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`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`
`Orthopediatrics Corp.,
`Petitioner
`
`v.
`
`K2M, Inc.,
`Patent Owner
`
`
`Case IPR2018-00429
`U.S. Patent No. 9,532,816
`
`
`
`
`
`
`
`EXHIBIT 2009
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`

`

`76
`
`J Anat. Soc. India 51(1) 76-84 (2002)
`
`Surgical Incisions-Spinal Column
`
`Surgical Incisions-Their Anatomical Basis
`Part V - Approaches to spinal column
`*Patnaik, V.V.G. ** Singla Rajan K; ***Gupta, P.N.; ****Bala, Sanju
`Department of Anatomy, Govt. Medical College, *Patiala, **Amritsar ***Department of Orthopaedics, Govt. Medical College,
`Chandigarh ****Department of Oral & Maxillofacial Surgery, S.G.R.D. Dental College, Amritsar. INDIA
`Abstract. The present paper is a continuation of the previous one by Patnaik et al (2001). Here the anatomical bases of various
`incisions used for the exposure of different parts of vertebral column are discussed Brief steps of dissection & important anatomical
`landmarks to be taken care are delineated. Since this part of the body falls in the domain of not only orthopaedician, & neurosurgeon but
`also otolaryngologist & oral & mexillo facial surgeon, an emphasis has been laid on a multidisciplinary approach. For the same reasons, the
`authors feel that the article would be of help, apart from the anatomists to the disciples of other specialities mentioned above.
`Key words : Surgical incisions, spine, vertebral column.
`
`Introduction :
`The spine is composed of 33 vertebral seg-
`ments of which 7 are cervical, 12 thoracic, 5 lumbar,
`5 sacral and 4 are coccygeal. The sacral and the
`coccygeal vertebrae are fused as single masses,
`separately. A typical vertebra consists of a body that
`lies anteriorly, and a posterior arch that further con-
`sists of 2 pedicles, 2 laminae that are joined to-
`gether and give rise to the spinous process. The
`posterior complex also consists of 2 transverse pro-
`cesses and a pair each of superior and inferior ar-
`ticular facets. In the intervening spaces between any
`two adjacent vertebral bodies are the intervertebral
`discs, which have outer fibrous portion, called annu-
`lus
`fibrosus and an
`inner gelatinous, nucleus
`pulposus. The normal spine is lordotic at cervical
`and lumbar levels and kyphotic at dorsal and sacral
`levels. The segmental nerves and vessels pass
`through the intervertebral foramina formed by supe-
`rior and inferior borders of pedicles of adjacent ver-
`tebrae.
`Surgical approaches to spine :
`Spine may be approached by any of the follow-
`ing routes :
`(A) Anterior approaches :
`I.
`Anterior approach from occiput to C3 ver-
`tebra
`Trans oral approach
`Anterior retropharyngeal approach
`Subtotal maxillectomy
`Extended maxillotomy
`
`1.
`2.
`3.
`4.
`
`B.
`
`II.
`Anterior approach from C3-C7
`Southwich & Robinson (1957) technique
`1.
`III. Anterior approach
`to cervico
`thoracic
`junction
`Low anterior cervical approach
`1.
`High transthoracic approach
`2.
`Trans-sternal approach
`3.
`IV. Ant. approach to thoracic spine
`V.
`Ant. approach to thoracolumbar junction
`VI. Ant. approach to lumbar spine
`1.
`Ant. retroperitoneal approach (L1-L5)
`2.
`Ant. Transperitoneal approach to L5S1
`Posterior approaches :
`I.
`Post. approach to cervical spine (occiput
`to C2)
`Post. approach to cervical spine (C3-C7)
`II.
`III. Post. approach to thoracic spine (T1-T12)
`1. Midline approach
`2.
`Costo transeversectomy
`IV. Post. approach to lumbar spine (L1-L5)
`1. Midline approach
`2.
`Paraspinous approach
`V.
