Introduction to Additive Manufacturing and Three-Dimensional Printing in Orthopaedics.

Additive manufacturing involves the construction of devices via the layer-by-layer deposition of materials. Additive manufacturing, which also is referred to as three-dimensional printing, is different from traditional machining, which involves the subtraction of material from a workpiece. Although traditional machining methods have been used in the field of manufacturing for decades, a recent rise in the commercial use of additive manufacturing has occurred in the field of orthopaedic surgery. Orthopaedic surgeons should understand the pertinent history of three-dimensional printing with regard to the field of manufacturing technology and the manner in which recent advances in additive manufacturing have allowed for new product designs with musculoskeletal applications. In addition, it is helpful to be aware of the regulatory aspects of additive manufacturing to ensure the safe and effective use of orthopaedic surgical devices created via three-dimensional printing.

Applications of Three-Dimensional Printing in Orthopaedic Surgery.

Orthopaedic surgeons should be aware of the variety of applications of three-dimensional printing, which range from rough-and-ready applications, such as rapid prototyping of implant designs with the use of polymers to the fabrication of patient-specific implants and custom implants with the use of the principles of metallurgy. The local manufacture of low-cost prosthetic devices in third-world nations is the best example of the potential application of three-dimensional printing. Orthopaedic surgeons should understand the multiple applications of three-dimensional printing, including prototyping of anatomy, implants, orthotics, patient-specific instrumentation, and implants that incorporate porous structures and accommodate complex anatomy, as well as the future of biologically active three-dimensional printing. It is helpful to be aware of the types of three-dimensional printing that are currently used in the clinical setting, those that are commercially available, and those under development.

Three-Dimensional Printing and Tissue Engineering in Orthopaedics.

Additive manufacturing and three-dimensional printing technology may revolutionize tissue-engineering strategies. Many clinical needs, including multitissue regeneration, remain unmet among patients with orthopaedic conditions. Ongoing research efforts in three-dimensional printing, including cell-containing bioinks for bioprinting, have resulted in acellular and cellular biomaterials that may help regenerate or replace damaged or missing biologic tissues. Recent advances in additive manufacturing aid in the preservation of biologic activity, such as the retention of growth factors, which may affect the delivery of safe, cost-effective, and efficacious bone graft substitutes for orthopaedic patients.

Effects of arm position on maximizing intra-articular visualization of the biceps tendon: a cadaveric study.

PURPOSE: The purpose of this study was to assess the intra-articular length of the biceps tendon in various shoulder and arm positions and identify the position in which the extra-articular portion of the tendon is maximally visualized within the glenohumeral joint. METHODS: We measured 18 positions in 4 fresh-frozen cadaveric shoulders for a total of 72 measurements. In each measurement the position of the proximal biceps tendon was measured relative to a baseline measurement in neutral position (0° shoulder flexion, 0° shoulder abduction, 0° elbow flexion, 0° shoulder rotation). Positions measured ranged between the following: 0° and 30° shoulder flexion; 0° and 40° shoulder abduction; 0° and 90° elbow flexion; and 0° neutral, 30° internal, and 30° external shoulder rotation. RESULTS: The position creating the greatest increase in intra-articular biceps tendon length from baseline was 30° shoulder flexion, 40° shoulder abduction, 90° elbow flexion, and 0° rotation. On average, 56% of the tendon within the bicipital groove is brought into view by the maximal position relative to baseline. In maximizing intra-articular biceps tendon length, the effect of elbow flexion was highly significant (P < .001) and the combined effect of shoulder flexion-abduction was significant (P = .016). CONCLUSIONS: The position of 30° shoulder flexion, 40° shoulder abduction, and 90° elbow flexion significantly increases the excursion of the proximal biceps tendon relative to a neutral position. Over 50% of the tendon within the bicipital groove at baseline can be pulled out of the groove by placing the extremity in the maximal position and using an arthroscopic probe. Rotation of the humerus does not improve intra-articular excursion. CLINICAL RELEVANCE: Maximizing the intra-articular tendon length by arm positional change is likely to be useful for arthroscopic examination of the biceps tendon.

