The miniarthrotomy technique for anterior cruciate ligament reconstruction

THE MINIARTHROTOMY TECHNIQUE FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION K. DONALD SHELBOURNE, MD and THOMAS E. KLOOTWYK, MD

Anterior cruciate ligament (ACL) reconstruction is performed in a variety of different surgical approaches. Techniques available include a miniarthrotorny, through the patellar tendon defect, arthroscopically assisted, and, most recently, the endoscopic technique. Methods of fixation used to secure the graft include interference fit with screw fixation, screw and spiked washer, barbed staples, suture and button, and sutures around a post. It is our opinion that the visualization of the notch and the access to the posterior lateral wall for placement of the femoral tunnel afforded the surgeon by the miniarthrotomy is superior to other techniques for ACL reconstruction. The miniarthrotomy technique, as described in this article, offers reproducible excellent results and remains our method of choice for ACL reconstruction surgery. KEY WORDS: ACL autogenous graft, ACL patellar tendon, ACL surgical technique

The rniniarthrotorny procedure for anterior cruciate ligament (ACL) reconstruction starts with a careful examination of the noninjured knee and the injured knee under anesthesia. Next, 20 mL of 0.25% Marcaine (bupivacaine hydrochloride, Winthrop, New York, NY) with epinephrine is injected intra-articularly into the injured knee, which is prepared and draped. The tourniquet is inflated before the start of the arthroscopic procedure. In this article we describe aspects of the total ACL reconstruction from the arthroscopic examination and meniscal repair to the time when the patient is in postoperative care.

MENISCAL PRESERVATION We take an extremely aggressive approach to meniscal preservation. It has been our finding that most meniscal tears associated with ACL tears are salvageable. In acute cases we have been able to preserve 94% of the medial menisci and 81% of the lateral menisci in recent years. Those meniscal tears that are stable and have a potential to heal are left alone. Those tears that are unstable with a potential to heal are repaired. The repair is performed using an inside-out technique with multiple permanent sutures that are placed with the aid of the Acufex (Acufex Microsurgica, Inc, Norwood, MA) meniscal repair cannulas. The sutures are tied over the capsule through a separate medial or lateral incision. Those infrequent meniscal tears that are considered unrepairable, such as chronic bucket-handle tears with extensive degeneration, are treated by partial meniscectomy. After the meniscal paFrom the Methodist Sports Medicine Center, Indianapolis, IN. Address reprint requests to K. Donald Shelbourne, MD, Methodist Sports Medicine Center, 1815 N Capitol Ave, Suite 530, Indianapolis, IN 46202. Copyright © 1993 by W. B. Saunders Company 1060·1872193/0101·0005$05.00/0

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thology has been treated, the articular surfaces are inspected and photographed for future reference. We rarely perform chondral shaving. Our only indication for chondral debridement is large articular surface flap tears.

MEDIAL MINIARTHROTOMY (6-CM INCISION); LATERAL RETINACULAR RELEASE At the completion of arthroscopic evaluation of the knee and the treatment of meniscal and chondral pathology, the ACL reconstruction is initiated with the operated extremity being redraped. A wedge is placed under the distal thigh. The tourniquet remains inflated from the beginning of the arthroscopic procedure. This does not present a problem because the total tournique time for the combined procedures is usually less than 60 minutes. The surgeon makes a 6-cm skin incision distally from the anteromedial arthroscopic portal to the level of the tibial tubercle (Fig 1). Sharp dissection is carried down to the level of the patellar tendon peritenon. At this point a combination of blunt and sharp dissection is used to develop a plane between the underlying fascia and the overlying subcutaneous tissue. This layer is created from the proximal pole of the patella to the anteromedial aspect of the proximal tibia distally. The dissection allows easy retraction for the eventual harvest of the patellar tendon graft and for performing the lateral patellar retinacular release. Using electrocautery we create a flap of periosteum starting along the medial border of the patellar tendon at the level of the proximal tibia. This is carried down the tibia to the level of the pes anserine tendons. This expoSure extends approximately 4 em below the joint line. Thus, the tibial drill hole can be placed distally enough to ensure that the bony tunnel wiII be at least 25 mm in length. A thick flap of periosteum is preserved to allow

