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Arthroscopic ACL Reconstruction with Bone Patellar Bone Graft using Anteromedial Technique

Xinning "Tiger" Li, MD, Nathan D. Orvets, MD
Boston University School of Medicine - Boston Medical Center

Anesthesia

  1. General endotrachial anesthesia. (Sedation and Spinal is another option)
  2. No femoral block for ACL reconstruction due to quadriceps inhibition in the postoperative period.

1. Examination Under Anesthesia

  1. Range of Motion, Varus/Valgus Stress, Lachman and Pivot Shift Test
    • Before beginning surgery, an examination under anesthesia is performed. It is essential to evaluate ROM, Lachman test and Pivot Shift before starting surgery or graft harvest.
  2. Compare to Contralateral Leg

2. Patella Graft Harvest

  • Patient is positioned supine on a regular operating room table with a post on the ipsilateral mid thigh.
  • A tourniquet is applied snugly as far proximal on the thigh as feasible.
  • After skin preparation and draping, a 5 to 7 cm midline knee incision centered over the patellar tendon is marked with a skin marker (BTB can also be harvested with horizontal incision).
  • The limb is exsanguinated and the tourniquet inflated to 250 mmHG.
  1. Anatomic Landmarks
    • A 5 to 7 cm midline incision is made over the patellar tendon with a #15 scalpel.
  2. Skin Incision and Dissection Down to Patellar Tendon
    • Dissection is carried down to the paratenon which is carefully reflected off the underlying tendon and preserved for repair. (Use a #15 scalpel to dissect the paratenon).
  3. Mark and Measure Graft
  4. Cut Graft
    • Using a #10 scalpel, 10 mm central third patellar tendon is harvested extending from the patella to the tibial tuberosity with the knee in flexion, and then dissection is completed with the knee in extension.
  5. Saw to Remove Graft
    • A 10x25 mm bone block is taken from both the patella and the tibia using a micro oscillating saw taking care not to cut deeper than 15 mm so as to prevent an iatrogenic fracture.
  6. Use Osteotome and Mallet
  7. Use Metzenbaum Scissors to Remove Graft
  8. Femoral Graft Cuts with Saw
  9. Use Osteotome to Free Graft

3. Prepare Graft

  1. Measure
    • Bone blocks are carefully removed with a curved osteotome.
  2. Trim and Sequentially Size Femoral Side
    • The graft diameter is carefully measured on the back table. Bone block is shaped with a ronguer to fit through a 10 mm tunnel for the femur and 10.5 mm tunnel for the tibia.
    • It is important that the bone plug goes through the 10 mm sizer easily to allow passage of the graft.
    • The plug is shaped to match a bullet for the femoral side to further allow turning of the graft to go into the femoral tunnel with ease.
  3. Trim and Sequentially Size Tibial Side
    • The bone block is placed in Bacitracin solution for 10 mins.

4. Femoral Tunnel Placement

  1. Diagnostic Arthroscopy
    • An anterolateral portal is established with the assistance of an 18 gauge spinal needle using an outside-in technique. The portal is just above the meniscus and it is essential to check the trajectory of the needle and make sure it is directed to the footprint of the ACL on the femoral side.
    • An anteromedial portal is then established with an #11 blade, and capsulotomy is performed cutting from an inferior to superior direction with the blade facing up. It is positioned just above the medial meniscus to allow adequate visualization of the femoral ACL footprint.
    • A thorough diagnostic arthroscopy is performed closely examining the patellofemoral, medial and lateral compartments.
    • Any meniscal pathology is addressed with either repair or partial menisectomy depending on the tear type and location.
    • The torn ACL remnant is debrided with ArthroCare device and shaver. A small notchplasty is done to allow improved visualization.
    • Alternatively, the senior author prefers the trans-notch portal through the patella tendon harvest site. This viewing portal allows excellent visualization of the ACL footprint for drilling.
  2. Notchplasty
    • A small notchplasty is performed with a high-speed burr until adequate visualization of the femoral footprint is established. An aggressive notchplasty is not critical as long as the tunnel positions are easily identifiable and there is no graft impingement in full extension.
  3. Use Arthroscopic Awl
    • The back wall of the femur is identified after debridement of the soft tissue. The anatomic position for ACL on the femoral side is located at the 10 to 10:30 position for a right knee (1 to 1:30 position for a left knee).
  4. Use Guide and Drill Tunnel
    • A femoral tunnel over the top guide is used to help retain 1 to 2 mm of posterior wall following drilling. If drilling a 10 mm tunnel, a 6 or 7 mm offset guide should be used. The senior author prefers a 2 mm back wall. (7 mm over the top guide)
  5. Flexible Reamer
    • The femoral tunnel is drilled through the anteromedial portal with the use of a flexible reamer (Stryker Versitomic Reamers) to match the width and depth as the bone block (10 mm diameter and 25 mm depth in this case). The senior author prefers to make the bone plug for the femoral side to measure 9.5 mm in diameter and 23 mm in length to allow ease of passage.
  6. Pass Suture Through Tunnel
    • A #2 fiberwire is shuttled through the femoral tunnel to help assist in graft passage.