Correlation of intra-articular ankle pathology with cytokine biomarkers and matrix degradation products.

BACKGROUND: Articular cartilage degeneration is mediated by inflammatory cytokines and fragments of structural matrix proteins. Few studies have examined the role of these biomarkers in intra-articular pathology of the ankle. METHODS: Four groups of patients with increasing ankle pathology were enrolled. Group 1 included controls with no pain who underwent unrelated forefoot surgery. Group 2 included patients undergoing arthroscopy with intraoperative mild chondrosis. Group 3 included patients undergoing arthroscopy with moderate/severe chondrosis, osteochondral lesions, impingement, or loose bodies. Group 4 included positive controls with severe arthrosis undergoing ankle arthrodesis/arthroplasty. Ankle fluid was obtained by intra-articular aspiration and was assayed for IL-6, IFN-γ, MCP, MIP-1ß, and fibronectin-aggrecan complex (FAC), a matrix-degradation marker. There were 36 patients total, 21 males and 15 females with a mean age 45 (±16; range 18 to 76) years and a mean VAS for pain of 4.7 (±3.5; range 0 to 9). In groups 1 through 4, there were 11, 6, 15 and 4 patients respectively. RESULTS: The mean values of MCP-1 were 49.8 (±8.0) for minimal pathology and 133.9 (±33.0) for substantial pathology (pg/ml). The mean values of the FAC were 2.83 (±1.16) for minimal pathology and 9.62 (±2.23) for substantial pathology (optical density at 450 nm). The groups differed significantly in age, preoperative VAS, FAC, IL-6, and MCP-1 (p<0.05). CONCLUSION: There are differences in FAC and MCP-1 with increasing grades of severity of intra-articular pathology. CLINICAL RELEVANCE: These tests may play a role in determining the necessity for arthroscopy or intra-articular procedures in equivocal candidates.

Summary of the FDA virtual public workshop on spinal device clinical review held on September 17, 2021.

The mission of Food and Drug Administration (FDA)'s Center for Devices and Radiological Health is to protect and promote public health. It assures that patients and providers have timely and continued access to safe, effective, and high-quality medical devices and safe radiation-emitting products by providing meaningful and timely information about the products we regulate and the decisions we make. On September 17, 2021, an FDA workshop was held to provide information to stakeholders, including members of the spine community, device manufacturers, regulatory affairs professionals, clinicians, patients, and the general public regarding FDA regulations, guidance and regulatory pathways related to spinal device clinical review. It was not intended to communicate any new policies, processes, or interpretations regarding medical device marketing authorizations. This workshop consisted of individual presentations, group discussions, question and answer sessions, and audience surveys. Information-sharing included discussions related to patient-reported outcomes, clinician-reported outcomes, observer-reported outcomes, and performance outcomes. Discussions involving external subject matter experts covered topics related to spinal device clinical studies including definition of a target population, enrollment criteria, strategies for inclusion of under-represented patient groups, reporting of adverse event and secondary surgical procedures, clinical study endpoints, and clinical outcome assessments. A meeting transcript and webcast workshop link are currently posted on the FDA website. Important related issues and challenges were discussed, and an exciting range of new ideas and concepts were shared which hold promise to advance regulatory science, patient care and future innovation related to spinal devices.

A comparison of 2 drilling techniques on the femoral tunnel for anterior cruciate ligament reconstruction.

