Biomechanical comparison of open Bankart repair vs. conjoint tendon transfer in a 10% anterior glenoid bone loss shoulder instability model

BACKGROUND

The treatment of shoulder instability in patients with subcritical glenoid bone loss poses a difficult problem for surgeons as new evidence supports a higher failure rate when a standard arthroscopic Bankart repair is used. The purpose of this study was to compare a conjoint tendon transfer (soft-tissue Bristow) to an open Bankart repair in a cadaveric instability model of 10% glenoid bone loss.

METHODS

Eight cadaveric shoulders were tested using a custom testing system that allows for a 6-degree-of-freedom positioning of the glenohumeral joint. The rotator cuff muscles were loaded to simulate physiologic muscle conditions. Four conditions were tested: (1) intact, (2) Bankart lesion with 10% bone loss, (3) conjoint tendon transfer, and (4) open Bankart repair. Range of motion, glenohumeral kinematics, and anterior-inferior translation at 60° of external rotation with 20 N, 30 N, and 40 N were measured in the scapular and coronal planes. Glenohumeral joint translational stiffness was calculated as the linear fit of the translational force-displacement curve. Force to anterior-inferior dislocation was also measured in the coronal plane. Repeated measures analysis of variance with a Bonferroni correction was used for statistical analysis.

RESULTS

A Bankart lesion with 10% bone loss increased the range of motion in both the scapular (P = .001) and coronal planes (P = .001). The conjoint tendon transfer had a minimal effect on the range of motion (vs. intact P = .019, .002), but the Bankart repair decreased the range of motion to intact (P = .9, .4). There was a significant decrease in glenohumeral joint translational stiffness for the Bankart lesion compared with intact in the coronal plane (P = .021). The conjoint tendon transfer significantly increased stiffness in the scapular plane (P = .034), and the Bankart repair increased stiffness in the coronal plane (P = .037) compared with the Bankart lesion. The conjoint tendon transfer shifted the humeral head posteriorly at 60° and 90° of external rotation in the scapular plane. The Bankart repair shifted the head posteriorly in maximum external rotation in the coronal plane. There was no significant difference in force to dislocation between the Bankart repair (75.8 ± 6.6 N) and the conjoint tendon transfer (66.5 ± 4.4 N) (P = .151).

CONCLUSION

In the setting of subcritical bone loss, both the open Bankart repair and conjoint tendon transfer are biomechanically viable options for the treatment of anterior shoulder instability; further studies are needed to extrapolate these data to the clinical setting.

Management of Hand and Wrist Injuries in NCAA Division I Football Players From a Single Institution: Factors Associated With Epidemiology, Surgical Intervention, and Return to Play

Background

Upper extremity injuries account for approximately 16.9% of football injuries in the National Collegiate Athletic Association (NCAA).

Purpose

To determine the epidemiology, management, and outcomes of hand/wrist injuries in collegiate football athletes so as to identify factors associated with surgical intervention and delayed return to play (RTP).

Study Design

Descriptive epidemiology study.

Methods

We retrospectively reviewed hand/wrist injuries that occurred within a single NCAA Division I football team from January 1, 2003, to December 31, 2020. Data analyzed included player position, college seniority, injury characteristics, injury management, surgical procedures performed, and timing of RTP. A univariate analysis was performed to identify factors associated with increased risk for surgical intervention and delayed (>21 days) RTP after hand and wrist injury in this cohort.

Results

Overall, 124 patients with 168 hand/wrist injuries were identified (9.9 wrist/hand injuries per year). Sprain of the thumb metacarpophalangeal (MCP) joint ulnar collateral ligament (UCL) was the most common diagnosis (19.6%). Surgery was required in 22% of injuries, with injury of the UCL of the thumb MCP joint (8/37) being the most common indication. Injuries occurring during competitive games (odds ratio = 4.29; 95% CI, 1.2-15.9) were associated with an increased risk for surgery. Most (70%) injuries did not lead to time missed from football, whereas the remaining 30% resulted in an average of 33 ± 36 days missed.

Conclusion

Over 17 athletic seasons, the annual incidence of hand and wrist injury in these NCAA Division I football players was 9.9 injuries per year, with 22% requiring surgical treatment. Injury to the UCL of the thumb MCP joint was the most common injury and indication for surgery, and 30% of injuries resulted in approximately 1 month lost. Injuries sustained in games were associated with operative management and delayed RTP.

Superior Capsule Reconstruction With Fascia Lata Allograft Has Initial Stiffness and Ultimate Load Comparable to the Native Shoulder Superior Capsule: A Cadaveric Biomechanical Study

PURPOSE

The purpose of this study was to compare the biomechanical characteristics of a fascia lata superior capsule reconstruction (FL-SCR) to the native superior capsule.

METHODS

The native superior capsule of 8 cadaveric shoulders was tested with cyclic loading from 10 to 50 N for 30 cycles in 20° of glenohumeral abduction followed by load to failure at 60 mm/min. Following native superior capsule testing, FL-SCR was performed, which was tested as described for the native capsule. Paired t test was used for statistical analyses with P < .05 for significance.

RESULTS

The stiffness for cycle 1 to 50 N was significantly higher for the native superior capsule compared to the FL-SCR (P = .001). By cycle 30, the stiffness between the two was not statistically different (P = .734). During load to failure, the initial stiffness to 2 mm for the FL-SCR and the native superior capsule was not statistically different (P = .262). The linear stiffness and yield load of the native superior capsule were significantly greater than that of the FL-SCR (94.5 vs 28.0 N/mm, P = .013; 386.9 vs 123.8 N, P = .029). There was no significant difference in ultimate load between the native superior capsule and the FL-SCR (444.9 vs 369.0 N, P = .413).

CONCLUSIONS

FL-SCR has initial stiffness and ultimate load similar to the native superior capsule.

CLINICAL RELEVANCE

The biomechanical properties of FL allograft make it an appealing option as a graft choice for superior capsule reconstruction.

Off-Season Arthroscopic Partial Meniscectomy in National Collegiate Athletic Association Division I Football Players Has a Longer Return to Sport Time than In-Season Surgery

Purpose

To report the outcomes of routine arthroscopic meniscectomy in National Collegiate Athletic Association (NCAA) Division I Football players.

Methods

NCAA athletes who underwent arthroscopic meniscectomy over 5 years were included. Players who had incomplete data, previous knee surgery, ligamentous injury, and/or microfractures were excluded. Data collected were player position, timing of surgery, procedures performed, return to play (RTP) rate and time, and postoperative performance. Continuous variables were analyzed with Student t-tests or a one-way analysis of variance.

Results

Thirty-six athletes (38 knees) who underwent arthroscopic partial meniscectomy (31 lateral, 7 medial) were included. The mean RTP time was 71 ± 39 days. The mean RTP time in athletes who underwent in-season surgery) was significantly shorter than the RTP in athletes who had off-season surgery (58 ± 41 days vs 85 ± 33 days, P < .05). The mean RTP in 29 athletes (31 knees) with lateral meniscectomy was similar to the 7 athletes (7 knees) who had medial meniscectomy (70 ± 36 vs 77 ± 56, P = .6803). The mean RTP time was similar between football players who underwent isolated lateral meniscectomy and those who had lateral meniscectomy with chondroplasty (61 ± 36 days vs 75±41 days, P = .32). Athletes played an average of 7.7 ± 4.9 games the season they returned; position category and anatomical compartment of the knee lesion had no bearing on number of games played (P = .1864 and P = .425).

Conclusions

NCAA Division 1 football players who underwent arthroscopic partial meniscectomy RTP at approximately 2.5 months' postoperatively. Athletes who underwent off-season surgery had longer RTP time compared with those who underwent in-season surgery. RTP time and performance after surgery did not differ based on player position, anatomical location of the lesions, or chondroplasty at the time of meniscectomy.

Level of Evidence

Level IV, therapeutic case series.

Human Dermal Allograft Superior Capsule Reconstruction With Graft Length Determined at Glenohumeral Abduction Angles of 20° and 40° Decreases Joint Translation and Subacromial Pressure Without Compromising Range of Motion: A Cadaveric Biomechanical Study

PURPOSE

To compare the biomechanical effects of superior capsule reconstruction (SCR) graft fixation length determined at 20° and 40° of glenohumeral (GH) abduction.

METHODS

Humeral translation, rotational range of motion (ROM), and subacromial contact pressure were quantified at 0°, 30°, and 60° of GH abduction in the scapular plane in 6 cadaveric shoulders for the following states: intact, massive rotator cuff tear, SCR with dermal allograft fixed at 20° of GH abduction (SCR 20), and SCR with dermal allograft fixed at 40° of GH abduction (SCR 40). Statistical analysis was conducted using a repeated-measures analysis of variance and a paired t test (P < .05).

RESULTS

A massive cuff tear significantly increased total ROM compared with the intact state at 0° and 60° of abduction. SCR 20 or SCR 40 did not affect ROM. Compared with the intact state, the massive cuff tear model significantly increased superior translation by an average of 4.6 ± 0.5 mm in 9 of 12 positions (P ≤ .002). Both SCR 20 and SCR 40 reduced superior translation compared with the massive cuff tear model (P < .05); however, SCR 40 significantly decreased superior translation compared with SCR 20 at 0° of abduction (P ≤ .046). Peak subacromial pressure for the massive cuff tear model increased by an average of 486.8 ± 233.9 kPa relative to the intact state in 5 of 12 positions (P ≤ .037). SCR 20 reduced peak subacromial pressure in 2 of 12 positions (P ≤ .012), whereas SCR 40 achieved this in 6 of 12 positions (P ≤ .024).

CONCLUSIONS

SCR with dermal allograft fixed at 20° or 40° of GH abduction decreases GH translation and subacromial pressure without decreasing ROM.

CLINICAL RELEVANCE

With an increasing abduction angle for graft fixation, the medial-to-lateral graft length is decreased and the graft tension is effectively increased. Surgeons may increase shoulder stability without restricting ROM by fixing the graft at higher abduction angles. However, surgeons should remain cognizant of potential graft failure due to increased tension.

Consensus statement on the treatment of massive irreparable rotator cuff tears: a Delphi approach by the Neer Circle of the American Shoulder and Elbow Surgeons

BACKGROUND

Management of massive irreparable rotator cuff tears (MIRCTs) remains controversial owing to variability in patient features and outcomes contributing to a lack of unanimity in treatment recommendations. The purpose of this study was to implement the Delphi process using experts from the Neer Circle of the American Shoulder and Elbow Surgeons to determine areas of consensus regarding treatment options for a variety of MIRCTs.

