A biomechanical comparison of repair techniques for type II SLAP lesions

Biomechanical Studies for Glenoid Based Labral Repairs With Suture Anchors Do Not Use Consistent Testing Methods: A Critical Systematic Review

PURPOSE

The purpose of this systematic review was to investigate variability in biomechanical testing protocols for laboratory-based studies using suture anchors for glenohumeral shoulder instability and SLAP lesion repair.

METHODS

A systematic review of Medline, Embase, Scopus, and Google Scholar using Covidence software was performed for all biomechanical studies investigating labral-based suture anchor repair for shoulder instability and SLAP lesions. Clinical studies, technical notes or surgical technique descriptions, or studies treating glenoid bone loss or capsulorrhaphy were excluded. Risk of bias (ROB) was assessed with the ROBINS-I tool. Study quality was assessed with the Quality Appraisal for Cadaveric Studies. Heterogeneity was assessed with the I² statistic.

RESULTS

A total of 41 studies were included. ROB was serious and critical in 27 studies, moderate in 13, and low in 1; 6 studies had high quality, 21 good quality, 10 moderate quality, 2 low quality, and 2 very low quality. Thirty-one studies used and 22 studies included cyclic loading. Angle of anchor insertion was reported by 33 studies. The force vector for displacement varied. The most common directions were perpendicular to the glenoid (n = 9), and anteroinferior or anterior (n = 8). The most common outcome measures were load to failure (n = 35), failure mode (n = 23), and stiffness (n = 21). Other outcome measures included load at displacement, displacement at failure, tensile load at displacement, translation, energy absorbed, cycles to failure, contact pressure, and elongation.

CONCLUSION

This systematic review demonstrated a clear lack of consistency in those cadaver studies that investigated biomechanical properties after surgical repair with suture anchors for shoulder instability and SLAP lesions. Testing methods between studies varied substantially with no universally applied standard for preloading, load to failure and cyclic loading protocols, insertion angles of suture anchors, or direction of loading. To allow comparability between studies standardization of testing protocols is strongly recommended.

Effects of type II SLAP lesion repair techniques on the vascular supply of the long head of the biceps tendon: a cadaveric injection study

BACKGROUND

One option for the treatment of type 2 superior labral anterior to posterior (SLAP) lesions is arthroscopic repair. However, the fact that the vascular supply of the proximal long head of the biceps tendon (LHBT) arises from the soft tissue near the SLAP repair site must also be considered. The aims of this study were to evaluate the vascular channel of the proximal long head biceps tendon and to compare potential damage to the vascular supply with alternative SLAP techniques.

METHODS

Forty-five fresh cadaveric shoulders were divided into 3 groups: 9 shoulders each for the normal group and the created SLAP group, and 27 shoulders for the repaired SLAP group. SLAP group shoulders were repaired using one of 3 techniques: 2 anchors with simple sutures, 1 anchor with double sutures, or 1 anchor with a horizontal mattress suture. India ink was then injected into the acromial branch of the thoracoacromial artery. The proximal LHBT was resected for a histologic cross-sectional study. The intratendinous vascular distance was measured and compared among the groups.

RESULTS

The vascular supply of the proximal LHBT arises from soft tissue lying anterior and dorsal to the tendon origin. In the normal shoulders, the average intratendinous vascular distance was 16.9 ± 1.5 mm (95% confidence interval: 15.8-18.1). A comparison of nonrepaired SLAPs with each of the repair techniques found that using 2 anchors with simple sutures showed no significant difference in vascular distance (P = .716), whereas the other techniques showed a significant disruption of the blood supply. The differences in vascular distance among the 3 repair techniques were statistically significant (P = .0001).

CONCLUSIONS

The main vascular supply of the proximal LHBT comes from the anterior-dorsal direction. Some SLAP repair techniques can disrupt vascularization; however, the technique using 2 anchors with simple sutures, 1 anchor 3 mm anterior to the anterior border and 1 at the posterior border of the tendon, can preserve the vascularization of the LHBT.

Biomechanical Comparison of Knotless All-Suture Anchors and Knotted All-Suture Anchors in Type II SLAP Lesions: A Cadaveric Study

PURPOSE

To compare the biomechanical performance of knotless versus knotted all-suture anchors for the repair of type II SLAP lesions with a simulated peel-back mechanism.

METHODS

Twenty paired cadaveric shoulders were used. A standardized type II SLAP repair was performed using knotless (group A) or knotted (group B) all-suture anchors. The long head of the biceps (LHB) tendon was loaded in a posterior direction to simulate the peel-back mechanism. Cyclic loading was performed followed by load-to-failure testing. Stiffness, load at 1 and 2 mm of displacement, load to repair failure, load to ultimate failure, and failure modes were assessed.

