Anterior cruciate ligament reconstruction with the endoscopic technique

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH THE ENDOSCOPIC TECHNIQUE CHARLES L. BECK, JR, MD, LONNIE E. PAULOS, MD, and THOMAS D. ROSENBERG, MD

Surgical care of the anterior cruciate ligament (ACL)-deficient knee has evolved toward arthroscopic techniques over the last 10 years in an effort to reduce morbidity. A recent modification of arthroscopic-assisted technique is the endoscopic technique. This technique allows for isometric placement of a variety of graft types into tibial and femoral drill holes placed under arthroscopic control. In most cases it allows for elimination of the lateral incision, allowing selection, measurement for isometry, reaming, and fixation at the femoral side via the tibial tunnel. With recent clinical use, there appears to be a substantial decrease in perioperative morbidity when compared with techniques that require a lateral incision. In this article, the endoscopic and two-incision techniques are described in detail, including modifications needed for various graft options. KEY WORDS: anterior cruciate ligament, endoscopic, arthroscopic, isometry

Surgical care of the anterior cruciate ligament (ACL)deficient knee has evolved dramatically over the past 15 years} Improvements in surgical technique and the understanding of biomechanics have allowed a corresponding improvement in results. 1"12 However, the significant morbidity associated with ACL repair and reconstruction has led to the development of arthroscopically assisted techniques in hopes of reducing those ill effects) "7'13"19 The same techniques that have been successfully used for open~ reconstruction have been adapted to the arthroscopic technique; likewise, some of the techniques that have been developed for use with arthroscopic assistance have b e e n a d a p t e d for u s e with a miniarthrotomy, which also seems to reduce morbidityfl '4As Whether the reconstructive technique involves an arthroscopic-assisted or a mini-arthrotomy method, certain parameters must be met in order to achieve reproducible stability as well as to minimize morbidity) "7 The technique should allow for variations in the anatomy of the notch and the ACL, as well as being adaptable to several graft options. Appropriate notchplasty must be carried out both to visualize the ACL femoral attachment site and to avoid impingement of the graft in the notch as the knee goes through a full range of motion. Tibial tunnel placement should be d e p e n d e n t on notch anatomy; conversely, the amount of notchplasty required superiorly will ultimately be determined by tibial tunnel placement. The femoral attachment site must be selected, based first on the tibial tunnel site and second on the tylSe of graft and its method of fixation} 7 The so-called isometric or From the Orthopedic Specialty Hospital, Salt Lake City, UT. Address reprint requests to Charles L. Beck, Jr, MD, 5848 South 300 East, Salt Lake City, UT 84107. Copyright 9 1992 by W. B. Saunders Company

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mechanical behavior of the particular site selected for the ligament substitute should be assessed before placement of the femoral tunnel because changes in its location have a significant effect on that behavior. 4's The technique used should not leave the knee open to the possibility of hyaline cartilage desiccation or of mechanical disruption by metal retractors used within the joint. Division of any portion of the quadriceps tendon, retinaculum, or joint capsule should be avoided except where absolutely necessary: at the portal sites or in the patella tendon defect. This is done in the hope of minimizing the disturbance of proprioceptive feedback and periarticular sensation as well as m a i n t a i n i n g n o r m a l p e r i a r t i c u l a r s u p p l e ~ ness. 1'13As Additionally, the level of pain postoperatively should facilitate the patient's early return home from the hospital and the beginning of aggressive rehabilitation) s A final benefit to the patient is that of cosmesis; patients are infinitely appreciative of smaller scars. The so-called endoscopic technique for ACL reconstruction, which is to be described in this article, is not a new technique; it is the result of an evolutionary process that has taken place over the past 10 years} 7"19 Improved instrumentation and improved understanding of graft materials and the requirements of isometric placement have led to modifications and improvements in the technique. The endoscopic technique is designed primarily for use with arthroscopic assistance; however, it is easily adaptable to the mini-arthrotomy technique. A potential benefit of the procedure is the elimination of the lateral exposure and its resultant morbidity. A second benefit is the elimination of "sundial" wear on the ACL substitute because of minimal tunnel divergence: the graft bends on its attachment site on the femur rather than rotating around that attachment site. The techniques described herein are not an attempt to editorialize on graft or instrument selection. The techniques are adaptable to a

Operative Techniques in Orthopaedics, Vol 2, No 2 (April), 1992: pp 86-98

variety of grafts; it should also be evident that a variety of tibial guide instrumentation can be used. In most cases, the femoral guide is replaced by the isometer. The techniques of using two incisions and outside-in reaming will also be described; the "endoscopic" technique evolved from these methods.

OPERATIVE TECHNIQUE The procedure may be performed under either regional or general anesthesia. After successful induction of anesthesia, the preoperative diagnosis is confirmed by examination of the affected knee. The patient is positioned in a supine position and a tourniquet !s applied to the proximal thigh 12 to 14 in above the jointline with adequate padding. The operative leg is placed into an arthroscopic leg holder applied over the tourniquet. An adequate sterile field proximal to the patella is required for passage of the femoral guide pin. A compression hose or elastic wrap is placed on the unaffected leg, and that leg is placed into a welMeg support that flexes, externally rotates and abducts the hip slightly, and flexes the knee, moving the well leg up and out of the surgical field. The foot of the table is dropped and the affected knee is allowed to flex (Fig 1). Standard prepping and draping techniques are used. Intravenous (IV) antibiotics are administered before the tourniquet is inflated. A sterile Esmarch bandage is then used to exsanguinate the affected leg and the tourniquet is elevated to 300 m m Hg.

Fig 1. Operating room setup and patient positioning. Note that the operative knee can flex to 110 ~ and extend fully. The thigh holder is applied at least 12 in proximal to the knee.

