Role of PDGF-A/B Ligands in Cardiac Repair After Myocardial Infarction.

Platelet-derived growth factors (PDGFs) are powerful inducers of cellular mitosis, migration, angiogenesis, and matrix modulation that play pivotal roles in the development, homeostasis, and healing of cardiac tissues. PDGFs are key signaling molecules and important drug targets in the treatment of cardiovascular disease as multiple researchers have shown that delivery of recombinant PDGF ligands during or after myocardial infarction can reduce mortality and improve cardiac function in both rodents and porcine models. The mechanism involved cannot be easily elucidated due to the complexity of PDGF regulatory activities, crosstalk with other protein tyrosine kinase activators, and diversity of the pathological milieu. This review outlines the possible roles of PDGF ligands A and B in the healing of cardiac tissues including reduced cell death, improved vascularization, and improved extracellular matrix remodeling to improve cardiac architecture and function after acute myocardial injury. This review may highlight the use of recombinant PDGF-A and PDGF-B as a potential therapeutic modality in the treatment of cardiac injury.

Trochlear Osteonecrosis After a Nonoperative Lateral Humeral Condyle Fracture in a Child.

This patient originally presented at the age of 2 years with a 1-mm displaced lateral humeral condyle fracture after a fall. He was treated nonoperatively in a long-arm cast, and serial x-rays were followed for 1 month. At the 1-month clinic visit, the lateral condyle demonstrated excellent alignment and healing, and the long-arm cast was removed. He eased back into activities and was doing well at 3 months. He returned over 4 years later, at the age of 7 years, with the report of elbow clicking with motion. At that time, imaging demonstrated collapse of the ulnohumeral articulation.

Advances in the Generation of Functional ß-cells from Induced Pluripotent Stem Cells As a Cure for Diabetes Mellitus.

Diabetes mellitus is one of the leading causes of death worldwide. Loss and functional failure of pancreatic ß-cells, the parenchyma cells in the islets of Langerhans, progress diabetes mellitus. The increasing incidence of this metabolic disorder necessitates efficient strategies to produce functional ß-cells for treating diabetes mellitus. Human induced Pluripotent Stem Cells (hiPSC), hold potential for treating diabetes ownig to their self-renewal capacity and the ability to differentiate into ß- cells. iPSC technology also provides unlimited starting material to generate differentiated cells for regenerative applications. Progress has also been made in establishing in-vitro culture protocols to yield definitive endoderm, pancreatic endoderm progenitor cells and ß-cells via different reprogramming strategies and growth factor supplementation. However, these generated ß-cells are still immature, lack functional characteristics and exhibit lower capability in reversing the diseases conditions. Current methods employed to generate mature and functional ß-cells include; use of small and large molecules to enhance the reprogramming and differentiation efficiency, 3D culture systems to improve the functional properties and heterogeneity of differentiated cells. This review details recent advancements in the generation of mature ß-cells by reprogramming stem cells into iPSCs that are further programmed to ß-cells. It also provides deeper insight into current reprogramming protocols and their efficacy, focusing on the underlying mechanism of chemical-based approach to generate iPSCs. Furthermore, we have highlighted the recent differentiation strategies both in-vitro and in-vivo to date and the future prospects in the generation of mature ß-cells.

Proximity of Lateral Critical Structures to the All-Epiphyseal Outside-In Femoral Tunnels in Pediatric Anterior Cruciate Ligament Reconstruction.

