Ji-Hoon Ok

Seoul National University Bundang Hospital, Sŏul, Seoul, South Korea

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Publications (11)24.15 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND:Even though apoptosis is known to be closely associated with rotator cuff tears, the differences in apoptosis according to the location within the torn supraspinatus tendon are still unknown. PURPOSE:To elucidate where apoptosis begins within the supraspinatus tendon. STUDY DESIGN:Controlled laboratory study. METHODS:Tendon tissues were collected from 14 patients undergoing arthroscopic rotator cuff repair surgery and 7 patients undergoing surgery for proximal humeral fracture who served as controls. In the patients with rotator cuff tears, the samples were harvested at 3 sites: the most lateral torn margin, 1 cm medial from the torn margin, and at the posterior torn corner. Caspase 3/7, 8, and 9 and cytochrome c activities were measured to determine the intracellular apoptosis pathway. Apoptotic cells were determined by in situ TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) staining, and immunohistochemistry was performed. RESULTS:The apoptotic activities of tendons from the experimental subjects were significantly higher than those of the controls. There were, however, no significant differences between the 3 sample sites. Immunohistochemistry also revealed strong expression of increased caspase 3/7, 8, and 9 and cytochrome c but no significant difference between them. CONCLUSION:This study shows that the intracellular apoptotic pathway is not only through the cell membrane receptor but also via intracellular mitochondria cascade. CLINICAL RELEVANCE:Because apoptosis occurs regardless of the location within the rotator cuff, debridement of the torn margin to obtain a healthy tendon may not be needed. Further study should focus on not only the technique of tying the torn tendon back to the bone but also biological augmentation to reverse or prevent further apoptosis within rotator cuff tendon.
    The American journal of sports medicine 06/2013; · 3.61 Impact Factor
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    ABSTRACT: BACKGROUND: We evaluated the short-term clinical outcomes and compared the component's sizes of reverse total shoulder arthroplasty (RTSA) in Korean Population. MATERIALS AND METHODS: We performed an RTSA on 42 patients between December 2007 to February 2010. The mean age at surgery was 72.5 ± 5.6 (10 men, 32 women) and average follow-up period was 24 months. Twenty-two cuff tears arthropathy, 15 irreparable massive rotator cuff tears with pseudoparalysis, 5 proximal humeral fractures, and 2 infection cases were included. We evaluated clinical outcomes and also the intra- and postoperative complications to determine if any of the complications were unique to the use of a RTSA in a Korean population. In the anatomic study, 92 uninjured shoulders of 92 patients were used for measuring the inferior glenoid size, and we compared the component's sizes of RTSA with those of the normal population. RESULTS: The ASES (American Shoulder and Elbow), UCLA, and KS (Knee Society) scores significantly improved from preoperative 35 (0-63), 12 (5-27), and 39 (3-81) to postoperative 68 (37-95), 24 (16-35), and 68 (34-88), respectively (P < .05). Postoperative complications were seen in 20% and scapular notching 35%. Three patients required further surgery for shoulder dislocation, periprosthetic fracture, and stem loosening. In the anatomic study, mean radius of the inferior glenoid was 17.1 ± 2.1 mm in male and 15.4 ± 1.6 mm in female. CONCLUSION: The short-term clinical results of an RTSA in Korean population are excellent despite high complication rate. However, the size of the glenoid is sometimes smaller than the baseplate (29 mm diameter) in female patients. More adequate size of the glenoid component should be considered.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 02/2013; · 1.93 Impact Factor
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    ABSTRACT: PURPOSE: This study examined the early effect of a subacromial steroid injection on injured rotator cuff tendon. METHODS: Forty rats were allocated into two groups: a steroid injection (group 1) and no injection as control (group 2). A full-thickness defect was made at the unilateral infraspinatus tendon in both groups. A single dose of methylprednisolone was injected in steroid group. The tendon was harvested at 1, 3, 7, 14, and 42 days after surgery; gene expression and immunohistochemical study were performed for type-I/III collagen, tumour necrosis factor (TNF)-α, and extracellular matrix molecules. RESULTS: The type-III to type-I collagen ratio was at 7 days higher in the steroid group than that in the control group and decreased to the control level at 14 days and was maintained until 42 days. The general expression of the MMPs and TIMPs between two groups showed similar pattern regardless of the steroid injection. The gene expression of aggrecan and fibronectin in the steroid group was significantly higher than that in the control group (p < 0.05) at 3 days after surgery. They decreased to the equal level with control group at 7 days after surgery. Both groups showed no significant difference between aggrecan and fibronectin until 42 days after surgery (n.s.). CONCLUSIONS: A subacromial steroid injection may alter the collagen composition and extracellular matrix and interfere with the healing process in an acute tear of rat infraspinatus tendon at the early phase after the injection. However, these alterations seem to become normalized after the early inflammatory healing phase.
