Jumping Mechanography is a Suitable Complementary Method to Assess Motor Function in Ambulatory Boys with Duchenne Muscular Dystrophy

Objective The number of clinical trials for Duchenne muscular dystrophy (DMD) has increased substantially lately, therefore appropriate clinical instruments are needed to measure disease progression and drug efficacy. Jumping mechanography is a medical diagnostic method for motion analysis, which allows to quantify physical parameters. In this study, we compared mechanography with timed function tests (TFTs). Methods 41 ambulatory DMD patients performed a total of 95 chair rising tests (CRT) and a total of 76 single two-legged jumps (S2LJ) on a mechanography ground reaction force platform. The results were correlated with a 6-minute walk test (6MWT) and the time required to run 10 meters, stand up from a supine position, and climb four stairs, all performed in the same setting. Results Our measurements show a high correlation between mechanography and the TFTs: S2LJ/10-m run, r = 0.62; CRT/10-m run, r = 0.61; S2LJ/standing up from supine, r = 0.48; CRT/standing up from supine, r = 0.58; S2LJ/climb four stairs, r = 0.55; CRT/climb four stairs, r = 0.51. The correlation between mechanography and the 6MWT was only moderate with r = 0.38 for S2LJ/6MWT and r = 0.39 for CRT/6MWT. Interpretation Jumping mechanography is a reliable additional method, which can be used for physical endpoint measurements in clinical trials. We confirmed our assumption, that the method provides additional information concerning performance at movement with higher power output. We suggest using the S2LJ as a first-choice tandem tool combined with the 6MWT. In patients with higher disability, the CRT is an alternative measuring method, because with the progression of the disease this is longer feasible.

Jumping Joints: The Complex Relationship Between Osteoarthritis and Jumping Mechanography

We investigated the relationship between lower limb osteoarthritis (OA) and muscle strength and power (assessed by jumping mechanography) in UK community-dwelling older adults. We recruited 249 older adults (144 males, 105 females). OA was assessed clinically at the knee according to ACR criteria and radiographically, at the knee and hip, using Kellgren and Lawrence grading. Two-footed jumping tests were performed using a Leonardo Mechanography Ground Reaction Force Platform to assess maximum muscle force, power and Esslinger Fitness Index. Linear regression was used to assess the relationship between OA and jumping outcomes. Results are presented as β (95% confidence interval). The mean age of participants was 75.2 years (SD 2.6). Males had a significantly higher maximum relative power during lift off (mean 25.7 W/kg vs. 19.9 W/kg) and maximum total force during lift off (mean 21.0 N/kg vs. 19.1 N/kg) than females. In adjusted models, we found significant associations in males between clinical knee OA and maximum relative power [− 6.00 (CI − 9.10, − 2.94)] and Esslinger Fitness Index [− 19.3 (− 29.0, − 9.7)]. In females, radiographic knee OA was associated with total maximum power [− 2.0 (− 3.9, − 0.1)] and Esslinger Fitness Index [− 8.2 (− 15.9, − 0.4)]. No significant associations were observed for maximum total force. We observed significant negative associations between maximum relative power and Esslinger Fitness Index and clinical knee OA in males and radiographic knee OA in females. We have used novel methodology to demonstrate relationships between muscle function and OA in older adults.

Jumping Mechanography as a Complementary Testing Tool for Motor Function in Children with Hereditary Motor and Sensory Neuropathy

Objective This study aims to compare mechanography, measuring force in jumping, and rising, with the 6-minute walk test (6MWT) and time function tests in pediatric patients with hereditary motor and sensory neuropathies. Methods A cohort of 23 patients performed the 6MWT and time function tests (time to run 10 m, to rise from a supine position, and to climb four stairs), as well as the chair rising test (CRT) and the single two-legged jump (S2LJ) on a mechanography ground reaction force platform. Results were correlated calculating linear regression. Results Correlation revealed high or moderate correlation between mechanography and the 6MWT and the time function tests: S2LJ/6MWT = 0.64; CRT/6MWT = 0.52; S2LJ/rising from floor = 0.63; CRT/rising from floor = 0.67; S2LJ/10 m run = 0.74; CRT/10 m run = 0.66; S2LJ/climb four stairs = 0.56; CRT/climb four stairs = 0.47. Conclusion Jumping mechanography is a good additional tool for the assessment of pediatric patients with Charcot-Marie-Tooth disease and might be used for primary outcome measures. It was not feasible in more advanced stages of the disease. In less disabled children, the S2LJ, which quantifies force generated by proximal and distal muscles, might be superior to other tests.