RESULTS

The mean load to repair failure was similar in groups A (179.99 ± 58.42 N) and B (167.83 ± 44.27 N, P = .530). The mean load to ultimate failure was 230 ± 95.93 N in group A and 229.48 ± 78.45 N in group B and did not differ significantly (P = .958). Stiffness (P = .980), as well as load at 1 mm (P = .721) and 2 mm (P = .849) of displacement, did not differ significantly between groups. In 16 of the 20 specimens (7 in group A and 9 in group B), ultimate failure occurred at the proximal LHB tendon. Failed occurred through slippage of the labrum in 1 specimen in each group and through anchor pullout in 2 specimens in group A.

CONCLUSIONS

Knotless and knotted all-suture anchors displayed high initial fixation strength with no significant differences between groups in type II SLAP lesions. Ultimate failure occurred predominantly as tears of the proximal LHB tendon.

CLINICAL RELEVANCE

All-suture anchors have a smaller diameter than solid anchors, can be inserted through curved guides, preserve bone stock, and facilitate postoperative imaging. There is a paucity of literature investigating the biomechanical capacities of knotless versus knotted all-suture anchors in type II SLAP repair.

Effect of Anterior Anchor on Clinical Outcomes of Type II SLAP Repairs in an Active Population

This study evaluated the role of anchor position in persistence of pain and/or revision biceps tenodesis after arthroscopic repair of type II superior labrum anterior and posterior (SLAP) lesions and assessed for patient- and injury-specific variables influencing clinical outcomes. Active-duty service members who underwent arthroscopic repair of type II SLAP lesions between March 1, 2007, and January 23, 2012, were identified. Patients with less than 2-year clinical follow-up; type I, III, and IV SLAP lesions; and primary treatment with biceps tenodesis and/or rotator cuff repair at the time of index surgery were excluded. Demographic, preoperative, and operative variables, including anchor positions, were reviewed and evaluated for association with outcomes. Total failure rate (defined as either surgical and/or clinical failure), anchor position, and return to military function were the primary outcomes of interest. Forty-nine patients underwent type II SLAP repairs with a mean follow-up of 52.3 months. Forty-eight (97.9%) were men, and mean age was 35.2 years. Eleven patients (22%) underwent subsequent subpectoral biceps tenodesis. Forty patients (82%) returned to military function, whereas 9 patients (18%) had medical discharge for significant, rate-limiting, shoulder pain. Age was a significant predictor of surgical failure. Patients with anchor position anterior to the biceps attachment had no increased risk of clinical or surgical failure compared with patients with only posterior-based anchors. Anchor placement anterior to the biceps tendon was not associated with inferior outcomes. Younger age was shown to be a poor prognostic factor in patients' ability to return to active duty. Revision with biceps tenodesis showed significant utility in achieving good clinical outcomes and return to duty in more than 90% of patients. Patient-, injury-, and surgery-specific variables need to be identified as prognostic indicators so that clinical outcomes can continue to be improved. [Orthopedics. 2019; 42(1):e32-e38.].

Bankart lesion repair: biomechanical and anatomical analysis of Mason-Allen and simple sutures in a swine model

Objective

To evaluate the labral height and pullout resistance after the repair of Bankart lesions in the glenohumeral joint of swine models, using double-loaded anchors with two suture configurations: simple and Mason-Allen.

Methods

Ten swine shoulders were used, in which Bankart lesions were created. For each specimen, the lesion was sutured randomly with Mason-Allen sutures or simple sutures. The labral height was measured before the lesion was created and after the labral repair. The specimens were submitted to a tensile test for biomechanical evaluation.

Results

In specimens submitted to simple suture (n = 5), the mean labral height observed before the lesion was 3.86 mm, and after suturing, 3.33 mm. In specimens submitted to Mason-Allen suture (n = 5), it was observed that the mean labral height before the lesion was 3.92 mm, and after suturing, 3.48 mm. When comparing the labral height after simple suture and Mason-Allen suture, no significant difference was observed. The pullout force at the end of the tensile test on specimens with single suture was 130 N, and in specimens with Mason-Allen suture, 128.6 N. No statistically significant differences were observed between the shoulders treated with single suture and Mason-Allen suture; p = 0.885.

Conclusions

Repair of Bankart lesions with Mason-Allen suture provides increased labrum height; however, it does not increase the pullout strength.

Subpectoral biceps tenodesis for the treatment of type II and IV superior labral anterior and posterior lesions

BACKGROUND

Surgical repair remains the gold standard for most type II and type IV superior labral anterior and posterior (SLAP) lesions that fail nonoperative management. However, most recently, there have been data demonstrating unacceptably high failure rates with primary repair of type II SLAP lesions. Biceps tenodesis may offer an acceptable, if not better, alternative to primary repair of SLAP lesions.

