Assessment of lower limb rotational profile and its correlation with the tibial tuberosity-trochlea groove distance: A radiological study

Abstract

Objective: The purpose of our study was to determine whether there is a correlation between the lower limb rotational profile and tibial tuberosity-trochlea groove (TT-TG) distance. Design and patients: The computed tomography cross-sectional imaging on 50 patients’ lower limbs (100 limbs) was investigated at our institution. The TT-TG distance was measured along with rotational measurements including femoral version (FV), tibial torsion and knee joint rotation angle (KJRA). Patients were divided into two groups. Group 1 had a TT-TG ≥ 20 mm which was considered pathological and group 2 with a non-pathological TT-TG (≤19 mm). Rotational angles were compared between groups. Statistical analysis was performed using the t-test and Mann–Whitney U analysis. Results and conclusions: Our results demonstrated a statistically significant difference in the mean KJRA ( p = 0.026) between the pathological (mean = 10.6, standard deviation (SD) = 7.79°) and the non-pathological TT-TG groups (mean = 6.99, SD = 5.06°). A higher mean value for FV and tibial torsion was also demonstrated in patients with a pathological TT-TG (18.2 vs. 13.7, 32.8 vs. 30.9, p > 0.05, respectively). In conclusion, there was a statistically significant higher mean value for the KJRA in patients with a pathological TT-TG. Hence, a lateralized tibial tubercle as demonstrated by an increase in the TT-TG distance may be associated with a coexisting lower limb rotational malalignment.

Sex differences in linear bone measurements occur following puberty but do not influence femoral or tibial torsion

“…Anteversion angle: angle between the neck axis of the femur (measured between a sphere t to the femoral head and the centre of a cylinder tted to the femoral neck), and the posterior condylar axis (measured between the medial and lateral posterior femoral condyle) (Fig. 1) [12], [24]- [32].…”

Patellofemoral Instability Part I: Evaluation and Nonsurgical Treatment

“…The TT-TG distance is measured by drawing a line along the coronal plane between the deepest point of the trochlear groove and the most prominent point on the proximal tibial tubercle, paralleling the posterior femoral condylar line (Figure 8). 25,26…”

“…A TT-TG distance more than 20 mm is generally considered abnormal and is thought to be indicative of lateralized insertion of the patellar tendon into the tibial tubercle (Level IV evidence), with over 90% association with PFI. 2,25,26 An increased TT-TG distance can be caused by increased femoral anteversion, which internally rotates and medializes the trochlear groove; increased external tibial torsion, which externally rotates and lateralizes the tibial tubercle; valgus malalignment of the lower limb, which lateralizes the path of patellar tracking relative to the trochlear groove; or combinations of these. 25…”

“…3 A larger than normal Q-angle indicates a laterally directed vector of the force applied to the patella. 3,26 In cases of valgus malalignment, when the mechanical axis of the entire limb is deviated laterally to the center of the knee, the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) can help identify the origin of the deformity (Figure 6). The mechanical (m) LDFA is denoted by the angle between the mechanical axis of the femur and a line drawn across the articular surface of the distal femur.…”

“…The TT-TG distance is measured by drawing a line along the coronal plane between the deepest point of the trochlear groove and the most prominent point on the proximal tibial tubercle, paralleling the posterior femoral condylar line (Figure 8). 25,26 Controversy exists for the method for measuring femoral torsion on CT. 33 This is mainly because of the difficulty in determining the true femoral neck axis, in which slice selection can influence the measured values. 33 Nevertheless, femoral torsion is measured as the angle between the femoral neck axis (a line parallel to the femoral neck and the center of the femoral head) and the posterior bicondylar axis (Figure 9).…”