Using histology, we studied the innervation of nociceptors in the medial and lateral menisci of the knee joint. Specimens examined were taken from 16 patients during arthroplasty. The patients were 6 men and 10 women, with ages ranging from 14 to 76 years (mean 56 years). Immunohistochemistry with the unlabeled antibody biotin-streptavidin method was employed to detect protein gene product 9.5 (PGP 9.5) or substance P (SP) in the specimen. The antibody for PGP 9.5 detected nerve tissues in the menisci. Most but not all of the nerve fibers were associated with blood vessels. Nerve fibers and sensory receptors were found mainly in the peripheral, vascular zone, representing the outer one-third of the meniscus, and the innervated area was wider in the anterior and posterior horns. Pacinian and Ruffini corpuscles as well as free nerve endings were identified in these areas. Larger fibers coursed circumferentially in the peripheral zone, with smaller branches of nerve fibers running radially into the meniscus. Nerve fibers positive for SP were also detected in the menisci, but were fewer in number. Their branches also were fewer, oriented radially and paralleling blood vessels. This study showed that some of the pain in cases of meniscal tear could originate in the meniscus itself, especially with peripheral tears that may be accompanied by bleeding.

This report describes the first case of postpartum pyogenic sacroiliitis caused by MRSA. The frequency of infection with MRSA has recently increased, and community-acquired MRSA, which affects even healthy young people, has also become a problem. Antibiotics for empirical therapy after a diagnosis of pyogenic sacroiliitis, including anti-MRSA antibiotics, should be carefully selected.

V.

Hip dislocation associated with Down syndrome is relatively rare. Hip dislocation can progress to severe subluxation or habitual dislocation if the initial therapy is improperly performed. However, definitive treatment guidelines for conservative and surgical therapy for hip dislocation in patients with Down syndrome have not been established. This article describes a case of a 12-year-old girl with Down syndrome with nontraumatic habitual hip dislocation. Her hip joint was associated with acetabular dysplasia and hypoplasia of the posterior acetabular wall. Although conservative therapy was initially performed, no effects were observed. Rotational acetabular osteotomy and capsular plication were performed to reconstruct the posterior acetabular wall. No postoperative redislocation occurred, and the treatment effects were favorably sustained for 2 years. In Down syndrome, few cases of developmental dysplasia and hypoplasia of the posterior acetabular wall have been reported. In previous reports, these morphological abnormalities were rarely taken into consideration when determining the treatment strategy, and to our knowledge, no other reports demonstrate therapy involving rotational acetabular osteotomy for hip dislocation complicated with Down syndrome. Whether the acetabulum had posterior wall deficiency was thought to be important for conservative and surgical therapies in hip dislocation in patients with Down syndrome. Rotational acetabular osteotomy could be an effective surgical procedure for reconstruction of the acetabulum by posterolateral rotation of the osteotomized acetabulum.

No abstract