The articular joint and its intriguing gliding surfaces

In 1969, the first man made his first steps on the moon. It was a fantastic research work behind that enormous achievement. Ten years earlier, in 1959, Pridie described how to treat cartilage lesions with bare bone with multiple drilling. Eighteen years after the first moon walk, chondrocytes were used to treat cartilage lesions for the first time. Many of us looking at the moon walks expected a large future of space invasions with a living on the moon but it has not yet happened. Similarly, many believed that cell implantations quite fast would heal OA joints, but that has also not happened. However, looking at details, space research has led to an enormous amount of innovations that facilitates daily life. Also, in cartilage research, we have many small research pieces that all together start to make the cartilage puzzle’s image slightly visible even if it is still partly blurred. In this volume, we have the pleasure to present a large number of cartilage-related papers. Most of them are clinically related but some are purely basic in science. The different papers have been put into subcategories. There is one RCT paper to pay some attention to. Still in orthopaedics, there are too few numbers of RCT: s means that every new one published could give us valuable knowledge. The number of patients in the study was unfortunately low, only 25 patients with 11 treated by microfracture and 14 with mosaicplasty plugs and followed for 9.8 years and with equal clinical results. As with a low number of patients, one always has to discuss about the statistical power. The disease osteochondritis dissecans has intrigued many doctors, and there are many theories of the aetiology. The possibility to treat our young patients with this condition is important, and updates are needed at least every fifth year related to the development in the research field of tissue engineering and imaging. A review paper on OCD included in this cartilage issue will give us the latest updates to tell us how we in the second decade of the new century could treat our OCD patients. One paper is also included in the treatment of osteochondral injuries of the elbow. With a lot of more violent sports appearing, also the smaller joints will be more present in the trauma spheres and the elbow is increasing in the reports of frequencies related to osteochondral injuries. Two large sections are for clinical repairs in the knee and in the ankle. We could learn from those papers that there are a large variety of new materials used to augment the repair using primarily one stage bone marrow derived techniques with osteochondral plugs some of them as biomimetic scaffolds with multilayered constructs. However, also the cell-based tissue-engineered implants are presented from first generation of ACI to osteochondral implants. M. Brittberg (&) Consultant Orthopaedic Surgeon, Region Halland Orthopaedics, Kungsbacka Hospital, University of Gothenburg, 434 80 Kungsbacka, Sweden e-mail: Mats.Brittberg@regionhalland.se