Magnetic resonance evaluation of remodeling process in patellar tendon graft

Several studies have shown the accuracy of magnetic resonance imaging in evaluating the reconstructed anterior cruciate ligament. The purpose of the current study was to clarify the clinical usefulness of magnetic resonance imaging for evaluating the reconstructed anterior cruciate ligament in comparison with using arthroscopy. Sixty-nine patients who had an anterior cruciate ligament reconstruction using a bone-tendon-bone autograft were examined by magnetic resonance imaging and arthroscopy an average of 12 months after surgery. There were 41 males and 28 females with an average age of 25.9 years (range, 15-66 years). The interval from surgery to the magnetic resonance imaging or arthroscopic evaluation was a mean of 12 months (range, 4-32 months). The magnetic resonance imaging findings of the reconstructed anterior cruciate ligament were classified as either high, intermediate, or low intensity. The arthroscopic findings also were classified as either graft impingement at the intercondylar notch or no impingement. In the 47 anterior cruciate ligament grafts that were not impinged, the signal intensity remained low and did not increase during second-look arthroscopy. In contrast, 22 anterior cruciate ligament grafts that were impinged showed an increased signal intensity in the distal area of the graft at the time of the second-look arthroscopy. Furthermore, no significant correlation was observed between the presence of a high signal intensity and postoperative instability. The high signal intensity of the anterior cruciate ligament graft on magnetic resonance imaging was found to be caused by graft impingement. These findings therefore show a clear association between graft impingement and the subsequent appearance of the graft on magnetic resonance imaging.     

前十字韧带移植重建后移植物撞击新类型

 目的 通过双源CT三维重建前十字韧带（anterior cruciate ligament,ACL）移植重建后的移植物和骨隧道,分析移植物撞击症。方法 2012年11月至2014年11月,采用双源CT对134例ACL移植重建后患者的膝关节进行扫描,三维重建股骨和胫骨隧道、ACL重建移植物等。其中单束重建118例,男83例,女35例;年龄15~64岁,平均32岁。观察重建术后移植物是否受到撞击、撞击来源并进行分类;分别测量股骨、胫骨隧道的相对位置,并对有撞击与无撞击组患者进行统计比较。结果 基于双源CT移植物重建,根据ACL移植重建后移植物是否受到撞击分组,无撞击组39例（33%,39/118）,有撞击组79例（67%,79/118）。存在撞击者再根据撞击部位分为髁间窝出口撞击组77例（占总数的65%,占撞击组的97%）和髁间窝顶中途撞击组2例（占总数的2%,占撞击组的3%）。进一步根据撞击来源不同,再对髁间窝出口撞击组分为3个亚型,即鸟喙撞击10例（3%,10/77）、胫骨平台撞击46例（60%,46/77）、钳夹撞击21例（27%,21/77）。单因素方差分析显示,鸟喙撞击、胫骨平台撞击、钳夹撞击各组与无撞击组的股骨、胫骨隧道位置均无显著性差异。结论 基于双源CT三维重建ACL术后移植物扫描发现3种新的移植物撞击类型, 即髁间窝顶中途撞击、胫骨撞击和钳夹撞击。     

Comparison of sagittal obliquity of the reconstructed anterior cruciate ligament with native anterior cruciate ligament using magnetic resonance imaging

Purpose: This study was conducted to compare the obliquity of asymptomatic anterior cruciate ligament (ACL) grafts with normal controls using sagittal magnetic resonance imaging (MRI). Type of Study: Case control study. Methods: Sagittal MRIs from 30 patients with a reconstructed ACL graft and from 30 individuals with an intact ACL were reviewed. Reconstructed patients were operated on with a 2-incision technique using a patellar tendon autograft. These selected patients had a normal or nearly normal IKDC score with a 3 mm or less anterior posterior translation on KT-1000 arthrometer testing compared with the intact knee. MRI showed a continuous and homogeneous graft without evidence of roof impingement. Obliquity of the grafted ACL was determined on each lateral MRI by measuring the intersection of the graft line with the tibial plateau plane. These figures were compared with data similarly obtained from 30 individuals with a stable knee and an intact ACL determined by history and physical examination. Results: Graft obliquity in reconstructed patients averaged 67° with a range between 55° and 81°. In normal controls, intact ACL obliquity averaged 51° with a range between 45° and 55°. The difference between the two groups was statistically significant (P <.0001). Conclusions: MRIs of patients with an appropriate tibial tunnel placement in order to avoid notch impingement showed a continuous and homogeneous graft similar to the native ACL, but with a more vertical graft that does not recreate the normal sagittal obliquity. However, according to arthrometer testing, these more vertical grafts can control anterior posterior knee displacement.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 257–261     

