Introduction: The tissue sparing direct anterior approach (DAA/MicroHip) has been developed to improve patients’ rehabilitation and long-term function. But there was no long term evaluation up to now.

The approach is aligned along the interneural plane of Smith-Peterson, with complete preservation of the musculotendinous structures. The femoral neck oeteotomy is performed without dislocation or resection of the joint capsule. Because we perform the DAA without traction table no additional traction was applied to the soft tissues.

Methods: 55 patients underwent traditional THR (lateral approach) surgery In 2003 and 216 consecutive, non selected patients underwent THR with DAA. All Data was recorded prospectively including Haris Hip Score and gate analysis on a treadmill incorporating a dynamic force place. This data is compared to a similar group of patients operated by a traditional Harding approach. No other variables other than the surgical technique were changed for the protocol.

Results: The two groups of patients were comparable in terms of age and BMI. Blood loss dropped by 42%. Hospital stay was reduced by 2.1 days (+/−0.6.) Cup inclination was 45.56 (+/−3.4) in the traditional group and 44.8 (+/−3.7) in the MicroHip group. The dislocation rate was lower in the MicroHip group, being 0.4% compared with 3.5 in the traditional group. Harris Hip score for the MicroHip group was 91.35 (78.3) at 3 months and 94.43 (86.4) at 1 year. At five years there was still a significant difference (p< 0.001) between the two groups.

The gate analyze (excluding all patients with additional joint problems) in 98.8% of the DAA group no significant difference between the operated and the non-operated leg at five years.

Discussion: Even if the DAA a demanding technique for THR and should be used only by high volume surgeons we could prove that there is a significant long-term benefit for the patients. The benefit is certainly higher for high demand patient, but also handicapped patients or very obese patients demonstrate a better outcome. The results indicate that the joint function is more influenced by the soft tissues then by the implant design. But implant design is never the less very important for long term survivorship.