Total Shoulder Arthroplasty

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Total Shoulder Arthroplasty

Chris A. Sebelski and Carlos A. Guanche

Clinical Evaluation

History

The most common complaint in patients with advanced osteoarthritis (OA) of the shoulder is pain—more specifically, night pain. Most often, the pain is insidious in its onset, although an occasional patient will report acute symptomatology only to discover severe osteoarthritic changes in the glenohumeral (GH) joint. In many cases night pain is a major problem; specifically, difficulty with lying on the affected side is a common complaint.1

A careful history should be taken with respect to prior injuries and prior surgical procedures. For a total shoulder replacement to be viable and functional, an intact rotator cuff is necessary. In certain patients with long-standing rotator cuff disruption, the initial clinical signs are progressive pain that comes with the developing secondary arthropathy.2

Another area of concern is whether the patient has undergone any prior stabilization procedures. The reason this is important to remember is that preferential wear of certain parts of the glenoid can occur in long-standing cases that have undergone excessive capsular-tightening procedures.3 Most commonly, this is posterior wear. In addition, in certain types of stabilization procedures, a variety of bony transfer procedures are performed, including a lateralization of the lesser tuberosity and a transfer of the coracoid transfer. As a result, the surgical exposure in these cases can be difficult because of the distorted anatomy.

Physical Examination

The most important predictor of the outcome of a total shoulder replacement is the preoperative range of motion (ROM).4,5 imageIt is therefore incumbent on the physician to document all directions of the patient’s motion and to discuss the implications of lack of mobility on the overall outcome. Another important aspect is the integrity of the rotator cuff; a successful standard replacement depends very heavily on the presence of an intact cuff. The supraspinatus, infraspinatus, teres minor, and the subscapularis should all be carefully examined. If any doubt exists as to the function of the cuff, magnetic resonance imaging (MRI) is indicated. In cases in which a rotator cuff disruption coexists with severe OA, a determination should be made as to the possibility of repairing the cuff. In those cases in which significant chronicity of the cuff is noted, either by history or MRI examination, a simple hemiarthroplasty or a reverse total shoulder replacement (in cases in which pseudoparalysis of the arm exists) should be considered.6

Surgical Indications And Considerations

Those patients with refractory pain and limitation of motion that do not respond to conservative methods of treatment (i.e., a trial of physical therapy, antiinflammatory medications, activity modification, avoidance of inciting factors, and intraarticular corticosteroid injections) are candidates for shoulder replacement. Ideally, the patient’s age should also fit within the acceptable parameters for a joint replacement. Although the ideal patient should be over the age of 65 and have a relatively limited activity level, the reality is that many patients do not fit such criteria.

In cases in which the patient’s age is significantly under 65 years or the activity level is not commensurate with their age, avoiding the surgery should be considered (in some of these patients, a case can be made for fusion of the joint). In addition, a spectrum of replacement procedures can be used, including a partial humeral replacement (classically termed a hemiarthroplasty), a hemiarthroplasty with a biologic resurfacing of the joint, and a standard total shoulder replacement; in more severe cases of patients with concurrent unrepairable rotator cuff tears, a reverse total shoulder can be used.

Surgical Procedure

The choice of anesthesia depends on the clinical experience of the surgeon and anesthesiologist. Ideally, the anesthesia would include an interscalene block, either by itself or as a supplement to a general anesthetic. The use of such blocks has been shown to significantly affect the patient’s postoperative course in a very positive manner.7 In cases in which interscalene anesthesia is not used, the preemptive administration of a long-acting anesthetic (Marcaine) is also well-founded in the literature and has been shown to positively affect recovery.8

The standard approach to a shoulder replacement operation includes positioning the patient in a semirecumbent (beach chair) position, with a small bolster under the scapula to effectively stabilize the glenoid for exposure. In addition, the operative shoulder should be examined under anesthesia with all of the directions of motion measured and documented. Finally, it is important to ensure that the operative arm can be extended and rotated appropriately for delivery of the humeral head and subsequent resection during the surgical procedure (Fig. 7-1). This is called the ability to shotgun the arm into this position.

