Evaluation of Two Novel Integrated Stand-Alone Spacer Designs Compared with Anterior and Anterior-Posterior Single-Level Lumbar Fusion Techniques: An In Vitro Biomechanical Investigation.

STUDY DESIGN: In vitro biomechanical investigation. PURPOSE: To compare the biomechanics of integrated three-screw and four-screw anterior interbody spacer devices and traditional techniques for treatment of degenerative disc disease. OVERVIEW OF LITERATURE: Biomechanical literature describes investigations of operative techniques and integrated devices with four dual-stacked, diverging interbody screws; four alternating, converging screws through a polyether-ether-ketone (PEEK) spacer; and four converging screws threaded within the PEEK spacer. Conflicting reports on the stability of stand-alone devices and the influence of device design on biomechanics warrant investigation. METHODS: Fourteen cadaveric lumbar spines were divided randomly into two equal groups (n=7). Each spine was tested intact, after discectomy (injured), and with PEEK interbody spacer alone (S), anterior lumbar plate and spacer (AP+S), bilateral pedicle screws and spacer (BPS+S), circumferential fixation with spacer and anterior lumbar plate supplemented with BPS, and three-screw (SA3s) or four-screw (SA4s) integrated spacers. Constructs were tested in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Researchers performed one-way analysis of variance and independent t-testing (p≤0.05). RESULTS: Instrumented constructs showed significantly decreased motion compared with intact except the spacer-alone construct in FE and AR (p≤0.05). SA3s showed significantly decreased range of motion (ROM) compared with AP+S in LB (p≤0.05) and comparable ROM in FE and AR. The three-screw design increased stability in FE and LB with no significant differences between integrated spacers or between integrated spacers and BPS+S in all loading modes. CONCLUSIONS: Integrated spacers provided fixation statistically equivalent to traditional techniques. Comparison of three-screw and four-screw integrated anterior lumbar interbody fusion spacers revealed no significant differences, but the longer, larger-diameter interbody spacer with three-screw design increased stabilization in FE and LB; the diverging four-screw design showed marginal improvement during AR.

Is polymethyl methacrylate a viable option for salvaging lateral mass screw failure in the subaxial cervical spine?

Study Design Biomechanical analysis of lateral mass screw pullout strength. Objective We compare the pullout strength of our bone cement-revised lateral mass screw with the standard lateral mass screw. Methods In cadaveric cervical spines, we simulated lateral mass screw "cutouts" unilaterally from C3 to C7. We salvaged fixation in the cutout side with polymethyl methacrylate (PMMA) or Cortoss cement (Orthovita, Malvern, Pennsylvania, United States), allowed the cement to harden, and then drilled and placed lateral mass screws back into the cement-augmented lateral masses. On the contralateral side, we placed standard lateral mass screws into the native, or normal lateral, masses and then compared pullout strength of the cement-augmented side to the standard lateral mass screw. For pullout testing, each augmentation group was fixed to a servohydraulic load frame and a specially designed pullout fixture was attached to each lateral mass screw head. Results Quick-mix PMMA-salvaged lateral mass screws required greater force to fail when compared with native lateral mass screws. Cortoss cement and PMMA standard-mix cement-augmented screws demonstrated less strength of fixation when compared with control-side lateral mass screws. Attempts at a second round of cement salvage of the same lateral masses led to more variations in load to failure, but quick-mix PMMA again demonstrated greater load to failure when compared with the nonaugmented control lateral mass screws. Conclusion Quick-mix PMMA cement revision equips the spinal surgeon with a much needed salvage option for a failed lateral mass screw in the subaxial cervical spine.

Surgical strategies to improve fixation in the osteoporotic spine: the effects of tapping, cement augmentation, and screw trajectory.

