Characterization of Cruciate Ligament Impingement: The Influence
Transcrição
Characterization of Cruciate Ligament Impingement: The Influence
Characterization of Cruciate Ligament Impingement: The Influence of Femoral or Tibial Tunnel Positioning at Different Degrees of Knee Flexion Diego Costa Astur, M.D., Ciro Veronese Santos, M.D., Vinicius Aleluia, M.D., Nelson Astur Neto, M.D., Gustavo Gonçalves Arliani, M.D., Camila Cohen Kaleka, M.D., Abdalla Skaf, M.D., and Moises Cohen, M.D., Ph.D Purpose: We aimed to analyze how different positions of the tibial and femoral tunnels when used for anterior cruciate ligament (ACL) reconstruction affect relations with the posterior cruciate ligament (PCL) at different degrees of knee flexion. Information gained from this study may be helpful in determining optimal placement of the graft in ACL reconstructive surgery. Methods: We divided 10 cadaveric knees into 2 groups of 5 and had either their femoral or tibial ACL insertion detached. For each specimen, 16 different positions were reproduced during ACL reconstruction based on a combination of 4 different tunnels in the tibia for group A (anterior-medial, anterior-lateral, posterior-medial, and posterior-lateral) and 4 in the femur for group B (anterior-proximal, anterior-distal, posterior-proximal, and posteriordistal) with 4 of knee flexion for each (0 , 45 , 90 , and 135 ). We performed a magnetic resonance imaging (MRI) study for each configuration and analyzed the cruciate ligament positioning. Results: We identified 3 different situations: no contact between cruciate ligaments, contact without deformity, and contact with deformity. In group A, the degree of flexion (P ¼ .003) and ligament insertion positioned in the posterior quadrants (P < .05) were statistically significant for the presence of ACL impingement. Ligament contact with deformity was identified in 18 (22.5%) configurations, mostly when the knee was flexed 45 and 90 and the ACL was in the posterior quadrants. For group B, “contact with deformity” was identified in 23 MR images, mostly (12 cases) with the graft position being in the anterior-distal configuration, but it was not significant for the occurrence of cruciate impingement. Conclusions: Impingement with ligament deformity is greater when the graft is fixed at the posterior quadrants of the tibial footprint, regardless of the degree of knee flexion. Although quite common, the ligament position in the femoral footprint was not a primary cause of ACL impingement with deformity. Clinical Relevance: This study helps identify positions of the tibial or femoral tunnels during ACL reconstruction to avoid impingement between cruciate ligaments. T he anterior cruciate ligament (ACL) is an important structure in the knee because of both its anterior and rotational stabilization properties. Proximally, it From Departamento de Ortopedia e Traumatologia (D.C.A., G.G.A., M.C.) da Escola Paulista de Medicina/UNIFESP, São Paulo; Department of Orthopaedic Surgery (C.V.S., V.A.), Instituto Cohen, São Paulo; Department of Orthopaedic Surgery (C.C.K.) Faculdade de Medicina da Santa Casa de Misericórdia de São Paulo, São Paulo; Department of Radiology (A.S.), Alta Institute, São Paulo, SP, Brazil; and Department of Orthopaedic Surgery (N.A.N.), University of Tennessee, Memphis, TN, U.S.A. The authors report that they have no conflicts of interest in the authorship and publication of this article. Received August 16, 2012; accepted January 3, 2013. Address correspondence to Diego Costa Astur, M.D., Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, Rua Borges Lagoa 837, 5 andar, Vila Clementino, São Paulo, SP, Brazil. E-mail: [email protected] Ó 2013 by the Arthroscopy Association of North America 0749-8063/12541/$36.00 http://dx.doi.org/10.1016/j.arthro.2013.01.008 inserts on the medial aspect of the lateral femoral condyle; distally, it inserts anteriorly and laterally to the medial tibial spine.1-4 Anatomic reconstruction of the ACL is of paramount importance to achieve optimal clinical