S. Raymond Golish

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 In Vitro Chondrotoxicity of Single-Dose Local Anesthetics

Background: The administration of amide-type local anesthetics to cartilaginous tissues has revealed potential chondrotoxicity. Purpose: This study evaluated whether administration of single doses of 1% lidocaine, 0.25% bupivacaine, and 0.5% ropivacaine resulted in decreased chondrocyte viability or cartilage matrix degradation in vitro. Study Design: Controlled laboratory study. Methods: Monolayer human chondrocytes and intact cartilage samples were cultured for 1 week in media. Each drug was delivered in a custom bioreactor over its clinical duration of action. A Live/Dead Viability/Cytotoxicity Assay was used to determine the ratio of dead to live cells for monolayer chondrocyte cultures compared with controls. Damage to the cartilage extracellular matrix (ECM) in en bloc cartilage samples was evaluated by analysis of DNA, glycosaminoglycan (GAG), and collagen content. Results: Chondrocytes treated for 3 hours with a single dose of 1% lidocaine exhibited significantly more cell death (7.9%) compared with control media (2.9%; P < .001). No significant difference in cell death was observed in chondrocytes treated for 6 hours with 0.25% bupivacaine (2.7%) versus controls (2.8%; P = .856) or cells treated for 12 hours in 0.5% ropivacaine (2.9%) versus controls (2.4%; P = .084). There was no significant difference in GAG expression (P = .627) or DNA-normalized GAG expression (P = .065) between the intact cartilage treatment groups; however, the DNA-normalized GAG expression was markedly lower in cartilage cultures treated with 1% lidocaine (3.36 ± 1.15) compared with those in control media (7.61 ± 3.83). Conclusion: The results of this in vitro study indicate that a single-dose administration of 1% lidocaine resulted in a significant decrease in chondrocyte viability when compared with control cultures. Clinical Relevance: Single-dose injections of 1% lidocaine may be significantly chondrotoxic, and further investigation regarding in vivo chondrotoxicity appears warranted.

Diagnostic Utility of Cytokine Biomarkers in the Evaluation of Acute Knee Pain

BACKGROUND The diagnosis of clinically important meniscal tears of the knee remains challenging, and it is unknown why only some injuries become painful. The role of inflammatory cytokines in generating pain following meniscal injury remains unclear. This study aimed to investigate the cytokine profile in patients with acute knee pain believed to be secondary to meniscal damage. METHODS This prospective cohort study included thirty-two patients without rheumatoid arthritis who had knee pain for less than six months, with either an acute or insidious onset, and elected to have arthroscopic treatment after nonoperative management had failed. Twenty-three of these patients elected to have the contralateral, nonoperatively treated knee lavaged at the time of arthroscopy. Fifteen asymptomatic control subjects also contributed samples of knee joint fluid, for a total of seventy samples from forty-seven subjects. Lavage of the operatively treated, contralateral, and control knees was performed with the patient under regional anesthesia prior to arthroscopy, if applicable, by the infusion of sterile saline solution into the knee followed by the immediate withdrawal into a syringe. The concentrations of seventeen inflammatory cytokines and chemokines were measured with use of a multiplexed immunoassay panel. Preoperative magnetic resonance imaging findings and cytokine assay results were compared with intraoperative findings. RESULTS Multivariate analysis of variance detected significantly greater concentrations of interferon gamma (IFN-gamma); interleukins 2, 4, 6, 10, and 13 (IL-2, IL-4, IL-6, IL-10, and IL-13); monocyte chemotactic protein-1 (MCP-1); and macrophage inflammatory protein-1 beta (MIP-1beta) in fluid samples from painful knees than in samples from nonpainful knees. Correlation analysis demonstrated a significant positive correlation between patient-reported pain scores and concentrations of IL-6 (Spearman rho = 0.7), MCP-1 (rho = 0.8), MIP-1beta (rho = 0.6), and IFN-gamma (rho = 0.6). These four cytokines also demonstrated a positive correlation with each other (rho = 0.5 to 0.7). The presence of IFN-gamma, IL-6, MCP-1, or MIP-1beta performed as well as magnetic resonance imaging in the prediction of intraoperative findings. CONCLUSIONS Intra-articular concentrations of four inflammatory cytokines IFN-gamma, IL-6, MCP-1, and MIP-1beta correlated to pain in patients with symptomatic meniscal tears in the knee but were markedly lower in asymptomatic normal knees and in asymptomatic knees with meniscal tears. These cytokines may be involved in the generation of pain following meniscal injury.

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.

