Abstract
Background:
The incidence of anterior cruciate ligament (ACL) injuries, reconstructions, and re-ruptures has rapidly increased. Patients with failed ACL reconstructions have been reported to suffer from far worse outcomes as compared with those with primary reconstructions, prompting the advancement of surgical and biologic techniques. Effective treatment of re-tears has been shown to be achieved either utilizing a 1-stage or 2-staged approach, with the latter preferred if the patient presents with significant bone loss, previously malpositioned tunnels, or unacceptable tunnel expansion. Recent literature has shown the efficacy of bone marrow aspirate concentrate (BMAC) in improving clinical outcomes and graft integration as well as accelerated ligamentization.
Indication:
Patients are indicated for surgery when presenting with chronic ACL graft failure and objective insufficiency as well as concerns regarding tunnel overlap, enlargement, or interference. Contraindications for revision involve influences of concurrent injuries that may be secondary causes of the ACL injury.
Technique Description:
After bone marrow aspiration is performed, the tibial and femoral tunnel apertures are debrided of fibrous tissue with a combination of a shaver and curettes. A threaded guide wire is passed and the interference screws are removed, revealing the residual ruptured graft. A shaver and radiofrequency ablation device are utilized to clean off remaining graft remnants. Sequential debridement and reaming are performed to remove any residual fibrous tissue or sclerotic bone from the tunnel. The demineralized bone matrix is then combined with the prepared BMAC in a syringe with a cannula extension and subsequently injected into the tunnels. A freer elevate is used to tamp and smooth the graft to match the surrounding contour. A 12-mm cannulated allograft bone dowel is then passed up into the tibial tunnel and gently tamped into place.
Results:
Within 2 years postoperatively, patients are expected to have improved overall knee-specific quality of life, reduced pain, and a successful return to activities. No differences in outcomes have been noted in the literature between 1-staged and 2-staged ACL reconstructions.
Discussion/Conclusion:
Recent advancements in our understanding of the effects of BMAC in the setting of an ACL reconstruction should prompt surgeons to consider such treatments in indicated patients.
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.
Keywords
Video Transcript
This is a video case presentation of arthroscopic bone grafting with bone marrow aspirate concentrate (BMAC) augmentation for 2-staged-revision anterior cruciate ligament (ACL) reconstruction.
Our conflicts of interest can be seen here.
The ACL is a ligamentous tissue that prevents rotational instability and anterior translation of the tibia over the femur. An increasingly common condition, particularly in athletic activities, injury to the ACL has a reported incidence rate of around 61 per 100,000 persons.3,6 BMAC contains a high concentration of mesenchymal stem cells, progenitor cells, and growth factors. Given the relatively worse outcomes seen in patients undergoing revision ACL reconstruction or poor integration of allograft tissue into the knee, BMAC has begun to be seen to improve clinical outcomes, graft integration, and metabolic activity as well as accelerated ligamentization. 2 This makes the prospect of combining the ACL procedure with BMAC an attractive option, particularly for patients with chronic pathologies to their ACL.
In this case, our institution was presented a 46-year-old active man who initially underwent primary, right knee, ACL reconstruction with a bone-patellar tendon-bone (BTB) allograft 4 years ago. This was complicated by traumatic graft re-rupture which was managed with right knee revision ACL reconstruction with a BTB autograft with metal interference screw fixation 1 year prior to arriving at our practice. On current presentation, the patient reported an acute episode of right knee pain and progressive swelling after performing a squat during an intense strength-training session 2 weeks prior. Since then, he noted persistent subjective instability, pain, and swelling of his knee.
Physical examination revealed moderate effusion with well-maintained range of motion, but a positive Lachman, lax anterior drawer, and significant pivot shift.
Orthogonal radiographs demonstrate changes consistent with prior ACL reconstructions, with 2 stacked metal interference screws in the femur and a single screw in the tibia. Tunnel position appears grossly appropriate, but with evidence of possible osteolysis and widening with sclerotic tunnel margins.
