Technique
The patient is positioned on a radiolucent table, and a mobile fluoroscopy unit is available. A tourniquet is applied to the upper thigh but typically is not inflated during the percutaneous hardware removal portion of the operation. It is crucial to have information on retained implants so the correct screwdrivers for screw removal can be selected. In addition, provisions for stripped screws should be made. In each of the 3 cases we managed, the Synthes Screw Removal Set was available. Presence of an implant system known to have problems with cold welding of screws (eg, Less Invasive Stabilization System; Synthes) may necessitate additional preparations, such as making conical extraction devices available.1
After preoperative administration of antibiotics, the surgeon typically removes only those proximal tibia screws that are preventing insertion of the tibial base plate. Fluoroscopic guidance is used to locate these screws and then remove them with percutaneous stab incisions. (Retained plates are not removed.) The exact method of localizing and removing the screws percutaneously is crucial. A small stab incision is made in the dermal layer. The number of stab incisions to be made depends on the number of screws to be removed. One small incision is needed for each screw hole. Occasionally mobilizing the skin and redirecting the screwdriver in the deep tissues can allow 2 screws to be removed through a single skin wound. The screwdriver head can be inserted through the muscle and fascial layers without the need for deep dissection. The plate is then felt with the screwdriver and the screw head located. It is very important that the screw head be adequately engaged to prevent stripping. The surgeon should not rush this step. The C-arm can be helpful here. Fluoroscopy not only can guide the screwdriver to the screw hole but can confirm the screwdriver is at right angles to the plate, not oblique. Only when the surgeon is completely satisfied that the screw head is well engaged should the attempt to back out the screw be made. If the screw strips, the screwdriver can be removed, and an attempt can be made to insert a percutaneous stripped screw removal device.1 If this fails, then the technique must be abandoned for a more traditional approach.
Plating complex tibial plateau fractures through a separate posteromedial approach is now popular.2 The deep location and screw orientation of posteromedial hardware make percutaneous removal unfeasible. In these cases, a separate posteromedial incision may be needed—usually posterior enough so it minimally compromises the anterior soft tissues. The incision typically uses the old posteromedial surgical scar but may not need to be as large as the original approach, as only selected screws need be removed. The saphenous neurovascular bundle may still be at risk, depending on the location of these incisions. The plate is not removed.
After the necessary screws are removed, the tourniquet can be inflated, if desired. The total knee arthroplasty (TKA) then proceeds in usual fashion through a single incision and a medial parapatellar arthrotomy.
Results
Between January 2009 and February 2014, Dr. Georgiadis converted 3 cases of retained tibial hardware and severe knee arthrosis to a TKA in a single operation. These cases were reviewed after Institutional Review Board approval was obtained. One patient underwent a closing-wedge high tibial osteotomy 14 years earlier, and the other 2 sustained tibial plateau fractures. Clinical details of the 3 cases are presented in the Table.
In 2 of the cases, anterolateral surgical scars were present. New, separate percutaneous stab incisions were used to remove screws, which meant less of the original skin incision could be used for the TKA (Figures 1A, 1B).
In the third case, involving multiple plates, a similar strategy was used, but an additional small posteromedial incision was required (Figures 2-5). The TKA then proceeded through a new midline incision. This case was performed for tibiofemoral arthrosis in the setting of an acute distal femur fracture, but this had no bearing on the technique.
Tibial base plates were inserted in the usual manner. Length and type of tibial stem were left to the discretion of the surgeon. There were no changes from the usual surgical technique. All patients went on to routine, uneventful wound healing. Follow-up ranged from 10 months to 59 months.