Early clinical outcomes of over-the-top anterior cruciate ligament reconstruction combined with lateral extra-articular tenodesis

Abstract

BACKGROUND

The anterior cruciate ligament (ACL) ensures knee stability in anterior-posterior and rotational directions. Arthroscopic ACL reconstruction (ACLR) is the gold standard for ACL injuries. Although modified Lemaire lateral extra-articular tenodesis (LET) is increasingly used, high-quality evidence on ACLR combined with LET remains limited. Given that combining over-the-top (OTT) with ACLR and modified Lemaire LET shows limited efficacy in high pivot-shift patients, this study retrospectively evaluated short-term outcomes. We hypothesize this approach significantly improves rotational stability, supports return to sports, and achieves good short-term clinical results.

AIM

To confirm short-term efficacy of over-the-top ACL reconstruction with lateral extra-articular tenodesis for primary ACL tear and positive pivot shift.

METHODS

Fifty-six patients (34 males; 22 females) aged 15-45 years (mean age, 28 ± 10.5 years) with ACL injuries (22 left knees and 34 right knees) characterized by a high pivot shift who had undergone OTT ACL reconstruction in conjunction with modified Lemaire LET between March 2020 and October 2022 were included. The time from injury to surgery was 10-32 days. Outcomes (Lysholm, International Knee Documentation Committee, KT-2000) were recorded preoperatively and during a 24-month follow-up period.

RESULTS

All patients were followed up for a minimum of 24 months and successfully returned to sports activities. Both pivot-shift and Lachman tests were negative postoperatively. At the 24-month follow-up, magnetic resonance imaging revealed no ACL retears. The Lysholm score increased from 60.5 ± 4.5 to 92.4 ± 2.6 (P < 0.001), International Knee Documentation Committee score increased from 52.3 ± 2.6 to 92.8 ± 3.0 (P < 0.001), and KT-2000 side-to-side difference decreased from 5.4 ± 1.0 mm to 1.4 ± 0.3 mm (P < 0.001).

CONCLUSION

OTT-ACLR combined with the modified Lemaire LET is associated with improved knee rotational stability in patients with high pivot-shift ACL injuries, facilitating their return to sports with favorable short-term clinical outcomes.

Key Words: Anterior cruciate ligament reconstruction; Over-the-top; Anterolateral complex; Modified Lemaire procedure; Arthroscopic surgery

Core Tip: This study summarizes the clinical characteristics and treatment progress of patients with anterior cruciate ligament (ACL) tear accompanied by high grade pivot-shift test. We found that the over-the-top ACL reconstruction combined with lateral extra-articular tenodesis can effectively improve the clinical outcome and reduce complications, providing a reliable reference basis for the clinical diagnosis and treatment of ACL tear accompanied by high grade pivot-shift test.

INTRODUCTION

The anterior cruciate ligament (ACL) is a critical anatomical structure that maintains knee stability, particularly anteroposterior and rotational stability. The incidence of ACL rupture is increasing, and arthroscopic ACL reconstruction (ACLR) remains the gold standard for treating ACL injuries, with annual procedures in the United States exceeding 200000[1]. However, factors, such as poor tendon-bone healing, aggressive rehabilitation protocols, and postoperative reinjury, pose significant risks for ACL retear[1]. Additionally, 25% of patients experience knee instability[2], which can induce cartilage damage, meniscal injury, and traumatic arthritis[3].

Recent studies have highlighted the significance of the anterolateral complex (ALC), including the anterolateral ligament (ALL), joint capsule, superficial iliotibial bundle, iliopatellar bundle, deep iliotibial bundle, and Kaplan fibers, emphasizing its role in anterolateral knee rotational stability. This type of instability in the tibiofemoral joint is characterized by combined sagittal plane linear laxity (anterior translation) and axial rotatory abnormalities (internal rotation)[4,5]. ACL tears are often aggravated by concomitant injuries to the ALC, which increase the risk of rotational instability. If left untreated, these injuries increase the risk of retear and subsequent meniscal damage, leading to further instability, with pivot shift serving as an important clinical indicator[6]. Although some studies have reported positive outcomes with ALL reconstruction[7], lateral extra-articular tenodesis (LET) may offer a more cost-effective solution. Furthermore, ACLR combined with LET can increase career longevity for athletes[8,9].

