Intramedullary Cortical Button Repair for Distal Biceps Tendon Rupture: A Single-Center Experience.

PURPOSE: The aim of this retrospective study was to evaluate the clinical outcome and complication rate of intramedullary cortical button repair for distal biceps tendon rupture (partial and complete tears). METHODS: Between 2010 and 2014, a total of 28 patients with an acute distal biceps tendon rupture underwent intramedullary cortical button repair. Twenty-four patients (mean age, 49 years) with a mean follow-up of 28 months were included in the study. Twenty patients were examined clinically and by maximum isometric strength testing in flexion (at 90°) and supination of both arms. Twenty-four patients completed functional scores including the Mayo Elbow Performance Score (MEPS), the Andrews-Carson-Score (ACS) and the shortened Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire. Furthermore, follow-up radiographs of 24 patients were analyzed. RESULTS: Compared with the contralateral elbow, the active range of motion (ROM) was the same. The mean strength for flexion was 100.8% ± 14% and for supination 93.1% ± 22% compared with the uninjured side. The mean MEPS for all patients was 95.6 ± 8.2, the mean ACS 194.2 ± 9.4 and the QuickDASH 3.8 ± 7.6. Heterotopic ossification (HO) was seen on radiographs in 46% of patients, but was symptomatic in only 1 patient. One patient suffered a tendon rerupture, and 1 asymptomatic button migration was seen in the follow-up. CONCLUSIONS: Intramedullary cortical button repair provides good results with respect to strength, ROM, and functional outcomes. Because the posterior cortex is not violated, the risk of iatrogenic posterior interosseous nerve injury is minimized. However, the patient should be warned of a high prevalence of postoperative HO. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Validation of a new classification for periprosthetic shoulder fractures.

INTRODUCTION: Successful treatment of periprosthetic shoulder fractures depends on the right strategy, starting with a well-structured classification of the fracture. Unfortunately, clinically relevant factors for treatment planning are missing in the pre-existing classifications. Therefore, the aim of the present study was to describe a new specific classification system for periprosthetic shoulder fractures including a structured treatment algorithm for this important fragility fracture issue. METHODS: The classification was established, focussing on five relevant items, naming the prosthesis type, the fracture localisation, the rotator cuff status, the anatomical fracture region and the stability of the implant. After considering each single item, the individual treatment concept can be assessed in one last step. To evaluate the introduced classification, a retrospective analysis of pre- and post-operative data of patients, treated with periprosthetic shoulder fractures, was conducted by two board certified trauma surgery consultants. RESULTS: The data of 19 patients (8 male, 11 female) with a mean age of 74 ± five years have been analysed in our study. The suggested treatment algorithm was proven to be reliable, detected by good clinical outcome in 15 of 16 (94%) cases, where the suggested treatment was maintained. Only one case resulted in poor outcome due to post-operative wound infection and had to be revised. CONCLUSIONS: The newly developed six-step classification is easy to utilise and extends the pre-existing classification systems in terms of clinically-relevant information. This classification should serve as a simple tool for the surgeon to consider the optimal treatment for his patients.

Double intramedullary cortical button versus suture anchors for distal biceps tendon repair: a biomechanical comparison.

PURPOSE: The aim of this biomechanical in vitro study was to compare the novel technique of double intramedullary cortical button (DICB) fixation with the well-established method of suture anchor (SA) fixation for distal biceps tendon repair. METHODS: A matched-pair analysis (24 human cadaveric radii) was performed with respect to cyclic loadings and failure strengths. Twelve specimens per group were cyclically loaded for 1,000 cycles at 1.5 Hz from 5 to 50 N and from 5 to 100 N, respectively. The tendon-bone displacement was optically analysed using the Image J Software (National Institute of Health). Afterwards, all specimens were pulled to failure. Maximum load to failure and mode of failure were recorded. RESULTS: All DICB constructs passed the cyclic loading test, whereas 4 of the 12 specimens within the SA group failed by anchor pull-out. Cyclic loading showed a mean tendon-bone displacement of 0.6 ± 1.4 mm for the DICB group and 1.4 ± 1.4 mm for the SA group (n.s.) after 1,000 cycles with 50 N, and a mean displacement of 2.1 ± 2.4 mm for the DICB group and 3.5 ± 3.7 mm for the SA group (n.s.) after 1,000 cycles with 100 N. Load to failure testing showed a mean failure load of 312 ± 76 N and a stiffness of 67.1 ± 11.7 N/mm for the DICB technique. The mean load to failure for the SA repair was 200 ± 120 N (n.s.) and the stiffness was 55.9 ± 21.3 N/mm (n.s.). CONCLUSIONS: The novel technique of DICB fixation showed small tendon-bone displacement during cyclic testing and reliable fixation strength to the bone in load to failure. Moreover, all DICB constructs passed cyclic loadings without failure. Based on the current findings, a more aggressive postoperative rehabilitation may be allowed for the DICB repair in clinical use.