Variations in the three-dimensional location and orientation of the ACL in healthy subjects relative to patients after transtibial ACL reconstruction

Recent reports have indicated that anatomical placement of the anterior cruciate ligament (ACL) graft is an important factor for restoration of joint function following ACL reconstruction. The objective of this study was to address a need for a better understanding of anatomical variations in ACL position and orientation within the joint. Specifically, variations in the ACL anatomy were assessed by testing for side-to-side ACL footprint location symmetry in a healthy population relative to the operative and contralateral knee in a patient population after traditional transtibial single-bundle ACL reconstruction. MRI and three-dimensional modeling techniques were used to determine the in vivo tibiofemoral ACL footprint centers and the resulting ACL orientations in both knees of 30 healthy subjects and 30 subjects after transtibial ACL reconstruction. While there were substantial inter-subject variations in ACL anatomy, the side-to-side RMS differences in the ACL footprint center were 1.20 and 1.34 mm for the femur and tibia, respectively, for the healthy subjects and no clinically meaningful intra-subject differences were measured. However, there were large intra-subject side-to-side differences after transtibial ACL reconstruction, with ACL grafts placed 5.63 and 7.64 mm from the center of the contralateral femoral and tibial ACL footprint centers, respectively. Grafts were placed more medial, anterior, and superior on the femur and more posterior on the tibia; producing grafts that were more vertical in the sagittal and coronal planes. Given the large variation among subjects, these findings advocate the use of the contralateral ACL morphology for retrospectively evaluating patient-specific anatomic graft placement.     

Radiographic evaluation of anterior cruciate ligament graft failure with special reference to tibial tunnel placement

Graft failure in anterior cruciate ligament (ACL) reconstruction can result from anterior placement of the tibial tunnel. Conventional radiographic evaluation of this problem does not take into account potential changes in tibio-femoral relationship caused by ACL instability. A retrospective radiographic evaluation of failed as well as successful ACL reconstructions was carried out. Both published radiographs as well as those obtained of patients treated by the authors were evaluated for tibial tunnel placement, roof impingement, and tibial position relative to the femur. In the second part of the study, the radiographs were obtained under standard conditions in both failed ACL reconstructions and normal knees. The results of both parts of the study indicate that lateral radiographs of the extended knee with ACL instability are likely to show subtle anterior tibial subluxation. The subluxation can give the impression of roof impingement on the graft. However, the majority of the failed knees had similar tibial tunnel placement compared with successful reconstructions and would appear unimpinged once corrected for subluxation. The diagnosis of graft impingement by the femoral intercondylar roof has to take into account potential tibial subluxation. Impingement as a cause graft failure may be less common than previously thought.Arthroscopy 1998 Mar;14(2):206-11     

Accuracy of femoral tunnel placement and resulting graft force using one- or two-incision drill guides. A cadaver study on ten paired knees

Recently, one-incision drill guides introduced through predilled tibial tunnels have become popular in anterior cruciate ligament (ACL) reconstruction. No data are available on the reproducibility of the tunnel placement when this drill guide is used. The primary goal of this study was to compare accuracy of tunnel placement using the one-inciscion (all-inside) and the conventional two-incision drill guide (outside-in) to the location of the center of the normal ACL attachment. Furthermore, our goal was to measure the forces seen by the normal ACL during extension from 90° of flexion, when the tibia is subjected to 100 N anterior load (22.7 lbs), and compare these with the forces measured in the reconstructions performed with the two drill guides. The center of the tunnel on the lateral femoral condyle using the two different drill guides was measured with a three-dimensional pointer and compared with the center of the normal ACL insertion site. Forces in the normal ACL and the reconstructed ligament were measured with a buckle transducer in a loaded and an unloaded state at four different flexion angles. The one-incision drill guide led to a statistically more proximal placement of the graft than both the conventional drill guide and the center of the normal ACL. Both drill guides led to an anterior placement compared with the normal ACL. There was no difference in the graft forces after reconstruction with the two drill guides, but the forces in the loaded grafts were twice those of the normal ACL.     

