1 Introduction

The anterior cruciate ligament (ACL) is an integral part of the knee joint which provides both anteroposterior as well as rotatory stability. Rupture of ACL leads to instability which in turn will cause injury to the menisci as well as articular cartilage damage. Sports activities are the most common causes of ACL rupture but, they can also occur in other injuries like Road traffic or workplace accidents. Among athletes involved in multidirectional or contact sports, the annual incidence is 0.7%–5% (men's baseball and women's gymnastics) whereas in the general population, it is much lower.¹ Bilateral ACL tears are much more uncommon, making up only 2%–4% of all the ACL tears^2,3 and simultaneous injury to both ACLs is only restricted to reports and seldom case series in the published literature.^4–7

There is no consensus whether a single stage reconstruction of bilateral has to be performed or whether it has to be staged. In a US national survey,⁴ 76.2% of surgeons who have operated on at least one patient with bilateral knee ACL insufficiency, responded that they would prefer a staged procedure; whereas 90% of the surgeons who have not treated anyone with bilateral ACL insufficiency stated they would perform the procedure in a single stage.

We provide our experience with single staged bilateral ACL reconstruction as a safe, reproducible and a reliable procedure. In this study we also compared the functional outcomes among two variables, simultaneity of the injury and presence or absence of associated meniscal tears.

2 Materials and methods

After obtaining the approval of Institutional ethics committee, this restrospective study was started. In the period 2013 to 2021, 33 patients underwent bilateral ACL reconstruction in a single stage in our institution. All the subjects were male patients with an average age of 33.3 years (range 17–56 years). Patients were given a clear explanation about the procedure and consent was obtained. Functional outcome scores including IKDC and Tegner Lysholm scores were filled by the patients during the admission preoperatively. Of the 33 patients, one patient underwent revision ACL reconstruction and primary ACL reconstruction in the other knee so he was excluded from the study.

Documentation of all the patients who underwent bilateral ACL reconstruction was retrieved from the Electronic medical records. Patients' charts were screened and the demographic data as well as the pre-operative and intraoperative findings were recorded in an Excel spreadsheet. Preoperative patient-reported functional outcomes were recorded in the spreadsheet. Patients were examined by the operating surgeon at regular intervals. The latest functional outcomes were assessed with IKDC, and Tegner Lysholm activity scores on telephonic interview by the primary investigator and entered into the spreadsheet.

2.1

2.1 Surgical technique

After obtaining informed consent from the patient and relatives and a pre-anesthesia checkup, patients were taken up for surgery. All the patients were operated by 1 of the 3 senior surgeons in the hospital under combined spinal epidural anesthesia given by a senior anesthesiologist. After the patient was anaesthetized, the patient was positioned supine with the feet reaching the tip of the bed. Tourniquet cuffs were tied as proximally as possible in both the thighs and were connected to two separate tourniquet machines. Both the lower limbs were painted with 10% Betadine™ solution for 3 coats and then received and draped with disposable surgical drapes. Finally a double “O" is used to keep both limbs free. While performing the procedure on one limb, the other one is wrapped in a waterproof drape (Fig. 1).

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Fig. 1 Operation theatre setup showing Arthroscopy being performed in the left knee and right knee draped with a water proof sheet.

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One knee is exsanguinated using an Esmarch bandage and the tourniquet is inflated to usually to 280 mm of Hg which in some cases may change depending on the patient condition. Standard anterolateral and anteromedial portals are made and a diagnostic round is performed. Once the ACL tear is confirmed, menisci are assessed. An oblique incision is given in the anteromedial aspect of the proximal leg to expose the Semitendinosus and Gracilis tendons. Semitendinosis tendon is harvested with a closed stripper and length and thickness are assessed and if sufficient, it is used; if not, gracilis is harvested as well and prepared by the assistant.

While the assistant is preparing the harvested Hamstring tendons(s), the surgeon proceeds with the preparation of the medial wall of the lateral femoral condyle; the femoral tunnel is made with transportal technique making sure that there is a good posterior wall. Following this, the tibial tunnel is made using an aiming jig and impingement assessed. The surface of the tibia at the mouth of the tunnel is cleared off the soft tissues to allow smooth passage of the graft. A nylon loop is passed through the femoral tunnel and then retrieved through the tibial tunnel. Prepared graft along with a fixed loop endobutton is passed under arthroscopic vision. Once the button is flipped, it is confirmed by the senior surgeon. Then, after removing the slack in the graft by performing cyclical manoeuvre, holding the tibial side graft firmly, an appropriate size interference screw is passed with the knee in 30° flexion and a posterior thrust is given on the proximal tibia. In our institution, we use a padded bolster to keep the knee in 30° flexion. Now, the graft is assessed for tautness under arthroscopy with a probe as well a Lachmann test is performed. The incision given for graft harvest is closed in layers and the portal stab incisions are closed with 3–0 Ethilon™. A compression dressing is applied and a waterproof drape sheet is wound around the operated leg and a similar procedure is performed on the opposite side.