Study Design Biomechanical study of pedicle screw fixation in osteoporotic bone. Objective To investigate whether it is better to tap or not tap osteoporotic bone prior to placing a cement-augmented pedicle screw. Methods Initially, we evaluated load to failure of screws placed in cancellous bone blocks with or without prior tapping as well as after varying the depths of tapping prior to screw insertion. Then we evaluated load to failure of screws placed in bone block models with a straight-ahead screw trajectory as well as with screws having a 23-degree cephalad trajectory (toward the end plate). These techniques were tested with nonaugmented (NA) screws as well as with bioactive cement (BioC) augmentation prior to screw insertion. Results In the NA group, pretapping decreased fixation strength in a dose-dependent fashion. In the BioC group, the tapped screws had significantly greater loads to failure (p < 0.01). Comparing only the screw orientation, the screws oriented at 23 degrees cephalad had a significantly higher failure force than their respective counterparts at 0 degrees (p < 0.01). Conclusions Standard pedicle screw fixation is often inadequate in the osteoporotic spine, but this study suggests tapping prior to cement augmentation will substantially improve fixation when compared with not tapping. Angulating screws more cephalad also seems to enhance aging spine fixation.

Hip flexion contracture and diminished functional outcomes in cerebral palsy.

BACKGROUND: Hip flexion contracture (HFC) in the ambulatory child with cerebral palsy (CP) may impair function and lead to deteriorations in health-related quality of life. Furthermore, increasing HFC may lead to increasing disability. However, the association between passive range of motion and the measures of function and well-being is unclear. This study was designed to determine whether increasing HFC is associated with functional outcome. METHODS: A total of 181 children, with an average age of 14.0 ± 10.2 years, were evaluated as part of a multicenter prospective data collection of patients with ambulatory CP. Measurements of HFC were recorded, and patients were evaluated using walking score from Gillette Functional Assessment Questionnaire (FAQ), Gross Motor Function Measure (GMFM), and the Pediatric Outcome Data Collection Instrument (PODCI). Patients were grouped on the basis of severity of HFC: group A, 0 to 14 degrees; group B, 15 to 29 degrees; and group C ≥ 30 degrees. Associations were examined using the Spearman correlation. RESULTS: There was an inverse association between degree of HFC and FAQ walking score (P<0.01, ρ=-0.25). Similarly, there was an inverse association between the degree of HFC and GMFM parts D (P<0.001, ρ=-0.31) and E (P<0.001, ρ=-0.32). Lastly, the PODCI domains of global function, mobility, and physical function also showed an inverse association with degree of HFC (P<0.001, ρ=-0.24). CONCLUSIONS: As surgeons treating children with CP, we often rely on joint measurements as an indirect measure of function. This study of children with ambulatory CP suggests that increased HFC from the physician's perspective is associated with deterioration in function from a patient and a therapist's perspective. LEVEL OF EVIDENCE: Level II, prospective study.

Ketorolac and spinal fusion: does the perioperative use of ketorolac really inhibit spinal fusion?

STUDY DESIGN: Retrospective review. OBJECTIVE: To evaluate the effect of postoperative use of ketorolac (Toradol) on spinal fusion in humans. SUMMARY OF BACKGROUND DATA: The value of parenteral ketorolac in postoperative analgesia has been well documented across surgical specialties. However, some studies have shown that ketorolac may adversely affect osteogenic activity and fracture healing. METHODS: A total of 405 consecutive patients who underwent primary lumbar posterolateral intertransverse process fusion with pedicle screw instrumentation were included in this retrospective study. A subtotal of 228 patients received Toradol after surgery for adjunctive analgesia. Each patient received a mandatory dose of 30 mg intravenously every 6 hours for 48 hours. The same surgeon performed the fusion procedure on all of these patients. Historical controls included 177 patients who did not receive Toradol after surgery. The minimum follow-up period was 24 months. Nonunions were diagnosed by analyzing sequential radiographs, flexion-extension radiographs, and computed tomography with multiplanar reconstructions. The gold standard of surgical exploration was performed in symptomatic patients with diagnostic ambiguity or nonunions diagnosed by imaging. RESULTS: There were no smokers in the study population. Pseudarthrosis was identified in 12 of 228 patients (5.3%) who received Toradol after surgery, and in 11 of 177 patients (6.2%) who did not. There was no significant difference detected in the nonunion rates between the two groups (P > 0.05, chi2 method). CONCLUSION: Use of ketorolac after spinal fusion surgery in humans, limited to 48 hours after surgery for adjunctive analgesia, has no significant effect on ultimate fusion rates.