HYPOTHESIS

Subpectoral biceps tenodesis provides satisfactory, reproducible outcomes for the treatment of type II and type IV SLAP lesions.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent subpectoral biceps tenodesis and labral debridement for type II and type IV SLAP lesions by a single board-certified shoulder surgeon from 2006 to 2012 were evaluated. Exclusion criteria included those patients who underwent biceps tenodesis with an associated rotator cuff repair, anterior labral repair, or posterior labral repair. Outcome measures included the visual analog scale (VAS) for pain, the American Shoulder and Elbow Surgeons (ASES) score, and demographic data.

RESULTS

Between 2006 and 2012, a total of 36 subpectoral biceps tenodesis procedures were performed in 33 patients for type II or IV SLAP lesions. Twenty-six patients with 29 shoulder surgeries were available for follow-up. The average age was 46.7 years, with 16 male and 10 female patients participating in the study. The average follow-up was 40.17 months. There was a significant improvement in ASES and VAS scores: 48.1 and 6.4 preoperatively compared with 87.5 and 1.5 postoperatively, respectively (P < .001). There was no significant difference based on SLAP lesion type, patient age, or patient sex. Of 29 shoulders, 26 (89.66%) were able to return to the previous level of activity.

CONCLUSION

This study adds to the evolving literature supporting biceps tenodesis as a viable treatment for type II and IV SLAP lesions. Patient age had no effect on the outcomes. Based on these results, biceps tenodesis is a safe, effective, and technically straightforward alternative to primary SLAP repair in patients with type II and IV SLAP tears.

Role of the superior labrum after biceps tenodesis in glenohumeral stability

BACKGROUND

Little is known about the role that a torn superior labrum (SLAP) plays in glenohumeral stability after biceps tenodesis. This biomechanical study evaluated the contribution of a type II SLAP lesion to glenohumeral translation in the presence of biceps tenodesis. The authors hypothesize that subsequent to biceps tenodesis, a torn superior labrum does not affect glenohumeral stability and therefore does not require anatomic repair in an overhead throwing athlete.

METHODS

Baseline anterior, posterior, and abduction and maximal external rotation glenohumeral translation data were collected from 20 cadaveric shoulders. Translation testing was repeated after the creation of anterior (n = 10) and posterior (n = 10) type II SLAP lesions. Translation re-evaluation after biceps tenodesis was performed for each specimen. Finally, anatomic SLAP lesion repair and testing were performed.

RESULTS

Anterior and posterior SLAP lesions led to significant increases in glenohumeral translation in all directions (P < .0125). Biceps tenodesis showed no significance in stability compared with SLAP alone (P > .0125). Arthroscopic repair of anterior SLAP lesions did not restore anterior translation compared with the baseline state (P = .0011) but did restore posterior (P = .823) and abduction and maximal external rotation (P = .806) translations. Repair of posterior SLAP lesions demonstrated no statistical difference compared with the baseline state (P > .0125).

CONCLUSIONS

With no detrimental effect on glenohumeral stability in the presence of a SLAP lesion, biceps tenodesis may be considered a valid primary or revision surgery for patients suffering from symptomatic type II SLAP tears. However, biceps tenodesis should be considered with caution as the primary treatment of SLAP lesions in overhead throwing athletes secondary to its inability to completely restore translational stability.

Footprint contact restoration between the biceps-labrum complex and the glenoid rim in SLAP repair: a comparative cadaveric study using pressure-sensitive film

PURPOSE

To compare pressurized footprint contact and interface pressure between the biceps-labrum complex and the superior glenoid rim after SLAP repair using 3 different techniques.

METHODS

Twenty-four fresh-frozen human cadaveric shoulders were divided into 3 groups. SLAP lesions were repaired by (1) 2 single-loaded anchors in a simple suture configuration (group T), (2) a double-loaded anchor in a simple suture configuration in a V shape (group V), or (3) a double-loaded anchor by use of a hybrid simple and mattress suture configuration (group H). Pressure-sensitive film quantified pressurized contact areas and interface pressures between the biceps-labrum complex and the glenoid rim after SLAP repair.

RESULTS

Groups T and V showed significantly larger contact areas than group H (P < .0001). However, there was no significant difference between groups T and V. Despite a substantial contact area around the biceps-labrum complex in group T, there was a lack of sufficient contact area just below the biceps anchor. Group V showed a uniform contact area around the entire biceps-labrum complex, but in group H the contact area was concentrated only around the posterior superior labrum, where the simple suture was used.

