ABSTRACT
In recent years, opening-wedge osteotomy has gained popularity. However, the complication
rate reported is high. Opening-wedge osteotomy was modified to remedy the problems
seen with the conventional technique including loss of correction, delayed healing,
and patella infera. This biomechanical study evaluates the response of a new opening-wedge
osteotomy in a static and dynamic mode of human cadavers. Results were compared to
the stability of the conventional technique. Six preserved pairs of human cadaveric
knees were tested. Specimens of the same pair were randomly assigned to either the
modified or conventional osteotomy. Internal fixation was used to ensure precise correction
and prevent bone collapse. Each tibia was loaded on a material testing system from
0 to 700 N for 10,000 cycles to simulate immediate full weight bearing in a walking
individual. Specimens were then loaded to failure to determine ultimate load and stiffness
of the construct. Displacement of the articular fragment and stiffness were measured
during dynamic loading. Load to failure, displacement, and stiffness were measured
during static testing. The modified osteotomy provided significantly greater stiffness
(1392 N/mm) and smaller loss of correction (.68 mm) than the conventional osteotomy
(741 N/mm; 1.76 mm) under cyclic loading conditions (P < .05). The modified retrotubercle osteotomy provides greater stiffness than the
conventional osteotomy, increasing stability by 62% and minimizing loss of correction
to <1 mm. The modified osteotomy eliminates the need for bone graft and provides additional
strength to allow accelerated rehabilitation.
