Fracture of neck of femur

Blood supply to the head and neck of femur
The profunda femoris artery arising from the femoral artery gives off medical circumflex femoral artery.  This gives off the lateral epiphyseal and superior and inferior metaphyseal arteries.  The lateral epiphyseal arteries are important and supply the laterial 2/3 of the femoral head.  The superior metaphyseal artery supplies the superior aspect of the femoral neck.  The inferior metaphyseal artery supplies the inferior part of the neck and the adjacent part of the head derived from the metaphysis.
The medial epiphyseal artery supplies a circumfoveal sector of the head.  It is a continuation of the artery of the ligamentum teres which arises from the acetabular branch of the obturator artery.

Femoral neck fractures that are intracapsular and may threaten any or all of the three sources of blood to the femoral head:

• the cervical vessels in the retinaculum of the joint capsule - usually damaged if the fracture is displaced
• intramedullary vessels - always torn
• from the ligamentum teres - usually contributes minimally in the elderly and not uncommonly, may be non-existent

In addition to the damage to the blood supply, the intracapsular nature of the fracture hinders recovery from the injury:

• intra-articular bone has only a thin periosteum and has no contact with soft tissues - the response to injury - callus formation - is weak
• blood remains inside the joint capsule, increasing intracapsular pressure and further damaging the femoral head; synovial fluid hinders clotting

Incidence and Mechanism
The fracture of the neck of femur is common in the elderly.  It does occur occasionally in young adults and even in children.  It occurs more frequently in women.  In India, the incidence of fracture neck of femur in children is higher than in the Western countries.
The fracture may result either from rotation violence at the hip due to tripping over something on the floor and falling or a direct violence over the lateral aspect of the hip by a fall on the side.

Two broad groups of fractures are recognised in the neck of femur

(1) Intracapsular fractures (2) Extracapsular fractures.

Intracapsular Fractures
This is diveded according to the level of the fracture line in the neck as follows.

                1) Subcapital
                2) Transcervical
                3) Basal

Extracapsular Fractures
There are all grouped as Trochanteric fractures of various types.

INTRACAPSULAR FRACTURE NECK OF FEMUR
This is also called a high fracture neck of femur.  In this group, the proximal fragment often loses part of its blood supply and hence, the union of this fracture is difficult.  This is a serious injury in the elderly patient.  In the very old and debilitated person, it can precipitate a crisis in the precarious metabolic balance.  It can become a terminal illness due to uremia, lung infection, bed sores etc, and be fatal.

Classification (Garden).
This classification relies only upon the appearance of the hip on the AP radiograph. It is used to determine the appropriate treatment.

• stage I : incomplete fracture of the neck (so-called abducted or impacted)
• 
• stage II : complete without displacement
• 
• stage III: complete with partial displacement: fragments are still connected by posterior retinacular attachment; there is malalignment of the femoral trabeculae
• 
• stage IV : this is a complete femoral neck fracture with full displacement: the proximal fragment is free and lies correctly in the acetabulum so that the trabeculae appear normally aligned
• 

Subcapital fractures are classified along two continuums: the Pauwels and Linton classifications.

Pauwels Classification:
Type I has an obliquity ranging from 0 to 30 degrees
Type II has an obliquity ranging from 30 to 50 degrees
Type III has an obliquity of 70 or more degrees

The greater the obliquity in the fracture, the higher the chances of either delayed or nonunion. This woman's fracture is Pauwels Type II and therefore has an intermediate chance of delayed or nonunion.

Linton Classification:
Stage I: Incomplete fracture
Stage II: Complete but undisplaced fracture
Stage III: Complete, partially displaced fracture
Stage IV: Displaced and totally free fracture

Clinical Features
The patient is usually an elderly person with a history of a fall and inability to walk.  On inspection, the injured led lies in a position of external rotation and there is shortening of the leg.  The attachment of the capsule to the distal fragment prevents excessive external rotation of the leg.  On palpation, there is tenderness over the anterior and lateral aspects of the hip joint.  The greater trochanter is elevated on the injured side.  All movements are extremely painful except in the rare case of an impacted type of fracture.

