Stem Geometry Recommendation for Total Hip Replacement Planning Using Computed Tomography Data Analysis

Total Hip Replacement (THR) requires careful preparation, especially in the geometry suitability between the patient's bone and the implant. If applied incorrectly, it will be dangerous for the patient, such as the risk of complications, dislocation, and re-surgery. This paper aims to compare the size of the patient's THR geometry as a basis for consideration in implant designs to minimize the risk of harm after implantation. This study was limited to male patients only. The computed tomography scanning data (CT-Scan data) in the lower abdomen, segmented to hip joint area belonging to the American race and an Indonesian male, were compared. The comparison indicates that the American race data has a greater dimension than Indonesian. The American hip bone geometry result follows the standard modern implant by Johnson and Johnson size. By all analysis, the fittest geometry for the Indonesian male patient needs to adjust and has a smaller size than the commercial implant. This study finally recommends the specific length of the femoral stem for the optimal THR implant with the parameter values of Femoral Head Offset, Neck Length, Neck Shaft Angle, Mediolateral Width 1, Mediolateral Width 2, Mediolateral Width 3 respectively for the right THR, namely 37.9; 31.6; 134.3; 43.1; 13.62; 12.36; while the left THR is 38.9; 31.7; 134.5; 43.1; 13.70; 12.4 in mm. Overall, precise implant planning based on real patient conditions and anthropometry is necessary to match implants and bone anatomy.