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No medium-term advantage of electrochemical deposition of hydroxyapatite in cementless femoral stems. 5-year RSA and DXA results from a randomized controlled trial.

Flatøy B, Röhrl SM, Bøe B, Nordsletten L - Acta Orthop (2015)

Bottom Line: Bone resorption occurred mainly during the first year, and subsequently decreased to a rate close to what is seen in normal ageing.The greatest total decrease occurred in Gruen zones 1 and 7, similar in the groups at 5 years.Thus, at this point, Bonemaster appears to be safe.

View Article: PubMed Central - PubMed

Affiliation: a Department of Orthopedic Surgery , Oslo University Hospital Ullevål , Oslo , Norway .

ABSTRACT

Background and purpose: Hydroxyapatite has been used for a long time as an adjunct to enhance cementless fixation. The benefit of this is still debated, but new methods of hydroxyapatite deposition have emerged, offering possible gains. In order to investigate this further, we compared the migration pattern and periprosthetic bone remodeling in a cementless femoral stem with either electrochemically deposited hydroxyapatite-called Bonemaster (BM)-or a conventional plasma-sprayed hydroxyapatite (HA) coating.

Patients and methods: 55 hips were randomized to either BM or HA cementless femoral stems. Patients were followed with radiostereometry (RSA), dual-energy X-ray absorptiometry (DXA), radiographic measurements, and hip questionnaires for 5 years.

Results: For both stems, migration occurred mainly as subsidence and retroversion during the first 3 months. The BM group had a higher retroversion rate of 0.17° per month during this period, as compared to 0.06° per month for the HA group (p = 0.006). Thereafter, there was almost no movement in any direction for both stem types. Bone resorption occurred mainly during the first year, and subsequently decreased to a rate close to what is seen in normal ageing. The greatest total decrease occurred in Gruen zones 1 and 7, similar in the groups at 5 years. There was a slightly higher resorption rate in Gruen zone 7 from 2 to 5 years in the BM group (1.3% per year; p = 0.04), but in a magnitude that would scarcely affect stem stability or survival.

Interpretation: There were no clinically relevant differences between the 2 stems regarding stability or periprosthetic bone loss at 5 years. Electrochemically deposited HA does not appear to affect fixation or bone remodeling when compared to conventional plasma spraying at 5 years. Thus, at this point, Bonemaster appears to be safe.

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Related in: MedlinePlus

The postoperative, 3-month and 5-year radiographs from the patient that was excluded from RSA analysis. The stem seems to be undersized in the postoperative image. There is macroscopic subsidence from postoperatively to 3 months, but no visible changes thereafter, consistent with the RSA data.
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Figure 0002: The postoperative, 3-month and 5-year radiographs from the patient that was excluded from RSA analysis. The stem seems to be undersized in the postoperative image. There is macroscopic subsidence from postoperatively to 3 months, but no visible changes thereafter, consistent with the RSA data.

Mentions: 55 hips in 50 patients were included. 1 patient was excluded due to a periprosthetic fracture after 6 weeks, and 3 patients were lost to follow-up due to concomitant disease or withdrawal from the trial, leaving 29 BM and 22 HA hips at 5 years. 2 hips in the BM group underwent cup revision, but remained in the trial. 1 patient, who contracted early postoperative infection and was operated at 5 weeks with soft tissue revision and exchange of the femoral head, also remained in the trial. 1 stem in the BM group subsided excessively (10.4 mm) during the first 3 months. However, it did not subside any further after that; nor was there movement in any other direction. This stem appeared to be undersized when we were evaluating postoperative radiographs, and it was excluded from the overall subsidence rate calculation since we considered it to be a confounding factor (Figure 2). This patient was also excluded at the 2-year analysis, due to a condition number (CN) expressing the quality of marker segments above the threshold accepted at that time (CN > 100).


No medium-term advantage of electrochemical deposition of hydroxyapatite in cementless femoral stems. 5-year RSA and DXA results from a randomized controlled trial.

Flatøy B, Röhrl SM, Bøe B, Nordsletten L - Acta Orthop (2015)

The postoperative, 3-month and 5-year radiographs from the patient that was excluded from RSA analysis. The stem seems to be undersized in the postoperative image. There is macroscopic subsidence from postoperatively to 3 months, but no visible changes thereafter, consistent with the RSA data.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940590&req=5

Figure 0002: The postoperative, 3-month and 5-year radiographs from the patient that was excluded from RSA analysis. The stem seems to be undersized in the postoperative image. There is macroscopic subsidence from postoperatively to 3 months, but no visible changes thereafter, consistent with the RSA data.
Mentions: 55 hips in 50 patients were included. 1 patient was excluded due to a periprosthetic fracture after 6 weeks, and 3 patients were lost to follow-up due to concomitant disease or withdrawal from the trial, leaving 29 BM and 22 HA hips at 5 years. 2 hips in the BM group underwent cup revision, but remained in the trial. 1 patient, who contracted early postoperative infection and was operated at 5 weeks with soft tissue revision and exchange of the femoral head, also remained in the trial. 1 stem in the BM group subsided excessively (10.4 mm) during the first 3 months. However, it did not subside any further after that; nor was there movement in any other direction. This stem appeared to be undersized when we were evaluating postoperative radiographs, and it was excluded from the overall subsidence rate calculation since we considered it to be a confounding factor (Figure 2). This patient was also excluded at the 2-year analysis, due to a condition number (CN) expressing the quality of marker segments above the threshold accepted at that time (CN > 100).

Bottom Line: Bone resorption occurred mainly during the first year, and subsequently decreased to a rate close to what is seen in normal ageing.The greatest total decrease occurred in Gruen zones 1 and 7, similar in the groups at 5 years.Thus, at this point, Bonemaster appears to be safe.

View Article: PubMed Central - PubMed

Affiliation: a Department of Orthopedic Surgery , Oslo University Hospital Ullevål , Oslo , Norway .

ABSTRACT

Background and purpose: Hydroxyapatite has been used for a long time as an adjunct to enhance cementless fixation. The benefit of this is still debated, but new methods of hydroxyapatite deposition have emerged, offering possible gains. In order to investigate this further, we compared the migration pattern and periprosthetic bone remodeling in a cementless femoral stem with either electrochemically deposited hydroxyapatite-called Bonemaster (BM)-or a conventional plasma-sprayed hydroxyapatite (HA) coating.

Patients and methods: 55 hips were randomized to either BM or HA cementless femoral stems. Patients were followed with radiostereometry (RSA), dual-energy X-ray absorptiometry (DXA), radiographic measurements, and hip questionnaires for 5 years.

Results: For both stems, migration occurred mainly as subsidence and retroversion during the first 3 months. The BM group had a higher retroversion rate of 0.17° per month during this period, as compared to 0.06° per month for the HA group (p = 0.006). Thereafter, there was almost no movement in any direction for both stem types. Bone resorption occurred mainly during the first year, and subsequently decreased to a rate close to what is seen in normal ageing. The greatest total decrease occurred in Gruen zones 1 and 7, similar in the groups at 5 years. There was a slightly higher resorption rate in Gruen zone 7 from 2 to 5 years in the BM group (1.3% per year; p = 0.04), but in a magnitude that would scarcely affect stem stability or survival.

Interpretation: There were no clinically relevant differences between the 2 stems regarding stability or periprosthetic bone loss at 5 years. Electrochemically deposited HA does not appear to affect fixation or bone remodeling when compared to conventional plasma spraying at 5 years. Thus, at this point, Bonemaster appears to be safe.

Show MeSH
Related in: MedlinePlus