Radiological Features
An anteroposterior view of the whole pelvis to show both the hips must be taken.  It shows the level and the type of fracture.  The subcapital and transcervical fractures are divided into three types according to the obliquity of the line of fracture (Pauwel).  This is expressed as the angle formed by the line of the fracture with the horizontal line (Pauwel's angle).

Type I: Pauwel's angle is less than 30 degrees, the fracture line is nearer the horizontal.
Type II: The angle is between 30 and 70 degrees.
Type III: The angle is more than 70 degrees and the fracture line is nearer the vertical.
In the more vertical fractures, the action of the gluteal and adductor museles produces a shearing force on the fracture line and hence nonunion is commoner.  Thus, prognosis is worse in Type III and good in Type I.

(Following imaging info from http://www.emedicine.com)

Radiography is the preferred initial imaging modality in evaluating femoral neck fractures because of its near universal availability, ease of acquisition, and documented correlation with surgical results over many years of use.

However, radiography has some limitations. Spiral fractures are difficult to assess on a single view. Comminution is also not as easily demonstrated as it is with CT. Some stress fractures are simply not visible on plain images at all. However, radiography will likely remain the mainstay in the evaluation of these injuries in the near future, and cross-sectional imaging will play an increasing but supplementary role.

False Positives/Negatives: Some femoral neck fractures are not visible on radiographs obtained during the initial evaluation. If the clinical suspicion is strong, these cases can be further evaluated with MRI, which shows bone marrow edema, or nuclear medicine bone scanning, which shows increased tracer uptake. The latter is much less expensive than MRI and nearly as sensitive. The major drawback of bone scanning is in the first 48-72 hours after trauma, when its sensitivity is lower than that of MRI.

CT plays an increasingly important role in evaluating the hip after a fracture. CT is exquisite useful for imaging abnormalities of the bone itself. Because of its superior resolution, cross-sectional capabilities, and amenability to image reconstruction in the coronal and sagittal planes, CT is useful for assessing fracture comminution preoperatively and in determining the extent of union (or lack thereof) postoperatively.

Degree of Confidence: CT is the most useful test for evaluating bony injury. However, axial fractures in the plane of the images can on occasion be missed with CT. This potential is decreased with the use of images reconstructed in orthogonal planes and newer multidetector CT scanners.

MRI is both sensitive and specific in the detection of femoral neck fractures, because it can show both the actual fracture line and the resulting bone marrow edema. The superior contrast of MRI when appropriate pulse sequences are used, the intrinsic spatial resolution, and the ability to image in multiple planes (coronal, axial, and less commonly, sagittal) makes MRI the premiere imaging modality, especially in the setting of stress fractures, which can appear normal on initial plain images.

Popular pulse sequences include coronal and axial T1-weighted and T2-weighted fat-suppressed sequences, although several other bone marrow sequences can also be used. In practice, a large field of view is usually used so that both hips and the bony pelvis can be imaged simultaneously. Intravenous contrast enhancement is not routinely used in the assessment of fractures. The fracture line can be visualized as linear low-signal-intensity areas surrounded by bone marrow edema, which is hypointense relative to normal marrow on T1-weighted images or hyperintense on T2-weighted images.

Drawbacks of MRI include its longer imaging time, its relative lack of widespread availability, its higher costs, and the exclusion of patients with cardiac pacemakers and certain metal hardware in their body. With continued technological advances the imaging time has decreased, as have the costs, making MRI more cost-effective.

MRI is the most sensitive modality in detecting bone marrow changes related to avascular necrosis, even when radiographic findings are normal; therefore, MRI is the imaging modality of choice in this regard. When avascular necrosis is detected after surgical fixation for a femoral fracture, the patient can become a candidate for placement of a prosthesis. More importantly, MRI can be used to detect early stages of ischemic necrosis in the femoral head, where interventions can be initiated before further damage can occur. Such damage may include femoral head collapse, secondary osteoarthritis, or fragmentation.

