Effect of different femoral tunnel locations on patellofemoral joint during single-bundle anterior cruciate ligament reconstruction / 中国组织工程研究

ABSTRACT

BACKGROUND: Studies have shown that arthroscopic single-bundle anterior cruciate ligament reconstruction can restore the forward stability of the knee joint, but the rotational stability of the knee joint and the matching degree with the patellofemoral joint are affected by the central position of the femoral and tibial tunnels. OBJECTIVE: To investigate the relationship between the location of different femoral tunnel centers and patellofemoral articulation and cartilage conditions in young and middle-aged patients with anterior cruciate ligament reconstruction, and to carry out the correlation analysis of patient study factors to further explore the location of the femoral tunnel with the least influence on the patellofemoral joint. METHODS: Seventy patients with anterior cruciate ligament rupture were diagnosed by preoperative MRI, physical examination and intraoperative arthroscopy. All patients were divided into quasi-isometric group and quasi-anatomical group according to the parity of random numbers. In the quasi-isometric group, a Kirschner needle was inserted 7 mm distal to the apex of the lateral wall of the intervertebral fossa using a femoral locator. In the quasi-anatomical group, the Kirschner needle was inserted at the lateral wall of the intercondylar fossa and at the foot print center of the original anterior cruciate ligament. The central coordinates of the femoral tunnel were evaluated on the near-far-front-rear plane based on a standardized grid system, while the central coordinates of the tibial tunnel was evaluated on the anterior-posterior-inner-outer plane, labeled as quadrant Y% and quadrant X%. By comparing the baseline data of patients in the two groups, the difference of lateral patellofemoral angle (LPFA), the difference of cartilage quantitative T2 value, and the correlation between various research factors, the surgical operators were further guided to carry out clinical practice. The implementation of the study protocol complied with the relevant ethical requirements of the First Affiliated Hospital of Anhui Medical University, and all patients signed an informed consent form prior to the participation in the trial. RESULTS AND CONCLUSION: There was no significant difference in baseline data between the two groups, but a significant difference in LPFA existed between the two groups, (0.57±0.33)° in the quasi-anatomical group vs. (1.55±0.36)° in the quasi-isometric group (P<0.001). The T2 values of medial patella, lateral patella and trochlear cartilage in the quasi-anatomical group were all smaller than the corresponding values of the quasi-isometric group. Quadrant X% had a significant negative correlation with LPFA difference (R=-0.664, P<0.01). Quadrant Y% was positively correlated with LPFA difference (R=0.804, P<0.01). The difference of LPFA was significantly positively correlated with T2 values of trochlear and patellar outer cartilage (R=0.651, 0.655, P<0.01). T2 values of trochlea and lateral patella cartilage were negatively correlated with postoperative Lysholm score (R=-0.505, -0.529, P<0.01). Quadrant Y% was highly correlated with T2 value of lateral patella (R=0.825, P<0.01), and significantly correlated with T2 value of trochlear cartilage (R=0.798, P<0.01). Quadrant X% was negatively correlated with T2 values of lateral patella and pulley cartilage (R=-0.639, -0.657, P<0.01). By exploring the change of the patellofemoral joint at early stage after single-bundle anterior cruciate ligament reconstruction, we found that the quasi-anatomical reconstruction relative to the quasi-isometric reconstruction requires less patellofemoral articular cartilage degeneration and smaller patellar tilt angle. Therefore, the surgeon is required to local the center point of the femoral tunnel as far as possible at the quasi-anatomical position, thereby minimizing the degeneration of the patellofemoral joint.