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Ian K Y Lo

Publications and source records attributed to Ian K Y Lo.

At least 19 recordsLinked to original sources
PubMed2006

Effects of ligament repair on laxity and creep behavior of an early healing ligament scar.

BACKGROUND: Previous clinical studies have reported that conservatively managed medial collateral ligament (MCL) injuries remained unstable 9 years post injury with subjective complaints of muscle weakness, reinjuries, and post-traumatic osteoarthritis. Animal studies have also reported that healing MCLs were weaker and more lax than controls. Therefore, our purpose was to study the early effects of ligament repair on scar laxity, creep, and creep recovery in a rabbit model of bilateral medial collateral ligament (MCL) injury. METHODS: Each rabbit had one MCL cut in midsubstance which was not repaired, while the other MCL had a sagittal Z-plasty repair. Six weeks after surgery, isolated bone-MCL-bone complexes were biomechanically tested for MCL laxity, cyclic creep, creep recovery, and then loaded to ultimate failure. RESULTS: Nonrepaired scars were significantly more lax than both repaired Z-plasty scars and normal controls. In contrast, there was no significant difference in MCL laxity between repaired scars and normal controls. There were no significant differences between nonrepaired or repaired scars for either cyclic creep and creep recovery. Both crept significantly more and recovered significantly less than normal controls after the same load history. There were no significant differences in the failure load, stiffness, and tensile strength between gap scars and Z-plasty scars. All healing ligaments had significantly lower failure load, stiffness, and tensile strength than normal controls. CONCLUSIONS: The present study demonstrates that ligament repair is effective in decreasing short-term laxity of ligament scars. These 6-week scars would be prone to abnormal creep if loaded excessively.

Animals↗
PubMed2006

Arthroscopic rotator cuff repair.

Arthroscopic rotator cuff repair is being performed by an increasing number of orthopaedic surgeons. The principles, techniques, and instrumentation have evolved to the extent that all patterns and sizes of rotator cuff tear, including massive tears, can now be repaired arthroscopically. Achieving a biomechanically stable construct is critical to biologic healing. The ideal repair construct must optimize suture-to-bone fixation, suture-to-tendon fixation, abrasion resistance of suture, suture strength, knot security, loop security, and restoration of the anatomic rotator cuff footprint (the surface area of bone to which the cuff tendons attach). By achieving optimized repair constructs, experienced arthroscopic surgeons are reporting results equal to those of open rotator cuff repair. As surgeons' arthroscopic skill levels increase through attendance at surgical skills courses and greater experience gained in the operating room, there will be an increasing trend toward arthroscopic repair of most rotator cuff pathology.

Arthroscopy↗
PubMed2005

Triple labral lesions: pathology and surgical repair technique-report of seven cases.

PURPOSE: The purpose of this article is to describe the pathology and operative treatment of triple labral lesions. TYPE OF STUDY: Retrospective review. METHODS: From June 1998 to June 2001, 297 patients underwent surgery by the senior author for lesions of the glenoid labrum. Of these, 7 patients (2.4%) had combined lesions of the anterior, posterior, and superior labrum. All patients were male with a mean age of 25 +/- 7.3 years. All had a traumatic onset of symptoms. There were 4 dominant and 3 nondominant shoulders. Two patients had previously undergone surgery for instability. Each patient's primary complaint was instability and apprehension in the abducted and externally rotated position. No patient complained of posterior instability, although 3 patients had physical examinations suggestive of excessive posterior laxity. All patients underwent arthroscopic surgery following failure of conservative management. RESULTS: All patients had distinct anterior labrum, posterior labrum, and type II SLAP lesions. All anterior and posterior labrum injuries were Bankart type except one. Two patients had complete circumferential detachment of the labrum and the other 5 patients had a small portion of the labrum still attached. Six patients had a Hill-Sachs lesion and 1 patient had a reverse Hill-Sachs lesion. All were nonengaging Hill-Sachs lesions. All patients were treated with suture anchor fixation of the torn labrum to bone. The median number of anchors used for fixation was 7 (range, 5 to 9 anchors). All patients were treated with a standardized postoperative rehabilitation protocol. At latest follow-up, 6 of 7 patients were satisfied with the procedure. There were no cases of recurrent instability. One patient developed post-traumatic osteoarthritis and underwent a second arthroscopic procedure and subsequently required hemiarthroplasty. This patient was dissatisfied with his result. CONCLUSIONS: Triple labral lesions represent an uncommon combination of lesions of the glenoid labrum. The majority of cases are likely secondary to primary anterior instability. Arthroscopic repair of triple labral lesions using suture anchor fixation to bone, although difficult and time consuming, can restore normal stability to the glenohumeral joint. The long-term outcome of these severe labral lesions remains to be determined, particularly with respect to the development of post-traumatic osteoarthritis. LEVEL OF EVIDENCE: Level IV. Case series, no or historical control group.

