Musculoskeletal Intervention

Indications

The objective of PMSB is to obtain a sufficient volume of tissue, representative of the underlying disease, with minimum risk to the patient.

Percutaneous bone biopsy is performed whenever pathologic, bacteriologic, or biologic examinations are required for definitive diagnosis or treatment.

Determination of whether a metastasis is present is the most frequent indication for which a bone biopsy is performed. Positron emission tomography (PET) CT is able to establish the presence of hypermetabolic lesions suggestive of metastasis with increasing accuracy, often obviating the need for biopsy. However, in certain equivocal cases, tissue diagnosis is essential to prove the metastatic origin of the lesion before commencement of treatment or to identify the primary tumor. In certain situations, such as breast cancer, a biopsy may provide information regarding the hormonal sensitivity of the lesion, which has direct therapeutic implications. For primary bone tumors, biopsy is not indicated if complete surgical excision is planned. However, a biopsy can be performed if doubt persists as to the nature of the lesion or if the histology will change therapy.

Infectious lesions (osteitis, septic arthritis, and discitis) are another indication for PMSB, which is used to discover the causative organism.

Contraindications

Bleeding diatheses, biopsies of inaccessible sites (e.g., odontoid process, anterior arch of C1), and soft tissue infection with high risk of contamination of bone are known contraindications for PMSB.

All diagnostic imaging modalities should be reviewed before proceeding to biopsy to avoid unnecessary procedures and afford maximum safety benefit to the patient. The risk of tumor seeding should be considered, especially for sarcomas, and the biopsy trajectory should be planned with the surgeon so that the biopsy tract can be resected with the tumor.

Tools

Soft tissue and lytic lesions without ossification are directly biopsied using a 14- to 18-gauge coaxial biopsy gun. We use the semiautomated side notch cutting Temno needle, which allows for manual advancement of the trocar, followed by automated firing of the outer cannula. We perform a CT scan after the deployment of the trocar but before firing of the outer cannula to allow for accurate positioning of the needle and to prevent complications caused by inadvertent biopsy of nearby structures.

In cases of mild ossification, lesions surrounded by minimal cortex, and spinal biopsies, we use a 14-gauge Ostycut bone biopsy needle (Ostycut, Angiomed/Bard, Karlsruhe, Germany). Penetration of the cortex is performed using a surgical hammer. For primary bone tumors or lymphoma with mild sclerosis, we use an 8-gauge trephine needle (Laredo type).

In cases of dense ossification or osteoblastic metastasis, or if dense cortical bone needs to be penetrated, drilling is necessary. We use a 2-mm diameter hand drill or a 14-gauge Bonopty Penetration set (Radi Medical Systems, Uppsala, Sweden).

Technique

A CT scan is performed to localize the lesion precisely. The entry point and the pathway are determined by CT, such that the shortest route from skin to tumor is selected, avoiding neural, vascular, and visceral structures. The patient is positioned prone, supine, or oblique. In cases of spine and disc biopsy, a combination of CT and fluoroscopy is used.

Bone biopsy is usually performed under local anesthesia. Neuroleptanalgesia may be necessary for painful lesions. General anesthesia is used for children.

After sterile draping, the biopsy trajectory is anesthetized with 1% lidocaine from skin to periosteum using a 22-gauge spinal needle. This needle is then repositioned at the soft tissue tumor interface and a confirmatory scan performed. The biopsy needle is then inserted parallel to the spinal needle using the tandem needle technique. In cases of bone biopsy wherein cortical penetration is required, a surgical hammer may be required to tap the needle into position. Frequent scans are performed to check for correct needle trajectory because once the needle has entered the bone it is very difficult to change direction. The use of fluoroscopy allows for real-time monitoring of needle progression. A combination of CT and fluoroscopy allows for rapid and safe performance of the procedure. Once the needle is within the lesion and the position is confirmed with CT, sampling is performed.

For histopathologic examination, the specimen is fixed in 10% formalin. If bacteriologic analysis is necessary, the specimens are not fixed and are sent for culture in normal saline. Single-use needles are preferred for biopsies.

On completion of the biopsy, the needle is removed and compression applied. A completion CT through the biopsy site is done to rule out hemorrhage.

• Peripheral long bone: The approach has to be orthogonal to the bone cortex, which avoids the needle tip slipping off the cortex. The approach must avoid tendons as well as nerves, vessels, and visceral and articular structures.

• Flat bones (scapula, ribs, sternum, and skull): An oblique approach using a 30- to 60-degree angle is recommended. This approach is a compromise between the tangential approach, which avoids damage to underlying structures, and the orthogonal approach, which avoids slippage of the needle tip ( Fig. 24-1 ).

