Table 4.

Predictive factors for conversion to THA, radiographic progression of OA, or Merle d’Aubigné-Postel score less than 15 points with corresponding hazard ratios

Category	Parameter	Crude hazard ratio	p value (hazard ratio)	Adjusted hazard ratio	p value (adjusted hazard ratio)
Demographic factors	Age > 30 years	3.3 (2.5–4.1)	< 0.001	4.1 (3.3–4.9)	< 0.001
	Preoperative Merle d’Aubigne-Postel score < 15	3.3 (2.5–4.1)	< 0.001	4.7 (3.9–5.6)	< 0.001
	Preoperative positive Trendelenburg sign	2.0 (1.5–2.6)	0.017	2.2 (1.6–2.9)	0.015
Preoperative radiographic factors	Nonspherical head	2.0 (1.4–2.5)	0.013	2.0 (1.5–2.6)	0.010
	Preoperative osteoarthritis ≥ Grade 1	5.8 (4.9–6.7)	< 0.001	3.7 (2.4–5.0)	0.042
	Severin > Grade 3	1.9 (1.3–2.6)	0.05	2.4 (1.6–3.3)	0.047
Postoperative factors related to surgical accuracy	Total femoral coverage of < 70% (undercoverage)	2.6 (1.8–3.4)	0.017	NA	–
	Total femoral coverage of > 83% (overcoverage)	2.5 (1.7–3.4)	0.031	NA	–
	Anterior femoral coverage of > 27% (overcoverage)	1.9 (1.3–2.5)	0.045	NA	–
	Posterior femoral coverage of < 36% (undercoverage)	1.9 (1.2–2.5)	0.045	NA	–
	Excessive acetabular anteversion*	2.2 (1.4–2.9)	0.043	6.0 (4.5–7.5)	0.019
	Acetabular retroversion†	3.3 (2.8–3.8)	0.013	3.7 (2.9–4.4)	< 0.001
	Extrusion index > 27% (undercoverage)	2.2 (1.6–2.8)	0.011	NA	–
	Acetabular index > 14° (undercoverage)	2.5 (1.7–3.3)	0.023	NA	–
	LCE < 22° (undercoverage)	2.2 (1.6–2.9)	0.013	2.2 (1.5–2.9)	0.022
	No offset correction in a nonspherical femoral head	2.4 (2.1–2.7)	0.003	2.8 (2.2–3.4)	< 0.001

Values expressed as mean with 95% confidence interval in parentheses; * defined as deficient anterior acetabular coverage (< 15%) and excessive acetabular posterior coverage (> 47%); †defined as excessive anterior acetabular coverage (> 27%) and deficient posterior acetabular coverage (< 36%) [30]; LCE = lateral center-edge angle; NA = not applicable.