Considerations for revision anterior cruciate ligament reconstruction: A review of the current literature

Abstract

Background

Failure rates among primary Anterior cruciate ligament reconstruction range from 3.2 to 11.1 %. Recently, there has been increased focus on surgical and anatomic considerations which predispose patients to failure, including excessive posterior tibial slope (PTS), unaddressed high-grade pivot shift, and improper tunnel placement.

Methods

The purpose of this review was to provide a current summary and analysis of the literature regarding patient-related and technical factors surrounding revision ACLR, rehabilitation considerations, overall outcomes, and return to sport (RTS) for patients who undergo revision ACLR.

Results

In revision ACLR patients, those receiving autografts are 2.78 times less likely to experience a re-rupture compared to patients who receive allografts. Additionally, individuals with properly positioned tunnels and removable implants are considered strong candidates for one-stage revision procedures. Conversely, cases involving primary tunnel widening of approximately 15 mm are typically indicative of two-stage revision ACLR. These findings underscore the importance of graft selection and surgical approach in optimizing outcomes for patients undergoing revision ACLR.

Conclusion

Given the high rates of revision surgery in young, active patients who return to pivoting sports, the literature recommends strong consideration of a combined ACLR + anterolateral ligament (ALL) or lateral extra-articular tenodesis (LET) procedure in this population. Unrecognized posterolateral corner (PLC) injury is a common cause of ACLR failure and current literature suggests concurrent operative management of high-grade PLC injuries. Excessive PTS has been identified as an independent risk factor for ACL graft failure. Consider revision ACLR with combined slope-reducing tibial osteotomy in cases of posterior tibial slope greater than 12°.

1. Introduction

The anterior cruciate ligament (ACL) plays a pivotal role in knee stability by restricting anterior tibial translation and internal rotation, while also influencing external rotation and angulation. ACL injuries constitute approximately 64 % of athletic knee injuries, resulting in 60,000–200,000 ACL reconstructions (ACLR) annually in the United States.1, 2, 3, 4 The escalating rate of ACL injuries correlates with an uptick in revision ACLR procedures.^5,6 Factors contributing to primary ACLR failure encompass technical errors, instability, and graft failure.⁶ Revision ACLR exhibits a higher failure rate (approximately 13.7 % in athletes) compared to primary ACLR (ranging from 3.2 % to 11 %), with inferior clinical outcomes.7, 8, 9, 10, 11, 12, 13, 14, 15 Modifiable variables such as graft characteristics and technical considerations are under scrutiny to pinpoint risk factors. This review aims to dissect the causes of graft failure post-revision ACLR and provide guidance to surgeons in managing primary graft failure.

2. Technical considerations for performing revision ACL reconstruction

2.1. Graft type

The debate surrounding graft selection for revision ACLR arises due to limited availability from prior surgeries. A study by the MARS group tracked 1205 patients postoperatively, revealing that autografts predicted better outcomes in terms of International Knee Documentation Committee (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS) sport, and KOOS quality of life scores.¹⁶ Autograft recipients were 2.78 times less likely to experience reinjury compared to allograft recipients. However, no difference was found between soft tissue and bone-patellar tendon-bone (BTB) grafts.¹⁶ At the 6-year post-op mark, the risk of re-rupture continued to rise in the allograft cohort, with allograft recipients being 3.9 times more likely to sustain re-rupture than autograft patients, and BTB allograft recipients were 4.2 times more likely to sustain re-rupture than BTB autograft recipients.¹⁶ Controlling for age, sex, and baseline activity level showed no difference in graft failure rate between cohorts.¹⁷

Another investigation conducted by the MARS group employed logistic regression modeling to establish a propensity score for revision ACLR graft type.¹⁸ This score encompassed various factors, including sex, age, ethnicity, smoking status, BMI, sport, activity level, previous graft type, number of revisions, operating surgeon, surgeon opinion of failure, and technical details from the primary reconstruction (such as concomitant procedures and fixation devices).¹⁸ While patient-specific variables like general activity level or demographics are typically regarded as strong predictors of graft choice, this study revealed that surgeon preference wielded the greatest influence, approximately five times more impactful than the prior graft type, which emerged as the second most significant predictor.¹⁸ Given that graft selection significantly impacts long-term success, surgeons can leverage current literature to inform their treatment strategies in revision ACLR, potentially overcoming previous constraints.