PURPOSE: To describe the proximity of the lateral critical structures (peroneal nerve [PN], popliteus tendon [PT], lateral collateral ligament [LCL], and articular cartilage [AC]) to the femoral tunnel for outside-in all-epiphyseal anterior cruciate ligament (ACL) reconstruction in reference to knee flexion angle. METHODS: All-epiphyseal ACL reconstructions were performed in 12 human cadaveric knees using arthroscopy and outside-in drilling for anatomic femoral tunnel placement that was ensured by identifying the center of the total ACL footprint. Fluoroscopy was used to confirm tunnel position and reconstructions were performed with quadrupled semitendinosus and gracilis autograft with Xtendobutton (Smith & Nephew, Andover, MA) fixation on the femoral side. After reconstruction, the lateral side of the knee was dissected and the LCL, PT, distal and posterior AC, and the PN were identified. The distances of these structures from the center of the exiting femoral tunnel were then measured using a digital caliper at 0°, 30°, 60°, 90°, and 120° of knee flexion. Any gross damage to these structures caused by the femoral drilling was also noted. Data were compiled and the mean and standard deviations (SD) of the distances from the pin to the structures of interest were calculated. The normality of the data at each flexion angle was assessed using Shapiro-Wilk tests (P > .05), and the relationship between flexion angle and average distance was evaluated using repeated measures analysis of variance (P < .05). Any significant relationships were then evaluated using paired t-tests (P < .05) with a Benjamini-Hochberg adjustment for each possible pair of flexion angles. Averages, SD, and P values are reported. A post hoc power analysis was performed. RESULTS: The violation of the LCL was noted in 3 specimens and that of the PT in 1 specimen as a result of femoral tunnel drilling at flexion angles ranging from 90° to 120°. The distance between the PT and the femoral tunnel also decreased significantly (P < .001) with knee flexion with average distances to the center of 8.07 mm at 0°, 7.75 mm at 30°, 6.33 mm at 60°, 4.12 mm at 90°, and 1.89 mm at 120°. The mean ± SD for distances from the femoral tunnel to the center of the PT at 0° was 8.07 ± 7.15, at 30° 7.75 ± 6.66, at 60° 6.33 ± 6.79, at 90° 4.12 ± 5.71, and at 120° 1.89 ± 5.56. As the knee was progressively flexed, the distance between the LCL and the femoral tunnel decreased significantly (P < .001) with an average distance of 6.52 mm at 0°, 6.26 mm at 30°, 4.23 mm at 60°, 2.38 mm at 90°, and 0.4 mm at 120°. The mean ± SD for distances from the femoral tunnel to the center of the LCL at 0° was 6.52 ± 5.93, at 30° 6.26 ± 7.32, at 60° 4.23 ± 7.82, 90° 2.38 ± 7.31, and at 120° 0.4 ± 7.01. The PN was remote from the femoral tunnel at all flexion angles with a mean distance of 42.83 to 59.22 mm. The PN to guide pin distance increased significantly with progressive knee flexion (P < .001). The AC was not damaged in all specimens. CONCLUSIONS: The LCL and PT are at significant risk during percutaneous femoral drilling for all-epiphyseal anatomic ACL reconstruction using an outside-in technique. This risk was maximized at 120° flexion and minimized in full extension. These findings suggest that the optimal position for femoral drilling in all-epiphyseal ACL reconstruction is full or near-full extension of the knee that can be accomplished by placing the knee in 30° of flexion (after using fluoroscopic guidance to pass the guide pin past the lateral critical structures) to visualize the footprint of the ACL. CLINICAL RELEVANCE: Information garnered from this study may help clinicians better understand the risk to the lateral critical structures when an outside-in femoral tunnel is not drilled in the appropriate degree of knee flexion.

Vancomycin-induced thrombocytopenia in a newborn.

Neonatal thrombocytopenia is common and is frequently seen in neonatal sepsis. Drug-induced thrombocytopenia is likely to be missed unless a high index of suspicion is present. Changing of antibiotics for assumed nonresolution of sepsis may lead to persistent thrombocytopenia in a neonate if drug-induced thrombocytopenia is missed. Vancomycin-induced neonatal thrombocytopenia is rarely described in scientific literature. We describe a newborn who was diagnosed with early onset sepsis and vancomycin-induced thrombocytopenia. Other causes of thrombocytopenia such as sepsis, alloimmune thrombocytopenia, thrombosis etc. were excluded. The platelet counts normalized within 72 h of stopping vancomycin. Vancomycin-induced IgM platelet antibodies could not be done in our case (due to financial constraints), but their absence does not exclude the diagnosis of vancomycin-induced thrombocytopenia.

Can Flexible Instruments Create Adequate Femoral Tunnel Lengths at 90° of Knee Flexion in Anterior Cruciate Ligament Reconstruction?

