Graft choices for anterolateral ligament knee reconstruction surgery: Current concepts

Abstract

The anterolateral ligament (ALL) is a primary structure of the anterolateral complex of the knee that contributes to internal rotational stability of the joint. Injury of the ALL is commonly associated with rupture of the anterior cruciate ligament. If left untreated, ALL lesions may lead to residual anterolateral rotational instability of the knee after anterior cruciate ligament reconstruction, which is a common cause of anterior cruciate ligament graft failure. The function of the ALL can be restored by lateral extraarticular tenodesis or anterolateral ligament reconstruction (ALLR). In the lateral extraarticular tenodesis procedure, a strip of the iliotibial band is placed in a non-anatomical position to restrain the internal rotation of the tibia, while in ALLR, a free graft is fixed at the insertion points of the native ALL. Gracilis and semitendinosus grafts have mainly been utilized for ALLR, but other autografts have also been suggested. Furthermore, allografts and synthetic grafts have been applied to minimize donor-site morbidity and maximize the size and strength of the graft. Nevertheless, there has been no strong evidence to fully support one method over another thus far. The present review presents a detailed description of the graft choices for ALLR and the current literature available in regard to the effectiveness and outcomes of published surgical techniques.

Key Words: Anterolateral ligament; Reconstruction; Lateral extraarticular tenodesis; Anterior cruciate ligament; Hamstrings; Gracilis; Semitendinosus

Core Tip: There is no convincing evidence regarding the biomechanical and functional superiority of either lateral extraarticular tenodesis or anterolateral ligament reconstruction procedures during anterior cruciate ligament reconstruction. Although hamstrings remain the most common graft choice for anterolateral ligament reconstruction, other autografts as well as allografts and synthetic grafts have been applied. Further research and comparative studies should be carried out to identify the most effective graft material and technique for the restoration of rotational knee stability in the presence of residual instability after anterior cruciate ligament reconstruction.

INTRODUCTION

The anterolateral ligament (ALL) is an independent structure of the anterolateral complex of the knee along with the lateral collateral ligament (LCL), the iliotibial band (ITB) and the anterolateral joint capsule[1,2]. There is no consensus so far on whether ALL bony attachment is located posterior and proximal or anterior and distal to the lateral femoral epicondyle or just on the lateral epicondylar together with the LCL attachment[3-7]. Its course is anterodistal and superficial to the LCL and its distal insertion midway between the anterior border of the fibular head and the Gerdy’s tubercle of the tibia[8]. The ALL is a nonisometric structure that tenses during knee flexion and internal tibial rotation and shows the greatest length change at 90° of flexion[9]. As a distinct structure of the anterolateral complex of the knee, the ALL seems to contribute to internal rotational stability of the joint, but its role in resisting rotational as well as anteroposterior instability in an anterior cruciate ligament (ACL) deficient knee is still controversial[10-13].

An ALL lesion is presented as a midsubstance strain and tear or avulsion of its bony insertion on the tibia, which is known as a Segond fracture[14]. The injury is most commonly associated with ACL rupture[5]. Concomitant ACL and ALL deficiency may result in increased knee rotational instability, which may not be restored by isolated anterior cruciate ligament reconstruction (ACLR)[15]. The incidence of positive pivot shift after ACLR could rise to 34% of operated cases, and many studies have demonstrated that additional ALL reconstruction (ALLR) decreases knee laxity and ACL graft failure rate and improves patient-reported outcomes[16-20]. On the other hand, simultaneous ALLR has been associated with overconstrained internal rotation and subsequent knee joint stiffness[21,22]. Furthermore, there is some evidence that ALLR does not decrease the rotational laxity of the knee to a desirable degree and its role in improving the postoperative function is limited[23,24]. Thus, simultaneous ACLR and ALLR have been suggested mainly in cases of grossly unstable pivot-shift and revision ACL surgery[25,26]. Moreover, indications for ALLR may include young patients who participate in pivoting activities as well as knees with chronic ACL deficiency or concomitant meniscal tears requiring surgical repair[27].

LITERATURE SEARCH

We conducted a narrative review using the MEDLINE online database regarding ALLR. The initial search applying the keywords “Anterolateral Ligament Reconstruction” led to 807 results. After abstract and full-text screening, 22 studies describing the results of ALLR in ACLR surgery were enrolled for further assessment (Figure 1). The extracted data were analyzed and organized to present the different reported methods of ALLR during ACLR in respect to graft choice, proximal and distal attachment location, stabilization technique and knee fixation angle (Table 1).