Operative Techniques in Sports Medicine, Vol 1, No 1 (January), 1993: pp 26-39

Fig 1. Anteromedial skin incision.

closure over the tunnel and fixation button at the completion of the ACL reconstruction (Fig 2). In our experience the closure of the periosteum over the button minimizes the incidence of problems with prominent painful buttons in the postoperative phase. Only 2.2% of tibial buttons have required removal postoperatively in a population of 1,300 ACL reconstructions. The medial miniarthrotomy is performed with electrocautery. The capsular incision starts just medial to the patella and is carried proximal to the level of the vastus medialis muscle and distally to the joint line. With appropriate retraction we obtain excellent visualization of the notch and the tibial plateau. At no time during the reconstructive procedure is the patella dislocated. We perform a lateral patellar retinacular release with electrocautery. Starting at the lateral joint line, lateral to the patellar tendon, the release is carried proximally to the superior pole of the patella. The release is carried through the lateral retinaculum and the lateral patellofemoral ligament but not through the synovial lining. Because we close the patellar tendon defect after graft harvest, we have found that the lateral release is helpful. Although there exists no scientific evidence that a lateral release decreases postoperative patellofemoral problems, in our opinion the release helps to decrease patellofemoral symptoms of those patients undergoing ACL reconstruction with the bone-patellar tendon-bone autograft. MINIARTHROTOMY ACL RECONSTRUCTION

Fig 2. Proximal tibial exposure with periosteal flap preserved (in forceps).

LATERAL (2.5 CM) OBLIQUE INCISION The position of the extremity is taken from 25° of flexion to 90° of flexion by raising the operating table and lowering the foot completely. We expose the distal lateral femur by making an oblique incision centered over the lateral aspect of the femur in line with Langer's lines. The proximal extent of this incision is started 2.5 cm proximal to the superior pole of the patella with the knee in a 90° position (Fig 3). Previously, we made this incision parallel to the iliotibial band. We encountered occasional problems with lateral wound healing. When we analyzed these problems, we decided that they were secondary to stress placed on the healing skin by the aggressive postoperative rehabilitation. In 1990 we began performing the lateral skin incision in an oblique direction and noted a resolution of the previous wound healing problems. After completing the lateral skin incision, we make a sharp dissection down to the level of the iliotibial band where we use blunt dissection to separate the iliotibial band from the overlying subcutaneous tissue. With the knee held in extension, the iliotibial band is split. Blunt digital dissection is then performed down to the level of the lateral femoral cortex. The vastus lateralis muscle belly is swept anteriorly. A Slocum retractor is placed over the anterior aspect of the distal femur, and a Cush-

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Fig 3. Lateral skin Incision.

ing retractor is placed on the posterior border of the iliotibial band; thus, we have obtained an excellent exposure of the distal lateral femur. At the site of exposure there lies a branch of vessels from the superior lateral geniculate artery. These visible vessels are electrocauterized and then the periosteum is split in a r-type fashion. Flaps are raised with the periosteal elevator. The lateral femoral cortex is prepared for the desired exit point of the femoral tunnel. This site is approximately 5 cm above the articular surface above the metaphyseal flare and on the flat surface of the lateral femur. We now direct our attention back to the intraarticular aspect of the knee.

