Major drawbacks associated with autologous bone grafting are the risk of donor site morbidity and its limited availability. Sterilized bone allograft, however, lacking osteoinductive properties, carries the risk of graft failure resulting from insufficient osseointegration of the graft.

The aim of this study was to vitalize bone allograft with human osteoprogenitor cells under GMP-conform conditions. For this purpose we investigated proliferation, osteogenic differentiation and large-scale gene expression of human MSCs cultured three-dimensionally on peracetic acid (PAA)-treated spongious bone chips.

MSCs were isolated from healthy donors (N=5) and seeded onto PAA-treated spongious bone samples (~5×5×5 mm, DIZG, Germany) under GMP-conform conditions. Proliferation (total protein assay), osteogenic differentiation (cell-specific ALP activity assay, quantitative gene expression analysis of selected osteogenic marker genes), and morphology were assessed. RNA was isolated and microarray analysis was performed using the PIQORTM Stem Cell Microarray system (Miltenyi Biotec) including 942 target sequences.

Increasing cellularity was observed during the 42 d observation period while cell-specific ALP activity peaked at day 21. Effective proliferation and adhesion of human MSCs on PAA-treated spongious bone was confirmed by histology, scanning electron and confocal laser scanning microscopy. Gene expression of early (Runx-2), intermediate (ALP), and late (osteocalcin) osteogenic marker genes was present during 42 days of cultivation. Microarray analysis of MSCs cultivated on bone allograft versus 2-D tissue culture demonstrated temporal upregulation of genes involved in extracellular matrix synthesis (e.g., matrix metalloproteases, collagens), osteogenesis (e.g., BMPR1b, Runx-2) and angiogenesis (angiopoietin, VEGF).

PAA-treated spongious bone allograft is a biocompatible carrier matrix for long-term ex vivo cultivation of MSCs as observed by favorable proliferation, cell distribution, gene expression profile, and persisting osteogenic differentiation. GMP-grade vitalisation of bone allograft by cultivation with autologous MSCs represents a promising clinical application for the treatment of osseous defects.

For the prevention of premature osteoarthritis of the hip, the periacetabular osteotomy (PAO) of Ganz has become a common procedure. Though being a powerful method for obtaining large correction angles its drawback is the need for a broad exposure, resulting in more or less disfiguring scars. We modified the surgical approach to PAO by using two small skin incisions and reduced the extent of deep exposure by leaving the rectus femoris tendon in place and avoiding larger peri-articular deep soft tissue release.

The aim of this study is, to compare the early clinical and radiographic results of this less invasive approach with the conventional Smith-Peterson approach.

Patients and Methods: Between 01/04 and 05/05 22 consecutive PAO were performed through a conventional Smith-Peterson approach (group A). After introducing the less invasive technique 22 PAO were performed between 09/04 and 11/05 (group B). All patients were operated by the same experienced surgeon. Patients age ranged from 14 years to 46 years (mean age 26 years). Clinical (i.e. Harris-Hip-Score, Vancouver Scar Scale) and radiographic examinations (i.e. CE-angle) were performed preoperatively and postoperatively at an average follow-up of 16 months (range 6–29 months).

Results: Mean CE-angle correction in group A was 17° and in group B 23°. Functional improvement, as rated by the preoperative to postoperative Harris-Hip-Score-difference, was 15 points in group A and 22 points in group B. After the less-invasive approach, scars were considerable smaller and better-rated by the Vancouver Scar Scale (3 versus 4 after conventional surgery). The number of transient lateral cutaneous femoral nerve lesions was the same in both groups. The average time of surgery was 135 min. in group A and 153 min. in group B.

Conclusion: A smaller skin incision and limited soft tissue exposure improves cosmetic results after PAO without influencing the extent of acetabular correction negatively. The early and mid-term postoperative functional results, however, could not be significantly improved by the less invasive approach.