outcomes after surgery. The position of the tibial and femoral tunnels for ACL reconstruction is well documented and is one of the most important factors determining clinical outcome.5 Anatomic positioning of the tunnel decreases the incidence of complications, such as restriction of knee motion, graft failure, or graft impingement against the posterior cruciate ligament (PCL) or lateral femoral condyle. ACL impingement on the PCL has not been extensively studied. Previous studies have shown that contact between the different ligamentous structures in the knee might have a potential impact on joint pain, decreased flexion, and increased instability.6,7 Thus, the correct positioning of the tibial and femoral tunnels in Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol -, No - (Month), 2013: pp 1-7 1 2 D. C. ASTUR ET AL. the coronal and sagittal planes in the ACL footprint is necessary to achieve optimal results. Small variations in these tunnels can affect the position of the graft and result in impingement on the PCL. The purpose of this study was to analyze how different positions of both the tibial and femoral tunnels in ACL reconstruction affect the relations with the PCL at different degrees of knee flexion. Information gained from this study may be helpful for defining optimal placement of the graft during ACL reconstruction. We hypothesized that small variations in these tunnels can affect the position of the graft and result in impingement on the PCL. Methods After institutional review board approval, we dissected 10 human cadaveric knees in a cadaver laboratory. They were between 27 and 43 years old without previous ligament injuries or pre-existing arthritis. We then took a medial parapatellar approach in each specimen to access the ACL without affecting the stability of the knee joint. We then used a surgical marking pen to demarcate the femoral and tibial ACL footprints before intentionally detaching the ACL at its insertion on the femur or tibia, keeping its respective counterpoint insertion intact. We divided the specimens into 2 groups of 5 knees each based on where the ACLs were detached from their insertiondfrom the ACL tibial footprint (group A) or from the ACL femoral footprint (group B). We stitched the free end of the ACL with a No. 5 Ethibond wire (Ethicon, Somerville, NJ) to make its manipulation and relocation in the desired position easier (Fig 1). We then divided the previously marked footprint of the respective detached insertion of the ACL into 4 quadrants within the native ACL footprint for groups A and Bdgroup A: anterior-medial, anterior-lateral, posterior-medial, and posterior-lateral; group B: anteriorproximal, anterior-distal, posterior-proximal, and posteriordistal (Fig 2A). For each quadrant in groups A and B, we drilled a surgical tunnel in a standard fashion (ACL anatomic reconstruction guides) with a 2-mm guidewire. We placed an ACL tibial aimer set at 55 in the center of each quadrant of the ACL tibial insertion site previously marked. The position of the aimer on the tibial cortex was between 3 and 6 cm medial to the tibial tubercle. However, the tunnels were not drilled with the use of a reamer. We just drilled the tunnels with the 2-mm guidewire, avoiding bone fragility because of the fact that all 4 tunnels were too close to each other. Next, we turned attention to the femoral tunnels. We placed the femoral tunnel in the center of each previously marked insertion site and drilled each tunnel without an ACL femoral aimer and with 90 of knee flexion. Fig 1. Anterior cruciate ligament detached from the femoral footprint stitched with an Ethibond suture wire to reposition the ligament as desired. Therefore, each knee in group A had 4 tibial tunnels and each knee in group B had 4 femoral tunnels (Fig 2B). To place the free end of the detached ACL in the desired position, we stitched the Ethibond wire to the guidewire and pulled it through the respective tunnel. We then fixed the Ethibond wire in the tibial shaft for group A and in the femoral