Shoulder

Abstract:

As technology continues to improve, surgeons must regularly re-evaluate techniques to improve efficacy and outcomes. The Bankart repair for shoulder instability has evolved from open reconstruction to minimally invasive arthroscopic techniques, which have the benefit of less pain and morbidity. This technical description and video present a modern arthroscopic technique for Bankart repair used at our institution with high success in an athletic population.

Abstract:

BACKGROUND:

To compare the activation of shoulder and trunk muscles between six pairs of closed (CC) and open chain (OC) exercises for the upper extremity, matched for performance characteristics. The secondary aims were to compare shoulder and trunk muscle activation and shoulder activation ratios during each pair of CC and OC exercise.

METHODS:

Twenty-two healthy young adults were recruited. During visit 1, the 5-repetition maximum resistance was established for each CC and OC exercise. During visit 2, electromyography activation from the infraspinatus (INF), deltoid (DEL), serratus anterior (SA), upper, middle and lower trapezius (UT, MT, LT), erector spinae (ES) and external oblique (EO) muscles was collected during 5-repetition max of each exercise. Average activation was calculated during the concentric and eccentric phases of each exercises. Activation ratios (DEL/INF, UT/LT, UT/MT, UT/SA) were also calculated. Linear mixed models compared the activation by muscle collapsed across CC and OC exercises. A paired t-test compared the activation of each muscle and the activation ratios (DEL/INF, UT/LT, UT/MT, UT/SA) between each pair of CC and OC exercises.

RESULTS:

The INF, LT, ES, and EO had greater activation during both concentric (p = 0.03) and eccentric (p < 0.01) phases of CC versus OC exercises. Activation ratios were lower in CC exercises compared to OC exercises (DEL/INF, 3 pairs; UT/LT, 2 pairs; UT/MT, 1 pair; UT/SA, 3 pairs).

CONCLUSION:

Upper extremity CC exercises generated greater activation of shoulder and trunk muscles compared to OC exercises. Some of the CC exercises produced lower activation ratios compared to OC exercises.

Abstract:

BACKGROUND:

Literature on arthroscopic stabilization in adolescent patients participating in collision and contact sports is limited, as most studies include adolescents within a larger sample group comprised primarily of adults.

PURPOSE:

To review the outcomes of arthroscopic Bankart repair for anterior shoulder instability in an adolescent population participating in collision and contact sports.

STUDY CASE:

Case series; Level of evidence, 4.

METHODS:

This retrospective review included 39 shoulders in 37 adolescent (≤19 years) athletes who underwent primary arthroscopic Bankart repair using suture anchors with at least 2-year follow-up. All patients had a history of trauma to their shoulder resulting in an anterior dislocation. Outcome measures included patient satisfaction, the visual analog scale (VAS) for pain, American Shoulder and Elbow Surgeons (ASES) score, and Rowe score. Recurrence of dislocation and return to sporting activity were also assessed.

RESULTS:

The mean age at the time of surgery was 16.9 years (range, 15-19 years), and the mean follow-up was 6.3 years (range, 4.3-10.0 years); 58.6% of patients participated in collision sports. Time to surgery after the initial dislocation episode was 9.2 months (range, 0.5-36.2 months). Four shoulders (10.3%) had dislocation events postoperatively. The majority (78.1%) of patients returned to sports at the same level of competition. Mean VAS was 0.49 ± 1.0, and the mean ASES and Rowe scores were 92.8 ± 12.6 and 85.0 ± 24.2, respectively. Univariate analyses demonstrated that subjective functional outcomes were negatively correlated with recurrence (ASES, P = .005; Rowe, P = .001) and failure to return to sport (ASES, P = .016; Rowe, P = .004). Independent variables shown to have no significant relationship to functional outcomes included age, follow-up, number of preoperative dislocations, time to surgery, sport classification, competition level, tear extent, number of anchors, concurrent Hill-Sachs lesion, and repair of a superior labral anterior-posterior (SLAP) lesion.

CONCLUSION:

Arthroscopic Bankart repair is an effective surgical option for traumatic shoulder instability in adolescents participating in collision and contact sports. At a minimum 4-year follow-up, arthroscopic Bankart repair effectively restored stability in 90% of cases; 80% returned to their preinjury level of sport.