CONCLUSIONS

The methods using 2 single-loaded suture anchors and using 1 double-loaded suture anchor with a simple suture configuration showed significantly larger pressurized contact areas than the method using 1 double-loaded suture anchor with both a simple and mattress suture configuration. The interface pressure was not significantly different among groups.

CLINICAL RELEVANCE

Although there have been several kinds of repair techniques and biomechanical studies for the type II SLAP lesion, there has been no study about footprint restoration on the superior glenoid rim. This study analyzed and compared the footprint contact restoration after type II SLAP repair among 3 different techniques.

The effect on external rotation of an anchor placed anterior to the biceps in type 2 SLAP repairs in a cadaveric throwing model

PURPOSE

This study examined whether there is a difference in external rotation (ER) between type 2 SLAP repairs consisting of anchors placed only posterior to the biceps insertion compared with repairs with an additional anchor placed anterior to the biceps.

METHODS

Seven cadaveric shoulders from donors with a mean age of 39.4 years were tested. Type 2 SLAP lesions were created, followed by a 3-anchor repair: a standard repair with 2 anchors posterior to the biceps plus an additional anchor anterior to the biceps. The specimens were placed on a material testing system machine and rotation was measured under a constant torque. The sutures were then removed sequentially from anterior to posterior during testing.

RESULTS

The average ER of the intact shoulder was 115.7° ± 2.6°. After SLAP tear creation and cyclic loading, the ER was 118.5° ± 2.6°, which decreased to 116.5° ± 2.6° after repair. This corresponds to a reduction of 2.0° of ER (P < .0001) with the repair. After release of the anterior anchor, the ER increased to 117.9° ± 2.6°, which corresponds to an increase in shoulder motion of 1.4° of ER (P = .0011). Additional release of the middle anchor, leaving only the posterior anchor intact, resulted in 118.0° ± 2.7° of ER, which corresponds to an increase of only 0.1° of ER (P = .7667).

CONCLUSIONS

Following type 2 SLAP repair in the cadaveric shoulder, removing the effect of the anchor anterior to the biceps resulted in a small but statistically significant increase in ER. The anterior anchor had the greatest effect on ER. The presence of 1 or 2 anchors posterior to the biceps did not have a significant effect on rotation.

CLINICAL RELEVANCE

When performing SLAP repairs on those in whom even a small loss of ER would be detrimental, such as baseball pitchers, avoidance of the use of an anchor anterior to the biceps should be considered.

Arthroscopic suture anchor capsulorrhaphy versus labral-based suture capsulorrhaphy in a cadaveric model

PURPOSE

The purpose of this study was to establish whether suture anchor capsulorrhaphy (SAC) is biomechanically superior to suture capsulorrhaphy (SC) in the management of recurrent anterior shoulder instability without a labral avulsion.

METHODS

Twelve matched pairs of shoulders were randomized to either SC or SAC. Specimens were mounted in 60° of abduction and 90° of external rotation. Testing was conducted on an MTS servohydraulic load testing device (MTS, Eden Prairie, MN). A compressive load of 22 N was applied, followed by a 2-N anterior and posterior force to establish a 0 point. Translation with 10-N anterior and posterior loads was recorded for baseline laxity measurement. Arthroscopic capsulorrhaphy was performed with either 3 solitary sutures or 3 suture anchors. Specimens were remounted and returned to the 0 point. Translation was measured with 10-N anterior and posterior loads to determine reduction in translation. Specimens were then loaded to failure to the 0 point at a rate of 0.1 mm/s.

RESULTS

Load to failure was significantly greater (P = .02) in the SC group (13.6 ± 1.0 N) versus the SAC group (20.5 ± 2.8 N). No differences were found between SC (2.7 ± 0.7 mm) and SAC (2.3 ± 0.6 mm) when we compared reduction of anterior translation with a 10-N load. The percent reduction of anterior displacement with a 10-N load was similar for the SC (49.9%) and SAC (49.6%) groups. The dominant mode of failure in the study was suture pull-through of the capsular tissue.

CONCLUSIONS

Our study indicates that labral-based SC and SAC similarly reduce anterior glenohumeral translation at low loading conditions. Load-to-failure studies indicate that SAC exhibits significantly greater resistance to translation at higher loading conditions. Our study suggests that the use of a suture anchor when one is performing a capsulorrhaphy may provide biomechanical advantage at high loading conditions.

CLINICAL RELEVANCE

Our study suggests that when one is performing capsulorrhaphy, the use of a suture anchor may provide biomechanical advantages at high loading conditions.