ENDOSCOPIC ACL RECONSTRUCTION

Anteromedial and anterolateral portals are established for diagnostic and operative arthroscopy. The outflow (or mechanical pump sensor) is placed in the superolateral or superomedial portal. Adequate flow and distention must be established for ACL reconstruction. This can be done using a 4- or 5-mm arthroscope in a 6.5-mm canula with gravity flow of the irrigation fluid through the arthroscopic sheath. Alternatively, a 4-mm scope and a 5- or 5.5-mm sheath can be used in conjunction with a mechanical pump.

Graft Harvest and Preparation Once meniscal and chondral pathology have been addressed, the ACL reconstruction is performed. If the technique is to be performed via mini-arthrotomy with patella tendon autograft, the graft is harvested at this time. If the arthroscopic technique is to be used with either patella tendon autograft, hamstring, or allograft, the surgeon may prefer to harvest the graft after the completion of the notchplasty and tibial and femoral tunnel placements in order to avoid possible desiccation of the graft. The technique of graft harvest is described here. For a bone-tendon-bone autograft, the patella tendon is exposed through a longitudinal incision extending from the anteromedial portal distally for a distance of 6 to 9 cm. The dissection is performed superiorly through the prepatella bursa, laterally just superficial to the peritenon, and distally superficial to the tubercle periosteum to keep the skin flaps as thick as possible. The peritenon is divided sharply in line with the fibers of the tendon and then dissected sharply away from the tendon medially, laterally, proximally, and distally to be preserved for closure later. The medial and lateral borders of the tendon are identified and the tendon width measured. The central one-third of the tendon is marked and then incised with a fresh scalpel to its bony insertion at both the tibial tubercle and the patella. Care must be taken to follow the normal tendon fiber orientation so that none of the fibers are transected. This results in a graft slightly wider at the patella side than at the tubercle side because of the natural distal narrowing of the tendon. A small oscillating saw is used to harvest the tibial tubercle attachment to a depth of 8 to 10 m m and a length of approximately 25 mm. A V4-in osteotome is used to complete the cuts at the proximal and distal ends of the tubercle and then to gently pry the tubercle free. The proximal cut will assure that the tubercle does not fragment in its mid portion during its elevation. The fat pad is now freed from the undersurface of the graft up to its attachment at the patella. The knee is brought into extension; with distal traction the patella can be exposed in the w o u n d without lengthening the wound proximally. The oscillating saw is used to harvest a 25-mm long by 5- to 8-mm deep bone plug from the patella, maintaining a width equal to that of the tendinous portion of the graft. The patellar bone plug is harvested as a rectangle rather than a wedge to minimize the stress-riser effect on the anterior surface of the patella. The graft is shaped to fit through the smallest possible sizing tubes. Excess bone is r e m o v e d by rongeur and then placed into the patella defect. The retinacular tissue is closed with a running 2.0 absorbable 87

suture. When using an arthroscopic technique, this graft harvest should be entirely extra-articular and the fat pad should not be violated in order to assure that adequate joint distention can be maintained for the remainder of the procedure. If a mini-arthrotomy is used, the fat pad is detached from its proximal attachment to the patella and retracted distally to afford a view of the notch. The graft is further prepared by drilling a single 2-mm hole anterior to posterior approximately 5 mm from the end of each bone plug and placing a no. 5 nonabsorbable suture through each hole. The diameters of the bone plugs are noted; the larger of the bone plugs will be used on the tibial side and the smaller on the femoral side to assure easy passage of the graft. Additionally, using a slightly smaller femoral drill hole will allow easier passage of the corresponding endoscopic reamer through the tibial tunnel. The graft is kept in a moistened sponge on the back table until implantation. If preferred, the hamstring tendons (semitendinosus and gracilis) are harvested through a 3.5- to 5-cm longitudinal incision immediately medial to the tibial tubercle and beginning approximately 3 cm below the jointline. The distal sartorius aponeurosis is identified and incised longitudinally in line with its fibers. The gracilis and semitendinosus are identified by palpation proximally where they are distinct. The semitendinosus is harvested by detaching it from its insertion on the tibia and then placing a no. 2 suture in a baseball-stitch fashion in the distal 2 to 3 cm of the tendon. This suture is then used for traction on the tendon while its expansion distally onto the tibia and the expansion into the gastrocnemius are incised sharply. With the knee at 90 ~ of flexion, the tendon and its aponeurosis are harvested with a tendon stripper, obtaining a free graft with a length between 28 and 32 cm. The gracilis may be harvested in a similar fashion if so desired. The semitendinous is prepared on the back table by using a curette to strip the remaining muscle from the aponeurosis. The aponeurotic portion is tubularized with 2.0 absorbable suture. The tendon can then be prepared into three or four 7- to 8-cm independent segments with whip sutures at either end or can be maintained as a single graft to be used in a double or looped fashion. The gracilis can be used in a similar double fashion to augment the semitendinous graft. The doubled tendons should have whip sutures placed at the free ends, and will be passed through the bone tunnels with either a Dacron tape or a doubled 18-gauge wire. The hamstring graft is n o w w r a p p e d in a moistened sponge and protected on the back table. With the use of an allograft, the tibial tunnel will r e quire a 2-cm incision on the anteromedial tibia immediately adjacent to the tibial tubercle and beginning approximately 1.5 to 2 cm below the jointline.

