Thrombogenetic effect of facet denervation using in disc surgery on spinal radicular arteries: an experimental study.

BACKGROUND: Although it is well known that electric current can be hazardous for living tissues, facet denervation (FD) has been largely used in spine surgery. In spite of the fact that vascular structures are protected during the operation, some neurovascular disorders may develop after surgery. In this study, we investigated if FD can cause lesions of the radicular arteries. METHODS: Seventeen rabbits were included in this study. Three of them were used as control group and the remainder were subjected to L4-5 discectomy. FD was applied via monopolar electrocauterization to only half of the operated animals. One month after the surgery, all animals were sacrificed and the L4-5 spinal radicular arteries examined histopathologically. RESULTS: Vascular wall injury, endothelial necrosis, muscular lesions and thrombus development were seen in the majority of the spinal radicular arteries of the animals subjected to FD. CONCLUSION: Facet denervation via monopolar electrocautery may cause arterial lesions and thrombus development in the radicular arteries and therefore it should not be applied unless obligatory.

Comparisons of analgesic effects of different doses of morphine and morphine plus methylprednisolone after knee surgery.

BACKGROUND: In this double-blind randomized study, the analgesic effects of morphine alone and with methylprednisolone were examined in 72 patients undergoing arthroscopic knee surgery. METHODS: At the end of arthroscopy, patients were allocated randomly to one of four groups to receive intra-articular administrations of saline, morphine 1 mg, morphine 5 mg or morphine 1 mg with methylprednisolone 40 mg. Preoperative and postoperative pain levels at rest and during movement (active flexion of the knee) were measured by a visual analogue scale (VAS). Postoperative analgesic requirements to alleviate pain were evaluated. RESULTS: Pain scores were significantly lower for the patients who received 5 mg morphine and 1 mg morphine with 40 mg methylprednisolone than for those who received saline or 1 mg morphine. This was accompanied by a decrease in the postoperative consumption of analgesics and prolongation of the duration of pain relief. CONCLUSIONS: This study confirms that the analgesic effect of morphine given intra-articularly is dose dependent and that combination of methylprednisolone with morphine has an additive effect on analgesia.

An investigation of the effects of hydroxyapatite coatings on the fixation strength of cortical screws.

Hydroxyapatite (HA) are commonly applied to orthopaedic implants for acceleration of osteointegration and so overcoming the loosening problems such as in cortical screws. Electrophoretic deposition (EPD) of hydroxyapatite was applied for coating of cortical screws in this work. The effects of hydroxyapatite-coated and uncoated cortical screws on insertion and extraction torque were investigated through in vivo experiments. Three groups of screws were undertaken: first group with no coating, second group coated with HA and the third group coated with HA+interlayer, a synthetic calcium silicate compound. Five sheep were operated, and 60 cortical (20 x 3) screws from those of groups were implanted in cortical femurs to observe the effect of HA and interlayer on screws. Results show that as an alternative to plasma spray coating method, the EPD process enables to produce a quick, easy, cheap and uniform adjustable coating layer. Also from biomechanical and SEM examinations, HA coating by EPD method of cortical screws resulted in extremely improved fixation with reduced risk of loosening problem.

Coating analysis of implant materials used in orthopaedic surgery.

Biocompatibility of orthopaedic surgical implants with bone tissue allows adequate osseointegration between the bone and implant. To achieve this, implants are coated with biocompatible materials. The costly plasma spray procedure is routinely used to coat implants but uses high temperatures (over 16,000 degrees C), which affect the surface quality and microstructure of the implant. We analysed the effect of sintering temperature, time and rate on coated and uncoated implants using a dipping method. The effectiveness of synthetic hydrated calcium silicate compound as an interlayer was also investigated, using the dipping method and electrophoretic deposition. Sintering temperature, time and rate all affected the quality of the bond with the coating, but the interlayer bonded effectively with both implant and biocompatible coating. Electrophoretic deposition resulted in imperfect bonding and some irregularity on the substrate surface was seen. This technique may be improved by using coating particles of a smaller size.