gms | German Medical Science

Objectives: To compare the survival-rate, complications and radiographic results of Anatomic (AC) vs High (HC) rotation centers in the mid-term, in patients with Crowe 3 and 4 Developmental Dysplasia of the Hip (DDH), who had undergone Total Hip Arthroplasties (THA).

Methods: We retrospectively reviewed charts and radiographs of 41 patients (45 hips) with arthrosis due to Crowe 3 and 4 DDH, operated by a single surgeon in our institution from 1998 to 2012. The mean follow-up was 8.7 years (range 4-18 years, SD 3.2). All patients had a posterolateral approach, and implants were selected according to the patient's characteristics and surgeon's preference. Radiographic analysis were performed by an independent surgeon; they included cup abduction and hip center, calculated with Meazure® 2.0 software. Anatomic rotation center was defined as ≤20 mm above from the interteardrop line. To assess survival rate, we excluded revision due to instability (n=2) or infection (n=1), and used GraphPad Prism® 7.02 software, obtaining Kaplan Meier survivorship and comparing with Mantel-Cox Test and Gehan-Breslow-Wilcoxon test. The complication rate was evaluated with Fisher's test.

Results: The mean age was 42 years (range 24-73, SD 11.1), 71.1% were females. Trochanteric osteotomy was performed in 9 cases. Sub-trochanteric transverse femoral-shortening was needed in 9 cases, and acetabular augmentation with femoral head autograft in 11 patients. The construction was hybrid in 40.5% (non-cemented cup, cemented stem), all-cemented in 33.3% and non-cemented in 26.2%. There were 20 cups cataloged as HC (44.4%) and 25 as AC (55.6%) (Table 1 [Tab. 1]).

The overall complication rate was 37.8%. Two of the dislocations required revision surgery, and one deep infection leaded to implant removal and two-timed revision surgery. The trochanteric osteotomy was discontinued in 2009 due to its high non-union rate (44.4%) (Table 2 [Tab. 2]).

The complication rate was higher in the AC group (44%) than the HC group (35%), but not statistically significant (p=0.76). The 12-year survival rate was similar for both groups (AC 95.7% HC 94.7% p=0.91) (Figure 1 [Fig. 1]).

Conclusion: At mid-term follow up, we achieved a good survival rate despite the complexity of high developmental dysplasia. This demanding surgery carries a considerable complication rate that should be taken into account. Both rotation centers had similar survival and complications rate.