`Post approach to lumbosacral spine (L1-
`sacrum)
`A. Anterior approaches to spine : With the
`posterior approaches for correction of spinal defor-
`mity well estblished, in recent years more attention
`has been placed on the anterior approach to the
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`77
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`spinal column. Common use of anterior approach
`for spinal surgery did not evolve until the 1950s
`(Crenshaw, 1992). Leaders in anterior approach to
`the cervical and lumbar spine have been Cloward,
`1958; Southwick & Robinson, 1957; Bailey & Bagley,
`1960; Bohlman et al, 1982; Burrington et al, 1976;
`Conchoix & Binet, 1957; Charles & Govender, 1989;
`Fang & Ong, 1962; Fang et al, 1964; Hall, 1972;
`Charles & Hodgson et al, 1960; Micheli & Hood,
`1983; Mirbaha, 1973; Riseborough, 1973; etc.
`Indications : In general, anterior approaches
`to the spine are indicated for decompression of the
`neural elements (spinal cord, conus medullaris,
`cauda equina or nerve roots), when anterior neural
`compression
`has
`been
`documented
`by
`myelography, CT Scan or MRI. Crenshaw (1992)
`has listed followings as the most accepted indication
`for these approaches.
`A.
`Traumatic
`documented
`with
`1.
`Fractures
`neurocompression secondary to bone or
`disc fragments anterior to dura.
`Incomplete spinal cord injury (for cord re-
`covery) with anterior extradural compres-
`sion.
`Complete spinal cord injury (for root re-
`covery) with anterior extradural compres-
`sion.
`Late pain or paralysis after remote inju-
`ries with anterior extradural compression.
`Herniated intervertebral disc.
`5.
`Infections
`1.
`Open biopsy for diagnosis
`2.
`Debridement and anterior strut grafting
`C. Degenerative
`1.
`Cervical spondylitic radiculopathy
`2.
`Cervical spondylitic myelopathy
`3.
`Thoracic disc herniation
`4.
`Cervical, thoracic, and lumbar interbody
`fusions
`D. Neoplastic
`1.
`Extradural metastatic disease
`2.
`Primary vertebral body tumor
`J. Anat. Soc. India 51(1) 76-84 (2002)
`
`2.
`
`3.
`
`4.
`
`B.
`
`E. Deformity
`1.
`Kyphosis - congenital or acquired
`2.
`Scoliosis - congenital, acquired, or idio-
`pathic
`Anterior approaches have the propensity to
`cause significant morbidity as potential dangers in-
`clude
`iatrogenic
`injury
`to
`the visceral and
`neurovascular structures. Injury to specially the neu-
`ral structures is irreversible and may defeat the very
`purpose for which the surgery was planned for;
`therefore, a thorough knowledge of anatomy is es-
`sential.
`:
`The choice of approach depends upon
`(a) preference and experience of the surgeon.
`(b) Patient’s age, (c) Medical condition of the pa-
`tient, (d) Segment of the spine involved, (e) Under-
`lying pathological process, (f) Presence or absence
`of signs of neural compression.
`Various anterior approaches are described be-
`
`low :
`I.
`
`Anterior approach from occiput to C3.
`1. Trans oral approach (Spetzler, 1983)
`The patient is placed supine and the head is
`stabilized either by skull traction tongs or by May-
`Field head holding device. Uvula and the soft palate
`are retracted by tying a rubber catheter, which is
`passed from each nostril, and pulling it. The endot-
`racheal tube required for general anaesthesia is re-
`tracted to one side using special retractors. Anterior
`arch of C1(atlas) can be palpated in the depth of
`posterior wall of pharynx. A midline longitudinal inci-
`sion is chosen to expose the anterior aspects of C1
`and C2 as the midline is relatively avascular. Re-
`tracting the flaps laterally can further increase the
`exposure. After the wound is closed, it is desirable
`to keep the endotracheal tube in situ for a further
`period of 12-24 hours to maintain adequate airway.
`This approach is commonly used for caries involv-
`ing the anterior arch of C1 or vertebral bodies of C2,
`C3 and also for transoral odontoidectomy.
`2.