METHODS

A panel of 120 shoulder surgeons were sent a survey regarding MIRCT treatments including arthroscopic débridement and partial cuff repair, graft augmentation, reverse shoulder arthroplasty (RSA), superior capsular reconstruction (SCR), and tendon transfer. An iterative Delphi process was then conducted with a first-round questionnaire consisting of 13 patient factors with the option for open-ended responses to identify important features influencing the treatment of MIRCTs. The second-round survey sought to determine the importance of patient factors related to the 6 included treatment options. A third-round survey asked participants to classify treatment options for 60 MIRCT patient scenarios as either preferred treatment, acceptable treatment, not acceptable/contraindicated, or unsure/no opinion. Patient scenarios were declared to achieve consensus for the preferred and not acceptable/contraindicated categories when at least 80% of the survey respondents agreed on a response, and a 90% threshold was required for the acceptable treatment category, defined by an acceptable treatment or preferred treatment response.

RESULTS

Seventy-two members agreed to participate and were deemed to have the requisite expertise to contribute based on their survey responses regarding clinical practice and patient volume. There were 20 clinical scenarios that reached 90% consensus as an acceptable treatment, with RSA selected for 18 scenarios and arthroscopic débridement and/or partial repair selected for 2. RSA was selected as the singular preferred treatment option in 8 scenarios. Not acceptable/contraindicated treatment options reached consensus in 8 scenarios, of which, 4 related to SCR, 3 related to RSA, and 1 related to partial repair with graft augmentation.

CONCLUSION

This Delphi process exhibited significant consensus regarding RSA as a preferred treatment strategy in older patients with pseudoparesis, an irreparable subscapularis, and dynamic instability. In addition, the process identified certain unacceptable treatments for MIRCTs such as SCR in older patients with pseudoparesis and an irreparable subscapularis or RSA in young patients with an intact or reparable subscapularis without pseudoparesis or dynamic instability. The publication of these scenarios and areas of consensus may serve as a useful guide for practitioners in the management of MIRCTs.

Superior Capsular Reconstruction of the Shoulder

For irreparable rotator cuff tears, superior capsular reconstruction (SCR) has become an option for restoring glenohumeral joint stability and reversing proximal humeral migration. Signs of irreparable rotator cuff tears include pain from subacromial impingement, muscle weakness, and pseudoparalysis. In biomechanical studies, Mihata et al. showed SCR with fascia lata graft and side-to-side suturing to remaining infraspinatus tendon restored superior stability of the shoulder joint. Adding acromioplasty decreased the subacromial contact area without altering the humeral head position, superior translation, or subacromial peak contact pressure. The same research group showed that using an 8-mm thick fascia lata graft attached at 15° to 45° of shoulder abduction optimized superior stability of the shoulder joint. Adams et al. performed SCR using a dermal allograft and found that greater glenohumeral abduction angle (60°) decreased applied deltoid force. SCR can be performed with the patient in the lateral decubitus or beach chair position. Arthroscopic exploration, debridement, and infraspinatus and supraspinatus repair attempt is completed before proceeding with SCR. To restore the superior capsule of the shoulder, the graft (fascia lata autograft, dermal allograft) can be attached to the superior glenoid medially and the rotator cuff footprint on the greater tuberosity of the humerus laterally, after debriding bone to enhance healing. SCR with side-to-side suturing to the remnant rotator cuff yields promising clinical results. Using a fascia lata autograft, Mihata et al. showed a reversal of pseudoparalysis in 93% to 96% of patients and mean active elevation, external rotation, and acromiohumeral distance on radiography all improved. Using a dermal allograft and a unique graft delivery technique, Burkhart et al. reversed pseudoparalysis in 9 of 10 patients and 70% of patients had completely intact grafts. Recommendations for rehabilitation and return to activity vary, but adequate time for graft healing is recommended.

Load-to-failure characteristics of patellar tendon allograft superior capsule reconstruction compared with the native superior capsule

Background

The potential use of a patellar tendon allograft for superior capsular reconstruction has been demonstrated biomechanically; however, there are concerns regarding compromised fixation strength owing to the longitudinal orientation of the fibers in the patellar tendon. Therefore, the purpose of this study was to compare the fixation strength of superior capsule reconstruction using a patellar tendon allograft to the intact superior capsule.

Methods

The structural properties of the intact native superior capsule (NSC) followed by superior capsular reconstruction using a patellar tendon allograft (PT-SCR) were tested in eight cadaveric specimens. The scapula and humerus were potted and mounted onto an Instron testing machine in 20 degrees of glenohumeral abduction. Humeral rotation was set to achieve uniform loading across the reconstruction. Specimens were preloaded to 10 N followed by cyclic loading from 10 N to 50 N for 30 cycles, then load to failure at a rate of 60 mm/min. Video digitizing software was used to quantify the regional deformation characteristics.

Results

During cyclic loading, there was no difference found in stiffness between PT-SCR and NSC (cycle 1 - PT-SCR: 12.9 ± 3.6 N/mm vs. NSC: 22.5 ± 1.6 N/mm; P = .055 and cycle 30 - PT-SCR: 27.3 ± 1.4 N/mm vs. NSC: 25.4 ± 1.7 N/mm; P = .510). Displacement at the yield load was not significantly different between the two groups (PT-SCR: 7.0 ± 1.0 mm vs. NSC: 6.5 ± 0.3 mm; P = .636); however, at the ultimate load, there was a difference in displacement (PT-SCR: 20.7 ± 1.1 mm vs. NSC: 8.1 ± 0.5 mm; P < .001). There was a significant difference at both the yield load (PT-SCR: 71.4 ± 2.2 N vs. NSC: 331.6 ± 56.6 N; P = .004) and the ultimate load (PT-SCR: 217.1 ± 26.9 N vs. NSC: 397.7 ± 62.4 N; P = .019). At the yield load, there was a difference found in the energy absorbed (PT-SCR: 84.4 ± 8.9 N-mm vs. NSC: 722.6 ± 156.8 N-mm; P = .005), but no difference in energy absorbed was found at the ultimate load.

Conclusions

PT-SCR resulted in similar stiffness to NSC at lower loads, yield displacement, and energy absorbed to ultimate load. The ultimate load of the PT-SCR was approximately 54% of the NSC, which is comparable with the percent of the ultimate load in rotator cuff repair and the intact supraspinatus at time zero.

Injury Epidemiology and Time Lost From Participation in Women's NCAA Division I Indoor Versus Beach Volleyball Players

Background:

Beach volleyball officially became a National Collegiate Athletic Association (NCAA) Division I sport in 2015-2016. Few studies have examined the epidemiology of injuries in indoor versus beach volleyball in NCAA Division I athletes.

Purpose:

To compare the epidemiology of injuries and time lost from participation between female NCAA Division I athletes who participate in indoor versus beach volleyball.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Injury surveillance data (2003-2020) were obtained using an institutional database for all NCAA Division I women’s beach or indoor volleyball athletes. The total injury rate was expressed per 1000 hours played. The injury rate per body site was calculated by dividing the number of injuries in each body region by the total number of injuries. The frequency of injury per body site was also expressed as number of injuries per 1000 hours of practice or number of injuries per 1000 hours of game. The injury rate (total and per body site) and time lost from participation were compared between indoor and beach volleyball athletes.

Results:

Participants were 161 female NCAA Division I volleyball athletes (53 beach volleyball and 108 indoor volleyball athletes). In total, 974 injuries were recorded: 170 in beach volleyball and 804 in indoor volleyball. The injury rates for beach versus indoor volleyball were 1.8 versus 5.3 injuries per 1000 hours played (P < .0001). Indoor volleyball athletes had significantly higher injury rates compared with beach volleyball players for concussion (7.5% vs 6.5%; P < .0001) and knee injury (16.7% vs 7.6%; P = .0004); however, the rate of abdominal muscle injury was significantly higher in beach versus indoor volleyball (11.8% vs 4.7%; P = .0008). Time lost from sport participation was significantly longer in beach versus indoor volleyball for knee (24 vs 11 days; P = .047), low back (25 vs 17 days; P = .0009), and shoulder (52 vs 28 days; P = .001) injuries.

Conclusion:

Based on this study, injury was more likely to occur in indoor compared with beach volleyball. Sport-related concussion and knee injuries were more common in indoor volleyball, but the rate of abdominal muscle injury was higher in beach volleyball. Beach volleyball players needed longer time to recover after injuries to the knee, low back, and shoulder.

Superior Capsule Reconstruction Using Fascia Lata Allograft Compared With Double- and Single-Layer Dermal Allograft: A Biomechanical Study

PURPOSE

To biomechanically characterize superior capsule reconstruction (SCR) using fascia lata allograft, double-layer dermal allograft, and single-layer dermal allograft for a clinically relevant massive irreparable rotator cuff tear involving the entire supraspinatus and 50% of the infraspinatus tendons.

METHODS

Eight cadaveric specimens were tested in 0°, 30°, and 60° abduction for (1) intact, (2) massive rotator cuff tear, (3) SCR using fascia lata, (4) SCR using double-layer dermis, and (5) SCR using single-layer dermis. Superior translation and subacromial contact pressure were measured. Statistical analysis was conducted using repeated measures ANOVA or paired t test with P < .05.

RESULTS

Massive rotator cuff tear significantly increased superior translation of the humeral head at all abduction angles (P < .05). At 0° abduction, all SCR conditions significantly decreased superior translation compared with the massive tear but did not restore translation (P < .05) to intact. Fascia lata and double-layer dermis SCR restored superior translation to intact at 30° and 60° of abduction, but single-layer dermis did not. Subacromial contact pressure at 0° of abduction significantly decreased with SCR with fascia lata and double-layer dermis compared with tear. At 30°, all SCR conditions significantly decreased subacromial contact pressure. Single-layer dermis graft thickness significantly decreased more than fascia lata during testing (P = .02).

CONCLUSION

For SCR tensioned at 20° glenohumeral abduction, all 3 graft types may restore superior translation and subacromial contact pressure depending on the glenohumeral abduction angle; fascia lata and double-layer dermis may be more effective than single-layer dermis.

CLINICAL RELEVANCE

If a dermal graft is to be used for SCR, consideration should be given to doubling the graft for increased thickness and better restorative biomechanical properties, which may improve clinical outcomes following SCR.

Glenoid Bone Loss in Shoulder Instability: Superiority of Three-Dimensional Computed Tomography over Two-Dimensional Magnetic Resonance Imaging Using Established Methodology

Backgroud

Recent literature suggests that three-dimensional magnetic resonance imaging (3D MRI) can replace 3D computed tomography (3D CT) when evaluating glenoid bone loss in patients with shoulder instability. We aimed to examine if 2D MRI in conjunction with a validated predictive formula for assessment of glenoid height is equivalent to the gold standard 3D CT scans for patients with recurrent glenohumeral instability.

