Primary Osteoarthritis

Primary osteoarthritis results in bony proliferation and articular cartilage loss of both the humeral head and glenoid. Synovial thickening and inflammatory episodes result in soft tissue fibrosis. Bony proliferation and osteocartilaginous bodies increase joint volume, accentuating loss of motion and eventual subscapularis contracture. Chronic anterior capsuloligamentous complex (CLC) and subscapularis constriction result in posterior humeral head migration, increased glenoid wear, posterior capsule attenuation, and posterior subluxation. Global soft tissue contracture of the rotator cuff muscles, latissimus dorsi, teres major, and pectoralis major develops. Capsuloligamentous and musculotendinous contracture can impair postoperative outcome and expectations. Iannotti and Norris found that patients treated with hemiarthroplasty (HA) with preoperative external rotation of 10 degrees or less had less postoperative active external rotation (25 degrees) compared with those who had greater than 10 degrees (47 degrees). However, external rotation motion was unaffected by the degree of internal rotation contracture if the patient had a total shoulder arthroplasty (TSA). Limited preoperative elevation did not influence postoperative outcome in either arthroplasty group.

Outcomes following arthroplasty for osteoarthritis are considered good. Bryant et al. did a systematic review on several studies and found the average forward elevation was 131 degrees and 117 degrees following TSA and HA, respectively. Others reported average return of forward elevation was 138 to 145 degrees. All studies report significantly improved functional outcomes and pain relief.

Fortunately, most patients with advanced primary osteoarthritis do not have rotator cuff tears; therefore, dynamic stabilization is typically good. Norris and Iannotti found only 9% of patients with primary osteoarthritis of the shoulder had rotator cuff tears, but all were confined to the supraspinatus tendon and all were repairable. The presence of a repairable rotator cuff tear did not affect outcomes, although better active external rotation was found in patients who were treated with a total shoulder arthroplasty versus a hemiarthroplasty. A multi-center study on 514 patients found the presence of partial- or full-thickness supraspinatus tears did not influence range of motion or outcome. However, moderate to severe fatty degeneration of the infraspinatus and severe fatty degeneration of the subscapularis did result in lower Constant scores and range of motion. Godeneche et al. found that both partial and superficial supraspinatus cuff tears adversely affected the final outcome, particularly active forward elevation and strength. Stage 2 fatty degeneration was a predictor of impaired active elevation (123 degrees for stages 2 to 4, versus 147 degrees for stages 0 to 1). Better active range of motion is expected when arthroplasty is performed on patients with primary osteoarthritis and an intact rotator cuff compared with patients with rheumatoid arthritis, posttraumatic arthritis, or rotator cuff arthropathy.

The incidence of rotator cuff tears following arthroplasty is most likely underreported, yet it was found to be the number one complication following total shoulder arthroplasty. Commonly, the poor outcome is related to the arthroplasty and not to the primary cuff insufficiency. Cofield et al. reported that the tearing of the rotator cuff was a minor complication in 5 individuals but a major complication that affected outcomes in 11 individuals.

The influence of posterior glenoid erosion and posterior subluxation on postarthroplasty outcome was evaluated in patients with primary osteoarthritis. Patients treated with a hemiarthroplasty having moderate to severe preoperative posterior glenoid erosion had significantly less active external rotation and elevation (16 degrees versus 32 degrees, and 117 degrees versus 139 degrees, respectively) compared with those treated with a total shoulder arthroplasty. Although range of motion was affected, no difference was seen in pain relief or the American Shoulder and Elbow Surgeons (ASES) score. The amount of glenoid erosion did not influence any outcomes in patients treated with a total shoulder arthroplasty. The presence of preoperative posterior subluxation resulted in less range of motion, increased pain, and lower ASES scores in patients treated with arthroplasty.

Acute Fracture

Arthroplasty performed in patients with three- and four-part fractures is discussed separately. The indication for arthroplasty in the acute fracture patient is quite different from other patients treated with arthroplasty. Patients with an acute proximal humeral fracture have spontaneous obliteration of the humeral head, compared with the slow, destructive changes seen in various forms of arthritis. A hemiarthroplasty is performed in the acute postfracture group since the glenoid is typically spared from trauma. The technical demand on the surgeon is greater because not only is proper prosthetic placement required but tuberosity fixation must be achieved. The rate of postoperative rehabilitation progression is determined by the tuberosity fixation integrity. Evidence of tuberosity motion at the time of surgery or in early postoperative radiographs will limit early mobilization of the shoulder. The surgeon must relay fixation concerns to the therapist in order to prevent facture line stress. Agorastides et al. found that there was no significant difference in range of motion or outcomes if patients were mobilized at 2 weeks versus 6 weeks following three- and four-part fractures treated with hemiarthroplasty. Average active elevation range of motion at 12 months postoperatively was 78 degrees, external rotation was 15 to 18 degrees, and functional internal rotation was to L4.

