Outcomes of a Combined Procedure of Tibial Tubercle Proximalization, MPFL Reconstruction and Extensive Lateral Release for Revision Treatment of Habitual Patellar Dislocation in Flexion in Skeletally Mature Patients.

Background: Habitual patellar dislocation in flexion (HPD-F) is a rare condition in skeletally mature patients. Current literature reports that tibial tubercle proximalization has achieved favorable clinical outcomes for such patients. However, there are no studies to date reporting the clinical outcomes of revision surgery for skeletally mature HPD-F patients after failure of the initial procedure. Purpose: To evaluate the clinical and radiological outcomes of combined extensive lateral release, tibial tubercle proximalization, and medial patellofemoral ligament (MPFL) reconstruction for the revision treatment of HPD-F in skeletally mature patients who have failed initial surgery. Study Design: Case series; Level of evidence, 4. Methods: This retrospective study included 28 skeletally mature patients with habitual patellar dislocation in flexion who underwent revision surgery. The cohort had a mean age of 25.3 years and were followed up for a mean of 3.1 ± 1.3 years. All patients underwent the combined procedure. Preoperative and postoperative evaluations included patient-reported outcome measures (Kujala, Tegner, and Lysholm scores), radiological assessments, and isokinetic knee extension strength testing. Further analysis assessed the influence of postoperative iatrogenic patella alta on outcomes. Results: None of the patients experienced subsequent episodes of instability. The mean outcome scores were as follows: Kujala, 84; Tegner, 4; and Lysholm, 81. Following tibial tubercle proximalization by a mean of 17 mm, the mean Caton-Deschamps index increased from 0.7 ± 0.3 preoperatively to 1.2 ± 0.4 postoperatively. The mean isokinetic peak torque of the quadriceps muscles significantly improved from 31 N·m to 59 N·m after surgery, and no patient exhibited "extensor lag" postoperatively. Further analysis showed no significant differences in quadriceps strength or patient-reported outcomes between the patella alta group (n = 9) and normal group (n = 19). Conclusion: Combined extensive lateral release, tibial tubercle proximalization, and MPFL reconstruction demonstrated favorable short-term clinical outcomes with a low complication rate in skeletally mature patients with HPD-F who had failed previous surgery. In this case series, tibial tubercle proximalization led to postoperative patella alta in approximately one-third of patients; however, this did not appear to affect short-term functional outcomes or quadriceps strength.