MRI is currently the best imaging modality for detecting femoral neck fractures. Several facts must be kept in mind, however. The normal bone marrow of the pelvis and hips can have a patchy intermediate-signal-intensity appearance corresponding to the persistence of red marrow. Also, the subchondral area of the femoral head can sometimes have a thin rim of red marrow. These normal variants should not be confused with fractures.

Fractures and contusions should not be confused with idiopathic transient osteoporosis of the hip. This is an uncommon, self-limited disease that affects middle-aged men and pregnant women. It appears as osteopenia on plain radiographs and as areas of decreased T1 signal intensity and increased T2 signal intensity which generally extends from the femoral head to the intertrochanteric line on MRI. Usually, only one hip is affected at a given time. To complicate matters, transient osteoporosis can predispose patients to a fracture if proper care (eg, protected weight bearing) is not implemented. ULTRASOUND Section 7 of 12
Author Information Introduction Differentials X-ray Cat Scan MRI Ultrasound Nuclear Medicine Angiography Intervention Pictures Bibliography

Ultrasonography does not play a significant role in the routine evaluation of hip fractures. However, it has been used in research to evaluate the degree of distention of the hip joint capsule after fractures and in the study of elevated intracapsular pressures. Sonograms can also depict the presence of an intracapsular hematoma, which is mildly echogenic, as distinguished from synovial fluid, which is anechoic

Nuclear Medicine
Findings: Approximately 80% of fractures can be visualized 24 hours after trauma, as seen by diffusely increased tracer uptake. By 3 days after trauma, 95% of fractures are visualized, and maximal fracture sensitivity is found at 7 days; this knowledge may be helpful in equivocal cases. Given the high sensitivity of nuclear medicine studies, they can be used to diagnose suspected femoral neck fractures not confirmed by means of plain radiography.

Nuclear medicine studies with technetium-99m methylene diphosphonate (99mTc-MDP) have also been found to be effective in predicting healing complications related to femoral neck fractures. Stromqvist et al have demonstrated that 99mTc-MDP bone scans of the hips performed within 2 weeks after fixation surgery for femoral neck fractures have an excellent prognostic value for future fracture redisplacement, nonunion, or segmental femoral head collapse.
Although sensitive, bone scintigraphy is not specific for fractures. Other processes such as infection, inflammation, or tumor formation can also demonstrate increased uptake. However, in the right clinical setting (eg, known trauma), it is highly sensitive for the detection of fractures.
 

Conservative Treatment
Fractures at this level have a poor capacity for union due to the following factors.
a) interference with the blood supply to the proximal fragment.
b) difficulty in controlling the small proximal fragment.
c) the lack of organisation of the fracture haematoma due to the presence of the synovial
fluid.

Surgical Treatment
Two essential principles to be followed in the surgical management of this fracture are
(a) perfect anatomical reduction.  (b) rigid internal fixation.

The earlier method of stabilising the fracture was by internal fixation with Smith Petersen Trifin nail.  The fracture is reduced by manipulation with the patient in a special orthopaedic table.  The fracture is internally fixed with an S.P. Nail under radiological control.
The more recent method of internal fixation of the fracture is the use of multiple compression screws

Dynamic Hip Screw

.
In older patients above 60 years, such fractures are treated by removing the head of the femur and replacing it by metal prosthesis like Austin Moore's prosthesis.  This enables the patient to be ambulant and start early weight bearing.

Fracture neck of femur in Children
The fracture is reduced by manipulation and the leg immobilised in full plaster spica in abduction for 8-10 weeks.  When indicated internal fixation could be done with multiple thin Austin Moore's Pins.

Complications of Fracture Neck of Femur
The important complications are: a) Non-union b) Avascular necrosis of head of femur.

Non-union
Failure of union of this fracture still occurs due to improper reduction of imperfect internal fixation.  When this occurs, the patient complains of pain and develops instability on walking.  The condition is treated by intertrochanteric osteotomy (McMurray) in the younger age group and replacement arthroplasty in the elderly.

