Clinical results after anterior cruciate ligament (ACL) reconstruction are considered successful as anterior stability is restored. However, even though anterior stability was successfully restored in the majority of patients, anterolateral rotatory instability (ALRI) remains after reconstruction in some patients. This may cause limitations in regular daily activities and in the ability of athletes to participate in sports.
Dynamic ALRI in ACL-injured knees is commonly evaluated by the pivot test. A residual pivot shift has also been shown to be correlated with the development of osteoarthritis.
Therefore, controlling ALRI is one of the most critical keys to improving outcomes after ACL reconstruction.
To investigate the risk factors for residual pivot shift test after anterior cruciate ligament (ACL) reconstruction based on a multicenter prospective cohort study.
368 patients were included.
- Inclusion criteria: patients from Multicenter Arthroscopic Knee Surgery Study (MAKS) who underwent primary ACL reconstruction using hamstring tendon graft between 2013 and 2016.
- Exclusion criteria: injuries or surgeries in the contralateral knee, prior ligamentous injuries in the involved knee, grade 2 or 3 concomitant ligament injuries, and inflammatory or other forms of osteoarthritis.
Forty-eight (13%) of 368 patients were classified as having a positive RPS (RPS+), whereas 320 patients were classified as having a negative RPS (RPS−) at 1 year after ACL reconstruction.
The most important finding of the current study was that knee hyperextension and preoperative greater pivot shift were risk factors for residual pivot shift 1 year after ACL reconstruction.
The role that knee hyperextension plays in the outcome of ACL reconstruction has been evaluated in several studies. Hyperextension causes notch roof impingement in all knees at a certain degree of extension. Kim et al. reported that hyperextension of the knee most strongly predicted postoperative knee instability and function among the clinical indices of joint laxity.
The results indicated that knee hyperextension and greater preoperative pivot shift under anesthesia were risk factors for residual pivot shift at 1 year after ACL reconstruction.
The clinical relevance of this study is that risk factors for residual pivot shift could be identified by preoperative findings of the pivot shift test and knee extension angle, and in cases with higher risk of residual pivot shift, i.e., preoperative high-grade pivot shift and knee hyperextension, additional ALS augmentation might be considered in order to eliminate pivot shift and eventually obtain better outcomes after ACL reconstruction.