The concept of a learning curve was first introduced to predict aircraft manufacturing costs in 1936, but in the past 2 decades, it has been increasingly adopted in surgical practice. It was recognized that surgeons operating at the early stages of their learning curve pose a potential hazard, and modeling learning has since received considerable attention. Any new procedure will require a period of learning, and training schemes seek to ensure that trainees achieve a satisfactory standard of performance.
A fundamental difference between drug trials and surgical trials is that the latter involve a procedure and therefore the patient outcome will depend on a complex interaction between surgeon, patient and the operating environment. With regards to the surgeon’s impact; the outcome will be influenced by their proficiency in the delivery of the procedure. Surgical proficiency is known to depend on both the learning curve for a procedure and the case volume of the surgeon, i.e., it is necessary to both ascend the learning curve and to practice the procedure regularly.
The learning curve varies for different procedures. For instance for hip fracture fixation the operating time does not level off until the surgeon has done 20 to 30 of these operations.1 For reduction of uncomplicated congenitally dislocated hips it may be slightly fewer as the performance seems to level after 10 to 20 procedures and can be accelerated with appropriate simulation training.2 For arthroscopy of the knee, a simulation study suggests that consultant level skills are not reached until 170 procedures have been carried out.3 Thus although the actual number might vary, there will always be a certain number of cases a surgeon needs to have performed before his/her proficiency has plateaued. From the ethical point of view, before offering a new procedure a surgeon should be confident that he/she will do sufficient cases to complete the learning curve.
Ongoing research on surgical learning curves adds further information on a weekly basis, and changes to current practice seems to be around the corner; impact will likely be on new medical device introduction as well as patient consenting practices where surgeons learning curve presents potential risk to the patient. Ongoing discussions with insurance companies shows it is also likely to change how premiums are being calculated for regularly vs non regularly trained surgeons.