Minimum 10-year follow-up results of ALPINA cementless hydroxyapatite-coated anatomic unicompartmental knee arthroplasty.

One hundred and one unicompartmental knee arthroplasties (UKA) were done between 1996 and 2000 with ALPINA(®) UNI, a cementless hydroxyapatite-coated anatomic prosthesis. Sixty-five knees were available for the long-term follow-up at a mean of 11 years. The mean IKS improved from 119.3 ± 16.8 points preoperatively to 171.4 ± 25.3 at the latest follow-up (p < 0.0001). Eighty-nine percentage of the knees were rated good and excellent. The mean knee flexion has significantly improved from 120°5 preoperatively to 127°3 at the latest follow-up (p < 0.01). Eleven revision procedures were done: 1 for early knee degeneration on rheumatoid arthritis, 1 for degeneration of osteoarthritis in the opposite compartment of the knee, 1 for unexplained pain and 1 for late ACL rupture, all these 4 cases were replaced by total knee arthroplasties; 3 revisions by another UKA were done due to polyethylene insert fracture; and 4 partial revision were done for bearing exchange due to severe polyethylene wear. When revision for any reason was defined as the end point, the 13-year Kaplan-Meier survival rate was 88 % (95 % CI 81-95 %) and when revision due to implant mechanical failure (excluding degeneration of osteoarthritis in the opposite compartment of the knee and bearing exchange only) was defined as the end point, the 13-year survival rate was 94 % (95 % CI 89.1-99.1 %).

Consequences of group fission for the patterns of relatedness among rhesus macaques.

When mammalian social groups exceed their optimal size, they often tend to split. In view of the potential evolutionary benefits, it should be more advantageous for animals to stay with kin, rather than nonkin, during such fission events. In the present study, the spontaneous fission of two social groups, R and S, of rhesus macaques living on Cayo Santiago, Puerto Rico, provided the opportunity to compare the kinship structure of the corresponding parent and daughter groups, using information on both maternal and paternal relatedness. In both instances, maternal half-siblings and pairs of animals from the same family were significantly more prevalent in the fission products than in the parent group. During the split of group R, significantly more paternal half-siblings stayed in the remnants of the parent group than joined the seceding group. Our findings are compatible with previous behavioural studies demonstrating that female primates bias their social behaviour more to maternal than to paternal kin, but that both types of half-siblings prefer each other more than unrelated animals. It remains to be clarified by future research, however, whether the observed co-segregation of paternal half-sibs in our study reflects active choice or is a by-product of the group-specific kin structures, prior to fission.