`Anterior retropharyngeal approach (McAffee et
`al, 1987)
`This approach is extra-mucosal and avoids all
`the complications associated with transoral ap-
`proach. One of the common indications is caries
`involving C1 , C2 region. The technique has been
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`described by Mc Affee et al. (1987) A thorough un-
`derstanding of anatomical tissue planes and fascial
`spaces as described by Singh et al (2000) is manda-
`tory before undertaking this approach. A T-shaped
`incision is given in right submandibular region
`(Fig. 1). The platysma muscle is cut and its flaps
`
`Fig. 1
`Anterior retropharyngeal
`Approach
`
`mobilized. The marginal mandibular branch of 7th
`nerve
`is
`identified
`and
`protected.
`The
`retromandibular vein is ligated at its junction with
`the
`internal
`jugular vein. This brings
`the
`sternomastoid muscle in view with its overlying su-
`perficial layer of deep cervical fascia; this layer is
`cut and the sternomastoid muscle is retracted. Next
`pulsations of the carotid artery are felt and it is pro-
`tected. Submandibular gland is resected and its duct
`is ligated to prevent formation of a salivary fistula.
`Tendon of digastric is identified and divided. Trac-
`tion injury to the facial nerve can be caused by su-
`perior retraction on the stylohyoid muscle and one
`should be careful regarding that. The hyoid bone
`and hypopharynx are then mobilized medially, pre-
`venting exposure of the esophagus, hypopharynx,
`and nasopharynx out of harm’s way. Next, hypoglos-
`sal nerve is identified and retracted superiorly. Dis-
`section is continued to the retropharyngeal space
`between the carotid sheath laterally and the larynx
`and pharynx medially. Exposure is increased by
`ligating branches of the carotid artery and internal
`jugular vein, which prevent retraction of the carotid
`sheath laterally. The superior laryngeal nerve is
`identified and mobilized. Following adequate retrac-
`tion of
`the carotid sheath
`laterally, alar and
`prevertebral fascial layers are divided longitudinally
`to expose the longus colli muscles which are erased
`subperiosteally from the anterior aspect of the arch
`of C1 and the body of C2, taking care to avoid injury
`to the vertebral arteries. Next, meticulously debride
`the involved osseous structures and, if needed, per-
`form bone grafting with either autogenous iliac or
`fibular bone. During closure it is important to repair
`the digastric muscle.
`
`Surgical Incisions-Spinal Column
`
`The patient is maintained in skeletal traction in
`the postoperative period with the head end of the
`bed elevated to reduce swelling. Endotracheal tube
`is continued until pharyngeal edema subsides, usu-
`ally by 48 hours.
`3.
`Subtotal maxillectomy
`Cocke et al (1990) have described an ex-
`tended maxillotomy and subtotal maxillectomy as
`an alternative to the transoral approach for exposure
`and removal of tumor or bone anteriorly at the base
`of the skull and cervical spine to C5. This approach
`has been used in a limited number of procedures,
`and the indications have not yet been firmly estab-
`lished. This procedure is technically demanding and
`requires a thorough knowledge of head and neck
`anatomy. It should be performed by a team of sur-
`geons,
`including
`an
`otolaryngologist,
`a
`neurosurgeon, an orthopaedist and oral & maxillofa-
`cial surgeon.
`
`Fig. 2
`Extended maxillotomy and
`subtototal maxillectomy
`
`The maxilla is exposed through a modified
`Weber Ferguson skin incision (Fig. 2). A vertical
`incision is made through the upper lip in the philtrum
`from the nasolabial groove to the vermillion border.
`Lower end in extended to the midline and then verti-
`cally in the midline through the buccal mucosa to
`the gingivobuccal gutter. Upper lip is divided and
`labial arteries are ligated. External skin incision is
`extended transversely from the upper end of the lip
`incision in the nasolabial groove to beyond the nasal
`ala and then superiorly along the nasofacial groove
`to the lower eyelid. Central incisor is extracted and a
`vertical midline
`incision
`is made
`through
`the
`mucoperiosteum of maxilla from gingivobuccal gut-
`ter to the central incisor defect and then trans-
`versely through the buccal gingiva adjacent to the
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`teeth to the retromolar area. Skin, subcutaneous tis-
`sue, periosteum and mucoperiosteum of maxilla is
`elevated to expose maxilla, nasal bone, piriform ap-
`erture of nose inferior orbital nerve and zygomatic
`bone (Crenshaw, 1992). Further steps of dissection
`are beyond the scope of this article and interested
`readers are referred to the original article.
