Outcomes after revision anterior cruciate ligament reconstruction - A prospective observational study

INTRODUCTION

Revision anterior cruciate ligament reconstructions (ACLRs) have increased with time because of the significant rise in the failure rates (5-25%) of primary ACLR. Young patients participating in high-intensity athletic activities are at a higher risk.^[1,2] Many causes contribute to failed anterior cruciate ligament (ACL) reconstruction which can be broadly classified into five categories: (i) Technical errors such as tunnel malposition, inadequate graft fixation, or graft size; (ii) biological factors such as poor graft incorporation, infection, and tunnel widening; (iii) traumatic re-injury; (iv) missed associated injuries such as anterolateral ligament (ALL), posterior cruciate ligament (PCL)/posterolateral corner (PLC) injuries, and malalignment; and (v) patient profiles such as young age, females, high body mass index, and poor compliance with rehabilitation protocols.^[3,4]

The results following revision ACLR have largely been difficult to predict, with higher rates of graft re-rupture (between 3.5% and 33%) even when experienced surgeons performed the revision.^[5,6] Revision ACLR involves removing and debriding the previous ACL graft and replacing it with a new graft using either the previous femoral/tibial tunnel or making new tunnels, along with concurrent additional procedures such as lateral extra-articular tenodesis (LET), PLC reconstruction, or high tibial osteotomy (HTO) as needed. Due to the scarcity of research in this area, especially in the Indian context, we conducted a study to determine the functional outcome after revision ACLR.

MATERIALS AND METHODS

This prospective observational study was conducted on 30 patients at the Department of Orthopaedics, Pt. B.D. Sharma Post Graduate Institute of Medical Sciences (PGIMS), Rohtak (Haryana) for over 1 year. The inclusion criteria included patients aged between 15 and 50 years and patients requiring revision ACL reconstruction with or without concurrent procedures. On the other hand, patients with PCL and medial collateral ligament (MCL) injuries, active infection, those with major chondral injuries of the knee, and those undergoing subtotal/total menisectomy were excluded. Furthermore, patients with dilated femoral and tibial tunnels requiring bone grafting and staged revision ACL reconstruction were also not included.

The diagnosis of an ACL-deficient knee was made based on the Lachman test, the anterior drawer test (ADT), and the pivot shift test. The integrity of the MCL and LCL was tested using the valgus stress test and the varus stress test, respectively. The dial test was performed to look for a PLC injury. The clinical diagnosis was confirmed by magnetic resonance imaging scan, and a scanogram was done to look for limb malalignment. After the analysis, the surgery was planned accordingly. The decision to perform any concurrent procedure was based on clinical and radiographic findings as shown in Table 1. Informed written consent was obtained from all subjects, and ethical clearance was obtained from the Institutional Ethics Committee.

Operative procedures

Revision ACL reconstruction using the same femoral and tibial tunnel

The standard portals for ACLR (anterolateral and anteromedial) were made, torn and non-functional ACL graft debrided, both tunnels were found in good anatomical position, using a shaver and curette both femoral and tibial tunnels were debrided and wall margin freshened, and autografts in the form of peroneus longus tendon and contralateral semitendinosus graft (if needed) were folded and fashioned to make a thick graft of minimum 9-10 mm diameter. The graft was then routed through the same tibial and femoral tunnels and fixed on the femoral side using appropriate-sized closed loop EndoButton and biodegradable screw on the tibial side.

Revision ACL reconstruction bypassing the previous femoral and tibial tunnel

The standard arthroscopic procedure was followed as described above to debride the earlier ACL graft. If the femoral tunnel was found in non-anatomical position, i.e., too vertical, a new anatomical tunnel was made using the antero-medial portal drilling technique, near to 10 o’clock position. This allowed accurate placement within the footprint of the native ACL. Similarly, if the tibial tunnel was found to be non-anatomical, i.e., too anterior or posterior, a new tibial tunnel was drilled bypassing the earlier tibial tunnel tract medial or lateral to it. In almost all cases, the intra-articular aperture of the tibial tunnel was the same, but the tract in the tibial metaphysis was fashioned separately from the earlier tibial tunnel tract. The autograft (tripled peroneus longus or semitendinosus plus gracilis of the contralateral side) was routed through the new tunnel and fixed [Figures 1 and 2].

