Thin flap sulcus-deepening trochleoplasty in patellar instability yields good functional outcomes without progressive cartilage deterioration in the short-term follow-up-A retrospective single-surgeon cohort study.

Purpose: Sulcus-deepening trochleoplasty (TP) effectively treats patellofemoral (PF) instability (PFI) caused by high-grade trochlear dysplasia (TD), but current evidence is based on small case series. We hypothesised, that TP would result in significant functional improvements and a low re-dislocation rate but would not accelerate the progression of PF cartilage deterioration.

Methods: We retrospectively reviewed all TP cases performed by a single surgeon between 2015 and 2021. Inclusion criteria were postoperative Magnetic resonance imaging (MRI) >6 and >12 months and a clinical follow-up >12 months. Patients with simultaneous cartilage repair, open physes or incomplete records were excluded. Clinical outcomes were assessed using pre- and postoperative scores, postoperative Banff Patellofemoral Instability Instrument (BPII) 2.0 and Knee Injury and Osteoarthritis Outcome Score (KOOS), re-dislocation rate and patient satisfaction. PF cartilage was evaluated via Area Measurement and Depth & Underlying Structures (AMADEUS) scores preoperatively, at 6 months and at the final follow-up.

Results: We included 113 patients (25.8 ± 8.3 years) with high-grade TD (Dejour B-D; mean lateral inclination angle: -2.9 ± 9.1°), 85% of whom had advanced cartilage lesions. All underwent TP, lateral retinacular lengthening (LRL) and medial patellofemoral ligament reconstruction (MPFL-R). After 34.8 ± 20.9 months, function, pain levels and Tegner scores improved significantly (p < 0.001). KOOS dimensions were: symptoms 79.9 ± 13.5, pain 86.4 ± 12.1, activity 91.9 ± 8.3, sports 71.7 ± 22.2 and quality-of-life 58.1 ± 23.8. BPII 2.0 was 64.3 ± 31.4. Preoperative AMADEUS scores (55.2 ± 17.4) remained stable at 6 months (p = 0.343) but improved to 58.4 ± 16.0 at 28.6 (12-89) months (p = 0.004). Complication and re-dislocation rates were 5.3% and 1.8%, with 93% patient satisfaction.

Conclusion: Sulcus-deepening TP with MPFL-R and LRL yields good to excellent short-term results without progressive chondral deterioration, enabling patients to return to their prior or higher activity levels despite advanced preoperative chondral lesions. TP can be considered a safe, joint-preserving technique for PF stabilisation.

Level of evidence: Level III, retrospective cohort study.