Abstract
Background:
Revision anterior cruciate ligament (ACL) reconstruction is technically challenging and may require the use of bone dowels in either 1 or 2 stages.
Indications:
The indications for bone dowels include tibial or femoral tunnel malposition or widening of the tunnels. In the patient case, the tibial tunnel aperture was positioned far medial to the native ACL insertion with a horizontal tunnel trajectory and the femoral tunnel was vertical. In addition, there was tunnel widening to 12 mm of both tibial and femoral tunnels.
Technique Description:
A bone-patellar tendon-bone autograft was harvested and diagnostic arthroscopy was performed. The previous tibial tunnel was sequentially reamed from 8 to 12 mm to adequately overdrill the previous widened tunnel. Next, the femoral tunnel was reamed to 12 mm in similar fashion. Using a tamp and guide pin, a 12 × 30-mm allograft bone dowel was then malleted into the femoral tunnel until it was flush with the medial aspect of the lateral femoral condyle. Another 12 × 30-mm bone dowel was then advanced into the tibial tunnel until it was just below the native articular margin. With the bone dowels securely in place, the ACL reconstruction using the harvested bone-patellar tendon-bone autograft was performed.
Results:
Werner et al reported a study of 12 patients who had excellent incorporation of femoral tunnel allograft bone dowels and comparable objective and subjective scoring to 2-stage techniques. Dragoo et al reported a study of 18 patients with tibial tunnel allograft bone dowels that demonstrated significant increases in patient-reported outcome measures and a significant decrease in tunnel widening.
Discussion/Conclusion:
Revision ACL reconstruction may require bone dowels if there are malpositioned tunnels or if there is tunnel widening. Overall, the literature demonstrates that 1-stage revision outcomes have been comparable to reported 2-stage revision outcomes, both of which are satisfactory.
This is a visual representation of the abstract.
Video Transcript
In this video, we will discuss the indications and surgical technique for revision anterior cruciate ligament (ACL) reconstruction using bone dowels. Listed here are the financial disclosures. The following topics will be reviewed in this video.
In this case presentation, our patient is a 36-year-old man who tore his ACL 14 years prior. He had an ACL reconstruction using a hamstring autograft that initially performed well. However, in recent years, the patient experienced progressive instability to the point where he could not trust his knee with activities. Physical examination demonstrated a 2+ Lachman test and a positive pivot shift glide.
Radiographs were acquired and revealed mild osteoarthritis, a staple from prior procedure, moderate tunnel widening, a horizontal tibial tunnel with the aperture positioned medially on the tibial plateau, and a vertical femoral tunnel.
Magnetic resonance imaging (MRI) confirmed the suspected ACL graft tear, and the tear is marked with the orange arrow in each plane. Femoral and tibial tunnel widening to 12 mm was also appreciated. A computed tomographic (CT) scan is typically recommended to further evaluate positioning and size of tunnels; however, in this particular case, it was clear from the radiographs and MRI that the tunnels were malpositioned and thus a CT was not deemed necessary.
Revision ACL reconstruction is technically challenging and may require the use of bone dowels in either 1 or 2 stages. The indications for bone dowels include tibial or femoral tunnel malposition or widening of the tunnels. In our case, the tibial tunnel aperture was positioned far medial to the native ACL insertion with a horizontal tunnel trajectory. It can be seen in the standing radiographs that both tunnels had widening to 12 mm. Although the decision to perform 1- vs 2-stage revision is multifactorial, Miller et al recommends considering a 2-stage revision with tunnel widening of >14 mm. 3 In this case, we decided to perform a 1-stage revision with 12 × 30-mm bone dowels in both tibial and femoral tunnels with bone-patellar tendon-bone autograft. This decision was based on moderate tunnel widening and minimal overlap between previous and planned tunnels. One-stage revision reduces patient risk, recovery time, and costs with comparable outcomes to 2-stage revision.
The patient was positioned supine on the operating table with a nonsterile tourniquet high on the operative thigh. The contralateral leg was secured, and a lateral post was utilized during knee arthroscopy with a bracketed leg holder. A 6-cm vertical incision was made on the medial border of the patellar tendon. The paratenon was then incised and elevated. A 10-mm graft width in the midsubstance of the patellar tendon was marked for harvest.
An approximately 23-mm-length plug from the tibia was then carefully harvested using a sagittal saw. From the patella, the same length plug was harvested using more angled cuts to produce a trapezoidal shape. The graft was elevated using an osteotome and prepared at the back table. Each bone plug was cut to 10 mm in diameter, and the tendinous graft length was 55 mm. Holes were then drilled and sutures placed on each end for graft passage.
The scope was introduced for diagnostics into an inferolateral portal created with a #11 blade. The graft appeared attenuated with laxity of >50% of the fibers. A shaver was introduced through the inferomedial portal to debride the ACL graft and the footprint on both the femoral and the tibial sides leaving behind only the posterior cruciate ligament (PCL).
