| | Scientific justification and technique for anterior cruciate ligament reconstruction using autogenous and allogeneic soft-tissue grafts
Arthroscopic reconstruction of the torn anterior cruciate ligament (ACL) of the knee is a widely accepted treatment for patients with symptomatic knee instability. The orthopedic surgeon makes several decisions, including source of graft tissue, tunnel placement technique, and type of femoral and tibial fixation device. We present the scientific justification for the use of the double-looped, semitendinosus and gracilis (DLSTG) autograft and single-looped anterior tibialis and posterior tibialis allograft for reconstructing a torn ACL. We discuss the rationale for placing the tibial tunnel with a guide that references the intercondylar roof and drills the guide pin with the knee in full extension. The advantages of drilling the femoral tunnel through the tibial tunnel using the so-called trans-tibial technique are outlined. Because tendon healing is slower than bone healing, the need for strong, stiff fixation methods that resist slippage and are applied at the end of the tunnels to promote tendon tunnel healing are presented. A patient-controlled program that safely and aggressively rehabilitates the knee without a brace and returns the patient to unrestricted sports and work activities at 4 months is outlined. Finally, the key surgical steps are described for surgeons interested in reconstructing the knee with a soft-tissue graft and using brace-free aggressive rehabilitation.
Source of graft tissue  The surgeon must decide where to obtain the tendons for constructing a graft when planning an ACL reconstruction. The autogenous sources include the semitendinosis and gracilis (hamstring) tendons, patellar tendon, and quadriceps tendon. The allogeneic sources include the tibialis tendon (anterior and posterior) and hamstring tendons, as well as bone plug grafts, such as the patellar tendon and Achilles tendon. In this section, we discuss our preference for using a soft-tissue anterior cruciate ligament graft and the principles for constructing them to maximize structural properties at implantation. Autogenous graft tissue We prefer the autogenous double-looped semitendinosis and gracilis because of its superior strength and stiffness, reciprocal tensile behavior, biologic incorporation, and low morbidity. The DLSTG graft with the four strands equally tensioned is the strongest (4304–4590 N) and stiffest (861–954 N/mm) autogenous graft [1], [2]. The strands of the DLSTG graft must be aligned in parallel because braiding or weaving ruins the structural properties by markedly decreasing strength (54%) and stiffness (84%) [3]. The anterior and posterior strands of the DLSTG graft exhibit reciprocal tensile behavior similar to the anteromedial and posterolateral bands of the normal ACL when fixed over a rigid metal post inside a femoral tunnel compacted with bone [4]. The biologic incorporation of a DLSTG graft is rapid since the tendons do not undergo necrosis, and viability does not depend on revascularization [5], [6]. The morbidity from harvesting the DLSTG is minimal because flexion strength returns completely, the hamstring tendons regenerate, and extensor mechanism problems, such as anterior knee pain, kneeling pain, quadriceps weakness, patellar fracture, and patellar tendon rupture, are avoided [7], [8], [9], [10], [11], [12], [13]. These mechanical and biological characteristics of hamstring grafts are consistent with clinical results showing that the DLSTG graft is as effective as an autogenous patellar bone-tendon-bone graft for restoring stability and function in the knee with a torn ACL [14], [15]. Allograft tissue When an allograft is indicated, we prefer to use soft tissue, such as a single loop of anterior tibialis tendon, a single loop of posterior tibialis tendon, and a DLSTG graft, instead of bone plug grafts, such as the patellar tendon and Achilles tendon. One advantage of the soft-tissue allograft is that there is no bone plug. Preparation of allograft bone into a plug is time-consuming. Furthermore, the allograft bone plug is slow to incorporate, weakens with age, and when it extends beyond the tunnel, compromises fixation with an interference screw [16]. Another advantage of soft-tissue allografts is that they are stronger and stiffer than a patellar bone-tendon-bone graft because the cross-sectional area of soft-tissue allografts is larger [17]. A third