Leg length Inequality and the pathogenesis or the origin and development of the condition, is and will always be, a controversial subject. There is a wide variance of opinion on the significance of structural leg length and the various methods for measurement.

Measuring of structural leg length when treating with orthotic therapy is necessary as undiagnosed structural leg length compensation will be affected when orthotics are prescribed for the patient. The natural body compensations for leg length difference can range from long leg flexion, to short leg supination amongst others as the body seeks to rebalance pelvic alignment. The most common compensation is long leg excessive pronation, accounting for around 80% of the long leg compensations. However in very large structural differences, short leg toe walking and short leg excessive pelvic drop may be taken up as compensations with inevitable upper spine outcomes such as functional scoliosis.

Managing a treatment protocol to assist in minimising issues can be difficult especially if the spine is fixed, that is, the spine (or spinal segment) is not mobile or correctable by conservative means. This is often referred to as a Fixed Sagittal Imbalance (FSI) and conservative treatment looks to make the patient as comfortable as possible when surgical intervention is not undertaken.

In this newsletter we will focus on conservative treatment methods that can be adopted when the osseous structure is mobile.

Assessment for structural leg length difference as part of the initial assessment will avoid removal of undiagnosed compensations and provide an understanding of the size and extent of the leg length difference .

There are many ways to measure leg length, tape measure, x-ray, physical assessment of the limbs such as Palpation for Supine Medial Malleoli Asymmetry Technique 1

ICB provides both 10mm and 15mm extended heel lifts which can be used when the patient has custom made orthopaedic shoes or is wearing boots or the shoe has extra depth in the heel cup as they can be accommodated inside the shoe wear.

The extended heel lift is designed with a longer profile to support the mid foot and eliminate any mid foot collapse which can occur in Heel lift Larger than 8mm high. ICB regular heel lifts are available in S/M/L heel 4/6/8mm and the extended model is available in 10 &15mm.

Generally leather dress shoes can cope with a heel lift up to 6- 8mm (depending upon heel cup height) when added to the orthotic, higher than that the patient may complain that their heel is slipping out of the shoe.

Therefore, alternate shoe styles or modifications need to be considered to accommodate for large structural differences. When recommending shoes with orthotics a deep heel cup is an advantage.

Cross trainers and boots are able to accommodate a larger amount of heel lift in the heel cup, however this may limit the patient to a smaller selection of fashion shoe styles. A solution may be to add maximum amount to the orthotic and then modify the patient’s shoe to achieve the best result. (see below)

To incorporate an intrinsic lift, the sole of the shoe should not contain gel, air cushion pockets and have a base that is flat with no arch cut out. A boot maker can cut the EVA sole with a band saw, finishing behind the breakpoint or 1st MTPJ when the heel lift is less than 30mm. This will enable a normal walking pattern and toe off to occur.

Once the intrinsic heel lift in the shoe sole is over 30mm the cut in the sole must extend to the sulcus behind the phalanges and if a greater amount, to the end of the foot in a thicker ‘ramp’ like adjustment.

The patient featured presented with a condition that could be treated with orthotics , an additional heel lift or raise was recommended to be placed into the heel of the shoe by a boot maker or shoe repairer.

A temporary Heel Lift was used to validate the treatment suggestion note the RIGHT shoe with temporary extrinsic addition which successfully corrected the functional

Extrinsic Heel Lift under shoe heel (above)

scoliosis, this is the amount that should be added into the shoe sole.

Refer :The Orthotic Solution book p45 

Note: It is recommended that both left and right feet are fitted with an orthotic, in addition to any heel lift requirements, to ensure the foundation of the body is balanced.

Generally most footwear will accommodate an orthotic with a 6-8mm heel lift addition (depending upon heel cup height). If a larger heel lift is required(10mm +), extra depth footwear or boots may be required – or alternatively, adjustments to the footwear to incorporate a partial lift into the sole of the footwear can assist.