  

• Pelvic girdle: A posterior approach is used to avoid the sacral canal and nerves.

• Vertebral body biopsy: Different approach routes can be selected depending on the vertebral level biopsied: the anterolateral route is used for the cervical level; the transpedicular or intercostovertebral route for the thoracic level; and the posterolateral or transpedicular route for the lumbar level ( Box 24-2 ).

  Box 24-2

  Percutaneous Musculoskeletal Biopsy

  • An orthogonal approach is used for peripheral long bones

  • An oblique (30- to 60-degree) approach is used for flat bones

  • An anterolateral approach is used for the cervical vertebrae

  • A transpendicular or intercostovertebral approach is used for the thoracic vertebrae

  • A posterolateral or transpendicular approach is used for the lumbar vertebrae

  • Overall accuracy of computed tomography–guided PMSB varies from 74% to 96%

• For the neural posterior arch, a tangential approach is used to avoid damage to underlying neural structures.

• Vertebral disc biopsy: As for vertebral biopsies, the approach changes depending on the level where the biopsy is performed. For the lumbar level, a transforaminal route using the “Scotty dog” technique is used to gain access to the disc ( Fig. 24-2 ). At the thoracic level, the intercostotransverse route is used with the needle advanced in the direction of the fluoroscopic beam, which is directed 35 degrees from the patient’s sagittal plane ( Fig. 24-3 ).

  
  

Complications

Complications are rare following image-guided bone biopsies with an incidence of up to 2%.

The major complication is infection. Strict sterility should be maintained throughout the intervention. In immunocompromised patients, the biopsy should be done under antibiotic coverage. Other reported complications are hematoma, reflex sympathetic dystrophy, neural and vascular injuries, and pneumothorax following biopsies in the thorax. The risk of tumor seeding is rare but real. Hence, it is absolutely necessary in patients with primary bone tumors to choose the needle trajectory in consultation with the surgeon.

Murphy and colleagues, in a large review of 9500 percutaneous skeletal biopsies, identified 22 complications (0.2%). They reported nine pneumothoraces, three cases of meningitis, and five spinal cord injuries. Serious neurologic injury occurred in 0.08% of procedures. Death occurred in 0.02%.

In our experience, we observed only three complications, all paravertebral hematomas: Two cases resolved spontaneously; the other was caused by needle tip breakage in cortical bone. We believe that the low complication rate is related to the systematic use of CT and/or dual guidance.

Results

The overall diagnostic accuracy of CT-guided biopsies ranges from 74% to 96%. However, diagnostic accuracy of CT-guided biopsies for spinal lesions and for infectious etiology is much lower.

In our department, 620 percutaneous musculoskeletal biopsies were performed on an outpatient basis. There were 63% female and 37% male patients, with a mean age of 58 years (range 2-87 years). The distribution of lesions was vertebral 68%, pelvic girdle 17%, and peripheral long bones 15%. Of the biopsied lesions, 55% were lytic, 24% were sclerotic or mixed, and 21% were vertebral compression fractures. In the spine the distribution of lesions was as follows: cervical 5%, thoracic 28%, lumbar 55%, and sacrum 12%.

We found a specificity of 100%, sensitivity of 93.9%, positive predictive value of 100%, and negative predictive value of 87.5%.

Indications

Intraarticular injection of steroids is performed in patients in whom “diagnostic blocks” prove that the facet joints are the source of back pain.

Technique

Facet joint injection in the lumbar spine is a simple and safe procedure that can be performed on an outpatient basis under CT or fluoroscopic control. Facet joint degenerative disease usually affects multiple levels on both sides, and thus multilevel facet joint injections (L3-L4, L4-L5, and L5-S1) may be necessary.

The patient is placed in a prone position on the CT or fluoroscopy table. A CT scan of the affected level is used to determine the needle pathway and the entry point. A 22-gauge needle is advanced vertically into each joint ( Fig. 24-4 ). Once the needle is in the joint, a solution of cortivazol and lidocaine 1% is injected into the joint. Cortivazol is provided in 1.5 mL of solution (containing 3.75 mg of long-acting steroid) and with the addition of 1.5 mL of lidocaine 1%, a 3-mL solution is obtained. Usually the injection is performed bilaterally and 1.5 mL of this solution is injected into each side. The global dose of 3.75 mg of cortivazol per session should not be exceeded.

