Biologically Augmented Hamstring Autograft Anterior Cruciate Ligament Reconstruction With Arthroscopically Harvested Minced Anterior Cruciate Ligament Remnant

Abstract

Anterior cruciate ligament (ACL) reconstruction is the most commonly used surgical procedure for the treatment of ACL injury, and the success of this procedure depends on the biological healing between the bone and the graft. The surgical procedure described in this study uses minced ACL remnants to enhance biological healing during ACL reconstruction.

Anterior cruciate ligament reconstruction (ACLR) is the most commonly performed procedure for the treatment of anterior cruciate ligament (ACL) injuries.¹ The rapid advancement of ACLR and ACL repair techniques has significantly improved the outcomes of these procedures. Recent efforts to enhance the clinical success of ACLR have focused on strategies to improve and optimize the biological environment of the graft-bone interface, thereby supporting and potentially enhancing the speed and durability of the reconstruction. Over the past decade, biological solutions and methods have been proposed to improve ligament remodeling.² One approach to improving outcomes after ACLR entails the preservation of the ACL remnant. It is known that mesenchymal cells remain in this remnant.³ In the standard remnant-preserving technique, the remnants are wrapped around the ACL graft. The weakest link after ACLR is not the graft itself but the fixation points on the tibial and femoral sides until the graft has sufficiently healed within the bone tunnels.^4,5 Minced ACL remnant provides mesenchymal stem cells, growth factors, and tissue-specific factors that may support graft-to-bone healing.³ The goal of our technique is to transfer these potential benefits of the ACL remnant to the tendon-bone healing zones within the tunnels, the weakest points of the reconstruction. This technique may be particularly beneficial in enhancing bone-tendon healing by accelerating the natural recovery process.^2,3

Surgical Technique

All steps are shown in Video 1. The patient is placed in the supine position, and a nonsterile thigh tourniquet is applied. After administering regional or general anesthesia, the leg to be operated on is prepared and draped in a sterile manner. Diagnostic arthroscopy is performed through standard anterolateral and anteromedial arthroscopic portals to rule out concomitant intra-articular lesions and confirm the diagnosis of an ACL tear. If meniscal tears or articular cartilage lesions are identified, additional treatment is performed. Once the ACL tear is confirmed, the ACL remnant is debrided using a shaver equipped with a GraftNet attachment (Arthrex) on the aspirator. The minced ACL remnants collected in the filter mechanism of the tissue collector are transferred to a container (Fig 1). Autologous conditioned plasma (Arthrex) is then added (Fig 2), and the mixture is homogenized using a dual-syringe technique until a uniform consistency is achieved (Fig 3).

Fig 1.

Minced anterior cruciate ligament (ACL) pieces removed from the filter mechanism of the tissue collector. White arrow shows collected ACL fragments.

Fig 2.

Adding autologous conditioned plasma (white arrow) to minced anterior cruciate ligament parts (white asterisk).

Fig 3.

Mixing of minced anterior cruciate ligament (ACL) pieces and autologous conditioned plasma (ACP) (Arthrex) with the double-syringe technique. White arrow indicates the minced ACL and ACP mixture in the syringe.

Graft Harvesting and Preparation

The surgical procedure begins with an oblique incision 2 cm medial to the anterior tibial tuberosity and 4 cm distal to the joint line. A planar dissection is performed to reach the sartorius fascia, which is incised to allow identification of the hamstring tendons. Using an open tendon stripper, only the semitendinosus tendon is harvested. The graft is cleaned and rinsed with a saline solution supplemented with 1 g of vancomycin powder, then transferred to a workstation for further preparation. At the workstation, the semitendinosus autograft is laid out longitudinally, and any residual muscle tissue on the tendon is removed. After thorough cleaning, the minced ACL mixture (Fig 4), prepared from the ACL remnants, is carefully placed into the fan-shaped broad end of the tendon (Fig 5). The opening is then meticulously closed and sutured (Fig 6). Finally, the tendon is folded into 4 strands with a TightRope (Arthrex) preattached at both ends (Fig 7).

Fig 4.

White asterisk shows mix of minced anterior cruciate ligament and autologous conditioned plasma.

Fig 5.

Placing the minced anterior cruciate ligament mixture inside the wide end of the tendon like a fan.

Fig 6.

White arrows indicate the tendon fragment that has been sutured by trapping the minced anterior cruciate ligament fragments inside.

Fig 7.

Autograft prepared in 4 layers (white asterisk) with TightRope (Arthrex) at both ends (white arrows) ready for reconstruction.

Tunnel Preparation and Graft Placement

The femoral tunnel is prepared using a standard technique with a drill matching the tendon’s diameter. The tibial tunnel is created in a retrograde fashion using a FlipCutter III drill (Arthrex) sized according to the graft’s thickness. The graft is first passed through the femoral tunnel and secured with an adjustable loop system. It is then tensioned and passed through the tibial tunnel, where it is similarly fixed using the adjustable loop system.