PURPOSE: This study aims to study femoral tunnel lengths drilled with a flexible reamer and the distance to important lateral structures obtained by flexing the knee at various angles and by drilling the guide pins arthroscopically to resemble clinical practice. The purpose of this cadaveric study was twofold: 1. to determine whether femoral tunnel lengths of greater than 20 mm can be created with a flexible reamer system at 90 ° of knee flexion and 2. to determine whether the lateral structures of the knee are safe with this technique. METHODS: Ten fresh cadaveric knees were utilized. The intra-osseous length can be measured with a specially de - signed flexible guide pin. Flexible pins were inserted with the knee at 70°, 90°, and 120° of flexion. The intra-osseous length was measured with the measuring device. Each speci - men was dissected around the lateral aspect of the knee to identify the critical structures, the common peroneal nerve, and the LCL. The distance from the guide pins to the com - mon peroneal nerve and femoral attachment of the LCL were measured with a standard flexible paper ruler to the nearest millimeter. RESULTS: There is a trend for progressively increasing mean intra-osseous length associated with increased flexion of the knee. The mean intra-osseous length for 70° flexion was 25.2 mm (20 mm to 32 mm), which was statistically significant when compared to mean intra-osseous lengths of 32.1 mm (22 mm to 45 mm) and 38.0 mm (34 mm to 45 mm) in the 90° and 120° flexion groups, respectively (p < 0.05). There were no significant differences among the groups with respect to distance to the LCL. There is a trend toward longer distances to the common peroneal nerve with increased flexion. There was a statistically significant dif - ference when comparing 120° versus 70° (p < 0.05). CONCLUSIONS: This study that shows that adequate femoral tunnel lengths can be safely created without knee hyperflex - ion using flexible instruments via an anteromedial portal.

Intrapelvic displacement of a trial femoral head during total hip arthroplasty and a method to retrieve it.

We describe a technique to retrieve a dislodged femoral trial during total hip arthroplasty. During a revision total hip arthroplasty performed through a direct lateral approach, the femoral trial head was dislodged deep into the pelvis, superior and anterior to the hip joint and behind the anterior pelvic rim. This was retrieved via a posterior approach through the same incision by manipulating the trial head through the pelvis from the anterior to posterior direction. To our knowledge, this technique has not been described previously.

Complications using bioabsorbable cross-pin femoral fixation: a case report and review of the literature.

The use of bioabsorbable cross-pin transcondylar fixation has remained a viable option for femoral fixation in anterior cruciate ligament reconstruction. Although numerous biomechanical studies have demonstrated high fixation strength and minimal slippage with use of this method of fixation, there have been increasing reports of a variety of clinical complications associated with these implants. We reviewed the literature for all complications associated with the Bio-TransFix implant and present a case report of a patient status after ACL reconstruction using Bio-TransFix cross-pin femoral fixation with iliotibial band friction syndrome from a broken cross-pin four month post-operatively.

Isolated pectoralis minor tendon tear in a professional ice hockey player--radiographic findings and presentation.

The purpose of this paper is to report the clinical signs, symptoms, imaging findings and treatment of an isolated pectoralis minor tendon tear in a professional hockey player.

Arthroscopic repair of full-thickness rotator cuff tears: is there tendon healing in patients aged 65 years or older?

PURPOSE: The aim of this study was to assess tendon healing and clinical results of rotator cuff tears (RCTs) repaired arthroscopically in patients aged 65 years or older. METHODS: Between January 2001 and December 2004, 88 patients with a mean age of 70 years (range, 65 to 85 years) had arthroscopic RCT repair. The repair was performed on 54 women (61%). The dominant arm was involved in 72 patients (82%). RCT included more than 2 tendons in 45 cases. Functional outcomes were assessed by use of the Constant score and Simple Shoulder Test. Tendon healing was estimated by use of a computed tomography (CT) arthrogram, which was obtained 6 months postoperatively, and was classified into 3 categories: stage 1, watertight and anatomic healing; stage 2, watertight and partial healing; and stage 3, not watertight and retear. RESULTS: The mean duration of follow-up was 41 months (range, 24 to 77 months). The mean clinical outcome scores all improved significantly at the time of the final follow-up (P < .01). Computed tomography arthrogram imaging showed 27 shoulders with a stage 1 repair, 20 with a stage 2 repair, and 34 with a stage 3 repair. The retear rate was 42% (34 of 81). The patients with tendon healing stage 1 or 2 had a significantly superior functional outcome in terms of overall scores and strength compared with the stage 3 repairs (P < .01). In our study we had 39 isolated supraspinatus tears (small or medium tears); 11 (28.9%) had a retear (stage 3). CONCLUSIONS: Arthroscopic repair in patients aged 65 years or older can yield tendon healing resulting in significant functional improvement. Our data suggest that arthroscopic repair can be considered successful for the older patient specifically when the tear is limited to the supraspinatus tendon. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Repeat 2-stage revision for recurrent infection of total hip arthroplasty.

