Birmingham Hip Resurfacing for osteoarthritis — a Canadian retrospective cohort study with a minimum 10-year follow-up

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Fig. 1
Anteroposterior radiograph showing the measurement of the abduction angle (inclination) of the cup.
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Fig. 2
Survival curves following Birmingham hip resurfacing.
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Fig. 3
Radiograph showing a patient who required revision surgery for a loose acetabular cup. The patient would be revised to a BHR dysplastic cup. BHR = Birmingham hip resurfacing.

Table 1

Baseline patient characteristics, by gender

Characteristic	Male n = 83	Female n = 24	Total n = 107
Age, mean ± SD, yr	50.3 ± 6.6	45.1 ± 8.1	49.1 ± 7.3
BMI, mean ± SD, kg/m²	28.97 ± 5.0	25.87 ± 5.2	28.27 ± 5.2
Follow-up, mean, yr	12.23	12.81	12.37
Hips, n (%)	96 (75.6)	31 (24.4)	127 (100)
BHR procedure, n
Unilateral	70	17	87
Bilateral^*	6	3	9
Simultaneous	7	4	11

BHR = Birmingham hip resurfacing; SD = standard deviation.
↵* Twenty-eight patients had bilateral BHRs at the last follow-up in June 2019; however, 19 of these patients (17 male, 2 female) had their second BHR performed < 10 years ago and, therefore, only their first BHR was included for data analysis.

Table 2

Characteristics of the 11 patients who underwent BHR revision

Patient	Age, yr^*	Cup/head size, mm	Cup inclination^†	Time to revision, mo	Reason for revision
Male
1	53	62/54	33.2°	160	Pseudotumour at 12 yr
2	66	64/58	43.7°	56	Acetabular cup loosening
3	60	64/58	41.1°	105	Femoral avascular necrosis with implant subsidence
4	62	56/50	43.1°	124	Anterior acetabular impingement
5	57	58/52	44.2°	48	Acetabular cup loosening
Female
1	54	54/48	35.6°	110	ALVAL/pseudotumour at 2 yr
2	67	52/46	37.5°	62	Elevated whole-blood metal-ions at 4 yr
3	38	48/42	45.9°	78	Periprosthetic fracture
4	59	50/44	34.8°	108	Aseptic femoral loosening
5	41	48/42	37.1°	102	Aseptic femoral loosening
6	33	54/46	53.8°	97	Ongoing symptomatology

ALVAL = aseptic lymphocyte-dominated vasculitis-associated lesion; BHR = Birmingham hip resurfacing.
↵* Age of the patient at the time of the index surgery.
↵† Measurement of the abduction angle on standard anteroposterior radiographs, as described previously by De Haan et al.22

Table 3

Implant characteristics

Characteristic	% of patients^*
Acetabular cup inclination, mean ± SD (range)
Males	45.5° ± 6.0 (34.6°–57.2°)
Females	44.6° ± 5.9 (29.0°–58.9°)
BHR implant size
Head size, 42 mm
Cup size, 48 mm	3.5
Cup size, 50 mm	5.3
Head size, 46 mm
Cup size, 52 mm	18.6
Head size, 50 mm
Cup size, 56 mm	36.3
Cup size, 58 mm	0.9
Head size, 52 mm
Cup size, 58 mm	10.6
Head size, 54 mm
Cup size, 60 mm	15.0
Cup size, 62 mm	1.8
Head size, 58 mm
Cup size, 62 mm	8.0