Adolescent↗
PubMed2005

Immediate postoperative fluid retention and weight gain after shoulder arthroscopy.

PURPOSE: The primary purpose of this study was to determine the amount of weight gain immediately after shoulder arthroscopy. In addition, patient and surgical factors correlated with weight gain were analyzed. We hypothesized that there would be a significant increase in weight immediately after shoulder arthroscopy and that the amount of weight gain would correlate with a number of surgical factors. TYPE OF STUDY: Observational case series. METHODS: Fifty-three patients were enrolled in the study. There were 34 male and 19 female patients, with a mean age of 47.1 +/- 13.8 years. All patients were weighed before and after surgery using the same weight scale by the same observer. Weight gain was calculated and adjusted to account for the weight of the dressing and sling. Weight gain then was correlated to various clinical and surgical variables. Pearson correlation coefficients, Student t tests, and stepwise regression were used to determine significant correlations between clinical and surgical variables and weight gain. RESULTS: The mean amount of net weight gain was 8.7 +/- 3.9 lb (range, 0.8-18.8 lb), representing 4.6% +/- 2.1% of preoperative weight. The mean amount of weight gain attributable to arthroscopy fluid only was 4.2 +/- 3.8 lb (range, 0-14.5 lb), representing a gain of 2.2% +/- 2.0% of preoperative weight. The mean amount of intravenous fluid infused was 1,885 +/- 547 mL, and the mean amount of normal saline arthroscopy fluid used was 30 +/- 24 L. Surgical time, the amount of arthroscopy fluid, the size of the rotator cuff tear, the number of tendons involved, the presence of a subscapularis tear, the number of procedures performed, the concomitant performance of a subacromial decompression, the number of BioCorkscrew (Arthrex, Inc., Naples, FL) anchors used, and the total number of anchors used all correlated with increasing weight gain (all P < .05). A procedure of stepwise regression selection did not identify any quantitative parameters attributable to weight gain other than the earlier-described parameters. There were no significant intraoperative or postoperative complications attributable to the amount of weight gain. CONCLUSIONS: Weight gain immediately after shoulder arthroscopy is a common finding. Although no complications were seen in this group of patients, both patients and surgeons should be aware of this concern after shoulder arthroscopy and the potential complications related to it.

Adult↗
PubMed2005

Matrix molecule mRNA levels in the bursa and rotator cuff of patients with full-thickness rotator cuff tears.

PURPOSE: The purpose of this study was to evaluate at the mRNA level a subset of extracellular matrix molecules relevant during healing and remodeling of rotator cuff tears. TYPE OF STUDY: Controlled laboratory study. METHODS: Bursal and rotator cuff tissue from the margin of the rotator cuff tear were harvested from 10 patients (mean age, 57.5 +/- 7.3 years) undergoing surgical repair of full-thickness rotator cuff tears. There were six male and four female patients with a mean duration of symptoms of 14.6 months (range, 2 to 60 months). The mean tear size was 4.4 cm. In addition, tissue was obtained from 6 cadaveric specimens with no gross evidence of rotator cuff tearing. Reverse transcription polymerase chain reaction (RT-PCR) was performed for type I, II, and III collagen, biglycan, decorin, and aggrecan, and normalized to the housekeeping gene GAPDH. RESULTS: RT-PCR showed that both the bursa and rotator cuff margin had increased mRNA levels for type I and type III collagen in patients with full-thickness rotator cuff tears when compared with normal cadaveric controls. In addition, there was a significant decrease in decorin mRNA levels and an increase in aggrecan mRNA levels in the rotator cuff margin of torn rotator cuff tendons when compared with normal cadaveric controls. CONCLUSIONS: These results suggest that both the bursa and rotator cuff margin of patients with rotator cuff tears are actively remodeling after injury and that both tissues may potentially contribute to the healing process following repair. CLINICAL RELEVANCE: These findings may help clinicians determine what aspects of the repair process can be manipulated to affect optimal ruptured tendon repair.

