Anterior Closing Wedge Proximal Tibial Osteotomy and Revision Anterior Cruciate Ligament Reconstruction With Quadriceps Tendon Autograft

Abstract

Background:

Anterior cruciate ligament (ACL) ruptures are among the most common injuries in young athletes and active adults. Reconstruction of the ACL most often leads to good functional outcomes and return to full activities. However, a number of patients experience ACL graft failures requiring revision surgery. The reasons for ACL graft failure are often multifactorial, though recent attention has been given to elevated posterior tibial slope (PTS) as a risk factor for recurrent ACL injuries.

Indications:

In patients with 2 or more ACL reconstruction failures with a PTS ≥12 degrees, anterior closing wedge proximal tibia osteotomy (ACWPTO) may be indicated to reduce the risk of recurrent ACL graft failure and allow return to full activities.

Technique Description:

This surgical technique video demonstrates the ACWPTO using a case example in a young athlete. Preoperative templating on lateral radiograph is used to determine the amount of correction for the closing wedge. The osteotomy is completed using K-wires and a free hand biplanar cutting technique with the tibial tubercle left in place. This is performed with a concomitant revision ACL reconstruction using quadriceps tendon autograft.

Results:

There are 2 small cases series published with good clinical outcomes and return to sport activities. No ACL graft failures were reported in either study with short-term follow-up.

Discussion:

In this surgical technique video, we review the literature indicating elevated PTS as a risk factor in ACL injuries and recurrent ACL graft failures. We highlight important technique pearls and pitfalls to avoid complications during the surgical demonstration. Finally, we review postoperative rehabilitation guidelines and clinical outcomes within the existing literature. In patients with recurrent ACL graft failures, ACWPTO provides a safe and reliable technique to correct an elevated PTS and return patients back to full activities with reduced risk of ACL graft re-tear.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This video describes our technique for anterior closing wedge proximal tibia osteotomy (ACWPTO) and revision anterior cruciate ligament (ACL) reconstruction with quadriceps tendon autograft.

Anterior closing wedge proximal tibia osteotomy has gained recent attention due to increased recognition of elevated posterior tibial slope (PTS) as a risk factor in ACL injury and ACL graft failure.

Quadriceps tendon autograft has also increased in popularity as a graft choice in both primary and revision ACL reconstruction.

This video will review a selection of the relevant literature, present our preferred technique, and review published outcomes along with a case presentation.

Cadaveric biomechanical studies have demonstrated a strong linear relationship between tibial slope and ACL graft forces. ¹ Slope reducing osteotomy was also demonstrated to reduce ACL graft forces. ⁶

A number of case control studies that are well summarized in a meta-analysis by Wang et al ¹⁰ have demonstrated increased tibial slope as a risk factor for sustaining an ACL injury.

Further studies have also identified elevated tibial slope as a risk factor for ACL graft failure, with this 20-year outcomes study identifying a tibial slope of 12 degrees or more as the strongest predictor of repeat ACL injury. ⁷ Perhaps most importantly, studies have also demonstrated that elevated tibial slope is associated with multiple ACL failures. ⁴ As we will review, these are the patients who are often indicated for anterior closing wedge osteotomy.

Our patient is an 18-year-old male athlete. After 2 previous ACL reconstructions, he is now presenting with recurrent instability after a non-contact football injury, concerning for a re-tear of his ACL graft. He had previous bone-patellar tendon-bone autograft and revision with soft tissue allograft. On examination, he has near full range of motion with a 2B Lachman and moderate pivot shift. The remainder of his examination is benign. Important aspects of his social history include that he is a senior in high school and wishes to play baseball in the winter and spring of this year. This will be his last year of competitive athletics, though he would like to continue to participate in recreational sports through college and remain active.

When seeing any patient with a third ACL tear, it is important to consider all causes of failure. We know from the Multicenter ACL Revision Study (MARS) group that the most common cause is trauma with technical errors being a close second with femoral tunnel malposition being the most common technical error. Often there is a combination of factors that can contribute to ACL failure.

In the case of our patient, weight-bearing anteroposterior, Rosenberg, lateral and sunrise views demonstrate previous ACL hardware. Screw in the femur from first BTB ACL appears to be a vertical femoral tunnel, though we can see the revision tunnel in a more anatomic position.

Single-leg weight-bearing lateral x-ray demonstrates more than 10 mm of anterior tibial translation compared to the uninjured left knee. Especially in the presence of an intact medial meniscus, this translation is an important measure of the impact of the elevated tibial slope.