Abstract:

OBJECTIVES:

Though pitchers often throw during multiple games in a day, there are currently no pitch count restrictions in softball. The accumulation of high pitch counts over time may contribute to the development of upper extremity pain. The purpose of our study was to examine functional characteristics of shoulder and hip range of motion (ROM), isometric strength (ISO), and ball speed in softball pitchers with and without upper extremity (UE) pain.

DESIGN:

Controlled laboratory design.

METHODS:

Fifty-three NCAA Division I softball pitchers (20.0±1.4 years; 173.3±8.3cm; 80.9±12.3kg) participated and were divided into two groups: pain-free (n=30) and pain in the UE (n=23). Bilateral shoulder and hip external rotation (ER) and internal rotation (IR) ROM and ISO were measured prior to pitching to a catcher located 13.1m (43ft) away.

RESULTS:

Independent samples t-tests revealed significantly greater throwing side (TS) hip ER ROM (p=0.012), TS hip IR ISO (p=0.038), glove side (GS) hip ER ISO (p=0.025), TS shoulder ER ISO (p=0.002), GS shoulder IR (p=0.006) and ER (p=0.004) ISO in the pain free group versus the UE pain group.

CONCLUSIONS:

Differences in shoulder and hip ROM and ISO exist between those who have upper extremity pain and those who do not. Therefore, findings suggest that both the upper and lower extremities should be considered when treating softball pitchers with UE pain.

Abstract:

BACKGROUND:

Partial-thickness articular-sided rotator cuff tears are a frequent source of shoulder pain. Despite conservative measures, some patients continue to be symptomatic and require surgical management. However, there is some controversy as to which surgical approach results in the best outcomes for grade 3 tears.

HYPOTHESIS/PURPOSE:

The purpose of this study was to evaluate repair integrity and the clinical results of patients treated with transtendinous repair of high-grade partial-thickness articular-sided rotator cuff tears. Our hypothesis was that transtendinous repairs would result in reliable healing and acceptable functional outcomes.

STUDY DESIGN:

Case series; Level of evidence, 4.

METHODS:

Twenty patients with a minimum follow-up of 2 years were included in the study. All patients underwent arthroscopic repair of high-grade partial-thickness rotator cuff tears utilizing a transtendinous technique by a single surgeon. At latest follow-up, the repair integrity was evaluated using ultrasound imaging, and functional scores were calculated.

RESULTS:

Ultrasound evaluation demonstrated that 18 of 20 patients had complete healing with a normal-appearing rotator cuff. Two patients had a minor residual partial tear. Sixteen of 20 patients had no pain on visual analog scale. Four patients complained of mild intermittent residual pain. All patients were rated as “excellent” by both the University of California at Los Angeles Shoulder Score and the Simple Shoulder Test.

CONCLUSION:

The transtendon technique for the repair of articular-sided high-grade partial rotator cuff tears results in reliable tendon healing and excellent functional outcomes.

Abstract:

Recent advances to improve outcomes in rotator cuff repair include using arthroscopic double-row suture-bridge techniques in an effort to reconstruct the rotator cuff footprint and improve fixation. However, when using this technique for larger tears, it can be difficult to get the lateral portion of the rotator cuff into an anatomic position. This report describes a triple-row modification of the suture-bridge technique that results in significantly more footprint contact area and contact pressure compared with the double-row and standard suture-bridge techniques. Maximizing the rotator cuff footprint contact area exposes more of the tendon to bone and may improve the healing potential.

Abstract:

PURPOSE:

To report a large number of highly active patients who underwent arthroscopic Bankart repair at our institution over the last decade.

METHODS:

A retrospective analysis of patients who underwent primary and revision arthroscopic Bankart repairs using bioabsorbable anchors was performed. Outcome measures included recurrence of dislocation, American Shoulder and Elbow Scores (ASES), Rowe, visual analog scale (VAS), return to sports, and satisfaction scores.