Figure 1 Flow-chart of graft types. ALLR: Anterolateral ligament reconstruction, LET: Lateral extraarticular tenodesis.

Table 1 Graft choices and fixation methods.

Ref.	ACL graft type	ALL graft type	Femoral fixation point	Tibial fixation point	Fixation Technique	Knee flexion/rotation
Lemaire and Combelles[36], 1980	BTB (hole for ITB graft)	ITB	Above the lateral epicondyle, proximal to the LCL insertion	Maintain attachment to Gerdy’s tubercle	Two bone tunnels, suture on itself	30º flexion/external rotation
Andrews and Sanders[41], 1983		ITB (two strips)	Lateral femoral epicondyle	Maintain attachment to Gerdy‘s tubercle	Suture strips together at medial femoral condyle after passing through two parallel lateral-to-medial tunnels	90º flexion/external rotation
Amirault et al[40], 1988		ITB	Above the lateral epicondyle, proximal to the LCL insertion	Maintain attachment to Gerdy’s tubercle	Suture fixation to ITB after passing through the lateral intermuscular septum	90º flexion/external rotation
Christel and Djian[37], 2002		ITB	Above the lateral epicondyle, proximal to the LCL insertion	Maintain attachment to Gerdy’s tubercle	Interference screw	30º flexion
Mathew et al[38], 2018		ITB	Anterior and proximal to the lateral gastrocnemius tendon	Maintain attachment to Gerdy’s tubercle	Richards staple and sutures to itself	60º flexion/neutral rotation
Abusleme et al[39], 2021		ITB	Above the lateral epicondyle, proximal to the LCL insertion	Maintain attachment to Gerdy’s tubercle	Suture fixation to ITB after passing through the lateral intermuscular septum	30º flexion/neutral rotation
Colombet[49], 2010	Quadruple (Semitendinosus double-bundle and gracilis double-bundle) or Double (single-bundle each)	Gracilis -semitendinosus (one bundle each)	Proximal to lateral epicondyle	Gerdy’s tubercule	Absorbable screws at each fixation point	90º flexion/neutral rotation
Helito et al[29], 2015	Quadruple (semitendinosus triple-bundle and gracilis single-bundle)	Gracilis (single-bundle)	3-4 mm below the halfway point on the Blumensaat’s line in the AP direction	5-10 mm below the lateral tibial plateau, between fibular head and Gerdy’s tubercle	One 5 mm metal anchors at each fixation point	60-90° of flexion/nm
Smith et al[45], 2015	Semitendinosus graft	Gracilis (double-bundle)	Anterior to lateral femoral epicondyle	Midway between fibular head and the Gerdy’s tubercle, 11 mm distal to joint line	4.75 or 5.5 mm bioabsorbable knotless suture anchor at each fixation point	30° of flexion/neutral rotation
Ferreira et al[48], 2016	Semitendinosus triple-bundle	Gracilis (double-bundle)	8 mm posterosuperiorly from lateral epicondyle	9-13 mm distal to lateral joint line, between fibular head and the Gerdy’s tubercle	Interference screw 2 mm larger than tunnel	45-60° flexion/nm
Sonnery-Cottet et al[44], 2016	Semitendinosus SAMBBA	Gracilis (double-bundle)	Proximal and posterior to lateral epicondyle	One superolateral margin of the Gerdy’s tubercle and one midway between fibular head and the Gerdy’s tubercle	4.75 or 5.5 mm bioabsorbable knotless suture anchor at each fixation point	Full extension/neutral rotation
Delaloye et al[47], 2018	Internal brace	Gracilis (double-bundle)	Proximal and posterior to lateral epicondyle	Bone tunnel: One point just anterior to the fibular head and second posterior to Gerdy’s tubercle	4.75 bioabsorbable knotless suture anchor at femoral fixation point	Full extension/neutral rotation
Saithna et al[18], 2018	Quadruple (Semitendinosus triple-bundle and gracilis single-bundle)	Gracilis (single-bundle)	Proximal and posterior to lateral epicondyle	Bone tunnel: One point just anterior to the fibular head and second posterior to Gerdy’s tubercle	Ethibond suture around the graft	Full extension/neutral rotation
Goncharov et al[46], 2019	BTB autograft	Gracilis or semitendinosus tendon autograft	Proximal to lateral epicondyle	10 mm distal to joint line, between fibular head and the Gerdy’s tubercle	Interference screws	Full extension/nm
Kim et al[50], 2020		Semitendinosus autograft	Proximal and posterior to lateral epicondyle	Midway between fibular head and the Gerdy’s tubercle	Interference screw at femur, adjustable length loop button at tibia	30° flexion/neutral rotation
Escudeiro de Oliveira et al[52], 2021	Quintuple, Semitendinosus double-bundle, gracilis double-bundle and peroneous longus single-bundle	Peroneous longus	Proximal and posterior to lateral epicondyle	15 mm distal to joint line, between fibular head and the Gerdy’s tubercle	Interference screws	30° flexion/nm
Josipovic et al[53], 2020	Quintuple, Semitendinosus triple-bundle, plantaris longus double-bundle	Plantaris longus	Proximal and posterior to lateral epicondyle	10 mm distal to joint line, between fibular head and the Gerdy’s tubercle	Interference screw at tibia	Full extension/nm
Wagih and Elguindy[59], 2016		Polyester tape	Distal and anterior to lateral femoral condyle	Midpoint between the Gerdy’s tubercle and the fibular head	Cortical suspension button proximally, tie on a bone bridge of two bone tunnels distally	30° flexion/nm
Lee et al[25], 2019	Tibialis anterior tendon allograft	Gracilis tendon allograft	Proximal and posterior to lateral epicondyle	10 mm distal to joint line, between fibular head and the Gerdy’s tubercle	Interference screws	30° flexion/neutral rotation
Chahla et al[57], 2016		Semitendinosus allograft	4.7 mm proximal and posterior to LCL insertion site	9.5 mm distal to joint line, between fibular head and the Gerdy’s tubercle	Interference screws	30° flexion/nm
Fernández et al[58], 2020	Achilles tendon allograft	Achilles tendon allograft	Proximal and posterior to lateral epicondyle	15 mm distal to joint line, between fibular head and the Gerdy’s tubercle	Staple at distal site	30° flexion/neutral rotation
Benum[42], 1982		Patellar tendon (lateral one-third with proximal bone block)	Femoral origin of LCL	Maintain attachment to tibial tubercle	Staple at femoral side	45º flexion/external rotation

