Musculoskeletal: The Upper Extremity

The upper extremity questions on the NPTE rarely ask you to name a muscle; they hand you a patient with a painful arc, a weak grip or a numb ring finger and ask what is wrong, what to test next and what is safe to do this week. Shoulder pathology, postoperative protocols, elbow and hand injuries and peripheral nerve lesions form a large and predictable block of the musculoskeletal content. This chapter organizes that block around the decisions you will make on the exam and in clinic.

Section 1The shoulder complex

Joints and the scapulohumeral rhythm

The shoulder complex is four articulations working as one unit: the glenohumeral joint, the sternoclavicular joint, the acromioclavicular joint and the functional scapulothoracic articulation. The glenohumeral joint is a ball and socket with a shallow glenoid that covers only about a quarter to a third of the humeral head; the labrum deepens it, and the capsule, glenohumeral ligaments and rotator cuff supply the rest of its stability. That trade of bony stability for mobility is the reason the shoulder dislocates more than any other large joint and the reason rotator cuff function matters so much.

Full elevation of the arm (about 180 degrees) is shared between the glenohumeral joint and the scapula. The classic teaching ratio is 2:1: about 120 degrees of glenohumeral motion and 60 degrees of scapular upward rotation. The ratio is not constant through the range; in the first 30 degrees or so of abduction (the setting phase) the scapula moves little and variably, and most scapular contribution comes later. The clavicle elevates about 30 to 40 degrees at the sternoclavicular joint and rotates posteriorly about its long axis, which allows the scapula to finish upward rotation. If the clavicle cannot rotate (for example after acromioclavicular fusion), elevation is limited to roughly 110 to 120 degrees.

Two arthrokinematic rules drive many questions. The humeral head is convex moving on a concave glenoid, so the head glides opposite to the direction the shaft moves: during abduction the head rolls up and glides inferiorly; during flexion and internal rotation it glides posteriorly; during extension and external rotation it glides anteriorly. To gain abduction you therefore mobilize the humerus inferiorly; to gain external rotation, the traditional rule says anterior glide, although several studies show posterior glides also improve external rotation in adhesive capsulitis. Full elevation also requires external rotation of the humerus so the greater tubercle clears the acromion.

Force couples and scapular dyskinesis

Scapular upward rotation is produced by a force couple of the upper trapezius, lower trapezius and serratus anterior. The serratus also holds the medial border against the thorax and posteriorly tilts the scapula. At the glenohumeral joint the deltoid pulls the humerus upward, and the rotator cuff (especially infraspinatus, teres minor and subscapularis) compresses and depresses the head so the deltoid produces rotation rather than superior translation. When the cuff is weak or torn, the deltoid shears the head toward the acromion and the subacromial space narrows.

Scapular dyskinesis is any altered position or motion of the scapula: prominence of the medial border, early or excessive shrugging, or poor control on lowering. True winging of the medial border at rest or during a wall push up suggests long thoracic nerve palsy (serratus anterior); lateral winging with a depressed, laterally displaced scapula suggests spinal accessory nerve injury (trapezius), often after posterior triangle surgery. Dyskinesis from weakness or tightness (tight pectoralis minor, weak lower trapezius and serratus) is far more common than nerve palsy and responds to targeted exercise.

Subacromial pain and rotator cuff disease

The older term impingement described compression of the supraspinatus tendon and subacromial bursa between the humeral head and the coracoacromial arch. Current practice increasingly uses subacromial pain syndrome or rotator cuff related shoulder pain, because most of the problem is a tendinopathy driven by load and age rather than mechanical pinching. The exam may still use the Neer stages, so know them: stage I, edema and hemorrhage, typically under 25 years, reversible; stage II, fibrosis and tendinitis, about 25 to 40 years; stage III, bone spurs and tendon rupture, over 40 years.

External impingement is classified as primary (structural narrowing: hooked type III acromion, acromioclavicular osteophytes) or secondary (functional narrowing from instability, cuff weakness, scapular dyskinesis or posterior capsule tightness). Internal impingement is a different entity: in the throwing athlete in abduction and external rotation, the articular side of the posterior supraspinatus and infraspinatus is pinched between the greater tuberosity and the posterosuperior glenoid and labrum. Throwers often show glenohumeral internal rotation deficit (GIRD), a loss of internal rotation of 20 degrees or more compared with the other side (or a loss of total arc), linked to posterior capsule tightness; the sleeper stretch and cross body stretch are the usual treatments.

