- Email: [email protected]
ACL reconstruction with hamstring tendon
Orthop Clin N Am 34 (2003) 9 – 18
ACL reconstruction with hamstring tendon Leo Chen, MDa,b,*, Vernon Cooley, MDa,b, Thomas Rosenberg, MDa,b a
The Orthopedic Specialty Hospital, 5848 South 300 East, Salt Lake City, UT 84107, USA b Rosenberg-Cooley Clinic, 1820 Sidewinder Drive, Park City, UT 84098, USA
Anterior cruciate ligament (ACL) reconstruction has become the standard of care for ACL injuries in the active patient. Autograft reconstructions are more reliable than synthetic or allograft reconstructions. Both patellar tendon and hamstring tendon autografts are widely accepted graft options. Hamstring tendon grafts, specifically the quadrupled semitendinosus (ST) tendon, are excellent choices given their biomechanical properties, low harvest morbidity, and minimal complication profile.
Graft selection Graft selection is the cornerstone upon which optimal intra-articular ACL reconstruction is built. Graft sources include most commonly synthetic ligaments, allograft or cadaveric tissue, and autograft sources. Synthetic grafts have three main advantages: (1) strength of the graft, (2) absence of graft site morbidity, and (3) virtually endless supply. While some interest in synthetic ligaments continues, prosthetic failure, persistent effusions, late infections, excessive cost and a high reoperation rate make synthetic ligaments unattractive presently. Allografts also are abundantly supplied through a tissue bank, have no donor site morbidity, and allow shorter operating times. A huge interest in allograft reconstruction during the 1980s and early 1990s now appears to be waning as a result of late failures beyond 2 years. Allografts incorporate and remodel at slower rates than autografts. Malek and DeLuca
* Corresponding author. Rosenberg-Cooley Clinic, 1820 Sidewinder Drive, Park City, UT 84098. E-mail address: [email protected] (L. Chen).
have reported a high failure rate after 2 years using freeze-dried allografts [1]. Animal experimentation using allograft reconstruction has been disappointing as reported by Jackson et al and Sabiston et al [2,3]. A poorly understood immune response to allograft tissue, the potential for disease transmission, and quality control of the sources remain serious issues that discourage their use. Intra-articular ACL reconstruction using autografts is the gold standard for the foreseeable future. Since the 1980s, the endoscopic technique for reconstruction has reduced the associated surgical morbidity in the early postoperative course. Patellar bone-tendon-bone (BTB) or hamstring constructs are most commonly considered. Graft site morbidity, graft strength, graft fixation, practical considerations, and clinical results are important issues in determining the optimal graft.
Rationale for semitendinosus autograft Graft site morbidity All autologous graft choices have associated donor site morbidity. Many studies have demonstrated that hamstring grafts have fewer problems with anterior knee pain, quadriceps muscle deficits, and loss of extension compared with patellar BTB autografts. In reviewing BTB reconstructions at one year, Sachs et al reported a flexion contracture incidence of 24% of their patients, patellofemoral pain in 19% of their patients, and quadriceps weakness in 65% of their patients [4]. Bartlett reviewed the morbidity of central one-third patellar BTB graft harvest from the contralateral normal knee in patients requiring revision ACL reconstruction [5]. He found quad-
0030-5898/03/$ – see front matter D 2003, Elsevier Science (USA). All rights reserved. PII: S 0 0 3 0 - 5 8 9 8 ( 0 2 ) 0 0 0 1 6 - 0
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L. Chen et al / Orthop Clin N Am 34 (2003) 9–18
riceps deficits of from 15 to 20% at 6 months, a time when many athletes may return to sports. Rosenberg et al reviewed patients at 18 months after BTB reconstruction and identified an average quadriceps muscle deficit of 18%, as well as functional deficits, such as a diminished mean vertical hop of 4 cm [6]. Devastating complications have been associated with BTB reconstruction, such as patellar fracture, patellar tendon rupture, patellar dislocation, and patellar entrapment syndrome. Differences also exist between harvesting the semitendinosus and gracilis tendons versus the semitendinosus tendon alone. Lipscomb et al have reported small reductions in hamstring torque when using a combined semitendinosus and gracilis (STG) graft [7]. However, there were no differences in hamstring strength if only the semitendinosus was harvested. Yasuda et al reported a 19% decrease in hamstring strength compared with the uninvolved leg when the STG was used for reconstruction [8]. Cooley et al reported isokinetic hamstring deficits of less than 3% with singular harvest of the semitendinosus tendon for reconstruction [9]. In summary, semitendinosus harvest does not contribute significantly to the surgical risks of residual anterior knee pain, quadriceps weakness, and patellar entrapment syndrome. Surgeons who have commonly used both BTB and hamstring constructs recognize reduced morbidity with hamstring grafts. Graft strength Noyes et al reported that a 14 mm BTB graft represented 168% of ACL strength [10]. Therefore, a 9 or 10 mm BTB graft would represent approximately 120% of ACL strength. Noyes reported semitendinosus represents 70% of ACL strength. Assuming that doubling the graft produces equal tension in both limbs, a doubled semitendinosus graft would represent 140% of ACL strength, and a quadrupled construct might exceed 250% of ACL strength. Using a biomechanical cadaveric model, Hamner et al confirmed that a doubled semitendinosus construct has tensile strength over twice its initial strength [11]. In addition, their four-strand hamstring constructs were stronger than any of the 10 mm patellar ligament grafts described previously. The cross-sectional area of a 9 mm quadrupled semitendinosus autograft is between 60 mm2 and 70 mm2 compared with only 40 mm2 for a 10 mm BTB autograft. Compared with the STG graft, the average quadrupled semitendinosus (QST) autograft is larger in diameter and has a larger cross-sectional area. Thus, the QST has more surface area for tendon-
to-bone healing and is a stronger graft. The tubular shape of the QST allows for excellent graft-tunnel conformity, preventing tunnel widening. In addition, this larger graft often enables the surgeon to use a double- socket technique on the femoral side, allowing the ACL graft to be spread out over the femoral ACL footprint. Woo and Adams emphasize the importance of linear stiffness in addition to ultimate load to failure in graft selection [12]. Excessive stiffness may lead to abnormal knee kinematics, greater stress on the fixation, or microfailure of the graft. Noyes et al demonstrated that the stiffness of a semitendinosus graft is nearly equal to that of the anterior cruciate ligament, while BTB grafts are approximately 3.76 times stiffer than the ACL [10]. Thus, four-strand hamstring grafts, created by combining a doubled semitendinosus with doubled gracilis or by using a quadrupled semitendinosus graft, appear stronger than comparable BTB grafts and closer in linear stiffness to the anterior cruciate ligament. Graft fixation Initial graft fixation strength is important to allow early aggressive postoperative rehabilitation. While interference screw fixation has been heralded as the primary advantage of BTB reconstruction, Steiner et al have reported methods of quadrupled construct hamstring graft fixation with equivalent pull-out strength [13]. Corry et al used soft-tissue interference screws for four-strand hamstring tendon autograft and obtained satisfactory results [14]. Some BTB advocates still use sutures and buttons for BTB fixation, and it seems the advantage of interference screws for rigid initial fixation has been exaggerated. Using the EndoButton (Smith and Nephew Endoscopy, Andover, MA) in a cadaveric model, Rowden et al performed biomechanical testing of the quadrupled semitendinosus construct [15]. They found the load to failure with the EndoButton in a QST graft was higher than with interference screw fixation for BTB grafts. Ultimately, permanent biologic fixation of the autograft for stability is the goal. Since Sharpey’s description of the perforating fibers of the osteotendinous junction in the mid-nineteenth century, focus on tendon healing to bone has been intense. The literature contains many animal studies demonstrating soft-tissue graft healing to bone. Rodeo et al studied tendon-to-bone healing in a dog model, which revealed a steady progression in tendon-to-bone pull-out strength from 2 weeks to 6 months after surgery [16]. Fixation failure occurred before 8 weeks and graft failure thereafter. Sharpey-like fibers were