Operative treatment of adolescent idiopathic scoliosis with posterior pedicle screw-only constructs: minimum three-year follow-up of one hundred fourteen cases.

STUDY DESIGN: Preoperative review of a prospective study, single institution, consecutive series. OBJECTIVE.: To analyze the intermediate-term follow-up of consecutive adolescent idiopathic scoliosis (AIS) patients treated with pedicle screw constructs. SUMMARY OF BACKGROUND DATA: There have been no reports of the intermediate-term findings in North America following posterior spinal fusion with the use of pedicle screw-only constructs. METHODS: One hundred and fourteen consecutive patients having a minimum 3-year follow-up (mean 4.8 +/- 1.1; range, 3.0-7.3 years) with AIS were evaluated. The average age at surgery was 14.9 +/- 2.2 years. Radiographic measurements included preoperative (Preop), postoperative (PO), 2-year (2 years), and final follow-up (FFU). A chart review evaluated PFTs, Scoliosis Research Society scores, presence of thoracoplasty, Risser sign, Lenke classification, and complications. RESULTS: The most frequent curve pattern was Lenke type 1 (45.6%), followed by type 3 (21.9%). The average main thoracic curve measured 59.2 degrees +/- 12.2 SD Preop, and corrected to 16.8 degrees +/- 9.9 PO (P < 0.0001). Sagittal thoracic alignment (T5-T12) decreased from 25.8 degrees to 15.5 degrees at FFU (P = 0.05). Nash-Moe grading for apical vertebral rotation (AVR) in the proximal thoracic curve decreased from 2.0 Preop to 1.1 at FFU (P < 0.0001), and AVR in the thoracolumbar/lumbar spine decreased from 1.6 Preop to 1.1 at FFU (P < 0.0001). Importantly, the horizontalization of the subjacent disc measured -8.3 degrees Preop which decreased to -0.9 degrees PO (P < 0.001). PFT follow-up averaged 2.4 years with a 7.1% improvement in FVC (P = 0.004) and 8.8% in FEV1 (P < 0.0001). SRS scores averaged 83.0% at latest follow-up. Age, gender, Risser sign, or complications did not have a significant effect on outcomes. There were 2 cases of adding-on, 3 late onset infections, 1 with a single pseudarthrosis, but no neurologic complications. CONCLUSION: This is the largest (N = 114), consecutive series of North American patients with AIS treated with pedicle screws having a minimum of 3-year follow-up. The average curve correction was 68% for the main thoracic, 50% for the proximal thoracic, and 66% for the thoracolumbar/lumbar curve at final follow-up.

Surgical management of posttraumatic thoracolumbar kyphosis.

BACKGROUND CONTEXT: Spine trauma is relatively common, and each year approximately 10,000 to 17,000 people in the United States will sustain a spinal cord injury and approximately 150,000 to 160,000 will fracture their spinal column. Posttraumatic spinal deformity is a common potential complication of spinal injury and poses one of the greatest challenges in spinal surgery. PURPOSE: To provide a comprehensive and current review of posttraumatic deformity focusing on the epidemiology, clinical and radiographical presentation, treatment options, and prognosis. STUDY DESIGN/SETTING: A thorough review of the English literature on the management of posttraumatic deformity was performed. Pertinent articles were identified by using PubMed and a review of publications by the American Academy of Orthopaedic Surgeons. METHODS: Each article was reviewed, and findings were analyzed to formulate a concise review of current treatment methods for posttraumatic deformity. RESULTS: Successful treatment of posttraumatic deformity is dependent on careful patient selection and appropriate surgical intervention, which should be considered in the presence of significant or increasing deformity, increasing back and/or leg pain, "breakdown" at levels above or below the deformity, pseudarthrosis or malunion, and increasing neurological deficit. The goals of surgery should be to decompress the neural elements if neurological claudication or a neurological deficit is present, to recreate normal sagittal contours and balance, and to optimize the chances for successful fusion; these goals can be achieved through an all-anterior, all-posterior, or a combined anterior/posterior approach assuming that close attention is paid to using the appropriate bone-grafting techniques, selecting technically sound segmental instrumentation, and providing appropriate biomechanical environment for maintenance of correction and successful fusion. CONCLUSIONS: Posttraumatic spinal deformity is a common complication of spinal injury, and it is therefore essential for patients with vertebral column injuries to have a careful initial evaluation, close follow-up, and early intervention when needed. Once posttraumatic deformity is present, successful outcome is achievable assuming a thorough, systematic, and technically well-executed surgical intervention is performed.

