Abstract
Background:
Notch morphology has been implicated as a risk factor for anterior cruciate ligament (ACL) tears [1]. However, pediatric studies of these anatomic differences are limited. Therefore, we compared notch morphology between skeletally immature healthy cadaveric knees and age matched patients with ACL tears who had undergone subsequent ACL reconstruction (ACLR).
Hypothesis:
Pediatric patients undergoing an ACLR will have significantly different notch morphology and notch space compared to age matched healthy cadaveric knees with an intact ACL.
Methods:
Arthroscopic images from both fresh-frozen pediatric cadaveric knee specimens and patients who underwent ACLR from a quality improvement registry from 2018-2025 were retrospectively evaluated. We utilized a descriptive classification for notch morphologies, which were described as one of the following: 1) Inverted U 2) St. Louis arch 3) Sailboat/Shark fin 4) A frame 5) Omega (Figure 1). Each notch space was also categorized as wide or narrow. Available cadaveric specimens were age matched to patients undergoing ACLR, resulting in an included age range of 8 to 11 years. Descriptive statistics were used to categorize samples, and subsequent analysis followed using chi-square and Fisher’s exact tests to compare cadaveric specimens and ACLR patients.
Results:
In total, 25 cadaveric specimens (mean age 9.5, 60% male) and 67 ACLR patients (mean age 10.2, 82.9% male) were analyzed. Cadaveric specimens (intact ACL) demonstrated a primary notch morphology of Inverted U and Sailboat/Shark fin with 9 (36.0%) each. ACLR patients primarily had Sailboat/Shark fin morphology (34.3%) and had similar rates of A frame (26.9%) and Inverted U (23.9%) morphologies. The cadaveric knees and ACLR groups did not demonstrate differences in notch morphologies (p=0.803). There also were no differences noted on subgroup analysis between males (p=0.910) or females (p=0.291) (Table 1). However, narrow notch space was only seen in 12 (48%) cadaveric knees, whereas 52 (77.6%) ACLR patients had a narrow notch space (p=0.006). Additionally, 12 (100%) female ACLR patients had a narrow notch space compared to only 6 (60%) female cadaveric specimens (p=0.029), and 40 (72.7%) male ACLR patients had a narrow notch space compared to only 6 (60%) cadaveric specimens (p=0.018) (Table 2).
Conclusion:
A narrow notch space was observed at a significantly higher rate in patients who tore their ACL in both males and females. Further, this difference was noticeably higher in female patients where 100.0% of patients displayed a narrow notch space. We did not identify differences in descriptive notch morphology between ACLR patients and cadaveric specimens.
