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RFS – Clinical Vignette

Radicular Pain After Hip Disarticulation

A Clinical Vignette

Philip, Kemly MD, PhD, MBE; Sambasivan, Ajai MD

Author Information
American Journal of Physical Medicine & Rehabilitation: June 2021 - Volume 100 - Issue 6 - p e76-e79
doi: 10.1097/PHM.0000000000001585

Abstract

HISTORY AND PHYSICAL EXAMINATION

A 36-yr-old man with a history of industrial accident 3 yrs before resulting in traumatic left hip disarticulation, pubic symphysis, and right sacroiliac joint (SIJ) fractures status after percutaneous screw fixation presented with a 3-yr history of left-sided lower back pain (LBP) (Fig. 1A). He followed with an amputee specialist for phantom limb pain (PLP) but now described a distinct, gradually worsening, moderate electric and burning pain that was exacerbated with prolonged sitting, lying down, and daily activities. The left-sided LBP referred down the residual limb to where he felt his foot lay. Physical therapy, focusing on core and right lower limb muscle strengthening, in addition to oral medications including pregabalin, amitriptyline, and methadone, provided modest relief. On physical examination, he had tenderness to palpation over the left posterior superior iliac spine and a hypertrophic-appearing gluteus surgical scar. Right lower limb strength was 5 of 5 on manual muscle testing. Prone back extension elicited radicular pain from his left lower back down the amputated limb. Although the patient had a prosthesis, he preferred ambulation with forearm crutches, displaying a left lateral truncal lean associated with right lower limb hip vaulting and circumduction.

F1
FIGURE 1:
Pelvis x-ray (A) after a traumatic industrial accident showed a screw fixation of the right SIJ at S1 and the bilateral SIJ at S2 with evidence of left sacral fractures, right inferior and superior pubic ramus fractures, left L5 transverse process fracture, sacrococcygeal dislocation, pubic symphysis diastasis, and left hip disarticulation. CT imaging demonstrated (B) osteophytes (solid arrowheads) surrounding the bilateral SIJs with (C) decreased left L5–S1 foraminal space (dashed circle).

What differential diagnoses are considered in a patient with lower limb amputation (LLA), now with residual limb lower back and leg pain?

DIFFERENTIAL DIAGNOSIS

The differential diagnosis includes myofascial pain or pathology from the pelvis, hip, or lumbosacral spine including discogenic pain, facet arthropathy, SIJ dysfunction, tumor, or lumbar radicular syndrome. Additional causes after LLA include PLP, osteomyelitis, heterotopic ossificans, neuroma, inflammation, or terminal bone overgrowth.1

What physical examination maneuvers would you perform to elicit radicular pain and how might these be modified in a patient with LLA?

Physical examination assessment for radiculopathy includes noting atrophy, gait abnormalities, spine and hip range of motion, bony tenderness, changes in sensation or strength along a dermatome or myotome, and the presence of other hip or SIJ provocative maneuvers (Table 1). The physical examination was obviously limited in this case because of amputation of the affected limb; however, the patient demonstrated antalgia and truncal lean with gait aid, along with radicular pain with prone back extension, coinciding with clinical features of radiculopathy one might also observe in a patient without LLA (Table 1).

TABLE 1 - Physical examination considerations in lumbosacral radiculopathy
Inspection
Atrophy of muscles in a myotomal distribution
Gait deficits: antalgic posturing, truncal leana , fatigability, reproduction of symptoms of pain or weakness
Range of Motion
Lumbar lateral bendinga : leaning opposite of antalgic posturing exacerbates radicular irritation
Sensation
Light touch/pinprick: evaluate for sensory loss or paresthesias in a dermatomal distribution (L2–S2)
(Note: Evaluate for bowel or bladder symptoms/incontinence to assess possible S3–S4 involvement)
Strength/Muscle Stretch Reflexes
Nerve Root Motor Weakness Diminished/Absent Muscle Stretch Reflexes b
L2, L3  HF, adduction  –
L4  KE  Patellar
L5  DF of great toe and foot,  hip abduction  Medial hamstring
S1  PF of great toe and foot,  ankle eversion  Achilles
Provocative Maneuvers c
Straight leg raise (SLR): KE followed by HF when supine, exacerbated with ADF
Bechterew: seated SLR
Crossed SLR: KE followed by HF of the contralateral limb
Slump: CF when seated exacerbates radicular symptoms with passive KE and ADF, relieved with CE
Lasegue: HF followed by KE
Sicard: SLR followed by great toe DF
Kempa : Thoracolumbar lateral bending with extension and rotation
Femoral nerve stretch: KF followed by HE when prone
a Physical examination assessment and findings noted in this case of a patient with hip disarticulation.
b Rule out upper motor neuron signs including Babinski and Clonus.
c These maneuvers provoke nerve root tension. A positive test reproduces radicular symptoms in the affected limb.
HF indicates hip flexion; KE, knee extension; DF, dorsiflexion; PF, plantar flexion; ADF, ankle dorsiflexion; CF, cervical flexion; CE, cervical extension; KF, knee flexion; HE, hip extension.