Thoracolumbar deformity arthrodesis stopping at L5: fate of the L5-S1 disc, minimum 5-year follow-up.

STUDY DESIGN: A retrospective long-term follow-up study. OBJECTIVE: Evaluate the fate of L5-S1 disc analyzing subsequent disc degeneration and associated risk factors for degeneration at minimum 5-year follow-up (average 9-year follow-up). SUMMARY OF BACKGROUND DATA: Two previous studies reported the results of long deformity fusions terminating at L5 with minimum 2-year follow-up only. METHODS: Thirty-one consecutive patients with an average age of 45 years (range, 20-62 years) were fused from the thoracic spine to L5 and were evaluated at a mean follow-up of 9.4 years (range, 5-20.1 year). Patients were evaluated before surgery, after surgery, and latest follow-up with radiographs and Scoliosis Research Society Patient Questionnaire-24 scores. Disc degeneration using validated radiographic Weiner grades. Grade 0 to 1 discs were "healthy" and Grade 2 to 3 were degenerated. Patients with "healthy" discs preoperative that subsequently degenerated were designated subsequent advanced degeneration (SAD). RESULTS: Two out of 31 patients had preoperative advanced degeneration of the L5-S1 disc (Weiner grade 2-3). Three additional patients had an early revision to the sacrum secondary to sagittal imbalance not thought to be related to SAD. Twenty-six out of 31 patients were assessed as "healthy discs" preoperative (Weiner grade 0-1) and were evaluated for SAD. By latest follow-up, L5-S1 SAD developed in 18 of these 26 patients (69%). Risk factors for the development of SAD included long fusions extending into the upper thoracic spine down to L5 (P = 0.02) and having a circumferential lumbar fusion (P = 0.02). Although preoperative sagittal balance was not significantly different between the "healthy" and SAD group, sagittal balance at follow-up was: C7 plumb >5 cm in 67% of SAD patients and only 13% of "healthy" disc patients (P = 0.009). There was a trend toward inferior Scoliosis Research Society Patient Questionnaire-24 pain scores at follow-up in SAD patients (average score 4.1 vs. 3.4, P = 0.13). Eleven out of 30 patients (35%) had subsequent spinal surgery with 7 of 31 (23%) having extension of their fusion to the sacrum. An additional 6 of 31 (19%) were considered for extension to the sacrum but comorbidities precluded surgery (3 patients) or the patients declined further surgery (3 patients). CONCLUSION: Advanced L5-S1 DDD developed in 69% of deformity patients after long fusions to L5 with 5 to 15 year follow-up. SAD frequently results in significant positive sagittal balance at a minimum 5-year follow-up. Long fusions to the upper thoracic spine down to L5 and circumferential fusion may further promote subsequent L5-S1 disc degeneration.

Neurologic complications of lumbar pedicle subtraction osteotomy: a 10-year assessment.

STUDY DESIGN: Clinical, radiographic, and outcomes assessment focusing on neurologic complications in patients undergoing pedicle subtraction osteotomy (PSO). Clinical data were collected prospectively. Radiographic analysis was performed retrospectively. OBJECTIVE: To evaluate intraoperative and postoperative neurologic deficits following lumbar PSOs in order to determine risk factors, treatment strategies, and patient outcome. SUMMARY OF BACKGROUND DATA: Although technically demanding, PSOs have been increasingly used to restore lumbar lordosis and correct sagittal deformity. Although some reports have commented on various complications of the procedure, to our knowledge, there have been no studies focusing on neurologic complications of the osteotomy. METHODS: An analysis of 108 consecutive patients with an average age of 54.8 +/- 14.0 years and treated with a lumbar PSO at 1 institution over a 10-year period (1995-2005) was performed. Medical records, radiographs, and neuromonitoring data were analyzed. Clinical outcome was assessed using the Oswestry Disability Index and the Scoliosis Research Society (SRS)-24 instruments. RESULTS: A total of 108 PSOs were performed. Following surgery, lumbar lordosis increased from -17.1 degrees +/- 19.3 degrees to -49.3 degrees +/- 14.7 degrees (P < 0.000), and sagittal balance improved from 131 +/- 73 mm to 23 +/- 48 mm (P < 0.000). Intraoperative and postoperative deficits (defined as motor loss of 2 grades or more or loss of bowel/bladder control) were seen in 12 patients (11.1%) and were permanent in 3 patients (2.8%). With time motor function improved by 1 grade in 2 patients and all 3 were able to ambulate. Intraoperative neuromonitoring did not detect the deficits. In 9 patients, additional surgical intervention consisted of central enlargement and further decompression. Deficits were thought to be due to a combination of subluxation, residual dorsal impingement, and dural buckling. CONCLUSION: Intraoperative or postoperative neurologic deficits are relatively common following a PSO; however, in a majority of cases, deficits are not likely to be permanent.

