Biomechanics of the anterior cruciate ligament and implications for surgical reconstruction

Abstract Injury to the anterior cruciate ligament (ACL) is regarded as critical to the physiological kinematics of the femoral-tibial joint, its disruption eventually causing long-term functional impairment. Both the initial trauma and the pathologic motion pattern of the injured knee may result in primary degenerative lesions of the secondary stabilisers of the knee, each of which are associated with the early onset of osteoarthritis. Consequently, there is a wide consensus that young and active patients may profit from reconstructing the ACL. Several factors have been identified as significantly influencing the biomechanical characteristics and the functional outcome of an ACL reconstructed knee joint. These factors are: (1) individual choice of autologous graft material using either patellar tendon-bone grafts or quadrupled hamstring tendon grafts, (2) anatomical bone tunnel placement within the footprints of the native ACL, (3) adequate substitute tension after cyclic graft preconditioning, and (4) graft fixation close to the joint line using biodegradable graft fixation materials that provide an initial fixation strength exceeding those loads commonly expected during rehabilitation. Under observance of these factors, the literature encourages mid-to long-term clinical and functional outcomes after ACL reconstruction.     

All-Inside Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) reconstruction is one of the most commonly performed knee operations. An “all-inside” technique creates bone sockets for ACL graft passage, as opposed to more traditional full bone tunnels, and typically incorporates suspensory fixation instead of screw fixation to secure the graft. This technique may be indicated for any ACL reconstruction surgery, where adequate bone stock exists to drill sockets and to use cortical fixation. The technique may be used with all soft tissue, as well as bone plug ACL grafts and autograft hamstring or quadriceps tendon; most allograft tendon options may be performed with an all-inside technique. Advantages include anatomic tunnel/socket placement, decreased postoperative pain and swelling, minimal hardware, appropriate graft tensioning and retensioning, and circumferential graft to bone healing. Tips for successful all-inside surgery include matching graft diameter to socket diameter, drilling appropriate length sockets based on individual graft length, so as not to “bottom out” the graft and confirming cortical button fixation intraoperatively. Potential complications include graft-socket mismatch, full-tunnel reaming, and loss of cortical fixation. Multiple studies have shown the all-inside technique to have similar or superior biomechanical properties and clinical outcomes compared to the more traditional full-tunnel ACL reconstruction techniques.     

Editorial Commentary: Tunnel Widening After Anterior Cruciate Ligament Reconstruction May Increase Laxity and Complicate Revision

Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. It has been demonstrated that femoral tunnels enlarge anteriorly and distally (ie, the direction where the mechanical traction force of the graft works) rather than concentrically after anatomic double-bundle ACL reconstruction using hamstring autografts. This finding suggests that the wall supporting the graft moves closer to the direction of the pull, leading to increased laxity of the knee joint due to TW. The causes of TW are presumed to be multifactorial, with both biological and mechanical features. Biological factors include osteolytic cytokines that enter the space between the graft and the bone through the synovial fluid. Mechanical factors include longitudinal graft motion by extracortical femoral fixation (known as the bungee effect), transverse graft motion (also called the windshield-wiper effect), improper graft placement, higher initial graft tension, accelerated rehabilitation, and so on. Although TW does not seem to affect short-term clinical outcomes from studies published to date, it is plausible to speculate that the expansion of the bone tunnel (ie, the edge where the graft tendon is fixed) would theoretically increase joint laxity to some extent, and it would be premature to conclude that TW has no effect on clinical outcomes relative to graft–tunnel micromotion. In addition, there is a general consensus that the presence of expanded tunnels often severely complicates revision ACL reconstruction. In ACL reconstruction using the hamstring tendon, it is necessary to take into account the possibility of a shift in the tunnel position when determining the location of the femoral tunnel.     

膝关节前交叉韧带翻修及影响首次重建疗效的相关因素分析

目的总结影响关节镜下前交叉韧带重建疗效的相关因素。方法回顾性分析135例前交叉韧带翻修病例的相关临床资料,进行膝关节Lysholm评分综合分析。结果膝关节继发性疾患、骨隧道位置、移植物的张力、髁间窝撞击、所移植肌腱的固定和术后康复训练6大因素是影响关节镜下膝关节前交叉韧带重建疗效的关键因素。结论高度重视以上6方面因素并正确处理,能有效提高关节镜下膝关节前交叉韧带重建的成功率和治疗效果。     

Accurate placement of bone tunnels in reconstruction of the anterior cruciate ligament - a contribution of computer-assisted navigation

