gekettelt - untrimmed
abgekettelt - trimmed

Trimming is removing the sinewy "chain" and membranes from the loin - the particularly annoying chewy bits that remain after roasting or frying when you don't trim the meat.

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Note added at 1 day7 mins (2015-02-12 23:38:29 GMT)
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The process of cleaning up the meat is
1) boning - Ausbeinen
2) skinning - Entschwarten (Haut und Fettschicht)
3) trimming - Cutting off "wings" (ragged edges) and sinews, membranes and excess fat = Säubern/Enthäuten/Abketteln

Now a bit of meat trivia:
Before or after this, particularly in the case of beef (or venison, which turns game - from the Nordic word for old, which is also the root of Gammel (Danish for old, as in Gammel Dansk) and Gammeln/Gammelfleisch (to hang around, rot or"go off") in German) - the meat may be hung for a while to tenderise it. This is a natural enzyme process that breaks down the muscle fibres - aka dry aging.
This is not generally recommended for pork.