The purpose of this experiment was to test the susceptibility to retinal ganglion cell (RGC) axon loss and RGC layer cell loss from experimental glaucoma among 3 mouse strains, and between younger and older mice. We obstructed the mouse aqueous outflow channels by injecting 2 μL of 6 μm diameter, polystyrene beads followed by 3 μL of viscoelastic solution into the anterior chamber with a glass micropipette. We evaluated intraocular pressure (IOP) and damage to RGC as measured by optic nerve axon counts and RGC layer neuron counts in 3 strains of young mice (2 month old C57BL/ 6, DBA/2J, and CD1) and 10 month C57BL/6 mice. Bead and viscoelastic injection produced IOP elevation at ≥1 time point in 94.1% of eyes (112/119), with mean IOP difference from fellow eyes of 4.4 ± 3.0 mmHg. By 6-12 weeks, injected eyes were 10.8% longer and 7.6% wider (p <0.0001). Young DBA/2J and C57BL/6 eyes increased axial length significantly more than young CD1 or older C57BL/6 (all p ≤0.02). RGC layer and axon loss was greatest in CD1 mice, significantly more than the other groups (p from 0.04 to <0.0001). Young C57BL/6 eyes elongated more and lost more RGC layer cells than older C57BL/6 mice (p =0.02 and 0.01, respectively). With this mouse glaucoma model, there was differential susceptibility to ocular elongation and RGC layer and axon damage among mouse strains and by age. Factors that determine sensitivity to RGC injury can be studied using transgenic mouse strains with inducible models.

The purpose of this research was to develop a reliable and repeatable inflation protocol to measure the scleral inflation response of mouse eyes to elevations in intraocular pressure (IOP), comparing the inflation response exhibited by the sclera of younger and older C57BL/6 mice. Whole, enucleated eyes from younger (2 month) and older (11 month) C57BL/6 mice were mounted by the cornea on a custom fixture and inflated according to a load-unload, ramp-hold pressurization regimen via a cannula connected to a saline-filled programmable syringe pump. First, the tissue was submitted to three load-unload cycles from 6 mmHg to 15 mmHg at a rate of 0.25 mmHg/s with ten minutes of recovery between cycles. Next the tissue was submitted to a series of ramphold tests to measure the creep behavior at different pressure levels. For each ramp-hold test, the tissue was loaded from 6 mmHg to the set pressure at a rate of 0.25 mmHg/s and held for 30 minutes, and then the specimens were unloaded to 6mmHg for 10 minutes. This sequence was repeated for set pressures of: 10.5, 15, 22.5, 30, 37.5, and 45 mmHg. Scleral displacement was measured using digital image correlation (DIC), and fresh scleral thickness was measured optically for each specimen after testing. For comparison, scleral thickness was measured on untested fresh tissue and epoxy-fixed tissue from age-matched animals. Comparing the apex displacement of the different aged specimens, the sclera of older animals had a statistically significant stiffer response to pressurization than the sclera of younger animals. The stiffness of the pressure-displacement response of the apex measured in the small-strain (6-15 mmHg) and the large-strain (37.5-45 mmHg) regime, respectively, were 287 ± 100 mmHg/mm and 2381 ± 191 mmHg/mm for the older tissue and 193 ± 40 mmHg/mm and 1454 ± 93 mmHg/mm for the younger tissue (Student t-test, p < 0.05). The scleral thickness varied regionally, being thickest in the peripapillary region and thinnest at the equator. Fresh scleral thickness did not differ significantly by age in this group of animals. This study presents a reliable inflation test protocol to measure the mechanical properties of mouse sclera. The inflation methodology was sensitive enough to measure scleral response to changes in IOP elevations between younger and older C57BL/6 mice. Further, the specimen-specific scleral displacement profile and thickness measurements will enable future development of specimen-specific finite element models to analyze the inflation data for material properties.

The TonoLab accurately reflects IOP in both normal mice and in eyes of mice with experimental or spontaneous glaucoma, with no detectable effect of age.