Given limitations in physical examination in LLA, what imaging can assist with the diagnosis of lower back and radicular leg pain?

DIAGNOSTIC RESULTS

Lumbar spine computed tomography (CT) showed bilateral SIJ osteophytes with reduced left L4–L5 foraminal space (Figs. 1B and C). On presentation to the clinic, a noncontrast lumbar spine magnetic resonance imaging (MRI) with metal suppression was obtained to delineate changes related to inflammation, presence of absence of fluid, bony lesions, or other structural abnormalities that can contribute to radicular pain after LLA. MRI demonstrated a transitional type L5 vertebral body with bridging osteophytes on the left abutting the extraforaminal L4 and L5 nerves, degenerative disc disease, and facet arthropathy at L5–S1 with mild bilateral foraminal stenosis and atrophy of the left psoas and iliacus muscle (Figs. 2AC).

F2
FIGURE 2:
MRI without contrast showed transitional type L5 vertebral body with bridging osteophytes (A) (sagittal T2 image: solid circle) on the left, about the extraforaminal L4 (B) (axial T2 image: arrowhead) and L5 nerves (C) (axial T2 image: dashed circle) with left psoas and iliacus muscle atrophy.

What would be your next step in management given clinical findings of left-sided LBP and imaging findings of bilateral SIJ and degenerative disc, facet arthropathy, and osteophyte complex causing lumbosacral nerve root compression?

DIAGNOSIS AND MANAGEMENT

Given posterior superior iliac spine tenderness and bilateral SIJ osteophytes on CT, the patient first received a fluoroscopically guided left SIJ injection with 40 mg of triamcinolone, which led to mild improvement as evidenced by his decreased narcotic medication intake. However, his pain persisted, which prompted further imaging with MRI. Two months later, the patient received a fluoroscopically guided left L4–L5 transforaminal epidural steroid injection (ESI) via an infraneural approach with 10 mg of dexamethasone, which led to 50% improvement in his LBP referring down his left lower limb. A repeat L4–5 transforaminal ESI with additional L5–S1 level was performed for persistent symptoms. Thereafter, he reported further 50% improvement in left-sided radicular pain. This patient was ultimately diagnosed with left-sided L4–L5 lumbosacral phantom radiculopathy owing to bridging osteophyte complex with secondary SIJ dysfunction.

Three months since the above interventions, he has self-discontinued amitriptyline, self-weaned pregabalin, and continues methadone for PLP. He reported near resolution of phantom radicular pain, although he reported mild focal LBP exacerbated with extension. Left gluteal scar entrapment and facet arthropathy may contribute to his LBP; however, further procedures were deferred given his significant improvement in pain as evidenced by decreasing pharmacologic requirements and improved function.

DISCUSSION

This clinical vignette represents a rare case of phantom lumbar radiculopathy in a patient with hip disarticulation. Lower back and referred lower limb pain affects 50% to 80% of patients with LLA.2,3 First described in 1957, phantom radiculopathy refers to radicular symptoms among patients with amputations due to mechanical or inflammatory nerve root compression or irritation, presenting as pain or paresthesias, following the distribution of the involved nerve root.4,5 Phantom radiculopathy can present with PLP, phantom sensation, or residual limb pain, making its diagnosis difficult.4,6 PLP, or the perception of pain in the amputated leg, affects 40% to 90% of persons with amputations. Phantom sensation refers to the nonpainful perception that the amputated limb remains, whereas residual limb pain refers to amputation site pain.7,8 Review of the cases described suggests that affected patients present with radicular pain, as early as 7 mos or as late as 40 yrs after amputation, often because of disc herniation at the L4–L5 or L5–S1 level.4,9–11 This case is unique in that this patient’s phantom radiculopathy was secondary to extraforaminal nerve root compression by an osteophyte complex as compared with previously described cases.4,9,10,12,13

Neurologic examination, nerve conduction studies, or electromyography of the affected limb in patients with amputation and radiculopathy is limited as one cannot assess for deficits in a dermatomal or myotomal pattern (Table 1). These limitations in examination and diagnostic tests highlight further the importance of imaging in patients with radicular pain after LLA (Table 2). Although the patient had SIJ osteophytes bilaterally, sacroiliac steroid injection only provided modest relief for a short period. MRI aids, with greater sensitivity, in identifying structural causes of LBP that may be contributing to nerve root impingement among patients with LLA and trauma affecting multiple lumbopelvic joints.9 Workup for another pain generator contributing to SIJ dysfunction led to obtaining this additional imaging, which revealed left L4–L5 foraminal stenosis due to disc osteophyte complex causing lumbosacral radiculopathy.

