Season of the year influences infection rates following total hip arthroplasty

Table 1 Study patient demographics

	NE	MW	WE	SO
Female	61.60%	61.10%	60.60%	61.40%
Male	38.40%	38.90%	39.40%	38.60%
Age (yr)	9%	9%	9%	12%
≤ 64	9%	9%	9%	12%
65-69	23%	24%	26%	24%
70-74	22%	22%	23%	22%
75-79	21%	21%	20%	20%
80-84	16%	15%	14%	14%
≥ 85	10%	9%	9%	8%

NE: North East; MW: Mid West; WE: West; SO: South.

Table 2 Incidence of acute postoperative infections at 90 d following total hip arthroplasty

Location	Spring	Summer	Fall	Winter	χ2
North East	1.41%	1.35%	1.35%	1.47%	0.281
Mid West	1.54%	1.59%	1.51%	1.60%	0.39
South	1.60%	1.68%	1.58%	1.64%	0.277
West	1.25%	1.59%	1.31%	1.43%	< 0.001
Mean	1.45%	1.55%	1.44%	1.54%
SD	0.16%	0.14%	0.13%	0.10%

Table 3 Incidence of periprosthetic infections at 90 d following total hip arthroplasty

Location	Spring	Summer	Fall	Winter	χ2
North East	0.82%	0.83%	0.84%	0.91%	0.358
Mid West	0.97%	0.97%	0.88%	1.04%	0.013
South	1.06%	1.06%	0.96%	1.10%	0.007
West	0.84%	0.84%	0.88%	0.89%	0.68
Mean	0.92%	0.92%	0.89%	0.98%
SD	0.11%	0.11%	0.05%	0.10%