`4. Extended maxillotomy : Skin incision and
`initial steps to expose maxilla are same as subtotal
`maxillectomy with a difference that central incisor
`tooth is not extracted. For the rest of the steps origi-
`nal article may be consulted.
`II.
`Anterior Approach to C3-C7 :
`Cervical spine in region of C3 to C7 can be
`approached through a longitudinal or a transverse
`incision. The approach is carried out medial to the
`carotid sheath. A lot of vital structures come in the
`way, so as thorough knowledge of fascial planes and
`spaces, as described by Singh et al (2000) allows a
`safe and direct approach to this area.
`Cervical traction is recommended during sur-
`gery. Spinal cord monitoring should be used if avail-
`able to prevent inadvertent injury to the spinal cord.
`A left sided approach minimizes the risk of injury to
`recurrent laryngeal nerve as it has a more predict-
`able course than its right counterpart.
`
`Fig. 3
`Anterior approach to C3-C7
`
`A longitudinal or transverse incision is given at
`the anterior border of sternomastoid muscle (Fig. 3)
`at the desired level. In general, an incision 3-4 finger
`breadths above the clavicle is required to expose
`C3-C5 and an incision 2-3 finger breadths above the
`clavicle allows exposure of C5-C7. Platysma muscle
`is cut in line with the skin incision to expose the
`J. Anat. Soc. India 51(1) 76-84 (2002)
`
`79
`
`anterior border of sternomastoid muscle. The super-
`ficial layer of deep cervical fascia is incised longitu-
`dinally and the carotid vessels are located by palpa-
`tion. The middle layer of deep cervical fascia en-
`closing omohyoid muscle is then incised and the
`carotid sheath and the sternomastoid muscle are
`retracted laterally. The cervical bodies can be ex-
`posed by retracting the esophagus and the trachea
`medially. The deep layer of deep cervical fascia,
`which overlies the bodies, is dissected by blunt dis-
`section and the longus coll muscle is reflected later-
`ally to further increase the exposure. The lateral dis-
`section should be limited till the Uncovertebral joints
`to prevent injury to the vertebral vessels as they
`pass through the foramen. Appropriate vertebral/
`disc level is identified radiographically.
`III. Anterior approach to cervicothoracic junction
`The rapid transition from cervical lordosis to
`thoracic kyphosis results in an abrupt change in the
`depth of the wound. Also there is a confluent area of
`vital structures that are not readily retracted.
`The cervicothoracic
`junction can be ap-
`proached either by a low anterior cervical approach,
`which can expose cervical vertebral bodies as well
`as thoracic spine upto T2 level, or by a high tran-
`sthoracic approach, which is especially suitable in
`scoliosis involving the cervicothoracic junction, or by
`trans-sternal approach, which gives exposure from
`C4 to T4.
`1.
`Low anterior cervical approach :
`Enter on the left side by a transverse incision
`placed 1 finger breadth above the clavicle. Extend it
`well across the midline, taking particular care when
`dissecting about the carotid sheath in the area of
`entry of the thoracic duct. The latter approaches the
`jugular vein from its lateral side, but variations are
`not uncommon. Further steps in exposure follow
`those of the conventional anterior cervical approach.
`2.
`High trans-thoracic approach
`A kyphotic deformity of the thoracic spine
`tends to force the cervical spine into the chest, in
`which instance a high transthoracic approach is a
`logical choice. Make a periscapular incision (Fig. 4)
`and remove the second or third rib; removing the
`latter is necessary to provide sufficient working
`space in a child or if a kyphotic deformity is present.
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`This exposes the interval between C6 & T4. Excision
`of Ist or 2nd rib is adequate in adults.
`
`Fig. 4
`Patient poistioning and
`periscapular incision for
`high transthoracic approach
`
`3.