RESULTS:

A total of 94 shoulders met the inclusion criteria. The recurrence rate was 6/94 (6.4%) at a mean follow-up of 5 years (range, 3 to 8.3). The mean postoperative scores were as follows: ASES = 91.5/100; Rowe = 84.3/100; VAS = 0.8/10; satisfaction = 8.8/10. In those who attempted to return to sports, 82.5% were able to return to the same level of competition. Statistical analyses revealed a significant increase in risk of recurrence among high school and recreational athletes. No recurrences were observed among professional or college-level athletes. No significant difference in recurrence rates was observed in regards to age, time to surgery, type of athlete (collision v limited contact), repair of SLAP lesion, number of anchors, or revision surgery.

CONCLUSIONS:

Although several repair techniques exist for traumatic anterior shoulder instability, arthroscopic repair remains a viable option even in a highly active patient population. This study uniquely identified high school and recreational athletes at higher risk for recurrence. This is perhaps due to inferior shoulder development and technique as well as to limited access to postoperative physical therapy.

Abstract:

BACKGROUND:

Variable return-to-play (RTP) rates have been reported after surgical repair of superior labral anterior-posterior (SLAP) tears in baseball players. Many studies, however, have not controlled for concomitant shoulder injuries.

PURPOSE/HYPOTHESIS:

The purpose of this study was to evaluate rates of RTP and return to previous or higher performance level (RTPP) and long-term outcomes after isolated SLAP tear repair. The hypothesis was that improved outcomes would be identified compared with previous reports.

STUDY DESIGN:

Case series; Level of evidence, 4.

METHODS:

The records of 232 players who underwent isolated SLAP tear repair from 2004 to 2014 were reviewed. A total of 98 players who were at least 12 months out from surgery were identified. Through telephone interviews, participants completed the Western Ontario Shoulder Instability Index (WOSI) and Veterans RAND 12-Item Health Survey (VR-12) and answered scripted questions about RTP, RTPP, and current symptoms.

RESULTS:

Of the 98 players who met the inclusion criteria, 73 (74.5%) participated. The mean age at the time of surgery was 19.8 ± 2.9 years. The mean follow-up time was 86.2 ± 25.1 months overall; it was 84.4 ± 24.4 months for pitchers and 90.3 ± 26.7 months for other position players, (P = .40). There were 10 professional, 36 collegiate, and 27 high school players. Most players perceived successful RTP (83.6%), including 80.0% of pitchers and 91.3% of other position players (P = .23). However, RTPP rates were lower, at 52.3% (n = 26) and 78.3% (n = 18) for pitchers and other position players, respectively (P = .03). Pitchers were younger at the time of surgery (19.3 ± 3.0 vs 20.8 ± 3.0 years, respectively; P = .03) and had greater perceived shoulder and general health impairments compared with other position players (P ≤ .02). Players who perceived successful RTPP had better WOSI of the healthy shoulder and individual physical, sports, lifestyle, and emotion scores compared with players who did not perceive successful RTPP.

CONCLUSION:

After the surgical repair of isolated type II or greater SLAP tears, other position players displayed superior RTP (91.3% vs 80.0%, respectively) and RTPP (78.3% vs 52.3%, respectively) rates than pitchers. Long-term follow-up suggests that pitchers may perceive greater long-term impairments than other position players and are less likely to return to their previous or higher performance level.

Abstract:

BACKGROUND:

It is unclear how a glenohumeral internal rotation (IR) loss (GIRLoss), a glenohumeral external rotation (ER) gain (GERGain), or a total rotational motion (TRM) deficit (TRMD) predict medial ulnar collateral ligament (MUCL) injury risk among high school (HS), college (COLL), and professional (PRO) baseball pitchers with and without MUCL injury. We hypothesized that pitchers with MUCL injury would have more GIRLoss and TRMD compared with pitchers without MUCL injury, with no differences in IR, ER, TRM, GIRLoss, GERGain, and TRMD.

METHODS:

The study equally divided 216 male HS, COLL, and PRO pitchers into the MUCL injury group (n = 108) and a control group (n = 108) without MUCL injury. The control group was matched with the MUCL injury group according to number, level of play, and age. Bilateral shoulder passive IR/ER was measured and GIRLoss, GERGain, TRM, and TRMD calculated. A 2-way analysis of variance (P < .05) was used to assess shoulder rotational differences among the 2 groups and 3 pitching levels.