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noted at the bone interface in 8-week specimens. By 8 to 12 weeks, the tendon-bone interface closely resembled the normal insertion. Importantly, tendonto-bone healing may be less optimal for patellar tendon grafts that do not fill the tibial tunnel. ‘‘Windshield wipering’’ of the smaller patellar tendon graft and synovial fluid ingress can be anticipated. The patellar tendon grafts have smaller areas of exposed graft in contact with the tibial tunnel to enhance biologic healing and incorporation. Practical considerations Optimal graft size, graft stiffness, graft tissue compatibility, graft positioning, graft-to-tunnel conformity, and the method of postoperative rehabilitation all contribute to biologic healing. While interference screws provide a good initial fixation to BTB, fixation techniques for hamstring grafts also provide sufficient initial stability to allow early range of motion and weight bearing. Hamstring grafts are advantageous because they allow surgical precision and apply to a variety of patient needs. In this regard, quadrupled semitendinosus reconstruction is superior. Once learned, the semitendinosus harvest is quick and simple. Hamstring reconstruction can be undertaken without an overriding fear of patellar entrapment syndrome known to complicate acutely performed BTB reconstruction. The semitendinosus graft is indicated in some cases where a BTB graft would be ill advised. These cases include a skeletally immature patient, a patient (usually female) with a small patellar tendon, a patient with preexisting patellofemoral disease, a revision of failed BTB reconstruction, and augmentation in a reparable native ACL. Athletes who rely on their extensor mechanism, such as bikers, ballet dancers, skiers, and jumpers, often are compromised by a graft selection that insults the extensor mechanism—namely, BTB. Isometric or physiometric placement of the graft on the femur is achieved more readily with quadrupled semitendinosus constructs using the EndoButton. Endoscopic placement of the femoral tunnel for BTB grafts can be suboptimal because the surgeon is fearful of breaking through the posterior cortex of the femur. This is an especially valid consideration in small- to medium-sized patients where the goal of optimal tunnel positioning and maintenance of a strong circumferential bony tunnel wall may be mutually exclusive. With the QST graft, the femoral insertion can be elongated in the axis of the normal ACL footprint for optimal fiber orientation and function, because breakthrough of the posterior cortex does not compromise the fixation.
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Clinical results In the orthopedic literature, there are a growing number of outcome studies following endoscopic ACL reconstruction. In separate prospective series of alternatively treated patients with BTB and STG (quadrupled construct) grafts, Aglietti et al and Marder et al reported equivalent stability in both groups [17,18]. For studies looking specifically at QST, Cooley et al reported an average manual maximum KT1000 (MEDmetric Corporation, San Diego, CA) side-to-side difference of 0 +/ 1.3 mm in a series of patients treated by endoscopic QST reconstruction with at least 5-years’ follow-up [9]. Eriksson et al performed a prospective randomized study looking at unilateral ACL reconstruction with either the BTB grafts and interference screw fixation or QST autografts and EndoButton fixation [19]. Independent observers performed the follow-up investigation at a mean time of 33 months. The same rehabilitation protocol was used for all patients. No significant differences were found between the two groups with respect to functional testing, such as the one-leg hop test, IKDC score, Tegner activity level, and Lysholm score. While prior experience of the surgeon should help determine the best autograft choice for reconstruction, it appears that no single choice is optimally applied to a broad spectrum of patients who have variable risk factors and postoperative priorities. The reduced morbidity, enhanced connective tissue strength, and versatility of the quadrupled hamstring construct are important potential advantages to consider. Initial fixation strength of bone-tendon-bone by the use of interference screws and quick bone-to-bone healing remain important considerations for its use. Optimal results with either graft choice depend not only on the character of the graft, but also on precise surgical technique, which requires physiometric positioning and careful but aggressive postoperative rehabilitation. In the future, surgeons likely will need to be familiar with both autograft choices and their specific indications rather than relying solely on one or the other.
Endoscopic technique for quadrupled semitendinosus ACL reconstruction Patient positioning and surgical preparation The procedure is best accomplished using an arthroscopic leg holder and with the foot of the table flexed down completely (Fig. 1). A well-padded tourniquet is placed on the proximal thigh, and the affected leg is placed within the leg holder. The well
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Fig. 1. A tourniquet is on patient’s thigh, and patient’s affected leg is in leg holder. The foot of the operating room table is flexed completely.
leg is abducted, flexed at the hip and knee, and placed in a padded support, to be draped out of the surgical field (Fig. 2). The arthroscopic portion of the procedure may be done without a tourniquet, but the tourniquet is used to improve visualization during semitendinosus graft harvest. Placing the patient’s foot on the surgeon’s thigh controls the involved limb—accurate control of knee flexion is critical throughout the entire procedure. The surgeon sits on a draped rolling stool with full-length surgical gowns to maintain sterile technique (Fig. 3). By rolling forward or backward on a sitting stool, the surgeon is able to carefully control the degree of knee flexion. Semitendinosus graft harvest Semitendinosus harvest is accomplished with the surgeon sitting and the knee in 80° to 90° of flexion. A
Fig. 2. Abducted and flexed at the hip and knee, the patient’s well leg is draped out of the surgical field.
Fig. 3. Surgeon in a full-length gown sits on a draped, rolling stool. With the patient’s foot on the surgeon’s thigh, the surgeon can control the degree of knee flexion.
4 cm to 5 cm longitudinal skin incision is made over the pes tendons beginning 2 cm to 3 cm distal to the joint line and 1 cm to 2 cm medial to the tibial tuberosity. The sartorius aponeurosis is identified using a sponge, and the underlying gracilis tendon and semitendinosus tendon are palpated. The sartorius aponeurosis is incised in line with its fibers distal to the underlying semitendinosus tendon. Using digital palpation, the semitendinosus tendon is isolated where it naturally separates from the gracilis tendon, approximately 5 cm to 8 cm proximal to their tibial insertions. A curved clamp and a small Penrose drain are placed around the semitendinosus tendon for positive identification (Fig. 4). While carefully avoiding injury to the underlying superficial medial collateral ligament, sharp division with a scalpel of the proximal and distal margins of the semitendinosus tibial insertion usually permits the tendon to be digitally ‘‘popped off’’ its insertion, providing an
Fig. 4. Semitendinosus tendon is isolated with curved clamp and Penrose drain for positive identification.