ACL: Anterior cruciate ligament; ALL: Anterolateral ligament; AP: Anteroposterior; BTB: Bone-patellar tendon-bone; LCL: Lateral collateral ligament; ITB: Iliotibial band; nm: Not mentioned; SAMBBA: Single anteromedial bundle biological augmentation.

GRAFT TYPES AND TECHNIQUES

So far, many grafts have been applied for the restoration of ALL function, but no consensus exists regarding the ideal graft type and fixation technique. Controversies are based on the anatomic parameters of ALL regarding its bony origin and its length changes during knee motion. They are referred to graft material choice as well as graft insertion site location and fixation angle[6,8,23,28-33]. All the applied procedures aim to restore the knee kinematics in case of ALL deficiency and include either the lateral extraarticular tenodesis (LET) or ALLR techniques. The main principle of the LET procedure is the use of a strip of ITB that is stabilized proximally above the knee joint while its tibial insertion to Gerdy’s tubercle remains intact[34]. On the other hand, the ALLR aims to restore the ALL native features by fixing a free tendon graft between the anatomical femoral and tibial insertion points of the ALL[35].

AUTOGRAFTS

Iliotibial band

The ITB is exclusively used for the LET procedure. Lemaire[36] was the first who described the LET technique in cases of chronic ACL injuries. In the original procedure, the ITB was identified and a strip of 1 cm wide and 18 cm long was harvested, leaving the attachment to Gerdy’s tubercle intact. The graft was first passed in a distal to proximal direction under the LCL. Then, it was introduced to the distal femur through a bone tunnel above the lateral epicondyle and proximal to the LCL insertion. Consequently, it was passed again under the LCL in a proximal to distal direction and finally fixed to the tibia through a bone tunnel at Gerdy’s tubercle and sutured on itself. Fixation was completed in 30º of knee flexion and some tibial external rotation. In cases of combination with ACLR, LET allows for independent ACL graft choice. The authors also proposed a variation of the original technique by fixing the strip of ITB into the femoral tunnel that was created for bone-patellar tendon-bone graft ACLR.

Many modifications of the Lemaire procedure have been described referring to harvesting a shorter strip of tendon[37,38]. In addition, the graft may be stabilized proximally with sutures to the ITB after passing through the lateral intermuscular septum or with either a staple or an interference screw[37-40]. Andrews and Sanders[41] described a technique where two strips of ITB were harvested and passed through two parallel lateral-to-medial femoral tunnels and sutured together.

