A study published in the Annals of the Rheumatic Diseases has suggested that people with varus knee alignment have an increased risk for the development of osteoarthritis of the knee.

The aim of this study was to test whether alignment influences the risk for the development of new OA and to determine whether varus and valgus alignment cause the condition to progress in existing osteoarthritis.

Varus and valgus alignment increase, respectively, medial and lateral tibiofemoral load, the authors observed.

The study included 2713 volunteers aged 50 to 79 years. All had arthritis or were at increased risk for the development of the condition because they were overweight, had knee surgery, or had a previous knee injury.

The study carried full-limb x-rays from the hip to the knee to the ankle and knee x-rays at the beginning entry and at 30 months.

Varus  alignment was defined as a 178° angle or less from the hip to the knee to the ankle; valgus alignment was defined as an 182° angle or more from the hip to the knee to the ankle.

The study authors found that varus alignment was associated with 1.49 times the risk for the development of OA (95% confidence interval, 1.06 – 2.10). There was no increased risk for valgus alignment.

The study found that varus alignment was associated with a greater risk for medial osteoarthritis progression. Valgus alignment was associated with a greater risk for lateral progression but a reduced risk for medial progression.

The source of malalignment  may be genetic, developmental, or traumatic, but both varus and valgus alignments increase the risk for subsequent OA progression irrespective of the cause.

The study was supported by the National Institutes of Health. The study authors have disclosed no relevant financial relationships.

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Orthoses or a kind of splints applied to different parts of body to limit movements which can aggravate the existing pain.

Commonly used orthoses are cervical collars and lumbar supports. Following factors should be taken into account before the orthoses are prescribed.

• Examination  suggests that supports or reduced mobility benefits the patient.
• Patient must understand that it is a temporary measure.
• If the supports aggravates the problem, it should be removed.

Cervical collars

Cervical soft collars are useful for painful neck or nerve root pain of the arm, as they can reduce the jarring which aggravates the pain. They might be worn at night as well as during day if necessary.

The collar should not be required for longer than 1-2 weeks at a time. Once recovery starts, its usage should come down.

Lumbar Supports

They are useful for keeping lumbar spine steady and in a correct lordosis during an episode of acute pain.  Lumbar supports vary from the thoracolumbar to lumbosacral junctions orthoses. They provide support for  lifting and help to prevent further insult to lumbar spine.

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Hyperextgension casting is a non operative method to treat thoracolumbar spine injuries where a cast is applied in position of hyperextension.

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29 years lady was sitting in auto rickshaw which was struck by a car from behind. THe woman was thrown out of the auto rickshaw and the auto rickshaw fell on the lady.

She was brought to casualty of our hospital and found have injured her pelvis and spine along with paraplegia.

The xray in picture is lateral view of the spine and shows fracture of L3 vertebra.

MRI of the spine revealed a retropulsed fragment as well. She was operated upon and the spine was stabilized using pedicle screw system.

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There is controversy in literature about timing of surgery for thoracolumbar injuries. There is no conclusive evidence that early surgical decompression and stabilization improves neurological recovery, or that a delay in surgery would cause compromised neurological recovery.

However, it is agreed upon that if the neurological deficit is progressive, an emergency decompression is indicated.

Otherwise there are two schools of thought. One advocates early decompression and stabilization. The benefits highlighted are lesser complication rate and shorter duration of hospital stay.

The advocates of delay in surgical procedures to allow resolution of cord edema.

Decompression

The role of decompression also is controversial.

Decompression is relieving of the compression of the neural elements by retropulsed bone fragments.

It can be done either indirectly or directly. Indirect method is by insertion of posterior instrumentation which puts indirect pull on the compressive elements by distracting the vertebrae. This technique relies on intact posterior longitudinal ligament. Direct method is by exploring the spinal canal through a posterolateral or anterior approach and removing the structures that compress.

If surgery is delayed for several weeks or more, indirect reduction may not work satisfactorily.

Indirect reduction does not effectively reduce the comminuted fractures which has multiple pieces of bone pushed into the spinal.

Approaches To Direct Reduction

Posterolateral Approach

At thoracolumbar junction and in the lumbar spine, a posterolateral approach is helpful in decompression. The procedure involves hemilaminectomy and removal of a pedicle with a high-speed.