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extra 1 cm to 2 cm of tendon length. A #5 Mersilene (#2 for patients who weigh less than 150 pounds) running whipstitch is placed at five or six levels in the distal tendon to control the free end. While traction is applied to the free end of the tendon using the whipstitch, the deep fascial bands to the medial gastrocnemius fascia can be identified and released with Metzenbaum scissors (Fig. 5). Premature transection of the semitendinosus tendon may occur without release of these fascial attachments. With the knee flexed 70° to 80°, gentle traction is maintained on the distal tendon while a closed-end tendon stripper is advanced proximally in line with the tendon. Commonly, the semitendinosus tendon graft will have a length between 24 and 40 cm. While the graft is transferred to the back table for preparation, inspection of the distal insertion of the superficial medial collateral ligament (MCL) is recommended (Fig. 6). If there is no injury to the MCL that requires surgical attention, the sartorius aponeurosis is then reapproximated with #0 or #1 Vicryl suture. Semitendinosus graft preparation The graft is prepared on the back table by the surgeon or an assistant while the surgeon proceeds with the endoscopic portion of the procedure. Graft preparation is performed on a graft preparation board (Fig. 7). After harvest, the graft is kept moist at all times with a wet sponge to prevent tissue desiccation. Any muscle remaining on the graft is removed with a Cobb periosteal elevator or a metal ruler edge. The proximal end of the graft is thin and may be tubularized with a running baseball stitch using #2-0 or #3-0 Vicryl on a tapered needle. Overall tendon length is measured, and the final quadrupled graft length is calcu-
Fig. 5. The semitendinosus tendon has deep fascial bands to the medial gastrocnemius fascia. Failure to release these bands can lead to premature transection of the graft.
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Fig. 6. The superficial medial collateral ligament is underneath the semitendinosus, which is retracted by the Penrose drain. Inspection of the ligament is recommended to determine whether surgical attention is necessary.
lated by taking one quarter of the overall length. The required minimum graft length is about 22 cm, because a minimum of 15 mm of quadrupled graft is needed within both the tibial and femoral tunnels. However, if the semitendinosus tendon proves too short for use as a quadrupled graft, the gracilis tendon can be harvested, and a doubled semitendinosus and gracilis graft is used. Another option is a tripled semitendinosus graft that maintains the integrity of the gracilis. The semitendinosus tendon is sharply divided in half on the preparation board to create two equallength grafts. A #5 or #2 Mersilene suture on a tapered needle is whipstitched to each of the remaining three free ends of the grafts; holding clamps secure the grafts during suture placement. Then, the two grafts are each doubled over a 6 mm polyester tape to produce a quadrupled construct (Fig. 8). This construct is passed through sizing tubes to determine the graft
Fig. 7. Graft preparation board. Holding clamps secure the graft to facilitate suture placement.
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distal outlet of the notch is best visualized from 45° to 60° of knee flexion, and the proximal outlet at 90°of flexion. The over-the-top position is identified; however, the proximal outlet is not generally expanded. Tunnel preparation
Fig. 8. The two grafts are doubled over polyester tape to create a four-strand construct. Then the quadrupled graft is passed through sizing tubes.
diameter at both its proximal and distal ends. If a femoral double-socket technique will be employed, each graft is measured separately with the sizing tubes. The polyester tape is then placed through the two central holes of the EndoButton, but it is not tied. Alternatively, there is also an EndoButton CL (Smith and Nephew Endoscopy, Andover, MA) with a continuous polyester loop already attached to the EndoButton through the two central holes (Fig. 9). This contstruct eliminates the need for tying knots in the polyester tape. A #5 Ticron suture is placed through the leading EndoButton hole, and a #2 Ticron suture is placed through the trailing hole for either construct. The graft is kept moist wrapped in a wet sponge. Endoscopic preparation A superomedial outflow portal is created and is used initially to inject 30 cc of 0.25% Marcaine with epinephrine solution into the knee joint during graft harvest. The longitudinal anterolateral portal is created 1 cm above the joint line immediately adjacent to the patellar tendon, and the anteromedial portal is created at the same level above the joint line from 5 to 8 mm medial to the patellar tendon. If necessary, the ligamentum mucosum and fat pad are excised to facilitate viewing the intercondylar notch. The ACL stump is debrided partially, leaving a substantial portion to guide tibial tunnel placement. The intercondylar notch is then evaluated. Using arthroscopic curettes, grasping forceps, and a fullradius shaver, a notchplasty is performed, if needed, with its extent determined by individual anatomy. Notchplasty allows improved identification of the femoral attachment site of the native ACL and helps prevent graft impingement after reconstruction. The
First, the tibial tunnel is prepared. The pretibial periosteum is incised longitudinally with electrocautery, beginning at the superior margin of the sartorius insertion and the medial margin of the patellar tendon. This incision is taken 2 cm to 3 cm proximally toward the joint line. Limited subperiosteal elevation is performed with a Cobb elevator at this anteromedial incision. The endoscopic aimer for the tibial tunnel is adjusted to the 45° position, and the guide-tip is positioned intra-articularly through the anteromedial portal. The 45° orientation produces an ovoid intraarticular aperture that more closely approximates the anatomic ACL footprint of the tibia. The guide pin typically is angulated 45° to the anterior cortex of the tibia when viewed laterally placing the tibial tunnel approximately 3.5 cm below the joint line (Fig. 10). A more vertically oriented tibial tunnel may preclude optimal femoral access and produces a more circular, less anatomic aperture in the tibia. The guide-tip is positioned with the tip impaling the posterior fibers of the tibial ACL stump. With optimal guide pin positioning, (1) the guide pin is in the center of the tibial stump; (2) from 5 to 6 mm of clearance exists between the pin and the roof of the notch in full extension; and (3) at 90° of knee flexion, the guide pin is directed just distal to the over-the-top position. A cannulated reamer corresponding to the size of the graft is used to drill the tibial tunnel; the surgeon stops
Fig. 9. The two grafts are looped over an EndoButton CL to produce the quadrupled graft. A #5 Ticron suture is placed through the leading hole, and a #2 Ticron suture through the trailing hole.
