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9. Shoulder and Elbow MCQs

Practice Set 84 of 197

This practice set contains high-yield board review questions covering key concepts in 9. Shoulder and Elbow. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1661

Topic: 9. Shoulder and Elbow

A 64-year-old man who was involved in a high-speed motor vehicle accident 6 weeks ago has been in the ICU with a closed head injury. Examination reveals that his range of motion for external rotation to the side is -30 degrees. Radiographs are shown in Figures 28a and 28b. What is the most likely diagnosis?

. Adhesive capsulitis
. Calcific tendinitis
. Anterior shoulder dislocation
. Posterior shoulder dislocation
. Glenohumeral osteoarthritis

Correct Answer & Explanation

. Posterior shoulder dislocation

Explanation

The patient has a posterior shoulder dislocation. The AP radiograph shows overlapping of the humeral head on the glenoid. The scapular Y view shows his humeral articular surface posterior to the glenoid. The posterior shoulder dislocation is frequently missed because the patient is comfortable in the "sling" position with the arm adducted and internally rotated across the abdomen. The marked restriction in external rotation on examination raises the suspicion of a posterior dislocation, adhesive capsulitis, or glenohumeral osteoarthritis. The posterior dislocation is diagnosed based on the radiographic findings. An axillary view or CT is recommended to better evaluate the dislocation. Robinson CM, Aderinto J: Posterior shoulder dislocations and fracture-dislocations. J Bone Joint Surg Am 2005;87:639-650.

Question 1662

Topic: 9. Shoulder and Elbow

A 21-year-old man who underwent repair of a distal biceps tendon rupture using a two-incision approach 4 months ago now reports difficulty gaining rotation of his forearm. Figures 49a and 49b show the AP and lateral radiographs. What is the most likely cause of his problem?

. Inadequate physical therapy
. Exposure of the periosteum of the lateral ulna during surgery
. Inappropriate location of the suture anchor
. Fixation of the tendon with the forearm fully pronated
. Subluxation of the radial head

Correct Answer & Explanation

. Exposure of the periosteum of the lateral ulna during surgery

Explanation

The radiographs show early ectopic bone formation originating between the ulna and the radius. The development of ectopic bone in this area following a two-incision approach for anatomic repair of the distal biceps tendon is thought to be related to exposure of the periosteum of the lateral ulna during surgery. This can be avoided by the use of a muscle-splitting incision between the extensor carpi ulnaris and common extensor muscles. Full pronation of the forearm allows for the necessary exposure of the radial tuberosity during the procedure and for fixation of the tendon at its maximal length. Morrey BF: Tendon injuries about the elbow, in Morrey BF (ed): The Elbow and Its Disorders, ed. 2. Philadelphia, PA, WB Saunders, 1993, pp 492-503.

Question 1663

Topic: 9. Shoulder and Elbow

While lifting weights, a patient feels a pop in his arm. He has the deformity shown in Figure 30. If left untreated, the patient will have the greatest deficiency in

Sports Medicine 2004 Practice Questions: Set 3 (Solved) - Figure 16

. shoulder flexion.
. elbow flexion.
. forearm pronation.
. forearm supination.
. wrist flexion.

Correct Answer & Explanation

. forearm supination.

Explanation

The patient has a distal biceps rupture. While the distal biceps contributes to elbow flexion, its main function is forearm supination. Baker BE, Bierwagen D: Rupture of the distal tendon of the biceps brachii: Operative versus non-operative treatment. J Bone Joint Surg Am 1985;67:414-417. D'Arco P, Sitler M, Kelly J, et al: Clinical, functional, and radiographic assessments of the conventional and modified Boyd-Anderson surgical procedures for repair of distal biceps tendon ruptures. Am J Sports Med 1998;26:254-261.

Question 1664

Topic: 9. Shoulder and Elbow

A 37-year-old recreational tennis player undergoes surgery for tennis elbow. Following surgery, she describes clicking and popping on the lateral aspect of the elbow. A lateral pivot shift test is positive. What is the most likely cause of her symptoms?

. Injury to the anterior band of the medial collateral ligament
. Injury to the radial nerve
. Injury to the lateral ulnar collateral ligament
. Injury to the lateral radial collateral ligament
. Excessive dissection of the extensor carpi radialis brevis origin

Correct Answer & Explanation

. Injury to the lateral ulnar collateral ligament

Explanation

The patient has a posterolateral rotatory instability (PLRI) of the elbow that is most likely the result of iatrogenic injury to the lateral ulnar collateral ligament, the main ligament implicated in PLRI. The anterior band of the medial collateral ligament is implicated in valgus instability. Injury to the radial nerve is unlikely, and the lateral radial collateral ligament makes less of a contribution to elbow stability than does the ulnar component. While the origin of the extensor carpi radialis brevis may contribute to elbow stability, it is not as important a stabilizer as the lateral ulnohumeral ligament. O'Driscoll SW, Morrey BF: Surgical reconstruction of the lateral collateral ligament, in Morrey BF (ed): The Elbow. Philadelphia, PA, Lippincott, Williams and Wilkins, 1994, pp 169-182.

