Arthroscopic rotator cuff repair (ARCR) can provide excellent clinical results for patients who fail to respond to conservative management of symptomatic rotator cuff tears. ARCR, however, can be ...associated with severe postoperative pain and discomfort that requires adequate analgesia. As ARCR continues to shift toward being performed as an outpatient procedure, it is incumbent on physicians and ambulatory surgical centers to provide appropriate pain relief with minimal side effects to ensure rapid recovery and safe discharge. Although intravenous and oral opioids are the cornerstone of pain management after orthopedic procedures, they are associated with drowsiness, nausea, vomiting, and increased length of hospital stay. As health care reimbursements continue to become more intimately focused on quality, patient satisfaction, and minimizing of complications, the need for adequate pain control with minimal complications will continue to be a principal focus for providers and institutions alike. We present a review of alternative modalities for pain relief after ARCR, including cryotherapy, intralesional anesthesia, nerve blockade, indwelling continuous nerve block catheters, and multimodal anesthesia. In choosing among these modalities, physicians should consider patient- and system-based factors to allow the efficient delivery of analgesia that optimizes recovery and improves patient satisfaction.
Key points
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The excitatory afferents to the striatum from the cortex and thalamus are critical in the expression of basal ganglia function.
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Thalamostriatal afferents are markedly heterogeneous ...and arise in different subnuclei of the intralaminar thalamus.
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We used an optogenetic approach, to isolate and selectively activate thalamostriatal afferents arising in the central lateral or parafascicular thalamic nuclei, and to study the properties of their synapses with principal striatal neurons, the medium‐spiny neurons.
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Thalamostriatal synapses differ in many aspects and our data suggest that inputs from the central lateral nucleus are efficient drivers of medium‐spiny neuron action potential firing, whereas inputs from the parafascicular nucleus are likely to be modulatory.
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These results suggest distinct roles for thalamostriatal inputs from different subnuclei of the thalamus and will help us understand how the striatal circuit operates in health and disease.
To understand the principles of operation of the striatum it is critical to elucidate the properties of the main excitatory inputs from cortex and thalamus, as well as their ability to activate the main neurons of the striatum, the medium spiny neurons (MSNs). As the thalamostriatal projection is heterogeneous, we set out to isolate and study the thalamic afferent inputs to MSNs using small localized injections of adeno‐associated virus carrying fusion genes for channelrhodopsin‐2 and YFP, in either the rostral or caudal regions of the intralaminar thalamic nuclei (i.e. the central lateral or parafascicular nucleus). This enabled optical activation of specific thalamic afferents combined with whole‐cell, patch‐clamp recordings of MSNs and electrical stimulation of cortical afferents, in adult mice. We found that thalamostriatal synapses differ significantly in their peak amplitude responses, short‐term dynamics and expression of ionotropic glutamate receptor subtypes. Our results suggest that central lateral synapses are most efficient in driving MSNs to depolarization, particularly those of the direct pathway, as they exhibit large amplitude responses, short‐term facilitation and predominantly express postsynaptic AMPA receptors. In contrast, parafascicular synapses exhibit small amplitude responses, short‐term depression and predominantly express postsynaptic NMDA receptors, suggesting a modulatory role, e.g. facilitating Ca2+‐dependent processes. Indeed, pairing parafascicular, but not central lateral, presynaptic stimulation with action potentials in MSNs, leads to NMDA receptor‐ and Ca2+‐dependent long‐term depression at these synapses. We conclude that the main excitatory thalamostriatal afferents differ in many of their characteristics and suggest that they each contribute differentially to striatal information processing.
Abstract Tendon disorders after total hip arthroplasty are a major cause of debilitating pain that often goes unrecognized. We performed a literature review to identify the most common tendon ...pathologies after total hip arthroplasty which include iliopsoas tendinitis, trochanteric bursitis, snapping hip syndrome and abductor tendinopathy. These tendinopathies are treatable and mangagement begins with non-operative modalities, however in cases not responsive to conservative management, operative intervention may be necessary. We present a simplified approach highlighting the presentation and management of patients with suspected tendinopathies after total hip arthroplasty. An understanding of the scope of diagnoses can result in higher surgeon and patient satisfaction following total hip arthroplasty.
