Anterior cruciate ligament reconstruction: ANATOMICAL SINGLE-BUNDLE ENDOSCOPIC RECONSTRUCTION USING BONE–PATELLAR TENDON–BONE GRAFT

With the knee held in 90 degrees of flexion, make a 6-cm medial parapatellar incision starting inferior to the patella and extending distally medial to the tibial tuberosity. The length of this incision depends on the size of the patient.

Expose the patella and tendon by subcutaneous dissection.

Make a straight midline incision through the peritenon and dissect the peritenon from the patellar tendon, taking the flaps medially and laterally.

With the knee held flexed to maintain some tension on the patellar tendon, measure the width of the tendon.

Harvest a 10-mm-wide graft or one third of the tendon, whichever is smaller, from the central portion of the tendon extending distally from the palpable inferior tip of the patella. Maintain straight single-fiber plane incisions while harvesting the tendon. The size of the graft is individualized. For a large football lineman, an 11-mm graft may be indicated. For a small patient, a 9-mm or possibly an 8-mm graft and tunnels may be indicated.

Use an oscillating saw with a 1-cm-wide blade to make the bone cuts. Run the saw blade 15 degrees oblique to a line perpendicular to the anterior cortex of the patella, keeping 2 mm of the saw blade visible and making a cut 8 mm in depth. This cut should be about 10 mm wide × 17 mm long measured from the bony tip of the patella.

Make 25-mm-long cuts distally and free the tibial graft with a curved osteotome.

Flip the plug and place it back into the harvest site. Drill a 2-mm hole 3 mm from the distal tip of the plug and pass a no. 5 Tevdek suture (Deknatel OSP, Fall River, MA). An assistant should hold this at all times to ensure that the graft is not contaminated.

Complete the patellar cut with the saw placed at the inferior pole of the patella 7 to 8 mm deep and parallel to the anterior cortex.

Secure the graft to the top drape on a previously prepared table that holds appropriate-sized bone plug trials, rongeurs, a 2-mm drill bit, a Silastic block, a skin marker, no. 5 Tevdek sutures on Keith needles, and an 18-gauge steel wire.

Commercially available graft preparation boards make tensioning and graft preparation much easier.

Contour the graft with the rongeurs so that it fits through the 10-mm trial ensuring that the complete graft will pass through the trial.

Drill a single hole in the patellar plug about 3 mm from the end.

Bullet the end of the bone plug to make passage easier.

Drill a hole in the tibial bone plug. This plug should be 20 mm.

Place a no. 5 nonabsorbable suture through the better bone plug to be placed into the femoral tunnel and an 18-gauge wire through the other plug, which is placed into the tibial tunnel. The use of a wire prevents cut-out before firm fixation is obtained.

Mark the bone-tendon junction on the cancellous side of the graft at both ends with a methylene blue pencil and measure the total graft length. Wrap it in a sterile saline-soaked sponge and place it in a safe holding location.

Use electrocautery to make an inverted L-shaped flap through the tibial periosteum starting about 2.5 cm distal to the joint line and extending distally 1 cm medial to the tibial tuberosity.

Reflect the flap medially with a periosteal elevator to expose the proximal tibia for later placement of the tibial tunnel.

Make standard anteromedial and anterolateral arthroscopy portals, taking care not to damage the remaining portion of the patellar tendon.

Systematically examine the knee and evaluate and treat any associated intraarticular pathologic condition.

Perform meniscal suturing before securing the ACL graft.

With the arthroscope in the anterolateral portal and a 5.5-mm full-radius resector in the anteromedial portal, release the ligamentum mucosum and partially resect the fat pad to allow full exposure of the joint during the procedure.

Resect the soft tissue from the intercondylar notch and from the tibial stump by sliding the resector between the remaining stump of the ACL and the posterior cruciate ligament. The opening of the blade should always be pointed superiorly or laterally to avoid damage to the posterior cruciate ligament.

Leave the outline of the tibial and femoral footprint intact as a reference guide ( Fig. 14.2 ; A, ACL footprint through lateral parapatellar portal; B, from medial parapatellar portal). Visualize the lateral intercondylar ridge, the lateral bifurcate ridge, and the extent of the footprint that covers the lower third of the notch wall. Use an awl to make a hole slightly posterior to the center of the footprint so that the tunnel will have a 3-mm posterior wall and be about 3 mm superior to the articular cartilage in the posterosuperior aspect of the footprint just below the intercondylar ridge ( C ). After properly marking the footprint while visualizing from the anteromedial portal, the scope may be changed to the anterolateral portal and a small internal notchplasty can be performed to aid with graft placement.

