What are Shin Splints?

Now that we are getting close to the Marathon here in Victoria, I am encountering an increasing number of people who are referred to me with "Shin Splints."  What exactly does this mean?  Shin splints is a general term to cover anything that causes shin pain.  Most people know that they have shin pain, but where does it come from and why do they get it?  

 

Here are some notes from an article I wrote that may help to understand the term Shin Splints and how it relates to Stress Fractures, as well as how serious an injury Stress Fractures can be.

COMMON CAUSES AND MANAGEMENT OF STRESS FRACTURES IN RUNNERS

STRESS FRACTURES

Stress fractures occur on a continuum with the actual term “Stress Fracture” being the worst possible outcome.

ß------------------------------------------------------------------------------------------------------à

normal bone    bone strain     stress reaction                 non-displaced stress fracture     displaced stress fracture

This occurs when bone fails to remodel adequately with the application of repetitive stress.  The reasons stress fractures occur are multi-factorial.

IT IS KNOWN THAT WE ARE EXPECTED TO REACH PEAK BONE MASS AROUND THE AGE OF 25.  After that, both men and women’s bone density begins to decline, with women losing bone density more rapidly than men. 

HOW BONE IS REMODLED

Wolff’s Law states that bony adaptation is a function of the number of loading cycles, cycle frequency, amount of strain, strain rate and strain duration per cycle (basically, what we do when we are training).  The image below shows that as bone is bent, tension is created along the bottom edge (convex side) and compression is occurs along the top edge (concave side).

Tension forces are the ones responsible for resultant microfractures while compression forces tend to create more bone building

ETIOLOGY OF STRESS FRACTURES

The etiology of stress fractures is multi-factorial.  They can be divided up into intrinsic and extrinsic factors.

Extrinsic Factors (Controllable Factors)

TRAINING REGIMEN – higher running mileage is associated with increased incidence of stress fractures.  Abrupt training changes in DURATION (distance or time), FREQUENCY (times/day or week) INTENSITY (speed or time) are also correlated with increased incidence of stress fractures

FOOTWEAR – shoes are designed to REDUCE GROUND IMPACT FORCES. There is no evidence that cost of shoe can be associated with decreased risk of stress fracture.

There is moderate evidence that orthotic devices may help decrease incidence of stress fractures, however, it should be noted that all orthotics are made with different material and with different specifications so caution should be taken when deciding to purchase orthotics.

TRAINING SURFACE – there is conflicting evidence regarding training surface.  Theoretically, it has been proposed that training on harder surfaces will increase incidence of stress fractures, but there has been evidence to dispute this theory. 

Intrinsic Factors (Uncontrollable Factors)

DEMOGRAPHIC FACTORS –It has been noted that WOMEN tend to have higher incidence of stress fractures.   This is probably due to the large number of women who run as well as gender associated risk factors such as lower overall bone mineral density (BMD) and menopause.  The role of age as a risk factor has not been well correlated. 

BIOMECHANICAL FACTORS – the amount of force that a bone can withstand is directly proportional to its cross sectional area.  Thus, thicker bones tend to be stronger bones.  It has been highly correlated that women with low BMD (especially in the femoral neck and lumbar spine) were at increased risk for stress fractures.  THE BEST WAY TO DETERMINE BMD IS DUAL ENERGY XRAY ABSORTIOMETRY SCAN (DEXA SCAN).  DENSITY CAN ALSO BE ESTIMATED BY REGULAR XRAY (RADIOGRAPHY).

ANATOMIC FACTORS – everyone has a different shaped foot.  The shape of the foot can help control how much ground contact force is absorbed.  A RIGID HIGH ARCH FOOT ABSORBS LESS STRESS AND TRANSMITS GREATER FORCE UP THE LEG.  A FLEXIBLE LOW ARCH FOOT ABSORBS MORE FORCE AND TRANSMITS LESS FORCE UP THE LEG. Thus, high arches are good for sprinters who hope to transmit more force over short periods.  This is bad for distance runners who want to absorb more force for longer periods of time.  LEG LENGTH DESCREPANCY has shown to have moderate to mild correlation to stress fractures. 