NOTCHPLASTY A Slocum retractor is placed through the medial miniarthrotomy and around the lateral femoral condyle to retract the patellar tendon laterally. The patella remains located in the trochlear groove. A Cushing retractor is used to retract the vastus medialis muscle, and a twoprong rake is used to retract the fat pad. This gives excellent visualization of the notch (Fig 4). We use the lateral border of the posterior cruciate ligament (PCL) as our landmark for the intercondylar notch. A curved Metzanbaum scissor is used to penetrate and dissect along the lateral border of the PCL. All soft tissue lateral to the PCL (old ACL and fibrofatty synovium) is removed to ensure adequate notch visualization (Fig 5). A no. 4 curette is used to remove the soft tissue including the fat located posterior to the PCL. The curette is then used to probe the posterior lateral aspect of the notch and identify the over-the-top position. With the soft tissue lateral to the PCL removed, the overall notch configuration can be determined, and a better appreciation for the eventual placement of the ACL graft is obtained. At this point, measurement of the notch width and measurement of the lateral wall of the notch to the lateral border of the PCL is performed (Fig 6). This measurement indicates the amount of space in the notch that was available for the original ACL. Notch impingement has been one of the etiologies of limitation to extension after

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Fig 4. Exposure of the notch obtained with the miniarthrotomy.

ACL reconstruction. Therefore, adequate notchplasty should be performed at the time of ACL reconstruction. Because we are using a lO-mm graft for the reconstruction, our notchplasty is designed to allow us to have at least 10 mm from the lateral border of the PCL to the lateral of the femoral condyle to avoid impingement. The notchplasty is performed with a curette, and the created space is measured to ensure that adequate bony resection has been performed (Figs 7 and 8). The entire process of clearing the lateral wall of soft tissue and performing an adequate notchplasty is also extremely important for visualization and proper placement of the femoral tunnel in a posterior position. With the notchplasty complete, we direct attention to the tibial and femoral tunnels.

CREATION OF BONY TUNNELS (TIBIAL AND FEMORAL) Because of the importance of exact placement of both the tibial and femoral tunnels to ensure success of the ACL reconstruction, we advocate independent placement of both tunnels at the exact anatomic position. In our hands, this independent placement of the tunnels leads to the least source of error in tunnel placement. We avoid one tunnel being in a less than ideal position, subsequently leading to a compromise in position of the second tunnel position. The tibial attachment site of the normal ACL is wider than the femoral attachment.lv Exact placement of the SHELBOURNE AND KLOOTWYK

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Fig 5. (left) The lateral border of the PCl Is Identified, and (right) the notch space available for the (old) ACl Is visualIzed.

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tibial tunnel is more difficult to pinpoint. The ideal graft placement will result -in the graft lying flush with the roof of the femoral notch with the knee in full extension. Anterior placement of the tibial tunnel has been emphasized

by Clancy et al,3 and other studiesv'' have recommended anteromedial placement of the tibial tunnel. Anterior positioning will place the graft in a more horizontal attitude in the notch, which leads to less deformation with knee flexion than a more posterior/vertical placement. This information resulted in an acceptance among some surgeons that if an error in tibial placement occurred, an anterior placement would be more acceptable than a posterior position. Anterior placement of the tibial tunnel is not without problems. An anterior position leads to impingement of the graft in the notch when the surgeon or the therapist attempts (either passively or actively) to extend the knee fully or the patient tries to achieve full extension. This

Fig 6. Calipers are used to measure the original space available for the native ACL.

Fig 7. A curette Is used to perform the notchplasty. This Is quIckly and easily performed through the mlnlarthrotomy.

MINIARTHROTOMY ACL RECONSTRUCTION

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Fig 8. (left and right) Adequate notch space Is created lateral to the PCl to ensure adequate space for the 10-mm ACl graft.

rat space

problem of excessive anterior placement of the tibial tunnel has recently been demonstrated by magnetic resonance imaging." Anterior position can lead to graft failure or lack of full extension postoperatively because of notch impingement. The tibial tunnel is drilled first. Determining the position of the tibial tunnel is done by viewing the medial tibial plateau as a clock (Fig 9). Using the 9 o'clock position as the center of the plateau for a right knee and 3 o'clock for a left knee, the ideal position for the graft will

Area of Posterioriza io

/ Fig 9. A "clock face" is Interposed on that portion of the medial tibial plateau that is visualized through the miniarthrotomy.

