Salamh, Paul A. PT, DPT1; Speer, Kevin P. MD2
INTRODUCTION AND EPIDEMIOLOGY
Joint replacement (arthroplasty) is a viable surgical option for individuals with pain and/or impairments of the shoulder related to arthropathy that have been refractory to conservative treatment measures. The shoulder is the third most common joint requiring surgical reconstruction preceded by the knee and hip, respectively (15). The number of shoulder arthroplasties performed annually in the United States increased dramatically (from 18,621 to 46,951) between 2000 and 2008, and it is expected that this number will reach 100,000 by 2020 given the increased aging population (15,18,25).
The most common indication for shoulder arthroplasty (SA) is glenohumeral joint degenerative osteoarthritis. Other indications for SA include, but are not limited to, rheumatoid arthritis, avascular necrosis, and posttraumatic arthritis. Of the individuals undergoing SA, two-thirds are older than 65 years (18) and nearly always have chronic pre-operative impairments as well. With much of the aging population being more active, it is likely that strength and conditioning professionals will encounter more and more of these individuals in the future.
The purpose of this article is to provide the strength and conditioning professional with an overview of postoperative rehabilitation considerations for clients who have had a total SA (TSA) procedure with the rotator cuff intact. We will not discuss the reverse TSA, as this procedure is performed on individuals having a deficient rotator cuff and will not benefit from vigorous resistance training of the shoulder (14,17). It is necessary to discuss the perioperative procedures and the available evidence surrounding this topic to lay the groundwork from which a post-rehabilitation exercise program can be designed. Progression and advancement of post-rehabilitation variables will be highlighted in the context of safety and consensus.
SURGICAL TECHNIQUE AND IMPLICATION
Various surgical techniques and a variety of prosthetic designs exist for performing SA. Regardless of surgical technique, and to some degree prosthetic design, SA has been shown to dramatically reduce pain and yield improvements in shoulder-specific measures of function (5,7,23). Although there are variations among SA procedures, we will discuss the TSA and humeral hemiarthroplasty (HHA).
The purpose of the TSA is to replace the affected articulating joint surfaces with prosthetic components while attempting to maintain normal glenohumeral joint biomechanics. The humeral component is a metal implant that is either press fit (driven into) into the humerus or cemented. There is slightly greater variation within the polyethylene glenoid component but most all are implanted using cement as a grout to ensure fixation (Figure 1). The use of cement is preferred over screw fixation given the narrow width and depth of the bone present surrounding the glenoid, which can be further compromised with the presence of osteoarthritis. The bone ingrowth is also not predictable with the use of screw fixation. Even with the use of cement, glenoid component loosening and/or failure is one of the most common long-term complications of TSA, which can be attributed to a number of different factors (21,28).
Procedures for TSA vary from surgeon to surgeon, however, postoperative considerations and precautions are often similar (27). A brief discussion of the general procedure is necessary to understand the postoperative restrictions and persistent impairments. The procedure generally is initiated with an incision, starting just lateral to the coracoid process and extending 10–15 cm distally (down) along the anterior upper arm (Figure 2). An interval is then created between the deltoid and pectoralis major muscles, and the deltoid is moved laterally. A portion of the pectoralis major tendon and latissimus dorsi tendon is then incised or released at where they attach to the proximal humerus. A tenotomy is performed to the tendon of the long head of the biceps. A subscapularis tenotomy (incision of the tendon) must be performed, where it attaches to the humerus to access the glenohumeral joint. The infraspinatus, teres minor, and supraspinatus remain intact. At this point, the shoulder is progressively externally rotated and dislocated.
An oscillating saw is used to make a cut along the anatomical neck of the proximal humerus. The humerus is then sized for the appropriate stem (Figure 1), and this is press fit into the medullary cavity or canal of the humerus, most often times without the use of cement or any additional hardware. The glenoid is then reamed (shaped) to fit the shape of the glenoid component. One or more small pilot holes will then be drilled into the glenoid depending on what type of component is used (keeled or peg design). The glenoid component (Figure 1) is then cemented to the glenoid.
