Description
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.
Hypothesis/Purpose: The aim of the herein presented study was to assess the mid-term effect of trochleoplasty on the PF cartilage integrity in patients with severe trochlear dysplasia treated for patellar instability.
Study Design: Case-control study
Methods: Seventy-five patients with high-grade trochlear dysplasia (Dejour type B and C) who underwent patellar stabilizing surgery for patellar instability at a single institution were included. Of these, 42 patients had patellar stabilizing surgery without trochleoplasty (group I), while 33 patients received sulcus deepening trochleoplasty as part of their surgical treatment (group II). Pre- and postoperative magnetic resonance imaging (MRI) was retrospectively assessed to evaluate the PF cartilage from 0 (intact) – 4 (full-thickness lesion) separately scoring the medial, central, and lateral patella and trochlea, respectively. Associations between patient-specific characteristics, anatomical parameters and chondral integrity were also assessed.
Results: Patients underwent patellar stabilizing surgery at an average age of 23.2 ± 8.0 years with a BMI of 25.5 ± 5.0 kg/m2. Postoperative MRI was attained at an average of 35.2 ± 26.3 months (range, 6-118 months). Patients in group II were slightly older (21.8 ± 8.2 years vs. 25.0 ± 7.5 years, p=0.032) and presented with a significantly higher TTTG distance (14.1 ± 3.4 mm vs. 18.4 ± 4.0 mm, p<0.001) and patellar tilt (13.2 ± 6.7° vs. 26.4 ± 12.5°, p<0.001) compared to group I. Both groups showed similar preoperative cartilage integrity in the PF joint (n.s.). Postoperatively, both groups had similar patellar chondral damage (n.s.) but group II showed significantly greater trochlear (all zones) cartilage damage (p<0.001 (medial), p=0.001 (central), p=0.002 (lateral)). Compared to the preoperative state, 92.9-97.6% of patients in group I had an intact or unchanged status of the trochlear cartilage compared to 32.8-63.6% in group II, depending on the location (p<0.001 (medial), p=0.001 (central), p=0.008 (lateral)). Among all PF parameters, only the postoperative sagittal TTTG was associated with the progression or new occurrence of chondral damage on the medial trochlea (r=0.232, p=0.045).
Conclusion: The integrity of the PF chondral layer remains unchanged in most patients treated for patellar instability in the setting of trochlear dysplasia. Yet, patients who underwent trochleoplasty showed significantly more often trochlear chondral status decline at mid-term follow-up.