TABLE 2 - Overview of diagnostic evaluation and management in lumbosacral radiculopathy
DIAGNOSTICS:
 IMAGING
   Plain radiographs
   Can evaluate for spondylolysis, spondylolisthesis, malalignment, instability, malignancy, infection, fracture, inflammatory spondyloarthropathy, degenerative contributing to spinal pain or nerve root impingement. Limited evaluation of soft tissue structures however including disc, nerves, muscles, or ligaments. Lacks specificity.
   MRI (diagnostic gold standard)
   High sensitivity for disc and soft tissue abnormalities. No radiation exposure as with CT. Contrast assists with identifying malignancy or infection.
   CT myelogram
   Superior visualization of cortical bone. Less expensive than MRI. Valuable for patients who are unable to obtain MRI because of contraindications such as pacemaker or in situations where metal can cause MRI artifact. Intrathecal contrast aids in visualizing thecal sac, spinal nerves, or spinal cord.
   Selective nerve root block
   Fluoroscopically guided delivery of low-volume anesthetic to a selective nerve root to determine its role as a pain generator (diagnostic and therapeutic)
 ELECTRODIAGNOSTICS
   Nerve conduction studies
   Sensory studies often normal as lesion is proximal to the dorsal root ganglion
   Electromyography
   May see abnormal activity in muscle groups innervated by the common affected nerve root including paraspinal musculature. Absent H reflex with S1 radiculopathy.
MANAGEMENT:
 PHYSICAL THERAPY
   Stretching to improve flexibility and strengthening to improve the stability of core musculature including spinal stabilizers, scapular, abdominal, pelvic, and lower limb muscles
   Manual therapy, flexion or extension-based (i.e., McKenzie) exercise program, transcutaneous electrical nerve stimulation, thermal modalities, mechanical traction, acupuncture
 MEDICATIONS
   Nonsteroidal anti-inflammatory drugs (topical or oral), acetaminophen, or opioids for severe pain as needed
   Short course of oral corticosteroids (acute flare)
   Neuropathic pain medications including neuroleptics, gabapentinoids, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, or opioids
 NONSURGICAL INTERVENTIONS
   Fluoroscopically guided interlaminar or transforaminal epidural steroid injection
 SURGICAL INTERVENTIONS
   Reserved for patients who do not improve with the above conservative measures
   (Micro) discectomy ± (hemi) laminectomy (open vs. minimally invasive)

LBP in patients with amputations is often multifactorial, as evidenced by degenerative disease secondary to age or trauma affects multiple joints. In this patient, the presence of the transitional vertebrae and disc osteophyte complex at left L4–L5 disc space likely contributed to altered biomechanics, which were exacerbated after a traumatic injury causing hip disarticulation. Patients with amputations are more likely to experience asymmetries of joint movement, muscle morphology, and recruitment contributing to compensatory lumbopelvic and hip changes that cause instability and subsequent LBP.2,3 These asymmetries may be exacerbated by lower limb prosthesis or assistive gait device such as the patient in this case.3

Previous treatment of phantom radiculopathy emphasized surgical management, including laminectomy with discectomy of the affected segment9 (Table 2). Recently, fluoroscopically guided interlaminar or transforaminal ESI is used for patients with radicular pain refractory to conservative techniques.9,13,14 ESI at two levels provided the most benefit for this patient, emphasizing the diagnostic and therapeutic benefit of ESI in radicular pain. However, a comprehensive rehabilitation program that includes physical therapy or other modalities such as transcutaneous electrical nerve stimulation or soft tissue mobilization is important. Therapy should focus on improving flexibility and stability of the core musculature with the goal of improving range of motion, postural stability, and muscle activation, thereby decreasing pain.15

PLP in this patient remained, although the radicular pain resolved after multilevel transforaminal ESI; this supports the notion that pain related to degenerative disease or changes in biomechanics may differ from PLP pathogenesis.7 Pharmacologic management for radiculopathy often includes anti-inflammatory medications to decrease nociceptive or neuropathic pain from neural irritation, including neuroleptics, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, or opioids16 (Table 2). This patient successfully weaned off the tricyclic antidepressant, is in the process of titrating off the neuroleptic, and continues on methadone alone after intervention. Although robust clinical trials are needed, methadone is considered a neuropathic pain treatment because of its unique properties of inhibiting norepinephrine and serotonin and ability to bind the N-methyl d-aspartate and μ-opioid receptors.17,18 Moreover, a multimodal approach of ESI, pharmacologic management, and physical therapy can optimally treat lumbosacral radiculopathy in patients with or without LLA.

CONCLUSIONS

Nonspecific LBP is as disabling as PLP in patients with LLA.3 Identifying radiculopathy among patients with amputations is challenging owing to varied clinical presentations. The few cases of phantom radiculopathy described are due to disc herniation; however, this is the first case report of nerve root impingement secondary to bony osteophyte complex. Although rare, suspicion should remain for radiculopathy superimposed on PLP as fluoroscopically guided ESI can provide significant relief improving quality of life. This study conforms to all CARE guidelines and reports the required information accordingly (see Supplemental Checklist, Supplemental Digital Content 1, https://links.lww.com/PHM/B123).

REFERENCES

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Keywords:

Phantom Limb Pain; Radiculopathy; Magnetic Resonance Imaging; Intervertebral Disc; Osteophyte; Epidural Injections

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