domingo, 20 de enero de 2013

Medial Tibial Stress Syndrome

Resumen del artículo de Kirby sobre el estrés tibial medial La fuente original completa puede verse en el siguiente enlace:
Originally Posted by Kevin A. Kirby, DPM: October 15, 2005: At 2005 Australian Conference of Science and Medicine in Sport, Melbourne

Medial Tibial Stress Syndrome: Biomechanical Etiology and Effective Foot Orthosis Treatment

Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine
Oakland, California, USA

Leg Pain in Athletes

 Pain that occurs in the lower legs during exercise has commonly been called “shin splints” within the medical community for the past 50 years
 As our knowledge has increased regarding the specific pathologies that cause exertional leg pain, it has been recommended to discard the term “shin splints”
 Shin splints is “a nonspecific term used to describe exertional pain from almost any cause”
Anderson MW, Ugalde V, Batt M, Gacayan J: Shin splints: MR appearance in a preliminary study. Radiology 204:177-180, 1997.

Differential Diagnosis of “Shin Splints”

 Tibial or fibular stress fractures
 Chronic exertional compartment syndrome
 Arterial or nerve entrapment
 Deep vein thrombosis
 Fascial herniations
 Muscle strains or tears
 Medial tibial stress syndrome

Medial Tibial Stress Syndrome

 In 1974, the term “tibial stress syndrome” was first reported in the literature by Clement and the term “medial tibial syndrome” was first reported in the literature by Puranen
Clement DB: Tibial stress syndrome in athletes. J Sports Med, 2:81-85, 1974.
Puranen J: The medial tibial syndrome. JBJS, 56B:712-715, 1974.
 “Medial tibial stress syndrome” was first coined as a term by David Drez, MD and first used within the medical literature by Mubarak et al in their 1982 study of 12 patients with leg pain
Mubarak SJ, Gould RN, Lee YF, Schmidt DA, Hargens AR: The medial tibial stress syndrome: A cause of shin splints. Am J Sp Med, 10:201-205, 1982.

Incidence of MTSS

 Running sports and jumping sports are, by far, the most common causes of MTSS
 In aerobic dancers, 22% of all injuries were due to MTSS
Taunton JE, McKenzie DC, Clement DB: The role of biomechanics in the epidemiology of injuries. Sports Med, 6:107-120, 1988.
 In runners, MTSS accounted for between 13.2% to 17.3% of all injuries
Clement D, Taunton J, Smart G, McNicol KL: A survey of overuse running injuries. Phys Sportsmed, 9:47-58, 1981.
Epperly T, Fields K: Epidemiology of running injuries. In O’Connor F, Wilder R (eds), Textbook of Running Medicine. New York, McGraw-Hill, 2001, pp. 1-11.

 Prospective study by Yates and White on 124 Australian military recruits from HMAS Cerberus, Australia’s largest naval training facility, showed that, during basic training, 40 of these recruits (35%) developed MTSS
Yates B, White S: The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. Am J Sp Med, 32:772-780, 2004.
 Prospective study of 125 high school distance runners showed a 13% incidence of MTSS
Bennett JE, Reinking MF, Pluemer B, et al: Factors contributing to the development of medial tibial stress syndrome in high school runners. J Ortho Sports Phys Ther, 31:504-511, 2001.

Predominantly in Females?

 In a study of 125 high school XC runners, 15 runners developed MTSS, 13 female and only 2 male (6.5 female/male ratio)
Bennett JE, Reinking MF, Pluemer B, et al: Factors contributing to the development of medial tibial stress syndrome in high school runners. J Ortho Sports Phys Ther, 31:504-511, 2001.
 Incidence of tibial stress reaction was .75/1000 in males vs 8.0/1000 in females during basic training (over ten times more likely in female than male recruits)
Reinker KA, Ozburne S: A comparison of male and female orthopaedic pathology in basic training. Military Medicine, 144:532-536,1979.

Clinical Diagnosis of MTSS

 Presents as diffuse tenderness along distal two-thirds of posterior aspect of medial border of the tibia
 Rarely is any single traumatic event reported by patient
 Pain generally worsens with increased duration or intensity of running or jumping activities
 Pain generally ends after exercise ceases

Imaging Studies in MTSS

 Plain film radiographs are almost always normal but may be positive in tibial stress fracture
 Triple phase radionuclide imaging is very sensitive in detecting MTSS (delayed images only) and is thought to become positive due to early bone remodeling in tibia
Roub LW, Gumerman LW, Hanley EN: Bone stress: A radionuclide imaging perspective. Radiology, 132:431-438, 1979.
 Bone scan, however, is not always positive in patients with early stages of MTSS
Milgrom C, Chisin R, Giladi M, et al: Negative bone scans in impending tibial stress fractures. A report of three cases. Am J Sp Med, 12:488-491, 1984.