All-Inside Meniscal Repair Using a New Flexible, Tensionable Device

Background A new generation of flexible all-inside meniscal repair devices is available, but clinical studies with these devices are lacking. Hypothesis The RapidLoc has an intermediate-term meniscal healing rate that is equivalent to literature reports of inside-out suture technique in patients undergoing concurrent anterior cruciate ligament reconstruction. Study Design Case series; Level of evidence, 4. Methods Retrospective analysis was performed for 75 meniscal tears in 66 consecutive patients undergoing anterior cruciate ligament reconstruction who underwent meniscal repair with the RapidLoc. Patients with at least 2 years’ follow-up were evaluated for symptoms suggestive of a meniscal tear and were assessed with the International Knee Documentation Committee form and the Knee Disorders Subjective History visual analog scale. Subjects were asked to return for a clinical examination to include evaluation for an effusion and joint line tenderness as well as McMurray test and KT-1000 arthrometry readings. Patients with symptoms consistent with meniscal repair failure underwent magnetic resonance arthrography and repeat arthroscopy. Results Twenty patients with 21 meniscal tears were excluded, resulting in 54 meniscal tears in 46 patients. At a mean follow-up of 34.8 months, the clinical success rate for meniscal repair was 90.7% (49/54), with 5 failures requiring meniscectomy. Univariate analysis revealed predictive variables for failure: bucket-handle configuration, multiplanar tears, tear length greater than 2 cm, and chronicity longer than 3 months. Nonpredictive variables included compartment, zone, ligament graft choice, gender, age, follow-up, and visual analog scale score. Analysis of healed patients revealed a negative correlation between chronicity of tear and International Knee Documentation Committee score. Conclusions The RapidLoc has an acceptable intermediate-term clinical healing rate in patients undergoing concurrent anterior cruciate ligament reconstruction. Predictive variables for failure should be considered during operative decision making.

Platelet-rich plasma increases matrix metalloproteinases in cultures of human synovial fibroblasts.

BACKGROUND The effect of platelet-rich plasma on chondrocytes has been studied in cell and tissue culture. Less attention has been given to the effect of platelet-rich plasma on nonchondrocytic cell lineages within synovial joints, such as fibroblast-like synoviocytes, which produce cytokines and matrix metalloproteinases (MMPs) that mediate cartilage catabolism. The purpose of the present study was to determine the effect of platelet-rich plasma on cytokines and proteases produced by fibroblast-like synoviocytes. METHODS Platelet-rich plasma and platelet-poor plasma from harvested autologous blood were prepared with a commercially available system. Fibroblast-like synoviocytes were treated with platelet-rich plasma, platelet-poor plasma, recombinant PDGFββ (platelet-derived growth factor ββ), or phosphate-buffered saline solution and incubated at 37°C for forty-eight hours. The concentrations of IL-1β (interleukin-1β), IL-1RA (IL-1 receptor antagonist), IL-6, IFN-γ (interferon-γ), IP-10 (interferon gamma-induced protein 10), MCP-1 (monocyte chemotactic protein-1), MIP-1β (macrophage inflammatory protein-1β), PDGFββ, RANTES, TNF-α (tumor necrosis factor-α), VEGF (vascular endothelial growth factor), MMP-1, MMP-3, and MMP-9 in the culture medium were determined by multiplex immunoassay. RESULTS Platelet-rich plasma cultured in medium contained multiple catabolic mediators in substantial concentrations, including MMP-9 (15.8 ± 2.3 ng/mL) and MMP-1 (2.5 ± 0.8 ng/mL), as well as proinflammatory mediators IL-1β, IL-6, IFN-γ, IP-10, MCP-1, MIP-1β, RANTES, and TNF-α in concentrations between 20 pg/mL and 20 ng/mL. Platelet-poor plasma contained significantly lower concentrations of these compounds. Platelet-rich plasma was used to treat human fibroblast-like synoviocytes, and the resulting concentrations of mediators were corrected for the concentrations in the platelet-rich plasma alone. Compared with untreated fibroblast-like synoviocytes, synoviocytes treated with platelet-rich plasma exhibited significantly greater levels of MMP-1 (363 ± 94.0 ng/mL, p = 0.018) and MMP-3 (278 ± 90.0 ng/mL, p = 0.018). In contrast, platelet-poor plasma had little effect on mediators secreted by the synoviocytes. PDGFββ-treated fibroblast-like synoviocytes exhibited a broad proinflammatory cytokine response at four and forty-eight hours. CONCLUSIONS Platelet-rich plasma was shown to contain a mixture of anabolic and catabolic mediators. Synoviocytes treated with platelet-rich plasma responded with substantial MMP secretion, which may increase cartilage catabolism. Synoviocytes responded to PDGF with a substantial proinflammatory response.

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.

