Seok Won Chung

Factors Affecting Rotator Cuff Healing After Arthroscopic Repair Osteoporosis as One of the Independent Risk Factors

Background: The prognostic factors associated with structural outcome after arthroscopic rotator cuff repair have not yet been fully determined. Hypothesis: The hypothesis of this study was that bone mineral density (BMD) is an important prognostic factor affecting rotator cuff healing after arthroscopic cuff repair. Study Design: Cohort study; Level of evidence, 3. Methods: Among 408 patients who underwent arthroscopic repair for full-thickness rotator cuff tear between January 2004 and July 2008, 272 patients were included whose postoperative cuff integrity was verified by computed tomography arthrography (CTA) or ultrasonography (USG) and simultaneously who were evaluated by various functional outcome instruments. The mean age at the time of operation was 59.5 ± 7.9 years. Postoperative CTA or USG was performed at a mean 13.0 ± 5.1 months after surgery, and the mean follow-up period was 37.2 ± 10.0 months (range, 24-65 months). The clinical, structural, and surgery-related factors affecting cuff integrity including BMD were analyzed using both univariate and multivariate analysis. Evaluation of postoperative cuff integrity was performed by musculoskeletal radiologists who were unaware of the present study. Results: The failure rate of rotator cuff healing was 22.8% (62 of 272). The failure rate was significantly higher in patients with lower BMD (P < .001); older age (P < .001); female gender (P = .03); larger tear size (P < .001); higher grade of fatty infiltration (FI) of the supraspinatus, infraspinatus, and subscapularis (all P < .001); diabetes mellitus (P = .02); shorter acromiohumeral distance (P < .001); and associated biceps procedure (P < .001). However, in the multivariate analysis, only BMD (P = .001), FI of the infraspinatus (P = .01), and the amount of retraction (P = .03) showed a significant relationship with cuff healing failure following arthroscopic rotator cuff repair. Conclusion: Bone mineral density, as well as FI of the infraspinatus and amount of retraction, was an independent determining factor affecting postoperative rotator cuff healing. Further studies with prospective, randomized, and controlled design are needed to confirm the relationship between BMD and postoperative rotator cuff healing.

Arthroscopic Repair of Massive Rotator Cuff Tears Outcome and Analysis of Factors Associated With Healing Failure or Poor Postoperative Function

Background: Many patients with an unhealed cuff after repair show functional improvement. Purpose: To evaluate outcomes of arthroscopically repaired massive rotator cuff tears and to identify prognostic factors affecting rotator cuff healing and functional outcome, especially in patients with failed rotator cuff healing. Study Design: Case series; Level of evidence, 4. Methods: Among 173 patients who underwent arthroscopic repair of a massive rotator cuff tear, 108 patients with a mean age of 63.7 years were included. Outcome evaluation was completed both anatomically (CT arthrography or ultrasonography) and functionally at a minimum of 1 year postoperatively; mean follow-up period was 31.68 ± 15.81 months. Various factors affecting cuff healing were analyzed, and factors affecting functional outcome were evaluated in patients with failed repairs using both univariate and multivariate analyses. Results: The anatomic failure rate was 39.8% in arthroscopically repaired massive rotator cuff tears; however, functional status significantly improved regardless of cuff healing (P < .05). Several factors were associated with failure of cuff healing in the univariate analysis, but only fatty infiltration (FI) of the infraspinatus was significantly related to healing failure in the multivariate analysis (P = .04). Among patients with failed rotator cuff healing, only reduced postoperative acromiohumeral distance (AHD) was related to poor functional outcome in the multivariate analysis (P = .01), with a cutoff value of 4.1 mm. Conclusion: Despite a high rate of healing failures, arthroscopic repair can be recommended in patients with massive rotator cuff tears because of the functional gain at midterm follow-up. Higher FI of the infraspinatus was the single most important factor negatively affecting cuff healing. In cases of failed massive rotator cuff repair, no preoperative factor was able to predict poor functional outcome; reduced postoperative AHD was the only relevant functional determinant in the patients’ eventual functional outcome and should be considered when ascertaining a prognosis and planning further treatment strategies.

Is Early Passive Motion Exercise Necessary After Arthroscopic Rotator Cuff Repair

Background: 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. Purpose: To elucidate whether early passive motion exercise affects functional outcome and tendon healing after arthroscopic rotator cuff repair. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: 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. Results: 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). Conclusion: 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.

