Abstract
Background:
When evaluating a patient with a failed anterior cruciate ligament (ACL) reconstruction, a detailed history and physical examination is paramount. The position and size of original femoral and tibial tunnels are critical in the surgical decision-making in the setting of revision ACL reconstruction. This video presents a case of stage I revision ACL reconstruction with the use of allograft bone dowels due to increased size and poor position of original fixation tunnels.
Indications:
Indications for staging revision ACL reconstruction include significant tunnel osteolysis or dilation (>14 mm), or any situation in which the previous bone tunnels will interfere with anatomic graft placement and fixation.
Technique Description:
The patient is placed in the supine position with a standard setup for knee arthroscopy, including lateral thigh post and foot stop for maintained knee flexion at 90°. After diagnostic arthroscopy, the ACL graft remnant is debrided. The femoral tunnel is then debrided and re-cannulated, followed by reaming with cannulated reamers until adequate cortical chatter is achieved, ensuring the presence of a bleeding rim of bone throughout the tunnel to confirm that the correct diameter reamer has been reached. The appropriately sized bone dowel is inserted along the guide pin until fully seated and flush with lateral wall of the notch. This process is then repeated for the tibial tunnel, accessing the tunnel from the previous incision along the medial tibia.
Results:
This video presents a technique to achieve adequate bone grafting of previously used tunnels that are not suitable for single-stage revision ACL reconstruction. Patients undergo second-stage revision ACL reconstruction at roughly 4 to 6 months following stage I, when bone graft has fully incorporated on radiographs.
Discussion/Conclusion:
Stage I revision ACL reconstruction with tunnel grafting using allograft bone dowels is a minimally invasive method of grafting previously used fixation tunnels to allow for anatomic second-stage graft placement and fixation.
Patient Consent Disclosure Statement:
The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.
This is a visual representation of the abstract.
Video Transcript
Hi, my name is Steve Marcaccio, and together with Dr Robin Dunn, Dr Justin Arner, and Dr James Bradley, we will present our technique for stage I revision anterior cruciate ligament (ACL) reconstruction with allograft bone dowels. These are our disclosures.
When evaluating a patient with a failed ACL reconstruction, the most critical aspects of the workup are a thorough history and a careful physical examination. What graft was used during the index surgery? Did their knee ever feel stable afterward? What was the mechanism of re-injury? On examination, it is important to note the location of previous incisions, the patient’s overall standing alignment, their quadriceps tone, whether they have laxity with the Lachman, anterior drawer, or pivot shift testing, and any evidence of missed concomitant injuries such as posterolateral corner injury. 2 We routinely obtain standing anteroposterior (AP), lateral, flexion posteroanterior, and merchant radiographs of the affected knee to critically assess the position and size of the original femoral and tibial tunnels, as well as the type of fixation used.3,6 Furthermore, we routinely obtain full-length alignment films, including a full-length lateral film of the tibia, to evaluate coronal alignment and tibial slope. Overall, our goal is not to miss any underlying abnormality that may have predisposed to failure. We also routinely obtain a computed tomographic (CT) scan of the affected knee to more accurately measure the diameter and location of the femoral and tibial bone tunnels, and a magnetic resonance imaging (MRI) to evaluate the associated soft tissues, searching for additional pathology in the meniscus, capsule, and collateral ligaments that may have contributed to failure. Furthermore, while rare, infection can also be a cause of failure of ACL reconstruction, and should always be considered, especially in presentations without a mechanical cause of failure (no traumatic event, otherwise well placed tunnels). In the event of infection, this technique can still be used as part of a 2-stage revision ACL reconstruction; however, a thorough debridement of the surgical site, including an aggressive reaming of the previously used tunnels, should be performed first, followed by culture-specific antibiotic therapy in the postoperative period.
Our general indications for staging revision ACL reconstruction include any situation in which the previous bone tunnels will interfere with anatomic graft placement and fixation, which often occurs after significant tunnel dilation, specifically with tunnel dilation greater than 14 mm. 5
Our patient is a 31-year-old male, 18 months status post left knee ACL reconstruction with tibialis anterior allograft, performed at an outside hospital. Unfortunately, he sustained a re-injury during an awkward landing while playing basketball. On examination in our clinic, he had a small effusion, a 2B Lachman, and a 2+ pivot shift test.
