Recapitulation of normal collagen architecture in embryonic wounded corneas.

Wound healing is characterized by cell and extracellular matrix changes mediating cell migration, fibrosis, remodeling and regeneration. We previously demonstrated that chick fetal wound healing shows a regenerative phenotype regarding the cellular and molecular organization of the cornea. However, the chick corneal stromal structure is remarkably complex in the collagen fiber/lamellar organization, involving branching and anastomosing of collagen bundles. It is unknown whether the chick fetal wound healing is capable of recapitulating this developmentally regulated organization pattern. The purpose of this study was to examine the three-dimensional collagen architecture of wounded embryonic corneas, whilst identifying temporal and spatial changes in collagen organization during wound healing. Linear corneal wounds that traversed the epithelial layer, Bowman´s layer, and anterior stroma were generated in chick corneas on embryonic day 7. Irregular thin collagen fibers are present in the wounded cornea during the early phases of wound healing. As wound healing progresses, the collagen organization dramatically changes, acquiring an orthogonal arrangement. Fourier transform analysis affirmed this observation and revealed that adjacent collagen lamellae display an angular displacement progressing from the epithelium layer towards the endothelium. These data indicate that the collagen organization of the wounded embryonic cornea recapitulate the native macrostructure.

Periocular neural crest cell differentiation into corneal endothelium is influenced by signals in the nascent corneal environment.

During ocular development, periocular neural crest cells (pNC) migrate into the region between the lens and presumptive corneal epithelium to form the corneal endothelium and stromal keratocytes. Although defects in neural crest cell development are associated with ocular dysgenesis, very little is known about the molecular mechanisms involved in this process. This study focuses on the corneal endothelium, a monolayer of specialized cells that are essential for maintaining normal hydration and transparency of the cornea. In avians, corneal endothelial cells are first to be specified from the pNC during their migration into the presumptive corneal region. To investigate the signals required for formation of the corneal endothelium, we utilized orthotopic and heterotopic injections of dissociated quail pNC into chick ocular regions. We find that pNC are multipotent and that the nascent cornea is competent to induce differentiation of ectopically injected pNC into corneal endothelium. Injected pNC downregulate expression of multipotency transcription factors and upregulate genes that are consistent with ontogenesis of the chick corneal endothelium. Importantly, we showed that TGFß2 is expressed by the nascent lens and the corneal endothelium, and that TGFß signaling plays a critical role in changing the molecular signature of pNC in vitro. Collectively, our results demonstrate the significance of the ocular environmental cues towards pNC differentiation, and have potential implications for clinical application of stem cells in the anterior segment.

Outcomes of closed reduction and periarticular pinning of base and shaft fractures of the proximal phalanx.

PURPOSE: To review the results of periarticular pinning of extra-articular fractures of the proximal phalanx base and shaft. METHODS: A retrospective review was performed of the senior author's practice (C.S.M.) from 2006 to 2012. The inclusion criteria were patients older than 18 years of age who underwent periarticular pinning of base or shaft fractures of the proximal phalanx. Age, sex, fracture location, fracture pattern, and time to surgery were recorded. Outcome measures were range of motion, time to healing, and complication rate. RESULTS: A total of 43 patients with 50 fractures were identified. There were 19 men and 24 women with 16 shaft and 34 base fractures. Five fractures were open. The little finger was involved in 62%, the ring finger in 30%, and the index and middle fingers in 4% each. Most fractures were transverse or oblique, and just over half had comminution and/or impaction. Average follow-up was 17 weeks, and average time to clinical union was 35 days. Nine patients (18%) were lost to follow-up. Twenty-six fingers had excellent results (63%), lacking less than 10° of total motion. Seven patients (17%) had good results, lacking less than 20° of motion; 7 patients had fair results (17%); and 1 patient had a poor result. Three patients (7%) developed stiffness requiring tenolysis. There were 2 pin-site infections, 1 of which resulted in a loss of reduction. Results for shaft and base fractures were not significantly different. CONCLUSIONS: Percutaneous periarticular pinning is an acceptable option for unstable base and shaft fractures of the proximal phalanx. Most fractures healed within 4 weeks. The majority of patients had excellent or good results. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Kinematic determinants of anterior knee pain in cerebral palsy: a case-control study.

OBJECTIVE: To quantify the role patellofemoral and tibiofemoral kinematics may play in development of anterior knee pain (AKP) in individuals with cerebral palsy (CP). DESIGN: Case-control. SETTING: Clinical research center. PARTICIPANTS: Knees from individuals with diagnosed CP (n=20) and control knees (n=40) were evaluated. Controls were matched for sex and age based on the group average. Matching by height and weight was a secondary priority. Subjects in the control cohort were asymptomatic with no history of lower leg abnormalities, surgery, or major injury. Only individuals who were physically capable of sustaining slow, cyclic knee flexion-extension for 2.5 minutes and had no contraindications to magnetic resonance imaging were enrolled. Both groups were samples of convenience. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Three-dimensional patellofemoral and tibiofemoral joint kinematics, acquired during active leg extension, under volitional control. RESULTS: Participants with CP and AKP (n=8) demonstrated significantly greater patellofemoral extension, valgus rotation, and superior and posterior displacement relative to controls and to the subgroup of participants with CP and no AKP (n=12). Patellofemoral extension discriminated AKP in individuals with CP with 100% accuracy. CONCLUSIONS: In quantifying the 3-dimensional, in vivo knee joint kinematics during a volitional extension task, kinematic markers that discriminate AKP in individuals with CP were identified. This provides an ability to predict which individuals with CP are most likely to develop AKP and could enable aggressive conservative treatment, aimed at reducing patella alta and excessive patellofemoral extension, to be prescribed before considering surgical options. The current findings will likely lead to improved clinical diagnostics and interventions for individuals with CP, with the ultimate goal of helping maintain, if not improve, functional mobility throughout the lifespan.

Corticocancellous olecranon autograft for metacarpal defect reconstruction: a case report.

BACKGROUND: High-energy injuries to the hand frequently lead to bone defects as well as soft tissue loss. Early bone grafting of defects is well established in the literature; however, few options are available for autologous corticocancellous grafts. Most frequently cited studies describe the iliac crest or the distal radius donor sites. METHODS: In this case report, we describe a new technique of obtaining corticocancellous bone graft from the olecranon. RESULTS: Complete union of the segmental defect was achieved with this technique. CONCLUSIONS: The olecranon donor site is outside the zone of injury and therefore safe to access, but within the upper extremity, thus avoiding the need for harvest from a distant site such as the iliac crest or the distal femur. Additional benefits of this site are the greater volume of graft that can be harvested compared to the distal radius as well as a more optimal ratio of cancellous to cortical graft available, compared to the iliac crest where the graft may be excessively cortical in nature.