Reference: 1. Gary Fryer 2005 : Factors affecting the intra-examiner and inter-examiner reliability of palpation for supine medial malleoli asymmetry .

Tibial torsion has been defined as torsion of tibia bone along its longitudinal axis1, which produces a change in alignment of the planes of motion of the proximal and distal articulations, it is a twist in the osseous structure.

This definition draws a distinction between both Tibial Torsion (twist in the bone) and Tibial rotation.

Tibial Rotation occurs when the tibia internally or externally rotates along its axis as a functional outcome of biomechanical forces such as supination and pronation.

Tibial rotation is the rotation of the entire tibial shaft (bone) which takes place in gait as the foot pronates and supinates. The Tibia can exhibit both torsion and rotation and this makes this subject both interesting and somewhat difficult.

Tibial torsion occurs where the tibia exhibits a twist in the actual bone and is apparent from birth.

The biomechanical condition can be treated prior to skeletal maturity using foot orthotic devices which work to un torsion the tibia (see Fig 1) .

Once skeletal maturity has occurred, the soft tissue structures are engaged within the body to correct and adjust by tightening and or elongating as the means of correction or repositioning of the foot structure. In both instances knowledge of tibial torsion and tibial rotation will be invaluable to practitioners, in the design and implementation of treatments for their patients.

The broad parameters for identifying Tibial torsion have been outlined by Dr Merton Root 2 and Ronald L. Valmassy DPM3 and others, in which it is stated that torsion of the tibia be undertaken by measurement of the position of the medial and lateral malleoli apexes, (see Fig 2) a technique known as the Malleoli Position. (M.P.) This method imagines a pin bisecting medial and lateral malleoli apexes whilst the knee joint is maintained in the neutral position.

Several tibial torsion measurement techniques have been used or recommended by researchers; radiological methods and arthropometric methods, such as gravity goniometers. The method of measurement generally used in clinical practice is either by eye or by use of a gravity goniometer to measure malleoli positioning. (see Fig 3)

By Eye assessment

Gravity Goniometer

Root and Valmassey reported that the average normal position of the normal malleolar position M.P. was 13° – 18° 2, or slight out toed position.

The malleolar position is determined by observing the bisection of apex of the medial and lateral malleolar whilst the knee joint remained in the neutral position and the patient in the supine position.

Due to the occurrence of displacement of the patella it should be noted that research groups stipulate the position of the knee joint not patella as neutral in the sagittal plane. The positioning of the knee joint was achieved by the using of the knee condyles and lifting in the sagittal plane, ensuring that no lateral or medial deviation is observed.

There are believed to be several causes of the Tibial Torsion condition such as :

a) Acquired: due to injury / trauma such as a broken tibia which is re-positioned and takes on a post-operative internal or external position.

b) Genetics: congenital which is inherited from the mother, father or their genetic lines.

c) Acquired or caused by the environment, especially the uterine environment such as positioning in the womb – the tibia can form in an internal or external torsion position.

When treating in the field of paediatrics it should be noted that Tibial Torsion can effect the gait pattern which, if left untreated may have considerable affect upon the child as it grows to maturity. The outcome may leave the child’s biomechanical structure compromised, leading to other pathologies as the body seeks to compensate for these changes.

Traditionally paediatric biomechanical foot problems were given a low priority, with the result that manageable cases were left untreated and secondary features related to structural pathologies developed. Michaud comments that – ‘Early recognition and management, of actual foot problems in the young would go a long way to the reduction of issues later in life’ 4.

‘Gait plate’ orthotic treatment is a simple and effective method of restoring the lower limb to the ‘normal Malleoli Positioning range of 13° to 18° for children over the age of 6 years.

The gait plate orthotic device is manufactured to provide an extension under the 5th phalange for in-toe or under the hallux for out-toe. In gait the gait plate extension is identified by the proprioception system in the body and the brain instructs the body to reposition the foot in an automated response pattern, gently working on removing the bone torsion in an attempt to reposition to the 13-18° position.

The method is gentle and persuasive and has measurable results , however it appears to be most effective during ‘growth spurts’ in children.