Bursa, Synovial↗
PubMed2005

Gap junctions of the medial collateral ligament: structure, distribution, associations and function.

Ligaments are composed of two major components: cells and extracellular matrix. The cells express gap junction proteins and are arranged into a series of rows that traverse the tissue, suggesting that all the cells of the tissue are functionally interconnected. The results of our study demonstrate that medial collateral ligament (MCL) cells do not have a uniform fusiform morphology or placement along a row of cells as previously suggested, but rather display a complex placement and form that weaves within the collagen matrix in a manner that is far more extensive and complex than previously appreciated. Within this morphological context, we find that MCL cells in vivo contain functional gap junctions (verified using fluorescence recovery after photobleaching) that are localized to sites of close cell-cell contact, and this pattern imparts or reflects a bipolarity inherent to each cell. When we studied ligament cells in conventional tissue culture we found that this bipolarity is lost, and the placement of gap junctions and their related proteins, as well as general cell morphology, is also altered. Finally, our study demonstrates, for the first time, that in addition to gap junctions, adherens junctions and desmosomes are also expressed by MCL cells both in vivo and in vitro and map to sites of cell-cell contact.

Adherens Junctions↗
PubMed2005

Quality-of-life outcome following hemiarthroplasty or total shoulder arthroplasty in patients with osteoarthritis. A prospective, randomized trial.

BACKGROUND: Both total shoulder arthroplasty and hemiarthroplasty have been used commonly to treat severe osteoarthritis of the shoulder; however, their effect on disease-specific quality-of-life outcome is unknown. The purpose of this study was to compare the quality-of-life outcome following hemiarthroplasty with that following total shoulder arthroplasty in patients with osteoarthritis of the shoulder. METHODS: Forty-two patients with a diagnosis of osteoarthritis of the shoulder were randomized to receive a hemiarthroplasty or a total shoulder arthroplasty. One patient died, and all others were evaluated preoperatively and at six weeks and three, six, twelve, eighteen, and twenty-four months postoperatively with use of a standardized format including a disease-specific quality-of-life measurement tool (Western Ontario Osteoarthritis of the Shoulder [WOOS] index), general shoulder rating scales (University of California at Los Angeles [UCLA] shoulder scale, Constant score, and American Shoulder and Elbow Surgeons [ASES] evaluation form), general pain scales (McGill pain score and visual analogue scale), and a global health measure (Short Form-36 [SF-36]). When a patient required revision of a hemiarthroplasty to a total shoulder arthroplasty, the last score before he or she "crossed over" was used for the analysis. RESULTS: Significant improvements in disease-specific quality of life were seen two years after both the total shoulder arthroplasties and the hemiarthroplasties. There were no significant differences in quality of life (WOOS score) between the group treated with total shoulder arthroplasty and that treated with hemiarthroplasty (90.6 +/- 13.2 and 81.5 +/- 24.1 points, respectively; p = 0.18). The other outcome measures demonstrated similar findings. Two patients in the hemiarthroplasty group crossed over to the other group by undergoing a revision to a total shoulder arthroplasty because of glenoid arthrosis. CONCLUSIONS: Both total shoulder arthroplasty and hemiarthroplasty improve disease-specific and general quality-of-life measurements. With the small number of patients in our study, we found no significant differences in these measurements between the two treatment groups. LEVEL OF EVIDENCE: Therapeutic Level I.

Aged↗
PubMed2004

Matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase mRNA levels are specifically altered in torn rotator cuff tendons.