Biomechanical comparison of intramedullary cortical button fixation and interference screw technique for subpectoral biceps tenodesis.

PURPOSE: The purpose of this study was to biomechanically evaluate a new technique of intramedullary cortical button fixation for subpectoral biceps tenodesis and to compare it with the interference screw technique. METHODS: We compared intramedullary unicortical button fixation (BicepsButton; Arthrex, Naples, FL) with interference screw fixation (Bio-Tenodesis screw; Arthrex) for subpectoral biceps tenodesis using 10 pairs of human cadaveric shoulders and ovine superficial digital flexor tendons. After computed tomography analysis, the specimens were mounted in a testing machine. Cyclic loading was performed (preload, 5 N; 5 to 70 N at 1.5 Hz for 500 cycles), recording the displacement of the tendon. Load to failure and stiffness were subsequently evaluated with a load-to-failure test (1 mm/s). RESULTS: Cyclic loading showed a displacement of 11.3 ± 2.8 mm for intramedullary cortical button fixation and 9 ± 1.7 mm for interference screw fixation (P = .112). All specimens within the cortical button group passed the cyclic loading test, whereas 3 of 10 specimens within the interference screw group failed by tendon slippage at the screw-tendon-bone interface after a mean of 252 cycles (P = .221). Load-to-failure testing showed a mean load to failure of 218.8 ± 40 N and stiffness of 27.2 ± 7.2 N/mm for the intramedullary cortical button technique. For the interference screw, the mean load to failure was 212.1 ± 28.3 N (P = .625) and stiffness was 40.4 ± 13 N/mm (P = .056). CONCLUSIONS: We could not find any major differences in load to failure when comparing the tested techniques for subpectoral biceps tenodesis. Intramedullary cortical button fixation showed no failure during cyclic testing. However, we found a 30% failure rate (3 of 10) for the interference screw fixation. CLINICAL RELEVANCE: Intramedullary cortical button fixation provides an alternative technique for subpectoral biceps tenodesis with comparable and, during cyclic loading, even superior biomechanical properties to interference screw fixation.

Acromioclavicular and coracoclavicular PDS augmentation for complete AC joint dislocation showed insufficient properties in a cadaver model.

PURPOSE: Optimal surgical treatment of high-grade acromioclavicular joint dislocations is still controversially discussed. The purpose of the present controlled laboratory study was to evaluate whether a polydioxansulfate (PDS(®)) cord augmentation with separate reconstruction of the coracoclavicular (CC) ligaments and the acromioclavicular (AC) complex provides sufficient vertical stability in a biomechanical cadaver model. METHODS: Twenty-four shoulders of fresh-frozen cadaveric specimen were tested. Cyclic loading and load to failure protocol was performed in vertical direction on 12 native AC joints and repeated after reconstruction. The reconstruction of the coracoclavicular ligament was performed using two CC PDS cerclages and an additional AC PDS cerclage. RESULTS: In static load testing for vertical force, the native AC joint complex measured 590.1 N (±95.8 N), elongation 13.4 mm (±2.1 mm) and stiffness 48.7 N/mm (±12.0 N/mm). The mean maximum load to failure in the reconstructed joints was 569.9 N (±97.9 N), elongation 18.8 mm (±4.7 mm) and stiffness 37.9 N/mm (±8.0 N/mm). During dynamic testing of the reconstructed AC joints, all specimens reached the critical elongation of 12.0 mm, defined as clinical failure between 200 and 300 N. The mean amount of repetitions at clinical failure was 305. A plastic deformation of the reconstructed specimens throughout cyclic loading could not be detected. CONCLUSION: The AC joint reconstruction with acromioclavicular and coracoclavicular PDS cord cerclages did not provide the aspired vertical stability in a cadaver model. LEVEL OF EVIDENCE: Basic Science Study.

Green tea protects human osteoblasts from cigarette smoke-induced injury: possible clinical implication.