Over the past decade, research has clearly demonstrated that the ACL is a crucial structure that maintains anterior and rotational stability of the knee joint. Reconstruction or augmentation surgery after an ACL injury can improve rotational stability postoperatively. The clinical application of the modified Lemaire LET fixation technique has become increasingly widespread, but high-quality studies evaluating the clinical efficacy of ACLR combined with LET are still relatively scarce[10,11]. Given the limited clinical evidence on the effectiveness of combining over-the-top (OTT) ACLR with modified Lemaire LET in patients with high-grade pivot shifts, this study retrospectively evaluated the short-term clinical outcomes in this population.

MATERIALS AND METHODS

Inclusion and exclusion criteria

Inclusion criteria comprised the following: (1) Diagnosis of ACL tear based on clinical evaluation and magnetic resonance imaging (MRI); (2) Age 15-45 years; (3) Pivot shift test grade II or above; (4) Complete follow-up data [International Knee Documentation Committee (IKDC), Lysholm, KT-2000, MRI]; and (5) Follow-up duration of ≥ 24 months. The exclusion criteria were as follows: (1) Concomitant ipsilateral periprosthetic fracture; (2) Presence of generalized multiple joint laxity; (3) Poor lower limb alignment(Mechanical Axis Deviation> 15 mm); (4) History of knee surgery on the affected limb; (5) Preexisting conditions that hinder follow-up and postoperative rehabilitation; and (6) Incomplete follow-up data.

General information

Fifty-six patients (34 males, 22 females) aged 15-45 years (mean age, 28 ± 10.5 years) with sports-related ACL injuries (22 left knees, 34 right knees) characterized by a high-grade pivot shift (≥ grade II) who had undergone OTT ACLR combined with LET using the modified Lemaire technique between March 2020 and October 2022 were retrospectively analyzed. Preoperative knee flexion and extension ranged from 0° to 90°-120°. The patients included in this study had no alignment abnormalities. Preoperative MRI confirmed ACL injuries and excluded posterior cruciate ligament and other ligament injuries. This study was approved by the Ethics Committee of our hospital (Ethics approval No. 2023-175-01). All methods adhered to the relevant guidelines and regulations, and informed consent was obtained from all patients.

Surgical methods

Arthroscopic examination: Depending on the patient’s condition, spinal or general anesthesia was administered with the patient in the supine position. The pivot shift and Lachman tests were performed post-anesthesia, with all cases exhibiting ≥ grade II instability. Routine arthroscopic examination was performed to assess the meniscus and articular cartilage. If necessary, a posterior medial portal was established to evaluate the meniscus for ramp lesions. Arthroscopic examination confirmed that all cases involved ACL rupture.

Preparation of grafted tendons: Autologous hamstring tendon grafts were used for ACLR. Each graft had a diameter of 7.5 mm to 8.5 mm and minimum length of 12 cm. The tunnel diameter was determined based on the diameter of the graft tendon.

Drilling of tunnels: A 2-mm Kirschner wire was drilled into the joint to identify the center of the ACL tibial footprint. The knee was then slowly straightened to confirm that there was no impingement between the Kirschner wire and the intercondylar notch.

OTT and graft passage: The lateral femoral epicondyle was identified, and a 4-5 cm longitudinal incision was made along the iliotibial band (ITB). The posterior aspect of the intercondylar notch was observed under arthroscopic visualization of the anterolateral portal. An angled clamp was used to gently elevate the posterolateral capsule into the joint, and a small window was created through the posterolateral capsule. The lateral femoral condyle was prepared to create a bleeding surface. The suture was passed through the OTT from the posterolateral window to the anteromedial portal. A suture was then passed through the graft.

Modified Lemaire LET: The ITB was exposed both proximally and distally through the same lateral incision. The distal attachment of the ITB was preserved. An 8-cm long and 1-cm wide strip of the ITB was harvested. A soft-tissue passage was created beneath the fibular collateral ligament. The femoral fixation point for LET was located immediately anterior to the insertion of the distal Kaplan fibers and approximately 1 cm posterior to the lateral femoral epicondyle. After confirming appropriate isometric positioning, the ITB graft was secured with a bioabsorbable interference screw (Mitek, United States) under 10 lb of traction[12].

