Objective:To evaluate the distribution of SP (substance P) and S-100 peptide immunoreactivity, as well as the vascular supply of tissues commonly used as grafts for anterior cruciate ligament (ACL) reconstruction. A second aim was to compare the above mentioned distribution in the semitendinosus muscle tendons of cerebral palsy (CP) patients with the semitendinosus muscle tendons and patellar tendons of patients without CP.Methods:The first group consisted of 14 children with cerebral palsy with a mean age of 11.7 years old. At the time of hamstring lengthening operation, a sample of semitendinosus muscle was taken for analysis. The second group comprised 20 patients treated for isolated ACL rupture of the knee (mean age 32 years old). Group three comprised ten patients in the mean age of 14.3 years old treated for recurrent lateral patellar dislocation, and from whom a sample of patellar tendon was obtained.Results:No statistically significant differences were demonstrated with regard to the amount of immunopositive nerve fibers expressing SP or S-100 in all 3 groups of patients. A significant difference was noted in the number of blood vessels between the adult and child semitendinosus muscles, but not between the semitendinosus muscles and patellar tendon of children.Conclusion:The number of nociceptors as well as proprioceptive fibers is similar in patients with CP and patients from a neurologically healthy population.Level of Evidence IV, Cases Series.