。
Many doctors use a certain type of absorbable suture.
Literal
Many [attributive-の] doctors [topic-は] a-certain type [attributive-の] absorbable suture [object-を] are-using-[continuous-ている].
Medical technical register. 吸収性縫合糸 is a fully Sino-Japanese compound — 吸収 (absorb) + 性 (-ity/-able) + 縫合糸 (suture thread) — the kind of noun you meet in surgical manuals. ある種の is a common set phrase meaning 'a certain kind of, a particular type of.' ~ている here expresses habitual / general practice ('use regularly'), not a specific ongoing action at the moment of speaking.