Early diagnosis and targeted intervention based on the pathogenesis of rapidly progressive osteoarthritis of the hip

Table 2 Key findings for differential diagnosis of rapidly progressive osteoarthritis of the hip in the early stage

Findings	RPOH	OA	ON	SIF
Pain	Acute and severe, nocturnal	Slow onset, at exertion	At rest and constant	Acute, at rest and exertion
ROM	Normal passive ROM and painful active, weight-bearing ROM	Restricted ROM, Joint stiffness	Joint stiffness less common	Joint stiffness less common
X-ray	Rapid joint space narrowing, lack of osteophytes, and scant/minimal subchondral sclerosis	Gradual joint space narrowing, osteophyte formation, and subchondral sclerosis	Femoral head lucency or sclerosis, and a crescent sign within the femoral head	Fracture on the subchondral area in the femoral head, followed by joint space narrowing
	Femoral head destruction after joint space narrowing
MRI	T1 a subchondral area of low signal intensity	T1: Diffuse low-intensity lesions	T1: Serpentine low-intensity lesions	T1 a band-like hypointense lesion surrounded by a diffuse bone marrow edema pattern
	T2 inhomogeneous high intensity	T2: Diffuse high-intensity lesions	T2: Serpentine high-intensity lesions	T2 a linear pattern of high signal intensity
	Location: The superolateral portion of the femoral head	Location: Weight-bearing portion of femoral head	Location: Any portion and orientation random	Location: Adjacent to the articular surface of the femoral head

RPOH: Rapidly progressive osteoarthritis of the hip; OA: Osteoarthritis of the hip; ON: Osteonecrosis of the femoral head; SIF: Subchondral insufficiency fracture of the femoral head; ROM: Range of hip joint motion; MRI: Magnetic resonance imaging.