We obtained radiographs and advanced imaging. The radiographs demonstrated dilated femoral and tibial tunnels with suspensory fixation. An MRI confirmed the retear of the ACL and demonstrated a femoral tunnel measuring 21 mm in diameter and 45 mm in length, with apparent anterior malposition. The tibial tunnel measured 17 mm in diameter and 50 mm in length. The size and position of these tunnels would preclude us from placing a new graft in its anatomic position. We discussed treating him in a staged manner, with a first-stage bone grafting procedure followed by a delayed second-stage revision ACL reconstruction.
For the first-stage ACL reconstruction, necessary equipment includes standard knee arthroscope, rigid reamers similar to those used in revision hip arthroplasty or femoral intramedullary nailing, arthroscopic bone cutting shaver, radiofrequency ablation wand, cannulated allograft bone dowels, and cannulated dilators for impacting the graft into place. We use our standard knee arthroscopy setup with a foot stop and a thigh post. We make our standard lateral and medial arthroscopic portals. The medial portal can be extended 1 to 2 cm to accommodate a large graft for the femoral tunnel.
First, we perform a thorough diagnostic arthroscopy. We use an arthroscopic shaver to debride the remnant of the ACL graft. Next, we debride the soft tissue within the femoral tunnel with an arthroscopic aggressive shaver and a radiofrequency ablator. Of note, a 70° arthroscope can aide in the viewing through the lateral portal. In this case, the femoral tunnel appears to be anterior to the lateral intercondylar ridge, which is consistent with our preoperative evaluation of advanced imaging and therefore meeting our indication to perform revision ACL reconstruction in a staged manner.
Next, with the knee in hyperflexion, we insert a beath pin through the medial portal to cannulate the center of the previous femoral tunnel. This is driven out the lateral femoral cortex. We then used cannulated rigid reamers and sequentially ream the tunnel starting at 10 mm and reaming up by 1 mm until good chatter is achieved and there is circumferential bleeding bone with no remaining fibrous tissue in the tunnel. In this case, we stopped at 18 mm. We remove any remaining debris from the tunnel with an aggressive shaver.
We then measure the depth of the tunnel. We prefer to ream using a line-to-line technique. In this case, we stopped reaming at an 18-mm-diameter reamer, so we selected the appropriately sized 18-mm-diameter allograft bone dowel. This is inserted along the beath pin and then malleted into place using the cannulated dilator. This is done carefully to ensure that the dowel follows the exact tunnel trajectory when being placed. When it is just about fully seated, the beath pin is then removed. We then use an aggressive shaver or arthroscopic burr to shave down the dowel so that it is flush with the native lateral wall of the notch.
Next, we bring our attention to the tibial tunnel. We open the previous incision and dissect sharply down to the aperture in the tibia. In this case, we identified the previous PEEK interference screw, which we identified and then removed.
Working through the tibial tunnel, we use a shaver to debride fibrous tissue. We then ream the tibial tunnel starting at 10 mm, and increasing until there is good chatter and a circumferential bed of bleeding bone without any fibrous tissue. In this case, this was 16 mm in diameter.
Next, we use a depth gauge to measure the length of the tibial tunnel. In this case, it measured to be 55 mm. We then insert the bone dowels over the beath pin, again being careful to ensure proper trajectory of the dowel placement within the tunnel. We make sure to remove the beath pin before the grafts are fully seated so that the graft follows the path of the previous tunnel. We then malleted it into place until it was flush with the surrounding proximal tibial surface. We then use an aggressive shaver to smooth down the dowel inside the joint so that it is flush with the remaining proximal tibia. Finally, the joint is irrigated with arthroscopic fluid and any remaining debris is removed with the shaver.
This slide highlights technical pearls from our senior author, including obtaining a thorough history and physical examination with the appropriate imaging, to maximize the known information to minimize surprises in the operating room, counseling patients preoperatively regarding clinical possibilities and timeline for second-stage reconstruction, performing a thorough diagnostic arthroscopy to identify and treat any missed associated pathologies, performing a thorough debridement of the previous tunnels to removal all fibrous tissue and create a bleeding bed of bone, using proper dowel sizes and removing the beath pin prior to final impaction to allow the graft to follow the previous tunnel trajectory.
