Medical Care of Osteoporotic Pelvic Bone Fracture: The United Kingdom Experience

Editor’s Note: Clinical Geriatrics occasionally presents information on how diseases and/or medical problems are diagnosed and managed in other countries. We hope you will enjoy reading this article from a United Kingdom perspective.

Introduction

Incidence of osteoporotic pelvic fracture is higher than previously expected. The majority of these patients are frail, female, elderly, and have multiple coexisting medical problems. Most osteoporotic pelvic fractures need no surgical intervention and the main focus of management is treating any acute medical problems that may have led to the fall, issues surrounding bone fragility and osteoporosis, falls risk assessment, and facilitation of rehabilitation with safe discharge from the hospital. As a consequence, in the United Kingdom the medical team cares for most of these patients, in particular, care of the elderly physician “geriatricians,” rather than the orthopedic team.

Complications of osteoporotic pelvic fracture include urinary bladder injury in multiple pubic ramus fractures or bleeding due to inferior epigastric artery injury, particularly in those taking oral anticoagulants. While most pubic ramus fractures can be identified on plain x-ray, sacral fractures may not be identified without further imaging (eg, radioisotope bone scan, magnetic resonance imaging [MRI] scan). Since sacral fractures can be associated with sacral nerve root damage, it is vital to keep this association in mind, especially in patients with persistent lower-back pain or in those developing signs and symptoms of cauda equina lesions.

In this article, we will review the epidemiology and managementof osteoporotic pelvic bone fracture, specifically from a United Kingdom perspective.

Epidemiology

The World Health Organization defines osteoporosis as “a progressive, systemic skeletal disease characterised by reduced bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fractures.”¹ The diagnosis of osteoporosis is based on a quantitative assessment of bone mineral density (BMD), usually by dual-energy x-ray absorptiometry (DXA). Osteoporosis is confirmed when the BMD falls 2.5 or more standard deviations below the mean for a young female adult (T-score ≤ -2.5). The femoral neck is used as the reference point.¹ In premenopausal women, men under the age of 50 years, and children, it is recommended that Z-scores of -2.0 or lower (ie, ≥ 2 standard deviations below a normal adult of the same age and sex) are used to make the diagnosis of osteoporosis, rather than comparisons with a young normal adult (a T-score).²

Osteoporosis causes a significant burden on healthcare resources as a result of the fractures that ensue. It is estimated that 1 in 3 adult women will sustain 1 or more osteoporotic fractures in their lifetime.¹ In the United Kingdom, it has been estimated that the annual cost to the National Health Service is more than £1.73 billion.¹ In the United States, the cost of osteoporosis-related fractures to the healthcare system was estimated at $17 billion in 2005.³ It is estimated that there are 12 million men and women in the United States with osteoporosis.⁴ A recent article reviewed the impact of hip fractures in the elderly, highlighting that by 2040, it is estimated that there will be 500,000 hip fractures per year in the United States, and that 75% of these are likely to be in women.⁵

Osteoporotic pelvic fracture is becoming an increasingly important issue for healthcare providers, particularly for those involved in the medical care of the older person. Recent studies have shown a sharp increase in the incidence of pelvic fractures among elderly people, particularly women, who sustain simple falls. Data from Finland showed that the incidence of these fractures has risen from 20 to 95 per 100,000 people between 1970 and 1997.⁶ Patients over age 80 years are at particular risk.⁷ This rise could be attributed to several factors: the increasing awareness of this type of fracture; the growing elderly population; and improvements in radiological imaging technology, which is helping to identify these fractures more easily than before. If this trend were to continue, then the number of patients admitted with pelvic fracture is estimated to triple by the year 2030.⁷ This will have huge financial implications for planning any health service strategy (number of hospital beds, rehabilitation facilities, etc) for the future.

To date, there have not been any prospective studies to assess the outcome of osteoporotic pelvic bone fractures. Most of the evidence that is available is derived from retrospective studies and case reports. However, there are common themes emerging from such studies that help to clarify the scale of the problem and to identify effective ways to deal with it.