advantage is that they are more readily available because each donor provides six soft-tissue grafts but only four bone plug grafts. We especially like to use a soft-tissue allograft in revision surgery and as a primary graft when harvesting the hamstring tendons might be difficult, such as in an obese patient or when a surgical scar exists on the medial side of the knee. The increased use of the soft-tissue allograft is fostered by improvements in fixation, particularly low-profile devices that are strong, stiff, and resist slippage and that promote tendon tunnel healing by fixing the graft at the end of the tunnel [2], [18], [19]. Tunnel placement The surgeon must choose from three techniques for placing the femoral tunnel. The two-incision technique drills the femoral tunnel independent of the tibial tunnel by placing the femoral guide and drilling through a second incision made on the anterolateral thigh. The disadvantage of the two-incision technique is that the second incision weakens knee flexion and extension [20]. The transportal technique drills the femoral tunnel independent of the tibial tunnel by inserting an over-the-top femoral aimer through the anteromedial portal. The disadvantage of the transportal technique is that the posterior wall of the femoral tunnel can blow out unless the knee is flexed past 100° [21]. The transtibial technique drills the femoral tunnel through the tibial tunnel. The advantage of the transtibial technique is that correct placement of the tibial tunnel in the sagittal and coronal planes ensures correct placement of the femoral tunnel [22], [23]. In this section, we present our guidelines for placing the tibial and femoral tunnels using the transtibial technique. These guidelines center the tibial tunnel between the tibial spines, prevent impingement of the graft against the intercondylar roof in extension, prevent impingement of the graft against the PCL in flexion, and place the femoral tunnel so that the tension pattern of the graft is similar to the intact ACL. Tibial tunnel guidelines—sagittal plane The position of the tibial tunnel in the sagittal plane determines whether the graft impinges against the roof in knee extension, which ultimately determines whether the knee regains extension and retains stability. A tibial tunnel anterior to the intercondylar roof with the knee in extension positions the graft to impinge (ie, abrade) against the roof during extension. Moderate roof impingement causes effusions, anterior knee pain, and extension loss, while severe roof impingement causes increased anterior laxity and graft failure from abrasion [24], [25], [26], [27], [28]. We prefer to center the tibial tunnel 4 to 5 mm posterior and parallel to the intercondylar roof with the knee in extension to minimize the complications of extension loss and increased anterior laxity. The PCL-referencing and point-and-shoot guides reference soft tissues, drill the guide pin with the knee in flexion, and therefore, cannot account for the wide variability in roof angle and knee extension among our patients [29], [30]. These guides do not place the tibial tunnel posterior, parallel, and close to the intercondylar roof. The PCL-referencing guide with a 7 mm offset places the tibial tunnel too posterior (8.3 mm), which has prompted a recommendation to increase the offset to 10 to 11 mm to reduce the tendency for posterior placement [31], [32]. The point-and-shoot guide places the tibial tunnel too anterior because the selection of the tibial landmark is left to the surgeon's judgment and does not rely on bony landmarks. Our own experience with the point-and-shoot guide resulted in extension loss and increased anterior laxity [24], [25], [26]. We use a tibial guide that references the intercondylar roof to control the sagittal position of the tibial tunnel for several reasons. One is that the guide is accurate when used by different surgeons [22]. Another is that the guide simultaneously accounts for roof angle (23°–60°) and knee extension (−20°–5°), both of which vary widely among our patients [29], [30]. The guide customizes the sagittal position of the tibial tunnel to the specific combination of roof angle and extension in the reconstructed knee, thereby avoiding excessive anterior or posterior tunnel placement. A third reason is that roof impingement can be detected by inserting an impingement rod through the tibial tunnel with the knee in extension because the tibial tunnel is