RECONSTRUCTION 2023, Jan, 08 | 12:00 am

Knee Arthrodesis with an Intramedullary Nail After Failed Total Knee Arthroplasty

Contraindications

  • Contraindicated for patients with contralateral above-knee amputation.

  • Relatively contraindicated for patients with ipsilateral hip or ankle degenerative arthritis.

 

Knee Arthrodesis with an Intramedullary Nail

 

Indications

  • Limb salvage after failure of delayed exchange and re-implantation of infected total knee arthroplasty (TKA)

  • Loss of extensor mechanism

  • Bone loss after failed repeat re-implantation or posttraumatic osteoarthritis

     

    P ITFALLS

    • Arthrodesis does not guarantee eradication of infection. Any infection must be successfully treated prior to arthrodesis surgery. Most commonly this involves staged débridements, including antibiotic-eluting cement spacers.

       

    • This procedure may provide union, pain relief, and a stable limb for ambulation, but the absence of knee motion introduces some practical drawbacks.

     

  • Neuropathic joint, especially after failed TKA

  • Inability to maintain knee extension after previously failed TKA

  • Degenerative knee disease and extreme obesity

    Examination/Imaging

  • Arthrodesis should be preceded by any or all necessary treatments for infection (removal of implants, cement debris, and necrotic tissue) and implantation of an antibiotic cement spacer.

  • Anteroposterior (AP) and lateral plain films of the affected knee and entire lower extremity from hip to ankle are important.

  • The length of the femur and the tibia must be determined, and any unusual bowing or canal abnormalities must be identified.

    Controversies

    • The most effective method of surgical arthrodesis is debatable, but the highest reported fusion rates are with an intramedullary nail.

    • Additional techniques previously described include external fixation and plate fixation.

    • Spread of infection along the nail proximally or distally has led some authors to recommend other techniques for fusion (a short intramedullary nail, plates and screws, external fixation). A variety of published reports do not report spread of infection as a significant complication. However, if infection recurs in the knee, a short intramedullary nail can be extremely difficult to remove once arthrodesis has been achieved.

    • The final nail position should be within 3–5 inches above the tibial plafond.

     

    • The length of the femur and the tibia can be obtained from plain radiographs with a measuring template in place.

    • Alternatively, a computed tomography (CT) scan from the tip of the trochanter to the distal femur and then from the proximal tibia to the distal tibia can be used (Fig. 1).

  • CT scans are also helpful for identifying the narrowest portion of isthmus of the tibia, which is the dimension that limits the size of the nail.

    • The arthrodesis nail should extend from the tip of the greater trochanter to well within the isthmus of the distal tibia.

    • If there is distraction at the level of the knee, this amount of length should be taken into consideration with the final nail length.

  • Coronal CT scans can be used to identify the narrowest portion of the femoral canal (Fig. 2A) and the tibial canal (Fig. 2B) for measurement of intended nail diameter.

     

    Knee Arthrodesis with an Intramedullary Nail

     

     

     

     

     

     

     

     

    475.99 mm

     

    361.78 mm

     

    371

     

    FIGURE 1

     

    A

    FIGURE 2

     

    B

     

     

    372

     

    Treatment Options

    • External fixation across the knee

    • Internal fixation with plate and screw construct

    • Short intramedullary nail device

     

    Knee Arthrodesis with an Intramedullary Nail

     

    Surgical Anatomy

  • Femoral and tibial canals must be without obstruction, such as fracture callus.

    • An osteotomy may be necessary to open the obliterated canal in the region of the fracture callus or to correct any deformity that would preclude successful nail placement.

    • The preoperative radiograph in Figure 3 demonstrates a small deformity of the distal femur. This deformity did not affect the procedure, but a more significant deformity would add to the complexity of the arthodesis.

  • The femoral canal must be free of previously placed hardware or prostheses.

     

    P EARLS

    • The lateral position facilitates guidewire insertion, reaming, and nail placement for the femur, but makes it slightly difficult for the tibia.

       

      P ITFALLS

    • Insufficient proximal sterile field and exposure at the level of the trochanter will increase the risk for contamination during the procedure.

     

    Positioning

  • A radiolucent operating room table is required, with a single draped C-arm fluoroscopic unit.

  • The patient is placed in the lateral (Fig. 4) or semi-lateral (“sloppy” lateral) position. Positioning devices are used both anteriorly and posteriorly.

  • Prepping and draping resemble that for a hip arthoplasty procedure. However, the affected limb should be draped free from the gluteal region to the distal tibia to optimize positioning and maneuverability while the guide, reamer, and nail are passed.