In the very old patient with poor general condition, the only treatment possibly may be to keep the leg between sand bags and attend to the general care of the patient.  As soon as the general condition is restored and the local pain relieved, physiotherapy is started.  Movements of the hip are encouraged and the patient is got up on crutches about three weeks after the injury.  Gradual weight bearing will lead to painless nonunion.  This end result is practicable and is still useful in our country, in places where good surgical and hospital facilities are not available.

Avascular Necrosis
Avascular necrosis of the head of the femur is an unpredictable complication met with after any type of internal fixation.  The patient presents with pain in the hip and limping.  There is limitation of all movements of the hip with muscle spasm.  Radiography shows patchy areas of increased density in the head of the femur.  Treatment in the early stages is by rest, traction and weight relieving caliper.  When indicated, osteotomy or replacement arthroplasty is done.

(Extra Capsular Fracture neck of femur)
These are also called low fractures and are again classified as (i) Stable, (ii) Unstable fractures.  In this group, the blood supply to the proximal fragment is not interfered with and there is a greater area of contact between the two fragments; hence the fractures unite easily.  While union is the rule, it is common to see these fractures malunited with a coxa vara deformity.

The normal neck shaft angle is about 115 degrees.  When the angle is reduced to nearer
90 degrees, the deformity is called Coxa Vara.

These fractures occur in the elderly and the nature of the violence is the same as in the intracapsular fracture.

Clinical Features
On examination, the injured leg lies externally rotated and is obviously shorter.  The degree of external rotation is greater than in the intra capsular fracture.  There is marked local swelling and echymoses over the trochanteric area.  All movements of the hip are extremely painful and limited.  This has to be differentiated from intracapsular fracture.
                                                      Intracapsular                                     Extracapsular

        Incidence                                Less common                                  More common
        Causative violence                 Minimal rotation violence              Lateral violence
        Clinical features
        External rotation                     Minimal                                          Fully externally    rotated
        Local swelling                         Nil                                                   Marked local swelling
        Treatment                               Difficult                                           Easy
        Complications
        Non Union                               Common                                         Does not occur
        Malunion                                Rare                                                Common
 

Radiological features
Stable Type: There is a single fracture line and it is a two piece fracture.
Unstable Type: This is a comminuated fracture with multiple fractures at the trochanteric level

Management
The principle of the treatment is reduction of the fracture and maintenance of the fragments in good position till union occurs.

Conservative Treatment
This consists of the application of continuous skeletal traction.  For cases with marked coxa vara, continuous skeletal traction through the upper tibia is applied and the leg is immobilised in the Bohler Braun splint and the foot end of the bed is raised. Traction with 12 to 15 Ibs is sufficient.  The coxa vara gets corrected and the fracture unites in about 12 weeks.  When the coxa vara is not marked, skin traction in Thomas' splint will be sufficient.  Excepting the fact that the patient occupies a hospital bed for about 3 months, there is no other serious defect in this conservative method and the results are highly satisfactory.

Operative Treatment
This consists of manipulative reduction and internal fixation.  The internal fixation is done by a nail plate as shown in the figure. The McLauglin two piece nail plate has been commonly used.  The use of a single piece angled nail plate (Jewett) has been found to be mechanically superior and gives good results. More recently the use of compression hip screw and plate system has enabled earlier mobilisation of the hip and weight bearing.

Complications
The main complication is malunion with coxa vara and shortening.  If the coxa vara is gross, it can be corrected by osteotomy.

The death rate within one year of fractured neck of femur is typically reported as between 20% and 35%.Performance indicators based on mortality after hospital admission for such fractures have been promoted.The only measure of mortality in routine hospital statistics, however, is “in-hospital mortality”—death during the initial admission for the fracture. We analysed inpatient statistics that had been linked to death registration data in the former Oxford NHS health region (population 2.5 million) from 1994 to 1998. (BMJ. 2002 October 19; 325 (7369): 868–869)

Exploring the Outcomes of Fractured Neck of Femur (http://www.leeds.ac.uk/nuffield/infoservices/UKCH/fnf.html)

Identifying the Key Actors
The outcomes of interventions for fractured neck of femur can be explored in five types of service (prevention, access to hospital setting and initial diagnosis, actual treatment episode and subsequent hospital based recovery, recovery in the community, longer term recovery) and at four possible time periods (prior to fracture, early treatment, first three months, longer term).

