Abstract
PurposeThe aim of the present study is to present the outcome of a cohort of adolescent patients with trochlear dysplasia and elevated tibial tuberosity trochlear groove (TTTG) distance suffering from recurrent patellar dislocation. Treatment consisted of medial patellofemoral ligament (MPFL) reconstruction and a modified Grammont procedure.MethodsMRI examinations were obtained pre- and postoperatively. Trochlear dysplasia was classified according to Déjour, and TTTG was measured on MRI. The Tegner Activity Scale and the Kujala Knee Score were assessed preoperatively and at follow-up. The Kujala Knee score and the IKDC 2000 knee score were documented at follow-up (median 50, range 20–61 months; SD 16.6).ResultsSeven knees of six patients (median age 16.5 years, range 14–17 years) with trochlear dysplasia and elevated TTTG distance (median 17 mm, range 16.1–21.9 mm; SD 2.8) were treated. Trochlear dysplasia was classified as Déjour type A in 1, type B in 5, and type C in 1 knee. The Kujala Knee Score significantly increased from values of 55 (range 17–88; SD 25.9) to 94 (range 73–100; SD 9.1) at follow-up (p = 0.028). TAS improved from preoperative 2 (range 0–7; SD 2.5) to 5 (range 4–9; SD 1.8) at follow-up (p = 0.034). Median IKDC 2000 Knee Score at follow-up was 89 (range 61–100, SD 13.4). No re-dislocations were encountered.ConclusionIn selected adolescents with recurrent patellofemoral instability, MPFL reconstruction in combination with a modified Grammont technique yields excellent functional outcome and could, therefore, help to avoid major procedures, such as osteotomies.Level of evidenceTherapeutic, Level IV.
Highlights
The stability of the patellofemoral joint is guaranteed by a complex interaction between the surrounding soft tissue and bony structures
Trochlear dysplasia Déjour type A was diagnosed in one knee, Déjour type B in five knees, and Déjour type C in one knee
tuberosity trochlear groove (TTTG) distances were elevated in all patients
Summary
The stability of the patellofemoral joint is guaranteed by a complex interaction between the surrounding soft tissue and bony structures. Active stabilizers (the quadriceps muscle) can be differentiated from passive stabilizers, such as the retinacula and the medial patellofemoral ligament (MPFL), and static stabilizers, such as the trochlear geometry itself [30]. Trochlear dysplasia seems to be a major risk factor for failure of operative stabilization of recurrent patellofemoral instability (PFI) in children and adolescents [22]. Another relevant anatomical factor responsible for recurrent instability is an increased distance between the tibial tuberosity and the trochlear groove (TTTG).
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