Complications

The complications of lumbar facet joint injections with precise needle positioning are rare. Severe allergic reactions to local anesthetic are uncommon. Steroid injections can produce local reactions, which occur most often immediately after the injection. These reactions last 24-48 hours, and they can be relieved by the application of ice. The most serious complication is septic arthritis, which is avoided by adherence to strict aseptic technique. The only serious complication we have observed is a temporary episode of agitation in a patient as a reaction to the steroid injected. Other complications are rare if the usual contraindications to steroid use are respected.

Results

The value of steroid injection into the facet joint remains controversial. In the literature, immediate relief of pain occurs in 59%-94% of cases, and long-term relief occurs in 27%-54%. In our experience with 166 facet blocks, immediate pain relief was obtained in 62% of patients but long-term relief (persistence of relief for at least 6 months) in only 31% ( Box 24-3 ).

Indication

Patients in whom the block test is positive, who have undergone successful facet joint block using a mixture of steroid and local anesthetic, and in whom pain relief is complete but very short lasting may benefit from RF neurotomy of the zygapophysial joints.

Technique

The procedure is performed on an outpatient basis ( Box 24-4 ). We use dual CT and fluoroscopic guidance. The patient is positioned prone.

A perfect anteroposterior (AP) projection of the involved vertebral body is obtained, which may require craniocaudal angulation of the fluoroscopic tube so that there is perfect alignment of the vertebral endplates. Dispersive ground pads are placed on the medial aspect of the patient’s thigh.

After sterile draping, local anesthesia is infiltrated superficially in the skin and the subcutaneous tissues. We do not advocate deep anesthesia or conscious sedation, because these can interfere with the patient’s perception of pain, which is important for correct positioning of the electrode.

An 18-gauge insulated needle with an active 5-mm tip is then advanced under fluoroscopic guidance so that the tip is positioned in the groove formed by the junction of the superior articular process and the transverse process. If fluoroscopy alone is used, a lateral view is obtained to confirm the ideal position of the needle; it should not be too deep within the soft tissues for risk of damage to the dorsal nerve root. With dual guidance, a CT scan ensures correct positioning of the needle. Maintaining contact with bone ensures a safe positioning of the needle. At the L5 level, the tip of the needle should rest in the groove between the superior articular process and the sacral ala.

Once correct positioning of the needle is obtained, the electrode is inserted and connected to the generator (Smith and Nephew). Electrode impedance should be less than 500 ohms, which indicates good position of the electrode. The generator is put in stimulation mode and sensory stimulation is performed by gradually increasing the voltage to reproduce the pain that the patient normally feels in the back. It is important for the patient to only feel pain in the back and not radiating down the leg. Radiation of pain down the leg indicates that the electrode is in contact with the dorsal ramus and needs to be repositioned. Following sensory stimulation, motor stimulation is performed with gradual augmentation of the voltage, such that there is local contraction of the muscles of the back without any contraction of the muscles of the buttocks, thigh, or leg.

The generator is switched to the RF mode and coagulation is obtained by gradually increasing the RF current to achieve a temperature of 80°C, which is maintained for 90 seconds. If during the RF ablation (RFA) of the targeted nerve the patient experiences pain, injection of local anesthesia through the needle can be performed and the procedure continued to complete treatment.

Multiple levels can be treated at one visit. The patient is maintained in recumbent position for 1 hour and then discharged home.

Complications

The procedure is safe. The most serious complication is damage to the dorsal nerve root due to incorrect positioning of the electrode. This is avoided by fluoroscopic and CT-guided placement of the electrode and the use of the stimulation mode before commencing the ablation.

Results

Dreyfuss and colleagues in a prospective audit of 15 patients who were selected for rhyzolysis following a positive bloc test reported that 60% of the patients obtained at least 90% relief of pain at 12 months, and 87% obtained at least 60% relief. Relief was associated with denervation of the multifidus in those segments in which the medial branches had been coagulated.

In a randomized controlled trial of 31 patients, Van Kleef and colleagues reported success in 10 of 15 patients treated with RF compared with six of 16 in the sham group. The adjusted odds ratio was 4.8 ( P < 0.05, significant). The differences in effect on the visual analog scale scores, global perceived effect, and the Oswestry disability scale were statistically significant. Three, 6, and 12 months after treatment, there were significantly more success patients in the RF group than in the sham group.

Leclaire and colleagues in a randomized controlled trial of 70 patients undertaken to assess the clinical effectiveness of RF facet joint denervation concluded that the procedure provided some short-term improvement in functional disability among patients with chronic low back pain, but could not establish the efficacy of the treatment modality. However, the main drawback of their study was the patient selection criteria. All patients with chronic nonspecific low back pain were eligible for intraarticular zygapophysial joint injection, which was performed and reported by 30 different referring physicians. Furthermore, only one block test was performed and the levels infiltrated were not reported.