aligned parallel to the intercondylar roof. The benefit of using a tibial guide that references the intercondylar roof is that it improves knee extension and stability. Tibial tunnel guidelines—coronal plane The medial-lateral placement of the tibial tunnel in the coronal plane determines whether the knee regains flexion and the degree of synovitis. Placing a portion of the tibial tunnel medial to the medial tibial spine causes flexion loss [28]. Placing a portion of the tibial tunnel lateral to the lateral tibial spine causes synovitis [27]. The bullet tip of the tibial guide that references the intercondylar roof centers the tibial tunnel between the medial and lateral tibial spines [22], [33]. Containment of the tip between the lateral femoral condyle and posterior cruciate ligament during drilling of the tibial guide pin prevents the tunnel from drifting beyond the boundary of the tibial spines. We prefer to center the tibial tunnel between the medial and lateral tibial spines to minimize the complications of flexion loss and synovitis. With the transtibial technique, the angle of the tibial tunnel in the coronal plane determines whether the graft impinges against the posterior cruciate ligament in flexion, which ultimately determines whether the knee regains flexion and the degree of stability. A tibial tunnel with an angle greater than 75° with respect to the medial joint line places the femoral tunnel closer to 12 o'clock, which positions the graft to impinge against the posterior cruciate ligament during knee flexion. Posterior cruciate ligament impingement causes flexion loss and increased anterior laxity because of a tension increase in the graft from wrapping around the posterior cruciate ligament [23]. We prefer to place the tibial tunnel at an angle less than 75° in the coronal plane to minimize the complications of flexion loss and increased anterior laxity. For several reasons, we use an alignment rod inserted into the handle of a tibial guide that references the intercondylar roof to control the coronal angle. One reason is that the use of an alignment rod places the angle more accurately than the use of a freehand technique [22]. Aligning the rod parallel to the tibial joint line and perpendicular to the long axis of the tibia places the tibial tunnel at an angle of 70° [22]. Another reason is that the tensile behavior of the graft is similar to the intact ACL when the tibial tunnel is placed with this guide and the femoral tunnel is drilled through the tibial tunnel [23]. Using a coronal alignment rod inserted into the handle of a tibial guide that references the intercondylar roof improves flexion and stability. Femoral tunnel With the transtibial technique, the position of the femoral tunnel depends on the position of the tibial tunnel in the sagittal and coronal planes because the femoral tunnel is drilled through the tibial tunnel [22]. Because the femoral tunnel is drilled through the tibial tunnel, correct placement of the tibial tunnel in the sagittal and coronal planes ensures correct placement of the femoral tunnel. We use an over-the-top femoral aimer with an offset specific for the tunnel diameter so the back wall of the femoral tunnel is not greater than 1 mm thick. Drilling a femoral tunnel with a 1 mm thick back wall along the axis of a correctly placed tibial tunnel produces a tensile behavior of the graft similar to the intact ACL [23]. Graft fixation The surgeon can choose from a variety of fixation methods; however, not all methods produce the same stability and clinical outcome, especially in females. For example, interference screw fixation of a four-strand hamstring graft provides less stability in females than in males because the cancellous bone in the tibia is softer in females than in males [34]. Endobutton and suture tied to a post fixation of a four-strand hamstring graft provides poorer clinical outcome in females than in males [35]. In contrast, females and males have similar stability and clinical outcome with more secure fixation methods that include looping the graft around a post, WasherLoc, soft-tissue washer, and double staples [22], [33], [36]. In this section, we try to explain the clinical differences by examining the fixation method's effect on the rate of healing of a tendon in a tunnel and the structural properties of slippage, stiffness, and failure. Tunnel healing Tunnel healing is slower for a tendon graft than a bone plug graft [37], [38]. The