Short-term functional outcomes of anatomic single-bundle ACL reconstruction using modified I.D.E.A.L technique

Introduction

Sports activities are leading causes of Anterior Cruciate Ligament (ACL) injuries that may require surgery; approximately 80% of all knee ligament operations involved ACL surgery, making it among the most commonly performed procedures by sports surgeons all over the world.^[1] An ACL injury can be deleterious, especially for a young athlete who may not be able to engage in demanding sports at a high level without surgical reconstruction. Furthermore, it can increase the long-term risk of developing knee osteoarthritis (OA).^[2], ^[3], ^[4] The main objective of ACL reconstruction is to re-establish the normal knee biomechanics in patients with a functionally unstable knee. It is assumed that impaired knee biomechanics with the reconstruction procedure is the principal cause of long-term degenerative joint disease.^[5], ^[6]

ACL reconstruction techniques have progressed considerably over the last four decades. Initially, it was accomplished using an open technique to restore the ACL's native architecture until the early 1980s, when technological innovations allowed for the development of arthroscopically assisted procedures. In 1990, the trans-tibial technique was developed, in which the femoral tunnel was established through the tibial tunnel; though this technique could restore the translational stability of the knee joint, follow-up of these patients revealed that they still exhibit rotatory instability. ^[5], ^[7]

According to anatomical studies, ACL comprises anteromedial and posterolateral bundles corresponding to the tibial insertion sites.^[5], ^[8] Functional restoration of the injured ACL to its native dimensions, fiber orientations, and insertion sites on femoral and tibial sides is referred to as anatomic reconstruction.^[9] The idea of recreating both bundles was first suggested in the 1980s to improve the rotational stability of the knee joint. However, several studies have compared the clinical results between anatomic double-bundle and single-bundle procedures showing that the double-bundle technique is not superior to the single-bundle technique in long-term follow-up.^[10], ^[11], ^[12], ^[13]

Improper graft placement is the principal cause of poor functional outcomes and early graft failure after ACL reconstruction.^[14] Numerous research works have been conducted to further clarify the anatomical features and dimensions of native ACL footprint in an attempt to replicate these anatomical characteristics and obtain a more favorable clinical outcome,^[15], ^[16] as a consequence, many new surgical concepts have been developed including ˝complete footprint restoration˝ and ˝I.D.E.A.L techniques˝.^[17], ^[18] Our main objectives are to assess the functional outcomes of anatomic single-bundle reconstruction using the modified I.D.E.A.L femoral footprint positioning technique.

Materials and Methods

Surgical technique

A pneumatic tourniquet was applied on the proximal thigh, the limb was stabilized by a vertical post on the proximal thigh, and 2 horizontal posts were established on the bed to hold the knee in 90° and hyperflexion during the procedure ([Figure 1] A). Prophylactic antibiotics (cefuroxime injection) administered within 30 minutes prior to incision. An oblique incision (3-4 cm) is made over the anteromedial aspect of the proximal tibia, approximately one inch medial and inferior to the tibial tubercle; Semitendinosus and gracilis tendons were identified and harvested ([Figure 1] B).

Two main portals were established; standard anteromedial and anterolateral portals; a check scope was performed prior to ACL reconstruction for all patients; to confirm the ACL incompetency and assess other associated intra-articular pathologies such as chondral and meniscal injuries. Notchplasty, if needed performed with an arthroscopic burr through the anteromedial portal.

The lateral intercondylar ridge (Resident's ridge) is a bony landmark that can be utilized to identify the anterior endpoint of the femoral footprint; Bifurcate ridge is another important osseous ridge that separates the insertion sites of anteromedial and posterolateral bundles within the footprint. The native ACL insertion site is oblong-shaped that attaches to the lateral intercondylar ridge anteriorly and extends to the lateral femoral condyle cartilage posteriorly.^[17] ([Figure 2]).

Through the anteromedial portal, a microfracture awl was placed 2-3 mm posterior to the lateral intercondylar ridge, posterior enough on the native footprint, leaving 1-2 mm bone bridge with the articular cartilage of the posterior aspect of the lateral femoral condyle in 90° of flexion, and introduced into the bone, creating a hole to reference the guidewire insertion. The joint was then hyperflexed, and the guide pin was drilled through the footprint toward the lateral epicondyle of the femur and out the skin on the lateral aspect of the femur. Reaming was then carried out initially with a (4 mm reamer), followed by an (8 mm reamer), creating a tunnel that crosses the anterior edge of the lateral intercondylar ridge 3-4 mm ([Figure 3]).

