Yun-Rak Choi

Identifying genes related to radiation resistance in oral squamous cell carcinoma cell lines

Radioresistance is one of the main determinants of treatment outcome in oral cancer, but the prediction of radioresistance is difficult. The authors aimed to establish radioresistant oral squamous cell carcinoma (OSCC) cell lines to identify genes with altered expression in response to radioresistance. To induce radioresistant cell lines, the authors treated OSCC cell lines with an accumulated dosage of 60Gy over 30 cycles of radiotherapy. They compared the results from cDNA arrays and proteomics between non-radiated and radioresistant cell lines in order to identify changes in gene expression. Western blot analysis was used to validate the results. The cDNA array revealed 265 commonly up-regulated genes and 268 commonly down-regulated genes in radioresistant cell lines, 30 of which were cancer-related genes. Proteomics identified 51 proteins with commonly altered expression in radioresistant cell lines, 18 of which were cancer-related proteins. Both the cDNA array and proteomics indicated that NM23-H1 and PA2G4 were over-expressed. Western blot analysis showed increased expression of NM23-H1, but not PA2G4, in radioresistant cell lines. The authors concluded that NM23-H1 may be a radioresistance-related gene and over-expression of NM23-H1 could serve as a biomarker to predict radioresistance in OSCC.

A central threadless shaft screw is better than a fully threaded variable pitch screw for unstable scaphoid nonunion: A biomechanical study

INTRODUCTION An interpositional wedge bone graft is a procedure performed to restore carpal height and scaphoid length for displaced scaphoid nonunions with carpal instability. The purpose of this study was to investigate which headless screw design (threadless central shaft screw or fully threaded variable pitch compression screw) is biomechanically preferred when an interpositional bone graft is needed. METHODS A total of 24 cadaveric scaphoid interpositional bone grafts were divided into three groups and fixed with HCS 3.0, Herbert-Whipple or Acutrak mini-screws, and the relative biochemical stability of each was measured. The specimens were tested using an Instron tensile testing machine to calculate stiffness and load to failure. To measure compression forces at different interfragmentary gaps, 30 interpositional polyurethane bone graft models were generated with three pieces of cancellous sawbone block, and two custom-made load-cells were inserted in each gap. The models were then divided into three groups and fixed with the above screw types. The compression forces at different interfragmentary gaps were measured immediately and 30 min after screw fixation. RESULTS The average stiffness and load to failure were similar among the three groups (p>0.05). The average compression force measured at each interfragmentary gap was highest in the HCS 3.0 fixation group, followed by the Herbert-Whipple and Acutrak mini-screw fixation groups both immediately after screw fixation and after 30 min (at which time there were significant decreases in force). The compression forces measured at different interfragmentary gaps were almost identical in the HCS 3.0 and Herbert-Whipple screw fixation groups; however, the force measured at the leading side was significantly lower than that measured at the trailing side in the Acutrak mini-screw fixation group. CONCLUSION The threadless central shaft screw design is biomechanically preferred over the fully threaded variable pitch screw design because it achieves higher and identical compression forces at different interfragmentary gaps with similar stiffness and load to failure.

Topographical anatomy of the radial nerve and its muscular branches related to surface landmarks.

Understanding of the anatomy of the radial nerve and its branches is vital to the treatment of humeral fracture or the restoration of upper extremity function. In this study, we dissected 40 upper extremities from adult cadavers to locate the course of the radial nerve and the origins and insertions of the branches of the radial nerve using surface landmarks. The radial nerve reached and left the radial groove and pierced the lateral intermuscular septum, at the levels of 46.7, 60.5, and 66.8% from the acromion to the transepicondylar line, respectively. Branches to the long head of the triceps brachii originated in the axilla, and branches to the medial and lateral heads originated in the axilla or in the arm. The muscular attachments to the long, medial, and lateral heads were on average 34.0 mm proximal, 16.4 mm distal, and 19.3 mm proximal to the level of inferior end of the deltoid muscle, respectively. The radial nerve innervated 65.0% of the brachialis muscles. Branches to the brachioradialis and those to the extensor carpi radialis longus arose from the radial nerve above the transepicondylar line. Branches to the extensor carpi radialis brevis usually arose from the deep branch of radial nerve (67.5%); however, in some cases, branches to the extensor carpi radialis brevis arose from either the radial nerve (20.0%) or the superficial branch of the radial nerve (12.5%). Using these data, the course of the radial nerve can be estimated by observing the surface of the arm. Clin. Anat. 26:862–869, 2013.