The joint is then relocated and examined for hyperlaxity (greater than normal joint mobility) and appropriate fit of the prosthetic components. Humeral head trials are used to best replicate normal anatomy. Figure 3 depicts the placement of both the humeral and glenoid components. At this time, if any other procedures are warranted, such as rotator cuff tendon repair and capsular releases for soft tissue balance, they are performed. The subscapularis, rotator interval, pectoralis major, and latissimus dorsi muscles are then repaired (sutured back to their original insertion) and the deltopectoral interval closed. A drain will often times be placed before final closure of the skin. A radiograph taken postoperatively of a right TSA can be seen in Figure 4.
Although the majority of this article focuses on the perioperative and postoperative considerations after TSA, it is important to briefly discuss HHA. HHA consists of replacing the humeral head (ball) of the glenohumeral joint and leaving the glenoid intact. This is often times done in younger individuals or those individuals having significant wearing of only one of the articulating surfaces, which could be the result of an irreparable rotator cuff tear. However, replacing only the humeral portion can sometimes lead to increased wear of the glenoid over time (7,21). Given that this procedure is performed on younger individuals, it is most likely that they will require revision surgery of the humeral component, and if the glenoid is worn significantly, it can make it difficult to implant the glenoid component and lead to increased pain and decreased function over time (7,28).
Physical therapists are the primary rehabilitation providers throughout the perioperative and postoperative care following TSA. Physical therapists integrate a patient care model, where they independently examine, evaluate, posit a prognosis, and provide interventions in an attempt to optimize outcomes after these procedures (1). Physical therapists must recognize that surgeons often have strict requirements (protocols) that their patients must follow postoperatively and remain aware of these requirements when determining interventions.
The progressive rehabilitation protocol following TSA is intentionally designed primarily to protect the repair of the subscapularis tendon that was released and then repaired during the surgical procedure. It is the belief of the authors that many individuals feel as though the progression and length of the rehabilitation process is the result of the placement of prosthetic components when in fact it is because of the structures compromised and repaired to access the glenohumeral joint during surgery. The prosthesis is stable from time zero. Jackson et al. (13) examined the integrity and function of the subscapularis in individuals after TSA at 6 months postoperatively. They found that of the 15 shoulders examined, 7 had complete ruptures of their repaired subscapularis tendon.
The following is a general overview of the protocol used by the primary author when treating patients after TSA, keeping in mind that different surgeons have different protocols, and this is not intended for use with all patients after TSA. Although there is variation among protocols, there is agreement in the literature that a deliberate and progressive protocol tailored to each individual is warranted after TSA (2,4,12,27).
For the first 3 weeks after surgery, phase I, individuals are under strict sling wear precautions and have no form of physical therapy but are encouraged to perform active elbow, wrist, and hand range of motion. During weeks 4 through 7 after surgery, phase II, individuals begin formal physical therapy with an emphasis on protecting the subscapularis repair while initiating passive (therapist moves arm for patient to prevent stiffness) and active assisted shoulder motion within restricted ranges. Active assistive range of motion is performed by using the uninvolved extremity to assist the operative shoulder through a particular movement. During this time, individuals are discouraged from wearing their sling but are not to perform any active range of motion of the shoulder on dry land (pool is allowed within limitations). Exercises that patients may be asked to do as part of their home exercise program include scapular motions, pendulum exercises, passive stretches within certain limits, activities of daily living below shoulder level, and isometric activation of rotator cuff and deltoid muscles in a neutral position.
During weeks 8 through 12, phase III, full passive and active shoulder range of motion is sought to be achieved (although usually not achieved until 4–6 months) and dry land active range of motion is initiated. Initially active range of motion is performed without resistance to establish normal joint mechanics before adding weights. These individuals will have a shoulder that is severely deconditioned given the chronicity of their pathology. Much of the strengthening initially is centered on the rotator cuff, particularly internal rotation, and the periscapular musculature. This helps to build a strong foundation for the shoulder to function. A balance of strength and flexibility in the shoulder is sought to decrease early wear and failure of the prosthetic components and to prevent rotator cuff tendon distortion.
Twelve weeks after surgery, phase IV, patients are encouraged to maintain their passive range of motion and progress to an independent strengthening program. It is shortly after this point that patients are often discharged but are followed annually with radiographs.
