Hydroxyapatite-coated compaction short stem represents a characteristic pattern of peri-prosthetic bone remodelling after total hip arthroplasty

Abstract

Purpose: We aimed to investigate the differences in peri-prosthetic bone remodelling between the full hydroxyapatite (HA)-collared compaction short stem and the short tapered-wedge stem.Methods: This retrospective cohort study enrolled 159 consecutive patients (159 joints) undergoing total hip arthroplasty (THA) using the full HA compaction short (n=64) and short tapered-wedge (n=95) stems. Body mass index (BMI), peri-prosthetic bone mineral density (BMD), and clinical factors, including the Japanese Orthopaedic Association score and the University of California Los Angeles (UCLA) activity score, were assessed and compared.Results: Both groups showed similar peri-prosthetic BMD changes. Peri-prosthetic BMD was almost maintained in the distal femur and Gruen zone 6 with both type of stems, but signi cant BMD loss was found in zones 1 and 7 in both groups and in zone 2 of the full HA compaction stem group. Signi cant positive correlations were found between the proximal femoral BMD changes and the UCLA score in the tapered-wedge stem group but not between BMD changes and clinical factors in the full HA compaction stem group. Femoral bone shape affected the peri-prosthetic BMD changes in the tapered-wedge stem but not in the full HA compaction group. The stem collar of the full HA compaction stem did not affect peri-prosthetic BMD, but unique bone remodelling in the calcar region was observed in 27.6% cases. Conclusion: Peri-prosthetic bone remodelling remained unaffected by clinical and radiographic factorsafter THA with the new short full HA compaction stem. Therefore, the new stem may be useful in a variety of cases.

Peri-prosthetic bone remodeling of hydroxyapatite-coated compaction short stem was not affected by stem alignment

“…We demonstrated that the mean value of stem valgus was significantly higher in the stem collar-calcar contact group than in the non-contact group, and the result can explain the reason for stem alignment changes to valgus during bone compaction in the stem collar-calcar contact group. However, we previously reported a relationship between the stem collar and periprosthetic BMD changes, and no differences was found in any of the Gruen zones between the stem collar-calcar contact and non-contact groups [ 5 ]. These findings supported our current result that stem alignment does not affect peri-prosthetic bone remodeling in the HA compaction stem.…”

“…Previous studies have investigated the influence of the proximal femoral canal shape on post-operative BMD changes in the femur [ 5 , 22 ]. The pre-operative femoral canal’s morphology did not affect the BMD at two years post-operatively around the Zweymüller-type stem [ 22 ].…”

“…Recently, we reported that peri-prosthetic BMD changes was similar in full HA-coated compaction short stems and short tapered-wedge stems [ 5 ]. We further demonstrated that age, body mass index (BMI), and daily activity did not affect proximal femoral BMD changes in both stem types, and femoral bone shape affected the BMD changes in the tapered-wedge stem but not in the full HA compaction stem [ 5 ]. The contact force is dependent on subject-specific geometry and that specificity influences stress distribution in the peri-prosthetic bone after THA [ 6 , 7 ].…”