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The StayFuse implant may improve the results of hallux interphalangeal joint fusion and hammertoe procedures, as well as eliminate pin tract infection and reduce post-op complications. This author discusses how to best use the device for optimal patient outcomes.
Fusion of the hallux interphalangeal joint is a procedure that can provide symptomatic relief of a painful arthritic hallux, a contracted hallux hammertoe or relief of a pressure area from a callus or ulcer. There are numerous techniques described in the literature to achieve fusion including K-wires, screws, compression staples and dissolvable implants.
However, a new implant allows for internal fixation with a component that easily screws into the phalanx and snaps together to provide rigid internal fixation that is equal to or stronger than a standard 4.0 stainless steel screw.
|  | | Once the StayFuse’s component snaps into the phalanx, it provides rigid internal fixation that is equal to or stronger than a 4.0 stainless steel screw. |
The purpose of the StayFuse implant is to enhance the results of procedures for small bone fusion, hammertoes, fractures and other digital deformities. The implant can potentially reduce postoperative visits and patient discomfort. The implant will eliminate the risk of pin tract infections. The gold-colored implant is specifically indicated for use in the hallux interphalangeal joint of the foot for fusion of the great toe or management of a fracture of the great toe.
The device consists of two components. The “mid” half possesses a protruding connection feature and the “prox” half has an internal connection feature. The bone-mating portion has a cancellous type thread with a self-drilling and tapping tip. Distal to the screw tip is an external hex that is engaged with a hex driver. The hex driver offers a dual purpose. One end is shaped for pre-drilling the bone and the other end features an internal hex for inserting the implant. The purpose of the hex driver is to interface with a chuck of a standard cannulated drill.
|  | | Surgeons may find success using the StayFuse for hallux interphalangeal joint fusions, fusion of the great toe or fracture management of the great toe. It allows for internal fixation due to a component that screws into the phalanx. |
The device is designed to stabilize and hold the hallux interphalangeal joint in alignment during the healing process. Its intention is not to withstand the stresses of full weightbearing during the healing process. Also, surgeons should not use the device in the presence of degenerative bone processes such as tumors, osteolysis, severe osteoporosis and active or latent infections near the implant site.
Understanding Proper Implant Technique
The proper technique for insertion of the implant involves evaluation of the length of the bones to be fused and the desired length when fusion will be completed. One would then resect the appropriate amount of bone from the proximal and distal aspects of the hallux interphalangeal joint. Take care to ensure the cut is flat and perpendicular to the bone. The surgeon must then check to ensure that two flat opposing surfaces are present. Then use a broach to approximate the position where the guide hole is drilled. Utilize the pilot-hole driver bit on the handle included in the set or on a power driver to create a guide hole in the bones to be fused. Be certain that the driver is aligned at 90 degrees to the bone surface. Keep it central in the bone to allow maximum bony approximation.
Insert the prox end first to avoid having to work around the protruding connection mechanism feature of the mid part. Drive the prox half of the StayFuse device into the bone until the screw spins off the hex of the insertion device and countersinks flush with the resected bone surface.
|  | | Here one can see the post-op AP view of the StayFuse implant. |
One would use the same technique for the mid half into the opposing bone. Grasp the distal and proximal portions of the hallux and retract them, separating the two screw ends. Insert the mid end into the prox component. With firm pressure, “snap” the mid end progressively into the prox end until the bone is approximated. Perform closure in the usual manner. Postoperatively, keep the patient in a guarded weightbearing device such as an IPOS shoe, CAM Walker or cast for a period of six weeks or at a point where bony fusion occurs.
Case Study: Treating A Patient With A Painful Hallux
The case presented is a 65-year-old male with a history of cerebral palsy, hypertension and chronic renal dysfunction. He had undergone a bunionectomy and hammertoe fusion to the lesser digit many years prior. The patient developed a painful hallux hammertoe with a need for surgical correction.
The chosen procedure was a hallux interphalangeal fusion with the gold StayFuse device. The surgeon kept the patient in guarded weightbearing in a CAM Walker for six weeks and he progressed back to his normal shoe gear at week six. He went on to a successful bony fusion as well as a pain-free straight hallux toe. |