Through the same incision which was used for hamstring graft harvesting, the tibial tunnel was drilled in the standard anatomical position, the prepared graft (8 mm in diameter in most of the patients) was then passed under direct arthroscopic visualization, when the position was satisfactory, secured by an appropriate-size interference screw (anterior to the graft) or endobutton on the femoral side, and an interference screw on the tibial side. Finally, the arthroscope was reintroduced into the knee joint to check the final positioning and stability of the graft ([Figure 4]).

Postoperative care

All patients were discharged on the same day of the surgery; if there was no associated meniscal repair, full weight-bearing started on the same day using axillary crutches. The first postoperative visit was after 3 days, during which the surgical site was inspected, and the dressing was changed, appropriate imaging studies were taken to check and document the position of the graft and interference screws ([Figure 5], [Figure 6]), and the physiotherapy program commenced, concentrating on, active range of motion and quadriceps isometric exercises. The second and third postoperative visits were after 2 weeks and 1 month, respectively.

Results

Demographic data of patients, which is summarized in ([Table 1]), illustrates that most of the patients were between 20-29 years old, which was 45% of the total, while 44.2% and 5.8% were between 30-39 years old and less than 20 years old, respectively. 95.83% of participants were male gender. Right side ACL rupture constitutes 58.3% of the patients, whereas 41.7% had left side injury. Regarding the activity level of the participants, 63.4% were recreational athletes. Then, 81.7% of injuries were sport-related injury mechanisms.

The mean IKDC score preoperatively was 50.96 and increased to 83.81 after the operation. While 51.17 and 86.19 were the mean of Lysholm score, Preoperative & Post-operative, respectively. Moreover, the Mean Tegner score before ACL injury was 7.59, while 3.63 preoperative and 7.18 post-operatively, indicating a statistically significant difference between (preoperative & postoperative) values in IKDC, Lysholm, and Tegner scores with a (P-value 0.000), as shown in ([Table 2], [Table 3]).

We had shown here that all patients had poor IKDC scores before the operation, while in post-operative assessment, 65.8% of patients had a good score, and 13.3% demonstrated excellent scores. Moreover, 99.2% of the patients show unsatisfactory Lysholm score preoperatively, while postoperative score calculation demonstrates good outcome in 60.8% and excellent outcome in 14.2% of patients, representing a statistically significant difference between IKDC (P-value 0.000) and Lysholm (P-value 0.000) score values before and after the operation, as demonstrated in the ([Table 4]).

Discussion

Although many reconstruction techniques have been developed to recreate near-normal ACL anatomy and kinematics, the most common surgical option is a single-bundle anatomic reconstruction. Several studies have proven its success with comparable clinical outcomes between single-bundle and double-bundle techniques.^[10], ^[11], ^[19], ^[20], ^[12], ^[13] The concept of the I.D.E.A.L femoral tunnel placement was first proposed by Pearle AD and coworkers in 2015 in an attempt to imitate the characteristics of native ACL more closely and achieve more preferable clinical outcomes.^[17] We have modified the I.D.E.A.L technique by moving the location of the femoral tunnel more anteriorly to cross the anterior edge of the lateral intercondylar ridge (3-4 mm) with a favorable clinical outcome in a short-term follow-up.

Cadaveric dissections have revealed that, albeit the ACL femoral insertion site is oval in shape, the ligament fibers create a flat, ribbonlike structure 9 to 16 mm wide and 2 to 4 mm thick as it extends from the bone, resulting in a mismatch between the femoral footprint shape and the structure of the ligament. Making the tunnel in the center of the footprint or “covering the footprint” with the graft may not replicate the structure or efficacy of the native ACL.^[17], ^[21]

Histological studies have demonstrated that femoral ACL footprint consists of direct and indirect insertion sites; the direct insertion is composed of dense collagen fibers, located directly posterior to the resident's ridge, extending posteriorly but does not reach the posterior femoral articular cartilage, while the fibers of indirect insertion located posterior to the direct insertion, spans posteriorly and merges with the posterior articular cartilage of the femoral condyle.^[15] Fibers of the direct insertion create a strong and secure osseous attachment that allows transmission of the majority of the mechanical load to the joint, whereas indirect insertion fibers have a minimal stabilizing role in restricting tibial translation and rotations; this means that it is reasonable to establish the tunnel in the direct insertion region; over the anterior edge of the footprint instead of being in the center.^[17], ^[22]