HORMONAL FACTORS – Females tend to be at higher risk for stress fractures.  This is likely due to lower BMD, low body weight, future menstrual disturbances and/or excessive training.  FITNESS PROFESSIONALS SHOULD BE AWARE OF FEMALE ATHLETE TRIAD CONSISTING OF EATING DISORDERS, AMENORRHEA (menstrual disturbance) AND OSTEOPOROSIS.  Menstrual abnormalities are not a normal product of training. 

DIAGNOSIS OF STRESS FRACTURES

Diagnosis of stress fractures is often difficult and requires a high degree of suspicion.  Most commonly, it is an abrupt change in training such as increasing distance or intensity.  Pain typically occurs at the end of the run, or after.  THE HALLMARK DURING PHYSICAL EXAMINATION IS POINT TENDERNESS ALONG THE SHINS AND/OR FOOT.  Other tests that are performed in order to reproduce pain may include tuning fork, percussion and single leg hop.

THE DIFFERENCE BETWEEN STRESS FRACTURE AND “SHIN SPLINT”

There are subtle difference between stress fractures and shin splints  (more appropriately called medial tibial stress syndrome or MTSS). 

-FOR STRESS FRACTURES, PAIN WILL INCREASE AS THE RUN GOES ON.  TYPICAL MTSS PAIN USUALLY DIMINISHES AFTER WARM UP.

-STRESS FRACTURES WILL BE MORE POINT TENDER WHEREAS MTSS WILL HAVE MORE DIFFUSE TENDERNESS.

-FURTHER DIAGNOSTIC IMAGING MUST BE DONE TO DISTINGUISH THE DIFFERENCE.  THIS MAY INCLUDE XRAY, MRI AND CT

CONSERVATIVE MANAGEMENT FOR STRESS FRACTURES

PHASE 1

Cessation of painful activity, ice, analgesics,

Maintain fitness with cross training

Modify risk factors such as change shoes, tape/brace, etc.

PHASE 2

Light weight exercises may be implemented including non impact loading such as walking, elliptical etc.

Increase weight bearing/loading exercises 5-10 min a day as long as no bone pain occurs

Recovery of strength that is lost during phase 1 must also be addressed

PHASE 3

Gradual reentry into sport specific activity starting every other day and progressing to normal activity.  This may take from 3-18 weeks depending on severity of injury. 

Gait analysis should also be done to determine if there are any risk factors that can be reduced

TAKE HOME POINTS

STRESS FRACTURES OCCUR ALONG A CONTINUUM WITH DIFFERENT SEVERITY

PEAK BONE DENSITY OCCURS AROUND AGE 25 AND DECREASES THEREAFTER.

STRESS INJURIES ARE RESULTANT ACCUMULATION OF MICRODAMAGE THAT MAY EVENTUALLY FAIL THROUGH CRACKING (STRESS FRACTURES)

THE ETIOLOGY OF STRESS FRACTURES ARE MULTIFACTORIAL AND USUALLY OCCUR DUE TO A COMBINATION OF MANY INTRINSIC AND EXTRINSIC FACTORS

WOMEN ARE AT HIGHER RISK FOR STRESS FRACTURES AS THEY TYPICALLY HAVE LOWER BMD AS WELL AS HORMONAL CHANGES THROUGH AGE AND THE POTENTIAL FOR THE FEMALE ATHLETE TRIAD

MUSCLE EXERTS A PROTECTIVE EFFECT AGAINST STRESS INJURIES BY ACTING AS THE MAJOR SHOCK ABSORBER

THE HALLMARK OF STRESS FRACTURES IS WORSENING OF PAIN DURING A RUN AS WELL AS POINT TENDERNESS ALONG THE TIBIA OR THE NAVICULAR (FOOT)

SUBTLE DIFFERENCES BETWEEN STRESS FRACTURES AND MTSS MUST BE DETERMINED AS MANAGEMENT FOR EACH CONDITION DIFFER

CONSERVATIVE MANAGEMENT FOR STRESS FRACTURES INCLUDE THE 3 PHASES MENTIONED PREVIOUSLY

Knee Injuries in Runners

KNEE INJURIES IN RUNNERS

INTRODUCTION

Knee injuries in runners are typically caused by biomechanical problems above or below the knee.  Most common knee injuries are have been broken down into the areas of pain:

ANTERIOR KNEE PAIN

Patellofemoral pain syndrome (PFPS), quadriceps tendonitis/opathy, patellar tendonitis/opathy, Hoffa’s fat pad syndrome, osteoarthritis/chondromalacia patella, bursitis.