Tuberosity and prosthetic component malpostion are related to poor functional outcomes. Cofield reported a relatively small incidence of tuberosity malposition of 1.8% and nonunion/malunion of 0.4% after arthroplasty. Boileau et al. reported that significant tuberosity and humeral component malposition negatively influence outcome in patients treated with hemiarthroplasty following three- and four-part fractures. They found early radiographic evidence of tuberosity malposition in 27% of patients and final tuberosity malposition in 33 of the 66 cases. At an average follow-up of 27 months, 29 patients were very satisfied, 9 were satisfied, and 28 were unsatisfied. Seventy percent of the patients had less than 120 degrees of active elevation. Average active elevation was 101 degrees, external rotation to 18 degrees, and functional internal rotation to L3. Bigliani et al. reported similar findings in patients with failed hemiarthroplasty performed for proximal humeral head fractures. They reported tuberosity displacement or malunion and component malposition occurring in 59% and 42% of the failures, respectively. A “proud” humeral component results in relative excessive tension on the rotator cuff and possible nonunion between the greater tuberosity and the humeral dyaphysis. Greater than 40 degrees of humeral component retroversion results in greater tuberosity posterior migration due to excessive tension on the tuberosity when the arm is internally rotated (placed in sling). Tuberosity or humeral component malposition may ultimately result in rotator cuff deficiency, internal impingement, and pain.

Nerve lesions are commonly seen following proximal humeral head fractures. Visser et al. reported that 67% of patients with proximal humeral head fractures had nerve injuries and persistent neurologic deficits that diminished functional outcome. The axillary nerve is most often affected, but combinations of nerve lesions were found. A nerve lesion should be identified before surgery, but difficulty in examining the painful shoulder may make detection difficult. Any patients undergoing arthroplasty surgery for an acute fracture should be thoroughly examined for nerve lesions before and after arthroplasty.

It is important for the rehabilitation specialist to understand that range of motion may be significantly limited in patients treated with hemiarthroplasty for three- and four-part fractures. Prakash et al. reported that patients treated with hemiarthroplasty for three- and four-part fractures had elevation, external rotation, and internal rotation of 93 degrees, 24 degrees, and L1, respectively. They found no significant difference in outcome if operated on within 30 days of injury or at a mean of 13 months postinjury. Green et al. found that approximately 50% of patients treated for acute fractures could perform above-shoulder-level activities. Zyto et al. reported on disappointing active elevation, averaging 70 degrees, in patients treated with a hemiarthroplasty within 4 weeks for a three- or four-part humeral head fracture.

Attempts to perform aggressive range-of-motion exercises following hemiarthroplasty due to a proximal humeral fracture can result in iatrogenic injury, pain, and patient and therapist frustration. Frankle et al. reported that too much passive external rotation motion, approximately 50 degrees, performed soon after surgery could disrupt fracture healing. The rehabilitation specialist must be aware of the reported outcomes and healing concerns so that inappropriate therapy is avoided.

Posttraumatic/Fracture Arthritis

Most often patients classified as having posttraumatic arthritis have had a previous proximal humeral fracture with or without surgical fixation. Osteoarthritis occurs in 25% and 64% of patients with three-part and four-part fractures, respectively. Tuberosity malposition subsequent to injury or previous surgery can result in chronic rotator cuff deficiency. Dramatic soft tissue scarring and distortion of normal bony anatomy due to heterotopic bone formation and malunion can occur in this population. Chronic nerve injuries, significant presurgery contracture, and chronic rotator cuff deficiency will limit postoperative arthroplasty outcomes. Torchia et al. reported on long-term results (mean follow-up: 12.2 years) of patients treated with total shoulder arthroplasty. Of the nine patients having posttraumatic arthritis, approximately 45% undergoing a full exercise program had unsatisfactory results and 50% of those with limited goal were unsuccessful.

