PMC7472799_01
FOP patient with multiple incurable ulcers at the right lower extremity (A). Ulcer located at the right calcaneus. Despite Intensive wound care, custom-made orthopedic shoes and targeted systemic and topical antimicrobial treatment, surgical intervention was unavoidable. Due to an ulcer on the calf (B) and proximal from the knee, a through-knee amputation was thought to be most favorable for adequate healing and to minimize tissue damage.
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F1
But, unfortunately, after years of treatment the ulcers and infections progressed to chronic osteomyelitis with multidrug resistant microorganisms (including Pseudomonas aeruginosa) in visible and palpable bone in the wound surface (Figure 1).
Anesthetic and surgical management of a through-knee amputation in an FOP patient. (A) Two nerve block catheters, i.e., the femoral (F) and the sciatic nerve block catheter (S), which were both already placed and tested at the preoperative day. The picture shows the antero-lateral aspect of the patient's right leg. The femoral nerve block catheter is positioned at the ventral aspect of the leg, whereas the sciatic nerve catheter is positioned at the lateral aspect of the leg. (B) The patient was carefully positioned on the theater table to prevent any tissue damage that might cause FOP disease activity. The positioning was challenging due to ankylosis in the hips and knees, resulting in the position shown in the picture. (C) Surgical procedure was performed carefully to minimize tissue damage that might cause a flare-up. (D) The skin flap and gastrocnemius muscle transposition were designed to opposite each other to prevent overlapping scars and minimize the chance of fistula formation due to expected wound healing issues. Lateral of the stump an area of necrosis developed, but healed with supportive care.
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F2
Two peripheral nerve block catheters were placed at the femoral and sciatic nerve on the pre-operative day (Figure 2A). The positioning of the patient was challenging, due to complete immobility of the major joints (Figure 2B). While most ligaments and the capsule of the knee joint were ossified, no abnormalities were observed in the knee joint itself (Figure 2C). The gastrocnemius muscles were transposed forward and fixed near the patella region to cover the bone, to provide a vascularized bed and to protect underlying tissues in case of a future prosthesis (Figure 2D). The patient developed partial skin necrosis laterally of the stump (Figure 2D), but healed with supportive care.
Axial Low dose CT-images at the level of the distal femur of a patient prior to and after a through-knee amputation of the right leg. (A) Eight months prior to the surgery. (B) Twelve months after the surgical procedure. Minor HO formed (4cc) on the right side posterior to the lateral femoral condyle (red arrow). FOP, fibrodysplasia ossificans progressiva; HO, heterotopic ossification; CT, computed tomography.
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F3
A follow-up [18F]NaF PET/CT-scan was obtained 8 weeks after surgery, revealing minimal HO formation (4 cc) at the base of the femur (Figure 3).