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PubMed1994

Cervical corpectomy and plate fixation for postlaminectomy kyphosis.

Between 1987 and 1991, 20 patients with symptomatic postlaminectomy kyphosis were treated with anterior decompression, bone graft, and anterior cervical plate. The patients were predominantly male (14:6) with a mean age of 58 years. The initial laminectomy was performed for either spondylosis (80%) or spinal tumor (20%). All patients had anterior compressive pathology, which was associated with instability (45%), neck pain (75%), myeloradiculopathy (90%), or severe neck deformity (30%). The mean degree of kyphosis was 38 degrees. Treatment consisted of a trial of cervical traction (75%), anterior corpectomy (95%), intersegmental decompression (5%), bone fusion (100%), and fixation with either Caspar (85%) or Synthes (15%) anterior plating at a mean of 3.8 levels. Halo fixation was used in 10% of patients. Postoperative complications included vocal cord paresis (15%), pneumonia (10%), wound dehiscence (5%), and screw pull-out (5%). At follow-up evaluation, a mean of 28 months after treatment, all patients had a solid fusion and a mean curvature improvement to 16 degrees residual kyphosis. Neurologically, 10% were cured, 55% were improved and returned to premorbid function, 30% were stable, and 5% had late progression. These data suggest that immediate fixation with anterior plating facilitates solid fusion, maintains spinal curvature, and promotes neurological improvement.

Adult↗
PubMed1994

Same-day microsurgical arthroscopic lateral-approach laser-assisted (SMALL) fluoroscopic discectomy.

The 2-year experience of one neurosurgeon with Kambin's orthopedic instruments and frame for arthroscopic microdiscectomy is reported. Arthroscopy using a unilateral approach and monoportal technique is a valuable adjunct to fluoroscopic monitoring. One hundred patients underwent same-day microsurgical arthroscopic lateral-approach laser-assisted (SMALL) fluoroscopic discectomy. In addition, suspected spinal tumors in three patients were treated by biopsy and infection of the disc space was drained in one. A prototype operating discoscope was employed for delivery of the neodymium:yttrium-aluminum-garnet laser beam to assist with hemostasis. Seventy-five "ideal" cases were identified that exhibited the following features: 1) up to a 6-month history of unilateral sciatica symptoms, which responded to bed rest; 2) mechanical signs of nerve root irritation when the patient was erect; 3) computerized tomography or magnetic resonance imaging studies interpreted as showing one protruding or prolapsed disc without extrusion; 4) no segmental spondylosis at the level of a herniated nucleus pulposus; 5) no motor weakness; 6) no prior disc surgery; 7) no obesity; and 8) no diabetes mellitus. Twenty-five "nonideal" cases failed to meet one or more of the above criteria. Good outcome rates were not substantially different in the two groups, success being judged in part by patient satisfaction. Complete success was evidenced in two-thirds of cases by early return to work, but improvement was also determined by increased mobility and a reduction in pain medication from narcotic to analgesic agents. Three patients underwent repeat surgery (laminotomy), but only one improved. Two years has provided sufficient clinical experience to determine that a percutaneous endoscopic procedure under neuroleptanalgesia may become a significant surgical alternative.

Adolescent↗
PubMed1994

Update on the Cloward procedure: new instruments.

A series of 283 patients who suffered from cervical spondylosis, herniated disc, or traumatic pathology of the cervical spine were operated on using an anterior approach. Intersomatic arthrodesis was performed in 350 cases; in every case, a threaded bone graft was screwed into the intervertebral orifice using the technique described by the author. Fusion was achieved within 6 months in 93% of cases with 92 autologous grafts and in 81% of cases with 258 heterologous grafts. In addition to the use of threaded intervertebral holes and threaded bone grafts, the Cloward technique was modified by the introduction of a set of new instruments, which largely replaced the ones previously use. These included a low-speed motor with different drills and trephines, a trephine guide retractor, and an intersomatic retractor.

Animals↗
PubMed1995

Continuous intraoperative electromyographic recording during spinal surgery.