The standard incision is a deltopectoral approach that is typically centered immediately lateral to the coracoid process of the scapula and extends down the proximal arm, avoiding the axilla (Fig. 7-2). It is important to allow for distal exposure of the wound should the need arise for a more complex humeral approach, such as in complications associated with humeral shaft fractures on prosthetic insertion.

The exposure includes identification of the deltopectoral interval with identification of the cephalic vein and subsequent medial retraction. The pectoralis tendon is identified laterally and, in severe cases, released for a distance of 1 to 2 cm for improved GH joint exposure. In addition, the deltopectoral interval is exposed in its entirety from the leading edge of the clavicle to the lower end of the pectoralis muscle. Commonly, significant subdeltoid adhesions need to be released for proper delivery of the humeral head out of the wound.

After complete exposure of the deltopectoral interval, the conjoint tendon is identified and released at its proximal portion for a distance of 1 cm, and the medial retractor is placed behind the tendon. Care should be taken to protect the musculocutaneous nerve when performing this maneuver.

The subscapularis tendon is now identified and released from superior to inferior, beginning at its lateral corner. The tendon is released directly off the lesser tuberosity and retracted medially. The release continues inferiorly, cauterizing the vascular leash consisting of the anterior inferior humeral circumflex vessels and proceeding along the inferior humeral head, while externally rotating the humerus (Fig. 7-3). The extent of the release is variable. However, the requirement is that the entire humeral head can be delivered for resection and that adequate exposure of the glenoid is possible if resurfacing of that portion is being performed.

Once the exposure is complete, a variety of humeral resection techniques can be used, depending on the manufacturer’s individual surgical protocol. The design the author of this chapter uses involves resection of the humeral head at its anatomic base. Before completing this cut, the head must be exposed and all peripheral osteophytes should be removed to appropriately resect the head in an anatomic fashion (Fig. 7-4).

After resection of the head, the humeral canal is prepared for the prosthetic device being implanted. A series of reamers are inserted down the medullary canal, stopping when the appropriate-sized device is used. The size is typically judged from templates that measure the size of the medullary canal based on their radiographic dimension. However, ultimately the choice is made intraoperatively, based on the surgeon’s experience as he or she advances the device into the shaft.

The humeral metaphysis is then prepared with a series of broaches that contour the proximal humerus for insertion of the actual component. The type of implant varies, with two major types being available: (1) cemented and (2) cementless. A cementless device uses the body’s ability to grow bone into some of its surfaces; these surfaces are often prepared with a sintered metal (Fig. 7-5). In a cemented device, the prosthesis is implanted using polymethylmethacrylate cement for immediate fixation of the device. The theoretic advantages of one device over another are beyond the scope of this chapter; the reader is directed to the appropriate references.911

Attention is now directed to the glenoid. It is important to be able to access the entire area of the glenoid from anterior to posterior and superior to inferior to effectively prepare the bony surface for the implant. The capsule of the joint is excised, beginning with the most anterior, superior portion and extending inferiorly and posteriorly as far as necessary to allow for adequate exposure (Fig. 7-6). Once the exposure is gained, the central point of the glenoid is identified; then the surface is prepared for accepting the actual component. Finally, the device is cemented into position using polymethylmethacrylate cement.

The final decisions that need to be made include choosing the appropriately sized humeral head component to allow a relatively normal passive range of motion (PROM) with minimal to no instability before closure of the subscapularis muscle tendon (Fig. 7-7). Once the appropriate head is chosen and implanted, the subscapularis muscle tendon is reapproximated to the lesser tuberosity with the use of sutures that have been prepositioned through the bone before implantation of the humeral component (Figs. 7-8 and 7-9). The repair of the subscapularis is the critical element that needs attention during the first 6 weeks because of the importance of the subscapularis for component stability and overall shoulder girdle strength. Moreover, a disruption of the repair is notoriously difficult to diagnose in the early phases and extremely difficult to salvage when a chronic diagnosis is made.

