Injuries to the anterior cruciate ligament (ACL) were once thought to be rare occurrences among skeletally immature patients. Tibial eminence fractures were considered the pediatric equivalent to ACL injuries and thought to occur much more frequently.¹,²,³,⁴ However, a 10% to 65% incidence of ACL tears in the setting of acute hemarthrosis has been reported in pediatric patients in recent years.⁵,⁶,⁷,⁸,⁹,¹⁰,¹¹ The increase in ACL ruptures in the growing athlete has led to a reevaluation of treatment options for the immature patient. Historically, treatment of ACL injuries has been largely nonsurgical consisting of physical therapy, activity modification, and bracing until skeletal maturity due to the fear of physeal injury. At maturity, these patients would receive a standard ACL reconstruction; however, high rates of instability and subsequent meniscal and articular cartilage injuries have been the hallmark of this approach.¹²,¹³,¹⁴,¹⁵,¹⁶,¹⁷,¹⁸,¹⁹,²⁰,²¹,²²,²³,²⁴,²⁵ Aichroth et al.²¹ conducted a prospective natural history study of 33 patients for 10 years: 10 of these patients could not tolerate nonsurgical treatment and opted for surgical intervention and 23 patients remained in the study. At the time of injury, the mean age was 12.5 years (range, 11 to 15 years), and the mean follow-up was 72 months (range, 36 to 144 months). The mean Lysholm score decreased from 78.6 (range, 54 to 93) at the time of injury to 52.4 (range, 30 to 83) at final follow-up; the mean Tegner score decreased from 6.7 (range, 4 to 9) at the time of injury to 4.2 (range, 2 to 6) at final follow-up. At the time of injury, 14 meniscal tears (8 medial, 6 lateral) and 3 osteochondral fractures were reported, all of which underwent surgical intervention. At final follow-up, an additional 7 meniscal tears were reported and 10 patients had degenerative radiographic changes.

In a more recent study, Lawrence et al.²⁵ reviewed the results of delayed versus acute treatment in 70 patients (mean age, 12.9 years; range, 10 to 14 years). Of these, 29 (41%) underwent at least 12 weeks of nonsurgical treatment and 41 underwent acute ACL reconstruction. Logistic regression analysis exhibited that time from injury to surgery greater than 12 weeks was independently associated with an increased rate of meniscal tears and chondral injuries at the time of surgery. Survivorship analysis showed that patients without meniscal tears or high-grade chondral defects (Outerbridge grades II to IV) underwent surgery at a median of 9 weeks. This implies causality of the presence of these lesions to the timing of surgery. The authors also noted that rates of irreparable meniscal tears were over three times more frequent (24% vs. 7%) among patients who were treated nonoperatively for more than 12 weeks versus those patients who underwent acute surgery. The authors also reported that 45% of patients who underwent surgery more than 12 weeks from the time of injury had Outerbridge grade II, III, or IV chondral lesions of the lateral femoral condyle versus 10% of patients in the early treatment group. Among the patients who underwent delayed surgery, 7% sustained grade IV lesions versus none in the acute surgery group. Within the last decade, other studies have reported similar findings.²²,²³,²⁴