Don’t Blame the Design!

Bar

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. Continue reading “Don’t Blame the Design!”

Don’t Always Blame the Tread and Riser for the Fall

stairs-expert-witness

Robert J. Nobilini, Ph.D., Biomechanical Engineer
Case Synopsis: Plaintiff testified that she was in the process of descending a flight of stairs, one step at a time. She had stepped down onto the first tread with both feet and was stepping down onto the second tread with her right foot when her foot went out in front of her. The heel of her foot barely contacted the front edge of the second tread, and she fell backwards down the rest of the stairs.
Expert Analysis: Plaintiff’s expert opined that the stair treads were shorter than what was required by present code and that there were inconsistencies in the tread and riser dimensions. He concluded that the plaintiff’s fall was due to these issues. Continue reading “Don’t Always Blame the Tread and Riser for the Fall”

Which Impact Caused Plaintiff’s Injuries?

Robert J. Nobilini, Ph.D., Biomechanical Engineer
Case Synopsis: Plaintiff was the operator of a vehicle that was initially impacted on the front driver’s side corner by a vehicle prior to being struck in the rear by a second vehicle. Plaintiff incurred a left shoulder supraspinatus tendon tear during the subject incident. It was requested that the dynamics of the two impacts be examined to determine which impact caused the plaintiff’s left shoulder injury. Continue reading “Which Impact Caused Plaintiff’s Injuries?”

Pedestrian v. Vehicle Collision: A Biomechanical Analysis

jaywalking

Robert J. Nobilini, Ph.D., Biomechanical Engineer
Case Synopsis: A pedestrian was crossing the road when he was struck by a passing vehicle. The plaintiff stated that he had a green light, looked both ways, and stepped out into the street when he noticed the defendant’s vehicle approaching at a high rate of speed. The plaintiff testified that when he observed the vehicle, he attempted to jump back, but his right leg was struck by the front passenger side corner of the defendant’s vehicle. The defendant claimed that the plaintiff ran out into the roadway from between two parked cars and into the rear passenger side of his vehicle. Continue reading “Pedestrian v. Vehicle Collision: A Biomechanical Analysis”

Cervical Injuries Causally Related to Defective Amusement Ride

Biomechanical-Expert-Witness

Robert J. Nobilini, Ph.D., Biomechanical Engineer
Case Synopsis: The plaintiff was riding a rollercoaster style ride at an amusement park when she incurred significant cervical injuries. Plaintiff described being thrown sideways to her right, feeling pain in her neck, and immediately experiencing neurological symptoms from the neck down. When the car returned to the station, the plaintiff could not feel or control her extremities.
Expert Analysis: An examination of plaintiff’s medical records revealed that she had incurred a herniated nucleus pulposus at the C5-6 level of her cervical spine with spinal cord impingement. During her deposition, plaintiff described that the car went into a sharp left turn, throwing her to the right, causing her right shoulder to strike the padded metal restraint rail that was mounted to the car. An examination of the subject ride revealed that the right siderail on the incident car was bent outward. Maintenance records for the ride revealed that the park was having issues with the speed of the ride increasing over the months leading up to the incident. It was determined that the increased speed of the ride, particularly as the cars moved through the sharp turns, created higher than expected lateral loads on patrons. The outward bending of the right siderails on the incident car was evidence that patrons were being thrown laterally into the rail with great force. During the incident, the plaintiff was thrown laterally towards the rail. Because the rail was displaced outward, the plaintiff was able to accelerate over a greater distance before striking the rail. As a result, she struck the rail at a greater than expected velocity, exposing her to a higher rate of deceleration. As plaintiff’s right shoulder struck the rail, her head continued to move laterally, forcing her cervical spine into extreme side bending, which resulted in her injuries. Continue reading “Cervical Injuries Causally Related to Defective Amusement Ride”

