[Evaluation of results after total hip replacement using a minimally invasive and a conventional approach. Clinical scores and gait analysis]

Abstract

Aim: In a prospective study the results of total hip replacement of patients with coxarthrosis and minimally invasive anterolateral (MIS; n = 48) vs. conventional transgluteal approach (KONV; n = 10) were investigated by means of clinical and functional outcomes. Different clinical scores and gait parameters were compared with each other preoperatively and on average 5 weeks and 6 months postoperatively as well as to a control group (VG; n = 58) of healthy age-matched probands.

Material and method: For clinical examination the range of hip motion was determined and the Harris hip score (HHS), the score according to Merle d'Aubigné (MD), the intensity of pain (visual analogue scale - VAS), the SF-36 and the WOMAC arthrosis index have been used. Furthermore, the subjective gait pattern was interpreted and the Trendelenburg sign was analysed. The influence of the implantation on the biomechanics of the joint was estimated with a biomechanical score by analysing the pelvic radiographs. Objective measurement data of the gait were obtained by using a three-dimensional motion analysis system with six infrared cameras and three force plates.

Results: Both groups of patients had good clinical results at five weeks after surgery, especially shown in the significantly better results of the used pain scores. Despite visually inconspicuous gait in both operated groups, the sensitive parameters of the gait analysis showed persistent large deficits. A significant improvement was appreciated six months after surgery, but the level of the healthy probands was not attained at this time. There were no significant differences of any gait parameter between the groups MIS and KONV at any time of examination.

Conclusion: Advantages of minimally invasive approaches in total hip replacement which can be found a short time after surgery (like less blood loss, less pain after operation, quicker beginning of mobilisation) were not found in this study 5 weeks later regarding functional outcomes. Persistence of functional deficits, caused by damage to the arthromuscular complex, which occur during the process of the development of the arthrosis, need much more time to recover after surgery, independent of the used approach.