Quadriceps tendon autografts demonstrated significantly elevated magnetic resonance imaging signal intensity at 3 months and 6 months following anterior cruciate ligament reconstruction but were no longer different from the native ligament by 12 months, according to a recent study published in the Orthopaedic Journal of Sports Medicine.
Signal intensity (SI) of quadriceps tendon (QT) autografts was significantly elevated early following anterior cruciate ligament (ACL) reconstruction and approached native ligament values by 12 months, with the most persistent changes observed in the proximal portion of the graft.
Researchers conducted a prospective case series of 19 young amateur athletes aged 13 to 19 years (mean age, 16 years) who sustained ACL rupture and underwent primary all-inside QT autograft reconstruction performed by a single surgeon. Magnetic resonance imaging (MRI) was obtained at four prespecified time points: prior to surgery and at 3 months, 6 months, and 12 months postoperatively.
Imaging was performed using a 3.0-Tesla General Electric SIGNA Premier scanner with a T2-weighted fat-saturated fast spin-echo sequence optimized to detect graft-related signal changes. The native ACL of the contralateral knee at the presurgery visit served as the biologic reference standard. SI ratios were calculated by normalizing graft SI to the posterior cruciate ligament (PCL) at each visit to account for scan-to-scan variability. Analyses were performed at the full intra-articular graft level and following segmenting the graft into four equal regions and 24 equally spaced sections to evaluate regional maturation patterns.
At the full-graft level, repeated-measures analysis demonstrated a significant time effect, with SI ratios significantly higher than the native contralateral ligament at 3 months and 6 months. By 12 months following surgery, full-graft SI was not significantly different from native ligament values.
Consistent with this pattern, distal graft segments did not differ significantly from the native ligament, whereas distal middle, proximal middle, and proximal regions showed elevated SI at 3 months and 6 months prior to normalizing by 12 months, reflecting a proximal-to-distal gradient during early and mid-phase healing.
"The SI ratio of QT autograft was increased at both 3 months and 6 months after surgery before approaching the native contralateral ACL at 12 months, with the most pronounced differences observed within the proximal aspect of the graft," noted lead study author Daniel R. Smith, PhD, of Emory University School of Medicine in Atlanta, Georgia, and colleagues.
Several limitations were noted. The absence of histologic validation limited direct assessment of tissue-level remodeling. The small, predominately female cohort of adolescent athletes restricts generalizability to older populations, male patients, or other graft types. SI measures were sequence and scanner dependent, and manual graft segmentation may have introduced measurement variability. Clinical outcomes, including patient-reported measures and graft failure, were not assessed alongside imaging findings.
Full disclosures can be found in the published study.
