The Knee
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We present the first case of late spontaneous dislocation of a high flexion polyethylene insert after Genesis II total knee arthroplasty. Dislocation of the fixed insert occurred at 14 months post surgery while walking down a steep aircraft staircase. ⋯ The clinical presentation, possible causes and management are discussed. A surgical error, failure to remove a posterior femoral osteophyte, seems the most probable cause for the late insert dislocation in our case.
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A "hot patella" is a bone scan finding of increased tracer uptake in the patella, greater than the ipsilateral distal femur or the proximal tibia. Increased patellar uptake on the bone scans is a relatively frequent finding; this is often not commented upon. The aim of our study was to define the incidence of a "hot patella" on bone scans following total knee replacements with ongoing symptoms unrelated to sepsis. ⋯ The patients with "hot patella" who underwent secondary patellar resurfacing had symptomatic relief of symptoms. Our study has shown that the finding of a "hot patella" on a bone scan in patients with anterior knee pain following total knee replacement suggests a problem related to the patellofemoral joint. This study would appear to indicate that a "hot patella" in a patient with clinically defined anterior knee pain is likely to benefit from secondary patellar resurfacing.
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Randomized Controlled Trial
Efficacy of intra-articular cocktail analgesic injection in total knee arthroplasty - a randomized controlled trial.
In a randomized, double-blind, placebo, parallel and controlled study, 80 patients with osteoarthritis who underwent unilateral TKA were randomly assigned to two groups: Trial Group, where patients received intra-articular intraoperative injection containing morphine, bupivacaine and betamethasone, and Control Group, where patients received normal saline as control. All patients received patient-controlled analgesia (PCA) for 48 h postoperatively. We found that intra-articular cocktail analgesic injection significantly reduced the morphine consumption during the 0-36 h postoperative period and the total morphine consumption. ⋯ There were no significant differences in postoperative wound healing, infection, blood pressure, heart rate, rash, respiratory depression, urine retention and DVT between the two groups. The occurrence of nausea and vomiting in Trial Group was lower than that of Control Group. This study revealed that intra-articular cocktail analgesic injection reduced the need for morphine and offered a better pain control, without apparent risks following TKA.
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Femoral nerve block (FNB) is a well documented option for post-operative analgesia following major knee surgery. However, motor blockade may be prolonged preventing early mobilisation thereby increasing the length of stay. ⋯ The literature, which is largely in anaesthetic journals, reflects the high quality of analgesia of FNB but makes little or no mention of the delays or dangers in early mobilization. We believe that the potential risks to orthopaedic patients are underestimated.
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We measured the location of the popliteal artery (PA) in extension and 90 degree of knee flexion by magnetic resonance images (MRI) to provide practical information to avoid PA injury. The MRIs of 30 knees of Korean male subject whose mean age was 20.7 were acquired in knee extension and 90 degree flexion. The distance from the posterior aspect of knee joint to the PA was measured at three levels on the axial images and one sagittal image. ⋯ The PA was located around 3 mm lateral to the PCL, and within 5 mm in extension and 10 mm in 90 degree flexion of the knee behind knee joint. It moves farther posteriorly in 90 degree flexion than in extension of the knee. The conventional wisdom of flexing the knee to prevent the PA injury was supported by this study.