Seasonal dynamics of wheat aphid complex and predator Coccinella septempunctata in relation to abiotic and biotic factors.

Seasonal dynamics studies on wheat aphid complex, comprising of four major species and its predator Coccinella septempunctata were conducted in context to abiotic and biotic factors. The alate form of aphids appeared on the crop during the 1st week of December. The colony build up of aphid complex started during the 2nd week of January and peak was observed after the 1st week of March. Wheat aphid complex started declining in the last week of March and disappeared by mid April. The abiotic factors like maximum temperature and evaporation were most important for the build up of aphids. The grubs and adults of C. septempunctata appeared on the crop during mid February and their population increased with the increase in aphid population. The grubs and adult population showed a strong positive correlation with aphid complex. The population of predators had significant positive correlation with maximum, minimum, mean temperature, sunshine and vapour pressure. The population of aphids declined after the 2nd week of March due to the rise in temperature, crop maturity and this in turn resulted in the lowering of the predator population. The studies evaluate in detail the abiotic and biotic factors regulating the wheat aphid complex and C. septempunctata populations under wheat agro-ecosystem.

A comparison of the vastus splitting and median parapatellar approaches in total knee arthroplasty.

This prospective randomized study was undertaken to evaluate the vastus splitting approach as an alternative to the median parapatellar approach in primary total knee arthroplasty. Fifty-one knees in 42 patients were randomized preoperatively. Clinical parameters were evaluated preoperatively and at regular postoperative intervals. Electromyography was performed preoperatively and postoperatively to evaluate each approach relative to its effect on the innervation of the quadriceps mechanism. There were no significant preoperative differences. Postoperatively, there were no significant differences regarding strength, range of motion, knee scores, tourniquet time, proprioception, or patellar replacement. There were significantly more lateral releases performed and greater blood loss in the patients in the parapatellar group. The results of all preoperative electromyograms were normal, as were all of the results of postoperative electromyograms in the patients in the parapatellar group. However, the results of nine of 21 (43%) of the electromyograms performed postoperatively on patients who had the vastus splitting approach were abnormal. Significantly fewer lateral releases were performed and there was less blood loss in the patients in the vastus group. However, the postoperative electromyographic results revealed neurologic injuries in the vastus medialis muscle that only were present after the vastus splitting approach. The clinical significance of denervation of the vastus medialis muscle by the vastus approach remains to be determined by longer term clinical and electromyographic studies.

The Frank Stinchfield Award. Inhibition of heterotopic ossification with radiation therapy in an animal model.

An animal model for the study of heterotopic ossification was developed and the effects of perioperative radiation were analyzed. In Phase I, New Zealand White rabbits (n = 18) underwent surgery either with or without muscle injury on each hip to establish the most reliable model in which to study heterotopic ossification. In Phase II, rabbits (n = 36) underwent either 400, 800, or 1200 cGy radiation to one hip 24 hours after bilateral hip surgery to establish a dose response relationship for postoperative radiation therapy. In Phase III, rabbits (n = 24) underwent preoperative radiation therapy (800 cGy) at 4, 16, or 24 hours preoperatively to investigate the mechanism of action and efficacy of preoperative radiation therapy. Monthly radiographs were graded by blinded observers for severity of heterotopic ossification. Mean grade, intraobserver and interobserver variability, and statistical significance were evaluated. In Phase II, 17 of 18 rabbits generated heterotopic ossification in both hips, and the mean grade of heterotopic ossification was always greater on the operative side with intentional muscle injury. Variability in the grading was considered excellent. Phase II revealed that 800 cGy was the minimal effective dose. Contrary to hypothesis, Phase III revealed an increasing grade of heterotopic ossification coinciding with a decreasing preoperative time interval, with the difference in heterotopic ossification grade with 24-hour versus 4-hour preoperative radiation being significant. The rabbit model is reliable and reproducible and closely resembles the human clinical situation after hip surgery. Preoperative and postoperative radiation effectively prevented heterotopic ossification formation. The results support the use of preoperative radiation and establish a need for additional investigation regarding the mechanism of action and timing of preoperative radiation therapy.