POST-REHABILITATION COORDINATION OF CARE
Although physical therapists technically provide the rehabilitation care for individuals, as they continue to have functional limitations related to initial illness, injury, or surgery, they are often limited in their ability to guide a patient to complete recovery for various reasons. In this instance, the physical therapist will counsel the patient and encourage them to pursue activities that will further improve their function and quality of life. Patients at this stage are often faced with the challenge of bridging activities from a regimented health care professional driven rehabilitation process to a self-guided program. The transition to an independent program may be quite daunting to the patient who is unfamiliar with the principles of safe and effective exercise. This provides an opportunity for the strength and conditioning professional familiar with TSA to bridge this gap. An open line of communication between the physical therapist and strength and conditioning professional can allow the patient to achieve their full potential after TSA. This communication is critical, as often times, patients are not able to adequately articulate information to their strength and conditioning professional regarding their procedure and/or their limitations.
POST-REHABILITATION EXERCISE CONSIDERATIONS
An understanding of the most common residual impairments is essential when designing a post-rehabilitation program for clients after TSA. A common problem after shoulder surgery, regardless of the procedure, is postoperative shoulder stiffness (3,8,11,26). Although it is the experience of the primary author that individuals undergoing TSA have less difficulty regaining range of motion initially than those undergoing arthroscopic or open rotator cuff repair; it is still imperative to restore and maintain as much glenohumeral joint range of motion as possible. It is important to note that although the literature consistently shows significant improvements in strength, range of motion, and functional outcomes after TSA, full range of motion and restoration of full strength are generally not obtained and in some cases not expected (16,24).
When considering restoration of range of motion after TSA, it is also important to note that 1 complication or problem postoperatively is posterior and anterior subluxation and/or dislocation. Many surgeons realize this potential during the procedure, as the posterior joint capsule distorts because of arthritis and will often times perform a posterior capsulorrhaphy, which is a procedure that tightens the posterior capsule of the shoulder to increase stability (10,19). Anterior dislocation is a risk early on when the subscapularis is not fully healed as it helps to prevent anterior translation of the humeral head in the glenoid (13).
A greater potential limitation that has been alluded to previously in this article is the integrity and function of the repaired subscapularis. Given that during the surgical procedure, two of the main internal rotators of the glenohumeral joint, the subscapularis, and pectoralis major were incised and repaired, it is very common to see individuals with weakness in isolated internal rotation against resistance and with motions of which internal rotation is a component of.
Formal postoperative rehabilitation programs follow a particular progression of avoidance and protection of specific motions that gradually are lifted as the individual advances through the process. However, it is imperative that the strength and conditioning professional be aware of these precautions when designing a post-rehabilitation program. Specific to TSA, the strength and conditioning professional should be cognizant of the predilection for stiffness and activities that may cause premature wear to prosthetic components.
Zumstein et al. (28) reported that 7% of complications after TSA involved instability. Subluxation and/or dislocation after TSA can occur both posteriorly and anteriorly (13,23). Posterior subluxation and/or dislocation seen early on may be because of malposition of the prosthesis and/or inadequate protection of the shoulder. In the latter stages, it can be a result of malposition of the humeral prosthesis, failure of the glenoid component, and/or over tightening of the anterior structures such as the subscapularis. Anterior subluxation and/or dislocation after TSA can be seen early in the rehabilitation process secondary to inadequate protection of the subscapularis repair. Because the subscapularis is released and then repaired, it is at risk for being torn if not well protected and can lead to a decrease in shoulder stability anteriorly (13). In the later stages, anterior subluxations, although rare, can be the result of posterior shoulder tightness in combination with or in isolation of decreased integrity of the subscapularis. This will most likely occur in positions of combined horizontal extension and external rotation of the shoulder (Figure 5).
Given the risk for both anterior and posterior subluxations, it is imperative that these risk factors be evaluated before the implementation of a post-rehabilitation program. A clear and open communication between the physical therapist and strength and conditioning professional regarding this topic can help to prevent a potential pitfall.
