Technique

The technique with semi-patella tunnels was chosen because it avoids breaching the anterior cortex of the patella, utilizes blind transverse tunnels (not trans-patellar tunnels) minimizing the tunnel size, and provides aperture fixation with tendon-to-bone tunnel healing [32].

Gracilis tendon autograft was harvested through a vertical incision placed 2 cm medially to the pes anserinus. After the preparation of the gracilis tendon graft (approximately 20–21 cm), a running locking Krackow suture was placed up to approximately 2 cm from each free end with a Νo. 2 non-absorbable suture (Ethibond). With the knee flexed at 90°, a second longitudinal incision (2–3 cm) was performed on the anteromedial side of the patella and the medial aspect of the patella was exposed all the way to the bone surface by electrocautery, without penetrating the capsule. A guide pin of 2.0-mm diameter with an eyelet was transversely inserted from the midpoint of the medial edge of the patella (by palpations and lateral x-ray) to the lateral border, a) free hand (Group A) and b) with the help of an ACL tibia aiming device to avoid breaching either the articular surface or the anterior cortex (Group B). Intra-operatively, an anteroposterior x-ray is not helpful for guide wire positioning and measuring the distance between tunnels, because the patella is obscured by the distal femur. The direction guide pin was drilled in a transverse fashion, perpendicular to the longitudinal axis of the patella and parallel to the coronal patella plane. The appropriate placement of the guide pin was confirmed by fluoroscopy. Distal drilling was performed first. A second guide pin was placed at least 10 mm proximally and parallel to the first pin, as checked using a ruler and the two guide pins were over-drilled with a cannulated 4.5-mm drill bit 2-cm deep, to create two 2-cm transverse bone tunnels at the medial side of the patella. The appropriate placement of the second guide pin was also confirmed by fluoroscopy. Two suture loops were inserted into the tunnels, with the loop lying on the medial side.

The knee is then flexed to 30°, and the adductor tubercle was identified by palpation and under fluoroscopic guidance, a 2.4-mm guide pin with an eyelet is drilled at the Schöttle point. Afterwards, the guide pin was over-reamed with a 6-mm cannulated reamer to a depth of 30 mm. The prepared graft was passed through the patellar incision, so that the sutures of each free graft-end were passed through the suture-loops at the patella tunnels and then pulled out from medial to lateral. Both ends of the tendon graft were pulled into the 2 patella tunnels, and the graft sutures were tied together with tension for stable graft fixation at the lateral patella rim. The graft loop was pulled into the created femoral tunnel for 2 cm or more and was finally fixed with a 7-mm interference screw at 20–30° of knee flexion.