PURPOSE: Recent reports discuss the altered bone homeostasis in cigarette smokers, being a risk factor for osteoporosis and negatively influencing fracture healing. Cigarette smoke is known to induce oxidative stress in the body via an increased production of reactive oxygen species (ROS). These increases in ROS are thought to damage the bone-forming osteoblasts. Naturally occurring polyphenols contained in green tea extract (GTE), e.g., catechins, are known to have anti-oxidative properties. Therefore, the aim of this study was to investigate whether GTE and especially catechins protect primary human osteoblasts from cigarette smoke-induced damage and to identify the underlying mechanisms. METHODS: Primary human osteoblasts were isolated from patients' femur heads. Cigarette smoke medium (CSM) was obtained using a gas-washing bottle and standardized by its optical density (OD(320)) at λ = 320 nm. ROS formation was measured using 2'7'dichlorofluorescein diacetate, and osteoblasts' viability was detected by resazurin conversion. RESULTS: Co-, pre-, and post-incubation with GTE and catechins significantly reduced ROS formation and thus improved the viability of CSM-treated osteoblasts. Besides GTE's direct radical scavenging properties, pre-incubation with both GTE and catechins protected osteoblasts from CSM-induced damage. Inhibition of the anti-oxidative enzyme HO-1 significantly reduced the protective effect of GTE and catechins emphasizing the key role of this enzyme in GTE anti-oxidative effect. CONCLUSIONS: Our data suggest possible beneficial effects on bone homeostasis, fracture healing, and bone mineral density following a GTE-rich diet or supplementation.

The double intramedullary cortical button fixation for distal biceps tendon repair.

PURPOSE: This study was designed to present the novel technique of intramedullary cortical button fixation for distal biceps tendon repair via a single-limited anterior portal. METHODS: To reattach the ruptured biceps tendon at the radial tuberosity, two Bicepsbutton(™) (Arthrex, Naples, FL, USA) were intramedullary positioned to the anterior cortex. The surgical procedure is described in detail. This technique has been performed in a first series of 3 patients with acute distal biceps tendon ruptures. RESULTS: All patients were very satisfied after surgery and would undergo the same surgical procedure again. All patients regained full range of elbow motion with comparable strength of forearm supination and elbow flexion measured against the uninjured arm at 6 months of follow-up. No neurovascular complications have been occured. CONCLUSION: Double intramedullary cortical button repair has shown to be a safe and reliable fixation method for distal biceps tendon rupture in a small series of patients. Preliminary results are encouraging.

Quercetin protects primary human osteoblasts exposed to cigarette smoke through activation of the antioxidative enzymes HO-1 and SOD-1.

Smokers frequently suffer from impaired fracture healing often due to poor bone quality and stability. Cigarette smoking harms bone cells and their homeostasis by increased formation of reactive oxygen species (ROS). The aim of this study was to investigate whether Quercetin, a naturally occurring antioxidant, can protect osteoblasts from the toxic effects of smoking. Human osteoblasts exposed to cigarette smoke medium (CSM) rapidly produced ROS and their viability decreased concentration- and time-dependently. Co-, pre- and postincubation with Quercetin dose-dependently improved their viability. Quercetin increased the expression of the anti-oxidative enzymes heme-oxygenase- (HO-) 1 and superoxide-dismutase- (SOD-) 1. Inhibiting HO-1 activity abolished the protective effect of Quercetin. Our results demonstrate that CSM damages human osteoblasts by accumulation of ROS. Quercetin can diminish this damage by scavenging the radicals and by upregulating the expression of HO-1 and SOD-1. Thus, a dietary supplementation with Quercetin could improve bone matter, stability and even fracture healing in smokers.

Concomitant Intra-Articular Glenohumeral Lesions in Fractures of the Scapula Body.

BACKGROUND: Scapula body fractures are rare injuries with an incidence of 1% of all fractures accounting for 3% to 5% of all upper extremity fractures. Fractures of the scapula commonly result from high-energetic trauma and fall from great height. While several studies focused on concomitant injuries of chest and head as well as the cervical spine, up to now in the common literature, no study exists analyzing the prevalence of concomitant intra-articular glenohumeral injury following extra-articular scapular fracture. OBJECTIVES: The aim of this study was to analyze the prevalence of concomitant intra-articular glenohumeral injuries in acute fractures of the scapula by performing magnetic resonance imaging (MRI) of the shoulder joint. STUDY DESIGN AND METHODS: This prospective cohort study was performed at our academic Level I trauma center from November 2014 to October 2016. According to our clinical algorithm, all patients suffering from an acute scapula body fracture primarily underwent computed tomography (CT) for assigning the fracture according to the Orthopedic Trauma Association (OTA)-classification and therapy planning. In addition, 3 T MRI-scans of all patients were performed within seven days after trauma. RESULTS: Twenty-one (16 male/5 female, mean age 53 years (25-83 y) patients with scapula body fractures (OTA 14.A3.2 80.1%, OTA 14.A3.1 4.8%, OTA14.B3.1 4.8%, OTA14.C3 9.5%) were enrolled. MRI revealed 11 acute intra-articular injuries in 8 of 21 patients (38%). In all 21 patients, hematoma of the rotator cuff and periarticular muscles was present. Three patients (14.3%) presented a partial bursa sided tear of the supraspinatus tendon, whereas in 5 (23.8%), a partial articular sided supraspinatus tendon tear and in 2 (9.5%) patients, a subtotal tear was observed. One patient (4.8%) showed a complete transmural supraspinatus tendon tear. CONCLUSIONS: Traumatic concomitant glenohumeral injuries in scapula body fractures seem to be more frequent than generally expected. Subsequent surgical treatment of these formerly missed but therapy-relevant injuries may increase functional outcome and reduce the postoperative complication rate following scapula body fractures.

