Purpose: This study presents the 2- to 10-year results of 35 arthroscopically assisted combined anterior cruciate ligament and posterior cruciate ligament (ACL/PCL) reconstructions evaluated preoperative and postoperatively using Lysholm, Tegner, and Hospital for Special Surgery knee ligament rating scales, KT-1000 arthrometer testing, stress radiography, and physical examination. Type of Study: Case series. Methods: This study population included 26 men and 9 women with 19 acute and 16 chronic knee injuries. Ligament injuries included 19 ACL/PCL/posterolateral instabilities, 9 ACL/PCL/medial cruciate ligament (MCL) instabilities, 6 ACL/PCL/posterolateral/MCL instabilities, and 1 ACL/PCL instability. All knees had grade III preoperative ACL/PCL laxity and were assessed preoperatively and postoperatively with arthrometer testing, 3 different knee ligament rating scales, stress radiography, and physical examination. Arthroscopically assisted combined ACL/PCL reconstructions were performed using the single-incision endoscopic ACL technique and the single femoral tunnel–single bundle transtibial tunnel PCL technique. PCLs were reconstructed with allograft Achilles tendon (in 26 cases), autograft bone–patellar tendon–bone (BPTB) (in 7 cases), and autograft semitendinosus/gracilis (in 2 cases). ACLs were reconstructed with autograft BPTB (16 cases), allograft BPTB (12 cases), Achilles tendon allograft (6 cases), and autograft semitendinosus/gracilis (1 case). MCL injuries were treated with bracing or open reconstruction. Posterolateral instability was treated with biceps femoris tendon transfer, with or without primary repair, and posterolateral capsular shift procedures as indicated. Results: Postoperative physical examination revealed normal posterior drawer/tibial step-off in 16 of 35 (46%) knees. Normal Lackman and pivot-shift test results were found in 33 of 35 (94%) knees. Posterolateral stability was restored to normal in 6 of 25 (24%) knees, and tighter than normal knee results were found in 19 of 25 (76%) knees evaluated with the external rotation thigh foot angle test. In this group, 30° varus stress testing was normal in 22 of 25 (88%) knees, and grade 1 laxity was found in 3 of 25 (12%) knees. 30° valgus stress testing was normal in 7 of 7 (100%) surgically treated MCL tears, and in 7 of 8 (87.5%) brace-treated knees. Postoperative KT-1000 arthrometer testing mean side-to-side difference measurements were 2.7 mm (PCL screen), 2.6 mm (corrected posterior), and 1.0 mm (corrected anterior) measurements, a statistically significant improvement from preoperative status (P = .001). Postoperative stress radiographic side-to-side difference measurements measured at 90° of knee flexion and 32 lb posteriorly directed proximal force were 0 to 3 mm in 11 of 21 (52.3%) knees, 4 to 5 mm in 5 of 21 (23.8%), and 6 to 10 mm in 4 of 21 (19%) knees. Postoperative Lysholm, Tegner, and HSS knee ligament rating scale mean values were 91.2, 5.3, and 86.8, respectively, showing a statistically significant improvement from preoperative status (P = .001). Conclusions: Combined ACL/PCL instabilities can be successfully treated with arthroscopic reconstruction and the appropriate collateral ligament surgery. Statistically significant improvement is noted from the preoperative condition at 2- to 10-year follow-up using objective parameters of knee ligament rating scales, arthrometer testing, stress radiography, and physical examination. Postoperatively, these knees are not normal, but they are functionally stable. Continuing technical improvements will probably improve future results.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 7 (September), 2002: pp 703–714