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Figure 1:

(a) Revision anterior cruciate ligament reconstruction using the same tibial tunnel. (b,c) Bypassing the previous femoral tunnel. (d) Fixing the new graft.

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Figure 2:

To demonstrate an arthroscopic image of revision anterior cruciate ligament reconstruction and clinical outcome. (a) Intra op arthroscopy image, (b) Pre op magnetic resonance imaging, (c) Post op X-ray, (d-f) Clinical photos showing patient’s ability to squat and full range of motion at knee.

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Revision ACL reconstruction with HTO

The standard arthroscopic procedure was done, and arthritic changes in the medial compartment of the knee were confirmed. The femoral tunnel was drilled either using the same femoral tunnel (enlarged by reamer to 1 mm size more than the previous tunnel to freshen the tunnel walls) or through a new femoral tunnel. Furthermore, guide wires were passed in the tibial metaphysis starting just above the pes anserinus and directed toward the head of the fibula under fluoroscopic guidance. An electric saw was used to make biplanar cuts, and a gauged chisel was used to open the wedge up to size as calculated preoperatively for the correction of varus malalignment. The osteotomy was fixed with a TomoFix plate (Arbeitsgemeinschaft für Osteosynthesefragen Swiss) [Figure 3a-e]. Care was taken not to alter the tibial slope while opening the wedge, and special care was taken to fix the TomoFix plate as posterior as possible so that anteriorly, there was space to fashion a standard tibial tunnel. Again, either through the same/new tibial tunnel, the prepared graft was routed and fixed.

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Figure 3:

Revision anterior cruciate ligament reconstruction with high tibial osteotomy as a concurrent procedure. (a) Pre-operative X-ray, (b) high tibial osteotomy, (c) Graft inserted in freshly created tibial tunnel, (d) Fixation of graft on tibial side, (e) Post-op X-ray

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Revision ACL reconstruction with LET

Revision ACLR was first done using the techniques mentioned before. The modified Lemaire technique was used to perform the LET procedure.^[7] A curved lateral side incision was made starting from Gerdy’s tubercle to the lateral epicondyle. A 1 cm broad strip of tensor fascia lata (TFL) was harvested by amputating it in mid-thigh while keeping the distal insertion at Gerdy’s tubercle intact so that at least 10-12 cm length is achieved. The strip of TFL was routed underneath the fibular collateral ligament and fixed on the lateral distal femur epicondylar area at the isometric point that was generally 2-3 mm proximal and posterior to the lateral epicondyle, using a tendon staple keeping the knee in 30° flexion and slight abduction and external rotation [Figure 4].

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Figure 4:

(a) Harvesting a strip of tensor fascia lata (marked F), cutting proximally while preserving the distal insertion, (b) fascia lata graft (marked F) passed underneath the lateral collateral ligament (marked L).

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Revision ACL reconstruction with PLC reconstruction

This procedure was done in patients with varus instability and anteroposterior instability due to a failed previous ACL graft. Revision ACLR was done first. A standard PLC reconstruction was done using modified Larson’s technique.^[8] An incision was made laterally, from the fibular head to the lateral femoral epicondyle [Figure 5]. The common peroneal nerve was dissected proximally at the undersurface of the biceps femoris and traced to the fibular neck, and an infant feeding tube was used to isolate the common peroneal nerve. A 4.5 mm cannulated drill bit was used to make an anteroposterior tunnel, slightly oblique, in the fibular head. A single-stranded semitendinosus autograft was routed through this tunnel, and both free ends were routed below the TFL proximally and fixed at an isometric point only on the femoral epicondylar area using a bioscrew, keeping the knee in slight valgus and 20° flexion. No fixation was done in the fibular tunnel.

