For the general method see Section 56.1.
ANAESTHESIA If possible, anaesthetize the patient, and then turn him onto his face, as in ’Primary Anaesthesia’ Section 16.12.
METHOD Apply a tourniquet. Cut a long, broad anterior flap, and a shorter posterior one, as in A, Fig. 56-12. Mark these out with his knee flexed.
Start the anterior incision on the posteromedial side of his knee just proximal to the joint line. Extend it 10 cm below his tibial plateau, and then curve it proximally to end at a point just proximal to the joint line on the posterolateral side of his knee.
Start the posterior incision at the origin of the anterior one. Extend it 5 cm distal to the popliteal flexor crease. Then curve it proximally to meet the anterior incision.
CAUTION! The anterior flap must have an adequate blood supply. If it might not, cut two equal medial and lateral flaps beginning just above the insertion of the patellar tendon.
Dissect the deep structures on the medial side of the patient’s knee. Expose the tendons of his medial hamstrings and cut them as far distally as you can.
Find, tie and cut the main trunk of his popliteal artery just distal to its superior genicular branches. These arise high in the popliteal fossa. Tie his popliteal vein. Reflect the posterior flap, cut the fascia, and dissect downwards in the midline between his medial hamstrings on one side and his lateral ones on the other.
Cut the deep fascia along the border of the anterior skin flap. Cut his patellar tendon as close to its insertion into his tibia as you can. Reflect his skin, his fascia, his patellar tendon, and the synovial membranes as a single flap (B).
On the lateral aspect of his knee, expose and divide his biceps tendon and his iliotibial tract.
Find his common peroneal nerve below his biceps tendon, as it goes towards the head of his fibula. Cut it proximally so it retracts above the level of the amputation.
Reflect the short posterior flap and cut his collateral and cruciate ligaments near their attachments to his femur (C). Find his tibial nerve, draw it gently into the wound, and cut it proximally (D).
Dissect the posterior joint capsule from his tibia. Strip the heads of his gastrocnemius from his femur, and remove his leg.
CAUTION! (1) The popliteal vessels lie very close to the posterior surface of the knee joint. If you have already tied them high up, they should not be in danger. (2) There is no need to disturb the articular cartilage of his femur, or to remove his patella.
Draw his patellar tendon posteriorly through the intercondylar notch of his femur, and sew it to the ends of his hamstring tendons with several interrupted sutures (E).
Stitch his sartorius and his iliotibial tract to the fascial part of his extensor mechanism. Remove the medial and lateral tubercles of the lower end of his femur. Remove the tourniquet, control bleeding, drain and close the stump as usual.
Prepare to fit a permanent prosthesis in 6 to 8 weeks.