In our institution, we change the instrumentation and get a new set of instruments for the second knee. We have two monitors, so one is used for the first knee and the other monitor is used by the surgeon for the second knee.

After both the side operations are done, long knee braces are applied on both knees and the patient is carefully transferred to the ward for post-operative monitoring and care.

Postoperative pain was managed with a top up given in to the epidural catheter with 0.5% Bupivacaine and Morphine just before shifting the patient from recovery room in the Operation theatre complex to the post operative ward. Dosage was titrated depending on the patient's general condition by the senior anaesthesiologist. In addition to this, they were also given NSAIDs (Tab Aceclofenac twice a day along with a PPI).

3 Results

All the 32 patients who underwent single-stage bilateral ACL reconstruction were males surprisingly. The mean age of the patient population was 33.3 years (range 17–56 years). Out of the 32 patients, 25 (78%) patients had the injury in two different situations, which led to ACL insufficiency whereas there was a simultaneous ACL tear in 7 (22%) patients and the modes of injury as shown in Fig. 2. Meniscal injuries associated are listed in Table 1 and the treatment modalities used in Fig. 3. Follow up period was an average of 6 years (range of 2–10 years). A total of 5 patients have completed 10 years when the data was collected. The preoperative IKDC scores mean 45.6 (range 17.2–71) which was increased to a mean of 82.9 (range 59.8–95) postoperatively at the final follow-up. Lysholm's scores were a mean of 50.85 (range 21–69) improved to a mean of 87.3 (range of 64–94). (See Table 2).

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Fig. 2 Modes of injury. RTA – Road traffic accident. Different modes of injury are listed in this pie diagram.

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Fig. 3 Treatment modalities used for meniscal tears included Meniscal debridement, excision and balancing, partial and subtotal excision, all of which are included in excision group. Repair included inside out as well as all inside repairs.

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A total of 27 patients (84.3%) returned to work within 2 months from the date of operation and the remaining 5 patients (15.7%) returned to work at 3 months post-op. 35% of patients (n = 12) had started playing the sports to their pre-injury level by 12 months, 31.3% (n = 10) between 13 and 18 months, 1 patient took more than 18 months but 28.1% patients (n = 9) never went back to their pre-injury level.

Simultaneous bilateral ACL injury was noted in 21.9% (n = 7) and non simultaneous injury in 78.1% (n = 25) of our study population. We compared the functional outcomes between these two groups. There was no statistically significant difference among them.

Surgical duration that was taken for a single side was on average 80.24 min (Range from 33 min to 125 min) and the time that was taken to finish both the sides was on average 165.76 min (range from 114 min to 218 min). The time duration that took to deflate the tourniquet of one side followed by exsanguinating the second side and inflating the second tourniquet was at an average of 5.48 min (range from 2 min to 19 min).

4 Discussion

Bilateral ACL injuries are quite rare when compared to unilateral ones. Unilateral ACL injuries were reported to be 68.6 per 100,000.⁸ Only 2%–4% of the total patients with ACL injuries were found to have bilateral ACL injuries.^9,10 The majority of the patients presenting with bilateral ACL insufficiency give a history of trauma to each knee at a different instance and a few of them have a simultaneous injury in both the knees leading to ACL rupture.^10,11 Out of the 32 patients in our study, we found out that 25 patients had non-simultaneous injuries and 7 had a simultaneous bilateral ACL rupture in a single incident. Cost and rehabilitation time advantages of sinlge stage bilateral ACLR were clearly noted and proven in the literature.^11–13

