Simple bone cysts are relatively common in children. When they present to a musculoskeletal oncology unit, they are usually treated by a variety of methods that range from observations following fracture to surgically curettage. The outcome is usually good.

Very little is written in the literature regarding adults with a cystic bone lesion.

We present 10 consecutive skeletally mature patients who presented with a benign cystic bone lesion. The mean age at diagnosis was 38 years (20–60 years). Three patients has a cyst in the foot, three in the hip, two in the knee, one in the pelvis and the remainder in the shoulder. Full work up, including biopsy, was performed in all cases. All hip lesions required internal fixation for actual or impending fractures. The average follow up was 1.5 years. The surgical outcome was good in all cases.

The histological features are similar in all cases. Cementum, as found in Unicameral Bone Cysts, is not seen. This may present a new entity that is not described in the literature.

Introduction

Enchondromas located in the phalangeal bones may be more cellular than non-digital locations necessitating clinical and radiological correlation to determine diagnosis. Atypical enchondromas have increased cellularity and atypia relative to simple enchondromas but no evidence of permeation. Chondrosarcomas of the phalanges are thought to have a more indolent course than chondrosarcomas in other locations. The aim of the study was to determine the outcome of atypical enchondromas and grade 1 chondrosarcomas of the phalanges treated surgically.

A new surgical hybrid technique involving the combination of autologous bone plug(s) and autologous chondrocyte implantation (AOsP-ACI) was used and evaluated as a treatment option in 15 patients for repair of large osteochondral defects in knee (N=12) and hip joints (N=3). Autologous Osplugs were used to contour the articular surface and the autologous chondrocytes were injected underneath a biological membrane covering the plug. The average size of the osteochondral defects treated was 4.5cm². The average depth of the bone defect was 26mm. The patients had a significant improvement in their clinical symptoms at 12 months with significant increase in the Lysholm Score and Harris Hip Score (p = 0.031). The repaired tissue was evaluated using Magnetic Resonance Imaging, Computerised Tomography, arthroscopy, histology and immunohistochemistry (for expression of type I and II collagen). Magnetic Resonance Imaging, Computerised Tomography and histology at 12 months revealed that the bone plug became well integrated with the host bone and repair cartilage. Arthroscopic examination at 12 months revealed good lateral integration of the AOsP-ACI with the surrounding cartilage. Immunohistochemistry revealed mixed fibro-hyaline cartilage. We conclude that the hybrid AOsP-ACI technique provides a promising surgical approach for the treatment of patients with large osteochondral defects. This study highlights the use of this procedure in two different weightbearing joints and demonstrates good early results which are encouraging. The long term results need to be evaluated.