shaft for group B in a way that kept the ACL tensioned (a bone tunnel perpendicular to the tibial and femoral shaft fixing the Ethibond wire to an EndoButton [Smith & Nephew Endoscopy, Andover, MA] in the contralateral cortex). After placing the free end of the ligament in the desired quadrant in both groups, we created a polyvinyl chloride pipe model to sustain the desired angle of knee flexion (0 , 45 , 90 , or 135 ) (Fig 3). We performed magnetic resonance imaging (MRI) for each specimen and for every ligament positioning in the quadrants. We analyzed the distance between the ACL and PCL and measured, in millimeters, the coronal, sagittal, and oblique axial images after MRI was performed for every quadrant situation and degree of knee flexion described. We obtained T2-weighted and 1-mm-slice MRI for each specimen and for each of their 16 possible graft location/knee flexion combinations. We used the major point of contact between the ACL and the PCL to CHARACTERIZATION OF CRUCIATE LIGAMENT IMPINGEMENT 3 Fig 2. (A) Four different quadrants inside the femoral and tibial footprints: anterior-proximal tunnel (AP), anteriordistal tunnel (AD), posterior-proximal tunnel (PP), posterior-distal tunnel (PD), anterior-medial tunnel (AM), anteriorlateral tunnel (AL), posterior-medial tunnel (PM), and posterior-lateral tunnel (PL). (B) Different tunnel configurations in the femur and tibia. determine the distance between them. This is the midpoint between proximal and distal insertions, which corresponds to the MRI sagittal cut immediately below the Blumensaat line. We used the oblique axial MRI view to measure the distance between the ligaments or the presence of deformity. As a control group, we submitted 5 intact knees of healthy individuals without ligament injuries or preexisting arthritis to MRI studies to determine the presence of contact between the cruciate ligaments. established as 20% (power of 80%) to find at least a 50% difference between different positions. We used an exchangeable correlation matrix for all analyses performed. To compare the presence of deformity in different positions and degrees of flexion, we used generalized estimating equations with logit link for binary data. To determine the greater possibility of impingement between the ligaments, we used the Bonferroni multiple comparison method (P < .05). Statistical Analyses We performed sample size estimates before choosing cadaveric knees. A type I error was pre-established as 5% (95% confidence interval), and a type II error was Using the 10 knee specimens, we created 32 different combinations considering 4 possible insertions in the femoral ACL footprint, 4 possible insertions in the tibial footprint, and 4 different grades of knee flexion. After Results Fig 3. Polyvinyl chloride pipe construct for fixed flexion positions of the knee. (A) Neutral; (B) 45 ; (C) 90 ; (D) 135 . 4 D. C. ASTUR ET AL. performing a total of 160 MRI studies to examine every specimen in every combination, we identified 3 relation patterns between the ACL graft and the PCL: no contact between the cruciate ligaments, contact without deformity of the ligaments, and contact with deformity (Fig 4). The specimens that had their tibial ACL insertion detached (group A) had 57 (71.25%) situations with ligament contact but no deformity, most of them (61.4%) when the graft was placed in the anterior quadrants. Ligament contact with deformity was identified in 18 (22.5%) configurations, mostly when the knee was flexed 45 and 90 and the ACL was in the posterior quadrants (7 in the posteromedial and 11 in the posterolateral quadrants). Finally, no contact was seen in 5 (6.35%) MR images; 3 (60%) of these were in 45 of knee flexion. The distance between the ligaments ranged from 1 to 2 mm. In group B, when the femoral ACL insertion was detached, “no contact” was identified in 32 (40%) MRI studies, 19 (60%) of which were in the anteriorproximal quadrant in all different degrees of knee flexion. The distance varied between 0.5 and 2.5 mm. Contact without