Typical findings of rotator cuff related pain: lateral shoulder or upper arm pain (deltoid region), worse with overhead reaching and lying on the side, a painful arc between about 60 and 120 degrees, pain and possible weakness on resisted abduction and external rotation, and full or near full passive motion. Passive motion that is well preserved separates cuff disease from adhesive capsulitis.

Full thickness tears increase with age; many are asymptomatic in people over 60. The supraspinatus is torn most often. A large tear produces weakness and the inability to hold the arm raised (positive drop arm test), external rotation lag sign and hornblower sign (teres minor). An acute tear in a younger person after trauma, or an acute traumatic tear with marked weakness in any age, warrants early surgical referral; degenerative tears in older adults are first managed with exercise, which many patients do as well with as with surgery.

Conservative management of cuff related pain emphasizes progressive loading of the cuff and scapular muscles: isometrics for pain relief early, then isotonic external rotation, scaption below shoulder height, rows, serratus punch and lower trapezius work, progressing to overhead and functional loading. Add posterior capsule stretching when internal rotation is limited, thoracic mobility and education on load management. Subacromial decompression surgery has not been shown to beat exercise for most patients.

Shoulder instability

Instability ranges from subtle subluxation to frank dislocation. A useful classic split is TUBS (traumatic, unidirectional, Bankart lesion, often requires surgery) versus AMBRI (atraumatic, multidirectional, bilateral, treated with rehabilitation, and inferior capsular shift if rehab fails). About 95 percent of dislocations are anterior, from a force on the abducted and externally rotated arm. Associated lesions: a Bankart lesion (avulsion of the anteroinferior labrum and inferior glenohumeral ligament, sometimes with a bony fragment) and a Hill Sachs lesion (impaction fracture of the posterolateral humeral head against the glenoid rim). The axillary nerve is the nerve most often injured with anterior dislocation and proximal humerus fracture: check deltoid strength and sensation over the lateral shoulder (the regimental badge area). Posterior dislocation is associated with seizures and electric shock; the arm is held in internal rotation and cannot be externally rotated.

Recurrence after a first anterior dislocation is very high in young athletes (often quoted as well over half under age 20 to 25) and much lower in older adults, in whom an associated cuff tear is more common. SLAP lesions (superior labrum anterior to posterior) cause deep pain and clicking in throwers.

Adhesive capsulitis

Adhesive capsulitis (frozen shoulder) is inflammation followed by fibrosis of the glenohumeral capsule, producing painful, progressive loss of both active and passive motion in a capsular pattern: external rotation lost most, then abduction, then internal rotation (some sources list flexion with internal rotation; external rotation is always first). It is most common in people aged 40 to 65, in women, and strongly associated with diabetes mellitus (and thyroid disease); diabetic cases tend to be more severe and prolonged. The course is often described in stages: freezing (painful, pain dominant, motion beginning to decrease), frozen (stiffness dominant, pain easing), and thawing (gradual return of motion), lasting a year or more in total.

Management follows tissue irritability. In the high irritability stage use pain relieving modalities, gentle low grade mobilization (grades I and II), pendulums and pain free active assisted range; an intra articular corticosteroid injection combined with mobility exercise gives faster short term improvement and is recommended by the clinical practice guideline. As irritability falls, progress to sustained end range stretching and grade III and IV mobilization.

Special tests of the shoulder

No single shoulder test is diagnostic. Clusters work better: for a full thickness supraspinatus tear, a painful arc plus a positive drop arm test plus weakness in external rotation raises the probability considerably; for subacromial pain, a combination of Hawkins Kennedy, painful arc and infraspinatus weakness performs well. Use apprehension and relocation together for anterior instability.

Section 2Shoulder surgery and rehabilitation

Principles that apply to every shoulder protocol

Postoperative shoulder rehabilitation is governed by three questions: what tissue was repaired or replaced, what motion or load stresses that tissue, and how long that tissue needs before it tolerates the stress. Tendon to bone healing after rotator cuff repair takes roughly 12 weeks to reach useful strength and continues to mature for months; labral and capsular repairs need about 6 weeks of protection; a subscapularis tenotomy or peel during arthroplasty must be protected from stretch and active load for about 6 weeks. When a stem gives a protocol, follow it; when it does not, apply the tissue logic.

