Injury Breakdown: Details On The Disc
By Abby Sims
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Mathias Kiwanuka will be out of action for an undetermined period of time after receiving a diagnosis of a bulging cervical disc. Though he had reportedly only complained of stiffness in his neck, a precautionary MRI revealed the extent of Kiwanuka's injury. The Giants and Kiwanuka would be smart to play this one safe, particularly due to the nature of the sport and the inherent risk involved even when there is no known injury.
Explaining the spine
The spine is the support system for the head and trunk and it encases and protects the spinal cord, from which the many nerves of the upper and lower body emerge. The bones of the spine are called vertebrae, and with the exception of those at the very top and at the lowermost segments, the bodies of the vertebrae are separated by discs. In addition to the vertebral bodies, which are at the front of the spine, other bony components at the sides and back of the vertebrae surround the cord and have openings through which the nerves exit the spinal column.
The role of the discs is to connect one vertebra to another (vertebrae also connect via small joints on either side) while allowing for movement between them. Discs also contribute to the stability of the spine and provide shock absorbency. The shape of both the bodies of the vertebrae and the discs, which vary by section of the spine, results in the natural and normal spinal curvature that enables it to best serve our needs.
The spine is divided into five segments. The neck, or cervical spine is the uppermost portion; it is comprised of seven vertebrae. Below the cervical spine is the thoracic region, whose 12 vertebrae also serve as attachments to the ribs via cartilage. It is this cartilage that Michael Vick reportedly bruised in the brutal double hit yesterday that led team doctors to initially suspect a rib fracture. The lumbar spine in the low back has 5 thick vertebrae. Below the lumbar spine is the sacrum, which lies between the two pelvic bones. It is actually one bone that was formed by the fusing of what initially were five. The lowermost segment is the coccyx, or tailbone.
What is a bulging disc? A herniated disc? A slipped disc?
Trick question, technically, there is no such thing as a slipped disc.
Discs have a firm fibrocartilaginous exterior rim and a softer, more gelatinous interior that contains a great deal of water, collagen and proteins. Discs help to resist compressive loading of the spine, and they are most often injured in the neck and low back because these are the regions where there is the greatest movement and stress to the spine. Though cervical discs commonly sustain injuries in the lower segments of the cervical spine, studies have demonstrated that football players have an unusual number of injuries to the disc between the third and fourth vertebrae when they lead with the helmet in making a tackle. I have not seen reports of the level of Kiwanuka's injury (See Wheeless' Textbook of Orthopaedics).
When the firm outer rim of the disc bulges, the injury is less likely to produce significant neurologic symptoms. This is because the disc has not actually torn and so the inner gel of the disc remains contained. The area may hurt because of stimulation of pain receptors and other nerve endings, localized swelling and inflammation. When the disc tears, or herniates, the inner portion leaks out and can create more significant pressure on the nerve roots, where the nerves exit the spine, or on the spinal cord itself. Some herniations cause only sensory symptoms such as numbness or tingling, while others also cause motor symptoms, or weakness. The type and degree of symptoms depends on which portion of the disc herniates and where the resulting pressure occurs. Symptoms include neck pain, radiating pain, and/or numbness or weakness into the arm or hand on the same side as the disc herniation. If symptoms occur on both sides, it is likely that the herniation is more central rather than on one side or the other. Pain is generally intensified with movement of the neck, particularly leaning backward into an extended posture. The nerve may be further compressed by turning the head toward the involved side, increasing symptoms.
There are other conditions that can result in symptoms similar to those from a cervical disc herniation. Nerves can be compressed in the wrist causing symptoms in the hand (as from Carpal Tunnel Syndrome), in the elbow region (causing symptoms below the elbow), or even in the region of the first rib (Thoracic Outlet Syndrome). Tightness in the nerves in the upper extremity can also result in numbness and tingling symptoms in the arm and hand and can be very easily addressed. Obtaining an accurate diagnosis is very important.
Mathias Kiwanuka will be on the sidelines in the hope that his bulging disc resolves. By not playing he is taking an important precaution to avoid allowing an already vulnerable disc to progress to herniation.
Abby Sims is an orthopedic and sports physical therapist who has been in private practice in NYC for the past 30 years (you may be familiar with her husband, sportscaster & WFAN alum Dave Sims). Abby has a Masters of Science in Physical Therapy from Duke University and has extensive experience working with professional, collegiate and recreational athletes with musculoskeletal injuries – both non-operative and operative. She has also enjoyed lecturing at many medical conferences. Abby looks forward to responding to your questions or writing about topics that you suggest. For more information about Abby, or her practice, please check out www.RecoveryPT.com as well as www.AthletiSense.com.
