This is the second of a series of reviews of registries. This review looks specifically at worldwide registry data that have been collected on knee arthroplasty, what we have learned from their reports, and what the limitations are as to what we currently know.

The August 2015 Trauma Roundup³⁶⁰ looks at: Thromboprophylaxis not required in lower limb fractures; Subclinical thyroid dysfunction and fracture risk: moving the boundaries in fracture; Posterior wall fractures refined; Neurological injury and acetabular fracture surgery; Posterior tibial plateau fixation; Tibial plateau fractures in the longer term; Comprehensive orthogeriatric care and hip fracture; Compartment syndrome: in the eye of the beholder?

While the demand for orthopaedic surgical expertise in the developing world is in critically short supply, short-term remedy from visiting doctors cannot solve this long-term healthcare problem. Capacity building by senior and training orthopaedic surgeons from established Western training programmes can offer a significant contribution to the orthopaedic patient in the developing world and the gains for those visiting are extremely valuable. We report on several visits by a UK orthopaedic team to a hospital in Kabul, Afghanistan and discuss the operative and non-operative case mix and the benefits in terms of local capacity building and the unique experience of those visiting.