Osteitis pubis

Osteitis pubis is characterized by bony resorption about the symphysis followed by spontaneous resossification ( Fig. 1 ) . The pregnant or postpartum woman has a gradual onset of pubic symphysis pain, followed by rapid progression over the course of a few days, leading to excruciating pain radiating down the inside of both thighs, exacerbated by any movement of the limbs. The prognosis for recovery is generally good, with a self-limited course that lasts from several days to weeks before gradually subsiding .

Osteitis pubis. Plain radiograph of the pelvis revealing a slight widening and small amount of adjacent sclerosis of the symphysis pubis. ( From Scott K, Carek P. Osteitis pubis: a diagnosis for the family physician. J Am Board Fam Pract 1998;11(4):291–5, with permission from the American Board of Family Medicine.)

Occasionally, the course of groin/pubic pain may be quite prolonged and should be treated with initial bed rest followed by ambulation with a walker as tolerated. Anti-inflammatory agents can be given to affected women after parturition. Intrasymphyseal injection of lidocaine and steroid may shorten the duration of symptoms . Ultrasound imaging may identify the pubic symphysis and accurately guide injection .

Acupuncture stimulation may be a valuable treatment to ameliorate pain in the condition of pelvic pain in late pregnancy and postpartum . The application of a pelvic belt may reduce pubic symphyseal pain or sacroiliac pain .

Specific stabilizing exercises for pelvic pain of pregnancy have demonstrated benefit and should be incorporated as well .

Rupture of the symphysis pubis

Rupture of the symphysis pubis, a true rupture of the ligaments supporting the symphysis pubis, is only rarely reported. This is believed to occur as a result of the wedge effect of the forceful descent of the fetal head against the pelvic ring, usually during delivery, creating a separation of approximately 1 cm . Another case series suggested that symphyseal rupture can occur as a result of forceful and excessive abduction of the thighs during labor . Characteristically, there is a sudden pain in the region of the symphysis pubis, sometimes an audible crack, followed by radiation of pain to the back or thighs. A gap may be palpable with associated soft-tissue swelling. Treatment is generally conservative. Initial bed rest in a lateral decubitus position with a pelvic binder is indicated. Progression to weight bearing as tolerated with a walker is appropriate when symptoms permit .

Complications are rare, and subsequent vaginal delivery is possible . In extremely rare circumstances, persistence of symptoms may warrant surgical stabilization with open reduction and internal fixation .

Pelvic dislocation of pregnancy

Severe pelvic dislocation of pregnancy is extremely rare. Cases reported are associated with difficult parturition. Patients sustain simultaneous rupture of the symphysis pubis and sacroiliac joints, with resultant pelvic dislocation. All patients in a series from Boston developed persistent sacroiliac pain after being managed with closed reduction. Based on the evidence, an operative approach should be considered for patients with symphyseal diastasis of 4.0 cm or more .

Epidemiology

The epidemiology of low back pain in pregnancy demonstrates incidence rates of approximately 50% among retrospective reviews . Low back pain rates have been found to increase with advancing maternal age, with a history of back pain during a previous pregnancy, with successive births, with a higher body mass index, and with a history of hypermobility . A recent study by Wang and colleagues demonstrated increased low back pain in younger women. No consistent relationship has been found between rate of back pain with the height of the mother, with the mother’s weight gain, or with the weight of the baby . It is reported that only 32% of women with low back pain during pregnancy report this to their prenatal providers, and only 25% of prenatal care providers recommend a specific treatment for their patients. Nearly 30% of women are forced to stop performing at least one daily activity because of low back pain over the course of their pregnancy .

Low back pain is also reported in 30% to 45% of women in the postpartum period . The main factors associated with development of postpartum back pain are previous episodes of back pain. Risk factors associated with persistent back pain after 24 months seem to be the onset of severe pain early during gestation, the inability to reduce weight to prepregnancy levels, high body mass index, and history of hypermobility .

Previous physical activity decreases the risk of low back pain and pelvic pain during pregnancy . Exercise during the second half of pregnancy significantly reduces the intensity of low back pain .