    Knee Surgery Sports Traumatology Arthroscopy 01/2013; · 2.68 Impact Factor
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    ABSTRACT: BACKGROUND: This study examined whether a mesenchymal stem cells (MSCs)-seeded 3-dimensional construct into a tendon defect would promote cellular differentiation and matrix healing. MATERIALS AND METHODS: Bone marrow was harvested from the iliac crests of 2 male New Zealand White rabbits. The MSCs were cultured, and an open-cell polylactic acid (OPLA) scaffold was encapsulated with these cells. The injury model was a 5-mm × 5-mm-sized full-thickness window defect in the central part of each rotator cuff tendon. The defects on the right side were grafted with the autologous MSCs-seeded OPLA scaffold implant and a biodegradable suture. The same procedure was done on the left side, except a cell-free OPLA scaffold was used. Three rabbits were used as controls, without treatment of the tendon defect. Samples were harvested at 2, 4, and 6 weeks for analysis, which included evaluation of gross morphology, fluorescent analysis, histologic assessment, and immunohistochemistry studies. RESULTS: The expression of immunohistochemical stainings for collagen I was higher in the scaffold with MSCs than in the scaffold without MSCs. The expression of collagen II, however, was not different between the scaffolds with and without MSCs. CONCLUSIONS: Even though this is a short-term study, we demonstrated that many MSCs in the scaffold survived after implantation in an acute rabbit rotator cuff defect. Furthermore, the generation of type I collagen increased more in the scaffold with MSCs than it did in the scaffold without MSCs. MSCs are thought to promote tendon healing by producing type I collagen when they are applied at the tendon defect.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 12/2012; · 1.93 Impact Factor
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    ABSTRACT: Study Design. An experimental comparative study on moderate epidural hypothermia (MEH), vs moderate systemic hypothermia (MSH) following spinal cord injury (SCI).Objective. To compare neuroprotective effects of hypothermia between MEH and MSH following SCI in rats.Summary of Background Data. Experimental MEH or MSH has been attempted for neuroprotection after ischemic or traumatic SCI. However, there are no comparative study on neuroprotective effect of MEH and MSH following SCI. If hypothermia is to be considered as one modality for treating SCI, further studies on the advantages and disadvantages of hypothermia will be mandatory.Methods. A spinal cord contusion was produced in all 32 rats, and these rats were randomly divided into 4 groups, 8 rats each group; (1) the control group (spinal cord contusion only), (2) the methylprednisolone (MP) group, (3) the MEH group (28° for 48 hours), (4) the MSH group (32° for 48 hours). The functional recovery was assessed using BBB scale and anti-apoptotic and anti-inflammatory effect were assessed.Results. The BBB scales in both the hypothermia groups were significantly higher than that of the control group at 6 weeks. The numbers of TUNEL-positive cells and OX-42 positive cells were significantly lower in both the MEH and the MSH groups compared to that of the control group. The p38 MAPK expression of the treated groups was significantly lower than that of the control group. The expression of caspase-8 and caspase-9 significantly decreased in the treated groups compared with that of the control group. However, in terms of caspase-3, only the MSH group has shown to be significantly lower than that of the control group.Conclusion. This study presented that both systemic and epidural hypothermia demonstrated neuroprotective effects following spinal cord injury. Systemic hypothermia showed more neuroprotective effect by anti-apoptotic and anti-inflammatory effects.
