REVENUE RECOGNITION

Our policies for recognizing sales have not changed from those described in our Annual Report on Form 10-K for 2018.

We disaggregate our net sales by product line and geography for each of our segments as we believe it best depicts how the nature, amount, timing and certainty of our net sales and cash flows are affected by economic factors.



Net Sales by Product Line
	Three Months
	2019		2018
Orthopaedics:
Knees	$	439	$	419
Hips	336		331
Trauma and Extremities	396		389
Other	79		77
	$	1,250	$	1,216
MedSurg:
Instruments	$	478	$	412
Endoscopy	470		444
Medical	531		511
Sustainability	65		60
	$	1,544	$	1,427
Neurotechnology and Spine:
Neurotechnology	$	465	$	410
Spine	257		188
	$	722	$	598
Total	$	3,516	$	3,241



Net Sales by Geography
	Three Months 2019				Three Months 2018
	United States		International		United States		International
Orthopaedics:
Knees	$	320	$	119	$	301	$	118
Hips	213		123		205		126
Trauma and Extremities	254		142		245		144
Other	63		16		63		14
	$	850	$	400	$	814	$	402
MedSurg:
Instruments	$	381	$	97	$	316	$	96
Endoscopy	376		94		349		95
Medical	416		115		381		130
Sustainability	64		1		60		—
	$	1,237	$	307	$	1,106	$	321
Neurotechnology and Spine:
Neurotechnology	$	297	$	168	$	256	$	154
Spine	195		62		138		50
	$	492	$	230	$	394	$	204
Total	$	2,579	$	937	$	2,314	$	927

Contract Assets and Liabilities

On March 31, 2019 there were no contract assets recorded on our Consolidated Balance Sheets.

Our contract liabilities arise as a result of consideration received from customers at inception of contracts for certain businesses or where the timing of billing for services precedes satisfaction of our performance obligations. We generally satisfy performance obligations within one year from the contract inception date. Our contract liabilities were $331 and $327 on March 31, 2019 and December 31, 2018.