`
`Trans-sternal appraoch :
`Make a Y shaped or straight incision with the
`vertical segment passing along the midsternal area
`form the suprasternal notch to just below the xiphoid
`
`Fig. 5
`Transternal approach to cervicthoracic spine
`
`process (Fig. 5). Next, extend the proximal end di-
`agonally to the right and left along the base of the
`neck for a short distance. To avoid entering the ab-
`dominal cavity, take care to keep the dissection be-
`neath the periosteum while exposing the distal end
`of the sternum. At the proximal end of the sternal
`notch take care to avoid the inferior thyroid vein. By
`blunt dissection reflect the parietal pleura from the
`posterior surfaces of
`the sternum and costal
`cartilages and develop a space. Pass one finger or
`an instrument above and below the suprasternal
`space, insert a Gigli saw, and split the sternum. Now
`spread the split sternum and gain access to the cen-
`ter of the chest. In children the upper portion of the
`exposure will be posterior to thymus and bounded
`by the innominate, the carotid arteries and their
`venous counterparts. Next, dissect the left side of
`this area bluntly. In patients with kyphotic deformity
`the innominate vein may now be divided as it
`crosses the field; it may be very tense and subject
`to rupture. This division is recommended by Fang et
`al (1964). The disadvantage of ligation is that it
`
`Surgical Incisions-Spinal Column
`
`leaves a slight postoperative enlargement of the left
`upper extremity that is not apparent unless carefully
`assessed. This approach provides limited access,
`and
`its success depends on accuracy
`in
`preoperative interpretation of the deformity and a
`high degree of surgical precision.
`IV. Anterior approach to thoracic spine (Tran-
`sthoracic approach)
`The anterior approach to the thoracic spine
`provides access from T2 to T12. Most of the times a
`left sided approach is preferred as in right -sided
`approach presence of liver especially in the lower
`thoracic area can limit the exposure. Moreover the
`inadvertent injury to aorta, which lies on the left
`side, is easier to handle as compared to injury to the
`inferior vena cava, which has thinner wall.
`
`Fig. 6
`Transthoracic approach
`
`The patient is placed in lateral position with
`left side up. Incision is then given over the rib of
`corresponding or 1-2 level higher vertebra depend-
`ing on the level and the extent of exposure required
`(Fig. 6). The rib is dissected subperiosteally by cut-
`ting the subcutancous tissue and the muscles over-
`lying it. The rib is removed by cutting at the
`costochondral junction and disarticulating the rib
`from the transverse process. During this process
`one should be careful not to injure the intercostal
`nerves. The parietal pleura are then incised in line
`with the skin incision and the lung and the other
`contents of mediastinum are retracted by a retractor.
`The parietal pleura overlying the vertebral bodies is
`dissected to expose the segmental vessels, which
`are identified and cut after ligating. The periosteum
`is elevated from the vertebral bodies to expose the
`vertebral bodies and the pedicles. The excised rib
`can be used as a strut graft for fusion of the spine. If
`extended exposure is required like for scoliosis cor-
`rection, 2 ribs can be removed either at adjacent
`levels or at different levels by another skin incision.
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`V.
`
`Anterior approach to thoracolumbar junction
`The presence of the diaphragm originating
`from the upper lumbar vertebrae and the twlfth ribs
`poses technical problems in exposure. The position
`is similar as for thoracic exposure. The incision is
`centered on 10th rib, which allowes exposure be-
`tween T10 and L2. It is made curvilinear with ability
`to extend either the cephalad or caudal end (Fig. 7).
`
`Fig. 7
`Thoracolumbar appraoch
`
`The diaphragm is identified and is incised after care-
`fully retracting the lung. The incision of the dia-
`phragm should be done at the periphery to minimize
`the risk of postoperative paralysis of diaphragm as
`the phrenic nerve supplies it from the center to the
`periphery. Now take care in entering the abdominal
`cavity. Since the transversalis fascia and the perito-
`neum do not diverge, dissect with caution and iden-
`tify the two cavities on either side of the diaphragm.
`Incise the diaphragm 2.5 cm away from its insertion
`and tag it with sutures for later closure. Incise the
`prevertebral fascia. The rest of the dissection is the
`same as for anterior thoracic and lumbar exposure.