Outcome of Rotator Cuff Repair in Large-to-Massive Tear With Pseudoparalysis A Comparative Study With Propensity Score Matching

Background: Active range of motion deficit is one of the alleged negative influencing factors of rotator cuff repair. Recently, with the popularity of reverse total shoulder arthroplasty (RTSA), there is a tendency toward performing RTSA in cases of nonarthritic large-to-massive tears with pseudoparalysis. Hypothesis: Rotator cuff repair in patients with active motion deficit may yield inferior outcome. Study Design: Cohort study; Level of evidence, 3. Methods: Among 195 complete repairs of large-to-massive rotator cuff tears, 35 patients experienced painful pseudoparalysis preoperatively. Propensity score matching (1-to-1) was performed between pseudoparalytic and nonpseudoparalytic groups. Finally, 29 patients in each group were matched using the following variables: age, gender, dominance, onset period, aggravation period, number of tendons involved, retraction, operation method (arthroscopic or mini-open), rows of repair (single or double), number of anchors, and fatty degeneration of the supraspinatus, infraspinatus, and subscapularis. At least 1 year after surgery (mean, 30.5 months), range of motion, visual analog scale for pain and satisfaction, Constant score, Simple Shoulder Test, American Shoulder and Elbow Surgeons (ASES) score, and University of California, Los Angeles shoulder rating scale (UCLA score) were evaluated. Healing of repaired cuffs was evaluated by computed tomography arthrography. Results: Range of motion was improved in both groups after rotator cuff repair. Active forward elevation had significantly improved postoperatively in the pseudoparalytic group (P < .001). All functional outcome scores improved at the final follow-up visit compared with preoperative values (all P < .05). Preoperative Constant, ASES, and UCLA scores were significantly inferior in the pseudoparalytic group, but all except the Constant score showed no differences between the 2 groups at the final follow-up (P = .04). Postoperatively, 7 patients (24.1%) in the pseudoparalytic and 1 (3.4%) in the nonpseudoparalytic group showed pseudoparalysis (P = .03). Among 37 patients who underwent postoperative computed tomography arthrography, cuff healing was achieved in 6 of 18 (33.3%) in the pseudoparalytic and 9 of 19 (47.4%) in the nonpseudoparalytic group (P = .385). Conclusion: Recovery from pseudoparalysis after rotator cuff repair was evident in a large portion of the study group, and postoperative function and cuff healing were not different according to the presence of pseudoparalysis. Considering possible complications and longevity of RTSA, rotator cuff repair should be the first-line treatment option for large-to-massive tears.

The Efficacy of Acromioplasty in the Arthroscopic Repair of Small- to Medium-Sized Rotator Cuff Tears Without Acromial Spur: Prospective Comparative Study

PURPOSE To assess the role of acromioplasty in the arthroscopic repair of small- to medium-sized rotator cuff tears. METHODS A prospective randomized trial of 120 patients who had small- to medium-sized rotator cuff tears and various types of acromions without spurs were included. Sixty patients received arthroscopic rotator cuff repair with acromioplasty (group I), and another sixty received the same procedure without acromioplasty (group II). The mean age at surgery was 57.8 ± 9.3 years in group I and 55.8 ± 8.0 years in group II. The shape of the acromion was flat in 18 patients, curved in 32, and hooked in 10 in group I, and it was flat in 15 patients, curved in 36, and hooked in 9 in group II. The mean tear size was similar in the two groups (14.6 ± 5.2 mm in group I and 15.3 ± 7.0 mm in group II). Pain and satisfaction were estimated and range of motion was measured at a mean of 35 months after surgery. Functional outcomes were assessed with American Shoulder and Elbow Surgeons: Constant; and University of California, Los Angeles scores. Tendon healing was evaluated by magnetic resonance imaging postoperatively. RESULTS Clinical outcome was significantly improved in both groups after arthroscopic rotator cuff repair (P < .05). There were no significant differences with respect to pain and range of motion between the groups at the final follow-up (1.1 ± 0.9 v 1.3 ± 1.4 on visual analog scale). Functional outcomes also showed no significant differences between the 2 groups (American Shoulder and Elbow Surgeons score, 90.7 ± 13.1 v 87.5 ± 12.0; Constant score, 85.0 ± 11.3 v 83.3 ± 13.0; and University of California, Los Angeles score, 33.4 ± 3.3 v 32.3 ± 3.5). Postoperative imaging showed that the retear rate was 17% in group I and 20% in group II (P = .475). CONCLUSIONS Arthroscopic repair of small- to medium-sized rotator cuff tears provided pain relief and improved functional outcome with or without acromioplasty. Clinical outcomes were not significantly different, and acromioplasty may not be necessary in the operative treatment of patients with small- to medium-sized rotator cuff tears in the absence of acromial spurs. LEVEL OF EVIDENCE Level II, prospective comparative study.

