03 November 2022: Articles
Injury to the Posterior Horn of the Lateral Meniscus from a Misplaced Tibial Tunnel for Anterior Cruciate Ligament Reconstruction: A Case Report
Challenging differential diagnosis, Unusual or unexpected effect of treatment, Diagnostic / therapeutic accidents, Rare disease, Clinical situation which can not be reproduced for ethical reasonsAmar S. Vadhera 12ABCDEF*, Jonathan S. Lee3E, Harsh Singh1ABE, Safa Gursoy4AE, Kyle N. Kunze 5EF, Nikhil N. Verma1AE, Jorge Chahla1AE
Am J Case Rep 2022; 23:e937581
BACKGROUND: Posterior meniscal root avulsions can cause meniscal extrusion, joint space narrowing, and progressive knee arthritis. Iatrogenic posterior meniscal root avulsions after malpositioning of the transtibial tunnels during anterior cruciate ligament (ACL) reconstruction can account for poor long-term outcomes seen in some patients following ACL reconstruction. Therefore, correct transtibial tunnel placement during ACL reconstruction is essential to avoid iatrogenic meniscal damage.
CASE REPORT: A 32-year-old man presented with 1 year of right knee pain and instability following a non-contact twisting injury sustained while playing soccer. An ACL tear with no meniscal involvement was diagnosed at an outside institution. A double-bundle reconstruction was performed at that time. Three months after surgery, a medial partial meniscectomy was performed after a medial meniscal tear and failure to reduce initial symptoms during the index procedure. Advanced imaging at our institution 6 months later demonstrated an iatrogenic lateral posterior meniscal root avulsions after malpositioning of the transtibial tunnels. Given the ACL graft integrity upon arthroscopic evaluation, the root tear was repaired using a 2-tunnel transtibial pull-out technique. Advanced imaging 1 year after surgery showed a well-maintained meniscal repair with no extrusion.
CONCLUSIONS: Accurate transtibial tunnel placement during ACL reconstructive surgery is vital to avoid meniscal root detachment and the associated complications resulting in poor patient outcomes from this iatrogenic injury. Clinicians treating patients with a history of cruciate ligament reconstruction presenting with postoperative pain and instability should consider this pathology in their differential diagnosis.
Keywords: Iatrogenic, Anterior Cruciate Ligament, Meniscal Root, anterior cruciate ligament reconstruction, Lateral Meniscus, Male, Humans, Adult, Menisci, Tibial, Tibial Meniscus Injuries, Anterior Cruciate Ligament, anterior cruciate ligament reconstruction, Iatrogenic Disease
Meniscal root tears are radial tears within 10 mm of the meniscal insertion or a bony root avulsion and have gained attention in recent years with advancements in clinical and radiographic diagnostic modalities [1–4]. Meniscal root tears have been reported to account for 10% to 21% of all meniscal tears and affect an estimated 100 000 patients annually . Importantly, meniscal root injuries can result in meniscal extrusion, joint space narrowing, and inadequate conversion of axial loads into hoop stresses within the joint [6,7]. Furthermore, they have been demonstrated to be an independent predictor of tibiofemoral cartilage degradation and osteoarthritis, equivalent to those experienced after a total meniscectomy [1,8–12]. Meniscal repair techniques have been shown to successfully restore knee kinematics, highlighting the importance of diagnosing and appropriately treating these injuries . However, there is still much controversy regarding the management and ideal surgical technique to treat meniscal tears, specifically regarding the location and type of tear and the assessment of methods of evaluation after repair .
The anatomy and injury mechanisms of the attachment sites of the menisci have been elucidated by recent quantitative and qualitative anatomic investigations . The relative proximity of the posterior root of the lateral meniscus to the tibial footprint of the anterior cruciate ligament (ACL) can place the lateral posterior root attachment at risk while drilling the tibial tunnel during an ACL reconstruction. This relationship is critical to consider when treating ACL injuries to avoid such iatrogenic detachments of the meniscal root, as this represents an avoidable complication of this procedure that otherwise can compromise long-term outcomes [15–17].