PURPOSE: This cadaveric study was undertaken to characterize the femoral tunnel geometry resulting from commonly used drilling techniques in anterior cruciate ligament reconstruction. METHODS: We randomized 10 matched-pair cadaveric knees (20 knees) into 2 groups with right and left matched pairs from each cadaver. Of the knees, 10 underwent transtibial femoral tunnel drilling from a far-medial starting point on the tibia (group 1) and 10 had the femoral tunnel drilled from a medial arthroscopic portal (group 2). The dimensions and size of the apertures, the volume and length of the tunnels, and the distance of the tunnels from the posterior wall and articular surface were measured by computed tomography. RESULTS: The mean femoral tunnel length was 29.7 mm in group 1 and 15.7 mm in group 2. The mean volume for each tunnel was 2,401 mm(3) in group 1 and 2,071 mm(3) in group 2. The intra-articular aperture area was 94.6 mm(2) in group 1 and 98.6 mm(2) in group 2. In group 2 the intra-articular shape was more elliptical than in group 1, with the long axis averaging 13.5 ± 1.3 mm (P = .004) and short axis averaging 9.7 ± 1.0 mm (P = .002); in group 2 the long axis averaged 12.5 ± 1.7 and short axis averaged 10.3 ± 0.7 (P = .002). Group 2 was closer to the posterior wall and articular surface (6.9 ± 0.6 mm and 9.4 ± 0.6 mm, respectively) than group 1 (10.8 ± 1.0 mm and 11.8 ± 1.9 mm, respectively). CONCLUSIONS: We determined the length and volume of the femoral tunnel to be shorter and smaller, respectively, with a medial arthroscopic portal. In addition, the aperture shape was more of an ellipse with a medial arthroscopic portal. The medial arthroscopic portal also created a femoral tunnel that was closer to the posterior wall and articular surface of the femur. CLINICAL RELEVANCE: Improved characterization of osseous tunnels with 3-dimensional figures will allow for improved matching of graft and incorporation.

Bacteriologic culture of excised intervertebral disc from immunocompetent patients undergoing single level primary lumbar microdiscectomy.

STUDY DESIGN: A consecutive case series from a single center of patients undergoing primary microdiscectomy for lumbar herniated nucleus pulposus (HNP) who received microbiologic laboratory culture of excised disc material. OBJECTIVE: To determine the prevalence of positive bacterial cultures in the disc material of immunocompetent patients without diabetes mellitus or other immune compromise. SUMMARY OF BACKGROUND DATA: The intradiscal space is a physiologically tenuous environment in terms of oxygen tension, pH, and vascularity. This space may be susceptible to indolent infections with an unknown effect on the pathogenesis of HNP. METHODS: This case series included 52 patients with radiculopathy and magnetic resonance imaging positive for HNP who elected for lumbar microdiscectomy after failure of conservative management. All patients received primary surgery at a single spinal level in the absence of diabetes mellitus, systemic steroid use, chemotherapy, other immune compromise, or prior lumbar surgery. Excised disc material was sent for routine bacterial culture. No special culture techniques were used to improve the yield of positive cultures. RESULTS: Cultures were positive in 10 patients (19.2%). Propionibacterium acnes was the sole organism isolated in 7 (13.5%), with Peptostreptococcus and Staphylococcus species accounting for the remainder. There were 24 women (46.2%) and 28 men (53.8%) with a mean age of 43.9 years (SE 1.8). Duration of symptoms was greater than 12 weeks in 35 patients (67.3%). Onset of symptoms was insidious in 22 patients (42.3%), sudden in 16 (30.8%), and the history was unclear in the remainder. Prior epidural steroid injection was received by 17 patients (32.7%), and 11 patients had a history of smoking (21.2%). None of these variables was significantly different in patients with positive and negative cultures (P >0.05). CONCLUSIONS: P. acnes was isolated by routine laboratory culture of excised disc material in 13.5% of immunocompetent patients undergoing primary single level discectomy for radiculopathy with lumbar HNP; other organisms were isolated in 6% of patients. LEVEL OF EVIDENCE: Diagnostic level of evidence III.

Are persistently symptomatic vertebral compression fractures associated with abnormal inflammatory profiles? A prospective study.