to the dimensions of the graft to be used. Excess removal of bone and articular cartilage should be avoided to minimize encroachment onto weightbearing or patellofemoral contact surfaces (Fig 2). The exposure of the notch is facilitated by selective debridement of the ACL stump and synovial tissue. Posterior cruciate ligament (PCL) injury must be avoided. Two to 3 mm of hyaline cartilage with underlying bone are removed from the superior and anterior portions of the distal notch outlet using a 1/4-in curved osteotome or gouge inserted through the anteromedial portal while viewing through the anterolateral portal with the knee flexed to approximately 45 ~. The lateral notch is similarly expanded 2 to 3 mm with the knee flexed to 90 ~ Osteochondral fragments are removed with a grasping forceps. At this point the ACL stump on the femur can be debrided with a no. 3 curette taking care to avoid expanding the posterior outlet. Final contouring of the notch is accomplished using a motorized burr, shaping the notch so that it cones down toward the posterior outlet. If the posterior outlet is widened, measuring the femoral tunnel site for isometry will be difficult because the isometric position may be altered and the subchondral cancellous bone will be too soft to hold the Isotac (Acufex Microsurgical, Norwood, MA). In many cases the lateral and distal extent of the notchplasty will partially expose the posterior horn of the lateral meniscus. The superior notchplasty should clearly avoid impingement at the proposed tibial attachment site when the knee is brought into full extension. The notchplasty is completed when the posterior drop-off or over-the-top point can be identified with a probe. The anterior intercondylar ridge may be a source of confusion in identifying the femoral anatomic site; the femoral anatomic attachment point is usually in a fossa just behind the anterior intercondylar ridge ("resident's ridge"). If the over-the-top region c a n n o t b e clearly identified, the notchplasty must be revised to remove this ridge (Fig 3).

Tibial Tunnel The tibial anatomic site is studied with the arthroscope in the anterolateral portal. The incisions previously described for graft harvest should provide adequate exposure for the external meatus of the tunnel. An aiming device (tibial guide) is placed through the anteromedial portal and impaled at the tibial anatomic attachment site. The appropriate spot is found on the anterolateral slope

Notchplasty The notchplasty is performed under either arthroscopic or direct visualization. In chronic ACL deficiency, osteophytes will often have developed in the superior and lateral portions of the notch and must be removed. In the acute setting, the notch may be congenitally stenotic. The dimensions of the notch must be considered relative 88

Fig 2. The shape of the notch determines the notchplasty. The proximal notch outlet is never expanded. (Reprinted with permission from Acufex Microsurgical, Inc.) BECK, PAULOS, AND ROSENBERG

Fig 3. Notchplasty. Probe marks over the top point. A flat roof has been produced and resident's ridge has been eliminated to expose the ACL origin.

of the medial intercondylar eminence. The site is best identified by bringing the knee into extension and selecting that point on the tibial attachment site just posterior to where the notch nears contact with the tibia. This maneuver can be repeated with the tip of the guide in place. The tip of the guide should be just posterior to the anterior notch in extension w h e n viewed arthroscopically. The lateral margin of the notch should also be cleared by the proposed tibial placement. The expected line of the guide pin is to hug but not impale the PCL and to be directed to a point just anterior to the over-the-top site high and central within the notch (Figs 4 and 5). This will require aligning the guide between 30~ and 60 ~ from a perpendicular to the tibia shaft and aiming slightly lat-

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Fig 5. Guide pin placement for tibial tunnel. Note orientation: Lateral notch is cleared, the pin enters the posterior half of the ACL tibial footprint, hugs the PCL, and is directed at the over-the-top position. Knee is flexed 90 ~ in this view from the anterolateral portal.

eral to midline. If interference screw-fixation is desired distally, the guide must be aligned at 50 ~to 60 ~ to produce a longer tibial tunnel (Fig 6). A 3,52-in guide pin is inserted into the selected site through the aiming device.

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/ Fig 4. The tibial aiming device is oriented to give the desired tibial tunnel length, aiming at a point just anterior to the over-the-top position and slightly lateral of midline. (Reprinted with permission from Acufex Microsurgical, Inc.)

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Fig 6. The red tunnel that forms an angle of 30 ~ perpendicular to the tiblal shaft is too short for consistent Interference fixation. The blue tunnel that forms an angle of between 50 ~ and 60 ~ perpendicular to the tiblal shaft will usually be long enough to allow interference fixation. (Reprinted with permission from Acufex Microsurgical, Inc.) ENDOSCOPIC ACL RECONSTRUCTION

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Fig 7. Guide pin placement. Knee in full extension with guide pin tucking into the superior notch.

The aiming device is then removed and the knee is brought into extension as a final check for tibial placement. The pin should not impinge but rather should tuck into the notch of Grant (Fig 7). If the appropriate placement point remains unclear, it is better to err slightly anteriorly and medially, avoiding the anterior horn of the medial meniscus. This should have negligible effects on isometry but may require additional superior expansion of the notch. If tibial tunnel placement is too posterior, the graft will be oriented too vertically and will not function effectively as a restraint to anterior tibial translation. If the tibial tunnel is oriented too vertically (more than 60~ off perpendicular to the tibial shaft), it may be impossible to reach the femoral attachment site with a guide pin or reamer. Once the tibial pin placement has been checked and deemed appropriate, the cannulated reamer corresponding to the largest size required for the graft is used over the 3/32-in guide pin from outside in (Fig 8). The tibial eminence bone is always denser than the underlying bone and will often force the reamer anterior as it breaks into the joint. Therefore, the intra-articular aperture must be selectively chamfered posteriorly and slightly laterally to prevent graft impingement or abrasion. All loose fragments are evacuated from the joint before proceeding further.

Isometry The femoral attachment site is identified with the aid of the Isotac and an isometer (Fig 9). At this time it is convenient to turn off the irrigation inflow and perform this part of the procedure "dry." If the synovium around the PCL or the posterior capsule impedes the view, this can be retracted with a probe inserted through the anteromedial portal. A sharp trochar-tip 3/32-in guide pin or an Isotac predrill (Fig 10) is used to mark the proposed site on the femur. The pin is passed through the tibial tunnel with the knee flexed between 70~ and 90 ~ and a hole is drilled to approximately two thirds the length of the trochar tip. (If the hole is drilled too deep, the Isotae will 90

Fig 8. Drilling of the tibial tunnel. Note that the reamer will enter the joint at the anteromedial slope of the tibial spine. (Reprinted with permission from Acufex Microsurgical, Inc.)