Fractures of the proximal ulna: current concepts in surgical management.

Fractures of the proximal ulna range from simple olecranon fractures to complex Monteggia fractures or Monteggia-like lesions involving damage to stabilizing key structures of the elbow (i.e. coronoid process, radial head, collateral ligament complex).In complex fracture patterns a computerized tomography scan is essential to properly assess the injury severity.Exact preoperative planning for the surgical approach is vital to adequately address all fracture parts (base coronoid fragments first).The management of olecranon fractures primarily comprises tension-band wiring in simple fractures as a valid treatment option, but modern plate techniques, especially in comminuted or osteoporotic fracture types, can reduce implant failure and potential implant-related soft tissue irritation.For Monteggia injuries, the accurate anatomical restoration of ulnar alignment and dimensions is crucial to adjust the radiocapitellar joint.Caution is advised if the anteromedial facet (anatomical insertion of the medial collateral ligament) of the coronoid process is affected, to avoid posteromedial instability.Radial head reconstruction or replacement is essential in Monteggia-like lesions to restore normal elbow function.The postoperative rehabilitation programme should involve active elbow motion exercises without limitations as early as possible following surgery to avoid joint stiffness. Cite this article: EFORT Open Rev 2019;4:1-9. DOI: 10.1302/2058-5241.4.180022.

Metabolomics: quantification of intracellular metabolite dynamics.

The rational improvement of microbial strains for the production of primary and secondary metabolites ('metabolic engineering') requires a quantitative understanding of microbial metabolism. A process by which this information can be derived from dynamic fermentation experiments is presented. By applying a substrate pulse to a substrate-limited, steady state culture, cellular metabolism is shifted away from its metabolic steady state. With the aid of a rapid sampling and quenching routine it is possible to take 4-5 samples per second during this process, thus capturing the metabolic response to this stimulus. Over 30 metabolites, nucleotides and cofactors from Escherichia coli metabolism can be extracted and analysed using a range of different techniques, for example enzymatic assays, HPLC and LC-MS methods. Using different substrates as limiting and pulse-substrates (glucose, glycerol), different metabolic pathways and substrate uptake systems are investigated. The resulting plots of intracellular metabolite concentrations against time serve as a data basis for modelling microbial metabolic networks.

Reconstruction of displaced acromio-clavicular joint dislocations using a triple suture-cerclage: description of a safe and efficient surgical technique.

PURPOSE: In this retrospective study we investigated the clinical and radiological outcome after operative treatment of acute Rockwood III-V injuries of the AC-joint using two acromioclavicular (AC) cerclages and one coracoclavicular (CC) cerclage with resorbable sutures. METHODS: Between 2007 and 2009 a total of 39 patients fit the inclusion criteria after operative treatment of acute AC joint dislocation. All patients underwent open reduction and anatomic reconstruction of the AC and CC-ligaments using PDS® sutures (Polydioxane, Ethicon, Norderstedt, Germany). Thirty-three patients could be investigated at a mean follow up of 32±9 months (range 24-56 months). RESULTS: The mean Constant score was 94.3±7.1 (range 73-100) with an age and gender correlated score of 104.2%±6.9 (88-123%). The DASH score (mean 3.46±6.6 points), the ASES score (94.6±9.7points) and the Visual Analogue Scale (mean 0.5±0,6) revealed a good to excellent clinical outcome. The difference in the coracoclavicular distance compared to the contralateral side was <5 mm for 28 patients, between 5-10 mm for 4 patients, and more than 10 mm for another patient. In the axial view, the anterior border of the clavicle was within 1 cm (ventral-dorsal direction) of the anterior rim of the acromion in 28 patients (85%). Re-dislocations occured in three patients (9%). CONCLUSION: Open AC joint reconstruction using AC and CC PDS cerclages provides good to excellent clinical results in the majority of cases. However, radiographically, the CC distance increased significantly at final follow up, but neither the amount of re-dislocation nor calcifications of the CC ligaments or osteoarthritis of the AC joint had significant influence on the outcome. LEVEL OF EVIDENCE: Case series, Level IV.

