Origin of Pain in Medial Tibial Stress Syndrome (MTSS): Cadaveric Study

Research Review: Muscles Involved at the Site of Medial Tibial Stress Syndrome

By Nicholas Rolnick SPT, MS, CSCS

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Brown A. (2016). Medial tibial stress syndrome: muscles located at the site of pain. Scientifica. Volume 2016 (2016), Article ID 7097489 - Abstract

Caption: Illustration of a cross-section of the lower leg with lower extermity muscles and fascia labeled.

Cross Section of Lower Leg: By Braus, Hermann - Anatomie des Menschen: ein Lehrbuch für Studierende und Ärzte, Public Domain, https://commons.wikimedia.org/w/index.php?curid=29934112

Why is this relevant?: Medial Tibial Stress Syndrome (MTSS) is a commonly occurring overuse condition, commonly affecting individuals (females more than males) who perform high impact exercise (running, jumping, hopping, etc.). Initially, the symptom of MTSS is pain on the middle to distal third of the posteromedial border of the tibia upon the beginning of exercise that resolves with continued activity. In later stages of the syndrome, pain persists through activity and at rest. Previous research have associated increased occurrence of MTSS with excessive foot pronation and navicular drop (> 10 mm), gender (female), excessive hip external rotation in males, increased BMI, previous history of MTSS and stress fractures, running experience (< 5 years), and orthotic usage (1-3). However, theories behind the anatomic source of MTSS pain are conflicting, ranging from excessive myofascial strain to bone stress reaction - excessive bending or bowing of the tibia, and or excessive traction of the tibial periosteum at muscle attachment sites. The current study utilized a cadaver dissection methodology to discover the muscles that attach to the junction of the middle and distal third of the posterior tibia in an effort to lend support to the traction hypothesis.

Study Summary

Study Design	Cadaveric Dissection
Level of Evidence	Level 4: Observational Study Without Controls
Subject Demographics	Age: N/A Gender: 11 males, 2 females Characteristics: Cadavers 22 legs were used in the study from Ghana 9 were paired, 4 were unpaired Protocol Cadavers were preserved in 10% formaldehyde solution The skin and subcutaneous tissue were dissected off each leg The heads of gastrocnemius were removed and reflected to allow viewing of the deep posterior lower leg The ligaments that attached to the knee were removed, the joint capsule of the knee was opened, and medial meniscus was removed to expose the medial tibial condyle The ligaments of the ankle and the flexor retinaculum of the ankle were also removed to expose the medial malleolus The length of the tibia was measured using anthropomorphic calipers from the middle of the tibial plateau to the medial malleolus The distances from the distal and proximal attachment sites of the muscles that attach to the posteromedial border of the tibia were measured to the nearest 0.1 cm and then converted into percentages representing the length of their respective tibia This allowed comparisons to be made between tibias of different cadavers The posteromedial tibia was divided into thirds of equal length This allowed for each of the muscles on the posteromedial tibia to be compared with the common pain generating areas associated with MTSS Inclusion Criteria: N/A Exclusion Criteria: N/A
Outcome Measures	Structures that attach to the posteromedial tibia (including muscles and fascia) Quantification of where these structures attach to the posteromedial tibia
Results	Structures that attach to the posteromedial tibia Flexor Digitorum Longus - medial part of the posterior surface of the tibia inferior to the soleal line Soleus - posterior surface of the proximal fibula, soleal line, and posteromedial aspect of the tibia Crural Fascia Where these structures attach to the posteromedial tibia (Percentage of the length of the tibia +/- standard deviation) Flexor Digitorum Longus Proximal attachment - 33.3 +/- 3.4% Distal attachment - 59.6 +/- 2.7% Mean distance of muscle fiber attachment to tibia - 26.3 +/- 4.3% Soleus Proximal attachment - 49.5 +/- 3.4% Distal attachment - 72.5 +/- 1.8% Mean distance of muscle fiber attachment to tibia - 23.0 +/- 4.1% Deep crural fascia Proximal 2/3 Percentage of Specimens that have muscle fiber attachments in different segments of the posteromedial tibia (proximal, middle, or distal tibia) Flexor Digitorum Longus - 100% in middle third, 52.2% in distal third Soleus - 95.7% in proximal third, 100% in middle third Mean Percentage Distribution of the Length of the Attachment for Muscles in Different Segments of the Posteromedial Tibia Flexor Digitorum Longus - 88.1% in middle third, 11.9% in distal third Soleus - 27.3% in proximal third, 72.7% in middle third
Conclusions	The flexor digitorum longus and the soleus have direct muscular attachments to the posteromedial surface of the tibia; Tibialis posterior did not have any attachments to the posteromedial tibia The deep crural fascia has attachments to the proximal 2/3 of the posteromedial tibia
Conclusions of the Researchers	The muscular attachments for flexor digitorum longus and soleus provide anatomical rationale for the etiology of the pain origin of MTSS in the periosteal traction hypothesis, as 88.1% of the attachment of flexor digitorum longus and 72.7% of the attachment of soleus attach in the middle third of the posteromedial tibia The presence of the crural fascia in the proximal 2/3 of the posteromedial border of the tibia could also play a role in generation of pain in MTSS