Progression between phases should be criterion based as well as time based. Typical criteria: pain controlled at rest and with the current exercises, passive range targets reached, no signs of a failed repair (sudden loss of active motion, a new pop with weakness), adequate strength (often expressed as a percentage of the uninvolved side) and normal scapular control before overhead or plyometric loading.

Rotator cuff repair

The repaired supraspinatus is under tension when the arm is adducted and is stressed most by active elevation and by passive motion beyond what the surgeon allows. Retear rates rise with age, tear size, fatty infiltration of the muscle, smoking and diabetes, and most retears happen in the first 3 to 6 months. Larger repairs and poorer tissue are progressed more slowly.

Stabilization procedures

An arthroscopic Bankart repair reattaches the anteroinferior labrum and capsule to the glenoid rim. The tissue at risk is stretched by external rotation combined with abduction and by extension. Typical restrictions: sling for about 4 to 6 weeks; external rotation limited (often to about 30 degrees at the side in the first weeks, progressing gradually); no combined abduction and external rotation (the apprehension position) for about 6 weeks or longer; no extension behind the body. Isometrics and scapular work begin early; strengthening progresses from about 6 to 12 weeks; contact and overhead sport usually waits 4 to 6 months. A Latarjet procedure (transfer of the coracoid with the conjoined tendon to the anterior glenoid) is used for glenoid bone loss and recurrent instability; it protects the subscapularis and the bone block. Posterior stabilization reverses the logic: avoid internal rotation, horizontal adduction and flexion with internal rotation (posterior capsule stress).

A SLAP repair protects the biceps anchor: avoid resisted elbow flexion and forearm supination and avoid loaded biceps activity for about 6 weeks; limit external rotation in abduction early, because the peel back mechanism stresses the superior labrum. A biceps tenodesis also avoids resisted elbow flexion and supination for about 6 weeks.

Total shoulder arthroplasty

An anatomic total shoulder arthroplasty replaces the humeral head and resurfaces the glenoid. It requires a functioning rotator cuff and is used for glenohumeral osteoarthritis with an intact cuff. The deltopectoral approach detaches the subscapularis (tenotomy, peel or lesser tuberosity osteotomy), so the main early precautions protect that repair: limit passive external rotation (often to about 30 degrees, per surgeon) for about 6 weeks, no active internal rotation or resisted internal rotation for about 6 weeks, no lifting heavier than a cup of coffee, no supporting body weight with the hand (such as pushing up from a chair). The operated arm is typically supported so the elbow sits slightly forward of the trunk when lying supine, avoiding extension. Subscapularis failure produces weakness in internal rotation, a positive lift off or belly press and anterior instability.

A hemiarthroplasty replaces only the humeral head (for some fractures or when the glenoid cannot be resurfaced). After fracture fixation or hemiarthroplasty, tuberosity healing is the main concern, so active motion often waits until the tuberosities have united.

Reverse total shoulder arthroplasty

A reverse total shoulder arthroplasty (rTSA) puts a ball (the glenosphere) on the glenoid and a socket on the humerus. This moves the center of rotation medially and inferiorly, lengthening the deltoid lever arm and tensioning the deltoid so that it can elevate the arm without a rotator cuff. It is indicated for cuff tear arthropathy, massive irreparable cuff tears with pseudoparalysis, complex proximal humerus fractures in older adults and failed previous arthroplasty. Because rehabilitation depends on the deltoid, the emphasis is on deltoid and scapular strengthening; strengthening the absent cuff is not the goal, and full external and internal rotation are often not achievable.

The key risk is dislocation, which typically occurs with the arm in extension, adduction and internal rotation together, the position used to reach behind the back to tuck in a shirt or perform toileting hygiene, or to push up from a chair with the arm behind the body. Classic early precautions (about 12 weeks): no combined shoulder extension, adduction and internal rotation; no reaching behind the back; no extension past neutral (keep the elbow in front of the trunk, using a pillow under the elbow in supine); no supporting body weight with the operated arm; no lifting more than a light object. The acromion takes much more deltoid load after rTSA, so new acute pain over the acromion with loss of elevation suggests an acromial stress fracture.