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flexion. A calibrated, cannulated, endoscopic reamer sized to match the graft’s proximal diameter is placed manually through the tibial tunnel and abutted against the femur. The intra-articular graft length is estimated from the calibration lines on the reamer. The amount of graft contained within the femoral tunnel (graft insertion length) is determined by taking one half of the remaining graft length after subtracting the intraarticular length from the overall, prepared quadrupled graft length. The femoral tunnel is drilled 5 to 6 mm deeper than the graft insertion length to allow for a ‘‘turning radius’’ of the EndoButton. A long passing pin is advanced through the tibial tunnel and femoral socket, and drilled through the anterolateral cortex of the distal femur. A 4.5 mm cannulated reamer is used to over drill this passing pin through the cortex, producing a femoral passing channel for the EndoButton (Fig. 12). A depth gauge measures the total femoral channel length precisely. Fig. 10. The endoscopic tibial aimer is set at 45° to allow optimal placement of the tibial tunnel and access to the overthe-top position. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
when the reamer just breaks through the intra-articular cortex. Finally, a 5.5 mm synovial resector is placed through the tibial tunnel to remove debris. Next, the femoral tunnel is prepared. A femoral endoscopic aimer with a 3 mm offset is inserted through the tibial tunnel and placed on the over-thetop position (Fig. 11). The femoral guide pin is then inserted at the 11 o’clock position for the right knee (1 o’clock for the left knee) and advanced 2 cm to 3 cm into the femur while maintaining the knee at 90° of
Fig. 11. The endoscopic femoral aimer with a 3 mm offset is placed at the over-the-top position. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
Fig. 12. The femoral tunnel is reamed and measured with a depth gauge. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
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Graft passage and fixation Tying the 6 mm polyester tape at its calculated connector length completes graft preparation. The connector length is determined by subtracting the graft insertion length from the total femoral channel length. The polyester tape is tied with a doubled surgeon’s knot. When using the EndoButton CL, the tape is continuous, and knots do not have to be tied. However, the appropriate length of the continuous loop must be calculated. This length is determined by the difference between the total femoral channel length and the desired graft insertion length. Because the EndoButton CL is available only in 5 mm increments, round up to the larger size if the length falls between two sizes. The graft is passed through the continuous loop and is marked at the graft insertion length with a sterile marking pen. While at least 90° of knee flexion is maintained, a passing pin is placed through the tibial tunnel, femoral socket, and distal thigh, while counter pressure is applied to the thigh with an Army-Navy retractor. The #5 and #2 Ticron sutures are threaded through the eyelet of the passing pin, and the passing pin is extracted proximally, bringing the sutures out through the distal thigh (Fig. 13). The #5 Ticron suture is used as a leading suture to pull the EndoButton and graft construct proximally into the joint while the surgeon controls the slack in the trailing #2 Ticron suture. The graft is viewed endoscopically to ensure the graft marker line is even with the entrance of the femoral socket. The trailing #2 Ticron suture is pulled to flip the EndoButton external to the femoral tunnel, now the #5 and #2 Ticron sutures can toggle the EndoButton (Fig. 14). The
Fig. 14. The EndoButton is flipped by the trailing #2 suture to provide superior femoral fixation. The #5 (upper black arrow) and #2 (lower black arrow) sutures can toggle the EndoButton. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
EndoButton is deployed on the cortex of the distal femur, providing femoral fixation. The graft is pulled firmly distally, confirming the EndoButton has been flipped and secured on the anterolateral cortex of the distal femur. With manual tension applied to the distal graft sutures, the knee is taken through a range of motion to confirm endoscopically the absence of graft impingement. If slight impingement is noted, the notch is slightly enlarged with curettes or an abrader. For tibial fixation, the distal graft sutures are tied over a screw as a post. The proximal tibia is drilled with a 2.5 mm drill bit perpendicular to the anteromedial tibial cortex approximately 1 cm distal to the tibial tunnel. A self-tapping unicortical cancellous fixation screw is advanced incompletely. The graft is tensioned at about 30° of knee flexion, and the matched sutures are secured around the fixation screw (Fig. 15). Then the screw is tightened fully.
Femoral double-socket technique Fig. 13. The #5 and #2 sutures are pulled through the distal thigh, and then the graft is pulled into place with the leading #5 suture.
During passive knee motion, the normal ACL elongates from 2 to 3 mm in the last 20° of extension.
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Postoperative rehabilitation Rehabilitation protocols emphasize early mobilization to maximize return to activity, while adhering to current scientific understanding of graft incorporation and remodeling. Postoperatively, patients remain in a hinged knee brace locked at 20° of knee flexion and kept nonweight bearing for 1 week. After 1 week, patients begin range of motion therapy and progressively bear weight as tolerated. After nearly full range of motion is achieved, patients start strength training, with the emphasis on closed kinetic chain exercises. Rehabilitation progresses from functional activities and to sports-specific training. If muscular strength is adequate, returning to sports usually is permitted after 6 months. Patients are fitted for functional sports braces to aid in proprioceptive feedback during their return to sports. Rehabilitation is altered by concomitant procedures, such as meniscal repair or microfracture. Meniscal repairs usually immobilize patients in a knee brace for 2 to 3 weeks after surgery, and microfracture procedures keep patients nonweight bearing for 4 to 6 weeks. Fig. 15. The graft is tensioned and the distal graft sutures are tied over a fixation screw as a post. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
However, single-bundle ACL reconstructions have difficulty reproducing the physiometric motion of the native ACL, especially in a large patient. A femoral double-socket technique offers the best physiometric approximation. This technique spreads out the grafts along the femoral attachment site along the axis of the native ligament, creating anteromedial and posterolateral fiber bundles that more nearly replicate the physiometric behavior of the native ACL. Two separate, double-stranded semitendinosus grafts looped over separate continuous loop EndoButtons are prepared. The femoral positions are selected at approximately 12:30 o’clock (2:00 o’clock for the left knee). The doubled semitendinosus graft constructs are usually from 6 to 7 mm in diameter, and the femoral sockets are reamed accordingly. Each double-stranded graft is passed as described for the single socket technique. When the two graft constructs have different diameters, the larger graft is pulled into the superior socket and secured proximally with the EndoButton. The second graft is then passed in the same fashion. The knee is taken through a range of motion to ensure there is no notch impingement. The two grafts are tensioned separately and tied over a single fixation post.
Summary The technique of quadrupled semitendinosus autograft for ACL reconstruction using the EndoButton for femoral fixation has been described. Dr. Rosenberg , this article’s senior author, has used this for over 10 years with no known instance of fixation failure at the femur or tibia. This technique using QST reconstruction has little morbidity, low reoperation rate, and excellent clinical results.
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tors. Knee ligaments. New York: Raven Press; 1990. p. 279 – 89. Steiner ME, Hecker AT, Brown Jr CH, et al. Anterior cruciate ligament graft fixation: comparison of hamstring and patellar tendon grafts. Am J Sports Med 1994;22:240 – 7. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament: a comparison of patellar tendon autograft and fourstrand hamstring tendon autograft. Am J Sports Med 1999;27:444 – 54. Rowden NJ, Sher D, Rogers GJ, et al. Anterior cruciate ligament graft fixation: initial comparison of patellar tendon and semitendinosus autografts in young fresh cadavers. Am J Sports Med 1997;25:472 – 8. Rodeo SA, Arnoczky SP, Torzilli PA, et al. Tendon healing in a bone tunnel: a biomechanical and histological study in the dog. J Bone J Surg Am 1993;75: 1795 – 803. Aglietti P, Buzzi R, Zaccherotti G, et al. Patellar tendon versus doubled semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction. Am J Sports Med 1994;22:211 – 8. Marder RA, Raskind JR, Carroll M. Prospective evaluation of arthroscopically assisted anterior cruciate ligament reconstruction: patellar tendon versus semitendinosus and gracilis tendons. Am J Sports Med 1991;19:478 – 84. Eriksson K, Anderberg P, Hamberg P, et al. A comparison of quadruple semitendinosus and patellar tendon grafts in reconstruction of the anterior cruciate ligament. J Bone J Surg Br 2001;83:348 – 54.
