Objective To evaluate the effect of preoperative digital planning in acetabular reconstruction of total hip arthroplasty (THA) for development dysplasia of the hip (DDH). Methods A prospective study was performed on 42 patients with DDH undergoing primary THA between January 2009 and December 2011. The patients were divided into 2 groups according to whether preoperative digital planning was made or not; before operation, conventional imaging method was used in 23 cases (group A), and TraumaCad software was used for preoperative digital planning in 19 cases (group B). There was no significant difference in gender, age, body mass index, DDH classification, and preoperative Harris score between 2 groups (P gt; 0.05). The operation time, amount of bleeding, and postoperative complication were observed. After 7 days of operation, X-ray films were done to measure the vertical location, horizontal location, radiographic anteversion angle, radiographic inclination angle, and prosthesis size by TraumaCad software. The qualified rate of cup placement was compared between 2 groups. Coincidence rate of cup size between preoperative predicted by the digital planning and actually implanted in group B also was calculated. Results The operation time and the amount of bleeding were (119.25 ± 47.16) minutes and (410.00 ± 200.39) mL in group A and were (155.31 ± 84.03) minutes and (387.50 ± 251.99) mL in group B respectively, showing no significant difference between 2 groups (P gt; 0.05). Incision infection and prosthetic anterior dislocation occurred in 1 case of group A respectively, prosthetic posterior dislocation in 1 case of group B. The patients were followed up 1 year and 1 month to 4 years and 1 month (mean, 2 years and 8 months ) in group A, and 1 year and 3 months to 4 years (mean, 2 years and 7 months) in group B. At last follow-up, the Harris scores were 91.09 ± 5.35 in group A and 91.72 ± 3.48 in group B, which were significantly increased when compared with preoperative scores (P lt; 0.05), but no significant difference was found between 2 groups (t=0.41, P=0.69). The qualified rate of cup placement of group B (78.95%, 15/19) was significantly higher than that of group A (43.48%, 10/23) (χ2=5.43, P=0.02); the coincidence rate of the cup size between preoperative predicted by the digital planning and actually implanted was 68.42% (13/19). ConclusionPreoperative digital planning can further optimize the acetabular reconstruction in THA for DDH.
Objective To investigate the effect of femoral offset reconstruction on pelvic stabil ity during gait after total hip arthroplasty. Methods According to the inclusion criteria, 29 patients undergoing unilateral total hip arthroplasty between January 2000 and December 2005 were selected. There were 10 males and 19 females with an average age of 64.3 years (range, 33-75 years). The affected hips included 15 left hips and 14 right hips. The follow-up time was from 5 to 10 years (mean, 7.7 years). The Harris score was 90 to 100 (mean, 97) at last follow-up. The femoral offset ratio (FOR) was calculated by measuring the femoral offset of the bilateral hips on radiograph, and then the patients were divided into 2 groups: group A (the femoral offset of diseased hip was less than that of normal hip, n=10) and group B (the femoral offset of diseased hip was greater than that of normal hip, n=19). The pelvis kinematic variables were measured by three-dimensional gait analysis to collect the magnitude of pelvic obl ique angle (POA). Results In group A, the FOR was 0.81 ± 0.08 and the POA was (—0.42 ± 0.91)°. In group B, the FOR was 1.27 ± 0.15 and the POA was (1.02 ± 0.94)°. For the normal hip, the POA was (1.15 ± 0.85)°. The POA was significantly less in group A than in group B and the normal l imb (P lt; 0.05). The difference in POA had no significance between group B and the normal hip (P gt; 0.05). The POA was positive relative with FOR (r=0.534, P=0.003), and the regression equation was y= — 2.551+ 2.781x. Conclusion The femoral offset reconstruction is crucial to improve hip abductor function and gait.