Effect of Leg Length Discrepancy on Lateral Center-edge Angle Measurement

When to Combine Acetabular Osteotomy in Patients With Proximal Femoral Deformity Causing Residual Hip Dysplasia/Subluxation After Reduction of Developmental Dysplasia of the Hip

BACKGROUND

After the successful reduction of developmental dysplasia of the hip, residual hip dysplasia may persist and lead to early osteoarthritis. Femoral and/or acetabular osteotomy has been used to address this problem. The purpose of this study is to determine the indication of femoral versus combined femoral-acetabular osteotomy in the management of residual hip dysplasia.

METHODS

Fifty-five patients with unilateral dislocated-type dysplasia of the hip, who had residual hip dysplasia after reduction, underwent femoral osteotomy with or without acetabular osteotomy before 8 years of age, and were followed for more than 2 years and over 8 years of age, were the subjects of this retrospective study. Twenty-eight patients underwent femoral osteotomy only at a median age of 34 months (group F), and 27 underwent combined femoral-Dega osteotomy at a median age of 49 months (group C). Seventeen patients in group F and 4 in group C had an additional osteotomy due to persistent hip dysplasia. Acetabular index (AI), lateral center-edge angle, and center-head distance difference were measured on serial radiographs. The z-value of AI (Z AI ) was calculated. At the latest follow-up, patients in group F with Severin I/II who did not have an additional osteotomy were considered satisfactory, and patients with Severin III/IV or those who had an additional osteotomy were considered unsatisfactory. Preoperative variables were tested for the difference between satisfactory and unsatisfactory cases. Receiver operating characteristic analysis was performed to delineate a cutoff value of a significant parameter dividing the outcome.

RESULTS

AI and Z AI before index osteotomy were significant parameters predicting a satisfactory outcome in group F. Receiver operating characteristic analysis returned a cutoff value of Z AI 2.6 (Area Under the Curve=0.86, P =0.001). Eight of 12 cases (66.7%) with Z AI <2.6 in group F achieved a satisfactory outcome, whereas only 2 of 14 cases with Z AI ≥2.6 in group F did ( P =0.02).

CONCLUSION

Z AI 2.6 may serve as a threshold to combine acetabular osteotomy with femoral osteotomy in the management of residual hip dysplasia before 8 years of age.

LEVEL OF EVIDENCE

Therapeutic III.

Performance of Tönnis triple osteotomy in older children with developmental dysplasia of the hip (DDH) assisted by a 3D printing navigation template

Background

The objective of this study is to investigate the preparation of a navigation template via a computer-aided design (CAD) and 3D printing (3DP) in order to improve the effectiveness of Tönnis triple osteotomy in older children with developmental dysplasia of the hip (DDH).

Method

Thirty-eight older children who received Tönnis triple osteotomy were included in this study. Among them, 20 were categorized as the 3DP navigation template group (3DP group), and the remaining 18 were categorized as the conventional surgery group (CS group). Data, including preoperative and postoperative pelvic sharp angle (SA), lateral center-edge angle (LCEA), acetabular roof angle (ARA), acetabular head index (AHI), crossover sign (COS), ischial spine sign (ISS), operation time (OT), intraoperative blood loss (IBL), and number of radiation exposures (NORE) were recorded for both groups. In addition, the therapeutic effect was evaluated at the last follow-up, according to the McKay criteria and Severin’s criteria.

Results

In the 3DP and CS groups, the mean OT was 126.6 ± 17.6 min and 156.0 ± 18.6 min, respectively; the mean IBL was 115.0 ± 16.9 ml and 135.7 ± 26.5 ml, respectively; the NORE were 3.3 ± 0.8 times and 8.6 ± 1.3 times, respectively. There were significant differences in the OT, IBL, and NORE between the two groups (P = 0.03, 0.05, < 0.001, respectively). At the last follow-up, the 3DP and CS groups displayed SA of 41.8 ± 2.3° and 42.6 ± 3.1°, respectively; LCEA of 35.6 ± 4.2° and 37.1 ± 2.8°, respectively; ARA of 6.9 ± 1.8° and 9.8 ± 2.6°, respectively; and AHI of 86.6 ± 4.1% and 84.3 ± 2.8%, respectively; COS(+) of 5 hips and 4 hips, respectively; ISS(+) of 6 hips and 7 hips. We observed no statistical differences in the SA, LCEA, ARA, AHI, COS and ISS between the two groups (P = 0.918, 0.846, 0.643, 0.891, 0.841, 0.564, respectively). According to the McKay criteria, the 3DP group had 10 excellent, 6 good, and 4 general hips, whereas, the CS group had 12 excellent, 4 good, and 2 general hip. There was no statistical difference between the two groups (P = 0.698). In 3DP group the postoperative Severin’s grading included 13 hips in grade I, 4 in grade II, 3 in grade III. Alternately, in the CS group, the postoperative Severin’s grading included 11 hips in grade I, 5 in grade II, 2 in grade III. The Severin ‘s criteria also showed no statistical difference between the two groups (P = 0.945).

Conclusions

Base on our analysis, our CAD-3DP-fabricated navigation template assisted Tönnis triple osteotomy in older DDH children, it reduced operation time and number of radiation exposures. However, no significant differences in radiological assessment and functional outcomes were observed when an experienced surgeon performs the surgery. Therefore, Surgeons who have less experience in triple osteotomy profit more from the application of this technology.