ACL reconstruction with hamstring tendon Leo Chen, MDa,b,*, Vernon Cooley, MDa,b, Thomas Rosenberg, MDa,b a
The Orthopedic Specialty Hospital, 5848 South 300 East, Salt Lake City, UT 84107, USA b Rosenberg-Cooley Clinic, 1820 Sidewinder Drive, Park City, UT 84098, USA
Anterior cruciate ligament (ACL) reconstruction has become the standard of care for ACL injuries in the active patient. Autograft reconstructions are more reliable than synthetic or allograft reconstructions. Both patellar tendon and hamstring tendon autografts are widely accepted graft options. Hamstring tendon grafts, specifically the quadrupled semitendinosus (ST) tendon, are excellent choices given their biomechanical properties, low harvest morbidity, and minimal complication profile.
Graft selection Graft selection is the cornerstone upon which optimal intra-articular ACL reconstruction is built. Graft sources include most commonly synthetic ligaments, allograft or cadaveric tissue, and autograft sources. Synthetic grafts have three main advantages: (1) strength of the graft, (2) absence of graft site morbidity, and (3) virtually endless supply. While some interest in synthetic ligaments continues, prosthetic failure, persistent effusions, late infections, excessive cost and a high reoperation rate make synthetic ligaments unattractive presently. Allografts also are abundantly supplied through a tissue bank, have no donor site morbidity, and allow shorter operating times. A huge interest in allograft reconstruction during the 1980s and early 1990s now appears to be waning as a result of late failures beyond 2 years. Allografts incorporate and remodel at slower rates than autografts. Malek and DeLuca
* Corresponding author. Rosenberg-Cooley Clinic, 1820 Sidewinder Drive, Park City, UT 84098. E-mail address: [email protected] (L. Chen).
have reported a high failure rate after 2 years using freeze-dried allografts [1]. Animal experimentation using allograft reconstruction has been disappointing as reported by Jackson et al and Sabiston et al [2,3]. A poorly understood immune response to allograft tissue, the potential for disease transmission, and quality control of the sources remain serious issues that discourage their use. Intra-articular ACL reconstruction using autografts is the gold standard for the foreseeable future. Since the 1980s, the endoscopic technique for reconstruction has reduced the associated surgical morbidity in the early postoperative course. Patellar bone-tendon-bone (BTB) or hamstring constructs are most commonly considered. Graft site morbidity, graft strength, graft fixation, practical considerations, and clinical results are important issues in determining the optimal graft.
Rationale for semitendinosus autograft Graft site morbidity All autologous graft choices have associated donor site morbidity. Many studies have demonstrated that hamstring grafts have fewer problems with anterior knee pain, quadriceps muscle deficits, and loss of extension compared with patellar BTB autografts. In reviewing BTB reconstructions at one year, Sachs et al reported a flexion contracture incidence of 24% of their patients, patellofemoral pain in 19% of their patients, and quadriceps weakness in 65% of their patients [4]. Bartlett reviewed the morbidity of central one-third patellar BTB graft harvest from the contralateral normal knee in patients requiring revision ACL reconstruction [5]. He found quad-
0030-5898/03/$ – see front matter D 2003, Elsevier Science (USA). All rights reserved. PII: S 0 0 3 0 - 5 8 9 8 ( 0 2 ) 0 0 0 1 6 - 0
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riceps deficits of from 15 to 20% at 6 months, a time when many athletes may return to sports. Rosenberg et al reviewed patients at 18 months after BTB reconstruction and identified an average quadriceps muscle deficit of 18%, as well as functional deficits, such as a diminished mean vertical hop of 4 cm [6]. Devastating complications have been associated with BTB reconstruction, such as patellar fracture, patellar tendon rupture, patellar dislocation, and patellar entrapment syndrome. Differences also exist between harvesting the semitendinosus and gracilis tendons versus the semitendinosus tendon alone. Lipscomb et al have reported small reductions in hamstring torque when using a combined semitendinosus and gracilis (STG) graft [7]. However, there were no differences in hamstring strength if only the semitendinosus was harvested. Yasuda et al reported a 19% decrease in hamstring strength compared with the uninvolved leg when the STG was used for reconstruction [8]. Cooley et al reported isokinetic hamstring deficits of less than 3% with singular harvest of the semitendinosus tendon for reconstruction [9]. In summary, semitendinosus harvest does not contribute significantly to the surgical risks of residual anterior knee pain, quadriceps weakness, and patellar entrapment syndrome. Surgeons who have commonly used both BTB and hamstring constructs recognize reduced morbidity with hamstring grafts. Graft strength Noyes et al reported that a 14 mm BTB graft represented 168% of ACL strength [10]. Therefore, a 9 or 10 mm BTB graft would represent approximately 120% of ACL strength. Noyes reported semitendinosus represents 70% of ACL strength. Assuming that doubling the graft produces equal tension in both limbs, a doubled semitendinosus graft would represent 140% of ACL strength, and a quadrupled construct might exceed 250% of ACL strength. Using a biomechanical cadaveric model, Hamner et al confirmed that a doubled semitendinosus construct has tensile strength over twice its initial strength [11]. In addition, their four-strand hamstring constructs were stronger than any of the 10 mm patellar ligament grafts described previously. The cross-sectional area of a 9 mm quadrupled semitendinosus autograft is between 60 mm2 and 70 mm2 compared with only 40 mm2 for a 10 mm BTB autograft. Compared with the STG graft, the average quadrupled semitendinosus (QST) autograft is larger in diameter and has a larger cross-sectional area. Thus, the QST has more surface area for tendon-
to-bone healing and is a stronger graft. The tubular shape of the QST allows for excellent graft-tunnel conformity, preventing tunnel widening. In addition, this larger graft often enables the surgeon to use a double- socket technique on the femoral side, allowing the ACL graft to be spread out over the femoral ACL footprint. Woo and Adams emphasize the importance of linear stiffness in addition to ultimate load to failure in graft selection [12]. Excessive stiffness may lead to abnormal knee kinematics, greater stress on the fixation, or microfailure of the graft. Noyes et al demonstrated that the stiffness of a semitendinosus graft is nearly equal to that of the anterior cruciate ligament, while BTB grafts are approximately 3.76 times stiffer than the ACL [10]. Thus, four-strand hamstring grafts, created by combining a doubled semitendinosus with doubled gracilis or by using a quadrupled semitendinosus graft, appear stronger than comparable BTB grafts and closer in linear stiffness to the anterior cruciate ligament. Graft fixation Initial graft fixation strength is important to allow early aggressive postoperative rehabilitation. While interference screw fixation has been heralded as the primary advantage of BTB reconstruction, Steiner et al have reported methods of quadrupled construct hamstring graft fixation with equivalent pull-out strength [13]. Corry et al used soft-tissue interference screws for four-strand hamstring tendon autograft and obtained satisfactory results [14]. Some BTB advocates still use sutures and buttons for BTB fixation, and it seems the advantage of interference screws for rigid initial fixation has been exaggerated. Using the EndoButton (Smith and Nephew Endoscopy, Andover, MA) in a cadaveric model, Rowden et al performed biomechanical testing of the quadrupled semitendinosus construct [15]. They found the load to failure with the EndoButton in a QST graft was higher than with interference screw fixation for BTB grafts. Ultimately, permanent biologic fixation of the autograft for stability is the goal. Since Sharpey’s description of the perforating fibers of the osteotendinous junction in the mid-nineteenth century, focus on tendon healing to bone has been intense. The literature contains many animal studies demonstrating soft-tissue graft healing to bone. Rodeo et al studied tendon-to-bone healing in a dog model, which revealed a steady progression in tendon-to-bone pull-out strength from 2 weeks to 6 months after surgery [16]. Fixation failure occurred before 8 weeks and graft failure thereafter. Sharpey-like fibers were
