4. Balance Sheet Details

Accounts Receivable

Accounts receivable consist of the following (in thousands):


	March 31, 2012			December 31, 2011
Accounts receivable	$	41,974		$	42,766
Allowance for doubtful accounts		(1,404	)		(1,055	)

Accounts receivables, net	$	40,570		$	41,711

Inventories

Inventories consist of the following (in thousands):


	March 31, 2012							December 31, 2011
	Gross		Reserve for excess and obsolete			Net		Gross		Reserve for excess and obsolete			Net
Raw materials	$	4,652	$	—		$	4,652	$	3,715	$	—		$	3,715
Work-in-process		1,369		—			1,369		2,088		—			2,088
Finished goods		55,689		(13,555	)		42,134		53,287		(13,174	)		40,113

Inventories, net	$	61,710	$	(13,555	)	$	48,155	$	59,090	$	(13,174	)	$	45,916

Property and Equipment

Property and equipment consist of the following (in thousands except as indicated):


	Useful lives (in years)		March 31, 2012			December 31, 2011
Surgical instruments		4	$	53,909		$	52,690
Machinery and equipment		7		13,122			12,462
Computer equipment		5		3,009			3,013
Office furniture and equipment		5		3,574			3,578
Leasehold improvements		various		4,075			3,657
Building		39		67			71
Land		n/a		13			14
Construction in progress		n/a		859			634

				78,628			76,119
Less accumulated depreciation and amortization				(46,539	)		(44,643	)

Property and equipment, net			$	32,089		$	31,476

Total depreciation expense was $3.5 million and $3.8 million for the three months ended March 31, 2012 and 2011, respectively.

Intangible Assets

Intangible assets consist of the following (in thousands except as indicated):


	Useful lives (in years)		March 31, 2012			December 31, 2011
Developed product technology		5-8	$	23,144		$	22,875
Distribution rights		3		4,381			4,531
Intellectual property		5		1,004			1,004
License agreements		1-7		14,297			14,297
Core technology		10		3,591			3,489
In-process technology		Indefinite		1,729			1,680
Trademarks and trade names		5-9		3,759			3,671
Customer-related		15		15,847			15,476
Distribution network		10		1,614			1,614
Physician education programs		10		3,059			2,972
Supply agreement		10		225			225

				72,650			71,834
Less accumulated amortization				(27,022	)		(24,690	)

Intangible assets, net			$	45,628		$	47,144

Total amortization expense was $2.3 million and $1.2 million for the three months ended March 31, 2012 and 2011, respectively.