Abstract
The aim was to study the evolution of radiographic patterns of osteointegration of tapered wedge stems and determine if there is correlation with bony morphology and initial stem fit.
We reviewed primary total hip replacements performed by two surgeons using a single cementless tapered wedge design and that had a complete series of radiographs (defined as preoperative, 6 weeks, 1 year and 5 or more years).
Signs of bony remodeling were recorded at each Gruen zone. Calcar remodeling, changes in cortical thickness, evidence of subsidence and pedestal formation were recorded (Figure 1).
57 hips (50 patients) were available for analysis with a mean follow up of 5.03 years. Mean changes in cortical thickness were positive in zones 2(7.51) and 6(5.36) and negative in zones 1(−7.53) and 7(−13.51). Radiolucent lines were found in gruen zones 3,4(39%), and 5. Femoral neck cancellization was seen in zone 7 in 8 patients (14%) in year 1 and 36 (63%) by year 5.
Correlations were seen with proximal canal fill and radiolucent lines at zones 3 (0.278; p0.36) and 5 (0.258; p 0.05) and with distal canal fill and hypertrophy of the cortex in zone 3 (0.429; p0.001) and 5.
Cortical hypertrophy around the midstem, lack of radiolucent lines around the proximal stem and cancellization of the calcar are all radiographic patterns which occur routinely. A positive correlation with distal canal fill and hypertrophy of zones 3 and 5 was noted.
There was no significant correlation with preoperative boney morphology or initial stem fit proximally.