Rupture of the anterior cruciate ligament (ACL) is one of the most frequent injuries to the knee joint in the young. ACL repair is a major orthopedic procedure most often performed in the younger adult population. Early stabilization of the knee joint by ACL reconstruction also decreases the risk of injury to other important structures. At ACL reconstruction, the biggest problem is usually the exact placement of drilled tunnels. This significantly affects the outcome of surgery, i. e., range of motion, knee joint stability, reaction of the synovium in the knee, pain, impingement and potential graft failure with lesion development. However, 70 % of ACL reconstructions are carried out by orthopedic surgeons whose experience is limited to less than 20 ACL repair procedures in a year! Arthroscopy does not allow the surgeon to gain a complete 3D view of important anatomical structures, particularly in the anteroposterior direction. Computer-assisted navigation systems should aid in minimizing these problems. First reports on the use of computer-assisted navigation in ACL reconstruction, which have already been published in the international literature, have provided clear evidence that more exact bone tunnel placement can be achieved with navigation than with the use of conventional techniques. In addition, kinematic navigation enables us to measure anteroposterior and rotational knee stability, isometry, impingement and the angles of bone tunnel placement. It permits a choice from various types of graft. Last but not least, kinematic navigation provides a tool for recording surgery outcomes without a necessity to use further examination methods. Its drawbacks, namely, the learning curve, additional fixation of navigation probes to the femur and tibia and slightly longer operative time, should be considered in the context of presumed long-term benefits for the patient.     

Current concepts in the treatment of anterior cruciate ligament disruption

Treatment of anterior cruciate ligament injuries has changed considerably in recent years. The purpose of this paper is to discuss the past and present treatment for anterior cruciate ligament (ACL) disruptions in athletic individuals. In addition, this paper will discuss current trends in rehabilitation, such as immediate motion, weight bearing, and close kinetic chain exercises, and provide the scientific rationale for these rehabilitation principles. The treatment of individuals who have suffered an ACL disruption has changed dramatically over the years. The treatment of ACL ruptures has made a full circle. The first reconstructive procedure described used a patellar tendon graft. Then primary ACL repairs were advocated. With the limited success of that procedure, the nonoperative treatment was popularized, with reconstruction performed only after the conservative program failed. With this treatment plan, clinicians noted early degenerative joint changes and an increase in meniscus tears in the ACL deficient knee. Thus, reconstructive surgery using a patellar tendon graft was again advocated. Today, the current trend in the treatment of ACL tears is an arthroscopically assisted procedure to reconstruct the ACL using a bone-tendon-bone graft, such as a patellar tendon. The surgery employs accurate graft placement, tensioning, and fixation, which allows the therapist the opportunity to utilize immediate motion and weight bearing, in addition to strengthening exercises. This paper attempts to explain the rehabilitation process following ACL reconstruction using current scientific and clinical research. The program is based on the anatomy, biomechanics, and healing process of the knee, joint, and ACL. The clinical implications of this paper are numerous. First, we believe the information will assist clinicians in developing their own programs. Second, the data will assist the reader in understanding the sequential healing process. Finally, this paper documents that immediate aggressive rehabilitation is not deleterious to the ACL graft, and early therapy improves the functional outcome. J Orthop Sports Phys Ther 1992;15(6):279-293.     

Medial portal technique for single-bundle anatomical Anterior Cruciate Ligament (ACL) reconstruction

The aim of the paper is to describe the medial portal technique for anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. Placement of an ACL graft within the anatomical femoral and tibial attachment sites is critical to the success and clinical outcome of ACL reconstruction. Non-anatomical ACL graft placement is the most common technical error leading to recurrent instability following ACL reconstruction. ACL reconstruction has commonly been performed using a transtibial tunnel technique in which the ACL femoral tunnel is drilled through a tibial tunnel positioned in the posterior half of the native ACL tibial attachment site. ACL reconstruction performed using a transtibial tunnel technique often results in a vertical ACL graft, which may fail to control the combined motions of anterior tibial translation and internal tibial rotation which occur during the pivot-shift phenomenon. The inability of a vertically oriented ACL graft to control these combined motions may result in the patient experiencing continued symptoms of instability due to the pivot-shift phenomenon. The medial portal technique in which the ACL femoral tunnel is drilled through an anteromedial or accessory anteromedial portal allows consistent anatomical ACL tunnel placement. This paper describes the advantages of the medial portal technique, indications for the technique, patient positioning, proper portal placement, anatomical femoral and tibial tunnel placement, graft tensioning and fixation.     