To determine if the absence of c-Jun N-terminal kinase 3 (JNK3) in the mouse retina would reduce retinal ganglion cell (RGC) loss in mice with experimental glaucoma. C57BL/6 mice underwent experimental intraocular pressure (IOP) elevation with a bead/viscoelastic injection into one eye. One-half of the mice were Jnk3 homozygous knockouts (KO) and were compared to wild type (WT) mice. IOP was measured under anesthesia with the TonoLab, axial length was measured post-mortem with calipers after inflation to 15 mm Hg, and RGC layer counts were performed on retinal whole mount images stained with DAPI, imaged by confocal microscopy, and counted by masked observers in an image analysis system. Axon counts were performed in optic nerve crosssections by semi-automated image analysis. Both WT and Jnk3 −/− mice had mean elevations of IOP of more than 50% after bead injection. Both groups underwent the expected axial globe elongation due to chronic IOP elevation. The absence of JNK3 in KO retina was demonstrated by Western blots. RGC layer neuron counts showed modest loss in both WT and Jnk3 −/− animals; local differences by retinal eccentricity were detected, in each case indicating greater loss in KO animals than in WT. The baseline number of RGC layer cells in KO animals was 10% higher than in WT, but the number of optic nerve axons was identical in KO and WT controls. A slightly greater loss of RGC in Jnk3 −/− mice compared to controls was detected in experimental mouse glaucoma by RGC layer counting and there was no protective effect shown in axon counts. Counts of RGC layer cells and optic nerve axons indicate that Jnk3 −/− mice have an increased number of amacrine cells compared to WT controls.

The Presence and distribution of elastin in the posterior and retrobulbar regions of the mouse eye was investigated. Mice of two strains (C57/BL6 and DBA/2J) were studied at 2 months and 8-12 months of age. Light, confocal, and transmission electron microscopy were used to identify elastin, using immunohistochemical techniques and ultrastructural evaluation. Elastin was found in the following ocular structures: conjunctiva, muscle tendons, sclera, choroid, and meninges. The elastin in the sclera was most dense in a ring surrounding the peripapillary optic nerve head, with its presence in the inner sclera declining with greater distance from the nerve head. Elastin fibers were oriented in the sclera along what would be expected to be the principal stress directions generated from the intraocular pressure, though actual biomechanical measurements have not yet been made in the mouse sclera. Elastin comprises a portion of the mouse sclera and its distribution in the peripapillary area is similar to that in human eyes.

Proximal row carpectomy (PRC) combined with distal radius hemiarthroplasty is a relatively novel procedure that rivals total wrist arthrodesis and offers a new surgical treatment option for select patients with painful, end-stage wrist disease. We present our early experience with this procedure. A retrospective chart review was conducted for nonrheumatoid patients diagnosed with wrist arthritis and subsequently treated with wrist hemiarthroplasty combined with PRC. The minimum follow-up duration was 12 months. Preoperative and postoperative flexion, extension, and grip strength were recorded. Postoperative radiographic findings were assessed. The Patient-Rated Wrist Evaluation (PRWE) questionnaire was administered to gauge postoperative pain and function. The records of 10 patients were reviewed. The mean age was 64 years and the mean postoperative follow-up duration was 19 months. Postoperative flexion, extension, and grip strength were all found to be less than the preoperative levels. The mean postoperative PRWE score for pain and function were 26 and 23, respectively. The complications were diverse and occurred at a relatively high rate. PRC combined with distal radius hemiarthroplasty is a novel procedure that offers a potential surgical option for the treatment of wrist arthritis in select patients. Our early experience has lead us to modify our technique with regard to the implant material, and at this stage, the surgical technique and the most appropriate implant may require further optimization. The level of evidence for this study is IV (therapeutic).

Partial fasciectomy through the described mini-incision approach provides an additional surgical option for patients who desire a less invasive surgical procedure than traditional fascietomy. Although this procedure is safe and effective at achieving immediate cord release, maintenance of correction for proximal interphalangeal joint contractures remains problematic.

Summary: An intramedullary nail is a common and reliable treatment option for diaphyseal tibial fractures. One such approach for this technique is suprapatellar. This video shows the surgical technique of a tibial nail through a suprapatellar approach in a semi-extended position in a 22-year-old man with a distal third tibial shaft fracture.