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Concept: Femoral nerve


Femoral continuous peripheral nerve blocks (CPNBs) provide effective analgesia after TKA but have been associated with quadriceps weakness and delayed ambulation. A promising alternative is adductor canal CPNB that delivers a primarily sensory blockade; however, the differential effects of these two techniques on functional outcomes after TKA are not well established.

Concepts: Femoral vein, Peripheral nervous system, Femoral nerve, Saphenous nerve, Nerve block, Adductor canal


BACKGROUND: /st>Our aim was to estimate the ED(95) of prilocaine 1% w/v for femoral nerve block. METHODS: /st>This two-stage dose-finding sequential clinical trial followed an adaptive design based on the continual reassessment method (CRM). Adult patients undergoing Vastus medialis muscle biopsy under ultrasound-guided femoral nerve block were recruited. Data from previously published studies and our own previous experience were used to set the dose levels and their guesstimate probabilities of response. RESULTS: /st>Forty patients were recruited in the trial (n=26 in the first stage and n=14 in the second stage). Using the CRM, the estimated response probabilities with 13 and 17 ml prilocaine 1% w/v were 90.4% (95% credibility interval: 68-98%) and 99.1% (95% credibility interval: 89-100%), respectively. CONCLUSION: /st>Our study demonstrates that the dose closest to the ED(95) of prilocaine 1% w/v for ultrasound-guided femoral nerve block is 17 ml. The study also illustrates the value of CRM in dose-finding experiments.

Concepts: Statistics, Muscle, Spacecraft propulsion, Multistage rocket, Femoral nerve, Vastus medialis


Hip fracture is the most common orthopaedic emergency. We investigated the concentration of 30 ml levobupivacaine that provided analgesia to 50% and 95% of patients with a hip fracture when injected around the femoral nerve under ultrasound guidance. We defined analgesia as a ≥ 20-point decrease on a 100-point pain scale with reduced cold sensation in the middle third of the anterior thigh 30 min after the nerve block. We increased the concentration of levobupivacaine if the preceding dose had been ineffective and decreased it if the preceding dose had been effective. Probit regression modelling estimated the effective (95% CI) concentration of 30 ml levobupivacaine in 50% and 95% of patients with a fractured hip to be 0.026 (0.023-0.028)% w/v and 0.036 (0.027-0.047)% w/v, respectively.

Concepts: Osteoporosis, Bone fracture, Hip fracture, Pain, Sartorius muscle, Probit model, Femoral nerve, Anterior compartment of thigh


This report describes a rare case of femoral nerve paresthesia caused by an acetabular paralabral cyst of the hip joint. A 68-year-old woman presented with a 6-month history of right hip pain and paresthesia along the anterior thigh and radiating down to the anterior aspect of the knee. Radiography showed osteoarthritis with a narrowed joint space in the right hip joint. Magnetic resonance imaging showed a cyst with low T1- and high T2-weighted signal intensity arising from a labral tear at the anterior aspect of the acetabulum. The cyst was connected to the joint space and displaced the femoral nerve to the anteromedial side. The lesion was diagnosed as an acetabular paralabral cyst causing femoral neuropathy. Because the main symptom was femoral nerve paresthesia and the patient desired a less invasive procedure, arthroscopic labral repair was performed to stop synovial fluid flow to the paralabral cyst that was causing the femoral nerve paresthesia. After surgery, the cyst and femoral nerve paresthesia disappeared. At the 18-month follow-up, the patient had no recurrence. There have been several reports of neurovascular compression caused by the cyst around the hip joint. To the authors' knowledge, only 3 cases of acetabular paralabral cysts causing sciatica have been reported. The current patient appears to represent a rare case of an acetabular paralabral cyst causing femoral nerve paresthesia. The authors suggest that arthroscopic labral repair for an acetabular paralabral cyst causing neuropathy can be an option for patients who desire a less invasive procedure.

Concepts: Nuclear magnetic resonance, Magnetic resonance imaging, Pelvis, Sartorius muscle, Synovial joint, Joints, Femoral nerve, Anterior compartment of thigh


Total knee arthroplasty (TKA) is a common procedure resulting in significant post-operative pain. Percutaneous cryoneurolysis targeting the infrapatellar branch of the saphenous nerve and anterior femoral cutaneous nerve could relieve post-operative knee pain by temporarily blocking sensory nerve conduction.