The technique is not useful in thoracic spine where lesser space is available at neural elements are at higher risk.

Anterior Approach

The anterior approach allows direct decompression of the cord. But the approach is has potential for higher morbidity and unfamiliar approach to many surgeons.
It also puts visceral and vascular structures at risk of injury. Stabilization with anterior implants needs to be done.

Overall, the posterior surgery takes the least time, causes the least blood loss, and is the least expensive.

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In case of spinal cord injury there is a continuous debate in the literature about operative versus non operative treatment and there are strong adovcates on either side. Because of complex nature of spinal injuries and multiple factors affecting prognosis there are options of treatment available which needs to be individualized in every case.

Broadly speaking, there are two kinds of treatments – non operative and operative.

Before we discuss them further a look into pathophysiology of the cord injury is necessary to grasp the concepts.

Cord Changes After Injury

Injury to the cord is of two types

Primary Injury

It is the actual injury that has occured during the process of trauma and could be a contusion or laceration or transection depending upon the severity of insulting trauma.

Secondary Injury

It occurs due to cellular changes at the injury site, and the effects of ongoing neural compression.
While the first kind is not modifiable except to preventive methods, there is need for an effective agent which would prevent secondary injury.
One of the such agents is the methylprednisolone given in in the immediate postinjury phase. Few studies have suggested good improvement but there are studies which found no such evidence.

Opertive Versus Non Operative Treatment

It seems logical that an ongoing compression should be relieved by surgery but this again is controversial because therer is not enough evidence on this.

Moreover, equally effective neural recovery has been demonstrated by few authors with conservative management. It has been observed that bony remodeling reduces residual canal compromise by more than 50% over the course of 1 year, making surgical treatment unnecessary in many patients.

It is however very clear that the late decompression, once natural recovery has ended, is associated with further improvement in neural function.

It must be noted that animal studies have demonstrated benefit of early and late decompression.

Incomplete neural deficit is a relative indication for surgery and should be considered on patient to patient basis.

In spite of every other factor, a persistent neural compression can inhibit neurologic recovery, and decompression can provide dramatic neurologic improvement in many patients.

Non Operative Treatment

Non operative treatment consists of bed rest, brace, molded orthosis or casts. It is estimated that only 20 to 30% of spine fractures require surgery and rest of them can be treated nonoperatively.

Single-column injuries like compression fractures, laminar fracture, and spinous process fractures can be treated with a brace which provides normal normal spinal alignment and immobilizes it.

Two-column injuries are quite unstable and should be treated by bed rest or hyperextension casting.

Operative Treatment

Operative treatment offers immediate spinal stability which allows early sitting by the patient, easy transfer of the patient and earlier rehabilitation.

Moreover, there is better restoration of spinal alignment and correction of translational deformities which translates into restoration of canal dimensions more.

Operative treatment includes decompression of the spinal cord/nerve roots, fixation of the injured spine followed and fusion of the spine.

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In continuation with spinal canal of cervical spine, spinal canal in thoracic and lumbar spine consists of vertebral body, intervertebral disc, posterior longitudinal ligament anteriorly, pedicles, medial aspect of facet joints on either side laterally and ligamentum flavum & laminae posteriorly.

Injury can cause compromise of the spinal canal and the most common cause is posterior bony retropulsion from a burst fracture of the vertebral body.

Dislocations and fracture dislocations of vertebrae leading to translation between adjacent vertebrae can also cause reduction in canal space. Anterirorly displaced fractures of posterior elements [laminae] can also compromise the canal space.

Postraumatic hematoma formation, disc herniations are other causes of compression following injury.

Lumbar canal stenosis is frequent non traumatic cause of reduction of canal space and neural compromise.

Conus medularis is most distal aspect of the spinal cord and its location varies between T12 and L3. Spinal canal dimensions relative to  spinal cord dimensions are smallest in the T2-T10 region and for this reason the neurologic injury is more commmon after trauma in this region.

Complete spinal cord injury is six times more common than incomplete injury with high-energy trauma to the midthoracic spine .

In addition to smaller canal space,  another factor which is responsible for susceptibility is the lesser vascular supply to the spinal cord. The region between T2 and T10  derives its proximal blood supply from antegrade vessels in the upper thoracic spine and distally from retrograde flow from the artery of Adamkiewicz.

