Don’t Blame the Design!



Robert J. Nobilini, Ph.D., Biomechanical Engineer
Case Synopsis: A bartender slipped and fell on a wet ceramic tile floor, fracturing her patella. The plaintiff’s expert claimed that the design of the plaintiff’s footwear was the primary cause of the fall.
Expert Analysis: Plaintiff’s expert opined that the design of the footwear’s sole reduced its contact area with the floor, which reduced the slip resistance of the footwear. It was shown that slip resistance is independent of surface contact area. Therefore, the plaintiff’s expert’s opinion contradicted the laws of physics. Plaintiff’s expert stated that the midsole stiffness of the footwear increased the push-off force between the footwear and the floor. However, he failed to provide any scientific basis to support his opinion. In fact, the design of the incident footwear was shown to be similar to other footwear on the market. It was also shown that the expert made certain assumptions about the plaintiff’s fall mechanics that were incorrect. Therefore, the stiffness of the footwear was determined not to be a factor.
A biomechanical analysis of the woman’s fall mechanics revealed that her injuries were consistent with her lead foot slipping forward, causing her body to fall straight down onto her trailing knee. The floor was not available for examination; however, it was described as a ceramic tile floor, which had water and/or ice on it at the time of the incident. Since the plaintiff’s fall was consistent with a slip, there was no evidence that her footwear was a factor, and the slip resistance of ceramic tile is commonly reduced when wet and/or icy. As a result, it was determined that the primary cause of the plaintiff’s fall was the condition of the floor.
Result: Case settled.
Robert J. Nobilini, Ph.D., Biomechanical Engineer with DJS Associates, Inc., can be reached via email at or via phone at 215-659-2010.

Categories: Uncategorized

Tags: Biomechanical Engineer | Robert J. Nobilini


Have A Question About This Article or Want to Contact the Expert?

Request An Expert

Fill out the form below so we may refer an expert

Do you have a question for us? We’re here to help!

James Schmidt Expert Spotlight