Osteoarthritis of the hip joint in elderly patients is most commonly atrophic, with low parameters of acetabular dysplasia and possible involvement of osteoporosis.
As elderly patients with hip osteoarthritis aged, acetabular dysplasia parameters decreased (Sharp's angle, acetabular roof obliquity angle, and acetabular head index) and the incidence of the atrophic type increased. Vertebral body fracture was more frequent in the atrophic type, suggesting the involvement of osteoporosis at the onset of hip osteoarthritis.


BACKGROUND
Osteoarthritis (OA) is associated with increased bone formation at a local site. However, excessive bone resorption has also been found to occur in the early stages of OA. Osteoporosis may be involved in the onset of OA in elderly patients. We conducted a cross-sectional radiographic study of patients with hip OA and examined the association between age and factors of acetabular dysplasia (Sharp's angle, acetabular roof obliquity angle, and acetabular head index) as well as the osteoblastic response to determine the potential involvement of osteoporosis.


METHODS
This study included 366 patients (58 men, 308 women) who had undergone total hip arthroplasty for the diagnosis of hip OA. We measured the parameters of acetabular dysplasia using preoperative frontal X-ray images and evaluated each patient according to Bombelli classification of OA (hypertrophic, normotrophic, or atrophic type).


RESULTS
As the patients aged, the parameters of acetabular dysplasia decreased. The incidence of the atrophic type of OA was significantly higher in older patients. Vertebral body fractures were more frequent in the atrophic type than in the other types. Additionally, the index of acetabular dysplasia was lower in the atrophic type. By contrast, the hypertrophic type was present in relatively younger patients and was associated with an increased index of acetabular dysplasia.


CONCLUSIONS
In elderly patients with hip OA, the parameters of acetabular dysplasia decreased and the incidence of the atrophic type increased as the patients aged. The frequency of vertebral body fracture was high in patients with the atrophic type, suggesting the involvement of osteoporosis in the onset of hip OA.
Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. ishidou@m2.kufm.kagoshima-u.ac.jp.
Yasuhiro
Y
Ishidou
Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan.
Kanehiro
K
Matsuyama
Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan.
Daisuke
D
Sakuma
The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
Takao
T
Setoguchi
Department of Orthopedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
Satoshi
S
Nagano
Department of Orthopedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
Ichiro
I
Kawamura
Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan.
Shingo
S
Maeda
Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan.|The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.|Department of Orthopedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
Setsuro
S
Komiya
D000077:Acetabulum / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001178:Arthroplasty / Q000379:methods; D001284:Atrophy; D001848:Bone Diseases, Developmental / Q000000981:diagnostic imaging / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D010024:Osteoporosis / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D012307:Risk Factors; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology
Acetabular dysplasia; Aging; Osteoarthritis; Osteoporosis