 MRI is increasingly being used to diagnose MTSS and tibial stress fractures in athletes due to its ability to detect edema within soft tissue and bone

 In 1995, Fredericson et al proposed an MRI grading system for MTSS and tibial stress fractures:
– Grade 1: mild to moderate periosteal edema on T2 images only
– Grade 2: more severe periosteal edema with bone marrow edema on T2 only
– Grade 3: moderate to severe edema of both periosteum and marrow on both T1 and T2 images
– Grade 4: low signal fracture line with severe marrow edema on both T1 and T2 images
Frederickson M, Bergman AG, Hoffman KL, Dillingham MS: Tibial stress reaction in runners. Correlation of clinical symptoms and scintigraphy with a new magnetic resonance imaging grading system, Am J Sports Med, 23:472-481, 1995.

Dynamics of Bone and Stress

 Bone is a dynamic tissue that will strengthen and remodel in response to stress
 Normal repair and remodeling of bone must be balanced or a temporary disturbance in equilibrium between bone reabsorption and bone regeneration may occur
 Excessive stress causes an increase in osteoclastic over osteoblastic activity that weakens bone and may lead to stress fracture
Johnson LC, Strdford HT, Geits RW, et al: Histo-genesis of stress fractures. JBJS, 45A:1542, 1963.

Stress Phenomenon of Bone

 MTSS and medial tibial stress fracture are best classified as points along a continuum of stress phenomenon of bone or stress reaction of bone
Arendt EA, Griffiths HJ: The use of MR imaging in the assessment and clinical management of stress reactions of bone in high-performance athletes. Clin Sp Med, 16:291-306, 1997.
 Idea of continuum of bone stress injury, which is now evident in MR studies, is in agreement with the continuum of histological changes in bone that was first noted by Johnson et al in 1963 with their histological studies of stress fractures
Johnson LC, Stradford HT, Gets RW, et al: Histogenesis of stress fractures. JBJS 45A:1542, 1963.

Is MTSS Caused by Periostitis?

 Is inflammation of tibial periosteum the cause of the pain in MTSS as many early authors thought?
 Bhatt et al showed that periosteum had fibrous thickening with increased vascularity and bone of medial tibial border had a loss of osteocytes
Bhatt R, Lauder I, Finlay DB, et al. Correlation of bone scintigraphy and histological findings in medial tibial syndrome. Br J Sp Med, 34:49-53, 2000.
 However, Johnell et al found evidence of periostitis in only 1 of 33 soft tissue biopsies in patients with MTSS
 Detmer showed no evidence of periostitis in 10 patients that had fasciotomy for MTSSJohnell O, Rausing A, Wendeberg B, Westlin N: Morphological bone changes in shin splints. Clin Ortho Rel Res, 167:180-184, 1982.
Detmer DE: Chronic shin splints: Classification and management of medial tibial stress syndrome. Am J Sp Med, 3:436-446, 1986.

Nature of Bone Weakness in MTSS

 Magnusson et al found 15% decrease in bone mineral density in medial tibia in 18 male athletes compared to 16 controls and found 23% decrease when compared to 18 athletes without MTSS
Magnusson HI, Westlin NE, Nyqvist F, et al: Am J Sp Med, 26:712-125, 2001.
 Magnusson et al also found that there was a 19% increase in bone mineral density in the medial tibial border in athletes that had recovered from MTSS when compared to when they were symptomatic
 Therefore, these researchers speculated that the losses in bone mineral density seen with MTSS are reversible and not inherited
Magnusson HI, Ahlborg HG, Karlsson, et al: Am J Sp Med, 31:596-600, 2003.

Bone Biopsy Study in MTSS

 Johnell et al took 37 tissue specimens from patients with MTSS and these results were compared to bone and soft tissue biopsies from 10 control patients
 In bone biopsies, there were signs of increased metabolic activity in 22/35 samples, not present in controls
 In soft tissue biopsies, there were inflammatory changes in the crural fascia in 13/33 samples and only 1/33 had inflammatory changes in periosteum
 From their results, they felt that the medial tibial pain may be a “stress microfracture” of the tibia
Johnell O, Rausing A, Wendeberg B, Westlin N: Morphological bone changes in shin splints. Clin Ortho Rel Res, 167:180-184, 1982.
 Microcracks are present even in normal bone
 However, microcracks, under continued loading, will multiply and grow into “macrocracks” resulting in stress fracture or a complete fracture

Etiology of MTSS

 Multiple etiologies for MTSS have been proposed within the medical literature over the past thirty years
 Caused by tensile force from muscle on tibia?
– Posterior tibial
– Flexor digitorum longus
– Soleus
 Caused by combined fascial tensile force from one or more of above muscles on medial tibia?
 Caused by frontal plane bending of tibia?