One hundred fifty patients underwent spinal surgery for radiculopathy; of these, 120 underwent lumbar surgery and 30 had cervical operations. All of the surgeries were performed to alleviate symptoms due to disc herniation, spondylosis, or both. During the surgical procedures continuous intraoperative electromyograph recordings were taken from the muscle corresponding to the involved nerve root. In baseline recordings taken in the operating room 10 minutes before lumbar surgery, electrical discharge or firing was recorded from the muscle in 18% (22 of 120 patients) of the cases. Once the nerve was decompressed, muscle firing ceased. Electrical discharges were produced with regularity on nerve root retraction. This study concludes that continuous electromyograph monitoring can be accomplished easily and yields valuable information that indicates when the nerve root is adequately decompressed or when undue retraction is exerted on the root.

Aged↗
PubMed1996

Bilateral multilevel laminectomy with or without posterolateral fusion for cervical spondylotic myelopathy: relationship to type of onset and time until operation.

The authors retrospectively evaluated the relationship of several preoperative factors in 69 patients who had myelopathy due to multilevel cervical spondylosis without ossification of the posterior longitudinal ligament treated with Kirita's bilateral wide laminectomy. In 34 patients with focal instability or malalignments, posterolateral fusion was also combined. The clinical results at an average follow-up period of 3.5 years (range 1-10 years) after operation in the groups that had and had not undergone fusion were equally satisfactory, and preoperative focal instability was believed to be the sole useful indication for adding posterolateral fusion. The patients were classified in three groups according to the acuteness of the onset. The type of onset and time until operation were found to be the factors most strongly related to prognosis, and clinical outcome was correlated with the duration after onset when plotted as days in the acute, months in the subacute, and years in the insidious onset groups. Wide laminectomy with or without posterolateral fusion is a simple operation that is recommended, provided that it is performed early enough according to the type of onset.

Aged↗
PubMed1997

Modified open-door cervical expansive laminoplasty for spondylotic myelopathy: operative technique, outcome, and predictors for gait improvement.

Twenty-five patients underwent an expansive cervical laminoplasty for nontraumatic cervical spondylosis with myelopathy during the period from June 1990 to November 1994, and all had a minimum of 18 months of follow-up review. The open-door laminoplasty procedure presently reported consisted of the same approach evaluated by Hirabayashi in 1977, except that the authors of this report used three rib allografts to anchor the "open door," rather than spinous process sutures or autologous bone grafts. Posterior foraminotomies and decompression were performed in patients with clinical radiculopathy and radiographic evidence of foraminal stenosis. Preoperatively, gait disturbance was present in all patients. All 25 patients (100%) had long-tract signs on presentation. Nondermatomal upper-extremity symptoms (numbness, tingling, weakness, and pain) were quite common in this group of patients. Bowel, bladder, and/or sexual dysfunction was found in 13 (52%) of 25 patients. Preoperative radiographic studies showed a mean midline anteroposterior diameter spinal canal/vertebral body (SC/VB) ratio of 0.623 and a mean compression ratio (sagittal/lateral diameter ratio x 100%) of 37%. This procedure was quite successful in relieving preoperative symptoms and few complications occurred. Gait disturbance was improved in 21 (84%) of 25 patients and hand numbness and tingling were improved in 13 (87%) of 15 patients. Bowel or bladder function improved in 10 (77%) of 13 patients. Radiculopathy, when present, was alleviated in all four patients after the decompressive procedure. The postoperative SC/VB ratio, as measured by plain lateral radiographs and/or computerized tomography scans, was improved to 0.871, a 38% improvement. In a comparison with the preoperative SC/VB ratio using the two-tailed t-test, alpha was less than 0.001. The compression ratio improved to 63% postoperatively, which yielded an alpha of less than 0.005 according to the two-tailed t-test. Only one postoperative complication, an anterior scalene syndrome, was encountered. Various predictors of surgical outcome based on gait improvement were evaluated. Age greater than 60 years at the time of presentation, duration of symptoms more than 18 months prior to surgery, preoperative bowel or bladder dysfunction, and lower-extremity dysfunction were found to be associated with poorer surgical outcome. Even when these conditions were present, gait improvement was noted in at least 70% of the patients.