RESULTS:

Compared with the control group, the MUCL injured group had more GIRLoss (21° ± 14° vs. 13° ± 8°; P < .001), GERGain (14° ± 9° vs. 10° ± 9°; P = .004), and TRMD (7° ± 13° vs. 3° ± 9°; P = .008). For all pitching levels, approximately 60% of pitchers in MUCL injury group had GIRLoss >18° compared with approximately 30% of those in the control group. Approximately 60% of pitchers in the MUCL injury group had TRMD >5° compared with 50% of pitchers in the control group. No differences were observed among HS, COLL, and PRO pitchers for GIRLoss (16° ± 12°, 17° ± 11°, 19° ± 13°, respectively; P = .131), GERGain (11° ± 9°, 11° ± 10°, 13° ± 10°, respectively; P = .171), TRMD (5° ± 11°, 6° ± 11°, 5° ± 14°, respectively; P = .711), and throwing shoulder ER (111° ± 10°, 111° ± 11°, 113° ± 9°, respectively; P = .427), IR (50° ± 11°, 49° ± 11°, 48° ± 10°, respectively; P = .121), and TRM (162° ± 14°, 160° ± 15°, 161° ± 14°, respectively; P = .770).

CONCLUSIONS:

Greater GIRLoss, GERGain, and TRMD in MUCL injured pitchers compared with uninjured pitchers implies these variables may be related to increased MUCL injury risk, especially because GIRLoss >18° and TRMD >5° demonstrate an increased MUCL injury risk. Shoulder rotational motion and deficits do not vary among HS, COLL, and PRO levels of pitchers.

Abstract:

CASE:

A sixty-three-year-old woman who underwent routine arthroscopic rotator cuff repair developed extensive heterotopic ossification postoperatively. She required a reoperation for excision.

CONCLUSION:

Heterotopic ossification should be included in the differential diagnosis for postoperative stiffness after an arthroscopic rotator cuff repair.

Abstract:

BACKGROUND:

Few studies have documented the outcomes of superior labral anterior-posterior (SLAP) repairs in baseball players. Furthermore, the results of these previous studies varied widely and were based on small numbers of patients. Hypothesis/Purpose: The purpose was to report return-to-play (RTP) rates and validated subjective outcome scores for baseball players after SLAP repair. It was hypothesized that RTP rates and outcomes would be significantly different between pitchers and nonpitchers, as well as among baseball levels.

STUDY DESIGN:

Case series; Level of evidence, 4.

METHODS:

A series of 216 baseball players was identified who had isolated SLAP repair or SLAP repair with debridement of partial-thickness (<25%) rotator cuff tear at our surgical centers. Patients were contacted by phone a minimum of 2 years after surgery and asked questions about their ability to RTP. Patients were also asked questions to complete the Western Ontario Shoulder Instability Index (WOSI), Veteran’s RAND 12-Item Health Survey (VR-12), and Kerlan-Jobe Orthopaedic Clinic (KJOC) questionnaires. Statistical equivalence in RTP rate, VR-12, and WOSI scores was determined between players with and without concomitant rotator cuff debridement using 2 one-sided tests and risk difference measures. Differences in RTP were tested among baseball levels (high school, college, professional) and positions (pitcher vs nonpitcher) using chi-square analyses ( P < .05). Differences in outcomes scores were compared using t tests and analyses of variance ( P < .05).

RESULTS:

Of the 216 baseball players, 133 were reached by phone for follow-up interview (mean, 78 months; range, 27-146 months). Overall, 62% successfully returned to play. There were no differences in RTP rates or subjective outcomes among baseball levels or between procedures. RTP rates were 59% for pitchers and 76% for nonpitchers ( P = .060). Subjectively, the percentage of patients who felt the same or better at follow-up compared to preinjury was significantly higher among nonpitchers (66%) than pitchers (43%). There was no difference in KJOC scores between the pitchers (75.3 ± 19.4) and nonpitchers (76.2 ± 17.4) who successfully returned to play, although these scores were well below the minimum desired score of 90 for healthy baseball players.

CONCLUSION:

SLAP repair should continue to be considered as an option for SLAP tear treatment only after nonsurgical management has failed. Some players may be able to return to baseball after SLAP repair, although regaining preinjury health and performance is challenging.

