Table 1.

Study inclusion and exclusion criteria.

Inclusion criteria

  1. Adults who underwent TKA > 6 months before study entry

  2. Chronic painful TKA for > 3 months with pain ≥ 6 on a 10-point numerical pain rating scale

  3. Failed treatments including oral pain medications and were not surgical candidates

  4. Negative investigation for an infectious etiology by the referring orthopedic surgeon with one or more of the following — normal inflammatory markers, including normal erythrocyte sedimentation rate, or C-reactive protein; normal clinical examination; and/or culture-negative joint fluid aspirate

Exclusion criteria

  1. History of myasthenia gravis, Eaton-Lambert syndrome, amyotrophic lateral sclerosis, or other known diseases of the neuromuscular junction or motor neuron disease

  2. Concomitant use of aminoglycoside or agents that interfere with neuromuscular junction transmission

  3. Women who were pregnant or breast-feeding

  4. Known allergy or sensitivity to the study medication

  5. Recent or ongoing alcohol or drug abuse

  6. Known, uncontrolled systemic disease

  7. Concurrent participation in other drug study