Abstract
Objectives:
The purpose of this study was to assess changes in limb alignment in skeletally immature patients at 1- and 2-years following transphyseal ACL reconstruction with quadriceps tendon autograft.
Methods:
A prospective single-center study was performed of all patients less than 19 years of age who underwent transphyseal or conventional ACL reconstruction with an all-soft tissue quadriceps tendon autograft from 10/1/20 – 6/30/22. Bone age was calculated for all skeletally immature patients using a left hand radiograph and the HSS Short-Hand Bone Age. A cohort of patients with 1 year of growth remaining based on bone age, and who had minimum 2-year clinical follow-up, were included in this study. Standing long-leg alignment radiographs were obtained on all patients pre-operatively, as well as annually after surgery until physes were closed and the following measurements calculated by the surgeon: anatomic lateral distal femoral angle (aLDFA), medial proximal tibial angle (MPTA), and mechanical axis deviation (MAD) in millimeters.
Results:
229 patients were enrolled in the prospective study and 34 patients (15%) had open physes and 1 year of growth remaining based on bone age. Nine patients were excluded without standing long-leg alignment radiographs: 3 missing baseline and 6 missing follow-up. The study cohort of 25 patients, 76% male, had a mean chronologic age at the time of surgery of 11.9 years for females and 14.5 years for males. Mean growth remaining was 1.8 years (range 1 – 2.5 years). Femoral transphyseal tunnels were drilled with a tibial-independent, outside-in technique. Mean femoral and tibial tunnel diameters were 8.8 (range 7.5 – 10) and 8.7 (range 7.5 – 10), respectively.
At baseline, the operative limb had neutral alignment in 18 patients (72%), zone 1 valgus in 6 patients (24%) and zone 1 varus in 1 patient. At final radiographic follow-up, limb alignment was neutral in 17 patients (68%), valgus zone 1 in 7 patients (28%), and valgus zone 2 in 1 patient. 20 patients (80%) had either no change in mechanical axis or changed from zone 1 varus or valgus to neutral. 4 patients (16%) changed from neutral to zone 1 valgus. One patient, a 12-year old female with 1 year of growth remaining at the time of ACL reconstruction with an 8.5mm graft, changed from neutral alignment at baseline to zone 2 valgus at 1-year after ACL reconstruction.
Mean aLDFA, MPTA, and MAD for the operative and non-operative limbs at baseline (25 patients), 1-year (23 patients), and 2-years (10 patients) are listed in Table 1.
Conclusions:
Transphyseal ACL reconstruction with quadriceps tendon autograft in skeletally immature patients with 1 or more years of growth remaining is a safe technique without significant changes in overall limb mechanical axis from the time of surgery to reaching skeletal maturity. There were no significant changes in aLDFA or MPTA in the operative limb.
