A population study in the Province of Ontario of the complications after conversion of hip or knee arthrodesis to total joint replacement

Article Figures & Tables

Table I

Demographics and Crude Complication Rates After Total Hip Replacement With and Without Previous Hip Fusion

Demographic factor	Fusion	No fusion
Mean age, yr	58.5	66.9^*
Follow-up, yr	2.5	2.5
Male sex, %	60	43^†
Diagnosis not osteoarthritis, %	47.5	8.9^‡
Comorbid conditions > 1, %	0	2.7
Mean hospital volume, no./yr	181	136^†
Mean surgeon volume, no./yr	76	60^†
Mean length of hospital stay, d	10.3	10.3
Complication present at index admission, %	45	10.9^‡
Revision within 4 yr, %	10	1.8^*
Infection within 4 yr, %	10	1.3^§
Girdlestone procedure performed within 4 yr, %	5	0.3^§
Urinary tract infection at index admission, %	0	2.1
Deep venous thrombosis within 3 mo of index admission, %	0	2.2

Student’s t-test was used for continuous variables, the χ² test for categorical variables (with continuity correction). Fisher’s exact test was used when 1 or more cells had fewer than 5 expected counts. Comparisons between patients who underwent hip fusion takedown and those who did not may be biased since no adjustment was made for other potentially confounding factors.
↵* p < 0.01,
↵† p < 0.05,
↵‡ p < 0.0001,
↵§ p < 0.001

Table III

Demographics and Crude Complication Rates After Total Knee Replacement With and Without Previous Knee Fusion

Demographic factor	Fusion	No fusion
Mean age, yr	60.9	69.6^*
Follow-up, yr	2.8	2.4
Male sex, %	61.1	38.0^†
Diagnosis not osteoarthritis, %	33.3	8.8^*
Comorbid conditions > 1, %	11.1	3.2^§
Mean hospital volume, no./yr	106.8	143.9
Mean surgeon volume, no./yr	38.5	49.5
Mean length of hospital stay, d	13.1	10.3^†
Complication present at index admission, %	22.2	10.3
Revision within 4 yr, %	5.6	2.0
Fusion or re-fusion within 4 yr, %	11.1	0.1^‡
Excision within 4 yr, %	16.7	0.8^‡
Patellar replacement or patelloplasty. %	27.8	85.3^‡
Infection within 4 yr, %	11.1	2.2
Urinary tract infection at index admission, %	5.6	2.0
Deep venous thrombosis within 3 mo of index admission, %	5.6	2.6

Student’s t-test was used for continuous variables, the χ² test for categorical variables (with continuity correction). Fisher’s exact test was used when 1 or more cells had fewer than 5 expected counts. Comparisons between patients who underwent hip fusion takedown and those who did not may be biased since no adjustment was made for other potentially confounding factors.
↵* p < 0.01,
↵† p < 0.05,
↵‡ p < 0.0001,
↵§ p < 0.001

Table IV

The Odds of Complications After Total Knee Replacement for Patient With and Without Previous Knee Fusion

Outcome	Odds ratio (with:without fusion)	95% confidence interval
Knee resection arthroplasty	15.8	4.3–58.5
Infection	4.0	0.9–17.8
Complications during index admission	2.7	0.9–8.3
Revision	1.9	0.25–14.5
Repeat fusion of the knee	82.0	15.3–44.2

An odds ratio > 1 implies that the complication is more likely to occur after conversion of a previous knee fusion. In all cases the estimate is adjusted for age, gender, diagnosis, admission year, follow-up time, and surgeon and hospital volume. A 95% confidence level that includes 1 suggests that the result was not significant at p < 0.05. Significant findings are highlighted.

Table V

Experience With Hip Fusion Conversion to Total Hip Arthroplasty Since 1980

Demographic factor	Series
Demographic factor	Current study	Reikeras et al, 199531	Kilgus et al, 199012	Strathy and Fitzgerald, 198813	Cameron and Jung, 198710	Hardinge et al 198611	Lubahn et al 19806
No. of joints	40	46	41	80	13	112	17
Surgically fused, %	NA	NA	31.7	80	100	65.2	29.4
Follow-up, yr	1–4	5–13	7	9–15	1–9	2–19	< 9
Mean age, yr	58.5	58	53	49.8	49	NA	58.5
Male, %	60	19.6	48.8	NA	53.8	NA	70.6
Infection, %	10	0	9.8	11.3	0	1.8	5.9
Excision, %	0	0	0	1.3	0	0	5.9
Revision, %	10	15.2	0	25	0	2.7	5.9
Repeat fusion, %	0	0	0	0	0	0	0
Function	NA	74% needed aids after (none before), 76% good & excellent	Fewer aids	45% good or excellent	69.2% good and excellent	Relief of back pain and function	Relief of back and ipsilateral knee pain
Mean range of movement (flexion)	NA	NA	87°	NA	88°	NA	72°

The information presented in the table is taken from English-language publications since 1980 reporting on at least 10 patients after conversion of a hip fusion to a total joint replacement.

Table VI

Experience With Knee Fusion Conversion to Total Knee Arthroplasty Since 1980

Demographic factor	Series
Demographic factor	Current study	Naranja et al, 199620	Cameron and Hu, 199616	Bradley et al, 198714
No. of joints	18	37	17	9
Follow-up, yr	1–4	0–20	1–10	2–6
Mean age, yr	60.9	53	59.1	55
Male, %	61.1	20	58.8	11.1
Infection, %	11.1	13.5	18	0
Excision, %	16.7	1^*	0	0
Revision, %	5.6	24.3	12	11.1
Repeat fusion, %	11.1	5.4	11.8	0
Function	NA	42.9% housebound	58.8% good or excellent	Longer Walking tolerance
Mean range of movement (flexion)	NA	−7°–62°	0–84°	2°–64°

The information presented in the table is taken from English-language publications since 1980 reporting on at least 10 patients after conversion of a knee fusion (0° of preoperative motion) to a total joint replacement.
↵* Above knee amputation