Sagittal plane imaging parameters for computer-assisted fluoroscopic anterior cruciate ligament reconstruction.

Reproducible graft placement in anterior cruciate ligament (ACL) reconstructions is considered to be a critical factor affecting the successful clinical outcome of the procedure. Many current ACL instrument systems rely on intra-articular landmarks to guide the ACL tunnel placement. However, most of these instrument systems use mobile soft tissues as landmarks. We hypothesize that consistently identifiable radiographic contour landmarks can be established that can be used to improve the reproducibility of graft tunnel placement in fluoroscopically and computer-assisted ACL reconstructions. For the tibia, magnetic resonance imaging (MRI) scans showed the average ACL attachment site to be projected at 46% on a line extending from the anterior to the posterior cortices. Intraoperative fluoroscopic images were checked for the reproducibility of this line and its clinical use. For the femur, lateral radiographs demonstrated a consistent relationship between the intercondylar roof line (Blumensaat's line) and the nearly circular profile of the posterior and inferior contour of the lateral femoral condyle. The middle of this circular profile is consistently projected on Blumensaat's line at 66% of its anterior-to-posterior direction. Intraoperative images were used, which showed the aiming drill at the point of entering the lateral femoral condyle. Instead of determining the femoral attachment site relative to Blumensaat's line, we can thus determine its position relative to the center of the circle. Based on intraoperative x-rays, the proposed femoral ACL attachment site can be projected on a line parallel with the Blumensaat's line from the circle center in the posterior direction. Our results indicate that there are consistently identifiable radiographic features on the tibia and femur contours that can be used for fluoroscopic and computer-assisted guidance of ACL graft placement.     

Magnetic resonance imaging of bioabsorbale polylactic acid interference screws during the first 2 years after anterior cruciate ligament reconstruction.

Bioabsorbable screws composed of poly(L-lactic acid) (PLA) were used for graft fixation and studied prospectively with serial magnetic resonance imaging (MRI) scans at 8, 16, and 24 months after autogenous patellar tendon anterior cruciate ligament (ACL) reconstruction in 10 patients. Conventional spin echo, proton density, and T2-weighted double echo sequences were obtained, as well as T2-weighted fat-saturated fast spin echo sequences. All but one of the screws (19 of 20) were evident in all serial scans. These showed minimal decrease in size over time. The one screw that had completely disappeared 8 months after reconstruction had cracked during insertion. None of the reconstructed ACL grafts showed clinical instability, persistent effusions, or detectable adverse reactions to the screws. Two patients developed abnormal signal in the tibial tunnel: one developed fluid anterior to the graft, and the other developed increased signal within the graft. The abnormal signal resolved with time in both patients. Other than the preceding changes, no abnormalities were detected on conventional sequences. Fat-saturated fast spin echo sequences showed a variable amount of increased signal around the tunnels, suggesting edema or fibrovascular marrow changes. The changes noted near the tunnels on the fat-suppressed scans most probably represent a general reaction to surgical insult rather than a reaction to the bioabsorbable screws, as similar changes were noted at the patellar harvest site.     