Methods

Patients with recurrent shoulder instability and available imaging were retrospectively reviewed. Glenoid height on 3D CT and 2D MRI was measured by two blinded raters. Difference and equivalence testing were performed using a paired t-test and two one-sided tests, respectively. The interclass correlation coefficient (ICC) was used to test for interrater reliability, and percent agreement between the measurements of one reviewer was used to assess intrarater reliability.

Results

Using an equivalence margin of 1 mm, 3D CT and 2D MRI were found to be different (p = 0.123). The mean glenoid height was significantly different when measured on 2D MRI (39.09 ± 2.93 mm) compared to 3D CT (38.71 ± 2.89 mm) (p = 0.032). The mean glenoid width was significantly different between 3D CT (30.13 ± 2.43 mm) and 2D MRI (27.45 ± 1.72 mm) (p < 0.001). The 3D CT measurements had better interrater agreement (ICC, 0.91) than 2D MRI measurements (ICC, 0.8). intrarater agreement was also higher on CT.

Conclusions

Measurements of glenoid height using 3D CT and 2D MRI with subsequent calculation of the glenoid width using a validated methodology were not equivalent, and 3D CT was superior. Based on the validated methods for the measurement of glenoid bone loss on advanced imaging studies, 3D CT study must be preferred over 2D MRI in order to estimate the amount of glenoid bone loss in candidates for shoulder stabilization surgery and to assist in surgical decision-making.

Five-Year Surveillance of Vitamin D Levels in NCAA Division I Football Players: Risk Factors for Failed Supplementation

Background

Monitoring vitamin D levels in athletes and determining their response to supplementation in cases of deficiency is thought to be necessary to modulate the risks associated with vitamin D deficiency.

Hypothesis/Purpose

To report the results of a 5-year-long surveillance program of vitamin D in the serum of football players on a National Collegiate Athletic Association (NCAA) Division I team and to examine whether factors including age, body mass index (BMI), race, position played, and supplement type would affect the response to 12-month oral vitamin D replacement therapy in athletes with deficiency. We hypothesized that yearly measurements would decrease the proportion of athletes with vitamin D insufficiency over the years and that the aforementioned factors would affect the response to the supplementation therapy.

Study Design

Cohort study; Level of evidence, 3.

Methods

We measured serum 25(OH)D levels (25-hydroxyvitamin D) in 272 NCAA Division I football players from our institution annually between 2012 and 2017. Athletes with insufficient vitamin D levels (<32 ng/mL) received supplementation with vitamin D3 alone or combined vitamin D3/D2. The percentage of insufficient cases between the first 2 years and last 2 years of the program was compared, and yearly team averages of vitamin D levels were calculated. Associations between player parameters (age, BMI, race, team position, supplement type) and failed supplementation were evaluated.

Results

The prevalence of vitamin D insufficiency decreased significantly during the study period, from 55.5% in 2012-2013 to 30.7% in 2016-2017 (P = .033). The mean 25(OH)D level in 2012 was 36.3 ng/mL, and this increased to 40.5 ng/mL in 2017 (P < .001); however, this increase was not steady over the study period. Non-Hispanic athletes and quarterbacks had the highest average 25(OH)D levels, and Black players and running backs had the lowest overall levels. There were no significant differences in age, BMI, race, or playing position between athletes with and without failed vitamin D supplementation. Athletes receiving vitamin D3 alone had a more successful rate of conversion (48.15%) than those receiving combined vitamin D3/D2 (22.22%; P = .034).

Conclusion

To decrease the prevalence of vitamin D deficiency in football players, serum vitamin D measurements should be performed at least once a year, and oral supplementation therapy should be provided in cases of deficiency. Black players might be at increased risk of vitamin D insufficiency. Oral vitamin D3 may be more effective in restoring vitamin D levels than combined vitamin D3/D2 therapy.

Biomechanics of tensor fascia lata allograft for superior capsular reconstruction

BACKGROUND

We hypothesized that in a cadaveric massive rotator cuff tear (MCT) model, a fascia lata (FL) allograft superior capsular reconstruction (SCR) would restore subacromial contact pressure and humeral head superior translation without limiting range of motion (ROM). Therefore, the objective of this study was to compare these parameters between an intact rotator cuff, MCT, and allograft FL SCR.

METHODS

Eight fresh cadavers were studied using a custom shoulder testing system. ROM, superior translation, and subacromial contact pressure were measured in each of 3 states: (1) intact rotator cuff, (2) MCT, and (3) MCT with SCR.

RESULTS

Total ROM was increased in the MCT state at 60° of abduction (P = .037). FL SCR did not restrict internal or external rotational ROM. Increased superior translation was observed in the MCT state at 0° and 30° of humeral abduction, with no significant difference between the intact cuff and FL SCR states. The MCT state significantly increased mean subacromial contact pressure at 0° of abduction with 30° and 60° of external rotation, and FL SCR restored this to intact levels. Peak subacromial contact pressure was increased for the MCT state at 0° of abduction with 30° and 60° of external rotation, as well as 30° of abduction with 30° of external rotation.

CONCLUSION

This study demonstrates a tensor FL allograft preparation technique for use in SCR. After MCT, FL SCR restores ROM, superior translation, and subacromial contact pressure to the intact state.

Epidemiology of Anterior Cruciate Ligament Injury on Natural Grass Versus Artificial Turf in Soccer: 10-Year Data From the National Collegiate Athletic Association Injury Surveillance System

Background:

Anterior cruciate ligament (ACL) injury is prevalent among National Collegiate Athletic Association (NCAA) soccer players. Controversy remains regarding the effect of the surface type on the rate of ACL injury in soccer players, considering differences in sex, type of athletic exposure, and level of competition.

Hypothesis:

Natural grass surfaces would be associated with decreased ACL injury rate in NCAA soccer players. Sex, type of athletic exposure (match vs practice), and level of competition (Division I-III) would affect the relationship between playing surface and ACL injury rates.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Using the NCAA Injury Surveillance System (ISS) database, we calculated the incidence rate of ACL injury in men and women from 2004-2005 through 2013-2014 seasons. The incidence was normalized against athletic exposure (AE). Additional data collected were sex, athletic activity at time of injury (match vs practice), and level of competition (NCAA division) to stratify the analysis. Statistical comparisons were made by calculating incidence rate ratios (IRR). Statistical significance was set at an alpha of .05.

Results:

There were 30,831,779 weighted AEs during the study period. The overall injury rate was 1.12 ACL injuries per 10,000 AEs (95% CI, 1.08-1.16). Women comprised 57% of the match data (10,261 games) and 55% of practice data (26,664 practices). The overall injury rate was significantly higher on natural grass (1.16/10,000 AEs; 95% CI, 1.12-1.20) compared with artificial turf (0.92/10,000 AEs [95% CI, 0.84-1.01]; IRR, 1.26 [95% CI, 1.14-1.38]) (P < .0001). This relationship was demonstrated consistently across all subanalyses, including stratification by NCAA division and sex. The injury rate on natural grass (0.52/10,000 AEs; 95% CI, 1.11-1.26) was significantly greater than the injury incidence during practice on artificial turf (0.06/10,000 AEs; 95% CI, 0.043-0.096). Players were 8.67 times more likely to sustain an ACL injury during practice on natural grass compared with practice on artificial turf (95% CI, 5.43-12.13; P < .0001). No significant difference was found in injury rates between matches played on grass versus turf (IRR, 0.93; 95% CI, 0.84-1.03; P = .15).

Conclusion:

NCAA soccer players who practice on natural grass have increased risk of ACL injury compared with the risk of those practicing on an artificial surface, regardless of sex or NCAA division of play. No difference in risk of ACL injury between playing surfaces was detected during matches. Further research is necessary to examine the effect of multiple factors when evaluating the effect of the surface type on the risk of ACL injury in soccer players.

Epidemiologic Assessment of Concussions in an NCAA Division I Women's Soccer Team

Background:

Among collegiate sports, ice hockey and wrestling have been reported to have the highest rates of concussion injury. Recent literature has shown that among all sports, female soccer players had the highest rate of concussion injury at the high school level. Sport-specific analysis will increase our knowledge of epidemiologic characteristics of this serious injury in young soccer players, where “heading” is commonly involved during participation.

Hypothesis:

Heading during soccer will be associated with increased frequency of concussion injury in collegiate female players compared with other mechanisms of injury, and concussion injury mechanism and rates will differ by setting of injury (practice or match) and player position.

Study Design:

Descriptive epidemiologic study.

Methods:

This was a retrospective review and epidemiologic analysis of all concussions documented from a single National Collegiate Athletic Association (NCAA) Division I female collegiate soccer team between 2004 and 2017. A total of 381 participants were reviewed, and concussion injury mechanism, setting (practice or match), player position, and number of games and practices missed due to injury were analyzed.

Results:

Overall, 25 concussions in 22 players from the 2004 to 2017 seasons were identified, for an annual rate of 1.79 concussions per year. Collisions (36%) followed by headers (20%) were the most common mechanisms. Forwards sustained the most concussions (32%). Injuries were more common in games (56%) than practice (40%). Of note, the most common cause of concussion during practice was headers (40%). Of the concussions documented, 20 (91%) were the player’s first concussion. On average, each concussion resulted in a player missing 3.96 games and 12.46 practices.

Conclusion:

Our results demonstrate that concussion rates in female NCAA soccer players vary by position and occur with different frequencies and mechanisms in practice and games. Interventions for concussion avoidance should aim to limit exposure to high-risk activity, including player-to-player contact in games and headers in practice. Although gameplay and collisions can be unpredictable and difficult to control, practice settings can be modified in an attempt to decrease risk.

Return to Sport After Hip Arthroscopy for Femoroacetabular Impingement Syndrome in NCAA Division I Athletes: Experience at a Single Institution

Background:

The rate of return to sport after surgical treatment of femoroacetabular impingement (FAI) syndrome (FAIS) has been studied in high-level athletes. However, few studies examining this rate have focused exclusively on National Collegiate Athletic Association (NCAA) Division I athletes.

Purpose:

To evaluate the return-to-sport rate after hip arthroscopy for FAIS and to examine the influence of sport type on the clinical presentation of FAIS in collegiate athletes.

Study Design:

Case series; Level of evidence, 4.

