Patient-reported outcome after dislocation of primary total hip arthroplasties: a cross-sectional study derived from the Danish Hip Arthroplasty Register

Figures & data

Figure 1. Flowchart of the inclusion/exclusion process: selection process from DHR data retrieval to the return of questionnaires.

Table 1. Patient demographics. Values are percentage unless otherwise specified

	Invited		Returned, eligible
	Cases	Controls	Cases	Controls
	(n = 1,010)	(n = 2,008)	(n = 640)	(n = 1,422)
Age, mean (CI)	70 (69–70)	70 (69–70)	69 (68–69)	69 (69–70)
Female sex	64	64	60	64
Follow-up, years mean (range)	7.2 (4.8–9.7)	7.2 (4.8–9.7)	7.1 (4.8–9.7)	7.2 (4.8–9.7)
CCI 0	64	69	69	70
CCI 1–2	27	25	25	25
CCI > 2	9	6	7	5

Patient demographics for both all the invited patients and for the responders separately. The 2 groups were similar in age, sex, and length of follow-up from primary surgery to the date for the receipt of questionnaires. The case group had a minor shift towards higher CCI scores than the control group. Overall, the listed demographics for the responders were comparable to the invited cases and controls. CCI = Charlson Comorbidity Index.

Figure 3. HOOS domain scores presented as means with 95% CIs for all cases with dislocation, cases with dislocation and revision(s), and the control group. A score of 100 indicates no problems and 0 indicates extreme problems. We compared the control group with cases with dislocation (no revision) by multiple linear regression analysis adjusting for CCI and stated statistical significance for all 5 domains (p-value < 0.001).

Figure 4. Predicted HOOS QoL score after hip dislocation: graph illustrating the predicted HOOS QoL domain score as a function of time elapsed since the latest dislocation, irrespective of the number of dislocations per patient.

Table 2. HOOS results based on number of dislocations

Domain	1 dislocation (no revision) n mean (CI)	2 dislocations (no revision) n mean (CI)	> 2 dislocations (no revision) n mean (CI)	Dislocation(s) and 1 revision n mean (CI)	Dislocation(s) and > 1 revision n mean (CI)	Controls without any dislocation or revision n mean (CI)
Invited	459	160	125	197	43	2,008
Returned, eligible	307	106	73	131	23	1,422
Pain	301 82 (80–84)	105 80 (77–84)	71 76 (71–82)	129 71 (67–75)	22 64 (52–76)	1,373 88 (87–89)
Symptoms	303 78 (76–81)	105 78 (74–82)	72 71 (66–77)	131 67 (63–72)	23 59 (49–68)	1,383 86 (85–87)
ADL	298 78 (75–81)	105 79 (75–82)	72 70 (64–76)	130 68 (63–72)	21 62 (49–74)	1,367 86 (85–87)
Sport/Rec	289 59 (55–62)	101 57 (51–62)	71 49 (41–56)	127 45 (39–51)	20 37 (26–48)	1,343 73 (71–74)
QoL	298 67 (64–70)	105 61 (56–67)	71 47 (40–54)	128 55 (50–60)	22 45 (33–56)	1,367 83 (82–84)

The HOOS questionnaire results presented as means with 95% CIs. The 5 domains (Pain, other Symptoms, Function in daily living [ADL], Function in sport and recreation [Sport/Rec] and hip related quality of life [QoL]) are divided into 5 groups depending on number of dislocations and subsequent revisions. The eligible number of patients in each domain varies because not all patients completed the required items per domain. A score of 100 indicate no problems and 0 indicates extreme problems.

Table 3. Differences in HOOS QoL score for patients with dis­lo­ca­tion(s) depending on age, sex, and CCI, analyzed by multiple linear regression adjusted for number of dislocations, age, sex, and CCI

Factor	No. of patients	QoL score Δ (95% CI)
Age group
< 65	166	–3.6 (–8.9 to 1.7)
65–75	320	Reference
> 75	131	–2.9 (–8.8 to 2.9)
Sex
Male	246	Reference
Female	371	–7.3 (–12 to –2.7)
CCI
0	422	Reference
1–2	154	–4.8 (–9.9 to 0.6)
> 2	41	–8.8 (–18 to 0.2)

Although the clinical difference may be low, females reported hip-related QoL to be 7 points lower than males (p < 0.01), while there were no statistical differences among patients regarding age and CCI.

Table 4. Patient satisfaction. Values are % unless otherwise specified

Question	Dislocation(s) no revision	Dislocation(s) subsequent revision(s)	Controls without any dislocation or revision
“Overall, how are the problems now in the hip on which you had surgery, compared with before your operation?”
Eligible, n	469	146	1,358
Much better	70	56	89
A little better	13	21	5.8
No difference	7.7	6.2	3.2
A little worse	4.9	5.5	1.0
Much worse	4.9	11	1.3
“How would you describe the results of your original hip operation?”
Eligible, n	471	145	1,357
Excellent	28	11	59
Very good	32	13	27
Good	21	15	9
Fair	12	16	4
Poor	8.5	44	3
“With the knowledge and experience you have gained after the hip operation, would you then undergo the surgery again?”
Eligible, n	464	145	1,352
Yes	80	66	93
No	20	34	6.7

The 3 patient satisfaction items clearly show that patients who have experienced 1 or more dislocations are less satisfied with the original procedure compared with controls. The results are even worse after revision due to dislocation.