Bone quality and mesenchymal stromal cell capacity in total hip replacement: Significance for stem osseointegration measured by radiostereometric analysis




Alm Jessica J

PublisherUniversity of Turku

TURKU

2016

ISBN 978-951-29-6579-3

ISBN 978-951-29-6580-9

http://urn.fi/URN:ISBN:978-951-29-6580-9



Immediate implant stability is a key factor for success in cementless total hip arthroplasty (THA). Cementless techniques were originally designed for middle-aged patients with normal bone structure and healing capacity, but indications have expanded to also include elderly patients. Poor local bone quality, as a result of osteoporosis (OP), and age-related geometric changes of the proximal femur, may jeopardize initial implant stability and lead to increased migration of the implant components thereby compromising biological fixation and osseointegration. Mesenchymal stromal cells (MSCs) are essential in the process of osseointegration. Age-related dysfunction of MSCs is suggested to be a main contributory factor in altered bone repair with aging and therefore may influence osseointegration. The hypothesis of this prospective clinical study was that preoperative bone quality and MSC capacity dictate stability and osseointegration of femoral stems in cementless THA, especially in women after menopause. 

A total of 61 consecutive women (age <80 yrs) scheduled for cementless THA for primary hip osteoarthritis (OA) were screened for undiagnosed primary or secondary OP, vitamin D insufficiency and other metabolic bone diseases. Prior to THA, patients underwent aspiration of iliac crest bone marrow for analysis of MSC capacity using optimized isolation and culturing protocols. All patients received a cementless total hip implant with an anatomically designed hydroxyapatite (HA) coated femoral stem and ceramic-ceramic bearings. Per-operative biopsy of the intertrochanteric bone was taken for ex vivo analysis of the local cancellous bone quality using micro-CT imaging and biomechanical testing. After surgery, stem migration and osseointegration was monitored for two years using radiostereometric analysis. 

The majority of women with hip OA was osteopenic or osteoporotic. These conditions were associated with increased periprosthetic bone loss in the proximal femur and impaired initial stability and delayed osseointegration of the femoral stem. Altered intraosseous dimensions of the proximal femur, as well as aging, also had adverse effects on initial stem stability and were associated with delayed osseointegration. Local bone mineral density of the operated hip and the quality of intertrochanteric cancellous bone had less influence than expected on implant migration. The THA females showed differences in the osteogenic properties of their MSCs. Patients with MSCs of low in vitro osteogenic capacity displayed increased stem subsidence after the initial 3 months settling period and thereby delayed osseointegration. 

The results suggest that decreased skeletal health, such as low systemic BMD and decreased osteogenic properties of bone marrow MSCs, has major influence on early stability and osseointegration of cementless hip prostheses in female patients.



Last updated on 2024-03-12 at 13:17