Moreover, variable knee flexion angles have been recommended during fixation, including 30º, 60º and 90º[38,39,42]. In respect to tibial rotation, older studies suggested that the tibia should be maintained in external rotation, but no specific angle was defined[40,41]. However, that position has been related to excessive restriction of internally rotatory movement and abnormal knee kinematics[34,43]. This overconstraint along with the non-anatomic nature of the LET procedure may lead to gradual elongation of the graft and subsequent recurrent rotational instability[43]. As a result, most recent studies have advocated a neutral rotation position for ITB graft fixation[38,39].

Gracilis tendon

Gracilis tendon (GT) is a commonly used autograft for ALLR. The free tendon graft is fixed proximally on the lateral femoral epicondyle and distally between the fibular head and Gerdy’s tubercle after passing between the ITB and LCL[19]. Most frequently, the graft is introduced proximal and posterior to lateral femoral, but a more anterior position has also been described[44,45]. Femoral fixation can be performed with an interference screw or an anchor[45,46]. The same principles are followed when concomitant ACLR is performed with either hamstrings graft, bone-patellar tendon-bone graft or internal brace[44-47].

The tibial attachment of the graft is placed between the fibular head and Gerdy’s tubercle approximately 5 to 13 cm distal to the lateral joint line[29,48]. Fixation is accomplished using an interference screw or an anchor[29,49]. Some authors have described ALLR in an inverted V-shaped fashion. Specifically, the graft is introduced in a tibial bone tunnel extending anterior to the fibular head and posterior to Gerdy’s tubercle and then is fixed at the femoral side with an anchor or with sutures around the graft[18,47]. Sonnery-Cottet et al[44] completed tibial fixation of the graft with two suture anchors. The first one was placed on the superolateral margin of the Gerdy’s tubercle and the other one midway between the fibular head and Gerdy’s tubercle.

During combined ALLR and ACLR using hamstring tendon autograft, a single graft is usually used for both procedures. After ACLR, the remaining graft is passed through a bone tunnel to the lateral surface of the distal femur, proximally and posteriorly to the lateral epicondyle[18,48]. Helito et al[29] identified the ALLR femoral tunnel location using fluoroscopy, aiming approximately 3-4 mm below the halfway point of the Blumensaat’s line in the anteroposterior direction. Furthermore, Ferreira et al[48] used a triple semitendinosus tendon (ST) graft for ACLR and a double GT graft for ALLR. Another combination is a four-strand ACL graft formed by a triple ST bundle and a single GT bundle, while the remaining GT is used for ALLR[29]. Colombet[49] also described the use of a quadruple ACL graft composed of two ST and two GT bundles. A double-bundle graft for ALLR was created from the excess tendon tissue of the bundles.

There is no consensus regarding the ideal fixation angle of a GT graft. Several different knee angles have been reported so far including full extension, 30º, 45º to 60º,60º to 90º and 90º[29,45,47-49]. In contrast, it has been generally accepted that the tibia should be maintained in neutral rotation at the time of graft stabilization[18,44,45].

Semitendinosus tendon

Apart from GT, the ST has been also widely used for ALLR[46]. Kim et al[50] harvested the contralateral ST for ALLR, as the ipsilateral ST had been already used for ACLR during the same or previous procedure. The double-bundle graft was first attached on the tibia (midway between the fibular head and Gerdy’s tubercle) using an adjustable length loop button, then passed deep to ITB and finally fixed posterior and proximal to the lateral femoral epicondyle with an interference screw, while the knee was positioned in 30º of flexion and neutral rotation. Additionally, Zarins and Rowe[51] proposed simultaneous ACLR and ALLR using only the ipsilateral ST. After proximal release, the ST was passed through the knee joint for ACLR, then exerted through a lateral femoral bone tunnel and tied to the ITB keeping the knee in 60º of flexion and tibial external rotation.

Peroneus longus

Escudeiro de Oliveira et al[52] reconstructed the ALL with an ipsilateral peroneus longus (PL) tendon graft and the ACL with a quintuple graft composed of a double-bundle ST, a double-bundle GT and a single-bundle PL. Specifically, the quintuple graft was initially used for ACLR, and the excess PL material was passed through a femoral tunnel, proximal and posterior to the lateral epicondyle, and was attached distally between the fibular head and Gerdy’s tubercle at 15 mm from the joint line. An interference screw was used in each attachment site, and during fixation the knee was kept at mild valgus and 30º of flexion. The authors supported the option of PL graft for ALLR as it could be easily harvested with minimal invasiveness. It was associated with low donor site morbidity and allowed adequate concomitant ACLR in combination with hamstring tendon autograft.