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be just posterior to this point. We aim for an intraarticular pin position of 5 mm lateral to the articular surface of the medial plateau and 2 mm anterior to the 9 o'clock position. Therefore, because the patellar tendon is approximately 4 mm thick, we will want the posterior aspect of the tunnel to be 3 to 4 mm posterior to the 9 o'clock (or 3 o'clock) position. Drilling from outside to inside, a 3/.32-inch guide pin (Steinmann pin) is placed on the anteromedial tibia, with the starting point approximately 3 to 4 cm below the joint line and 10 mm medial to the patellar tendon (Fig 10). This ensures a tibial bony tunnel of at least 25 mm, and the slight medial positioning will allow seating on bone of the 19-mm diameter fixation button without interference of the tibial tubercle . We have noted that perfect placement of the tibial tunnel is difficult with the initial drilling. The use of the 3/32-inch guide pin allows the surgeon to change the position easily if an acceptable placement is not obtained on the initial pass. Also, we intentionally drill the tibial tunnel slightly anterior, and then move the tunnel slightly posteriorly with curettes. A 9-mm Acufex cannulated reamer is used to drill the tibial tunnel when the pin position is determined to be appropriate (Fig 11). Bone from the tibial tunnel reaming is harvested and saved for bone grafting of patellar and tibial defects at the completion of the reconstruction. At the completion of reaming, all soft tissue, including the old ACL stump, is excised by sharp dissection from the floor of the tibial plateau with a no . 15 scalpel blade. Curettes are then used to modify the tibial tunnel entrance into the joint. Starting with a no. 5 curette (9 mm) and extending to a no. 6 curette (11 mm), this modification of the tibial tunnel is performed. The ability to change the entrance point of the tibal tunnel with the curettes by 1 to 2 mm is a distinct advantage. The surgeon is easily able to enlarge the tunnel to the desired 11-mm size and create this additional 2 mm of the tunnel posteriorly (Fig 12A). Thus, ideal placement of the tibial tunnel is created as it enters the joint. SHELBOURNE AND KLOOTWYK

Fig 10. Starting point for the tibial tunnel.

The tibial tunnel is usually somewhat funnel-shaped . Because the exact size for the tunnel is not known until the final curetting is performed, the graft is not harvested initially. Instead, we delay the patellar tendon graft harvest until we know the tibial tunnel size, and then we can modify the size of the bone plug to appropriately fill the tibial tunnel. This allows for a "wedge fit" of the eventual grafted bone plug. The total length of the tibial tunnel is usually approximately 25 to 30 mm. Femoral tunnel placement is the most important and perhaps the most difficult aspect of the procedure. It is our opinion that improper femoral tunnel position is one of the most common causes of failure of the reconstructive procedure. Vertical orientation of the graft from a

Fig 11. Reaming of the tibial tunnel.

femoral tunnel that is placed "too shallow" in the notch can lead to two separate problems. First, possible capturing of the joint with resultant joint stiffness can occur . Second, graft failure can occur once full range of motion (ROM) is achieved. The femoral tunnel should be created through a simple

L Fig 12. (Left) A curette is used to modify the tibial tunnel entrance into the joint. (Right) Most often a small amount of "posteriorization" of the tunnel is performed.