Our postop rehab protocol focuses on pain control, regaining range of motion, and then restoring quadriceps function. We obtain serial AP and lateral radiographs of the knee in clinic. We schedule the second-stage revision ACL reconstruction when the patient has full range of motion and quadriceps strength, and when the grafts have fully incorporated on radiographs, which is typically 4 months postoperatively. While CT scans are not routinely obtained to evaluate graft incorporation in our practice, it is obtained if there is any concern for poor graft incorporation on follow-up radiographs.
This slide highlights potential pitfalls and complications when performing this procedure. First, in the setting of significantly dilated tunnels, or a situation where the patient has been limited in their activity level and the distal femoral and proximal tibial bone is softer, there is a risk of the dowel traveling “off-course” within the tunnel, resulting in inaccurate positioning within the tunnel as it creates a new path eccentrically in the previous tunnel. This can be prevented by placing the guide pin into the center of the tunnel and confirming its position arthroscopically, followed by placement of the dowel over this guide pin to ensure that it remains in line with the tunnel. If not secured, the guide pin can be held with a grasping device placed through either an existing or a created accessory portal to ensure that the pin remains centered within the tunnel. However, it is important to remove the pin before the graft is terminally impacted into its final resting position in the tunnel to allow it to settle in its proper trajectory at the articular surface. Second, specifically with the tibial tunnel, if the graft does not cover the entire length of the tunnel, a second dowel of the same diameter can be measured and contoured to the remaining length required to fill the entire tunnel, and “stacked” onto the first dowel. If you find that the femoral dowel was too long for its tunnel or the tibial dowel was over-impacted, and the dowels are prominent within the knee joint, a bone cutting shaver, or burr, can be used to shave down and contour the prominent regions to create a flush surface and prevent impingement or damage to the articular cartilage. Finally, while nonunion of these grafts is rare, the incorporation potential can be optimized by confirming a completely reamed femoral and tibial tunnel with direct visualization of a bleeding rim of bone throughout the tunnel. The arthroscopic fluid pump can be turned down to allow for bleeding of the bone to be visualized if there is any concern.
While clinical outcomes data for 2-stage revision ACL reconstruction is limited, this recent retrospective cohort study evaluated 88 patients, and compared those that underwent single-stage versus 2-stage revision ACL reconstruction. Those patients who underwent 2-stage revision ACL reconstruction did so due to poor tunnel location or enlarged diameter, and they underwent bone grafting with allograft dowels using a technique similar to what was described in this video, and all patients received bone patellar tendon bone autograft or allograft for their revision ACL. The authors found significant improvement in clinical outcome scores for both groups. Furthermore, while there was a slightly increased failure rate in the single-stage group, this was not found to be statistically significant. This study suggests that in cases where tunnel diameter or location precludes the ability to perform revision ACL reconstruction in a single stage, performing the revision in 2 stages using allograft bone dowels can still produce excellent clinical outcomes with comparable failure rates to single-stage revision ACL reconstruction. 4 In addition, this 2021 study evaluated the overall incorporation rate of the allograft dowels in the setting of revision ACL reconstruction. In these 21 patients, CT scans were used about 3 months postoperatively to evaluate graft incorporation. The authors found an overall union ratio of 74% for tibial allograft bone dowels, and 83% for femoral allograft bone dowels, and an overall occupying ratio of 85.7% and 87.6% for tibial and femoral allograft bone dowels, respectively. Intraoperatively, all allografts showed punctate bleeding bone without any signs of degradation of the host bone-graft interface. 1 Of note, the patients in this study received various grafts and fixation constructs in the final revision ACL reconstruction, including titanium interference screws and suspensory fixation with all soft tissue grafts, suggesting there are no limitations to fixation technique after staging a revision ACL reconstruction with allograft bone dowels. 1 The authors concluded that allograft bone dowels are a viable graft choice to replenish bone stock in the setting of a staged revision ACL reconstruction. 1
Thank you for your attention, and we hope that you found our technique video to be useful.
Footnotes
Submitted October 8, 2023; accepted January 10, 2024.
One or more of the authors has declared the following potential conflict of interest or source of funding: J.A. receives financial support for research and educational content from Arthrex, whose implants were used in this surgical technique video. J.B. receives royalties from Arthrex, whose implants were used in this surgical technique video. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
