Independent Report – Part 1: Drop Rig Assessment
Football injuries are generally divided into two categories:
- Traumatic; and
Traumatic injuries are caused by an acute external force which exceeds the maximum durability of a tissue (bone, muscle, tendon, ligament) during one specific event, such as a tackle or high impact force. A one-off high load, such as those found in tackles of collisions, applied to a region can cause structural failure in tissues – this is also true for lower loads that are repeatedly applied.
Metatarsal injuries are the most common traumatic foot injuries causing debilitating pain and lost sports time.
The Metatarus consists of the five long bones of the foot, which are numbered from the medial side. The larger of these bones, the OS metatarsale 1 is the most exposed is more likely to be damaged. This bone is the metatarsal attached to the “great toe” or big toes and the bone that is responsible for distribution of weight when walking. The remaining four bones, OS metatarsale 2 – 5 are attached in turn to the remaining four toes of the foot and assist with balance when walking. These bones are protected by Zock to reduce or prevent injury.
Metatarsal injury facts:
- Is a devastating personal injury
- Painful and debilitating
- Required long term rehabilitation process
Proximal fifth metatarsal metaphyseal fractures (PFMMF) have been reported with increasing frequency in aethletes.
A drop rig designed to assess impact forces of the foot was used in this study. The drop rig consisted of a prosthetic foot connected to a 40kg mass, resulting in a combined 42kg mass that was dropped from a height of 1cm onto the Zock.
Data was collected in Qualisys Track Manager using an AMTI BP400600 force platform sampling at 10,000HZ with an upper limit of 2,800N.
In total, two sets of drop-rig tests were performed. The first set of tests assessed the material’s reaction to a one-off impact. Five drop rig trials were performed on different areas of the material to avoid a repeated loading effect on one specific area. The second set of tests assessed the endurance of the material over 20 drop-rig trials with 30 second intervals between each trial.
The Zock, consists of 4mm hexagons surrounded by thinner 2mm areas, as seen here:
Before the assessment of the Zock, 5 drop-rig trials were performed directly on to the force platform from a height of 1cm without any material, in order to calculate the peak impact force and loading rate.
The results showed a significant reduction in the impact force!
Several studies have reported that PFMMFs are challenging to treat. Furthermore, healing problems, delayed union and re-fractures have been shown to occur with PFMMFs. Although fifth metatarsal fractures often occur, thereby increasing the probability of a re-fracture especially in athletes who return early to sporting activity, to the best of our knowledge there are no reports of techniques or methods to prevent these fractures.
Zock reduces peak impact force and loading rates and could be used to reduce the physiological loads on the dorsal aspect of the foot, which in turn has the potential to move these loads out of the zone of supra-physiological loading and into the envelope of function and, therefore, reducing foot injuries.
Research was conducted by The University of Central Lancashire, at the Allied Health Research Unit in 2017.