Computed tomography (CT) scan was obtained to further evaluate tunnel morphology and position. CT scan was notable for significant tunnel enlargement measuring 18 mm at maximal diameter in the tibia and 21 mm in the femur. Three-dimensional CT scan and x-ray reformatting were obtained to further delineate tunnel and hardware position as well as widening. Magnetic resonance imaging confirmed isolated intrasubstance graft re-rupture with associated effusion. Menisci and controsurfaces appeared intact.
Based on the patient’s subjective instability, pain, and functional limitations, as well as objective laxity and evidence of graft insufficiency on imaging, the patient was indicated for revision ACL reconstruction.
Given the extent of osteolysis and magnitude of tunnel enlargement, the decision was made to proceed with a two-stage reconstruction with primary arthroscopic tunnel debridement and bone grafting.
In this case, we planned to utilize a pre-shaped, cannulated allograft bone dowel for primary grafting of the tibia along with demineralized bone matrix with BMAC for residual defects in the femur and tibia.
In the operating room after positioning examination under anesthesia, we start with BMAC. Collection syringes are first prepared by flushing with heparin and the needle’s trocar is introduced through the cortex of the proximal tibia, approximately 3 to 4 centimeters distal to the joint line at the medial, flat area. After bone marrow aspiration is performed, the trocar is removed, and attention is turned to the tibial tunnel. The tunnel aperture is debrided of fibrous tissue with a combination of a shaver and curettes.
Once the tunnel is defined and the interference screw is identified, a threaded guide wire is passed, and the interference screws are removed with the corresponding screwdriver.
Arthroscopic evaluation is then performed, revealing the residual ruptured graft and stump which is debrided with an arthroscopic shaver. The lateral intercondylar notch is debrided of fibrous tissue to reveal the retained femoral interference screws. The knee is hyper-flexed and guide wires are threaded into each screw prior to removal with the associated screwdriver.
After screw removal, additional sclerotic voids remain which are debrided with an arthroscopic shaver and curettes.
Attention is then turned back to the intra-articular tibial aperture. Shaver and radiofrequency ablation device are utilized to clean off remaining soft tissue and graft remnant. Anterior osteophytes along the tibial eminence are burred down to prevent graft impingement or tunnel interference.
An elbow tibial tunnel guide is used to facilitate guidewire passage to the desired location through the tibial tunnel.
Sequential debridement and reaming are performed to remove any residual fibrous tissue or sclerotic bone from the tunnel. After tunnel debridement is completed, significant tunnel dilation and osteolysis are apparent.
The demineralized bone matrix is then combined with the prepared BMAC in a syringe with a cannula extension. Under arthroscopic visualization, the syringe is introduced into the joint and is used to inject the demineralized bone matrix and BMAC mix into the femoral tunnel.
The syringe is then removed and a freer elevator is used to tamp and smooth the graft to match the surrounding contour.
We then turn our attention to the tibial tunnel. A 12-mm cannulated allograft bone dowel is then passed up into the tunnel and gently tamped into place. A residual defect can be noted posterior to the bone dowel and the remaining Demineralized Bone Matrix (DBM) and BMAC mixture is then used to fill this void.
Again, an elevator can be used to smooth the graft and match the surrounding contour.
Postoperatively, the patient’s weight-bearing is restricted for 6 weeks. Serial radiographs are obtained to assess graft integration. CT scan may be obtained if there is concern for graft union prior to proceeding with the second stage in approximately 4 to 6 months.
Initial postoperative radiographs demonstrate excellent tunnel fill without evidence of lucency or complication.
The decision to proceed with staged-revision ACL reconstruction remains controversial. Recent evidence suggests that even with critical tunnel widening and malposition, similar clinical outcomes can be obtained with 2-staged ACL reconstruction if restrictive indications are followed. 4 Bone graft selection during staged-revision ACL reconstruction also varies considerably. A recent systematic review describes the array of graft sources and materials utilized. 5 While many have distinct advantages and downsides, there is currently no consensus on the optimal bone graft source for staged-revision ACL tunnel grafting.
Finally, our technique for tunnel preparation and bone grafting in staged-revision ACL reconstruction has been published with further details to guide management. 1
We thank you for watching our technical description of arthroscopic bone grafting with BMAC augmentation for 2-staged-revision ACL reconstruction.
Footnotes
Submitted August 16, 2022; accepted December 7, 2022.
The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. 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.