ACL graft fixation

The grafted tendon was pulled through the tibial tunnel under arthroscopic guidance and slowly passed through the intercondylar notch in the OTT position. The femoral end of the grafted tendon was fixed using a double-suture absorbable anchor (Mitek, United States) and implanted 3-5 mm medial to the lateral femoral condyle. The tibial end of the grafted tendon was fixed using absorbable screws under 20 lb of traction[13].

Postoperative rehabilitation protocol

All patients were instructed to begin ankle pump exercises to prevent venous thrombosis. On postoperative day 2, the patients were fitted with an adjustable knee brace and mobilized with crutches, with partial weight-bearing on the affected limb. Straight leg-raising exercises were initiated to strengthen the quadriceps muscles. The brace was removed 2 months postoperatively. Squatting was avoided for the first 3 months postoperatively, and contact sports were prohibited for 6 months. Light yoga and squat training were gradually introduced. A progressive return to physical activity and increased exercise intensity were permitted 9 months postoperatively.

Clinical evaluation

Clinical data, including those from the Lachman and pivot shift tests, were recorded preoperatively under anesthesia and postoperatively. Complications, including graft retear, incision infection, deep vein thrombosis, joint fibrosis, complications related to internal fixation (such as screw irritation), and nerve and vascular injury, were recorded. The rate of return to sports (defined as return to practice or performance but not at the same level as before) was also recorded. All patients were followed up in the outpatient clinic at 1 month, 3 months, 6 months, 12 months, and 24 months postoperatively. The IKDC score[14], Lysholm score[15], and KT-2000 side-to-side difference[16] were recorded preoperatively and at 3 months, 6 months, 12 months, and 24 months postoperatively. MRI (Siemens, Germany) was performed to evaluate graft healing. All postoperative clinical examinations were performed without anesthesia.

Statistical analysis

Statistical analyses were performed using IBM SPSS Statistics (version 26.0; IBM Corp., Armonk, NY, United States). Continuous variables are expressed as means ± SD. Comparisons of IKDC scores (preoperative, 3 months postoperatively, and 24 months postoperatively), Lysholm scores, and KT-2000 side-to-side differences across multiple time points were performed using analysis of variance, with multiple comparisons performed using Q-tests. All tests were two-sided, with P < 0.05 considered statistically significant.

RESULTS

General results

All patients were followed up for at least 24 months. No graft rupture, bone tunnel fracture, or nerve injury was observed intraoperatively. After ACLR combined with LET, the pivot shift test was negative, and there was no graft impingement or instability during repeated knee flexion and extension. There were no instances of incision-related complications or infection. At the time of the final follow-up, all patients returned to sports without experiencing knee stiffness or ACL rupture. The mean surgical duration was 70.2 ± 12.2 minutes (range, 68-92 minutes; Table 1).

Table 1 Patient demographics and general information.

Characteristic	mean ± SD/n (%)
Age	28 ± 10.5
Follow up period (months)	26.6 ± 2.3
Surgery time (minutes)	70.18 ± 12.17
Sex
Male	34 (60.7)
Female	22 (39.3)
Knee side
Right	34 (60.7)
Left	22 (39.3)
Rerupture
Yes	0 (0)
No	56 (100)

Knee stability

Under anesthesia, there were zero cases of grade I, 40 cases of grade II, and 16 cases of grade III pivot shift and zero cases of grade I, 39 cases of grade II, and 17 cases of grade III instability according to the Lachman test. Both the pivot shift and Lachman tests were negative immediately postoperatively. At the 24-month postoperative follow-up, three patients had pivot shift grade I and four patients had Lachman test grade I; however, these patients reported feeling well (Table 2).

Table 2 Knee stability.

Characteristic	Pre-operative	Post-operative
Pivot-shift test
I	0	3
II	40	0
III	16	0
Lachman test
I	0	4
II	39	0
III	17	0

Functional scores

The Lysholm score, IKDC score, and KT-2000 side-to-side difference showed significant improvement from preoperatively to 24 months postoperatively, with the Lysholm score increasing from 60.5 ± 4.5 to 92.4 ± 2.6, the IKDC score increasing from 52.3 ± 2.6 to 92.8 ± 3.0, and the KT-2000 side-to-side difference decreasing from 5.4 ± 1.0 mm to 1.4 ± 0.3 mm, respectively (P < 0.001; Table 3).