Methods:

Included in this study were NCAA Division I student-athletes who underwent hip arthroscopy for FAIS at our institution between 2010 and 2017. Exclusion criteria were history of previous hip pathology, pediatric hip disease, radiographic evidence of osteoarthritis (Tönnis grade >0), prior lower extremity procedure, history of chronic pain, osteoporosis, or history of systemic inflammatory disease. Athletes were categorized into 6 subgroups based on the type of sport (cutting, contact, endurance, impingement, asymmetric/overhead, and flexibility) by using a previously reported classification system. Patient characteristics and preoperative, intraoperative, and return-to-sport variables were compared among sport types.

Results:

A total of 49 hip arthroscopies for FAIS were performed in 39 collegiate athletes (10 females, 29 males; mean age, 19.5 ± 1.3 years). A total of 1 (2.6%) cutting athlete, 15 (38.5%) contact athletes, 8 (20.5%) impingement athletes, 6 (15.4%) asymmetric/overhead athletes, and 9 (23.1%) endurance athletes were included in the study. There were no differences among sports groups with respect to the FAI type. Endurance athletes had lower rates of femoral osteochondroplasty (45.5%) and labral debridement (0.0%) (P < .0001). Contact sport athletes had higher rates of labral debridement (50.0%; P < .0001). Patients were evaluated for return to sport at an average of 1.96 ± 0.94 years. Overall, the return-to-sport rate was 89.7%. There were no differences in return-to-sport rates based on the sport type except for endurance athletes, who returned at a lower rate (66.6%; P < .001). No differences in return-to-sport rate (P = .411), duration after return (P = .265), or highest attempted level of sport resumed (P = .625) were found between patients who underwent labral repair versus debridement.

Conclusion:

Collegiate-level athletes who underwent hip arthroscopy for FAIS returned to sport at high and predictable rates, with endurance athletes possibly returning to sport at lower rates than all other sport types. Surgical procedures may be influenced by sport type, but the rate of return to sport between athletes who underwent labral debridement versus labral repair was similar.

Injections Prior to Rotator Cuff Repair Are Associated With Increased Rotator Cuff Revision Rates

PURPOSE

To determine whether shoulder injections prior to rotator cuff repair (RCR) are associated with deleterious surgical outcomes.

METHODS

Two large national insurance databases were used to identify a total of 22,156 patients who received ipsilateral shoulder injections prior to RCR. They were age, sex, obesity, smoking status, and comorbidity matched to a control group of patients who underwent RCR without prior injections. The 2 groups were compared regarding RCR revision rates.

RESULTS

Patients who received injections prior to RCR were more likely to undergo RCR revision than matched controls (odds ratio [OR], 1.52; 95% confidence interval [CI], 1.38-1.68; P < .0001). Patients who received injections closer to the time of index RCR were more likely to undergo revision (P < .0001). Patients who received a single injection prior to RCR had a higher likelihood of revision (OR, 1.25; 95% CI, 1.10-1.43; P = .001). Patients who received 2 or more injections prior to RCR had a greater than 2-fold odds of revision (combined OR, 2.12; 95% CI, 1.82-2.47; P < .0001) versus the control group.

CONCLUSIONS

This study strongly suggests a correlation between preoperative shoulder injections and revision RCR. There is also a frequency dependence and time dependence to this finding, with more frequent injections and with administration of injections closer to the time of surgery both independently associated with higher revision RCR rates. Presently, on the basis of this retrospective database study, orthopaedic surgeons should exercise due caution regarding shoulder injections in patients whom they are considering to be surgical candidates for RCR.

LEVEL OF EVIDENCE

Level III, therapeutic study.

National Athletic Trainers' Association Position Statement: Evaluation, Management, and Outcomes of and Return-to- Play Criteria for Overhead Athletes With Superior Labral Anterior-Posterior Injuries

OBJECTIVE

  To present recommendations for the diagnosis, management, outcomes, and return to play of athletes with superior labral anterior-posterior (SLAP) injuries.

BACKGROUND

  In overhead athletes, SLAP tears are common as either acute or chronic injuries. The clinical guidelines presented here were developed based on a systematic review of the current evidence and the consensus of the writing panel. Clinicians can use these guidelines to inform decision making regarding the diagnosis, acute and long-term conservative and surgical treatment, and expected outcomes of and return-to-play guidelines for athletes with SLAP injuries.

RECOMMENDATIONS

  Physical examination tests may aid diagnosis; 6 tests are recommended for confirming and 1 test is recommended for ruling out a SLAP lesion. Combinations of tests may be helpful to diagnose SLAP lesions. Clinical trials directly comparing outcomes between surgical and nonoperative management are absent; however, in cohort trials, the reports of function and return-to-sport outcomes are similar for each management approach. Nonoperative management that includes rehabilitation, nonsteroidal anti-inflammatory drugs, and corticosteroid injections is recommended as the first line of treatment. Rehabilitation should address deficits in shoulder internal rotation, total arc of motion, and horizontal-adduction motion, as well as periscapular and glenohumeral muscle strength, endurance, and neuromuscular control. Most researchers have examined the outcomes of surgical management and found high levels of satisfaction and return of shoulder function, but the ability to return to sport varied widely, with 20% to 94% of patients returning to their sport after surgical or nonoperative management. On average, 55% of athletes returned to full participation in prior sports, but overhead athletes had a lower average return of 45%. Additional work is needed to define the criteria for diagnosing and guiding clinical decision making to optimize outcomes and return to play.

NONOPERATIVE TREATMENT FOR INJURIES TO THE IN-SEASON THROWING SHOULDER: A CURRENT CONCEPTS REVIEW WITH CLINICAL COMMENTARY

Repetitive overhead throwing generates tremendous demands on the shoulder joint of the overhead athlete. Clinicians, therapists, and medical staff are charged with optimizing a throwing athlete's shoulder mobility and stability to maximize performance and prevent injury. Modifiable risk factors such as strength asymmetry, glenohumeral range of motion deficits, and scapulothoracic joint abnormalities contribute to the overhead athlete's predisposition to shoulder injury. Most shoulder injuries in the overhead thrower can be successfully treated nonoperatively to allow in-season return to sport. The optimal rehabilitation program must be based on an accurate evaluation of historical and physical information as well as diagnostic imaging. Return to play decisions should be individualized and should weigh subjective assessments along with objective measurements of range of motion, strength, and function. The purpose of this clinical commentary is to summarize the current literature regarding the nonoperative treatment options for these common injuries, and to present a treatment plan to safely return these athletes to the field of play.

Level of evidence

5.

Glenohumeral Internal Rotation Deficit and Risk of Upper Extremity Injury in Overhead Athletes: A Meta-Analysis and Systematic Review

CONTEXT

Current perception dictates that glenohumeral internal rotation deficit (GIRD) is a chronic adaptation that leads to an increased risk of pathologic conditions in the dominant shoulder or elbow of overhead athletes.

OBJECTIVE

To determine whether adaptations in glenohumeral range of motion in overhead athletes lead to injuries of the upper extremity, specifically in the shoulder or elbow.

DATA SOURCES

An electronic database search was performed using Medline, Embase, and SportDiscus from 1950 to 2016. The following keywords were used: GIRD, glenohumeral internal rotation deficit, glenohumeral deficit, shoulder, sport, injury, shoulder joint, baseball, football, racquet sports, volleyball, javelin, cricket, athletic injuries, handball, lacrosse, water polo, hammer throw, and throwing injury.

STUDY SELECTION

Seventeen studies met the inclusion criteria for this systematic review. Of those 17 studies, 10 included specific range of motion measurements required for inclusion in the meta-analysis.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Data on demographics and methodology as well as shoulder range of motion in various planes were collected when possible. The primary outcome of interest was upper extremity injury, specifically shoulder or elbow injury.

RESULTS

The systematic review included 2195 athletes (1889 males, 306 females) with a mean age of 20.8 years. Shoulders with GIRD favored an upper extremity injury, with a mean difference of 3.11° (95% CI, -0.13° to 6.36°; P = 0.06). Shoulder total range of motion suggested increased motion (mean difference, 2.97°) correlated with no injury ( P = 0.11), and less total motion (mean difference, 1.95°) favored injury ( P = 0.14). External rotational gain also favored injury, with a mean difference of 1.93° ( P = 0.07).

CONCLUSION

The pooled results of this systematic review and meta-analysis did not reach statistical significance for any shoulder motion measurement and its correlation to shoulder or elbow injury. Results, though not reaching significance, favored injury in overhead athletes with GIRD, as well as rotational loss and external rotational gain.

Return to Play After Shoulder Instability Surgery in National Collegiate Athletic Association Division I Intercollegiate Football Athletes

BACKGROUND

Recent attention has focused on the optimal surgical treatment for recurrent shoulder instability in young athletes. Collision athletes are at a higher risk for recurrent instability after surgery.

PURPOSE

To evaluate variables affecting return-to-play (RTP) rates in Division I intercollegiate football athletes after shoulder instability surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Invitations to participate were made to select sports medicine programs that care for athletes in Division I football conferences (Pac-12 Conference, Southeastern Conference [SEC], Atlantic Coast Conference [ACC]). After gaining institutional review board approval, 7 programs qualified and participated. Data on direction of instability, type of surgery, time to resume participation, and quality and level of play before and after surgery were collected.

RESULTS

There were 168 of 177 procedures that were arthroscopic surgery, with a mean 3.3-year follow-up. Overall, 85.4% of players who underwent arthroscopic surgery without concomitant procedures returned to play. Moreover, 15.6% of athletes who returned to play sustained subsequent shoulder injuries, and 10.3% sustained recurrent instability, resulting in reduction/revision surgery. No differences were noted in RTP rates in athletes who underwent anterior labral repair (82.4%), posterior labral repair (92.9%), combined anterior-posterior repair (84.8%; P = .2945), or open repair (88.9%; P = .9362). Also, 93.3% of starters, 95.4% of utilized players, and 75.7% of rarely used players returned to play. The percentage of games played before the injury was 49.9% and rose to 71.5% after surgery ( P < .0001). Athletes who played in a higher percentage of games before the injury were more likely to return to play; 91% of athletes who were starters before the injury returned as starters after surgery. Scholarship status significantly correlated with RTP after surgery ( P = .0003).

CONCLUSION

The majority of surgical interventions were isolated arthroscopic stabilization procedures, with no statistically significant difference in RTP rates when concomitant arthroscopic procedures or open stabilization procedures were performed. Athletes who returned to play often played in a higher percentage of games after surgery than before the injury, and many played at the same or a higher level after surgery.

Evaluating the Femoral-Side Critical Corner in Posterior Cruciate Ligament Reconstruction: The Effect of Outside-In Versus Inside-Out Creation of Femoral Tunnels on Graft Contact Pressure in a Synthetic Knee Model

PURPOSE

To characterize and compare the graft contact characteristics of outside-in (OI) and inside-out (IO) femoral tunnels during single-bundle reconstruction of the anterolateral bundle of the posterior cruciate ligament in a synthetic knee model.