The results of prosthetic replacement for three- and four-part fracture malunions do not approach those of prosthetic treatment in similar acute fractures. Delaying surgical treatment in patients with three- and four-part fractures could result in a high incidence of fracture instability. Antuna et al. reported on 77 patients with proximal humeral nonunions and malunions who eventually were treated with hemiarthroplasty and total shoulder arthroplasty. Although pain relief and satisfactory outcomes were achieved, more than half the patients were considered to have unsatisfactory results. Active elevation was 88 degrees and 102 degrees in the nonunion and malunion groups, respectively. Hasan et al. found that approximately 50% of the failed hemiarthroplasties were in patients treated for acute or chronic proximal humeral head fractures. Patients receiving arthroplasty for osteonecrosis caused by previous fracture demonstrated 107 degrees of flexion versus 130 degrees in the nontraumatic group.

Instability/Capsulorraphy Arthritis

A related group of posttraumatic arthritis occurs in patients with primary glenohumeral instability. Dislocations and/or surgical intervention for instability can result in soft tissue imbalance and eventual articular cartilage destruction. Hovelius reported a 20% incidence of “dislocation arthropathy” in a 10-year follow-up of patients younger than 40 years old with anterior instability. More commonly, arthritis due to instability is a result of surgical intervention or “capsulorraphy arthropathy.” Neer felt that arthritis developed due to recurrent dislocation when the “standard” surgical procedure intended for unidirectional instability was used in the patient with multidirectional instability. He observed that patients became unstable in the opposite direction of the surgical procedure. Even moderate to severe arthritis can develop with any stabilization procedure. Nonanatomic anterior stabilizing procedures like a Putti-platt or Magnuson–Stack can result in a severe internal rotation contracture, posterior humeral head subluxation, and posterior glenoid erosion. Laboratory studies support the clinical picture that an internal rotation contracture results in altered humeral head translation and arthritis.

Patients treated for capsulorraphy arthritis are typically younger. Green and Norris reported on 19 patients who had arthroplasty performed secondary to capsulorraphy arthritis and found a thickened anterior CLC and subscapularis tendon. He noted this tissue was denser than that found in patients with primary osteoarthritis, and half his patients required a subscapularis lengthening procedure. In his series, 20% required posterior bone grafting or eccentric reaming to remedy the excessive posterior glenoid erosion. Range-of-motion outcomes included active elevation of 120 degrees; external rotation averaged 41 degrees, with functional internal rotation to T12. Patients who underwent a subscapularis lengthening procedure had greater external rotation (46 degrees) compared with those who did not (27 degrees).

Instability appears to be the most common complication following shoulder arthroplasty. Instability presents as subluxation or a complete dislocation and can occur in any direction. The most common instability following shoulder arthroplasty is some degree of minor superior humeral head subluxation. Moekel reported on 10 patients who developed instability in a series of 236 consecutive arthroplasties. Instability was anterior in seven and posterior in three. Four of the seven patients with anterior instability dislocated within 7 weeks of surgery during physical therapy. Wirth and Rockwood reported on 18 patients who developed instability; 11 were posterior, 6 were anterior, and 1 was inferior. Anterior instability was associated with anterior deltoid dysfunction, malrotation of the humeral component, and disruption of the subscapularis. Disruption of the subscapularis tendon was associated with poor tissue quality or technique of reattachment, inappropriately oversized components, or aggressive physical therapy. Posterior instability was associated with dynamic muscle dysfunction, attenuation of the supraspinatus muscle tendon unit, or rotator cuff tearing. Hasan et al. found that stiffness, instability, and component malposition often coexisted. In Cofield’s series, 11% had instability complications. They found instability occurred early in 16 patients and later in 28 patients. Subluxation was always a devastating complication, requiring reoperation in 32 of 44 patients with unstable shoulders.

Osteonecrosis

Osteonecrosis by definition means “bone death.” It is sometimes referred to as avascular necrosis or aseptic necrosis. Unlike most arthritis that initially involves the articular cartilage, osteonecrosis begins in the subchondral cancellous bone, which fails and alters the articular cartilage. Osteonecrosis is classified as traumatic, related to fractures of the proximal humerus, or atraumatic, related to disease processes. When related to fractures, the wider the displacement of the articular segment from the shaft, the greater incidence of osteonecrosis. Multiple processes results in atraumatic osteonecrosis, including systemic use of steroids, alcohol ingestion, and Cushing disease.