This is the technique I prefer for measuring tibial slope on the lateral x-ray. I will measure 5 cm from the joint line and draw a circle at that point. And on a short lateral radiograph like this one I will draw my second circle as low as possible on the image. A line connecting the midpoint of these circles is used as the central tibial axis, and I then measure the angle of both the medial and lateral tibial plateau. In this case they both measured about 15 degrees.

Full length alignment x-rays demonstrate neutral mechanical axis.

The axial computed tomography (CT) scan demonstrates the femoral screw and the revision tunnel in a more anatomic position without widening. The tibial tunnel, however, is widened to about 15 mm at the widest point. 3D CT scan demonstrates the lateral tibial slope measures 14 degrees and femoral tunnel in a good position. The medial tibial slope measures 15 degrees, which corresponds with the x-ray measurements.

On magnetic resonance imaging (MRI), we can see the medial meniscus is intact, though a possible ramp lesion. The graft is re-torn. The lateral meniscus also appears intact.

In assessing the factors that contributed to a third ACL tear in this patient, the patient had a non-contact football injury. The tunnels of the revision appear in good position, though tunnel malposition may have contributed to his primary graft failure. Allograft was used for the revision in a 17-year-old athlete, which has higher failure rates. He also has significantly elevated medial and lateral PTS.

Indications for ACWPTO include a patient with ACL insufficiency with symptomatic instability who has elevated PTS, typically 12 degrees or higher and has had 2 or more ACL reconstruction failures. Having increased anterior tibial translation on single leg stance lateral x-ray helps demonstrate the impact of the elevated tibial slope on the biomechanics of the knee joint. If there is concomitant pathology, it should also be corrected. Primary contraindications include moderate to severe osteoarthritis (OA) and patients with generalized ligamentous laxity with genu recurvatum.

When planning for the anterior closing wedge osteotomy, how much should we correct? A general consensus of the currently published technique articles is to correct to about 8 degrees and avoid less than 5 degrees, which could increase the risk of posterior cruciate ligament (PCL) strain and avoid genu recurvatum.^2,3,5,8,9

For this case, I planned an 8 degree correction to reduce the PTS of the lateral and medial tibia to 8 and 7 degrees, respectively. This calculates to a 9.4 mm wedge of bone to remove from the anterior tibia.

Patient is positioned supine with a lateral thigh post at the level of the tourniquet and a foot post to maintain knee flexion of 90 degrees, and it is important to ensure the C-arm can obtain a perfect lateral x-ray without an assistant needing to hold the leg. We use general anesthesia, and I use a pericapsular injection. I like to use tranexamic acid (TXA) if there are no contraindications, and I typically do not use a tourniquet so I can monitor for bleeding throughout the case.

I try to use a midline approach, though always be mindful of previous incisions. We then expose the medial and lateral borders of the patella tendon. I then elevate the soft tissues medially, where there can be a lot of scar tissue from previous ACL reconstructions. Remove any previous hardware. On the lateral side, I will elevate the soft tissues at the level of Gerdy’s tubercle and try to stay above the anterior compartment musculature with my exposure.

I then place my top guide wires above the tibial tubercle, though at least 1 cm below the tibial plateau to preserve adequate bone for fixation. The key for this step was during the set up and now I can easily obtain a perfect lateral x-ray without an assistant holding the leg. I place the guide pins 1 to 2 mm from the borders of the patellar tendon. The second guide pin is placed in-line with the first pin. Now we use a ruler that I’ve cut to the desired length from my preoperative plan and will mark with the electrocautery.

The third and fourth guide wires are then placed just below the top guide wires with my goal for the pins to converge at the posterior cortex. Again, we are confirming the placement of each guide pin with fluoroscopy.

I use a smaller saw blade here from the micro instrument set (Conmed, Micro Sagittal Saw Cat. No. 5023-133, dimensions: length, 41 mm; width, 14 mm; thickness, 0.4 mm) to have better control and the key here is to start in line with your guide pin and then use the bone cut as your cutting guide to change the angle of your saw blade to complete the cut behind tubercle and along the cortices. Always have a blunt retractor deep to the soft tissues. I will check that the saw blade is perfectly flat on the lateral fluoro view. I will make the same cut on the lateral side and then use that cut as a guide to connect behind the tubercle. Then I will make the inferior saw cuts, again confirming that I am perfectly flat along the guide pin with fluoroscopy.

Now we have completed our saw cuts I will remove all of the guide pins. Then will make our retro-tubercle biplanar cut with the knee in extension to better protect the patellar tendon. The short saw blade is nice here as well, because you can bury it behind the tubercle.

