Introduction

Unilateral discrepancy is a shortening of bone which affects equal limb length. For an upper limb, a small difference in the length of the arm or forearm has no effect on function. However, for lower limbs, if there is a length difference of even 2-3 cm, this will induce a limp and in most cases, will tilt the pelvis to one side, causing a spine curvature or scoliosis. 1 in 1000 people have a unilateral discrepancy of over 6 cm, whilst several thousand present discrepancies between 2 to 6 cm.

Two types of shortening can occur:
Intercalary or isolated, which is where a singular bone is affected. This is usually caused by trauma.
Longitudinal, which involves more than one bone, is caused by a genetic defect or as a result of alterations in growth. Longitudinal bone shortening is primarily linked to patients with congenital shortening, which may result in the following:

• Short femur, or Proximal Femoral Focal Deficiency (PFFD)
• Fibular hemimelia
• Tibial hemimelia
• Foot deformity (such as clubfoot)

Common Discrepancy

14 Year-old patient who sustained a trauma resulting in a 5.5 cm discrepancy and a large varus deformity. After undergoing an initial plate fixation, a correction of her varus deformity with an intramedullary nail and an exchange of her trauma nail with a Guichet femoral nail a year later, the patient could resume all sports in less than 6 weeks.

14 Year-old patient who sustained a trauma resulting in a 5.5 cm discrepancy and a large varus deformity. After undergoing an initial plate fixation, a correction of her varus deformity with an intramedullary nail and an exchange of her trauma nail with a Guichet femoral nail a year later, the patient could resume all sports in less than 6 weeks.

Common discrepancy are discrepancies present in the standard population. Up to 1/1000 people present a discrepancy over 6 cm, but several thousants of people present discrepancies from 2 to 6 cm.

Origins may vary, some being congenital (gradually increasing from birth, even if limited to only 2 cm at adulthood), others being mild forms of PFFD, and further ones being after trauma (generally 1 to 4 cm in femurs).

Treatment is more successful with intramedullary nails. The Guichet nail allows patients a full return to sports from the first postoperative day, with the aim to resume sports completely from the 3rd to 4th month of recovery.

Congenital Short Femur – PFFD

Introduction

Patient with a congenital short femur. Note the modifications to the length, shape, and axis of the bones. On the right a 6 cm standard modified shoe is used for walking hiding the large deformity. A lengthening has been performed.

Patient with a congenital short femur. Note the modifications to the length, shape, and axis of the bones. On the right a 6 cm standard modified shoe is used for walking hiding the large deformity. A lengthening has been performed.

Congenital short femur is a longitudinal deficiency of the lower limb. Symptoms may be more visibly obvious to one section of a limb, such as the femur or tibia, but other limb functions can also be affected. The deficiency is usually located at thigh level, with severe cases of discrepancy ranging from 5cm to 35cm difference.

Picture above : Patient with a congenital short femur. On the right, a 6 cm standard modified shoe is used for walking hiding the large deformity.

Bone length differences are generally associated with:
• Abnormal acetabulum (pelvic socket)
• Shortened varus of the femur
• Lower femoral valgus
• Hypoplasia of thigh muscles and tendons
• Congenital deficiency of ligaments
• Fibular hemimelia (wherein the fibula is shorter than normal to the tibia)
• Rounded ankle joint with hypoplasia
• Missing section of the foot (for example, missing the arch and fifth toe)

Treatment Program

The aim of treatment is to attain functional joints and restore equal bone length by the end of a patient’s growth period. If the patient does not undergo numerous operations prior to treatment, the success rate is higher, as less procedures will reduce problems on the final results.
For treatment, joint stablisation would be addressed first, with lengthening procedures performed after.
However, in more severe cases, full reconstruction may be required. This can be a stress on patients, therefore it is important for all surgical decisions to be discussed between the surgeon and patient in an effort to prevent multiple operations.
Promising techniques have been developed to treat short stature, yet in some cases, amputation may be option. This depends on:

• Observed deformities (prediction of limb discrepancy)
• Complexity of surgical procedures
• Length of hospitalisation

Joint correction

Good alignment and joint stability are required before any lengthening operation, including corrections for axis malalignments and pseudarthrosis.
A common feature of PFFD is a lack of cruciate ligaments in the knee joints. In order to stabilise the knee for the use of lengthening nails, reconstruction of the ligaments is strongly advised.

Lengthening

When bones are lengthened with Albizzia, the complications are fewer than if external fixators are used.
The Albizzia nail can allow length gains up to 18 cm. Aftercare relies on the patient wearing orthoses or modified shoes up to the end of growth.

9 year-old patient with a 18 cm lower limb discrepancy (PFFD). The material (plate and screws) too fragile was broken, therefore a very strong nail has been set to correct the deformity.