Section 3The elbow and forearm

Lateral and medial epicondylalgia

Lateral epicondylalgia (tennis elbow) is a degenerative tendinopathy of the common extensor origin, chiefly the extensor carpi radialis brevis. Histology shows disorganized collagen and new vessels rather than inflammatory cells, which is why the terms tendinopathy or epicondylalgia are preferred to epicondylitis. It peaks between 35 and 55 years and is linked to repetitive gripping and wrist extension, in manual work more than in tennis. Findings: pain at or just distal to the lateral epicondyle, pain with resisted wrist extension and resisted middle finger extension, pain with passive wrist flexion with the elbow extended, and reduced pain free grip strength (the most useful outcome measure). Cozen test (resisted wrist extension with a fist) and Mill test (passive stretch into wrist flexion, pronation and elbow extension) reproduce pain.

Management: load modification, progressive tendon loading (isometrics for pain, then eccentric and concentric wrist extensor strengthening), a counterforce brace placed distal to the painful area, manual therapy including mobilization with movement of the elbow, and attention to cervical and thoracic contributions. Corticosteroid injection gives good short term relief but worse outcomes and more recurrence at one year than physical therapy or waiting, a classic exam point.

Medial epicondylalgia (golfer's elbow) affects the common flexor and pronator origin (pronator teres and flexor carpi radialis). Pain is reproduced by resisted wrist flexion and pronation and by passive wrist extension with elbow extension. It is often accompanied by ulnar neuropathy at the elbow, so always check ulnar nerve sensation and intrinsic strength.

Ulnar collateral ligament injury

The ulnar collateral ligament (UCL), especially its anterior bundle, is the primary restraint to valgus stress between about 20 and 120 degrees of elbow flexion. During the late cocking and early acceleration phases of throwing, huge valgus torque stretches the UCL, compresses the lateral radiocapitellar joint and shears the posteromedial olecranon (the valgus extension overload pattern). Overhead throwers present with medial elbow pain during throwing, loss of velocity and sometimes ulnar paresthesia. Tests: valgus stress test at about 20 to 30 degrees of flexion, milking maneuver and the moving valgus stress test (pain between about 70 and 120 degrees of flexion as the elbow is extended under valgus load). Partial tears are rehabilitated; complete tears in throwers who wish to return are often reconstructed with a tendon graft (commonly palmaris longus). After UCL reconstruction, valgus stress is avoided for months, a hinged brace is used early, and an interval throwing program usually begins around 4 months, with return to competitive pitching often taking 12 months or more. In young throwers the same forces cause medial epicondyle apophysitis (Little League elbow); pitch count limits and rest are the main prevention.

Fractures and dislocations around the elbow

The elbow stiffens quickly, so early protected motion matters, and its neurovascular structures are vulnerable. Know these patterns:

• Supracondylar humerus fracture: the most common elbow fracture in children, from a fall on an outstretched hand with the elbow hyperextended. Risks: brachial artery injury, anterior interosseous nerve palsy (most common nerve injury; cannot make the OK sign), and Volkmann ischemic contracture from compartment syndrome of the forearm flexors. Pain with passive finger extension, increasing pain out of proportion and tense forearm swelling are emergencies.
• Radial head fracture: the most common elbow fracture in adults, from a fall on an outstretched hand. Nondisplaced fractures are treated with brief sling use and early active motion within days. Look for associated injuries: the Essex Lopresti lesion (radial head fracture with interosseous membrane disruption and distal radioulnar joint injury).
• Olecranon fracture: from a direct fall on the elbow; displaced fractures need fixation because the triceps pulls the fragment proximally. Avoid resisted elbow extension until healed.
• Elbow dislocation: usually posterior, the second most commonly dislocated major joint in adults. The terrible triad is posterior dislocation with radial head and coronoid fractures. Stable reductions are moved early in a hinged brace; loss of extension is the commonest long term problem.
• Monteggia (proximal ulna fracture with radial head dislocation; posterior interosseous nerve at risk) and Galeazzi (distal radius shaft fracture with distal radioulnar joint dislocation) fracture dislocations.

Heterotopic ossification and myositis ossificans of the brachialis are risks after elbow trauma, especially if the elbow is forcefully stretched. Avoid aggressive passive stretching after elbow trauma; use active motion, gentle low load prolonged stretch and static progressive orthoses instead.

Nerve entrapments around the elbow

Three nerves cross the elbow, and each has typical entrapment sites. Recognizing the motor and sensory pattern localizes the lesion.