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Figure 5:

Revision anterior cruciate ligament reconstruction with modified Larson procedure as a concurrent procedure. (a) Graft passed through the fibular tunnel, (b) Graft passed beneath the tensor fascia lata, (c) Graft fixed to isometric point with bioscrew.

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The incisions were closed in a standard layered fashion. An antiseptic dressing was applied. A knee immobilizer was applied in full extension. Post-operative rehabilitation was commenced as per standard protocol.

Patients were followed up for one year. They were assessed based on clinical and radiological parameters. Age, sex, height, weight, and mechanism of injury were noted. Technical causes of failure, such as improper tunnel position and improper fixation methods, were noted. The functional outcome was assessed per Tegner Activity Scale, Lysholm score, and IKDC subjective score. Complications related to surgery and graft were also reported.

Statistical analysis was done with the Statistical Package for the Social Sciences 22.0. Continuous variables were presented as mean ± standard deviation (SD). Categorical variables were expressed as frequencies and percentages. The Pearson’s chi-square test or Fisher’s exact test was used to determine the relationship between two categorical variables. A P < 0.05 was taken for all statistical tests to indicate a significant difference.

RESULTS

In this study, the mean age was 26.40 ± 6.52 years (range: 18-50 years). Among 30 patients, a male preponderance (70%) was seen, and the right side was involved in 17 (56.7%) patients and the left side in 13 (43.3%) patients. Sports-related injuries accounted for 53.3% (16 patients) while falls, road traffic accidents (RTAs), and weightlifting contributed 30% (9 patients), 10% (3 patients) and 6.7% (2 patients), respectively. In our study, the pre-operative Lachman and ADT were grade 2 in 4 patients (13.3%) and 6 patients (20%), respectively. They were grade 3 in 20 patients (66.7%) and 16 patients (53.3%), respectively. Lachman test was grade 4 in 6 patients (20%), whereas ADT was grade 4 in 8 patients (26.6%). Pivot shift test was found to be positive in 24 patients (80%) and negative in the rest.

DISCUSSION

Arthroscopic ACLR has been reported to lead to failure rates up to 25% necessitating revision ACLR.^[9,10] The most common technical risk factors include improperly positioned tunnels, poor graft fixation, improper graft selection, high posterior tibial slope, and failure to diagnose/address concomitant injuries such as the ALL/PLC injuries and varus malalignment.^[3,4] However, there is evidence to show that the results of revision ACLRs are inferior to a primary ACLR.^[11] Therefore, we conducted a prospective observational study on 30 patients at the Department of Orthopaedics, Pt. B.D. Sharma PGIMS, Rohtak (Haryana) over one year.

The age range of patients in this study was 18-50 years, the mean age being 26.40 ± 6.52 years with a male preponderance. This is in line with observations made by Trung et al. and Rhatomy et al.^[12,13] and can be attributed to the propensity of young males to perform more vigorous athletic activities. The most common mode of injury was found to be sports-related injuries. This is in contrast to the study by Khajotia et al. who reported RTAs as the most common cause in their study. In the Indian context, this is probably due to more youngsters participating in athletic activities in this part of the country.^[14]

An important finding in this study is that most ACL reconstructions failed due to technical reasons (36.6%) wherein femoral tunnel malposition was the most common reason. It is pertinent to mention that the techniques used to create the femoral tunnel in primary ACLR were not found in any of the patient records. The tunnel was found to be exceedingly vertical or anterior, which is consistent with the findings of most studies.^[3,4] This anterior malposition often leads to loss of flexion and recurrence of instability. Several techniques have been described in the literature to create a new tunnel on the femoral side. These include a single anatomic oval femoral tunnel,^[15] over-the-top technique,^[16] two-stage approach with bone grafting, and the rectangular tunnel technique.^[17,18] The anteromedial portal drilling technique offers a time-tested standard, as it has been proven to allow for an independent and more anatomic placement of the femoral tunnel.^[19] This surgically reproducible technique, however, requires careful execution to avoid complications like posterior blowout.^[20] In our study, we have employed this technique in all our cases without any intraoperative complications.