In a retrospective study from Edinburgh (United Kingdom), the average age of patients with pelvic fractures was 80 years.⁸ Eighty percent of participants sustained only a simple fall, and, importantly, 16% did not remember falling at all. Eighty percent of these patients who sustained a fall were admitted from their home or warden-controlled flat (sheltered accommodation) and the rest from nursing or residential care facilities. Average length of acute hospital stay was 3 weeks, and 84% of patients required extra community support (home carers) on discharge. This will have major resource implications, and the cost of treatment might become comparable to that for treatment of fractured neck of femur. Inpatient mortality was 7.6%, 1-year mortality was 27%, and only 45% survived at 5 years.⁸ As for outcome, 25% of patients living in the community had to give up their accommodation and were discharged to a nursing or residential home.⁹ In another study, it was estimated that approximately 78% of patients with pelvic fractures were discharged back to their own home. Of those who were discharged home, nearly half needed a long period of rehabilitation in a specialist rehabilitation unit, with mean length of stay approximately 40 days. Only approximately half of the patients were independently mobile after discharge, nearly 40% required walking aids, and 10% were immobile.¹⁰

Anatomy of the Pelvic Bone and Type of Fracture

The pelvis is composed of two iliac bones joined anteriorly at the symphysis pubis and posteriorly with the sacral segment at the sacroiliac joints. The sacrum is composed of five fused segments attached to the lower lumbar spine superiorly and to the coccyx inferiorly.

Pelvic fractures can be classified according to stability. Unstable fractures involve the four ischiopubic rami or the anterior and posterior arches of the pelvic ring. Unstable fractures could potentially be associated with urethral and bladder injury, a complication that clinicians need to be aware of when treating these patients on medical or rehabilitation wards. Concern needs to be raised when such patients develop hematuria, even microscopic, in the context of unstable pelvic ring fractures.

Sacral fractures are classified into three types, depending on which part of the sacrum is affected.¹¹ Zone 1 fractures involve the sacral ala, zone 2 fractures involve the sacral foramina, and zone 3 fractures occur through the body of the sacrum. There is a risk of cauda equina injury in patients with zones 2 and 3 sacral fractures.

There is a high frequency of coexistence of pubic ramus and sacral fractures, which occur together in approximately 78% of cases.¹² While pubic ramus fractures can be identified on plain x-ray, those involving the sacrum usually need further imaging. Clinical suspicion of associated sacral fracture needs to be raised when patients with pubic ramus fractures report persistent back pain or symptoms of a cauda equina lesion, such as fecal or urinary incontinence or neurological leg weakness.

Patients at Risk

The majority of osteoporotic pelvic fractures occur in elderly women after a simple fall. Those with history of osteoporosis or fragility fracture need to be assessed carefully when admitted for falls to exclude pelvic fractures. Patients with rheumatoid arthritis are particularly at increased risk; these patients may have no history of previous trauma.¹³ Patients taking long-term systemic corticosteroids are at risk of all types of fractures, including hip fracture. In a recent study by Kwon et al,¹⁴ 45% of patients who had received radiotherapy treatment for cervical cancer developed pelvic fractures, and the majority had multiple pelvic bones affected.

Other causes of bone fragility increase the risk of fractures, including vitamin D deficiency, Paget’s disease, renal osteodystrophy, and hyperparathyroidism. Patients on hormonal treatment for breast and prostate cancers are at risk for osteoporosis-related fragility fractures, and the number of such patients is increasing.^15-17 Patients with polycystic kidney disease, especially those with grossly enlarged kidneys or liver, may have direct continuous pressure on the pelvic bone, leading to increased bone resorption and subsequent increased risk of pelvic fracture.¹⁸

Experimental studies to assess pelvic bone fracture risk in relation to BMD using axial scan have identified low total BMD at the hip (total BMD) to be strongly associated with increased pelvic bone fracture risk.¹⁹ Finally, pelvic ring instability and increased fracture risk has been reported in patients who have undergone iliac bone harvesting due to instability of the pelvic ring.²⁰

Clinical Assessment

The first step in assessing any elderly patient with a fall is to ensure that no serious underlying bony injury such as hip fracture is missed. Classically, patients with pubic bone fracture are admitted with groin pain after a simple fall. Back pain, as well as groin pain, should raise the suspicion of an associated sacral fracture. Due to lack of awareness of this association, there can be a delay of up to 28 days from the diagnosis of pubic ramus fracture to the identification of an associated sacral fracture.²¹

It is important to have a list of differential diagnoses of the causes of groin pain when assessing an elderly patient who presents with this symptom after a simple fall. Causes of groin pain are as follows:

• Fractured neck of femur
(Note: This needs to be ruled out immediately because of the need for surgical intervention within 24-48 hr of admission. If clinical suspicion is very high despite negative x-ray, then limited MRI scan will confirm the diagnosis.)
• Pubic ramus fracture
• Lumbar spine fracture
• Spinal stenosis
• Paget’s disease
• Referred pain from the knee
• Osteoarthritis of the hip
• Osteonecrosis of the hip

The two most important differential diagnoses in sacral fractures are bony metastases and sacral osteomyelitis.

