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Increased migration of uncemented acetabular cups in female total hip arthroplasty patients with low systemic bone mineral density. A 2-year RSA and 8-year radiographic follow-up study of 34 patients.

Finnilä S, Moritz N, SvedströM E, Alm JJ, Aro HT - Acta Orthop (2015)

Bottom Line: Patients with normal BMD did not show a statistically significant cup migration after the settling period of 3 months, while patients with low BMD had a continuous proximal migration between 3 and 12 months (p = 0.03).These differences in cup migration persisted at 24 months.Based on the perceived risk of cup revision, 14 of the 24 cases were "at risk" (proximal translation of 0.2 to 1.0 mm) in the low-BMD group and 2 of the 10 cases were "at risk" in the normal-BMD group (odds ratio (OR) = 8.0, 95% CI: 1.3-48).

View Article: PubMed Central - PubMed

Affiliation: a Orthopaedic Research Unit , Turku University Hospital and University of Turku.

ABSTRACT

Background and purpose: Low bone mineral density (BMD) may jeopardize the initial component stability and delay osseointegration of uncemented acetabular cups in total hip arthroplasty (THA). We measured the migration of uncemented cups in women with low or normal BMD.

Patients and methods: We used radiostereometric analysis (RSA) to measure the migration of hydroxyapatite-coated titanium alloy cups with alumina-on-alumina bearings in THA of 34 female patients with a median age of 64 (41-78) years. 10 patients had normal BMD and 24 patients had low systemic BMD (T-score ≤ -1) based on dual-energy X-ray absorptiometry (DXA). Cup migration was followed with RSA for 2 years. Radiographic follow-up was done at a median of 8 (2-10) years.

Results: Patients with normal BMD did not show a statistically significant cup migration after the settling period of 3 months, while patients with low BMD had a continuous proximal migration between 3 and 12 months (p = 0.03). These differences in cup migration persisted at 24 months. Based on the perceived risk of cup revision, 14 of the 24 cases were "at risk" (proximal translation of 0.2 to 1.0 mm) in the low-BMD group and 2 of the 10 cases were "at risk" in the normal-BMD group (odds ratio (OR) = 8.0, 95% CI: 1.3-48). The radiographic follow-up showed no radiolucent lines or osteolysis. 2 cups have been revised for fractures of the ceramic bearings, but none for loosening.

Interpretation: Low BMD contributed to cup migration beyond the settling period of 3 months, but the migrating cups appeared to osseointegrate eventually.

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Related in: MedlinePlus

The proximal translation (mean ± SD) of the acetabular cups in patients with normal or low BMD during the first 24 months after surgery.
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Figure 0002: The proximal translation (mean ± SD) of the acetabular cups in patients with normal or low BMD during the first 24 months after surgery.

Mentions: The difference in proximal cup migration between the patients with normal BMD and those with low BMD appeared to progress after the settling period of 3 months (Figure 2 and 3). An extra analysis was therefore performed. Patients with low BMD had statistically significant proximal translation (paired-samples t-test, p = 0.03) between 3 and 12 months but not between 12 and 24 months (paired-samples t-test, p = 1.0). Patients in the normal-BMD group did not show statistically significant proximal migration at any time after 3 months (repeated-measures ANOVA, p = 0.9) as a sign of cup stability.


Increased migration of uncemented acetabular cups in female total hip arthroplasty patients with low systemic bone mineral density. A 2-year RSA and 8-year radiographic follow-up study of 34 patients.

Finnilä S, Moritz N, SvedströM E, Alm JJ, Aro HT - Acta Orthop (2015)

The proximal translation (mean ± SD) of the acetabular cups in patients with normal or low BMD during the first 24 months after surgery.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940591&req=5

Figure 0002: The proximal translation (mean ± SD) of the acetabular cups in patients with normal or low BMD during the first 24 months after surgery.
Mentions: The difference in proximal cup migration between the patients with normal BMD and those with low BMD appeared to progress after the settling period of 3 months (Figure 2 and 3). An extra analysis was therefore performed. Patients with low BMD had statistically significant proximal translation (paired-samples t-test, p = 0.03) between 3 and 12 months but not between 12 and 24 months (paired-samples t-test, p = 1.0). Patients in the normal-BMD group did not show statistically significant proximal migration at any time after 3 months (repeated-measures ANOVA, p = 0.9) as a sign of cup stability.

Bottom Line: Patients with normal BMD did not show a statistically significant cup migration after the settling period of 3 months, while patients with low BMD had a continuous proximal migration between 3 and 12 months (p = 0.03).These differences in cup migration persisted at 24 months.Based on the perceived risk of cup revision, 14 of the 24 cases were "at risk" (proximal translation of 0.2 to 1.0 mm) in the low-BMD group and 2 of the 10 cases were "at risk" in the normal-BMD group (odds ratio (OR) = 8.0, 95% CI: 1.3-48).

View Article: PubMed Central - PubMed

Affiliation: a Orthopaedic Research Unit , Turku University Hospital and University of Turku.

ABSTRACT

Background and purpose: Low bone mineral density (BMD) may jeopardize the initial component stability and delay osseointegration of uncemented acetabular cups in total hip arthroplasty (THA). We measured the migration of uncemented cups in women with low or normal BMD.

Patients and methods: We used radiostereometric analysis (RSA) to measure the migration of hydroxyapatite-coated titanium alloy cups with alumina-on-alumina bearings in THA of 34 female patients with a median age of 64 (41-78) years. 10 patients had normal BMD and 24 patients had low systemic BMD (T-score ≤ -1) based on dual-energy X-ray absorptiometry (DXA). Cup migration was followed with RSA for 2 years. Radiographic follow-up was done at a median of 8 (2-10) years.

Results: Patients with normal BMD did not show a statistically significant cup migration after the settling period of 3 months, while patients with low BMD had a continuous proximal migration between 3 and 12 months (p = 0.03). These differences in cup migration persisted at 24 months. Based on the perceived risk of cup revision, 14 of the 24 cases were "at risk" (proximal translation of 0.2 to 1.0 mm) in the low-BMD group and 2 of the 10 cases were "at risk" in the normal-BMD group (odds ratio (OR) = 8.0, 95% CI: 1.3-48). The radiographic follow-up showed no radiolucent lines or osteolysis. 2 cups have been revised for fractures of the ceramic bearings, but none for loosening.

Interpretation: Low BMD contributed to cup migration beyond the settling period of 3 months, but the migrating cups appeared to osseointegrate eventually.

Show MeSH
Related in: MedlinePlus