METHODS

Femoral tunnels were separately made in 16 synthetic femora (8 OI and 8 IO). Achilles tendon allografts were fixed using suspensory fixation with a pressure sensor between the allograft and femoral tunnel. Grafts were cyclically loaded; force, contact area, contact pressure, and peak pressure at the aperture were measured. This process was repeated using the same allograft to assess the other tunnel angle in a separate specimen.

RESULTS

IO specimens showed higher mean contact pressure at all loading cycles, with significance shown at 50 N (P = .02). Peak pressure was also greater in IO specimens at all loading cycles and reached statistical significance at 100 N (P = .04). IO specimens had a lower contact area at 150 N (P = .04). No statistically significant differences in force were observed between the 2 groups.

CONCLUSIONS

OI creation of the femoral tunnel for anterolateral bundle reconstruction of the posterior cruciate ligament resulted in decreased mean and peak contact pressures at the femoral aperture compared with IO tunnel creation at the specific trajectories and loading parameters tested in this synthetic femoral model. These biomechanical data suggest that OI creation of the femoral tunnel may help reduce in vivo graft contact pressure at the femoral aperture.

CLINICAL RELEVANCE

These data suggest that a tunnel drilled from OI may result in less graft pressure at the femoral aperture, which may prevent graft elongation and optimize graft survival.

Return to Golfing Activity After Joint Arthroplasty

BACKGROUND

Many patients who are considering total joint arthroplasty, including hip, knee, and shoulder replacement, are concerned with their likelihood of returning to golf postoperatively as well as the effect that surgery will have on their game.

PURPOSE

To review the existing literature on patients who have undergone major joint arthroplasty (hip, knee, and shoulder), to examine the effects of surgery on performance in golf, and to provide surgeon recommendations as related to participation in golf after surgery. A brief review of the history and biomechanics of the golf swing is also provided.

STUDY DESIGN

Systematic review.

METHODS

We performed a systematic review of the literature in the online Medline database, evaluating articles that contained the terms "golf" and "arthroplasty." Additionally, a web-based search evaluating clinical practice recommendations after joint arthroplasty was performed. The research was reviewed, and objective and anecdotal guidelines were formulated.

RESULTS

Total joint arthroplasty provided an improvement in pain during golfing activity, and most patients were able to return to sport with variable improvements in sport-specific outcomes.

CONCLUSION

In counseling patients regarding the return to golf after joint arthroplasty, it is our opinion, on the basis of our experience and those reported from others in the literature, that golfers undergoing total hip, knee, and shoulder arthroplasty can safely return to sport.

Direct Cost Analysis of Outpatient Arthroscopic Rotator Cuff Repair in Medicare and Non-Medicare Populations

Background:

Providing high-quality care while also containing cost is a paramount goal in orthopaedic surgery. Increasingly, insurance providers in the United States, including government payers, are requiring financial and performance accountability for episodes of care, including a push toward bundled payments.

Hypothesis:

The direct cost of outpatient arthroscopic rotator cuff repair was assessed to determine whether, due to an older population, rotator cuff surgery was more costly in Medicare-insured patients than in patients covered by other insurers. We hypothesized that operative time, implant cost, and overall higher cost would be observed in Medicare patients.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Billing and operative reports from 184 outpatient arthroscopic rotator cuff repairs performed by 5 fellowship-trained arthroscopic surgeons were reviewed. Operative time, number and cost of implants, hospital reimbursement, surgeon reimbursement, and insurance type were determined from billing records and operative reports. Patients were stratified by payer (Medicare vs non-Medicare), and these variables were compared.

Results:

There were no statistically significant differences in the number of suture anchors used, implant cost, surgical duration, or overall cost of arthroscopic rotator cuff repair between Medicare and other insurers. Reimbursement was significantly higher for other payers when compared with Medicare, resulting in a mean per case deficit of $263.54 between billing and reimbursement for Medicare patients.

Conclusion:

Operating room time, implant cost, and total procedural cost was the same for Medicare patients as for patients with private payers. Further research needs to be conducted to understand the patient-specific factors that affect the cost of an episode of care for rotator cuff surgery.

Epidemiology of Operative Procedures in an NCAA Division I Football Team Over 10 Seasons

Background:

Injury rates are high for collegiate football players. Few studies have evaluated the epidemiology of surgical procedures in National Collegiate Athletic Association (NCAA) Division I collegiate football players.

Purpose:

To determine the most common surgical procedures performed in collegiate football players over a 10-year period.

Study Design:

Descriptive epidemiological study.

Methods:

From the 2004-2005 season through the 2013-2014 season, all surgical procedures performed on athletes from a single NCAA Division I college football team during athletic participation were reviewed. Surgeries were categorized by anatomic location, and operative reports were used to obtain further surgical details. Data collected over this 10-season span included type of injury, primary procedures, reoperations, and cause of reoperation, all categorized by specific anatomic locations and position played.

Results:

From the 2004-2005 through the 2013-2014 seasons, 254 operations were performed on 207 players, averaging 25.4 surgical procedures per year. The majority of surgeries performed were orthopaedic procedures (92.1%, n = 234). However, there were multiple nonorthopaedic procedures (7.9%, n = 20). The most common procedure performed was arthroscopic shoulder labral repair (12.2%, n = 31). Partial meniscectomy (11.8%, n = 30), arthroscopic anterior cruciate ligament (ACL) reconstruction (9.4% n = 24), and arthroscopic hip labral repair (5.9% n = 15) were the other commonly performed procedures. There were a total of 29 reoperations performed; thus, 12.9% of primary procedures had a reoperation. The most common revision procedure was a revision open reduction internal fixation of stress fractures in the foot as a result of a symptomatic nonunion (33.33%, n = 4) and revision ACL reconstruction (12.5%, n = 3). By position, relative to the number of athletes at each position, linebackers (30.5%) and defensive linemen (29.1%) were the most likely to undergo surgery while kickers (6%) were the least likely.

Conclusion:

In NCAA Division I college football players, the most commonly performed surgeries conducted for injuries were orthopaedic in nature. Of these, arthroscopic shoulder labral repair was the most common, followed closely by partial meniscectomy. Nonorthopaedic procedures nonetheless accounted for a sizable portion of surgical volume. Familiarity with this injury and surgical spectrum is of utmost importance for the team physician treating these high-level contact athletes.

A biomechanical assessment of a novel double endobutton technique versus a coracoid cerclage sling for acromioclavicular and coracoclavicular injuries

PURPOSE

Recently, many acromioclavicular-coracoclavicular (AC-CC) ligament reconstruction techniques address only the CC ligament. However, many of these techniques are costly, time-consuming, and require the use of allogenic grafts, making them prone to creep and failure or novel devices making them challenging for orthopaedic surgeons. The purpose of this study was to compare the biomechanical characteristics of a double endobutton technique using a standard endobutton CL with those of a coracoid cerclage sling (CS) for reconstruction of the CC ligaments.

METHODS

Anterior-posterior (AP) translation and superior-inferior (SI) translation were quantified for eight matched pairs of intact AC joints. One shoulder from each pair underwent a double endobutton repair, using an endobutton CL modified with an additional endobutton (Smith & Nephew, Memphis, Tenn) and placed through holes in the coracoid and clavicle. The contra-lateral shoulder received a coracoid sling reconstruction using an anterior tibialis tendon. Translation testing was repeated after reconstruction, followed by load-to-failure testing. Paired t tests were used for statistical analysis.

RESULTS

The CS technique demonstrated a greater SI and AP translation than the double endobutton technique (p < 0.05). Additionally, the double endobutton technique had a greater stiffness (40.2 ± 11.0 vs. 20.3 ± 6.4 N/mm, p = 0.005), yield load (168.5 ± 11.0 vs. 86.8 ± 22.9 N, p = 0.002), and ultimate load (504.4 ± 199.7 vs. 213.2 ± 103.4 N, p = 0.026) when compared to the CS technique.

CONCLUSION

The double endobutton technique yielded less translation about the AC joint and displayed stronger load-to-failure characteristics than the CS reconstruction. As such, this technique may be better suited to restore native AC-CC biomechanics, reduce post-operative pain, and prevent recurrent subluxation and dislocation than an allogenic graft construct. The double endobutton technique may be a suitable option for addressing AC-CC injuries.

Biomechanical Comparison of the Latarjet Procedure with and without Capsular Repair

Background

The purpose of this study was to determine if capsular repair used in conjunction with the Latarjet procedure results in significant alterations in glenohumeral rotational range of motion and translation.

Methods

Glenohumeral rotational range of motion and translation were measured in eight cadaveric shoulders in 90° of abduction in both the scapular and coronal planes under the following four conditions: intact glenoid, 20% bony Bankart lesion, modified Latarjet without capsular repair, and modified Latarjet with capsular repair.

Results

Creation of a 20% bony Bankart lesion led to significant increases in anterior and inferior glenohumeral translation and rotational range of motion (p < 0.005). The Latarjet procedure restored anterior and inferior stability compared to the bony Bankart condition. It also led to significant increases in glenohumeral internal and external rotational range of motion relative to both the intact and bony Bankart conditions (p < 0.05). The capsular repair from the coracoacromial ligament stump to the native capsule did not significantly affect translations relative to the Latarjet condition; however it did cause a significant decrease in external rotation in both the scapular and coronal planes (p < 0.005).

Conclusions

The Latarjet procedure is effective in restoring anteroinferior glenohumeral stability. The addition of a capsular repair does not result in significant added stability; however, it does appear to have the effect of restricting glenohumeral external rotational range of motion relative to the Latarjet procedure performed without capsular repair.

Biomechanical effects of anterior capsular plication and rotator interval closure in simulated anterior shoulder instability

PURPOSE

The purpose of this study was to determine the effect of a stepwise arthroscopic anterior plication and arthroscopic-equivalent rotator interval (RI) closure on glenohumeral range of motion, kinematics, and translation in the setting of anterior instability.

METHODS

Six cadaveric shoulders were stretched to 10 % beyond maximum external rotation (ER) to create an anterior shoulder instability model. Range of motion, kinematics, and glenohumeral translations were recorded for the following conditions: (1) intact, (2) stretched, (3) after anterior capsular plication, and (4) after RI closure.

