. Arthroscopic reduction and fixation of the posterior root of the medial meniscus with transosseous sutures was performed. The patients returned to sport at the end of 6 months without residual symptoms. At one year, the radiographs showed no modification of the physis. Healing of the medial meniscal posterior root was noted on MRI. Clinical relevance: In a skeletally immature patient it is important that this rare meniscal lesion is diagnosed early and adequately treated. We emphasize the importance of the indirect MRI signs that can lead a clinician to suspect the diagnosis of MMPRA. The aim of the surgery was to restore the anatomical footprint of the meniscal root and to re-establish its function thus preventing future chondral damage without damage to the tibial physeal growth plate. Level of evidence: Level IV © 2014 Elsevier B.V. All rights reserved.
1. Introduction The meniscus plays an important role in the biomechanics of the knee, including load distribution, impact absorption, and stabilization [1]. The meniscal root is a key to the normal biomechanical function of the meniscus; it behaves as a strong insertional ligament maintaining hoop tension and allowing axial load dispersion. When a lesion occurs in this ligamentary complex, its biomechanical function is compromised [2,3] and medial meniscal extrusion is observed [4]. Consequently, medial meniscal posterior root tears and radial/flap tears are associated with more severe cartilaginous lesions than other medial meniscal tears [5]. Medial meniscal root pathology is strongly associated with degenerative joint disease (DJD) [6]. Several techniques for posterior meniscal root repair have been published [7–11]. There aim is to restore hoop tension in order to potentially avoid the rapid progression of DJD. Yet, there is little published concerning the clinical and MRI presentation of this rare meniscal lesion in children and adolescents, and in particular the surgical technique of medial meniscus posterior root avulsion (MMPRA) reinsertion in ⁎ Corresponding author. Tel.: +33 437 530 024; fax: +33 437 530 025. E-mail addresses: [email protected], [email protected] (M. Thaunat).
patients with open physes. We report the case of two skeletally immature patients with a MMPRA. The purpose of this article is to describe the clinical symptoms and the importance of subtle MRI findings that can help to make an early diagnosis and treat this lesion. In addition we report the arthroscopic procedure for the reinsertion of the medial meniscus posterior root avulsion in a skeletally immature patient.
1.1. Case report Two young adolescents were successively treated in our department for a similar medial meniscal tear root avulsion in 2011. A 14-year-old male (patient 1) and a 12-year old male (patient 2) suffered a torsional injury to their right knee. The first patient fell and hurt his knee while rollerskating and the second patient felt pain after a torsional injury while playing football. The reason for consultation was in both cases pain and persistent effusion several weeks after the injury. They had no history of a previous knee injury. Following their injury, they both continued to complain of pain in their knee which affected their daily activities of living. Examination revealed in both cases a small joint effusion, normal range of motion (complete extension, 140° of knee flexion) and pain on the medial joint line. There was no increased laxity
http://dx.doi.org/10.1016/j.knee.2014.07.001 0968-0160/© 2014 Elsevier B.V. All rights reserved.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
2
B. Sonnery-Cottet et al. / The Knee xxx (2014) xxx–xxx
Fig. 1. Preoperative MR imaging of patient 1,: T2 weighted images with fat suppression. (A) Coronal view. Bone bruise oedema (open arrow) and truncated aspect of the posterior horn of the medial meniscus filled with fluid T2 hypersignal intensity. Note retraction of the avulsed root of the medial meniscus (solid arrow). (B) Coronal slice at the level of the MCL demonstrating minor meniscus extrusion (solid arow) indicative of the root avulsion. (C) Axial view. T2 hypersignal intensity and complete defect of the medial meniscal posterior root attachment (solid arrow). (D) Sagittal view, postero-medial tibial bone bruise oedema (open arrow) and a complete defect of the posterior meniscal root filled with fluid T2.
to varus and valgus stress on the knee at 0° and 30° of flexion and a firm endpoint to the Lachman test in both cases. By applying a varus stress to the knee in full extension, an extrusion of the middle and anterior segments of the medial meniscus could be palpated at the anteromedial joint line. An excessive anteroposterior drawer was noticed at the level of the medial plateau when the knee was bent at 90° of flexion. An MRI was performed with our standard protocol (axial sagittal and coronal T2 weighted fast spin echo with fat saturation images) with a 1.5 Tesla magnet (Avento, Siemens HealthCare, Erlangen, Germany) (Fig. 1). The radiologist noted in our first case a trabecular
bone oedema (“Bone bruise”) located at the postero-medial part of the tibial plateau. A thorough analysis of MR imaging revealed: - On coronal view, a truncated aspect of the meniscus filled with fluid-like T2 WI hypersignal in the area of the medial meniscal posterior root and a slight medial meniscal extrusion on the coronal slice passing through the MCL (Fig. 1A, B). - On sagittal view, a complete loss of the normal triangular shape of posterior medial meniscus, replaced by fluid like T2 WI hypersignal, giving a “ghost meniscus sign” (Fig. 1 D).
