ObjectiveTo analyze the methods of offside reconstruction in total hip arthroplasty (THA) for severe osteoarthritis. MethodsBetween July 2009 and June 2011,18 cases (18 hips) of severe osteoarthritis of the hip were treated by THA,including 14 males and 4 females with a mean age of 55.4 years (range,47-72 years).The disease duration was 11-74 months (mean,33.6 months).The left hip was involved in 11 cases and the right hip in 7 cases.The hip Harris score was 34.6±5.3.The lower limb discrepency was observed in 15 cases.Thomas sign,Patrick sign,and Trendelenburg sign were positive in all cases.All patients received THA; during operation,standard femoral neck osteotomy was performed and the correct rotation center was chosen to reconstruct offside. ResultsAll the incisions healed primarily.Common peroneal nerve injury occurred in 1 case and was cured after symptomatic treatment for 3 months,and the other patients had no complication.The mean follow-up period was 43.5 months (range,30-53 months).All patients achieved pain relief,and returned to normal gait.The X-ray films showed no dislocation of the hip or prosthetic loosening.Lower limb discrepency was observed in 6 cases.The mean offside difference between normal and ipsilateral side was 0.4 mm (range,0.1-0.7 mm).At last follow-up,the hip Harris score was 83.0±7.1,showing significant difference when compared with preoperative score (t=-22.96,P=0.01); the hip range of motion was significantly increased when compared with preoperative one (P<0.05). ConclusionThe offside reconstruction can accurately be carried out by making precise template and vernier caliper measurement,selecting suitable prosthesis preoperatively,maintaining the proper femoral calcar length,adjusting the length of the neck and neck-shaft angle,releasing the soft tissue reasonably during THA for severe osteoarthritis,and the short-term effectiveness is satisfactory.