`VI. Anterior aproach to lumbar spine.
`1. Anterior retroperitoneal approach (L1-L5)
`The patient is positioned with right side down.
`The approach is made most often from the left side
`
`Fig. 8
`Anaterior retroperitoneal
`appraoch
`
`J. Anat. Soc. India 51(1) 76-84 (2002)
`
`81
`
`to avoid the liver and IVC, which is more difficult to
`repair then the aorta, should vascular injury occur
`during the surgery. The skin incision is placed paral-
`lel to the 12th rib, in the abdominal region, depend-
`ing on the level of exposure required (Fig. 8). The
`subcutaneous tissue, external oblique, internal ob-
`lique, transversus abdominus, and the transversalis
`fascia are all cut in the line with skin incision. At this
`point care is taken not to enter the peritoneal cavity.
`The peritoneum is reflected anteriorly using blunt
`dissection to expose the psoas muscle. The expo-
`sure can be widened by applying a Finochitto rib
`retractor between the costal margin and the iliac
`crest. The sympahetic chain, which lies between the
`psoas and the vertebral bodis, and the genito-femo-
`ral nerve, which lies anteriorly on the psoas, need to
`be protected. Also the aorta and the inferior vena
`cava, which lie anterior on, the vertebral bodies re-
`quires to be identified and carefully protected. The
`appropriate vertebral body is exposed by elevating
`the psoas muscle from the lumbar vertebral bodies.
`The lumbar segmental vessels, which come in the
`way, should be ligated. The pedicles of the vertebral
`bodies are next identified to locate the neural fora-
`men. The affected bodies and the pedicles can be
`removed using bone rongeurs to expose the dura.
`The wound is closed over a drain in the retroperito-
`neal space.
`2.
`Anterior transperitoneal approach to L5-S1.
`Anterior transperitoneal approach is especially
`useful in lumbosacral junction area as the retroperi-
`toneal approach gives a limited exposure at the
`level because of presence of the iliac crest. How-
`ever, this approach has the disadvantage that the
`hypogastric plexus, which carries sympathetic fibres
`to the urogenital system can be injured and can
`cause retrograde ejaculation in males. However, in-
`jury to the hypogastric plexus can be avoided by
`careful opening of the posterior peritoneum and
`blunt dissection of the prevertebral tissue from left
`to right and by opening the posterior peritoneum
`higher over the bifurcation of the aorta and then
`extending the opening down over the sacral prom-
`ontory. In addition, electrocautery should be kept to
`a minimum when dissecting within the aortic bifurca-
`tion, and until the anulus of the L5 to S1 disc is
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`82
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`clearly exposed, no transverse scalpel cuts on the
`front of the disc should be made.
`The position is supine and a midline abdominal
`incision is given (Patnaik et al, 2001). The perito-
`neum is reached by incising the rectus abdominis
`sheath in the midline. The peritoneum is opened
`and the bowel is packed to expose the posterior
`peritoneum, which lies over the sacral promontory
`region. The aorta is palpated at its bifurcation and
`the posterior peritoneum is carefully incised in mid-
`line in that region avoiding damage to the great ves-
`sels. The dissection is then carried along the right
`common iliac vessels till its division into external
`and intrnal iliac vessels, and then the dissection is
`curved medially to avoid ureter from being injured,
`which is identified and protected. The soft tissues
`are dissected using blunt gauze from left to the right
`side from the level of left common iliac vessels,
`which will protect the hypogastric plexus from being
`injured. The middle sacral artery, which is the termi-
`nal branch of aorta, and also the middle sacral vein,
`needs to be protected during the exposure of L5/S1
`disc. Confirmation of L5/S1 disc should be done by
`intraoperative roentgenograms as L5 body may be
`frequently mistaken for the sacrum.
`B.
