Over the years, I have continued to employ the osteochondral graft procedure (HAT graft procedure), described by Bernard Regnault, MD, in selected cases of hallux valgus and hallux rigidus. I find the procedure to be reliable in satisfying the requirements of elderly patients as it offers a viable alternative to arthrodesis, resection arthroplasty or implant arthroplasty.
The procedure involves complete removal of the base of the proximal phalanx with a portion of diaphyseal bone, remodeling and then subsequent re-implantation of the remodeled proximal phalanx base. The procedure offers many of the benefits inherent to a Keller-type resection arthroplasty. The procedure by definition releases all soft tissue attachments to the proximal phalanx so contractures are relieved.
Unlike the traditional Keller-type resection arthroplasty, however, I have found over the years that many of the problems associated with the Keller type procedure (such as hallux hammertoe, loss of first ray weightbearing, shortening and resultant arthrofibrosis with pain) occur infrequently with the use of the HAT graft procedure. The procedure allows immediate ambulation and, in my experience, there has been a high rate of satisfaction in properly selected patients.
One may fixate the remodeled base of the proximal phalanx in position by any means whether it is via Kirschner wires, two small screws, compression staples or any reasonable device of the surgeon’s preference. Many patients require no fixation whatsoever with adequate purchase of the implant. I find that the procedure has been most successful in those patients who have a very large component of positional deformity secondary to soft tissue contracture.
As is the case with the Keller procedure, a rather large intermetatarsal angulation secondary to soft tissue contracture frequently reduces the retrograde force of the soft tissue contracture of the removed hallux. I have personally never witnessed avascular necrosis of the implant as a complication. Incomplete reduction of hallux valgus and continued limited motion represent the most frequent complications that I have encountered. Following surgery, one may allow immediate ambulation. Active range of motion is encouraged.
Consider the utilization of this old, very reliable procedure in selected elderly individuals in whom shortening of the great toe, complete release of soft tissue contracture, and immediate restoration of motion are our primary goals.
Figure 1 demonstrates a typical HAT graft fixated with a small Kirschner wire. The remodeled base of the proximal phalanx is demonstrated.
Figure 2 demonstrates resection of the base of the proximal phalanx.
Figure 3 demonstrates the resected base of the proximal phalanx. This is slightly larger than what you would typically see when performing the Keller procedure.
Figure 4 demonstrates the remodeled base of the proximal phalanx. One may use a sagittal saw or other instrument to remove the cortices of the proximal diaphysis of the resected bone. This leaves a stem of medullary bone and the articular surface as well as the subchondral surface of the proximal phalanx. Essentially, we created a hemi-implant out of the patient’s own bone. The surgeon may also remodel the periarticular structures of the proximal phalanx as required by intraoperative observation and the surgeon’s judgment. The amount of cortex you resect can vary in order to allow lesser shortening of the great toe as you determine to be appropriate.
Figure 5 demonstrates preparation of the medullary canal for receipt of the stem of the implant.
Figure 6 demonstrates the implanted, remodeled proximal phalanx base. If there is any indication of instability or tendency of the implant to sublux, one may utilize fixation.
Figure 7 demonstrates a re-implanted proximal phalanx base with small screw fixation.
Figure 8 demonstrates fixation of the implant with an OSStaple.