Surgical Results of Delaminated Rotator Cuff Repair Using Suture-Bridge Technique With All-Layers or Bursal Layer–Only Repair

Background: There are no known studies that have investigated the effect on delaminated rotator cuff tears of bursal layer–only repair when full-thickness repair would put the articular layer under tension, compared with all-layers repair when full-thickness repair is feasible. Hypothesis: Better outcomes will be seen in the bursal layer–only repair, as the articular layer would be under tension when repaired onto its footprint during the all-layers repair. Study Design: Cohort study; Level of evidence 3. Methods: This study included 112 patients who underwent arthroscopic rotator cuff repair for posteriorly delaminated tears of either all layers (group A) or the bursal layer alone (group B). If the articular layer was able to be reduced onto its footprint, the patient was assigned to group A; if such reduction was not possible or was only marginally possible under significant tension, the patient was assigned to group B. Pain scored on a visual analog scale (VAS) was assessed, as were subjective shoulder value (SSV), University of California, Los Angeles (UCLA) shoulder score, American Shoulder and Elbow Surgeons (ASES) score, and shoulder active range of motion (ROM). Postoperative magnetic resonance arthrography (MRA) or computed tomographic arthrography (CTA) was undertaken 6 months postoperatively for structural integrity assessment. Results: After 2 years, the VAS pain score (group A, from 6.5 to 1.2; group B, from 6.4 to 1.2), SSV (group A, from 38.3 to 89.4; group B, from 38.0 to 90.1), ASES score (group A, from 36.4 to 90.4; group B, from 38.0 to 90.8), UCLA shoulder score (group A, from 15.3 to 30.7; group B, from 15.0 to 31.3), and ROM improved significantly in both groups compared with preoperative values (P < .001). However, none of these values differed significantly between groups. On follow-up MRA or CTA images, there was no significant difference in the retear rate between group A (28%; 16/57) and group B (24%; 11/45). Conclusion: The all-layers repair did not produce better clinical outcomes or structural integrity than the bursal layer–only repair. The study findings indicate that if repair of the articular layer is possible only under significant tension or is not reparable, rather than all-layers repair by force, bursal-layer repair without incorporating the articular layer may produce comparable clinical outcomes and structural integrity in the delaminated rotator cuff tear.

Ulnar nerve stability-based surgery for cubital tunnel syndrome via a small incision: a comparison with classic anterior nerve transposition

ObjectiveThe purpose of this study was to compare the clinical outcomes of ulnar nerve stability-based surgery via a small incision with those of classic anterior transposition of the ulnar nerve for cubital tunnel syndrome.MethodsFrom March 2008 to December 2013, 107 patients with cubital tunnel syndrome underwent simple decompression or anterior transposition via a small incision, according to an ulnar nerve stability-based decision based on an assessment of intraoperative ulnar nerve stability (group A, n = 51), or anterior transposition via a classic incision (group B, n = 56). Clinical outcome was assessed using grip and pinch strength, two-point discrimination, the mean of the disabilities of arm, shoulder, and hand (DASH) survey, and the modified Bishop scale.ResultsAt the final follow-up, all outcome measures improved significantly in both groups and there were no significant differences between the two groups. However, there were fewer operation-related complications in group A (one revision surgery) than in group B (one superficial infection, two painful scars, and five cases of numbness at the medial elbow).ConclusionsOutcomes after the ulnar nerve stability-based approach and anterior transposition were similar, although more patients experienced operation-related complications after anterior transposition via a classic incision. Making an ulnar nerve stability-based decision to perform either simple decompression or anterior transposition via a small incision seems to be a better strategy for patients with cubital tunnel syndrome.