Etiology

Low back pain during pregnancy has multiple causes, and the relative frequency of these causes has not been fully established. These causes include mechanical strain, pelvic ligamentous laxity, sacroiliac pain, vascular compression, spondylolisthesis, discogenic pain, and hip pathology (discussed later in this article). One popular theory for the cause of nonspecific low back pain of pregnancy posits that the enlarging gravid uterus and accompanying compensatory lumbar lordosis contribute to substantial mechanical strain on the lower back. In addition, the tendency for pelvic rotation is increased as the lumbar lordosis increases. These altered biomechanics, in combination with relaxation of the pelvic and sacroiliac joints under the influence of relaxin, may further increase strain on the pelvis and low back .

Lumbar disk herniations of pregnancy, although relatively uncommon, are estimated to occur in approximately 1 in 10,000 cases of lumbosacral pain of pregnancy . During pregnancy, noncontrast MRI can be performed to identify the pathology. To date, no recognized adverse biological effects of MRI on the developing fetus have been identified, although the long-term effects of MRI on the developing fetus have not been fully evaluated .

Another hypothesis suggests that the vascular system may play an important role in the pathogenesis of back pain during pregnancy. In a 1992 study, Fast and Hertz hypothesize that prolonged time in the supine position leads to obstruction of the vena cava. They further suggest that increased pressure and venous stasis in combination with a decrease in basal oxygen saturation may lead to hypoxemia and compromise the metabolic supply of the neural structures, resulting in pain.

In susceptible women, pregnancy may be a factor for the development of degenerative spondylolisthesis . In women with previously diagnosed spondylolisthesis, no increase in low back pain or increase in slippage during pregnancy was found . As in other individuals with spondylolisthesis, low back pain may be unrelated to the presence of this anatomic finding and may be caused by disk, facet joint, or muscle abnormalities.

History and physical exam

The pregnant woman with low back pain generally reports lumbar, pelvic, or sacroiliac pain aggravated by weight bearing and activity. Sitting, resting, recumbency, and use of a supportive pillow often ameliorate the symptoms. Occasionally, there is a vague accompanying posterior thigh or inguinal radiation of pain into the leg. True nerve root pain is uncommon. The physical examination of the pregnant woman with back pain should begin with a standard neuromuscular exam that includes observation, palpation, range-of-motion tests, tests for muscle imbalances, and a thorough neurological examination. In addition, the examiner should assess posture and degree of lordosis. Occasionally, a “step-off” sign will be appreciated in the lumbar spine and may suggest spondylolisthesis. Tenderness is often present over the sacroiliac joints and lumbar paraspinal muscles. Sacroiliac compression tests, bimanual compression over the iliac crests, and Patrick’s test all may elicit sacroiliac pain. A careful examination of the hip should be performed as well.

Treatment

Most patients with low back pain respond to activity and postural modifications. Scheduled rest with elevation of the feet to flex the hips and decrease the lumbar lordosis helps relieve muscle spasm and acute pain . A regular exercise program before pregnancy reduces the risk for back pain during pregnancy . During pregnancy, exercise may be initiated once the acute pain is controlled. Sitting pelvic-tilt exercises and aquatic exercise have been shown to decrease pain intensity . Exercise to increase strength of the abdominal and back muscles is also recommended .

Lumbar support binders may also provide pain relief ( Fig. 2 ). A recent study looked at women with lower back pain who were at least 20 weeks gestation and who wore a maternity support binder during waking hours for 2 straight weeks. They had significant reduction in mean pain scores and effect of pain on daily activities, including those related to family, house and yard, recreation, exercise, and sleep. The maternity binders were well accepted by the women . Furthermore, the lumbar and abdominal support has not been shown to adversely affect the hemodynamics of the fetus or mother .

Back-A-Line maternity support binder. ( Courtesy of Back-A-Line, Inc., San Francisco, CA; with permission.)

A recent retrospective, observational study of 167 patients with low back and pelvic pain of pregnancy demonstrated improvement in 72% of patients treated with acupuncture administered during the second and third trimesters. No significant adverse effects were noted . In addition, a study by Guthrie and Martin looked at a group of 500 pregnant women with lower back pain and demonstrated that osteopathic manipulative treatment (specific techniques included muscle energy, myofascial release, ligamentous articular strain, high-velocity–low-amplitude thrust) to the lumbar area during the third trimester significantly reduced back pain experienced during labor and delivery, as measured by amount of analgesic medication requested.

A recent survey study from Wang and colleagues found that both providers of prenatal health care and pregnant women in New Haven County are likely to use complementary and alternative treatments for pregnancy-related low back pain. Massage (61.4%), acupuncture (44.6%), relaxation (42.6%), yoga (40.6%), and chiropractic (36.6%) were the most common complementary and alternative medical therapies recommended for low back pain in pregnancy by the providers of prenatal health in that sample.

