Activity-based therapies are routinely integrated in spinal cord injury (SCI) rehabilitation programs because they result in a reduction of hyperreflexia and spasticity. However, the mechanisms by which exercise regulates activity in spinal pathways to reduce spasticity and improve functional recovery are poorly understood. Persisting alterations in the action of GABA on postsynaptic targets is a signature of CNS injuries, including SCI. The action of GABA depends on the intracellular chloride concentration, which is determined largely by the expression of two cation-chloride cotransporters (CCCs), KCC2 and NKCC1, which serve as chloride exporters and importers, respectively. We hypothesized that the reduction in hyperreflexia with exercise after SCI relies on a return to chloride homeostasis. Sprague Dawley rats received a spinal cord transection at T12 and were assigned to SCI-7d, SCI-14d, SCI-14dϩexercise, SCI-28d, SCI28dϩexercise, or SCI-56d groups. During a terminal experiment, H-reflexes were recorded from interosseus muscles after stimulation of the tibial nerve and the low-frequency-dependent depression (FDD) was assessed. We provide evidence that exercise returns spinal excitability and levels of KCC2 and NKCC1 toward normal levels in the lumbar spinal cord. Acutely altering chloride extrusion using the KCC2 blocker DIOA masked the effect of exercise on FDD, whereas blocking NKCC1 with bumetanide returned FDD toward intact levels after SCI. Our results indicate that exercise contributes to reflex recovery and restoration of endogenous inhibition through a return to chloride homeostasis after SCI. This lends support for CCCs as part of a pathway that could be manipulated to improve functional recovery when combined with rehabilitation programs.

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Treatment of patella fractures is fraught with complications and historically poor functional outcomes. A fixation method that allows for early mobilization and decreases symptomatic hardware rates will improve knee range of motion, postoperative functional status, and reoperation rates. The purpose of this study was to evaluate the functional outcomes after locked plate osteosynthesis of patella fractures at a Level 1 trauma center. A retrospective case series was conducted of patients who underwent open reduction internal fixation (ORIF) of a patella fracture using a locked mesh plating technique coupled with neutralization of forces on the distal pole of the patella. Twelve patients were evaluated at a mean follow-up of 19 months (range, 6-30) with physical exam, functional outcomes, and radiographs. There were 9 women and 3 men with an average age of 66.1 years (range, 53-75). Radiographic bony union was achieved in all patients by 3-month follow-up. Visual Analog Pain Score averaged 1.7 (median, 1.0; range, 0-8), the mean Knee Outcome Score - Activities of Daily Living Scale was 83.9 (median, 92.1; range, 45.7-100.0), the mean Short Form Musculoskeletal Function Assessment (SMFA) Function Index was 9.9 (median, 3.7; range, 0.7-41.2), and the mean SMFA Bother Index was 11.1 (median, 3.1; range, 0-62.5). The SF-36 Physical Component Score mean was 48.4 ± 8.5 and the SF-36 Mental Component Score mean was 54.1 ± 9.6. No complications developed and there were no reoperations for nonunion, infection, or symptomatic hardware. This study demonstrates that locked plate osteosynthesis for operative patella fractures can reliably achieve bony union with potentially superior functional outcomes as compared with traditional methods. Further studies are needed to evaluate plate fixation for patella fractures, but early results are promising.