Effects of notchplasty and femoral tunnel position on excursion patterns of an anterior cruciate ligament graft

Purpose: Errors in femoral tunnel placement in anterior cruciate ligament (ACL) reconstruction can cause excessive length changes in the graft during knee flexion and extension, resulting in graft elongation during the postoperative period. To improve the accuracy of tunnel placement and to avoid graft impingement, a notchplasty is commonly performed. The purpose of this study was to determine the effects of varying the position of the femoral tunnel and of performing a 2-mm notchplasty of the lateral femoral condyle and roof of the intercondylar notch on excursion patterns of a bone–patellar tendon–bone graft. Type of Study: Biomechanical cadaveric study. Methods: A cylindrical cap of bone, containing the tibial insertion of the ACL, was mechanically isolated in 15 fresh-frozen cadaveric specimens using a coring cutter. The bone cap was attached to an electronic isometer that recorded displacement of the bone cap relative to the tibia as the knee was taken through a 90° range of motion. After native ACL testing, the proximal end of a 10-mm bone–patella tendon–bone graft was fixed within femoral tunnels drilled at the 10-, 11-, and 12-o'clock (or 2-, 1-, and 12-o'clock) positions within the notch. The distal end of the graft was attached to the isometer. Testing was then completed at each tunnel position before and after notchplasty. Results: Before notchplasty, mean graft excursions at the 10- or 2-, 11- or 1-, and 12-o'clock tunnels were not significantly different from the excursions of the native ACL or each other. After a 2-mm notchplasty, mean graft excursions at the 3 tunnel locations were not sigificantly different from each other but were greater than mean graft excursions before notchplasty. After notchplasty, all grafts tightened during knee flexion. Conclusions: Although errors in placement along the arc of the intercondylar notch did not significantly affect graft excursion patterns, the apparent graft tightening with knee flexion that was observed for all 3 tunnel positions after notchplasty suggests that graft forces would increase with knee flexion over this range. This would indicate that as little amount of bone as possible should be removed from the posterior portion of the intercondylar notch in ACL reconstruction.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 4 (April), 2003: pp 340–345     

Quadriceps tendon-patellar bone autograft for anterior cruciate ligament reconstruction: a technical note

The quadriceps tendon autograft can be used for primary and revision anterior cruciate ligament (ACL) reconstruction. Despite several successful clinical reports, graft fixation issues remain, and the ideal technique for fixation continues to be controversial. We present a technique of ACL reconstruction with quadriceps tendon autograft (QTA) using a patellar bone block. The tendon end is fixed in the femoral tunnel and the bone plug in the tibial tunnel using reabsorbable interference screws. The advantages of this technique are related to the increase in stiffness of the graft, the achievement of a more anatomic fixation, and a reduction in synovial fluid leakage.     

Arthroscopic anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft

BACKGROUND: Surgical reconstruction of the anterior cruciate ligament (ACL) is indicated in the ACL-deficient knee with symptomatic instability and multiple ligaments injuries. Bone patellar tendon-bone and the hamstring tendon generally have been used. In the present study, we describe an alternative graft, the quadriceps tendon-patellar bone autograft, by using arthroscopic ACL reconstruction. METHODS: From March of 1996 through March of 1997, a quadriceps tendon-patellar bone autograft was used in 12 patients with ACL injuries. RESULTS: After 15 to 24 months of follow-up, the clinical outcome for those patients with this graft have been encouraging. Ten patients could return to the same or a higher level of preinjury sports activity. According to the International Knee Documentation Committee rating system, 10 of the 12 patients had normal or nearly normal ratings. Recovery of quadriceps muscle strength to 80% of the normal knee was achieved in 11 patients in 1 year. CONCLUSION: The advantages of the quadriceps tendon graft include the following: the graft is larger and stronger than the patellar tendon; morbidity of harvest technique and donor site is less than that of patellar tendon graft; there is little quadriceps inhibition after quadriceps harvest; there is quicker return to sports activities with aggressive rehabilitation. A quadriceps tendon-patellar autograft is a reasonable alternative to ACL reconstruction in patients who are not suitable for either a bone-patellar tendon-bone autograft or a hamstring tendon autograft.     

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.     

