Research and publications

Dr Limbers was a site investigator for the RASKAL Study Group, which evaluated robotic-assisted surgery and functional alignment in total knee replacement in an Australian registry-nested randomised controlled trial. He recruited the second-highest number of patients in the study.

Robotic assistance is now widely used in knee replacement, and it is well established that it improves the accuracy and consistency of implant positioning. The open question has always been the one that matters most to patients: does that greater accuracy actually produce a better knee?

RASKAL was built to answer it. It is an Australian registry-nested randomised controlled trial with a 2×2 factorial design, meaning it tested two variables at once and in combination — robotic-assisted surgery against computer navigation, and functional alignment against mechanical alignment. Nesting the trial inside the Australian Orthopaedic Association National Joint Replacement Registry allows participants to be followed through the registry for long-term revision data, well beyond the life of the study itself.

The trial has now reported, and the result is worth stating plainly.

Findings: the RASKAL trial found no significant difference in patient-reported or functional outcomes at two years between robotic-assisted and computer-navigated total knee replacement. Within the operation, robotic assistance was associated with shorter operating time and better preservation of the posterior cruciate ligament, while functional alignment reduced the need for soft-tissue releases.

Those intraoperative advantages did not, however, translate into superior clinical or functional scores for patients over a two-year window, when compared against standard computer navigation with mechanical alignment.

Two points of context matter when reading that.

The comparison was against computer navigation — itself a technology-assisted technique — rather than traditional manual instrumentation. Two years is also relatively early in the life of a knee replacement. Longer-term follow-up is therefore important to determine whether differences in surgical accuracy or soft-tissue handling translate into differences in implant survival, function or revision rates.

Dr Limbers was a site investigator for the RASKAL trial and recruited the second-highest number of patients in the study. The trial was published in the Bone & Joint Journal in 2026.

• Limbers J, Edmunds I, Ruff S. Huckstep Intramedullary Nailing for Non-union of Humeral Shaft Fractures. Australian and New Zealand Journal of Surgery. 1998;68(3):194–198.
• Robinson AHN, Limbers JP. Modern Concepts in the Treatment of Hallux Valgus. Journal of Bone and Joint Surgery - British Volume. 2005;87(8):1038-1045.
• Cronin J, Limbers JP, Kutty S, Stephens MM. Intermetatarsal Angle After First Metatarsophalangeal Joint Arthrodesis for Hallux Valgus. Foot & Ankle International. 2006;27(2):104-109.
• Joshi MA, Le M, Campbell R, Sivakumar B, Limbers J, Harris IA, Symes M. Surgery for Olecranon Fractures in the Elderly (SOFIE): Results of the SOFIE Randomized Controlled Trial. Journal of Bone and Joint Surgery — American Volume. 2025;107:452–458.
• MacDessi SJ, Wernecke GC, Ghadirinejad K, Wood JA, Holder C, Lorimer M, Harris IA and the RASKAL Study Group. Robotic-assisted Surgery and Functional Alignment in Total Knee Arthroplasty: The RASKAL Registry Nested 2×2 Factorial Randomized Trial. Bone & Joint Journal. 2026;108-B(5):622–633.

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