Cervical Vertebrae↗
PubMed1997

Revision of anterior cervical pseudoarthrosis with anterior allograft fusion and plating.

Anterior cervical discectomy and fusion is an efficacious procedure used to treat a variety of cervical spinal disorders, including spondylosis, myelopathy, herniated discs, trauma, and degenerative disc disease. Pseudarthrosis, or failure of fusion, may be the most common complication of spinal fusion procedures. Nineteen consecutive patients with symptomatic pseudarthrosis following failed anterior cervical fusions were treated with anterior cervical revision using iliac crest allografts and either the Cervical Spine Locking Plate system (10 patients) or the Trapezial Osteosynthetic Plate system (nine patients). The mean age of the nine men and 10 women undergoing treatment was 49.1 years (range 25-72 years). Eleven patients (57.9%) exhibited pseudarthrosis at one level, six (31.5%) at two levels, and two (10.5%) at three levels. The indications for revision were intractable neck pain with radiculopathy (17 patients) or myelopathy (two patients), with evidence of pseudarthrosis on plain cervical radiography as well as computerized tomography (CT) or single-photon emission computerized tomography (SPECT) scanning, or both. All eight patients evaluated with SPECT showed increased focal uptake consistent with pseudarthrosis, which was subsequently confirmed intraoperatively in all eight. The average follow-up period was 22.4 months (range 12-42 months). Solid osseous fusion was achieved over all 28 levels in all 18 patients available for follow-up review (100%). One patient died 4 months postoperatively from myocardial infarction related to preexisting coronary artery disease. There were no intraoperative complications; postoperatively, two patients (10.5%) experienced transient hoarseness. Anterior revision of failed cervical fusions using allograft interbody fusion material and anterior plating is a safe and efficacious procedure. In this series, the use of allografts avoided donor site morbidity without adversely affecting fusion rates. Rigid internal fixation was achieved by means of anterior plating without increasing surgical morbidity rates. The SPECT imaging technique has the potential to reliably confirm the diagnosis of pseudarthrosis.

Adult↗
PubMed1997

Multilevel anterior cervical corpectomy and fibular allograft fusion for cervical myelopathy.

This study was conducted to determine the safety and efficacy of multilevel anterior cervical corpectomy and stabilization using fibular allograft in patients with cervical myelopathy. Thirty-six patients underwent this procedure for cervical myelopathy caused by spondylosis (20 patients), ossified posterior longitudinal ligament (four patients), trauma (one patient), or a combination of lesions (11 patients). The mean age (+/- standard deviation) of the patients was 58 +/- 10 years and 30 of the patients were men. The mean duration of symptoms before surgery was 30 +/- 6 months and 11 patients had undergone previous surgery. Prior to surgery, the mean Nurick grade of the myelopathy was 3.1 +/- 1.4. Seventeen patients also had cervicobrachial pain. Four vertebrae were removed in six patients, three in 19, and two in 11 patients. Instrumentation was used in 15 cases. The operative mortality rate was 3% (one patient) and two patients died 2 months postoperatively. Postoperative complications included early graft displacement requiring reoperation (three patients), transient dysphagia (two patients), cerebrospinal fluid leak treated by lumbar drainage (three patients), myocardial infarction (two patients), and late graft fracture (one patient). One patient developed transient worsening of myelopathy and three developed new, temporary radiculopathies. All patients achieved stable bone union and the mean Nurick grade at an average of 31 +/- 20 months (range 0-79 months) postoperatively was 2.4 +/- 1.6 (p < 0.05, t-test). Cervicobrachial pain improved in 10 (59%) of the 17 patients who had preoperative pain and myelopathy improved at least one grade in 17 patients (47%; p < 0.05). Twenty-six surviving patients (72%) were followed for more than 24 months and stable, osseous union occurred in 97%. These results show that extensive, multilevel anterior decompression and stabilization using fibular allograft can be achieved with a perioperative mortality and major morbidity rate of 22% and with significant improvement in pain and myelopathy.

