Comparative Study of Fixed Loop and Adjustable Loop Cortical Suspension Device Used for Femoral Fixation in Arthroscopic ACL Reconstruction

Arthroscopic anatomic reconstruction is the preferred surgical option for anterior cruciate ligament (ACL) tears(1). Femoral graft fixation includes compression and suspensory devices(2). Cortical suspensory fixation is considered an ideal model of femoral fixation and extensively used worldwide(3).  Fixed-loop device requires Additional drilling of the femoral tunnel so that the button comes out of the lateral femoral cortex. This suspensory device leaves some part of the dead space which devoid of graft where graft motion can take place. This can further lead to the widening of the tunnel and jeopardize graft incorporation inside the tunnel(3). Moreover, anatomical tunnel creation can sometimes result in short tunnel length and inadequate graft length inside the bone(4). Second generation adjustable suspensory loop fixation devices came to overcome the dead space which is devoid of graft.  In these devices over-drilling of femoral tunnel is not required. Adjustable loop can be tightened and adjusted according to the tunnel length during the surgical process, thereby decreasing the possibility of bungee cord effect(3,5,6). However, some studies shown loosening in adjustable-loop devices, which may affect functional outcome after ACL reconstruction(3,4,7–9). This study compares functional outcome between Closed Loop and Adjustable Loop Cortical Suspension Device in terms of graft laxity on clinical assessment and International Knee Documentation Committee (IKDC) score.

 

 

 

Fig.1: Graft harvested with help of long tendon stripper

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig.2: Pre-tensioning of the harvested graft with Measurement of Graft

 

 

 

 

 

 

 

 

 

Fig.3:  Femoral Tunnel (Arthroscopic View)

Follow up and assessment:

Dressing was done on the second postoperative day and looked for suture line, swelling or effusion if any, surrounding skin and range of movement of knee. Active toe movement, Ankle pump up exercise and static hamstring muscle exercise were started as spinal effect wean off. Gradual flexion of knee started aiming to achieve 90° of flexion until 2 weeks. Knee brace was used till one month post operative. Patients were discharged on 3^rd to 5^th post-operative day with home-based physiotherapy protocol.

Evaluation:

All the patients were asked for post-operative radiographs of knee joint in 2 standard view to assess the tunnel placement, position of cortical suspensory loop device in femur and interference screw in the tibia. Patients were followed up at 15 days intervals up to 6 months. All patients were evaluated by clinical examination and IKDC scoring.

                                                                                                                                                                                                                                                                                                

 

 

 

 

 

 

Fig.4: Post Operative X-Ray

In this study both groups were analogous in preoperative score and demographic data. In both groups Right side knee was involved more commonly than left side and most common cause of ACL injury is road traffic accident.  In our study 26% cases had medial meniscus and only 2% cases had lateral meniscus tear on arthroscopy which were managed by repair. Mean Femoral tunnel in this study was 31±1.5mm in group I and 30±1.5 in group II.

Table 1: Pre-operative clinical assessment by Lachman Test:

Pre-Operative Lachman test 1+ positivity was present in no cases in both group I and group II, 2+ positivity in 76% in group I and 84% in group II, 3+ positivity in 20% cases in Group I and 12% in group II.

Table 2: Post-operative clinical assessment by Lachman Test at 6 months post operative

Post operative 84% patients had negative Lachman test in group I and 72% in group II, 16% cases had 1+ Lachman Test in group I and 24% in group II.

Length of 5 layered Hamstrung graft was ranging from 8.2 cm to 10.8 cm. Challa et al.(11) yielded an average semitendinosus graft length of 24.39 ± 1.3 cm. Mean length of femoral tunnel was 38.25mm. Iriuchishima et al.(12) made  the average femoral tunnel length 35.6 ± 4.4 mm.

Table 3: IKDC score at 6 months post operative

 

Final assessment by IKDC found that 86% cases were normal or near normal (88% cases in group A and 84% cases in group B). Abnormal IKDC scores were rated in 14% cases (12% in group A and16% in group B). There is no significant difference in both the groups as per IKDC Score.

Most of the patients returned to their pre-functional level at 6 months.

Hemarthrosis of knee joint was developed in one patient in each group. Knee stiffness developed in 2 patient of group I and one patient in group II and they were managed with under general anaesthesia mobilization. In this study the follow-up period was short terms and there is no screw breakage, graft injury, infection, deep vein thrombosis, synovitis of knee joint and post-operative arthritis.

Most of the patients at time of clinical examination initially presented with grades 2 and 3 instability on assessment by Lachman test, which indicated reconstruction. Knee stability was restored in most patients as 84% in group I and 72% in group II tested negative on the Lachman test. Ahn et al. (13) assessed 88.2% in the adjustable-loop device group and 72.7% negative Lachman tests in the fixed-loop device group. Choi et al.(6) assessed a negative Lachman test in 82% in the adjustable-loop device group and 70.1% of the fixed-loop device group.

 

Significant improvement was noted in functional outcomes in the form of IKDC scores in both groups. In our study IKDC score normal and near normal in 96% in the adjustable loop cortical suspension device group and 92% in the fixed loop cortical suspension device group. Ranjan et al. [10] reported the IKDC score as being 84.3 in the adjustable loop group and 85.2 in the fixed loop group. Ahn et al.(13) identified IKDC scores of  78.6 in the adjustable loop group and 79.43 in the fixed-loop device group. Asif et al. (14) assessed postoperative IKDC score 91.9 ± 3.6 in adjustable-loop device group and 91.5 ± 3.6 in fixed-loop device group. Our observations matched with the studies mentioned above.