Different grafts were used in single stage bilateral ACL reconstructions as in unilateral ones, Hamstrings, Patella tendon, autografts as well as allografts. Jari and Shelbourne¹² used patella tendon autografts in all the 28 subjects who underwent single stage reconstruction and comparatively found that their pain and functional scores were similar to those in unilateral ACL reconstruction. Patella tendon allografts were used in 9 of the 11 patients who underwent bilateral ACL reconstruction and they found two graft failures in the study published by Larson et al.¹¹. In 5 out of 7 patients, the surgeon used Hamstring grafts and found no difference when compared with unilateral ACL reconstruction.¹³ Hamtrsing graft was used in 14 patients in the study published by Panigrahi et al.¹⁴ and at a follow up, a mean of 28 months, 86% were very satisfied on subjective Numeric rating scale (NRS) and 14% were satisfied (NRS 4–7) but none of the patients were unsatisfied. In this study, Hamstring graft was used in all 32 patients but in one patient for whom a Central quadriceps tendon was used to augment the hamstring. At a mean follow up of 6 years, IKDC and Lysholm scores were improved and none of the patients had graft failure. This study showcases a single staged consecutive bilateral ACL reconstruction and not a true simultaneous bilateral ACL reconstruction as published by Saithna et al.¹⁵ in which they used two arthroscopy towers and two teams of surgeons and nurses etc were used. In our case, we used a single Arthroscopy tower with an accessory monitor and a change of instruments and gloves was performed.

Post-operative functional outcome scores were measured using patient-filled IKDC scores and Tegner Lysholm scores. At an average follow-up of 6 years (range of 2–10 years), IKDC scores have improved from an average of 45.6 (range 17.2–71) to 82.9 (range 59.8–95). Tegner Lysholm's knee score has also improved from 50.85 (range 21–69) to 87.23 (range 64–94). Using the grading of Lysholm knee, none of the patients had excellent outcomes (95–100), 68.75% (n = 22) had good outcomes (84–94), 28.12% (n = 9) had fair outcomes and 3.12% (n = 1) had poor outcomes. The patients who had poor outcomes on Lysholm score had even preoperative scores very less i.e.,28, actually least in the subject group. None of the patients had a graft failure or features of instability in either or both knees till the final follow-up.

Patients who could return to their work under 8 weeks were 84.4% (n = 27) and the remaining 15.6% (n = 5) patients joined between 9 and 12 weeks. We tend to go slow on allowing the patients to return to play (RTP) as it is shown in the literature that ligamentization takes at least 1 year after a successful reconstruction of ACL.¹⁶ FAST (French ACL study) concluded that objective functional recovery was generally unsatisfactory at a mean of six months after ACL reconstruction¹⁷ and added that this seemed to be risk factor recurrent tears. In our patient group, we advised them to start sport-specific training or get started in any games only by the end of 8 months progressively over 12 months, if they performed well in the analysis conducted by our physio team in tandem with the senior surgeons. 37.5% (n = 12) of the patients returned to sports at their pre-injury level within 12 months from surgery, 31.3% (n-10) between 13 and 18 months and one patient took more than a year and a half to get back to sports. 28.1% (n = 9) of the patients didn't return to sport but were otherwise able to perform most of the activities they were able to perform pre-injury.

As described, there were 7 (21.9%) patients who had a simultaneous injury to both knees causing ACL tear and 25 (78.1%) non simultaneous ones. We compared their functional outcomes (IKDC and LYsholm) after a single staged bilateral ACL reconstruction. There was no statistically significant difference in the functional outcomes among the groups.

Meniscal tears associated with bilateral ACL rupture and comparison between the ones who had meniscal tears and who did not was performed. There was no statistical difference in functional outcome. Even when the groups where repair was done vs some form of excision or debridement, there was no functional difference at the final follow up.

5 Limitations

One of the main limitations of our study is the lower numbers, which is secondary to the paucity of the injury per se. Another limitation of the series is that we have no female patients at all in the group. This may be due to the skewed sample that came for treatment in our hospital or maybe secondary to the cultural differences between the Western population and those of the Indian subcontinent. Girls' sports are only starting to increase and have not reached the level that they are in their Western counterparts. As we have seen an increase in ACL injuries in female athletes with the rise of their involvement in more demanding sports activities in the West, that trend may also be seen in our population, only time will say.

6 Conclusion

In our patient group, we found out that single-stage bilateral ACL reconstruction performed by an experienced surgeon, with a good and personalized rehabilitation protocol leads to a good functional outcome at midterm follow-up. Our outcomes are comparable to the outcomes published in the literature. Single-stage bilateral ACL reconstruction saves time (during the admission as well as rehabilitation), and decreases the financial burden on the patients and their families.

Ethical approval

This study received approval from the Institutional Human Ethics Committee, Ortho-One IHEC.

Funding statement

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

Guardian or parent consent

There were no minors in the study group at the time of conception of the study. So we did not collect any consent from Guardian or parent after the discussion with IHEC.

CRediT authorship contribution statement

Srujun Vadranapu: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing. Santosh Sahanand: Conceptualization, Data, Methodology, Validation, Supervision, Writing – review & editing. David V. Rajan: Supervision, Validation, Writing – review & editing.