2.2. One-stage vs. two-stage revision reconstruction

Choosing between one-stage and two-stage revision is a critical decision, supported by abundant literature on the topic. A 2021 systematic review by Colatruglio et al. found only two studies directly comparing these techniques, both reporting no difference in failure rates concerning functional, radiographic, or patient-reported outcomes.¹⁹ Additionally, results from studies isolating one-stage or two-stage reconstructions demonstrated similar average weighted scores for Lysholm (83.4 across 5 studies vs. 78.1 across 4 studies), IKDC (66.6 across 6 studies vs. 65.9 across 3 studies), and Tegner (6.2 across 4 studies vs. 4.2 across 2 studies), suggesting that both types of revision reconstructions can produce satisfactory outcomes.¹⁹

Patients with properly positioned tunnels and removable implants are considered ideal candidates for one-stage revisions. In cases where previous graft tunnels do not obstruct anatomic tunnel placement, previous hardware can be disregarded while performing a one-stage revision with anatomic tunnel placement. On the other hand, two-stage revision is indicated when primary tunnel widening is observed.²⁰ During preoperative planning, computed tomography (CT) imaging has demonstrated superiority over magnetic resonance imaging (MRI) and is deemed the gold standard for evaluating tunnel size and position.²¹ If the tunnel has widened to approximately 15 mm, evidence suggests that a two-stage revision should be considered.^20,21 However, this threshold remains relative, as there is insufficient evidence to definitively determine the point at which a two-stage reconstruction becomes necessary.²¹

2.3. Pre-operative imaging

MRI serves a crucial role in assessing the extent of ACL injury and identifying concurrent ligamentous damage, which may not be immediately evident. Although CT imaging remains the gold standard for evaluating tunnel size and position, MRI can reveal additional ligamentous injuries that might compromise the revision construct. A study focusing on posterolateral corner (PLC) injuries recommended MRI in cases of suspected acute PLC injury.²² Moreover, MRI enables surgeons to comprehensively evaluate bony morphology, graft integrity, tunnel positioning, and associated ligamentous injuries, all of which could contribute to an increased risk of revision failure.²³

2.4. High grade pivot shift: ALL and LET

Recurrent pivot shift incidents following primary ACLR frequently result in re-rupture. Anterolateral complex reconstruction, incorporating procedures such as ALL reconstruction or lateral extra-articular tenodesis (LET), can aid in restoring knee joint rotation.^23,24 However, there is currently insufficient direct evidence available to compare the efficacy of these two techniques.²⁵

Grassi et al.'s systematic review investigated LET in revision ACLR. Among the 11 studies analyzed, 3 employed the Lemaire or modified versions, 3 used the Cocker-Arnold technique, and 3 utilized an over-the-top approach with the intra-articular graft remnant.²³ Additionally, two studies incorporated an extra-articular portion of the iliotibial band for intra-articular reconstruction, one with revision ACLR alone and another with revision ACLR with ALL reconstruction.²³ Across 7 studies, 83 % of patients achieved grade 0 pivot shift, while only 2 % experienced grade II or III. Subjective scores were consistent, with a weighted average Lysholm score of 88.9 at final follow-up across 7 studies.²³ Nearly 75 % of patients returned to sports, though only 41 % returned to their pre-injury level.²⁶ The STABILITY trial, a randomized controlled trial involving patients under 25, demonstrated that adding LET to ACLR using hamstring autograft significantly decreased graft rupture and persistent rotational laxity.²⁷

In a study conducted by Lee et al., 87 patients underwent either revision ACLR alone or combined with concurrent anterolateral ligament (ALL) reconstruction.²⁴ Findings at final follow-up indicated significantly improved IKDC, Tegner, and ACL Return to Sport after Injury scores in the ALL-reconstruction group. However, there was no significant difference observed in anterior laxity or functional tests between the two groups. Notably, the ALL-reconstruction cohort demonstrated reduced rotational laxity and a higher rate of return to the same level of sport compared to the isolated ACLR group (57.1 % vs. 25.6 %).²⁴

2.5. Excessive posterior tibial slope

Excessive posterior tibial slope (PTS) is a critical consideration in revision ACLR. PTS exceeding 12° and high-grade laxity are recognized risk factors for graft failure, and osteotomy to correct slope, combined with LET, can aid in stability restoration.28, 29, 30, 31 A biomechanical study by Imhoff et al. revealed that a 10° anterior closing-wedge osteotomy significantly reduces anterior tibial traction in ACL-deficient knees.²⁹ Clinically, there seems to be a direct association between postoperative tibial slope and ACL graft failure rates. Estimates indicate failure rates of 7 % for knees with a tibial slope of less than 7.5°, 24 % for slopes between 7.5° and 12.5°, and 36 % for slopes exceeding 12.5°.³² Additionally, a meta-analysis by Dean et al. compared PTS measurements based on ACL status and found that patients with failed ACLR demonstrated larger mean PTS values compared to those with primary ACLR or intact ACLs.

