Knee Reconstruction

Clinical Presentation

A 29-year-old white male had significant left proximal tibia bone loss and open knee injury as a result of an explosive injury in a foreign country. The orthopedic injury was stabilized initially after debridement in an overseas military hospital. He was subsequently transferred to the orthopedic trauma service of our hospital for more definitive treatment. After admission, an aggressive orthopedic debridement was performed by our orthopedic trauma service. The open facture wound was temporally covered with a vacuum-assisted closure (VAC) dressing after an external fixator placement and patella reconstruction. The plastic surgery service was consulted for soft tissue coverage of this large upper tibial wound that extended to the knee ( Fig. 42.1 ).

Operative Plan and Special Considerations

The potential definitive orthopedic management and soft tissue coverage was performed 8 months later after the initial injury. Because of the complexity of the composite injuries, the patient was taken to the operating room by the plastic surgery service for more definitive bony and soft tissue debridement. A plan for definitive soft tissue coverage along with the orthopedic reconstruction would be made at that time. Based on an intraoperative assessment, a successful soft tissue reconstruction could be performed after appropriate bony reconstructions for limb salvage. Because of the size of the upper tibial and knee wound and the long pedicle of the flap, a free latissimus dorsi muscle flap could be selected to provide adequate soft tissue coverage of the wound. However, good recipient vessels for a successful free flap reconstruction remained undetermined until direct intraoperative exploration would be carried out. If not feasible, the popliteal vessels could be explored as potential recipient vessels for free flap transfer and vein grafts could be avoided.

Operative Procedures

Under general anesthesia, the patient was placed in the supine position and the descending genicular vessels around the left knee were explored to see whether they could be used as recipient vessels. Unfortunately, these vessels appeared to be too small as recipient vessels for successful end-to-end microvascular anastomosis.

With the patient in a near prone position (not in a true prone position because of the external fixator), the popliteal vessels were explored as recipient vessels for microvascular anastomosis. A lazy S skin incision was made in the popliteal fossa. Once the dissection was through subcutaneous tissue, both the popliteal artery and vein were dissected free and prepared under a loupe magnification.

The left latissimus donor was harvested next. An oblique incision was made down to the fascia. After identifying both medial and lateral borders of the latissimus muscle, the muscle was divided using electrocautery medially, inferiorly, and laterally. Under direct vision, the latissimus dorsi muscle flap was elevated from the chest wall but the serratus muscle was left intact. Once the serratus branch of the artery had been divided, the latissimus dorsi muscle attachment to the humerus was also divided using electrocautery. The pedicle dissection was performed under direct vision with proper retraction. The thoracodorsal nerve was divided and the thoracodorsal artery and vein were both divided after further pedicle dissection from the axillary vessels.

The pedicle vessels of the muscle flap were prepared under loupe magnification. The pedicle artery and vein were irrigated with heparinized saline solution. The portion of the muscle flap including the pedicle was tunneled through the skin of the knee and the major portion of the muscle flap was temporarily placed into the knee and upper tibial wound. Both microvascular anastomoses to the popliteal vessles were performed under loupe magnification because of the unique position of the patient. End-to-side arterial and venous microanastomoses were performed with interrupted 8-0 nylon sutures. Once all the clamps had been removed, the flap was instantly perfused with good Doppler signals ( Fig. 42.2 ). The major portion of the latissimus dorsi muscle flap was then inset into the upper tibial and knee wound with multiple interrupted horizontal mattress sutures over a closed suction drain. Split-thickness skin grafts were placed over the muscle flap and secured with multiple skin stapes ( Fig. 42.3 ).

The left back flap donor site was closed after placing two drains into the donor site under the skin. The deep dermal layer was approximated with several interrupted 2-0 PDS sutures. The skin was then closed with 3-0 Monocryl in running subcuticular fashion.

Follow-Up Results

The patient did well postoperatively without any complications related to the free latissimus dorsi muscle flap reconstruction. Skin grafts over the muscle flap initially took. He was discharged from hospital on postoperative day 14. All drains were removed during subsequent follow-up visits. The left knee and upper tibial free flap reconstruction site healed well.

Management of Complications

The skin graft over the distal portion of the muscle flap had not healed well by postoperative 3 weeks. There were no issues related to the muscle flap. The patient was taken back to the operating room and underwent an additional skin graft procedure without difficulty ( Fig. 42.4 ). The skin graft site over the muscle flap healed well after the subsequent operation ( Fig. 42.5 ).

Final Outcome

Autologous bone grafting for the definitive fracture healing was performed 3 months later after the flap was elevated by the plastic surgery service ( Figs. 42.6 and 42.7 ). The bone graft procedure went well and the fracture site healed. The knee and upper tibial free flap reconstruction site healed well with good contour and minimal scarring even after the second flap elevation. There was no recurrent infection under the flap. The patient has some stiffness in his left knee but he has resumed his normal activities and been routinely followed by the orthopedic trauma service ( Fig. 42.8 ).