Section 4The wrist and hand

Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is compression of the median nerve beneath the transverse carpal ligament, the most common entrapment neuropathy. Risk factors include female sex, pregnancy, diabetes, hypothyroidism, rheumatoid arthritis, obesity and repetitive forceful wrist flexion with vibration. Symptoms: numbness and tingling in the thumb, index, middle and radial half of the ring finger, worse at night and relieved by shaking the hand (the flick sign); clumsiness; in advanced cases thenar atrophy and weakness of abductor pollicis brevis and opponens pollicis. The palmar cutaneous branch leaves the median nerve proximal to the tunnel, so sensation over the thenar eminence is spared in CTS (thenar numbness suggests a more proximal lesion).

Tests include Phalen (sustained wrist flexion for up to 60 seconds reproduces symptoms), Tinel at the carpal tunnel, and the carpal compression test (Durkan), which is among the more sensitive. Nerve conduction studies show prolonged distal latency of the median nerve. Conservative care, recommended by the clinical practice guideline for mild to moderate cases: a neutral wrist orthosis worn at night, education to avoid sustained end range wrist positions, nerve and tendon gliding, and possibly corticosteroid injection. Thenar atrophy or persistent sensory loss warrants surgical referral for carpal tunnel release, after which scar management, gentle motion and gradual grip strengthening follow; pillar pain at the base of the palm is common for weeks.

De Quervain tenosynovitis and other tendinopathies

De Quervain tenosynovitis is thickening of the tendon sheath of the first dorsal compartment, containing the abductor pollicis longus and extensor pollicis brevis, at the radial styloid. It is common in new parents lifting infants, in middle aged women and with repetitive thumb use. Finkelstein test (examiner deviates the wrist ulnarly while the thumb is held flexed) and the more specific Eichhoff variant (patient grasps the thumb in a fist before ulnar deviation) reproduce pain over the radial styloid; the WHAT test (wrist hyperflexion and abduction of the thumb) is also described. Treatment: a thumb spica orthosis that leaves the interphalangeal joint free, activity modification, and corticosteroid injection, which is often effective. Distinguish it from intersection syndrome (pain and crepitus about 4 to 6 cm proximal to the wrist where the first compartment crosses the second, often in rowers) and from first carpometacarpal osteoarthritis (positive grind test at the thumb base).

Trigger finger is a flexor tendon catching at the A1 pulley, common in diabetes.

Wrist fractures and instability

After a distal radius fracture, the cast or orthosis is typically worn about 6 weeks. During that time, active motion of the fingers, elbow and shoulder prevents stiffness and swelling. After immobilization, active and active assisted wrist and forearm motion progress to strengthening. Monitor for complex regional pain syndrome: burning pain out of proportion, swelling, color and temperature change, and hypersensitivity. Early recognition, desensitization, graded motor imagery and active use are key.

Tendon injuries and flexor zones

The flexor tendon zones guide prognosis and protocols. Zone II, between the A1 pulley at the distal palmar crease and the insertion of flexor digitorum superficialis at the middle phalanx, contains both flexor tendons inside a tight fibro osseous sheath, so adhesions form easily. It was historically called no man's land. Zone I lies distal to the FDS insertion (FDP only; a jersey finger is an avulsion of FDP, most often of the ring finger, when a grabbing finger is forcibly extended). Zone III is the palm, zone IV the carpal tunnel and zone V the wrist and forearm.

After flexor tendon repair, the hand is placed in a dorsal blocking orthosis with the wrist in slight flexion (or neutral), MCP joints flexed about 50 to 70 degrees and interphalangeal joints extended against the orthosis. The aim is to permit tendon gliding without tension on the repair. Classic early protocols: passive flexion with active extension within the orthosis (Duran style passive motion; Kleinert style rubber band traction) or early active motion (place and hold or controlled active flexion), now favored for strong multistrand repairs. Avoid active gripping, passive extension of the wrist and fingers together and resisted flexion for about 6 to 8 weeks; light resistance usually begins around 8 weeks and full strengthening around 12 weeks. A repaired tendon is weakest around days 5 to 21, when rupture risk peaks.

Extensor injuries: a mallet finger is disruption of the terminal extensor tendon at the distal phalanx (zone I) and is treated with continuous DIP extension splinting for about 6 to 8 weeks with the PIP free; any flexion of the DIP during that time restarts the clock. A rupture of the central slip (zone III) allows the lateral bands to slip volarly and leads to a boutonniere deformity; it is splinted with the PIP in extension and the DIP free to flex actively.

