Successful anterior cruciate ligament (ACL) reconstructions strive a firm ligament-bone integration. Therefore, the aim of this study was to address in more detail the enthesis as the thriphasic bone attachment of the ACL using a tissue engineering approach. To establish a tissue-engineered enthesis-like construct, triphasic scaffolds embroidered from poly(L-lactide-co-caprolactone) and polylactic acid functionalized with collagen foam were colonized with osteogenically differentiated human mesenchymal stromal cells (hMSCs) and lapine (L) ACL fibroblasts.

These triphasic scaffolds with a bone-, a fibrocartilage transition- and a ligament phase were seeded directly after spheroid assembly or with 14 days precultured LACL fibroblast spheroids and 14 days osteogenically differentiated hMSCs spheroids (=longer preculture) and cultured for further 14 days. Cell survival was tested. Collagen type I and vimentin were immunolabeled and the content of DNA and sulfated glycosaminoglycan (sGAG) was quantified. The relative gene expression of tenascin C, type I and X collagens, Mohawk and Runx2 was analyzed.

Compared to the LACL spheroids the hMSC spheroids adhered better to the scaffold surface with faster cell outgrowth on the fibers. Collagen type I and vimentin were mainly detected in the hMSCs colonizing the bone zone. The DNA content was generally higher in the bone (hMSCs) than in the ligament zones and after short spheroid preculture higher than after longer preculture whereas the sGAG content was greater after longer preculture for both cell types. The longer precultivated hMSCs expressed more type I collagen in comparison to those only shortly precultured before scaffold seeding. Type I collagen and tenascin C were higher expressed in scaffolds directly colonized with LACL compared to those seeded after longer spheroid preculture. The gene expression of ECM components and transcription factors depended on cell type and preculturing condition.

Zonal colonization of triphasic scaffolds using the spheroid method is possible offering a novel approach for enthesis tissue engineering.

In search for appropriate materials of potential use to relieve injured articular cartilage, we explored copolymers from HEMA (2-hydroxy-methyl-methacrylate) and MMA (methyl-methacrylate). Such copolymers can be synthesized by thermal or photochemical induced polymerization reaction. The water uptake by swelling to homogeneous hydrogels can easily be controlled by varying the mixing ratio of the hydrophilic (HEMA) and hydrophobic (MMA) monomer, and the nature and amount of added crosslinker (typically EGDA, ethyleneglycol-dimethacrylate). Essentially the same variables strongly influence the mechanical properties, i.e. modulus (stiffness), relaxation response, as well as tribological behavior.

The polymer samples were engineered in molds from degassed formulations containing various amounts of HEMA and MMA, 10 % deionized water, and 0.01 % AIBN for thermal polymerization (12 h @ 70°C) or 0.5 % Darocur 1173 (2-hydroxy-2-methyl-1-phenyl-propane-1-one, for photopolymerization, 360 nm UV radiation, 5 to 7 min, sample thickness up to 5 mm). The samples were immersed in saline buffer after curing to allow free swelling to the equilibrium water content (EWC). Subsequently, samples were mechanically and tribologically tested. The mechanical moduli were determined at different strains and as a function of MMA content using a Zwicki Z5.0 (Zwick-Roell, Ulm, Germany). Tribological versus cartilage tissue was performed on an in-house-built pin-on-plate setup. Flat polymer samples were mounted and tested versus fresh porcine osteochondral grafts, harvested from humeral heads.

Mechanical testing revealed that the elastic modulus of pHEMA can be tuned as a function of MMA (0–50%) with 1 to 2 % bifunctional crosslinker to values ranging between 0.5 to 50 MPa, and corresponding water content of 40 to 10 % (decreasing with increasing MMA content). Friction measurements revealed a very low friction coefficient of around 0.02 for pHEMA-cartilage pairings. The values are 2–5 fold smaller than typical values of CoCrMo or UHMWPE versus cartilage.

Hydrogels from HEMA and MMA as main constituents are already rather well known for their biocompatibility. Knowledge of the dependence of e.g. the mechanical properties from chemical composition and polymer network structure makes this system ideal to design anisotropic specimen with controlled macrostructure to be used for temporal or permanent implants.

Between January 1996 and December 2006, 130 patients were operated on for acquired varus equinus foot deformity. The most frequent aetiologies were stroke or brain damage due to head trauma. The primary indications for surgery included pain, caused by pressure of the foot or toes on the floor or in shoes, ankle instability due to varus deformity, or difficulty wearing orthopaedic shoes or braces. Split anterior tibial transfer was generally done after lengthening of Achillis tendon and tenotomy of long and short toe flexors during the same session. The author did compare preoperative and postoperative autonomy, and shoe or orthosis requirements. The results of this study include significant improvement in patient autonomy demonstrated by an improved ability to ambulate independently and a decreased need to wear orthopedic shoes and orthoses, as well as an increased ability to wear normal shoes, or the ability to ambulate bare foot. Adequate knee flexion during swing phase of the stride was the best indicator for better result. This procedure is safe and yields good results with minimal complications. The indications are very common, inasmuch as the number of young hemiplegic patients surviving after a stroke or head injury is increasing. This procedure can result in definite improvement for these disabled patients and can increase their autonomy.