Lower leg pain is more common in patients who participate in running or walking activities. The waste-basket diagnosis for many patients is often "shin-splints," however, this ill-defined entity may mimic or overlap with other causes. Certainly less common, yet significant differentials are stress fracture and compartment syndrome. In the elderly, calf pain may appear insidiously or arise secondary to minor trauma (e.g., bumping the leg against a coffee table). If the older patient is also active, a distinction between muscle sprain, shin-splints, or deep vein thrombosis is not as clear as one might first assume.
Shin Splints
While shin splints is a common diagnosis, the actual entity is not well understood. Depending on who you ask, shin splints are defined as a form of tendinitis, periostitis, muscle strain, or interosseous muscle strain. Various authors have attempted to classify shin-splints based on the source of pathology, but this too has led to much confusion. You may see classifications that include stress fracture and compartment syndrome under the main heading of shin splints. The rationale for this classification is that the underlying cause of these different entities is the same and that they may represent different degrees or sites of "stress" reaction. The underlying causes appear to fit two general categories: (1) muscles that serve the function of shock absorbers allow forces to be transmitted to bone if they are weak; and (2) repetitive overstrain of muscles or tendons causes strain or sprain, or excessively stress the bony origin of the muscle involved.
Generally, shin splints are geographically classified as anterior/lateral and posterior/medial. The anterior type is generally due to walking or running on hard surfaces or poor shock absorbing ability of the involved muscles or shoes. The tibialis anterior, extensor hallucis longus and extensor digitorum longus all act to dissipate the forces imposed by heel strike. If they are weak or asked to perform overtime, shin splints may result. It has been demonstrated electromyographically that the tibialis anterior fires at greater than 20% maximum contraction for 85% of the gait cycle in runners.1 This will lead to fatigue if the muscle is not properly trained or an extra burden of performing on a hard surface is added.
Posterior/medial type is common in athletes who are hyperpronated or who perform on a surface that imposes excessive or prolonged pronation. Therefore, the muscles that help support the arch are the most commonly affected. These muscles include the tibialis posterior, flexor hallucis longus, and the flexor digitorum longus muscles. You may read of the medial tibial stress syndrome.2 This is a broad classification system that includes tendinitis (tibialis posterior), stress fracture, compartment syndrome, vascular, and muscle pathology. Therefore, medial tibial stress syndrome identifies conditions that share common etiology; excessive stress to the middle/distal tibia and its attachments.
Historically, it is important to determine any inciting activity. Sports with the highest frequency of shin splints include long distance running, jogging, race walking, aerobic dance, sprinting, cross country skiing, soccer, and volleyball. In addition, the surface that these activities are performed on must be determined. Hard surfaces require more shock absorption. Shoes that are worn or provide poor support or shock absorption may also be contributing factors. Tightness of the gastrocnemius may provide more resistance for anterior or medial muscles to overcome. Factors often missed include hydration and the amount of daily dietary calcium consumed.
Pain and/or tenderness for the anterior/lateral type is usually just lateral to the middle tibia. For the posterior/medial type, the pain and/or tenderness is posteromedial to the middle or lower tibia. Pain may be increased with contraction into dorsiflexion and inversion with the anterior type; resisted plantarflexion and inversion may increase pain with the posterior type. It is interesting that for some athletes, stretching to the involved muscles may increase pain, while for others, the pain is temporarily relieved. Also, performing a mild contraction from the stretch position for a few seconds followed by stretching seems to temporarily relieve the pain for many. Many patients report that squeezing the area with their hand provides some relief.
Radiographs are rarely needed unless stress fracture is being considered. With stress fracture, it is more likely that the patient has significant increase in pain with weightbearing that prevents further performance. Other clues are the bone status of young females, which may be related to the degree of activity and menstrual status.
Acute care for shin splints fits into four broad categories:
- ice and compression
- myofascial release
- functional taping
- modification of activity
Each of these approaches seems specifically effective in a subgroup of patients while ineffective with others. This may depend to some degree on the site of irritation or inflammation. If the site of irritation is at the tibia, taping may be the most effective approach while myofascial stripping or release may be more effective for muscle involvement. It will be interesting to see if further research can separate out these groups.
There are two general taping approaches. The first involves "compressing" or shortening the involved muscle/tendon through the use of elastic tape. The tape spirals from distal to proximal starting on the opposite side of the leg spiraling to the site of tenderness. For example, with the anterior/lateral type, the tape would first begin at the medial leg above the malleolus and spiral posterior ending at the site of tenderness at the anterior/lateral tibia.
The second type employs "strapping" tape. This is the same tape used by McConnell for patellofemoral tracking disorders.3 A thin protective tape is applied first (Fixomill Stretch, BDF Deiersdorf, AG Hamburg) followed by the strapping tape (Leukosport). The tape is applied as a functional support for the involved muscle. For example, if the tibialis posterior was involved, the tape would be applied to substitute or support the function of this muscle tendon on the medial side of the leg.
Preventative strategies include:
- replacing worn-out shoes
- evaluating the need for orthotics
- stretching prior to activity with emphasis on the gastrocnemius
- eccentric training of the involved muscles
- increase calcium to 1 gm/day
Next month, we will discuss compartment syndromes and stress fractures.
References
- Reber L, Perry J, Pink M. Muscular control of the ankle in running. Am J Sports Med 1993;21:805-810.
- Reid D. Sports Injury and Rehabilitation. New York, NY. Churchill Livingstone. 1992, p. 271.
- McConnell J. The management of chondromalacia patellae: a long term solution. Aust J Phys Ther 1986;32:215.
Thomas Souza, DC, DACBSP
San Jose, California
