German researchers using a modified
straight cementless hip stem with proximal-medial curvature
total hip arthroplasty in cases with narrow femoral cavities
reported high stem survivorship and outcomes similar to those of a straight
tapered hip design.
say narrow femoral bone conditions can be
challenging, Steffen Kohler, MD, said during his presentation at the
SICOT XXV Triennial World Congress 2011. The small shape
of stem designs may change outcomes dramatically.
Kohler and colleagues conducted a retrospective study of 123 total hip
arthroplasties performed with a modified straight cementless proximal hip stem
for narrow femora and compared the results to studies using a straight tapered
stem. Of the patients, 100 hips in 92 patients were available for follow-up
between February 1991 and November 1996. The learning curve was fully included.
The patients had an average age of 57 years and were followed for a mean of 148
months. One-third of the patients had a preoperative diagnosis of
dysplasia, one-third of patients had primary
osteoarthritis and one-sixth of patients suffered aseptic
necrosis or other diagnosis, according to Kohler.
One patient died of pulmonary embolism on the second postoperative day.
The investigators found that femur fractures occurred within the acceptable
range, according to Kohler. The team measured the dislocation rate at 1%,
which is also the standard range and also far and away what is reported
from other research, Kohler said. After the study was finished, one
patient was treated for late infection and underwent a staged revision at 16.5
A patient is shown at 187 months (L) follow-up and
179 months (R) follow-up. It was the longest follow-up in this series.
Images: Kohler S
The investigators found that the Harris Hip score improved from 28
points at baseline to 93 points at the time of last follow-up. The mean Merle
DAubigné score was 16.7 points at last follow-up, Kohler said.
The Kaplan-Meier survival rate of the stem was 99%, with investigators
finding one loose stem. They recorded high failure rates of the acetabular
components of the modified device. However, Kohler noted that cup loosening and
polyethylene wear did not damage the bone-implant interface of the cementless
stem used in their study.
These findings were not different to the published mid- and
long-term results of the corresponding cementless straight hip stem
design, Kohler and his colleagues wrote in their study abstract.
by Renee Blisard
- Kohler S. Results of cementless THA in indications for narrow
femoral cavities. Presented at the SICOT XXV Triennial World Congress 2011.
Sept. 6-9. Prague.
- Steffen Kohler, MD, can be reached at HELIOS-Klinik,
Fachkrankenhaus für Orthopädie, Barbarastraße 11, 99752,
Bleicherode, Germany; (03 63 38) 65-0; email:
- Disclosure: Kohler is a paid consultant for Aesculap AG