Conquering Medial Tibial Stress Syndrome
Essential Diagnostic Insights
Diagnosing MTSS is relatively straightforward although a well directed history and physical are required to rule out other causes of exercise-induced leg pain. Athletes presenting with MTSS will typically complain of an aching pain at the middle to distal medial shin with activity (most commonly running). Medial tibial stress syndrome is similar to many overuse injuries in that athletes initially experience pain at the beginning of an activity. The pain then diminishes and often returns hours after completing the activity. These athletes generally achieve symptom relief with rest but the condition may progress to the point of causing pain even during inactivity. Eventually, athletes may experience pain throughout the offending activity to the point of impaired performance. This is often the point where the athlete seeks medical attention. A common scenario is for an athlete to present one to two weeks into a new season or training program. Keep in mind that bone remodeling typically starts five days after stimulation and leaves the bone in a relatively weakened state for approximately eight weeks.7 The hallmark of the physical exam is tenderness over a 4 to 6 cm area at the posteromedial margin of the middle to distal third of the tibia. This is in contrast to TSF, which presents with well localized point tenderness. Refer to “How To Differentiate Between MTSS And TSF” below) for other diagnostic differences between MTSS and TSF. The tenderness with MTSS may be exquisite and can often extend into the adjacent soft tissues. Mild soft tissue swelling and induration may be present. While researchers have described percussion, vibration with a tuning fork or using therapeutic ultrasound as adjunctive diagnostic maneuvers to help identify TSF, studies have shown these diagnostic tools have a low sensitivity.16 Passive stretch of the soleus, heel rises and unilateral hopping may reproduce symptoms. Radiographs are indicated to rule out TSF, infection or neoplasm but findings are generally normal with MTSS. Occasionally, one may observe cortical thickening due to chronic remodeling. If the patient is a competitive athlete or if suspicion for TSF is high, obtaining a triple phase 99Tc bone scan (TPBS) is indicated. The triple phase bone scan is highly sensitive for tibial stress injuries with the added advantage of being able to distinguish between MTSS and TSF. MTSS will generally (although not always) be positive, displaying a longitudinally or vertically oriented diffuse uptake on the delayed images only. Whereas false negative findings may occur with MTSS, TPBS is virtually 100 percent sensitive for TSF, demonstrating a focal, intense uptake of tracer on all three phases. MRI has become an increasingly utilized modality for assessing tibial stress injuries in athletes. It has also shed new light on the relationship between MTSS and TSF. Tibial stress fractures are clearly delineated on MRI and the sensitivity is similar to that of TPBS. In cases of acute MTSS, MRI will demonstrate findings consistent with tibial stress injury. However, chronic MTSS often demonstrates normal findings. Obtaining a MRI can also be helpful in differentiating MTSS from rarer longitudinal tibial stress fractures. With superior anatomic visualization, decreased radiation exposure and reasonable cost for a limited study, MRI is becoming a first line study for tibial stress injuries in many sports medicine practices.