Fig. 2. Preoperative MR imaging of patient 2: T2 weighted images with fat suppression. (A) Coronal view shows bone bruise oedema (open arrow) and minor meniscus extrusion indicative of the root avulsion. (B) Sagittal view, postero-medial tibial bone bruise oedema (solid arrow). (C) Axial view. Defect of the medial meniscal posterior root attachment (arrow head).
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
B. Sonnery-Cottet et al. / The Knee xxx (2014) xxx–xxx
3
Fig. 3. Pre-operative arthro CT scan of patient 1, coronal, axial and sagittal demonstrating a medial meniscal posterior root avulsion: complete disruption of the medial meniscus root attachment filled with intra-articular injected contrast (white arrows on each images).
- On axial view, intense T2 WI hypersignal at the level of the medial meniscal posterior root attachment (Fig. 1 C). These MRI findings indicated a medial meniscal posterior root tear [12,13]. Interestingly, a second case was diagnosed few months later in a 12 year-old adolescent (patient 2) and the same meniscal tear patterns were noted on MRI (Fig. 2). This lesion is rare particularly in a skeletally immature patient; therefore, an arthro-CT scan was performed for both patients to confirm our suspicion of an avulsion of the posterior root of medial meniscus (Fig. 3). CT arthrography was performed with intraarticular injection of 12 mL of nondiluted iodinated contrast material (Hexabrix; Guerbet, Roissy, France). Spiral CT was performed with 1- and 2-mm-thick sections (Somatom Plus; Siemens, Erlangen, Germany). Arthro-CT confirmed the posterior root avulsion, demonstrating a diffusion of the injected intra-articular contrast between the tibial bone and the torn medial meniscus root. After confirmation of the diagnosis it was decided for both cases to proceed with an arthroscopic reduction of the posterior root of medial meniscus and its fixation with transosseous sutures as shown in the video (online resource 1). Reinsertion of the meniscus
by limiting the size of the tibial tunnels was essential as the tibial physis was still open. During the arthroscopy we initially prepared the tibial footprint of the meniscal root with an arthroscopic rasp. Then, using a rotator cuff suture hook, we passed 2 non-absorbable sutures (ORTHOCORD TM suture, Depuy Mitek Inc., Norwood, MA) into the root of the medial meniscus (Fig. 4). With the help of an ACL reconstruction tibial guide we drilled two convergent kirschner wires of 2.5 mm diameter into the tibial footprint (Fig. 3). After removal of these two pins, a special eyelet pin (meniscal needle, Mitek), was passed through these small tunnels to retrieve each of the two non-absorbable sutures onto the anterior aspect of the tibia. Finally, after checking the intra-articular reduction of the medial meniscal root, each strand of the two ORTHOCORD TM sutures was knotted on the anterior cortex of the tibia. The knee was immobilized in an extension brace non-weightbearing weight bearing for 6 weeks. One week after surgery, passive and active extension exercises were permitted as tolerated by the patient. The flexion was limited to 90° during 6 weeks. After 6 weeks, gradual weight bearing and flexion over 90° was encouraged. A clinical follow-up was performed at 6 weeks, 3 months, 6 months and one year for both patients. At the 6 month follow-up, no effusion, and no tenderness
Fig. 4. Arthroscopic views of patient 1: A. Avulsed medial meniscus root; B. Foot print of the posterior horn of medial meniscus; C. Nonabsorbable sutures passing through the root by rotator cuff hooks; D. Tibial guide for drilling; E. Wires passed parallel to each other in the foot print of tibia; F. Sutured root back to its normal position.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
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Fig. 5. Postoperative MR imaging of patient 1, fat saturated T2 weighted sequences. A) coronal, B) axial and C) sagittal postoperative MRI demonstrating healing of the medial meniscus posterior root: meniscus continuity and insertion present a normal T2 hyposignal intensity (solid arrow). Disruption, previously noticed with fluid like T2 hypersignal filling, is no more longer visible.
over the medial joint line was observed. Clinical examination showed full range of motion, and no meniscal extrusion was noted at palpation during the varus stress test [13]. Six-month postoperative coronal fat suppressed T2 weighted MR image demonstrates the reattached tibial avulsion fracture of the posterior root of the MM. The MM has remained in its normal anatomic position with normalization of the adjacent intrameniscal signal intensity (Fig. 5). Both patients returned to their previous sport activity (soccer for patient 1 and roller skating for patient 2) at the same level at the end of 6 months without residual symptoms. At the one year follow-up, the radiograph showed no modification of the physis in both cases (Fig. 6).