MINIARTHROTOMY ACL RECONSTRUCTION

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and reproducible method. There should be a straight line orientation with the tibial tunnel. We believe that placing the femoral tunnel guide pin from the inside of the notch with an open view provided by the miniarthrotomy allows the surgeon to better visualize the overall configuration of the notch and therefore more accurately and predictably place the guide pin in the proper posterior position and orientation. The close-up view through the arthroscope does not give the surgeon a full appreciation of notch configuration, and in our opinion this represents an advantage of the open technique. Our guidelines for femoral tunnel placement are as follows. (1) The tunnel should be as "deep" in the notch as possible. (2) A 1- to 2-mm bony bridge should remain posteriorly after the tunnel has been reamed. (3) The "tunnel should be positioned so that with graft passage the new ligament lies directly adjacent to the PCL. (4) The tunnel should allow straight-line placement of the graft in line with the tibial tunnel when the knee is in 30° of flexion. With the notch already prepared by notchplasty, all soft tissue from the lateral border of the PCL to the lateral wall removed, and the posterior cortex of the notch cleaned and well visualized, the surgeon is ready to proceed with -placement of the femoral tunnel. The knee is placed in a figure-4 position (Fig 13). A Slocum retractor is used to hold the patellar tendon laterally, and the medial capsule is retracted with a twoprong rake. A 3h2-inch guide pin is placed directly next to the lateral border of the PCL and passed a few millimeters out of the back of the well-visualized notch. With the posterior aspect of the notch palpated and visualized, the pin is brought forward into the notch 6 to 7 mm and laterally 2 to 3 mm. This position will establish the center of the femoral tunnel (Figs 14, 15, and 16). With the appropriate pin starting point obtained, the guide pin is directed and advanced towards the previously established area on the lateral femoral cortex. Once

-10 mm diameter femoral tunnel

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Fig 14. The appropriate posterior position of the femoral tunnel.

the pin has penetrated the lateral femoral cortex, the tip of the pin is palpated beneath the vastus lateralis muscle to ensure that it is in proper position (not too anterior or too posterior). If the pin is in an unacceptable position it is redirected toward the desired lateral exit location without changing the starting point in the notch. It has been our observation that drilling through the patellar tendon defect or through the tibial tunnel can make it more difficult to have the pin exit in the desired lateral position (not too anterior or too posterior). When the guide pin is

----Fig 13. Flgure-4 position.

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Fig 15. Diagram showing the appropriate orientation of the femoral tunnel guide pin and subsequent tunnel In reference to the lateral border of the peL. SHELBOURNE AND KLOOTWYK

Fig 17. The 10-mm Acufex reamer.

Fig 16. The femoral tunnel guide pin resting along the lateral border of the pel in the appropriate posterior starting point at the back of the notch.

in the appropriate position, it is overdrilled with an Acufex lO-mm reamer (Fig 17). With the 10-mm overdrilling of the guide pin, the desired 1 to 2 mm of posterior cortex of the notch will remain, and the medial border of the reamed tunnel will lie just posterior to the lateral border of the PCL (Fig 18). The cancellous bone from the reamings is retrieved for bone grafting of the patellar and tibial defects at the completion of the ACL reconstruction. On completion of the femoral tunnel reaming, which is usually about 50 to 80 mm long, the lateral femoral cortex is checked to ensure that the femoral tunnel exit site is cleared of overlying periosteum.

Appropriate placement of both tibial and femoral tunnels is confirmed when, with the knee in 300 of flexion, a straight guide wire can be passed through the tibial tunnel across the knee joint and into the femoral tunnel exiting at the lateral femoral cortex (Fig 19). When the guide pin passes straight through the knee with the knee in this position, it can be confirmed that the tunnel in both the tibia and femur are in appropriate position and orientation. If the guide pin does not pass through the knee it is usually because the tibial tunnel is too anterior, and this can easily be corrected by curetting the tibial tunnel more posteriorly. If the tibial tunnel becomes larger than the desired 10 to 11 mm, a larger bone plug can be harvested to ensure that the tunnel will be filled with bone when placing the graft.

HARVESTING THE BONE-PATELLAR TENDON-BONE AUTOGRAFT At this time the bone-patellar tendon-bone autograft is harvested. Using curved Metzanbaum scissors, the plane between the peritenon and the underlying peripa-

Fig 18. (left and right) The femoral tunnel as it enters the notch shown In the appropriate posterior position and orientation.