RESULTS

The total range of motion after capsular stretching increased significantly in the 60° abduction position (p = 0.037). Average ER and total rotation were significantly decreased from the intact and stretched conditions by both repair conditions at 60° and 0° of glenohumeral abduction (p < 0.05), with no significant difference between plication and additional RI closure. At 0° abduction and 0° ER, glenohumeral translation decreased significantly from the stretched condition after RI closure with 10 and 15 N anterior and 10 N posterior loads (p < 0.05). At 30° ER, translation after RI closure was significantly less than both the intact and stretched conditions with 10 N anterior loads (p = 0.009; p = 0.004). These changes in translational stability were not seen with plication alone.

CONCLUSIONS

Anterior capsular plication reduced glenohumeral range of motion back to the intact state, and often tighter. RI closure did not contribute significantly to the reduction in the range of motion, but had implications regarding glenohumeral translation. Caution should be taken when performing anterior plication and combined repairs to avoid overtightening. Intraoperative translations could be useful when debating RI closure in patients with unidirectional anterior glenohumeral instability.

Biomechanical comparison of the modified Bristow procedure with and without capsular repair

PURPOSE

The Bristow procedure has become an effective surgical option for recurrent anterior instability of the shoulder; however, there is no consensus on whether a capsule repair following a Bristow procedure is necessary to restore glenohumeral stability. The purpose of this study was to evaluate whether capsular repair with a modified Bristow procedure affects rotational range of motion and glenohumeral stability.

METHODS

Rotational range of motion, glenohumeral translation and kinematics were measured in eight cadaveric shoulders in 90° shoulder abduction in the scapular and coronal planes for four conditions: intact, 20 % bony Bankart lesion, modified Bristow without capsular repair and modified Bristow with capsular repair.

RESULTS

Creation of the bony Bankart led to a significant increase in total range of motion and anterior-inferior translation compared to the intact shoulder. The modified Bristow procedure significantly decreased anterior-inferior translation compared to the bony Bankart but did not decrease total range of motion. Capsular repair decreased total range of motion in the scapular and coronal planes and altered normal glenohumeral kinematics in external rotation positions.

CONCLUSION

Repairing the capsule in a Bristow procedure decreases rotational range of motion yet does not offer any added anterior-inferior translational stability. Capsular repair also significantly alters normal glenohumeral kinematics. Capsule repair with a Bristow procedure may not add additional glenohumeral stability in positions of apprehension and may potentially over constrain the joint and cause altered kinematics.

Biomechanical comparison of the Latarjet procedure with and without a coracoid bone block

PURPOSE

The aim of this study was to biomechanically evaluate the Latarjet procedure, with and without a bone block, on glenohumeral range of motion, translation, and kinematics after creation of a bony Bankart lesion.

METHODS

Eight cadaveric shoulders were tested for range of motion, translation, and kinematics in 90° shoulder abduction in both the scapular and coronal planes with the following conditions: intact, Bankart lesion with 20 % glenoid bone loss, Latarjet procedure and soft tissue only conjoined tendon transfer.

RESULTS

There was a significant increase in range of motion in both the scapular and coronal planes with both the Latarjet and conjoined tendon transfer compared to the intact state. The Latarjet procedure restored anterior and inferior translation in both planes. The conjoined tendon transfer restored anterior and inferior translation at lower translational loads, but not with higher loads. Both reconstructions shifted the humeral head apex posteriorly in external rotation.

CONCLUSIONS

The increase in range of motion suggests that the Latarjet procedure does not initially over-constrain the joint. At higher loads, there was improved stability with the Latarjet procedure compared to the conjoint tendon transfer. Both Latarjet and conjoined tendon transfer procedures alter normal joint kinematics by shifting the humeral head apex posteriorly in external rotation.

Biomechanical evaluation of coracoid tunnel size and location for coracoclavicular ligament reconstruction

PURPOSE

The purpose of this study was to determine the effect of coracoid tunnel size and location on the biomechanical characteristics of cortical button fixation for coracoclavicular ligament reconstruction.

METHODS

Thirteen matched pairs of cadaveric scapulae were used to determine the effects of coracoid tunnel size, and 6 matched pairs were used to determine the effects of coracoid tunnel location. For tunnel size, a 4.5-mm hole was drilled in the base of the coracoid of one scapula and a 6-mm hole was drilled in the contralateral scapula. For tunnel location, 2 holes were drilled: (1) The first group received a hole centered in the coracoid base and a hole 1.5 cm distal from the first, along the axis of the coracoid. (2) The second group received holes that were offset anteromedially from the first set of holes (base eccentric and distal eccentric). A cortical button-suture tape construct was placed through each tunnel, and constructs were then loaded to failure.

RESULTS

For tunnel size specimens, load at ultimate failure was significantly greater for the 4.5-mm group compared with the 6-mm group (557.6 ± 48.5 N v 466.9 ± 42.2 N, P < .05). For tunnel location, load at ultimate failure was significantly greater for the centered-distal tunnel group compared with the eccentric-distal group (538.1 ± 70.2 N v 381.0 ± 68.6 N, P < .05).

CONCLUSIONS

A 4.5-mm tunnel in the coracoid provided greater strength for cortical button fixation than a 6-mm tunnel. In the distal coracoid, centered tunnels provided greater strength than eccentric tunnels.

CLINICAL RELEVANCE

When performing cortical button fixation at the coracoid process for coracoclavicular ligament reconstruction, a 4.5-mm tunnel provides greater fixation strength than a 6-mm tunnel. The base of the coracoid is more forgiving than the distal coracoid regarding location.

Primary partial humeral head resurfacing: outcomes with the HemiCAP implant

BACKGROUND

Humeral head defects such as degenerative disease or avascular necrosis are often treated with stemmed hemiarthroplasty or total shoulder arthroplasty. Despite its historical and clinical significance, stemmed humeral head replacement poses inherent technical challenges to placing spherical implants at the anatomically correct head height, version, and neck-shaft angle.

PURPOSE

The aim of this study was to assess humeral head inlay arthroplasty as a joint-preserving alternative that maintains the individual head-neck-shaft anatomy. Humeral head inlay arthroplasty also allows intraoperative surface mapping and placement of a contoured articular component that is matched to the patient's defect size, location, and individual surface geometry.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This retrospective case series included 19 patients (20 shoulders), with an average age of 48.9 years (range, 32-58 years; 16 men, 3 women). Preoperative diagnoses were osteoarthritis in 16 shoulders and osteonecrosis in 4 shoulders. Pre- and postoperative evaluations included physical examination, radiographic assessment, the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, the Simple Shoulder Test, a pain visual analog scale, and patient satisfaction rating.

RESULTS

The mean follow-up period was 32.7 months (range, 17-66 months). The mean American Shoulder and Elbow Surgeons score improved from 24.1 to 78.8, mean Simple Shoulder Test score from 3.95 to 9.3, mean visual analog scale score from 8.2 to 2.1, mean forward flexion from 100° to 129°, and mean external rotation from 23° to 43° (P < .001 for all). Radiographic follow-up showed no evidence of periprosthetic fracture, component loosening, osteolysis, or device failure. Patient shoulder self-assessment was 90% poor before surgery and improved to 75% good to excellent at last follow-up; 20% of patients self-rated as somewhat good to somewhat poor, and 5% self-rated as poor. Ninety percent of patients were satisfied with the choice of the procedure. Three patients had postoperative complications unrelated to the implants, including a partial rotator cuff tear treated with physical therapy, preexisting glenoid wear treated with arthroscopic debridement and microfracture, and infection complicated by subscapularis rupture requiring several subsequent surgical procedures but with retention of the implant.

CONCLUSION

Humeral head inlay arthroplasty is effective in providing pain relief, functional improvement, and patient satisfaction. Rather than delaying shoulder arthroplasty to end-stage osteoarthritis, humeral head inlay arthroplasty is a promising new direction in primary shoulder arthroplasty for younger and active patients with earlier stage disease.

Biomechanical analysis of the modified Bristow procedure for anterior shoulder instability: is the bone block necessary?

BACKGROUND

Anterior shoulder instability with bone loss can be treated successfully with the modified Bristow procedure. Opinions vary regarding the role of the soft-tissue sling created by the conjoined tendon after transfer. Therefore, the aim of this study was to determine the effect of the modified Bristow procedure and conjoined tendon transfer on glenohumeral translation and kinematics after creating anterior instability.

METHODS

Eight cadaveric shoulders were tested with a custom shoulder testing system. Range-of-motion, translation, and kinematic testing was performed in 60° of glenohumeral abduction in the scapular and coronal planes under the following conditions: intact joint, Bankart lesion with 20% glenoid bone loss, modified Bristow procedure, and soft tissue-only conjoined tendon transfer.

RESULTS

A Bankart lesion with 20% bone loss resulted in significantly increased external rotation and translation compared with the intact condition (P < .05), as well as an anterior shift of the humeral head apex at all points of external rotation. Both the modified Bristow procedure and soft-tissue Bristow procedure maintained the increase in external rotation but resulted in significantly decreased translation (P < .05). There was no difference in translation between the 2 reconstructions.

CONCLUSIONS

The increase in external rotation suggests that the modified Bristow procedure does not initially restrict joint motion. Translational stability can be restored in a 20% bone loss model without a bone block, suggesting the importance of the soft-tissue sling.

Prevalence of Abnormal Vitamin D Levels Among Division I NCAA Athletes

Background:

Up to 1 billion people have insufficient or deficient vitamin D levels. Despite the well-documented, widespread prevalence of low vitamin D levels and the importance of vitamin D for athletes, there is a paucity of research investigating the prevalence of vitamin D deficiency in athletes.

Hypothesis:

We investigated the prevalence of abnormal vitamin D levels in National Collegiate Athletic Association (NCAA) Division I college athletes at a single institution. We hypothesized that vitamin D insufficiency is prevalent among our cohort.

Study Design:

Cohort study.

Level of Evidence:

Level 1.

Methods:

We measured serum 25-hydroxyvitamin D (25(OH)D) levels of 223 NCAA Division I athletes between June 2012 and August 2012. The prevalence of normal (≥32 ng/mL), insufficient (20 to <32 ng/mL), and deficient (<20 ng/mL) vitamin D levels was determined. Logistic regression was utilized to analyze risk factors for abnormal vitamin D levels.

Results:

The mean serum 25(OH)D level for the 223 members of this study was 40.1 ± 14.9 ng/mL. Overall, 148 (66.4%) participants had sufficient 25(OH)D levels, and 75 (33.6%) had abnormal levels. Univariate analysis revealed the following significant predictors of abnormal vitamin D levels: male sex (odds ratio [OR] = 2.83; P = 0.0006), Hispanic race (OR = 6.07; P = 0.0063), black race (OR = 19.1; P < 0.0001), and dark skin tone (OR = 15.2; P < 0.0001). Only dark skin tone remained a significant predictor of abnormal vitamin D levels after multivariate analysis (adjusted OR = 15.2; P < 0.0001).

