gms | German Medical Science

Objectives: Trochleoplasty (TP) is an effective tool for surgical patella realignment in severe cases of patella instability and maltracking. Despite the vitality of the chondral flap has been shown in histological studies, there is an ongoing debate about postoperative progression of cartilage deterioration in the mid- and long-term. The purpose of this study was to examine the clinical results after TP and to evaluate the integrity of patellofemoral cartilage in the mid-term, as well as its influence on the functional outcome.

Methods: All TP performed due to severe TD (types B-D acc. Dejour) between 2015 and 2021 were included. Exclusion criteria were simultaneous chondral repair, missing Magnetic Resonance Images (MRI) or refusal to participate. Functional outcomes were assessed with a minimum follow-up of 1 year, using standardized scoring systems (Kujala, Lysholm, Tegner, Knee Injury and Osteoarthritis Outcome Score [KOOS] and BANFF Patellofemoral Instability Instrument [BPII] 2.0). Pre- and postoperative MRI were analyzed to quantify patellofemoral cartilage integrity, using the AMADEUS grading. A subgroup analysis was performed to allow for a sequential analysis of PF cartilage integrity after a minimum of 6 months, followed by a correlation analysis to investigate the influences of pre- and postoperative cartilage deterioration on the functional outcome.

Results and conclusion: 113 TP (27 males, 86 females, mean age 25.8 ± 8 years) were included in the study (5 types B, 57 types C, 57 types D, mean lateral inclination angle -2.9 ± 9°). TP was combined with a lateral retinacular lengthening and MPFL reconstruction in all cases, as well as staged extraarticular correction (n=5). 75 patients (66%) reported previous surgeries other than diagnostic arthroscopy. 44 cases (39%) demonstrated osteochondral flake fractures. 95 patients (85%) demonstrated severe intraoperative cartilage deterioration (77 III.°, 18 IV.° acc. ICRS). After 35 ± 20 (12 – 97) months, a significant decrease in pain (VAS 6.0 to 1.9, p < 0.001) and an increase of all PROMs (Kujala 49.5 to 80.6, Lysholm 46.2 to 83.0, Tegner 3.8 to 4.7, p < 0.001) was found. The KOOS was 79.9 ± 13.5 (symptoms), 86.4 ± 12.1 (pain), 92.1 ± 8.3 (activity), 71.7 ± 22.2 (sports),58.1 ± 23.8 (QoL) and the BPII 64.3 ± 21.4. Postoperatively, the AMADEUS score had not changed (2.5 to 2.5), however, after 22 ± 18 months, it had improved significantly to 2.3 (p=0.001). There were strong correlations between intraoperative ICRS grading and preoperative AMDEUS score. An improvement of AMADEUS correlated with higher postoperative PROMs. Complications were hematoma (n=1), re- or subdislocation (n=2), superficial wound infection (n=3) and arthrofibrosis (n=5). Overall patient satisfaction was 93%.

In conclusion, sulcus deepening TP yields good to excellent clinical results in the mid-term FU. Despite a high percentage of preexisting cartilage lesions, TP does not seem to promote progression of cartilage deterioration.