Restoration of labral anatomy and biomechanics after superior labral anterior-posterior repair: comparison of mattress versus simple technique

BACKGROUND

Both simple and mattress repair techniques have been utilized with success for type II superior labral anterior-posterior (SLAP) lesions; however, direct anatomic and biomechanical comparisons of these techniques have yet to be clearly demonstrated.

HYPOTHESIS

For type II SLAP lesions, the mattress suture repair technique will result in greater labral height and better position on the glenoid face and exhibit stronger biomechanical characteristics, when cyclically loaded and loaded to failure through the biceps, compared with the simple suture repair technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six matched pairs of cadaveric shoulders were dissected, and a clock face was created on the glenoid from 9 o'clock (posterior) to 3 o'clock (anterior). For the intact specimen, labral height and labral distance from the glenoid edge were measured using a MicroScribe. A SLAP lesion was then created from 10 o'clock to 2 o'clock. Lesions were repaired with two 3.0-mm BioSuture-Tak anchors placed at 11 o'clock and 1 o'clock. For each pair, a mattress repair was used for one shoulder, and a simple repair was used for the contralateral shoulder. After repair, labral height and labral distance from the glenoid edge were again measured. The specimens were then cyclically loaded and loaded to failure through the biceps using an Instron machine. A paired t test was used for statistical analysis.

RESULTS

After mattress repair, a significant increase in labral height occurred compared with intact from 2.5 ± 0.3 mm to 4.3 ± 0.3 mm at 11 o'clock (P = .013), 2.7 ± 0.5 mm to 4.2 ± 0.7 mm at 12:30 o'clock (P = .007), 3.1 ± 0.5 mm to 4.2 ± 0.7 mm at 1 o'clock (P = .006), and 2.8 ± 0.7 mm to 3.7 ± 0.8 mm at 1:30 o'clock (P = .037). There was no significant difference in labral height between the intact condition and after simple repair at any clock face position. Labral height was significantly increased in the mattress repairs compared with simple repairs at 11 o'clock (mean difference, 2.0 mm; P = .008) and 12:30 o'clock (mean difference, 1.3 mm; P = .044). Labral distance from the glenoid edge was not significantly different between techniques. No difference was observed between the mattress and simple repair techniques for all biomechanical parameters, except the simple technique had a higher load and energy absorbed at 2-mm displacement.

CONCLUSION

The mattress technique created a greater labral height while maintaining similar biomechanical characteristics compared with the simple repair, with the exception of load and energy absorbed at 2-mm displacement, which was increased for the simple technique.

CLINICAL RELEVANCE

Mattress repair for type II SLAP lesions creates a higher labral bumper compared with simple repairs, while both techniques resulted in similar biomechanical characteristics.

The effect of age on the outcomes of arthroscopic repair of type II superior labral anterior and posterior lesions

BACKGROUND

The majority of clinical outcome studies of type II superior labral anterior and posterior (SLAP) repair assess patients younger than age 40. Biceps tenotomy or tenodesis is often recommended for patients older than age 40 with superior labrum-biceps complex injury.

HYPOTHESIS

There is no difference in patient clinical outcomes comparing arthroscopic type II SLAP repair in patients younger or older than age 40.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Fifty-two patients stratified to groups younger than age 40 (21 patients; average age, 32.9 years) and older than age 40 (31 patients; average age, 55.1 years) were identified at a minimum 2-year follow-up (average, 28 months) after type II SLAP repair by a single surgeon using suture anchors. Outcome scores included American Shoulder and Elbow Society scores (ASES), Short Form-12 scores, Simple Shoulder Test scores, and visual analog pain scale.

RESULTS

At follow-up, there was no statistical difference in visual analog pain scale (P = .16), ASES scores (P = .07), Simple Shoulder Test scores (P =.41), Short Form-12 testing, or range of motion testing. Patients older than age 40 noted their shoulder to be 87% of normal; 26 of 31 (84%) were satisfied to completely satisfied, and 28 of 31 (90%) would have the surgery again. Patients younger than 40 noted their shoulder to be approximately 89% of normal; 20 of 21 (95%) were satisfied to completely satisfied, and 18 of 21 (86%) would have the same procedure performed again.

CONCLUSION

Our findings support that arthroscopic treatment of isolated type II SLAP repair using suture anchors can yield good to excellent results in patients older and younger than age 40. We found no statistically significant difference in patient outcome scores, satisfaction levels, or willingness to have the same procedure again when comparing arthroscopic SLAP repair in patients younger or older than age 40.

Strength of single- versus double-anchor repair of type II SLAP lesions: a cadaveric study

PURPOSE

This study was designed to examine whether there was a difference in pullout strength along with the mode of failure between 1 suture anchor and 2 suture anchors.