`Posterior approaches :—
`The posterior approach through a midline lon-
`gitudinal incision provides access to the posterior
`elements of the spine at all levels, including cervi-
`cal, thoracic, and lumbosacral. It is the most direct
`access to the spinous processes, laminae, and fac-
`ets and, in addition, the spinal canal may be ex-
`plored and decompressed over a large area after
`laminectomy. Under most circumstances the choice
`of approach to the spine should be dictated by the
`site of the primary pathological condition. Posterior
`approaches to the spine rarely are indicated when
`the anterior spinal column is the site of an infectious
`process or a metastatic disease. The posterior ele-
`ments usually are not involved in the pathological
`process and provide stabilization for the uninvolved
`structures of the spinal column. Removal of the
`uninvolved posterior elements, as in laminectomy,
`may result in subluxation, dislocation, or severe
`angulation of the spine, causing increased compres-
`sion of the neural elements and worsening of any
`neurological deficit.
`
`Surgical Incisions-Spinal Column
`
`I.
`
`Post. approach to cervical spine (Occiput
`to C2)
`Patient is positioned prone and skull traction
`tongs are applied. A midline longitudinal skin inci-
`sion is given from occiput to spinous process of C2.
`(Fig 9) Deeper dissection is carried out in the mid-
`line raphe (nuchal ligament) to minimize the bleed-
`ing, as it is avascular.
`
`Fig. 9
`Posterior approach to upper cervical spine
`
`One has to be careful in C1/Occiput junction
`and the dissection should not be carried out more
`than 1.5 cm from midline to avoid injuring the verte-
`bral vessels. Second cervical ganglion is the land-
`mark taken for the lateral dissection, which lies in
`the groove for vertebal artery.
`The posterior arch of C1 lies deeper in com-
`parison to the spinous process of C2. Care should
`be exercised while dissecting near to C1 arch be-
`cause it is thin and vulnerable to fracture during
`dissection and secondly the dura is also vulnerable
`to injury at superior as well as inferior aspect of C1.
`II.
`Post. approach to cervical spine (C3-C7)
`Patient is positioned prone and skull traction
`tongs are applied. A midline longitudinal skin inci-
`sion is given from spinous process of C2 to spinous
`process of C7, depending on the area to be dis-
`sected. Deeper dissection is carried out in the mid-
`line raphe (nuchal ligament) to minimize the bleed-
`ing, as it is avascular. The exposure can be safely
`done up to the level of facet joints without endanger-
`ing any important structure.
`III. Post. approach to thoracic spine (T1-T12)
`1. Mid line incision : Patient is positioned prone
`and a midline longitudinal skin incision is given from
`spinous process of T1 to spinous process of T12,
`depending on the area to be dissected. Deeper dis-
`J. Anat. Soc. India 51(1) 76-84 (2002)
`
`K2M, Ex. 2009-7
`IPR2018-00429
`
`

`

`Patnaik, V.V.G. et al
`
`the midline. The
`in
`is carried out
`section
`paraspinous muscles are erased from the posterior
`elements using a cobb’s periosteum elevator. Lat-
`eral exposure can be done to the level of transverse
`processes safely and no important structure comes
`in the way. This approach is commonly used for
`posterior spinal stabilization, for scoliosis correction
`and instrumentation and also for intradural surgery.
`2.
`Costotransversectomy
`The thoracic vertebrae may be alternatively
`approached through a costotransversectomy when
`direct access to the transverse processes and
`pedicles of the thoracic spine and limited access to
`the
`vertebral
`bodies
`are
`indicated.
`Costotransversectomy should be considered
`for
`simple biopsy or local debridement. It should be
`noted, however, that this approach does not provide
`the working operative area or length of exposure to
`the thoracic vertebral bodies that is afforded by a
`transthoracic approach or the midlongitudinal poste-
`rior approach.
`
`Fig. 10
`Skin incision for
`Costotransversectomy
`
`Position the patient prone or lateral. Make a
`curved incision with its apex lateral to the midline at
`the desired level (Fig. 10). Deepen the dissection
`through the subcutaneous tissues and the trapezius
`and latissimus dorsi muscles and the lumbodorsal
`fasciae, which are divided longitudinally. Dissect the
`paraspinal muscles sharply from their insertions on
`the ribs and transverse processes, and retract them
`medially. Expose the transverse process and poste-
`rior aspects of the associated rib subpriosteally and
`remove a section of rib 5 to 7.5 cm long at the level
`of involvement, disarticulating from the rib facet.