Component wear and loosening
Failure (loosening) and wear of the glenoid component is the most common long-term complication after TSA, which can result in decreased function, increased pain, and the need for further surgery (21,23). Numerous variables can contribute to premature glenoid failure, some of which physical therapists and strength and conditioning professionals can help to mitigate by using a progressive post-rehabilitation program at a moderate activity level using low resistance and high repetitions. Weight bearing through the shoulder prosthesis (i.e., closed chain exercises such as push-ups and dips), glenohumeral instability, rotator cuff insufficiency, and eccentric loading have all been shown to contribute to glenoid loosening (7,21,23). Postoperatively, strength and conditioning professionals must recognize that there is a balance between the amount of activity needed to maintain cardiovascular health and overall fitness and the amount and type of activity that could potentially lead to premature prosthetic wear (21). More specific questions regarding a particular individual's precautions and their recommended activity level can be answered by their physical therapist or surgeon.
EXERCISE PROGRAM DEVELOPMENT
There is little evidence that has investigated specific post-rehabilitation exercise considerations for individuals who have undergone TSA outside of general postoperative protocols. The following are recommendations based on the residual impairments that may be present among these individuals, current literature, and the authors' experience in a shoulder specialty practice. The strength and conditioning professional should refer to the physical therapist and orthopedic surgeon regarding both the timing and type of certain activities appropriate for each patient after TSA.
Resistance training is a key component of a post-rehabilitation program for individuals after TSA and HHA. From this point forward, TSA and HHA will be collectively referred to as SA. Many individuals may still have muscle performance deficits that would benefit from a regular resistance program targeting specific musculature. Even in the later stages of rehabilitation, the shoulder, as a whole, is weak given the chronic nature of their shoulder pathology.
With both the pectoralis major and subscapularis incised and then repaired during the surgical procedure, internal rotation will most likely be weak. Of the 2 muscles mentioned above, the subscapularis will be the main limiting factor contributing to weakness with internal rotation. Given the high incidence of subscapularis tears after repair, 47% as reported by Jackson et al. (13), this poses a significant challenge for the strength and conditioning professional as overzealous conditioning efforts may cause a tear.
When developing exercises to target the subscapularis, form is critical among this population. Among individuals with significant internal rotation weakness, one must attempt to optimize subscapularis activation while minimizing the contribution of the pectoralis major by adhering to strict form during the exercises. A majority of these individuals will not be able to tolerate any more resistance than that of thin elastic bands and in severe cases of weakness, may only be able to perform isometric activation without altered mechanics. Those with an ability to tolerate thin elastic bands may progress to more advanced exercises with strict adherence to form. An example of a typical progression for subscapularis strengthening after SA can be seen in Figure 6 consisting of isometric internal rotation, resisted internal rotation with bands, and side-lying internal rotation with resistance. Another exercise that has shown increased activity within the subscapularis muscle is the dynamic hug but should be used with those individuals demonstrating relatively good rotator cuff strength (6). As with any resistance program, proper warm-up and flexibility exercises can help to reduce the risk of potential injury.
Another common area of weakness seen among most individuals with shoulder pathology is that of the periscapular muscles (rhomboids; upper, middle, and lower trapezius; and latissimus dorsi). When targeting these muscles, it is important to realize that these individuals will also more than likely have degenerative necks. Many exercises designed to strengthen this area are performed in prone (lying on stomach) or standing. It is important to ensure that individuals are able to move through the entire range of motion without altered shoulder mechanics or pain and no resistance before resistance is added. In theory, performing shoulder exercises with resistance through partial range of motion in an individual who is unable to move through the entire range of motion without resistance can be harmful. Good examples of exercises to strengthen these areas may include seated rows and shrugs. Once good periscapular shoulder strength is present in conjunction with strength and stability of the rotator cuff, then more advanced exercises may ensue.
When developing a resistance program, the strength and conditioning professional must remain cognizant of the fact that most individuals undergoing TSA are aged 65 years and older (15). It is evident in the literature and through surgical examination that the shoulder goes through senescent or age-related changes (22). Of importance to the topic at hand is the presence of fatty infiltration and degeneration of rotator cuff tendons among the aging population (22). These biologic changes occur to some degree regardless of use or nonuse of these muscles. Simply put, this means that as we age, our rotator cuff tendons become more susceptible to injury and muscles become weaker. This principle is important to understand when developing an upper body resistance program for anyone, particularly, among individuals after SA.