Deformities

Splinting principles

Orthoses immobilize (rest inflamed or repaired tissue), mobilize (apply low load prolonged stress to lengthen tissue, as with dynamic or static progressive designs) or restrict motion. The safe position or intrinsic plus position for immobilizing the hand is wrist in about 20 to 30 degrees of extension, MCP joints in 70 to 90 degrees of flexion and IP joints in full extension, which keeps the MCP collateral ligaments and the IP volar plates at length so the hand does not stiffen. A resting hand orthosis in a functional position is used for rheumatoid arthritis flares. Check every orthosis for pressure points over bony prominences, especially in insensate skin, and teach a wearing schedule and skin checks.

Section 5Peripheral nerve injuries of the upper limb

The brachial plexus

The brachial plexus forms from the ventral rami of C5 to T1 and is organized as roots, trunks, divisions, cords and terminal branches (a common memory aid is "Read That Darn Cadaver Book"). C5 and C6 join as the upper trunk, C7 continues as the middle trunk, and C8 and T1 form the lower trunk. Each trunk splits into anterior and posterior divisions. The three posterior divisions form the posterior cord (axillary and radial nerves), the anterior divisions of the upper and middle trunks form the lateral cord (musculocutaneous nerve and the lateral root of the median nerve), and the anterior division of the lower trunk forms the medial cord (ulnar nerve and the medial root of the median nerve). Branches from the roots include the dorsal scapular (C5, rhomboids) and long thoracic (C5 to C7, serratus anterior); from the upper trunk the suprascapular nerve (supraspinatus and infraspinatus).

Erb palsy (upper trunk, C5 and C6) results from forced separation of the head and shoulder (birth with shoulder dystocia, motorcycle falls). The deltoid, cuff, biceps and brachialis are weak, producing the waiter's tip posture. Klumpke palsy (lower trunk, C8 and T1) results from traction on the abducted arm (grabbing a branch while falling, breech birth). It weakens the intrinsic hand muscles and long finger flexors and may include Horner syndrome (ptosis, miosis, anhidrosis) if T1 sympathetic fibers are injured, which also suggests a root avulsion with a poor prognosis. Thoracic outlet syndrome most commonly compresses the lower trunk, giving ulnar side symptoms; provocative tests (Adson, Roos elevated arm stress test, Wright hyperabduction) have poor specificity.

Radial, median and ulnar nerve lesions

Froment sign: when pinching paper between thumb and index finger, the thumb IP joint flexes because flexor pollicis longus (median) substitutes for a weak adductor pollicis (ulnar). Wartenberg sign: the little finger rests abducted from weak third palmar interosseous. The ulnar paradox: a more proximal ulnar lesion produces less clawing because FDP to the ring and little fingers is also paralyzed, so the IP joints are not pulled into flexion. The same logic applies to median lesions; a high median lesion causes the benediction posture on attempting a fist, while a low median lesion leaves finger flexion intact.

Seddon classification, recovery and testing

After axonal injury the distal segment undergoes Wallerian degeneration. Regeneration proceeds at roughly 1 mm per day, so a lesion 30 cm above a muscle needs about 10 months to reach it; motor end plates degenerate if reinnervation takes much beyond 12 to 18 months, so proximal lesions recover less. An advancing Tinel sign along the nerve tracks regrowth. Needle EMG should be delayed about 3 weeks after injury, because fibrillation potentials and positive sharp waves take that long to appear. Sensory recovery typically returns in sequence: pain and temperature, then touch, then moving two point discrimination, then static two point discrimination. Test with Semmes Weinstein monofilaments (the 4.31 filament marks the threshold of normal light touch on the hand in common teaching, and inability to feel 6.65 means loss of protective sensation) and two point discrimination (normal fingertip static value about 6 mm or less).

Rehabilitation during recovery: protect anesthetic skin with visual checks and education (burns and pressure injury are the main hazards), maintain passive range and prevent contracture with orthoses (a wrist cock up orthosis or dynamic extension orthosis for radial palsy, a thumb web spacer for median palsy, an anticlaw MCP blocking orthosis for ulnar palsy), avoid overstretching denervated muscle, begin active assisted and then resisted exercise as muscle reinnervates, and use desensitization and sensory reeducation.

Words worth knowing