Proximal Anterior Cruciate Ligament Tear Primary Repair Using a Tensionable Knotless Anchor System

Abstract

Recently, there has been a growing interest in repairing proximal anterior cruciate ligament (ACL) tears, a technique gaining popularity for its outcomes comparable with reconstruction methods within certain population subsets. Although many techniques have been described, it is difficult to reach a definitive consensus on the most effective approach. As a result, a surgical technique is presented to optimize the repair technique. In this procedure, the proximal bundles of the ACL are sutured using lasso-loop stitches, and a transosseous femoral tunnel is made to facilitate the passage of suture threads, which are subsequently fixed using a tension-control knotless suture anchor to the lateral femoral cortex, all arthroscopically. This surgical method not only allows for accurate tensioning during fixation but also reduces the possibility of interference with the healing process by eliminating the presence of implants in the femoral footprint and increasing the ligament-bone contact area. The meticulous control of ACL tension, along with the lack of implants in the footprint, contributes to a more efficient and undisturbed ligament healing process within the femur.

Proximal anterior cruciate ligament (ACL) tears typically are treated by reconstruction. However, certain repair approaches have emerged that aim to preserve original tissue and reduce surgical morbidity.¹ However, none have shown clear superiority. Many of the repair techniques using suture anchors typically involve intra-articular insertion, theoretically posing risks such as chronic inflammation and potential interference with the ligament-bone healing process.² In addition, intra-articular fixation increases the possibility of posterior femoral condyle perforation by the anchors.³ Moreover, achieving precise control over ligament tension proves challenging in reported repair techniques, with some employing single-stitch methods, which may contribute to early failure.⁴ Therefore, the presented technique holds the potential to enhance healing theoretically by eliminating the presence of any implant in the femoral footprint, thereby preserving the integrity of the ligament-bone contact area and accurately recreating the anatomical vector of the ligament.² In addition, it allows meticulous control of ligament tension, and the use of lasso-loop stitches provides a greater biomechanical profile.⁴

Surgical Technique

Patient Positioning and Setup

The patient is placed in the supine position, and a tourniquet is applied to the appropriate lower extremity. Standard knee arthroscopy equipment is used, and medial and high lateral portals are made. The camera is placed through the lateral portal and hand instruments are used for the medial portal.

Assessment of the Status of the Ligament

For improved visibility, the joint is cleaned. A visual examination of the knee is also undertaken to rule out any related lesions. The ligament tear is located (Fig 1A), the quality of the ligament is verified, and it is confirmed that it has adequate length to be in contact with the femoral footprint using an arthroscopic grasping forceps (Fig 1B). A shaver is used for initial debridement and microperforations are made with a 2.0-mm-diameter pin for generating a biological stimulus close to the femoral footprint.

Fig 1.

Arthroscopic view of the right knee. (A) The yellow arrow indicates the tear of the anterior cruciate ligament at its femoral insertion; a minimal tissue insertion is evident in the footprint. (B) There is evidence of an adequate length to be in contact with the femoral footprint using an arthroscopic grasping forceps.

ACL Femoral Tunnel

A femoral tunnel is performed initially with a 2.4-mm diameter pin and then with a 4.5-mm diameter cannulated drill bit at the femoral footprint. A loop suture is then temporarily placed through the tunnel. Then, a suture is loaded on the suture passer forceps, and 2 lasso-loop stitches are performed in the proximal bundles of the ligament (Fig 2A); one suture is placed in the anterolateral bundle and another in the anteromedial bundle. The suture loop is used to pass the ligament sutures through the femoral tunnel (Fig 2B), an additional lateral portal is made, and a cannula (7-mm diameter) is inserted through this portal, which allows visualization of the femoral condyle and sutures (Video 1).

Fig 2.

Arthroscopic view of the right knee. (A) Each bundle of the ligament is sutured. (B) The ligament sutures are passed through the femoral tunnel. The yellow arrow identifies the suture.

Femoral Fixation

The cortex of the lateral femoral condyle is cleaned with radiofrequency through the cannula. Then, the 2 ends of ligament sutures are loaded into a knotless anchor of 4.5 mm in diameter (ReelX STT; Stryker, Kalamazoo, MI) and are inserted through the cannula (Fig 3) in the lateral femoral condyle and both sutures are tensioned under arthroscopy visualization with the knee in 20° of flexion (Fig 4). Finally, it is confirmed that there is no impingement and that the construct presents adequate tension and stiffness, and an intraoperative Lachman test is performed to assess knee stability (Video 1).

Fig 3.

Ligament sutures are loaded into a knotless anchor. (A) External view; the yellow arrow identifies the knotless anchor with the suture. (B) Arthroscopic view of suture anchor insertion; the yellow arrow identifies the knotless anchor suture with the suture.

Fig 4.

(A) External view, the tension of the sutures is gradually increased; the yellow arrow identifies the site from which suture tension is increased. (B) While increasing the tension of the sutures, an arthroscopic view of the ligament should be obtained. The yellow arrow shows the ligament with its tension restored.

Rehabilitation

Patients use crutches for 6 weeks after surgery, and weight-bearing and progressive flexion are allowed as tolerated. Full knee extension and up to 120° flexion are achieved during weeks 6 to 8. Return to low-impact sports is permitted after 6 months; pivot sports are permitted after month 9.

