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This study measured the bonding strength between alkyl-2-cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6-11.2 N/mm2). In long-term experiments under water, n- and i-butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long-term strength.

Osteotomies of the distal femur in 19 rabbits were operatively fixed with totally biodegradable implants. Radiographic, histological, microradiographic, and oxytetracycline-labeling studies showing healing of the osteotomy within 6 weeks. The fixation proved stable sufficiently during healing of the osteotomized bone. The osteotomies united without delay and malalignment did not occur, although no external support was used and the rabbits were allowed to walk freely after the operation. Successful use of the biodegradable fixation developed in the present study was reported recently for the treatment of fractures of the ankle.

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The aim of this study was to ascertain whether the use of liquid acrylic resin or NeoCryl XK-53 acrylic emulsion or etching of the bone surface with phosphoric acid or the application of both these methods would improve the bonding of CMW bone cement or Concise and Silar composite resin to bone. The test materials were applied to fresh cortical bovine bone. Their bonding capacity was measured by the Instron Universal Testing Machine. The surfaces of the test materials and the bone surfaces were examined by means of optic microscope or scanning electron microscope. The bonding strength of the bone cement and composite resins as such were found to be of the same magnitude. A three- to five-fold improvement was obtained with liquid acrylic intermediary material. Acid etching impaired the bonding.

A distal femoral osteotomy was fixed with liquid cyanoacrylate and bone cement in 25 rabbits. Follow-up was done at 1, 3, 6, 12, and 24 weeks. The distal portion of each femur was removed, fixed in alcohol, embedded in methylmethacrylate, sawed to 80 micron thickness for OTC-fluorescence study and microradiography, and cut to 5-micron sections for histological analysis. Radiological and careful microscopic (OTC labeling, microradiographic, and histological) studies showed healing of the osteotomies during the first 6 weeks after operation. However, at 12 and 24 weeks' follow-up only four of ten osteotomies had healed. According to these observations it is obvious that fixation of an osteotomy of the cancellous bone with bone cement and cyanoacrylate does not provide sufficient stability for successful healing.

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