Relaxin Modulates the Expression of MMPs and TIMPs in Fibroblasts of Patients with Carpal Tunnel Syndrome

Purpose The aim of this study was to investigate the anti-fibrotic effect of relaxin in subsynovial fibroblasts activated by transforming growth factor beta (TGF-β). Materials and Methods To test the anti-fibrotic effect of an adenovirus-relaxin construct (Ad-RLN) on subsynovial fibroblasts in vitro, cells from subsynovial connective tissue of patients with carpal tunnel syndrome were activated with TGF-β1 and exposed to Ad-RLN (as a therapeutic gene) or adenovirus-lacZ construct (as a marker gene) for four hours. Subsynovial fibroblast cultures without adenoviral exposure served as controls. Results We observed induction of gene expressions of collagen I, III and IV, as well as the abatement of alpha-smooth muscle actin (a-SMA) synthesis, Smad2 phosphorylation, and fibronectin at the protein level, in comparison to controls. In addition, protein expressions of matrix metalloproteinase (MMP) I was significantly induced, whereas the protein expressions of tissue inhibitor of metalloproteinases (TIMP) I and IV were reduced due to relaxin expression. Conclusion RLN prevents excessive synthesis of extracellular matrix by reducing the expressions of its components, such as fibronectin, a-SMA, and phosphorylated Smad2, by increasing the expression of MMPs; and by decreasing the expression of TIMPs.

Clavicle hook plate fixation for distal-third clavicle fracture (Neer type II): comparison of clinical and radiologic outcomes between Neer types IIA and IIB

BACKGROUND The purpose of this study was to investigate clinical and radiologic outcomes of clavicle hook plate fixation for distal-third clavicle fracture (Neer type II) and to compare the clinical and radiologic outcomes and complications between Neer type IIA and type IIB. METHODS We retrospectively reviewed 35 patients who underwent open reduction and internal fixation with AO hook locking compression plate (LCP) for distal clavicle fracture, including 13 patients with Neer type IIA and 22 patients with type IIB. Visual analog scale pain score, shoulder scores (subjective shoulder value, University of California-Los Angeles shoulder score, American Shoulder and Elbow Surgeons score), and active range of motion were evaluated to determine clinical outcome. Coracoclavicular distance was measured, and that of the injured side at last follow-up was compared with that of the uninjured side to evaluate radiologic outcomes. RESULTS AO hook LCP fixation for distal-third clavicle fracture (Neer type II) produced satisfactory radiologic outcomes, including high union rates (100%) and coracoclavicular distance maintenance, as well as satisfactory clinical outcomes, including visual analog scale score for pain, shoulder scores (subjective shoulder value, University of California-Los Angeles shoulder score, American Shoulder and Elbow Surgeons score), and active range of motion. There were no significant differences between Neer type IIA and type IIB. With regard to complications, 22.9% of patients experienced shoulder stiffness and 17.1% had subacromial erosion; however, there were no significant differences between the 2 groups. CONCLUSION The AO hook LCP is a suitable choice for Neer type IIA and type IIB distal-third clavicle fracture fixation.

Arthroscopic Repair of Anterosuperior Massive Rotator Cuff Tears: Does Repair Integrity Affect Outcomes?:

Background: The purpose of this study was to investigate clinical outcomes and structural integrity after arthroscopic repair of anterosuperior massive rotator cuff tears (RCTs) and to compare clinical outcomes between healed and retear groups. Hypothesis: The authors hypothesized that although both groups would exhibit improved clinical outcomes compared with their preoperative status, the healed group would have better clinical outcomes than the retear group, and in the retear group, the subscapularis retear subgroup would have inferior outcomes compared with the intact subscapularis repair subgroup. Study Design: Case-control study; Level of evidence, 3. Methods: This study included 73 of 90 eligible patients who underwent arthroscopic repair of an anterosuperior massive RCT. Functional outcomes after 2-year follow-up were assessed using the visual analog scale (VAS) pain score, subjective shoulder value (SSV), American Shoulder and Elbow Surgeons (ASES) score, University of California, Los Angeles (UCLA) shoulder score, and active range of motion. Patients were assigned to the healed group (group H, n = 34) or retear group (group R, n = 39) based on magnetic resonance arthrography results at 6 months postoperatively. Group R was composed of subgroup R1 (subscapularis retear) and subgroup R2 (intact subscapularis repair). Results: Retearing occurred in 53% of patients. At 2-year follow-up, group H exhibited better outcomes for all functional scores versus group R, respectively (P < .001): VAS pain score (1.0 vs 2.1), SSV (90.2 vs 77.4), ASES score (90.8 vs 76.6), and UCLA shoulder score (31.0 vs 24.9). Within both groups, all scores improved significantly compared with preoperative values (P < .001). At follow-up, group H had significantly better forward flexion (P = .018) and internal rotation (P = .002) than group R; within both groups, active range of motion improved in all planes compared with the preoperative condition (P < .001). Subgroup R1 exhibited inferior outcomes versus subgroup R2, respectively: VAS pain score (2.6 vs 1.5; P = .012), ASES score (70.9 vs 83.6; P = .013), SSV (70.9 vs 85.4; P = .005), and UCLA shoulder score (22.0 vs 28.5; P = .001). Conclusion: After arthroscopic repair of anterosuperior massive RCTs, 53% of patients exhibited retearing. The healed group had better functional outcomes than the retear group. The subscapularis retear subgroup exhibited significantly inferior outcomes compared with the intact subscapularis repair subgroup.

