Biodegradable porous scaffolds play an important role in tissue engineering as the temporary templates for transplanted cells to guide the formation of the new organs. The most commonly used porous scaffolds are constructed from two classes of biomaterials. One class consists of synthetic biodegradable polymers such as poly (α-hydroxy acids), poly(glycolic acid), poly(lactic acid), and their copolymer of poly(DL-lactic-co-glycolic acid) (PLGA). The other class consists of naturally derived polymers such as collagen. These biomaterials have their respective advantages and drawbacks. Therefore, hybridization of these biomaterials has been expected to combine their advantages to provide excellent three-dimensional porous biomaterials for tissue engineering. Our group developed one such kind of hybrid biodegradable porous scaffolds by hybridizing synthetic poly (α-hydroxy acids) with collagen. Collagen microsponges were nested in the pores of poly (α-hydroxy acids) sponge to construct the poly (α-hydroxy acids)-collagen hybrid sponge.

Observation by scanning electron microscopy (SEM) showed that microsponges of collagen with interconnected pore structures were formed in the pores of poly (α-hydroxy acids) sponge. The mechanical strength of the hybrid sponge was higher than those of either poly (α-hydroxy acids) or collagen sponges both in dry and wet states. The wettability with water was improved by hybridization with collagen, which facilitated cell seeding in the hybrid sponge. Use of the poly (α-hydroxy acids) sponge as a skeleton facilitated formation of the hybrid sponge into the desired shapes with high mechanical strength, while collagen microsponges contributed good cell interaction and hydrophilicity. One of such kind of hybrids. Additionally, our group developed a hydrostatic pressure bioreactor for chondrocyte culture. And our study showed that hydrostatic pressure (0–3 MPa) had promotional effects on the production of proteoglycan and type II collagen by cultured chondrocytes. Therefore, it would be a promising pathway for reconstructing cartilage-like tissue to culture chondrocytes in this three-dimensional hybrid sponge under physiological hydrostatic pressure.

We treated 31 patients aged 65 years or more with cervical spondylotic myelopathy by microsurgical decompression and fusion at a single most appropriate level, in spite of MRI evidence of compression at several levels. Spinal cord potentials evoked at operation localised the level responsible for the principal lesion at C3-4 in 18 patients, C4-5 in 11 and at C5-6 in two. Despite the frequent coexistence of other age-related conditions, impairing ability to walk, the average Nurick grade improved from 3.5 before operation to 2.2 at a mean follow-up of 48 months. There was also good recovery of finger dexterity and sensitivity.

Operation at a single optimal level, as opposed to several, has the advantage of minimising complications, of particular importance in this age group.