There are a wide range of groups whose outcomes need to be considered, including the patient, carer, clinicians, managers and purchasers. Some will have a major interest throughout - the user/patient - while others will be primarily interested in shorter term outcomes (for example, the hospital team) or in longer term outcomes (the potential carer, the primary care team and other health and social services).

Identifying Desired Outcomes
Examples of the desired outcomes for the user, hospital team and purchaser are outlined in Table 1. As many patients with hip fracture may have other (pre-existing) ill-health problems, their assessment and implications for achieving best desirable outcomes need to be explored. From the patient's perspective, getting the process right may be most critical, suggesting the key role for measurement of satisfaction with the care, treatment and achieved outcome. For patients with pre-existing co-morbidity, desired outcomes will relate to potential change in their level of dependency and thus possible consequences for (informal) carers.

When Should the Outcomes be Measured?
Appropriate time periods will depend on the particular use for the outcomes data. Within routine patient care, achieved outcomes need to be assessed at discharge, in the subsequent three months and, for those with pre-existing or consequent co-morbidity, in the longer term, as part of the ongoing provision of care. It is important to measure and record pre-fracture mobility as a baseline measurement for comparison with the situation post-fracture.

Matching Measures to Desired Outcomes
Measures of pre-fracture and post-fracture mobility are central to any assessment of outcomes. These can be assessed by use of a measure of physical aspects of daily living (Freeman et al, 1995), a measure of instrumental/extended activities of daily living (shopping, use of public transport), use of a walking scale or short mobility scores (Keene et al, 1993), together with the use/need for walking aids (both prior and subsequent to the injury). The range of measures that have been used in research and audit studies are summarised in Table 2. Some key points to note are:

• Measures of impairment and disability predominate, both because they are easy to measure and valuable for assessing fracture repair.
• There may be a useful role for multi-dimensional health profiles in broadening the focus of measurement to the consequences of the fracture for the individual user, especially as few of the measures address explicitly patient defined/specified desired outcomes.
• Mortality and the ability to return home (defined as the patient's usual address) have been used as prime indicators at a population level (CRAG, 1994; Department of Health, 1993). Ability to return home will depend on a number of factors including walking ability, available formal health and social service support and informal carer support, and, for those coming from residential accommodation, the ability of the residential home to meet any additional (higher dependency) needs of the patient.
• For patients with pre-existing co-morbidity, changes in dependency must be assessed. Pre-existing and subsequent levels of handicap and implications for (informal) carers need to be (re-) assessed.

Measuring Longer Term Outcomes

For patients with pre-existing co-morbidity, a fractured hip may accentuate the level of dependency; for others, the fracture may form a transition point towards greater dependency. In both situations, the consequences for informal carers (friend, neighbour or relative) must be recognised, suggesting the need for the assessment of long term disability and handicap. Possible scales include the London Handicap scale or the Functional Autonomy Measurement Scale (Harwood et al, 1994). Alternatively, the individual components of handicap could be assessed, most particularly any lack of mobility and its subsequent implications, mental health and social functioning or isolation.

Interpreting Outcome Data

There is a range of factors that need to be taken into account in interpreting aggregate outcomes data for fractured neck of femur. These include:

• pre-fracture ADL/walking ability
• existing patient co-morbidity and level of frailty
• type of fracture (intracapsular or extracapsular)
• level of support at home
• other characteristics of the patient (age, socio-economic status, source of admission).

Information needs to be collected on these potentially confounding variables, to allow for their control in any comparative analysis and to enable sound interpretation of the indicators. If length of stay targets (a process measure) are set by purchasers, these also need to be adjusted for case severity adjustment. Setting inappropriate targets will reduce the quality and impair the patient outcome (Beech et al, 1995).

Useful Link http://www.bonetumour.org/book/Truma/allheading/chap_18_head.html