Biomechanics and anterior cruciate ligament reconstruction

For years, bioengineers and orthopaedic surgeons have applied the principles of mechanics to gain valuable information about the complex function of the anterior cruciate ligament (ACL). The results of these investigations have provided scientific data for surgeons to improve methods of ACL reconstruction and postoperative rehabilitation. This review paper will present specific examples of how the field of biomechanics has impacted the evolution of ACL research. The anatomy and biomechanics of the ACL as well as the discovery of new tools in ACL-related biomechanical study are first introduced. Some important factors affecting the surgical outcome of ACL reconstruction, including graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing, are then discussed. The scientific basis for the new surgical procedure, i.e., anatomic double bundle ACL reconstruction, designed to regain rotatory stability of the knee, is presented. To conclude, the future role of biomechanics in gaining valuable in-vivo data that can further advance the understanding of the ACL and ACL graft function in order to improve the patient outcome following ACL reconstruction is suggested.     

Quadriceps and patellar tendon ruptures

Ruptures of the quadriceps as well as the patellar tendon occur in low frequency, but cause major functional deficits of the leg. These injuries usually require operative treatment. Acute quadriceps tendon ruptures are treated by suture repair, using heavy sutures guided through bone tunnels in the patella. Chronic defects and neglected cases require a local tendon transfer, either by a quadriceps tendon turn-down or by a V-Y-plasty of the quadriceps tendon. Ruptures of the patellar tendon are treated by suture of the tendon stumps plus an reinforcement procedure protecting the tendon and avoiding secondary patella alta. Patello-tibial fixation may be achieved by a cerclage technique using wire or an autologous tendon strip, alternatively a patello-tibial external fixator can be applied. In chronic and neglected cases, patellar tendon reconstruction is performed with autologous tendon grafts or with soft tissue allografts. The graft must be protected by a patello-tibial fixation for the first weeks.     

The anatomy of the ACL and its importance in ACL reconstruction

The anterior cruciate ligament (ACL) anatomy is very significant if a reconstruction is attempted after its rupture. An anatomic study should have to address, its biomechanical properties, its kinematics, its position and anatomic correlation and its functional properties. In this review, an attempt is made to summarize the most recent and authoritative tendencies as far as the anatomy of the ACL, and its surgical application in its reconstruction are concerned. Also, it is significant to take into account the anatomy as far as the rehabilitation protocol is concerned. Separate placement in the femoral side is known to give better results from transtibial approach. The medial tibial eminence and the intermeniscal ligament may be used as landmarks to guide the correct tunnel placement in anatomic ACL reconstruction. The anatomic centrum of the ACL femoral footprint is 43 % of the proximal-to-distal length of lateral, femoral intercondylar notch wall and femoral socket radius plus 2.5 mm anterior to the posterior articular margin. Some important factors affecting the surgical outcome of ACL reconstruction include graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing. The rehabilitation protocol should come in phases in order to increase range of motion, muscle strength and leg balance, it should protect the graft and weightbearing should come in stages. The cornerstones of such a protocol remain bracing, controlling edema, pain and range of motion. This should be useful and valuable information in achieving full range of motion and stability of the knee postoperatively. In the end, all these advancements will contribute to better patient outcome. Recommendations point toward further experimental work with in vivo and in vitro studies, in order to assist in the development of new surgical procedures that could possibly replicate more closely the natural ACL anatomy and prevent future knee pathology.     

An alternative cruciate reconstruction graft: The central quadriceps tendon

The central quadriceps tendon, above the patella, is thicker and wider than the patella tendon. Using precise technique, one can obtain a tendon graft for cruciate reconstruction with 50% greater mass than a patellar tendon bone-tendonbone graft of similar width. The central quadriceps tendon graft may be harvested by a second surgeon while the first surgeon is simultaneously accomplishing notchplasty and tunnel placement for cruciate ligament reconstruction. Consequently, this cruciate ligament reconstruction graft offers time savings as well as greater tendon volume. The central quadriceps tendon graft is difficult to harvest, with significant risk of entering the suprapatellar pouch and losing knee distension during ACL reconstruction. By careful adherence to the technique described in this article, the surgeon can obtain this reconstruction graft safely. It is important to recognize the anatomic subtleties of the proximal patella, which include a curved proximal surface, dense cortical bone, and closely adherent suprapatellar pouch. Proper technique is of utmost importance in obtaining this tendon graft safely and efficiently.     