MINIARTHROTOMY ACL RECONSTRUCTION

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Fig 19. Guide pin passed through both tunnels with the knee in 30° of flexion.

tellar tendon is developed. The peritenon is split longitudinally over the tendon, and the patella and is preserved for closure of the patella, patellar tendon, and tibial defects at the completion of the ACL reconstruction (Fig 20). Medial and lateral borders of the patellar tendon are identified, and the width of the tendon is measured in millimeters at its narrowest point (Fig 21). A 10-mm bone-patellar tendon-bone graft is harvested from the central one third of the patellar tendon. Outlines of the bone plug to be harvested are made with a scalpel blade over the bony patella and proximal tibia. Osteotomes are used to score the most proximal extent of the patellar bone plug and the most distal extent of the tibial bone plug. An oscillating saw is used to harvest a plug 10 to 11 mm in diameter and 25 mm in length (Fig 22). The patellar bone plug is harvested initially. With the patellar tendon still connected to the underlying fat pad preserving soft tissue connections, the patellar bone plug is cut with the osciIlating saw and elevated out of its patellar bed with a curved osteotome. The bone plug is sized and contoured with a rongeur to ensure passage through the tibial tunnel (Figs 23 and 24). After this has been performed we turn the cancellous surface of the plug forward and place the bone plug back into the patellar defect. Three drill holes, appropriately spaced, are placed in the plug with a one-sixteenth-inch drill for passage of no. 2 Ethibond (Ethicon, Inc., Somerville, NJ) sutures (Fig 25). These Ethibond sutures have been threaded on single straight needles. The ends of the sutures through the patellar plug are then secured to the

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Fig 20. Preservation of the patellar tendon peritenon.

operative field to prevent inadvertent dropping of the graft. Next, the tibial bone plug is harvested and elevated out of the tibial bed. It is contoured in similar fashion to ensure that it passes through a 10-mm sizer. Three sets of no. 2 Ethibond are placed through the tibial bone plug. At this time the remainder of the fat pad and soft tissue connections to the patellar tendon are removed by sharp dissection (Fig 26). The graft is inspected briefly to en-

Fig 21. Measurement of the patellar tendon width. SHELBOURNE AND KLOOTWYK

Fig 23. Contouring of the bone plug to ensure proper size.

Fig 22. Harvesting of the patellar bone plug with an oscIllating saw.

sure that extraneous soft tissue has been removed that might prevent easy passage of the graft through the tunnels (Fig 27). The patellar tendon length and width are measured and recorded.

Fig 24. Confirmation of the proper sized bone plug. MINIARTHROTOMY ACL RECONSTRUCTION

The patellar tendon graft is longer than the native ACL, and therefore this "extra" length must be accommodated in one of the bony tunnels. Our full-length femoral tunnel can easily accommodate the extra tendon length.

PLACING THE GRAFT THROUGH THE TUNNELS Because the femoral tunnel has been made in a straight line with the tibial tunnel, the graft is easy to pass and does not abrade over the edge of the bony tunnel with knee motion. The passage of the graft bone plug should be simple, and the method of fixation should be easily performed without damage to the graft. The tibial bone plug is reserved to be passed into the femoral tunnel. With the tibial plug being straight, it passes easier into the femoral tunnel versus the curved patellar plug. The tibial tunnel is occupied by the 25-mm patellar bone plug. Because of the length of our femoral tunnel (50 to 80 mm), we do not have a problem with lateral femoral tunnel protrusion of our 25-mm tibial bone plug, and because we do not use interference screws for our fixation, the exact position of the bone plug in the tunnel is not critical. Using the suture passer from outside to inside, sutures of the patellar bone plug are passed through the tibial tunnel. These sutures are then used to pull the bone plug into the tibial tunnel with the cancellous surface of the patellar plug facing anteriorly. This places the at-