Tibial tunnel malposition, a less commonly seen complication, has been reportedly managed using staged bone grafting, a rectangular tunnel, and outside-in drilling techniques. However, we revised them using the tibial tunnel-first graft-sizing method, wherein the same tunnels were sequentially enlarged after reaming them with increasing diameter reamers. Our results were consistent with those of Kim et al., as it was relatively easier to reproduce due to its simplicity, giving good functional outcomes.^[21]

Another finding of this study is that true traumatic reinjury of a well-positioned and well-fixed graft also contributes to the failure of a primary ACLR. This can be ascribed to the tendency of high-demand patients to go back to their previous type of sports at the same level after ACLR and institution of an overzealous rehabilitation protocol, which can interfere with ACL graft integration and ligamentization. The accelerated rehabilitation protocol, as described by Shelbourne for primary ACLR, seems to be inappropriately used in certain patients, leading to reinjury.^[22]

Graft overload leading to failed ACLR has been reported due to an undiagnosed concomitant PLC injury. A high index of suspicion must be there, especially in cases with high velocity RTAs/low velocity sporting activities in a hyperextended and varus position. Dean and LaPrade advocated that when the workup indicates a combined acute PLC and ACL injury, reconstruction or a combined hybrid repair should ideally be performed within 3 weeks of injury. They concluded that the failure to address the PLC immediately leaves the ACL graft under increased tension, and acute reconstruction/repair allows for anatomic reconstructions as the native anatomic landmarks can be properly identified in most cases.^[23] In our series, we performed a concomitant PLC reconstruction in two cases that produced excellent functional outcomes akin to the study by van Gennip et al., who confirmed the effectiveness of Larson’s PLC reconstruction procedure in correcting posterolateral instability in knees with multiple ligament injuries, with a significant decrease in lateral compartment opening on stress radiographs compared to pre-operative values.^[24]

Coronal plane misalignments like varus alter the mechanical axis of the lower limb and negatively affect the medial compartment of the knee during weight bearing, thereby increasing stress on the ACL. ACLR failure may be attributed to an increased tibial slope and should be addressed for good functional outcomes in a revision case. As per Noyes, correction of varus before ACLR is essential to combat the challenges of a primary, double, or triple varus deformity.^[25] To address this challenge, an open wedge/closed wedge HTO can be done. While close wedge HTO results in decreased tibial slope, it has been said that the correction is difficult to fine-tune and that it is a more complex procedure involving common peroneal nerve dissection and proximal tibiofibular joint disruption.^[26] In our series, four patients underwent medial open wedge HTO as a concomitant procedure with revision ACLR, leading to decreased forces on the posteromedial tibial plateau and thereby producing excellent functional outcomes at 2-year follow-up.

Bernholt et al. mentioned in their study that persistent anterolateral rotary instability occurring after ACL reconstruction leads to poor patient outcomes and increased risk of graft failure; thus, LET procedures may be able to help improve patient outcomes when used as an adjunct to ACL reconstruction by helping to unload the ACL and restore normal rotational stability.^[27] In our series, we performed 12 cases with a concomitant LET repair using the modified Lemaire technique in patients with a grade 3 pivot shift test, with good functional outcomes in all of them.

While it has been established across the literature that revision ACL reconstruction results in inferior functional outcomes as compared to a primary ACL reconstruction, our results (as shown in results and compared in Table 3) depict significant improvement in the mean functional scores.^[11,28-30] Our study has limitations of a shorter follow-up and a relatively small cohort. However, our study highlights the potential causes of primary ACL reconstruction failures along with operative details of tunnel management while doing revision ACL reconstruction and the functional results after revision ACL reconstruction with and without concurrent procedures in a single series.

CONCLUSION

Revision ACLR remains a complex surgical challenge, often compounded by the need for concurrent surgeries. Our study demonstrates that tailored revision strategies with the integration of adjunct procedures such as LET, HTO, or PLC reconstruction can lead to clinically relevant improvements in pain, stability, and functional outcomes at 1 year postoperatively. As sports medicine continues to evolve within the country, these findings support the feasibility and effectiveness of advanced revision ACL techniques in achieving favorable mid-term outcomes.