Sacral Insufficiency Fracture?
Written by Chris Heywood
Sacral insufficiency fractures (SIF's) are now know to be a common cause of debilitating back pain predominantly in the elderly population, though not exclusively. But why do these occur, and what might you feel?
The concept of SIF's was first put forward in 1982 by Lourie (1) and although the recognition has increased, there is still thought to be a high degree of under, or delayed, diagnosis.
A primary reason for this is thought to be that in the elderly population, where SIF is most often seen, there are a variety of pathological processes, that can express similar symptoms, but which are perhaps more familiar with healthcare professions and thus carry a higher diagnostic bias initially. These are often non specific however and indistinct.
There a number of accepted predisposing risk factors for SIF, which are:
Elderly Women With Osteoporosis
Osteoporosis is a condition where bones are more likely to break/fracture due to a loss in their natural strength, sustaining injuries from falls and knocks, that would not normally occur in healthy bone. Up to half of women, and 20% of men, over the age of 50, that suffer a fracture do so as a result of reduced bone quality and strength. For more info
Previous Pelvic Radiation
Radiation treatment, often given as part of certain cancer treatments, can have a direct effect on the bone quality in the area around the location of the therapy. This is especially the case when considering bladder, rectal, prostate, cervical, womb and vaginal cancers (there are more) but is often considered a late effect, i.e. after 6 months+, rather than immediately however. For more info
Multiple Myeloma is a type of cancer that affects the white blood cells, more specifically a plasma cell, that is found inside our bone marrow. These normally help to neutralise pathogens such as bacteria and viruses by producing antibodies. These abnormal plasma cells can then go on to form masses within bone, such as the pelvis altering the strength and quality and subsequent risk of fracture. For more info
Paget's Disease is a condition that effects the normal ''repair and renewal' process that we see in healthy bone metabolism . Our bones are under a constant cycle where by old bone is broken down and removed and replaced by new bone. In Paget's disease however the equilibrium of this process, along side an increased volume of overall bone turnover, can be greatly altered meaning that new bone can be weakened and brittle. For more info
Renal Osteodystrophy is a type of bone disease that is caused by having a long term, elevated level, of Parathyroid Hormone in your blood stream. This can cause an increased level of calcium to be removed from your bones making the natural reparative cycle of bone, that we normally see, increasingly inefficient and of inferior quality. It is normally associate with chronic kidney disease. For more info
Steroid Induced Osteopenia
Steroid Induced Osteopenia refers to the thinning of the bones that we can relate to people who are on long term steroids. This can include inhalers, prescribed for some breathing complaints, and tablets such as Prednisolone, with the general definition of long term being everyday for more than 3 months. Steroid creams are thought of carry less of a risk. For more info
Parathyroid Hormone has a direct effect on the levels of calcium, phosphorus and vitamin D in our blood and bones. It is produced by 4 Parathyroid Glands that are found behind the Thyroid Gland in the neck. HYPER-Parathyroidism refers to when elevated levels of the hormone are produced which can in turn lead to Chronic Kidney Disease and Renal Osteodystrophy, as above. For more info
Rheumatoid Arthritis (RA) is a condition we commonly see in our clients is an autoimmune disorder that can commonly cause joint inflammation. The process that underlies the condition however can also affect the bone matrix - the architectural makeup if you like of the bone itself which can lead to bone weakness and poor structural quality. Some what ironically, some of the medications we use to treat RA can also have a direct effect on the bone quality as well. For more info
What is a Sacral Insufficiency Fracture (SIF)?
Sacral insufficiency fractures are a sub-type of stress fractures are a result of normal stresses being applied to abnormal bone that has lost its elastic resistance (2).
Denis et al (3), divided the sacrum up into three separate zones:
1) Outer Sacrum - Zone 1
2) Mid Sacrum - Zone 2
3) Inner Sacrum - Zone 3
The lower lumbar spine above, jointing to the sacrum below
There are some theories that SIF's occur primarily in Zone 1 and that the overload stress this then places on other anatomical regions can cause SIF's elsewhere within the sacrum/pelvis. Supporting this notion is the high incidence of multiple pelvic insufficiency fractures seen, with the most commonly associated being the Pubic Rami and Parasymphyseal regions (4). Fractures can be unilateral (one sided) or bilateral (2 sided) and neither appears to be more common than the other.
The most common presentation of SIF's are that of severe low back pain with a more diffuse pattern, that is often worse on movement, which can give rise to radiating sacral, buttock, hip and/or groin pain. Severe radiating pain down the leg is more unusual although not unheard of. Local tenderness on palpation is often seen through the lower back and sacrum. All in all, a rather non distinct presentation that is not altogether unusual and could be interpreted as originating at various other sites.
Historically treatment of SIF's has been with conservative management varying from bed rest to exercise modification such as crutches along with analgesia for pain control. A majority of patients will spontaneously recover, on average, within 12 months, but this can be longer. For those that fail conservative management, or risk other health complications from long term reductions of mobility, Sacroplasty may be an option.
Sacroplasty is a procedure where a special cement PMMA (Polymethyl Methacrylate) is injected under image guidance, into the sacral fracture site(s). It is a fairly new technique that has been derived from a more longstanding procedure called Kyphoplasty, which involves injecting the PMMA in to a vertebral body in the spine instead
There are two main techniques:
1) The Posterior Approach
2) The Long-Axis Approach
More recently there has been an introduction of a Sacral Kyphoplasty but this is significantly less common than the aforementioned techniques so will not be discussed further at present.
As with many new medical procedures the problem of good strong evidence is limited and only time will solve this however the research that has been undertaken to date is very positive on the whole. Akin to spinal disc prolapses, there is an acceptance that spontaneous recovery will, in most, occur naturally in 12 months (on average), so conservative management is championed by many. For those that don't heal however, are in too much pain, or where the conservative management (which is structured around significantly reduced mobility) is not ideal, Sacroplasty may be an option.
Sacroplasty has very limited patient based education available which is why this initial page has been created. If you do want further reading however the two papers listed below offer excellent insight and can be accessed by Google with no fee or memberships required. They both use medical terminology which may be difficult for some to understand however as more information and pictures become available we will endeavour to feature this in an easy to understand format.
The following paper's were very helpful in the construction of this page so are acknowledged:
Lyders EM, Whitlow CT, Baker MD, Morris PP. Imaging and Treatment of Sacral Insufficiency Fractures. Am J Neuroradiol 2010;31:201-10 (excellent for reading around the subject and getting a global overview)
Health Net National Medical Policy: Percutaneous Sacroplasty. (Very good review paper of present research and outcomes)
(1) Lourie H. Spontaneous osteoporotic fracture of the sacrum: an unrecognised syndrome in the elderly. JAMA 1982;248:715-17
(2) Lyders EM, Whitlow CT, Baker MD, Morris PP. Imaging and Treatment of Sacral Insufficiency Fractures. Am J Neuroradiol 2010;31:201-10
(3) Denis F, Davis S, Comfort T. Sacral fractures: an important problem. Clin Orthop Relat Res 1988;227:67-81
(4) De Smet AA, Neff JR. Pubic and sacral insufficiency fractures: clinical course and radiologic findings. AJR Am J Roentgenol 1985; 145:601-06