Measuring the the angle of external rotation of the tibial component preop helped to determine the extent of external rotation of the tibial component intraoperatively. A significant decrease of the postop Q angle was noticed in all patients.
A strict radiological and CT evaluation was done prior to and following the surgery and accompanied the clinical evaluation and follow up. A cohort of 32 patients is presented in details regarding the imaging pre-operative planning and the post-operative results. The radiological data included: 1. Angle of frontal deformity; 2. Angle of instability; 3. Fi-Fc – distance from the tip of the fibular head to the distal part of the lateral femoral condyle; 4. Frontal inclination angle of tibial component; 5. Frontal inclination angle of femoral component; 6. Sagital posterior inclination of tibial component; 7. Sagital posterior inclination angle of the femoral component; 8. The distance from the patella to the knee center of motion. The computed tomography data included: 1. The actual dimensions of the patella, tibia and femur; 2. The preoperative angle between the posterior condylar line and anterior condylar line; 3. The angle between the posterior condylar line and the trans-epicondylar line; 4. The angle of external rotation of the femoral component; 5. The angle of external rotation of the tibial component; 6. The distance of lateralization of the femoral and tibial components.
Measuring the angle of external rotation of the tibial component preop helped to determine the extent of external rotation of the tibial component intraoperatively. A significant decrease of the postop Q angle was noticed in all patients.
The imaging parameters that were collected from patient X-rays were: radiolucent line, osteolysis, subsidence, cortical hypertrophy, cortical thinning, undersizing, distal pod, rounded calcar, cupping and sagging.
No sign of loosening were observed in any patient, 23 stems were implanted in neutral position, 2 stems in valgus and 6 in varus position. In 15 patients stem was undersized. In 23 patients distal pod was observed, 19 patients had trochanteric osteopenia, in 10 patients cupping was noticed and in 6 patients cortical thinning was observed. Five patients showed proximal osteopenia and in 5 patients sagging of few millimeters was noticed during the first years after surgery. No radiolucent line, osteolysis, subsidence and cortical hypertrophy were observed up to 11 years follow-up.
Based on our experience, our recommendations are that:
Ceramic bearing surfaces T.H.A.-s should be performed in specialized centers. The use of 32 mm. heads should be considered in order to avoid dislocations. With 28 mm. heads, full profile cups should be considered. Conservative physical therapy and range of motion exercises for 6–12 weeks.