If left untreated the body will naturally attempt to correct by using soft tissues to cosmetically correct the in toed or out toed position. Abnormal foot positioning, i.e. that which is opposed to what is accepted as ‘ideal’ or normal, encourages the body to use soft tissue to en-gage compensatory mechanisms.

Some studies have actually concluded that tight rotators and adductors have a compensatory repositioning function, as in the case of out toe and in toe positioning, relating to tibial torsion. 5,6,7,8, Again it must be stated that this is not strictly the case in every situation, and as such a small number of patients may present with tibial torsion without exhibiting hip compensations. The reasons for a lack of compensatory muscle tightness are unknown. These compensatory mechanisms can move joints in the body outside the normal range of motion and in the pro-cess may lead to so called ‘idiopathic’ soft tissue tight-ness such as Tight Abductors & Adductors or alternatively joint soreness during the compensation process.

References:

1. MULLAJI Arun B, SHARMA Amit K,1 MARAWAR Satyajit V, and KOHLI AF. Tibial Torsion in Non-Arthritic Indian Adults: A Computer Tomography Study of 100 Limbs.

2. ROOT ML, ORIEN WP, WEED JH, HUGHES R, Biomechanical Ex-amination of the Foot The Orthotic Solution I 67 Vol 1. p34, 1971

3. VALMASSY R.L., (1996) Clinical Biomechanics of the Lower Ex-tremeties. p255

4. MICHAUD, T.C (1997): Foot Orthoses and Other Forms of Conserva-tive Foot Care. Sydney: Williams & Wilkins, p168.

5. STAHELI, LT. In-toeing and Out-toeing in Children. Journal Family Practice. May 1983;16(5):1005-11.

6. STAHELI LT, CORBETT M, WYSS C, KING H. Lower Extremity Rota-tional Problems in Children. Normal Values to Guide Management. American Journal Bone Joint Surgery Jan 1985;67(1):39-47.

7.DAVIDS JR, DAVIS RB. Tibial Torsion: Significance and Measure-ment. Gait Posture. Jul 2007;26(2):169-71.

A Dorsiflexed 1st Ray (Metatarsal) also known as metatarsus Primus describes a deformity in which the 1st Ray /Metatarsal lies in a dorsiflex position relative to the lesser metatarsals.

The first ray is made up from the first metatarsal and the medial cuneiform. The ray facilitates movement in all three planes however predominantly produces the frontal and sagittal plane movements of dorsiflexion coupled with inversion and plantarflexion with eversion. This is due to its axis being 45° to both of these planes.

The biomechanics of this condition and the compensatory mechanisms and the resultant limitations need to be considered to understand both the function issues and the possible treatment that will need to be proposed for this condition.

The first ray (metatarsal) normally sits parallel to the plane of the lesser rays with equal amounts of dorsiflexion and plantarflexion usually 5mm up and 5mm down to allow the required plantarflexion to enable 65° to 75 °of MPJ dorsiflexion during the propulsive phase.

A Dorsiflexed 1st Ray is an osseus deformity where the lesser metatarsals sits lower to the bisection of the 1st Metatarsal when the foot is in the STJN position.

The condition may be congenital or acquired and is often referred to as ‘metatarsus primus elevatus’ or simply the prime metatarsal is elevated in reference to the lesser.

It should not be confused with Forefoot Supinatus as once the foot is placed in STJN the shaft can, with a supinatus, be plantarflexed. However, we should understand that the dorsiflexed 1st can be both fixed and or mobile in nature.

Because the 1st metatarsal is dorsiflexed it encourages the foot to collapse medially inhibiting the phalange from propelling over the 1st MTPJ, jamming occurs and a reduction in the ROM of the joint may be experienced.

The result of this jamming will be a stiffening of the joint and often the patient will develop an adductory twist in gait to reduce the load on the 1stMTPJ, as this occurs callosity will develop on the medial aspect of the hallux.

