Abstract
PURPOSE: To evaluate the influence of knee rotation angle (KRA) on tibial tubercle-trochlear groove (TT-TG) distance measured by computed tomography (CT) in female anterior knee pain (AKP) patients. To assess how correcting for knee rotation affects TT-TG values. To correlate rotational corrected TT-TG with the tibial tubercle-posterior cruciate ligament (TT-PCL) distance and tibial tubercle lateralisation (TTL) ratio. METHODS: A retrospective study was performed on 100 consecutive female AKP patients (183 lower limbs) who underwent torsional CT scans. TT-TG distance was measured and KRA was determined. Rotational-corrected TT-TG (RC TT-TG) values were calculated by neutralising knee rotation. Moreover, TT-PCL distance and TTL were measured. Two orthopaedic surgeons independently performed all measurements. Spearman correlation and linear regression analyses were used to evaluate the relationship between KRA and TT-TG changes. RESULTS: The mean native TT-TG was 17.22 ± 4.20 mm, mean KRA was 8.81 ± 5.08° and mean corrected TT-TG was 9.34 ± 4.70 mm. The difference between noncorrected and corrected TT-TG distance showed a very strong positive correlation with KRA (ρ = 0.934, p < 0.001). Linear regression analysis demonstrated that KRA explained 73.3% of the variability in TT-TG changes (R² = 0.733), with TT-TG decreasing by approximately 0.84 mm for each degree of knee rotation. TT-TG distance showed a moderate positive correlation with TT-PCL (ρ = 0.515, p < 0.001). In contrast, rotational-corrected (RC) TT-TG demonstrated a stronger correlation with TT-PCL (ρ = 0.644, p < 0.001). The Spearman correlations show a moderate positive association between the normal TT-TG and TTL (ρ = 0.451, p < 0.001), while the RC TT-TG exhibits a stronger correlation with TTL (ρ = 0.539, p < 0.001). CONCLUSION: Knee rotation is a significant factor affecting TT-TG measurement. Measuring TT-TG after correcting knee rotation to neutral provides a more accurate estimation of this measurement. RC TT-TG correlates more closely with rotation-independent tibial-based measurements. LEVEL OF EVIDENCE: Level IV.