Specific examination to identify the cause of groin pain includes:

• Range of movement at the hip joint
• Palpation for local spinal tenderness
• Tenderness over the sacral bones to look for associated sacral fracture
• Knee examination
• Full neurological examination of the lower limbs; in particular, looking for any signs of cauda equina lesion, not forgetting to assess perianal sensation and anal tone
• Gait assessment; specifically, whether the patient is able to bear weight or not

It is important for patients with falls to be able to bear weight freely without pain and to ensure that gait assessment is included in the initial examination. Most patients with pelvic fractures will have great difficulty in doing so. This should alert the clinician to request further imaging to exclude pelvic fractures. If the clinician does not assess gait at the time of presentation, diagnosis of pelvic fractures may be delayed for several days.

A systemic review is necessary to identify any occult underlying acute medical problem causing the fall. Most patients with pelvic fractures following a simple fall have underlying osteoporosis, in addition to vitamin D deficiency. A thorough history and physical examination are vital to identify other acute medical problems and to treat them at an early stage, in order to accelerate the patient’s recovery from the associated fracture.

Investigations

Hematology
Raised alkaline phosphatase with otherwise normal liver function tests will raise suspicion of fracture in patients presenting with falls and/or groin pain. Osteoporosis screen including thyroid, liver, and kidney function tests, as well as myeloma screen, should be performed to look for diseases that may mimic osteoporosis (eg, myeloma, osteomalacia), and risk factors for osteoporosis. 25-hydroxyvitamin D (25[OH]D) level measurements are helpful, as the degree of deficiency will determine the method of its correction. Those with severe deficiency may need initial high-dose oral vitamin D to achieve a rapid therapeutic level very early,²² particularly if intravenous bisphosphonate is to be considered (eg, in those with compliance problems, in those with intolerance of oral medication).

Radiological Investigation
Plain x-ray of the pelvis is the usual initial test. A negative x-ray does not rule out a fracture, and a high index of suspicion is needed if patients are still struggling with pain on mobilization. The next step would be radioisotope bone scan, which identifies not only pubic ramus fractures, but also associated sacral or vertebral fractures. MRI scan of the pelvis may be required in cases with inconclusive x-rays of the hip.

Plain x-ray is not sensitive enough to identify sacral bone fractures. Isotope bone scan and MRI are very sensitive, but may be less specific. If metastases or infection are suspected, computed tomography (CT) scan of the sacrum is the most sensitive imaging to demonstrate the fracture lines and to exclude other diagnoses.²³

Similarly, it is important not to overlook sacral fractures by identifying vertebral fractures on plain x-ray of the spine or the finding of spinal stenosis on MRI. There have been reports of patients unnecessarily undergoing spinal surgery when the initial problem was related to unidentified sacral fracture.²⁴

All patients with pelvic fractures will need to have a baseline DXA scan to assess the degree of osteoporosis that will assist in planning treatment and follow-up. If the patient is a postmenopausal female with a fragility fracture, guidelines from the United Kingdom¹ would suggest that you can treat osteoporosis presumptively without actually requiring a DXA scan for diagnosis. However, a baseline DXA scan can be helpful in monitoring response to treatment or progression of disease.

Complications

Sacral Fracture
Patients with pubic ramus fracture who are reporting persistent back pain in addition to their groin pain should have a radioisotope bone scan to clarify if they have an associated sacral fracture. These two fractures coexist in 78% of cases.¹² This is particularly important in patients who show signs of cauda equina lesions. Moreover, patients with pubic ramus as well as sacral fractures have a prolonged course of recovery as compared with those who have isolated pubic ramus fractures.²⁵

Cauda Equina Injury
Patients with sacral fracture specially affecting zones 2 and 3 (defined above) are at risk of cauda equine injury. These patients need to be assessed for any symptoms of neurological leg weakness or sphincter disturbance, including assessment of anal tone and perianal sensation. If there is any suspicion of nerve root involvement, then MRI of the sacral spine and referral to a neurosurgeon should be considered.

