Risk factors for early onset patellofemoral osteoarthritis following anterior cruciate ligament reconstruction with hamstring tendon autograft

Abstract

Objective: This study aimed to identify risk factors contributing to the early onset of patellofemoral osteoarthritis (PFOA) within the first two years following anterior cruciate ligament reconstruction (ACLR) using a hamstring tendon autograft.

Methods: Participants aged 18 to 40 who had undergone ACLR within the past two years were included in this study, along with a control group of healthy volunteers. Magnetic resonance imaging (MRI) data were obtained preoperatively, at two years postoperatively, and from the control group. T-tests were used to assess differences in patellofemoral alignment (PA) and trochlear morphology (TM) between the pre- and post-ACLR patients and healthy controls. The incidence of PFOA was recorded, and associations between PA, TM, and clinical parameters were evaluated in patients with and without PFOA. Logistic regression analysis was conducted to identify potential risk factors for PFOA development.

Results: A total of 177 patients, with a mean follow-up period of 22.17 ± 5.09 months and a mean age of 26.4 ± 5.6 years, were included in the study. Following ACL injury, significant alterations in patellar tilt angle (PTA), tuberositas tibae-trochlear groove distance (TT-TG), Insall-Salvati ratio (ISR), and static anterior tibial translation (SATT) were observed compared to the control group. Postoperatively, deviations in PTA and SATT remained significant when compared to healthy controls. Of the 177 patients, 68 (38.42%) developed early-onset PFOA. Factors associated with the early onset of PFOA included age at the time of surgery, the interval between injury and surgery, PTA, bisect offset (BO), sulcus angle (SA), thigh circumference, SATT, and partial meniscectomy.

Conclusion: Significant differences in PTA, TT-TG, ISR, and SATT were identified between patients who underwent ACLR and healthy controls. Postoperatively, there was no correction in PTA or SATT, which remained significantly altered. Factors such as age at the time of surgery, PTA, BO, SA, ISR, SATT, thigh circumference, partial meniscectomy, and the time interval between injury and surgery were associated with the early onset of PFOA within two years post-ACLR. These findings may aid in the prevention of PFOA by identifying individuals at higher risk for early development.

Keywords: Anterior cruciate ligament reconstruction; Anterior tibial translation; Patellar tilt angle; Patellofemoral osteoarthritis; TT-TG distance.

Fig. 1

a. Sulcus angle (SA): The angle formed by the lateral and medial edges of the trochlea indicates the steepness/shallowness of the groove. Higher values indicate a shallower groove. b. Patellar tilt angle (PTA): The angle formed by the posterior condylar line (PCL) and the width of the patella signifies the degree of lateral tilt. An increased angle suggests a greater lateral tilt. c. Lateral patellar tilt angle (LPTA): The angle formed by the PCL and the medial and lateral facet edges of the patella reflects the degree of lateral tilt. An increased angle signifies a decrease in lateral tilt. d. Bipartite trochlear groove offset: This metric represents the percentage of the widest patellar length located laterally to a line perpendicular to the PCL at the deepest part of the trochlea. A higher percentage suggests more pronounced lateral displacement. e. Tuberositas tibae-trochlear groove (TT-TG) distance: This measurement represents the distance between the lowest point of the femoral trochlear groove, measured perpendicular to the PCL, and the midpoint of the tibial attachment of the patellar tendon, also measured perpendicular to the PCL. f. Insall-Salvati ratio (ISR): This ratio compares the length of the patellar tendon to the length of the longest patella. A higher value suggests a higher position of the patella. g. static Anterior tibial translation (ATT): The distance measured between the rear edge of the tibia, aligned perpendicularly to the lateral plateau line, and the tangent point of the posterior circle with the lateral plateau line, which is also perpendicular to it

Fig. 2

a. Thinning of cartilage thickness was observed in cases of lateral trochlear cartilage injury. b. Elevated T2 values were detected at the site of cartilage injury