In our experience, rhyzolysis is effective in the management of pain in patients with pure axial back pain attributed to facet syndrome. However, the durability of pain relief is limited to 1 year with many patients experiencing recurrence of pain. Our results are similar to those of Schofferman and colleagues. They reported that RF neurotomy is effective but temporary in the management of lumbar facet pain. Repeated RF neurotomies are effective in long-term palliative management of lumbar facet pain. Each RF neurotomy has a mean duration of relief of 10.5 months and is successful in more than 85% patients.

Indications

• Treatment of radicular pain of discogenic origin (without nerve paralysis) resistant to conventional medical therapy

• Postdiscectomy syndrome

Contraindications

• Patients with diabetes or gastric ulceration and pregnant patients in whom steroid use is contraindicated

• Bleeding diathesis (anticoagulant therapy): Epidural puncture is contraindicated for fear of producing an epidural hematoma, resulting in thecal sac compression; foraminal injection should be performed carefully

• Spinal canal stenosis: Long-acting synthetic steroids are avoided due to their hyperosmotic effect

Technique

The procedure is performed on an outpatient basis. CT or MRI guidance can be used. There is limited accessibility to MR interventional suites and special MR-compatible needles must be used. CT with its easy accessibility is presently the imaging modality of choice because it allows for accurate needle positioning within the epidural space close to the discoradicular interface.

Lumbar Infiltrations

The patient is placed prone on the CT table and a short CT acquisition through the level of interest is performed without gantry tilt with a maximum scan thickness of 3 mm. The entry point and the needle pathway are determined from the axial slices and the position marked on the skin.

Epidural Lateral Infiltration ( Fig. 24-5 )

Epidural lateral infiltration is used for posteromedial and posterolateral disc herniation. After sterile painting and draping, the skin entry point is anesthetized. A 22-gauge spinal needle is then introduced via a posterior approach, using CT guidance so that the tip is positioned close to the painful nerve root. A sterile flexible connecting tube is attached to the needle to avoid inadvertent displacement of the tip during injection. The extradural position of the needle is determined by negative aspiration of cerebrospinal fluid and gas epidurography by injection of CO ₂ or injection of iodinated contrast material. A mixture of 1.5 mL cortivazol (3.75 mg) and 1 mL of 1% lidocaine is then injected. During injection, the patient may experience a spontaneous recurrence of pain lasting a few seconds, brought on by stretching of the dura.

If the dura is punctured due to adhesions or an incorrect maneuver, the needle should be withdrawn into the epidural space and a natural steroid like hydrocortancyl (prednisolone acetate) injected without lidocaine. Long-acting synthetic steroids should never be injected intrathecally because they may precipitate in the cerebrospinal fluid and produce a chemical arachnoiditis. In spinal canal stenosis, only natural steroids such as hydrocortancyl (prednisolone acetate) should be used to avoid worsening of the symptoms due to the hyperosmolar effect of long-acting steroids.

Foraminal Infiltration

This approach is used for foraminal and extraforaminal herniations. The procedure is similar but the entry point is more lateral. The needle is positioned under CT guidance so that it glides across the articular process, with the tip being positioned just behind the emerging nerve root. If the nerve root is touched, the patient experiences a sharp electric sensation down the lower limb and the needle tip should be withdrawn a few millimeters before injection of the steroid-anesthetic mixture.

Cervical Infiltration ( Fig. 24-6 )

The patient is positioned supine with the neck hyperextended and the head turned to the opposite side. The painful nerve root is infiltrated as it exits its foramen. The entry point is determined by a CT scan (2-mm slice thickness) through the relevant level. After sterile draping, local anesthesia is infiltrated only into the subcutaneous tissues. A 22-gauge spinal needle is positioned using a lateral approach, in contact with the anterior side of the facet joint, behind the nerve root, avoiding the anteriorly situated vertebral artery. One- to 2-mL of iodinated contrast is then injected through a connecting tube after aspiration for blood, to check for correct position of the needle tip and to exclude intravascular injection. Then 1.5 mL (3.75 mg) cortivazol is injected. Lidocaine is never injected in the cervical region to avoid diffusion via the foramen around the cord, which would result in transient paralysis.

Postprocedure Care

The patient can stand up immediately and return to work. The sterile dressing can be removed after 36 hours. Restriction of dietary sodium is advocated for 2 weeks following the injection to reduce the hyperosmolar effect of the steroid medication.