BACKGROUND: Rotator cuff tears are a cause of pain and disability in the shoulder. The molecular changes associated with rotator cuff tearing are unclear. A subset of matrix metalloproteinases and tissue inhibitors of metalloproteinase, which are involved in extracellular matrix remodeling and degradation, were evaluated. HYPOTHESIS: There would be an increase in the mRNA level of specific matrix metalloproteinase and a decrease in the mRNA level of specific tissue inhibitors of metalloproteinase in rotator cuff tendon tissue obtained from patients with rotator cuff tears. STUDY DESIGN: Controlled laboratory study. METHODS: Tissue was obtained from 10 patients undergoing rotator cuff repair for full-thickness rotator cuff tears. Also, tissue was obtained from cadaveric specimens with no gross evidence of rotator cuff tearing. Reverse transcription polymerase chain reaction was performed for the collagenases (MMP-1, MMP-8, MMP-13), the stromelysins (MMP-3, MMP-10, MMP-11), and the tissue inhibitors of metalloproteinase (TIMP-1, TIMP-2, TIMP-3, TIMP-4). Western blotting was performed to confirm the mRNA changes demonstrated in collagenase-3 (MMP-13). RESULTS: There was a significant increase in collagenase-3 (MMP-13) mRNA levels, a decrease in stromelysin-1 (MMP-3) mRNA levels, and a decrease in tissue inhibitor of metalloproteinase-2, -3, and -4 mRNA levels. Western blotting demonstrated an increase in the active form of collagenase-3 (MMP-13) in rotator cuff tendon tears. CONCLUSIONS: The mRNA levels of specific matrix metalloproteinases and tissue inhibitors of metalloproteinase are altered in torn rotator cuff tendons. CLINICAL RELEVANCE: With the known action of the matrix metalloproteinases and tissue inhibitors of metalloproteinase in extra-cellular matrix remodeling, these findings suggest that their roles in remodeling of rotator cuff tears should be further investigated.

Aged↗
PubMed2004

Arthroscopic repair of massive, contracted, immobile rotator cuff tears using single and double interval slides: technique and preliminary results.

PURPOSE: The purpose of this study is to describe the technique and review the preliminary results of arthroscopic repair of massive, contracted, immobile rotator cuff tears using an interval slide technique. TYPE OF STUDY: Case series. METHODS: From January 1999 to December 2000, the senior author (S.S.B.) performed arthroscopic rotator cuff repair on 94 massive rotator cuff tears. Of these, 9 (9.6%) were massive, severely contracted rotator cuff tears and required repair using an interval slide technique. A single interval slide was used in 6 patients, and a double interval slide was used in 3 patients. All patients were evaluated preoperatively and postoperatively using a modified University of California Los Angeles (UCLA) scoring system. RESULTS: At a mean follow-up time of 17.9 months (range, 10-24 months), 8 of 9 patients were satisfied with the procedure. The mean UCLA score increased from 10.0 preoperatively to 28.3 postoperatively (P <.00001). All patients showed some improvement in active motion, strength, or function. Active forward flexion improved significantly, from a preoperative mean of 108 degrees to a postoperative mean of 146.1 degrees (P =.025). Active external rotation increased significantly from a preoperative mean of 24.4 degrees to a postoperative mean of 35.0 degrees (P =.04). A significant increase in strength grade (2.2 to 3.6; P <.005) and function (2.5 to 7.1; P <.0005) were also seen. We encountered no significant complications to the procedure. CONCLUSIONS: The interval slide technique provides a method of mobilization of massive, severely contracted, immobile rotator cuff tears allowing repair of previously irreparable tears. This technique, in conjunction with arthroscopic rotator cuff repair, may provide patients with improvements in pain, motion, strength, and overall shoulder function. LEVEL OF EVIDENCE: Level IV.

Aged↗
PubMed2004

Arthroscopic biceps tenodesis using a bioabsorbable interference screw.

Arthroscopic biceps tenodesis has rarely been reported. The purpose of this study is to present our technique of arthroscopic biceps tenodesis using the Bio-Tenodesis (Arthrex, Naples, FL) screw system. This system uses a uniquely designed screwdriver that allows manipulation of the biceps tendon subacromially and intra-articularly, facilitates placement and maintenance of the biceps tendon at the base of the bone socket during interference screw insertion, and assures an adequate bone-tendon-screw interface.