Native ACL is a nearly isometric structure that exhibits a minimal change in length throughout knee range of motion. Isometric behavior of the graft is primarily determined by the femoral tunnel positioning; establishing the femoral tunnel in a nonisometric location may lead to increased anterior knee laxity and graft failure. The most isometric region, which is the typical site for femoral tunnel placement, is a relatively narrow bandlike area proximal and anterior along the resident’s ridge. From the biomechanical point of view, placing the graft in this location can also serve a more convenient time-zero stability and a lower tension-flexion pattern when compared with a central tunnel position.^[17], ^[23], ^[24]

However, women have more ligamentous laxity and are more prone to sustain ACL rupture; our study showed that 95.83% of the patients were males, this male predominance also demonstrated by other studies such as Razi et al.^[25] (91.6% male), Sajjadi et al.^[26] (86.6% male), and Cury et al.^[27] (96.7% male), which may be related to a higher rate of male participation in sports activities. Most of the patients were young aged-athletes between 20-39 years old (89.2%); this demographic finding is supported by many other studies,^[25], ^[26], ^[28] as younger people are more likely to be engaged in strenuous activities than older people.

Right side injury was more common (58.3%) as compared to the left side; this finding is compatible with a study performed by Brophy et al., which showed that the dominant kicking leg was injured more commonly than the supporting side.^[29] Also consistent with a study performed by Cury et al.,^[27] in which 70% of participants had right side injuries. Though ACL rupture can be caused by various types of activities, the primary mechanism of injury in our study was sports activities, particularly football, which comprises 81.7% of cases; this finding is consistent with other studies such as Razi et al.,^[25] and Gianotti et al.,^[1] Everhart et al.^[28]

The mean preoperative and 1-year postoperative Lysholm score was 51.17 and 86.19, respectively with (p-value of 0.000); it could be noticed that there was considerable improvement in the mean Lysholm score after ACL reconstruction in all patients; this is consistent with a study performed by Thapa et al.,^[20] that showed a mean preoperative and 6 months postoperative Lysholm scores of 48.48 and 91.58, respectively. A similar study performed by Colombet et al.^[30] showed a mean Lysholm score of 75.6 preoperative and 90.8 postoperatively. Yasen et al.^[31] in their study demonstrated that the mean Lysholm score was 54.9 before the operation and 88.1 postoperatively. 25% of our cases rated fair, 60.8% of cases were rated good, and 14.2% were rated excellent functional outcomes after 1-year follow up, similar to a study conducted by Jonathan et al.^[32] that scored 90% of patients as good or excellent at 24 months of follow-up. Another study performed by Kilinc et al.^[33] showed that 57.1% of cases were excellent, 39.3% were good, and 3.6% were fair level.

We found that the mean IKDC score was 50.96 (40.22 to 60.91) and 83.81 (72.41 to 95.40) preoperative and postoperative, respectively, with a (P-value of 0.000), similar to a study performed by Colombet et al.,^[30] which showed that the mean preoperative IKDC score was 60.4±15, and 87.6±10.6 postoperatively. In a similar study performed by Hussein et al.,^[31] the mean preoperative IKDC score was 67.7 and 91.8 postoperative, with an average follow-up of 51.15 months.

Concerning the Tegner score, values were 7.5917, 3.6333, and 7.1833 preinjury, preoperative and postoperative, respectively, with a (p-value of 0.000), which shows a statistically significant improvement in the functional status of patients and their ability to return to preinjury activity level and sport participation, this finding is comparative with outcomes of a study conducted by Chen K. et al.^[12] which showed that the mean Tegner score was 2.47 and 6.59, preoperative and postoperative, respectively. In a similar study by Schurz M. et al.,^[34] the mean preoperative Tegner score was 2, and postoperative follow-up showed the mean score of 6.

Conclusion

Anatomical single-bundle ACL reconstruction with our modified I.D.E.A.L technique of femoral tunnel placement showed promising short-term results in terms of; improvement of the functional outcome and reestablishment of the native knee kinematics.

Source of Funding

None.

Conflict of Interest

The authors declare no conflict of interest.