/ Fig 9. The Isotac or a similar device will allow measurement of the isometric point without a lateral incision. (Reprinted with permission from Acufex Microsurgical, Inc.)

not have an adequate bite in the subchondral bone). The custom-sized Isotac pre-drill point avoids the possibility of overdrilling. If the drill point passes too easily (ie, the drilling is being done in cancellous bone), the proposed site will probably be too anterior. The appropriate site is generally near the transition between the denser cortical bone at the over-the-top position and the softer cancellous bone anteriorly. Once the site has been predrilled, the Isotac or similar device is assembled with a no. 1 suture, passed through the tibial tunnel with the appropriate cannulated driver, BECK, PAULOS, AND ROSENBERG

in the initial placement, then the above procedure is repeated after selecting a new site. If tightening in terminal extension is greater than 3 mm, the site selected is too posterior (proximal) or may be too lateral and distal on the femur. A site slightly anterior and more central within the notch (at the 1-o'clock position for a left knee or the 11-o'clock position for a right knee) should be selected. If excess tightening occurs in flexion, then the site selected is too anterior (distal) and care must be taken to assure that the over-the-top position has been properly identified. The site will need to be moved posterior (proximal). The use of the isometer is not mandatory. However, in our experience at least 25% of the femoral sites initially selected at surgery have been subsequently changed during the procedure after use of the isometer. The isometer is useful in assuring that the femoral tunnel will be placed in the appropriate posterior (proximal) and central position in the notch rather than mistakenly placing the tunnel at "resident's ridge "5 or at a point too distal and lateral on the femoral condyle. The isometer is not helpful if the posterior cruciate ligament is insufficient or absent. Fig 10. The over-the-top point is identified and the Isotac pre-drill inserted 3 to 5 mm anterior to the drop off, just lateral to the midline of the notch. (Reprinted with permission from Acufex Microsurgical, Inc.)

and placed into the hole previously drilled, seating the stud to the hilt of the driver. The cannulated driver,is removed and the appropriate-sized centering plug and isometer are assembled onto the suture with a suture passer. The spring is then engaged (Fig 11). The knee is placed through a flexion/extension cycle one or two times to allow equalization of tension along the suture. The isometer is zeroed at 45 ~ of flexion, and the knee is taken into full extension then to maximum available flexion (usually about 110 ~ with the patient positioned as described). An acceptable position for the Isotac is one that allows I to 3 mm of elongation (tightening) in the final 20~ of extension and 0 to 1 mm of tightening in flexion past 90~ (Fig 12). This pattern most closely mimics the ACL signature. If acceptable measurements are not obtained

A Fig 11. Insertion of Isotac (A) and assembly of Isometer (B). (Reprinted with permission from Acufex Microsurgical, Inc.) ENDOSCOPIC ACL RECONSTRUCTION

Femoral Tunnel Placement of the femoral tunnel is dependent on the type of graft selected. If a graft with bone plugs is used, a 3/32-in guide pin is placed through the tibial tunnel and into the previously selected femoral attachment site (Fig 13). The pin is advanced just through the lateral femoral cortex with the knee flexed to at least 90 ~. If the knee is not flexed sufficiently, the guide pin and reamer may penetrate the popliteal space or produce a trough rather than a tunnel in the femur. The appropriate endoscopic drill bit is then manually passed over the pin, through the tibial tunnel, across the joint, and seated against the lateral condyle. The femoral tunnel (socket) is drilled with power to a depth 3 to 5 mm deeper than the length of the bone plug. The guide pin is removed, the socket irrigated, and a small Beathe-type pin placed with arthroscopic visualization through the tibial tunnel into the femoral socket. The Beathe pin is drilled with power allowing it to follow the previously drilled track through the lateral femoral cortex and a d v a n c e d m a n u a l l y through the muscle and skin of the anterolateral thigh. (This extra step can be eliminated by the use of a recently developed 3/32-in guide pin that has an eyelet or a slot at one end to allow passage of a suture.) If the graft to be used is tendinous, consideration should be made to placing the guide pin slightly posterior (by 2 to 3 mm) of the femoral site which was selected with the Isotac. This is done to keep the bulk of the tunnel (and therefore the graft) posterior to the isometric point; otherwise, the graft will lay against the front edge of the tunnel, placing the bulk of the graft anterior to the isometric point. 2's This adjustment becomes unnecessary if tunnels in the range of 6 to 7 mm are used on the femur; however, this adjustment is recommended if a 10-mm or larger tunnel is used for a tendinous graft. The size of the femoral reamer is d e t e r m i n e d by passing the graft through sizing tubes. The socket is then drilled in the same fashion as noted above to a depth of 1.5 to 2 cm. 91

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Fig 12. Precise identification of the isometric point. (A) Anteroposterior view. (B) Lateral view showing the isometric point (A) and points too anterior (B) and too distal (C). (C) Strain measurements of point A, central and proximal within the notch, most closely mimic the normal ACL signature. ~ , point A; . . . . , point B ; - - - , point C. (Reprinted with permission from Acufex Microsurgical, Inc.)

