Article Review:

Factors Influencing Return to Play and Second Anterior Cruciate Ligament Injury Rates in Level 1 Athletes After Primary Anterior Cruciate Ligament Reconstruction

2-Year Follow-up on 1432 Reconstructions at a Single Center

King et al, 2020


Despite the importance of return-to-play (RTP) rates, second anterior cruciate ligament (ACL) injury rates, and patient-reported outcomes of athletes returning to sports after ACL reconstruction (ACLR), these outcomes have not been evaluated together across a single cohort nor the pre- and intraoperative factors influencing outcomes explored.


To prospectively report outcomes after ACLR relating to RTP, second ACL injury, and International Knee Document Committee (IKDC) scores in a large cohort of athletes at a single center to examine the influence of pre- and intraoperative variables on these outcomes.

Methods: A consecutive cohort of 1432 athletes undergoing primary ACLR by 2 orthopaedic surgeons was followed up prospectively more than 2 years after surgery. Pre- and intraoperative findings were reported with outcomes at follow-up relating to RTP, second ACL injury, and IKDC. Between-group differences for each outcome were reported and the predictive ability of pre- and intraoperative variables relating to each outcome assessed with logistic regression.


The results demonstrated a lower reinjury rate for Bone Patella Tendon Bone (BPTB) graft and a high level of RTP for those returning to level 1 sports (sports involving landing, pivoting, and hard cutting) at follow-up, with a higher percentage of those returning to level 1 sports achieving IKDC. In addition, RTP 6 months after surgery did not influence a second ACL injury.

Return to Play:

Differences between those who had and had not returned to level 1 sports at follow-up included age (greater RTP rate with weak correlation to younger age). In addition, there were lower RTP rates in those with medial or lateral meniscal injury or grade 3-4 medial femoral chondral injuries present at the time of surgery. The influence of meniscal and chondral injury on RTP rates after primary ACLR has not been reported in the literature and may warrant further exploration. Its effect on RTP after revision ACLR has been investigated, with no influence of meniscal injury but with a negative effect of chondral injury on RTP rates.The main reasons cited in the literature for non-RTP after ACLR are fear of reinjury, ongoing knee symptoms, and social factors. This is supported in this study, with lower IKDC scores (patient-reported outcome relating to knee function) and ACL-RSI scores (patient-reported readiness to RTP) in those who had not returned to play.

Second ACL Injury:

An overall reinjury rate of 2.7%, with a rate of 1.3% for BPTB and 8.3% for HT (Hamstring Tendon) is reported. The reinjury rate was 1.9% for BPTB and 11.9% for HT. There was a clear difference in rerupture rate between HT and BPTB grafts, with a significant difference in graft survival. BPTB had an 84% lower risk of injury every month and was almost 7 times less likely to rerupture at 2-year follow-up. There is differing evidence on the influence of graft selection in reinjury in the literature suggesting lower rerupture rates for BPTB grafts were reported. However, some other reviews reported no difference in rerupture rates in graft selection, albeit at longer follow-up. Additional differences between those who had an ipsilateral injury and those who did not in this study related to age, with younger athletes having higher ipsilateral injury rates, although the correlation was weak. Younger athletes have been widely reported to be at higher risk of reinjury in the previous literature,principally through higher levels of RTP in high risk sports, as seen in our data relating to RTP in level 1 sports. The predictive ability of pre- and intraoperative data to identify ipsilateral ACL injury was fair, with hamstring graft selection the dominant factor. The accuracy was not superior to suggesting by default that no athlete would experience reinjury; however, the low numbers relating to reinjury make more accurate prediction difficult. The influence of graft type may be a point for consideration during the clinical decision making of those treating level 1 athletes who want to RTP. The study also reported a higher overall contralateral injury rate than ipsilateral injury rate (6.6% vs 2.7% overall) and significant differences in survival. The contralateral ACL injury rate in those returning to level 1 sports was 9%, with the only difference between those who went on to contralateral injury and those who did not relating to age (weak correlation with higher injury rate in younger athletes), which is in agreement with the previous literature. As there were few differences in pre- and intraoperative data, there was a low ability to predict who would experience a contralateral injury, with a lower-than-baseline accuracy (63% vs 96%).


only 2 surgeons who specialize in knee surgery carried out the large number of reconstructions, and this may reduce the generalizability of the results and the comparison with registries with larger numbers of contributing surgeons. There was a very high follow-up rate (95%) after 2 years, but there was a large spread in time to follow-up (24-55 months). This may have influenced the results, with potentially lower rates of both second ACL injury and RTP, less recall bias, and fewer differences in IKDC scores if follow-up had been completed over a shorter period around the 2- year mark. There was a larger number (80%) of BPTB grafts than HT grafts (20%), creating the potential for performance bias in favor of the more commonly used graft. However, the 2 surgeons carried out 290 HT grafts reconstructions over the 20-month period between them, which would be more than what most single-graft surgeons would complete in the same period and well in excess of the recommended 35 per year required to minimize the risk of future surgery on the same knee.

Full article:

The American Journal of Sports Medicine 1–13

DOI: 10.1177/0363546519900170

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