    Spine 08/2012; · 2.16 Impact Factor
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    ABSTRACT: PURPOSE: To compare the accuracy of ultrasonography and MR arthrography (MRA) imaging in detecting of rotator cuff tears with arthroscopic finding used as the reference standard. METHODS: The ultrasonography and MRA findings of 51 shoulders that underwent the arthroscopic surgery were prospectively analysed. Two orthopaedic doctors independently performed ultrasonography and interpreted the findings at the office. The tear size measured at ultrasonography and MRA was compared with the size measured at surgery using Pearson correlation coefficients (r). The sensitivity, specificity, accuracy, positive predictive value, negative predictive value and false-positive rate were calculated for a diagnosis of partial-and full-thickness rotator cuff tears. The kappa coefficient was calculated to verify the inter-observer agreement. RESULTS: The sensitivity of ultrasonography and MRA for detecting partial-thickness tears was 45.5 and 72.7 %, and that for full-thickness tears was 80.0 and 100 %, respectively. The accuracy of ultrasonograpy and MRA for detecting partial-thickness tears was 45.1 and 88.2 %, and that for full-thickness tears was 82.4 and 98 %, respectively. Tear size measured based on ultrasonography examination showed a poor correlation with the size measured at arthroscopic surgery (r = 0.21; p < 0.05). However, tear size estimated by MRA showed a strong correlation (r = 0.75; p < 0.05). The kappa coefficient was 0.47 between the two independent examiners. CONCLUSIONS: The accuracy of office-based ultrasonography for beginner orthopaedic surgeons to detect full-thickness rotator cuff tears was comparable to that of MRA but was less accurate for detecting partial-thickness tears and torn size measurement. Inter-observer agreement on the interpretation was fair. These results highlight the importance of the correct technique and experience in operation of ultrasonography in shoulder joint. LEVEL OF EVIDENCE: Diagnostic study, Level II.
    Knee Surgery Sports Traumatology Arthroscopy 06/2012; · 2.68 Impact Factor
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    ABSTRACT: Early passive motion exercise has been the standard rehabilitation protocol after rotator cuff repair for preventing postoperative stiffness. However, recent approaches show that longer immobilization may enhance tendon healing and quality. To elucidate whether early passive motion exercise affects functional outcome and tendon healing after arthroscopic rotator cuff repair. Randomized controlled trial; Level of evidence, 1. One hundred five consecutive patients who underwent arthroscopic repair for small to medium-sized full-thickness rotator cuff tears were included. Patients with large to massive tears and concomitant stiffness or labral lesions were excluded. Patients were instructed to wear an abduction brace for 4 to 5 weeks after surgery and to start active-assisted shoulder exercise after brace weaning. Fifty-six patients were randomly allocated into group 1: early passive motion exercises were conducted 3 to 4 times per day during the abduction brace-wearing period. Forty-nine patients were allocated into group 2: no passive motion was allowed during the same period. Range of motion (ROM) and visual analog scale (VAS) for pain were measured preoperatively and 3, 6, and 12 months postoperatively. Functional evaluations, including Constant score, Simple Shoulder Test (SST), and American Shoulder and Elbow Surgeons (ASES) score, were also evaluated at 6 and 12 months postoperatively. Ultrasonography, magnetic resonance imaging, or computed tomography arthrography was utilized to evaluate postoperative cuff healing. There were no statistical differences between the 2 groups in ROM or VAS for pain at each time point. Functional evaluations were not statistically different between the 2 groups either. The final functional scores assessed at 12 months for groups 1 and 2 were as follows: Constant score, 69.81 ± 3.43 versus 69.83 ± 6.24 (P = .854); SST, 9.00 ± 2.12 versus 9.00 ± 2.59 (P = .631); and ASES score, 73.29 ± 18.48 versus 82.90 ± 12.35 (P = .216). Detachment of the repaired cuff was identified in 12% of group 1 and 18% of group 2 (P = .429). Early passive motion exercise after arthroscopic cuff repair did not guarantee early gain of ROM or pain relief but also did not negatively affect cuff healing. We suggest that early passive motion exercise is not mandatory after arthroscopic repair of small to medium-sized full-thickness rotator cuff tears, and postoperative rehabilitation can be modified to ensure patient compliance.