Aged↗
PubMed1998

Bisegmental cervical interbody fusion using hydroxyapatite implants: surgical results and long-term observation in 70 cases.

UNLABELLED: Hydroxyapatite (HA) is the main constituent of bone mineral, and synthetic HA serves as a biocompatible and bioactive material. It permits bone growth on its surface and forms a union with the adjacent bone. OBJECT: The authors have developed implants made of porous HA, which they have used in more than 90 cases in the past 6 years to achieve cervical interbody fusion. The implants were designed to provide maximum durability, biomechanical stability, and alignment preservation and to be technically easy to use. The authors summarize their experience and results with the use of these implants. METHODS: The results of postoperative follow-up observation of 12 months or longer (mean 37.1 +/- 2.4 months) are available in 70 patients with underlying disease including: spondylosis, disc extrusion, ossification of the posterior longitudinal ligament (PLL), hypertrophy of the PLL, and trauma. The patients' ages at the time of surgery ranged from 22 to 83 years (mean 50.6 +/- 1.3 years). Flexion-extension radiographs and tomograms, obtained 6 and 12 months after surgery and every year thereafter, were used to demonstrate solid fusion in all cases. Dislocation of the implant occurred in three patients who were treated during the early portion of the series. At 6 to 12 months after surgery, encasement of the implant and formation of union were observed. Normal lordosis, if present prior to surgery, was maintained postsurgery. No neurological deterioration related to the site of fusion occurred during the period of observation. CONCLUSIONS: The authors conclude that satisfactory interbody fusion can be achieved by using HA implants, provided their design is appropriate and adequate surgical techniques are used.

Adult↗
PubMed1999

Anterior cervical discectomy: is fusion necessary?

OBJECT: A prospective, randomized trial was performed to compare the efficacy of anterior cervical discectomy (ACD) with ACD and fusion (ACDF) for the treatment of cervical spondylosis in patients with neurological compromise. METHODS: Forty-four patients underwent ACD and 40 underwent ACDF. Operative time and length of hospital stay were shorter and there was less need for analgesia in the ACD group. It was found that whereas the incidence of fusion was greater in the ACDF group compared to the ACD group (97 compared with 70%, respectively; p<0.01), patient satisfaction and a return to preoperative activity level was similar between groups. CONCLUSIONS: Analysis of the results suggests that the addition of a fusion procedure may be unnecessary.

Cervical Vertebrae↗
PubMed1999

One-stage posterior decompression and reconstruction of the cervical spine by using pedicle screw fixation systems.

OBJECT: This retrospective study was conducted to analyze the results of one-stage posterior decompression and reconstruction of the cervical spine by using pedicle screw fixation systems in 46 patients. METHODS: Causes of cervical myelopathy in these 46 patients included spondylosis or ossification of the posterior longitudinal ligament, rheumatoid arthritis, metastatic or primary vertebral tumors, cervical spinal injuries, and spinal cord tumor. Thirty-three patients underwent this one-stage procedure as primary surgery. In the remaining 13 patients who had previously undergone laminectomies, the one-stage procedure was performed as salvage surgery. Cervical pedicle screws were inserted into the pedicles after probing and tapping. Graft bone was placed on the bilateral lateral masses, and pedicle screws were interconnected longitudinally by either plates or rods. Postoperatively, 26 patients showed improved neurological status (at least one grade improvement on Frankel's functional classification). There were no cases of neurological deterioration postoperatively. Solid bony fusion was obtained in all patients, except in seven patients with metastatic tumor who did not receive bone grafts. Correction of kyphosis was satisfactory. Postoperative radiological evaluation revealed that 10 (5.3%) of 190 screws inserted into the cervical vertebrae had perforated the cortex of the pedicles; however, no neurovascular complications were caused by the perforations. CONCLUSIONS: The pedicle screw fixation procedure, which does not require the lamina to be used as a stabilizing anchor, has proven to be valuable when performing one-stage posterior decompressive and reconstructive surgery in the cervical spine. The risk to neurovascular structures in this procedure, however, cannot be completely eliminated. Thorough knowledge of local anatomy and application of established surgical techniques are essential for this procedure.