前内侧入路解剖重建单束前交叉韧带的临床评估

目的评估关节镜下经前内侧入路解剖重建单束前交叉韧带(ACL)的位置、形态及临床效果。方法对25例ACL断裂患者在关节镜下经前内侧入路应用解剖重建技术行单束ACL重建术,移植物应用自体腘绳肌腱。术后行X线、MRI检查,了解骨道情况,观察移植物形态及张力,并与11例健侧膝关节的正常ACL进行对比。应用Lysholm评分系统评估膝关节功能。结果术后X线片显示股骨隧道内口位于髁间窝顶与股骨后缘皮质线交叉点前缘,胫骨隧道内口位于髁间窝顶后方。MRI显示所有重建ACL张力良好,ACL上倾角为50.82°±4.57°,胫骨平台止点至前缘距离与平台纵径比值为0.50±0.04,两项与对照组比较差异均无统计学意义(P0.05)。患者均获得随访,时间为13~44个月。Lysholm评分术后为92.20分±4.29分,明显高于术前的64.76分±7.16分(P0.01)。结论关节镜下经前内侧入路解剖重建ACL的位置及形态接近解剖结构,早中期临床效果满意。     

膝关节前交叉韧带胫骨止点的软组织解剖标记

背景：膝关节前交叉韧带（ACL）重建时,胫骨骨道定位不准会产生重建韧带与髁间窝的撞击或起不到维持膝关节稳定性的作用。因此,确定ACL胫骨止点的位置非常重要。目的：研究膝关节ACL胫骨止点前内束（AMB）和后外束（PLB）与软组织标记后交叉韧带（PCL）和外侧半月板前角的距离,从而明确ACL胫骨止点在胫骨平台的位置,为ACL损伤双束重建提供理论支持。方法：解剖18个膝关节尸体标本（左膝10个,右膝8个）,测量ACL中点、AMB中点、PLB中点与PCL和外侧半月板前角的距离,并分析左、右膝关节是否存在差异。结果：AMB中点与PCL和外侧半月板前角的距离分别为（15.00±3.97）mm和（19.78±4.10）mm;PLB中点与两者的距离分别为（10.17±5.56）mm和（19.50±4.40）mm;ACL中点与两者的距离分别为（12.67±4.52）mm和（19.61±3.87）mm。左右膝关节ACL中点、AMB中点、PLB中点与软组织解剖标记的距离无明显统计学差异。结论：膝关节ACL损伤行手术重建时,可采用PCL和外侧半月板前角作为定位标记。     

Definitive landmarks for reproducible tibial tunnel placement in anterior cruciate ligament reconstruction

The purpose of this prospective study was to define constant anatomic intraarticular and extraarticular landmarks that can be used as definative reference points to reproducibly create a tibial tunnel for anterior cruciate ligament (ACL) reconstruction that (1) results in an impingement-free graft in full extension without an intercondylar roofplasty; (2) positions the tibial tunnel's intraarticular orafice sagittally central in the original ACL insertion without visually guessing; (3) positions the tibial tunnel such that the sagittal tunnel-plateau angle is parallel with the sagittal intercondylar roof-plateau angle in full extension to minimize shear seen by the graft at the tibial tunnel inlet, and by doing so; (4) maximizes tunnel length to avoid patellar tendon graft-tunnel length mismatch allowing for endosteal interference screw fixation on both sides of the joint. Anatomic dissections in 50 knees showed the ACL sagittal central insertion point on the intercondylar floor averages 7 mm (range 7 to 8 mm) sagittally anterior to the anterior margin of the posterior cruciate ligament (PCL) with the knee flexed 90° such that the PCL may be used as a reliable reference landmark for locating the ACL sagittal central insertion. This constant relationship was found to be independent of knee size. Extraarticularly, beginning the tibial tunnel sagittally 1 cm above the superior (sartorial) border of the pes anserinus insertion and coronally 1.5 cm posteromedial from the medial margin of the tibial tubercle along the superior surface of the pes, directed toward the sagittal central ACL insertion, led to a sagittal tunnel-plateau angle that averaged 68°(range 64° to 72°) with a corresponding tunnel length that averaged 58 mm (range 50 to 65 mm) in 23 knees. This data correlated well with data obtained clinically in a series of 50 consecutive ACL reconstructions using intraarticular PCL and extraarticular pes anserine-medial tibial tubercle referenced tibial tunnels in which postoperative full extension lateral radiographs confirmed a sagittal tunnel-plateau angle parallel or near parallel with the intercondylar roofplateau angle in all cases averaging 68° ± 3.8°. Tibial tunnel length averaged 60 mm (range 52 to 66 mm) and in no case was there a patellar tendon autograft-tunnel length mismatch.     

