This is an instructional course for a distal femoral osteotomy. Listed here are the disclosures for the author. A common indication for performing a distal femoral osteotomy is genu-valgus alignment. Correcting genu-valgus alignment with a DFO can help relieve pressure on the lateral compartment. This can help relieve symptoms of lateral compartment osteoarthritis and improve outcomes for concomitant surgeries, including lateral articular cartilage resurfacing and or lateral meniscus transplant. Additionally, a DFO can help relieve the tension on the MCL for a patient with chronic MCL injuries. The size of the alignment correction should be calculated prior to surgery. This can be done using long leg radiographs. One line should be drawn from the center of the femoral head through the medial tibial eminence. Another line should be drawn from the center of the talus to the same point of the medial tibial eminence. Next, the distance of the correction horizontally through the femur should be predicted, maintaining a 1 centimeter medial cortical hinge. The distance of the correction should now be replicated distally, starting where the two vertical lines intersect. The distance between the two vertical lines should now be measured horizontally. This is the size of the correction that should be performed. The surgical approach for the surgery is an 8 to 10 centimeter long incision located centrally over the iliotibial band. A couple anatomic landmarks, including the fibular head, the lateral epicondyle, and Gertie's tubercle are highlighted to show the location of the incision. Care should be taken to avoid cutting into the iliotibial band initially, as it will be closed after the DFO is complete. Dissection was carried down to the superficial iliotibial band, and a Cobb elevator was used to clean the surface. To expose the site for the osteotomy, a horizontal incision is made that is about 8 centimeters long and located at the lower half of the iliotibial band. A large Cobb elevator is used to bluntly dissect the vastus lateralis musculature off the posterior iliotibial band and elevate the musculature off the lateral femur. After the vastus lateralis is elevated up, it is held in place with retractors to expose the femur. Dissection using the large Cobb elevator is continued with subperiosteal dissection anterior and posterior to the femur. Distal dissection is carried out to the distal region of Kaplan's fibers. The bone should be exposed enough to properly perform the osteotomy and properly fixate the DFO plate. Fluoroscopic imaging is now brought in to visualize placement of guide pins and to verify the progression of the osteotomy. Starting at the lateral femoral cortex, two guide pins were placed at a 45-degree angle aiming towards the adductor tubercle. The first guide pin is drilled and its location is verified by fluoroscopy. The osteotome guide is then placed over the first guide pin. When the proper angle and orientation of the osteotomy guide is achieved, a second guide pin is drilled to secure the osteotomy site. Next, an oscillating saw is used to start the osteotomy. The back side of the oscillating saw blade is placed against the osteotomy guide. An initial cut is made to a depth of about 5-7 mm along the lateral femoral cortex. After the initial cut with the oscillating saw, the osteotomy is completed using a variety of osteotomes. All osteotomes are used under direct visualization to ensure the proper orientation of the osteotomy is achieved and a 1 cm medial cortical hinge is maintained. A small osteotome is first used anteriorly with penetration through the anterior cortex verified with imaging and by palpation with one's finger. A medium-sized osteotome is then used in the mid-portion of the femur. Finally, a small osteotome is used posteriorly. While the osteome advances through the posterior portion, the neurovascular structures must be protected by placing one's finger on the posterior cortex to guide the osteotome. The opening spreader device is now placed and opened until the desired degree of correction is achieved. This process should be done slowly and carefully to avoid causing a fracture. Once the desired correction is achieved, the opening spreader device is left in place for 5 minutes to allow for stress relaxation of the opposite cortex. During this relaxation period, the DFO plate should be contoured to obtain an anatomic fit on the femur. After relaxation, the opening spreader device is replaced by the opening time device, which is used to open the osteotomy site back to the desired degree of correction. A DFO plate is placed into the osteotomy site and the handle is removed from the opening time device. The opening wedges of the opening time device can remain in place until the first two fixation screws are placed. Each screw is pre-drilled and measured to the proper depth. Four total cortical screws are used to secure the DFO plate approximately and two to three total cancellous screws are used to secure the plate distally. The distal-most cortical screw is fixated first, followed by the distal cancellous screw. This is then followed by the other three cortical screws, which are fixated distally to approximately. The second cancellous screw is fixated last. Fluoroscopic imaging should be used periodically throughout fixation of the screws and at the end to verify proper placement of the plate and screws. If the opening correction is 7.5 millimeters or more, as it was in this case, bone graft should be packed into the osteotomy site. Final fluoroscopic images are taken anterior to posterior and laterally to verify proper hardware and bone graft positioning.

distal femoral osteotomy

genu-valgus alignment

lateral compartment osteoarthritis

surgical approach

fluoroscopic imaging