ObjectiveTo summarize the short-and medium-term effectivenesses of stemless hip arthroplasty for treating hip joint disease in young and middle-aged patients. MethodsBetween June 2005 and December 2010, 25 cases (27 hips) of hip joint disease were treated with stemless hip arthroplasty. There were 17 males (19 hips) and 8 females (8 hips) with an average age of 45.6 years (range, 30-57 years), including 13 left hips, 10 right hips, and 2 bilateral hips. The causes included avascular necrosis of the femoral head (ANFH) secondary to femoral neck fracture in 5 cases (5 hips), ANFH in 15 cases (16 hips), osteoarthritis of the hip joint caused by ankylosing spondylitis in 2 cases (3 hips), osteoarthritis of the hip joint caused by dysplasia of acetabular in 2 cases (2 hips), and rheumatoid arthritis in 1 case (1 hip). The disease duration was 1-17 years (mean, 6.1 years). Before operation, the Harris score was 47.6±14.2. ResultsThe incision healed by first intention in all patients, and no complications occurred, such as infection, periprosthetic fracture, and deep vein thrombosis of lower extremity. Twenty-five patients (27 hips) were followed up 36-96 months (mean, 51 months). One case (1 hip) had sciatic nerve injury after operation, which was relieved by symptomatic treatment. One case (1 hip) had prosthesis loosening, which was relieved after revision. The survival rate of prosthesis was 96.3% (26/27). At last follow-up, the Harris score was 92.1±3.6, which was significantly better than preoperative score (t=18.241, P=0.000). The excellent and good rate was 88.9% (excellent in 19 hips, good in 5 hips, fair in 2 hips, and poor in 1 hip). The X-ray films showed good location of prosthesis, and no evidence of dislocation, bone resorption, osteolysis, and heterotopic ossification. ConclusionBecause of reserving femoral neck, biomechanics conduction and distribute of the proximal femur achieve natural biomechanics state of the human body. The short-and medium-term effectivenesses of stemless hip arthroplasty for treating hip joint disease in young and middle-aged patients are satisfactory, but the long-term effectiveness need further observation.