STUDY DESIGN: A case-control study with prospectively collected samples for laboratory analysis in a series of patients with spinal fragility fractures and a series of patients without fracture who underwent fusion for LBP. OBJECTIVE: Was an exploratory data analysis for candidate cytokine biomarkers present in the fracture milieu of patients with persistent back pain associated with vertebral compression fracture. SUMMARY OF BACKGROUND DATA: Lumbar and thoracic compression fractures are common. Little is known about the presence of inflammatory mediators within fractured vertebra in the clinical setting. METHODS: Thirty patients diagnosed with a single thoracic or lumbar compression fracture were treated with single level vertebroplasty. At the time of intervention, needle aspiration was carried out at the fractured level. A multiplexed bead assay was used to assess the presence of 27 different cytokines and inflammatory mediators. A control group consisted of needle aspiration samples of 30 lumbar vertebra from 13 patients with chronic pain but no fracture undergoing open instrumented fusion. RESULTS: Thirty patients with 30 fractures consisted of 23 female and 7 male with a mean age of 77.5 years (SD 13.6; range 42 to 97) and a mean of 3.9 weeks of pain (SD 3.1; range 1 to 12). The highest levels of inflammatory mediators were (in order): IL-1 receptor antagonist, PDGF, RANTES, IP-10, IL-8, and eotaxin. These mediators were present at concentrations>200 pg/mL. Compared with controls with chronic pain, significant differences were present for 4 mediators: TNF, MIP-1b, IL-9, and IL-12. The panel of these 4 markers was 93.3% specific and 66.7% sensitive for fracture compared with the control group. CONCLUSIONS: Inflammatory mediators are present in needle aspirates of symptomatic vertebral compression fractures. Some of these mediators show different levels than in patients with chronic pain but no fracture. LEVEL OF EVIDENCE: Diagnostic level of evidence II.

Principles of biomechanics and biomaterials in orthopaedic surgery.

There are few surgical procedures within the field of orthopaedic surgery that do not entail the basis or need for understanding basic biomechanical principles. Every subspecialty field requires some aspect of biomechanics to properly understand and perform surgical procedures, patient examinations, and clinical treatment. A proper review of these principles will allow surgeons to better approach all treatment modalities used for patient care.

Determination of Work Relative Value Units for Management of Lumbar Spinal Stenosis by Open Decompression and Interlaminar Stabilization.