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noted at the bone interface in 8-week specimens. By 8 to 12 weeks, the tendon-bone interface closely resembled the normal insertion. Importantly, tendonto-bone healing may be less optimal for patellar tendon grafts that do not fill the tibial tunnel. ‘‘Windshield wipering’’ of the smaller patellar tendon graft and synovial fluid ingress can be anticipated. The patellar tendon grafts have smaller areas of exposed graft in contact with the tibial tunnel to enhance biologic healing and incorporation. Practical considerations Optimal graft size, graft stiffness, graft tissue compatibility, graft positioning, graft-to-tunnel conformity, and the method of postoperative rehabilitation all contribute to biologic healing. While interference screws provide a good initial fixation to BTB, fixation techniques for hamstring grafts also provide sufficient initial stability to allow early range of motion and weight bearing. Hamstring grafts are advantageous because they allow surgical precision and apply to a variety of patient needs. In this regard, quadrupled semitendinosus reconstruction is superior. Once learned, the semitendinosus harvest is quick and simple. Hamstring reconstruction can be undertaken without an overriding fear of patellar entrapment syndrome known to complicate acutely performed BTB reconstruction. The semitendinosus graft is indicated in some cases where a BTB graft would be ill advised. These cases include a skeletally immature patient, a patient (usually female) with a small patellar tendon, a patient with preexisting patellofemoral disease, a revision of failed BTB reconstruction, and augmentation in a reparable native ACL. Athletes who rely on their extensor mechanism, such as bikers, ballet dancers, skiers, and jumpers, often are compromised by a graft selection that insults the extensor mechanism—namely, BTB. Isometric or physiometric placement of the graft on the femur is achieved more readily with quadrupled semitendinosus constructs using the EndoButton. Endoscopic placement of the femoral tunnel for BTB grafts can be suboptimal because the surgeon is fearful of breaking through the posterior cortex of the femur. This is an especially valid consideration in small- to medium-sized patients where the goal of optimal tunnel positioning and maintenance of a strong circumferential bony tunnel wall may be mutually exclusive. With the QST graft, the femoral insertion can be elongated in the axis of the normal ACL footprint for optimal fiber orientation and function, because breakthrough of the posterior cortex does not compromise the fixation.
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Clinical results In the orthopedic literature, there are a growing number of outcome studies following endoscopic ACL reconstruction. In separate prospective series of alternatively treated patients with BTB and STG (quadrupled construct) grafts, Aglietti et al and Marder et al reported equivalent stability in both groups [17,18]. For studies looking specifically at QST, Cooley et al reported an average manual maximum KT1000 (MEDmetric Corporation, San Diego, CA) side-to-side difference of 0 +/ 1.3 mm in a series of patients treated by endoscopic QST reconstruction with at least 5-years’ follow-up [9]. Eriksson et al performed a prospective randomized study looking at unilateral ACL reconstruction with either the BTB grafts and interference screw fixation or QST autografts and EndoButton fixation [19]. Independent observers performed the follow-up investigation at a mean time of 33 months. The same rehabilitation protocol was used for all patients. No significant differences were found between the two groups with respect to functional testing, such as the one-leg hop test, IKDC score, Tegner activity level, and Lysholm score. While prior experience of the surgeon should help determine the best autograft choice for reconstruction, it appears that no single choice is optimally applied to a broad spectrum of patients who have variable risk factors and postoperative priorities. The reduced morbidity, enhanced connective tissue strength, and versatility of the quadrupled hamstring construct are important potential advantages to consider. Initial fixation strength of bone-tendon-bone by the use of interference screws and quick bone-to-bone healing remain important considerations for its use. Optimal results with either graft choice depend not only on the character of the graft, but also on precise surgical technique, which requires physiometric positioning and careful but aggressive postoperative rehabilitation. In the future, surgeons likely will need to be familiar with both autograft choices and their specific indications rather than relying solely on one or the other.
Endoscopic technique for quadrupled semitendinosus ACL reconstruction Patient positioning and surgical preparation The procedure is best accomplished using an arthroscopic leg holder and with the foot of the table flexed down completely (Fig. 1). A well-padded tourniquet is placed on the proximal thigh, and the affected leg is placed within the leg holder. The well
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Fig. 1. A tourniquet is on patient’s thigh, and patient’s affected leg is in leg holder. The foot of the operating room table is flexed completely.
leg is abducted, flexed at the hip and knee, and placed in a padded support, to be draped out of the surgical field (Fig. 2). The arthroscopic portion of the procedure may be done without a tourniquet, but the tourniquet is used to improve visualization during semitendinosus graft harvest. Placing the patient’s foot on the surgeon’s thigh controls the involved limb—accurate control of knee flexion is critical throughout the entire procedure. The surgeon sits on a draped rolling stool with full-length surgical gowns to maintain sterile technique (Fig. 3). By rolling forward or backward on a sitting stool, the surgeon is able to carefully control the degree of knee flexion. Semitendinosus graft harvest Semitendinosus harvest is accomplished with the surgeon sitting and the knee in 80° to 90° of flexion. A
Fig. 2. Abducted and flexed at the hip and knee, the patient’s well leg is draped out of the surgical field.
Fig. 3. Surgeon in a full-length gown sits on a draped, rolling stool. With the patient’s foot on the surgeon’s thigh, the surgeon can control the degree of knee flexion.
4 cm to 5 cm longitudinal skin incision is made over the pes tendons beginning 2 cm to 3 cm distal to the joint line and 1 cm to 2 cm medial to the tibial tuberosity. The sartorius aponeurosis is identified using a sponge, and the underlying gracilis tendon and semitendinosus tendon are palpated. The sartorius aponeurosis is incised in line with its fibers distal to the underlying semitendinosus tendon. Using digital palpation, the semitendinosus tendon is isolated where it naturally separates from the gracilis tendon, approximately 5 cm to 8 cm proximal to their tibial insertions. A curved clamp and a small Penrose drain are placed around the semitendinosus tendon for positive identification (Fig. 4). While carefully avoiding injury to the underlying superficial medial collateral ligament, sharp division with a scalpel of the proximal and distal margins of the semitendinosus tibial insertion usually permits the tendon to be digitally ‘‘popped off’’ its insertion, providing an
Fig. 4. Semitendinosus tendon is isolated with curved clamp and Penrose drain for positive identification.