 

Short femoral tunnel length is a critical issue of the Anteromedial (AM) portal technique, especially when using a fixed-loop device. In a cadaveric study on a Western population, the average femoral tunnel length using the anteromedial portal method was 30.5 mm [25]. Furthermore, five subjects had less than 30 mm femoral tunnel length. In these cases, fixed-loop device use can be compromised because of the short graft length within the femoral tunnel. Many alternative techniques have been suggested to overcome this issue and secure adequate femoral length during the operation. Some authors reported that knee flexion with an anteromedial portal technique can yield a longer femoral tunnel; therefore, the knee joint’s hyperflexion during the femoral tunnel drilling could avoid a short femoral socket [26, 27].  Since we created a femoral tunnel by drilling carefully with hyperflexion of the knee, we did not encounter any patient with a femoral tunnel less than 30 mm.

 

The two groups were compared by using independent t-test. In this study, functional outcome evaluated by IKDC scoring was nearly equal in Adjustable loop and fixed-loop cortical suspension devices group (P value – 0.92). It shows that there is no significant difference in the outcomes associated with the use of fixed-loop and Adjustable loop cortical suspension devices for ACL reconstruction.

 

Limitation:

The follow-up period of this study period was short.

Radiological outcome is not included in follow up.

Knee stability was assessed by subjective methods.

A larger number of sample size, more objective data with longer follow-up is required to more authenticate the study.

1.           Fu FH, Bennett CH, Ma CB, Menetrey J, Lattermann C. Current Trends in Anterior Cruciate Ligament Reconstruction: Part II. Operative Procedures and Clinical Correlations. Am J Sports Med. 2000 Jan;28(1):124–30.

2.           Zeng C, Lei G, Gao S, Luo W. Methods and devices for graft fixation in anterior cruciate ligament reconstruction. Cochrane Bone, Joint and Muscle Trauma Group, editor. Cochrane Database Syst Rev [Internet]. 2018 Jun 29 [cited 2022 Nov 15]; Available from: https://doi.wiley.com/10.1002/14651858.CD010730.pub2

3.           Eguchi A, Ochi M, Adachi N, Deie M, Nakamae A, Usman MA. Mechanical properties of suspensory fixation devices for anterior cruciate ligament reconstruction: Comparison of the fixed-length loop device versus the adjustable-length loop device. The Knee. 2014 Jun;21(3):743–8.

4.           Barrow AE, Pilia M, Guda T, Kadrmas WR, Burns TC. Femoral Suspension Devices for Anterior Cruciate Ligament Reconstruction: Do Adjustable Loops Lengthen? Am J Sports Med. 2014 Feb;42(2):343–9.

5.           Lubowitz JH. All-Inside Anterior Cruciate Ligament Graft Link: Graft Preparation Technique. Arthrosc Tech. 2012 Dec;1(2):e165–8.

6.           Choi NH, Yang BS, Victoroff BN. Clinical and Radiological Outcomes After Hamstring Anterior Cruciate Ligament Reconstructions: Comparison Between Fixed-Loop and Adjustable-Loop Cortical Suspension Devices. Am J Sports Med. 2017 Mar;45(4):826–31.

7.           Johnson JS, Smith SD, LaPrade CM, Turnbull TL, LaPrade RF, Wijdicks CA. A Biomechanical Comparison of Femoral Cortical Suspension Devices for Soft Tissue Anterior Cruciate Ligament Reconstruction Under High Loads. Am J Sports Med. 2015 Jan;43(1):154–60.

8.           Petre BM, Smith SD, Jansson KS, de Meijer PP, Hackett TR, LaPrade RF, et al. Femoral Cortical Suspension Devices for Soft Tissue Anterior Cruciate Ligament Reconstruction: A Comparative Biomechanical Study. Am J Sports Med. 2013 Feb;41(2):416–22.

9.           Götschi T, Rosenberg G, Li X, Zhang C, Bachmann E, Snedeker JG, et al. Biomechanical Evaluation of a Novel Loop Retention Mechanism for Cortical Graft Fixation in ACL Reconstruction. Orthop J Sports Med. 2020 Feb 1;8(2):232596712090432.

10.         Gamboa JT, Shin EC, Pathare NP, McGahan PJ, Chen JL. Graft Retensioning Technique Using an Adjustable-Loop Fixation Device in Arthroscopic Anterior Cruciate Ligament Reconstruction. Arthrosc Tech. 2018 Feb;7(2):e185–91.

11.         Challa S, Satyaprasad J. Hamstring graft size and anthropometry in south Indian population. J Clin Orthop Trauma. 2013 Sep;4(3):135–8.

12.         Iriuchishima T, Goto B, Okano T, Ryu K, Fu FH. Femoral tunnel length in anatomical single-bundle ACL reconstruction is correlated with height, weight, and knee bony morphology. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2019 Jan;27(1):93–9.

13.         Ahn JH, Ko TS, Lee YS, Jeong HJ, Park JK. Magnetic Resonance Imaging and Clinical Results of Outside-in Anterior Cruciate Ligament Reconstruction: A Comparison of Fixed- and Adjustable-Length Loop Cortical Fixation. Clin Orthop Surg. 2018;10(2):157.

14.         Asif N, Khan MJ, Haris KP, Waliullah S, Sharma A, Firoz D. A prospective randomized study of arthroscopic ACL reconstruction with adjustable- versus fixed-loop device for femoral side fixation. Knee Surg Relat Res. 2021 Dec 4;33:42.