  • The leg is internally rotated to obtain radiographic views in multiple planes as needed.

    Equipment

    • Provide ample area at the level of the patient’s torso, and eliminate the use of an ipsilateral arm board to enhance sterile field space for passage of the guidewire, reamers, and substantial nail length.

     

    Portals/Exposures

  • This procedure can be carried out in three different ways.

    • The canals can be canulated from the knee. This involves retrograde guidewire placement in the femur, and anterograde guidewire placement in the tibia. This is our preferred method.

      Controversies

      • A tourniquet is not typically used for this procedure.

       

    • The tibia can be exposed from the knee joint and the greater trochanteric entry site can be exposed through a typical incision at the greater trochanter similar to traditional anterograde femoral nailing.

    • For both of these techniques, the femur and tibia are individually reamed in an anterograde fashion. Standard-length reamers are sufficient.

       

       

       

       

       

      Knee Arthrodesis with an Intramedullary Nail

       

       

       

      373

       

      FIGURE 3

       

      FIGURE 4

       

       

      374

       

       

      P EARLS

      • Fluoroscopy with a percutaneous guide pin may be helpful to localize the proximal greater trochanter in obese patients or for poorly defined anatomy.

         

        P ITFALLS

      • Excessive medial femoral entry may increase the risk of femoral neck fracture and/or femoral head osteonecrosis.

         

      • Use of previous knee incisions may lead to skin necrosis. A previous longitudinal incision should be utilized whenever possible.

       

      Knee Arthrodesis with an Intramedullary Nail

       

    • If no knee exposure or removal of a cement spacer at the knee is necessary, the entire procedure can be performed in an anterograde fashion. This is more difficult and requires the guidewire to successfully cross the knee joint in a blind fashion. Fluoroscopic surveillance is particularly important, and extra-long reamers are required.

  • For all three techniques, an extra-long guidewire is necessary to have the wire in proper position to guide correct passage of the nail.

    Procedure

    Step 1

  • Perform an anterior approach to the knee joint to remove any spacer block (Fig. 5) and to identify the distal femur and proximal tibial metaphyseal regions.

    Instrumentation

    • An awl or small guidewire with reamer may be used to open the proximal femur, once optimal position has been established.

     

    • The guidewire should then be easily advanced in a retrograde fashion up the femur into the greater trochanteric region (Fig. 6A), as monitored fluoroscopically (Fig. 6B). Once it gets to the region of the greater trochanter in a safe position (not in the femoral neck), it is gently advanced through the trochanter with gentle mallet blows. It can be retrieved using a small incision in the buttocks region (Fig. 6C).

       

      P EARLS

      • Remove ligament and capsular attachments from the distal femur to aid in alignment during wire and nail passage.

         

        P ITFALLS

      • Poor bone quality in the distal femur may allow the guidewire to penetrate the cortex, especially anteriorly, prior to passage into the knee joint; pass the wire with care, and under fluoroscopic visualization if necessary.

         

      • The tibia should be reamed first. The tibial diameter is the diameter that will determine the rod diameter. The tibia should be reamed line-to-line or 1 mm greater than the intended nail diameter.

       

    • Alternatively, if the guidewire cannot be placed in a retrograde fashion, a standard trochanteric approach is made and the proximal femur is canulated beginning with an awl or starting reamer over a guide pin.

  • The guidewire is passed into the femoral canal and retrieved at the knee joint.

  • The tibial canal can be reamed in an anterograde fashion with or without a guidewire. The tibia should be reamed well into the diaphysis, while keeping at least 8 cm above the distal tibial margin.

  • With the guidewire in place, the femoral canal is

    reamed (anterograde) to 2 mm larger than the intended nail diameter.

  • The guidewire is taken across the knee joint, introduced into the proximal tibia, and passed to the distal one third of the tibia.

     

     

     

     

     

     

     

     

    Knee Arthrodesis with an Intramedullary Nail

     

     

     

    375

     

    FIGURE 5

     

    A

     

    B

     

    C

    FIGURE 6

     

     

    376

     

    Instrumentation/ Implantation

    • Once reaming of both bones has been performed, a long guidewire is placed so that it is controlled at the hip and then advanced into the tibial distal metaphyseal region. This should be confirmed fluoroscopically.

    • Measurement of the intended nail length is performed. Knowledge of the guidewire length (measurement by subtraction), residual gapping at the knee joint, and preoperative measurement are all useful guides for nail length selection.