deformity was seen in 25 (31.25%) situations, most of them (56%) in 90 and 135 of flexion. Contact with deformity was identified in 23 (28.75%) MR images, mostly (53%) in the anterior-distal configuration. Although contact with deformity was more common at the femur than at the tibia, there were no statistically significant results that would favor the presence of impingement caused by a specific quadrant of the femoral footprint. In group A, the degree of flexion (P ¼ .003) was statistically more significant for the presence of ACL impingement than for the position of the ligament at the tibial insertion (P ¼ .08). Knee positions of both 0 and 135 of flexion showed ligament deformity more frequently than did the intermediate angles (P < .05), and this deformity was more frequent when the graft was placed at the posterior quadrants of the tibial footprint (P < .05). For group B, the graft position was not statistically significant for the occurrence of ACL impingement on the PCL. Contact between ligaments occurred more at 45 of flexion than at other grades of flexion (P < .05). At 90 of flexion, deformity was more common than at 135 of flexion (P < .05). There was no difference between 0 and 90 of flexion or between 0 and 135 of flexion. In the same fashion, but keeping the ligaments intact, we analyzed the 5 knees from the control group with MRI. Each specimen underwent one MRI study for every degree of flexion for a total of 20 studies. There was no contact between the cruciate ligaments in 18 positions, and there was contact without deformity in 2 positions (both in flexion at 45 ) (Table 1). Discussion A potential complication of improper positioning of the bone tunnels is contact between the new ACL and the PCL at any point during full excursion of the knee joint, which may result in instability and restriction in knee flexion.5 This impingement may lead to knee pain after ACL reconstruction. Nishimori et al.8 reported that the majority of the population with intact ACLs have no contact between these 2 structures. However, the same authors claimed that some healthy individuals do have some contact between the native ligaments, but they do not report the existence of deformity among ACL and PCL ligaments or pain symptoms. The results of the present study suggest that some healthy individuals (10%) have physiologic contact between the 2 ligaments without clinical symptoms. Cruciate impingement as a cause of painful symptoms in patients with ACL reconstruction seems to be caused not only by contact between the structures but also by the impression of one ligament on the other and the subsequent deformation of this neoligament.7 In our study, several tunnel positions and certain degrees of knee flexion were identified through MRI as potential risks leading to cruciate contact and subsequent deformity. This seemed to occur significantly more frequently in tunnels created through the posterior quadrants of the ACL footprint on the tibia. When we analyzed the position of the femoral tunnel as a risk for ligamentous deformity, none of the quadrants were significant risk factors. Fig 4. Oblique axial magnetic resonance image. (A) Contact with deformity of both ligaments refers to the situation in which there is loss of contour definition of the cruciate ligaments, which causes morphologic changes in both ligaments. (B) Contact between the ligaments without deformity of the ligaments. (C) There is no contact between the ligaments. The arrows correspond to the site of impingement. Knee 1 Cadaveric Knees Tibia Anterior-medial Anterior-lateral Posterior-medial Posterior-lateral 0 Knee 2 45 90 135 0 Knee 3 45 90 135 0 45 Knee 4 90 135 0 Knee 5 45 90 135 0 45 90 135 CWOD CWOD CWOD CWOD CWOD CWOD CWOD CWOD 1 CWOD CWOD CWOD CWOD CWOD CWOD CWOD 1.5 1.5 CWOD CWOD CWOD CWOD CWOD CWOD CWOD CWOD CWOD CWOD CWOD 1 CWOD CWOD CWOD CWOD CWOD CWOD CWOD 2 CWOD CWOD CWOD CWOD CWD CWOD CWOD CWD CWOD CWOD CWOD CWD CWD CWOD CWOD CWOD CWD CWOD CWOD CWD CWD CWOD CWOD CWD CWD CWOD CWOD CWOD CWD CWOD CWOD CWD CWD CWOD