Dr. McNicholl is a Brisbane based orthopaedic surgeon and sees private outpatients in rooms located within the Brisbane Hip Clinic Fortitude Valley, and operates privately on Wickham Terrace at both the Brisbane Private Hospital, and St. Andrews War Memorial Hospital.​ In addition to his private work he holds an appointment as a Senior Medical Officer (SMO) at the Mater Hospital Brisbane where he sees public patients. In association with this he also holds an academic appointment as a Senior Lecturer at the University of Queensland and regularly teaches medical students at the Mater Public Hospital.​​​​​​

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Prior to his return to Brisbane he worked as a Staff Specialist and as the Acting Clinical Director of Orthopaedic Surgery at the Cairns Hospital. Here he also held an academic appointment as a Senior Lecturer at James Cook University.

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Dr McNicholl has undertaken advanced subspecialty training in the United Kingdom. He worked as the Clinical Fellow in Arthroplasty at St Georges Hospital, one of London's oldest hospitals. Established in 1733 St George's is famous for its contribution to modern surgery, in particular for the work of Sir John Hunter, widely acknowledged as the founder of modern surgery, and Henry Gray, author of arguably the most famous anatomical textbook. While in London he also worked at the South West London Elective Orthopaedic Centre, the United Kingdom's highest volume centre for joint replacement where more than 5000 joint replacements are performed annually. His fellowship focused on complex and revision joint replacement of the hip and knee.

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Dr. McNicholl was selected for specialty training by The Royal Australasian College of Surgeons and the Australian Orthopaedic Association while working in Queensland as an Orthopaedic Principal House Officer. He completed his specialist surgical training at a number of hospitals across Australia including St. Vincent's Hospital Melbourne, The Royal Brisbane and Women's Hospital, The Prince Charles Hospital, The Royal Children's Hospital Queensland and and Mater Hospital. During this time he served as the Queensland representative for the Royal Australasian College of Surgeons Trainee Association (RACSTA).​​

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Dr. McNicholl obtained his Bachelor of Medicine, Bachelor of Surgery (MBBS) from James Cook University. Here he developed his foundational knowledge and interest in orthopaedic surgery and was ultimately awarded the university's nomination to the  Australian Orthopaedic Association's annual undergraduate workshop.

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Dr McNicholl's medical career is underpinned by a strong desire to be a 'man for others' which was the key ethos of his Jesuit education at St. Ignatius College Riverview, Sydney.