Patients with osteonecrosis who were treated with arthroplasty had better outcomes if the pathology was related to steroid use versus trauma. Hattrup and Cofield reported the mean return to active flexion was 126 degrees and 115 degrees for patients receiving hemiarthroplasty and total shoulder arthroplasty, respectively.

Rotator Cuff Arthropathy

Rotator cuff arthropathy is a result of end-stage rotator cuff failure. Progressive rotator cuff failure results in superior humeral head migration, significant soft tissue contracture, and fixed articulation with the coracacromial arch. Performing a standard total shoulder arthroplasty in a rotator cuff–deficient shoulder will result in eventual glenoid component loosening. Until recently a hemiarthroplasty was the preferred surgical intervention. However, the use of the reverse total shoulder is proving an excellent alternative.

The outcome in patients treated with a hemiarthroplasty is limited because the rotator cuff is irreparable; however, pain relief and improved function are expected. Zuckerman et al. found that mean elevation was only 86 degrees after hemiarthroplasty but pain relief was significant. They also found increased strength in this group following arthroplasty but concluded this was due to pain reduction. Williams and Rockwood reported on 20 patients who underwent hemiarthroplasty for glenohumeral arthritis combined with an irreparable rotator cuff. Using the Neer limited-goals criteria they obtained 86% satisfactory results. They found active elevation improved from 70 degrees preoperatively to an average of 120 postoperatively. Arntz et al. reported average active elevation of 112 degrees in 21 patients treated with hemiarthroplasty for rotator cuff arthropathy. Interestingly, in four of the six patients who had not undergone previous rotator cuff repair, all had greater than 135 of active elevation. None of the patients with previous rotator cuff repair had greater than 126 degrees; in fact, only 4 of 11 had greater than 100 degrees.

Functional motion improves significantly following reverse total arthroplasty for patients with rotator cuff arthropathy of massive cuff tears.

Two groups emerge when considering pathology, rehabilitation, and expected outcome: standard goals and limited goals. The standard goals group have a competent rotator cuff and deltoid muscles that allow full function and near normal motion. The limited-goals patient has rotator cuff or deltoid deficiency, due to an irreparable rotator cuff, poor tendinous tissue, tuberosity malposition, or denervation. Pain relief is always the goal, but the limited-goals group is expected to have limited active elevation of less than 90 degrees and external rotation of approximately 20 degrees. This group achieves less satisfactory function.

Goals of Examination

The goals of the examination are: (1) Determine baseline status relative to pain, range of motion, and swelling; (2) assess for postoperative complications such as signs of infection, increased reactivity, and nerve injury; (3) develop a prognosis for recovery and outcome; and (4) determine the patient’s frequency of visits. The amount of supervised therapy visits is based upon general reactivity, the patient’s ability to perform the home exercises, and the range of motion in the first 2 weeks postoperatively. A patient with minimal postoperative pain and acceptable range of motion will probably not need much supervised therapy, especially in the first 6 weeks. Recognize that the patient having a hemiarthroplasty for rotator cuff arthropathy will generally have a poorer outcome than the patient with primary osteoarthritis and an intact rotator cuff. The therapist will then “expect” limited goals and not aggressively treat the patient or become frustrated with recovery.

Evaluative goals of the postsurgical patient are defined by time period from surgery. Regardless of the procedure, an examination performed on the first day after surgery differs from an examination performed 6 weeks after surgery. Strength assessment requiring full resistance is contraindicated until the relevant tissues are adequately healed. The time varies depending on the surgery and tissue healing. Necessary information regarding muscular, structural, and neurologic integrity of the distal structures can be gained with a submaximal contraction within the first 2 weeks. Determining the presence of a nerve injury is an early goal of all examinations. Typically, a full shoulder examination can be performed at 6 weeks, although prudence is always required when assessing strength following rotator cuff repair and tuberosity fixation.

History

The patient’s history is an essential component of a postarthroplasty examination. Knowledge of the arthritic pathogenesis provides a sense of expected outcome and soft tissue considerations. The patient undergoing arthroplasty for primary osteoarthritis with an intact rotator cuff is expected to have a better outcome than the patient who has rotator cuff arthropathy. A patient who has had posttraumatic arthritis due to an old fracture should always be questioned about the existence of nerve lesions due to the high incidence of nerve injuries following proximal humeral head fractures and dislocations. Typically, greater stiffness and pain is noted if the tuberosities have been osteotomized or require fixation as in the acute fracture group or posttraumatic group.