`The rib generally is transected at its prominent pos-
`terior angle. Take care to remain subperiosteally and
`extra pleural during this part of the exposure and to
`protect the intercostal neurovascular bundle. Ante-
`rior to the transverse process is the vertebral
`pedicle, and above and below the pedicle lie the
`neuroforamina. Once the pedicles, neuroforamina,
`J. Anat. Soc. India 51(1) 76-84 (2002)
`
`83
`
`and neurovascular structures have been identified,
`proceed with dissection directly anteriorly on the
`pedicle to the vertebral body along a path that is
`relatively free of major vessels or nerves. Carefully
`dissect the parietal pleura anteriorly to expose the
`anterolateral aspect of the vertebral body, raising
`the sympathetic trunk and parietal pleura. Exposure
`may be increased by removal of the transverse pro-
`cess, pedicle, and facet joints as necessary. After
`completion of the spinal procedure, check for air
`leaks in the pleura. Close the wound in layers over a
`drain to prevent hematoma collection. Should a leak
`occur, an intercostal chest tube drainage should be
`used.
`IV. Posterior approach to lumbar spine (L1-L5)
`The lumbar spine can be approached posteri-
`orly either by a midline or through the Paramedian
`approach. Through the posterior midline approach
`the spine can be easily reached upto the transverse
`processes, though, it is much easier to reach the
`more lateral areas by the Para-median approach,
`the disadvanage is that the latter causes more
`bleeding. Posterior approach to the spine is com-
`monly used for disc excision in cases of prolapsed
`intervertebral disc, posterior stabilization in cases of
`fracture & scoliosis of spine and also for approach-
`ing any intra-dural pathology.
`1.
`Posterior midline approach
`Patient is positioned prone and a midline longi-
`tudinal skin incision is given from spinous process of
`L1 to spinous process of L5, depending on the area
`to be dissected. Deeper dissection is carried out in
`the midline. The spinous processes are reached and
`the paraspinous muscles are erased from the poste-
`rior arch to reach upto the tips of the transverse
`processes as required. The dissection can be ex-
`tended proximally to the dorsal or distally to the
`sacral region if required.
`Placing the patient on a padded spinal frame
`or kneeling position and keeping the abdomen free
`helps to minimize the bleeding during surgery.
`2.
`Posterior paraspinous approach :
`Recently, Wiltse and Spencer (1988) refined
`the paraspinal approach to the lumbar spine, which
`involves
`a
`longitudinal
`separation
`of
`the
`sacrospinalis muscle group to expose the posterolat-
`eral aspect of the lumbar spine. This approach is
`especially useful
`in
`removing
`far
`lateral disc
`
`K2M, Ex. 2009-8
`IPR2018-00429
`
`

`

`84
`
`Surgical Incisions-Spinal Column
`
`inserting
`
`lateral
`
`fusion, and
`
`herniation, pestero
`pedicle screws.
`Patient is positioned prone and a midline longi-
`tudinal skin incision is given from spinous process of
`L1 to spinous process of L5, depending on the area
`to be dissected. Dissection is done upto the deep
`fascia and retraction is done to expose paraspinal
`muscles on the desired side. Cleavage is then cre-
`ated between the multifidus and the latisimus dorsi
`muscles by blunt dissection to reach the area of the
`facet joints. Further exposure can be gained by
`subperiosteal dissection of the muscles. This ap-
`proach is commonly used for inter-transverse spinal
`fusion.
`V.
`Posterior approach to lumbosacral spine
`(L1-Sacrum).
`A longitudinal skin incision is given over the
`spinous processes of the appropriate vertebrae. The
`superficial
`fascia,
`lumbodorsal
`fascia, and
`the
`supraspinous ligaments are incised longitudinally,
`over the tips of processes. The ligament is divided
`longitudinally between the 2 spinous processes in
`the most distal part of the wound. Keeping a small,
`blunt periosteal elevator in this opening, and with a
`scalpel, muscles are striped subperiosteally from
`distal to proximal.
`Expose the spinous processes from distal to
`proxima