Excessive posterior tibial slope (PTS) poses a significant concern in revising ACLR. When PTS surpasses 12° alongside high-grade laxity, it becomes a recognized risk factor for graft failure.28, 29, 30, 31 Correction of slope through osteotomy, often combined with LET, can contribute to restoring stability.28, 29, 30, 31 Imhoff et al.'s biomechanical investigation illustrated that a 10° anterior closing-wedge osteotomy notably diminishes anterior tibial traction in ACL-deficient knees.²⁹ Clinically, there appears to be a direct correlation between postoperative tibial slope and ACL graft failure rates.³² Estimates suggest failure rates of 7 % for knees with a tibial slope under 7.5°, 24 % for slopes between 7.5° and 12.5°, and 36 % for slopes exceeding 12.5°.³² Moreover, Dean et al.'s meta-analysis, comparing PTS measurements across different ACL statuses, revealed that patients with failed ACLR exhibited larger mean PTS values compared to those with primary ACLR or intact ACLs.³³

2.6. Meniscal deficiency

The role of the medial meniscal posterior horn (MPH) is pivotal in restraining anterior tibial translation (ATT) in ACL deficient knees.³⁴ Research indicates that in the absence of an ACL, excessive ATT under loading causes the MPH to interact with the femoral condyle, essentially serving as a wedge against the tibia.^29,35 Prolonged engagement in this manner leads to irreversible damage to the meniscus. Patients with concurrent chronic MPH tears persisting for more than 6 months following ACL injury have demonstrated notably elevated failure rates after undergoing isolated ACLR, as noted by Song et al.³⁶ Considering the MPH's function as a secondary knee stabilizer and the increased susceptibility to injury in an ACL-deficient knee, early reconstruction should be considered for high-risk patients.

2.7. Posterolateral corner (PLC) injuries

The posterolateral corner (PLC) of the knee encompasses the fibular collateral ligament, the popliteus tendon, and the popliteofibular ligament, collectively providing both dynamic and static stability to prevent hyperextension, varus angulation, and external rotation of the tibia.37, 38, 39 About 75 % of PLC injuries involve damage to either cruciate ligament, with 7.4%–19.7 % of ACL injuries occurring concurrently with PLC injury.^40,41 In knees lacking PLC integrity, increased stresses on the ACL during varus movements may contribute to ACL rupture.^42,43 A national registry study comparing primary to revision ACLR revealed that PLC injury during ACL revision negatively impacted KOOS scores at 1 year.⁴⁴ While there is limited research on PLC injury in revision ACLR, prior studies on primary ACLR suggest that addressing acute PLC and ACL injuries, along with multi-ligament reconstruction, is ideally performed early and as a single-stage operation.45, 46, 47 A systematic review conducted by Moulton et al. showcased a reduced failure rate in combined PLC and ACLR when performed as a single stage, compared to a stepwise approach.⁴⁶

2.8. Varus alignment

Several studies have suggested that ACLR in varus knees might face failure if alignment issues are left unaddressed.41, 48, 49 A biomechanical investigation conducted by van de Pol et al. revealed that severe varus alignment, coupled with varus-thrust, led to excessive tension on the ACL graft, thereby contributing to graft failure.⁴¹ Won et al. observed that patients undergoing revision ACLR were more likely to present with varus alignment exceeding 5° compared to those undergoing primary ACLR.⁴⁸ Furthermore, multiple studies have demonstrated that symptomatic varus-aligned patients who undergo high tibial osteotomy (HTO) during ACLR tend to experience improved clinical outcomes.^31,49,50 Hence, HTO should be considered for young patients with varus malalignment undergoing revision ACLR.

