Loss of Extension Following Anterior Cruciate Ligament Reconstruction: Analysis of Incidence and Etiology Using IKDC Criteria

Purpose: The purpose of this study was to determine the incidence of and factors associated with loss of extension (LOE) 4 weeks after anterior cruciate ligament (ACL) reconstruction using the new IKDC Knee Ligament Evaluation Form criteria for loss of motion. Methods: A retrospective review of patients who had undergone arthroscopic ACL reconstruction between 1995 and 2000 was performed. An endoscopic single tunnel technique with autograft or allograft was used in all cases. A standardized physical therapy program was prescribed to all patients. Subjects with revision ACL reconstruction, concomitant ligament surgery, meniscal transplantation, or any articular cartilage surgery were excluded. LOE was defined as greater than a 5° side-to-side difference in passive knee extension 4 weeks after surgery, the need for repeat arthroscopy to restore extension, or use of a drop-out cast to restore extension. Results: Fifty-eight of 229 (25.3%) patients developed LOE 4 weeks after ACL reconstruction. LOE was not associated with age, sex, presence of nerve block, concomitant meniscal procedures, specific graft type, or tourniquet time (P > .05). LOE was significantly associated with preoperative extension, time from injury to surgery, and use of autograft (P < .05). Twenty-eight (12.2%) patients underwent an arthroscopic procedure to recover loss of motion. Following arthroscopy, 4 (1.7%) patients had passive motion deficits between 6° and 10°, with none greater than 10°. Conclusions: Preoperative range of motion and time to surgery are intimately related to a patient’s postoperative extension. While 48% of patients that lacked full extension by 4 weeks eventually required arthroscopic debridement to achieve satisfactory extension, our treatment algorithm led to an overall incidence of LOE greater than 5° at final follow-up of 1.7%. Level of Evidence: Level III, therapeutic, retrospective, comparative study.