METHODS

Ten matched pairs of cadaveric shoulders were used in the study. A type II SLAP lesion, according to the classification of Snyder et al., was created. In 10 shoulders 1 anchor with 2 sutures was used to repair the lesion. In the other group of 10 matched shoulders, fixation was done with 2 anchors, with each anchor having only 1 suture. An Instron servohydraulic test machine (Instron, Canton, MA) was used to pull the long head of the biceps tendon until failure occurred.

RESULTS

The single-anchor group failed at a mean load of 278.5 +/- 101.5 N. The double-anchor group failed at 242.5 +/- 96.5 N. A paired 2-sample Student t test showed that there was no significant difference in pullout strength between the 2 groups (P = .090). The most common mode of failure was soft-tissue failure. There was 1 anchor pullout in the single-anchor group and 2 anchor pullouts in the double-anchor group.

CONCLUSIONS

The results of this study imply that using 1 anchor with 2 sutures is biomechanically equivalent to 2 anchors with 1 suture each for repairing type II SLAP lesions.

CLINICAL RELEVANCE

Using 1 suture anchor is sufficient to repair a type II SLAP lesion.

Biomechanical comparison of knotless anchor repair versus simple suture repair for type II SLAP lesions

PURPOSE

The purpose of this study was to evaluate glenohumeral motion after knotless anchor repair of type II SLAP lesions versus repair with simple suture arthroscopic knot-tying techniques and to compare the initial fixation strength of the 2 repair techniques.

METHODS

Six matched-pair cadaveric shoulders were tested in an uninjured condition, after creation of a type II SLAP tear, and after repair with either a knotless repair with two 3.5-mm Bio-PushLock anchors (Arthrex, Naples, FL) or a simple suture repair with two 3.0-mm Bio-SutureTak anchors (Arthrex) placed anterior and posterior to the biceps tendon. Glenohumeral rotation, translation, and kinematics were measured. The SLAP repairs were then loaded to failure perpendicular to the glenoid face.

RESULTS

Glenohumeral rotation increased after creation of a type II SLAP lesion and was restored to the intact state after both repairs. There was no significant difference in glenohumeral translation or kinematics with SLAP lesion or either repair technique. There was no significant difference between stiffness, yield load, or ultimate load of the 2 repairs. Simple suture repairs failed most commonly by knot breakage, and knotless repairs failed by suture slippage around the anchor.

CONCLUSIONS

Knotless anchor repairs of type II SLAP lesions restore glenohumeral rotation as well as simple suture arthroscopic repair techniques without overconstraining the shoulder. In addition, the initial fixation strength of knotless anchor repairs of type II SLAP lesions is similar to that of simple suture repairs.

CLINICAL RELEVANCE

Knotless anchor repairs of type II SLAP lesions restore capsulolabral anatomy without overconstraining the shoulder.

Biomechanical comparison of a knotless suture anchor with standard suture anchor in the repair of type II SLAP tears

PURPOSE

To compare the biomechanical strength of knotless suture anchors and standard suture anchors in the repair of type II SLAP tears.

METHODS

Five pairs of cadaveric shoulders (10 shoulders) were dissected free of soft tissue except for the glenoid labrum and long head of the biceps tendon. Type II SLAP tears were created and repaired with 1 of 2 anchors: the Mitek Lupine suture anchor or the Mitek Bioknotless suture anchor (DePuy Mitek, Raynham, MA). All specimens were preloaded to 10 N, and loaded for 25 cycles in 10 N increments to a maximum of 200 N. If specimens were still intact after 200 N, they were loaded to ultimate failure. The load at which 2 mm of gapping occurred, load to ultimate failure, mode of failure, and the number of cycles to failure were compared using the Wilcoxon signed-rank test.

RESULTS

Load to 2-mm gapping was lower (P = .042) for knotless anchors (70 N) versus knotted anchors (104 N), with similar differences for ultimate failure (74 N v 132 N; P = .043), cycles to 2-mm gapping (133 v 219 cycles; P = .042), and cycles to failure (143 v 297; P = .043). Eight of 10 specimens failed at the soft tissue interface (4 knotless, 4 knotted) and 2 failed by anchor pullout (1 knotted, 1 knotless).

CONCLUSIONS

The results of this study suggest that repair of a type II SLAP with a Mitek knotted suture anchor and mattress suture configuration through the biceps anchor is stronger than repair with a Mitek knotless suture anchor. The most likely method of repair failure was at the suture-soft tissue interface regardless of the type of anchor used. The application of a suture anchor that requires arthroscopic knot tying may be preferable to a knotless anchor for the surgical repair of type II SLAP tears.

CLINICAL RELEVANCE

Repair of type II SLAP tears with knotless suture anchors may allow for the avoidance of arthroscopic knot tying but is weaker than repair with standard suture anchors.