The closure is done in layers, with a subcuticular skin closure protected by Steri-Strips being the final step. In some cases a drain may be exteriorized via a separate stab wound incision. This is typically removed on the first postoperative day. The final and perhaps most important part of the surgical procedure occurs at this time. The surgeon takes the arm through a PROM to assess the overall total motion possible without joint instability of disruption of the subscapularis tendon repair. This ROM will be used to guide the limits that will be allowed in the first phases of rehabilitation. Final radiographs are typically obtained immediately postoperatively to ensure an appropriate position of all the components and also to ascertain that no intraoperative complications such as a humeral shaft fracture have occurred (Fig. 7-10).

Therapy Guidelines For Rehabilitation

Total shoulder arthroplasty is performed less frequently than hip or knee total joint replacements in the United States.8 There is evidence that a decreased hospital stay and a higher likelihood of discharge to home may be associated with those patients treated in surgical centers with a higher volume of total shoulder arthroplasties.12,13 No attempts to correlate the patient’s functional limitations and impairments on discharge have been found with length of stay or “successful discharge.” The clinician must use physiologic healing principles to assist in gaining functional return of shoulder ROM following surgical intervention.

Successful rehabilitation of a total shoulder arthroplasty (TSA) depends in large part on the collegial communication between the surgeon and the therapist. Appropriate rehabilitation needs to recognize and address the preoperative history and impairments, the surgical technique, prosthetic type, and the surgeon’s assessment of the tissue status upon finalization of the repair.

The majority of these issues dictate the postoperative precautions and guidelines that are placed upon the rehabilitation timeline to ensure that protection of the position of the prosthesis and the appropriate healing of the subscapularis occurs (Box 7-1).

The patient and therapist must be aware that the primary goal for nontraumatic TSA is pain relief. It appears that the achievement of functional ROM goals are more achievable today than 5 years ago; however, the improvement of ROM is not as well substantiated in the literature as the successful achievement of decreased pain.14 The preoperative diagnosis also impacts the postoperative outcome. Completion of a TSA because of primary OA is more likely to result in functional use of the upper extremity than those completed as a result of trauma, rheumatoid arthritis of the GH joint, capsulorrhaphy, arthropathy, or rotator cuff arthropathy (Box 7-2).15

Box 7-2

Preoperative Factors for Better Outcomes Following TSA

Better Outcomes

Worse Outcomes

Data from Hettrich CM, et al: Preoperative factors associated with improvements in shoulder function after humeral hemiarthroplasty. J Bone Joint Surg Am 86-A(7):1446-1451, 2004; Iannotti JP, Norris TR: Influence of preoperative factors on outcome of shoulder arthroplasty for glenohumeral osteoarthritis. J Bone Joint Surg Am 85-A(2):251-258, 2003; Matsen FA III, et al: Correlates with comfort and function after total shoulder arthroplasty for degenerative joint disease. J Shoulder Elbow Surg 9(6):465-469, 2000; Edwards TB, et al: The influence of rotator cuff disease on the results of shoulder arthroplasty for primary osteoarthritis: Results of a multicenter study. J Bone Joint Surg Am 84-A(12):2240-2248, 2002; Franklin JL, et al: Glenoid loosening in total shoulder arthroplasty. Association with rotator cuff deficiency. J Arthroplasty 3(1):39-46, 1988; Rozencwaig R, et al: The correlation of comorbidity with function of the shoulder and health status of patients who have glenohumeral degenerative joint disease. J Bone Joint Surg Am 80(8):1146-1153, 1998.