BACKGROUND: Effective January 1, 2017, open surgical decompression and interlaminar stabilization (ILS) received a Category I Current Procedural Terminology (CPT®) code 22867. The current work relative value units (wRVUs) assigned to the procedure of 13.5 are not reflective of the amount of work involved. During the survey process, CPT® 22867 was erroneously assessed with a percutaneous "sister" code (CPT® 22869), which is performed with no decompression (but within the same new "family") and primarily by nonsurgeons. However, similar CPT® code descriptors assigned to each of these new codes undermined their procedural differences during the survey process and generated confusion among physician survey responders, the American Medical Association/Specialty Society Relative Value Scale Update Committee (RUC), and ultimately the Centers for Medicare and Medicaid Services (CMS) regarding the value of ILS. The resulting physician payment determination for the ILS procedure has had severe deleterious effects on this procedure being offered to lumbar spinal stenosis (LSS) patients. Our independent society-driven survey presents new data that assess the accuracy of the assigned wRVUs for CPT® 22867. METHODS: An independent survey was driven by the International Society for the Advancement of Spine Surgery (ISASS) in November 2018 and sent to 58 US surgeons with experience performing open decompression with ILS (CPT® 22867) and without financial conflicts of interest as analogous to RUC survey financial disclosure requests. Respondents were asked to compare CPT® 22867 with a list of 10 other comparator CPT® codes reflective of common spine surgeries. The survey presented each comparator CPT® code with its code descriptor and corresponding wRVUs alongside the code descriptor for CPT® 22867. A patient vignette was also provided that describes a typical clinical scenario for the surveyed procedure. Respondents were then asked to indicate which comparator CPT® code on the reference list is most similar to the survey code descriptor and typical patient/service vignette provided, as well as specify estimated wRVUs for CPT® 22867 relative to their selected comparator CPT® code. The surgeons' responses were analyzed to determine comparator CPT® codes and estimated wRVUs. RESULTS: Among the 28 surgeons who responded to the survey, both open decompression codes (57.1%) and fusion codes (42.9%) were chosen as most similar to the typical patient/service for CPT® 22867. Furthermore, the laminectomy procedure (CPT® 63047) was chosen as the surveyed surgeons' model response for a reference procedure in terms of similar work intensity and time for CPT® 22867. After calculating the difference between the selected comparator codes and estimated wRVUs, nearly all respondents had a positive calculated difference, indicating that surgeons selected wRVUs lower than they deemed appropriate as a result of the listed CPT® codes they were required to use. In the spirit of the Rasch analysis, the regression analysis estimated wRVUs for CPT® 22867 that are greater than its assigned wRVUs (13.5) and its most comparable procedure (CPT® 63047; reference wRVUs: 15.37). DISCUSSION AND CONCLUSIONS: The survey results indicate that the wRVUs assigned to CPT® 22867 are significantly undervalued at 13.50 and have directly resulted in the underreimbursement for surgeons performing the ILS procedure. This misvaluation of the code has created a supply-and-demand anomaly in which the rate of ILS procedures has flatlined despite increasing rates of fusion procedures and an increasing older population. This anomaly is a cause of concern for policy makers and the health care community for the future of safeguarding patient welfare and procedural innovation. Therefore, understanding the clinical economic impact and appropriately addressing potential misvalued codes, such as the ILS procedure, are critical to protecting the future of patient care.

Cytokine profiling in acute anterior cruciate ligament injury.

PURPOSE: To evaluate the presence and relative concentrations of cytokines, known to be involved in the inflammatory cascade, in acute anterior cruciate ligament (ACL) injury. METHODS: We evaluated an extensive cytokine profile in synovial fluid from 12 patients with acute ACL injury undergoing arthroscopy compared with 15 control subjects using a BioPlex assay (Bio-Rad Laboratories, Hercules, CA) to measure the concentration of 17 inflammatory cytokines. RESULTS: In patients with acute ACL injury compared with asymptomatic control subjects, the following cytokines were identified at significantly increased concentrations (P < .001, Mann-Whitney U test) compared with control samples: interleukin 6 (105 ± 72 v 0 ± 0 pg/ml), interferon γ (1,544 ± 608 v 9 ± 7.5 pg/ml), macrophage inflammatory protein 1ß (16 ± 3.8 v 0.3 ± 0.2 pg/ml), and monocyte chemotactic protein 1 (35 ± 13 v 0.5 ± 0.4 pg/ml). There was no case of a cytokine exhibiting increased levels in asymptomatic compared with symptomatic knee samples. CONCLUSIONS: This investigation identified 4 specific cytokines (interleukin 6, interferon γ, monocyte chemotactic protein 1, and macrophage inflammatory protein 1ß) out of a panel of 17 inflammatory molecules for which the levels were consistently elevated in the context of ACL injury compared with non-painful, non-acutely injured knees in a volunteer population. LEVEL OF EVIDENCE: Level IV, prognostic case series.

Superiority Claims for Spinal Devices: A Systematic Review of Randomized Controlled Trials.