Biomechanical in vitro validation of intramedullary cortical button fixation for distal biceps tendon repair: a new technique.

BACKGROUND: Extramedullary cortical button-based fixation for distal biceps tendon ruptures exhibits maximum load to failure in vitro but cannot restore the anatomic footprint and has the potential risk for injury to the posterior interosseous nerve. HYPOTHESIS: Double intramedullary cortical button fixation repair provides superior fixation strength to the bone when compared with single extramedullary cortical button-based repair. STUDY DESIGN: Controlled laboratory study. METHODS: The technique of intramedullary cortical button fixation with 1 or 2 buttons was compared with single extramedullary cortical button-based repair using 12 paired human cadaveric elbows. All specimens underwent computed tomography analysis to determine intramedullary dimensions of the radial tuberosity as well as the thickness of the anterior and posterior cortices before biomechanical testing. Maximum load to failure and failure modes were recorded. For baseline measurements, the native tendon was tested for maximum load to failure. RESULTS: The intramedullary area of the radial tuberosity provides sufficient space for single or double intramedullary cortical button implantation. The mean thickness of the anterior cortex was 1.13 ± 0.15 mm, and for the posterior cortex it was 1.97 ± 0.48 mm (P < .001). We found the highest loads to failure for double intramedullary cortical button fixation with a mean load to failure of 455 ± 103 N, versus 275 ± 44 N for single intramedullary cortical button fixation (P < .001) and 305 ± 27 N for single extramedullary cortical button-based technique (P = .003). There were no statistically significant differences between single intramedullary and single extramedullary button fixation repair (P = .081). The mean load to failure for the native tendon was 379 ± 87 N. CONCLUSION: Double intramedullary cortical button fixation provides the highest load to failure in the specimens tested. CLINICAL RELEVANCE: Double intramedullary cortical button fixation provides reliable fixation strength to the bone for distal biceps tendon repair and potentially minimizes the risk of posterior interosseous nerve injury. Further, based on a 2-point-fixation, this method may offer a wider, more anatomic restoration of the distal biceps tendon to its anatomic footprint.

Genetic algorithms as a tool for capillary electrophoresis method development.

Capillary electrophoresis is a powerful and versatile analytical tool due to the wide range of separation variables and separation methods possible. CE permits the combination of multiple separation mechanisms (e.g., chiral modifiers, polarity, pH) for the analysis of a large variety of compounds. The main advantage of CE (i.e., the broad range of separation variables) has thus far limited its application. This is due to the nonlinear influence and interactions of different parameters on separation quality, making it difficult to predict trends for the optimization of separation systems and hence hindering CE method development. In this paper, we present a means for rationalizing method development for CE separations using a genetic algorithm. We provide selected examples of separation enhancements achieved in the field of nucleotide and nucleotide sugar separation. An improved method for the enantioselective separation of amino acid derivatives (2-acetylamino-3-phenyl-propionic acid) will also be presented.

MMT--a pathway modeling tool for data from rapid sampling experiments.

The identification of metabolic regulation is a major concern in metabolic engineering. Metabolic regulation phenomena depend on intracellular compounds such as enzymes, metabolites and cofactors. A complete understanding of metabolic regulation requires quantitative information about these compounds under in vivo conditions. This quantitative knowledge in combination with the known network of metabolic pathways allows the construction of mathematical models that describe the dynamic changes in metabolite concentrations over time. Rapid sampling combined with pulse experiments is a useful tool for the identification of metabolic regulation owing to the transient data they provide. Enzymatic tests in combination with ESI-LC-MS (Electrospray Ionization Liquid Chromatographic Tandem Mass Spectrometry) and HPLC measurements have been used to identify up to 30 metabolites and nucleotides from rapid sampling experiments. A metabolic modeling tool (MMT) that is built on a relational database was developed specifically for analysis of rapid sampling experiments. The tool allows to construct complex pathway models with information stored in the relational database. Parameter fitting and simulation algorithms for the resulting system of Ordinary Differential Equations (ODEs) are part of MMT. Additionally explicit sensitivity functions are calculated. The integration of all necessary algorithms in one tool allows fast model analysis and comparison. Complex models have been developed to describe the central metabolic pathways of Escherichia coli during a glucose pulse experiment.