A biomechanical comparison of two suture anchor configurations for the repair of type II SLAP lesions subjected to a peel-back mechanism of failure

PURPOSE

The purpose of this study was to biomechanically compare 2 different suture anchor configurations in the repair of type II SLAP lesions.

METHODS

Standardized type II SLAP lesions were created in 8 matched pairs of cadaveric shoulders. Two different suture anchor configurations were used to repair the type II SLAP lesions. Group 1 SLAP lesions were repaired with 1 suture anchor placed at the anterior border and a second suture anchor placed at the posterior border of the biceps tendon. Group 2 SLAP lesions were repaired with 2 suture anchors placed posterior to the biceps tendon. Biomechanical testing was conducted in 1 direction. A posterior-directed force, in the plane of the glenoid, simulated the peel-back mechanism that occurs during the late cocking phase of throwing. Biceps-labral complex displacement from the glenoid was measured with 2 miniature displacement transducers. Repair failure (2 mm of posterior labral displacement), ultimate failure, and construct stiffness were measured for each specimen.

RESULTS

The mean load to repair failure was 43.66 N in group 1 and 40.70 N in group 2. The mean load to ultimate failure was 156.28 N in group 1 and 162.06 N in group 2. The mean construct stiffness was 25.91 N/mm in group 1 and 30.28 N/mm in group 2. The differences between the 2 groups were not statistically significant in terms of repair failure, ultimate failure, and construct stiffness.

CONCLUSIONS

When repaired type II SLAP lesions were subjected to a posterior vector load to simulate the peel-back mechanism, the 2 suture anchor configurations were biomechanically equivalent.

CLINICAL RELEVANCE

Placement of an anterior suture anchor could, theoretically, tension the anterior capsulolabral structures via the superior and middle glenohumeral ligaments to the superior labrum. The results of this study suggest that there is no biomechanical advantage to placing an anterior suture anchor and so the use of 2 posterior suture anchors may be preferable in the repair of type II SLAP lesions.

A biomechanical comparison of repair techniques in posterior type II superior labral anterior and posterior (SLAP) lesions

The purpose of this study was to compare the 3 different fixation methods of posterior type superior labral anterior posterior (SLAP) II lesion. Fifteen cadavers were randomly divided into 3 groups to compare the initial strength of 3 different fixation methods in posterior type II SLAP lesions. Group I used 1 anchor for 1-point fixation with a conventional simple suture; group II used 1 anchor passing both limbs through the posterior-superior labrum in a mattress fashion; and group III used 2 anchors for 2-point fixation with conventional simple sutures. Repair failure (2 mm permanent displacement of repaired site) and ultimate failure were measured. The mean load to (clinical) failure was 156 +/- 22 N in group I, 117 +/- 33 N in group II, and 161 +/- 44 N in group III. The mean load to ultimate failure was 198 +/- 6 N in group I, 189 +/- 23 N in group II, and 179 +/- 22 N in group III. The specimen stiffness was equivalent among groups. In mode of failure, clinical failure (more than 2 mm separations) first occurred between the markers on the biceps tendon just above (A) and below (B) compared to other markers, and ultimate failure occurred at the labral-implant interface. A single simple suture anchor repair in posterior type II SLAP seems sufficient to withstand the initial load without clinical failure. A mattress suture, although it anchors the biceps root, seems to be inferior than simple suture technique.

Isolated and combined Type II SLAP repairs in a military population

The study compares the clinical results of isolated arthroscopic repair of Type II SLAP tears with those of combined treatment for Type II SLAP and other associated shoulder conditions. The population was composed of 36 aged-matched active duty males with a mean age of 31.6 years (range 22-41 years); mean follow-up was 29.1 months (range 24-42 months). Eighteen subjects in Group I had isolated Type II SLAP tears. Eighteen subjects in Group II had Type II SLAP tear and concomitant ipsilateral shoulder conditions, including subacromial impingement in six patients, acromioclavicular arthrosis in three patients, subacromial impingement and acromioclavicular arthrosis in four patients, spinoglenoid cyst in four patients, and intra-articular loose bodies in one patient. Arthroscopic SLAP repair was performed with biodegradable suture anchors. Subacromial decompression and spinoglenoid cyst decompression were performed arthroscopically. Distal claviculectomy was performed in open fashion. Loose bodies were removed arthroscopically. At minimum 2-year follow-up, the mean UCLA score for Group I (30.2 +/- 3.0 points) was not significantly different from Group II (30.8 +/- 2.0 points) (P = 0.48). The mean post-operative ASES score for Group I (84.1 +/- 13.4 points) was significantly lower than for Group II (91.8 +/- 5.4 points) (P < 0.04). The mean VAS pain score for Group I (1.6 +/- 1.3 points) was significantly higher than for Group II (0.7 +/- 0.7 points) (P < 0.02). Seventeen of 18 patients (94%) in each group returned to full duty. In a population of active duty males, arthroscopic repair of isolated Type II SLAP had comparable results with a cohort of Type II SLAP repairs treated in combination with other shoulder conditions, with the combined treatment group having significantly better results in two of three parameters measured. Return to duty rates were identical. Therefore, concurrent treatment of other associated extra-articular shoulder conditions improves the overall success of SLAP repair and the presence of these other conditions should be recognized and treated along with the SLAP tears in order to maximize clinical results.