It is also important to realize that a majority of individuals undergoing SA have been dealing with pain and limitations in the shoulder for several years. The chronic nature of shoulder pathologies warranting SA lends itself to a myriad of deficits associated with the shoulder and neck. These individuals will most likely have decreased rotator cuff strength and/or activation, weakness in periscapular musculature, and stiffness throughout the joint ultimately leading to poor mechanics. Understanding that these factors will most likely still be present to some degree at the time when the strength and conditioning professional will begin working with them is imperative.
Because of the information presented above, there are certain exercises and/or positions that are advised against when performing resistance exercises in this population. Although individuals having had SA may be able to perform these exercises with good mechanics and no pain, they pose risk to injury and/or early wear of prosthetic components. These exercises include closed chain exercises, such as dips and push-ups, and other weight bearing exercises. Other considerations include limiting shoulder horizontal extension that is present with latissimus pull-downs, overhead military press, straight bar bench press, and traditional rear squats, as they all place the shoulder in compromising positions under load. It is also recommended that individuals do not use resistance bands above their head. Generally, the use of machines is preferred to free weights among these individuals, as there is a concern with shoulder instability secondary to rotator cuff weakness. The use of machines allows for the motion of the exercise to be more confined, whereas free weights will rely more heavily on the intrinsic shoulder musculature for stabilization, which may be weak among these individuals.
Overall, a resistance program should be developed that begins with strengthening the rotator cuff and periscapular musculature to provide a stable base for the larger movers of the shoulder (pectoralis and deltoids) to be strengthened, while ensuring proper shoulder mechanics that can help individuals reach their full strength potential after SA.
Cardiovascular exercise is a vital part of any fitness program. One must consider the same general principles used for any individual when developing a routine for this population. Controlling variables such as duration, intensity, and frequency are appropriate for the individual's initial cardiovascular fitness level.
Those having undergone SA can both benefit and tolerate most forms of cardiovascular exercise in the later stages of their recovery. Early cardiovascular exercise may consist of the use of a recumbent bike that may start as early as 6 weeks postoperatively. Traditional forms of cardiovascular exercise such as walking, jogging, and running present no undue stress on the shoulder when performed at 3 months postoperatively and beyond. Even the use of an elliptical machine can be a good form of cardiovascular exercise, while helping to incorporate the shoulder musculature in the latter stages. Swimming, however, must be looked at somewhat more closely, as there are a variety of different strokes, all requiring different degrees of strength and flexibility of the shoulder. Generally the more challenging motions for the shoulder are the backstroke and freestyle (front crawl) stroke, which are often advised against, whereas the breaststroke, particularly, and sidestroke are advocated at 3–6 months postoperatively in most cases.
Flexibility is arguably the most important component of a post-rehabilitation exercise program for those undergoing SA. Gaining near full range of motion in the shoulder should be sought before shifting the emphasis to resistance training. There may be residual stiffness at or near the end range of motions in the shoulder of those who are in the latter stages of SA rehabilitation, about the time they may seek the council of strength and conditioning professionals. Aside from residual tightness at the end range of most shoulder motions, there are particular areas of the shoulder that are more prone to developing stiffness than others. This makes dealing with stiffness in the shoulder a significant challenge.
It is this situation that makes it imperative to have considerable communication between the physical therapist and strength and conditioning professional. For example, if an individual thought to have global shoulder stiffness is advised to perform a horizontal adduction stretch (cross-body stretch) as part of their flexibility program without proper assessment of posterior shoulder integrity, this could lead to further hyperlaxity of the posterior shoulder and create a situation that is more likely to lead to posterior subluxation. Moreover, an individual who has an incompletely healed subscapularis may injure themselves performing motions that require combined shoulder abduction, horizontal extension, and external rotation (Figure 5). It is for this reason that individuals are advised not to perform motions that involve combined shoulder abduction, horizontal extension, and external rotation as seen with exercises such as military press (behind or in front of the neck), traditional rear squats, latissimus pull-downs, and straight bar bench press.
Communication between the physical therapist and strength and conditioning professional regarding the areas of shoulder tightness and hyperlaxity for each individual can help promote an effective and comprehensive flexibility program while maintaining shoulder integrity.
