## 2 Materials and Methods
### Procedure  
Single bundle ACL reconstructions were performed in an anatomic, transport manner with anteromedial femoral tunnel using a quadriceps tendon-bone full thickness autograft (9 mm \(\times\) 95\(-\)100 mm) (Figure 1). The graft was harvested as described in a recent technical article [14]. Grafts were approximately 9 mm in diameter, both on the soft tissue portion and on the bone plug. They were harvested with the use of straight 8-mm-wide osteetome used as the guide. The soft tissue portion was prepared by incising quadriceps tendon with surgical knife and straight scissors up to about 8 cm proximal to the patella. The bone plug was about 20 mm long and it was harvested with use of a power saw with a 7-mm depth limiter and an osteetome. Grafts were stabilized with titanium screws in the femoral and tibial tunnels and with sutures tied over the bone bridge as additional stabilization on the tibia. For the PRP group, it was obtained from a sample of the patient's blood and processed using the Zimmer Biomet GPS\({}^{\circledR}\) Platelet Concentration System. Minimal infrapatellar fat pad was resected. Saline passage was stopped at the initiation of injecting PRP (before placing the graft in the joint) in order to avoid rinsing off the PRP. In the PRP group, it was administered to the graft harvest site, onto the intra-tunnel portions of the graft (Figure 2) and into the reconstruction tunnels (Figure 3). Tunnels were injected with PRP both before and after graft insertion (through the cannulated interference screw, Figure 3). Any remaining plasma and thrombin were administered onto the skin wounds. All cases were operated and qualified by a single surgeon. ACLR was a second stage surgery, all additional procedures (i.e., suturing the meniscus) were performed during the first stage surgeries at least 6 to 8 weeks before the ACLR. All patients underwent the same postoperative rehabilitation protocol. They spent the first 3 days after the surgery in the hospital with on-demand analgesia. A postoperative brace was set at 15 to 90 degrees of flexion and administered for use while ambulating for the first three weeks. Patients were allowed to remove the brace during activities such as sitting or lying in bed. After the third week, the brace was maintained with no ROM limitation to 12 weeks postoperatively. Crutches were obligatory for 14 days for ambulation and up to 6 weeks for outside locomotion. Patients were recommended to perform weightbearing as tolerated. Home exercises for ROM restoration started at the first postoperative day; however, patients were warned to perform them in the pain-free zone. Physical therapy with a specialist started at 7 days after surgery and was performed twice a week up to 6 months postoperatively.  
Quadriceps tendon-bone full-thickness autograft visible after harvesting and preparation. The graft was harvested as described in a recent technical article [14]. Grafts were approximately 9 mm in diameter, both on the soft tissue portion and on the bone plug. They were harvested with the use of straight 8-mm-wide osteetome used as the guide. The soft tissue portion was prepared by incising quadriceps tendon with surgical knife and straight scissors up to about 8 cm proximal to the patella. The bone plug was about 20 mm long and it was harvested with use of a power saw with a 7-mm depth limiter and an osteetome.  
Figure 1: Quadriceps tendon bone full-thickness autograft.  
Figure 2: Administration of the PRP onto the harvest site and intra-tunnel portions of the graft: (**A**) administration of the PRP onto the harvest site of the QTB full thickness autograft; (**B**) administration of the PRP onto the intra-tunnel portions of the QTB full thickness autograft. PRP, platelet-rich plasma; QTB, quadriceps tendon bone.