Plantaris longus

Josipovic et al[53] presented a technique of ALLR using the ipsilateral plantaris longus tendon. A quintuple graft composed of a three-strand ST and a two-strand GT was used for ACLR and a two-strand plantaris longus graft, which substituted the ALL, sutured to the quintuple graft. After the ACL graft fixation, the plantaris longus tendon was passed through a bone tunnel posterior and proximal to the lateral femoral epicondyle and fixed with an interference screw 10 mm distally from the joint line and midway between the fibular head and Gerdy’s tubercle, while the knee was fully extended. Although the authors reported good short-term results, there was a lack of data regarding the effectiveness of the technique.

Quadriceps and patellar tendon grafts

Historically, Marshall et al[54] presented the Marshall-MacIntosh procedure using an autograft of quadriceps tendon-prepatellar retinaculum-patellar tendon for concomitant ACL and ALL reconstruction. The distal attachment of the extensor apparatus to the tibial tubercle was preserved, and the graft was passed through a tibial and femoral bone tunnel over the top of the lateral femoral condyle and fixed on Gerdy’s tubercle. Dupont et al[55] presented a modification of the technique by harvesting a free graft including the bony attachment of the quadriceps tendon-prepatellar retinaculum-patellar tendon on the tibial tubercle. Additionally, Benum[42] reported the use of the lateral one-third of the patellar tendon with a proximal bone block for ALLR. The distal attachment on the tibial tubercle was preserved, and the graft was fixed with staples to the femoral origin of LCL.

ALLOGRAFTS

Some authors have recommended the application of allografts for ALLR, even in primary surgery, emphasizing the advantages of no donor site morbidity and availability of larger and longer grafts[56]. However, the use of allografts has been mainly suggested in revision surgery, where autografts may be not available in sufficient quantity[57]. Lee et al[25] used a GT allograft for ALLR in combination with tibialis anterior allograft for ACLR in the setting of revision surgery. Comparing ACLR with and without ALLR, they reported better outcomes after at least 3 years in terms of residual pivot shift, subjective IKDC score and Tegner score, return to the preinjury level of sports activity and possibility of revision surgery when ALLR was additionally performed. Chahla et al[57] underwent ALLR using an ST allograft mainly in cases requiring revision ACL surgery. However, they did not present any postoperative outcomes. Fernández et al[58] used an Achilles tendon allograft for both ACLR and ALLR in patients with previously failed ACLR and significant bone loss. They performed a two-stage procedure to fill the bone defect with a bone graft and to subsequently reconstruct the ACL and ALL. Still, no postsurgical outcome was reported.

SYNTHETIC GRAFTS (POLYESTER TAPE)

Wagih and Elguindy[59] reported an ALLR technique using polyester tape. The synthetic ligament was attached proximally anterior and distal to the lateral femoral condyle with a cortical suspensory button. Distally, the graft was inserted between the Gerdy’s tubercle and the fibular head and stabilized via sutures that tied on the medial side of the tibia through two bone tunnels. During fixation, the knee was placed in 30º of flexion. The authors suggested that polyester tape ALLR might be worth further investigation as it was a minimally invasive technique without donor site morbidity. Furthermore, the material could offer adequate strength with minimal possibility of laxity and postoperative failure. However, no details about the postoperative outcome were provided.

BIOMECHANICAL EVALUATION

The combination of ACLR with LET or ALLR can restore residual rotational laxity after isolated ACLR[60]. However, the LET procedure has been related to postoperative overconstraint of the internal rotation of the knee[34]. In a cadaveric study, Smith et al[34] reported similar results and equivalent restoration of knee kinematics between ALLR and LET after ACLR. Regarding knee position during graft fixation, Inderhaug et al[61] in a controlled ACLR laboratory study found that knee laxity was equally restored when ITB graft tenodesis was performed at 0º, 30º or 60º of knee flexion. On the other hand, ALLR using a GT graft achieved normal kinematics only when fixation was performed in full extension. Conversely, in another cadaveric study, Geeslin et al[62] found that both LET and ALLR were effective in reducing internal tibial rotation independently of the knee fixation angle or graft tension.