Purpose To examine clinical outcomes and survivorship in patients aged 60 years or older who underwent hip arthroscopy for management of hip pain. Methods Prospectively collected data for patients 60 ...or older undergoing hip arthroscopy were obtained. All patients were indicated for hip arthroscopy based on standard preoperative examination as well as routine and advanced imaging. Demographic data, diagnosis, and details regarding operative procedures were collected. Baseline preoperative modified Harris Hip Scores (mHHS) and Non-arthritic Hip Scores (NAHS) were compared to mHHS and NAHS at the 2-year follow-up. Survivorship was assessed to determine failure rates, with failure defined as any subsequent ipsilateral revision arthroscopic surgery and/or hip arthroplasty. Results Forty-two patients met inclusion criteria. Mean age (standard deviation) and body mass index were 65.8 years (4.5 years) and 26.1 (4.7), respectively. Baseline mean mHHS and NAHS for all patients improved from 47.8 (±12.5) and 47.3 (±13.6) to 75.6 (±17.6) and 78.3 (±18.6), respectively ( P < .001 for both). Five patients (11.9%) met failure criteria and underwent additional surgery at an average of 14.8 (8-30) months. Three underwent conversion to total hip arthroplasty (7.1%), whereas 2 had revision arthroscopy with cam/pincer resection and labral repair for recurrent symptoms (4.7%). One- and 2-year survival rates were 95.2% and 88.9%, respectively. Conclusions Our results suggest that in patients 60 or older with Tonnis grade 0 or 1 osteoarthritic changes on initial radiographs—treatment with hip arthroscopy can lead to reliable improvement in early outcomes. As use of hip arthroscopy for treatment of mechanical hip pain increases, additional studies with long-term follow-up are needed. Level of Evidence Level IV, therapeutic case series.
Expression of cannabinoid 1 (CB1) and vanilloid 1 (VR1) receptor proteins was studied in adult, cultured rat dorsal root ganglion neurons. Immunostaining of CB1 receptors alone produced labelling in ...57±2% of the cultured dorsal root ganglion neurons (
n=3 cultures). The area of the labelled cells was between 200 and 800
μm
2 with an average of 527±68
μm
2. VR1 immunolabelling revealed immunopositivity in 42±6% of the total population of dorsal root ganglion neurons. Cells showing VR1-like immunopositivity had an area between 200 and 600
μm
2. The mean area of the VR1-like immunopositive neurons was 376±61
μm
2. Double immunostaining with antisera raised against the CB1 and VR1 receptor proteins, showed a high degree of co-expression between CB1 and VR1 receptors. An average of 82±3% of the CB1-like immunopositive cells also showed VR1-like immunoreactivity (
n=3 cultures) while 98±2% of the VR1-like immunolabelled neurons showed CB1 receptor-like immunostaining (
n=3 cultures). Our data suggests that nociceptive primary sensory neurons co-express CB1 and VR1 receptors to a very high degree. We propose that this may provide an anatomical basis for a powerful combination of VR1 mediated excitation and CB1-mediated inhibition of nociceptive responses at central and peripheral terminals of nociceptive primary afferents.
We studied neurogliaform neurons in the stratum lacunosum moleculare of the CA1 hippocampal area. These interneurons have short stellate dendrites and an extensive axonal arbor mainly located in the ...stratum lacunosum moleculare. Single-cell reverse transcription-PCR showed that these neurons were GABAergic and that the majority expressed mRNA for neuropeptide Y. Most neurogliaform neurons tested were immunoreactive for alpha-actinin-2, and many stratum lacunosum moleculare interneurons coexpressed alpha-actinin-2 and neuropeptide Y. Neurogliaform neurons received monosynaptic, DNQX-sensitive excitatory input from the perforant path, and 40 Hz stimulation of this input evoked EPSCs displaying either depression or initial facilitation, followed by depression. Paired recordings performed between neurogliaform neurons showed that 85% of pairs were electrically connected and 70% were also connected via GABAergic synapses. Injection of sine waveforms into neurons during paired recordings resulted in transmission of the waveforms through the electrical synapse. Unitary IPSCs recorded from neurogliaform pairs readily fatigued, had a slow decay, and had a strong depression of the synaptic response at a 5 Hz stimulation frequency that was antagonized by the GABA(B) antagonist (2S)-3-(1S)-1-(3,4-dichlorophenyl)ethylamino-2-hydroxypropyl(phenylmethyl) phosphinic acid (CGP55845). The amplitude of the first IPSC during the 5 Hz stimulation was also increased by CGP55845, suggesting a tonic inhibition of synaptic transmission. A small unitary GABA(B)-mediated IPSC could also be detected, providing the first evidence for such a component between GABAergic interneurons. Electron microscopic localization of the GABA(B1) subunit at neurogliaform synapses revealed the protein in both presynaptic and postsynaptic membranes. Our data disclose a novel interneuronal network well suited for modulating the flow of information between the entorhinal cortex and CA1 hippocampus.
