PATHOLOGICAL FRACTURE

Can you describe the radiograph?

This is an AP radiograph of the right hip. There is a pathological fracture of the right femur in the subtrochanteric region of a skeletally mature patient. A lytic area extends from just distal to the lesser trochanter to approximately 10 cm down the femoral shaft. There is cortical destruction and a relatively broad zone of transition. The matrix of the lesion is predominantly lytic. There are no other obvious areas of abnormal bone on the visualised femur and pelvis although plain radiographs are often unreliable as a measure of cortical destruction. Most studies state that at least 30% of bone destruction must take place prior to any changes being visible.

What is your differential diagnosis?

The differential diagnosis is dependent on the age of the patient. I would be highly suspicious of metastasis when considering a lytic lesion of bone in a patient over the age of 40, particularly in the proximal femur. In a younger patient, the differential diagnosis would include a variety of lesions which present with lysis (listed below).

The patient in question is 65 years old. How would you proceed if presented with this radiograph?

The patient has a fractured femur with a potential for blood loss and significant pain. I would ensure they are stable haemodynamically and have received appropriate analgesia prior to moving on to a full history and examination. Since the main dif- ferential diagnosis is of metastasis, I would conduct a full history and examination,

concentrating on identifying the primary tumour. As the main sources for a pri- mary tumour are breast, bronchus, thyroid, kidney and prostate, I would focus my history and examination on these areas.

Following a full history and examination, I would organise a full set of blood tests including FBC, U&Es, LFTs, TFTs, bone profiling (alkaline phosphatase, cal- cium and albumin), CRP, ESR, and tumour markers, in addition to a myeloma screen (which should include urine electrophoresis to look for Bence Jones protein). In terms of imaging, I would want plain radiographs of the rest of the femur with orthogonal views. I would organise a CT of the chest, abdomen and pelvis to look for a primary tumour, as well as a bone scan to look for other skeletal deposits. An MRI scan of the lesion would also be helpful. Following rapid investigation, the patient should be discussed with the local tumour service to discuss management and fur- ther investigation, which will include biopsy in most cases.

Biopsy should be performed by the tumour surgeon who will ultimately be treat- ing the pathological fracture. It is particularly useful where there is diagnostic doubt or, in a solitary bone lesion, where there may be a chance for curative treatment. It is probably superfluous to requirements if the diagnosis is disseminated metastatic malignancy to bone.

What are the management principles when dealing with any pathological fracture? The aims of surgery with any pathological fracture are ideally to ensure a single opera- tion for the patient to restore function and remove pain. It should allow immediate and full weight bearing, carry minimal morbidity, deal with all the metastatic disease within that bone and minimise time spent in hospital. Although pathological fractures can unite, there is a much higher rate of non-union as well as a longer time to union.

When considering treatment options, it is also pertinent to ascertain a life expec- tancy for the patient in conjunction with the oncologists.

The Scandinavian Sarcoma Group produced a scoring system to estimate survival after bone metastases. It allows clinicians to estimate survival and subse- quently tailor treatments for pathological fractures.

When dealing with a pathological lesion within a bone, how does one estimate the risk of fracture?

As a rule of thumb, where 50% of a single cortex of a long bone (in any radiological view) has been destroyed, patients are at significant risk of pathological fracture. In addition, avulsion of the lesser trochanter is an indication of imminent hip fracture. The Mirels score is frequently used to calculate the risk of fracture in long bones.

Mirels proposed a scoring system based on four characteristics: (1) site of lesion;

(2) nature of lesion; (3) size of lesion; and (4) pain. All the features were assigned progressive scores ranging from 1 to 3, and the current recommendation from the BOA/BOOS guidelines is that a score of 9 or greater warrants prophylactic fixation prior to radiotherapy.

Pathological Fracture 

LYTIC – FOGMACHINES        SCLEROTIC – ‘Surgical sieve’ VITAMIN CD

F: Fibrous dysplasia or fibrous cortical defect (FCD)

O: Osteoblastoma

G: Giant cell tumour (GCT) M: Metastasis/myeloma

A: Aneurysmal bone cyst (ABC)

C: Chondroblastoma or chondromyxoid fibroma

H: Hyperparathyroidism (brown tumour) I: Infection (osteomyelitis)

N: Non-ossifying fibroma (NOF)

E: Enchondroma or eosinophilic granuloma (EG)

S: Simple (unicameral) bone cyst

Vascular: Haemangiomas, bony infarcts Infection: Chronic osteomyelitis

Trauma: Stress fractures/healing fractures Autoimmune

Metabolic: Hyperparathyroidism, Paget’s disease

Inflammatory/Idiopathic Neoplastic:

Primary – Osteoma, Osteosarcoma

Metastatic – Prostate and breast, most commonly

Congenital: Bone islands, Osteopoikilosis, Osteopetrosis, Pyknodysostosis

Drugs: Vitamin D, fluoride, lead poisoning