Christopher K. Kepler

AOSpine thoracolumbar spine injury classification system: fracture description, neurological status, and key modifiers.

Study Design. Reliability and agreement study, retrospective case series. Objective. To develop a widely accepted, comprehensive yet simple classification system with clinically acceptable intra- and interobserver reliability for use in both clinical practice and research. Summary of Background Data. Although the Magerl classification and thoracolumbar injury classification system (TLICS) are both well-known schemes to describe thoracolumbar (TL) fractures, no TL injury classification system has achieved universal international adoption. This lack of consensus limits communication between clinicians and researchers complicating the study of these injuries and the development of treatment algorithms. Methods. A simple and reproducible classification system of TL injuries was developed using a structured international consensus process. This classification system consists of a morphologic classification of the fracture, a grading system for the neurological status, and description of relevant patient-specific modifiers. Forty cases with a broad range of injuries were classified independently twice by group members 1 month apart and analyzed for classification reliability using the Kappa coefficient (&kgr;). Results. The morphologic classification is based on 3 main injury patterns: type A (compression), type B (tension band disruption), and type C (displacement/translation) injuries. Reliability in the identification of a morphologic injury type was substantial (&kgr;= 0.72). Conclusion. The AOSpine TL injury classification system is clinically relevant according to the consensus agreement of our international team of spine trauma experts. Final evaluation data showed reasonable reliability and accuracy, but further clinical validation of the proposed system requires prospective observational data collection documenting use of the classification system, therapeutic decision making, and clinical follow-up evaluation by a large number of surgeons from different countries. Level of Evidence: 4

The molecular basis of intervertebral disc degeneration

BACKGROUND Intervertebral disc (IVD) degeneration remains a clinically important condition for which treatment is costly and relatively ineffective. The molecular basis of degenerative disc disease has been an intense focus of research recently, which has greatly increased our understanding of the biology underlying this process. PURPOSE To review the current understanding of the molecular basis of disc degeneration. STUDY DESIGN Review article. METHODS A literature review was performed to identify recent investigations and current knowledge regarding the molecular basis of IVD degeneration. RESULTS The unique structural requirements and biochemical properties of the disc contribute to its propensity toward degeneration. Mounting evidence suggests that genetic factors account for up to 75% of individual susceptibility to IVD degeneration, far more than the environmental factors such as occupational exposure or smoking that were previously suspected to figure prominently in this process. Decreased extracellular matrix production, increased production of degradative enzymes, and increased expression of inflammatory cytokines contribute to the loss of structural integrity and accelerate IVD degeneration. Neurovascular ingrowth occurs, in part, because of the changing degenerative phenotype. CONCLUSIONS A detailed understanding of the biology of IVD degeneration is essential to the design of therapeutic solutions to treat degenerative discs. Although significant advances have been made in explaining the biologic mediators of disc degeneration, the inhospitable biochemical environment of the IVD remains a challenging environment for biological therapies.

Zone of Injury of the Medial Patellofemoral Ligament After Acute Patellar Dislocation in Children and Adolescents

Background: Patellar dislocation is a common traumatic injury in the pediatric and adolescent population. The primary constraint to lateral subluxation and dislocation of the patella is the medial patellofemoral ligament (MPFL), which serves to resist lateral translation of the patella. Injury to the MPFL may predispose to recurrent dislocation but the anatomic site of injury is poorly characterized in children and adolescents. Purpose: The authors addressed 2 questions: (1) What is the zone of injury to the MPFL in a pediatric/adolescent population after primary patellar dislocation? (2) What is the location of the femoral attachment of the MPFL with respect to the growth plate? Study Design: Cohort study (prevalence); Level of evidence, 2. Methods: Patients were eligible if they were ≤18 years of age and suffered a recent patellar dislocation characterized by magnetic resonance imaging (MRI) findings of high T2-signal intensity in the lateral femoral condyle. Patients were excluded if they had a history of prior dislocations, prior knee surgery, or congenital dislocation. Two musculoskeletal radiologists and an orthopaedic resident reviewed MRI scans of 43 children. The MPFL was divided into 3 zones: patellar insertion, femoral insertion, and midsubstance. The zone of injury was confirmed by the presence of associated soft tissue edema on short tau inversion recovery sequences and the distance from the MPFL insertion to the medial distal femoral growth plate was measured. Associated injuries were noted and the Insall-Salvati ratio was measured. Results: The MPFL injury was isolated to the patellar attachment in 61% of patients and to the femoral attachment in 12%. Twelve percent of patients had injury at both the patellar and femoral attachments. Six percent had no identifiable MPFL injury and 9% had combinations of midsubstance and either patellar or femoral attachment injuries. The kappa value for injury determinations was 0.71, indicating substantial concordance. The MPFL insertion site averaged 5 mm distal to the medial physis. Eighty-six percent of patients had an MPFL insertion distal to the growth plate, 7% had an insertion at the physis, while only 7% had a proximal insertion. The incidence of associated chondral injuries, the value of the Insall-Salvati ratio, and the location of MPFL insertion did not vary significantly with location of MPFL injury. Sixteen patients (36%) had MPFL insertions that were within 5 mm (either proximal or distal) of the growth plate. Conclusion: The zone of MPFL injury in a pediatric population after primary patellar dislocation was predominantly isolated to the patellar attachment (61%), in contrast to previous literature. Twelve percent of patients had injury only at the femoral attachment, while 12% of patients had injury to both the patellar and femoral attachments. The remaining 15% had injury at multiple locations or no identifiable injury. The MRI finding that the anatomic insertion of the MPFL is distal to the physis in 93% of patients and that the MPFL is more likely to be injured at the patellar attachment has important implications in the surgical reconstruction of the MPFL in pediatric or adolescent patients.