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extra 1 cm to 2 cm of tendon length. A #5 Mersilene (#2 for patients who weigh less than 150 pounds) running whipstitch is placed at five or six levels in the distal tendon to control the free end. While traction is applied to the free end of the tendon using the whipstitch, the deep fascial bands to the medial gastrocnemius fascia can be identified and released with Metzenbaum scissors (Fig. 5). Premature transection of the semitendinosus tendon may occur without release of these fascial attachments. With the knee flexed 70° to 80°, gentle traction is maintained on the distal tendon while a closed-end tendon stripper is advanced proximally in line with the tendon. Commonly, the semitendinosus tendon graft will have a length between 24 and 40 cm. While the graft is transferred to the back table for preparation, inspection of the distal insertion of the superficial medial collateral ligament (MCL) is recommended (Fig. 6). If there is no injury to the MCL that requires surgical attention, the sartorius aponeurosis is then reapproximated with #0 or #1 Vicryl suture. Semitendinosus graft preparation The graft is prepared on the back table by the surgeon or an assistant while the surgeon proceeds with the endoscopic portion of the procedure. Graft preparation is performed on a graft preparation board (Fig. 7). After harvest, the graft is kept moist at all times with a wet sponge to prevent tissue desiccation. Any muscle remaining on the graft is removed with a Cobb periosteal elevator or a metal ruler edge. The proximal end of the graft is thin and may be tubularized with a running baseball stitch using #2-0 or #3-0 Vicryl on a tapered needle. Overall tendon length is measured, and the final quadrupled graft length is calcu-
Fig. 5. The semitendinosus tendon has deep fascial bands to the medial gastrocnemius fascia. Failure to release these bands can lead to premature transection of the graft.
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Fig. 6. The superficial medial collateral ligament is underneath the semitendinosus, which is retracted by the Penrose drain. Inspection of the ligament is recommended to determine whether surgical attention is necessary.
lated by taking one quarter of the overall length. The required minimum graft length is about 22 cm, because a minimum of 15 mm of quadrupled graft is needed within both the tibial and femoral tunnels. However, if the semitendinosus tendon proves too short for use as a quadrupled graft, the gracilis tendon can be harvested, and a doubled semitendinosus and gracilis graft is used. Another option is a tripled semitendinosus graft that maintains the integrity of the gracilis. The semitendinosus tendon is sharply divided in half on the preparation board to create two equallength grafts. A #5 or #2 Mersilene suture on a tapered needle is whipstitched to each of the remaining three free ends of the grafts; holding clamps secure the grafts during suture placement. Then, the two grafts are each doubled over a 6 mm polyester tape to produce a quadrupled construct (Fig. 8). This construct is passed through sizing tubes to determine the graft
Fig. 7. Graft preparation board. Holding clamps secure the graft to facilitate suture placement.
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distal outlet of the notch is best visualized from 45° to 60° of knee flexion, and the proximal outlet at 90°of flexion. The over-the-top position is identified; however, the proximal outlet is not generally expanded. Tunnel preparation
Fig. 8. The two grafts are doubled over polyester tape to create a four-strand construct. Then the quadrupled graft is passed through sizing tubes.
diameter at both its proximal and distal ends. If a femoral double-socket technique will be employed, each graft is measured separately with the sizing tubes. The polyester tape is then placed through the two central holes of the EndoButton, but it is not tied. Alternatively, there is also an EndoButton CL (Smith and Nephew Endoscopy, Andover, MA) with a continuous polyester loop already attached to the EndoButton through the two central holes (Fig. 9). This contstruct eliminates the need for tying knots in the polyester tape. A #5 Ticron suture is placed through the leading EndoButton hole, and a #2 Ticron suture is placed through the trailing hole for either construct. The graft is kept moist wrapped in a wet sponge. Endoscopic preparation A superomedial outflow portal is created and is used initially to inject 30 cc of 0.25% Marcaine with epinephrine solution into the knee joint during graft harvest. The longitudinal anterolateral portal is created 1 cm above the joint line immediately adjacent to the patellar tendon, and the anteromedial portal is created at the same level above the joint line from 5 to 8 mm medial to the patellar tendon. If necessary, the ligamentum mucosum and fat pad are excised to facilitate viewing the intercondylar notch. The ACL stump is debrided partially, leaving a substantial portion to guide tibial tunnel placement. The intercondylar notch is then evaluated. Using arthroscopic curettes, grasping forceps, and a fullradius shaver, a notchplasty is performed, if needed, with its extent determined by individual anatomy. Notchplasty allows improved identification of the femoral attachment site of the native ACL and helps prevent graft impingement after reconstruction. The
First, the tibial tunnel is prepared. The pretibial periosteum is incised longitudinally with electrocautery, beginning at the superior margin of the sartorius insertion and the medial margin of the patellar tendon. This incision is taken 2 cm to 3 cm proximally toward the joint line. Limited subperiosteal elevation is performed with a Cobb elevator at this anteromedial incision. The endoscopic aimer for the tibial tunnel is adjusted to the 45° position, and the guide-tip is positioned intra-articularly through the anteromedial portal. The 45° orientation produces an ovoid intraarticular aperture that more closely approximates the anatomic ACL footprint of the tibia. The guide pin typically is angulated 45° to the anterior cortex of the tibia when viewed laterally placing the tibial tunnel approximately 3.5 cm below the joint line (Fig. 10). A more vertically oriented tibial tunnel may preclude optimal femoral access and produces a more circular, less anatomic aperture in the tibia. The guide-tip is positioned with the tip impaling the posterior fibers of the tibial ACL stump. With optimal guide pin positioning, (1) the guide pin is in the center of the tibial stump; (2) from 5 to 6 mm of clearance exists between the pin and the roof of the notch in full extension; and (3) at 90° of knee flexion, the guide pin is directed just distal to the over-the-top position. A cannulated reamer corresponding to the size of the graft is used to drill the tibial tunnel; the surgeon stops
Fig. 9. The two grafts are looped over an EndoButton CL to produce the quadrupled graft. A #5 Ticron suture is placed through the leading hole, and a #2 Ticron suture through the trailing hole.