Discussion

ACL tears often require surgical management for their treatment, and methods such as repair or reconstruction are used.⁵ Although reconstruction is the gold standard for surgical treatment,⁶ repair is a less-invasive method that theoretically preserves proprioception and contributes to the dynamic stability of the knee.⁷ In addition, it does not generate more morbidity with graft harvesting in cases in which autografts are used.⁵ Repair is a method that can lead to normal joint mechanics by preserving the native ligament attachment sites and can lower the risk of posttraumatic osteoarthritis.⁸ Another advantage is that, in the event of a new injury, a standard ACL reconstruction can be performed. It also produces positive clinical outcomes with appropriate patient selection, which has contributed to its recent rise in popularity.⁸

There are various techniques described to repair the proximal portion of the ACL.¹ However, the superiority of these techniques has not been shown, and their choice is usually determined by the availability and experience of the surgeon. The use of intra-articular suture anchors, bone tunnels, buttons, or combinations of these with an internal brace, as well as the dynamic intraligamentary stabilization system, are among the alternatives mentioned in the literature.⁹

The clinical outcomes of ACL repairs have been favorable in carefully selected patients.¹⁰ Nevertheless, a meta-analysis comparing ACL repair with autograft reconstruction indicates that repairs are associated with greater rates of hardware removal, reoperation, and failure. Conversely, ACL repair shows superior early follow-up outcomes in terms of return to activity, knee function, and quality of life.¹ These findings should be interpreted with caution and not generalized, as there are numerous techniques for both repair and reconstruction, as well as various fixation methods.

Despite the variety of repair techniques, particularly for proximal ACL injuries, evidence suggests that these injuries have a greater healing potential as the result of their vascularization. Even one meta-analyses report better functional outcomes for repairs compared with reconstructions, supporting their use in proximal lesions and appropriately selected patients.⁸

A meta-analysis on the primary repair of proximal ACL tears reported failure rates ranging from 7% to 11%.¹ Notably, the likelihood of primary repair failure for proximal ACL tears is significantly greater among patients younger than 21 years, with a rate of 37.0%. This demographic factor warrants careful consideration when evaluating repair options for younger patients. In contrast, for patients older than 21 years of age, ACL repair appears to be a good treatment option, with significantly lower failure rates (3.5%) and complication rates (1.2%), along with favorable subjective outcomes.¹⁰

A review of the literature indicates that most reoperations in patients who have undergone ACL repair are attributed to hardware removal, scar tissue formation, deficits in range of motion, and arthrofibrosis, which may be caused by the devices implanted during the repair procedure.¹ With the proposed surgical technique, we aim to preserve the native tissue of the ACL in femoral-sided injuries using lasso-loop stitches and a suture anchor fixed in the lateral femoral cortex, which allows control of ligament tension, does not interfere with the ligament-bone contact area, and recreate the anatomical vector of the ligament (Table 1, Table 2, Table 3).

Table 1.

Surgical Indications and Contraindications

Indications	Contraindications
Acute proximal ACL tears	ACL tissue with no healing capabilities
Tissue quality sufficient to hold sutures	High-performance athletes and elite military patients
	Patients younger than 21 years of age
	Patients who are smokers

ACL, Anterior cruciate ligament.

Table 2.

Advantages and Disadvantages of the Surgical Technique

Advantages	Disadvantages
A minimally invasive approach reduces recovery time	Requires advanced training and expertise
Lower potential risk of complications compared with alternatives	Limited availability in some health care facilities
Enhances precision and minimizes tissue damage	This may involve greater costs due to the suture anchor
Increases the ligament-bone contact area
There is no hardware intra-articularly
Creates an anatomically and biomechanically stable construct

Table 3.

Pearls and Pitfalls of the Surgical Technique

Pearls	Pitfalls
Ensure proper patient selection to maximize benefits.	Inadequate patient assessment may lead to suboptimal outcomes.
The tension generated in the ligament must be controlled with direct vision.	Excessive tension on the ligament can cause rupture of its fibers.
Use lasso-loop stitches to increase biomechanical resistance.	The poor quality of the ligament tissue can generate tears in the tissue with the passage of the suture.
The quality of the ACL tissue and ACL tear type should be accurately evaluated.	A poor assessment of the tension of the remaining anterior cruciate ligament on the femur could cause failures in the healing of the ligament.
	Failure to recognize poor tissue may result in failure of repair.

ACL, anterior cruciate ligament.

The presented anatomic repair technique for proximal ACL tears may be an alternative to previously described methods for repairing these injuries. Creating an anatomically and biomechanically stable construct may reduce the potential risk of failure.^2,4 This hypothesis is generated on the basis of the technique's inherent ability to provide precise intraoperative manipulation of ligament tension. In theory, this technique promotes the optimum healing process by generating a physiologically favorable stimulation while avoiding the fixation of implants in the ligament footprint.

Proper patient selection is one of the most crucial variables for guaranteeing the success of ACL repair. In the first place, a patient must be willing to perform physiotherapy correctly to avoid the risk of early re-rupture or stiffness and limited joint mobility if, on the contrary, the therapy is not appropriately performed because some patients experience kinesiophobia after the procedure.⁵ Conversely, various series report suboptimal outcomes in high-performance athletes, elite military personnel, smokers, and patients younger than 21 years old.^1,10 For this reason, the procedure is not recommended for this type of patient. In addition to this, the characteristics of the ligament intraoperatively are very important, with this reference being made to the quality and length of the tissue, defined by the ability to withstand suture passage, and that the ligament is long enough to reach the femoral footprint.³ Therefore, the correct selection of the patient is important to avoid failure in the repair.

Disclosures

All authors (G.A.J.Q., P.A.S.R., R.D.A.P., A.J.M.B.) 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

The video illustrates the step-by-step surgical technique of anatomic arthroscopic primary repair for proximal anterior cruciate ligament tear using a tensionable knotless anchor system. The video shows a proximal anterior cruciate ligament tear on the right knee.