Possible Causes of MTSS:Posterior Tibial Muscle

 Posterior tibial muscle was thought to be the cause MTSS by many authors since this muscle is known to be active in decelerating pronation
 However, other than the study of Saxena et al in 1990, anatomical studies have not shown that the posterior tibial muscle originates from the area of the tibia where the symptoms of MTSS are most commonly located
Saxena A, O’Brien T, Bunce D: Anatomic dissection of the tibialis posterior muscle and its correlation to medial tibial stress syndrome. J Foot Surg, 29:105-108, 1990.

Possible Causes of MTSS: Flexor Digitorum Longus Muscle

 FDL has been proposed as primary muscle causing MTSS due to its origin from medial tibia
Garth WP, Miller STJ: Evaluation of claw toe deformity, weakness of foot intrinsics, and posteromedial shin pain. Am J Sp Med, 17:821-827, 1989.

Possible Causes of MTSS: Soleus

 Detmer proposed in 1980 that MTSS was caused by traction stress on periosteum applied by medially arising fibers of the soleus muscle
Detmer DE: Chronic shin splints: Classification and management of medial tibial stress syndrome. Am J Sp Med, 3:436-446, 1986.
 The term soleus syndrome was proposed by Michael and Holder in 1985 since their study of 28 cadaver legs showed that the soleus extends distally, via its investing fascia, to insert along the medial tibia where the symptoms and scintigraphic findings of MTSS most commonly occur
Michael RH, Holder LE: The soleus syndrome. A cause of medial tibial stress (shin splints). Am J Sp Med, 13:87-94, 1985.

Possible Causes of MTSS: Fascia of Leg 

 In unpublished study by Bouche and Johnson, tendons of PT, FDL and soleus were attached to pneumatic actuators to simulate muscle pull during stance while strain gauges were placed along medial tibial fascia
 There was an increase in visible bowstringing and measured strain in the medial tibial fascia with tensile loads applied to all three muscles
 Because of tibial fascial involvement in medial tibial pain, Bouche called the condition “tibial fasciitis”

Possible Causes of MTSS: Bending of Tibia

 Milgrom et al, in their prospective study of tibial stress fractures in 295 Israeli infantry recruits, found that the recruits with tibias that had the smallest area moment of inertia were also the recruits more likely to experience tibial stress fractures during basic training
Milgrom C, Giladi M, Simkin A, et al: The area moment of inertia of the tibia: A risk factor for stress fractures. J. Biomech, 21:1243-1248, 1989.
 Beck et al found that Marine Corps recruits with tibial stress fracture had significantly smaller tibial cross-sectional areas and widths
Beck TJ, Ruff CB, Mourtnda FA, et al: Dual-energy x-ray absorptiometry derived structural geometry for stress fracture prediction in male US Marine Corp recruits. J Bone Miner Res, 11:645-653, 1996.

Bone Bending as Cause of MTSS

 Long bones with narrow diaphyseal widths will bend more under load than those with wider diaphyses
Martin RB, Burr DB, Sharkey NA: Skeletal Tissue Mechanics, Springer, New York, 1998.
 Adaptation in long bones that are subjected to bending strains is to increase cortical thickness, density and width that will cause bone to better resist bending loads
Beck BR: Tibial stress injuries: An aetiological review for purposes of guiding management. Sports Med, 26:265-279, 1998.

Why Do Runners Get MTSS:
Running Limb Varus?

Running Limb Varus:
A Common Cause of MTSS?

Bending Moment on Tibia Caused by Eccentric Tibial Loading Forces

Structural/Functional Factors Cited in Literature as Causes of MTSS

 Tibial varus
 Rearfoot varus
 Forefoot varus
 Pes planus
 Increased tibial torsion
 Increased femoral external rotation
 Limb length discrepancy
 Excessive foot pronation
 Tight calf muscles