Additionally, Monaco et al[63] noticed that ALLR with GT showed superior biomechanical properties than LET, while the native ALL had lower failure load and stiffness compared to both grafts. Ra et al[64] found that LET resulted in similar rotational stability but worse anterior instability compared to ALLR. On the contrary, Spencer et al[65] reported that ALLR was less effective in reducing anterolateral rotational laxity than the LET procedure. Deviandri and van der Veen[66] used LET in four patients with residual rotational instability after ACLR and reported a significant improvement of knee kinematics.

In a recent meta-analysis, Yin et al[67] reported superior knee kinematics after combined ACLR and ALLR or LET compared to isolated ACLR in ACL deficient knees. Similarly, Littlefield et al[19] in a systematic review identified that supplementary ALLR during ACLR improved anterior tibial translation and internal knee rotation and resulted in a lower incidence of graft failure.

CLINICAL EVIDENCE

Current literature suggests that combined ACLR with ALLR or LET can improve clinical outcomes and decrease the possibility of ACL graft failure compared to isolated ACLR[43]. Beckers et al[68] observed that both LET and ALLR during ACLR provided superior Lysholm Score and reduced ACL re-rupture rate. Na et al[69] in a systematic review found that ALLR or LET along with ACLR were related to superior subjective IKDC, Tegner and Lysholm scores than isolated ACLR. However, the LET was associated with higher postoperative stiffness and complications than ALLR. Sonnery-Cottet et al[70] using data from 270 patients noticed that combined ACLR with ALLR led to a lower reoperation rate and better long-term graft survivorship but similar overall complication risk compared to isolated ACLR. The authors reported a 5-fold increase in the risk of ACL graft failure after a mean of 104 mo in cases of isolated ACLR. Similarly, in a systematic review of de Lima et al[71] the simultaneous ALLR and ACLR were related to better clinical outcomes than single ACLR, including higher success in return to sport and lower ACL graft rupture rate. The advantages and disadvantages of each technique are summarized in Table 2.

Table 2 Lateral extraarticular tenodesis and anterolateral ligament reconstruction Techniques: Advantages and disadvantages[39,72,73].

Advantages	Disadvantages
1. Lateral extraarticular tenodesis
Improvement of rotational knee stability	Non-anatomic procedure
Reduction of ACL graft failure rate	Possible over-constraining
Reproducible, easy-to-learn technique	May add pain to postoperative rehabilitation
Inexpensive procedure, especially when using high-resistance suture	Muscle herniation, if ITB closure is not performed in proper way
No risk of tunnel coalition when fixed with sutures proximally
2. Anterolateral ligament reconstruction
Improvement of rotational knee stability	Need ability to identify anatomic landmarks
Reduction of ACL graft failure rate	Use of allograft or synthetic results in increased cost
Preserves iliotibial band	Use of autograft requires additional surgery for graft harvest and possible donor site morbidity
Avoids lateral collateral ligament attachment
Secure graft fixation allows for early motion and accelerated anterior cruciate ligament rehabilitation

ACL: Anterior cruciate ligament; ITB: Iliotibial band.

DISCUSSION

Restoration of rotational stability is of paramount importance in the ACL injured knee. Apart from intraarticular ACLR, additional extraarticular procedures may be required to improve knee function and stability and minimize the risk for ACL graft failure. These include the LET and the ALLR with variable modifications of each procedure regarding the graft choice and fixation technique. Semitendinosus and gracilis are the main tendon grafts for ALLR, but other autografts such as peroneus longus, plantaris longus and quadriceps-patellar tendons have also been applied. Allografts and synthetic grafts are usually preferred in revision ACLR procedures where there is limited availability of autograft material for both ACLR and ALLR. Although all the available grafts for LET and ALLR may improve knee rotational stability, few studies with a relatively short follow-up and a small number of patients have been published so far. Therefore, there is inconclusive evidence to favor one method over the others in terms of biomechanical properties and clinical outcomes. Further large-scale studies are required to clarify the benefit of ALLR during primary or revision ACLR procedures. Particularly, future randomized control trials should compare ACLR with or without ALLR in young, active and high-demand patients by using different graft types. The research should focus on the subgroup of patients with large pivot-shift and operated meniscal tears aiming to find a potential correlation between ALLR and failure of ACLR under these conditions.

CONCLUSION

According to the current review and existing literature, there is no convincing evidence regarding the biomechanical and functional superiority of either LET or ALLR procedures during ACLR. Although hamstrings remain the most common graft choice for ALLR, other autografts as well as allografts and synthetic grafts have been applied with satisfactory results and low complication rate. However, a pooled analysis of all published raw data would further improve the quality of the review and related evidence despite the heterogeneity of the studies.