Artery of Adamkiewicz is the largest anterior segmental medullary arterIt typically arises from a left posterior intercostal artery, which branches from the aorta, and supplies the lower two thirds of the spinal cord via the anterior spinal artery

This region is called  circulatory watershed area, which can be variably located between T9 to L2.

Studies have repeatedly shown that there is no definite correlation between the degree of compromise of the spinal canal and the severity of the neural deficit.

Due to variations in the spinal canal space and differences in blood supply the damage to neural structures is caused mainly by the severity and level of injury.

Because the spinal canal in the thoracic area is small and the blood supply is less, severe neurological injury is common in the thoracic spine. Due to greater vascularity, greater spinal diameter and lesser vulnerability of cuada equina, injuries the lumbosacral region may cause marked displacement without  neurological deficit.

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The implant material, its shape, size and the method of affects the  of stress transfer to the bone. Implant loosening, and  fracture of the femur or the implant are risks that arise from stress transfers to the bone. At the same time stress also provides stimulus for maintaining bone mass.

Modulus of elasticity of the implant material affects the stress that it would cause. A decrease in the modulus of the stem, stem length and cross sectional area  causes a decrease in the stress  in the stem. But it would increase the stress in the proximal third of the cement mass, which transfers these stresses to the surrounding bone.

An Increase in the modulus of elasticity, the stem length, and the cross-sectional area of the stem increases the stress in the stem, but decreases the stress in the cement and proximal third of the femur.

Stress shielding occurs because the stress that was originally on the bone is borne by the implant after total hip replacement and the bone of the proximal femur is relieved of stress. As noted before a larger size stem would cause more stress shielding.

The area where the stress shielding occurs in greatest amount is the proximal medial cortex. The prosthesis with medial collar theoretically allows  axial loading of the bone in that area and thus reduces stress shielding. But the role of a collar in preventing loosening of a cemented femoral component has not been clearly established

Cementless stems are more physiological as compared to  fully cemented stems, depending on the stem size and the extent of porous coating.

The bone loss after total hip replacement is also dependent upon the bone mineral density of the patient. There is a strong association between the bone mineral density in the opposite femur and the percentage of bone mineral loss in the operated femur. Therefore the  patients with decreased bone mineral density are at higher risk of bone loss after the surgery.

Usually the  bone loss does not often progress after 2 years.

In acetabular side it has been found that cemented polyethylene cup causes development of peak stresses whereas  metal-backed cup with a polyethylene liner reduces the high areas of stress and distributes the stresses more evenly.

The preservation of subchondral bone, the use of a metal-backed cup or thick-walled polyethylene cup decrease the peak stress levels in the trabecular bone of the pelvis.

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Stress shielding means a reduction in the bone density as a result of removal of normal stress from the bone by an implant. For example it occurs after hip replacement when the normal bone is replaced by an implant.

This is because in a normal person the bone would remodel in response to the loads it is placed under.

When a hip is replaced as in total hip replacement, the load that was usually placed on the bone would decrease and hence would become less dense.

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Femoral offset is the distance from the center of rotation of the femoral head to a line dissecting the long axis of the femur. In case of  total replacement hip the the offset  is considered  as the  distance from the center of rotation of the femoral head to a line bissecting the long axis of the stem.

Normal femoral offset varies  between 30 amd 60 mm.

Image Credit: http://www.traumazamora.org/articulos/offset/offset.html

A decrease in femoral offset would move the femur closer to the pelvis medially. This can lead to  impingement of greater trochanter in extremes.  Medial movement would also result in soft tissue relaxation.  Both of these factors can lead to instability  of the implant and possible dislocation.

Moreover, when the offset decreases, greater force is required by the abductor muscles to balance the pelvis and resultant force across the hip joint also increases resulting  in greater wear and tear.

An increase in femoral offset moves the femur laterally resulting in decrease chances of impingement, a better tension in soft tissues and  better stability.

A change in femoral offset  does not affect the leg length and thus provides a measure to make adjustment without altering the leg length the leg.

An increase in femoral offset decreases the force required by the abductor muscles to balance the pelvis, which will improve gait. As well, resultant force decreases with increased offset, which may result in less wear and loosening over time.

In total hip replacement surgery, the offset needs to be determined preoperatively for better planning of the surgery.

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