Surgical Procedure for Toggle Pin Method of Hip Luxation Repair
Figure 1: This method of repair is best accomplished through a craniolateral approach to the hip with caudal retraction of the femur to allow for complete visualization, exploration, and appropriate debridement of the acetabulum. After debridement of impinging tissue, clot, and remaining round ligament in the acetabulum, a hole is drilled completely through the medial wall of the acetabulum centered in the acetabular fossa. Use of an A/O type, hand-held drill sleeve will simplify drilling while protecting the femoral head. The diameter of the hole must be large enough for the toggle pin and suture combination chosen. A 3.2mm toggle pin will require at minimum a 3.5mm hole. However, a 4.0mm hole or larger is often needed if using heavy monofilament line. For the 4.0mm toggle pin, a 4.5mm or 5.5mm drill bit is recommended. The toggle pin-suture combination should be easily inserted through the acetabular drill hole. If difficulty is encountered, the acetabular hole should be enlarged with a larger drill bit.
Figure 2: The aiming device is used to drill a femoral tunnel for the suture. The aiming device is placed so the tunnel is drilled from the subtrochanteric area of the lateral femur to the fovea capitis of the femoral head. It is helpful to have a surgical assistant at this time. The 3.5mm drill bit is the most common drill bit utilized and also the minimum hole diameter used with the suture passer. When drilling of the femoral tunnel is nearly complete, it is advisable to remove the aiming device and complete the drill hole by hand. This eliminates potential damage to the drill bit.
Figure 3: The suture used for repair is passed once through the hole in the toggle pin creating a simple loop. The toggle pin is held at one end using large needle holders, Kelly forceps, or a similar instrument. The suture is pulled tight along the sides of the toggle pin so each strand seats within the toggle pin grooves. The toggle pin is then visually started into the acetabular drill hole and inserted as far as the instrument will allow. The instrument is removed, and the blunt end of the suture passer is used to push the toggle pin completely through the acetabular drill hole. (If this step seems to require excess force, it is likely that the acetabular drill hole is not large enough to accommodate the diameter of the toggle pin-suture combination used.)
Figure 4a: The ends of the suture are spread and tensioned to pull the toggle pin tight against the medial wall of the acetabulum. The toggle pin is tested for secure seating within the pelvic canal. The suture is then pushed or pulled through the femoral canal to exit the lateral femur. The suture is tensioned while the femoral head is reduced into the acetabulum.
Figure 4b: Appropriate reduction is verified and the ends of the suture are tied over another toggle pin or a suture button. Alternatively, another small bone tunnel can be drilled in the lateral aspect of the femur to allow one of the suture strands to be passed through and then tied to the opposite strand. The hip should be appropriately reduced and firmly seated; however, do not over-tighten the suture by placing excess tension on it. This will adversely effect hip joint range of motion and will cause the suture to fail prematurely.