Abstract:

BACKGROUND:

Shoulder and elbow injuries are common in young athletes, especially high school baseball players. Understanding the risk factors associated with baseball injuries is an essential first step in the development of injury prevention strategies.

PURPOSE:

Shoulder and elbow injuries are common in young athletes, especially high school baseball players. Understanding the risk factors associated with baseball injuries is an essential first step in the development of injury prevention strategies.

STUDY DESIGN:

Descriptive epidemiological study.

METHODS:

Baseball-related injury data were obtained from the National High School Sports-Related Injury Surveillance Study using High School RIO (Reporting Information Online), an Internet-based sports injury surveillance system. Athletic trainers from high schools across the country uploaded data regarding athlete-exposures (AEs) (defined as practice or game participation) and shoulder and elbow injuries from the school years 2005-2006 through 2014-2015.

RESULTS:

A total of 241 shoulder injuries and 150 elbow injuries occurred during 1,734,198 AEs during the study period, for an overall shoulder injury rate of 1.39 per 10,000 AEs and an overall elbow injury rate of 0.86 per 10,000 AEs. The overall rates of injury were higher in competitions compared with practices for shoulders (rate ratio, 1.44; 95% CI, 1.11-1.85) and elbows (rate ratio, 2.15; 95% CI, 1.56-2.96). The majority of shoulder (39.6%) and elbow (56.9%) injuries were sustained by pitchers, and most injuries were chronic and caused by overuse. Position players were more likely to sustain injuries by contact with the playing surface or apparatus. For pitchers, muscle strains were the most common shoulder injuries (38.7%), while ligament sprains were the most common elbow injuries (42.7%). The majority of pitchers with shoulder (70.8%) and elbow (64.6%) injuries returned to play within 21 days. Among pitchers, a higher proportion of elbow injuries (11.4%) resulted in medical disqualification compared with shoulder injuries (5.6%). Among pitchers, the majority of shoulder (89.2%) and elbow (96.4%) injuries were managed nonsurgically.

CONCLUSION:

Shoulder and elbow injury rates and patterns in high school baseball players differed between field positions (pitchers vs position players) and by type of exposure (practice vs competition). This study suggests several areas of emphasis for targeted injury prevention interventions, most notably limiting fatigue and preventing overuse injuries.

Abstract:

BACKGROUND:

Rotator cuff tears are rare injuries in adolescents but cause significant morbidity if unrecognized. Previous literature on rotator cuff repairs in adolescents is limited to small case series, with few data to guide treatment.

HYPOTHESIS:

Adolescent patients would have excellent functional outcome scores and return to the same level of sports participation after rotator cuff repair but would have some difficulty with returning to overhead sports.

STUDY DESIGN:

Case series; Level of evidence 4.

METHODS:

A retrospective search of the practice’s billing records identified all patients participating in at least 1 sport who underwent rotator cuff repair between 2006 and 2014 with an age <18 years at the time of surgery and a minimum follow-up of 2 years. Clinical records were evaluated for demographic information, and telephone follow-up was obtained regarding return to play, performance, other surgery and complications, a numeric pain rating scale (0-10) for current shoulder pain, American Shoulder and Elbow Surgeons (ASES) Shoulder Assessment Form, and the Western Ontario Rotator Cuff Index.

RESULTS:

Thirty-two consecutive adolescent athletes (28 boys and 4 girls) with a mean age of 16.1 years (range, 13.2-17.9 years) met inclusion criteria. Twenty-nine patients (91%) had a traumatic event, and 27 of these patients (93%) had no symptoms before the trauma. The most common single tendon injury was to the supraspinatus (21 patients, 66%), of which 2 were complete tendon tears, 1 was a bony avulsion of the tendon, and 18 were high-grade partial tears. Fourteen patients (56%) underwent single-row repair of their rotator cuff tear, and 11 (44%) underwent double-row repair. All subscapularis injuries were repaired in open fashion, while all other tears were repaired arthroscopically. Twenty-seven patients (84%) completed the outcome questionnaires at a mean 6.2 years after surgery (range, 2-10 years). The mean ASES score was 93 (range, 65-100; SD = 9); mean Western Ontario Rotator Cuff Index, 89% (range, 60%-100%; SD = 13%); and mean numeric pain rating, 0.3 (range, 0-3; SD = 0.8). Overall, 25 patients (93%) returned to the same level of play or higher. Among overhead athletes, 13 (93%) were able to return to the same level of play, but 8 (57%) were forced to change positions. There were no surgical complications, but 2 patients did undergo a subsequent operation.

