How To Salvage A Failed First MPJ Implant
Why Distraction Arthrodesis May Be The Most Effective Procedure
The final and most biomechanically sound option for salvage is bone block distraction fusion of the first metatarsophalangeal joint. This procedure accomplishes subjective improvement of the patient’s level of pain and walking tolerance as well as objective restoration of first ray stability (thus alleviating symptoms of lesser metatarsophalangeal joint overload). The procedure also restores great toe alignment and length, and usually enables one to correct lesser digital malalignment after restoring the hallux position. To date, only one study (14 patients) has reported functional outcomes of distraction arthrodesis after a failed implant.22 The authors of that study stipulated this technically demanding procedure provides long-term stability to the hallux, restores weightbearing and allows patients to maintain a propulsive gait.22 Distraction arthrodesis is preferable for medically fit, active individuals with a failed silicone implant. Although the age of the patient is a factor in considering surgical options, this procedure can be a reasonable choice for medically fit, active patients as old as 70. Surgeons should obtain preoperative anteroposterior, lateral and medial oblique radiographs of both feet in weightbearing stance so they can compare the unaffected foot with the other foot in regard to digital malalignment, shortening and bony erosion about the implant. These preoperative radiographs also enable surgeons to assess implant fragmentation and the metatarsal parabola. One should counsel patients regarding the need for autogenous bone graft and the risk of further morbidity from the bone graft donor site. In most cases, two donor sites are available for use, depending on the size of the graft you need. If a piece measuring 1.0 to 1.5 cm in length is required, then one can harvest a bicortical block of bone from the superior aspect of the calcaneus. If one needs a larger piece, obtaining a tricortical bone block from the anterior iliac crest is the best option. Preoperative radiographs will indicate the size of structural graft needed. In my experience with these cases, I have found it a good idea always to anticipate the need for more bone. The bony interfaces with the implant are usually sclerotic and adequate resection to healthy bleeding bone can result in a large defect. In my experience, nearly all cases of failed first metatarsophalangeal joint implants have required iliac crest bone grafting. Mixing demineralized bone matrix and other osteogenic products with autogenous cancellous bone also can be useful to “fill” defects created by the implant. Rigid fixation is required until one achieves radiographic union. I usually employ internal fixation but one can use external fixators to supplement the construct. In many of these cases, one will observe varus malposition of the hallux and second and third digits. These digits can usually be anatomically aligned after the hallux is anatomically positioned.