MEDIAL KNEE PAIN

PFPS, medial collateral ligament sprain, medial meniscus tear, osteoarthritis

LATERAL KNEE PAIN

PFPS, Iliotibial band syndrome (ITBS), popliteus muscle strain, lateral collateral ligament sprain, lateral meniscus tear, osteoarthritis

POSTERIOR KNEE PAIN

Baker’s cyst, hamstring tendonitis/opathy, popliteus muscle strain

Though this is not an exhaustive list of knee problems from running, it provides an ideal of the different structures that can potentially be injured.  This article will review the two most prevalent knee injuries experienced by runners; PATELLOFEMORAL PAIN SYNDROME (PFPS) AND ILIOTIBIAL BAND SYNDROME (ITBS)

PATELLOFEMORAL PAIN SYNDROME (PFPS)

PFPS is one of the most common problems experienced by runner (keep in mind, SYNDROME is merely a collection of signs and symptoms). Pain generators for PFPS include infrapatellar fat pad (between tibia and patellar tendon), bursa, tendon and the patella itself (bone).  Females typically experience PFPS more often than males.  Biomechanical issues such as wider hips and increased internal rotation of the femurs causing poor tracking of the patella that irritates structures that hold the patella in place (patellar tendon, joint capsule etc). 

PRESENTATION

The classic onset of PFPS is:

-insidious onset of progressively worsening anterior knee pain, worse with increased running distance or time

-pain is typically described as diffuse and achy, worse in the morning, and may be sharp with activity

-aggravated with prolonged sitting with knees in flexion (such as on an airplane, or in a movie theater). 

-pain may be felt along or within the patellar tendon if there is tendinopathy

TREATMENT

Initial treatment for PFPS should include at symptom relief.  This should include reducing or stopping running or any other insulting activities.  If there is swelling, ice may help to reduce discomfort

During the rehabilitation phase, isometric exercise may be beneficial if the patient is still suffering from pain.  This might include simple contraction of quads while the knee is straight or slightly bent.  Therapy for tight structures such as muscles and tendons have been found to be beneficial. 

For later phases of rehabilitation, functional closed kinetic chain exercises have been found to be very effective in reducing incidence and reoccurrence of PFPS.  Exercises focusing on hip/gluteal strengthening should be included.  Squatting, lunges and single leg exercises focusing on maintaining knee and hip stability are encouraged.

ILIOTIBIAL BAND SYNDROME (ITBS)

ITBS and PFPS are considered separate diagnoses, though they have common signs and syptoms.  The ITB is a dense fascial band that runs down the lateral aspect of the thigh.  It has extensive connections to the gluteal muscles, tensor fascia latae (anteriolateral muscle of the hip) and to a number of structures around the lateral aspect of the knee. Originally, it was thought that friction over the lateral femoral condyle was the cause of irritation to the ITB (just above the lateral aspect of the knee).  Current research has shown that it may not be friction (the ITB does not actually slide) but compression of a fat pad or bursa in the area of pain (typically lateral aspect of the knee). 

PRESENTATION

The classic presentation of ITBS is:

-pain felt in the lateral hip, thigh and more commonly, the lateral aspect of the knee

-slow onset of achy/burning pain that gets worse with increased running time or distance

-pain is typically felt when knee is flexed at 20-30 degrees and worse running downhill

-paradoxically, pain typically (but not always) decreases with faster running

TREATMENT

Initial treatment for ITBS should aim at symptom relief.  Though there is little research on the efficacy of stretching the ITB, anecdotally there are many records of moderate relief of symptoms from stretching and foam rolling the ITB.  Caution must be exercised when rolling ITB, particularly over the lateral knee as structures may become more inflamed and irritated.  Just as PFPS, once pain is reduced, rehabilitation should focus on hip strengthening exercises.  These exercises should emphasize close kinetic chain exercises such as squats, lunges and single leg exercises.