前十字韧带重建中的移植物位置偏移

目的 计算可吸收界面螺钉导致的移植物偏离隧道位移,探讨其对前十字韧带重建产生的影响.方法 19个新鲜尸体膝关节标本,随机选取5个,采用7 mm、8 mm、9 mm界面螺钉固定自体肌腱,测定偏移距离.另外14个膝关节分为等长组和解剖组,等长组膝关节测量界面螺钉固定后及校正位置的移植物拉长距离;解剖组膝关节于膝关节生物力学测试仪上分别测定ACL完整组、ACL缺失组、偏移组和校正组在134 N前向负荷下膝关节屈曲0°、15°、30°、60°和90°位的胫骨前向位移.结果 (1)肌腱偏移:直径7mm、8 mm、9mm的界面螺钉分别使移植物偏移(2.36±0.11)mm、(2.72±0.06)mm、(3.00±0.06)mm.(2)等长性:初始拉长小于3 mm,偏移拉长大于3 mm,校正拉长小于3 mm.(3)生物力学:屈膝0°、15°位,ACL完整组与偏移组、校正组差异无统计学意义.屈膝30°、60°、90°位ACL完整组与其他各组比较差异均有统计学意义,屈膝30°、60°位偏移组与校正组比较差异有统计学意义.结论 无论等长重建还是解剖重建,界面螺钉均影响移植物的股骨隧道口位置.前十字韧带重建预先校正股骨隧道口位置,移植物基本会处于预先的理想位置.

Abstract：

Objective To investigate the impact of graft position shift on anterior cruciate ligament reconstruction induced by femoral fixation of interference screw. Methods Nineteen fresh cadaveric knees were used and assigned to three groups. 1) Study of graft position shift: 5 knees were randomly selected, interference screws of 7 mm, 8 mm and 9 mm were used in autologous tendon fixation, then the graft position shift were measured. 2) Study of isometry: 7 knees were randomly divided into the isometric reconstruction group (D group). In the D group, Retrobutton, interference screw and interference screw in location-corrected bone tunnel were used respectively as fixation. The isometry of grafts was evaluated. 3) Study of tibia anterior translation: 7 knees were randomly divided into the anatomic reconstruction group (J group). In the J group,the tibia anterior translation was measured in four different conditions in the same joint: intact knee joint,knee joint without ACL, ACL anatomic reconstruction by interference screw fixation, and ACL anatomic reconstruction by interference screw fixation with corrected bone tunnel location. Results 1) With 7 mm, 8mm and 9 mm interference screw fixation, graft position shift were (2.36±0.11) mm, (2.72±0.06) mm and (3.00±0.06) mm respectively. 2) Graft length change: graft length change in Retrobutton group and corrected bone tunnel group were less than 3 mm, while graft length change in those fixed with interference screw were stretched in more than 3 mm. 3) Study of tibia anterior translation: there was no difference among the intact group, the anatomic group and the corrected group at 0° and 15°. However, the difference was found between the intact group and other groups at 30°、60° and 90° of flexion, as well as between these two reconstructed methods at 20° joint flexion (P＜0.05). Conclusion In both isometric and anatomic ACL reconstruction with interference screw, the graft is pushed tightly toward the femoral tunnel wall, which shifts the graft away from the desired position. In our study we find out that the corrected location of the femoral bone tunnel significantly improves the isometry of ACL reconstruction and anatomic reconstruction.     