CT Outperforms Radiography for Determination of Acetabular Cup Version after THA

Precise evaluation of acetabular cup version is necessary for patients with recurrent hip dislocation after THA. We retrospectively studied 42 patients, who underwent THAs, with multiple cross-table lateral radiographs and CT scans to determine whether radiographic or CT measurement of acetabular component version is more accurate. One observer measured cup version on all radiographs. CT scans were interpreted by one observer. Twenty radiographs were measured twice each by two observers to determine intraobserver and interobserver reliability. We implanted cups in four model pelvises using navigation and compared measurements of anteversion made with radiographs and CT scans. Intraclass correlation coefficients (ICC) for anteversion measurements of two observers were 0.9990 and 0.9998, respectively, when comparing measurements of identical radiographs (intraobserver). Paired values for two observers measuring the same radiograph had an ICC of 0.9686 (interobserver) compared with 0.7412 for measurements from serial radiographs of the same component. The ICC comparing radiographic versus CT-based measurements was 0.6981. CT measurements had stronger correlations with navigated values than radiographic measurements. Accuracy of anteversion measurements on cross-table radiographs depends on radiographic technique and patient positioning whereas properly performed CT measurements are independent of patient position.Level of Evidence: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Adjacent segment disease in the lumbar spine following different treatment interventions.

BACKGROUND CONTEXT Adjacent segment disease (ASD) is symptomatic deterioration of spinal levels adjacent to the site of a previous fusion. A critical issue related to ASD is whether deterioration of spinal segments adjacent to a fusion is due to the spinal intervention or due to the natural history of spinal degenerative disease. PURPOSE The purpose of this review is to summarize the recent clinical literature on adjacent segment disease in light of the natural history, patient-modifiable risk factors, surgical risk factors, sagittal balance, and new technology. STUDY DESIGN This review will evaluate the recent literature on genetic and hereditary components of spinal degenerative disease and potential links to the development of ASD. METHODS After a meticulous search of Medline for relevant articles pertaining to our review, we summarized the recent literature on the rate of ASD and the effect of various interventions, including motion preservation, sagittal imbalance, arthroplasty, and minimally invasive surgery. RESULTS The reported rate of ASD after decompression and stabilization procedures is approximately 2% to 3% per year. The factors that are consistently associated with adjacent segment disease include laminectomy adjacent to a fusion and a sagittal imbalance. CONCLUSIONS Spinal surgical interventions have been associated with ASD. However, whether such interventions may lead to an acceleration of the natural history of the disease remains questionable.

Indirect foraminal decompression after lateral transpsoas interbody fusion.

