Mid-term results of short-stem total hip arthroplasty in patients with Crowe type I and II developmental dysplasia of the hip.

BACKGROUND

This study aimed to evaluate the clinical and radiographic mid-term results of short-stem THA in patients with DDH.

METHODS

We reviewed 32 cases that underwent Metha stem between November 2010 and February 2015. WOMAC scores, Oxford Hip Scores (OHS) and Harris Hip Scores (HHS) were recorded to evaluate the clinical results. The appearance of bone trabeculae development and stress shielding was analyzed.

RESULTS

The mean age of patients was 50.3 years (33-67) with the mean follow-up of 77 months (60-106). According to Crowe classification, 13 cases were graded as Crowe I and 19 cases as Crowe II. According to Dorr classification, 17 cases were graded as Dorr A and 15 cases as Dorr B. The postoperative WOMAC scores decreased, and OHS and HHS increased significantly compared with preoperative (p < 0.001). The caput-column-diaphysis angles decreased significantly (p < 0.001) and limb length discrepancy decreased significantly (p = 0.013) after surgery. The radiographic change around the stem showed bone trabeculae development at zones 1 (93.9%), 2 (93.9%), 3 (25%), 5 (6.3%), 6 (96.9%) and 7 (90.6%). There was grade 1 stress shielding in 30 cases (93.9%). There was no stem subsidence greater than 2 mm in all hips, no sciatic nerve injury or no dislocation. Neither acetabulum nor femoral stem was defined as definite loosening, and none of the implants was revised.

CONCLUSIONS

The short stem showed promising mid-term clinical results in patients with DDH. The radiographic results demonstrated that the short stem provided physiological proximal load transfer with less stress shielding, being a useful alternative for femoral reconstruction.