By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 439, Public Domain, https://commons.wikimedia.org/w/index.php?curid=529088

Caption: By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 439, Public Domain, https://commons.wikimedia.org/w/index.php?curid=529088

Deep Posterior Compartment of the Leg - By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 439, Public Domain, https://commons.wikimedia.org/w/index.php?curid=529088

Review & Commentary:

The current study had strengths in its simple methodology. The author dissected 22 cadaveric legs with the goal of identifying potential pain generating structures involved in MTSS, based on the traction hypothesis. The traction hypothesis states that over-activity of the muscles on the posteromedial tibia cause excessive stress on the periosteum at the site of muscle attachment. As the syndrome progresses, this causes inflammation and pain at the middle to distal third of the bone. The experimental procedure was described in detail and easy to follow, allowing reproducibility if future studies are to be performed on this topic.

However, the study had many limitations. First, there was no inclusion or exclusion criteria, nor was there any demographic information about the subjects (Ghanaians?). This limits applicability to other populations. Second, as this was a cadaveric study, information muscle activity and lower extremity kinematics can only be inferred from other research. Last, research has shown MTSS to have a higher prevalence in females (4), but the current study examined 2 females and 9 males. This creates a gender bias, especially considering the prevalence of MTSS in women. Future studies on this topic should provide better descriptions of the cadavers with equal inclusion of men and women.

Why is this study important?

MTSS is one of the most common lower extremity injuries in runners and individuals participating in high impact sports. Understanding its etiology is important in order to identify appropriate interventions for rehabilitation and minimizing risk factors leading to MTSS. The current study supports the notion that the soleus and flexor digitorum longus are potential sources of pain, and the tibialis posterior is not. Another study investigating gender differences in muscle attachments of the posterior lower leg indicated that females had an increased prevalence of flexor digitorum longus and soleus attachments at the middle and distal medial thirds of the tibia. This could help explain the increased prevalence of MTSS in women while lending additional support to the traction theory (4). The results suggest that hyper-pronation of the foot could place additional stress on the flexor digitorum longus and soleus, and consequently the periosteum of the middle to distal posterior medial third of the tibia, resulting in pain. Further, studies have shown increased activation patterns of the soleus muscle during the gait cycle in individuals with hyper-pronation (5). Further studies are needed to elucidate the full etiology of MTSS, but based on the current evidence, it appears that excessive pronation of the foot is an important factor to address when treating MTSS or training to prevent its occurrence.

How does it affect practice?

