This study examined the effect of 2 yr of treatment with the aminobisphosphonate alendronate (ALN) (0.05 or 0.25 mg/ kg i.v. ALN every 2 wk) on estrogen deficiency bone loss and bone strength changes in ovariectomized (OVX) baboons (n = 7 per group) and the ALN mode of action at the tissue level. Biochemical markers of bone turnover increased in OVX animals and were maintained by ALN treatment at non-OVX levels (low dose) or below (high dose). 2 yr of treatment produced no cumulative effects on bone turnover markers. Histomorphometry showed a marked increase in cancellous bone remodeling in OVX animals. Activation frequency increased from 0.48 to 0.86 per yr (L5 vertebra), and the osteoid surfaces from 9 to 13.5% (P < 0.05). No changes were observed in eroded and osteoclast surfaces. ALN treatment decreased activation frequency and indices of bone formation to control levels (low dose) or below (high dose), did not change indices of mineralization, and increased bone mineral density (BMD) in the lumbar vertebrae (L2-L4) by 15% at 0.25 mg/kg (P < 0.05), relative to vehicle-treated animals. The mean strength of cancellous bone (LA) increased by 44% (low ALN dose) and 100% (high dose), compared with vehicle. The strength of individual bones correlated with the square of the L2-L4 BMD (r = 0.91, P < 0.0034). In conclusion, ALN treatment reversed the effects of ovariectomy on cancellous bone turnover and increased bone mass and bone strength in baboons. (J. Clin. Invest. 1993. 92:2577-2586 Key words: osteoporosis * alendronate * histomorphometry-bone strength * bone mineral density

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We have developed a novel, two-layered, collagen matrix seeded with chondrocytes for repair of articular cartilage. It consists of a dense collagen layer which is in contact with bone and a porous matrix to support the seeded chondrocytes. The matrices were implanted in rabbit femoral trochleas for up to 24 weeks. The control groups received either a matrix without cells or no implant.The best histological repair was seen with cell-seeded implants. The permeability and glycosaminoglycan content of both implant groups were nearly normal, but were significantly less in tissue from empty defects. The type-II collagen content of the seeded implants was normal. For unseeded implants it was 74.3% of the normal and for empty defects only 20%. The current treatments for articular injury often result in a fibrous repair which deteriorates with time. This bilayer implant allowed sustained hyaline-like repair of articular defects during the entire six-month period of observation. [Br] 1997;79-B:831-6. Received 23 September 1996; Accepted after revision 18 April 1997 The clinical need for repair of lesions of the articular cartilage is increasing, but there is no satisfactory method of surgical repair. Abrasion arthroplasty, excision and drilling, cartilage debridement, and arthroscopic shaving have all been used. J Bone Joint Surg

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The lateral column lengthening group achieved greater realignment initially and maintained correction better over time than the calcaneal osteotomy group while having a lower reoperation rate despite a higher incidence of nonunion and radiographic progression of adjacent joint arthritis.

Weightbearing radiographs permit the recognition of associated malalignments of the foot in patients with hallux valgus. The comparisons performed in this study identified deformities consistent with pes planovalgus and hypermobility of the first ray in patients with moderate to severe hallux valgus. The results of our study support a recommendation for a thorough evaluation of full-length, biplanar weightbearing radiographs via the measurement of midfoot and first ray alignment for concomitant deformities of the foot in patients with hallux valgus.

The significant improvements in the radiographic and functional measures of outcome that were observed in this small cohort suggest that chronic syndesmotic instability after ankle fracture can be salvaged with reduction and arthrodesis of the distal tibiofibular articulation. Furthermore, the reconstruction of an incongruous and arthritic ankle is an alternative to and may postpone the subsequent need for ankle arthrodesis or arthroplasty.

Level III, comparative series.