The distal phalanx of the hallux can also be forced into dorsiflexion as a toe off compensation, causing a hole to wear on top of the shoe and thickening of the nail from the constant trauma on the dorsal toe.

Clinical assessment of Metatarsal Phalangea Elevatus ( MPE) involves the evaluation of the sagittal plane position of the joint. The patient is evaluated in a non-weight bearing supine position with the subtalar joint in its neutral position (use the ICB AAM method) for Neutral.

As previously stated Metatarsus primus elevatus can be described as being congenital or acquired and can be further classified as a rigid, semi rigid, mobile or hypermobile deformity. A normal range of motion usually indicates a congenital deformity whilst an acquired.

MPE is characterised by an abnormal range of motion. This may be due to tibialis anterior contracture or associated with a forefoot supinatus.

The main issue is that the elevated metatarsal encour-ages the foot to function similar to a forefoot varus and excessive pronation is a key element as the foot collapses medially to allow normal ground contact in the toe off phase. Treatment will be a Morton’s ramp extension.

The purpose of the treatment is to allow a more normal ‘toe off’ to occur in the gait cycle by filling the gap under the 1st MTPJ whilst supporting the proximal hallux and thereby allowing earlier loading to occur.

To create the Mortons ramp to lift the proximal hallux this can be achieved by using a ICB 4° Forefoot addition (acts like a Morton’s ramp Image 9) to support the hallux and allow it to propel over the 1st metatarsal joint during toe off stage of gait.

A Full Length orthotic can also be used to create a Morton’s extension, use the forefoot addition to provide the required lift. See image 10 add the addition and mould to the foot in Neutral. First mark out the Morton’s extension ramp shape , cut and use a hand grinder to smooth the distal edges.

Orthotic therapy is not an exact science, so be prepared to adjust the orthotic for the patient by adding or subtracting as needed.

General REFERENCES

1. Merriman, L.M. and Tollafield, D.R. (1995) Assessment of the Lower Limb. Churchill Livingstone, Singapore Figure 2: Evaluation of first ray position(Merriman and Tollafield, 1995)

2. Root M L, Orien W P, Weed J H., 1977 Normal and Abnormal Function of the Foot. Clinical Biomechanics Vol 2, Los Angeles

3.Merriman’s assessment of the Lower Limb 3rd Ed. Churchill Livingstone

Leg length inequality and the pathogenesis or the origin of the condition, is and will always be, a controversial subject. There is not enough space to conduct a debate on the treatment, origin and possible associated compensatory mechanisms that may arise when we examine the topic. Also a wide variance of opinion exists on the significance of structural leg length and the various methods for measurement.

Many texts define minor structural leg length discrepancy as, less than 2 cm of difference. Other studies have suggested that, 40-70% of the population have at least some degree of LLD1, larger differences also appear in .001% (1:1000)of the population. From ICB’s perspective in dealing with Lower Limb Biomechanics, a 2cm structural difference is, rather than being minor, quite a significant amount and should be treated mechanically.

Leg length discrepancy or anisomelia, meaning a difference in length between paired legs, can broadly be categorised into two types:

1. Structural leg length difference, a difference in the long bone measurement of the leg. Its root cause can be illness, hereditary or trauma-related. The etiological factors involved in the causative process can be numerous such as: Idiopathic developmental abnormalities, fracture, trauma to the epiphyseal endplate prior to skeletal maturity, degenerative disorders, Perthes disease, cancer or neoplastic changes and Infections to name a few.

2. Functional differences can be more difficult to identify and treat as the etiological factors can be difficult to diagnose, e.g: body compensation associated with trauma, shortening of soft tissues, joint contractures, ligamentous laxity, axial misalignments, foot biomechanics, such as, unilateral excessive pronation, pelvic rotation and pelvic flare to name a few.

Often structural short leg syndrome is a commonly un-recognised condition that often goes untreated. It can be argued that even small discrepancies of only 4mm, if uncorrected, may over time set off a chain reaction of symptomology throughout the body.