The medication of choice for pain relief is acetaminophen because antiprostaglandins (aspirin and nonsteroidal anti-inflammatory drugs) are relatively contraindicated in pregnancy because they can cause premature closure of the ductus arteriosis in the fetus if given at or near term. Other medications that the US Food and Drug Administration rates class B (no evidence of risk in humans during pregnancy) may be considered for pain control during pregnancy. These include cyclobenzaprine, oxycodone (if used for short periods not near term), and prednisone.

There is no literature examining the safety or efficacy of epidural steroid injections during pregnancy. In the authors’ clinical experience, interlaminar epidural steroid injections, performed without any fluoroscopic guidance, can be administered safely by an interventional pain specialist with extensive experience in epidural injections in pregnancy. Surgery for lumbar disk herniation during pregnancy with cauda equina syndrome or progressive neurologic deficit can be safely undertaken if clinical circumstances dictate. Brown and Levi report a case series of three pregnant women who were successfully treated this way. Care should be carefully coordinated with the obstetrician.

Introduction

Peripheral nerves are susceptible to injury in the pregnant, laboring, and postpartum woman by several mechanisms: compression, traction, ischemia, and, less commonly, laceration. As would be expected biomechanically, labor and delivery are more likely to compromise the lumbosacral plexus and lower-limb peripheral nerves, whereas activities of daily living and child care, especially those requiring repetitive or prolonged positioning of the upper limb, are associated with upper-limb peripheral nerve injury. Upper-limb neuropathies (eg, median neuropathy at the wrist) can also occur during pregnancy because of peripheral edema.

Mechanisms of peripheral nerve injury

Compression and traction are the most common mechanisms of peripheral nerve entrapment in pregnancy and the puerperium. Compression neuropathies are most common in anatomic locations where excessive pressure can occur (median nerve in the carpal tunnel) or in superficial nerves (common peroneal nerve at the fibular head). The endoneurium, a connective tissue matrix of collagen and fatty tissue, surrounds individual nerve fascicles, absorbing shock and dissipating pressure. Nerves with tightly packed fasciculi and thin endoneurium are more susceptible to compression. Pregnancy-related swelling and prolonged positioning increase compressive forces, resulting in increased prevalence of compression neuropathies in pregnancy and postpartum child-care activities. Labor and delivery are also associated with compressive mononeuropathies and lumbosacral plexopathies . Traction neuropathies result when the stretch applied to the nerve exceeds the elastic capacity of the neural and connective tissue. Intrinsic nerve characteristics, such as the amount of perineurium, the lamellated sheaths of perineural cells, and collagen fibrils, have been implicated in differential risk of traction injury . A combination of compression and stretch may result in decreased perineural blood flow and ischemic injury. Less severe injuries that cause focal demyelination and conduction block are the most common type in pregnancy and the puerperium. These neuropathies are generally short-lived and have a good recovery .

Carpal tunnel syndrome (median neuropathy at the wrist)

Hand pain is the second most frequent musculoskeletal symptom of pregnancy, with carpal tunnel syndrome (CTS) frequently the cause . The median nerve can be entrapped at the wrist in the enclosed space formed by the carpal bones and the overlying transverse carpal ligament. CTS typically presents with pain and paresthesias in the first three digits of the hand, often bilaterally, and is most frequently diagnosed during the third trimester . The rate of CTS varies from 2% to 25% in pregnant women . The pain can worsen at night or during the day with repetitive wrist flexion or extension.

Peripheral edema has been implicated in pregnancy-related CTS and is most common in older, primiparous women . Prolactin and fluid retention coupled with prolonged, awkward positioning of the wrist and hand may cause CTS related to nursing. The symptoms of CTS frequently resolve within days to weeks after labor and delivery. Forty-three percent to 95% of women have resolution of symptoms within 2 weeks postpartum . In one study, women with onset of CTS symptoms early during pregnancy had prolonged recovery time after delivery . Nonsurgical management of CTS is appropriate in pregnant women because most patients obtain relief after delivery. In pregnant women symptomatic enough to require treatment, splinting of the wrist in a neutral position is recommended. More than 80% of women had good relief of symptoms using thermoplastic night splints for 2 weeks . Serial electrophysiologic studies done before and after splinting in one case study demonstrated rapid improvement in physiologic measures, mirroring clinical improvement . Education on correct positioning of the hand and wrist for occupational and child-care activities should be provided to women with CTS during and after pregnancy. Steroid injections are useful in patients with recalcitrant symptoms . Infrequently, surgery is indicated during pregnancy or the postpartum period for patients with ongoing severe symptomatology and positive electrodiagnostic studies .