STUDY DESIGN: Systematic review. OBJECTIVES: Superiority claims for medical devices are commonly derived from noninferiority trials, but interpretation of such claims can be challenging. This study aimed to (a) establish the prevalence of noninferiority and superiority designs among spinal device trials, (b) assess the frequency of post hoc superiority claims from noninferiority studies, and (c) critically evaluate the risk of bias in claims that could translate to misleading conclusions. METHODS: Study bias was assessed using the Cochrane Risk of Bias Tool. The risk of bias for the superiority claim was established based on post hoc hypothesis specification, analysis of the intention-to-treat population, post hoc modification of a priori primary outcomes, and sensitivity analyses. RESULTS: Forty-one studies were identified from 1895 records. Nineteen (46%) were noninferiority trials. Fifteen more (37%) were noninferiority trials with a secondary superiority hypothesis specified a priori. Seven (17%) were superiority trials. Of the 34 noninferiority trials, 14 (41%) made superiority claims. A medium or high risk of bias was related to the superiority claim in 9 of those trials (64%), which was due to the analyzed population, lacking sensitivity analyses, claims not being robust during sensitivity analyses, post hoc hypotheses, or modified endpoints. Only 4 of the 14 (29%) noninferiority studies provided low bias in the superiority claim, compared with 3 of the 5 (60%) superiority trials. CONCLUSIONS: Health care decision makers should carefully evaluate the risk of bias in each superiority claim and weigh their conclusions appropriately.

Guideline summary review: an evidence-based clinical guideline for the diagnosis and treatment of low back pain.

BACKGROUND CONTEXT: The North American Spine Society's (NASS) Evidence Based Clinical Guideline for the Diagnosis and Treatment of Low Back Pain features evidence-based recommendations for diagnosing and treating adult patients with nonspecific low back pain. The guideline is intended to reflect contemporary treatment concepts for nonspecific low back pain as reflected in the highest quality clinical literature available on this subject as of February 2016. PURPOSE: The purpose of the guideline is to provide an evidence-based educational tool to assist spine specialists when making clinical decisions for adult patients with nonspecific low back pain. This article provides a brief summary of the evidence-based guideline recommendations for diagnosing and treating patients with this condition. STUDY DESIGN: This is a guideline summary review. METHODS: This guideline is the product of the Low Back Pain Work Group of NASS' Evidence-Based Clinical Guideline Development Committee. The methods used to develop this guideline are detailed in the complete guideline and technical report available on the NASS website. In brief, a multidisciplinary work group of spine care specialists convened to identify clinical questions to address in the guideline. The literature search strategy was developed in consultation with medical librarians. Upon completion of the systematic literature search, evidence relevant to the clinical questions posed in the guideline was reviewed. Work group members utilized NASS evidentiary table templates to summarize study conclusions, identify study strengths and weaknesses, and assign levels of evidence. Work group members participated in webcasts and in-person recommendation meetings to update and formulate evidence-based recommendations and incorporate expert opinion when necessary. The draft guideline was submitted to an internal and external peer review process and ultimately approved by the NASS Board of Directors. RESULTS: Eighty-two clinical questions were addressed, and the answers are summarized in this article. The respective recommendations were graded according to the levels of evidence of the supporting literature. CONCLUSIONS: The evidence-based clinical guideline has been created using techniques of evidence-based medicine and best available evidence to aid practitioners in the diagnosis and treatment of adult patients with nonspecific low back pain. The entire guideline document, including the evidentiary tables, literature search parameters, literature attrition flowchart, suggestions for future research, and all of the references, is available electronically on the NASS website at https://www.spine.org/ResearchClinicalCare/QualityImprovement/ClinicalGuidelines.aspx.

The graft/femoral tunnel angles in posterior cruciate ligament reconstruction: a comparison of 3 techniques for femoral tunnel placement.