5. Tibial Tunnel Placement

  1. Use Tibial Guide on Plateau
    • Setting of the tibial guide is dependent on the length of the patella tendon. The rule is add 10 degrees to the patella tendon length. Typically, the tibial guide is set at 55 to 60 degrees.
  2. Drill Tibial Tunnel
    • A tibial tunnel drill guide is positioned such that the tunnel is located at the center of the native ACL footprint. This should also be adjacent to the slope of the medial eminence and along a line extended from the posterior border of the anterior horn of the lateral meniscus.
    • The obliquity of the ACL is restored when the guide pin is slightly on the medial tibial eminence.
    • The guide wire is placed and the tunnel is drilled with a 10.5 mm diameter drill bit.
  3. Ream Tunnel
  4. Clear Tunnel of Soft Tissue
    • Soft tissue from both tunnels is cleared with the ArthroCare.

6. Place, Tension, and Secure Graft

  1. Final Graft Preparations
  2. Graft Inserted
    • Shuttle sutures are placed through both bone plugs and the graft is passed into the tibial tunnel and then to the femoral tunnel.
    • A needle driver or grasper maybe used to help turn the graft on the femoral side if difficulty is encountered
  3. Femoral Interference Screw
    • An interference screw is placed in the tibial tunnel after tensioning is complete, and the knee is placed in 20 degree flexion. The senior author prefers to use a 8 mm x 25 mm screw if the tunnel is drilled to 10.5 mm in diameter.
  4. Assess Knee
  5. Cycle Knee to Tension Graft
    • The graft is tensioned by repetitively cycling the knee through a complete range of motion (20 cycles).
  6. Fixation of Tibial Side with Interference Screw
    • An interference screw is used to fix the femoral side superior to the graft. The senior author prefers to use a 7 mm x 20 mm screw if the tunnel is drilled 10 mm x 25 mm in size.
  7. Check for Impingement
    • Knee is evaluated one more time with the Lachman test to assess for graft stability.

7. Closure

  • The paratenon is carefully closed with buried #0 vicryl suture. In addition, the patella tendon is also closed with interrupted #0 vicryl sutures in a buried fashion.
  • Place previously collected bone graft in the patellar defect.
  • Skin is closed with running 3-0 monocryl with Steri-Strips.
  • A dry sterile dressing and ice therapy device is applied, and knee brace locked in extension are applied before leaving the operating room.

Postoperative Protocol

  • Partial weight bearing in a hinged knee brace locked in extension for 4 weeks.
  • Brace is opened 0 to 90 from 4 weeks to 6 weeks and completely opened after 6 weeks.
  • Patient may transition to a smaller post operative knee brace at 8 weeks after surgery (Road runner ACL brace).
  • Post operative follow-up visits are normally scheduled at 2 weeks, 6 weeks, 3 months, 6 months, and 1 year after surgery.
  • Range of motion and physical therapy are typically started 2 weeks post-operatively.
  • Patients may begin jogging at 3 to 4 months depending on progress and may resume sports between 6 months to 9 months depending on the type of sport and also when full quadriceps strength returns.