Conclusion:

In a large cohort of NCAA athletes, more than one third had abnormal vitamin D levels. Races with dark skin tones are at much higher risk than white athletes. Male athletes are more likely than female athletes to be vitamin D deficient. Our study demonstrates a high prevalence of vitamin D deficiency among healthy NCAA athletes.

Clinical Relevance:

Many studies indicate a significant prevalence of vitamin-D insufficiency across various populations. Recent studies have demonstrated a direct relationship between serum 25(OH)D levels and muscle power, force, velocity, and optimal bone mass. In fact, studies examining muscle biopsies from patients with low vitamin D levels have demonstrated atrophic changes in type II muscle fibers, which are crucial to most athletes. Furthermore, insufficient 25(OH)D levels can result in secondary hyperparathyroidism, increased bone turnover, bone loss, and increased risk of low trauma fractures and muscle injuries. Despite this well-documented relationship between vitamin D and athletic performance, the prevalence of vitamin D deficiency in NCAA athletes has not been well studied.

Biomechanical comparison of single-row, double-row, and transosseous-equivalent repair techniques after healing in an animal rotator cuff tear model

The transosseous-equivalent (TOE) rotator cuff repair technique increases failure loads and contact pressure and area between tendon and bone compared to single-row (SR) and double-row (DR) repairs, but no study has investigated if this translates into improved healing in vivo. We hypothesized that a TOE repair in a rabbit chronic rotator cuff tear model would demonstrate a better biomechanical profile than SR and DR repairs after 12 weeks of healing. A two-stage surgical procedure was performed on 21 New Zealand White Rabbits. The right subscapularis tendon was transected and allowed to retract for 6 weeks to simulate a chronic tear. Repair was done with the SR, DR, or TOE technique and allowed to heal for 12 weeks. Cyclic loading and load to failure biomechanical testing was then performed. The TOE repair showed greater biomechanical characteristics than DR, which in turn were greater than SR. These included yield load (p < 0.05), energy absorbed to yield (p < 0.05), and ultimate load (p < 0.05). For repair of a chronic, retracted rotator cuff tear, the TOE technique was the strongest biomechanical construct after healing followed by DR with SR being the weakest.

Tunnel intersection in combined anatomic reconstruction of the ACL and posterolateral corner

Femoral tunnel intersection in combined anterior cruciate ligament and posterolateral corner reconstruction has been reported to be high. The purpose of this study was to examine the risk of intersection between an anatomic femoral anterior cruciate ligament tunnel created with a retrograde reaming device and femoral lateral collateral ligament reconstruction tunnels of varying trajectory in a synthetic femur model.

Biomechanical evaluation of augmentation of suture-bridge supraspinatus repair with additional anterior fixation

BACKGROUND

Studies have recently focused on evaluating the ability of the supraspinatus repair to withstand rotational loads. Other studies have focused on the importance of minimizing gap formation to avoid decreased healing and failure of repair. The objective of this study was to use a loading model that incorporates external rotation to biomechanically evaluate augmenting a suture-bridge technique for supraspinatus repair with an additional anterior fixation.

METHODS

Eight matched cadaveric shoulder pairs were randomized to 2 different types of repairs after a simulated supraspinatus tear. One group received a standard suture-bridge technique, and the other underwent a suture-bridge repair with an additional anterior fixation consisting of a 4.5-mm suture anchor. A custom apparatus was used to test all specimens, allowing for dynamic external rotation from 0° to 30° during loading. Cyclic loading was performed for 30 cycles from 0 to 90 N, followed by load to failure using a materials-testing machine.

RESULTS

No differences were found in linear stiffness, yield load, ultimate load, and energy absorbed for load to failure between the 2 groups (P > .05). There was a reduction in anterior gapping at ultimate load between the anterior augmentation repair group (6.4 ± 3.1 mm) and the standard suture bridge (9.4 ± 2.8 mm; P = .037).

CONCLUSION

There does not appear to be a biomechanical advantage with the addition of an anterior suture augmentation of a suture bridge for a supraspinatus repair. However, using an anterior augmentation for a suture bridge prevents gap formation at ultimate load in a biomechanical, dynamic external rotation model.

Kinematic effect of MGHL incorporation into Bankart repair

Surgical treatment for traumatic shoulder instability has progressed in tandem with the evolution of the current understanding of the anatomy and biomechanics of the shoulder. Proponents of incorporating the middle glenohumeral ligament (MGHL) in Bankart repair believe this technique could increase repair strength. The purpose of this biomechanical study was to compare the range of motion and humeral head kinematic changes that result from including the MGHL in a Bankart repair in an effort to identify possible changes in shoulder biomechanics as a result of this addition in surgical repair.Six cadaveric shoulders were tested in 4 conditions: intact, Bankart lesion, repair excluding the MGHL, and repair including the MGHL. Each condition was tested for range of motion, glenohumeral translation, and humeral head apex position. Standard Bankart repair and repair with MGHL inclusion resulted in decreased range of motion, but no statistically significant difference was found between the 2 repair types (P=.846). Anterior translation was significantly reduced with both the Bankart repair (4.8 ± .9; P=.049) and included MGHL repair (4.6 ± 0.9; P=.029). No statistically significant difference was found between both repairs (P=.993). Although both repairs showed posterior displacement of the humeral head apex when in external rotation, this trend only reached statistical significance when compared with the Bankart lesion in 90° of external rotation (P=.0456); however, no significant difference was found between the 2 repairs (P=.999). Inclusion or exclusion of the MGHL in a Bankart repair does not significantly affect the range of motion, translation, or kinematics of the glenohumeral joint.

The effect of glenohumeral internal rotation deficit due to posterior capsular contracture on passive glenohumeral joint motion

BACKGROUND

To date, no study has investigated the biomechanical consequences of glenohumeral internal rotation deficit (GIRD) at values seen in symptomatic athletes. Hypothesis/

PURPOSE

The purpose of this study was to determine the biomechanical changes that occur with a full spectrum of GIRD in a cadaveric model with passive loading. We hypothesized that there is a critical percentage of GIRD that will result in a decrease in posterior glenohumeral translation and shift of the humeral head apex at the extreme ranges of motion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six specimens were tested using the following conditions: (1) native state ("intact"); (2) after external rotation (ER) stretch ("stretched"); and (3) GIRD of 5%, 10%, 15%, and 20%. For each condition, maximum ER, maximum internal rotation (IR), and total range of motion were measured. Kinematic data were obtained to determine the position of the humeral head apex (HHA), the highest point on the articular surface of the humeral head, relative to the geometric center of the glenoid. The amount of translation was measured in the anterior, posterior, superior, and inferior directions.

RESULTS

External rotation significantly increased compared with the intact condition for the stretched and 5% GIRD states, and IR decreased significantly beginning with 5% GIRD. At maximum ER, the HHA shifted significantly in the superior direction compared with the intact condition for all GIRD states, and at maximum IR, the HHA shifted significantly in the inferior direction compared with the intact and stretched conditions starting at 10% GIRD. The amount of posterior translation decreased significantly starting at 10% GIRD, and the amount of inferior translation decreased significantly starting at 20% GIRD.

CONCLUSION

Biomechanical changes of passive glenohumeral joint motion occur in the glenohumeral joint with as little as 5% GIRD.

CLINICAL RELEVANCE

Biomechanical changes of passive glenohumeral joint motion are noted with as little as 5% GIRD in this cadaveric model, and as the amount of GIRD increases, more substantial effects are noted.

Effects of combined anterior and posterior plication of the glenohumeral ligament complex for the repair of anterior glenohumeral instability: a biomechanical study

BACKGROUND

Arthroscopic repair techniques for anterior instability most commonly address only the anterior band of the inferior glenohumeral ligament. This study quantitatively evaluated and compared the combined anterior and posterior arthroscopic plication by repairing both the anterior and posterior bands of the inferior glenohumeral ligament with the anterior arthroscopic plication alone.

MATERIALS AND METHODS

Six cadaveric shoulders were tested in 60° of glenohumeral abduction with 22 N of compressive force in the coronal plane for intact, after anterior capsular stretching, after anterior repair, and after posterior arthroscopic repair. Range of motion, glenohumeral translation, and glenohumeral kinematics throughout the rotational range of motion were measured with a MicroScribe 3DLX (Immersion, San Jose, CA, USA). Glenohumeral contact pressure and area were measured with a pressure measurement system (Tekscan Inc, South Boston, MA, USA).

RESULTS

Stretching the anterior capsule significantly increased external rotation and anterior translation (P < .05). After anterior plication, external rotation was restored to the intact condition, and anterior translation was significantly decreased compared with stretched condition (P < .05). The combined anterior and posterior plication significantly decreased internal rotation compared with the intact condition. The anterior plication shifted the humeral head posterior in external rotation, whereas the combined anterior and posterior plication shifted the humeral head anterior in internal rotation (P < .05). Both repairs led to a decrease in glenohumeral contact area at 45° external rotation (P < .07).

CONCLUSIONS

The addition of a posterior plication to anterior plication for anterior instability has no biomechanical advantage over a typical arthroscopic anterior repair for anterior glenohumeral instability.

A watertight construct in arthroscopic rotator cuff repair

BACKGROUND

It is unknown which type of rotator cuff repair technique best isolates the healing zone interface from the synovial fluid environment. The purpose of this study was to determine the leakage area and pattern onto the rotator cuff footprint after 3 different rotator cuff repairs.

MATERIALS AND METHODS

Six fresh frozen cadaveric glenohumeral joints in each of 3 groups were injected with gelatin to a pressure of 103 mm Hg (∼2 psi) after 1 of 3 different rotator cuff repairs of a supraspinatus tear: (1) single-row repair (SR), (2) knotless transosseous equivalent repair (KTE), and (3) traditional transosseous equivalent repair (TTE), which uses medial tied knots. Specimens were cycled in external rotation and abduction and were cooled to allow the gelatin to solidify. The supraspinatus was dissected off the footprint and photographs were taken. Scion Image (Frederick, MD, USA) was used to quantify the area.

RESULTS

The average area of leakage was 1.09 cm(2) for the SR and 1.15 cm(2) for the KTE. The TTE did not demonstrate any leakage. The pattern of leakage for the KTE was medial and central on the footprint, whereas the SR demonstrated leakage up to the tied knots. The difference in the area of leakage in the SR and KTE compared with the TTE was statistically significant. There was no difference in area of leakage between the SR and KTE.