Adult↗
PubMed1999

Treatment of cervical compressive myelopathy with a new dorsolateral decompressive procedure.

OBJECT: A new dorsolateral decompressive procedure involving a unilateral approach has been devised for the treatment of cervical compressive myelopathy. In this operation, the posterior spinal elements of the contralateral side are not disturbed, and thus, postoperative deformity of the cervical spine can be avoided. Following decompressive surgery via the unilateral approach, the cervical spine was kept more stable compared with the results obtained after wide laminectomy or other expansive laminoplasty procedures. METHODS: Twenty-six patients underwent dorsolateral decompressive surgery, and the patients' clinical and radiological results were examined during the follow-up period to evaluate neurological function and postoperative deformities of the cervical spine. The underlying conditions for myelopathy were cervical spondylosis (19 patients), ossification of posterior longitudinal ligament (three patients), and ossification of yellow ligament (four patients). The follow-up period ranged from 6 to 110 months (average 35.5 months). Functional recovery, which was rated by using the Japanese Orthopaedic Association scoring system, was an average of 56% in all patients (100% being equal to full recovery). The recovery rate was compatible with those attained after other expansive laminoplasty procedures. Radiographically, progression to swan-neck or kyphotic deformity was not observed in any patient. No postoperative spinal instability was noted. Based on computerized tomography myelograph evaluation, the average transectional area of the dural tube at the C4-5 level was expanded from 122 mm2 to 169 mm2, and the transectional area of the spinal cord at the C4-5 level was expanded from 39.6 mm2 to 52.9 mm2 after surgery. CONCLUSIONS: The authors conclude that this operative procedure could be used as a new option for the treatment of cervical compressive myelopathy.

Adult↗
PubMed2000

Acute cervical cord injury without fracture or dislocation of the spinal column.

OBJECT: It is known that the spinal cord can sustain traumatic injury without associated injury of the spinal column in some conditions, such as a flexible spinal column or preexisting narrowed spinal canal. The purpose of this study was to characterize the clinical features and to understand the mechanisms in cases of acute cervical cord injury in which fracture or dislocation of the cervical spine has not occurred. METHODS: Eighty-nine patients who sustained an acute cervical cord injury were treated in our hospitals between 1990 and 1998. In 42 patients (47%) no bone injuries of the cervical spine were demonstrated, and this group was retrospectively analyzed. There were 35 men and seven women, aged 19 to 81 years (mean 58.9 years). The initial neurological examination indicated complete injury in five patients, whereas incomplete injury was demonstrated in 37. In the majority of the patients (90%) the authors found degenerative changes of the cervical spine such as spondylosis (22 cases) or ossification of the posterior longitudinal ligament (16 cases). The mean sagittal diameter of the cervical spinal canal, as measured on computerized tomography scans, was significantly narrower than that obtained in the control patients. Magnetic resonance (MR) imaging revealed spinal cord compression in 93% and paravertebral soft-tissue injuries in 58% of the patients. CONCLUSIONS: Degenerative changes of the cervical spine and developmental narrowing of the spinal canal are important preexisting factors. In the acute stage MR imaging is useful to understand the level and mechanisms of spinal cord injury. The fact that a significant number of the patients were found to have spinal cord compression despite the absence of bone injuries of the spinal column indicates that future investigations into surgical treatment of this type of injury are necessary.

Adult↗
PubMed2000

Single-stage anterior-posterior decompression and stabilization for complex cervical spine disorders.

