Increased femoral anteversion is associated with inferior clinical outcomes after MPFL reconstruction and combined tibial tubercle osteotomy for the treatment of recurrent patellar instability

Abstract

Purpose This study aimed at investigating the influence of an increased femoral anteversion angle on clinical outcomes after medial patellofemoral ligament reconstruction and combined tibial tubercle osteotomy for the treatment of recurrent patellar instability. It was hypothesized that an increased femoral anteversion is associated with inferior clinical outcomes. Methods From 2014 to 2016, a total of 144 consecutive patients with recurrent patellar instability were treated with medial patellofemoral ligament reconstruction and combined tibial tubercle osteotomy. The femoral anteversion angle was measured using three‐dimensional computed tomography scans. Patients were allocated into group A (femoral anteversion < 20°), group B (femoral anteversion 20°–30°) and group C (femoral anteversion > 30°) based on the value of the femoral anteversion angle. Routine radiography and CT examinations were performed to evaluate the patellar height, trochlear dysplasia, genu valgum, and tibial tuberosity–trochlear groove (TT–TG) distance. The patellar lateral shift distance assessed with stress radiography was used pre‐ and postoperatively to quantify medial patellofemoral ligament residual laxity under anaesthesia. Patient‐reported outcomes (Kujala, IKDC, and Lysholm scores) and patellar maltracking (“J‐sign”) were evaluated pre‐ and postoperatively. Finally, subgroup analysis was performed to investigate the influence of an increased femoral anteversion angle on the clinical and radiological outcomes. Results A total of 66 patients (70 knees) were included with a median follow‐up time of 28 months (range 24–32). After a minimum of 2 years of follow‐up, all patient‐reported outcomes (Kujala, Lysholm, and IKDC scores) improved significantly, and subgroup analysis showed that group C had significantly lower Kujala scores (75 ± 8 vs. 84 ± 8, P13 = 0.003; 75 ± 8 vs. 82 ± 8, P23 = 0.030), Lysholm scores (81 ± 9 vs. 87 ± 7, P13 = 0.021) and IKDC scores (78 ± 6 vs. 85 ± 7, P13 = 0.001; 78 ± 6 vs. 84 ± 6, P23 = 0.005) than group A and group B. Twelve patients had a postoperative residual J‐sign (17.1%), and significant differences were found between group C and group A regarding the rate of residual J‐sign (32.1% vs. 4.8%, P13 = 0.003). Postoperatively, group C had a greater patellar lateral shift distance than group A (10 ± 4 vs. 6 ± 4 mm, P13 = 0.006) and group B (10 ± 4 vs. 6 ± 3 mm, P23 = 0.008). Additionally, patients with a residual J‐sign demonstrated greater medial patellofemoral ligament laxity than patients without a residual J‐sign (12 ± 4 vs. 9 ± 3 mm, P = 0.009). Conclusion Patients with an increased femoral anteversion angle (> 30°) had inferior postoperative clinical outcomes, including greater patellar laxity, a higher rate of residual J‐sign and lower patient‐reported outcomes after medial patellofemoral ligament reconstruction and combined tibial tubercle osteotomy for the treatment of recurrent patellar instability. Level of evidence III, retrospective cohort study.

Correlations between intra and extraarticular factors measured by computed tomography in patients with recurrent patellar dislocation

“…Tibial tubercle osteotomy (TTO) is a frequent surgical technique applied for correcting abnormal patellar tracking caused by a lateral force vector, described in literature as the main cause of the lateralization of the tibial tubercle and other rotational deformities [10,11]. The surgical indication for TTO has been established by a computed tomography study of Dejour et al, in 1994, at a tibial tubercle-trochlear groove (TT-TG) distance of 20 mm or more and it has been considered a standard surgery indication since then [12].…”

Preoperative Complete Patellofemoral Dislocation in Extension Predicts an Inferior Clinical Outcome After Medial Patellofemoral Ligament Reconstruction in Patients With Recurrent Patellar Dislocation

“…Few studies have described the phenomenon of the inward patella as a sequela of RPD, and little is known about its clinical significance in the literature. 4 , 8 , 27 Zhang et al 33 speculated that the procedure of MPFL-R without addressing concomitant increased femoral anteversion might iatrogenically create a squinting patella. The authors further pointed out that a postoperative inward patella might be a contributing factor to inferior clinical outcomes.…”

The alignment alteration of transverse plane in growing rabbits after patella dislocation

“…The increased femoral anteversion has been regarded as a risk factor for patellar instability, as it produces a lateralizing force on the patella. The lateralizing force exists after MPFL reconstruction, contributes to the inferior clinical outcomes, even reconstruction failure [6,32,33,34].…”