Dr. Loh Choong Sing commenced his practice in KPJ Ipoh Specialist Hospital in February 2001 as a Resident Consultant Orthopaedic Surgeon. He experienced working in Tawau Hospital as a Medical Officer in General Surgery. Meanwhile, at Queen Elizabeth Hospital, Dr Loh was once a Medical Officer (General Surgery and Orthopaedic), Clinical Specialist (Orthopaedic and Spine) and Head of Department and Consultant Orthopaedic Surgeon. He was also a Medical Officer (Hand and Microsurgery) at Hospital Kuala Lumpur. In 1999, he has served as a Fellow (Adult Reconstruction/Sport Surgery) at Singapore General Hospital. He was an Honorary Lecturer of postgraduate studies at University Kebangsaan Malaysia. On top of that, he was a Panel Member of classification and assessment of Para-Olympic athletes of Sabah.