The aim of this case report is to describe the presentation and treatment of a patient with an iatrogenic posterior lateral meniscus root tear due to malpositioned tibial tunnels during a prior ACL reconstruction. Additionally, the authors present this case to increase awareness and understanding of posterior lateral meniscal root anatomy and recognize this uncommon injury. The patient was informed that data concerning his case would be submitted for publication, and he provided consent.
After surgery, the patient was made non-weight-bearing on his operative lower extremity for 4 weeks. A brace locked in extension was used during this time and removed only when the patient was performing physical therapy, which was started on postoperative day 1, to begin early passive range-of-motion exercises. Knee flexion was limited between 0° to 90° of flexion for the first 2 weeks and then progressed as tolerated. The patient was seen at 6, 9, and 12 months after surgery, with an intact lateral meniscal repair seen on imaging and the absence of symptoms (Figure 3).
This case report describes an iatrogenic lateral meniscal posterior root tear that occurred secondary to a malpositioned tibial tunnel during primary ACL reconstruction. As such, this case report highlights the importance of anatomic tibial tunnel placement during an ACL reconstruction and raises awareness of the possibility of an iatrogenic injury to the meniscus during the procedure.
Meniscal root anatomy and ligamentous arthroscopic landmarks in the knee have been comprehensively studied through cadaveric analyses as guides for ACL tunnel placement. Fujishiro et al described the posterior horn of the lateral meniscus forming an anterolateral and posteromedial crura, which intertwined into the posterior margin of the ACL footprint . Further, Ziegler et al reported that the posterior horn of the lateral meniscus was approximately 15.7 mm anteromedially from the tibial center of the ACL footprint, 4.8 mm posterior to the center of the anteromedial bundle, and 5.6 mm anterior to the center of the posterolateral bundle . With an understanding of the fundamental anatomic relationships between the lateral meniscus posterior root attachment and the tibial-sided ACL footprint, treatment of concomitant posterior root lateral meniscal and ACL injuries has been well described . In addition, previous case series have described iatrogenic anterior root lateral meniscus injury after ACL reconstruction and posterior root meniscal injury following PCL reconstruction, as well as their successful treatment [18,25]. Nevertheless, although a rare injury, this case report establishes the possibility of iatrogenic injury to the posterior root of the lateral meniscal during tibial tunnel drilling for an ACL reconstruction and further emphasizes the importance of its anatomic placement.
Lateral meniscal posterior root tears are commonly associated with ACL injury mechanisms, with a prevalence of 8% to 14% in patients presenting with an ACL tear [20,24,26]. This is plausible as the meniscus serves as a secondary stabilizer in antero-posterior translation and rotatory movement to the ACL [21,27]. Prior studies have investigated the biomechanical effects of lateral meniscal posterior root tears and repairs in both ACL-intact and ACL-deficient knees. Frank et al found the posterior root to be a significant stabilizer in the knee during anterior tibial translation at lower flexion angles and the primary stabilizer during internal rotation at higher flexion angles . Therefore, the loss of the posterior root can contribute to increased strain on an ACL graft and subsequent failure, while preventing potential overload when repaired [20,21]. In our case, the decision to not revise the previously reconstructed ACL, which was far too posteriorly positioned, was based on the anteroposterior stability and good integrity of the graft confirmed during surgery. Nonetheless, in the presence of persistent symptoms and subjective laxity after ACL reconstruction, we recommend obtaining an MRI to promptly identify pathology either overlooked during surgery or that may have developed as the result of iatrogenic injury. However, there is still controversy regarding the proper treatment of posterior root tears, as well as regarding the assessment of methods of evaluation after repair . Ultimately, future research is necessary to understand the specific outcomes and optimal treatment for iatrogenic damage to the meniscus following ligament reconstructive surgery.
This case report had limitations. The index surgery was performed at an outside institution. However, the authors are confident that the meniscal injury was iatrogenic in nature given the results noted from diagnostic imaging, utilizing a combination of MRI and CT scans, along with the assessment of intraoperative findings.
This case report describes a complication of primary ACL reconstruction consisting of an iatrogenic posterior horn lateral meniscal root tear due to non-anatomic tibial tunnel placement. The iatrogenic nature of this injury underscores the importance of an accurate tibial tunnel placement during ACL reconstruction to avoid posterior meniscal root injuries and other associated complications. Physicians should consider such pathology in the differential diagnosis of patients presenting with persistent pain and instability following a primary ACL reconstruction.
