The Migration Pattern of a Cementless Hydroxyapatite-Coated Titanium Stem under Immediate Full Weight-Bearing-A Randomized Controlled Trial Using Model-Based RSA

Migration Characteristics of a Proximally Coated Collarless Femoral Stem: A Prospective 2-Year Radiostereometric Analysis Study

Background

Collared femoral stems have been considered to reduce the risk of early subsidence over collarless stems. However, with advances in material technology, new surface treatments have been introduced into cementless stem design to enhance primary fixation and long-term stability. This study aims to analyze the early migration behaviors of a proximally coated collarless femoral stem and cementless acetabular component and compare the outcomes with commercially available cementless stems and acetabular cups.

Methods

A total of 24 patients (25 hips) undergoing total hip arthroplasty were recruited and followed up for 2 years. All patients received a Masterloc femoral stem (Medacta International SA, Castel San Pietro, Switzerland) and an Mpact acetabular component (Medacta International SA, Castel San Pietro, Switzerland) with tantalum beads embedded during the operation. Radiographs for radiostereometric analysis were taken immediately postsurgery, 6-months, 1-year, and 2-years postoperatively.

Results

The median condition number for this study was 59. The median stem subsidence was -0.08 mm (-2.47 to 0.40) at 2 years. The median cup subsidence was -0.03 mm (-0.38 to 0.57) at 2 years. The migration of the Masterloc stem was less than that of other cementless collarless, as well as collared stems, as reported in literature.

Conclusions

This study has demonstrated the high stability and fixation provided with the use of a collarless cementless stem. The subsidence seen in both this cementless femoral stem and acetabular cup at 2 years postoperative was below the range reported in literature for cementless collarless and collared stems.

Mid-Term Migration Behavior of an Uncemented Proximally Anchored Straight Stem-A Retrospective EBRA Migration Analysis

BACKGROUND

Aseptic loosening is one of the most-common causes of the failure of cementless stems. Einzel Bild Röntgen Analyse-Femoral Component Analysis (EBRA-FCA) allows the diagnosis of stem migration, which can be considered a factor in predicting implant survival. The current study aimed to present the migration behavior of a tapered proximally anchored straight stem.

METHODS

This retrospective study reviewed all consecutive patients who received a cementless CBC straight stem (Mathys AG, Bettlach, Switzerland) between 2005 and 2019. We analyzed the migration pattern using the EBRA-FCA software and reviewed their medical histories. In addition, periprosthetic radiolucency was rated according to the Gruen zones and femoral configuration according to Dorr.

RESULTS

A total of 333 stems in 332 patients (female 191; male 141) met our inclusion criteria. The mean age at surgery was 63 (range 21-87) years. Migration analysis by EBRA-FCA showed a mean subsidence of 1.6 mm at final follow-up at 96 months with a maximum noted mean subsidence of 2.0 mm at 72 and 84 months. Dorr Type A showed a tendency of less subsidence than did Dorr Type B and was statistically significant at 6 (p = 0.0396) and 72 months (p = 0.0127). The body mass index (BMI) and increased subsidence were not found to correlate (p > 0.05). For this cohort, the overall femoral revision-free rate was 95.2% and the revision-free rate for aseptic loosening was 99.1%.

CONCLUSIONS

The results showed migration behavior in cementless stems with initial increased migration and subsequent secondary stabilization, suggesting an excellent long-term outcome. Stem migration of this tapered proximally anchored stem might be lower in Dorr Type A than in Dorr Type B femurs without being statistically significant at all time points.

The effects of full weight-bearing mobilization on clinical outcomes and subsidence in cemented and uncemented hemiarthroplasty in osteoporotic patients: A retrospective single-center study

BACKGROUND

Early full weight-bearing mobilization is controversial in osteoporotic patients who have undergone uncemented hemiarthroplasty (UCH).

OBJECTIVES

The aim of the study was to compare the results of early full weight-bearing mobilization in CH and uncemented hemiarthroplasty (UCH). The effect of subsidence on the results was also evaluated.

METHODS

Fifty-nine patients who underwent CH and UCH were evaluated. The mean age was 79.8 years (10 females, 15 males) for CH and 75.5 years (10 females, 24 males) for UCH. All patients started immediate full weight-bearing mobilization and weight-bearing exercises.

RESULTS

There was no difference between the groups according to the Harris Hip Score. Both groups were evaluated in subgroups according to whether there is varus in the femoral stem. There was no difference between subgroups according to the Harris Hip Score. The femoral subsidence was not determined in CH group. In the UCH group, the subsidence was 1.13 ± 1.03 mm in varus femoral stem subgroup and 0.81 ± 0.85 mm in without femoral stem varus subgroup. There was no difference in subsidence between femoral stem with varus and without varus. The subsidence did not affect the Harris Hip Score.

CONCLUSION

Full weight-bearing mobilization could be safely preferred in UCH, as in CH. Femoral stem varus below 5 degrees does not affect the results and subsidence.