This study compared the graft/femoral tunnel angle produced with the outside-in technique with the inside-out technique at 90 degrees and 120 degrees of flexion. Three femoral tunnels were marked with guidewires and measured radiographically in 8 fresh-frozen cadaveric knees using both techniques. Results were analyzed. The mean graft/femoral tunnel angle was 34.4 degrees +/- 14.4 degrees for the outside-in technique, 52.3 degrees +/- 14.1 degrees for the inside-out technique at 120 degrees of flexion, and 74.4 degrees +/- 11 degrees for the inside-out technique at 90 degrees of flexion. The angle was smaller for the outside-in technique versus the inside-out technique at both 120 degrees (P = .019) and 90 degrees of knee flexion (P < .001). The outside-in technique for femoral tunnel placement produces the lowest graft/femoral tunnel angle in cadavers. With the inside-out technique, 120 degrees of flexion produces smaller angles than does 90 degrees of flexion. The outside-in technique results in lower angles and perhaps lower graft failure rates. However, additional clinical studies are needed.

Does the presence of the fibronectin-aggrecan complex predict outcomes from lumbar discectomy for disc herniation?

BACKGROUND CONTEXT: Protein biomarkers associated with lumbar disc disease have been studied as diagnostic indicators and therapeutic targets. Recently, a cartilage degradation product, the fibronectin-aggrecan complex (FAC) identified in the epidural space, has been shown to predict response to lumbar epidural steroid injection in patients with radiculopathy from herniated nucleus pulposus (HNP). PURPOSE: Determine the ability of FAC to predict response to microdiscectomy for patients with radiculopathy due to lumbar disc herniation STUDY DESIGN/SETTING: Single-center prospective consecutive cohort study. PATIENT SAMPLE: Patients with radiculopathy from HNP with concordant symptoms to MRI who underwent microdiscectomy. OUTCOMES MEASURES: Oswestry disability index (ODI) and visual analog scores (VAS) were noted at baseline and at 3-month follow-up. Primary outcome of clinical improvement was defined as patients with both a decrease in VAS of at least 3 points and ODI >20 points. METHODS: Intraoperative sampling was done via lavage of the excised fragment by ELISA for presence of FAC. Funding for the ELISA was provided by Cytonics, Inc. RESULTS: Seventy-five patients had full complement of data and were included in this analysis. At 3-month follow-up, 57 (76%) patents were "better." There was a statistically significant association of the presence of FAC and clinical improvement (p=.017) with an 85% positive predictive value. Receiver-operating-characteristic (ROC) curve plotting association of FAC and clinical improvement demonstrates an area under the curve (AUC) of 0.66±0.08 (p=.037). Subset analysis of those with weakness on physical examination (n=48) plotting the association of FAC and improvement shows AUC on ROC of 0.81±0.067 (p=.002). CONCLUSIONS: Patients who are "FAC+" are more likely to demonstrate clinical improvement following microdiscectomy. The data suggest that the inflammatory milieu plays a significant role regarding improvement in patients undergoing discectomy for radiculopathy in lumbar HNP, even in those with preoperative weakness. The FAC represents a potential target for treatment in HNP.

A critical evaluation of discography in patients with lumbar intervertebral disc disease.

STUDY DESIGN: The study is a prospective observational study of 48 continuous patients with symptomatic lumbar degenerative disk disease. Each patient underwent discography, MRI, and a biochemical analysis of disk lavage fluid. OBJECTIVES: The purpose of this study was to correlate concordant pain on discography with MRI grade and biochemical markers of inflammation in a clinical setting. SUMMARY OF BACKGROUND DATA: The pathophysiology of degenerative disk disease is complex. Discography is used to differentiate symptomatic from asymptomatic levels. MRI is used to image changes in disk water content. Biochemical assays have identified molecular markers of inflammation. To date, no study has correlated concordant pain on discography with MRI findings and biochemical markers. METHODS: Forty-eight (48) continuous patients with symptomatic lumbar degenerative disk disease gave informed consent for study entry. Patient sex, age, insurance, work status and visual analog score (VAS) were recorded. MRI was obtained and Pfirrmann grading was performed by a single spine surgeon. Discography with disc lavage was performed by a single anesthesiologist. Lavage samples were tested for inflammatory markers with high resolution multi-plex bead immunoassays and ELISA with >5 pg/ml resolution. RESULTS: None of demographic variables was significantly related to concordant pain on discogram by chi-squared tests and Mann-Whitney U-test. The Pfirrmann score was significantly different for patients with and without concordant pain at L3-L4 (p<0.001), but was insignificant at other levels after multitest correction. Pfirrmann scores were significantly different at any level in patients with and without concordant pain. VAS scores were not significantly correlated with opening pressures at any level. Despite the presence of serum proteins in the disk lavage fluid, none of the tested inflammatory mediators was identified by multi-plex bead immunoassays and ELISA. CONCLUSIONS: There are only weak correlations between demographic, discogram, and radiographic variables. Response to discogram cannot be predicted by non-invasive means. The disk lavage method was unable to identify the presence of specific inflammatory peptides with multi-plex immunoassays and ELISA.

