Patients with less than 1 cm of growth remaining at the knee have virtually no risk of developing a meaningful growth disturbance. These are typically boys with a bone age of 15 or 16 years and girls with a bone age of 13 or 14 years. For them, we feel a transphyseal reconstruction is always safe. The keys to understanding this group are several. Since there is so little growth risk, the family can be advised of these remote risks, but should not be unduly caused to worry. There are probably few if any special technique precautions necessary. While the physes should not be totally disregarded, all conventional ACL techniques and grafts are probably reasonable options. Specifically, grafts that include bone blocks such as patellar tendon grafts, quadriceps grafts (with an optional patellar bone block), and Achilles tendon allografts are options. These patients, with less than 1 cm of growth remaining around the knee, are followed clinically for at least 9 months and discharged once radiographs show that their physes surrounding the knee have closed. Alignment is followed clinically and long radiographs for limb alignment are not routinely obtained. The bigger issues that must be discussed with the child and family relate to the importance of proper rehabilitation and reinjury rates in adolescents.

For those patients with 1–5 cm of growth remaining, who have definite risk of developing an appreciable growth disturbance, several strategies come into play. These are typically boys with a bone age of 13 or 14 years and girls with a bone age of 11 or 12 years. For them, a thoughtfully performed “physeal-respecting” reconstruction is a viable option, and is our usual recommendation. Preoperatively, a bone age is obtained and documented. In many cases, we obtain a full-length bilateral lower extremity radiograph to document alignment. Occasionally, we identify an existing deformity, typically genu valgum. If significant, this could be a risk factor for the original ACL injury and perhaps a risk factor for subsequent graft injury. Correction with hemi-epiphyseal tethering (often referred to as guided growth) can be considered.

Tunnel sizes are based on graft size, with an average of 7.5–8.5 mm in the preadolescent population. There is mixed literature regarding optimal graft size, but if patients are approaching adult body habitus, we strive for a minimum of 8 mm. If the quadrupled autograft is too small, it can be folded an additional time (if adequate length) or supplemented with allograft. Graft fixation is performed on the femur using cortical suspensory fixation (through a femoral tunnel drilled by a flipcutter through a separate incision) and a solid biocomposite 23 mm interference screw placed distal to the physis on the tibia. Fixation placement is verified with fluoroscopy. Fixation can be supplemented with a staple, post and washer, or anchor distally as deemed necessary (Fig. 16.2).

Patients and families are advised of the risks of growth disturbance associated with this technique, but are reassured that reasonable precautions will be taken to minimize these risks and the patients will be monitored afterward to identify any growth related abnormality. If necessary, treatment can be undertaken in a timely manner to diminish the effect of the growth disturbance and minimize the need for future interventions. Postoperatively, the exam of limb lengths and alignments is documented at each visit. If we have a clinical concern for length or angular deformities, then lower extremity alignment radiographs are obtained.

For patients with more than 5 cm of growth remaining, who have a definite risk of developing a meaningful growth disturbance, we feel that additional options should be considered. This patient group typically includes boys with a bone age of 12 years or less and girls with a bone age of 10 years or less. For this youngest age group, we feel the literature has fairly little data on the risks and safety of transphyseal ACL reconstruction, so we typically recommend a physeal sparing procedure . In our hands, this is most commonly the iliotibial band reconstruction modified by Micheli [49] and published by Micheli, Kocher, and others [50, 51]. We have been very happy with the relatively good graft survival rates and no apparent growth disturbances. These knees seem to remain stable over time, and this has not been a “temporizing procedure” as some have labeled it. All epiphyseal reconstructions are growing in popularity for these very young patients as well, but it will take some time to sort out all the issues and outcomes for this relatively rare group of patients [52–54].

To minimize the risk of growth disturbance when transphyseal reconstruction is selected, tunnels should be small and central in the physis. Preference for graft selection is gracilis and semitendinosus autograft with supplemental soft tissue allograft when autograft alone is insufficient. Metaphyseal fixation should be utilized to avoid hardware at the level of the closing physis. Excessive graft tension and damage to the tibial tubercle and perichondral tissue should be avoided. A structured rehabilitation program with experienced physical therapists is important to ensure optimal outcomes. Return to unrestricted cutting and pivoting sports is routinely no sooner than 9 months and requires symmetric core, hip, and lower limb strength and proprioception. Establishing clear patient and family expectations regarding restrictions and estimated return to play is critical to successful outcomes and maximizing compliance. Patients with significant growth remaining warrant close postoperative follow-up until skeletal maturity, with both clinical and radiographic exams to identify linear and angular growth disturbances.