Patellar

An interneuron together with a sensory afferent and motor efferent form a polysynaptic reflex (Figure 2.2) this comprises the initial stage of information input (sensory afferent), the processing/computing an appropriate response (interneurons) and the execution of a behavioural response (motor efferent). The simplest reflexes in the nervous system are monosynaptic reflexes, such as the familiar tendon (knee) jerk, these do not involve an interneuron. The sensory afferent activated by the mechano-receptor (the tap of the patellar hammer) forms a synapse with the motor efferent in the spinal cord, which then causes the skeletal muscle to contract and the crossed leg to jerk forward. With a synaptic delay of 1 millisecond (ms), the time between input and output increases with the number of synapses introduced into the circuit. As an... 

Physical examinations of monkeys are usually conducted no more than once a week and generally consist of the measurement of rectal temperature, observation of general demeanor, palpation of the head, thorax, and abdomen, examination of eyes, ears, and bodily orifices, as well as testing of the pupillary and patellar reflexes. 

Discontinue as soon as the desired effect is obtained. Repeat doses are dependent on the continuing presence of the patellar reflex and adequate respiratory function. Acute nephritis in chiidren 20 to 40 mg/kg IM as needed to control seizures. Dilute the 50% concentration to a 20% solution and give 0.1 to 0.2 mL/kg. 

After the initial IV dose, some clinicians administer 1 to 2 g/hr by constant IV infusion. Subsequent IM doses of 4 to 5 g magnesium sulfate may be injected into alternate buttocks every 4 hours, depending on the presence of the patellar reflex, adequate respiratory function, and absence of signs of magnesium toxicity. Continue therapy until paroxysms cease. 

Adults. 3 g PO q6h x 4 PRN Supl 1-2 g IM or IV repeat PRN Preeclampsia/pre-mature labor 4 g load then g/h IV inf Cardiac arrest 1-2 g IV push (2-4 mL 50% soln) in 10 mL DjW AMI Load 1-2 g in 50-100 mL D5W, over 5-60 min IV then 0.5-1.0 g/h IV up to 24 h (ECC 2005) Feds. 25-50 mg/kg/dose IM or IV q4-6h for 3-4 doses repeat PRN dose w/ low urine output or renal insuff Caution [B, +] Contra Heart block, renal failure Disp Inj 10, 20, 40, 80, 125, 500 mg/mL bulk powder SE CNS depression, D, flushing, heart block Interactions T CNS depression W/ antidepressants, antipsychotics, anxiolytics, barbiturates, hypnotics, narcotics EtOH T neuromuscular blockade Wf aminoglycosides, atracurium, gallamine, pancuronium, tubocurarine, vecuronium EMS Check for absent patellar reflexes this may indicate tox may cause hypokalemia (flattened T waves) and hypocalcemia OD May cause hypotension, resp arrest, T PR, QRS, and QT interval, AV block, and cardiac arrest calcium salts can be given to reverse resp depression... 

A 28 year-old woman with Kearns-Sayre Syndrome, previously exposed multiple times to lidocaine, underwent planned tooth extraction after injection of articaine 1.5 ml (60 mg) with adrenaline (0.009 mg) (168). Within 5 minutes she complained of a feeling of heat, fatigue, weakness, and a desire to sleep. She was unable to walk or stand and had frequent urination. At 20 hours after the injection she had diffuse weakness, reduced tendon and absent patellar reflexes, and sub-clonic Achilles tendon reflexes. She recovered fully 48 hours after the injection. 

In mature tendon, collagen fibril bundles (fibers) have diameters between 1 and 300 mm and fibrils have diameters from 20 to over 280 nm (Figure 3.28). The presence of a crimp pattern in the collagen fibers has been established for rat tail tendon as well as for patellar tendon and anterior cruciate ligament the specific geometry of the pattern, however, differs from tissue to tissue. It is not clear that the crimp morphology of tendon is actually present in tendons that are under normal resting muscular forces. 

Skeleton Renal phosphate diabetes associated with hypercalciuria may lead to osteomalacia or osteoporosis. Likewise, inflammatory or degenerative arthrosis is thought to be a late manifestation of Wilson s disease. (354) Often, these developments are combined with intra-articular calcium deposits and chondromalacia, in particular patellar chondromalacia. Bone fractures are frequently observed even with minor traumas. Calcification may occur in articular cartilage, capsule and tendinous insertions, and deposits of calcium pyrophosphate dihydrate can appear in the intervertebral disks. 

Saint F, Gueguen G, Biserte J, Fontaine C, Mazeman E. Rupture du ligament patellaire un mois apres traitement par fluoroquinolone. [Rupture of the patellar ligament one month after treatment with fluoroquinolone.] Rev Chir Orthop Reparatrice Appar Mot 2000 86(5) 495-7. 

Van Hoogmoed LM, Agnew DW, Whitcomb M, et al. Ultrasonographic and histologic evaluation of medial and middle patellar ligaments in exercised horses following injection with ethanola-mine oleate and 2% iodine in almond oil. Am ] Vet Res 2002 63(5) 738-743. 

Systemic Monitor renal function, magnesium levels, EKG for cardiac function. Test patellar reflex or knee jerk reflexes before giving repeat parenteral doses (used as indication of CNS depression suppressed reflex may be sign of impending respiratory arrest). Patellar reflex must be present, respiratory rate greater than 16/min before each parenteral dose. Provide seizure precautions. 

The usual initial complaint is cramping muscle pain in the lower limbs, followed by distal numbness and paresthesia. Progressive weakness then occurs, together with depression of patellar and Achilles reflexes. When severe,... 

The prosthesis for total knee joint replacement consists of femoral, tibial, and patellar components. Compared to the hip joint, the knee joint has a more complicated geometry and movement biomechanics, and it is not intrinsically stable. In a normal knee, the center of movement is controlled by the geometry of the ligaments. As the knee moves, the ligaments rotate on their bony attachments and the center of movement also moves. The eccentric movement of the knee helps distribute the load throughout the entire joint surface [Burstein and Wright, 1993]. 

Total knee replacements can be implanted with or without cement, the latter relying on porous coating for fixation. The femoral components are typically made of CoCr alloy and the monolithic tibial components are made of UHMWPE. In modular components, the tibial polyethylene component assembles onto a titanium alloy tibial tray. The patellar component is made of UHMWPE, and a titanium ahoy back is added to components designed for uncemented use. The relatively small size of the pateUar component compared to the forces that travel through the extensor mechanism, and the small area of bone available for anchorage of the prosthesis, make the pateUa vulnerable. 

The patellofemoral contact area is smaller than the tibiofemoral contact area (Table 49.10). As the knee joint moves from extension to flexion, a band of contact moves upward over the patellar surface (Figure 49.10). As knee flexion increases, not only does the contact area move superiorly, but it also becomes larger. At 90° of knee flexion, the contact area has reached the upper level of the patella. As the knee continues to flex, the contact area is divided into separate medial and lateral zones. 

F1GURE49.8 Medial (ym) andlateral (/n) patellar facet angles. (FromAhmedA.M.,BurkeD.L., andHyderA. 1987. 

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