Abstract

A non-controlled prospective trial was carried out to investigate ultrastructure of acetabular roof and joint capsule by electron microscopy in dislocated developmental dysplasia of the hip (DDC). Nineteen randomly selected babies aged 18 months to 8 years and ten months, were operated on by a medial approach for open hip reduction between January and July 2006, obtaining biopsies at surgery. No healthy hips were opened just for harvesting biopsies. Surprisingly Mycoplasma corpuscles were found in 15 out of the 19 patients (78%, p = 0.019 binominal distribution test). Corpuscles appeared in 3 cases in roof and capsule, in 5 only in cartilage and in 7 only in capsule. Four out of 5 children aged 18 - 22 months (80%) had Mycoplasma in cartilage, as well as in 4 out of those 14 (28.6%) older than 22 months. Three out of 5 under 22 months (60%) had Mycoplasma in joint capsule: 40% in cartilage and capsule and 20% only in capsule. In those greater than 22 months only 7.2% had Mycoplasma at both levels and 42.8% only in the joint capsule. Mycoplasma had a tendency to decrease as patients grew-up in age. It is proposed that Mycoplasma in acetabulum could contribute to impair its full ossification in DDC since it would compete for cartilage nutrients, thus producing deterioration of chondral cells and matrix, and a difficult acetabular physis advancement inside the chondral acetabulum. Also a decreased capsule tensile strength could result in slacking capsule and joint dislocation.

Keys words: Congenital, developmental, hip dysplasia, Mycoplasma