Arthroscopic superior labrum anterior-posterior repair in military patients

The purpose of this retrospective study was to determine the efficacy of arthroscopic superior labrum anterior-posterior (SLAP) repair in a military population. In this study, 27 patients (of 30 consecutive patients) who had suture anchor repair of a type II SLAP lesion were evaluated at a mean of 30.5 months postoperatively. Fifteen patients had isolated tears, whereas twelve also had a concomitant diagnosis. At follow-up, the overall mean American Shoulder and Elbow Surgeons score was 86.9 points and the mean University of California, Los Angeles score was 30.4 points. The results were excellent in 4 patients, good in 20, and fair in 3. Of the patients, 96% returned to full duty (mean, 4.4 months). Patients treated for concomitant diagnoses and a SLAP tear had significantly higher American Shoulder and Elbow Surgeons scores and tended to have higher University of California, Los Angeles scores than those treated for an isolated SLAP tear. The findings indicate that arthroscopic SLAP repair in military patients results in a high rate of return to duty. The results suggest that concomitant shoulder pathology should be treated at the time of SLAP repair.

[SLAP lesions: treatment.]

The advent of shoulder arthroscopy, as well as our improved understanding of shoulder anatomy and biomechanics, has led to the identification of previously undiagnosed lesions involving the superior labrum and biceps tendon anchor. Although the history and physical examinations as well as improved imaging modalities (arthro-MRI, arthro-CT) are extremely important in understanding the pathology, the definitive diagnosis of superior labrum anterior to posterior (SLAP) lesions is accomplished through diagnostic arthroscopy. Treatment of these lesions is directed according to the type of SLAP lesion. Generally, type I did not need any treatment, type III are debrided, whereas type II and many type IV lesions are repaired. The purpose of this article is to review the anatomy, classification, diagnosis and current treatment recommendations of SLAP lesions.

Biomechanical comparison of 3 suture anchor configurations for repair of type II SLAP lesions

PURPOSE

Our purpose was to compare 3 commonly used suture anchor configurations for repair of type II SLAP lesions.

METHODS

Biomechanical testing was performed on 3 groups of 7 cadaveric shoulders by use of an optical linear strain measurement system. Standardized type II SLAP lesions were created and repaired via 3 suture anchor configurations: (1) a single simple suture anterior to the biceps; (2) two simple sutures, one anterior and one posterior to the biceps; and (3) a single mattress suture through the biceps anchor. Cyclic traction was applied to the biceps tendon, and strain failure (defined as 2 mm of permanent displacement), yield, and pullout loads were measured.

RESULTS

The mean load to strain failure was 63 N in group 1, 70 N in group 2, and 106 N in group 3. The mean load to ultimate failure was 140 N in group 1, 194 N in group 2, and 194 N in group 3. Strain failure load was significantly higher in the mattress suture group than in either of the other two groups (P < .05). Groups 2 and 3 both had a significantly higher load to ultimate failure than group 1.

CONCLUSIONS

When type II SLAP lesions were subjected to cyclic traction, the load to strain failure was greater with a single anchor and mattress suture than with one or two anchors with simple sutures around the labrum. Fixation with two simple sutures appears to provide intermediate load to strain failure.

CLINICAL RELEVANCE

The results of this study suggest that a single anchor with a mattress suture may be a biomechanically advantageous construct for the repair of type II SLAP lesions.

Suture anchors and tacks for shoulder surgery, part 1: biology and biomechanics

The development and successful clinical application of suture anchors and tacks have revolutionized the surgeon's ability to secure soft tissues to bone via open or arthroscopic surgical techniques. When used carefully and with proper technique, these devices provide viable options for the repair and reconstruction of many intra-articular and extra-articular abnormalities in the shoulder, including rotator cuff tears, shoulder instability, and biceps lesions that require labrum repair or biceps tendon tenodesis. Like many technologies, however, the successful application of these devices requires an understanding of the biology and biomechanics that affect their use in the shoulder as well as knowledge of the factors that can affect subsequent clinical outcomes, including complications.