     

    Knee Arthrodesis with an Intramedullary Nail

     

    Step 2

  • Use of a long intramedullary nail with a 5° valgus bend and flexion angle of 5° is preferable.

  • With the guidewire in place in the femur and tibia, the nail is introduced in the greater trochanter.

  • Gentle blows should advance the nail into the femur diaphysis. This should be viewed fluoroscopically.

  • If the nail does not easily pass into the femur, the femur can be reamed an additional 1 mm. This will not compromise fixation because a proximal interlocking screw will be used.

  • Once the nail emerges from the distal femur, the tibia is held in the desired position, especially rotational position, as the nail is advanced into the tibial metaphysis (Fig. 7A).

  • Ensure that the tibia is positioned under the femur on both the AP and lateral fluoroscopic views

    Controversies

    • The proximal tibia may be prepared with a convex reamer and the distal femur may be prepared with a concave reamer. This will involve greater limb shortening and we do not routinely perform this.

    • It is important that any residual gapping at the knee joint be taken into account for the selected nail length. Unless the bone ends are approximated (which is difficult to achieve) or a structural bone graft is used, the gap will slowly close when the patient bears weight on the extremity. Because a proximal interlocking nail is used, the tibia will gradually move proximally over the nail.

     

    (Fig. 7B).

     

     

     

    A

     

     

     

    FIGURE 7 B

     

    377

     

     

    P EARLS

    • The tibia should be reamed to the diameter of the nail, or, if passage is difficult, an additional 1 mm.

       

    • Correct rotation of the lower extremity should be ensured prior to final nail seating in the tibia. This must be done visually, looking at the distal femur, proximal tibia, and foot position.

       

    • Careful attention to the rotation and angular position of the tibia is necessary as the nail enters the tibial metaphysis and diaphysis.

       

      P ITFALLS

    • Without proper visualization and alignment across the knee joint, the nail may fracture the distal femur or proximal tibia when passed at those levels.

     

    Knee Arthrodesis with an Intramedullary Nail

     

  • Once the rod enters the proximal tibial diaphysis, the tibial rotation must be finalized. As the rod enters the tibial diaphysis, the rotational position becomes fixed.

    Step 3

  • Proximal interlock of the nail is performed near the greater trochanter (Fig. 8A and 8B).

 

Controversies

  • Some authors recommend bone apposition or grafting of any distraction between the femur and the tibia. In this case, a distal interlocking screw can be used and a nail compression device can also be utilized.

  • We believe, however, that the femoral and tibial bone at the fusion site need not be freshened up or even grafted. Some distraction of the bone ends is permissible, with subsequent weight bearing providing the necessary compression for union.

  • We have intentionally not recut or fashioned the bone ends to provide more bone contact. Instead, we prefer the gradual compression that occurs with weight bearing to achieve the proper amount of bone contact necessary for fusion to occur.

 

 

Instrumentation/ Implantation

  • Seat the nail such that the proximal tip is flush with the greater trochanter, for correct placement of the proximal interlocking screw.

 

 

Controversies

  • Femoral-tibial canal diameter mismatch may lead to use of a smaller nail. This has not been a problem, in our experience, with the use of a proximal interlocking nail.

 

A

 

 

P EARLS

  • Make a final assessment of limb rotation and arthrodesis site bone approximation.

 

 

FIGURE 8 B

 

 

 

378

 

 

P EARLS

  • Union, defined radiographically as bridging bony trabeculae spanning the fusion site, can be observed on AP and lateral views. This is usually first seen at the posterior knee aspect on the lateral radiograph.

     

    P ITFALLS

  • Recurrent infection

  • Lower extremity shortening

  • Implant failure and migration

  • Blood loss

  • Ipsilateral fracture

  • Nonunion/malunion

  • Nail migration

 

Controversies

  • There may be some resultant loss of valgus knee alignment even with a bowed intramedullary nail.

  • Management of lower extremity shortening can be challenging. Once fusion is achieved, leg lengthening over the intramedullary nail is an option.

  • Shortening greater than 2 cm will necessitate modified shoes and/or possibly an ankle-foot orthosis.

 

Knee Arthrodesis with an Intramedullary Nail

 

A

 

 

 

B

FIGURE 9

 

  • Final alignment and fusion site distraction are assessed radiographically (Fig. 9A and 9B).

  • Coverage of the proximal nail hole is left to the discretion of the surgeon.

    Step 4

  • Close the incision over the trochanter and anterior knee.

     

    379

     

    Knee Arthrodesis with an Intramedullary Nail

     

    Postoperative Care and Expected Outcomes

    • Patient advanced to immediate weight bearing as tolerated.