Isolated Subscapularis Repair in Irreparable Posterosuperior Massive Rotator Cuff Tears Involving the Subscapularis Tendon

Background: No previous study has examined whether isolated subscapularis tendon repair in irreparable posterosuperior massive rotator tears involving the subscapularis tendon in relatively young patients without arthritis can yield satisfactory outcomes. Hypothesis: We hypothesized that this procedure would produce favorable outcomes in patients who might otherwise be candidates for reverse arthroplasty. Study Design: Case series; Level of evidence, 4. Methods: This retrospective study included 24 patients in their 50s and 60s, without shoulder arthritis, who underwent arthroscopic isolated subscapularis repair for an irreparable massive rotator cuff tear involving the subscapularis tendon. Preoperative and postoperative visual analog scale (VAS) pain scores, subjective shoulder values (SSVs), University of California at Los Angeles (UCLA) shoulder scores, American Shoulder and Elbow Surgeons (ASES) scores, subscapularis strength (modified bell-press test; maximum of 5), and shoulder active range of motion (ROM) were assessed. Postoperative magnetic resonance arthrography (MRA) was performed 6 months postoperatively to assess structural integrity of the repaired subscapularis. Results: At a mean 34.8 months (range, 24-49 months) of follow-up, VAS pain scores (improved from 7.1 to 2.5), SSVs (33.3 to 75.2), ASES scores (35.9 to 76.0), UCLA shoulder scores (11.6 to 24.8), subscapularis strength, and ROM were significantly improved compared with preoperative measurements (P < .001). Subscapularis muscle strength improved from 3.7 to 4.2 (P < .001). For active ROM, forward flexion and internal rotation improved significantly (P < .001); however, external rotation exhibited no significant improvement. Follow-up MRA was performed in 22 patients (92%) and showed retear of the repaired subscapularis in 6 (27% of the 22). Conclusion: Isolated repair of the subscapularis tendon in irreparable massive rotator cuff tears involving the subscapularis tendon yielded satisfactory short-term outcomes and structural integrity in patients in their 50s and 60s without arthritis. If patients with irreparable massive rotator cuff tears involving the subscapularis tendon are relatively young or have minimal concomitant arthritis, this repair can be worthwhile.

Clinical outcomes of minimally invasive open reduction and internal fixation by screw and washer for displaced greater tuberosity fracture of the humerus

BACKGROUND The purpose of this study was to investigate clinical and radiologic outcomes of open reduction and internal fixation with a screw and washer for a displaced greater tuberosity fracture of the proximal humerus through a small incision. METHODS We retrospectively reviewed 29 patients who underwent open reduction and internal fixation with a screw and washer for a greater tuberosity fracture of the proximal humerus. After surgery, the patients were immobilized in a brace for 4 weeks. To determine clinical outcomes, we evaluated a visual analog scale pain score; the Subjective Shoulder Value; the University of California, Los Angeles shoulder score; the American Shoulder and Elbow Surgeons score; and active range of motion. RESULTS All patients achieved bone union within 3 months after surgery. At the 2-year follow-up, the mean visual analog scale pain score was 1.1 ± 1.1; Subjective Shoulder Value, 93.4 ± 5.3; University of California, Los Angeles shoulder score, 31.2 ± 2.7; and American Shoulder and Elbow Surgeons score, 92.6 ± 6.7. Mean active forward flexion, external rotation, and internal rotation were 144° ± 16°, 33° ± 11°, and 13.3 ± 1.7, respectively. Postoperatively, 9 patients (31%) had stiffness and pain refractory to conservative treatment and underwent arthroscopic release. CONCLUSION Although minimal open reduction and screw and washer fixation resulted in bone union in all cases, the incidence of postoperative stiffness was relatively high in patients with displaced greater tuberosity fractures because of prolonged immobilization after surgery.