Dr Mark S. Myerson, M.D. is the renowned Orthopedic and Medical Director for The Institute for Foot and Ankle Reconstruction at Mercy Medical Center, Baltimore, Maryland. Dr Myerson is one of the world's foremost experts on foot and ankle reconstruction and injury. He has pioneered surgical techniques that have revolutionized the diagnosis, treatment and recovery of disorders of the foot and ankle. His outstanding knowledge of foot and ankle conditions means that he is the expert of choice for many elite athletes from the NFL, NBA and European soccer leagues. PhysioRoom.com recently caught up with him to discuss the latest thinking on Fifth Metatarsal fractures.
Dr Myerson, what are the different types of fractures of the 5th metatarsal, and why are they treated differently?
"It is important to understand the anatomy of the 5th metatarsal in order to appreciate the nuances of injury and treatment. The metatarsal is divided into four anatomic segments (the base, the junction of the base and the shaft, the shaft, and the neck).
"Fractures of the base of the metatarsal are the most common, and occur as a result of a twisting injury of the foot or ankle. The ankle rolls inward (inverts), and there is a powerful ligament that attaches to the base of the metatarsal which pulls off a small bone fragment. This type of fracture is invariably treated without surgery, and immediate walking in a protective shoe or boot is ideal.
The junction between the base of the metatarsal and the shaft (the junction between the Metaphysis and Diaphysis of the bone) is the area which creates most problems when fractured. The reason for the difficulty is that bone healing relies upon a good circulation, and this particular area of the bone has a notoriously poor blood supply. Fractures of the shaft of the metatarsal occur commonly as a result of twisting of the foot when landing from a jump, for example in ballet dancers, and these heal very rapidly in a stiff shoe without any need for surgery."
5th metatarsal fractures have been quite common among elite soccer players in the English Premier League over the past five years. Do you have any thoughts why this injury seems more prevalent in this group?
"We must distinguish between the acute traumatic fracture (let us call this a Jones type fracture at the high risk zone of the metatarsal) and one that results from chronic repetitive fatigue (a typical stress fracture). The two fractures need to be approached differently.
"Why there has been a surge of these fractures in professional sports over the past decade is puzzling, since we have witnessed the same increased prevalence in the United States with all type of sports which involve pivoting, acceleration and deceleration. To some extent this may have something to do with the type of shoewear and the playing surface, but ultimately, in soccer, it is the lower leg body shape and the alignment of the leg and the foot which is the problem.
"I am sure that you have observed that many soccer players are slightly bow legged. This creates enormous stress on the outside of the foot and ankle. This is a simple fact of mechanics. If you imagine a bow leg, and you turn the foot inwards, there is naturally an increased stress on the outside of the foot, which in this instance means an increased stress on the 5th metatarsal. The back of the foot moves inward (inversion) and outward (eversion), and this occurs predominantly through the heel (the subtalar) joint. If the subtalar joint is stiff, then there is an even further decreased capacity for the foot to adapt on uneven ground surfaces, and an increased risk of stress fracture is present.
"Even in the normally shaped and aligned foot, there is in fact a triad of injury in the soccer player which one must look for, which includes a chronically unstable or loose ankle, injury to the Peroneal tendons, and stress fracture of the 5th metatarsal. These are the result of repetitive injury to the outside or lateral aspect of the foot and ankle from inversion type sprains. The ankle ligaments have limited capacity to heal once torn, and without external support, this puts the rest of the foot at risk for injury. With repeated inversion sprains, there is an increased stress or loading of the outside of the foot which includes the 5th metatarsal."
Why is the base of the 5 th metatarsal so susceptible to fatigue fracture?
"Firstly, this is a susceptible metatarsal. It is on the outside of the foot, so that naturally there would be an increased incidence of fractures as a result of inversion injury (as described above). However, it is the repetitive nature of the loads applied to the Metatarsal beyond the body's capacity for healing which leads to the development a frank or 'complete' stress fracture.
"The sensation of aching and soreness along the outer aspect of the foot is critical, since this represents 'overstress' or fatigue of the bone prior to going on to a complete stress fracture. Typically, this soreness occurs following a game, and dissipates by the following day. If the exercise continues without protecting the metatarsal, the stresses also continue, and then the soreness begins earlier in the game, a condition we refer to as the 'crescendo effect' of stress. Changing activities or protecting the foot at this stage may prevent a true stress fracture from occurring.