RETURN TO RECREATIONAL SPORTS AND EXERCISE
Recreational sports and exercise can contribute to the overall power, strength, agility, endurance, and overall mental health for individuals after SA. However, it is important to understand that a high level of activity can potentially lead to early prosthetic wear. Sports and/or activities that can lead to early prosthetic wear are those that involve overhead motions such as racquet sports, swimming, baseball, softball, and volleyball. Although individuals may be able to participate in these sports at a competitive level for their age group without pain, it can lead to significant early wear of prosthetic components. A recent study by Golant et al. (9) revealed that only 45.7% of orthopedic surgeons surveyed allowed patients to return to sport at 3–6 months postoperative SA. It is also recommended that contact sports be avoided by patients after SA (9,20). These sports include football, rugby, lacrosse, hockey, basketball, and martial arts.
Strength and conditioning professionals must recognize the balance between the benefits of recreation sports and exercise and early prosthetic component wear. Many alternatives exist to the aforementioned sports that do not place as much stress on the prosthesis but still provide the same benefits, golf being one example. Also, some of the aforementioned activities can be modified, such as choosing a different swimming stroke (such as the breast stroke) so that an overhead motion is not required and thus does not predispose the individual to premature prosthetic wear. Presently, there is no evidence that examines prosthetic life span for individuals participating and/or not participating in particular sports or activities after SA.
The number of joint replacement surgeries performed annually continues to rise and will most likely continue to do so in years to come. Individuals who have undergone SA often require an extensive bout of care to restore normal physical function because the preoperative condition was so chronic. Although a formal rehabilitation program carried out by a physical therapist has been shown effective at allowing these individuals to return to near normal physical function postoperatively, there are usually functional limitations that are present beyond discharge. These individuals with functional limitations or those who seek a transition from formal rehabilitation to a daily fitness program can benefit from a guided post-rehabilitation exercise program.
This presents an opportunity for the strength and conditioning professional to help bridge the gap between any residual impairment that may exist at the post-rehabilitation stage and the point at which the individual's optimal physical function is realized. To realize this potential, it is critical that the strength and conditioning professional have a working knowledge of limitations, precautions, and considerations for individuals having undergone SA. An emphasis on maintaining optimal range of motion and creating a strong foundation of strength within the intrinsic shoulder musculature can help prevent further shoulder pathology in the future. Direct communication between the physical therapist and strength and conditioning professional can allow for a mindful and progressive post-rehabilitation program aimed at restoring function.
1. Association APTA. Guide to Physical Therapy Practice. Alexandria, VA: American Physical Therapy Association, 2001.
2. Brems JJ. Rehabilitation following total shoulder arthroplasty. Clin Orthop Relat Res 307: 70–85, 1994.
3. Brislin KJ, Field LD, Savoie FH III. Complications after arthroscopic rotator cuff repair. Arthroscopy 23: 124–128, 2007.
4. Brown DD, Friedman RJ. Postoperative rehabilitation following total shoulder arthroplasty. Orthop Clin North Am 29: 535–547, 1998.
5. Carter MJ, Mikuls TR, Nayak S, Fehringer EV, Michaud K. Impact of total shoulder arthroplasty on generic and shoulder-specific health-related quality-of-life measures: A systematic literature review and meta-analysis. J Bone Joint Surg Am 94: e127, 2012.
6. Escamilla RF, Yamashiro K, Paulos L, Andrews JR. Shoulder muscle activity and function in common shoulder rehabilitation exercises. Sports Med 39: 663–685, 2009.
7. Favard L, Katz D, Colmar M, Benkalfate T, Thomazeau H, Emily S. Total shoulder arthroplasty-arthroplasty for glenohumeral arthropathies: Results and complications after a minimum follow-up of 8 years according to the type of arthroplasty and etiology. Orthop Traumatol Surg Res 98: S41–S47, 2012.
8. Franceschi F, Papalia R, Palumbo A, Vasta S, Maffulli N, Denaro V. Management of postoperative shoulder stiffness. Sports Med Arthrosc 19: 420–427, 2011.
