Shin Splints (Posterior Tibial Pain Syndrome)

The term ‘shin splints’, also known as posterior tibial syndrome, is a collective name for a group of overuse injuries that can develop in the middle and lower section of the shinbone (tibia). To understand how shin splints develop, it helps to know a little about the structures involved. The lower leg consists of two bones, the tibia and the fibula. These are connected by a strong sheet of connective tissue (the interosseous membrane). The bones are covered by a thin periosteum, which is richly supplied with blood and highly sensitive – as anyone who has banged their shin against something can confirm.

Several muscles originate from the lower leg. The most important ones involved in shin splints are the deep calf muscle (soleus), the posterior tibial muscle and the long toe flexor. During running, the forces acting on these muscles cannot always be absorbed properly, which places extra traction on the periosteum where the muscle attaches. Over time this can lead to tiny tears, which in turn trigger an inflammatory response in the surrounding tissue.

Symptoms

The main complaint is pain, usually felt over the middle and lower third of the shinbone. It can also be felt lower down, along the inner ankle, or higher up, even as far as the knee. The pain is often sharp in character, sometimes described as ‘stabbing’. In severe cases it is described as feeling like being struck with a stick – a clear sign that the runner has continued for too long despite the complaints. The pain is felt when the foot lands and when pushing off during running, and is sometimes also noticeable when squatting. The area is very tender to the touch, for example when crossing the legs. The pain can actually worsen at a slower running pace, and a slower pace generally produces more complaints. Depending on the severity, running may still be possible, though often the pain is too intense. Even after a period of rest, the complaints usually return if no further treatment is given. Occasionally there is slight superficial swelling at the painful spot, and the runner may feel a taut ‘cord’ under the skin.

Causes

There are several causes behind the development of shin splints, all affecting the structures around the shinbone described above. With shin splints, a distinction is made between factors originating from within the body itself (endogenous) and factors from outside the body (exogenous).

Endogenous factors

• An over-pronating running pattern. This is the most common cause. With overpronation, the foot rolls inward, the inner edge sinks, and the heel ends up at an angled position beneath the lower leg. This movement places greater strain on the posterior tibial muscle and on the foot and toe flexors. The deep calf muscle is stretched asymmetrically, placing greater load specifically on its attachment to the shinbone.
• Flat feet. The foot is too flexible, so the muscles involved are stretched excessively on landing. This increases the traction forces on the periosteum. This foot type is often accompanied by an over-pronating running pattern.
• Abnormal toe position (claw toes) can result from weak toe flexor muscles.
• A leg length difference creates asymmetrical loading of the lower leg muscles, which can show up as overuse on one side.
• Shortening of the deep calf muscle makes the attachment site more prone to overload.
• Ankle problems. With instability, greater demands are placed on the calf muscles. Limited mobility can also cause problems.

Exogenous factors

• A hard surface, or a switch from a softer to a harder surface while keeping training load the same. A harder surface comes with greater shock loading on the various tissues. The muscles have to absorb this load, producing greater traction forces at the bone attachment sites.
• An increase in training load, in intensity and/or duration, leads to greater direct loading. As training frequency increases, recovery time decreases.
• Insufficient warm-up and too little attention to stretching the calf muscles.
• Skipping the cool-down and neglecting strengthening of the calf and foot muscles.
• Continuing to train through mild early symptoms, resting, then immediately resuming full training.
• A slow running pace can cause more complaints because the stance phase lasts longer.
• Insufficient stability in footwear. Shoe stability is determined mainly by the heel counter and the sole, and the sole in particular needs to suit the runner's foot type, gait pattern, foot roll-off and body weight.

What can you do if the complaints have already developed?

Pay close attention to the onset of pain. A nagging pain during or shortly after sport is not normal! ‘Running through the pain’ only makes things worse. Shin pain can be the first sign of a stress fracture in the shinbone! To prevent things from getting worse, it is wise to follow the guidelines below in the early stage.

• Adjust your training. Timely modification or stopping of strenuous training is often enough to let an early-stage injury heal. Think of reducing speed work and adjusting the surface or footwear (spikes!) you train on. You can often maintain fitness by switching to other forms of exercise that don't place heavy strain on the calf muscles and shinbone, such as cycling, aqua jogging or using a stepper.
• Cooling. If the injury is still in an early stage, cool the shin with ice for about 15 minutes after training. This works best by massaging an ice cube along the painful spot. Repeat this ice massage 3 to 5 times a day. Even if the injury has persisted for longer, it can help to cool the shin several times a day.
• Massage. If the calf muscles are stiff, have them massaged.
• Sports medicine advice. If the measures above do not clearly reduce your complaints within two to four weeks, see your GP or a sports physician, working at a hospital or a Sports Medicine Centre. They can assess which treatment suits you best and whether new running shoes or custom orthopaedic insoles, fitted by an orthopaedic shoemaker, would be useful.

What can you do yourself to prevent these complaints?

• Good overall fitness and a thorough warm-up reduce the risk of shin irritation, preparing your muscles and the rest of your body for what's to come.
• A proper training cool-down.
• Suitable running shoes reduce the risk of shin irritation.
• Full recovery is the best way to prevent recurrence. Rehabilitation and adapted training support recovery, and a Sports Medicine Advice Centre or Sports Medicine Department of a hospital can provide excellent guidance for athletes and coaches.
• Even without an injury, it can be worthwhile to strengthen certain muscles or muscle groups. When strengthening exercises are part of a training programme aimed at building muscle, the load may be higher than in a programme aimed at recovering from an injury.
• Sometimes your body has certain deficiencies (such as a leg length difference) that can cause an injury. Make sure to correct these in good time to avoid unnecessary trouble.

Treatment by the physiotherapist

Shin complaints essentially involve chronic overload of a number of muscles, causing hairline tears at the attachment on the lower leg. A painful swelling with local signs of inflammation follows, for which rest in the acute phase is a good remedy. The downside of (prolonged) rest is that the strength of the muscles involved decreases. Before running load can be built back up to its previous level, muscle strength needs to be maintained or restored in an alternative way. This step is sometimes forgotten, increasing the risk that the complaints return. It is therefore recommended to have the condition treated, in order to build up the load tolerance of your muscles. Physiotherapy can help with this.

The exercise therapy consists of the following components:

• Stretching exercises
• Strengthening exercises
• Coordination exercises
• Stability exercises

This is often combined with local therapy, treating the painful spot itself or the muscle fibres along its course. This can involve:

• Transverse friction massage
• Dry needling
• Kinesiology tape

Additional adjustments may also be used, such as:

• Raising the medial arch of the foot to counteract excessive pronation and/or support the inner side of the foot.
• Stabilising the heel bone (calcaneus) to limit excessive movement.
• A heel raise in the footwear to compensate for any leg length difference.

If the complaints keep recurring, surgical treatment may be considered. This involves releasing and widening the membrane surrounding the muscles of the lower leg (the muscle compartment) to give the muscles more room.

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