CONCLUSION:

Surgical repair of high-grade partial-thickness and complete rotator cuff tears yielded successful outcomes among adolescents, with excellent functional outcomes at midterm follow-up. However, overhead athletes may have difficulty playing the same position after surgery.

Abstract:

BACKGROUND:

In spite of the bodyblade (BB®) being used in clinical settings during shoulder and trunk rehabilitation and training for 24 years, there are only five known scientific papers that have described muscle recruitment patterns using the BB®. Moreover, there are no known studies that have examined muscle activity differences between males and females (who both use the bodyblade in the clinic) or between different BB® devices.

HYPOTHESIS/PURPOSE:

The primary purposes of this investigation were to compare glenohumeral and scapular muscle activity between the Bodyblade® Pro (BB®P) and Bodyblade® Classic (BB®C) devices while performing a variety of exercises, as well as to compare muscle activity between males and females. It was hypothesized that glenohumeral and scapular muscle activity would be significantly greater in females compared to males, significantly greater while performing exercises with the BB®P compared to the BB®C, significantly different among various BB® exercises, and greater with two hand use compared to one hand use for the same exercise.

STUDY DESIGN:

Controlled laboratory study using a repeated-measures, counterbalanced design.

METHODS:

Twenty young adults, 10 males and 10 females, performed seven BB® exercises using the BB®C and BB®P, which are: 1) BB®1 – one hand, up and down motion, arm at side; 2) BB®2 – one hand, front to back motion, shoulder flexed 90 °; 3) BB®3 – one hand, up and down motion, shoulder abducted 90 °; 4) BB®4 – one hand, side to side motion, shoulder and elbow flexed 45 °; 5) BB®5 – two hands, side to side motion, shoulders and elbows flexed 45 °; 6) BB®6 – two hands, up and down motion, shoulders flexed 90 °; and 7) BB®7 – two hands, front to back motion, shoulders flexed 90 °. EMG data were collected from anterior and posterior deltoids, sternal pectoralis major, latissimus dorsi, infraspinatus, upper and lower trapezius, and serratus anterior during 10 sec of continuous motion for each exercise, and then normalized using maximum voluntary isometric contractions (MVIC). A two-factor repeated measures Analysis of Variance (p < 0.05) was employed to assess differences in EMG activity between BB® devices (BB®C and BB®P) and genders.

RESULTS:

As hypothesized, for numerous exercises and muscles glenohumeral and scapular EMG activity was significantly greater in females compared to males and was significantly greater in the BB®P compared to BB®C. There were generally no significant interactions between BB® devices and gender. Overall glenohumeral and scapular muscle activity was significantly greater in BB®3 and BB®6 compared to the remaining exercises, but generally not significantly different between using one hand and using two hands.

CONCLUSIONS:

It may be appropriate to employ BB® exercises during shoulder rehabilitation earlier for males compared to females and earlier for the BB®C compared to the BB®P given less overall muscle activation in males and BB®C compared to in females and BB®P. There was generally no difference in muscle activity between performing the BB® with one-hand or two-hands. Differences in muscle activity between exercises generally was the similar regardless if the BB®C or the BB®P was employed.

LEVEL OF EVIDENCE:

Level 2.

 

Abstract:

The repetitive nature of throwing manifests characteristic adaptive changes to the shoulder, scapulothoracic, and hip/pelvis complexes that result in a set of unique physical traits in the overhead throwing athlete. An effective rehabilitation program is dependent upon an accurate evaluation and differential diagnosis to determine the causative factors for the athlete’s pathologic features. The treatment program should be individualized with specific strengthening and flexibility exercises to achieve the dynamic stability that is required for overhead function. In this article we describe the characteristics of the throwing shoulder, along with a multiphased rehabilitation program that allows for the restoration of strength, mobility, endurance, and power and is aimed toward a return to unrestricted sporting activity. We also describe exercises that link the upper and lower extremities because of the importance of core control and leg strength in the development of power during the act of throwing. Additionally, proper throwing mechanics, utilization of pitch counts, appropriate rest, and proper off-season conditioning will help decrease overall injury risk in the overhead throwing athlete.

