The effect of increased distraction frequency on soft tissues during limb lengthening in an animal model.

The purpose of this study was to compare the effect of distraction frequency on soft tissues. Ten rabbits underwent high-frequency, automated distraction at 1,440 increments per day, whereas five rabbits were manually distracted at a low frequency of three increments per day. The tibias were lengthened approximately 20% at a rate of 1.05 mm/day. The results indicate that all animals had decreased range of motion of the ankle; however, the high-frequency group fared better compared with the low-frequency group (p<0.01). In addition, the P1 latency of the somatosensory evoked potentials did not change in the high-frequency group, but was statistically higher for the low-frequency group (p<0.05). There was no significant difference found in the histologic studies of muscle of either group. Thus increasing the distraction frequency resulted in better range of motion of the ankle joint and maintained normal somatosensory evoked potentials.

Pelvic mass secondary to polyethylene and titanium alloy wear debris resulting in recurrent deep vein thrombosis.

External venous compression can be a cause of deep vein thrombosis (DVT). This is an unusual case of acetabular component failure and resultant polyethylene and titanium alloy wear debris that presented as a pelvic mass and resulted in iliac vein compression and subsequent DVT.

Fatal pulmonary embolus after knee arthroscopy.

We report a case of fatal pulmonary embolus after arthroscopy of the knee to heighten awareness of this potentially fatal complication. A literature search was conducted to review the reported complications of knee arthroscopy.

Blunt needle infusion of local anesthetics or narcotic analgesics into operative wounds or joints.

Local anesthetics or narcotic analgesics introduced into surgical wounds have been noted to provide pain relief. These agents are typically infused into the postoperative joint or wound using a standard beveled needle or by pressing the syringe hub against the incision without a needle. We present an alternative method of administering these agents to provide pain relief in the orthopedic patient. A blunt needle is used to infiltrate the postoperative joint or wound with local anesthetics or narcotic analgesics.

Retinoic acid stimulates interstitial collagenase messenger ribonucleic acid in osteosarcoma cells.

The rat osteoblastic osteosarcoma cell line UMR 106-01 secretes interstitial collagenase in response to retinoic acid (RA). The present study demonstrates by Northern blot analysis that RA causes an increase in collagenase messenger RNA (mRNA) at 6 h, which is maximal at 24 h (20.5 times basal) and declines toward basal level by 72 h. This stimulation is dose dependent, with a maximal response at 5 x 10(-7) M RA. Nuclear run-on assays show a greater than 20-fold increase in the rate of collagenase mRNA transcription between 12-24 h after RA treatment. Cycloheximide blocks RA stimulation of collagenase mRNA, demonstrating the need for de novo protein synthesis. RA not only causes an increase in collagenase secretion, but is known to decrease collagen synthesis in UMR 106-01 cells. In this study, the increase in collagenase mRNA is accompanied by a concomitant decrease in the level of alpha 1(I) procollagen mRNA, which is maximal at 24 h (70% decrease), with a return to near-control levels by 72 h. Nuclear run-on assays demonstrated that the decrease in alpha 1 (I) procollagen expression does not have a statistically significant transcriptional component. RA did not statistically decrease the stability of alpha 1 (I) procollagen mRNA (calculated t1/2 = 8.06 +/- 0.30 and 9.01 +/- 0.62 h in the presence and absence of RA, respectively). However, transcription and stability together probably contribute to the major decrease in stable alpha 1 (I) procollagen mRNA observed. Cycloheximide treatment inhibits basal level alpha 1 (I) procollagen mRNA accumulation, demonstrating the need for on-going protein synthesis to maintain basal expression of this gene.