Prospective Correlation Between Serum Relaxin Concentration and Anterior Cruciate Ligament Tears Among Elite Collegiate Female Athletes

Background: The female anterior cruciate ligament may be more susceptible to injury than the male anterior cruciate ligament because of the gender-specific expression of receptors for relaxin, a collagenolytic hormone that promotes remodeling of the anterior cruciate ligament. Purpose: This study was undertaken to investigate whether collegiate female athletes with elevated serum relaxin concentrations (SRC) sustain anterior cruciate ligament tears at an increased rate compared with those with lower SRC. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: From 2005 to 2010, 143 Division I female athletes from 2 universities participating in sports at high risk for anterior cruciate ligament tears (basketball, lacrosse, field hockey, soccer, gymnastics, and volleyball) were recruited to participate. Questionnaires and urine luteinizing hormone (LH) tests were used to determine participants’ anterior cruciate ligament injury and menstrual history and to identify their mid-luteal phase or projected cycle days 21 to 24. Serum samples were obtained for progesterone and relaxin ELISA (enzyme-linked immunosorbent assay) analysis. Participants were monitored for anterior cruciate ligament injury over their 4-year National Collegiate Athletic Association athletic career. Results: A total of 128 participants completed the study and were eligible for data analysis. The cumulative incidence of complete anterior cruciate ligament tear over the 4-year study period was 21.9%, and varied significantly by sport (P < .001). The mean SRC for athletes with anterior cruciate ligament tears (6.0 ± 8.1 pg/mL) was significantly higher than that for those without anterior cruciate ligament tears (1.8 ± 3.4 pg/mL; P = .013). In subgroup analysis of the 46 athletes who had detectable SRC, the cumulative incidence of anterior cruciate ligament tear was 14 of 46 (30.4%); the mean SRC among athletes with anterior cruciate ligament tears (14 of 46) was 12.1 ± 7.7 pg/mL and without anterior cruciate ligament tears (32 of 46), 5.7 ± 3.6 pg/mL (P = .002). When 6.0 pg/mL was set as the SRC cutoff for screening athletes for risk of anterior cruciate ligament tear in the subgroup with detectable relaxin levels, the test had 71% sensitivity, 69% specificity, 52% positive predictive value, 88% negative predictive value, and a relative risk of 4.4. These values were significant by χ2 test (P = .003) and receiver operating characteristic analysis (P = .002). Conclusion: Elite female athletes with anterior cruciate ligament tears have higher SRC than those without tears. Those with an SRC greater than 6.0 pg/mL had over 4 times increased risk for a tear. Clinical Relevance: Females with higher serum relaxin levels may be at increased risk for anterior cruciate ligament tears. Further investigation of the clinical utility of SRC testing is warranted.

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 1β (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 1β) 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.

The Effects of Extra-articular Starting Point and Transtibial Femoral Drilling on the Intra-articular Aperture of the Tibial Tunnel in ACL Reconstruction

Background The recent emphasis on more horizontal femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstructions requires placing a femoral tunnel lower on the lateral wall of the notch. Some surgeons have advocated moving the starting point of the tibial tunnel farther medial to achieve this more horizontal tunnel. Purpose To compare tibial tunnel aperture changes with transtibial femoral tunnel drilling. Study Design Controlled laboratory study. Methods Twenty match-paired cadaveric knees (10 specimens) were randomized into 2 groups with equal right and left knee distribution. Ten of the knees underwent tibial tunnel drilling from a medial starting point (group 1), and the corresponding opposite knee of each cadaveric specimen had the tibial tunnel drilled from a central starting point (group 2). Computerized tomography (CT) with thin slices and 3-dimensional reconstruction was used to obtain the dimensions of the apertures, area of the apertures, angles of the tunnels, and location of the starting point and ending point of the tunnels. We also determined the location of the femoral tunnels in the notch for each of the groups. The 10 knees with medial starting points underwent transtibial femoral tunnel drilling and were restudied with CT to evaluate changes in tibial tunnel characteristics. The 10 knees with central starting points underwent femoral drilling from an anteromedial arthroscopic portal. Results Central tibial tunnels were slightly larger than medial tibial tunnels before femoral drilling (106.3 mm3 vs 92.4 mm3). After femoral drilling through the medial tunnels, the apertures were larger than the central tibial apertures (118.6 mm3 vs 106.3 mm3). Medial tibial tunnels resulted in an intra-articular aperture that was farther from the tibial tubercle (43.1 mm vs 16.3 mm), farther from the medial tibial plateau (38.3 mm vs 32.2 mm), and more acute in the coronal plane (50.4° vs 79.3°). Medial tibial tunnels resulted in an intra-articular aperture that was closer to the anterior edge of the tibia (22.6 mm vs 29.6 mm) but with a less acute sagittal plane angle (82.5° vs 54.5°). The average clock-face measurement on the femur was 10:40 (±14 minutes) for the medial starting point and 10:14 (±14 minutes) for the central starting point (drilled from an anteromedial arthroscopic portal) (P = .0016). Conclusion We observed significantly increased tibial aperture size and shape after transtibial femoral drilling with a medial tibial starting point. Medial tibial tunnels, compared with more central tunnels, resulted in a more acute tibial tunnel in the coronal plane and less acute tibial tunnels relative to the sagittal plane. Medial tibial tunnels started farther from the tibial tubercle but ended farther from the medial joint line and closer to the anterior edge of the tibia in comparison to central tunnels Clinical Relevance Femoral tunnel placements may be best accomplished using a technique other than transtibial drilling through a medial tibial tunnel. Tibial tunnel angle, intra-articular position, and femoral tunnel placement are affected by the choice of extra-articular starting position.