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Pseudoarthrosis is a common complication following fusion operations. It can be found in both instrumented and noninstrumented fusions but more commonly occurs following noninstrumented fusion. Pseudoarthrosis is defined as symptomatic nonunion after 1 year of a fusion surgery. The symptoms can vary from mechanical back pain, radicular pain, or focal deformity due to construct failure. Pseudoarthrosis can also be identified radiographically in asymptomatic patients. Additionally, the rate of pseudoarthrosis also varies depending on the number of fused levels. There are known risk factors that increase the risk of pseudoarthrosis and include osteoporosis, smoking, malnutrition, rheumatoid arthritis, age, radiation therapy, and the use of immunosuppressants. Pseudoarthrosis can also lead to failure at the bone-metal interface causing haloing of the pedicle as well as hardware failure. For cases of lumbar spinal pseudoarthrosis requiring reoperation, fusion adjuncts such as bone morphogenetic protein have been found to increase rate of fusion. Additionally, reduction of the modifiable risk factors predisposing to pseudoarthrosis should be attempted to improve the likelihood of fusion following revision.
Chief complaint: back pain and leg pain
History of present illness: A 29-year-old male presents with a history of back pain and left leg numbness. He underwent a L5-S1 decompression and fusion at that time. He had improvement of the leg pain but no change in his back pain. He underwent revision a year later with a spinous process device to help his back pain. Immediately postoperatively, he had pain in L5 distribution down his left leg. He presented with back pain and burning leg pain and imaging was done ( Fig. 11.1 ).
Medications: hydrocodone, tizanidine
Allergies: no known drug allergies
Past medical and surgical history: L5-S1 fusion x 2
Family history: noncontributory
Social history: engineer, no smoking history, occasional alcohol
Physical examination: awake, alert, and oriented to person, place, and time; cranial nerves II–XII intact; bilateral deltoids/biceps/triceps 5/5; interossei 5/5; iliopsoas/knee flexion/knee extension/dorsi, and plantar flexion 5/5
Reflexes: 2+ in bilateral biceps/triceps/brachioradialis; 2+ in bilateral patella/ankle; no clonus or Babinski; negative Hoffman; sensation intact to light touch
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Preoperative | ||||
Additional tests requested |
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None | Flexion-extension lumbar x-rays |
Surgical approach selected | L5-S1 TLIF |
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If convinced symptoms are due to the pseudoarthrosis, L5-S1 MIS posterolateral fusion |
Goal of surgery | Stabilize spine | Stabilize spine, decompress foramina | Stabilize spine, decompress left L5-S1 nerve roots | Stabilize spine, treat pseudoarthrosis |
Perioperative | ||||
Positioning | Prone, no pins |
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Prone, no pins |
Surgical equipment | Fluoroscopy |
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Fluoroscopy |
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Medications | None | None | None | None |
Anatomical considerations | Dura, nerve root | Abdominal viscera, great vessels, segmental radicular artery | Common iliac vessels namely left common iliac vein, posterior annular defect, left L5-S1 nerve roots | Thecal sac, spinal nerves, pedicles |
Complications feared with approach chosen | Dural tear, CSF leak | Lumbar plexus injury, durotomy, end plate fracture, psoas weakness, retroperitoneal hematoma | Persistent left leg pain, nerve injury, infection | Retrograde ejaculation with ALIF, CSF leak, nerve root injury |
Intraoperative | ||||
Anesthesia | General | General | General | General |
Exposure | L5-S1 |
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L5-S1 |
Levels decompressed | L5-S1 |
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L5-S1 |
Levels fused | L5-S1 |
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L5-S1 |
Surgical narrative | Position prone, posterior midline incision, subperiosteal dissection, removal of interspinous implant, decortication of the posterolateral elements, pedicle screw insertion at L5-S1, fascetectomy and transforaminal discectomy, removal of loose interbody cage, good debridement of the disc space and remove all fibrous tissue until bleeding cancellous bone seen, insertion of new interbody cage filled with bone graft, gentle compression over pedicle screws to stabilize cage, insertion of bone graft in the posterolateral gutter to achieve 360-degree fusion, closure of wound in layers |
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Position prone, place percutaneous dynamic reference frame, use navigated probe to create two separate 1-inch incisions over L5 and S1 pedicle screw entry sites, dissect through muscle and fascia and using the bovie, expose L5 transverse process and sacral ala using microscope bilaterally, harvest iliac crest autograft, decorticate L5 transverse process/facet complex/sacral ala, place autograft bone over it, place navigated percutaneous pedicle screws, confirm accuracy with O-arm, lock rods, standard closure |
Complication avoidance | Good debridement of disc space, gentle compression over pedicles to compress screws, attempt to achieve 360-degree fusion | Mild flexion of left hip to relax left psoas, be aware of nerves under internal oblique muscle, avoid extended muscular dissections, use anatomical corridors around disc with anterior border of psoas and left lateral border of aorta or left iliac artery with minimal retraction of psoas not beyond coronal plane to avoid injury to genitofemoral nerve | Two-staged approach, ligate medial branches off of left iliac vein, ligate median sacral vessels, remove lower portion of L5 and upper portion of S1 to allow removal of TLIF cage, place cage that distracts to provide indirect decompression, standard closure, BMP | Surgical navigation, minimally invasive approach, iliac crest autograft |
Postoperative | ||||
Admission | Intermediate care | Floor | Floor | Floor |
Postoperative complications feared | CSF leak, wound infection | End plate fracture, psoas weakness, injury to segmental radicular artery, nerve root injury, major vessel injury | Persistent left leg pain, nerve injury, infection | Screw misplacement, pseudoarthrosis |
Anticipated length of stay | 2 days | 1–3 days | 3–4 days | 3 days |
Follow-up testing | L-spine x-rays 2 months, 6 months, 1 year after surgery |
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Bracing | None | None | None | LSO brace for 3 months |
Follow-up visits | 2 weeks, 2 months, 6 months, 1 year after surgery | 10 days, 1 month, every 3 months until fusion after surgery | 6 weeks, 3 months, 6 months, 12 months after surgery | 2 weeks, 6 weeks, 3 months, 6 months, 1 year, 2 years after surgery |
Pseudoarthrosis
Discitis
Osteomyelitis
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