Quality of Life After Arthroscopic Rotator Cuff Repair Evaluation Using SF-36 and an Analysis of Affecting Clinical Factors

Background: Despite its importance, few studies regarding health-related quality of life (HRQOL) after rotator cuff repair have been reported. Purpose: To evaluate the outcomes of rotator cuff repair in terms of HRQOL using SF-36 and to analyze factors affecting postoperative HRQOL. Study Design: Case series; Level of evidence, 4. Methods: We included 309 patients who were followed-up for a mean 26.3 months (range, 12-48 months) after arthroscopic rotator cuff repair, between November 2004 and August 2008, and who underwent periodic measurement of HRQOL using SF-36 preoperatively, 1 year postoperatively, and at the final follow-up. The correlation between SF-36 and shoulder-specific functional outcome measures (American Shoulder and Elbow Surgeons [ASES], Simple Shoulder Test [SST], and Constant score) was evaluated using correlation analysis, and the relationship between various clinical factors, including rotator cuff healing and HRQOL, was assessed using univariate and multivariate analyses. Results: The SF-36 scores for physical HRQOL and mental HRQOL showed significant improvement, from 40.40 to 47.53 and from 44.45 to 50.55 at 12 months after surgery, respectively (all P < .001), and improvement was maintained with 48.24 and 50.45, respectively, at the final follow-up (all P < .001). Scores also showed improvement according to all clinical variables, even after stratification of each variable. The correlation between SF-36 and shoulder-specific functional outcome measures was fair to moderate (Pearson correlation coefficients, 0.199-0.528). Various factors had significant effects on preoperative physical and mental HRQOL; however, postoperatively (at 12 months and final follow-up, respectively), only older age (P = .008 and .013), female sex (P = .036 and .043), presence of diabetes (P = .026 and .027), and low level of sports activity (P = .049 at final follow-up) had a negative effect on postoperative physical HRQOL in multivariate analysis, and female sex (P = .010 and .001) was the only factor leading to worse postoperative mental HRQOL. Conclusion: Arthroscopic rotator cuff repair significantly improved the patients’ HRQOL both physically and mentally. Older age, female sex, diabetes, and low level of sports activity were related to low postoperative physical HRQOL, and female sex was also related to low postoperative mental HRQOL.

Effect of Platelet-Rich Plasma and Porcine Dermal Collagen Graft Augmentation for Rotator Cuff Healing in a Rabbit Model

Background: The rate of healing failure after surgical repair of chronic rotator cuff tears is considerably high. Purpose: To verify the effect of platelet-rich plasma (PRP) with and without porcine dermal collagen graft augmentation on tendon-to-bone healing, using the rabbit supraspinatus tendon. Study Design: Controlled laboratory study. Methods: A total of 80 rabbits were randomly allocated into 4 groups (20 rabbits per group: 12 for histological and 8 for mechanical testing): repair (R), repair + patch augmentation (RPa), repair + PRP (RPr), and repair + patch + PRP (RPaPr). The right shoulder was used for experimental interventions, and the left served as a control. Six weeks after the detachment of the supraspinatus, the torn tendon was repaired in a transosseous manner, simulating double-row repair in all groups. Platelet-rich plasma was prepared and applied onto the repair site in the RPr and RPaPr groups, and the patch was used to augment the repair in the RPa and RPaPr groups. The mechanical tensile strength test was performed at 8 weeks after repair and the histological evaluation at 4 and 8 weeks. Results: At 4 weeks, the collagen fibers were poorly organized, and fiber continuity was not established in all groups. However, vascularity and cellularity were higher with granulation tissue formation in the PRP-treated groups (RPr and RPaPr) than the nontreated groups (R and RPa). At 8 weeks, tendon-to-bone integration was much improved with more collagen fibers, and longitudinally oriented collagen fibers were visible in all groups. The PRP-treated groups showed better collagen fiber continuity and orientation than the nontreated groups; however, no distinctive difference was found between the patch-augmented groups (RPa and RPaPr) and nonaugmented groups (R and RPr). The mean load-to-failure results were 61.57 ± 29.99 N, 76.84 ± 16.08 N, 105.35 ± 33.82 N, and 117.93 ± 12.60 N for the R, RPa, RPr, and RPaPr groups, respectively, and they were significantly different between the R and RPr (P = .018), R and RPaPr (P = .002), and RPa and RPaPr (P = .029) groups. Conclusion: This animal study showed the enhancement of tendon-to-bone healing after local administration of autologous PRP assessed by histological and biomechanical testing in a rabbit model of chronic rotator cuff tears. However, there was little additive effect of the patch graft. Clinical Relevance: The use of PRP might be a biological supplement to increase the rotator cuff healing rate, which still remains low even after successful cuff repair, but this result should be interpreted with caution regarding clinical applications.