9. Golant A, Christoforou D, Zuckerman JD, Kwon YW. Return to sports after shoulder arthroplasty: A survey of surgeon's preferences. J Shoulder Elbow Surg 21: 554–560, 2012.
10. Habermeyer P, Magosch P, Lichtenberg S. Recentering the humeral head for glenoid deficiency in total shoulder arthroplasty. Clin Orthop Relat Res 457: 124–132, 2007.
11. Huberty DP, Schoolfield JD, Brady PC, Vadala AP, Arrigoni P, Burkhart SS. Incidence and treatment of postoperative stiffness following arthroscopic rotator cuff repair. Arthroscopy 25: 880–890, 2009.
12. Hughes M, Neer CS II. Glenohumeral joint replacement and postoperative rehabilitation. Phys Ther 55: 850–858, 1975.
13. Jackson JD, Cil A, Smith J, Steinmann SP. Integrity and function of the subscapularis after total shoulder arthroplasty. J Shoulder Elbow Surg 19: 1085–1090, 2010.
14. Jobin CM, Brown GD, Bahu MJ, Gardner TR, Bigliani LU, Levine WN, Ahmad CS. Reverse total shoulder arthroplasty for cuff tear arthropathy: the clinical effect of deltoid lengthening and center of rotation medialization. J Shoulder Elbow Surg 21: 1269–1277, 2012.
15. Kaback LA, Green A, Blaine TA. Glenohumeral arthritis and total shoulder replacement. Med Health R I 95: 120–124, 2012.
16. Kasten P, Maier M, Wendy P, Rettig O, Raiss P, Wolf S, Loew M. Can shoulder arthroplasty restore the range of motion in activities of daily living? A prospective 3D video motion analysis study. J Shoulder Elbow Surg 19: 59–65, 2010.
17. Kempton LB, Ankerson E, Wiater JM. A complication-based learning curve from 200 reverse shoulder arthroplasties. Clin Orthop Relat Res 469: 2496–2504, 2011.
18. Kim SH, Wise BL, Zhang Y, Szabo RM. Increasing incidence of shoulder arthroplasty in the United States. J Bone Joint Surg Am 93: 2249–2254, 2011.
19. Kontakis GM, Tozakidou M, Karantinos J. Stabilisation of a posteriorly unstable glenohumeral joint during total shoulder arthroplasty: A novel capsulorrhaphy technique. Acta Orthop Belg 72: 353–355, 2006.
20. Magnussen RA, Mallon WJ, Willems WJ, Moorman CT III. Long-term activity restrictions after shoulder arthroplasty: An international survey of experienced shoulder surgeons. J Shoulder Elbow Surg 20: 281–289, 2011.
21. Matsen FA III, Clinton J, Lynch J, Bertelsen A, Richardson ML. Glenoid component failure in total shoulder arthroplasty. J Bone Joint Surg Am 90: 885–896, 2008.
22. Nho SJ, Yadav H, Shindle MK, Macgillivray JD. Rotator cuff degeneration: Etiology and pathogenesis. Am J Sports Med 36: 987–993, 2008.
23. Norris TR, Iannotti JP. Functional outcome after shoulder arthroplasty for primary osteoarthritis: A multicenter study. J Shoulder Elbow Surg 11: 130–135, 2002.
24. Sperling JW, Kaufman KR, Schleck CD, Cofield RH. A biomechanical analysis of strength and motion following total shoulder arthroplasty. Int J Shoulder Surg 2: 1–3, 2008.
25. Vavken P, Sadoghi P, von Keudell A, Rosso C, Valderrabano V, Muller AM. Rates of radiolucency and loosening after total shoulder arthroplasty with pegged or keeled glenoid components. J Bone Joint Surg Am 95: 215–221, 2013.
26. Vezeridis PS, Goel DP, Shah AA, Sung SY, Warner JJ. Postarthroscopic arthrofibrosis of the shoulder. Sports Med Arthrosc 18: 198–206, 2010.
27. Wilcox RB, Arslanian LE, Millett P. Rehabilitation following total shoulder arthroplasty. J Orthop Sports Phys Ther 35: 821–836, 2005.
28. Zumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: A systematic review. J Shoulder Elbow Surg 20: 146–157, 2011.