Figure 2: Pronation

propel the body forward from the balls (metatarsophalangeal joints) of the foot and toes.

The ability to resupinate and

recover from pronation is paramount to normal effective functional gait. Failure to resupinate is often associated with functional hallux limitus and chronic postural problems (see below).

Figure 3: Supination

Figure 4: Severe heel eversion

ABNORMAL FOOT MECHANICS DURING GAIT The feet support the whole body weight. When things go wrong, problems can occur anywhere along the kinetic chain, including in the foot, ankle, shin, knee, hip, pelvis, sacroiliac joint and lower back. Abnormal movement (overpronation or underpronation) and incorrect timing of movement may predispose the individual to injury or magnify the symptoms that result from abnormal repetitive stress (2–4). Generally, patients with low- arched feet overpronate, and patients with high-arched rigid feet tend to underpronate and thus oversupinate. Many people inherit foot types that

Figure 5: Increased internal tibial rotation

are more likely to develop problems. Other foot problems arise because of injury or disease. According to Root and colleagues, abnormal subtalar joint pronation can be a result of forefoot varus, rearfoot varus, tibial varum, ankle joint equinus and plantar flexed first ray (5). Excessive pronation represents the most common biomechanical problem and is often cited as a key contributor in many overuse injuries of the lower limb and lower back (6). Excess pronation is synonymous with excessive calcaneal eversion (Fig. 4) and increased internal tibial rotation (Fig. 5).

Often asymmetrical gait develops. If left untreated, this can lead to abnormal postural changes. It is estimated that 75% of the population suffer from excessive pronation, from children to elderly people, from top athletes to people with a sedentary lifestyle (7). Although the majority of affected people exhibit excessive pronation, symptoms may present only following increased weight-bearing activity.

LOWER BACK PAIN Research indicates that at any one time 35% of the UK population has

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some form of lower back pain (LBP), which represents 7% of the workload of all general practitioners (8). LBP may arise from various aetiologies and various regional structures, including the lumbar spine, sacroiliac joints, hips, buttocks and pelvis. LBP may be due to disease, tumour, direct trauma, overuse, and abnormal or altered biomechanics. In order to establish a diagnosis, a thorough and systematic clinical examination must be undertaken. The patient should be screened for potential risks and contraindications, especially those with true pathology. In this article, our focus is on LBP purportedly attributed to excessive pronation.

Although LBP is often multifactorial,

and with overlapping conditions, we discuss the pathological effects of excessive pronation under three separate headings: gluteus medius syndrome, sacroiliac problems and lumbar spine problems.

CLINICAL IMPLICATIONS OF EXCESSIVE PRONATION Gluteus medius syndrome During mid-stance of gait, the foot should remain stable, thus effectively supporting the full body weight while the opposite leg swings forward. Failure to provide a stable platform (owing to excess pronation) compromises the ability of the muscles responsible for core and pelvic stability, particularly the gluteus medius. Consequently, the gluteus medius and other muscles cannot function efficiently. Over time the muscle becomes fatigued, weak, hypotonic and tender on palpation – “gluteus medius syndrome”. This often leads to abnormal pelvic movement, pelvic muscle imbalance and pelvic instability. Clinically the patient presents with a Trendelenburg gait (Fig. 6), frequently accompanied by hypertonic piriformis, tensor fascia lata, adductors and psoas muscles owing to their compensatory role. The patient may also present with apparent leg-length discrepancy. Pelvic instability and pelvic malalignment arising from excessive pronation are now recognised as predisposing factors for hamstring strains (9). Pelvic stability can be tested by observing the patient performing a single-leg squat; it is surprisingly common to see patients who have difficulty maintaining a level pelvis.

sportEX dynamics 2009;19(Jan):11-14

© PRIMAL PICTURES 2009