recognition that healing of a tendon in a tunnel is slow has led to the adoption of several strategies that promote early tendon tunnel healing. One strategy is to maximize the contact area between the tendon and bone tunnel. Maximizing contact area is accomplished two ways: (1) by increasing the length of the tunnel and (2) by applying the fixation device to the end of the tunnel rather than in the tunnel along side the graft (interference screw) [19], [39]. Doubling the length of the tunnel increases strength 72% at 6 weeks [39]. Applying the fixation device at the end of the tunnel (WasherLoc) increases stiffness 136%, whereas applying the fixation device inside the tunnel (bioresorbable interference screw) decreases strength 63% and decreases stiffness 40% at 4 weeks [19]. Another strategy is to maximize the tightness of fit of the tendon in the tunnel [39]. Maximizing the tightness of fit is accomplished two ways: (1) by drilling a snug tunnel and (2) by compacting bone graft between the tendon and tunnel wall [39]. Drilling a tunnel that matches the diameter of the tendon graft (4.2 mm) rather than 43% looser (6 mm) increases strength 32% at 6 weeks [39]. Compacting bone graft around a tendon graft increases the initial stiffness 41 N/mm, fills voids between the tendon tunnel wall, and might promote tendon tunnel healing [2]. The combination of using a long and snug tunnel, applying the fixation method at the end of the tunnel, and compacting bone graft increases strength and stiffness during the first 4 to 6 weeks after implantation by promoting tendon tunnel healing. The placement of an interference screw along side the tendon “shortens” the tunnel by decreasing the contact area available for healing and “interferes” with early tendon tunnel healing. Structural properties Patients with a low-morbidity, soft-tissue graft use their knee early and more vigorously than patients with a high-morbidity, patellar-tendon graft [40]. This early use in conjunction with slow healing of the tendon to the tunnel increases the potential for fixation failure [38]. Aggressive rehabilitation with a soft-tissue graft requires femoral and tibial fixation methods that resist slippage, are stiff and strong, and do not interfere with tendon tunnel healing. There are few fixation methods that meet the requirements for aggressive rehabilitation. Slippage under cyclic load is excessive with sutures sewn to the tendon graft and tied to a post, double staples, and a single soft-tissue ligament washer [18], [41]. Stiffness is less than the intact ACL with the Endobutton, sutures tied to a post, and a single soft-tissue ligament washer [2], [18]. Low-stiffness constructs require higher graft tensioning to restore stability to the knee. The increased graft tensioning may increase risk for fixation failure and deteriorates the biomechanical properties of the graft [42]. The strength of suture and the interference screw fixation is less than the estimated daily tension of an anterior cruciate ligament graft during intensive rehabilitation (500 N) [2], [18], [41], [43]. The three fixation methods that meet the requirements for rehabilitation and do not interfere with tendon tunnel healing are looping the graft around a metal post (Bone Mulch Screw [Arthrotek, Inc., Warsaw, IN]), WasherLoc (Arthrotek, Inc.), and two soft-tissue washers applied in tandem [2], [18], [33], [36]. Aggressive rehabilitation The last decision a surgeon needs to make when using a soft-tissue graft is whether to use a brace and aggressively rehabilitate the patient. Our clinical experience spanning 11 years is that bracing is not needed after reconstruction of a DLSTG graft with secure fixation and proper tunnel placement [22], [33], [36]. We found no prospective, randomized studies that evaluated the effectiveness of brace use with a soft-tissue graft. Several prospective, randomized studies with a patellar tendon graft show no clinical benefit from wearing a brace at 1 and 2 years postoperatively [44], [45], [46], [47], [48]. Furthermore, bracing is associated with more atrophy and slower running and turning [49], [50]. Prospective, randomized studies are needed to determine whether bracing is effective with less secure methods of fixing a tendon graft, such as sutures and interference screws. The rehabilitation program we prefer for an autogenous DLSTG graft fixed securely is patient-controlled and aggressive. Patients are discharged the day of surgery with a