OBJECT Lateral transpsoas interbody fusion (LTIF) permits anterior column lumbar interbody fusion via a direct lateral approach. The authors sought to answer 3 questions. First, what is the effect of LTIF on lumbar foraminal area? Second, how does interbody cage placement affect intervertebral height? And third, how does the change in foraminal area and cage position correlate with changes in Oswestry Disability Index (ODI) and 12-Item Short Form Health Survey (SF-12) scores? METHODS Included patients underwent LTIF with or without posterior instrumentation and received preoperative and postoperative CT scans. Disc heights, neural foraminal area between adjacent-level pedicles, and anteroposterior cage position were measured from sagittal CT images. Preoperative and postoperative ODI and SF-12 scores were matched with the change in foraminal area from the clinically most severely affected side for analysis of the relationship between outcomes instruments and change in foraminal area. RESULTS Average foraminal area increased by 36.2 mm(2), or 35% of the preoperative area (p < 0.01), without statistically significant differences by side, level, or anteroposterior cage position. Preoperative anterior and posterior disc heights measured 6.2 mm and 3.7 mm, respectively, compared with postoperative measurements of 9.8 mm (p < 0.01) and 6.3 mm (p < 0.01), respectively, without significant differences by level or cage position. Despite significant overall improvement in ODI and SF-12 scores, there was no correlation with foraminal area increase. CONCLUSIONS Average foraminal area increased approximately 35% after cage placement without variation based on cage position. While ODI and SF-12 scores increased significantly, there was no significant association with cage position or foraminal area change, likely attributable to the multifactorial nature of preoperative pain.

Functional and quality-of-life outcomes in geriatric patients with type-II dens fracture.

BACKGROUND Dens fractures are relatively common in the elderly. The treatment of Type-II dens fractures remains controversial. The aim of this multicenter prospective cohort study was to compare outcomes (assessed with use of validated clinical measures) and complications of nonsurgical and surgical treatment of Type-II dens fractures in patients sixty-five years of age or older. METHODS One hundred and fifty-nine patients with a Type-II dens fracture were enrolled in a multicenter prospective study. Subjects were treated either surgically (n = 101) or nonsurgically (n = 58) as determined by the treatment preferences of the treating physicians and the patients. The subjects were followed at six and twelve months with validated outcome measures, including the Neck Disability Index (NDI) and Short Form-36v2 (SF-36v2). Treatment complications were prospectively recorded. Statistical analysis was performed to compare outcome measures before and after adjustment for confounding variables. RESULTS The two groups were similar with regard to baseline characteristics. The most common surgical treatment was posterior C1-C2 arthrodesis (eighty of 101, or 79%) while the most common nonsurgical treatment was immobilization with use of a hard collar (forty-seven of fifty-eight, or 81%). The overall mortality rate was 18% over the twelve-month follow-up period. At twelve months, the NDI had increased (worsened) by 14.7 points in the nonsurgical cohort (p < 0.0001) compared with a nonsignificant increase (worsening) of 5.7 points in the surgical group (p = 0.0555). The surgical group had significantly better outcomes as measured by the NDI and SF-36v2 Bodily Pain dimension compared with the nonsurgical group, and these differences persisted after adjustment. There was no difference in the overall rate of complications, but the surgical group had a significantly lower rate of nonunion (5% versus 21% in the nonsurgical group; p = 0.0033). Mortality was higher in the nonsurgical group compared with the surgical group (annual mortality rates of 26% and 14%, respectively; p = 0.059). CONCLUSIONS We demonstrated a significant benefit with surgical treatment of dens fractures as measured by the NDI, a disease-specific functional outcome measure. As a result of the nonrandomized nature of the study, the results are vulnerable to the effects of possible residual confounding. We recommend that elderly patients with a Type-II dens fracture who are healthy enough for general anesthesia be considered for surgical stabilization to improve functional outcome as well as the union and fusion rates.

Postoperative infections of the lumbar spine: presentation and management.

PurposePostoperative surgical site infections (SSI) are a frequent complication following posterior lumbar spinal surgery. In this manuscript we review strategies for prevention, diagnosis and treatment of SSI.MethodsThe literature was reviewed using the Pubmed database.ResultsWe identified fifty-nine relevant manuscripts almost exclusively composed of Level III and IV studies.ConclusionsRisk factors for SSI include: 1) factors related to the nature of the spinal pathology and the surgical procedure and 2) factors related to the systemic health of the patient. Staphylococcus aureus is the most common infectious organism in reported series. Proven methods to prevent SSI include prophylactic antibiotics, meticulous adherence to aseptic technique and frequent release of retractors to prevent myonecrosis. The presentation of SSI is varied depending on the virulence of the infectious organism. Frequently, increasing pain is the only presenting complaint and can lead to a delay in diagnosis. Magnetic resonance imaging and the use of C-reactive protein laboratory studies are useful to establish the diagnosis. Treatment of SSI is centered on surgical debridement of all necrotic tissue and obtaining intra-operative cultures to guide antibiotic therapy. We recommend the involvement of an infectious disease specialist and use of minimum serial bactericidal titers to monitor the efficacy of antibiotic treatment. In the most cases, SSI can be adequately treated while leaving spinal instrumentation in place. For severe SSI, repeat debridement, delayed closure and involvement of a plastic surgeon may be necessary.