OBJECT: To evaluate the applicability and safety of single-stage combined anterior-posterior decompression and fusion for complex cervical spine disorders, the authors retrospectively reviewed 72 consecutive procedures of this type performed using a uniform technique at a single center. METHODS: The indications for decompression and stabilization included: postlaminectomy kyphosis (15 patients), trauma (19 patients), spondylosis and congenital stenosis (32 patients), and ossification of the posterior longitudinal ligament (six patients). All patients underwent anterior cervical corpectomies in which allograft fibula and plates were placed, with 89% of patients undergoing two- or three-level procedures (range one-four levels). Lateral mass plating with autograft (morselized iliac crest) fusion was performed in all patients while the same anesthetic agent was still in effect. A hard cervical collar was used postoperatively in all patients (mean 13 weeks). All patients were followed for a minimum of 2 years (mean 29 months). Fusion was determined to be successful in all 72 patients (100%). Although the short-term morbidity rate reached 32%, the significant long-term morbidity rate was only 5%. At the 2-year follow-up examination, anterior cervical plate dislodgment was seen in one patient, and 16 of the 516 lateral mass screws implanted were observed to have partially backed out. However, there were no cases of nerve root injury, strut graft extrusion, or anterior plate or screw fracture. There were no clinically significant hardware complications and no patient required repeated operation. CONCLUSIONS: The combined single-stage anterior-posterior decompression, reconstruction, and instrumentation procedure represents a viable option in the treatment of a select group of patients with complex cervical spinal disorders. The technique provides immediate rigid stabilization of the cervical spine, prevents anterior plate failure or strut graft extrusion, and eliminates the need for halo immobilization postoperatively. Furthermore, a higher rate of fusion is achieved with this combined approach than with the anterior approach alone.

Adult↗
PubMed2001

Microendoscopic posterior cervical laminoforaminotomy for unilateral radiculopathy: results of a new technique in 100 cases.

OBJECT: In this report the author presents surgery-related outcomes after application of a new technique. A posterior microendoscopic laminoforaminotomy was used for the surgical treatment of unilateral cervical radiculopathy secondary to intervertebral disc herniations and/or spondylotic foraminal stenosis. The results of this procedure are compared with those achieved using traditional laminoforaminotomy and anterior cervical discectomy with or without fusion. METHODS: One hundred consecutive patients who experienced unilateral cervical radicular syndromes, which were refractory to conservative therapy, and in whom imaging studies had confirmed lateral canal or foraminal compression, underwent surgical treatment. An endoscopy-assisted posterior laminoforaminotomy was performed using a microendoscopic visualization system for removal of herniated disc and foraminal decompression while the patient was in the sitting position. Excellent or good results were obtained in 97 patients. who returned to their preoperative employment and baseline level of physical activity. One patient returned to work but was unable to perform at baseline level; two patients returned to prior sedentary work but continued to have some activity-related pain and paresthesias. Two patients reported experiencing intermittent paresthesias or numbness, but this did not limit their activities. There were two cases of dural punctures, one case of superficial wound infection, and no deaths. CONCLUSIONS: The microendoscopic posterior laminoforaminotomy is an effective alternative for the treatment of unilateral cervical radiculopathy secondary to lateral or foraminal disc herniations or spondylosis. In this group of patients, it is preferable because it does not require the sacrifice of a cervical motion segment, has a low incidence of complications, and is associated with a much quicker return to unrestricted full activity than that obtained with other techniques.

Adult↗
PubMed2002

Cervical spinal stenosis: outcome after anterior corpectomy, allograft reconstruction, and instrumentation.