Previous surgery is a factor related to eventual outcome. Hasan et al. found that the clinical expression of failure following arthroplasty was related to the number of previous surgeries. They found that patients having two or more shoulder surgeries had a lower Simple Shoulder Test score than those having an initial arthroplasty. Neer and Kirby reported that 35% of 40 patients with failed arthroplasties had between one and six previous surgeries. Bigliani et al. also felt that a poorer outcome was related to previous surgeries. Patients treated with hemiarthroplasty for rotator cuff arthropathy who had not had a previous rotator cuff repair had greater active elevation than those who had a previous rotator cuff repair.

Knowing presurgery range of motion and activity demands provide information relative to expected postoperative range of motion and activity levels. Significant weakness and unresolved range of motion decrements prior to surgery have been shown to depreciate postoperative results. The 70-year-old patient who has been unable to elevate beyond shoulder level for the last 10 years but was able to function until the pain became unbearable would have different expected outcome and ultimate rehabilitation intervention than the 70 year old who was playing tennis up to 3 months prior to surgery. Questions regarding pre- and postoperative instability events will alert the clinician about possible stability issues and the need for caution with range-of-motion exercises.

The clinician must remember the primary goal of surgery is to reduce pain. Function should improve; however, it may not always be manifested by a dramatic increase in motion. For instance, a 20-degree improvement in elevation may sound significant; however, it may be a gain from 80 to 100 degrees. A postoperative range-of-motion outcome of 100 degrees of elevation would not be acceptable in almost any other type of shoulder surgery, but in the arthroplasty patient, pain-free motion to 100 degrees may result in a significant improvement in function and the patient may be very satisfied.

Examination

Following arthroplasty the patient will commonly spend 2 days in the hospital. The examination process at this time should include passive motion of the shoulder in elevation and external rotation with the arm toward the side. External rotation range of motion may be limited to 30 degrees because the subscapularis is incised, possibly altered by lengthening, and then reattached. The therapist should recognize that the CLC has been released and therefore the rotator cuff envelope provides passive restraint to motion. The shoulder should not be assessed in the coronal plane for abduction or external rotation motion. Moekele reported on five cases of dislocation occurring during therapy within the first 7 postoperative weeks. Four of these cases occurred with aggressive external rotation motion in abduction or adduction. Expected passive elevation is 120 to 160 degrees of elevation. However, this will depend on the reason for arthroplasty and previous soft tissue restrictions. In patients who have undergone total shoulder arthroplasty for osteoarthritis, 140 degrees of passive elevation is common at 1 to 2 days postoperatively. Following a hemiarthroplasty for a three- and four-part acute fracture, shoulder motion may not be assessed at all or limited to 90 degrees, depending on the quality of the fixation.

Assessment of elbow, wrist, and hand motion is performed both actively and passively. Neurologic assessment of the elbow, wrist, and hand should be performed. Early determination of nerve injury is difficult because interscalene blocks are commonly employed. Significant edema throughout the shoulder and upper arm is expected following arthroplasty.

It may be common for the therapist to see the patient 7 to 10 days postoperatively depending upon the surgeon’s preference. We strongly recommend therapy intervention at this time to instruct or re-instruct the patient in range-of-motion exercises. Assessing the incision for signs of infection or healing problems is important. Upper extremity edema should be assessed and determined if it appears “normal,” recognizing there is always some degree of shoulder and upper extremity edema/ecchymosis. Significant edema of the elbow, forearm, and hand must be addressed with positioning, massage, and elbow, wrist, and hand active range-of-motion exercises.

“Cold” passive range-of-motion expectations for a patient with uncomplicated TSA at this time is typically 100 to 140 degrees and external rotation is from 15 to 30 degrees; however, this will depend on the preoperative chronicity of the soft tissue restrictions. At this time, a neurologic screen of the upper extremity should be performed. The deltoid can be assessed by palpating the different heads and prompting minimal activity. Neurologic integrity can be assessed in the muscle groups of the elbow, wrist, and hand. The incidence of nerve injury following arthroplasty is 1 to 20 percent, although the incidence may be higher following fracture.