An outcomes analysis of the treatment of cervical pseudarthrosis with posterior fusion.

STUDY DESIGN: A retrospective review of 33 consecutive patients treated with posterior fusion and selective nerve root decompression for the treatment of pseudarthrosis following anterior cervical discectomy and fusion. OBJECTIVES: Use standardized outcome measures to evaluate the results of posterior fusion with selective nerve root decompression as a treatment option for symptomatic pseudarthrosis of the cervical spine. SUMMARY OF BACKGROUND DATA: Pseudarthrosis after anterior cervical discectomy and fusion has been recognized as a cause of continued cervical pain and unsatisfactory outcomes. Debate continues as to whether a revision anterior approach or a posterior fusion procedure is the best treatment for symptomatic cervical pseudarthrosis. To our knowledge, standardized outcome measures have not been used to evaluate the results of either surgical treatment option; therefore, it is difficult to evaluate outcomes in these patients, let alone compare surgical treatment options. Data on fusion rates in these two surgical treatment groups suggest a trend of a higher fusion rate with utilization of a posterior revision procedure, but the largest study to date includes the study of only 19 patients treated with a posterior fusion. METHODS: Thirty-three consecutive patients with symptomatic pseudarthrosis following anterior cervical discectomy and fusion were treated with selective nerve root decompression and posterior fusion using iliac crest or local bone graft as well as posterior wiring and/or lateral mass plating. The average follow-up period was 46 months (range, 20-86 months). Patients were assessed using physical examination, flexion-extension lateral radiographs, and standardized outcome measures including the SF-36, Arthritis Impact Measurement Scales 2, and Cervical Spine Outcomes Questionnaire. RESULTS: All 33 patients (100%) demonstrated a solid fusion at their most recent follow-up, and all 33 patients noted significant improvement in their preoperative symptoms. No difference in fusion status was noted between those treated with iliac crest versus patients treated with local bone graft--all had a solid fusion; 72% of the patients were satisfied with the result of their surgery. Cervical Spine Outcomes Questionnaire pain scales demonstrated 52% of patients reported mild or nopain at follow-up, whereas 20% described their pain as "discomforting" and 28% of the patients continued to report moderate to severe pain. CONCLUSIONS: This is the first study to our knowledge to use standardized outcome measures to assess clinical outcome in patients treated with posterior fusion for pseudarthrosis after anterior cervical discectomy and fusion. Patients and surgeons need to understand the potential for success with this revision procedure but also be aware of the relatively high rate of continued moderate to severe pain observed in this patient population even after a solid fusion is achieved. All of the patients in this study fused with a single posterior fusion procedure, further supporting the relatively higher fusion rates observed in the literature using posterior fusion as a treatment for cervical pseudarthrosis. Our results also support the ability of surgeons to use local bone graft without iliac crest in a posterior fusion for cervical pseudarthrosis and therefore avoid the morbidity associated with iliac crest bone graft harvest.

Calcaneocuboid fusion in children undergoing talectomy.