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The posterior wall of the socket may be "blown out" for a few millimeters at the over-the-top point; this should not affect fixation or healing. The following method is used if the surgeon decides to use an outside-in reaming technique with a lateral incision. The femoral attachment site within the joint is selected in the same manner with the isometer. The %2-in guide pin is placed through the tibial tunnel and into the femoral attachment site as noted previously. It is then advanced through the femur and out the skin of the anterolateral thigh. A 4-cm longitudinal incision is centered over this exit w o u n d and blunt dissection is used through the subcutaneous tissue, fascia, and quadriceps, down to the femur. A special obturator is available to perform this technique (Concept, Largo, FL). The soft-tissue path is maintained with deep retractors. A reamer with a tissue sleeve is inserted on the guide pin and the tunnel reamed to the appropriate diameter. This technique allows the surgeon to maintain nondivergent tibial tunnels in the anteroposterior plane. After irrigating the reamings from the wound, a doubled 18-gauge wire or suture passer is placed through the femoral tunnel across the joint and out the exit of the tibial tunnel for later graft passage. If the surgeon has elected to include lateral extra-articular surgery with the reconstruction, the reaming can be per92

formed through the standard straight lateral 6- to 8-cm incision on the distal femur; however, this requires substantial retraction of the quadriceps to allow engagement of the reamer over the guide pin placed in the straightshot fashion. A better alternative is to select the isometric point as noted above and use a femoral drill guide, such as the Acufex rear-entry guide or a similar device, to engage the femoral attachment site and allow placing the guide pin and reaming in the standard outside-in fashion. Graft

Insertion

B o n e - t e n d o n - b o n e graft. The no. 5 nonabsorbable suture in the tubercle end of the graft is passed through the eyelet of the Beathe or 3/32-in pin which is then advanced proximally through the thigh and out through the skin with pliers or a chuck. The suture is then used to pul! the graft through the tibial tunnel, across the joint, and into the femoral tunnel while visualizing arthroscopically through the anterolateral portal (Fig 14). A probe is inserted through the anteromedial portal to aid in positioning the bone plug as it begins to enter the femoral socket. The patella tendon graft is positioned so that the BECK, PAULOS, AND ROSENBERG

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Fig 13. Femoral reaming. (A) Insertion of a %2-in drill point into the isometric point. Note that because of the tibial angle, the drill lays against the posterior aspect of the internal meatus of the tiblal tunnel. (B) Inserting the reamer should be done manually to avoid deforming the guide pin. Reaming is accomplished to the desired depth. (C) The femoral tunnel should have either a thin 1- to 2-ram cortical wall posteriorly or a 3- to 5-mm periosteal-covered groove, confirming that the tunnel is just anterior to the over-the-top position. (Reprinted with permission from Acufex Microsurgical, Inc.)

tendinous portion of the graft is directly posterior and the bony cancellous portion is anterior. This facilitates placing the interference screw in the anterior portion of the femoral socket and avoids the possibility of cutting the tendinous portion of the graft with the screw or having the screw break out posteriorly. Additionally 9 it allows placement of the tendinous portion of the graft at or posterior to the previously measured isometric point. 2'5 Once the graft is properly oriented, it is seated with tension on the guide suture until the bone-tendon junction is flush with the opening of the femoral tunnel.

Hamstring tendon graft. If hamstring tendons are to be used, all of the sutures at one end of the composite graft (or the Dacron tape in the doubled semitendinosusgracilis graft) are passed through the eyelet of the guide pin and pulled through the pin tract and out the thigh as noted above. The graft is then fully seated into the socket with gentle proximally directed pressure. If the surgeon ENDOSCOPIC ACL RECONSTRUCTION

believes a full-length femoral tunnel is needed, the twoincision "straight-shot" technique described previously is used. The looped ends of the hamstring graft are brought out of the external exit of the femoral tunnel for fixation with a staple or screw and washer.

Graft Fixation Proximal fixation. The patella tendon autograft or allograft and Achilles tendon allograft are fixed in the femoral socket with an interference screw (Fig 15). A press-fitted, cannulated, or angled screwdriver will greatly facilitate this portion of the procedure. The interference screw should have a bullet point rather than a short, blunt conical point to assure easy engagement in the femoral tunnel. The knee is flexed to 90 ~ and the interference screw is introduced through the anterome93

be inserted into the anteromedial portal to move the screw butt laterally to make the screwdriver insertion easier. The knee is now flexed back to 90~to 100~ to bring the screw in line with the socket and bone plug (Fig 17), and the screw is advanced until it no longer can contact the tendinous portion of the graft. It will occasionally be necessary to back the screw out by one to two turns before bringing the screw into line with the socket if the screw has been seated too deeply initially. The dimensions of the screw should correspond to the size of the bone plug (usually 25-mm long and 7-mm wide, provided the bone plug fills the socket with 3 mm or less gap). 4 Care should be taken during this portion of the procedure to avoid placing the screw through the bone-tendon junction which will disrupt the graft. The screw will occasionally migrate laterally in the tunnel, or it may either pull the graft back into the joint or advance it further into the tunnel than desired. For these reasons, proximal and distal traction must be maintained on the guide sutures while the screw is inserted, and a small slot can be cut into the anterior edge of the tunnel with a punch or curette to serve as a guide for the screw. An alternative method is to use the recently available angled screwdriver (Concept, Largo, FL), which involves a similar technique to that just described; however, the screw can be placed parallel to the bone plug, entirely through the anteromedial portal without having to detach the screwdriver and redirect through the tibial tunnel. Another alternative method is to use a cannulated screw and screwdriver system. When performing this the guide pin is placed through the anteromedial portal and alongside the bone plug within the tunnel with the knee flexed 100~ or greater. The cannulated screw and screwdriver are then placed over the guide pin through

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Fig 14. Insertion of the graft. (A) A Beathe or slotted guide pin is used to pass the sutures out through the thigh. (B) The guide sutures are used to pull the graft into the full depth of the socket. (Reprinted with permission from Acufex Microsurgical, Inc.)

dial portal under direct visualization with the arthroscope in the anterolateral portal. One technique is to advance the screw through the fat pad with a clockwise rotation and insert the point one or two turns into the socket anterior to the bone plug, leaving the butt of the screw proud. The screw is then redirected to assure an adequate interference fit by removing the screwdriver and placing the screwdriver through the tibial tunnel anterior to the graft and into the joint (Fig 16). The knee is extended slowly until the screwdriver can enter the screw butt and be securely seated. If necessary, a grasper can

