Clinical and radiographic outcomes of primary total hip arthroplasty with the Revelation Hip System using density mapping

概要

Cementless femoral stems in total hip arthroplasty (THA) have been widely used in the previous
decades and have shown excellent long-term survivorship and functional outcomes. Various types
of cementless femoral stems, including single wedge, double wedge, tapered, cylindrical fully
coated, modular, and anatomic stems, have been developed and used in a variety of applications.
Each stem design has a different geometry and place to be fixed in the femur, indicating that the
stem concept and fitting of cementless stem into the medullary cavity is important for stable
fixation. However, the fixation to the medullary cavity, which is different from the concept, may
cause stem malalignment and subsidence, resulting in thigh pain and poor postoperative outcomes.
The Revelation Hip System is a cementless stem with a lateral flare concept. Stable fixation is
achieved by fitting the stem to the medullary cavity of the proximal lateral femoral cortex. Patients
who have undergone total hip arthroplasty using the Revelation Hip System show good
postoperative clinical and radiographic outcomes. However, to the best of our knowledge, no
study has reported the relationship between stem fitting and clinical or radiological outcomes after
the surgery. In the present study, we investigated the relationship between stem fitting and clinical
or radiological outcomes after total hip arthroplasty using the Revelation Hip System. In this study,
28 hips of 26 patients who were treated with the Revelation Hip System for osteoarthritis,
osteonecrosis of the femoral head, rheumatoid arthritis, and rapidly destructive coxarthropathy
and were followed up for >5 y were enrolled. These patients were divided into two groups,
including the rest fit group (11 hips, group R) and the control group (17 hips, group C), according
to the results of the density mapping analysis. In group R, the lateral side of the stem fit on the
medullary cavity of the proximal lateral femoral cortex, while in group C, the lateral side of the
stem did not fit. Radiographic results showed no significant differences between the groups in
terms of stem alignment, subsidence, and stress shielding around the cup. The incidence of stress
shielding around the stem in zone 7 was not significant but tended to be higher in group R than
in group C (p = 0.052). Clinical outcomes showed no significant differences between group R and
group C in terms of the Harris hip score, the Japanese Orthopaedic Association (JOA) score, and
the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) total score.
However, pain complaints that were assessed by patient-reported outcomes using the 36-Item
Short Form Health Survey (SF-36) bodily pain and vitality subscales and the JHEQ pain subscale
were significantly higher in group R than in group C at the final follow-up. These results suggest
that some patients had pain complaint even if the stems were inserted as per the concept after
THA with the Revelation Hip System. ...