ObjectiveTo analyze and summarize the short-term effectiveness of total hip arthroplasty (THA) with a tapered, modular neck hip stem for developmental dysplasia of the hip (DDH). MethodsBetween October 2010 and May 2012, 28 patients (31 hips) with DDH and secondary osteoarthritis underwent THA with a tapered, modular neck hip stem. There were 2 males and 26 females, with an average age of 61 years (range, 47-77 years). The unilateral hip was involved in 25 cases and bilateral hips in 3 cases. According to the Crowe system, 22 cases were classified as Crowe type I, 8 as Crowe type Ⅱ, and 1 as Crowe type Ⅲ. At preoperation, the leg length discrepancy was (1.6±0.8) cm; the hip range of motion values were (76.1±12.8)° in flexion, (14.5±6.7)° in abduction, (9.0±4.5)° in adduction, (13.1±6.4)° in internal rotation, and (11.7±7.0)° in external rotation; and the Harris hip score was 44.7±11.1. ResultsFemoral neck fracture occurred in 2 cases (2 hips) during operation, which healed by fixed with steel wire. The incisions healed by first intention. No related complication occurred. The mean follow-up time was 20 months (range, 12-32 months). At last follow-up, the leg length discrepancy was significant decreased to (1.0±0.5) cm (t=-3.512, P=0.002). The hip range of motion values were (102.9±10.1)° in flexion, (32.9±6.0)° in abduction, (19.2±4.3)° in adduction, (34.4±4.2)° in internal rotation, and (32.3±5.1)° in external rotation, all showing significant differences when compared with preoperative values (P<0.05). The Harris hip score was significantly improved to 90.3±6.1 (t=21.263, P=0.000). The X-ray films showed no subsidence, loosening, or breakage in the other cases except 2 cases having subsidence (<2 mm) within 1 year. Heterotopic ossification occurred in 2 hips. ConclusionThe short-term effectiveness of THA with a tapered, modular neck hip stem for DDH is satisfactory. However, the medium and long-term effectiveness still need further follow-up.