TABLE V.

Dislocation Risk After Primary THA Based on Non-Modifiable Patient Factors and Modifiable Operative Decisions^*

	Direct Anterior Approach					Lateral Approach					Posterior Approach
	≥36-mm Head		≤32-mm Head		Dual Mobil.	≥36-mm Head		≤32-mm Head		Dual Mobil.	≥36-mm Head		≤32-mm Head		Dual Mobil.
	Stand. Liner	Elev. Liner	Stand. Liner	Elev. Liner		Stand. Liner	Elev. Liner	Stand. Liner	Elev. Liner		Stand. Liner	Elev. Liner	Stand. Liner	Elev. Liner
No. of THAs	2159	0	726	2	8	2971	40	4161	523	66	5645	132	4237	773	280
HR for dislocation risk	0.13	—	0.35	—	—	0.33	—	0.57	0.41	0.48	0.71	0.28	1.00 (ref.)	0.55	0.48
Absolute risk at 1 year (%)
Worst host†	1.8	—	4.7	—	—	4.4	—	7.5	5.5	6.3	9.3	3.8	12.8	7.2	6.3
Best host‡	0.3	—	0.7	—	—	0.6	—	1.1	0.8	0.9	1.4	0.6	2.0	1.1	0.9
Absolute risk at 5 years (%)
Worst host†	2.8	—	7.2	—	—	6.7	—	11.4	8.3	9.6	14.0	5.9	19.1	11.0	9.6
Best host‡	0.4	—	1.1	—	—	1.0	—	1.7	1.2	1.4	2.2	0.9	3.0	1.7	1.4

^*HR = hazard ratio (reference set to 1.00 individually for highest-risk group). Dashes represent combinations with an insufficient sample size to calculate reliable HRs or absolute risks.

^†Worst possible host: female, age = 65 years, body mass index = 35 kg/m², osteonecrosis indication for THA, neurologic disease present, major spine disease present, and prior major spine surgery.

^‡Best possible host: male, age = 75 years, body mass index = 25 kg/m², osteoarthritis indication for THA, neurologic disease absent, spine disease absent, and no prior spine surgery.