To prognosticate functional outcomes, including achievement of active ROM against gravity, the clinician should examine the patient’s prior surgical history, duration of impairments before surgery, presence and severity of a preoperative rotator cuff tear,15 the underlying cause for the surgical technique, and finally, the postoperative ROM at the shoulder while under anesthesia. These factors can help the clinician predict the maximal outcome that may be achieved. Both the patient’s status before surgery and the underlying causative factors leading to surgery can be obtained via patient interview. It is rare that the treating physical therapist would have the opportunity to perform a physical examination to potentially address postural deficits preoperatively. The surgical information including comments on ROM and the condition of the repaired tissue may be obtained from communications with the surgeon including the surgical report.

imageRehabilitation progression may further be guided by precautions and recommendations directly from the surgeon. In some instances formal physical therapy may not be used depending on the surgeon’s experiences.16 Typically, the patient will present in an abduction pillow or at the very least a shoulder sling. Additional positioning options or passive ROM (PROM) restrictions may be in place for a patient with a history of rheumatoid arthritis. A long history of rotator cuff pathology may require positioning that decreases the mechanical stresses placed on the healing structures. imageAn external rotation restriction of less than 30° to 40° is typical for protection of the healing subscapularis muscle and the anterior capsule, which is disrupted during placement of the prosthetic. This restriction may last up to 6 weeks.1719

The periodization of the rehabilitation program for a TSA must balance protection of the healing tissues, structures with the need for ROM gain to prevent overall stiffness of the shoulder. There are indications that an increased immobilization period increases the risk of a contracture of the deltoid and the rotator cuff. This soft tissue imbalance is theorized to be one of the reasons for revision surgery of a TSA. Other reasons for surgical revision include glenoid loosening, rotator cuff tear, humeral head subluxation, proximal humeral head migration, and GH instability.1,14,20,55image The following guidelines should not supersede the communications from the surgeon nor should they override sound clinical judgment to create an independent plan of care based on your patient’s comorbidities, physical health, and functional needs.

Initial Postoperative Examination

Patient examination following surgery typically occurs on day 0 (day of surgery) or on postoperative day 1. The therapist will note IV lines for postsurgical fluid intake, sanguineous drains, postoperative dressing, and the upper extremity in a sling for comfort. Physical examination should include cognitive testing for orientation to name, time, place, and reason and vital sign assessment on the noninvolved extremity in supine, sitting, and standing. Testing specific to the involved upper extremity should adhere to the postoperative restrictions according to the patient’s chart (Box 7-3).

Neural screening should be completed as allowed within the postsurgical restrictions, including myotome, dermatome, and deep tendon reflex (DTR) testing. Active range of motion (AROM) of the cervical spine, thoracic spine, and elbow, wrist, and fingers should be assessed. PROM of the shoulder should be assessed with the patient in supine, understanding that some limitation in mobility may be contributable to the dressing or IV lines. Girth measurements should be noted at the elbow and at the wrist for comparison with the uninvolved extremity. Additionally, the anterior and posterior chest wall should be monitored for ecchymosis.

imageFunctional mobility assessment should be initiated with instructions cautioning against direct pushing or pulling of the involved upper extremity during transferring. Patients must be assessed for independent mobility from supine to sit to stand and vice versa. Once standing is achieved, balance must be assessed for single limb support without loss of balance. Frequently, postoperative day 0 or day 1 will require the patient to use a temporary single upper extremity support (IV pole or single point cane) because of anxiety and a deconditioned state. Monitoring of vitals and orientation during the transfer and gait assessment is necessary due to risk of hypotensive episodes. The clinician should encourage the use of coughing and incentive spirometry throughout the hospital stay because of the greater level of inactivity following surgery intervention.

Phase I: Hospital Phase of Rehabilitation

TIME: 2 to 6 days after surgery13

GOALS: Protection of healing structures, pain control, independent functional mobility for transfers, dressing and ambulation, education, and the institution of a home exercise program within the surgical restrictions (Table 7-1)

Treatment during the hospital phase of rehabilitation focuses on the achievement of appropriate pain control, independent functional mobility for transfers, dressing and ambulation, education, and the institution of a home exercise program within the surgical restrictions. Length of hospital stay depends on multiple factors including the volume and experience of the hospital and the surgeon experienced in the total shoulder procedure. Home support, comorbidities, and demographic features play a smaller role. Unlike the total knee arthroplasty where a certain objective measure of knee flexion is often one of the impairment goals for discharge, common discharge goals regarding functional level, pain control, and impairment objective measurements for total shoulder procedures have not been established in the literature.12,13

Typically, PROM is initiated on day 0 or 1, with a progression to self-assisted ROM exercises including pendulum or table top activities.

