Saturday, 1 September 2012

Knee Pain in Runners

Overview and Clinical Observation of Knee Pain in Runners

The knee joint has a high rate of injury in runners and is subject to large forces during the gait cycle. The vast majority of knee injuries related to running are overuse in nature. The focus of this post will be an overview of running related knee injuries with further posts looking at specifics, healing times and treatment options.

The knee is a hinge joint with an arrangement of ligaments, bursa, cartilage and connective tissue in abundance. It is a simple design with fairly simple mechanics yet can become quite troublesome in chronic issues.

Fig 1. Surface anatomy of the knee. Dysfunction above and below the knee will increase loading through the joint.

Pain may present as anterior, anteriomedial, medial, lateral or posteriorly. The site of injury will dictate what type of tissue involvement there is, unless of course, referred pain is present (radicular or other).

From a broad perspective the big considerations on knee loading are the effect from the SIJ/hip above (lumbo-pelvic mechanics) and the functioning of the foot below. Poor mechanics of the lumbo-pelvic region considerably load the tissues of the knee in an uneven fashion typically resulting in pain and/or dysfunction. The glutes (medius and minimus), adductors and the VMO (medial portion of the lower quads) should function synergistically to provide optimal stability and transfer the load from the foot to the SIJ. This allows the knee to be in the best position mechanically.

Pelvic position will ultimately affect the loading of the lower limb and in particular the knee. As previously discussed in the biomechanics of running posture a pelvis rotated posteriorly will ultimately end in an overstride pattern typically landing in a heel first and knee locked position. This loads the joint and does not take advantage of the hamstring during mid-stance and hip extension.

Inability of the glutes to fire in time (late) or not at all will give rise to internal hip rotation, internal knee rotation and internal foot rotation as a consequence. In this case the knee injury is a consequence of poor lumbo-pelvic control. Treatment directed at the knee only will be a less than adequate result and certainly not optimal.

The mechanics of the foot itself may be a causative factor. As the foot makes contact with the ground, pronation typically occurs. Pronation attenuates the forces through the foot, allowing load to be spread across the foot. Pronation is desirable – it’s just how much and at what rate (as discussed in previous posts).  Excessive pronation may be due to a variety of factors, it is paramount to assess why this is occurring.

Further up the chain the thoracic may also be a factor to consider. The thoracic is largely influenced by arm swing, in particular, the amount and site of rotation that takes place. This has been discussed in a previous post and considers the effect of rotation on the lumbo-pelvic region and it’s flow on effect to the knee and foot.
Knee pain must take into consideration the biomechanics of the individual’s running posture and the causative factor. Treatment should be directed at alleviating these.

Further posts will look at different knee injuries common in the distance runner.

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