Research Article: Low BMD affects initial stability and delays stem osseointegration in cementless total hip arthroplasty in women

Date Published: April 24, 2012

Publisher: Informa Healthcare

Author(s): Hannu T Aro, Jessica J Alm, Niko Moritz, Tatu J Mäkinen, Petteri Lankinen.


Immediate implant stability is a key factor for success in cementless total hip arthroplasty (THA). Low bone mineral density (BMD) and age-related geometric changes of the proximal femur may jeopardize initial stability and osseointegration. We compared migration of hydroxyapatite-coated femoral stems in women with or without low systemic BMD.

61 female patients with hip osteoarthritis were treated with cementless THA with anatomically designed hydroxyapatite-coated femoral stems and ceramic-ceramic bearing surfaces (ABG-II). Of the 39 eligible patients between the ages of 41 and 78 years, 12 had normal systemic BMD and 27 had osteopenia or osteoporosis. According to the Dorr classification, 21 had type A bone and 18 had type B. Translational and rotational migration of the stems was evaluated with radiostereometric analysis (RSA) up to 2 years after surgery.

Patients with low systemic BMD showed higher subsidence of the femoral stem during the first 3 months after surgery than did those with normal BMD (difference = 0.6, 95% CI: 0.1–1.1; p = 0.03). Low systemic BMD (odds ratio (OR) = 0.1, CI: 0.006–1.0; p = 0.02), low local hip BMD (OR = 0.3, CI: 0.1–0.7; p = 0.005) and ageing (OR = 1.1, CI: 1.0–1.2; p = 0.02) were risk factors for delayed translational stability. Ageing and low canal flare index were risk factors for delayed rotational stabilization (OR = 3, CI: 1.1–9; p = 0.04 and OR = 1.1, CI: 1.0–1.2; p = 0.02, respectively). Harris hip score and WOMAC score were similar in patients with normal systemic BMD and low systemic BMD.

Low BMD, changes in intraosseous dimensions of the proximal femur, and ageing adversely affected initial stability and delayed osseointegration of cementless stems in women.

Partial Text

Osteoporosis may have 4 major potential complications in cementless THA: increased migration and subsequent loss of the optimal position of the stem, delayed osseointegration of the stem due to increased migration, an increased risk of periprosthetic fracture, and a risk of late loosening due to mechanical failure of ingrown trabecular bone. Our study shows that low systemic BMD, geometric changes in the proximal femur, and ageing may indeed increase initial migration and delay osseointegration of cementless femoral stems.