There are 3 types of short leg issues that have been attributed as causative factors: inherited biomechanics, postural habits and or trauma:

1. Structural Short Leg: when the measurement from the head of the femur to the lateral or medial Malleolus measures shorter on one side than the other.

2. Functional Short Leg: when the measurement from the 2 same reference points are equal on both sides, but there still appears to be a short leg – usually due to a twist in the pelvis.

3. Combination of Structural and Functional Short Leg.

Symptoms
Common symptoms may include:

• Neck and shoulder pain
• Back ache & Hip pain
• Foot pain, Ankle pain, Knee pain.

Muscular, Vascular and Neurological systems may also be affected. Osteoarthritis in the joints, and Scoliosis (including idiopathic’) are classic indicators of a leg length discrepancy and or twist in the pelvis.

Biomechanical Aetiology

Anecdotal observation indicates that 80% of compensations is excessive long leg pronation. If the pelvis does not level as a result of the excessive pronation, the pelvis may twist or drop to one side – causing either a scoliosis or prolapse of the vertebral discs. Unilateral tightness in the gluteal muscles may occur with posterior pelvic tilt and rotation, which in the case of a functional short leg has the effect of rotating the pelvis posteriorly-effectively causing increased rotation of the spine at L1 to L5. A tendency to repeatedly pull (overstretch) the same muscles even though it has been given sufficient time to heal may occur.

A unilateral bunion is often associated with a leg length discrepancy. As the body excessively pronates to provide long leg compensation (to level the pelvis), this predisposes the longer leg to the formation of a HAV or bunion 2. Thus when bilateral HAV is evident and there is unequal Bunion growth, it can be deduced that a longer leg may be evident.

Assessment

Although some Physicians still use measurement methods such as Knee height and tape measure. Current research indicates that newer manual techniques and radiographic analysis are preferred over the old tape measure method.

There are many ways to measure leg length, 2 of the most reliable methods are:

1. CT Scanogram: a radiographic technique that measures the actual length of the tibia and fibula bones. Point of failure in this method could be the inability of the radiologist to match the measurement reference points, however, this is not usually an issue.

2. Supine medial malleoli asymmetry (manual) (Fig : 4): A technique which is becoming more common and certainly more popular is a process that osteopath Gary Fryer at RMIT University Melbourne 20053 known as The Palpation for Supine Medial Malleoli Asymmetry Technique. This method is we believe, quick to perform and has demonstrated both a high intra-examiner and inter-examiner reliability. The trial concluded that Intra-examiner and inter-examiner reliability was almost perfect following subject selection for malleoli asymmetry, suggesting that clinicians can reliably detect medial malleoli asymmetries of greater than approximately 4 mm difference. The patient is placed in the supine position.

The Practitioner balances the hips and pelvis, then marking the inferior aspect of the medial malleolus with a pen. Align the malleoli and rub together to compare the pen line markings, checking for discrepancy between the two lines.

Treatment

In the case of a structural leg length discrepancy, a heel lift alone to the short leg may not provide the solution for the patient, as the long leg will continue to pronate and cause upper body imbalance and compensations. Correction to the longitudinal arch of both feet and their biomechanics by prescribing an orthotic device is essential.

The orthotic device will ensure the correction and realignment of the feet, and the addition of a heel lift on the shorter leg will prevent jamming in the hip of the longer leg, and prevent upper body compensations and resultant pain.

Generally 80-85% of compensatory action will be excessive long leg pronation, other compensations may occur such as : Long leg knee flexion, short leg supination, genu recurvatum or knee hyperextension as a means to adjust the pelvic alignment.

References
1. Woerman AL, Binder-MacLeod SA. Leg length discrepancy assessment: accuracy and precision in five clinical methods of evaluation. J. OrthopSports Phys Ther 1984;5:230-8.
2. Neale’s disorder of the foot 8th edition 2010 p103
3. Gary Fryer 2005 : Factors affecting the intra-examiner and inter-examiner reliability of palpation for supine medial malleoli asymmetry.