After a few loose 2-0 Vicryl sutures were used, the fifth toe rotation flap was trimmed to fit the base of both the fourth and fifth previous digits.

Question: not a run-on-
not a comma splice
not a complete sentence
Answer:
Thinking it is a fragment (missing a subject).

It's a complete sentence.

[introductory adverbial clause], flap (subject) was trimmed (verb) ...

The subjects are "sutures" and "flap." If I was acquainted with the context and terms, it might not seem to run-on. It would seem clearer in two sentences.

To determine whether the given sentence is a fragment, run-on, comma splice, or a complete sentence, we can analyze its structure and check for any missing components.

In this case, the sentence "After a few loose 2-0 Vicryl sutures were used, the fifth toe rotation flap was trimmed to fit the base of both the fourth and fifth previous digits" appears to be a fragment. It lacks a subject, which is the noun or pronoun that performs the action in a sentence.

To correct the fragment and make a complete sentence, we need to add a subject. For example:

"The surgeon used a few loose 2-0 Vicryl sutures, then trimmed the fifth toe rotation flap to fit the base of both the fourth and fifth previous digits."

By adding the subject "the surgeon," we now have a complete sentence that clearly expresses the action being performed.