Posterior Tibial Tendinitis: A Case study

Subject

The subject was a 27 year old male runner with a history of right medial shin pain of 2 months duration. He first noticed discomfort after a particularly heavy weekend run schedule over a very hilly course. His mileage was increasing weekly in preparation for a Marathon. At the time of initial injury he was running approximately 20 miles per week.

The pain increased as he steadily increased his mileage until after one 20 mile run his right lower leg experienced pins and needles and remained very sore for several days after, walking was painful, running was impossible. He went via his GP to A local hospital Sports Injury Clinic where he was seen by a consultant who had the limb X-Rayed no abnormalities seen and bone scanned which showed a hot spot along the medial aspect of the tibia and around the medial malleolus. A diagnosis of posterior tibial tendinitis with periostitis at he origin of the muscle was made. He was advised to stop running, offered a hydrocortisone injection which he declined and was sent to see a physiotherapist. The physiotherapist treated him with various modalities electrical and physical and he slowly returned to running. He ran short distances at first gradually increasing but as soon as he reached two to three miles the pain would return. The physiotherapist had noted the feet were "not right" and advised him to see a podiatrist with a view to gait analysis.

AETIOLOGY

It is known that the rate of impact as well as the amount of load will affect the degree of damage to a tendon (Nordin, Frankel 1989). Generally, tendon injuries are influenced by the amount of force produced by the contraction of the muscle to which the tendon is attached and the cross sectional area of the tendon in relation to that of its muscle.

The posterior tibial muscle by virtue of its course and attachments, primarily to the navicular bone (plantar medial aspect) the tendon then divides to insert distally into the three cuneiforms, the cuboid and the bases of 2nd, 3rd, and 4th metatarsals, acts as a major player in the control of pronation at sub talar and midtarsal joints. A tendon slip is also sent posteriorly to attach to the sustentaculum tali, which helps stabilise the navicular. The tendon has 2 pulley arrangements the first being around the medial malleolus and the second at the navicular where the tendon divides and turns to angle obliquely in a lateral anterior direction to its final attachments. Thus the posterior tibial muscle is a strong supinator and invertor of the sub talar joint that functions to control and reverse pronation during gait. It decelerates sub talar joint pronation and tibial internal rotation at heel strike and then reverses its function to accelerate sub talar supination and tibial external rotation during stance. The posterior tibial muscle also maintains the stability of the midtarsal joint in the direction of supination around it oblique axis during the stance phase of gait (Andrews and Harrelson 1991).

The comparatively long tendon of the posterior tibial muscle and its attachment to the navicular which is know to lower in cases of excessive pronation of rear and forefoot will lead to an increased stress on the tendon as the navicular is lowered during stance phase. Also the tension in the tendon will lead to an increased contraction of the muscle belly for a longer time than normal as it attempts to reduce sub talar and then midtarsal joint pronation this will further increase the tension in the tendon. This will increase as the subject increases speed, as the pronation increases. The repetitive tugging on the tendon with every step during the run is thought to be the underlying cause of the tendinitis seen.

In this subject with marked over pronation and varus forefoot etc he is predisposed to this condition (Sommer H, Vallentyne S. 1995)(Viitasalo J., Kvist M. 1983). The excessive pronation and the repeated stress of hill running requiring maximum dorsiflexion of the foot would in part have been resolved at the midtarsal joint particularly stressing the posterior tibial muscle.

Donatelli (1996) states: When excessive pronation is present after heel strike, eccentric over activation of the muscle attempts to support the medial arch and navicular bone of the foot, resulting in strain and microtears of the tendon. The shoes being used by the subject were more than 1 year old and had been used extensively. They were not helping the condition as they had deformed at the medial longitudinal arch and the heel counter had been broken down so that it offered no resistance to heel eversion.

Assessment & Examination

The patient was examined sitting and standing and walking on a treadmill. The pain could be illicited locally on direct pressure and forced pronation of the foot was also painful. The feet exhibited a good range of motion at all joints with some limitation of 1st MTP joints in dorsiflexion especially the right foot.

On Standing the feet were noticeably pronated with marked calcaneal eversion especially of the right foot and the lower limbs internally rotated. There was obvious tibial bowing and he was mildly bowlegged. With the sub talar joint in neutral position it was noted that the right leg was longer and there was marked forefoot varus present. This was less so on the left foot.

>On the treadmill which was video recorded for later viewing he exhibited rapid pronation at heel contact and throughout the stance phase of gait and through into the propulsive phase. So that at toe off he was rolling off the side of his big toe where he had a consequently heavy callous. The shoes as mentioned above were inadequate for their purpose.

Using a digital biometer the following measurements were taken with the subject standing:

If possible one would have used a two or three camera video kinematic technique to allow scientific assessment of gait parameters such as duration of pronation and velocity of rear foot pronation, internal rotation of lower limb, tibial varum and such measures with and without footwear and eventually with orthoses.

An electromyographic study of the posterior tibial muscle one would expect to show an increased duration and intensity of action. A normal duration of action for this muscle in walking is from just after heel contact until heel lift or just after.

>A force plate examination would show the forces involved in direction and time and confirm the pronated function particularly of the right foot.

Treatment

The main thrust of the treatment was to reduce the amount of and duration of the rear foot pronation seen in the feet. (Andrews. Harrelson 1991). This was done by the fabrication of a semi rigid orthotic device for both feet posted according to the measurements taken above. Thus the right foot orthotic was posted rear foot 10 degrees varus and the forefoot 5 degrees varus, whilst the left orthotic was posted rear foot 5 degrees and forefoot 2 degrees. Several authors have shown the effectiveness of orthoses in controlling rear foot pronation (Johanson et all 1994) (Gross and Napoli 1993), (Nawoczenski et al 1995) and (McCulloch et al 1993). Taping after Macdonald (1987) was applied to the right foot and leg to provide compression and to help resist stretching of the affected tendon along its course. The subject was advised to purchase new running shoes that were reinforced medially to help prevent over pronation with a stiff heel counter to assist in the same way. Shock absorbing properties of the shoe are also important to decrease the shock wave through foot and in particular the tendon, at heel strike. The orthoses should control the extra pronation that is caused by the extra shock absorbing properties of the shoe.

A short course of non-steroidal anti-inflammatory medication was suggested as this has been shown likely to increase the rate of biomechanical restoration of tendon (Nordin and Frankel 1989). They further state that ligaments and tendons remodel in response to the mechanical demands placed upon them. Thus if the excessive amount of pronation can be controlled by the orthoses and so reduce the pull on the tendon a full recovery should be enabled.

Advice was given when returning to running to run on grass or forest grounds or cinder paths, as these are less strenuous compared to asphalt or tartan paths. (Nitzschke and Leonhardt 1991). Running on hard non-compliant sport surfaces has been shown by (Richie et al 1993) to specifically predispose to shin muscle damage.

The subject wore the orthoses every time he ran and gradually over a period of 1 month increased his running with minimal discomfort which after 1 further month disappeared completely.