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TENSIONING OF THE GRAFT The goal of the ACL graft is to prevent instability while maintaining full ROM. The advantage of button fixation is noted when tensioning the graft. Adjustments can be made a number of times before the knots are tied. After final graft tensioning, the knee should have full hyperextension and full flexion and still be stable. Because the graft is most lax at 30° of flexion, we retighten the two throws in the tibial button sutures with the knee in this position. We desire to have both femoral and tibial buttons tight against the bone. The knee is taken through a ROM from hyperextension to full flexion (heel to buttock) (Fig 29). By performing the preparation of the notch and drilling of tunnels with the knee at 90° of flexion, the patellar tendon has already been "preloaded." If the graft was tensioned too tightly at 30°, then with full ROM the two throws of suture on the tibial button will loosen. This allows the graft enough "laxity" to achieve full ROM. By forcing the knee into full flexion after our initial graft fixation, we prevent overtightening the graft and capturing the joint postoperatively. After performing full ROM, we take the knee back to the 30° position and pull firmly on the tibial sutures to evaluate how far off the tibia we can lift the fixation button (Fig 30). This process acts as our "isometer." When the tunnels are properly placed, the button should remain tight against the tibia.

Fig 25. Passage of sutures through the bone graft.

tached portion of the patellar tendon graft most posteriorly. Because the tibial tunnel is somewhat funnel in shape, a "wedge fit" of the patellar bone plug within the tunnel is obtained. Once a snug fit has been obtained and the bone plug lies at the level of the joint surface of the tibial plateau, the patellar plug is secured into the tibial tunnel. This is accomplished by tying the three sets of sutures of the patellar plug over the polyethylene button (Fig 28). The advantage of using three sutures is this: if one suture breaks, adequate tunnel fixation will be maintained by the remaining two sutures tied over the button. Only two throws of sutures are made at this point to allow for easy untying of the suture for subsequent graft tensioning adjustment. The tibial plug is placed by passage of the sutures of the plug out the lateral side of the tunnel with the aid of a suture passer. Then, pulling on the sutures and guiding the tibial bone plug into the femoral tunnel with forceps, the tibial bone plug is passed. Again, the orientation of the plug is such that cancellous bone faces anteriorly placing the attached patellar graft tendon in the most posterior position. A tight fit of the bone plug in the tunnel has been assured by .the previous sizing of the plug. The graft is then secured on the femoral side by tying the three sutures over a polyethylene button. A full set of five throws are placed at this time, and the button is confirmed to lie flush on the lateral femoral cortex.

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Fig. 26. After harvesting both bone plugs, the remaining soft tissue connection to the patellar tendon graft is released. SHELBOURNE AND KLOOTWYK

Vicryl figure-8 stitch. A medium ConstaVac (Stryker, Kalamazoo, MI) drain is placed in both wounds. The iliotibial band is reapproximated with a Vicryl stitch. Standard skin closure is performed for both wounds. A light compressive dressing is applied, followed by a fuIl length lower extremity TED (KendaIl, Mansfield, MA) hose. The CryoCuff (Aircast, Inc, Summit, NJ) is applied, folIowed by a Tecnol postoperative splint (Tecnol, Inc, Fort Worth, TX). This postoperative dressing remains intact throughout the recovery room stay. When the patient arrives in the ward postoperatively, the splint is removed, and the knee is placed in a continuous passive motion machine with the CryoCuff left in place.

COMMENT The miniarthrotomy technique using a central one-third bone-patellar tendon-bone autograft with suture-andbutton fixation offers distinct advantages. There are three distinct advantages of the miniarthrotomyexposure. (1) The angle for drilling the femoral tunnel from an inside to outside fashion is enhanced when drilling medialIy to the patellar tendon. (2) The medial approach allows the guide wire to exit on the femur at a desirable lateral position. (3) By not relying on the tendon defect for exposure, the harvesting of the patelIar

Fig 27. The final Inspection of the patellar tendon graft.