The kinetics of GABAergic synaptic currents can vary by an order of magnitude depending on the cell type. The neurogliaform cell (NGFC) has recently been identified as a key generator of slow GABA(A) ...receptor-mediated volume transmission in the isocortex. However, the mechanisms underlying slow GABA(A) receptor-mediated IPSCs and their use-dependent plasticity remain unknown. Here, we provide experimental and modeling data showing that hippocampal NGFCs generate an unusually prolonged (tens of milliseconds) but low-concentration (micromolar range) GABA transient, which is responsible for the slow response kinetics and which leads to a robust desensitization of postsynaptic GABA(A) receptors. This strongly contributes to the use-dependent synaptic depression elicited by various patterns of NGFC activity including the one detected during theta network oscillations in vivo. Synaptic depression mediated by NGFCs is likely to play an important modulatory role in the feedforward inhibition of CA1 pyramidal cells provided by the entorhinal cortex.
Abstract The purpose of this study is to review a large series of HIV-infected patients who underwent total joint arthroplasty and identify potential risk-factors for infection. Sixty-nine ...HIV-infected arthroplasty cases were analyzed with 138 matched controls. Deep infection rate following total hip or knee arthroplasty was 4.4% (3 of 69) among HIV cases compared to 0.72% (1 of 138) among controls, yielding a non-significant 6.22 times increased odds of infection (95% CI 0.64–61.0, P = 0.11). Kaplan–Meier survival curves for infection free survival and revision free survival revealed non-significantly decreased survival in HIV cases compared to controls ( P = 0.06 and P = 0.09). Our results suggest that the rate of early joint infection following primary total joint arthroplasty in the HIV-infected population is lower than reported in a number of previously published studies.
Feedforward inhibition of neurons is a fundamental component of information flow control in the brain. We studied the roles played by neurogliaform cells (NGFCs) of stratum lacunosum moleculare of ...the hippocampus in providing feedforward inhibition to CA1 pyramidal cells. We recorded from synaptically coupled pairs of anatomically identified NGFCs and CA1 pyramidal cells and found that, strikingly, a single presynaptic action potential evoked a biphasic unitary IPSC (uIPSC), consisting of two distinct components mediated by GABA
A
and GABA
B
receptors. A GABA
B
receptor-mediated unitary response has not previously been observed in hippocampal excitatory neurons. The decay of the GABA
A
receptor-mediated response was slow (time constant = 50 ms), and was tightly regulated by presynaptic GABA
B
receptors. Surprisingly, the GABA
B
receptor ligands baclofen and (2
S
)-3-{(1
S
)-1-(3,4-dichlorophenyl)ethylamino-2-hydroxypropyl}(phenylmethyl)phosphinic acid (CGP55845), while affecting the NGFC-mediated uIPSCs, had no effect on action potential-evoked presynaptic Ca
2+
signals monitored in individual axonal boutons of NGFCs with two-photon microscopy. In contrast, baclofen clearly depressed presynaptic Ca
2+
transients in non-NGF interneurons. Changes in extracellular Ca
2+
concentration that mimicked the effects of baclofen or CGP55845 on uIPSCs significantly altered presynaptic Ca
2+
transients. Electrophysiological data suggest that GABA
B
receptors expressed by NGFCs contribute to the dynamic control of the excitatory input to CA1 pyramidal neurons from the temporoammonic path. The NGFC–CA1 pyramidal cell connection therefore provides a unique and subtle mechanism to shape the integration time domain for signals arriving via a major excitatory input to CA1 pyramidal cells.
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