Absorbable Implants↗
PubMed2004

The inverted pear glenoid: an indicator of significant glenoid bone loss.

PURPOSE: The purpose of this study was to determine the amount of glenoid bone loss required to produce an inverted pear glenoid. TYPE OF STUDY: Two-part anatomic study involving live subjects and cadaveric specimens. METHODS: From June 2000 to April 2002, 53 patients (mean age, 30 +/- 13 years) underwent arthroscopic evaluation and treatment with a diagnosis of anterior instability by the senior author (S.S.B.). Each of these patients underwent a 3-portal diagnostic arthroscopy to determine the morphology of the glenoid. Glenoids were classified as either inverted pear or non-inverted pear glenoids based on the visual appearance. The amount of glenoid bone loss was then quantified arthroscopically using a validated methodology. In addition, 6 fresh-frozen cadaveric specimens (mean age, 74.1 +/- 7.4 years) were dissected and evaluated to determine the minimum amount of bone loss required to produce an inverted pear glenoid. RESULTS: Forty-two patients were classified as having non-inverted pear glenoids and 11 patients were classified as having inverted pear glenoids. The mean amount of bone loss anteriorly was significantly more (P <.000006) in the inverted pear glenoid group (mean, 8.6 mm; range, 6 to 12 mm) than the non-inverted pear glenoid group (mean, 1.5 mm; range, 0 to 3.0 mm). The percentage of loss of glenoid width was also significantly different (inverted pear mean, 36%; range, 25% to 45% versus non-inverted pear mean, 6.2%; range, 0% to 12.5%; P <.000006). The mean amount of bone loss required in cadaveric specimens to convert a normal pear-shaped glenoid into an inverted pear glenoid was 7.5 mm (range, 6.5 to 9.0 mm), representing 28.8% of the glenoid width (range, 27% to 30%). CONCLUSIONS: The results of this study show that the majority of patients with the diagnosis of anterior instability show some bone loss anteriorly. However, the inverted pear glenoid represents a significant amount of bone loss, at least 25% to 27% of the width of the inferior glenoid. In patients with an inverted pear glenoid, a bone grafting procedure to restore the normal articular arc of the glenoid should be strongly considered to re-establish normal stability to the shoulder.

Adult↗
PubMed2004

Arthroscopic revision of failed rotator cuff repairs: technique and results.

PURPOSE: The purpose of this study was to review the results of arthroscopic revision rotator cuff repair in patients for whom a previous rotator cuff repair had failed. TYPE OF STUDY: Case series. METHODS: From October 1998 to October 2000, 14 patients with a mean age of 57.9 +/- 9.2 years underwent arthroscopic revision rotator cuff repair and were available for follow-up evaluation. The mean time from primary to revision procedure was 41.4 months (range, 8 to 240 months). Eleven patients had undergone a previous rotator cuff repair, 2 patients had undergone 2 rotator cuff repairs, and 1 patient had undergone 3 rotator cuff repairs. We found 2 medium, 1 large, and 11 massive recurrent rotator cuff tears, with a mean tear size of 4.4 x 5.5 cm. All large and massive tears required extensive arthroscopic dissection and mobilization of the rotator cuff to delineate the tear margins and repair the rotator cuff. All patients were evaluated preoperatively and postoperatively using a modified University of California Los Angeles (UCLA) scoring system. RESULTS: At a mean of 23.4 +/- 9.8 months after arthroscopic revision rotator cuff repair, 13 of 14 patients were satisfied with the procedure. The mean UCLA score increased from 13.1 +/- 2.3 preoperatively to 28.6 +/- 7.1 postoperatively (P <.00001). We noted 4 excellent, 5 good, 4 fair, and 1 poor result. The mean active forward elevation increased from 120.7 degrees +/- 48.9 degrees preoperatively to 153.6 degrees +/- 33.1 degrees postoperatively (P =.006). The mean active external rotation increased from 26.1 degrees +/- 19.3 degrees preoperatively to 44.3 degrees +/- 15.9 degrees postoperatively (P =.006). Of the 4 patients without active overhead function preoperatively, 3 gained overhead function postoperatively. One patient who did not regain overhead function had a poor result secondary to anterior deltoid detachment after the primary procedure. CONCLUSIONS: Revision arthroscopic rotator cuff repair is a technically demanding procedure. However, appropriate patient selection and careful attention to rotator cuff dissection, mobilization, and repair by arthroscopic means can lead to significant improvements in overall shoulder pain and function. LEVEL OF EVIDENCE: Level 4, case series (no or historical control group).