3. Rehabilitation and bracing

After surgical revision of failed ACL grafts, adhering to a rigorous rehabilitation regimen is crucial for optimizing recovery and increasing the likelihood of returning to sports.⁵¹ Therapy plans should be tailored to each patient, considering factors like surgical techniques, graft selection, occupational demands, physical performance, patient characteristics, and expectations. Additional procedures performed alongside revision ACLR can influence postoperative rehabilitation, affecting weightbearing status, recovery duration, and overall morbidity to a greater extent. Comprehensive rehabilitation programs following revision ACL grafts play a pivotal role in enhancing recovery and facilitating a return to sports.⁵²

While there isn't a universal rehabilitation protocol, data from the MARS group on the use of functional bracing during recovery from revision ACLR suggests promising results.¹⁸ Patients who utilized an ACL brace during their return to sports reported significantly improved KOOS sport and recreational activity scores at the 2-year mark.¹⁸ However, those prescribed an ACL brace postoperatively were notably more likely to require subsequent surgery within the same timeframe.¹⁸ This suggests that wearing a brace may encourage earlier participation in high-level activities or offer perceived additional protection, highlighting the substantial influence of rehabilitation-related factors on overall outcomes.⁵³

3.1. Outcomes and RTS

In general, return-to-sport (RTS) rates following revision ACLR are lower than those observed after primary ACLR, with reported rates ranging from 56 % to 100 %. Furthermore, the rates of returning to the same level of play are even lower, varying from 13 % to 69 %.⁵⁴ A systematic review conducted by Glogovac et al. highlighted that patients undergoing revision ACLR face greater difficulties in returning to their pre-injury level of play compared to individuals undergoing primary ACLR.⁵⁴

In the realm of revision ACLR, outcome assessments extend beyond RTS rates and exhibit notable diversity. Nevertheless, a consistent observation emerges regarding the superior clinical outcomes linked with autograft reconstruction. Comparative analyses conducted by the MARS group showcased that autograft consistently resulted in superior scores across various measures including IKDC, KOOS sport, and KOOS quality of life. Furthermore, patients who received autografts were significantly less susceptible to experiencing graft failure.⁵⁵

4. Algorithm

From our review, we have created the following algorithm for evaluating a patient with a failed ACL reconstruction and factors to consider when performing a revision reconstruction (Fig. 1).

Fig. 1.

Algorithm for performing revision ACL reconstruction.

5. Limitations

The nature of this study is a review of the current literature regarding considerations regarding revision ACLRs. This study presents a broad overview of the evidence pertaining to this topic, irrespective of study quality, and to clarify key concepts and identify gaps. Therefore, although the authors have attempted to summarize the available literature, the evidence base presented here does not weigh the quality of each individual study.

6. Conclusion

Given the high rates of revision surgery in young, active patients who return to pivoting sports, the literature recommends strong consideration of a combined ACLR + anterolateral ligament (ALL) or lateral extra-articular tenodesis (LET) procedure in this population. Unrecognized posterolateral corner (PLC) injury is a common cause of ACLR failure and current literature suggests concurrent operative management of high-grade PLC injuries. Excessive PTS has been identified as an independent risk factor for ACL graft failure. Consider revision ACLR with combined slope-reducing tibial osteotomy in cases of posterior tibial slope greater than 12°. A thorough review of previous tunnel placement should be done to determine whether a one-stage or two-stage reconstruction should be performed.

Ethical statement

This systematic review was IRB exempt.

Funding sources

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Guardian/patient's consent

Due to the review nature of this study, patient consent was not needed.

CRediT authorship contribution statement

Bryson Kemler: Methodology, data collection, Data curation, Writing – original draft, Writing – review & editing. Carlo Coladonato: data collection, Writing – original draft, Writing – review & editing. Andres Perez: Formal analysis, Writing – review & editing. Brandon J. Erickson: data collection, Writing – review & editing. Fotios P. Tjoumakaris: data collection, Writing – review & editing. Kevin B. Freedman: Conceptualization, Supervision, Writing – review & editing.

Declaration of competing interest

One or more of the authors has declared the following potential conflict of interest or source of funding: K.B.F. is a paid consultant: Medical Device Business Services, Inc and Innocoll, Inc; honoraria from Vericel Inc; education, travel, and lodging from Liberty Surgical, Inc; and is a board or committee member for AOSSM. F.P.T. is a paid consultant for Medical Device Business Services, Inc; Research support from Smith & Nephew; and holds stock in Franklin/Keystone Biosciences, LLC, and Trice Medical, Inc. B.J.E.: is a board or committee member AOSSM, ASES; Arthrex, Inc: Paid consultant; Research support DePuy, A Johnson & Johnson Company, Linvatec, Smith & Nephew, Stryker PLOS One: Editorial or governing board.