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Fig 15. Proximal fixation for bone4endon-bone graft. (A) Screw and press-fit driver inserted through anteromedial portal and introduced to anterior edge of femoral socket, inserting one to two turns. (B) Screwdriver removed from screw butt, inserted through anterior side of tibial tunnel, and reinserted into the screw butt with knee extended to approximately 40 ~ (C) With knee flexed back to 90 ~ the screw and driver are brought into line with the femoral socket, thus maximizing interference fit. (D) Alternatively, a cannulated screwdriver allows placement of the guide pin into the desired position in the femoral socket; the knee must be flexed to 100 ~ or greater to allow the proper screw orientation when the screw is passed through the anteromedial portal. If a cannulated screw driver is not available or if a screw driver is too large for step C, step A is used, followed by insertion of the screwdriver over the anterior lip of the tibia, through the fat pad, and superior to the anterior horn of the medial meniscus, thus bringing it into line with the femoral socket with the knee in approximately 100 ~ of flexion. (Reprinted with permission from Acufex Microsurgical, Inc.) 94

BECK, PAULOS, AND ROSENBERG

Fig 16. Redirection of interference screw. Screwdriver is placed through tibial tunnel and enters the joint anterior to the graft. Note orientation of screw, which has been partially inserted into femoral tunnel from the direction of the anteromedial portal.

the anteromedial portal and seated halfway into the tunnel. The guide pin must be removed at this point, or the tip may bend proximal to the screw tip as the screw is seated fully, making removal of the guide pin impossible. After the guide pin is removed, the screw is seated fully so that no metal is in contact with the tendinous portion of the graft. After any of these techniques, fixation must be checked to assure that the strength is adequate. This is done by grasping either the end of the graft at the exit of the tibial tunnel or the guide suture and pulling firmly three or four times while visualizing the graft arthroscopically or through the patella tendon defect. T h e graft should be

Fig 17. Reorientation of interference screw. Srewdriver has been inserted into interference screw and the knee has been brought back to 90 ~ of flexion with the screw now parallel to the graft and ready for completion of insertion.

ENDOSCOPIC ACL RECONSTRUCTION

stable without any evidence of motion or loosening. The proximal guide suture is now pulled in a proximal direction, in a straight line with the orientation of the graft, and removed with firm pressure. If the suture cannot be removed, it can be cut off subcutaneously. If an outside-in full-length tunnel method is used, at this point the graft is fixed with the screw passed from the outside-in. The graft is seated in an identical fashion to that noted previously with the bone-tendon junction flush with the internal meatus of the femoral tunnel. A cannulated or non-cannulated interference screw is used depending on the surgeon's preference. The screw is placed on the anterior (distal) aspect of the bone plug to assure appropriate orientation of the graft fibers within the tunnel. This is most easily performed with the cannulated interference screw; the guide pin is placed into the femoral tunnel proximally and observed arthroscopically to come in the joint on the anterior aspect of the graft. The screw is then driven to the appropriate depth, taking care to avoid having the tip of the screw go so deep as to enter the joint or come in contact with the bonetendon junction. In this way, compromise of the graft by the sharp point or threads of the screw can be avoided. Placement of the interference screw using this method can be difficult. Some surgeons may prefer to seat the bone plug more deeply in the tunnel and closer to the proximal meatus of the femoral tunnel so that it is more easily visualized and screw placement is facilitated. If the graft tissue does not fully fill the femoral tunnel, then the reader is referred to the previous section discussing eccentric tunnel placement to compensate for noneccentric placement of the graft (see Femoral Tunnel section). If hamstring tendons are used with an endoscopically placed femoral socket tunnel, fixation is accomplished by making a 3- to 5-crn incision in the lateral thigh, incising the iliotibial band and retracting the vastus lateralis anteriorly. The sutures or Dacron tape previously passed through the thigh are now brought back into the lateral w o u n d from beneath the quadriceps and tied over either a button or a screw and washer (Fig 18). The tendons should be seated in the full depth of the socket before fixation. If a full-length femoral tunnel has been used, the looped end of the tendons are now fixed over a screw and spiked washer or a staple or the Dacron tape used for passage may be tied over hardware depending on the surgeon's preference.

Fig 18. Tripled semitendinosus technique with proximal fixation over a button and distal fixation over a screw and washer post. (Reprinted with permission from Acufex Microsurgical, Inc.)

95

Fig 20. Distal fixation of bone-tendon-bone graft. (A) If majority of bone plug is contained within tibial tunnel, then interference screw fixation can be used. (B) If bone plug is not well contained within the tibial tunnel, the graft is fixed into a trough at the exit of the tunnel with sutures over a screw and washer or staples directly over the bone plug. (Reprinted with permission from Acufex Microsurgical, Inc.) Fig 19. Twisting of graft fibers to ensure evenly distributed tension. An added benefit is shortening of the graft length, which makes interference screw fixation in the tibia more likely.

Distal Fixation Before distal fixation the knee is placed through a range of motion with the arthroscope in the anterolateral portal to confirm the absence of graft impingement within the notch. If impingement does occur in terminal extension (ie, 0~ the notch should be expanded accordingly. If placement on the femoral side has been appropriate, the graft will tighten I to 2 mm as the knee goes through the final 20 ~ of extension and should not noticeably tighten as the knee is flexed past 90 ~. With patella tendon or allograft tissue, the graft should be internally rotated to more evenly distribute tension and assure that the entire graft is loaded (Fig 19). This is accomplished by grasping the distal bone plug and internally rotating it away from the lateral femoral condyle (clockwise for the right knee and counterclockwise for the left knee) under arthroscopic visualization; the intraarticular portion of the graft should rotate at least 90 ~. The knee should be cycled several times with tension on the graft to assure that the fibers twist evenly throughout the length of the graft. The knee is then brought into full extension and 2 to 4 lbs of tension are applied to the graft with distal traction. 4 If at least half the length of the bone plug is within the tibial tunnel, an interference screw may be used, placing the appropriate-sized screw on the cancellous side of the bone plug to avoid cutting the tendinous portion of the graft. The screw should be placed in the posterior aspect of the tunnel to ensure the greatest length of contact. If secure fixation cannot be accomplished with the interference technique, the graft is fixed into a shallow I x 2-cm trough cut at the distal side of the exit of the tibial tunnel (Fig 20). A small portion of the bone at the proximal edge of the trough is removed to prevent any sharp edges from touching the graft. The base of the trough is evenly depressed 4 to 5 mm with an impactor. The distal bone plug is then laid into this trough under appropriate tension and fixed with two distally directed medium staples or with two or more no. 5 nonabsorbable sutures tied over a screw and washer.