soft dressing and bearing weight as tolerated. At 2 weeks, crutches are discarded if they are still being used, and bicycling is started. At 4 weeks, low-weight, high-repetition strengthening exercises are permitted using machines and free weights. At 8 weeks, jogging is allowed. At 12 weeks, agility activities are taught. At 16 weeks, a comprehensive evaluation is performed, including arthrometric measurements, radiographs, and single-leg hop test. If motion is full, pain and effusion are absent, laxity is within 3 mm of the intact knee using the maximum manual test, the tunnels are properly placed without roof and PCL impingement, and the distance jumped is at least 85% of the contralateral leg, the patient is cleared to return to sport. We have not observed any increase in anterior laxity between 4 months and 2 years using this surgical technique and rehabilitation protocol, which indicates that resumption of sport at 4 months is safe [33], [36]. Surgical technique Harvest the tendons Use a tourniquet to prevent bleeding from interfering with tendon harvest. Once experience is gained, the harvest can be performed without a tourniquet. Center a 3 to 4 cm vertical incision three fingerbreadths distal to the medial joint line. Place the incision a few millimeters posterior to the midpoint of the anteromedial flair of the tibia. Move the incision more posterior in the patient with a large or obese leg. Posterior placement extends the reach of the dissecting index finger into the popliteal fossa. Sweep the subcutaneous tissue off the sartorius fascia. Palpate the gracilis tendon at the posterior edge of the tibia through the overlying sartorius. Cut the sartorius in line with the gracilis tendon. Flex the knee to relax the hamstring tendons. Insert the index finger in the plane between the medial collateral ligament and gracilis and semitendinosus and free adhesions from the insertion of the tendons into the popliteal space. Use a right-angle clamp (Arthrotek, Inc.) and loop a 0.5 inch Penrose drain around the gracilis tendon. Identify and cut any fascial slips to the sartorius or medial gastrocnemius. Free the gracilis tendon from muscle using an open-ended tendon stripper. Leave the insertion intact. Use a right-angle clamp and loop a Penrose drain around the semitendinosus tendon, which lies distal and parallel to the gracilis tendon. Identify and cut any fascial slips (there may be up to five) arising from the inferior border of the tendon. Confirm all the slips are detached by pulling the tendon and noting an increase excursion and dimpling of the skin in the popliteal fossa. Free the semitendinosus tendon from muscle with an open-ended tendon stripper. Leave the insertion intact. Prepare the graft Leaving the insertion intact simplifies graft preparation because only one end of the tendon needs to be sewn. If a skilled assistant is available, the tendons can be detached and prepared on the back table. Peel the muscle off each tendon using curved Mayo scissors or periosteal elevator. Grasp the tip of the tendon with an Allis clamp. Color code the tendons by using an undyed suture for the gracilis tendon and a violet suture for the semitendinosus (1 vicryl, 36 inches in length). Create a “Chinese finger trap” or “Roman sandal” effect for each tendon using a whipstitch (Fig. 1). Begin sewing at the tip and catch four fifths of the cross-sectional area of the tendon with each throw. Place 4 to 5 throws spaced at 7 to 10 mm intervals until 4 to 5 cm of tendon is sewn. Sew back down the tendon to the tip by crossing over each previous throw at a right angle. Each throw should be in the same direction—don't reverse them. Tension the stitch to taper the graft. Form the DLSTG graft by looping the middle of each tendon over a suture. Use sizing sleeves to determine the diameter of the graft. The diameter of the smallest sleeve that freely passes over the graft is the diameter used to drill the tibial and femoral tunnels. Place the portals Place a transpatellar tendon portal in the lateral one third of the patella tendon. The transpatellar portal provides a clearer view than an anterolateral portal of the entire length of the femoral tunnel. Place the medial portal against the medial border of the patella tendon, which allows the tibial guide that references the intercondylar roof to center in the notch. Place the tibial tunnel Excise the stump of the torn ACL and expose the lateral edge of the posterior cruciate