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Articles by C. J Park
Total Records ( 3 ) for C. J Park
  W. Y Lee , C. J Park , T. J Shin , K. W Yum , T. G Yoon , K. S Seo and H. J. Kim
  Background

The potential risks of neurotoxicity due to local anaesthetics after regional anaesthesia have been suggested recently. To evaluate the neurotoxicity of commonly used local anaesthetics, primary cultured rat cortical astrocytes were treated with lidocaine, ropivacaine, bupivacaine, levobupivacaine, and tetracaine.

Methods

Cell death after local anaesthetic treatment was evaluated with a lactate dehydrogenase (LDH) assay. To examine the mechanisms of cell death, reactive oxygen species (ROS) measurement and western blots of poly-ADP ribose polymerase (PARP), procaspase-3, and mitogen-activated protein kinases family members were performed.

Results

Of the local anaesthetics, which were applied at <1 mM for 18 h, only tetracaine significantly increased LDH leakage (P<0.05) and cell death in a dose- and time-dependent manner. Hoechst 33258–propidium iodide staining and western blots with PARP and procaspase-3 antibodies suggested that tetracaine induced apoptosis. ROS levels increased 2-fold at 30 min after tetracaine treatment compared with the control and then decreased. The antioxidants, N-acetylcysteine and trolox, markedly inhibited tetracaine-induced apoptosis.

Conclusions

Tetracaine induced apoptosis through ROS generation. Further studies focusing on the neurotoxicity of tetracaine are needed.

  M. C Park , J. M Pirolo , C. J Park , J. E Tibone , M. H McGarry and T. Q. Lee
  Background

An abduction pillow and abduction and rotation exercises are commonly used after rotator cuff repair. The effect of glenohumeral abduction and rotation on footprint contact has not been elucidated.

Hypothesis

Abduction will decrease tendon-to-bone contact for all repairs. A modified double-row repair will maintain footprint contact more effectively at each position of humeral abduction and rotation than double- or single-row repairs.

Study Design

Controlled laboratory study.

Methods

In 6 fresh-frozen human shoulders, a modified double-row supraspinatus tendon repair was performed; a suture limb from each of 2 medial anchors was bridged over the tendon and fixed laterally. Double- and single-row repairs were performed sequentially; a total of 3 repairs were tested. For all repairs, a Tekscan pressure sensor was fixed at the tendon-footprint interface. The tendon was loaded with 30 N. The shoulders were tested at 0°, 30°, and 60° of abduction with 0° of rotation. For both dual-row repairs, 5 rotation positions were tested.

Results

The greatest contact areas at neutral rotation were achieved at 0° of abduction for the modified double-row, double-row, and single-row repairs (151.3 ± 10.7 mm2, 80.7 ± 30.0 mm2, and 61.3 ± 26.1 mm2, respectively), with values decreasing as abduction increased. Each repair was significantly different from one another at each abduction angle (P < .05), except between single- and double-row repairs at 0° of abduction. Mean interface pressure exerted over the footprint was greater for the modified double-row technique than for the other techniques at each abduction angle (P < .05). With respect to rotation, the modified double-row repair had significantly more footprint contact than did the double-row repair at each position tested (P < .05).

Conclusion

For a given repair, increasing abduction at neutral rotation reduced footprint contact. Internal rotation to 60° provided among the highest contact measurements. The modified double-row technique provided the most contact.

Clinical Relevance

Results are consistent with the practice of immobilizing the shoulder with 30° or less of abduction and up to 60° of internal rotation to optimize footprint contact. A dual-row repair may maximize contact when initiating rehabilitation that involves abduction and rotation.

  M. C Park , B. J Jun , C. J Park , J. H Oh and T. Q. Lee
  Background

A transtendon interimplant mattress repair along the medial row for partial-thickness rotator cuff repairs has been described with clinical success. However, the biomechanical characteristics for such a repair have not been elucidated.

Hypothesis

A knotless interimplant mattress repair may show improved or equivalent load and strain characteristics, compared with a repair using isolated mattress repairs over each of 2 anchors.

Study Design

Controlled laboratory study.

Methods

Seven matched pairs of human cadaveric shoulders were dissected. Articular-sided tears were created involving 50% of the supraspinatus footprint. In 7 shoulders, repairs were performed with mattress configurations isolated over each of 2 anchor sites (control group). In 7 contralateral shoulders, a knotless interimplant mattress suture configuration was employed creating bridging sutures between implants. For all specimens, a materials-testing machine was used to cyclically load each repair from 10 to 180 N for 30 cycles; each repair was then loaded to failure. A deformation rate of 1 mm per second was employed for all tests. A video-digitizing system was employed to quantitatively measure the gap formation and strain on the footprint area of the repair. For detecting gap formation, 7 matched pairs were necessary for achieving a power of at least 90%.

Results

During cyclic loading, gap formation at the anterior tendon was significantly lower in the control group (P < .05) but did not exceed 0.5 mm. There were no significant differences for linear stiffness, hysteresis, and strain between the 2 constructs. During tensile load-to-failure testing, there were no significant differences at yield load between the control and knotless techniques (293.90 ± 132.72 N and 320.38 ± 237.01 N, respectively; P > .05). There were no differences for stiffness, ultimate load, and energy absorbed to failure between the 2 repairs (P > .05). Gap formation in 3 regions was not significantly different between groups at yield and ultimate loads (P > .05). The anterior regions of the repair were the first to fail in all constructs.

Conclusion

A transtendon interimplant mattress rotator cuff repair for partial articular-sided tendon tears involving 50% of the footprint has biomechanical characteristics similar to those of a repair employing 2 isolated mattress configurations. An interim-plant mattress repair can protect tendon strain; it also exhibits yield loads that exceed those typically experienced in the early postoperative period.

Clinical Relevance

A medial-row interimplant mattress repair configuration that is knotless may facilitate repair without compromising biomechanical characteristics.

 
 
 
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