CORR Insights®: What Factors Are Associated With Neck Fracture in One Commonly Used Bimodular THA Design? A Multicenter Nationwide Study in Slovenia

摘要

In the current study, Kovač and colleagues [ ] found an increased risk of THA implant fracture when orthopaedic surgeons use modular necks and concluded that these implants should not be used. I concur with their conclusion, and believe it is fair to ask why this innovation ever was used at all. My group and I used a modular neck in my own implant design in 1982 because we felt it would offer superiority in restoration of hip length and offset. I was warned then by my mentor Dr. Chit Ranawat that the more moving parts added to a design, the greater the likelihood of one of those parts failing. Thanks to that advice, I abandoned modular necks in my subsequent designs. I also learned through experience that good surgery is superior to implant modifications in terms of compensating for anatomic variations. After using computer-assisted navigation for complex THAs for 17 years, I learned that most of the femoral anteversion in dysplastic hips is caused by antetorsion of the head (head-neck angle). And with a neck cut at 10 mm above the lesser trochanter, I have never observed stem anteversion greater than 30°. Because I use cemented stems in some hips, and combined anteversion (lower anteversion in cup) in all, I have never used modularity for dysplastic hips.