Biomechanical properties of interference screw implantation in replacement of the anterior cruciate ligament with patellar and hamstring transplants. An experimental study using roentgen stereometry analysis (RSA)

This experimental roentgen stereometric analysis (RSA) study was performed to measure micromotions between the graft and tunnel under submaximal load in anterior cruciate ligament (ACL) reconstruction. The aim was to evaluate the maximum load at failure, linear stiffness, and slippage of bone-patellar-tendon-bone (BPTB) grafts fixed with interference screws compared to quadrupled hamstring grafts fixed with interference screws. We used 15 porcine tibia specimens for the study. In the BPTB group, the 10 x 25-mm bone plugs were fixed in a tunnel with 10 mm in diameter using a 7 x 25-mm titanium interference screw (n = 5) or a biodegradable screw (n = 5). The five hamstring transplants were folded to a four-stranded graft and armed with a baseball stitch suture. The sutured side was fixed with a 7 x 25-mm biodegradable polylactide screw in an 8-mm tunnel. The tibial bones, tendon grafts, and interference screws were marked with tantalum beads. The grafts were mounted to a custom made load frame and loaded parallel to the axis under RSA control increasing the force in steps of 50 N. Micromotions between bone plug, screw, and tibia were measured with RSA. Accuracy of RSA for the in vitro study was evaluated as 0.05 mm. Hamstring grafts failed at significantly lower maximum loads (492 +/- 30 N) than BPTB grafts (658 +/- 98 N). Linear stiffness of the hamstring graft fixations was eight times lower compared to the BPTB grafts (403 +/- 141 N/mm vs 3500 +/- 1300 N/mm). There was no significant difference between the biodegradable and titanium screws in the BPTB group. Slippage of the graft started at 82 +/- 35 N load in the hamstring group and at 428 +/- 135 N in the BPTB group. Slippage of the graft at 75% of the maximum pull-out strength was measured as 0.36 +/- 0.25 mm in the BPTB and 2.58 +/- 1.08 mm in the hamstring group. The interference screw fixation of a quadrupled hamstring graft showed a lower linear stiffness and an earlier slippage compared to a patellar tendon bone plug. Slippage of the hamstring grafts at submaximal loads may result in fixation failure during rehabilitation.     

Magnetic resonance imaging evaluation after re-notchplasty at second-look arthroscopy

Purpose: To clarify the effects of re-notchplasty on magnetic resonance imaging (MRI) for evaluating the reconstructed anterior cruciate ligament (ACL). Type of Study: Observational cohort study. Methods: Twenty-one patients who underwent re-notchplasty at second-look arthroscopy were examined. The MRI findings of the reconstructed ACL were classified as having either high, intermediate, or low intensity based on the clarity of appearance. Results: The impinged group at second-look arthroscopy underwent re-notchplasty. Twelve patients continued to show a high signal intensity that did not decrease after re-notchplasty at the second-look operation. In contrast, 9 impinged ACL grafts showed a decreased signal intensity of the graft after re-notchplasty. Conclusions: In this study, 9 cases showed a decreased intensity and were considered to have an impingement at the notch, which thus influenced the maturity process by decreasing the compression on the reconstructed ACL.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 6 (July-August), 2002: pp 584–588     

股骨Blumensaat线的MRI测量及其对重建ACL的意义

目的应用MRI对股骨Blumensaat线的测量,为重建前交叉韧带(anterior cruciate ligament,ACL)提供参考。方法通过选择100例正常的膝关节伸直位磁共振检查结果,在适当的切面上绘制Blumensaat线延长线与胫骨平台的交点,测量其在胫骨矢状径位置及其与后交叉韧带(posterior cruciate ligament,PCL)的距离,并与ACL胫骨侧生理止点中心和PCL的距离比较。结果 Blumensaat线延长线与胫骨平台的交点在胫骨矢状径上距前缘(51.9±7.3)%,与PCL距离(14.2±2.5)mm,较ACL生理止点中心靠后。结论为避免髁间窝前方撞击,重建ACL胫骨侧止点定位于胫骨平台生理性止点中心后方或PCL前方8～10mm,个别人需更后方。     

Editorial Commentary: Goldilocks and the Three Grafts: Managing Tendon Harvest and Graft Length Problems in Autograft Anterior Cruciate Ligament Reconstruction

