Inside Insights For Performing A Metatarsal Osteochondral Graft

A 43-year-old female presented with many years of painful joint motion in the left first metatarsophalangeal joint (MTPJ). She suffered a stubbing injury three years prior but has had more symptoms and pain recently. It is becoming more difficult to wear shoes with medial and dorsal joint pressure. Her physical exam and history are otherwise unremarkable.
Preoperative AP radiographs show moderate joint space narrowing with osseous contact laterally. The structural length of the first metatarsal is equal to the second metatarsal. The pre-op lateral view shows mild first metatarsal elevation with moderate spurring.

In the surgical management of this patient, one would perform a capsulotomy into the first MTPJ for exposure of the capital fragment. A “T” configuration allows for better relaxation of the joint capsule for exposure to the lateral aspect of the joint. Remove the fragmentation and spurring around the joint, and direct attention towards the osteochondral defect in the central lateral aspect. Remove any loose cartilage or flaps up to good healthy surrounding cartilage.

Determining The Size And Treatment Of A Lesion
One can determine the size of the lesion by close evaluation and by using the metallic sizers available. These are available in sizes from 5 mm to 11 mm. It is helpful to remove the entire lesion or remove as much as possible. This will allow direct contact of the graft with viable peripheral cartilage for optimum repair. This technique works well for single plugs but is not as successful with multiple plugs that may be in contact with each other.
After determining the size of the lesion, one can place a cannulated pin perpendicular to the joint surface within the central portion of the defect. Use the appropriate sized cannulated drill to drill a hole roughly 1 cm deep. The drill will cause less trauma than the use of a mallet and trephine plug impacting the metatarsal. The use of a mallet on the metatarsal heads is risky for the potential of causing a stress fracture, especially in the lesser metatarsals.

Place the measuring tube into the defect and push extra bone graft out from the opposite end. The remaining graft within the measuring tube is exactly the depth of the drilled defect. Use a knife, included within the disposable kit, to cut off the extra bone portion extending from the tube.
Reverse the tube and use a mallet to tap the OsteoCure plug gently into the defect site. The drill hole is up to 0.4 mm smaller than the actual graft so this will be a nice tight press fit. Be gentle with this step to avoid impacting the graft deeper than the chondral surface. Tap the graft into place so it is flush with the surrounding surface.
Perform an osteotomy to assist in decompression of the capital fragment. Stabilize this with internal fixation as one deems necessary. Stable rigid compression fixation will allow early range of motion. The surgeon should make the osteotomy after placing the chondral graft. This will avoid extra stress and movement to the capital fragment. Within a few minutes, the blood from the surrounding tissues absorbs into the synthetic graft.
Postoperative radiographs show the metatarsal osteotomy and chondral graft. Note the outline of the chondral graft is still slightly visible on the AP radiograph. This will fully incorporate with a “creeping substitution” type of healing from the periphery over the next one to two years. At 10 months, the patient is doing well clinically and is fully participating in her activities.

What You Should Know About The Surgical Technique
Over the past several years, evolving techniques for osteochondral defects have been used for talar lesions. These include autografts and allografts in single plugs or mosaic patterns. Surgeons have utilized similar techniques for chondral defects in the metatarsal heads as well. The degenerative changes seen in hallux valgus and limitus cases can present with lesions that can be staged into the traditional types I to IV. They also can occasionally present with cystic changes within the metatarsal heads. Obtaining a MRI may be useful to image these cystic changes and recognize the deep marrow edema within the capital fragment.

An important facet in the complete correction of the deformity is to assess biomechanical contributions to the deformity. It is imperative to create a better environment to the joint in question and this will often require an osteotomy. Consider metatarsal decompressional osteotomies in joint preservation cases with hallux limitus/rigidus. One can perform this behind the graft site and still stay within the metaphyseal portion of the bone. This will provide a much healthier environment for the joint in the long term.
The formation of hyaline cartilage into the graft site has been well documented in both the in vitro and in vivo models. There is essentially a creeping substitution type of incorporation as both the bone and the cartilage will heal from the periphery inward. The central portions of the graft are the last to heal and fully revascularize. Once complete, however, this provides the surgeon with an almost perfect cartilage repair in a synthetic form. The applications of this technology to our current practices will be limitless.