Influence of Sulcus-Deepening Trochleoplasty on Patellofemoral Cartilage Integrity in Patients With Severe Trochlear Dysplasia at Short-term to Midterm Follow-up: A Case-Control Study.

Background: Sulcus-deepening trochleoplasty is a well-established treatment option for patients presenting with severe trochlear dysplasia and patellar instability. However, concerns remain regarding its influence on cartilage integrity in the patellofemoral (PF) joint.

Purpose: To assess the midterm effect of trochleoplasty on PF cartilage integrity in patients with severe trochlear dysplasia treated for patellar instability.

Study design: Cohort study; Level of evidence, 3.

Methods: A total of 75 patients with high-grade trochlear dysplasia (Dejour types B and C) who underwent patellar stabilizing surgery for patellar instability at a single institution were included. Of these, 42 patients underwent patellar stabilizing surgery without trochleoplasty (group I), while 33 patients underwent thin-flap sulcus-deepening trochleoplasty as part of their surgical treatment (group II). Preoperative and postoperative magnetic resonance imaging scans were retrospectively assessed to evaluate PF cartilage, grading from 0 (intact) to 4 (full-thickness lesion) for the medial, central, and lateral patella as well as the medial, central, and lateral trochlea. Associations between patient-specific characteristics, anatomic parameters, and chondral integrity were also assessed.

Results: Patients underwent patellar stabilizing surgery at a mean age of 23.2 ± 8.0 years with a body mass index of 25.5 ± 5.0 kg/m². Postoperative magnetic resonance imaging was performed at a mean of 35.2 ± 26.3 months (range, 6-118 months). Patients in group II were slightly older (25.0 ± 7.5 vs 21.8 ± 8.2 years, respectively; P = .032) and had a significantly higher preoperative tibial tubercle-trochlear groove distance (18.4 ± 4.0 vs 14.1 ± 3.4 mm, respectively; P < .001) and patellar tilt (26.4° ± 12.5° vs 13.2° ± 6.7°, respectively; P < .001) compared with patients in group I. Both groups showed similar preoperative cartilage integrity in the PF joint (not significant). Postoperatively, both groups had similar patellar chondral damage (not significant), but group II showed significantly greater trochlear chondral damage (P = .001 for medial; P < .001 for central; and P = .002 for lateral). In comparison to preoperatively, 92.9% to 97.6% of patients in group I had intact trochlear cartilage or an unchanged status of trochlear cartilage postoperatively compared with 36.4%to 63.6% of patients in group II; the incidence varied depending on the location (P = .001 for medial; P < .001 for central; and P = .008 for lateral). Among all PF parameters, only the postoperative sagittal tibial tubercle-trochlear groove distance was associated with the progression or new occurrence of chondral damage in the medial trochlea (r = 0.232; P = .045).

Conclusion: The integrity of the PF chondral layer remained unchanged in most patients treated for patellar instability in the setting of trochlear dysplasia. Yet, significantly more patients who underwent trochleoplasty showed a decline in trochlear chondral status at short-term to midterm follow-up.