Abstract:

Shoulder impingement is a progressive orthopedic condition that occurs as a result of altered biomechanics and/or structural abnormalities. An effective nonoperative treatment for impingement syndrome is aimed at addressing the underlying causative factor or factors that are identified after a complete and thorough evaluation. The clinician devises an effective rehabilitation program to regain full glenohumeral range of motion, reestablish dynamic rotator cuff stability, and implement a progression of resistive exercises to fully restore strength and local muscular endurance in the rotator cuff and scapular stabilizers. The clinician can introduce stresses and forces via sport-specific drills and functional activities to allow a return to activity.

Abstract:

The rotator cuff performs multiple functions during shoulder exercises, including glenohumeral abduction, external rotation (ER) and internal rotation (IR). The rotator cuff also stabilizes the glenohumeral joint and controls humeral head translations. The infraspinatus and subscapularis have significant roles in scapular plane abduction (scaption), generating forces that are two to three times greater than supraspinatus force. However, the supraspinatus still remains a more effective shoulder abductor because of its more effective moment arm. Both the deltoids and rotator cuff provide significant abduction torque, with an estimated contribution up to 35-65% by the middle deltoid, 30% by the subscapularis, 25% by the supraspinatus, 10% by the infraspinatus and 2% by the anterior deltoid. During abduction, middle deltoid force has been estimated to be 434 N, followed by 323 N from the anterior deltoid, 283 N from the subscapularis, 205 N from the infraspinatus, and 117 N from the supraspinatus. These forces are generated not only to abduct the shoulder but also to stabilize the joint and neutralize the antagonistic effects of undesirable actions. Relatively high force from the rotator cuff not only helps abduct the shoulder but also neutralizes the superior directed force generated by the deltoids at lower abduction angles. Even though anterior deltoid force is relatively high, its ability to abduct the shoulder is low due to a very small moment arm, especially at low abduction angles. The deltoids are more effective abductors at higher abduction angles while the rotator cuff muscles are more effective abductors at lower abduction angles. During maximum humeral elevation the scapula normally upwardly rotates 45-55 degrees, posterior tilts 20-40 degrees and externally rotates 15-35 degrees. The scapular muscles are important during humeral elevation because they cause these motions, especially the serratus anterior, which contributes to scapular upward rotation, posterior tilt and ER. The serratus anterior also helps stabilize the medial border and inferior angle of the scapular, preventing scapular IR (winging) and anterior tilt. If normal scapular movements are disrupted by abnormal scapular muscle firing patterns, weakness, fatigue, or injury, the shoulder complex functions less efficiency and injury risk increases. Scapula position and humeral rotation can affect injury risk during humeral elevation. Compared with scapular protraction, scapular retraction has been shown to both increase subacromial space width and enhance supraspinatus force production during humeral elevation. Moreover, scapular IR and scapular anterior tilt, both of which decrease subacromial space width and increase impingement risk, are greater when performing scaption with IR (’empty can’) compared with scaption with ER (‘full can’). There are several exercises in the literature that exhibit high to very high activity from the rotator cuff, deltoids and scapular muscles, such as prone horizontal abduction at 100 degrees abduction with ER, flexion and abduction with ER, ‘full can’ and ’empty can’, D1 and D2 diagonal pattern flexion and extension, ER and IR at 0 degrees and 90 degrees abduction, standing extension from 90-0 degrees , a variety of weight-bearing upper extremity exercises, such as the push-up, standing scapular dynamic hug, forward scapular punch, and rowing type exercises. Supraspinatus activity is similar between ’empty can’ and ‘full can’ exercises, although the ‘full can’ results in less risk of subacromial impingement. Infraspinatus and subscapularis activity have generally been reported to be higher in the ‘full can’ compared with the ’empty can’, while posterior deltoid activity has been reported to be higher in the ’empty can’ than the ‘full can’.