The home exercise program should be completed multiple times per day for short durations of 5 minutes maximum per bout of exercise.18image If there is a strict passive ROM restriction in place, then this will require the education of a caregiver or family member to assist with the execution of the home program. This caregiver must understand all postsurgical restrictions that limit ROM. Self-assisted ROM exercises can be based on patient comfort or surgeon preference.

Pendulum exercises involve a static position of forward flexion of the trunk with movement of the hips and trunk to drive the dangling upper extremity into multiple planes of motion (Fig. 7-11). The benefits of this activity for this patient population includes the addition of traction to the joint, stretching of the capsule, and imageavoidance of active muscular contraction at the shoulder joint.21 Overall, the goal is prevention of soft tissue contracture and possible modulation of pain via the rhythmic movement of the upper extremity through a PROM.17,22 There are several challenges with the correct performance of this exercise as it applies to the patient with a recent TSA. Frequently, the patient demonstrates inappropriate performance by recruiting excessive muscular action at the deltoid and pectoralis major muscles. The recommended posture for pendulum exercises emphasizes poor mechanical alignment of the scapula on the thorax with promotion of scapular abduction. And lastly, the excessive and unopposed stretching of the recently repaired musculature and tissues from the surgical procedure may actually generate greater pain response.

The Neer protocol for TSA23 placed wall slides in the same phase as pendulum activities with literary evidence of low muscular activity about the healing structures.21 Modification of this position to a lower gravitational demanding position would be self-assisted ROM using a table top. This table top modification is frequently used before wall slides during this early intervention phase. The patient stands at a table top with bilateral upper extremities resting at a comfortable placement. The hands maintain a static position and then ROM is attained by the lower extremity stepping into the various planes of motion.17 There are several benefits to this type of exercise prescription. The position of weight bearing promotes ROM gains through planar lower extremity motion. The trunk is moving underneath the scapula, which promotes interaction of the scapula and thorax in preparation for later stages of rehabilitation (Fig. 7-12). The patient is able to control the excursion of the ROM of the shoulder via decreasing the step size. The supported position of the shoulder via the hand decreases the unopposed stress on the healing tissue that may be achieved in the open kinetic chain position of the pendulum. Finally, closed kinetic chain activities at the shoulder reap similar benefits as stated for other extremities including: muscular cocontraction, decrease of shear forces, increased joint compression, and increased stability about the joint.3,24

The home exercise program should require AROM of the cervical and thoracic spines through the cardinal planes and active movement of the elbow, wrist, and hand.image If the patient is supine then flexion of the elbow should occur only with the humerus supported by a towel underneath it to decrease the strain on the biceps tendon at its insertion. Frequent bouts of exercise for short durations are recommended for the earlier stages of rehabilitation.

The home exercise program contains education for passive and/or self-assisted ROM at the shoulder, active ROM for proximal and distal structures, and education on sleeping postures. This should include positional support via the use of pillows or an immobilizer to support the healing structures during the night. The encouragement of experimentation to attain the best possible sleeping posture should be discussed. Anecdotally, patients following shoulder surgery feel better sleeping in a semireclined posture with the involved upper extremity supported by pillows or bolsters (Fig. 7-13).

Phase II: Outpatient Rehabilitation–Early Range of Motion 0 to 6 Weeks

TIME: 0 to 6 weeks

GOALS: Protection of healing structures, pain control, uninterrupted sleep pattern, normalized circumference measurements between upper extremities, mobilization of scar, ability to demonstrate normalized posture, and increased ROM (Table 7-2)

TABLE 7-2

Total Shoulder Replacement

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Rehabilitation Phase Criteria to Progress to This Phase Anticipated Impairments and Functional Limitations Intervention Goal Rationale
Phase II (ROM) Postoperative 0-6 wk