2. Discussion The incidence of medial meniscal root avulsion ranges from 10.1% to 27.8% [14,15]. A possible injury mechanism could be a rotational distortion of the knee. Previously it has been predominantly reported in an adult population. However, the increased practice of sports and the improvement of diagnostic methods have led to a better notification of these lesions [16]. Increased age, female sex predominance, higher Body Mass Index, increased Kellgren Lawrence Grade, greater varus mechanical axis angle, and lower sports activity level have been identified as risk factors for MMPR tear [17]. To our knowledge, only 2 cases have been published to date in skeletally immature patients [18,19].
A MMPRA is suspected to lead to DJD [5,6]. In a recent study investigating the association of isolated medial meniscal tears with articular cartilage degeneration, it was reported that these root tears were associated with more severe articular cartilage damage than the other types of meniscal lesion (longitudinal and vertical tears) [5]. From a biomecanichal point of view, MMPRA leads to a 25% increase in peak contact pressure compared to an intact meniscus; MMPRA have been considered equivalent to total menisectomy [2,3]. Partial menisectomy is one of the treatment options for adult patients. Symptomatic relief has been reported, but does not prevent progression of osteoarthritis [14,15,20]. Therefore, arthroscopic meniscal root repair should be considered as an important treatment option [15,16,21] particularly in children and adolescents. However MMPRA is difficult to diagnose. The clinical symptoms are limited and non-specific. Only one clinical sign of meniscal root avulsion has been described in the literature [22]. By applying a varus stress to the knee in full extension, an extrusion of the middle and anterior segments of the medial meniscus can be palpated at the anteromedial joint line. Moreover, correct diagnosis can be easily missed on MRI as most of radiologists are not familiar with this type of meniscal lesion. In this case, fat saturated MRI sequences allowed us to easily visualize the bone bruise in the posterior medial tibial plateau. This oedema caught our attention and made us strongly investigate the possibility of a meniscal lesion on MRI in this area. Further studies are required to investigate the predictive value of a bone bruise located in the
Fig. 6. One year follow-up of patient 1, no modification of the physis observable on radiograph.
Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001
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Fig. 7. MR imaging of a nondisplaced subchondral fracture of the postero-medial tibial plateau (T2 weighted images with fat suppression) mimicking a posterior medial meniscus root avulsion.
posterior area of the medial tibial plateau as an indirect sign of a potential MMPRA. In this situation we advocate that an Arthro-CT should be used to confirm the diagnosis, as a non-displaced subchondral fracture could mimic this particular aspect on MRI (Fig. 7). Reports on the clinical outcome of meniscal root tear repair are limited and largely involve skeletally mature patients. Nevertheless, the factors that influence the outcome of meniscal root repair in adults have been studied. A higher BMI, a greater varus mechanical axis angle, a higher outerbridge grade cartilage status and a larger preoperative meniscal extrusion negatively impact postoperative outcomes [23]. Our patient has none of these risk factors. In our opinion, all posterior horn avulsions in children or adolescent should be repaired. As advocated by Seil et al. [22], avulsion of the posterior root of the medial meniscus results in a ‘phantom meniscus’ meaning that the majority of the meniscal tissue is still present, but that it is biomechanically inefficient. Such a lesion may lead subsequently to the development of cartilage lesions over a 6-month period. In this age group the surgical technique must take into consideration the presence of an open physis in order to avoid potential iatrogenic growth disturbances. In this case report, the transosseous suture technique with two 2.5 mm tibial tunnels allows the surgeon to minimize physeal damage. They are positioned in the central area of the tibial physis to reduce the risk of growth disturbance [24]. Although we obtained a satisfactory clinical result and recommend this surgical procedure in similar cases of MMPRA we do acknowledge a number of limitations in this report. Our followup is short and late failure is still possible. Further studies with a larger sample are needed to accurately define the prevalence of this lesion, its healing rate and to define the subtle clinical and radiological signs that could aid in an early diagnosis in a skeletally immature population. 3. Conclusion This study reports an unusual case of a skeletally immature patient who presented with a root avulsion of the posterior medial meniscus. This type of injury leads to instability and displacement of the posterior portion of the meniscus, altering meniscal function. This can potentially lead to joint degeneration and osteoarthritis with disastrous consequences for a young patient. We emphasize the importance of the indirect MRI signs that can lead a clinician to suspect the diagnosis of MMPRA and describe the surgical technique for repair of the meniscal root in this population of patients. Our case confirms that a satisfactory outcome can be expected after an arthroscopic reduction of MMPRA
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Please cite this article as: Sonnery-Cottet B, et al, Root avulsion of the posterior horn of the medial meniscus in skeletally immature patients, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.07.001