Functional integration of serial dilution and capillary electrophoresis on a PDMS microchip

For the quantitative analysis of an unknown sample a calibration curve should be obtained, as analytical instruments give relative, rather than absolute measurements. Therefore, researchers should make standard samples with various known concentrations, measure each standard and the unknown sample, and then determine the concentration of the unknown by comparing the measured value to those of the standards. These procedures are tedious and time-consuming. Therefore, we developed a polymer based microfluidic device from polydimethylsiloxane, which integrates serial dilution and capillary electrophoresis functions in a single device. The integrated microchip can provide a one-step analytical tool, and thus replace the complex experimental procedures. Two plastic syringes, one containing a buffer solution and the other a standard solution, were connected to two inlet holes on a microchip, and pushed by a hydrodynamic force. The standard sample is serially diluted to various concentrations through the microfluidic networks. The diluted samples are sequentially introduced through microchannels by electro-osmotic force, and their laser-induced fluorescence signals measured by capillary electrophoresis. We demonstrate the integrated microchip performance by measuring the fluorescence signals of fluorescein at various concentrations. The calibration curve obtained from the electropherograms showed the expected linearity.

Evaluation of Fatty Degeneration of the Supraspinatus Muscle Using a New Measuring Tool and Its Correlation Between Multidetector Computed Tomography and Magnetic Resonance Imaging

Background: The assessment of fatty degeneration of rotator cuff muscles with a reliable grading system is very important. However, there is no generally accepted tool to measure it quantitatively. Purpose: This work was undertaken to introduce a new method to evaluate fatty degeneration by calculating the occupation ratio of the supraspinatus, to determine the correlation between this occupation ratio and the degree of Goutallier’s fatty degeneration or tear size of rotator cuff muscles and to assess the correlation between multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) using this new measuring tool. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Sixty-one patients with full-thickness rotator cuff tears who had undergone arthroscopic rotator cuff repair were included. The occupation ratio was measured using the magic selection tool in Photoshop on MDCT and both T1- and T2-weighted oblique sagittal magnetic resonance images of Y-view. One-way analysis of variance was used to determine the association between this occupation ratio and the degree of fatty degeneration as assessed by Goutallier’s method. The correlation between the occupation ratio and tear size, and the correlation of the occupation ratio between MDCT and MRI, were evaluated using the Pearson correlation coefficient. In addition, the interobserver and intraobserver reliabilities of this measuring tool were assessed on each image by 2 orthopaedic surgeons and analyzed using interclass correlation coefficients. Results: Comparison of the occupation ratio measured by this new method with the Goutallier grade of fatty degeneration on MDCT and MRI revealed a highly significant correlation, with all P values < .001. Also, comparison of this new occupation ratio and cuff tear size showed a reverse correlation on MDCT, T1-weighted magnetic resonance images, and T2-weighted images, with Pearson correlation coefficients of −.61, −.56, and −.50 (all P < .001) by rater 1, and −.57, −.53, and −.43 (all P < .001) by rater 2. Comparison of the occupation ratio between MDCT and MRI demonstrated significant correlation, with Pearson correlation coefficients of .78 and .87 between MDCT and T1-weighted magnetic resonance images and .73 and .82 between MDCT and T2-weighted images. The interobserver and intraobserver reliabilities of this new measuring tool on MDCT and both T1- and T2-weighted magnetic resonance images were excellent in all images, with interobserver correlation of .89, .92, and .91 and intraobserver correlation of .89 and .96, .90 and .98, and .85 and .97, respectively. Conclusion: This new quantitative measuring tool to evaluate the fatty degeneration of rotator cuff muscles was reliable and correlated well with both the preexisting grade of fatty degeneration and cuff tear size. Also, there was a significant correlation between oblique sagittal images of MDCT and MRI using this method; therefore, MDCT can be another option for imaging modality, comparable with MRI, for the evaluation of fatty degeneration of rotator cuff muscles.

Intravascular micro active catheter for minimal invasive surgery

The authors have developed an intravascular micro active catheter system for microsurgery in human vascular systems, such as cerebrovascular and coronary arteries. Also this system can be applied to laparoscopical treatment. It consists of the micro active bending catheter and some functional catheters. The former is a tube-like catheter which has an outer-diameter of 3.0 mm, an inner-diameter of 2.0 mm and a length of 1000 mm. Its inner hole is a pathway for the functional catheters, such as conventional guide wire, balloon catheter, conventional suction tube, micro ultrasound probe catheter, fiber optics (angioscope), angioplatic devices and drug injection lines. This active bending catheter is actuated with three SMA (shape-memory-alloy) zigzag type springs-SMA wires are connected with plastic and brass connection links. This actuator can be bent to any direction with the PWM controlled electric current. The authors also developed a micro drug infusion catheter and a micro ultrasound probe catheter fitted to the inner hole of active bending catheter. All of these systems were evaluated with the human mock circulation system. They can be introduced through 90/spl deg/, 120/spl deg/, 180/spl deg/ crooked branches to the brachiocephalic artery, common carotid artery, subelavian artery and so on in the mock circulation system. Also, the authors tested this endoscope system in vivo by performing laparoscopical surgery on a pig. They could easily induce the catheter to the point they wanted in the pig ovary.