We then identified the previous tibial tunnel that was positioned medially on the tibial face. First the staple was removed and then the tunnel was cannulated with a 3/32nd pin. Next, we reamed with an 8-mm fully threaded reamer. This was followed by a 10- and a 12-mm reamer to adequately overdrill the previous tunnel. A shaver and half round rasp were additionally used to debride the tunnel. We introduced the scope through the tunnel to confirm it had been appropriately debrided of all soft tissue.
Next, we identified the previous femoral tunnel high in the notch. By flexing the knee to about 100°, we were able to introduce a 6-mm dilator through the tibial tunnel and into the femoral tunnel. This dilator was then cannulated with a beath pin which was advanced through the condyle and out laterally.
We then sequentially reamed the previous femoral tunnel from an 8- to a 12-mm tunnel until the borders were clean of graft. These reamers were advanced to a depth of about 30 mm. The camera was advanced through the tibial tunnel into the femoral tunnel and confirmed adequate debridement.
Presented here is the pin and the tamp used to place the bone dowel into the tunnels. An advantage of this particular tamp is that the pin is displaced to the side, as opposed to centrally through the tamp, allowing for the use of a mallet without pin interference.
Next, the 12 × 30-mm bone dowel was advanced through the tibial tunnel into the femoral tunnel and impacted into place with a tamp. This was advanced until it was flush with the medial aspect of the lateral femoral condyle. A burr may be used if it remains prominent. After this, the same sized bone dowel was placed into tibial tunnel and advanced until it was just below the native articular margin. Having completed the bone grafting, we moved on to the ACL reconstruction.
The anatomic femoral footprint of the ACL was identified on the medial aspect of the lateral femoral condyle. The knee was then hyperflexed and the guide pin placed through our accessory anteromedial portal and through the condyle out laterally.
The ACL tibial guide was then placed on the posterior medial aspect of the footprint, even with the lateral meniscus anterior horn and in the middle of the lateral and medal tibial eminences. A guide pin was again placed with the guide set at 65° given our graft length measured 55 mm. The pin positioning was confirmed on lateral fluoroscopy. Next the femoral tunnel was reamed to a depth of 25 mm with a 10-mm half-fluted reamer. The placement of our tunnel involved about 30% of the bone dowel which remained stable after reaming with circumferential bony margins. The 10-mm drill was used to create our tibial tunnel, and the reamings were saved for later packing into the patellar bone plug harvest site.
The graft was retrieved from the back table and passed through the tunnels. A 7-mm metal femoral interference screw was inserted into the femoral tunnel to secure the bone plug. The knee was then cycled through its range of motion 10 times. The graft was placed at the appropriate tension, and the tibial 9-mm interference screw was then placed with the knee in full extension. Here, you can see previous malpositioned tunnel packed with the bone dowel and our new tibial tunnel. There was a strong end point with Lachman and anterior drawer testing after fixation.
There are several potential complications specifically associated with a 1-stage revision ACL reconstruction using bone dowels. One possible complication is loosening of bone dowels if the new tunnel placement significantly overlaps with the dowel. It is also important to select an appropriately sized bone dowel that is the same or 1 mm greater than the tunnel width to help ensure a snug fit. 1 The senior author typically chooses a dowel that is the same size as the last reamer as the friction fit is sufficient and dowel fracture may occur if it is too snug. In addition, there is potential for poor incorporation circumferentially with the native bone when healing. Further complications exist that are present among all ACL reconstruction procedures.
Our protocol for postoperative management of revision ACL reconstruction is the same as primary ACL reconstruction. Patients start out with weight-bearing as tolerated and full range of motion for the first 10 weeks and then progress to full weight bearing. At 4 months out, they are encouraged to perform basic symmetric exercises and they may return to sport after 9 months or as tolerated by strength and symmetry.
Werner et al 4 reported a study of 12 patients who had excellent incorporation of femoral tunnel allograft bone dowels, defined as >75% incorporation, and comparable objective and subjective scoring to 2-stage techniques. Dragoo et al 2 reported a study of 18 patients with tibial tunnel allograft bone dowels that demonstrated significant increases in patient-reported outcome measures and a significant decrease in tunnel widening. Overall, the literature demonstrates that 1-stage revision outcomes have been comparable to reported 2-stage revision outcomes, both of which are satisfactory.
From the Department of Orthopaedics at the University of Virginia, we thank you for watching.
Footnotes
Submitted April 16, 2022; accepted May 9, 2022.
One or more of the authors has declared the following potential conflict of interest or source of funding: M.M. has received stock or stock options from Johnson & Johnson and Stryker; has received options from Clozex; has received IP royalties from Arthrex, Inc; is a paid consultant for Arthrex, Inc; has received publishing royalties, financial or material support from Saunders/Mosby-Elsevier and Wolters Kluwer Health—Lippincott Williams & Wilkins; and has been a board or committee member of the American Orthopaedic Society for Sports Medicine. 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.