Human movement professionals should be familiar with medial tibial stress syndrome (MTSS) and its associated risk factors. The current study provides anatomical support for the role of the flexor digitorum longus and soleus in the generation of additional traction forces on the periosteum at the posteromedial tibia. While this study was cadaveric, and could not examine these muscles with electromyography, the increased activity of these muscle in those exhibiting signs of MTSS is supported by other studies (5). Further, the current study does not implicate the tibialis posterior as a pain generating structures. As it is common practice to release and lengthen over-active, pain generating structures, this may imply that the tibialis posterior should not be included during administration of these techniques. This study may also offer some support that inhibition of the tibialis posterior results in synergistic dominance of the other invertors (namely, soleus , flexor digitorum longus , and flexor hallucis longus ), resulting in over-activity, traction of the periosteum, and MTSS associated pain.

Soft tissue release and stretching of the muscles that have become over-active (such as soleus and flexor digitorum longus ), lengthening of muscle that have become short, and activation of under-active muscles (tibialis posterior ?) is recommended. Further, optimization of function in both walking and running, along with a pragmatic, gradual increase (no more than 10% per week in volume) in activity is recommended for both rehabilitation and reduction in the risk of MTSS.

How does it relate to Brookbush Institute Content?

The Brookbush Institute's predictive model of Lower Leg Dysfunction (LLD) lists the tibialis posterior as long/under-active, with compensatory over-activity of flexor digitorum longus and flexor hallucis longus , as well as over-activity of the soleus and gastrocnemius . The synergistic dominance of the flexor digitorum longus and flexor hallucis longus may be due to the inability of an inhibited tibialis posterior to eccentrically decelerate pronation during gate. The suggested activity of these muscles in the LLD model would appear to be supported by this study, assuming that traction on the periosteum is a source of pain in those with MTSS.

It is a tenant of the Brookbush Institute to provide a complete intervention addressing all myofascial, joint, and neurological dysfunctions contributing to aberrant movement patterns. In situations where tibialis posterior is inhibited, release of overactive synergists (flexor digitorum longus, flexor hallucis longus ), release and lengthening of short and over-active antagonists (soleus , gastrocnemius , and fibularis muscles ), and mobilization of affected joints (ankle mobilization ) would be advised prior to activation and integration of tibialis posterior . Further, manual therapists may consider fascial techniques for the posterior crural fascia and first ray and cuboid mobilization to assist in optimal motion. The following videos are sample techniques used by the Brookbush Institute for release, mobilization and activation techniques for the structures mentioned in this article.

Brookbush Institute videos

Gastrocnemius/Soleus (and potentially Flexor Digitorum Longus & Flexor Hallucis Longus) Self-administered Release Technique:

Self-administered Ankle Mobilization (Anterior to Posterior Talus Mobilization with Dorsiflexion):

Flexor Hallucis Longus and Flexor Digitorum Longus Static Manual Release

Posterior Tibialis Activation Progression 4

References:

1. Bennett KE, Reinking MF, Pleumer B, et al. (2001). Factors contributing to the development of medial tibial stress syndrome in high school runners. JOSPT. 31(9): 504-510.

2. Hubbard TJ, Carpenter EM, Cardova ML. (2009). Contributing factors to medial tibial stress syndrome: a prospective investigation. Med Sci Sports Exerc. 41(3): 490-496.

3. Newman P, Witchalls J, Waddington, et al. (2013). Risk factors associated with medial tibial stress syndrome in runners: a systematic review and meta-analysis. Open Access J Sports Med. 4: 229-241.

4. Edama M, Onishi H, Kubo M, et al. (2015). Gender differences of muscle and crural fascia origins in relation to the occurrence of medial tibial stress syndrome. Scand J Med Sports Sci. doi: 10.1111/sms.12639.

5. Murley GS, Landorf KB, Menz HB, et al. (2009). Effect of foot posture, foot orthoses and footwear on lower limb muscle activity during walking and running: a systematic review. Gait and Posture. 29(2): 172-187.

Questions, comments, and criticisms are welcomed and encouraged -

Origin of Pain in Medial Tibial Stress Syndrome (MTSS): Cadaveric Study

Research Review: Muscles Involved at the Site of Medial Tibial Stress Syndrome

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