FiguresFigure 1.. Preoperative imaging of the right knee. (A) Lateral and standing (B) anteroposterior radiographs demonstrate a malpositioned tibial anterior cruciate ligament reconstruction tunnel (white arrows). This was confirmed to be in a non-anatomic position on (C) axial and (D) sagittal computed tomography. (E) Axial and (F) sagittal magnetic resonance imaging show the posterior location of the tunnel, blunting the lateral posterior meniscal root. Figure 2.. Arthroscopic photographs of a lateral posterior root tear (right knee). (A) Evidence of a significant root tear due to the non-anatomic, posterior position of the anterior cruciate ligament (ACL) tibial tunnel. (B) Cadaveric image demonstrating the position of the lateral and medial meniscus posterior root attachment (MPRA and LPRA) in relation to the anatomic ACL location (black circle) and current tunnel location (red circle). (C) Repair of the posterior horn of the lateral meniscus using a transtibial pull-out technique. LFC – lateral femoral condyle; LTP – lateral tibial plateau; AG – ACL graft. Figure 3.. Postoperative follow-up (A) 6-month and (B) 12-month coronal magnetic resonance imaging views demonstrating an intact lateral meniscal repair without a sign of meniscal extrusion.
1.. 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(9); 1922-31
2.. Jones AO, Houang MTW, Low RS, Wood DG, Medial meniscus posterior root attachment injury and degeneration: MRI findings: Australas Radiol, 2006; 50(4); 306-13
3.. Shepard MF, Hunter DM, Davies MR, The clinical significance of anterior horn meniscal tears diagnosed on magnetic resonance images: Am J Sports Med, 2002; 30(2); 189-192
4.. 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(10); 569-74
5.. Cinque ME, Chahla J, Moatshe G, Meniscal root tears: A silent epidemic: Br J Sports Med, 2018; 52(13); 872-76
6.. Nicholas SJ, Golant A, Schachter AK, Lee SJ, A new surgical technique for arthroscopic repair of the meniscus root tear: Knee Surg Sports Traumatol Arthrosc, 2009; 17(12); 1433-36
7.. Berthiaume M-J, Raynauld J-P, Martel-Pelletier J, Meniscal tear and extrusion are strongly associated with progression of symptomatic knee osteoarthritis as assessed by quantitative magnetic resonance imaging: Ann Rheum Dis, 2005; 64(4); 556-63
8.. Miller TT, Staron RB, Feldman F, Cepel E, Meniscal position on routine MR imaging of the knee: Skeletal Radiol, 1997; 26(7); 424-27
9.. Kenny C, Radial displacement of the medial meniscus and Fairbank’s signs: Clin Orthop, 1997(339); 163-73
10.. Ding C, Martel-Pelletier J, Pelletier J-P, Knee meniscal extrusion in a largely non-osteoarthritic cohort: Association with greater loss of cartilage volume: Arthritis Res Ther, 2007; 9(2); R21
11.. Hunter DJ, Zhang YQ, Niu JB, The association of meniscal pathologic changes with cartilage loss in symptomatic knee osteoarthritis: Arthritis Rheum, 2006; 54(3); 795-801
12.. Wang Y, Wluka AE, Pelletier J-P, Meniscal extrusion predicts increases in subchondral bone marrow lesions and bone cysts and expansion of subchondral bone in osteoarthritic knees: Rheumatol Oxf Engl, 2010; 49(5); 997-1004
13.. Karia M, Ghaly Y, Al-Hadithy N, Current concepts in the techniques, indications and outcomes of meniscal repairs: Eur J Orthop Surg Traumatol, 2019; 29(3); 509-20
14.. Johannsen AM, Civitarese DM, Padalecki JR, Qualitative and quantitative anatomic analysis of the posterior root attachments of the medial and lateral menisci: Am J Sports Med, 2012; 40(10); 2342-47
15.. LaPrade CM, Smith SD, Rasmussen MT, Consequences of tibial tunnel reaming on the meniscal roots during cruciate ligament reconstruction in a cadaveric model, Part 1: The anterior cruciate ligament: Am J Sports Med, 2015; 43(1); 200-6