COMMON QUESTIONS

WHAT IS THE DIFFERENCE BETWEEN PFPS AND CHONDROMALACIA PATELLA?

There is no difference between PFPS and chondromalacia patella though CMP can be considered a cause or sign of PFPS.  Chondromalacia patella was believed to be a major cause of anterior knee pain (feeling of pain under the knee cap).  CHONDROMALACIA PATELLA is a roughening of the cartilage on the underside of the knee cap.  HOWEVER, IT IS KNOWN THAT CARTILAGE IS NOT INNERVATED BY NERVES AND THUS IS NOT LIKELY A SOURCE OF PAIN.  Current theories of causes of pain include subchondral bone injury (like a bone bruise beneath the cartilage) or damage to nerve endings that innervate the joint itself (such as the joint capsule)

CAN THE VASTUS MEDIALIS OBLIQUUS (VMO OR MOST MEDIAL QUADRUCEP MUSCLE) BE PREFERENTIALLY RECRUITED?

Recent research has shown that preferentially recruiting VMO does not occur.  Thus, exercises aimed at activating the VMO should not be given.  Instead, the aim should be toward functional exercises involving the whole quadriceps muscle.  Exercises including closed chain squatting, lunges, and single leg exercises should be recommended.  Exercises that should be avoided include squeezing a ball between the knees while squatting, using bands that place lateral stress on the knee while squatting and hip adduction and leg extension exercises using machines. 

TAKE HOME POINTS

THERE ARE MANY SOURCES OF KNEE PAIN FROM RUNNING. THE TWO MOST COMMON CAUSES OF KNEE PAIN ARE PATELLOFEMORAL PAIN SYNDROME (PFPS) AND ILIOTIBIAL BAND SYNDROME (ITBS)

PFPS IS TYPICALLY ANTERIOR KNEE PAIN FROM THE BURSA, TENDON, FAT PAD OR BONE.  IT DIFFERS FROM ITBS AS ITBS IS A SOURCE OF LATERAL KNEE/THIGH PAIN. 

PRESENTATION OF PFPS INCLUDES WORSENING KNEE PAIN WITH INCREASED RUNNING, AND PAIN WHILE SITITNG WITH THE KNEES FLEXED

PRESENTATION OF ITBS INCLUDES WORSENING LATERAL KNEE/THIGH PAIN WHILE RUNNING UP HILL. 

BOTH PFPS AND ITBS SHOULD BE TREATED WITH REHABILITATION.  ONCE PAIN SUBSIDES, REHABILITATION SHOULD FOCUS ON CLOSED KINETIC CHAIN EXERCISES WHILE MAINTAINING HIP AND KNEE STABILITY

THE VASTUS MEDIALIS (OBLIQUUS) CANNOT BE PREFERENTIALLY RECRUITED. THUS, TRAINING SHOULD FOCUS ON QUADRICEPS AND HIP/GLUTE ACTIVATION

Squatting: Helpful or Harmful?

SQUATTING EXERCISES: ARE THEY HELPFUL OR HARMFUL?

INTRODUCTION

There are a variety of different squatting exercises that are given to patients and clients for various reasons.  Reasons may include performance enhancement, functional activities, and rehabilitation. Not all squats are equal.  The following is a brief review on different squats and what they do:

PARALLEL SQUATS: Top of thigh stops parallel to the floor, roughly around 90 degrees knee and hip flexion.

HALF SQUATS: Knee and hips flex to approximately 60 degrees.

FULL SQUATS:  Top of thigh goes below parallel to the ground, past 90 degrees of knee flexion.

OLYMPIC SQUATS: Maximum knee flexion, buttocks is on or close to ankles with feet flat on the floor.

HIGH BAR SQUATS: Bar high on traps, greater load on quads.

LOW BAR SQUATS: Bar low on traps, greater load on glutes and hamstrings.

FRONT SQUATS: Bar rests on anterior deltoid, greater load on quads (more than High bar squats).

ONE LEG SQUATS/SPLIT SQUAT/LUNGE: Squat performed unilaterally.

