FRACTURE NECK OF FEMUR
Consultant Orthopaedics Surgeon, Specialist in Joint Replacement and Reconstruction, Bombay Hospital.
Fracture neck of femur is a common injury. It commonly requires surgery for good results. The surgery needs to be precise to avoid potential complications. Most, if not all fractures should be surgically treated such that the patient can be up and about on their fractured legs. Intertrochanteric fractures require fixation and transcervical fractures are commonly treated by replacement in the elderly and by fixation in the young. The replacement can be partial when only the head and the neck of the femur are replaced or total when the acetabulum is replaced as well. Total Hip Replacement can only be performed by a well trained surgeon in proper set-up. With due care and precise surgery these difficult fractures can by successfully treated.
Fracture neck of femur is one of the commonest injuries causing morbidity and mortality in patients of geriatric age group. With improvements in standards of health and longevity, this fracture is being increasingly encountered. Even the current emphasis on Osteoporosis aims finally to decrease the incidence of this fracture as this is the fracture with the greatest risk to independent ambulation. In this article, I have outlined the salient features of management of this fracture.
The upper end of femur anatomically consists of the head, the cervical region or the neck and the trochanteric region. Fractures of the head of the femur are rarely seen and are due to severe trauma such as high energy motor car collision. These fractures are not a part of fracture neck of femur and are not being discussed here. Fracture neck of femur implies a fracture of the cervical region of the femur or the intertrochanteric region.Fracture of the Cervical region of the femur (Fig. 1)
The fracture occurs between the head and the trochanteric region of the femur. The fracture can be displaced or undisplaced. There are classifications of the fracture depending on the degree of displacement and the degree of angulation of the fracture. Suffice it to say, that on studying the radiographs, the more vertical the fracture line appears and the more displaced the fracture fragments are, the worse is the prognosis.
Relevant information necessary for decision making
1. The blood supply of the femoral head comes mainly in a retrograde fashion from the neck upwards. Therefore, in a displaced transcervical fracture the blood supply can be seriously jeopardised.
2. Transcervical fracture is called in Orthopaedic jargon "a fracture of necessity". This means that this fracture should almost always be operated on for a good result. The only exception to this statement is the impacted fracture on which the patient is walking. Some of these impacted fractures may be treated conservatively but even this may have a 30%
Fig 1 Radiograph showing a transcervical fracture neck of femur. The arrow points to the fracture.
failure rate due to late disimpaction. Hence, even in impacted fractures it may be prudent to do fixation in situ with a suitable device such as cannulated screws.
3. For fractures that are displaced there are essentially two treatment strategies. One can either reduce and fix these fractures or one can replace for the head and neck of the femur by a prosthesis.
4. The more displaced the fracture is on presentation and the greater the delay in instituting treatment, the greater is the risk of avascular necrosis of the head of the femur due to lack of blood supply to the head of the femur.
5. Despite the advances in surgical technique and the quality of prostheses, the function of the hip after satisfactory healing of the fracture with a viable head of the femur is better than the function after prosthetic replacement of the head of the femur. Apart from that, one healed with a viable head the good function of the hip will last life long whereas function with the prosthetic head can deteriorate after some years mainly due to loosening and wear.
6. In physiologically younger and active patients, displaced fractures of the neck of the femur should be treated by reduction and fixing. The patient needs to be explained that there is a risk of further surgery if the hip develops painful avascular necrosis, a complication that may not be avoided despite the best surgical treatment.
7. In physiologically older patients, these displaced fractures are best treated by replacement for the head and neck of the femur so that potential further surgery can be avoided.
8. The replacement can be partial such as a Hemireplacement e.g. Austin Moore or Thompson prosthesis. This sort of prosthesis works well for some years but can become loose and can even cause acetabular erosions. Cementing the prosthesis can prevent the problem of loosening to some extent. Thompson type of prostheses are commonly cemented.
9. A special type of Hemireplacement is a bipolar prosthesis. Here the prosthesis is of a special design which theoretically allows movement within itself and also between the prosthesis and the acetabulum thus allowing a greater range of movement at the hip joint. However, this advantage is not universally acknowledged.
10. In older but active patients the replacement can be Total which means that the acetabulum as well as the femoral head are replaced to provide a totally new articulating surface. The advantage of this operation is that it is longer lasting and provides a virtually painfree hip.
Fig 2 Radiograph showing the treatment of a transcervical fracture. Here the fracture has been internally fixed by cannulated screws.
The disadvantage is its higher cost and the inability of the patient to squat and sit crosslegged post-operatively. However, in the well chosen patient the advantages outweigh the disadvantages significantly. However, the operation of Total Hip Replacement is more difficult and should be performed by a well trained surgeon in proper operating room conditions. It is generally accepted that the functional result after a total hip replacement is much better and much longer lasting than the result obtained after a hemireplacement.
11. When the fracture is fixed the specific complications can be non-union of the fracture or avascular necrosis of the head of the femur that may progress to painful arthritis.
12. When the fracture is treated by replacement of the head and neck of the femur by a prosthesis, the specific complication can be of dislocation.
Fig 3 Radiograph showing the treatment of transcervical fracture by a hemiarthropalsty. The prosthesis utilised is the Austin Moore prosthesis.
Fig 4 Fig 5 Radiograph showing a total hip replacement carried out for a transcervical fracture neck of the femur. Radiograph showing an intertrochanteric fracture of the femur.
13. Infection and thromboembolism, can occur in both groups albeit rarely.
Illustrative cases of fractures treated by the various methods are shown. (Figs. 2,3 and 4).
Intertrochanteric Fracture (Fig. 5)
As the name suggests these fractures occur between the trochanters of the femur. The area involved is primarily cancellous bone. The blood supply to the head of the femur is not disturbed and avascular necrosis of the femoral head does not occur.
Fig 6 Radiograph showing stabilisation of the intertrochanteric fracture by a sliding nail plate device.
The intertrochanteric fractures can be classified by the number of fracture fragments into 2 part, 3 part and 4 part fractures. The more fracture fragments there are, the more complicated the fracture is. The fractures are also classified into stable and unstable varieties based on whether there is medial bony fragment apposition on reduction radiographs. If there is no bony contact on either the AP or the lateral image medially the fracture is deemed unstable.
Intertrochanteric fractures should be fixed with suitable devices as soon as the medical condition of the patient permits. In some cases, especially when the fracture geometry reveals a mainly stable fracture, it may be treated conservatively. How ever, this necessitates a period of bed rest and traction for at least 6 weeks, a situation which is most undesirable in elderly patients due to the problems of recumbency.
The surgical philosophy is to align the fracture in the best possible manner and to securely hold the fractured fragments in this position by suitable metallic devices (Fig. 6). Generally, the patients can be allowed up and walking on their fractured legs as soon as the acute trauma and pain of the operation subsides, a matter of two to three days. When the fracture configuration is unstable the surgical philosophy involves stabilizing the fractured fragments first and then utilising suitable fixation to hold the fracture till the bone unites.
Union of the fracture is not really a problem as the fracture occurs through cancellous bone. Union in slight malposition (coxa vara) is a common complication and the patient is left with a limp due to shortening and weakening of the abductor muscle (Trendelenburg gait). Attention to detail and use of modern sliding metallic devices can avoid this complication.