96

Examination of the graft with a probe is performed arthroscopically at this point to assure that satisfactory tension is maintained on the graft. If tension has been lost during fixation, then the fixation must be revised. Tensioning the graft in full extension assures that the knee will not be captured by an over-tensioned graft. When a tendinous graft has been used, the graft is fixed distally under a spiked washer and screw or a staple if the graft length is adequate. Alternatively, fixation can be accomplished with guide sutures tied over a screw and washer. Eight to 10 lbs of tension should be applied to a tendinous graft with the knee in extension at the time of fixation. 4 Bone grafting of the tibial tunnel may be performed at this time if there is greater than a 4- to 5-mm gap between the tunnel wall and the graft. If necessary, extra-articular surgery and collateral ligament repair are completed at this time.

Wound Closure All w o u n d s are irrigated with saline and antibiotic solution. The tourniquet is deflated and the thigh-holding device is loosened. Hemostasis is achieved with electrocautery. Closure is accomplished in a layered fashion, closing periosteum where possible with 0 absorbable suture; subcutaneous and retinacular layers are closed with 2.0 absorbable sutures. The skin is approximated with a subcuticular running suture. Arthroscopic portals are closed with 3.0 absorbable suture placed subcutaneously. If hemostasis is questionable, particularly if a lateral w o u n d was required for fixation, a drain should be considered for that wound. A sterile dressing is applied along with an appropriately sized compression hose. A postoperative rehabilitation brace is placed and locked at 10~ of flexion. The patient is then awakened from anesthesia and transferred to the recovery room.

POSTOPERATIVE MANAGEMENT The most dramatic benefits to be noted from the endoscopic technique are manifested in the immediate postoperative period. Most patients can be managed with BECK, PAULOS, AND ROSENBERG

intramuscular analgesics for the first 12 to 24 hours and then tapered to oral analgesics. With the new intramuscular nonsteroidal anti-inflammatory agents, many patients progress directly to oral analgesics and are able to avoid other intramuscular (IM) or IV pain medication. IV antibiotics are maintained for 24 hours postoperatively. If a drain was used, it is removed the morning after surgery. Physical therapy is initiated on postoperative day 1. Weight-bearing status is determined by the graft used, the fixation, and by any concomitant meniscal or chondral pathology. In the case of an isolated ACL reconstruction with a securely fixed patella tendon autograft or allograft, weight bearing is allowed to tolerance immediately. The brace is locked at 10 ~ to prevent hyperextension and reflex quadriceps contraction with sudden flexion. Straight-leg raises with the brace locked at 40 ~, isometric exercises and co-contractions, passive range-ofmotion exercises from full extension to at least 90 ~ flexion, patella mobility exercises, and active ankle and calf exercises are initiated as soon as possible after surgery. The patient may be discharged from the hospital when he is confident on crutches, including stair ambulation, comfortable taking oral analgesics, and able to perform range-of-motion exercises three to four times daily. The use of the endoscopic technique has reduced the hospitalization time dramatically in our experience. Whereas patients who received a reconstruction technique requiring a lateral incision routinely required 2 to 3 days of ACL PROTOCOL

hospitalization, most endoscopically treated patients are able to be discharged after a single night in the hospital. Outpatient treatment is also possible particularly if home nursing care is available.

REHABILITATION The patient is seen 5 to 7 days postoperatively for suture removal and a physical therapy prescription. The rehabilitation prescription must be individualized based on the patient's associated ligamentous, meniscal, and chondral injuries as well as taking into account general alignment and joint laxity patterns. General guidelines include crutch-assisted ambulation for 2 to 6 weeks postoperatively and active range of motion immediately postoperatively from 40 ~ to 90 ~ increasing this by 5 ~ to 10 ~ in each direction weekly after the initial 3 weeks postoperatively. Passive range of motion should be gradually increased to full range of motion by postoperative weeks 6 to 8. A functional exercise program is instituted as soon as the patient is able to tolerate weight bearing, ie, 2 to 6 weeks postoperation. A jogging program is begun by 16 to 20 weeks postoperatively, and progressive jumping, cutting, and twisting exercises are gradually added over the ensuing 2 to 3 months. As a general guideline, by 5 to 6 months a functional knee brace is fitted and return to sports-specific activity is allowed gradually. Full return to sports without limitation is generally withheld for 9

IIIIIII

Post O p W e e k Date:

Charte~ L Beck, M.D.