Table 3 Knee function scores and KT-2000 results before and after surgery.

	Preoperative (mean ± SD)	Postoperative (mean ± SD)		P value	P value1
		3 months	24 months
Lysholm score	60.5 ± 4.5	72.4 ± 4.2	92.4 ± 2.6	< 0.001	< 0.001
IKDC score	52.3 ± 2.6	58.0 ± 2.2	92.8 ± 3.0	< 0.001	< 0.001
KT-2000 side-to-side difference (mm)	5.4 ± 1.0	1.6 ± 0.7	1.4 ± 0.3	< 0.001	< 0.001

¹Comparison of 2 years postoperative with preoperative.

IKDC: International Knee Documentation Committee.

MRI

MRI of the knee at the 24-month follow-up showed no meniscal tears or cartilage lesions in any patient. Sagittal T1-weighted imaging revealed a normal bone marrow signal intensity. Oblique sagittal T2-weighted imaging showed a uniformly low signal intensity of the reconstructed ACL without evidence of graft impingement within the intercondylar notch. Coronal T2-weighted imaging showed satisfactory graft incorporation at the posterosuperior aspect of the lateral femoral condyle (Figure 1).

Figure 1 Thirty-seven-year-old male with an anterior cruciate ligament injury and grade III pivot shift. A: Preoperative sagittal T2-weighted image (T2WI) showing increased and heterogeneous signal intensity of the anterior cruciate ligament (ACL) (arrow); B and C: Preoperative (B) coronal and (C) axial T2WI showing absence of the ACL, indicated by the low signal intensity within the intercondylar notch (arrow); D: Sagittal T2WI obtained 24 months postoperatively showing a reconstructed ACL graft with uniform low signal intensity (arrow); E: Coronal T2WI obtained 24 months postoperatively showing the graft in a stable position posterior to the lateral femoral condyle without displacement (arrow); F: Axial T2WI obtained 24 months postoperatively showing the fixation screw used for lateral extra-articular tenodesis (arrow).

Complications

There were no tunnel fractures, graft retears, nerve injuries, or vascular injuries in any of the patients. Additionally, there were no postoperative complications, such as incisional or intra-articular infections, venous thrombosis, knee stiffness, or myositis ossificans of the quadriceps muscle. At the final follow-up, the reconstructed ACL in all cases showed favorable outcomes without any instances of rerupture.

DISCUSSION

The pivot shift test, a classical physical examination for ACL injuries, is crucial for assessing rotational knee stability. A positive pivot shift test indicates ACL injury, which can be exacerbated by a concomitant lateral meniscus injury, ALC (ALL) injury, and abnormalities of the ITB and posterior tibial slope[17-21]. In one study, 80%-90% of patients who underwent OTT ACLR and ALC augmentation following an ACL injury achieved satisfactory functional outcomes and quality of life at the 10-year follow-up, with a long-term survival rate of 96%[22]. Mid- and long-term follow-up studies also suggest that combined ACL and ALC reconstruction provides superior stability compared to single- and double-bundle ACLR, resulting in faster recovery[23]. For patients with grade II or III pivot shifts, ACLR combined with ALC reconstruction or augmentation improves postoperative rotational knee stability compared to ACLR alone[24]. Our findings of improved pivot-shift grading are consistent with those of previous reports showing that addressing anterolateral instability via LET or ALL reconstruction can reduce postoperative rotatory laxity.

Currently, most studies identify the following as indicators for combined ALC reconstruction or augmentation during ACLR: High-grade preoperative pivot shift, severe rotational instability (including revision ACL surgery), age < 25 years, and participation in sports requiring high rotational stability. These criteria are reflected in national and international consensus statements; however, surgical indications vary among experts, and the literature remains inconsistent regarding the exact role of ALC reconstruction in improving rotational stability and whether it may excessively limit internal rotation[25]. There is a lack of consensus regarding the anatomical and morphological factors that contribute to high-grade pivot shifts and their role in anterior rotational knee stability, highlighting the importance of identifying the anatomical structures responsible for rotational instability during ACLR[25]. In this study, all patients had a high-grade pivot shift under anesthesia. After ACLR combined with LET using the modified Lemaire technique, the pivot shift tests were negative immediately postoperatively. At the 24-month postoperative follow-up, all patients had successfully returned to sports without rotational knee instability, reflecting the favorable clinical outcome of this procedure. Therefore, we hope that future high-quality studies will further evaluate the surgical indications and clinical efficacy of LET.

