Lower Body Positive Pressure Treadmill for Functional Improvement in Knee Conditions
Lower body positive pressure (LBPP) treadmill training can significantly improve functional outcomes in the knee, particularly for patients with knee osteoarthritis by reducing knee forces while allowing therapeutic exercise. 1
Mechanism and Benefits
- LBPP treadmills use a pressurized chamber to unweight patients, reducing forces through the knee joint while maintaining normal gait patterns 2
- In vivo measurements have shown that LBPP can reduce peak axial tibiofemoral forces from 5.1 times body weight to as low as 0.8 times body weight, depending on settings 2
- The technology effectively simulates weight loss during exercise, which is particularly beneficial for overweight individuals with knee osteoarthritis 3
Clinical Evidence for Knee Osteoarthritis
- Randomized controlled trial evidence shows that LBPP treadmill training produces greater improvements in walking speed, stride length, and knee range of motion compared to conventional ground walking in patients with mild to moderate knee osteoarthritis 1
- A mean LBPP support of 12.4% of body weight has been shown to provide significant pain relief during walking and prevent exacerbation of acute knee pain during 20-minute exercise sessions 3
- LBPP treadmill training has demonstrated improvements in Western Ontario and McMaster Universities Arthritis Index (WOMAC) and visual analog scale (VAS) pain scores after a 2-week intervention program 1
Application in ACL Rehabilitation
- While specific LBPP treadmill studies for ACL rehabilitation are limited, clinical guidelines for ACL rehabilitation note that backward walking on an inclined treadmill (as part of motor control training) can significantly improve knee joint proprioception in early and intermediate phases after ACL reconstruction 4
- The addition of motor control training that includes treadmill exercises has shown moderate effects on knee joint proprioception even at 2 years after ACL reconstruction 4
Comparison to Other Rehabilitation Approaches
- For stroke rehabilitation, evidence regarding body-weight support treadmill training is equivocal, with one systematic review of 23 RCTs finding no significant difference between body-weight support treadmill training and conventional overground training 4
- For knee osteoarthritis, guidelines recommend low-impact aerobic fitness exercises, which LBPP treadmill walking would qualify as 4
- Strength training for lower limbs has been shown to reduce pain effectively (ES 0.53,95% CI 0.27 to 0.79) and improve physical function (ES 0.58,95% CI 0.27 to 0.88) in knee OA patients 4
Practical Implementation
- LBPP protocols can include both walking and squatting models to address different functional aspects of knee rehabilitation 5
- Walking sessions typically last 20-30 minutes at moderate speeds (e.g., 3.1 mph), with LBPP adjusted to minimize knee pain 3, 1
- For knee osteoarthritis patients, a 6-week program with three 30-minute sessions per week has shown promising results 6
- The strong correlation between tibiofemoral force and walking speed/treadmill reaction forces allows for precise targeting of desired knee forces during rehabilitation 2
Limitations and Considerations
- Most research has focused on knee osteoarthritis; evidence for other knee conditions is more limited 3, 1
- Long-term effects of LBPP treadmill training need further exploration in larger clinical trials 5
- LBPP technology may not be widely available in all rehabilitation settings due to equipment costs and space requirements 3
Emerging Applications
- Backward walking exercise using LBPP treadmills is being investigated as a potentially superior intervention compared to forward walking for knee osteoarthritis 6
- LBPP treadmill training may be particularly valuable during early rehabilitation phases when weight-bearing activities would otherwise be limited or painful 2, 3