All Arthroscopic Suture-Bridge Fixation of a Delaminated Chondral Fragment

Introduction Articular cartilage lines the surface of joints and transmits the forces generated with joint loading. When damaged, it has poor healing potential. Conditions such as osteochondritis dissecans, trauma, and occasionally avascular necrosis, can create free or detached fragments of articular cartilage with varying amounts of attached subchondral bone. Detached fragments require operative intervention because of the intra-articular loose body. With removal of a detached fragment, the resultant articular incongruity can lead to rapid joint degradation. If possible, fixation of the loose or detached osteochondral fragment can lead to healing of the fragment and good long-term outcomes. Multiple techniques have been described for fixation of loose osteochondral fragments with open, mini-open and arthroscopic assisted approaches. The earliest descriptions were of headed metal screws, which necessitated a repeat surgical procedure for implant removal. Headless, and more recently bioabsorbable headless compression implants, have been developed that eliminate the need for subsequent surgery to remove the implants. Because these devices need to be countersunk below the level of the articular cartilage to avoid damage to the apposing articular surface, all of these techniques depend on their interaction with the subchondral bone to achieve fixation. Thus as the thickness of subchondral bone on the free piece decreases, the stability of the fixation afforded by these devices would be expected to decrease. Recently, two case series of suture bridge fixation of loose osteochondral fragments have been described with good results. In these cases, drill hole tunnels were created from four corners of the defect to an area away from the articular surface. Two absorbable sutures were then passed in a cross configuration, capturing the free fragment in the defect. The sutures were then tied over a bone bridge off of the articular surface. Because this technique does not require fixation based on the integrity of the subchondral bone on the free piece, it is a useful technique for thinly delaminated osteochondral fragments, or osteochondral pieces where the integrity of the subchondral bone has been compromised. It also affords uniform compression across the piece to promote healing and more secure fixation at the edges of the lesion where edge loading and catching during range of motion would be thought to lead to early failure. A notable downside to this approach is the requirement of a large open arthrotomy with all the attendant risks and rehabilitation delays. Based on the clinical success of this fixation method, and the proposed biomechanical advantages, we have devised an all-arthroscopic technique to secure osteochondral fragments with a suture bridge construct. (Figure 1) We present a case in which successful fixation of a completely displaced, thinly-delaminated chondral fragment involving most of the medial trochlea was achieved in the knee of a 12-yearold skeletally-immature boy. This is the first description in the literature, to our knowledge, of an all arthroscopic suture bridge fixation of a completely displaced osteochondral fracture in the knee joint.