A subchondral bone defect, often referred to as a trabecular fracture, marrow edema lesion, or a Bone Marrow Lesion (or BML), is a term for a finding on an MRI that represents an abnormal area or defect inside the bone. BMLs are visible on an MRI but not in a regular X-ray. They are typically found in subchondral bone, the region below the cortical bone near a joint. They can only be seen on certain MRI sequences, such as T2, appearing as a hazy white area against the background of darker bone.
Microscopic analysis has shown that BMLs represent a healing response surrounding small defects in the subchondral bone, such as micro trabecular fractures. In some cases, BML defects are a result of a bone injury that does not heal properly. In other cases, BML may be a stress reaction that forms from overuse or poor joint mechanics.
Conservative treatments for BMLs include pain medications, knee braces, crutches, and physical therapy. However, long lasting (chronic) BMLs that do not heal by themselves will require treatment. Patients with chronic BMLs may have more rapid cartilage loss and may be more likely to require a total knee replacement.
If concservative treatment fails, subchondroplasty is a minimally invasive procedure that is performed to specifically repair chronic BMLs by filling them with a bone substitute material. The bone substitute is then slowly resorbed and replaced with healthy bone repairing the bone defect. Subchondroplasty also resolves the associated edema. Subchondroplasty may be performed alone or along with other arthroscopic procedures.
Patients with a BML may be indicated for subchondroplasty. While indications may vary slightly among surgeons, in Dr. Rice’s practice the best candidates for subchondroplasty present with some or all of the following features:
As with most newer technologies and procedures, it is especially important for Dr. Rice to evaluate each patient and case on an individual basis to best determine if subchondroplasty is an appropriate treatment option.
The whole subchondroplasty procedure is performed under fluoroscopy to accurately target the chronic BMLs. Fluoroscopy provides the surgeon with intraoperative real time X-ray images of the surgical area to guide the surgeon. Before the procedure the BMLs are first diagnosed on a T2 Fat Suppressed MRI.
Often this procedure is performed in conjunction with joint arthroscopy, when chondroplasty, synovectomy, meniscus repair or resection (knee), and labral repair or resection (hip) may be performed simultaneously.
Patients are typically treated in an outpatient setting, returning home the same day of the procedure. Some pain and discomfort in the operated area is usually experienced for 1-2 days after the procedure. Pain medications will be prescribed to manage pain. For most patients, the subchondroplasty has no effect on the duration of recovery or restrictions after surgery. Most patients are permitted to bear weight as tolerated after surgery with crutches for support, and participate in physical therapy as part of the routine arthroscopy postop protocol. In the case of knee arthroscopy with concomitant partial menisectomy, recovery is often 4-6 weeks; for meniscal repair, 3-6 months; and hip arthroscopy with labral repair, 4-6 months. These variable recovery periods are dependent not on the subchondroplasty procedure, which is rarely the limiting factor in the surgical recovery, but rather the other procedures performed simultaneously with the subchodroplasty procedure, which may require protection of relatively fragile soft tissue structures.
Subchondroplasty is a minimally invasive procedure with the following advantages:
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