The aim of management of the child with a severe, rigid equinovarus foot is to provide a foot that is plantigrade and painless and can be placed within standard footwear. The authors identified a retrospective cohort of 17 children with a mean age at surgery of 5.6 years (range 2.3-9.6 years) who underwent 31 talectomy procedures for the management of their rigid, equinovarus foot deformities (14 isolated talectomies, 17 combined talectomy and calcaneocuboid fusions). The underlying diagnosis was predominantly arthrogryposis. The average follow-up was 9.7 years (range 2.3-9.5 years) and 3.8 years (range 2.8-9.6 years) respectively. The addition of calcaneocuboid fusion prevented the development of postoperative equinus, varus, adductus, and supination deformities as determined by clinical examination at medium-term follow-up (P = 0.01, P < 0.001, P < 0.001, P < 0.001, P < 0.01, respectively). This was associated with a decreased incidence of recurrent foot pain with weightbearing (P < 0.001) and a reduced need for revision surgery for pain or deformity (P < 0.001). This study determined that the addition of a concomitant calcaneocuboid fusion in the setting of talectomy may improve the medium-term surgical outcome.

Hematoma and distraction arthroplasty for basal thumb osteoarthritis.

Many surgeons have abandoned the simple trapeziectomy for the treatment of thumb basal joint arthritis secondary to reports of postoperative weakness. More recently, ligament reconstruction techniques have been the favored surgical procedure for the treatment of trapezial arthritis, but the necessity of such an extensive procedure that requires tendon harvest and rerouting has come into question. Simple trapeziectomy modified with distraction pinning, without interposition grafting, allows for a stable, pain-free thumb that has superior strength and motion when compared with the more complicated ligament reconstruction techniques.

Growth rates in skeletally immature feet after triple arthrodesis.

Many authors delay triple arthrodesis in skeletally immature patients secondary to the belief that such a surgery would cause excessive shortening in a foot that is often already short. In the current study, foot growth rates were compared between a group of skeletally immature patients (<11 years) and a group of more skeletally mature patients (>11 years) after triple arthrodesis. The average age at surgery in the skeletally immature group was 9.8 years, with a mean follow-up of 3.4 years, and the average age at surgery in the more skeletally mature group was 13.6 years, with a mean follow-up of 2.5 years. No statistically significant differences in length or height growth rates after triple arthrodesis were found between the two groups. The incidence of pseudoarthrosis and residual deformity in both groups was comparable with other studies in the literature. This study does not support the belief that triple arthrodesis to correct hindfoot deformity, instability, or relief of pain should be restricted to the older child.

Hematoma and distraction arthroplasty for thumb basal joint osteoarthritis: a prospective, single-surgeon study including outcomes measures.

PURPOSE: Many surgeons have abandoned the simple trapeziectomy as a surgical treatment option for thumb basal joint arthritis secondary to reports of postoperative weakness. The thumb metacarpal subsiding into the trapezial void has been proposed as the causative factor. The goal of the present study was to evaluate the results of trapeziectomy and postoperative K-wire immobilization of the thumb metacarpal in a distracted position without the use of ligament reconstruction or tendon interposition. METHODS: Twenty-six thumbs in 26 patients from a single surgeon's practice were entered into a prospective single-arm study for surgical treatment of peritrapezial arthritis. Treatment consisted of piecemeal excision of the entire trapezium and 5 weeks of K-wire immobilization of the first metacarpal in slight distraction and opposition. No ligament reconstruction or tendon interposition was used. Motion, strength, stress radiographs, standardized dexterity tests, and outcomes questionnaires including the Arthritis Impact Measurement Scales 2 (AIMS2) were evaluated before surgery and 6 and 24 months after surgery. RESULTS: At 6 months 19 of 26 patients (73%) reported complete relief of pain and at 24 months 92% were entirely pain free. Range of motion evaluation showed 24 of 26 thumbs adducted fully into the plane of the palm and 25 of 26 opposed to the fifth metacarpal head. Comparisons between preoperative and 24-month postoperative strength measurements showed an average 47% increase in grip strength, 33% increase in key pinch strength, and a 23% increase in tip pinch strength over preoperative values. AIMS2 data showed postoperative improvement in "hand and finger function" and "arthritis pain" scales. CONCLUSIONS: After trapezial excision K-wire immobilization in a slightly overcorrected position without tissue interposition or ligament reconstruction restores a stable, pain-free thumb that has superior strength and motion compared with published reports of the more complicated interventions.