Abstract
Background:
Arthrofibrosis (AF) is a common and, at times debilitating, complication following anterior cruciate ligament reconstruction (ACLR), which may necessitate unexpected additional procedures, including arthroscopic lysis of adhesions (LoA) and manipulation under anesthesia (MUA). Its reported incidence varies widely (2-35%), with published risk factors including early ACLR following injury, female sex, younger age, specific autograft type, such as patellar or quadriceps tendon, and concurrent meniscal repair. Additionally, a narrower femoral notch width index (NWI), which has been associated with increased ACL rupture risk and a smaller native ACL, may play a role in AF risk.
Despite a recent trend towards individualized ACLR that considers both native ACL graft size and notch width to optimize knee biomechanics, no studies have specifically examined the impact of ACL graft size, relative to the patient's native notch width, on patient outcomes and AF risk, particularly in younger ACLR populations who are at greater risk for post-operative complications.
Hypothesis:
The study hypothesis is that a higher ACL graft: patient notch index (GNI) ratio will be an independent risk factor for developing AF in adolescent.
Methods:
This study was an IRB-approved retrospective review of records of patients aged 10 to 18 years-old with pre-operative MRI who underwent primary ACL reconstruction between 1/1/10-12/31/24, and >1 year of clinical follow-up. Measurements were taken from coronal MRI sequences using established methods. AF was defined as decreased range of motion compared to the contralateral side with a loss of extension >10 degrees and/or flexion <120 degrees. AF patients were then stratum matched with control subjects without AF.
Results:
Out of 2,346 patients screened, 127 AF patients were identified and stratum-matched with 128 control patients for a final cohort of 255. Within the AF cohort, 31patients (24%) underwent LoA/MUA. When evaluating the association with LoA, both NWI (p=0.042) and GNI (p=0.019) showed a statistically significant association, with smaller NWI predicting AF undergoing LoA. In our study, graft type and patient age were not significantly associated with LoA.
Conclusion:
In the current series of over 2000 adolescent ACLR patients, larger ACL graft diameter relative to notch width significantly increased AF risk. Future research investigating whether individualized graft selection to address this risk factor would effectively lower AF risk, and a correlation with graft rupture risk and functional outcomes, is warranted for this high-risk younger population of athletes.