Effect of Foot Mechanics on MTSS

 Combination of either forefoot varus or rearfoot varus alignment correlated with frequency of MTSS in 25 dancers
Sommer HM, Vallentyne: Effect of foot posture on the incidence of medial tibial stress syndrome. Med Sci Sp Exerc, 27:800-804, 1995.
 13 male distance runners without MTSS were compared to 35 male athletes with shin splints (MTSS) and found that those with shin pain had greater Achilles tendon angles, more STJ ROM, and more rearfoot pronation during running
Viitasalo JT, Kvist M: Some biomechanical aspects of the foot and ankle in athletes with and without shin splints. Am J Sp Med, 11:125-130, 2005.
 Unilateral standing navicular drop was found to be significantly greater in 125 high school XC runners that developed MTSS
Bennett JE, Reinking MF, Pluemer B, et al: Factors contributing to the development of medial tibial stress syndrome in high school runners. J Ortho Sports Phys Ther, 31:504-511, 2001.
 Prospective study of 124 recruits showed that individuals with pronated foot type (using foot posture index) were significantly more likely to develop MTSS than those with normal or supinated feet
Yates B, White S: The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. Am J Sp Med, 32:772-780, 2004.

 Many treatments have been proposed for MTSS ranging from conservative to surgical measures
– Ice
– Rest or modified rest
– Foot and/or leg taping
– Antipronation shoes
– Foot orthoses
– Strengthening, stretching
– PT modalities
– Casting and pneumatic leg braces
– Electrical bone stimulator
– Tibial fasciotomy

Guide for Treatment of MTSS
 Reduce the inflammation in the medial tibia with ice, NSAIDS and/or modalities
 Reduce or eliminate pathological forces on medial tibia that are causing the symptoms of MTSS with foot orthoses and/or shoes
 Advise patient on strengthening, stretching and return to activities protocol
 Design long-term treatment program for patient so that symptoms will be less likely to return once they resume training

Reducing Pathological Forces on Medial Tibia with Foot Orthoses

 Foot orthoses have the potential to allow the patient to train harder, longer and at more speed with less risk of developing MTSS or tibial stress fracture
 Foot orthoses must also be combined with appropriate shoegear and other treatments to allow for optimum orthosis function
 Foot orthoses designed for treatment of MTSS must be highly specialized in order to achieve maximal therapeutic benefit

Mechanical Effect of Foot Orthoses in Treatment of MTSS

 Basic mechanical goal of foot orthoses is to transfer center of pressure (CoP) that acts on plantar foot to a more medial location
 Medial positioning of CoP will cause STJ supination moment in early stance phase that will lessen early STJ pronation moments that may cause traction on medial tibial muscles/fascia
 Medial positioning of CoP will also decrease the valgus (frontal plane) bending moment on the tibia since the CoP will become more aligned relative to long axis of tibia
 Placing orthosis under foot of patient with MTSS will decrease tibial bending moment by shifting CoP medially

Causes of Increased Valgus Bending Moment of Tibia

 Any structural or positional abnormality that moves the CoP more lateral on plantar foot relative to long axis of the tibia will tend to increase the eccentric loading of tibia and increase the valgus tibial bending moment
 Increased varus alignment of tibia, rearfoot or forefoot at footstrike will cause more lateral positioning of CoP on the foot
 Increased foot abduction relative to the tibia displaces the CoP laterally relative to the long axis of tibia, increases eccentric loading of tibia and will increase tibial bending moment

Design of Foot Orthoses for MTSS

 Foot orthosis needs to have increased varus at both rearfoot and forefoot in order to cause decreased STJ pronation moments and decreased valgus tibial bending moments
– Medial heel skive
– Inverted balancing position of cast
– Relatively stiff plate material
– Rearfoot post
– Varus forefoot extension
 Varus forefoot extension and medial heel skive are most helpful orthosis modifications since they both are very effective at shifting the CoP more medial on the foot

Female Runner Patient with MTSS

 28 y/o female distance runner with medial tibial pain, tight calf muscles, pronated feet and varus forefoot

Foot Orthoses for MTSS 

Treatment Protocol for MTSS

– TID gastroc/soleus stretching
– 20 min BID icing to tibia
– Antipronation running shoes
– Reduce training mileage and intensity and/or start alternative exercise program
– Initially, OTC full length orthosis with added rearfoot, arch and forefoot varus wedging and heel lifts
– Later, custom foot orthoses depending on response to initial care
– Bone scan and/or MRI if pain is present at rest or during walking and/or induration/warmth is detected on medial tibial border


 MTSS is likely an early point along a medial tibial stress injury continuum that may, or may not, progress on to medial tibial stress fracture
 Likely etiologies of MTSS include increased tensile forces from medial tibial muscles/fascia and increased valgus bending moment on tibia during running and jumping activities
 Females much more likely to develop MTSS than males
 Decreased tibial diameter, increased varus alignment of forefoot, rearfoot and tibia along with excessive foot pronation may increase tendency to develop MTSS
 Orthoses with increased rearfoot and forefoot varus correction greatly help relieve symptoms of MTSS

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