"In summary then, it is the training patterns, the location of the Metatarsal, a lack of adequate blood supply to that part of the bone, a limited capacity for rapid bone healing, and if any biomechanical abnormality of the leg or hindfoot exists, then there is a greater propensity for stress fracture."
Delayed union and non union of the fracture of the 5th metatarsal are more common. Why is this?
"This is all the result of a decrease in the blood supply to the metatarsal, specifically in the high risk zone where the Jones fracture occurs. To some extent this also depends upon the manner in which the fracture is initially treated. Unless an adequate bone healing response is initiated at the onset of fracture, the bone quality itself gets even worse. The bone gets thicker (a condition we refer to as sclerosis), and as this sclerosis worsens, the microscopic blood supply also has less ability to penetrate and heal the bone."
What is the state of the art management of a Jones Fracture?
"Let us distinguish between an acute Jones fracture and a stress fracture of the base of the 5th metatarsal which occurs in the same region. The acute Jones fracture occurs as a result of an explosive force or acute injury, and the stress fracture is more insidious and associated with gradually worsening symptoms, until bone failure occurs.
"Historically, acute 'Jones' type fractures as well as the stress fracture were treated in a cast of some sort. However, it was noted that healing was particularly poor with both types of fracture. At that time, it was recommended that if a cast or boot were used, then the patient should not be allowed to bear weight for 6 weeks. While the rate of healing improved with this regimen, the success of this treatment was still inadequate, and this type of restricted activity is not an acceptable treatment in the athlete.
"For both the acute Jones fracture and chronic stress fracture operative treatment with a screw is ideal. It is not necessary to open the skin with a large incision to fix the fracture at all. We use a tiny puncture in the skin, and then insert a small pin into the Metatarsal guided with a live X-Ray machine called 'fluoroscopy'. Once the pin has been inserted across the fracture into the canal of the metatarsal, it is then easy to insert a screw into the shaft of the metatarsal to facilitate healing. The size and type of the screw are very important. Athletes are allowed to bear weight on the foot immediately following surgery in a boot, but limit impact loading of the foot, particularly twisting activities.
"Physiotherapy is an essential part of the recovery, maintaining flexibility of the foot, decreasing swelling, and stimulating tissue healing. We use an external bone stimulator in all athletes which is applied to the foot daily to speed up the healing process. Exercise can begin in a single plane (bike, elliptical trainer, swimming pool) by 4 weeks, but monitored according to swelling and discomfort. Running in a pool, with the help of a buoyancy belt, followed by running on a hard surface can begin once soreness is relieved, usually at 6-8 weeks, and then finally a return to full activities including twisting and pivoting by 8-10 weeks."
There have been some recent high profile cases of re-fracture of the 5th metatarsal in elite athletes, even after surgical fixation. How are these cases salvaged?
"Firstly, one has to identify the cause of the failure. Make sure that there is no problem with the alignment of the leg and the heel. Be certain that the foot had been adequately protected during the recovery process, including the use of a good, carefully designed orthotic arch support for the shoe.
"The surgeon should look at the type of screw used. Was it the correct size and length? Did the screw itself cause the problem or the failure by inadequately supporting the Metatarsal because it was too small? Is the problem in the bone itself? For example, following failure of screw treatment the bone can thicken and harden, a condition called bone sclerosis, which makes it very difficult to get the bone to heal. Was an incision used to fix the fracture? Ideally, an incision should not be used, since this increases the risk of a non union since the blood circulation to the bone is disturbed.
"In order to salvage a non union, particularly when the bone is poor or the screw is bent or broken, the fracture needs to be opened, the bone stimulated and a correct size appropriate screw used. Wherever possible, I try to avoid opening the fracture, however, this may have to be done in order to insert a bone graft. I use a small amount of bone graft and add blood cells which are aspirated using a small specially designed syringe from the pelvis to stimulate the production of new bone. This puncture in the pelvis is surprisingly painless and adds a vital part of the surgery to be able to stimulate the bone. However possible therefore, the bone is stimulated, and I use a specially designed tiny drill to perforate the bone, create channels in the bone which then permit blood flow and ultimately speed up the healing. The recovery and treatment following revision surgery is slower, more cautious but generally follows along similar program which I have outlined above."
For more information please visit The Institute for Foot and Ankle Reconstruction at Mercy website at footandankle.mdmercy.com.