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STRENGTH TRAINING

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WEEK

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Hantcurls - s~ttJng -

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9 R a n g e of m o t l o n 0 ~ to 140 ~

THE ORTHOPEDIC SPECIALTYHOSPITAL 5648 South 300 East Salt Lake City, Utah 84107

(801) 269-4100

Fig 21. Rehabilitation prescription for bone-tendon-bone ACL reconstruction without meniscus repair. ENDOSCOPIC ACL RECONSTRUCTION

97

m o n t h s p o s t o p e r a t i o n ; the p a t i e n t is e n c o u r a g e d to w e a r a f u n c t i o n a l k n e e brace for s p o r t s for a p p r o x i m a t e l y 12 m o n t h s after r e t u r n to athletic participation. R e c e n t histological s t u d i e s o n allograft a n d a u t o g r a f t h e a l i n g at o u r institution s u p p o r t this p r o l o n g e d p r o t e c t i o n as graft vascularity a n d r e m o d e l i n g o c c u r s o v e r a p e r i o d of m o n t h s to years, especially w i t h allograft tissue. A rehabilitation p r e s c r i p t i o n f o r m is i n c l u d e d for a t y p ical p a t e l l a t e n d o n a u t o g r a f t A C L r e c o n s t r u c t i o n (Fig 21). 16 If a t e n d i n o u s graft fixed w i t h s u t u r e h a s b e e n used, the immobility phase and progressive weightb e a r i n g p r e s c r i p t i o n s h o u l d be altered t o w a r d a l o n g e r a n d m o r e c o n s e r v a t i v e time s c h e d u l e .

SUMMARY A r t h r o s c o p i c a l l y a s s i s t e d A C L r e c o n s t r u c t i o n w i t h a n end o s c o p i c t e c h n i q u e a p p e a r s to offer a significantly d i m i n i s h e d m o r b i d i t y for the p a t i e n t as well as a predictable a n d r e p r o d u c i b l e t e c h n i q u e for t h e s u r g e o n . T h e e n d o scopic t e c h n i q u e c a n be a d a p t e d to a m i n i - a r t h r o t o m y t e c h n i q u e a n d p r o b a b l y a c h i e v e t h e s a m e benefits. It is n o t a n e w t e c h n i q u e b u t r a t h e r i n c o r p o r a t e s several imp r o v e m e n t s in the original o p e n t e c h n i q u e a n d is p a r t of a continuing evolutionary process.

REFERENCES 1. lhle CJ, Jackson JW: Intraarticular surgical considerations, in Jackson DW, Drez D (eds): Anterior Cruciate Deficient Knee. St Louis, MO, Mosby, 1987, pp 142-167 2. Clancy WG, Nelson DA, Reider B, et al: Anterior cruciate ligament reconstruction using one-third of the patella ligament augmented by extraarticular tendon transfers. J Bone Joint Surg [Am] 64-A:352359, 1982 3. Clancy WG, Ray JM, Zoltan DJ: Acute tears of the anterior cruciate ligament. J Bone Joint Surg [Am] 70-A:1483-1488, 1988 4. Daniel DM: Principles of knee ligament surgery, in Daniel D, Akeson W, O'Connor J (eds): Knee Ligaments. Structure, Function, Injury and Repair. New York, NY, Raven, 1990, pp 11-29

98

5. Graf B: Isometric placement of substitutes for the anterior cruciate ligament, in Jackson DW, Drez D (eds): The Anterior Cruciate Deficient Knee. St Louis, MO, Mosby, 1987, pp 102-113 6. Indelicato PA, Bittar ES, Prevot TJ, et al: Clinical comparison of freeze-dried and fresh-frozen patella tendon allografts for anterior cruciate ligament reconstruction of the knee. Am J Sports Med 18:335-342, 1990 7. Jackson DW, Reiman PR: Principles of arthroscopic anterior cruciate reconstruction, in Jackson DW, Drez D (eds): The Anterior Cruciate Deficient Knee. St Louis, MO, Mosby, 1987, pp 273-285 8. Lipscomb AB, Johnston RK, Snyder RB, et al: Secondary reconstruction of the anterior cruciate ligament in athletes by using the semitendinosus tendon: A preliminary report of 78 cases. Am J Sports Med 7:81-84, 1979 9. Noyes FR, Barber SD, Mangine RE: Bone-patellar ligament-bone and fascia lata allografts for reconstruction of the anterior cruciate ligament. J Bone Joint Surg [Am] 72-A:1125-1136, 1990 10. O'Brien SJ, Warren RF, Pavlov H, et al: Reconstruction of the chronically insufficient anterior cruciate ligament with the central third of the patellar ligament. J Bone Joint Surg [Am] 73-A:278-286, 1991 11. Shelbourne KD, Nitz P: Accelerated rehabilitation after anterior crudate ligament reconstruction. Am J Sports Med 18:292-299, 1990 12. Shino K, Inoue M, Horibe S, et al: Reconstruction of the anterior cruciate ligament using allogeneic tendon. Long-term follow-up. Am J Sports Med 18:457-465, 1990 13. Graf B, Uhr F: Complications of intraarticular anterior cruciate ligament reconstruction. Clin Sports Med 7:835-848, 1988 14. Harner CD, Paul JJ, Fu FH, et al: Loss of knee motion following arthroscopic anterior cruciate ligament reconstruction. Presented at 58th annual meeting of American Academy of Orthopaedic Surgeons, Anaheim, CA, March, 1991 15. Ott JW, Graf BK, Keene JS, et al: Risk factors for restricted motion after anterior cruciate ligament reconstruction: A retrospective study of 373 patients. Presented at the 58th annual meeting of the American Academy of Orthopaedic Surgeons, Anaheim, CA, March, 1991 16. Paulos LE, Rosenberg TD, Drawbert J, et al: Infrapatella contracture syndrome. An unrecognized cause of knee stiffness with patella entrapment and patella infera. Am J Sports Med 15:331-341, 1987 17. Rosenberg TD: Arthroscopic Technique for Anterior Cruciate Ligament Surgery, Technical Bulletin. Nonvood, MA, Acufex Microsurgical, 1984 18. Rosenberg TD: Arthroscopic Technique for Anterior Cruciate Ligament Reconstruction, Technical Bulletin. Norwood, MA, Acufex Microsurgical, 1988 19. Rosenberg TD: Technique For Endoscopic Method Of ACL Reconstruction, Technical Bulletin. Nonvood, MA, Acufex Microsurgical, 1989

BECK, PAULOS, AND ROSENBERG