With the knee in 30 degrees of flexion to expose the opening of the notch, evaluate the available space between the posterior cruciate ligament and lateral wall and the architecture of the roof. Use a 5.5-mm burr to enlarge the notch as indicated. The notch should be opened to look like an inverted U. Do not extend the notchplasty too far medially or superiorly, which would interfere with the patellofemoral articulation. Often the opening needs to be enlarged only 2 to 3 mm superiorly and laterally. The burr can be placed in reverse to remove the articular fringe and smooth the initial notchplasty.

As the notchplasty proceeds posteriorly, flex the knee from 45 to 60 degrees; when the notchplasty is complete, the knee should be at 90 degrees of flexion. Use controlled strokes with the burr from posterior to anterior. Posteriorly open the notch enough to accommodate the 10-mm endoscopic reamer. Smooth the edges of the tunnel by placing the burr in reverse or by using an arthroscopic rasp.

If transosseous drilling of the femoral tunnel is planned, the tibial tunnel will need to be placed at a 45-degree sagittal angle, starting just lateral to the medial collateral ligament. More acute angles tend to undercut the tibial articular suture and result in an oblique nonanatomical aperture. This does allow for a longer tibial tunnel and the anatomical femoral footprint can be successfully reamed about 60% of the time through the tibial tunnel. A low medial portal may be preferable to independently ream the femur in the posterosuperior aspect of the direct fibers of the ACL stump.

When placing the tibial guide intraarticularly, be aware of the intended tunnel length and direction so that the graft can be secured in an anatomical impingement-free position. Proper length and direction of the tunnel require a starting point approximately 1 cm proximal to the pes anserinus and about 1.5 cm medial to the tibial tuberosity to form a 30- to 40-degree angle with the shaft of the tibia. One should see this wire being directed to approach the femoral pilot ( Fig. 14.3 ).

When evaluating pin placement in a two-dimensional picture in the anteroposterior plane, ensure that the guidewire exits just anterior to a reference line extended medially from the inner edge of the lateral meniscus. This point should be approximately 7 mm anterior to the posterior cruciate ligament and 2 to 3 mm anterior to the peak of the medial spine just anterior to the center of the ACL footprint. In the mediolateral plane, ensure that the wire enters at the base of the medial spine or just slightly medial to the center of the ACL footprint ( Fig. 14.4 ).

The unaltered roof of the intercondylar notch normally forms an angle of 35 to 40 degrees with the long axis of the femur. To prevent impingement, an internal notchplasty, as previously described, may be necessary as is appropriate tunnel placement. Use the tibial and femoral landmarks described earlier and place the guide at 55 to 60 degrees to the tibial plateau surface to obtain sufficient tunnel length and an angle that allows the graft angle to approximate that of the original. Measure the tibial tunnel length directly off the guide calibrations and approximate the length of the tendinous portion of the graft. The tunnel length should be sufficient to allow at least 20 mm of bone to be secured in the tibial tunnel for stable fixation ( Fig. 14.5 ).

If the tendinous portion of the graft is 50 mm long or less, increase the guide angle to produce a longer tibial tunnel. The tunnel can be easily increased to 45 to 50 mm long to accommodate the longer graft.

Using the guide, advance the wire approximately 10 mm into the knee while observing through the arthroscope.

Place a clamp over the intraarticular end of the Kirschner wire to prevent advancement. Ream over the wire with a reamer 2 mm smaller than the intended final tunnel.

Leave the protruding end of the reamer in the tunnel and examine the tunnel for appropriate impingement-free position as the knee is moved through a full range of motion.

Make necessary adjustments with the 8-mm reamer.

Prevent bowstringing of the ACL graft over the posterior cruciate ligament by leaving a 2-mm posterior wall between the tibial tunnel and the posterior cruciate ligament. By directing the tunnel just lateral to the posterior cruciate ligament the graft lies on the posterior cruciate ligament without bowing around the ligament.

Ream the tunnel with a reamer the size of the graft and use the full radius resector to contour the edges of the tunnel and resect any remaining soft tissue that might block extension.

Place a rasp through the tunnel to complete contouring and ensure that the external portion of the tunnel is free of soft tissue.

Use a spinal needle to identify the best position for a low medial portal about 2.5 cm medial to the patellar tendon and just above the meniscus. A guide is placed to ensure that the tunnel is just anterior to the anteromedial bundle, that is, leaving a 3-mm posterior wall and about 3 mm from the femoral articular surface. Flex the knee 120 degrees and use a hemispherical reamer to avoid articular damage. Advance the reamer 1 mm and recheck the tunnel location. If it is in the desired location, ream a 30-mm tunnel if possible ( Fig. 14.6 ).

Carefully retract the reamer and remove it from the joint being careful not to enlarge the tunnel and ream out the posterior wall of the femur.

Smooth the edges of the femoral tunnel with a full radius resector.

Use the tunnel notcher to make a 25-mm-long slot per the guidewire.