Anterior cruciate ligament rupture is a serious event linked to detrimental sequelae such as short-term functional deficits and long-term morbidity involving osteoarthritis and degenerative, progressive disability. In most cases, highly active patients that desire to return to pre-injury activity levels require ACL reconstruction surgery with 75-97 percent experiencing positive results with respect to knee function and stability, reduced pain, and a return to normal levels of activity. Despite this, there remain patients who experience negative outcomes such as knee pain and stiffness, restricted motion, instability, graft failure, and osteoarthritis. An increasing number of studies have focused on revision outcomes, with the vast majority reporting subjective data collected from validated questionnaires and objective data in the form of functional testing and radiographic results. It is estimated that between 2 and 6 percent of primary ACL reconstructions will fail, requiring revision surgery. Due to the relative rarity of graft failure the collection of a sufficient number of graft failures leading to revision in a prospective manner can be lengthy and costly. The Multicenter ACL Revision Study was designed to prospectively assess revision outcomes and has amassed nearly 1000 patients since 2006. The extraction of demographic and primary ACL reconstruction surgical data from this study allows for the calculation of time from primary reconstruction to revision and time from primary ACL reconstruction to graft failure. To date no published study has been designed to investigate time-to-revision or time-to-failure as a dependent outcome of interest.
The goals of this study were: 1. Describe patient and surgical characteristics of the largest collection of anterior cruciate ligament graft failures in the US, 2. Identify factors associated with occurrence of revision surgery within 30 months of primary reconstruction, and 3. Specifically investigate the association of sex and time-to-graft failure and the modifying effects of graft type and activity level.
The main finding of this research is that among patients with confirmed ACL graft failure, factors associated with greater odds of revision within 30 months of primary ACL reconstruction are: age at primary of 18 years or less, a return to a high activity level, allograft use in primary surgery, hamstring with semitendinosis plus gracilis use in primary surgery, and prior lateral meniscus surgery. Patients with a femoral tunnel position deemed too anterior or too vertical had reduced odds of revision within 30 months of primary ACL surgery when compared to a position deemed ideal. A sex difference was not observed for revision occurring within 30 months of primary surgery. However, an additional finding suggests that when time-to-graft failure, rather than revision, is taken into account a significant difference between males and females exists, with female grafts failing earlier. Activity level and prior graft type modify this difference. Future, prospective studies should investigate the temporal component of graft failure and results from this study suggest age at primary ACL surgery, activity level to which the patient wishes to return, and prior graft type, graft source, and femoral tunnel position should be considered as potential factors.