9 year-old patient with a 18 cm lower limb discrepancy (PFFD). The material (plate and screws) too fragile was broken, therefore a very strong nail has been set to correct the deformity.

Patient who received a correction from a varus to a valgus of the hip of 90° and a 90° posterior tilt of the top part of the femur.

Patient who received a correction from a varus to a valgus of the hip of 90° and a 90° posterior tilt of the top part of the femur.

Patient with a reconstruction of the anterior cruciate ligament to allow stabilization of the knee before the lengthening procedure (for a 6-cm gain).

Patient with a reconstruction of the anterior cruciate ligament to allow stabilization of the knee before the lengthening procedure (for a 6-cm gain).

Patient with a 6-cm shortening wearing a specially constructed shoe, masking the 6-cm discrepancy.

Patient with a 6-cm shortening wearing a specially constructed shoe, masking the 6-cm discrepancy.

Patient with a 12-cm discrepancy. A special orthosis with an artificial foot below the normal one is advised.

Patient with a 12-cm discrepancy. A special orthosis with an artificial foot below the normal one is advised.

Patient with a congenital short femur, who had a 6-cm femoral lengthening with the Albizzia nail.

Patient with a congenital short femur, who had a 6-cm femoral lengthening with the Albizzia nail.

Fibular Hemimelia

The fibula is the long, small bone on the outside of the leg. In cases of fibular hemimelia, the fibula is hypotrophic or absent, which leads to the shortening of the leg and lateral deviation, placing the patient’s weight on the tibia. This defect of the fibula can lead to the decreasing stability or tilting of the ankle, creating a valgus deformity.

 

Shortened limbs can be associated with various lesions:

 

• Absence or hypoplasia of the fibula and associated muscles
• Deviation of the ankle into valgus
• Absent lateral arch of the foot
• Congenital deficiency of cruciate ligaments
• Congenital short femur

 

Abnormal foot with a fibular hemimelia. There is an absence of the fifth section of the foot and the fold at the ankle.

Abnormal foot with a fibular hemimelia. There is an absence of the fifth section of the foot and the fold at the ankle.

An untreated Fibular hemimelia at adulthood, caused by rubella (German measles) during mother's pregnancy.

An untreated Fibular hemimelia at adulthood, caused by rubella (German measles) during mother’s pregnancy.

A patient with a fibular hemimelia who had a leg lengthening. Note the absence of the fibula on the right (on the left photo) and the hypoplastic lateral malleolus. On the right photo, note the spontaneous posture of the knee in valgus, due to a ligament laxity in addition to the ankle valgus.

A patient with a fibular hemimelia who had a leg lengthening. Note the absence of the fibula on the right (on the left photo) and the hypoplastic lateral malleolus. On the right photo, note the spontaneous posture of the knee in valgus, due to a ligament laxity in addition to the ankle valgus.

A 9 year old patient with a 5 cm shortening. He presented with an absence of the fifth toe, a congenital absence of the anterior cruciate ligament, and a shortened femur. Treatment will include reconstruction of his knee ligament is planned under arthroscopy, and the lengthening will be performed at the end of growth, allowing full and accurate correction.

A 9 year old patient with a 5 cm shortening. He presented with an absence of the fifth toe, a congenital absence of the anterior cruciate ligament, and a shortened femur. Treatment will include reconstruction of his knee ligament is planned under arthroscopy, and the lengthening will be performed at the end of growth, allowing full and accurate correction.

Tibial Hemimelia

The condition Tibial hemimelia is a rare but severe congenital disorder. Treatment aims to restore a limb to function correctly, which would not only allow the patient to walk, but also participate in sports activities and drive a car.

 
However, treatment for Tibial hemimelia is difficult, as all cases need to be recognised early to prevent unnecessary surgical procedures and therapeutic errors.
 

An 8-year-old patient, who previously had 21 surgical procedures performed to treat her deformity. Surgery expects a 30 cm growth, yet a transfer of the fibula to the inside of the tibia is planned. For this, the tibia will be cut at its middle and lengthened, which forms a gap for the fibula to be transferred. Her foot will be corrected to fit an orthotic and she will be able to get a special prosthesis for sports, if desired. If successful, an additional lengthening at the end of growth is possible.

An 8-year-old patient, who previously had 21 surgical procedures performed to treat her deformity. Surgery expects a 30 cm growth, yet a transfer of the fibula to the inside of the tibia is planned. For this, the tibia will be cut at its middle and lengthened, which forms a gap for the fibula to be transferred. Her foot will be corrected to fit an orthotic and she will be able to get a special prosthesis for sports, if desired. If successful, an additional lengthening at the end of growth is possible.