There are 2 ball joints on the front suspension upper and lower. The upper one appears to be integral with the suspension arm whereas the lower one is replaceable in the existing arm. If either arm was removed to replace a ball joint then a suspension re-alignment would probably be necessary particularly the lower arm which has an eccentric bush-- 40 in the diagram
http://www.detali.ru/cat/oem_mb2.as...GA=722.633&CT=F&cat=65N&SID=33&SGR=030&SGN=01
. If the lower ball joint was replaced "in situ" without the arm being removed then "in theory" re-alignment should not be necessary. However checking the tracking afterwards would still be desirable. In practice if the front tyres are worn unevenly due to prior suspension wear then its very difficult to set up the car properly without a fresh set of tyres .