OBJECT: The authors undertook a retrospective single-institution review of 261 patients who underwent anterior cervical corpectomy, reconstruction with allograft fibula, and placement of an anterior plating system for the treatment of cervical spinal stenosis to assess fusion rates and procedure-related complications. METHODS: Between October 1989 and June 1995, 261 patients with cervical stenosis underwent cervical corpectomy, allograft fibular bone fusion, and placement of instrumentation for spondylosis (197 patients), postlaminectomy kyphosis (27 patients), acute fracture (25 patients), or ossification of the posterior longitudinal ligament (12 patients). All patients suffered neck pain and cervical myelopathy or radiculopathy refractory to medical management. Of the procedures, 133 involved a single vertebral level (two disc levels and one vertebral body), 96 involved two levels, 31 involved three levels, and a single patient underwent a four-level procedure. Clinical and radiographic outcomes were assessed postoperatively and at 6-month intervals. The mean follow-up period was 25.7 months (range 24-47 months). Successful fusion was documented in 226 patients (86.6%). A stable, fibrous union developed in 33 asymptomatic patients (12.6%), whereas an unstable pseudarthrosis in two patients (0.8%) required reoperation. There were no cases of infection, spinal fluid leakage, or postoperative hematoma. Complications included transient unilateral upper-extremity weakness (two patients), dysphagia (35 transient and seven permanent), and hoarseness (35 transient and two permanent). In 14 patients (5.4%) radiological studies demonstrated evidence of hardware failure. CONCLUSIONS: Cervical corpectomy with fibular allograft reconstruction and anterior plating is an effective means of achieving spinal decompression and stabilization in cases of anterior cervical disease. Symptomatic improvement was achieved in 99.2% of patients. In their series the authors found a fusion rate of 86.6% and rates of permanent hoarseness of 3.4%, dysphagia of 0.7%, and an instrumentation failure rate of 5.4%.

Adolescent↗
PubMed2002

Influence of an artificial cervical joint compared with fusion on adjacent-level motion in the treatment of degenerative cervical disc disease.

OBJECT: The authors report the preservation of motion at surgically treated and adjacent spinal segments after placing an artificial cervical joint (ACJ) and they describe the influence of interbody fusion on changes in angulation occurring in the sagittal plane at adjacent levels in the treatment of cervical spondylosis. METHODS: The authors conducted a prospective nonrandomized study of patients in whom an ACJ was placed or autologous bone graft interbody fusion was performed. Angular measurements at levels adjacent to that surgically treated were calculated using plain flexion-extension radiographs obtained at 6-month intervals. Analyses of qualitative data, such as increase or decrease in adjacent-level motion, and the degree of disc degeneration were performed. Quantitative data were also analyzed. In the fusion group a significant increase in adjacent-level movement was demonstrated at the 12-month follow-up visit compared with the group of patients in whom ACJs were placed (p < 0.001). The increase in movement occurred predominantly at intervertebral discs that were preoperatively regarded as normal (p < 0.02). An overall reduction in adjacent-level movement was observed in patients who underwent joint replacement, although this was compensated for by the movement provided by the ACJ itself. CONCLUSIONS: Fusion results in increased motion at adjacent levels. The increase in adjacent-level motion derives from those discs that appear radiologically normal prior to surgery. It remains unknown whether ACJs have a protective influence on adjacent intervertebral discs.

Adult↗
PubMed2003

Cervical laminoplasty: evaluation of bone bonding of a high porosity hydroxyapatite spacer.

OBJECT: The purpose of this study was to evaluate the usefulness of a high-porosity hydroxyapatite (HA) spacer in cervical laminoplasty. Bone-spacer bonding rates, complications associated with the implant, and factors related to bone bonding were examined. METHODS: The authors evaluated 33 consecutive patients with cervical myelopathy who underwent high-porosity HA spacer-assisted laminoplasty and were followed for at least 1 year (mean 30 months). The results of bone-spacer bonding of the 147 implants were evaluated using computerized tomography (CT) scanning. The symptoms significantly improved in 30 patients. No difference in results was detected between patients with cervical spondylosis and those with ossification of posterior longitudinal ligament. Breakage of seven spacers occurred in four patients without causing neck pain or neurological deficits. There were no other HA spacer-related complications. The spacers became rigidly bound to bone in 61% of the cases, and bone regrowth developed around the spacer in 91%. The rate of bone-spacer bonding increased over time, and the CT-documented attenuation value (Hounsfield unit) of the spacer adjacent to the bone-spacer junction in the group in which union occurred was significantly higher than in the nonunion group. CONCLUSIONS: High-porosity HA spacer-augmented laminoplasty produced good bonding-related results. Bone bonding continued to progress 1 year after surgery, indicating the good osteoconductive capability of high-porosity HA. To avoid breakage of a spacer, a minimum 7-mm distance between spacers is necessary.

Biocompatible Materials↗