Expression and relationship of proinflammatory chemokine RANTES/CCL5 and cytokine IL-1β in painful human intervertebral discs.

Study Design. Laboratory study. Objective. To evaluate expression of chemokine regulated and normal T cell expressed and secreted (RANTES)/C-C motif ligand 5 (CCL5) and interleukins in intervertebral discs (IVDs) specimens from patients with discogram-proven painful degeneration. Summary of Background Data. Discogenic back pain results in tremendous costs related to treatment and lost productivity. The relationship between inflammation, degeneration (IVD), and cytokine upregulation is well established, but other mediators of the inflammatory cascade are not well characterized. Methods. Painful IVDs were taken from 18 patients undergoing surgery for discogenic pain with positive preoperative discogram. Painless control tissue was taken at autopsy from patients without back pain/spinal pathology or spinal levels with negative discograms resected for deformity. Quantitative real time polymerase chain reaction (qRT-PCR) was performed to evaluate RANTES, IL-1&bgr;, IL-6, and IL-8 expression in painful and control discs. RANTES and interleukin expression were analyzed on the basis of Pfirrmann grade. Disc cells were cultured in alginate beads using 2 groups: an untreated group and a group treated with 10 ng/mL IL-1&bgr;, 10 ng/mL TNF-&agr;, and 1% fetal bovine serum to induce a degenerative phenotype. Results. Nine painless IVD specimens and 7 painful IVD specimens were collected. RANTES expression demonstrated a 3.60-fold increase in painful discs versus painless discs, a significant difference (P = 0.049). IL-1&bgr; expression demonstrated significantly higher expression in painful discs (P = 0.03). RANTES expression data demonstrated significant upregulation with increasing Pfirrmann grade (P = 0.045). RANTES expression correlated significantly with IL-1&bgr; expression (&rgr; = 0.67, P < 0.0001). RANTES expression increased more than 200-fold in the alginate culture model in cells treated with IL-1&bgr;/TNF-&agr;, 1% fetal bovine serum (P < 0.001). Conclusion. RANTES and IL-1&bgr; expression was significantly elevated in painful IVDs after careful selection of painless versus painful IVD tissue. RANTES expression was found to correlate significantly with expression of IL-1&bgr;. RANTES was upregulated by IL-1&bgr;/TNF-&agr;/1% fetal bovine serum an in vitro treatment to induce a degenerative phenotype.

Reverse total shoulder arthroplasty: Current concepts, results, and component wear analysis

After its introduction in the 1970s, reverse total shoulder arthroplasty had minimal clinical success, as its constrained design and lateralized glenohumeral center of rotation led to excessive shear forces and failure of the glenoid component1,2. Modern implant design modifications have emphasized a larger radius of curvature of the glenoid component and movement of the center of shoulder rotation medially and distally, creating a more stable and efficient fulcrum and decreasing shear forces at the glenoid-bone interface3,4. Since receiving U.S. Food and Drug Administration (FDA) approval in 2003, reverse total shoulder arthroplasty has become popular for use for more than rotator cuff-tear arthropathy; its uses include treatment of failed conventional total shoulder arthroplasties, rheumatoid arthritis in patients with an irreparable cuff tear, proximal humeral tumors, and proximal humeral fractures with anterosuperior escape5,6. However, with major complication rates as high as 26%7, limited implant longevity, and a lack of long-term functional outcome data, concerns have continued about its widespread use2. ### Source of Funding There was no external funding source for this investigation. Without injury, the glenohumeral joint possesses remarkable mobility and is able to remain stable over the majority of an individual’s life span. While both static and dynamic restraints contribute to its stability, the glenohumeral joint lacks substantial intrinsic osseous constraints8,9. Although the glenoid and the humeral head have similar shapes, they differ substantially in size. Warner demonstrated that the spherical humeral head has an articular surface area of approximately 21 to 22 cm2, while that of the glenoid is 8 to 9 cm2, with a maximum contact area of only 4 to 5 cm2 between the two surfaces10. This limited contact area and the shallow glenoid …