Rehabilitation

The minced ACL technique does not change the physiotherapy protocol of standard ACLR surgery. It does not affect the postoperative knee joint range of motion or weightbearing possibilities. Depending on muscle control and the patient’s individual tolerance, walking with crutches is recommended for 2 to 4 weeks postoperatively. Full weightbearing is allowed to the extent tolerated. Running is permitted at 3 months postoperatively. Athletes are allowed to return to competitive sports 9 months after surgery.

Discussion

ACLR remains the gold-standard procedure for restoring anteroposterior knee joint stability. However, while ACLR techniques have evolved in recent years, they remain imperfect. Optimal ACLR depends on multiple factors, including secure fixation with proper anatomic graft placement, effective graft incorporation, revascularization, and ligamentization.⁶ Successful ACLR requires comprehensive biological integration of the graft with host tissue.⁷ One of the major concerns in the literature on ACLR is the incomplete microscopic healing of autografts.⁸ Consequently, techniques that can biologically enhance graft healing, thereby facilitating earlier and more intensive postoperative rehabilitation and faster return to preinjury activity levels, are being investigated.^2,9,10 Preserving the ACL remnant is one approach to improve the outcomes after ACLR. Residual ACL remnants containing mechanoreceptors and nerve endings are crucial for promoting graft revascularization and reinnervation.¹¹ Beyond the repaired microenvironment provided by the surrounding synovium and growth factors, another key mechanism of remnant-preserving techniques is the presence of mesenchymal stem cell (MSC)–like cells in ACL remnants. Recent studies have isolated stem cells from tendon tissues, referring to them as tissue-specific tendon-derived stem cells. These cells form adherent colonies in vitro, exhibit typical fibroblast-like morphology, and show self-renewal and multilineage differentiation potential.¹² Fu et al.³ reported finding MSC-like stem cells in ACL remnants. Compared to bone marrow MSCs, ligament stem cells proliferate faster, making them a potential cell source for future ACL tissue engineering applications.¹³ However, the preservation of ACL remnants to improve graft remodeling may lead to intraoperative visualization challenges during arthroscopy and graft passage difficulties.¹⁴ The main complications of remnant preservation include cyclops lesions, notch impingement, and loss of extension.¹⁵ Our technique of minced ACL avoids these challenges by debriding the remnant ACL tissue while enhancing the biological environment for bone tunnel–tendon healing, which is one of the weakest links in ACLR surgery. This method offers a simple, cost-effective approach with significant potential to improve graft–bone tunnel healing. One potential disadvantage of complete remnant harvesting is the loss of the residual ACL stump, which is known to provide a vascularized environment that may contribute to graft revascularization and proprioceptive recovery during ACL reconstruction. That said, these additional biological enhancements require extra time during graft preparation. The advantages and disadvantages of the technique are summarized in Table 1. The pearls and pitfalls of the technique are summarized in Table 2.

Table 1.

Advantages and Disadvantages of the Minced ACL Technique

Advantages	Disadvantages
▪Enhances the biological environment for bone-tendon healing ▪Avoids complications seen in standard remnant-preserving techniques (e.g., cyclops lesion formation, graft impingement) ▪Provides improved arthroscopic visualization and easier determination of correct tunnel placement since the ACL remnant is debrided	▪Requires additional time for graft preparation ▪Involves extra cost for the graft harvesting device ▪Loss of remnant stump eliminates a vascular source for graft revascularization

ACL, anterior cruciate ligament.

Table 2.

Pearls and Pitfalls of the Minced ACL Technique

Pearls	Pitfalls
▪Use a GraftNet (Arthrex) or similar tissue collector to efficiently harvest ACL remnants without losing viable tissue. ▪Ensure thorough mixing of minced ACL with autologous conditioned plasma to create a uniform, injectable consistency. ▪Place the minced ACL mixture into the broad, fan-shaped portion of the semitendinosus tendon to maximize surface area contact with the bone tunnel.	▪Poor homogenization can lead to uneven graft preparation or clogging during injection into the tendon. ▪Incorrect placement of the minced ACL mixture may compromise tendon folding and fixation. ▪Insufficient suturing may result in graft construct failure during tunnel passage.

ACL, anterior cruciate ligament.

Disclosures

Both authors (M.B., A.Ş.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Data

Video 1

This video shows the surgical steps of biologically augmented hamstring autograft anterior cruciate ligament (ACL) reconstruction using arthroscopically harvested minced ACL remnants. The procedure includes ACL remnant collection, preparation of the minced ACL mixture with autologous conditioned plasma, and integration of the mixture into the autograft to enhance graft-to-bone healing.