Patient population
Institutional review board was granted for this study (IRB number blinded for journal review). From January 2018 to May 2020, a total of 154 patients with ACL acute tears, within 14 days from injury, were admitted to our institution. Patients were carefully informed pre-operatively about possible surgical procedures depending on the type of lesion and tissue quality of the remnant found intraoperatively. Acute proximal type I and II with good or fair tissue quality, according to the modified Sherman classification by van der List et al. [19], were repaired. Based on these criteria, a total of 49 ACL repair were performed in the study period.
A total of 15 adult patients, who underwent ACL repair, agreed voluntarily to participate in the study. The purpose of second look in-office needle arthroscopy was explained to all patients prior and informed written consent was subsequently obtained.
In-office arthroscopy technique
A sterile field with the disposable kit was prepared. The kit includes a 20-cc syringe of 1% lidocaine with epinephrine/0.75 ropivacaine, a separate 20-cc syringe with only 0.75% ropivacaine, a saline-filled 60-cc syringe, Chlorhexidine scrub, the needle arthroscopy (NanoScope™ Console, Arthrex, Naples, FL). Patients were placed in the supine position with the knee free to move from full extension to flexion. The leg was draped in a sterile fashion and a stockinette was placed over the foot and ankle and secured in place just distal to the tibial tuberosity with Coban wrap. The standard anteromedial and anterolateral portals were marked 1 cm medial and lateral to patellar tendon. Other working portals were marked medial to the standard medial portal and lateral to the lateral portal. The portals were made by inserting percutaneously the Nanoscope sharp obturator without blade. The 20-mL syringe with a 25- gauge needle was used to infiltrate 10 mL of the mixed local anaesthetic to each portal site and the surrounding capsule to anesthetize the area. Subsequently, an intra-articular injection of 20 cc of 0.75% ropivacaine was performed. The needle arthroscope was connected to the viewing tablet in sterile fashion, and a 60-mL syringe of sterile saline was attached to the inflow port of the needle arthroscopy hand piece (NanoScope™ Handpiece, Arthrex, Naples, FL). The anteromedial portal was used to insert the arthroscopy needle. The arthroscope has a 0° viewing angle and 120° field of view. Saline solution can be injected to the joint with the 60-mL syringe to distend the joint space and remove obstructing tissue blocking the arthroscope. After the insertion of the camera, a standard diagnostic arthroscopy was performed. A NanoProbe (NanoScope™ Probe, Arthrex, Naples, FL) was inserted from one of the accessory portals to evaluate the tension of the repaired ACL. At the end of each procedure an aspiration of the saline solution injected during the procedure was performed before the removal of the device to minimize the patient’s post-operative discomfort. The needle arthroscope was then removed, and the portals were covered with band-aids.
After the in-office arthroscopy procedure, patients were kept for observation for one hour. No patients reported complications and all patients immediately returned to daily activities.
Patient assessment
The second look in-office needle arthroscopy was performed at an average follow-up of 7.2 months after ACL repair before allowing patients to return to sports. Moreover, all patients were also evaluated at a mean follow-up of 6 months with 1.5 T MRI and KT-1000 arthrometric measurement (MedDmetric, San Diego, CA) as expected by our standard post-operative protocol. Clinical assessment with patients reported outcomes scores was performed at the final 2-year follow-up using the Tegner Lysholm Knee Scoring Scale (TLKSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) subjective and objective scores for greater validity. An experienced musculoskeletal radiologist was asked to describe the MRI images and T2- Turbo spin echo (TSE) sequences were considered and ACL maturity was measured with a four-grade system according to Howell et al. [11]: I, homogeneous, low-intensity signal indistinguishable from the PCL and patellar tendon; II, normal ligament signal over at least 50% of its volume, intermingled with portions that have increased signal intensity; III, increased signal intensity over at least 50% of its volume, intermingled with portions that have a normal ligament signal; or IV, diffuse increase in signal intensity without strands with a normal ligament appearance [3] (Fig. 1 A, B).
In-office needle arthroscopic assessment
The in-office needle arthroscopic second look focused on the evaluation of the continuity and anatomic footprint (healing) of the repaired ACL, subjective assessment of the ACL tension with the probe and evaluation of the synovial coverage. The healing of repaired ACL was graded by the examiner in four subjective types. Type A is a normal adhesion to the femoral footprint with excellent anatomical continuity (Fig. 1B); type B is a nearly normal adhesion to the femoral footprint with good anatomical continuity; type C is a moderate adhesion to the femoral footprint and fair anatomical continuity and D is abnormal adhesion to the femoral footprint with poor anatomical continuity. Tension has also been classified into four subjective types: normal tension (A), slight laxity (B), fair laxity (C) and poor laxity (D). Synovial coverage of the repaired ligament was classified into 3 categories: good, when the synovium entirely covered the repaired ligament (Fig. 2); fair, when the area of synovial coverage was more than 50% of the entire area (Fig. 3); poor, when more than 50% of the repaired ligament was without synovial coverage. A comparison between the appearance of the repaired ACL with second look was performed in relation to the MRI appearance of the ACL (signal intensity of the repaired ACL based on the Howell scale), the subjective tension based on ligament probing and arthrometric evaluation with KT-1000.
Statistical analysis
All analyses were performed with SPSS for MacOS (v 27.0.1.0; IBM). Descriptive data analysis was conducted depending on the nature of the considered criteria. The mean, range, frequencies and proportions of demographic data and clinical outcomes were calculated. The correlation between the characteristics of ACL appearance at the time of the second look arthroscopy was investigated with the Kendall tau rank correlation coefficient.