ligament by shaving away overlying synovium. Insert a 70° curved curette (Arthrotek, Inc.) in the over-the-top position and remove the ACL origin from the back of the femur. Removal of the ACL origin rests the femoral aimer on bone rather than on soft tissue and prevents blowout of the back wall of the femoral tunnel. Insert the tip of the tibial guide that references the intercondylar roof through the medial portal (Howell Tibial Guide, Arthrotek, Inc.). Keep the dorsal bump on the guide inside the notch while extending the knee. Place the foot on a Mayo stand and adjust the height of the stand to maintain the knee in maximum extension. Grasp the handle of the guide with the index and ring fingers. Rotate the handle anteriorly and superiorly in the sagittal plane, which abuts the tip of the guide against the tibia and the dorsal bump of the guide against the intercondylar roof. During rotation of the handle, the hypothenar area of the hand gently pushes the patella posterior against the femur, locking the guide in place. Insert an alignment rod into the proximal hole in the handle from the lateral side of the guide. Rotate the guide in the coronal plane until the alignment rod parallels the tibial joint line and is perpendicular to the long axis of the tibia (Fig. 2A, B). Aligning the rod in the coronal plane places the tibial tunnel at 70° with respect to the medial joint line in the coronal plane. Insert and lock the drill sleeve in the tibial guide. Drill a 2.4 mm drill-tipped guide pin through the tibia. Tap the guide pin into the joint and assess the position of the pin. The guide pin should bisect the tibial spines and enter the notch lateral to the PCL. Drill the tibial tunnel. Perform a roof or wallplasty until an impingement rod, the same diameter as the graft, can be inserted freely into the notch through the tibial tunnel with the knee in maximum extension (Fig. 3). Prepare the counterbore for the WasherLoc Use electrocautery to expose a thumbnail-sized area of soft tissue overlying the bone at the distal end of the tibial tunnel. Insert the counterbore guide into the tibial tunnel as far as possible. Aim the guide toward the fibula by rotating the guide posteromedial. Create a pilot hole in the posterior wall of the tibial tunnel by impacting the awl through the guide (Fig. 4). Insert the tip of the counterbore reamer in the pilot hole, aim toward the fibula, and align the cutting surface parallel to the posterolateral wall of the tibial tunnel. Gently ream until the counterbore is flush with the posterolateral wall of the tibial tunnel (Fig. 5). Place the femoral tunnel Correct placement of the femoral tunnel is automatic when the tunnel is drilled through a tibial tunnel, which is posterior and parallel to the intercondylar roof in the sagittal plane, and between the tibial spines at an angle of 70° in the coronal plane. Insert a size-specific femoral aimer through the tibial tunnel (Arthrotek, Inc.). Extend the knee until the tip of the aimer is hooked in the over-the-top position. Let gravity flex the knee until the guide locks in place (Fig. 6). Rotate the femoral aimer away from the PCL and drill the guide pin. Use an acorn-tip reamer and drill a 30 mm in length femoral tunnel. Insert the Bone Mulch Screw Insert the U-guide (Arthrotek, Inc.) through the tibial tunnel and into the femoral tunnel. Insert the drill sleeve and orient the U-guide medial-lateral in the coronal plane. Advance the bullet to mark the skin. Make a 12 mm long incision through skin, iliotibial band, to bone. Remove the drill sleeve and use the tip to dissect the soft tissues down to bone. Reinsert the drill sleeve and measure the length of the Bone Mulch Screw by reading the screw sizes on the sleeve from the inner edge of the U-guide (Fig. 7). When the length is between screw sizes, use the shorter screw. Drill a guide pin across the lateral condyle until it strikes the U-guide. Remove the U-guide. Insert the 30° arthroscope through the transpatellar or medial portal and view up the femoral tunnel. Tap the guide pin across the femoral tunnel and into the medial wall of the femoral tunnel. Use an 8 mm in diameter cannulated reamer in hard bone and a 7 mm reamer in soft bone to drill the tunnel for the Bone Mulch Screw. Place a sizing sleeve around the reamer to collect bone mulch. Stop reaming when the medial wall of the femoral tunnel is reached (Fig. 8). Screw in the Bone Mulch Screw until the tip of the screw crosses the