16.. Laprade CM, James EW, Engebretsen L, Laprade RF, Anterior medial meniscal root avulsions due to malposition of the tibial tunnel during anterior cruciate ligament reconstruction: two case reports: Knee Surg Sports Traumatol Arthrosc, 2014; 22(5); 1119-23
17.. Weiler A, Wagner M, Kittl C, The posterior horn of the lateral meniscus is a reliable novel landmark for femoral tunnel placement in ACL reconstruction: Knee Surg Sports Traumatol Arthrosc, 2018; 26(5); 1384-91
18.. Gursoy S, Perry AK, Brady A, Optimal tibial tunnel placement for medial and lateral meniscus root repair on the anteromedial tibia in the setting of anterior and posterior cruciate ligament reconstruction of the knee: Am J Sports Med, 2022; 50(5); 1237-44
19.. LaPrade RF, Matheny LM, Moulton SG, Posterior meniscal root repairs: Outcomes of an anatomic transtibial pull-out technique: Am J Sports Med, 2017; 45(4); 884-91
20.. Frank JM, Moatshe G, Brady AW, Lateral meniscus posterior root and meniscofemoral ligaments as stabilizing structures in the ACL-deficient knee: A biomechanical study: Orthop J Sports Med, 2017; 5(6); 2325967117695756
21.. Shybut TB, Vega CE, Haddad J, Effect of lateral meniscal root tear on the stability of the anterior cruciate ligament-deficient knee: Am J Sports Med, 2015; 43(4); 905-11
22.. Fujishiro H, Tsukada S, Nakamura T, Attachment area of fibres from the horns of lateral meniscus: anatomic study with special reference to the positional relationship of anterior cruciate ligament: Knee Surg Sports Traumatol Arthrosc, 2017; 25(2); 368-73
23.. Ziegler CG, Pietrini SD, Westerhaus BD, Arthroscopically pertinent landmarks for tunnel positioning in single-bundle and double-bundle anterior cruciate ligament reconstructions: Am J Sports Med, 2011; 39(4); 743-52
24.. Forkel P, Reuter S, Sprenker F, Different patterns of lateral meniscus root tears in ACL injuries: Application of a differentiated classification system: Knee Surg Sports Traumatol Arthrosc, 2015; 23(1); 112-18
25.. Kennedy NI, Michalski MP, Engebretsen L, LaPrade RF, Iatrogenic meniscus posterior root injury following reconstruction of the posterior cruciate ligament: A report of three cases: JBJS Case Connect, 2014; 4(1 Suppl. 6); e20
26.. Brody JM, Lin HM, Hulstyn MJ, Tung GA, Lateral meniscus root tear and meniscus extrusion with anterior cruciate ligament tear: Radiology, 2006; 239(3); 805-10
27.. Musahl V, Citak M, O’Loughlin PF, The effect of medial versus lateral meniscectomy on the stability of the anterior cruciate ligament-deficient knee: Am J Sports Med, 2010; 38(8); 1591-97
07 Dec 2023 : Case reportA 65-Year-Old Man Presenting to the Emergency Department with Gastric Hemorrhage Caused by a Glomus Tumor
Am J Case Rep In Press; DOI:
07 Dec 2023 : Case reportGraves' Disease Exacerbation with Impending Thyroid Storm After SARS-CoV-2 Infection: A Case Report
Am J Case Rep In Press; DOI:
05 Dec 2023 : Case reportNovel Mini-Invasive Surgical Technique for Treating Fifth Metacarpal Neck Fractures: A Case Report
Am J Case Rep In Press; DOI:
Most Viewed Current Articles
06 Dec 2021 : Case reportLipedema Can Be Treated Non-Surgically: A Report of 5 Cases
Am J Case Rep 2021; 22:e934406
07 Dec 2021 : Case reportEdwardsiella tarda: A Classic Presentation of a Rare Fatal Infection, with Possible New Background Risk Fac...
Am J Case Rep 2021; 22:e934347
19 Jul 2022 : Case reportAtlantoaxial Subluxation Secondary to SARS-CoV-2 Infection: A Rare Orthopedic Complication from COVID-19
Am J Case Rep 2022; 23:e936128