Bladder and Urethral Injury
This complication may not be as common as it is in patients with high-impact pelvic injury. However, there are reports of bladder and urethral injury in persons with minimal trauma pelvic fracture, particularly in those with unstable fracture involving multiple pelvic bones.^26,27 Microscopic and frank hematuria should raise the suspicion of such injury with early referral to urology. CT cystography will help to identify any bladder wall rupture.²⁸

Inferior Epigastric Artery Injury
There have been case reports of elderly patients presenting with groin pain after a simple fall who deteriorated rapidly with hypotension and shock.^29,30 Subsequent angiography showed rupture of the inferior epigastric artery by the pubic ramus fracture. This complication needs to be kept in mind, particularly with the increasing number of elderly patients taking oral anticoagulant therapy.

Osteolysis
Several cases of osteolysis of the pelvic bone have been reported. These patients tend to present with persistent pain at the site of the fracture, usually in those who had previously received radiotherapy to the pelvis. The identification of pelvic fracture callus in due course will help to clarify the matter and avoid unnecessary further investigation.³¹

Management

Most osteoporotic pelvic fractures do not require surgical intervention, and one might argue that in the United Kingdom this group of elderly patients with multiple comorbidities are better managed in a specialized “orthogeriatric unit.” Many of these patients will develop acute medical complications, such as respiratory infections, renal failure, acute confusion, and sepsis. Moreover, these specialized units are equipped to address other important issues such as pain control, osteoporosis, vitamin D deficiency, rehabilitation progress, mental health, and falls risk assessment. These units provide the ideal environment for a multidisciplinary approach to rehabilitation, with staff that liaises effectively with community-based services to facilitate discharge. Such units have been proven to be very effective in providing effective perioperative care for patients with fractured neck of femur, and a similar principle could be applied for patients with pelvic fractures.

Medical management of osteoporosis includes the use of bisphosphonates (analogues of inorganic pyrophosphate that inhibit bone resorption), strontium ranelate (not FDA-approved in the U.S.), raloxifene (an estrogen receptor modulator that inhibits bone resorption), or parathyroid hormone peptides (eg, teriparatide).¹ Extensive guidelines for the treatment of osteoporosis in the United States are outlined in the National Osteoporosis Foundation Clinician’s Guide to Prevention and Treatment of Osteoporosis.² Medical management should be considered in postmenopausal women and in men age 50 years or older presenting with a fragility fracture, a T-score of less than or equal to -2.5 on DXA, or a low bone mass on DXA (T-score between -1.0 and -2.5), as well as a 10-year probability of a hip fracture of 3% or greater or a 10-year probability of a major osteoporosis-related fracture of 20% or greater.²

Hospitals should have a clear policy about where to admit patients with osteoporotic pelvic fractures, and orthopedic input should be provided when necessary. The main line of treatment includes:

• Pain control: simple analgesia and opiates if needed
• Treatment of any underlying acute medical issues causing the initial fall
• Monitoring for any acute medical problems developing during the course of rehabilitation, with particular attention to sepsis, delirium, and cardiac, respiratory, and renal problems • Medical management of underlying osteoporosis
• Correction of vitamin D deficiency
• Effective multidisciplinary rehabilitation
• Prevention of thromboembolic complications with prophylactic subcutaneous low-molecular-weight heparin

Conclusion

Osteoporotic pelvic fractures, including sacral insufficiency fractures, are on the rise, particularly with the increasing elderly population. An occult sacral fracture should be suspected in patients with pubic ramus fractures who have associated back pain in addition to groin pain and with symptoms or signs of cauda equina lesions. In the United Kingdom, a dedicated orthogeriatric unit lead by a geriatrician is the best place to care for such frail elderly patients with multiple comorbidities. Due to the scale of the problem, further research is necessary into this type of fracture, with a particular focus on epidemiology, resource utilization, risk factor profile, and clinical outcome.

The authors report no relevant financial relationships.

Dr. Dotchin is Academic Clinical Lecturer in Ageing Medicine/Specialist Registrar in Geriatrics, Institute for Ageing and Health, Campus for Ageing and Vitality, Newcastle University, UK; and Dr. Shanshal is Consultant Physician, Queen Elizabeth Hospital, Gateshead, UK.

References

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