Graft failure versus graft fixation in ACL reconstruction: histological and immunohistochemical studies in rabbits

The causes of graft failure after anterior cruciate ligament (ACL) reconstruction are multifactorial including the methods of graft fixation. The purpose of this study was to examine the ACL graft failure in three different methods of graft fixations including interference screw fixation, suture-post fixation and combined interference screw and suture-post fixation. We hypothesized that the fixation method after ACL reconstruction can affect the graft healing in tibial tunnel. Eighteen New Zealand white rabbits were categorized into three groups according to the method of fixation in unilateral ACL reconstruction with long digital extensor autograft. Histological examination demonstrated that the combined fixation and suture-post fixation groups showed significantly better integration between tendon and bone (P = 0.04). In immunohistochemical analysis, the combined fixation and suture-post fixation groups showed significantly higher BMP-2 and VEGF expressions than interference screw (P < 0.01). The tendon–bone healing after ACL reconstruction was affected by the method of graft fixation. Combined fixation with interference screw and suture-post reduced graft-tunnel micromotion and improved the graft healing in tibial tunnel.     

Anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft two-incision technique

Anterior cruciate ligament (ACL) reconstruction can be performed with a variety of techniques. Multiple graft sources for reconstruction are also available. The senior author (JRS) has used an arthroscopically assisted technique with 2 incisions that has achieved consistently good results. One incision is made over the patellar tendon, allowing harvest of the bone-patellar tendon-bone graft and tibial tunnel placement and graft fixation. A second lateral incision is used for femoral tunnel placement and fixation. This method has produced predictably good results and avoids some of the potential complications of endoscopic ACL reconstruction.     

Implant-free ACL reconstruction: a review

Implant-free anterior cruciate ligament (ACL) reconstruction is the fixation of ACL grafts without the need for artificial implants. Our aim was to study the evolution of this technique, review the biomechanical evidence and summarise the results. Implant-free graft fixation for bone patella tendon ACL reconstruction was first described in 1987. This concept of implant-free graft fixation was adapted for hamstring and quadriceps tendons as alternative graft sources. Various biomechanical studies have reported that by adhering to certain technical details, this technique provides comparable fixation strength as conventional ACL fixation. The outcome studies of implant-free ACL reconstruction also report clinical results similar to ACL reconstruction with conventional implants.     

膝关节镜下采用挤压螺钉固定骨-髌腱-骨自体移植重建前交叉韧带

目的　探讨采用关节镜下微创手术的方法重建膝关节前交叉韧带。　方法　在膝关节镜下采用挤压螺钉固定骨 髌腱 (中 1/ 3) 骨复合体自体移植重建前交叉韧带 ,术后 1年以上者 2 0例 ,平均随访时间 1年 5个月。　结果　按关节功能评定标准 ,本组 2 0例中 ,优 13例 ,良 5例 ,可 2例 ,优良率 90 % ;9例术后关节镜观察重建前交叉韧带的形态结构 ,7例塑形改建良好。　结论　关节镜下重建前交叉韧带手术创伤小 ,骨道定位准确、固定牢固 ,可做到等长重建 ,有利于早期康复 ;由于利用了自体骨 髌腱 骨组织 ,重建的韧带经塑形改建后可获得牢固的生物学固定     

Anterior Cruciate Ligament Reconstruction: A New Technique for Achilles Tendon Allograft Preparation

We describe a new technique in Achilles tendon allograft preparation for use in anterior cruciate ligament (ACL) reconstruction that allows for secure bony interference fixation on each side of the joint and aperture fixation for all patients. In addition, preparation of the graft in this manner avoids some problems that are frequently encountered with patellar tendon allografts, including graft tunnel mismatch and limited availability. Previous studies have reported successful results with Achilles tendon allograft use in ACL reconstruction with soft tissue fixation in the tibial tunnel. Bony interference fixation on the tibial side can be achieved by suturing a free bone plug to the tendon end of an Achilles allograft. We use a 9-mm circular oscillating saw to harvest a free 30-mm length bone plug from the remaining calcaneal bone block. This is then sutured directly to the tendon end of a bone-Achilles tendon allograft with the use of No. 1 nonabsorbable suture placed through 3 equally spaced drill holes in the free bone plug. Tendon length between the bone plugs can be individually set for each patient at a distance equivalent to the length of the native ACL (intra-articular distance between the femoral and tibial tunnels). After graft passage, the construct is tensioned and secured with interference screws, similar to a traditional bone–patellar tendon–bone graft. The senior author (S.G.) has performed 40 procedures with excellent results and reports no cases of tibial fixation failure. Biomechanical and long-term follow-up studies are in progress.