The OTT ACLR technique, developed over 20 years ago at the Rizzoli Institute[26,27], remains widely utilized in orthopedic centers worldwide. A biomechanical study conducted on a porcine model demonstrated that ACLR using the OTT technique improves rotational knee stability compared with traditional single-bundle ACLR and can be used for both primary and revision ACLR[28,29]. The OTT technique provides both anterior and rotational stability, in contrast to the total intraepiphyseal technique[30]. In this study, postoperative KT-2000 measurements showed that ACLR using the OTT technique significantly improved anteroposterior knee stability, whereas the postoperative pivot shift test indicated good control of rotational stability. Based on existing research, the clinical outcomes of the OTT technique applied to primary ACLR, regardless of epiphyseal maturity, are widely recognized. Therefore, the implementation of the OTT technique for ACLR in this study was supported by both theoretical and clinical foundations. Clinical follow-up showed that none of the patients experienced ACL rerupture within 2 years, and functional assessments (Lysholm and IKDC scores) demonstrated significant improvement. MRI revealed adequate maturity of the grafted tendon, reinforcing the clinical effectiveness and feasibility of the OTT technique for primary ACLR. The favorable outcomes observed in this study may be associated with patient selection and the relatively short follow-up duration. Therefore, further high-quality prospective studies are needed to confirm the clinical efficacy of this surgical procedure.

OTT ACLR also showed good biomechanical stability at high knee flexion angles[31]. It has been suggested that ligaments maintain good biomechanical stability during knee flexion following ACLR using the OTT technique. Furthermore, it has been noted that the ligaments exhibit proportional laxity during knee flexion post-reconstruction[32]. This phenomenon may be related to the isometric properties of the graft. In this study, the bone at the intersection of the intercondylar fixation point and lateral condyle was moderately ground during the surgical procedure, and no ligamentous laxity was observed during knee flexion and extension under arthroscopy, demonstrating favorable isometric properties. In another study involving 273 patients who underwent ACLR using OTT, 244 were reviewed 3-9 years postoperatively; of these, 71% achieved excellent or good outcomes, whereas most of the 29% with fair or poor outcomes had degenerative meniscal changes. Notably, 11 patients showed arthroscopic and histological evidence of successful graft healing[33]. While biomechanical models support favorable graft isometry with OTT techniques, our study was not designed to directly evaluate biomechanical parameters. However, the postoperative knee function scores in this study reflect knee joint stability.

The posterolateral bundle of the ACL plays a crucial role in maintaining rotational knee stability. Double-bundle ACLR can effectively enhance both anteroposterior and rotational stability; however, owing to stringent surgical criteria, this approach is not suitable for all cases[34]. Recent studies have confirmed that the ALC functions as a secondary stabilizing structure of the knee joint, primarily limiting the internal rotation of the tibia, which significantly contributes to controlling axial displacement[35]. The biomechanical functions and advantages of LET have been extensively studied, with reports on its ability to limit translation within the lateral compartment, reduce pivot shift, protect the graft and meniscus, and improve clinical outcomes[36,37]. No statistically significant differences in patellofemoral cartilage health were observed between knees at 2 years after primary ACLR with hamstring tendon autografts, regardless of whether LET was performed[38]. In this study, postoperative MRI showed no evidence of patellofemoral cartilage injury, further supporting the idea that LET surgery can effectively control knee joint stability. These findings are consistent with those of the aforementioned studies. However, the LET procedure also has potential risks, including excessive restriction of the internal rotation of the tibia, which could lead to biomechanical changes in the knee joint, increased pressure in the lateral compartment, and resultant degeneration, as well as complications related to the peroneal collateral ligament or the ITB.

CONCLUSION

OTT ACLR combined with modified Lemaire LET for the treatment of primary ACL injuries with a high-grade pivot shift was associated with improved rotational knee stability and facilitated the patients’ return to sports, demonstrating favorable short-term clinical outcomes.