CT changes after trochleoplasty for symptomatic trochlear dysplasia

Abstract

Trochlear dysplasia is an important risk factor for patellar instability. Because of a decreased trochlear depth in combination with a low lateral femoral condyle, the patella cannot engage properly in the trochlea. Trochleoplasty is a surgical procedure, which strives to correct such bony abnormalities. The aim of this study was to describe morphological features of trochlear dysplasia and the corrective changes after trochleoplasty on CT scan. The study group consists of 17 knees with trochlear dysplasia having undergone trochleoplasty for recurrent patellofemoral dislocation at a mean age of 22.4 years. The evaluation consisted in pre-and postoperative measurements on the proximal and distal trochlea on transverse CT scans in order to determine the morphological features. We measured the transverse position and depth of the trochlear groove, the transverse position of the patella, the ratio between the posterior patellar edge and the trochlear groove, the lateral patellar inclination angle, the sulcus angle, and the lateral trochlear slope. The trochlear groove lateralised a mean of 6.1 mm in the proximal aspect and 2.5 mm in the distal aspect of the trochlea, while the patella medialised a mean of 5 mm. Preoperatively the patella was lateral in relation to the trochlear groove in 13 cases, neutral in two cases, and medial in two cases. Postoperatively it was lateral in four cases, in neutral position in seven cases, and medialised in six cases, referenced to the trochlear groove. The trochlear depth increased from 0 to 5.9 mm postoperatively in the proximal aspect of the trochlea, and from 5.5 to 8.3 mm postoperatively in the distal trochlea. The lateral patellar inclination angle decreased from a mean of 21.9°to a mean of 7.8°. The sulcus angle decreased from a mean of 172.1°to a mean of 133°in the proximal trochlea and from a mean of 141.9°to a mean of 121.7°in the distal trochlea. The lateral trochlear slope changed from 2.8°to 22.7°in the proximal and from 14.9°to 26.9°in the distal part of the trochlea. In the CT scan patients with trochlear dysplasia demonstrated a poor depth, or even a flat or convex trochlea with a greater sulcus and lateral trochlear slope angle, a lateralised patella to the trochlear groove with poor congruency, and a greater lateral patellar inclination angle. Trochleoplasty can correct the pathological features of trochlear dysplasia by surgically creating more normal anatomy. The goal of this surgical procedure is to steepen and lateralise the trochlear groove for a better engagement of the patella.

Surgical treatment of patellofemoral instability using trochleoplasty or MPFL reconstruction: a systematic review

“…Fucentese et al [9] have shown similar results for trochleoplasty patients. They reported that trochleoplasty leads to normal patellofemoral anatomy by correction of the pathological characteristics.…”

Is there a relationship between anterior knee pain and femoral trochlear dysplasia? Assessment of lateral trochlear inclination by magnetic resonance imaging

“…Computed tomography (CT) scans have been used for measuring lateral trochlear inclination [10]. However, when possible etiologic factors of anterior knee pain is the concern, MRI seems to be more useful than CT to make specific diagnoses.…”

Arthroscopic Deepening Trochleoplasty: The Technique

“…4,5 The medialized groove causes the tibial tubercle-trochlear groove distance to increase, the low lateral inclination angle decreases the osseous stability, and the tilt occurs as a consequence of the patella articulation with the lateral facet only. 6 The trochleoplasty procedure seems to more or less normalize these anatomical issues 7 and correspondingly it provides good clinical results. This is illustrated by multiple studies in which improvements in patella stability, reduction of anterior knee pain (AKP), and better quality of life have been shown compared with other surgical procedures in cases with severe trochlear dysplasia.…”