    The American journal of sports medicine 01/2012; 40(4):815-21. · 3.61 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the clinical and structural outcome of the new fixation technique of type-II SLAP repair using double anchors compared with conventional method. Twenty-eight patients with 29 shoulders, who were followed up for at least 1 year after surgery, were enrolled. Fourteen shoulders were treated using the new technique (group 1), and 15 shoulders using the conventional technique (group 2). The clinical outcomes were evaluated using two different functional scores, the pain VAS and range of motion. The postoperative labral integrity was determined by magnetic resonance imaging at 1 year after surgery. At postoperative 6 months, all functional scores of group 1 were superior to group 2, particularly in pain VAS and Constant Scoring System. All ranges of motion in group 1 showed a better result than in group 2, particularly in forward flexion and external rotation at 90° abduction (88° ± 4.8 in group 1 and 84° ± 9.2 in group 2, P = 0.03). At postoperative 12 months and the last visit, all functional scores in group 1 were superior to those in group 2 and all external rotations at 90° of abduction in group 1 showed significantly better results than those of group 2. All patients in group 1 showed complete healing of the repaired SLAP lesion but one patient in group 2 showed partial detachments on the MRI. This new technique provides anatomical restoration of a SLAP lesion and yields successful clinical and structural outcomes at a short-term follow-up. Randomized controlled trials, level II.
    Knee Surgery Sports Traumatology Arthroscopy 10/2011; 20(10):1935-42. · 2.68 Impact Factor
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    Yang-Soo Kim, Ji-Hoon Ok
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    ABSTRACT: Purpose: We reviewed arthroscopic reconstruction among the several treatment options for anterior shoulder instability with a bony Bankart lesion. Materials and Methods: Although open Bankart repair has long been considered the optimal surgical management of anterior shoulder instability, advancements in arthroscopic techniques have led to a recent shift to arthroscopic Bankart repair. However, for cases of a glenoid bony defect, several authors have reported various methods to accurately measure the amount of bony defect. Results: The arthroscopic technique of bony Bankart reconstruction continues to evolve and various methods have followed. To overcome the limitations of single fixation of a Bankart lesion, arthroscopic dual fixation (2 point fixation) has recently been tried to anatomically repair and restore the rigid fixation of a bony fragment. The concept of performing the Bristow-Latarjet transfer procedure under arthroscopy has also recently emerged. However, a large series of cases and long term follow up are required to prove the better results. Conclusion: To obtain a successful outcome for patients with anterior instability with a glenoid bony defect, it is imperative that the surgeon be aware of the accurate status of the bony defect and the intraoperative, postoperative factors associated with the proper treatment of this unstable pathology.
    The Journal of the Korean Shoulder and Elbow Society. 01/2011; 14(1).
  • The Journal of trauma 08/2009; 67(1):E1-4. · 2.35 Impact Factor
  • In-Young Ok, Seok-Jung Kim, Ji-Hoon Ok
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    ABSTRACT: Nine patients aged over 8 years with developmental dislocation of the hip were treated by an open reduction, femoral shortening and varus derotation osteotomy with or without a Chiari osteotomy. The mean age of the patients was 11.1 years (range 8-17 years), and the mean follow-up period was 7.1 years (range 1-13 years). The left hip was involved in four cases: the right in three and two cases were bilateral. One hip redislocated. The remaining patients recovered nearly full movement of the affected hip. Five out of eight patients had a normal gait without limping or pain. Two others limped secondary to a leg-length discrepancy, which was corrected with leg equalization. The remaining patient had an improvement of her preoperative limp and was pain-free. These results indicate that it is possible to obtain good hip function after open reduction of a developmentally dislocated hip, even after the age of 8 years.
    Journal of Pediatric Orthopaedics B 08/2007; 16(4):256-61. · 0.53 Impact Factor

Publication Stats

20 Citations
24.15 Total Impact Points

Institutions

  • 2012
    • Seoul National University Bundang Hospital
      • Department of Orthopaedic Surgery
      Sŏul, Seoul, South Korea
  • 2007–2011
    • Catholic University of Korea
      • College of Medicine
      Seoul, Seoul, South Korea