VIABILITY PROBLEMS OF LOWER LIMBS WITH COMPROMISED SENSIBILITY

William R. Osebold, M.D.; Donald M. Christenson, CPO; Shriners Hospitals for Children, Spokane, Washington


PURPOSE:

To illustrate the problems of trying to preserve limb length in patients with compromised sensibility.

Patient 1 was born with a unilateral pterygium of the right lower limb, extending from ischium to calcaneus, complicated by the presence of a duplicate six-toed foot extending from the postero-lateral aspect of the pterygium. The duplicate foot was much more robust and motile than the foot on tile end of the major tibia at the distal end of the pterygium, and had greater apparent sensibility to light touch. At age 5 months the pterygium was released, the duplicate foot and ankle excised, and closure of the posterior lower limb completed with skin grafts. The foot at the end of the pterygium was in 900 of plantar flexion, and required an extensive posterior release and TAL to dorsiflex the ankle to 300 short of plantigrade. To straighten the knee from 1000 to 300 of flexion, the hypoplastic hamstrings and gastrocnemei and posterior knee capsule had to be released. The family rejected the option of a BK or Symes amputation. At age 11 months she underwent posterior knee and ankle releases, followed by serial casting to decrease the knee flexion contracture to 13~, and to dorsiflex the ankle to 200 short of plantigrade.

At age 1 year 3 months, the right little toe was amputated, secondary to chronic trauma and failure to heal.

By age 1 year 9 months the right ankle was again at 900 plantar flexion, and required repeat posterior release with distal tibial-fibular extension osteotomies, and full thickness skin flaps to dorsiflex the ankle to so short of plantigrade.

By age 5 years 11 months, the right knee had a 25~ flexion contracture and the ankle was in 400 of rigid equinus, with extensive scarring of the posterior lower limb. At age 6 years she underwent a right triple arthrodesis and skin grafting to the heel.

By age 8 years 7 months she had recurrent hindfoot ulcers, atrophy of the right thigh and calf, 3.4 cm of limb-length discrepancy, a stiff, hypoplastic right foot with barely protective sensibility, and no function of the EHL, EDL, anterior or posterior tib, or peronei. At age 12 years 3 months, after the fourth toe was excised due to osteomyelitis, and with an ulcer over the second metatarsal head, the patient decided to have a BK amputation. She acclimatized well to a BK prosthesis, had only an 110 knee flexion contracture, and remarked that she should have had the amputation years ago.

At the time of initial evaluation in infancy, it seemed there was at least protective plantar sensibility of the right foot, and in view of the family's strong preference, extensive efforts were made to preserve the limb. The foot and limb turned out to be less robust and less sensate, and stiffer, than initially thought. It is apparent now that this hypoplastic, stiff, incompletely sensate lower limb was a chronic problem for mis child, who later decided independently that a BK amputation would be far more functional and practical.

Patient 2 at age 3 years 4 months sustained a crush injury to the pelvis and right lower limb, damaging the right pelvic plexus and external iliac artery, and rupturing me bladder and urethra. Despite extensive repairs, at age 3 years 7 months limb viability was uncertain. There were no functioning motors in the right lower limb and sensibility was meager, with incontinence of urine and stool and recurrent UTI's.

By age 4 years 8 months he had good return of hip and knee control, but still a flail ankle and foot, and no bladder or bowel sensibility. At age 6 years 5 months he had a right Symes amputation for the flail inse~isate foot and ankle with first metatarsal osteomyelitis. However, the end of the residual limb became necrotic, and at age 7 years 6 months he was converted to a BK amputation. One month later the surgical wound had dehisced and necrotic drainage grew 1+ Staph, aureus, as he was finishing a course of amoxicillin for a UTI. The wound was debrided, but the next day he developed high, spiking fevers and an erythematous rash. The limb was re-explored and much necrotic muscle was debrided. The limb was packed open and the patient received multiple antibiotics for toxic shock syndrome. Cultures grew 1 ± Staph, aureus with rare alphastrep and rare Klebsiella oxytoca. He required two more debridements with packing open, followed by formal wound closure, whose culture grew Enterobacter cloacae, requiring a change in antibiotics.

By age 7 years 9 months his wound had healed, ESR and CRP were normal, and he was fitted with a new PTB prosthesis.

He did well until age 8, when he had intermittent episodes of skin breakdown, eschar formation, and serous drainage. At age 8 years 6 months he required excision of two centimeters of protruding distal fibula. Deep wound cultures showed no growth. Despite persistent residual limb hypesthesia and eschar formation, he is finally stable, and fully active with his prosthesis.

In this case, despite early Symes amputation for flail ankle and foot, the markedly compromised sensibility of the residual limb predisposed to multiple severe problems in trying to preserve some tibial length. With persistent sensory deficit of the residual limb and pelvis, he may still require a future AK revision.

COMMENT:

Understandably, patients, families, and clinicians strive to maintain as much residual limb length as possible. However, in limbs with compromised sensibility a series of higher amputations may become necessary, even if the vascular supply is adequate. Early counseling of families may facilitate acceptance of a functional amputation in favor of extensive failed attempts at salvage in such cases.