gms | German Medical Science

Objectives: Here we present our results of Total Hip Arthroplasty (THA) in a series of patients with arthrosis due to Developmental Dysplasia of the Hip (DDH). We assessed the radiological features, clinical score, complications and survival rate.

Methods: We retrospectively reviewed the records and X-ray films of patients who had undergone THA due DDH from 1998 to 2014 in our institution. We included 53 patients (63 hips) with a mean follow-up of 8.4 years (range 2-18). All patients were operated by the same surgeon, by posterolateral approach. The implant was selected according to the patient's characteristics and surgeon's preference. In follow-up X-rays, we evaluated cup abduction and hip rotation center with Meazure® 2.0 software; anatomical center was defined as ≤ 20 mm from above the interteardrop line. To assess survival rate, we excluded revision due to instability or infection. Kaplan Meier curve was compared with Mantel-Cox and Gehan-Breslow-Wilcoxon tests (GraphPad Prism® 7.02). Fisher's test was used to evaluate the complication rates. The modified Oxford Hip Score and radiographic analysis were performed by an independent surgeon at end of follow-up.

Results: The mean age at surgery was 44 years (range 24-73, SD 10.9), 68.2% of patients were females. According to the Crowe classification, we had 28.6% of low-dysplasia (one patient Crowe-1 and 17 Crowe-2) and 71.4% of high-dysplasia (25 Crowe-3 and 20 Crowe-4). A trochanteric osteotomy was performed in 9 cases. Sub-trochanteric femoral-shortening was needed in 9 cases of high dysplasia. Acetabular augmentation by a femoral head autograft was used in 13 hips. The construction choice was hybrid 38% (non-cemented cup, cemented stem), non-cemented in 35%, and all-cemented in 27%. The mean cup abduction angle was 43.2° (SD 10.4°, range 17-75°), obtaining an anatomical hip center in 63.5% of the hips. However, when segregating the data between low or high dysplasia, we noticed that an anatomical center was achieved in 83.3% of low-dysplasia, but only in 55.5% of high-dysplasia (p=0.046, OR 4) (Table 1 [Tab. 1]).

The overall complication rate was 31.8%, mostly in high-dysplasia (90% of the complications, p=0.03) (Table 2 [Tab. 2]).

The modified Oxford Hip Score was 38.2 (range 14-48 SD 9.0). Excluding revision due to infection or instability, we achieved a survival rate of 96.5% at 12 years (Figure 1 [Fig. 1]).

Conclusions: This challenging procedure -even for an experienced surgeon- has considerable complication rate, mainly in high dysplasia patients, with a more complex reconstruction of the anatomical hip center. The promising mid-term results should be followed in long term.