Abstract
Purpose
Aim of the study was to assess difficulties and adverse effects in more than 400 CAS hip replacements using a short modular femoral stem to assess their incidence and to determine if this surgical procedure has to be considered as an high demanding surgical technique.
Materials and Methods
Since 1998, 511 computer assisted hip replacements using a short modular stem were performed in our department. 403 implants were followed for at least 6 months postoperatively and included in the study. All the cases were divided into 3 series according to when the surgery had been performed to consider the evolution of the navigation systems and the surgeons familiarity with this improvement (group A: 1998–2003, group B: 2004–2008 and group C: 2009–2014). All intra-operative problems (difficulties that required no operative intervention to resolve or without any conseguence on the navigation process), intra-operative obstacles (difficulties that required operative intervention or that caused a failure of the navigation process) and complications (intra-operative injuries and all the problems following in the first 6 months post-operatively) were registered. Adverse facts not directly caused by the surgical but derived by other conditions were excluded from the study.
Results
There were no differences in number of total problems/complications among the 3 groups. Obstacles were statistically higher in group A where we observed a higher incidence of navigation failures in association both to the first software versions and to a minor surgical experience. We did not register any statistically significant difference in the number of septic THR (complication) and incidence of superficial pin site infections (complication). One case in group A had to be successfully revised because a proven metal allergy in group B. We registered 8 cases of proximal femur fractures with different distribution among the 3 groups. In 1 case in group A we experienced an acetabular fracture during cup impaction managed with rest. No abnormal intra operative or post operative bleeding was registered because of the surgical technique with no statistical difference in clinical evident DVT among the 3 groups. Surgical time was longer in group A with a statistical significant difference in group A compared both to group B and C.
Conclusion
In this study the authors registered both a higher rate in navigation failure and longer surgical time in the first cases even because of less advance navigation systems and lower experience with CAS. However in a series of more than 400 CAS THRs using a modular short femoral stem the authors could demonstrate no increased rate of complications compared to traditional techniques.
