Comparison of different tendon transposition techniques for the treatment of monocular elevation deficiency type 2

Abstract

To compare results of three different tendon transposition techniques (Knapp procedure and two modified techniques) for the treatment of type 2 monocular elevation deficiency (MED) patients. The medical records of patients with MED type 2 operated on at a single institution from 2000 to 2016 were reviewed retrospectively. Patients were divided into three vertical transposition groups: (1) full tendon width, (2) augmented surgery; and (3) partial tendon width. Surgical success was defined as no severe limitation of upgaze, hypotropia of <6Δ, and no hypertropia in primary position. Pre- and postoperative vertical deviations in the primary position and limitations in elevation levels were compared. A total of 39 patients were included. The pre- and postoperative deviations in the full-tendon group were 22.50Δ ± 4.17Δ and 3.50Δ ± 1.27Δ, respectively; in the augmented surgery group, 23.75Δ ± 4.78Δ and 1.75Δ ± 1.14Δ; and in the partial-tendon group, 20.50Δ ± 3.98Δ and 4.12Δ ± 2.78Δ. Corrected vertical deviations were 19Δ, 23Δ, and 16Δ, respectively. The pre- and postoperative limitation of elevations were -2.80 and -0.80 in the full-tendon group, -3.20 and -0.90 in the augmented surgery group, and -2.37 and -1.12 in the partial-tendon group. The pre- and postoperative vertical deviation improvements and limitations of elevation were statistically significant (P<0.05) in all groups. Success was achieved in 29 patients (74%). In this study cohort, all three procedures were reasonably effective in improving vertical deviations and limitation of elevation.