Aged↗
PubMed2004

The interval slide in continuity: a method of mobilizing the anterosuperior rotator cuff without disrupting the tear margins.

Massive, contracted, immobile rotator cuff tears involving the subscapularis, supraspinatus, and infraspinatus tendons present difficult surgical challenges to the arthroscopic surgeon. We describe the interval slide in continuity, a release and resection of a portion of the coracohumeral ligament and rotator interval. This technique improves the mobility of the subscapularis and supraspinatus tendons but also maintains an important lateral bridge of tissue spanning the interval between the subscapularis anteriorly and the supraspinatus tendon superiorly. After repair of the subscapularis tendon, this lateral rotator interval tissue can greatly facilitate repair of the posterosuperior rotator cuff.

Arthroscopy↗
PubMed2004

Abrasion resistance of two types of nonabsorbable braided suture.

PURPOSE: The purpose of this study was to compare the abrasion resistance of different types of non-absorbable braided sutures under varying in vitro conditions of cyclic loading. TYPE OF STUDY: Biomechanical study. METHODS: Two types of nonabsorbable braided sutures were used in this study, No. 2 Ethibond and No. 2 Fiberwire, combined with 5 different anchors: 5.0-mm Corkscrew anchor, 5.0-mm BioCorkscrew anchor, 3.0-mm BioFastak anchor, Panalok RC anchor, and 3.5-mm Panalok anchor. Twelve tests for each construct were performed. A custom-designed testing apparatus was constructed to evaluate the abrasion resistance of sutures through an anchor eyelet. The apparatus cycled the suture through the anchor eyelet at a rate of 84 revolutions per minute and a speed of 12.5 m/min. In addition to suture type, the effect of different suture-to-anchor angles and testing conditions (dry v wet testing) were evaluated. The number of cycles to failure and the mode of failure were recorded (suture breakage v eyelet breakage). RESULTS: Results showed that under all testing conditions No. 2 Fiberwire displayed abrasion resistance superior to No. 2 Ethibond (P <.002 in all cases). The mean number of cycles to failure was 5 to 51 times greater when using No. 2 Fiberwire than when using No. 2 Ethibond. Altering the suture-to-anchor angle from 0 degree (in-line) to 45 degrees decreased the abrasion resistance of both No. 2 Ethibond (69.8 cycles +/- 26.5 cycles v 7.4 cycles +/- 3.9 cycles; P <.000004) and No. 2 Fiberwire (918.3 cycles +/- 417.4 cycles v 389.2 cycles +/- 195.7 cycles; P =.001) when using the 5.0-mm Corkscrew anchor. Fiberwire performed equally well under both dry and wet conditions (P >.05) whereas Ethibond performed better under wet conditions (P =.0002) when using the 5.0-mm BioCorkscrew anchor. When using the Panalok RC anchor (mean failure, 11.2 cycles +/- 1.3 cycles) or the 3.5-mm Panalok anchor (mean failure, 12.5 cycles +/- 2.4 cycles), constructs failed at significantly lower cycles than other comparable anchor-suture constructs (P <.00007 in all cases). In addition, although the vast majority of failure modes for the other anchor-suture constructs was by suture breakage, the Panalok RC anchor and 3.5-mm Panalok anchor consistently failed by cutting of the suture through the biodegradable eyelet. CONCLUSIONS: (1) Suture abrasion differs according to the suture type, anchor type, and testing conditions. (2) No. 2 Fiberwire showed superior resistance to abrasion when compared with No. 2 Ethibond under all conditions tested in the study. (3) The abrasion resistance of No. 2 Fiberwire is sufficiently high to eliminate, clinically, the theoretical concerns over weakening of suture from the anchor eyelet. (4) Suture eyelets formed of biodegradable materials can fail at low numbers of cycles by cutting of the suture through the biodegradable eyelet during cyclic loading. CLINICAL RELEVANCE: The study will help the surgeon to assess suture and suture anchor characteristics in order to optimize fixation of biologic tissues during surgical repair and reconstruction.