Concepts: Nervous system, Sensory system, Knee replacement, Nerve conduction study, Sensory receptor, Femoral nerve, Saphenous nerve, Sensory neuron


Hip and femoral neck fractures are common in elderly patients, who are at an increased risk of complications if their pain is suboptimally managed. This systematic review seeks to determine if regional nerve blocks reduce pain, reduce the need for parenteral opiates, and reduce complications, compared to standard pain management with opiates, acetaminophen, or NSAIDs. Data sources Systematic review of MEDLINE, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials found 401 articles, of which nine were selected for inclusion. Study selection Randomized controlled trials including adult patients with a hip or femoral neck fracture (Population) who had a 3-in-1 femoral nerve block, traditional femoral nerve block, or fascia iliaca compartment block performed preoperatively (Intervention). Comparison must have been made with standard pain management with opiates, acetaminophen, or NSAIDs (Comparison) and outcomes must have included pain score reduction (Outcome). Data synthesis Eight out of nine studies concluded pain scores were improved with the regional nerve block compared to standard pain management. A significant reduction in parenteral opiate use was seen in five out of six studies. No patients suffered life-threatening complications related to the nerve block; however, more minor complications were under-reported. Most of the studies were at a moderate to high risk of bias.

Concepts: Randomized controlled trial, Opioid, Pain, Sartorius muscle, Suffering, Hydrocodone, Opiate, Femoral nerve


to determine the efficacy of the fascia iliaca block in providing analgesia to patients with a proximal femoral fracture in the emergency department.

Concepts: Hip fracture, Hospital, Pain, Pain management, Femoral nerve, Dublin


This study examined the effects of prior upper body exercise on subsequent high-intensity cycling exercise tolerance and associated changes in neuromuscular function and perceptual responses. Eight males performed 3 fixed work-rate (85% peak power) cycling tests: (1) to the limit of tolerance (CYC); (2) to the limit of tolerance after prior high-intensity arm-cranking exercise (ARM-CYC); (3) without prior exercise and for an equal duration as ARM-CYC (ISOTIME). Peripheral fatigue was assessed via changes in potentiated quadriceps twitch force during supramaximal electrical femoral nerve stimulation. Voluntary activation was assessed using twitch interpolation during maximal voluntary contractions. Cycling time during ARM-CYC and ISOTIME (4.33 ± 1.10 min) was 38% shorter than CYC (7.46 ± 2.79 min) (P < 0.01). Twitch force decreased more after CYC (-38 ± 13%) than ARM-CYC (-26 ± 10%) (P < 0.01) and ISOTIME (-24 ± 10%) (P < 0.05). Voluntary activation was 94 ± 5% at rest and decreased after CYC (89 ± 9%, P < 0.01) and ARM-CYC (91 ± 8%, P < 0.05). Rating of perceived exertion for limb discomfort increased more quickly during ARM-CYC (1.83 ± 0.46 AU∙min(-1)) than CYC (1.10 ± 0.38 AU∙min(-1)) and ISOTIME (1.05 ± 0.43 AU∙min(-1)) (P < 0.01), and this was correlated with the reduced cycling time in ARM-CYC (r = -0.72, P = 0.045. In conclusion, cycling exercise tolerance after prior upper body exercise is potentially mediated by central fatigue and intolerable levels of sensory perception rather than a critical peripheral fatigue limit.

Concepts: Muscle, Exercise, Perception, Sense, Mind, Fatigue, Philosophy of perception, Femoral nerve


Effective analgesia after total knee arthroplasty (TKA) improves patient satisfaction, mobility and expedites discharge. This study assessed whether continuous femoral nerve infusion (CFNI) was superior to a single-shot femoral nerve block in primary TKA surgery completed under subarachnoid blockade including morphine.

Concepts: Sartorius muscle, Morphine, Knee replacement, Codeine, Femoral nerve


Femoral neck fractures are a common and painful injury. Femoral nerve blocks, and a variant of this technique termed the ‘3-in-1’ block, are often used in this patient group, but their effect is variable. The fascia iliaca compartment block (FIB) has been proposed as an alternative, but the relative effectiveness of the two techniques in the early stages of care is unknown. We therefore compared the FIB versus the 3-in-1 block in a randomised trial conducted in two UK emergency departments.

Concepts: Myocardial infarction, Hospital, Femoral nerve, Acute assessment unit, Closure, Iliac fascia