Don’t always blame the Tread and Riser for the Fall

Flight of Stairs Engineer

Robert J. Nobilini, Ph.D., Biomechanical Engineer ::::
Case Synopsis: Plaintiff testified that she was in the process of descending a flight of stairs, one step at a time. She had stepped down onto the first tread with both feet and was stepping down onto the second tread with her right foot when her foot went out in front of her. The heel of her foot barely contacted the front edge of the second tread, and she fell backwards down the rest of the stairs.
Expert Analysis: Plaintiff’s expert opined that the stair treads were shorter than what was required by present code and that there were inconsistencies in the tread and riser dimensions. He concluded that the plaintiff’s fall was due to these issues.
Plaintiff’s medical records revealed that 16 years prior to her fall she was diagnosed with avascular necrosis of the left hip due to osteoporosis and underwent a hip replacement. Since her hip replacement, she descended stairs one step at a time. Four months prior to her fall, she underwent a revision of her left hip.
Biomechanical research has shown that descending stairs too slowly lengthens the time a person has to support their weight on one leg and increases the risk of a fall. Plaintiff’s testimony that her right leg went out in front of her and that she barely contacted the front edge of the second tread was consistent with the plaintiff’s left leg giving way due to her prior left hip issues. As a result, her center of mass began falling backwards causing her right foot to move forward of the second tread. Continue reading “Don’t always blame the Tread and Riser for the Fall”

Plaintiff Incurs Spinal Cord Injury on Rollercoaster

biomechanical-expert-witness-rollercoaster-accident

Robert J. Nobilini, Ph.D., Biomechanical Engineer ::::
Case Synopsis: The plaintiff was injured while riding a rollercoaster. He testified that the ride was “awfully bumpy” and when the ride ended, he was unable to move. He was taken to the hospital and diagnosed with a distraction fracture and spinal cord injury at the C6-7 level of his cervical spine along with previously undiagnosed ankylosing spondylitis.
Expert Analysis: An examination of the subject rollercoaster revealed the presences of brackets on the sides of the track. These brackets contained adjustment screws, which pushed inward on the rails of the track. It was observed that numerous brackets were broken and/or non-functional. Subsequently, it was discovered that these brackets had been installed sometime after the initial installation of the ride to maintain the gauge of the track.
Further investigation revealed that when the ride initially opened, the cars were slapping hard in the turns, which was causing the axles on the cars to break. It was determined that the reason the axles were breaking was because the gauge of the track was widening. To stop the axles from braking, gauge brackets were installed to maintain the gauge of the track. Several years later, the cars were rebuilt with stronger axles. Since the axles were stronger, it was determined that the gauge brackets were no longer needed. Some of the brackets were removed and others were loosened and abandoned. As a result, the gauge of the track widened over time and the cars began to slap hard in the turns again.
The slapping of the cars in the turns increased the lateral loads on the cars, as well as on the patrons of the ride. The ride owner was aware and concerned about the effect of the increased lateral loads on the axles of the cars. However, once the strength of the axles was increased, no consideration was given to the patrons of the ride.
The plaintiff in this case had an undiagnosed, pre-existing condition (i.e. ankylosing spondylitis), which increased his risk of injury. The ride owner’s failure to properly maintain the gauge of the track resulted in the plaintiff being exposed to higher than intended lateral loads. These loads, in combination with the plaintiff’s pre-existing condition, were the cause of his injuries.
Results: The case settled favorably for the plaintiff.
Robert J. Nobilini, Ph.D., Biomechanical Engineer with DJS Associates, can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Defective Gym Equipment

defective gym equipment

Robert J. Nobilini, Ph.D., Biomechanical Consultant ::::
Case Synopsis: While working out at a gym, the plaintiff was attempting to perform an abdominal crunch using an adjustable pulley weight machine when the cable on the machine suddenly broke causing the plaintiff to strike her face on the ground.
Expert Analysis: An examination of the incident equipment revealed that the subject cable traveled through a set of metal brackets and then up and over a pulley. A rubber ball was installed on the end of the cable just above the accessory attachment clip. This ball would interact with the metal brackets that were below the pulley to prevent the end of the cable from traveling back into the machine. Continue reading “Defective Gym Equipment”

Walkway Defect or Human Error?

Robert J. Nobilini, Ph.D., Biomechanical Engineer ::::
Case Synopsis: Plaintiff was a middle-aged male, who incurred a rupture of his patella tendon while playing basketball. He claimed that his injury was due to him stepping into a patched area on the court surface that he contended was depressed by about 2 to 3 inches. It was requested that a biomechanical analysis be performed to determine if there was a causal relationship between the alleged court defect and the plaintiff’s injury.
Expert Analysis: The patella tendon is part of the extensor mechanism of the knee. It is loaded every time the knee is extended. Biomechanical studies have quantified the load on the patella tendon as a multiple of body weight for various activities. Activities such as ascending stairs, running, kicking a soccer ball, and landing from a jump exert a force of 3.2 to 11 times body weight on the patella tendon, while the failure load of a healthy patella tendon is about 17.5 times body weight. Continue reading “Walkway Defect or Human Error?”