Biomechanical Phenomena↗
PubMed2004

Arthroscopic knots: determining the optimal balance of loop security and knot security.

PURPOSE: The purpose of this study was to determine the optimal knot configuration that maximized both knot and loop security when tied with 2 different types of nonabsorbable, braided suture. TYPE OF STUDY: In vitro biomechanical study. METHODS: Six commonly used arthroscopic sliding knots (Duncan loop, Nicky's knot, Tennessee slider, Roeder knot, SMC knot, Weston knot) with and without a series of 3 reversing half-hitches on alternating posts (RHAPs) as well as a static surgeon's knot were tied. Two different nonabsorbable, braided sutures were used, and a total of 7 knots were tied for each possible combination of knots and sutures, for a total of 182 knots. Each knot was tied around a 30-mm circumference post to assure a consistent loop circumference of 30 mm before "locking" the complex sliding knots by tensioning the wrapping limb of the suture. Each loop was mounted on a Material Testing System machine, and its circumference was measured at a 5-N preload to assess each knot's ability to maintain a tight suture loop without slippage (loop security). Knot security was measured as the maximum force to failure at 3 mm of crosshead displacement or suture breakage during single-pull load testing. RESULTS: The surgeon's knot provided the highest force to failure and the tightest loop circumference whether tied with No. 2 Ethibond (Ethicon, Somerville, NJ) or No. 2 Fiberwire (Arthrex, Naples, FL) suture. Among the sliding knots, the Roeder knot with 3 RHAPs showed the best balance of loop security and knot security when tied with No. 2 Ethibond or No. 2 Fiberwire. Sliding knots tied without RHAPs showed low force to failure and loose suture loops whether tied with Ethibond or Fiberwire. The addition of 3 RHAPs improved knot security and, in most cases, loop security of all the sliding knots. When tying a static surgeon's knot or a sliding knot with RHAPs, using No. 2 Fiberwire increased the force to failure over comparable knots tied with No. 2 Ethibond. All knots failed by a combination of knot slippage and suture stretch. When using No. 2 Ethibond, securing most sliding knots with 3 RHAPs or tying a surgeon's knot changed the failure mechanism from knot slippage to suture stretch, suggesting that the maximum knot holding capacity of No. 2 Ethibond had been achieved when tying these knot configurations. However, even at failure forces twice that achieved with No. 2 Ethibond, suture slippage continued to occur with sliding knots with 3 RHAPs using No. 2 Fiberwire. This indicates that the maximum knot-holding capacity of No. 2 Fiberwire had not been achieved, and that further knot configurations should be tested. CONCLUSIONS: (1) A static surgeon's knot provides the best balance of loop security and knot security within the knot configurations tested in this study. (2) A sliding knot without RHAPs has both poor loop security and knot security and should not be tied. (3) The addition of 3 RHAPs improves knot security of all sliding knots tested and improves loop security of most of the sliding knots tested. (4) The addition of 3 RHAPs improves the knot security of all sliding knots to adequately resist predicted in vivo loads. (5) The Roeder knot with 3 RHAPs provides the best balance of loop security and knot security within the sliding knot configurations tested in this study regardless of suture type. (6) Tying a surgeon's knot or a sliding knot with 3 RHAPS using No. 2 Fiberwire increases knot security over the same knot tied with No. 2 Ethibond. CLINICAL RELEVANCE: This study identifies the static and sliding configurations of commonly used arthroscopic knots in order to aid the surgeon in choosing the most biomechanically effective knot for use in arthroscopic surgery.

Arthroscopy↗
PubMed2004

Glenohumeral arthroscopy portals established using an outside-in technique: neurovascular anatomy at risk.

