What procedure involves creating a surgical opening into the joint capsule?

The procedure that involves creating a surgical opening into the joint capsule is arthrotomy. This operation allows surgeons to gain direct access to the interior of a joint for diagnostic purposes or to perform surgical repairs or interventions. By creating an opening, the surgeon can visualize the joint structure directly, which is particularly useful for addressing issues such as joint damage, loose bodies, or significant inflammation.

In contrast, arthroplasty refers to the surgical repair or replacement of a joint, often used in the context of joint reconstruction or replacement surgeries, like knee or hip replacements. Bursectomy involves the removal of a bursa, which is a fluid-filled sac that reduces friction between tissues, but it does not pertain directly to the joint capsule itself. Arthroscopy, on the other hand, is a minimally invasive procedure that uses a camera and instruments inserted through small incisions to visualize and treat joint issues without making a large incision like in arthrotomy. Thus, the specific nature of arthrotomy as it relates to creating an opening in the joint capsule distinguishes it as the correct answer.