I will with then use osteotomes to help complete the cortical cuts. Always checking on fluoro to ensure we are in a safe position. Generally, I will get a nice wedge of bone from the medial side. I will save this bone as potential bone graft for my ACL tunnels if needed. I will do the same on the lateral side with osteotome above and below the wedge and can remove a nice wedge of bone.

If the opening is large enough, you can use the arthroscope to visualize the osteotomy and use a small pituitary rongeur to remove excess bone. There is typically a lot of bone behind the tubercle and deeper in the osteotomy at the midline. I will check with fluoroscopy that we do not go too deep with the pituitary.

If the posterior cortex is still thick, you can postage stamp with a small drill bit. I am using a 2.0 drill bit for this case.

We will then place our lateral plate fixation (Synthes Mini Fragment 2.7mm LCP L-plate). I will place the proximal locking screws first using fluoroscopy to confirm we have adequate purchase in the proximal tibia. Then while holding the leg in full extension to close the osteotomy, I will place cortical screws distally to compress the osteotomy through the plate. On fluoroscopy, we can see that the osteotomy is nicely compressed.

We will then go back to the arthroscopy to complete our ACL tunnels. The tibial tunnel guide is placed into position and the guide pin is placed. A size 10 reamer is used to complete the tunnel. The arthroscope is used to visualize within the tunnel to ensure there is healthy bleeding bone circumferentially.

Attention is turned to medial plate fixation. A good tip here is to place the reamer into the tunnel while placing the screws to ensure they do not converge while placing the screws using fluoroscopy.

We will now drill our femoral tunnel with our drill guide in position. The flip cutter is drilled into place and the tunnel is retrograde reamed to a size 10. I will bring in the shaver to clear any bone debris or soft tissue in this case from the previous ACL graft. I will then visualize from the medial portal to ensure we have healthy circumferential bone and a passing suture is brought through the tunnel.

Now that we are happy with our tunnels, we turn attention to harvesting the quad tendon autograft. A 10-mm double blade is used to cut the tendon from proximal to distal. The bone cuts are then made using a small saw blade, and the bone block is harvested with an osteotome. I will prepare the bone block at this point to a size 10. Drill for a passing suture. I will harvest a partial thickness graft from the quad tendon and aim for an 85 to 90 mm total graft length.

We will now pass our graft into the joint. The soft tissue is on our femoral side. We have it marked at 20 mm to bring into our femoral tunnel. The graft is then fixed with a metal screw on the tibial side with the knee at full extension. We then ensure there is no graft impingement.

Here is a final fluoroscopic view showing the tibial interference screw.

Postoperatively, the most important thing during the early recovery period is to avoid any hyperextension of the knee. I will keep them in a brace for at least 6 weeks that will block extension. After 6 weeks they begin a standard ACL protocol which is available online.

Return-to-sport criteria is a standard ACL reconstruction protocol when the patient passes appropriate milestones.

At 6 weeks postoperatively, this patient’s x-rays demonstrate near-complete healing of the osteotomy. The lateral tibial slope has been corrected to about 6 degrees, and the medial slope to 7 degrees, which is within 1 to 2 degrees of our preoperative plan.

Here is a summary of the pearls and pitfalls we reviewed during the technique video.

There are several potential complications with this technique. Neurovascular injury would be a devastating complication, and the key is to prevent injury by careful placement of the guide pins and appropriate use of retractors and fluoroscopy to ensure instruments are safe. If you are concerned about recurvatum after the osteotomy, I recommend bracing the patient at 15 degrees of flexion for the first 4 to 6 weeks, though this requires close coordination with physical therapist to ensure patient does not get stiff and will allow the patient flexion range of motion as tolerated. You can also consider a posteromedial capsule advancement intraoperatively if the recurvatum is excessive. Extensor mechanism injuries and delayed union are other complications to avoid.

Outcomes reported in the literature are limited to small case series. This series of 5 patients who underwent combined anterior closing wedge osteotomy using a different technique that involves detachment and re-fixation of the tibial tubercle with revision ACL demonstrated significantly improved outcome scores, no complications, and no failures at a mean follow-up of 31 months in a young and active cohort of patients. ⁸

In this case series of 9 patients using a technique similar to that described here demonstrated that improved outcomes could be achieved without detaching the tibial tubercle. ² Again this was in a relatively young and active cohort. Both of these series are limited due to small sample size and lack of a comparison group, though as more surgeons learn to recognize and treat elevated PTS hopefully more outcomes will be reported.