When assessing the patient following arthroplasty at 4 to 6 weeks, the examination focuses on neurologic integrity and willingness to move (spontaneity of motion), as well as active and passive range of motion. If the arthroplasty was done for an acute fracture or posttraumatic arthritis and tuberosity fixation was required, active motion may be deferred until 6 to 8 weeks. Active range of motion is assessed in elevation, external rotation at neutral and at 90 degrees in the scapular plane. IR can be assessed at 90 and functional internal rotation (IR) (thumb-up spine). Scapular shrugging commonly occurs with active elevation. Passive motion is assessed in supine in the same directions. The clinician should observe and palpate for signs of humeral head migration. A patient with rotator cuff deficiency may have visual and palpable superior migration when elevating. A patient with instability may have posterior head migration with forward elevation.

Range of motion should be assessed after stretching and compared with the pretreatment motion. This provides insight about muscle guarding versus true soft tissue restriction. For instance, a 25-degree gain in elevation during one session is most likely related to muscle guarding as opposed to contracture.

The therapist should specifically assess the deltoid heads for neurologic integrity. This should be done without asking for maximal contraction. Even in the absence of deltoid activity, sufficient “resistance” is encountered during abduction muscle testing. The deltoid heads should be evaluated separately by using specific arm positioning. The key to testing the deltoid is palpation, not perceived resistance.

For anterior deltoid assessment, position the arm toward the sagittal plane in approximately 60 to 80 degrees of elevation and in some external rotation so that the forearm is almost vertical. The examiner must support the arm at the elbow and have the patient fully relax. The head is palpated and should be flaccid. The examiner then asks the patient to “hold the arm there” while the examiner begins to release the arm. It is important that the arm is still supported, particularly after a surgical procedure. The arm should not move. As the patient attempts to activate the muscle, one can palpate for activity. This sequence of relaxing and activating is repeated to accurately determine if the muscle is innervated. Even if muscle activity is perceived, the “tone” of the muscle needs to be interpreted. Decreased tone may be due to a recovering palsy. However, several sessions or even weeks may need to pass before one can determine whether postoperative inhibition versus the presence of a nerve lesion is the reason for reduced tone.

The middle deltoid is assessed by positioning the arm in approximately 40 to 60 degrees of coronal plane abduction while supporting at the elbow and wrist. The examiner must support the arm and have the patient fully relax. The head is palpated and should be flaccid. The examiner then asks the patient to “hold the arm there” while the examiner begins to release the arm. Proceed with repeated relaxing and activating. The posterior deltoid is assessed in the same manner but with the arm positioned in approximately 60 to 80 degrees of coronal plane abduction while supporting at the elbow and wrist. The examiner then asks the patient to “push backward” while the examiner resists horizontal abduction.

Strength assessment is carried out throughout the upper extremity, determining both weakness and pain. Strength can be graded from 0 to 5; however, manual muscle testing using this grading system is unreliable and subjective above the fair grade. A simple, valid, and reliable method of strength assessment is using a handheld or wall-mounted dynamometer. A functional outcome score specific to the shoulder is also recommended. Numerous outcome tools are available such as the Penn Shoulder Score, American Society of Shoulder and Elbow Surgeons score or the Simple Shoulder Test.

Special tests to assess rotator cuff integrity may be beneficial. The external rotation lag sign is a specific and sensitive test for identifying a supraspinatus and/or infraspinatus tear or neurologic integrity. Two positions are used for the external rotation lag signs. The first is to passively place the arm in full external rotation with the arm 20 degrees abducted in the plane of the scapula (POS). Care should be taken to not overrotate, resulting in elastic recoil. The examiner instructs the patient to maintain the arm in this position and releases at the wrist but supports the elbow. A patient with an intact supraspinatus and infraspinatus can maintain the arm in this position. If the arm lags or falls toward internal rotation, the test is positive. The degree of lag is related to the size of tendon tear or severity of nerve involvement. A lag of 5 to 10 degrees was found to indicate a supraspinatus tear, whereas a lag of greater than 10 degrees was associated with complete tearing of the supraspinatus and infraspinatus. Significant lagging was also found also found with a severe complete suprascapular nerve palsy. We have also seen positive lag signs in cases of brachial plexopathy or C6 nerve root radiculopathy.

Hertel et al. also described an external rotation lag sign performed at 90 degrees of elevation and 90 degrees of external rotation. This may be impractical in the postarthroplasty patient due to difficulty attaining this position. A lag seen in this position was consistent with a tear involving the infraspinatus tendon.