Interference screw versus suture anchor fixation for subpectoral tenodesis of the proximal biceps tendon: a cadaveric study.

PURPOSE: The purpose of this study was to compare the biomechanical properties of 2 fixation methods for subpectoral proximal biceps tenodesis. METHODS: In 9 matched pairs of cadaveric shoulders, an open subpectoral tenodesis was performed 1 cm proximal to the inferior border of the pectoralis major tendon by use of either an 8 x 12-mm Bio-Tenodesis screw (Arthrex, Naples, FL) with No. 2 FiberWire sutures (Arthrex) or a 5.5-mm Bio-Corkscrew double-loaded suture anchor (Arthrex) with No. 2 FiberWire sutures. The specimens were dissected and mounted in a material testing machine. Cyclic loading (20 to 60 N, 100 cycles, 0.5 mm/s, 5-N preload) was performed, followed by an unloaded 30-minute rest, a 5-N preload, and a load-to-failure protocol (1.25 mm/s) with a 100-lb load cell. Ultimate load (in Newtons), stiffness (in Newtons per millimeter), and modes of failure were recorded. Data were analyzed by use of paired t tests and Wilcoxon signed rank tests. RESULTS: Proximal biceps tenodeses with Bio-Tenodesis screws had a significantly higher mean load to failure (169.6 +/- 50.5 N; range, 99.6 to 244.7 N) than those with Bio-Corkscrew suture anchors (68.5 +/- 33.0 N; range, 24.2 to 119.4 N) (P = .002). Bio-Tenodesis screws also had a significantly higher stiffness (34.1 +/- 9.0 N/mm; range, 20.6 to 48.9 N/mm) than Bio-Corkscrews (19.3 +/- 10.5; range, 5.9 to 32.9 N/mm) (P = .038). CONCLUSIONS: In this cadaveric study the Bio-Tenodesis screw showed a statistically significantly higher load to failure and significantly higher stiffness than the Bio-Corkscrew anchor when used for tenodesis of the proximal biceps tendon in a subpectoral location. CLINICAL RELEVANCE: Biomechanical comparison of these 2 fixation techniques provides information on stiffness and load to failure of alternate fixation methods.

The effect of plate position and size on tibial slope in high tibial osteotomy: a cadaveric study.

Opening wedge high tibial osteotomies are performed for degenerative changes and varus. Opening wedge osteotomies can change proximal tibial slope in the sagittal plane, possibly imparting stability in the ACL-deficient knee. The aim of this study was to assess the effect of plate position and size on change in tibial slope. Eight cadaveric knees underwent opening wedge high tibial osteotomy with Puddu plates of each different size. Plates were placed anterior, central, and posterior for each size used. Lateral radiographs were obtained. Tibial slope was measured and compared with baseline slope. Tibial slope was affected by plate position (P < 0.05) and size (P < 0.001). Smaller, posterior plates had less effect on tibial slope. However, anterior and central plates increased tibial slope over all plate sizes (P < 0.05). This study found that tibial slope increases with opening wedge high tibial osteotomy. Larger corrections and anterior placement of the plate are associated with larger increases in slope.