THE CONTROVERSY

There has been much debate over the use of squats and the potential harm they may impose on the knee joint.  This controversy first ensued with work published in a journal by Klein in 1961.  Klein hypothesized that deep squatting would stretch ligaments and increase instability of the knee. He found that there was increased laxity in the medial collateral (MCL) and lateral collateral ligaments (LCL).  Despite speculative study methods, these results were published in many lay (non scientific) journals and became an accepted standard that squats beyond parallel (or 90 degrees) would be harmful to the knees. 

There is an assumption that knee laxity may predict knee injury.  This further ‘snowballed” into more people removing squatting from their programs.  In fact, this notion became so widely accepted that the US Marine Corp recommended the removal of squatting from their training programs. 

BIOMECHANICS OF THE KNEE DURING SQUATTING

There are 3 movements that are required for flexion and extension of the knee.

SLIDING (OR GLIDING) – single point on one surface contacting multiple points on another (such as going down a slide at the park)

ROLLING – multiple points on one surface contact multiple points on another (such as a ball rolling down a hill)

SPINNING – single point on one surface rotates on a single point on another (as a top spinning on a table)

DURING MOVEMENT ABOUT THE KNEE, THERE ARE VARYING DEGREES OF ALL 3 AFORMENTIONED MOVEMENTS.  THE SUMMATION OF THOSE MOVEMENTS LEAD TO FORCE AT THE CONTACT POINTS OF THE KNEE.  THESE FORCES INCLUDE SHEAR (ANTERIOR AND POSTERIOR OR FORWARD AND BACKWARD FORCE) AND COMPRESSION (UP AND DOWN FORCE).

SHEAR AND COMPRESSION FORCES

-It has been found that SHEAR and COMPRESSION INCREASES with:

            -DEPTH OF SQUAT

            -INCREASED SPEED OF DECENT

            -FATIGUE

            -LOAD

-it was noted that experienced lifters were able to REDUCE shear and compression forces during lifts.   

ARTHRITIS AND CHONDROMALACIA PATELLA

It is a common thought that overuse of knee joints leads to arthritis and chondromalacia patella (knee cap pain)  However, the following has been found:

-THERE IS A LOW INCIDENCE OF KNEE OSTEOARTHIRITS IN THOSE WHO LOAD THE KNEE THROUGH FULL RANGE OF MOTION

-THERE WAS FOUND TO BE LESS SYMPTOMATIC KNEE OSTEOARTHRITIS ARTHRITIS IN RETIRED WEIGHT LIFTERS

-THERE WAS NO DIFFERENCE IN DEGENERATIVE CHANGES (ARTHRITIS) IN THE KNEES OF WEIGHTLIFTERS VS. CONTROLS (NON WEIGHTLIFTERS)

-NO CHONDROMALACIA PATELLA FOUND IN WEIGHTLIFTERS STUDIED.

THE GREATEST CONCERN WAS THE QUADRICEPS TENDON (LIGAMENT) WHICH HAS BEEN PRVEN TO BE SUCEPTABLE TO OVERUSE INJURIES

            -TOO MUCH LOAD, TOO FAST = PATELLAR TENDINITIS/OPATHY

TAKE HOME MESSAGE

-QUESTION EVERYTHING YOU READ AND ENSURE THEY ARE RELIABLE SOURCES   ALWAYS ASK FOR EVIDENCE AND READ RESEARCH METHODS TO SEE IF THEY ARE VALID AND RELIABLE SOURCES.  REMEMBER, THAT MANY TEXTBOOKS ARE MANY YEARS BEHIND IN PUBLISHING ‘UP TO DATE’ MATERIAL.

-SQUATS ARE A LOW RISK EXERCISES AND DO NOT LEAD TO INSTABILITY AND DEGENERATIVE CHANGES IN THE KNEE. 

-SQUATS CAN BE SAFELY USED TO PREVENT INJURY, IMPROVE ATHLETIC PERFORMANCE, AND CAN SAFELY BE USED AS A REHABILITATION TOOL IF INSTRUCTED PROPERLY.

-BE SURE NOT TO LOAD A SQUAT TOO FAST AS IT CAN LEAD TO PATELLAR TENDON PROBLEMS.