CWOD CWD CWD CWD CWOD CWD CWD CWD Knee 6 0 45 90 Knee 7 135 0 45 Knee 8 90 135 0 45 Knee 9 90 135 0 45 Knee 10 90 135 0 45 90 135 Femur Anterior-proximal 1.5 2 1 2 1 1.5 CWOD 2 2 1.5 1.5 2 1.5 2.5 0.5 1.5 1.5 2.5 2 2.5 Anterior-distal CWD CWD CWOD 2 CWD CWD CWOD CWOD CWD CWD CWD CWOD CWOD CWD CWD 1 CWD CWD CWD CWOD Posterior-proximal CWOD 1 CWOD CWOD CWOD CWOD CWOD 1 1 CWOD 1 1 CWOD CWOD CWOD 1.5 1.5 CWOD CWOD 2 Posterior-distal 1.5 CWD CWD 2 CWOD CWD CWD CWOD 1 CWD CWOD CWD CWOD CWD CWD CWD CWOD CWD CWD CWOD Knee 11 Control Group Knee 12 Knee 13 Knee 14 Knee 15 0 45 90 135 0 45 90 135 0 45 90 135 0 45 90 135 0 45 90 135 1 CWOD 1.5 1.5 1 1 1 1 0.5 CWOD 1 1 0.5 0.5 1 1 1 1 1.5 1.5 The distance is measured in millimeters. CWD, ligamental contact with deformity; CWOD, ligamental contact without deformity. *The measurements correspond to the value of each knee examined. CHARACTERIZATION OF CRUCIATE LIGAMENT IMPINGEMENT Table 1. Results Obtained for the Different Positions of the Tibial and Femoral Tunnels with Different Degrees of Knee Flexion* 5 6 D. C. ASTUR ET AL. Some studies report that impingement between the neo-ACL and the PCL is more significant when the knee is in full extension.6,9,10 Simmons et al.11 considers that impingement is greater with the knee in flexion. This study demonstrates that the degree of flexion of the knee is a predictor of impingement. With the tibial tunnels, when the knee was in extension or flexed 135 , contact without deformity of the ligaments was frequently observed, regardless of the quadrant insertion position. However, when the tibial tunnels were drilled at the posterior quadrants, contact with deformity was very common, particularly when the knee was flexed at 45 and 90 . Previous studies reported that the clinical diagnosis of contact, with or without deformity, during arthroscopic procedures is difficult.6,10 This is one of the reasons for the misdiagnosis of a possible impingement during ACL reconstruction screw fixation, which usually occurs at 90 of knee flexion, thereby requiring MRI for the diagnosis. When we analyzed the femoral tunnels, ligamentous contact was seldom seen in extension or at 135 of flexion. In this same group, we observed impingement most often at 45 of flexion. This study focused on the influence of the exact location of the entry point of the femoral or tibial tunnel inside its respective ACL footprint as a cause of postoperative ligament impingement. Although other studies analyzed different ACL reconstruction techniques and the incidence of impingement, our results may guide a more precise positioning of the tunnel during surgery. Furthermore, graft choice during ACL reconstruction can also increase ligament impingement and deformity. Studies concluded that the average area and diameter in the midportion of the semitendinosus and gracilis tendon graft and the bone-patella tendonbone graft are greater than those of the native ACL.12,13 The analysis of multiple knee flexion grades helped define the relationship between the cruciate ligaments along the full excursion of the knee range of motion. Furthermore, this study identified not only the concept of contact but also how deformity of the ligaments after contact may play a role in postoperative ligament impingement. This would be a potential cause for the appearance of symptoms after ACL reconstruction. Because this was a cadaveric study, clinical outcome and type of ligament relationship could not be analyzed. Avoiding impingement with ligament deformity during ACL reconstruction seems to be necessary to avoid adverse patient symptoms such as instability and knee flexion deficits.5,14,15 Knowledge of safe zones within the footprint to avoid PCL impingement can minimize the chance of these symptoms occurring. Limitations There are several limitations to this study. Cadaveric studies do not always reproduce the physiology of a live joint. The main limitation was the lack of a third group that would assess ligament detachment on the tibia and femur and favor the crossing