PURPOSE: The purpose of this study was to examine the neurovascular structures at risk during placement of glenohumeral arthroscopy portals using an outside-in technique. TYPE OF STUDY: Anatomic cadaveric study. METHODS: Five fresh-frozen cadaveric specimens were used in this study. Each shoulder was mounted on a custom-designed apparatus allowing shoulder arthroscopy in a lateral decubitus position. The following portals were established using an outside-in technique and marked using an 18-gauge spinal needle: posterior, posterolateral, anterior, 5-o'clock, anterosuperolateral, and Port of Wilmington. Each specimen was carefully dissected after the procedure, and the distance from each portal site to the adjacent relevant neurovascular structures (axillary nerve, musculocutaneous nerve, lateral cord of the brachial plexus, cephalic vein, and axillary artery) was measured using a precision caliper. RESULTS: Except for the cephalic vein, all of the neurovascular structures were more than 20 mm away from all the portals evaluated. When creating either an anterior portal or a 5-o'clock position portal, the mean distance from the portal to the cephalic vein was 18.8 mm and 9.8 mm, respectively. In one anterior portal, a direct injury to the cephalic vein occurred. CONCLUSIONS: Our study suggests that shoulder arthroscopy portals placed in an outside-in fashion are unlikely to produce neurologic injury. However, the cephalic vein is at risk during placement of an anterior or 5-o'clock position portal, although probably with minimal subsequent patient morbidity. Placing portals in an outside-in fashion guarantees the correct angle of approach, with minimal risk to adjacent neurologic structures. CLINICAL RELEVANCE: This study shows the safety of standard and accessory glenohumeral arthroscopy portals.

Anthropometry↗
PubMed2004

Surgery about the coracoid: neurovascular structures at risk.

PURPOSE: The purpose of this study was to examine the neurovascular structures at risk when performing surgery about the coracoid. TYPE OF STUDY: Anatomic cadaveric study. METHODS: Five fresh-frozen cadaveric shoulders were dissected to determine the dimensions of the coracoid and the distance from the coracoid to adjacent neurologic and vascular structures. The minimal distance from the coracoid tip to the axillary nerve, musculocutaneous nerve, the lateral cord of the brachial plexus, and the axillary artery was measured using a precision caliper. Similarly, the minimal distance from the base of the coracoid to the axillary nerve, musculocutaneous nerve, the lateral cord of the brachial plexus, and the axillary artery was measured. RESULTS: The coracoid tip was defined as that portion of the bone that was distal to the "elbow" of the coracoid. Results showed that the mean width (medial-to-lateral dimension in the plane of the subscapularis tendon) of the coracoid tip was 15.9 +/- 2.2 mm, and the mean length of the coracoid tip was 22.7 +/- 4.5 mm. The mean thickness of the coracoid tip at its midportion was 10.4 +/- 1.5 mm. The portion of the coracoid tip which was closest to the neurovascular structures was the anteromedial portion of the coracoid tip. The distance from the anteromedial portion of the coracoid tip to the axillary nerve, the musculocutaneous nerve, the lateral cord, and the axillary artery was 30.3 +/- 3.9 mm, 33.0 +/- 6.2 mm, 28.5 +/- 4.4 mm, and 36.8 +/- 6.1 mm, respectively. Similarly, the portion of the base of the coracoid that was closest to the neurovascular structures was its anteromedial portion. The shortest distance from the anteromedial aspect of the base of the coracoid to the axillary nerve, the musculocutaneous nerve, the lateral cord, and the axillary artery was 29.3 +/- 5.6 mm, 36.5 +/- 6.1 mm, 36.6 +/- 6.2 mm, and 42.7 +/- 7.3 mm, respectively. CONCLUSIONS: Procedures about the coracoid are relatively safe procedures. The lateral cord of the brachial plexus is at greatest risk during dissection about the tip of the coracoid, and the axillary nerve is at greatest risk during dissection about the base of the coracoid. The safety of arthroscopic coracoplasty or interval releases is further increased by the fact that most of the work is performed on the lateral aspect of the coracoid, which is even further away from the neurovascular structures. CLINICAL RELEVANCE: This study quantifies the relative risk of injury to neurovascular structures during arthroscopic surgery about the coracoid.

Anthropometry↗