center of the tunnel. Pass a loop of suture in a passer through the tibial tunnel and into the femoral tunnel. Loop the suture around the post of the Bone Mulch Screw. Advance the tip of the Bone Mulch Screw until the stepdown tip is in the medial wall (Fig. 9). Withdraw the passer outside the tibial without twisting. Clamp the anterior suture to the drape. Pass and tension the graft Tie the posterior limb of the suture to the sutures sewn to each tendon. Pull on the anterior suture and draw the graft around the post of the Bone Mulch Screw. Tension each tendon and tie the two sutures together to form a closed loop because the tendon was left intact. Insert a metal rod into the loop, tension the graft, and cycle the knee 20 to 30 times. Judge the graft excursion in and out of the tibial tunnel during flexion of the knee. Typically the graft moves 1 to 2 mm out of the tibial tunnel from 0° to 30° of flexion and remains isometric during further flexion. Position the knee in full extension by placing the heel on an adjustable Mayo stand. Instruct an assistant to tension the graft by pulling on the metal rod inserted in the loop of suture. The four strands are equally tensioned, which maximizes strength and stiffness of the graft. Insert the WasherLoc Select a 16 mm WasherLoc for a 7 to 8 mm in diameter graft and an 18 mm WasherLoc for a 9 to 10 mm in diameter graft. Thread the awl into the drill guide and screw the drill guide on the WasherLoc. While maintaining tension on the graft, use a right-angle clamp to separate the four strands into two groups. Insert the awl between the two groups and then into the previously made pilot hole in the posterior wall of the tibial tunnel. Use the right-angle clamp to maneuver the four strands inside the four large peripheral spikes. Orient the drill guide toward the fibula and, with a mallet, strike the WasherLoc into the tibia (Fig. 10). Remove the awl and insert a 3.2 mm drill into the drill guide and drill through the lateral cortex. Remove the drill guide and measure the length with a depth gage. Select a cancellous screw of the correct length and compress the WasherLoc against the graft (Fig. 11). Assess stability and bone graft the tunnels Perform a Lachman test. Palpate the graft and check tension with a nerve hook probe. Compact bone mulch into the femoral tunnel through the Bone Mulch Screw using a sleeve that seats into the head of the bone mulch screw and the compaction rod (Fig. 12). Compact bone mulch into the femoral tunnel filling any voids. Compact the wallplasty fragments and any remaining bone mulch into the tibial tunnel anterior to the graft. Close the wound, inject local anesthetic, and apply a soft compression dressing. Summary The DLSTG is the strongest and stiffest autogenous graft source available for reconstruction of the torn anterior cruciate ligament. Harvest morbidity is low compared with other autogenous graft sources, such as the patellar bone-tendon-bone graft. Soft-tissue allografts provide an excellent alternative for patients requiring revision surgery or for patients who want to avoid any morbidity associated with autogenous graft harvest. Successful use of any soft-tissue graft source, however, relies on precise placement of the tibial and femoral tunnels to prevent roof and PCL impingement and to restore tensile behavior in the graft tissue similar to the native ACL. The use of high-strength, high-stiffness fixation devices that secure the graft at the end of the tunnel promote tendon tunnel healing, restore stability without high graft tensioning, and allow safe, aggressive rehabilitation. The Bone Mulch Screw/WasherLoc screw system provides the surgeon with a consistent, reproducible technique that restores stability and function to the ACL-deficient knee using a soft-tissue graft in both males and females. 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a Uniformed Services, University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA b Department of Orthopedic Surgery, Malcolm Grow Medical Center, Andrews Air Force Base, MD, USA c Department of Mechanical and Aeronautical Engineering, University of California at Davis, Davis, CA 95616, USA  Corresponding author. 89MSGS/SGCXO, Department of Orthopedic Surgery, 1050 W. Perimeter Road, Andrews AFB, MD 20762
PII: S0030-5898(02)00029-9 doi:10.1016/S0030-5898(02)00029-9 © 2003 Elsevier Science (USA). All rights reserved. | |
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