CONCLUSION

A transosseous equivalent repair technique best prevents leakage onto the rotator cuff footprint compared with single-row and knotless repairs.

Biomechanical effects of arthroscopic capsulorrhaphy in line with the fibers of the anterior band of the inferior glenohumeral ligament

BACKGROUND

There is no consensus as to the amount and direction of capsular plication necessary to correct anterior shoulder instability without overconstraining the joint.

HYPOTHESIS

An arthroscopic capsulorrhaphy in line with the fibers of the inferior glenohumeral ligament (IGHL) in an anterior laxity model will restore glenohumeral kinematics to normal.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six cadaveric specimens were tested in both the scapular and coronal plane in 3 conditions: intact, anterior instability, and plicated. The anterior instability model was created by stretching the shoulder 20% beyond the physiological external rotational range of motion, and plication was achieved by performing a 10-mm arthroscopic plication in line with the fibers of the anterior band of the IGHL.

RESULTS

Stretching significantly increased the rotational range of motion, while plication restored it back to that of the intact condition (P < .05). There were few significant changes in humeral head apex position across all 3 testing conditions. Plication significantly reduced anterior translation compared with the stretched condition (P < .05). Stretching and plication both significantly reduced contact area relative to the intact condition (P < .05). There were no significant differences between any of the 3 conditions for contact pressure and only few significant differences between the conditions for contact peak pressure.

CONCLUSION

A 10-mm capsular plication in line with the fibers of the anterior band of the IGHL effectively reduces capsular laxity without overconstraining the joint.

CLINICAL RELEVANCE

The fibers of the anterior band of the IGHL provide a useful arthroscopic anatomic landmark for the direction of anterior capsulorrhaphy.

Biomechanical comparison of anatomic humeral head resurfacing and hemiarthroplasty in functional glenohumeral positions

BACKGROUND

Resurfacing of the humeral head has gained interest as an alternative to traditional hemiarthroplasty because it preserves bone stock and respects the native geometry of the glenohumeral articulation. The purpose of this study was to compare the biomechanics of the intact glenohumeral joint with those following humeral head resurfacing and following hemiarthroplasty.

METHODS

Seven fresh-frozen cadaveric shoulders were tested with the rotator cuff, pectoralis major, and latissimus dorsi musculature loaded with 20 N and the deltoid muscle loaded with 40 N in a custom shoulder testing system. Each specimen was tested in 20°, 40°, 60°, and 80° of vertical abduction. The articular surfaces of the humeral head and the glenoid were digitized to calculate the positions of the geometric center and apex of the humeral head relative to the geometric center of the glenoid at each testing position. The contact area and contact pressures were also measured with use of a Tekscan pressure sensor.

RESULTS

The geometric center of the humeral head shifted by a mean (and standard error) of 2.2 ± 0.3 mm following humeral resurfacing and 4.7 ± 0.3 mm following hemiarthroplasty (p &lt; 0.0002). The apex of the humeral head was shifted superiorly at all abduction angles following hemiarthroplasty (p &lt; 0.03). Both humeral resurfacing and hemiarthroplasty decreased the glenohumeral contact area and increased the peak pressure.

CONCLUSIONS

Resurfacing more closely restored the geometric center of the humeral head than hemiarthroplasty did, with less eccentric loading of the glenoid.

CLINICAL RELEVANCE

Compared with hemiarthroplasty, humeral resurfacing may limit eccentric glenoid wear and permit better function because the glenohumeral joint biomechanics and the moment arms of the rotator cuff and the deltoid muscle are restored more closely to those of the intact condition.

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.

The effect of abduction and rotation on footprint contact for single-row, double-row, and modified double-row rotator cuff repair techniques

BACKGROUND

An abduction pillow and abduction and rotation exercises are commonly used after rotator cuff repair. The effect of glenohumeral abduction and rotation on footprint contact has not been elucidated.

HYPOTHESIS

Abduction will decrease tendon-to-bone contact for all repairs. A modified double-row repair will maintain footprint contact more effectively at each position of humeral abduction and rotation than double- or single-row repairs.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 6 fresh-frozen human shoulders, a modified double-row supraspinatus tendon repair was performed; a suture limb from each of 2 medial anchors was bridged over the tendon and fixed laterally. Double- and single-row repairs were performed sequentially; a total of 3 repairs were tested. For all repairs, a Tekscan pressure sensor was fixed at the tendon-footprint interface. The tendon was loaded with 30 N. The shoulders were tested at 0 degrees , 30 degrees , and 60 degrees of abduction with 0 degrees of rotation. For both dual-row repairs, 5 rotation positions were tested.

RESULTS

The greatest contact areas at neutral rotation were achieved at 0 degrees of abduction for the modified double-row, double-row, and single-row repairs (151.3 +/- 10.7 mm2, 80.7 +/- 30.0 mm2, and 61.3 +/- 26.1 mm2, respectively), with values decreasing as abduction increased. Each repair was significantly different from one another at each abduction angle (P < .05), except between single- and double-row repairs at 0 degrees of abduction. Mean interface pressure exerted over the footprint was greater for the modified double-row technique than for the other techniques at each abduction angle (P < .05). With respect to rotation, the modified double-row repair had significantly more footprint contact than did the double-row repair at each position tested (P < .05).

CONCLUSION

For a given repair, increasing abduction at neutral rotation reduced footprint contact. Internal rotation to 60 degrees provided among the highest contact measurements. The modified double-row technique provided the most contact.

CLINICAL RELEVANCE

Results are consistent with the practice of immobilizing the shoulder with 30 degrees or less of abduction and up to 60 degrees of internal rotation to optimize footprint contact. A dual-row repair may maximize contact when initiating rehabilitation that involves abduction and rotation.

Biomechanical analysis comparing a traditional superior-inferior arthroscopic rotator interval closure with a novel medial-lateral technique in a cadaveric multidirectional instability model

BACKGROUND

Commonly performed arthroscopic rotator interval closure techniques that imbricate the rotator interval in a superior-inferior direction have been unable to reproduce the stabilizing effects of an open medial-lateral rotator interval imbrication.

HYPOTHESIS

The medial-lateral rotator interval closure will allow less inferior and posterior glenohumeral translation than the superior-inferior rotator interval closure, and the medial-lateral rotator interval closure will result in less loss of external rotation than the superior-inferior closure.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight match-paired cadaveric shoulders were stretched to 10% beyond the maximum range of motion in 0 degrees and 60 degrees of glenohumeral abduction to create a multidirectional instability model. Shoulders were then repaired using a superior-inferior rotator interval closure or an arthroscopic medial-lateral rotator interval closure with an anchor in the humeral head. Rotational range of motion, glenohumeral translation, and humeral head apex position were measured for intact, stretched, and repaired conditions in both 0 degrees and 60 degrees of glenohumeral abduction.

RESULTS

In 0 degrees of abduction, after both rotator interval closure techniques, external rotation decreased significantly (by 4.4%; P < .05) relative to the stretched state and was restored to the intact state. In 60 degrees of abduction, only the medial-lateral rotator interval closure restored range of motion to the intact state. In 60 degrees of abduction, the medial-lateral rotator interval closure was more effective in reducing posterior translation than was the superior-inferior closure (P = .03).

CONCLUSION

The medial-lateral rotator interval closure restored range of motion to the intact state better than the superior-inferior closure. Compared with the superior-inferior rotator interval closure, the medial-lateral closure significantly decreased posterior translation with the shoulder in abduction and external rotation.

CLINICAL RELEVANCE

Arthroscopic medial-lateral rotator interval closure with a suture anchor in the humeral head can be considered in the surgical treatment of patients with multidirectional instability, especially those with a component of posterior instability, without concern for excessive loss of range of motion.

The effect of the long head of the biceps on glenohumeral kinematics

The long head of the biceps has been described as a stabilizing force in the setting of glenohumeral instability. However, data are lacking on the effect of loading the long head of the biceps on glenohumeral kinematics. Six cadaveric shoulders were tested for glenohumeral rotational range of motion and translation using a custom shoulder testing system and the Microscribe 3DLX (Immersion, San Jose, CA). The path of glenohumeral articulation (PGA) was measured by calculating the humeral head center with respect to the glenoid articular surface at maximal internal rotation, 30 degrees, 60 degrees, 90 degrees, and maximal external rotation. Significant decreases in glenohumeral rotational range of motion and translation were found with 22-N biceps loading vs the unloaded group. With respect to the PGA, the humeral rotation center was shifted posterior with biceps loading at maximal internal rotation, 30 degrees, and 60 degrees of external rotation. Loading the long head of the biceps significantly affects glenohumeral rotational range of motion, translations, and kinematics.

Biomechanical assessment of Type II superior labral anterior-posterior (SLAP) lesions associated with anterior shoulder capsular laxity as seen in throwers: a cadaveric study

BACKGROUND

Type II superior labral anterior-posterior lesions in throwers are often associated with anterior shoulder capsular laxity.

HYPOTHESIS

Shoulder instability in patients with type II superior labral anterior-posterior lesions may result from the associated shoulder capsular laxity rather than the superior labral anterior-posterior lesion alone.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six cadaveric shoulders were externally rotated to 20% beyond the maximum humeral external rotation at 60 degrees of glenohumeral abduction, which simulated 90 degrees of shoulder abduction, to detach the superior labrum and elongate the anterior shoulder capsular ligaments. The detached labrum was then repaired to isolate the effect of the detached superior labrum and that of the capsular laxity. Rotational range of motion was measured at 60 degrees of glenohumeral abduction. Anterior-posterior glenohumeral translation was measured at 30 degrees and 60 degrees of glenohumeral abduction. Superior-inferior glenohumeral translation was measured at 0 degrees and 60 degrees of glenohumeral abduction.

RESULTS

The experimentally created type II superior labral anterior-posterior lesion and capsular laxity significantly increased anterior translation at 30 degrees (mean difference, 1.0 +/- 0.8 mm; P < .05) and 60 degrees (mean difference, 2.2 +/- 2.0 mm; P < .05) of glenohumeral abduction. Subsequent superior labral anterior-posterior repair restored the anterior translation but only at 30 degrees of glenohumeral abduction (mean difference, 0.9 +/- 0.6 mm; P < .05).

CONCLUSION

Because of the anterior capsular laxity associated with type II superior labral anterior-posterior lesions, superior labral anterior-posterior repair of the peeled-back superior labrum may not restore anterior glenohumeral translation at 90 degrees of shoulder abduction.

CLINICAL RELEVANCE

Anterior shoulder capsular laxity associated with type II superior labral anterior-posterior lesions may cause anterior shoulder instability at 90 degrees of shoulder abduction in throwers even after superior labral anterior-posterior lesion repair.