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flexion. A calibrated, cannulated, endoscopic reamer sized to match the graft’s proximal diameter is placed manually through the tibial tunnel and abutted against the femur. The intra-articular graft length is estimated from the calibration lines on the reamer. The amount of graft contained within the femoral tunnel (graft insertion length) is determined by taking one half of the remaining graft length after subtracting the intraarticular length from the overall, prepared quadrupled graft length. The femoral tunnel is drilled 5 to 6 mm deeper than the graft insertion length to allow for a ‘‘turning radius’’ of the EndoButton. A long passing pin is advanced through the tibial tunnel and femoral socket, and drilled through the anterolateral cortex of the distal femur. A 4.5 mm cannulated reamer is used to over drill this passing pin through the cortex, producing a femoral passing channel for the EndoButton (Fig. 12). A depth gauge measures the total femoral channel length precisely. Fig. 10. The endoscopic tibial aimer is set at 45° to allow optimal placement of the tibial tunnel and access to the overthe-top position. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
when the reamer just breaks through the intra-articular cortex. Finally, a 5.5 mm synovial resector is placed through the tibial tunnel to remove debris. Next, the femoral tunnel is prepared. A femoral endoscopic aimer with a 3 mm offset is inserted through the tibial tunnel and placed on the over-thetop position (Fig. 11). The femoral guide pin is then inserted at the 11 o’clock position for the right knee (1 o’clock for the left knee) and advanced 2 cm to 3 cm into the femur while maintaining the knee at 90° of
Fig. 11. The endoscopic femoral aimer with a 3 mm offset is placed at the over-the-top position. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
Fig. 12. The femoral tunnel is reamed and measured with a depth gauge. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
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Graft passage and fixation Tying the 6 mm polyester tape at its calculated connector length completes graft preparation. The connector length is determined by subtracting the graft insertion length from the total femoral channel length. The polyester tape is tied with a doubled surgeon’s knot. When using the EndoButton CL, the tape is continuous, and knots do not have to be tied. However, the appropriate length of the continuous loop must be calculated. This length is determined by the difference between the total femoral channel length and the desired graft insertion length. Because the EndoButton CL is available only in 5 mm increments, round up to the larger size if the length falls between two sizes. The graft is passed through the continuous loop and is marked at the graft insertion length with a sterile marking pen. While at least 90° of knee flexion is maintained, a passing pin is placed through the tibial tunnel, femoral socket, and distal thigh, while counter pressure is applied to the thigh with an Army-Navy retractor. The #5 and #2 Ticron sutures are threaded through the eyelet of the passing pin, and the passing pin is extracted proximally, bringing the sutures out through the distal thigh (Fig. 13). The #5 Ticron suture is used as a leading suture to pull the EndoButton and graft construct proximally into the joint while the surgeon controls the slack in the trailing #2 Ticron suture. The graft is viewed endoscopically to ensure the graft marker line is even with the entrance of the femoral socket. The trailing #2 Ticron suture is pulled to flip the EndoButton external to the femoral tunnel, now the #5 and #2 Ticron sutures can toggle the EndoButton (Fig. 14). The
Fig. 14. The EndoButton is flipped by the trailing #2 suture to provide superior femoral fixation. The #5 (upper black arrow) and #2 (lower black arrow) sutures can toggle the EndoButton. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
EndoButton is deployed on the cortex of the distal femur, providing femoral fixation. The graft is pulled firmly distally, confirming the EndoButton has been flipped and secured on the anterolateral cortex of the distal femur. With manual tension applied to the distal graft sutures, the knee is taken through a range of motion to confirm endoscopically the absence of graft impingement. If slight impingement is noted, the notch is slightly enlarged with curettes or an abrader. For tibial fixation, the distal graft sutures are tied over a screw as a post. The proximal tibia is drilled with a 2.5 mm drill bit perpendicular to the anteromedial tibial cortex approximately 1 cm distal to the tibial tunnel. A self-tapping unicortical cancellous fixation screw is advanced incompletely. The graft is tensioned at about 30° of knee flexion, and the matched sutures are secured around the fixation screw (Fig. 15). Then the screw is tightened fully.
Femoral double-socket technique Fig. 13. The #5 and #2 sutures are pulled through the distal thigh, and then the graft is pulled into place with the leading #5 suture.
During passive knee motion, the normal ACL elongates from 2 to 3 mm in the last 20° of extension.
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Postoperative rehabilitation Rehabilitation protocols emphasize early mobilization to maximize return to activity, while adhering to current scientific understanding of graft incorporation and remodeling. Postoperatively, patients remain in a hinged knee brace locked at 20° of knee flexion and kept nonweight bearing for 1 week. After 1 week, patients begin range of motion therapy and progressively bear weight as tolerated. After nearly full range of motion is achieved, patients start strength training, with the emphasis on closed kinetic chain exercises. Rehabilitation progresses from functional activities and to sports-specific training. If muscular strength is adequate, returning to sports usually is permitted after 6 months. Patients are fitted for functional sports braces to aid in proprioceptive feedback during their return to sports. Rehabilitation is altered by concomitant procedures, such as meniscal repair or microfracture. Meniscal repairs usually immobilize patients in a knee brace for 2 to 3 weeks after surgery, and microfracture procedures keep patients nonweight bearing for 4 to 6 weeks. Fig. 15. The graft is tensioned and the distal graft sutures are tied over a fixation screw as a post. (Adapted from Rosenberg TD. Technique for ACL reconstruction with AcufexR director drill guide and EndoButtonR CL. Andover (MA): Smith & Nephew, Inc.; 1999; with permission.)
However, single-bundle ACL reconstructions have difficulty reproducing the physiometric motion of the native ACL, especially in a large patient. A femoral double-socket technique offers the best physiometric approximation. This technique spreads out the grafts along the femoral attachment site along the axis of the native ligament, creating anteromedial and posterolateral fiber bundles that more nearly replicate the physiometric behavior of the native ACL. Two separate, double-stranded semitendinosus grafts looped over separate continuous loop EndoButtons are prepared. The femoral positions are selected at approximately 12:30 o’clock (2:00 o’clock for the left knee). The doubled semitendinosus graft constructs are usually from 6 to 7 mm in diameter, and the femoral sockets are reamed accordingly. Each double-stranded graft is passed as described for the single socket technique. When the two graft constructs have different diameters, the larger graft is pulled into the superior socket and secured proximally with the EndoButton. The second graft is then passed in the same fashion. The knee is taken through a range of motion to ensure there is no notch impingement. The two grafts are tensioned separately and tied over a single fixation post.
Summary The technique of quadrupled semitendinosus autograft for ACL reconstruction using the EndoButton for femoral fixation has been described. Dr. Rosenberg , this article’s senior author, has used this for over 10 years with no known instance of fixation failure at the femur or tibia. This technique using QST reconstruction has little morbidity, low reoperation rate, and excellent clinical results.
References [1] Malek MM, Deluca JV. Freeze-dried Achilles tendon allograft in anterior cruciate ligament reconstruction: two and five year follow-up comparison. Presented at the annual meeting of the American Academy of Orthopaedic Surgeons. San Francisco, February 1993. [2] Jackson DW, Grood ES, Arnoczky SP, et al. Cruciate reconstruction using freeze-dried anterior cruciate ligament allograft and a ligament augmentation device (LAD): an experimental study in a goat model. Am J Sports Med 1987;15(6):528 – 38. [3] Sabiston P, Frank C, Lam T, et al. Allograft ligament transplantation: a morphological and biochemical evaluation of a medial collateral ligament complex in a rabbit model. Am J Sports Med 1990;18:160 – 6. [4] Sachs RA, Daniel DM, Stone ML, et al. Patellofemoral
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