Autograft hamstring tendon harvest in anterior cruciate ligament (ACL) reconstruction can occasionally result in a graft length that is inadequate for creation of a robust ACL graft. Patients at risk for an abnormally short hamstring may also be high risk for ACL reinjury. Graft augmentation with allograft may be a suboptimal solution to this problem. Therefore, a reliable means for preoperative estimation of hamstring tendon length by magnetic resonance imaging measurement could avoid this pitfall. However, even with a reliable correlation between magnetic resonance imaging measurement and actual harvested tendon length, establishing a simple, clinically relevant threshold below which hamstring grafts should be avoided remains elusive. By contrast, all-soft-tissue quadriceps autograft avoids the potential length problems inherent to both bone tendon bone (graft–tunnel mismatch) and hamstring tendon grafts, but intermediate- and long-term outcome studies are still needed to validate all-soft-tissue quadriceps autograft in ACL reconstruction.     

Anterior cruciate ligament reconstruction stability with continuous passive motion. The role of isometric graft placement.

A comparison was made of the stability of isometric versus nonisometric anterior cruciate ligament (ACL) reconstructions when subjected to immediate postoperative continuous passive motion (CPM). Anterior cruciate ligament reconstructions were performed on 13 anatomic specimen knees using bone/patellar tendon/bone grafts. Nine ACL substitutions were considered isometric with maximum graft length changes of less than 1 mm. Four ACL substitutions were nonisometric with graft length changes of 3 mm or greater resulting from tightening in flexion. The specimens were subjected to CPM through 0 degrees-95 degrees knee flexion. Knee stability was remeasured with a knee arthrometer at three and 14 days after beginning CPM. All four nonisometric specimens had failed within three days, with increased anterior laxity of 2-9 mm in both the Lachman (20 degrees) and anterior drawer (90 degrees) positions. All nine isometric reconstructions successfully retained pre-CPM anterior stability within 1 mm after 14 days of CPM. This investigation illustrates the importance of isometric graft placement for ACL reconstruction success. Continuous passive motion does not appear to adversely affect immediate ACL-substitute integrity or fixation if graft placement is isometric (less than 1 mm of graft excursion through 0 degrees-110 degrees of knee motion). Continuous passive motion may cause graft deformation, fixation failure, or both, with resultant loss of knee stability if the graft is not isometrically positioned (greater than 3 mm of graft excursion resulting from tightening in flexion).     

Anatomical relationship between insertion sites,tunnel placement,and lateral meniscus anterior horn injury during single and double bundle anterior cruciate ligament reconstructions: A comparative macroscopic and histopathological evaluation in cadavers

PurposeThe influence of tunnel extension outside the anatomical anterior cruciate ligament (ACL) insertion in single-bundle (SB) or double-bundle (DB) ACL reconstruction is unclear. This study aimed to investigate the anatomical relationship between ACL insertion and tunnel extension in SB and DB ACL reconstruction, and the impact of tibial tunnel extension to the insertion of anterior horn of lateral meniscus in terms of injury.MethodsForty-six paired cadaver knees (mean age, 82.7 ± 10.7 years) were used. Right and left knees were used for SB (10 mm) and DB tunnel reaming (6 mm for the anteromedial and posterolateral bundles). Tibial and femoral tunnels were created to aim at the center of the ACL insertion by arthroscopic visualization. The relationship between tunnel extension and ACL insertion was evaluated macroscopically, and there ratio in two groups were compared by chi-square test. Further, the relative risk for meniscus injury based on tunnel placement was estimated. Coronal section of tibia and parallel section to Blumensaat line in femur were prepared to evaluate the relationship among tunnel position, ACL insertion, and anterior horn of the meniscus histologically.ResultsTibial tunnel extension out of the ACL insertion was observed macroscopically in 9 (39.1%) knees of the SB group, and 3 (13.0%) of the DB group (p = 0.045). In femoral tunnels, extension out of the ACL insertion was seen in 8 (34.8%) knees of the SB group and 1 (4.3%) of the DB group (p = 0.011). Partial injuries of the lateral meniscus anterior horn (LMAH) were observed in 5 (21.7%) knees of the SB group and 1 (4.3%) knee of the DB group (p = 0.091). The relative risk for LMAH injury was calculated as 5.0 (odds ratio, 6.1). Microscopically, SB tunnels appeared to expand out of ACL insertion, both in the femur and tibia.ConclusionsThe incidence of tunnel extension out of the ACL insertion in femur and tibia were higher with SB than with DB reconstruction. Furthermore, injury rate of the LMAH in the DB group was lower.     