Several tests have been described to determine subscapularis integrity. Two have been described by Gerber : the lift-off test and the abdominal compression or belly press test. Hertel et al. described the internal rotation lag sign. The lift-off test is performed sitting or standing. The patient is asked to place the dorsal aspect of the hand on the lower back and lift it away. The test is positive if the patient cannot remove the hand from the back or can do so partially. This position places all the internal rotators in their shortened position but primarily isolates the subscapularis. For the lift-off test to be valid, the patient must have available pain-free internal rotation motion.

If full motion is available, the internal rotation lag sign can also be performed. The examiner passively places the patient’s arm into internal rotation behind the back and lifts the dorsum of the hand from the back (essentially the completed lift-off position). Care must be taken not to rotate beyond available range. The elbow is supported and the patient is asked to maintain this position as the hand is released. A positive test is when the hand falls toward or onto the back. In both the lift-off test and internal rotation lag sign, the examiner must watch for substitution of shoulder extension and elbow extension. For these test positions to be valid, the patient must have the available pain-free motion. We have found that patients often do not have enough passive internal rotation motion following arthroplasty for these to be used.

The abdominal compression test is useful in the patient who cannot be placed into the lift-off or lag sign position because of pain or contracture. However, it still isolates the subscapularis. The patient is asked to place the hand flat against the stomach and the elbow out to the side and slightly forward. The patient is instructed to push into the stomach while keeping the elbow out to the side. A positive test is when the elbow cannot be maintained out to the side and forward (the arm adducts). To further appreciate the amount of weakness, the examiner may also attempt to pull the hand from the stomach. The hand is easily pulled from the stomach when the subscapularis is ruptured or neurologically impaired.

We have found many patients who present with positive signs for subscapularis rupture following a total shoulder replacement or hemiarthroplasty. We followed eight patients 10 to 26 months after total shoulder arthroplasty for primary osteoarthritis. Four patients had an anatomic repair of the subscapularis and four had the tendon medialized. All patients had a Penn Shoulder score of greater than 85 out of 100, but all had positive lift-off and belly press tests. Objective isometric measurement in the belly press test position revealed a 100% deficit. We also found a significant loss of internal rotation motion at 90 degrees and functionally behind the back.

Miller et al. evaluated subscapularis function following total shoulder replacement. The presence of a positive lift-off test and belly press test was 67.5% and 66.6%, respectively. The functional status of the subscapularis was documented by the patients’ ability to tuck in a shirt in the back of the pants. Of the 25 patients with a positive lift-off test, 92% were unable to tuck in their shirts. Armstrong et al. documented the healing rate of the subscapularis by use of ultrasound in 23 patients (30 shoulders) who underwent total shoulder arthroplasty. They also correlated healing to physical examination findings. All patients had an improvement in functional outcome scores and shoulder range of motion. Of 30 shoulders, 26 (87%) had an intact subscapularis as determined by ultrasound. By use of ultrasound as the gold standard, the abdominal compression test had 7 false-positive results, 3 false-negative results, 19 true negative results, and 1 true-positive result. The sensitivity of the abdominal compression test was 25%, and the specificity was 73%. The negative predictive value was 86%, and the positive predictive value was 13%. Causes of this weakness may include partial or complete subscapularis repair failure, subscapularis weakness, mechanical insufficiency of the subscapularis, and nerve injury. The loss of internal rotation motion dramatically affects the ability to use both the lift-off and the belly press test. The abdominal compression test position requires significant internal rotation motion as the patient is asked to place the elbow forward. If passive internal rotation is lacking, these tests may not be valid assessment tools. We have seen a similar phenomenon in other patients who lack significant internal rotation. Therefore we are suspicious of the validity of the internal rotation sign, lift-off test, and belly press test in assessing structural integrity of the subscapularis, particularly in the early postoperative period.

The examination process should be ongoing during the rehabilitative process. During each session, range of motion and strength can be quickly assessed. Spontaneity of motion is an excellent indication of reduced joint reactivity and normalization of the neuromuscular system. Periodic use of a shoulder-specific outcome tool helps to measure functional progress. When findings indicate progress not consistent with expectations, the rehabilitation interventions should be modified. If the patient continues to demonstrate suspicious findings, such as weakness, this should be relayed to the surgeon for his feedback.