In-Service Exam
Lower Extremity - 2003





A 29-year-old woman is brought to the emergency department one hour after sustaining a traumatic avulsion amputation at the level of the proximal third of the lower leg. On examination, the tibia is exposed, and there is not adequate soft tissue for coverage of the bone. The amputated part has been appropriately preserved; examination shows extensive injury in the middle third of the leg but no evidence of injury in the distal third or the foot.

In order to provide the best functional outcome in this patient, which of the following is the most appropriate management?

(A) Above-knee amputation
(B) Immediate coverage of the exposed tibia with a reverse rectus femoris flap
(C) Immediate coverage of the exposed tibia with a filet-of-foot free flap
(D) Immediate coverage of the exposed tibia with a latissimus dorsi muscle flap and split-thickness skin graft
(E) Microvascular replantation of the amputated leg with 12 cm of bone shortening to allow for complete soft-tissue coverage

The correct response is Option C.

The most appropriate management is immediate coverage of the exposed tibia using a filet-of-foot free flap. Free tissue from the amputated foot can be transferred to provide appropriate soft-tissue coverage without additional donor site morbidity. The dorsalis pedis artery and/or posterior tibial artery supply vascularity to the flap, and the tibial nerve provides sensory innervation.

Above-knee amputation should be considered only as the last possible option. The energy required for ambulation in a patient with an above-knee amputation is much greater than in a patient with below-knee amputation.

The reverse rectus femoris flap is not based on a distal pedicle; thus, it should not be used in a patient in whom knee extension must be preserved.

A latissimus dorsi flap and split-thickness skin graft could be used for coverage if the amputated part were injured and unavailable as a donor site; however, in this patient there is no evidence of trauma distal to the lower third of the leg.

Microvascular replantation cannot be performed in a patient who has sustained an avulsion amputation. In addition, bone shortening of greater than 10 cm would ultimately result in an abnormal gait.

References
1. Kasabian AK, Glat PM, Eidelman Y, et al. Salvage of traumatic below-knee amputation stumps utilizing the filet of foot free flap: critical evaluation of six cases. Plast Reconstr Surg. 1995;96:1145-1153.
2. Mathes SJ, Nahai F, eds. Reconstructive Surgery. New York, NY: Churchill Livingstone, Inc; 1997:1233-1245.
3. Thorne CH, Siebert JW, Grotting JC, et al. Reconstructive surgery of the lower extremity. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;6:4029-4092.

A 34-year-old motorcycle driver sustains a Gustilo type IIIB open fracture of the right tibia. At the time of debridement, stabilization, and coverage of the wound, there is a superficial infection of the tibia. Low-pressure pulse lavage is to be performed.

Which of the following solutions will most likely preserve osteoblast-osteoclast function while clearing bone-adherent bacteria?

(A) 1% Bacitracin
(B) 1% Chlorhexidine
(C) 1% Ethanol
(D) 1% Povidone-iodine
(E) 1% Surgical soap

The correct response is Option E.

According to the results of an animal in vitro study, low-pressure pulse lavage with 1% surgical soap resulted in a more significant clearing of bone-adherent bacteria than other solutions. Low-pressure lavage was defined as 14 psi of pressure with 550 pulsations per minute; the solutions were evaluated in 1% and 10% concentrations. Osteoclast and osteoblast function was also shown to be preserved more significantly with use of the 1% soap or detergent solution. In contrast, the other solutions studied were shown to have a deleterious effect on osteoclast and osteoblast function. Low-pressure lavage with chlorhexidine or povidone-iodine was associated with the greatest decrease in osteoblast and osteoclast function.

The antibacterial mechanism of soap is thought to act through its micelle function. The hydrophilic ends of the soap micelle surround the bacteria, interfering with its potential for adherence to bone.

High-pressure lavage should not be used because it results in a significant depth or zone of bony injury.

