Distal Femoral Replacement Following an Intraoperative Periprosthetic Fracture in a Patient with Prior Bone Mulch ACL Reconstruction

Case Reports in Orthopedics
03 Apr, 2019 ,

This is a case of a 54-year-old female with a remote history of bone mulch anterior cruciate ligament (ACL) reconstruction who sustained an intraoperative comminuted bicondylar distal femur fracture during primary total knee arthroplasty. This patient was treated with a distal femoral replacement and successfully returned to her preoperative function.

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A 54-year-old Caucasian female with a history of lupus presented for elective left total knee arthroplasty following the development of osteoarthritis that had failed conservative measures. The patient had a history of previous left knee ACL reconstruction approximately 25 years ago using the Arthrotek bone mulch screw and WasherLoc system. She underwent removal of the tibial WasherLoc approximately 10 years later, in the early 2000s.
The patient was positioned supine; standard incision with a medial parapatellar arthrotomy was performed. A measured resection technique was then performed with an intramedullary guide placed in the femur. The femur was cut in 6 degrees of valgus and 3 degrees of external rotation. A size 4 femoral prosthesis was placed and noted to overhang both medially and laterally on the condyles. At this time, it was decided to downsize the femoral component. The 4 in 1 femoral cutting block was then placed back on the femur and was noted to be in contact with the bone mulch ACL screw. The bone mulch screw was located and identified in the lateral femoral condyle; a curette was used to clear the head of the screw, and it was removed. The proximal tibia was then prepared using an intramedullary guide with 3 degrees of posterior slope. A size 3 tibial component and a 9 mm poly were placed; the knee was noted to be tight in both flexion and extension. An additional 2 mm resection was performed on the proximal tibia. It was noted at this time while trying to trial the prostheses that the lateral femoral condyle was fractured. Conversion to a stemmed femoral component with a cruciate stabilizing prosthesis was attempted. The femoral canal was reamed, and the femoral box cut was made. However, during the trial, the medial femoral condyle was now noted to have a fracture as well. An intraoperative consultation with an adult reconstruction trained orthopedic surgeon was performed. Immediate surgical correction was not possible due to improper implants being presented. The femoral and tibial canals were then reamed to accept an intramedullary nail to act as a temporary internal stabilization device. The knee was irrigated and closed, and the patient was admitted to the floor. The patient was then brought back to the OR on postoperative day 3 following the index procedure. The prior incision was utilized; the wound was copiously irrigated. It was noted that due to the patient’s poor bone quality and comminution of the fractures that the only viable option was a distal femoral replacement. The distal femur was resected, the femoral canal was reamed, and a planar was used on the distal femur. A skim cut and reaming of the tibia were performed. The components were trialed. Final implants included an mm hinged femoral prosthesis and a small 1-stemmed tibial tray; a 32 mm patellar component was used, and a size 10 polyethylene was then inserted; all components were cemented. The knee was noted to be stable throughout the range of motion with good patellofemoral tracking. The surgical wound was copiously irrigated and closed. Estimated blood loss was 100 mL; no postoperative transfusion was necessary. She was able to bear weight as tolerated immediately postoperatively. The patient’s pain was controlled postoperatively, and she worked well with physical therapy and was discharged home with home health care on a postoperative day two with 3 weeks of Coumadin for venous thromboembolism prophylaxis.
The first postoperative visit was at two weeks; the patient had some swelling and quadriceps weakness, and the incision was healing well. The range of motion (ROM) was from 0-100°. At 6 weeks, she was still requiring narcotic medication; quadriceps strength was improving, ROM from 0-105°.
At 12 weeks, X-rays remained unchanged; the patient continued to have mild quadriceps weakness and was no longer requiring narcotic medications. ROM was not documented at this visit. At 6 months, ROM was 0-120°. The incision was well healed; X-rays were unchanged. The patient was doing well; however, she continued to have some residual quadriceps weakness and difficulty ambulating long distances. The patient was lost to follow-up after 6 months.