Distal Femur Resection

Megan E. Anderson

Operative Indications

Malignant tumors of the distal femur—wide resection (Figure 42.1)

Alternative Treatments

Rotationplasty
Above-knee amputation

Positioning (Figure 42.2)

Supine
Pad prominences (cranium, sacrum, contralateral heel)
- Long surgery and low body weight often contribute to high risk of decubitus ulcers
Small roll behind involved hip to position limb in slight external rotation, nearly neutral
Assess leg lengths in this position to restore this with reconstruction
- Can place electrocardiogram (ECG) electrode on contralateral medial malleolus to aid in palpating under drapes
Gel bump to rest foot against with the knee in flexion
Drape entire extremity from lower abdomen and femoral triangle to toes

Figure 42-1 ▪ Right distal femur osteosarcoma. A, X-ray showing destructive, permeative lesion with immature bone formation within lesion. B, Magnetic resonance imaging (MRI) T1 sequence without fat saturation in a coronal plane showing marrow (fatty bright T1 signal) replacement by the tumor (hypointense dark signal). C, MRI proton density sequence in an axial plane with tumor extending from within the bone to lift the periosteum and even extend beyond the periosteum. Note the position of the tibial and peroneal divisions of the sciatic nerve as well as the popliteal vessels. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-2 ▪ Illustration of setup and positioning for distal femur resection. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Surgical Approach (Figure 42.3)

Anteromedial
Extensile
Length of incision from below tibial tubercle to 2 to 5 cm proximal to planned bone cut (depending on thickness of soft tissue envelope) (Figure 42.4)

Technique in Steps

Deeper Dissection

Incise fascia over vastus medialis (Figure 42.5) ( Video)
Keep intact the entire length of wound for later repair
Separate from retinaculum in the distal portion of wound (Figure 42.6) ( Video)
Lift medial fascia away from vastus medialis (Figure 42.7) ( Video)
Finger dissection with cautery for perforating vessels
Start to release vastus medialis from medial intermuscular septum (Figure 42.8) ( Video)
Extent of soft tissue mass dictates proximity of dissection on the septum to the involved portion of the femur

Flex the knee to allow relaxation of neurovascular structures (Figure 42.9)

Figure 42-3 ▪ Right lower extremity prepared and draped for distal femur resection with incision drawn. Longer hatch mark is level of planned bone resection based on preoperative magnetic resonance imaging (MRI) measurements. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-4 ▪ Right distal femur osteosarcoma magnetic resonance image (MRI) in coronal plane with T1 sequence demonstrating planned resection (line) above intramedullary tumor and periosteal reaction. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-5 ▪ Incising fascia over vastus medialis. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-6 ▪ Separate retinaculum from fascia for double-layered repair later. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-7 ▪ Lift medial fascial flap off vastus medialis. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-8 ▪ Release vastus medialis from intermuscular septum. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-9 ▪ Flex the knee and leave posterior structures free from any pressure. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-10 ▪ Release the distal adductor tendon to enter Hunter canal. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Figure 42-11 ▪ Release the proximal medial gastrocnemius tendon and muscle to enter the popliteal fossa. (Courtesy of Children’s Orthopaedic Surgery Foundation.)

Leave the posterior thigh and knee free
Enter Hunter canal with release of adductor tendon insertion (Figure 42.10) ( Video)
Release medial gastrocnemius tendon origin to enter the popliteal fossa (Figure 42.11) ( Video)
Tendon is usually melded with posteromedial capsule, so if extra-articular resection is needed, release tendon more distal after separating from capsule