As of March 31, 2022 and December 31, 2021 the carrying values of our indefinite lived intangible assets were as follows (in thousands):

We monitor the phases of development of our acquired in-process research and development projects, including the risks associated with further development and the amount and timing of benefits expected to be derived from the completed projects. Incremental costs associated with development are charged to expense as incurred. Capitalized costs are amortized over the estimated useful life of the developed asset once completed. Our in-process research and development projects are reviewed for impairment annually, or more frequently, if events or changes in circumstances indicate that the asset might be impaired. We did not record any impairment of indefinite lived intangible assets during the three months ended March 31, 2022. In-process research and development, procurement contracts and agreements, and trademarks are included in Other intangibles, net on the Condensed Consolidated Balance Sheets as of March 31, 2022 and December 31, 2021.

Based on our experience with similar agreements, we believe that our acquired procurement contracts and agreements have indefinite useful lives, as we expect to continue to renew these contracts for the foreseeable future. We believe that our trademarks have indefinite useful lives as we currently anticipate that our trademarks will contribute to our cash flows indefinitely.

We evaluate our goodwill and non-amortizing intangible assets for impairment on an annual basis during the fourth quarter of the year, and, if necessary, during interim periods if factors indicate that an impairment review is warranted. As of March 31, 2022 we concluded that our assessment of current factors did not indicate that goodwill or non-amortizing intangible assets are more likely than not to be impaired. We will continue to evaluate the recoverability of these non-amortizing intangible assets in future periods as necessary.

As of March 31, 2022 and December 31, 2021 our entire goodwill balance was related to our Medical devices segment.

The definite lived intangible assets balance includes balances related to acquired technology, customer relationships, distribution and manufacturing rights and know-how, patents, and other definite lived intangible assets. As of March 31, 2022 and December 31, 2021 the gross carrying values, accumulated amortization, and approximate amortization period of our definite lived intangible assets were as follows (in thousands):


							Weighted Average
	Gross Carrying		Accumulated		Net Carrying		Useful Life
March 31, 2022	Value		Amortization		Value		(Years)
Acquired technology	$	211,589	$	49,131	$	162,458	17.7
Other intangibles:
Customer lists and relationships		31,108		9,987		21,121	20.5
Distribution and manufacturing rights and know-how		9,652		4,675		4,977	5.0
Patents		4,127		3,153		974	17.0
Other		4,190		1,938		2,252	4.4
Total other intangibles	$	49,077	$	19,753	$	29,324	10.6

							Weighted Average
	Gross Carrying		Accumulated		Net Carrying		Useful Life
December 31, 2021	Value		Amortization		Value		(Years)
Acquired technology	$	213,626	$	46,632	$	166,994	17.7
Other intangibles:
Customer lists and relationships		31,148		9,618		21,530	20.5
Distribution and manufacturing rights and know-how		9,847		4,308		5,539	5.0
Patents		4,083		3,144		939	17.0
Other		3,969		1,762		2,207	4.4
Total other intangibles	$	49,047	$	18,832	$	30,215	10.6

The following is a summary of amortization expense as recorded in General, administrative, and marketing expenses on our Condensed Consolidated Statement of Operations and Comprehensive Loss (in thousands):

As of March 31, 2022 scheduled amortization of intangible assets for the next five years is as follows (in thousands):


	Remainder
	of 2022		2023		2024		2025		2026		2027		Total
Amortization expense	$	11,625		15,131		14,754		12,785		12,559		12,496	$	79,350