Eleven patients who developed reinfection after 2-stage revision for infected total hip arthroplasty (THA) were treated with a repeat 2-stage rerevision. Of the 11 rerevisions, 4 were successful, with no recurrent infection at mean follow-up of 44 months. Reinfection occurred in 7 patients of whom 6 involved either a significantly compromised host or poor local wound status. Clinical symptoms of infection were controlled in 4 of the 7 reinfected cases with antibiotic therapy in 2, irrigation and debridement in 1, and a third 2-stage revision THA in 1. Repeat 2-stage treatment of infected THA is associated with a high failure rate. However, successful results can be achieved particularly if the host is not immunocompromised and healthy soft tissue coverage is present.

In vitro biomechanical comparison of three different types of single- and double-row arthroscopic rotator cuff repairs: analysis of continuous bone-tendon contact pressure and surface during different simulated joint positions.

HYPOTHESIS: We assessed bone-tendon contact surface and pressure with a continuous and reversible measurement system comparing 3 different double- and single-row techniques of cuff repair with simulation of different joint positions. MATERIALS AND METHODS: We reproduced a medium supraspinatus tear in 24 human cadaveric shoulders. For the 12 right shoulders, single-row suture (SRS) and then double-row bridge suture (DRBS) were used. For the 12 left shoulders, DRBS and then double-row cross suture (DRCS) were used. Measurements were performed before, during, and after knot tying and then with different joint positions. RESULTS: There was a significant increase in contact surface with the DRBS technique compared with the SRS technique and with the DRCS technique compared with the SRS or DRBS technique. There was a significant increase in contact pressure with the DRBS technique and DRCS technique compared with the SRS technique but no difference between the DRBS technique and DRCS technique. CONCLUSIONS: The DRCS technique seems to be superior to the DRBS and SRS techniques in terms of bone-tendon contact surface and pressure.

Discoid lateral meniscus in children.

The discoid lateral meniscus is the most common abnormal meniscal variant in children. It affects the shape and mobility of the menisci, altering the normal mechanical relationships between the articulating surfaces of the knee and predisposing it to injury. The incidence of discoid lateral meniscus is estimated to be 1%-3% in the pediatric population and the condition is bilateral in 10%-20% of patients (Stanitski, 2002). An otherwise asymptomatic knee with an incidentally detected discoid meniscus does not require surgical intervention. However, a discoid lateral meniscus is much more likely to tear, and many children develop pain as well as mechanical symptoms (popping, snapping, locking, or giving way of the knee). Recent improvements in arthroscopic technique have led to greater attempts to stabilize, sculpt, and repair the torn discoid lateral meniscus. This article will review the classification, clinical presentation, diagnostic/imaging studies, and treatment options for a discoid lateral meniscus in children.

The time for functional recovery after arthroscopic rotator cuff repair: correlation with tendon healing controlled by computed tomography arthrography.

PURPOSE: We investigated how soon postoperative functional recovery became significant after arthroscopic rotator cuff repair and the influence of tendon healing. METHODS: We conducted a prospective study on 114 cases of full-thickness rotator cuff tears arthroscopically repaired from January 2001 to December 2003. All patients were evaluated by the Constant scoring system at 3, 6, 12, and 24 months after surgery and at last follow-up. Computed tomography arthrography was done at 6 months postoperatively to study the progression of tendon healing. RESULTS: The Constant score significantly improved from the third month after surgery (P < .0001) until the twelfth month, after which it stabilized (P < .0001). At last follow-up (31 months), the mean score was 80.1 points (range, 50 to 95 points). Female sex (P < .0001), upper-limb heavy work (P < .0001), poor bone quality (P = .039), and absence of healing (P = .002) were negative predictive factors. In particular, the absence of tendon healing leads to a worsening of the results from the twelfth month onward. CONCLUSIONS: Arthroscopic repair of rotator cuff lesions as performed in this study gives very good results in terms of functional recovery. Our study showed functional recovery as early as 3 months after surgery and further improvement over the first year, followed by stabilization. We found that female sex, upper-limb heavy work, poor bone quality, and lack of tendon healing were all negatively associated with outcome. Patients presenting with a retear differed from the other patients, in that their clinical progression showed a significant rise in the Constant score over the first year, with a lowering of the score thereafter. LEVEL OF EVIDENCE: Level IV, therapeutic case series.