The Musculoskeletal System

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Chapter 21 The Musculoskeletal System

Generalities

This is a difficult area of physical exam, but one necessary in ambulatory medicine and often rewarding. One of 10 patients presenting to a primary care office will do so because of musculoskeletal complaints. Most of these can be diagnosed through a thorough exam, specific maneuvers (Table 21-1), and a proper knowledge of joints’ anatomy and physiology.

Table 21-1 Joint Diseases—Specific Maneuvers

Joint Problem Maneuver
Shoulder General Painful arc sign
  Acromioclavicular (AC) arthritis Cross-body and cross-arm maneuvers
  Bicipital tendinitis Yergason’s and Speed’s tests
  Rotator cuff pathology Gerber’s lift-off test, drop arm test, empty can test
  Impingement Neer (impingement) and Hawkins-Kennedy tests
  Anterior shoulder instability Apprehension and Jobe’s relocation tests
  Inferior shoulder instability Sulcus sign
  Glenoid labral tears O’Brien’s and anterior slide tests
Elbow Cubital tunnel syndrome Elbow flexion test
Wrist Carpal tunnel syndrome Tinel’s sign, Phalen’s sign, flick sign
  Rheumatoid arthritis Piano key sign
  De Quervain’s tendinitis Finkelstein test (positive)
  Intersection syndrome Finkelstein test (negative)
Hand Interosseous tightness versus capsular contraction Bunnel-Littler test
Hip General FABER maneuver
Knee Patellofemoral syndrome Patellofemoral grinding test
  Effusion Bulge sign, patellar ballottement, fluid wave test
  Anterior cruciate ligament Lachman’s test, anterior drawer test, lateral pivot shift test
  Posterior cruciate ligament Posterior drawer test, tibial sag test
  Meniscal tears Medial-lateral grind test, McMurray’s test, Apley’s grind and distraction test
Ankle Anterior talofibular tear Anterior drawer test
  Anterior talofibular/calcaneofibular tear “Talar tilt” test
  Tibiofibular syndesmosis “Squeeze” test
  Tarsal tunnel syndrome Submalleolar tap

A. The Shoulder

15 Describe the muscles and tendons of the shoulder

image The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis (mnemonic, SITS). Their tendons converge on the humerus, thus allowing for most of the joint movements (abduction of the arm and rotation of the shoulder, both internal and external). They also hold the humeral head in the glenoid cavity, thus stabilizing the joint.

image The deltoid is the largest and strongest muscle, responsible for the later part of abduction and flexion once the arm has been lifted by the supraspinatus. It is visible but rarely injured.

image The biceps has two proximal heads (hence, the name), which insert into the shoulder: (1) the long head tendon and (2) the short head of the biceps. The long head tendon lies in the bicipital groove of the humerus, between the greater and lesser tuberosities and under the transverse humeral ligament. This arrangement prevents the humeral head from sliding too far during abduction and external rotation. At the upper end of the groove, the long head of the biceps angles 90   degrees inward, crossing the humeral head and eventually inserting itself into the upper edge of the glenoid labrum and supraglenoid tubercle. The short head of the biceps connects instead on the coracoid process. Distally, the two heads of the biceps merge to form the body of the biceps brachii muscle, which inserts itself into the radius through its common distal head. The biceps is a powerful flexor and supinator of the forearm (i.e., it rotates forearm and hand so that the palm faces upward).

16 What are the shoulder’s movements? How do you test its ROM?

The shoulder can actively abduct, adduct, externally and internally rotate, flex, and extend. It has the largest ROM of any joint, since it provides mobility not only to the girdle but also to the hand. ROM is tested as follows:

If active ROM elicits pain, evaluate the same movements through passive ROM. To provide your patient with adequate support (and thus ensure maximal relaxation), gently rest one hand on his/her shoulder while using your other hand to move the humerus through the same ROM as previously discussed. Look for pain and crepitus. Pain and limitation on active, but not passive, ROM indicate muscular or tendinous problems. Crepitus suggests instead degenerative joint disease.

19 What is the general approach to the shoulder exam?

Always expose both shoulders (and watch while the patient removes the shirt). Then carry out a systematic exam: inspect, palpate, assess ROM, measure strength, evaluate neurologically, and perform special shoulder tests. Also, examine the cervical spine and upper extremity.

33 How do you diagnose rotator cuff tendinitis?

By carefully examining the shoulder and by knowing the function of the four rotator cuff muscles (i.e., abduction, external rotation, and internal rotation).

image The supraspinatus is the most important and most commonly damaged of the four. It links the top of the scapula to the humerus, inserting into its greater tuberosity. It is partially responsible for arm abduction (the initial 15–30   degrees are actually produced by the deltoid, the next 60   degrees by the supraspinatus, and the final 90   degrees by the deltoid again). Hence, inflammation of the supraspinatus tendon leads to pain at 30–90   degrees of abduction, as the humerus impinges the tendon against the acromion. It can be easily tested through the empty can test.

image The infraspinatus produces external rotation of the humerus, a function assisted by the teres minor. The two also cooperate to maintain glenohumeral stability. To test external rotators (infraspinatus and teres minor): (1) have the patient abduct both shoulders to 20–30   degrees, while keeping the elbows flexed at 90   degrees; (2) instruct the patient to push the arms outward (externally rotate) against resistance. External rotation elicits pain in tendinitis and weakness in tears.

image The subscapularis is the only of the four rotator muscles to originate from the anterior surface of the scapula (the others arise instead in the back). It connects the scapula to the humerus, serving as humeral head depressor and, in certain shoulder positions (adduction), as internal rotator. Function is evaluated through the “Gerber’s lift-off test”: (1) have patients place the hand behind the back, with palm facing out, and (2) instruct them to lift the hand away from the back and against resistance. Internal rotation elicits pain in tendinitis and weakness in tears.

Note that given the anatomic closeness of the long head tendon of the biceps (which passes down the bicipital groove in a fibrous sheath between the subscapularis and supraspinatus tendons), patients with rotator cuff disease also may have biceps tendinitis (see questions 27 and 28).

50 How do you test for anterior shoulder instability?

Through the apprehension and Jobe’s relocation tests. Start with “apprehension” (Fig. 21-2). To perform it, ask patients to lie supine, with the affected shoulder just off the examining table. Grasp the elbow with one hand, and gently bring the arm to 90-degree abduction and 90-degree external rotation. Then push with your other hand on the posterior aspect of the humeral head, from back to front. Anterior shoulder instability will give a feeling that the arm is about to pop out of the joint. At the same time, patients will experience pain, apprehension, and guarding. In the original series of Rowe and Zarins, all 60 cases of anterior shoulder instability had a positive apprehension test. If the patient experiences pain and/or apprehension, move on to the second part of the maneuver: the Jobe’s relocation test. This is performed in the same position, but this time by pushing on the anterior aspect of the humeral head, from front to back, as if relocating a glenohumeral joint that had been partially dislocated by the apprehension test. Patients with primary impingement will have no change in pain, whereas those with anterior instability (subluxation) and secondary impingement will have relief of pain and/or apprehension. When relying primarily on relief of apprehension, the relocation test has sensitivity for anterior instability of 68%; specificity, 100%; positive predictive value, 100%; negative predictive value, 78%; and accuracy, 85%.

image

Figure 21-2 Apprehension test.

(From Mellion MB: Office Sports Medicine, 2nd ed. Philadelphia, Hanley & Belfus, 1998.)

B. The Elbow

C. The Wrist