Meralgia paresthetica (lateral femoral cutaneous neuropathy)

The lateral femoral cutaneous nerve is a pure sensory nerve supplying sensation to the anterolateral thigh. It passes slightly medial and inferior to the anterior superior iliac spine after exiting the pelvis by traveling under the inguinal ligament. Injury to the nerve causes burning, pain, or numbness in the region of innervation, referred to as meralgia paresthetica syndrome. Pregnancy, along with obesity, diabetes mellitus, trauma, belt pressure, and anatomic variation, is a risk factor for meralgia paresthetica . One recent study found that pregnant women had 12 times the likelihood of meralgia paresthetica compared with nonpregnant patients in a primary-care setting . Lateral femoral cutaneous neuropathy was the most common finding in a prospective study of postpartum lumbosacral spine and lower-limb nerve injuries resulting from labor and delivery . Cesarean delivery may infrequently lead to meralgia paresthetica from a wide incision, stretching, or retractor placement, although the prevalence does not vary substantially with method of delivery . As with CTS, pregnancy-related meralgia paresthetica syndrome typically resolves after delivery. The diagnosis is typically clinical; the nerve conduction study of the lateral femoral cutaneous nerve can be difficult to obtain, even in healthy, asymptomatic individuals. Pregnant patients are advised not wear clothes that fit tightly along the hips and to avoid as much as possible carrying older children on the ipsilateral hip. Several investigators postulate that intrapartum nerve injury can be reduced by attention to laboring practices . Consideration of frequent position changes for laboring, with avoidance of prolonged hip flexion, may reduce compression on the lateral femoral nerve. In addition, shortening pushing time by allowing the fetus to descend into the perineum without active maternal pushing may reduce nerve compression or traction.

Femoral neuropathy and other intrapartum maternal nerve injuries

The incidence of lumbosacral spine and lower-limb nerve injuries related to labor and delivery varies in studies, depending on sample size and study methodology. A retrospective study using codes for nerve injury from the International Classification of Diseases, Ninth Edition, examined charts over 16 years for 140,000 women and found 0.08% incidence of nerve injury . The investigators concluded that improvements in modern obstetric practice might be responsible for a reduction in nerve injury rates of almost 5% since the turn of the century . A more recent prospective study of 6000 women who delivered in a 1-year period found an almost 1% (0.92%) rate of injury . Injury rate was not associated with obstetric anesthesia but rather nulliparity and prolonged pushing. Many studies are limited by lack of electromyographic documentation because the injuries are frequently of limited duration and new mothers may not follow up for an electrodiagnostic study before symptom resolution. Most nerve injuries resolve over weeks to months.

Femoral neuropathy has been documented as a consequence of labor and delivery. During a prolonged second stage of labor, compression of the femoral nerve under the inguinal ligament may occur. Stretch or ischemia of the intrapelvic, poorly vascularized portion of the femoral nerve may be another mechanism of injury, as the femoral nerve does not descend through the true pelvis . However, in cases in which the iliopsoas muscle, along with the quadriceps, is found to be weak, the lesion may be proximal to the inguinal ligament, where branches to the iliopsoas arise . Femoral neuropathy can result in significant functional impairment, particularly in ascending and descending stairs, walking, and transferring from sitting to standing. Physical therapy evaluation and assistive-device training is mandatory before hospital discharge. Treatment is supportive, and prognosis is good. Demyelinating lesions typically recover in 6 months or less .

Lumbosacral plexopathies

Lumbosacral plexopathies resulting in proximal or distal lower-limb weakness can occur. Plexus-associated foot drop can result from compression of the peroneal division of the sciatic nerve in the pelvis or compression of the common peroneal nerve at the head of the fibula . Common peroneal nerve compression at the fibular head was documented in laboring women both from hand placement and squatting . Obturator nerve palsies have been described as related to labor and delivery. The nerve crosses the pelvic brim and may be compressed by the descending fetal head or instrumentation used for fetal evacuation .