To retrospectively analyze the application of Sch?ttle method—a X-ray assisted method in the reconstruction of medial patellofemoral ligament (MPFL) in recurrent patellar dislocation, summarize and observe the clinical efficacy, and explore the positioning method of anatomical terminus of equal-length femoral reconstruction of MPFL.

From October 2015 to December 2017, Sch?ttle method was used to identify 19 femoral lateral fixation points, three males and 16 females, with an average age of (18.1±0.5)years (15~20 years old). Inclusion criteria: (1) history of knee joint trauma, and recurrent patellar extraversion dislocation history; (2) X-ray and CT measurements determine that the femoral trochlear classification belongs to Dejour B and D; (3) patella extrapolation test and patella pushout fear test are positive; (4)tibial nodules are excessively external. Exclusion criteria: (1) habitual patella dislocation; (2) epiphyseal is not completely closed; (3) local knee infection lesions; (4) high expectations for surgery; (5) external bone malformation of the knee joint. All the patients accepted anteroposterior and patellar axial X ray examinations with knee joint flexing to 30 °, and CT scan for tibial tubercle-trochlear groove distance preoperatively. In all the cases, intraoperative tibial nodules internal transposition was performed. The anchor was sutured with 4.5 mm diameter metal band wire as the lateral fixation of patella, allogeneic tendon was selected for ligament reconstruction, and the lateral femoral medullary tract was determined by Sch?ttle method. Functional evaluation was performed on the appropriate patellofemoral angle, lateral patellofemoral angle, and Lysholm score of knee joint function before the operation and at the end of the follow-up.Statistical analysis was performed with paired t test.

All 19 patients were followed up for (20.1±1.3) months on average. Postoperative fear test was negative and no patella redislocation occurred during the follow-up. The Lysholm score of knee joint function were statistically significant improved compared to the preoperative ones (t=3.328, P<0.05). Patellofemoral fitness angle and lateral patellofemoral angle, which were measured by CT scan, were also significantly improved(t=12.572, 8.334, both P<0.05). The postoperative range of motion of the joint was improved but without statistically significant difference compared to that before the operation (t=1.764, P>0.05).

Sch?ttle′s method can accurately locate the lateral midpoint of MPFL femur, reconstruct MPFL, and reconstruct patellofemoral joint stability with the operation method of tibial nodule internal displacement.