ACL Reconstruction Graft Angle and Outcomes: Transtibial vs Anteromedial Reconstruction

Background

The importance of creating an anatomic anterior cruciate ligament (ACL) reconstruction has been receiving significant attention. The best technique by which to achieve this anatomic reconstruction continues to be debated. The two most common methods are the transtibial (TT) and anteromedial (AM) techniques. Each has its advantages and disadvantages, and the literature comparing the two remains uncertain.

Questions/Purposes

In this prospective comparative study, we aimed to compare the ACL graft and tunnel angles achieved using the anatomic transtibial (TT) and anteromedial (AM) techniques; compare the ACL graft and tunnel angles in knees that have undergone ACL reconstruction and knees with intact ACLs; and determine whether differences in the graft or tunnel angle produce differences in clinical outcomes, as measured using both physical exam and patient-reported outcomes, after ACL reconstruction.

Methods

Patients who underwent primary ACL reconstruction with bone–tendon–bone grafts using a TT or AM technique were included. Femoral graft angle (FGA), tibial graft angle (TGA), and sagittal orientation of the reconstructed ACL and contralateral native ACL were measured on post-operative magnetic resonance imaging. Post-operatively, patients underwent measurement of knee stability and completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) survey.

Results

Twenty-nine patients were enrolled (AM group, 14; TT group, 15); at follow-up, KOOS data were available for 26 patients (13 in each group). There were no differences in sagittal ACL graft angle between groups or in comparison with the normal knee. The FGA was more vertical after TT reconstructions; the TGA was comparable between groups. There were no significant differences in 2-year post-operative physical exam measurements or in KOOS scores.

Conclusion

Anatomic ACL angle was restored after reconstruction with both the TT and AM techniques, despite different FGAs. No significant differences in clinical outcome were noted between groups on physical exam or KOOS at 2 years after surgery. These results suggest that TT reconstruction results in a graft position similar to that seen in AM reconstruction and that the location of the intra-articular tunnel aperture matters more than the orientation of the tunnel.

     

Endoscopic anterior cruciate ligament reconstruction using a computer-assisted fluoroscopic navigation system

Background During anterior cruciate ligament (ACL) reconstruction, placement of the reconstructed ligament affects the clinical results. To accomplish accurate and reproducible placement of the tibial bone tunnel, we employed a fluoroscopic navigation system for endoscopic ACL reconstruction. In this study, preciseness of the tibial tunnel placement was evaluated, and the advantages and disadvantages of this navigation system for endoscopic ACL reconstruction are discussed. Methods Altogether, 16 knees of 16 patients who had undergone ACL reconstruction using this system (navi group) were evaluated regarding the positioning of the tibial tunnel against Blumensaat's line using X-p and the route of the graft by magnetic resonance imaging (MRI). Another 16 knees of 16 patients who underwent endoscopic ACL reconstruction without the navigation system were the controls (control group). Results At the 1-year follow-up, maximally extended lateral knee X-p revealed that the anterior edge of the tibial tunnel and Blumensaat's line were almost aligned and that roof impingement was avoided; the T2-weighted MR images showed that the graft was placed close to and parallel to the intercondylar roof in all the knees of the navi group. The ratio of the distance between Blumensaat's line and the anterior edge of the tibial tunnel at the level of the tibial plateau to the anteroposterior width in fully extended true lateral radiographs was 2.7% ± 3.4% in the navi group and 8.4% ± 7.4% in the control group. Conclusions The computer-assisted fluoroscopic navigation system improves accuracy and decreases dispersion of the tibial tunnel placement against Blumensaat's line in single-bundle ACL reconstruction. This innovative device renders the reconstruction procedure more reliable, eliminating the problem of skeletal variation among patients. However, the function of this navigation system for femoral tunnel placement is insufficient at present. Further refinement of the system is necessary, and the method of application requires improvement.