A 6 to 10 Years Follow-Up Study Comparing Two-incision Total Hip Arthroplasties in Patients with Osteonecrosis of the Femoral Head or Hip Dysplasia

Abstract

Muscle sparing approaches for total hip arthroplasties (THAs) have been advocated in the past two decades. The twoincision approach technique is one of the muscle sparing approaches. The technique has the potential benefits of avoiding muscle and tendon damage, less intraoperative blood loss, rapid patient recovery, and shortened hospitalization but might increase complications such as fractures, nerve injury, and implants malposition, so it required a steep learning curve.1-6 The ideal cup position, stem alignment, and proper leg length and offset are the keys to a successful THA. Our previous study has demonstrated that using of intraoperative fluoroscopy or imageless navigation system can increase the accuracy of cup and stem alignment for the two-incision THA. AbstractTwo-incision total hip arthroplasty (THA) has a steep learning curve and might increase the risks of implant malposition and perioperative complications in difficult cases. Whether dysplasic hip or osteonecrosis of the femoral head (ONFH) would have different results by the two-incision technique remains unreported. From 2003 to 2010, 159 hips in 151 patients (68 female and 83 male) treated with the two-incision THA were included. Cases were divided into two groups with ONFH in 99 hips and dysplasia in 60 hips. The inclusion criteria for hip dysplasia were a Sharp's angle more than 43°and coverage of the femoral head less than 75%. Clinical data and radiological measurement were retrospectively analyzed. The ONFH patients had younger age (48.5 AE 12.8 years) with male predominance (74%) while the dysplasic patients had older age (62 AE 12 years) with female predominance (76%). There were no differences in preoperative functional score, operation time, blood loss, wound size, and length of hospital stay between groups. The ONFH group had bigger cup size (p ¼ 0.028) but similar stem size (p ¼ 0.072) as compared with the dysplasia group. The cup inclination angle was 43.7°AE 4.8°and 42.8°AE 5°(p ¼ 0.25) and the cup anteversion angle was 17.6°AE 7.6°and 14.2°AE 8.2°(p ¼ 0.009), in the ONFH and the dysplasia group, respectively. At the final follow-up, there were three revisions cases (one septic loosening in the dysplasia group and two periprosthetic fractures in the ONFH group). No dislocation was noted in the study cohort. We had overall 99.4% cup and 98.1% stem survival rate with the two-incision THA. The only differences were the bigger cup size and the more anteverted cup position in the ONFH hips as compared with the dysplasic hips. The two-incision THA seemed to be successful for patients with ONFH or dysplasic hips.