Biologic alternatives to shoulder arthroplasty

Biologic Humeral Resurfacing

Biologic subtotal resurfacing of the humeral head is an option for focal loss of humeral head articular cartilage. Situations in which subtotal resurfacing of the humeral head are indicated are rare, but biologic implants can prove useful in certain scenarios.

Biologic surface replacement is indicated in young patients (<30 years) with localized full-thickness defects of the articular cartilage of the humeral head who have failed other treatments. When young patients with full-thickness articular cartilage lesions of the humeral head are seen in our practice, we initially treat them nonoperatively with nonsteroidal antiinflammatory medications, selective rest, and activity modification for a period of 6 to 12 weeks. If such treatment proves unsuccessful, we offer arthroscopic treatment of the lesion with débridement and drilling of subchondral bone to stimulate the formation of fibrocartilage. If patients remain symptomatic 6 months after arthroscopic treatment, we will offer them biologic surface replacement with a matched osteochondral allograft. In our experience, it is rare for a patient to fail arthroscopic treatment of these localized articular cartilage lesions, thus minimizing the indications for partial surface replacement.

Contraindications specific to biologic surface replacement include cartilaginous lesions larger than 35 mm in diameter, the presence of nonlocalized disease, and the absence of sufficient bone quality to support the osteochondral allograft.

Technique for Biologic Resurfacing

The operating room setup, anesthesia, patient positioning, skin preparation, surgical draping, and surgical approach are identical to that for humeral surface replacement and other shoulder arthroplasties (see Chapter 3, Chapter 4, Chapter 8 ). Handling of the subscapularis is the same as for stemless shoulder replacement, as described previously in Chapter 33 . Biologic resurfacing necessitates greater preoperative planning in that it is necessary for the company supplying the proximal humeral allograft to locate an appropriately sized specimen (we use the Musculoskeletal Transplant Foundation). Magnification-controlled radiographs and computed tomography scans of the proximal humerus are provided to the allograft supplier to allow appropriate specimen selection. Our supplier has usually been able to provide specimens within 6 weeks of receiving the preoperative imaging studies. After the specimen has been obtained, surgery is scheduled.

The humeral head is dislocated to expose the articular cartilage lesion ( Fig. 34.1 ). The size of the lesion is measured with a templating device from the instrumentation set (Arthrex, Inc., Naples, Florida; Fig. 34.2 ), and a guide pin is placed in the humeral head at the center of the articular cartilage lesion with the templating device used as a guide ( Fig. 34.3 ). A specialized cannulated drill is used to score the periphery of the lesion ( Fig. 34.4 ), and a cannulated triflange reamer is used to create an osseous defect in which to place the osteochondral allograft ( Fig. 34.5 ). If associated osteonecrosis is present in addition to the articular cartilage lesion, the reamer is advanced to a depth sufficient to eliminate the necrotic bone as determined on preoperative imaging studies. If no or minimal osteonecrosis is present, the reamer is advanced a minimum of 10 mm deep to provide an adequate interference fit for the osteochondral allograft. Fig. 34.6 shows the humerus after reaming has been completed.

The proximal humeral allograft is positioned in the cutting jig, and the selected donor site is marked with a surgical marker ( Fig. 34.7 ). A cutting guide of appropriate diameter is assembled onto the cutting jig, and a coring drill is used to harvest the osteochondral allograft plug ( Fig. 34.8 ). The allograft plug is placed in a specialized clamp, and a saw is used to trim the deep surface of the allograft to match the depth penetrated by the triflange reamer ( Fig. 34.9 ). The bone plug is progressively impacted into the prepared humeral defect until it is fully seated ( Fig. 34.10 ).

The subscapularis is closed with interrupted no. 2 braided permanent tendon-to-tendon suture. The closure is reinforced with running no. 1 braided absorbable suture. The wound is then closed as for other cases of shoulder arthroplasty.