References
1. Bhandari M, Adili A, Schemitsch E. The efficacy of low-pressure lavage with different irrigating solutions to remove adherent bacteria from bone. J Bone Joint Surg. 2001;83:412-419.
2. Rodeheaver GT, Pettry O, Thacker JG, et al. Wound cleansing by high pressure irrigation. Surg Gynecol Obstet. 1975;141:357-362.
3. West BR, Nichter LS, Halpern DE, et al. Ultrasound debridement of trabeculated bone: effective and atraumatic. Plast Reconstr Surg. 1994;93:561-566.

A 24-year-old woman has a 3-cm soft-tissue defect at the medial malleolus 10 months after sustaining an open fracture of the distal third of the tibia in a motorcycle accident. There were no vascular or nerve injuries at the time of the accident. Examination shows exposed bone with dense scarring of the skin and adherence to underlying tissue. Radiographs are consistent with osteomyelitis and fracture nonunion.

Which of the following is the most appropriate management?

(A) Total contact casting
(B) Split-thickness skin grafting
(C) Coverage of the wound with a soleus pedicle flap
(D) Coverage of the wound with a free latissimus dorsi flap
(E) Below-knee amputation

The correct response is Option D.

The most appropriate management of this patient with a soft-tissue defect and osteomyelitis is stabilization of the segment, debridement of the affected area, and coverage with a free latissimus dorsi pedicle flap. Application of an external fixator, radical sequestrectomy, placement of antibiotic beads, and autotransplantation of a free latissimus dorsi flap are performed initially; bone grafting of the tibial defect is performed secondarily.

There is controversy regarding the precise advantages offered by free flaps when applied to infected bone. However, the basic principles for use of these flaps include skeletal stabilization, radical debridement of infected or devitalized tissues, and coverage with vascularized tissues. The free flap provides an abundance of vascularized tissue necessary to close large wounds left by aggressive debridement, and the muscle free flap provides pliability to fill the dead spaces.

Total contact casting can be performed in patients with clean, slowly healing wounds of the distal lower extremity, but would only aggravate the fracture nonunion and osteomyelitis in this patient. Adequate debridement of only the soft-tissue scar and skin grafting over the wound will not result in a stable, healed site without infection. A soleus pedicle flap would not reliably cover this complex distal leg wound. In addition, the posterior compartment leg muscles and their vascular supply are frequently injured by high-energy injuries. Therefore, the soleus muscle is not likely to be reliable for transfer. A below-knee amputation would not be appropriate in a healthy patient with a sensate distal extremity in which the circulation is fully intact.

References
1. Anthony JP, Mathes SJ. Update on chronic osteomyelitis. Clin Plast Surg. 1991;18:515-523.
2. Gayle LB, Lineaweaver WC, Oliva A, et al. Treatment of chronic osteomyelitis of the lower extremities with debridement and microvascular muscle transfer. Clin Plast Surg. 1992;19:895-903.

A 42-year-old man sustains open fractures of the tibia and fibula (Gustilo type IIIB) when he is thrown from his motorcycle. The wounds are irrigated, debrided, and covered with a free flap. Which of the following will NOT increase this patient's risk for the development of osteomyelitis?

(A) Dead space at the surgical site
(B) Inadequate soft-tissue coverage
(C) Internal fixation
(D) Presence of nonviable muscle
(E) Retention of devitalized bone

The correct response is Option C.

Patients who sustain open fractures of the long bones are susceptible to bacterial invasion of the wound site and the subsequent development of infection, especially osteomyelitis. Factors associated with persistent infection include the presence of dead space at the surgical site, inadequate soft-tissue coverage, the presence of nonviable soft tissue, including muscle, and retention of devitalized bone. Aggressive irrigation and debridement should be performed in any patient with an open fracture. All nonviable tissue must be removed, and the fracture site should be covered with adequate soft tissue from a local site or via a free tissue transfer.

Internal fixation has not been associated with development of osteomyelitis in patients who have open fractures of the tibia and/or fibula.

Reference
1. Sherman R, Law M. Lower extremity reconstruction. In: Achauer BM, Erikson E, Guyuron B, et al, eds. Plastic Surgery: Indications, Operations, and Outcomes. Saint Louis, Mo: Mosby Ð Year Book, Inc; 2000;2:475.