If the button can be lifted off the tibia more than 1 or 2 mm, the sutures are retightened and the knee is again taken through full ROM. If the button again shows 1 to 2 mm of laxity, the tunnels are probably improperly placed. If the button has appropriate fit, the remaining throws in the sutures are placed. Five knots are tied.

COMPLETING THE PROCEDURE After securing both femoral and tibial buttons and being assured that the knee can be carried through a full ROM, the graft is inspected (Fig 31). Also, the new ACL is examined in full extension to ensure that no impingement in the notch occurs. If necessary, anterior notchplasty is performed with a no. 4 curette to allow full unimpinged extension. The tourniquet is deflated, and hemostasis is obtained with electrocautery. Copious irrigation of both wounds is performed. One quarter percent Marcaine with epinephrine is injected into the deep and subcutaneous tissues. The patellar tendon defect is loosely closed with a running Vicryl (Ethicon, Inc, Somerville, NJ) stitch incorporating the overlying peritenon. Reamings from the tunnels are placed first in the patellar and then in the tibial defects, and the preserved peritenon is closed in a running stitch fashion over the bone grafted areas. The miniarthrotomy is closed with a no. 1 MINIARTHROTOMY ACL RECONSTRUCTION

Fig 28. The sutures are tied Initially over the tibial button.

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Fig 29. (A and B) Once the graft is secured with both tibial and femoral buttons in place, the knee is taken through a full ROM.

tendon graft is delayed until the tunnels are prepared and sized. This delay allows for modification of the size of the bone plugs depending on the size of the bony tunnels.

Drilling of both the femoral and the tibial tunnels through an open technique allows significantly more cancellous bone to be harvested than when tunnels are drilled under arthroscopic guidance. The majority of the

Fig 30. Confirmation of tight tibial button fixation.

Fig 31. Final Inspection of the ACL graft.

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SHELBOURNE AND KLOOTWYK

bone can be lost with arthroscopic drilling because of fluid evacuation from the joint. The button fixation allows the surgeon to adjust the tension of the grafted ligament so that joint motion of the knee is ensured postoperatively. The graft can be retightened if unacceptable laxity is noted. The button lies directly on the surface of the bone and allows the tunnels to heal completely with bone. This advantage is realized in revision ACL surgery-new tunnels can be drilled without compromise in location because of the old tunnel defects that are present from previous screw fixation. Buttons do not appear on radiographs. Although the sutureand-button form of fixation is biomechanically weaker than interference screws or staples, we have not identified a single incidence of fixation failure in more than 1,300 ACL reconstructions performed using button fixation." The miniarthrotomy technique using a patellar tendonautograft and suture-and-button fixation for ACL reconstruction offers reproducible excellent results and remains our method of choice for ACL reconstruction surgery.

MINIARTHROTOMY ACL RECONSTRUCTION

REFERENCES 1. Arnoczky SP: Anatomy of the anterior cruciate ligament. C1in Orthop 172:19-25, 1983 2. Girgis FG: The cruciate ligaments of the knee joint. Clin Orthop 106:216-231, 1975

3. Clancy WG, Nelson DA, Reider B, et al: Anterior cruciate ligament reconstruction using one-third of the patellar ligament, augmented by extra-articular tendon transfers. J Bone [oint Surg [Am] 64:352359,1982

4. Penner DA, Daniel DM, Wood P, et al: An in vitro study of anterior cruciate ligament graft placement and isometry. Am J Sports Med 16:238-243, 1988 5. Arms SW, Pope MH, Johnson RJ, et al: The biomechanics of anterior cruciate ligament rehabilitation and reconstruction. Am J Sports Med 12:8-18, 1984

6. Howell SM, Clark JA, Farley TE: A rationale for predicting anterior cruciate graft impingemcnt by the intercondylar roof. Am J Sports Med 19:276-282, 1991 7. Kurosaka M, Yoshiya S, Andrish JT: A biomechanical comparison of different surgical techniques of graft fixation in anterior eructate ligament reconstruction. Am J Sports Med 15:225-229, 1987

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