The study
A multicentre randomised trial from a trauma research consortium took 78 adults, aged 18 to 55, with surgically fixed fractures around the knee or distal tibia. They were randomised to 10 weeks of antigravity treadmill therapy, a treadmill that offloads bodyweight so the patient can walk with less load through the healing limb, or to standard care. The primary outcome at six months was a joint-specific function score: the Knee injury and Osteoarthritis Outcome Score (KOOS) for knee fractures and the Ankle Osteoarthritis Scale (AOS) for distal tibia fractures. It was funded by the US Department of Defense.
What they found
No clear overall win. For knee fractures, six-month function was no better with the treadmill (KOOS 54 versus 61, not significant). For distal tibia fractures there was a signal favouring the treadmill that sat right on the threshold (AOS 28 versus 50, where lower is better, p = 0.05). There was no difference in general physical function, fracture healing or complications. Patients who used the treadmill were more satisfied with their therapy at six weeks and three months. This was a small trial of 78 people.
What it means for your practice
Use the antigravity treadmill as a way to load a healing limb comfortably and keep the patient engaged, not as something that reliably improves the final result. The primary outcome for knee fractures did not move. There is a hint it may help after distal tibia fractures, which is interesting but not proven on these numbers.
The satisfaction finding is worth taking seriously on its own terms. Patients liked being able to move earlier with less load through the limb, and that engagement has real value in early rehab. Just keep the promise matched to the evidence: comfortable graded loading and a better experience, not a guaranteed better six-month outcome. The authors themselves frame this as groundwork for larger trials.
Bottom line
The antigravity treadmill did not clearly improve six-month function after these fractures, with a borderline distal-tibia signal and a clear satisfaction gain. Use it for comfortable graded loading, not as a guaranteed outcome boost.