of 4 different positions of the femur and the tibia tunnels. In this case, 16 different situations for each knee could possibly indicate tunnel positions more prone to ligament contact as well as positions that are safer to use to avoid ligament contact. Moreover, we did not assess the relation between the ligament impingement and the roof impingement. Positioning the ACL on the tibia may be one of the reasons for these types of impingements, leading to limitation of range of motion and pain.16 In addition, the flexion angle for the fixation might have an impact on graft rotation and therefore an influence on graft impingement. Conclusions Impingement with ligament deformity is more likely when the graft is fixed in the posterior quadrants of the tibial footprint, regardless of the degree of knee flexion. Although quite common, the ligament position in the femoral footprint was not found to be a primary cause of ACL impingement with deformity. References 1. Cohen M, Astur Dda C, Kaleka CC, et al. Introducing 3-dimensional stereoscopic imaging to the study of musculoskeletal anatomy. Arthroscopy 2011;27:593-596. 2. Duthon VB, Barea C, Abrassart S, Fasel JH, Fritschy D, Menetrey J. Anatomy of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 2006;14:204-213. 3. Matsumoto H, Suda Y, Otani T, Niki Y, Seedhom BB, Fujikawa K. Roles of the anterior cruciate ligament and the medial collateral ligament in preventing valgus instability. J Orthop Sci 2001;6:28-32. 4. Sakane M, Fox RJ, Woo SL, Livesay GA, Li G, Fu FH. In situ forces in the anterior cruciate ligament and its bundles in response to anterior tibial loads. J Orthop Res 1997;15:285-293. 5. Howell SM, Hull ML. Checkpoints for judging tunnel and anterior cruciate ligament graft placement. J Knee Surg 2009;22:161-170. 6. Fujimoto E, Sumen Y, Deie M, Yasumoto M, Kobayashi K, Ochi M. Anterior cruciate ligament graft impingement against the posterior cruciate ligament: diagnosis using MRI plus three-dimensional reconstruction software. Magn Reson Imaging 2004;22:1125-1129. 7. Maak TG, Bedi A, Raphael BS, et al. Effect of femoral socket position on graft impingement after anterior cruciate ligament reconstruction. Am J Sports Med 2011;39: 1018-1023. 8. Nishimori M, Sumen Y, Sakaridani K, Nakamura M. An evaluation of reconstructed ACL impingement on PCL using MRI. Magn Reson Imaging 2007;25:722-726. 9. Iriuchishima T, Tajima G, Ingham SJ, Shen W, Smolinski P, Fu FH. Impingement pressure in the anatomical and nonanatomical anterior cruciate ligament reconstruction: a cadaver study. Am J Sports Med 2010;38:1611-1617. CHARACTERIZATION OF CRUCIATE LIGAMENT IMPINGEMENT 10. Strobel MJ, Castillo RJ, Weiler A. Reflex extension loss after anterior cruciate ligament reconstruction due to femoral “high noon” graft placement. Arthroscopy 2001;17:408-411. 11. Simmons R, Howell SM, Hull ML. Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study. J Bone Joint Surg Am 2003;85-A:1018-1029. 12. Iriuchima T, Shirakura K, Yorifuji H, Aizawa S, Fu FH. Size comparison of ACL footprint and reconstructed autograft. Knee Surg Sports Traumatol Arthrosc. 2012 Mar 10 [Epub ahead of print]. 13. Pujol N, Queinnec S, Boisrenoult P, Magdes A, Beaufils P. Anatomy of the anterior cruciate ligament related to 7 hamstring tendon grafts. A cadaveric study. Knee. 2012 Nov 14 [Epub ahead of print]. 14. Iriushima T, Tajima G, Ingham SJ, Shirakura K, Fu FH. PCL to graft impingement pressure after anatomical or non-anatomical single-bundle ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2012;20:964-969. 15. Liu SH, Osti L, Dorey F, Yao L. Anterior cruciate ligament tear. A new diagnostic index on magnetic resonance imaging. Clin Orthop Relat Res 1994;302:147-150. 16. Kropf EJ, Shen W, van Eck CF, Musahl V, Irrgang JJ, Fu FH. ACL-PCL and intercondylar notch impingement: magnetic resonance imaging of native and double-bundle ACL reconstructed knees. Knee Surg Sports Traumatol Arthrosc. 2012 May 24 [Epub ahead of print].
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