D Taggart: Performed previous work that was the foundation of current study (thought of the idea for the review, helped to design the study, extracted and compiled data and wrote the initial draft of the systematic review). Edited text of protocol for current review, provided a clinical perspective, assisted with design of inclusion and exclusion criteria and data extraction form.

D Altman: Performed previous work that was the foundation of current study (helped design the study, collaborated on final draft of published review). Edited text of protocol for current review. Advised on design of inclusion and exclusion form, and data extraction form.

S Mussa: Provided expert guidance on surgical techniques, provided a clinical perspective, screened search results. screened retrieved papers against inclusion criteria, extracted data from papers.

R D'Amico: Performed previous work that was the foundation of current study (helped design study, analysed and compiled data). Edited text of protocol for current review, screened search results, screened retrieved papers against inclusion criteria, extracted data from papers, assisted in design of data extraction from.

THM Moore: Coordinated the review, provided general advice on the review, entered the review into RevMan, screened search results, organised retrieval of papers.

M Burke: Designed the search strategy and ran the searches on all of the bibliographic databases.