Question 1665

Topic: 9. Shoulder and Elbow

A 49-year-old woman noted pain in her right axilla 1 day after moving heavy furniture. Two weeks later, she now reports persistent numbness and paresthesias along the inner aspect of her upper arm radiating into the ulnar digits. Examination reveals full shoulder motion, tenderness over the first rib, and a decreased radial pulse with the shoulder placed overhead. What is the most likely diagnosis?

Shoulder Board Review 2002: High-Yield MCQs (Set 2) - Figure 26

. Brachial plexus stretch injury
. Cervical radiculopathy
. Rotator cuff tendinitis
. Anterior subluxation of the shoulder
. Thoracic outlet syndrome

Correct Answer & Explanation

. Thoracic outlet syndrome

Explanation

Thoracic outlet syndrome is thought to be caused by compression of the neurovascular supply to the upper limb in the supraclavicular and axillary regions of the shoulder. While typically progressive in onset, thoracic outlet syndrome may develop after acute injury. Injury or weakness of the scapular muscles, especially the trapezius, may result in descent of the scapula and cause compression of the thoracic outlet. In general, most symptoms are the result of neural compression. Typical symptoms include pain in the neck or shoulder and numbness or tingling that predominantly involves the ulnar side of the arm and hand. Exacerbation of these symptoms is typical when the arm is abducted. Initial management should consist of postural exercises aimed at restoring proper scapular stability. Severe recalcitrant symptoms may warrant surgical decompression. Leffert RD: Thoracic outlet syndrome. J Am Acad Orthop Surg 1994;2:317-325.

Question 1666

Topic: 9. Shoulder and Elbow

A 23-year-old baseball pitcher who has diffuse pain along the posterior deltoid reports pain during late acceleration and follow-through. Examination of his arc of motion from external rotation to internal rotation at 90 degrees of shoulder abduction reveals a significant deficit in internal rotation when compared to the nonthrowing shoulder. Initial management should consist of

Sports Medicine 2004 Practice Questions: Set 1 (Solved) - Figure 3

. a cortisone injection to the subscapular bursa.
. posterior capsular stretching.
. strengthening of the external rotators and scapular stabilizers.
. continued pitching and working through the pain.
. a sling and rest.

Correct Answer & Explanation

. posterior capsular stretching.

Explanation

Loss of internal rotation is common among overhead throwers and tennis players. Posterior capsular stretching can improve symptoms when accompanied by rest and gradual resumption of throwing. To avoid a false impression of improvement, cortisone injection is not recommended. Pitching through pain can cause further damage to the labrum and capsule. A sling and external rotator strengthening will not improve internal rotation. Kibler WB: Biomechanical analysis of the shoulder during tennis activities. Clin Sports Med 1995;14:79-85.

Question 1667

Topic: 9. Shoulder and Elbow

What is the most important stabilizing mechanism in the midrange of motion of the glenohumeral joint?

. Concavity compression
. Isometric articular ligaments
. Increased tensile force of the capsule
. Biceps tendon
. Deltoid contraction

Correct Answer & Explanation

. Concavity compression

Explanation

Concavity compression is a stabilizing mechanism by which muscular compression of the humeral head into the glenoid fossa stabilizes the glenohumeral joint against shear forces. This is dependent on the depth of the concavity and the magnitude of the compressive force. Lee SB, Kim KJ, O'Driscoll SW, et al: Dynamic glenohumeral stability provided by the rotator cuff muscles in the mid-range and end-range of motion: A study in cadavera. J Bone Joint Surg Am 2000;82:849-857.

Question 1668

Topic: 9. Shoulder and Elbow

Figure 42 is a transverse MRI scan of the left shoulder. The arrow points to which of the following structures?

Anatomy Board Review 2002: High-Yield MCQs (Set 4) - Figure 1

. Anterior labrum
. Long head of the biceps tendon
. Middle glenohumeral ligament
. Lower glenohumeral ligament
. Axillary nerve

Correct Answer & Explanation

. Long head of the biceps tendon

Explanation

The figure shows an axial image of the shoulder immediately inferior to the coracoid process. The subscapularis tendon, which can be traced from the myotendinous junction, is torn and detached from its lesser tuberosity attachment on the humerus. Lateral to the lesser tuberosity, the bicipital groove is empty. The arrow points to the subluxated biceps tendon. Superficial fibers of the subscapularis tendon are contiguous with the biceps retinaculum, which covers the bicipital groove and hold the biceps tendon in place. The vast majority of subscapularis tendon tears result in disruption of the biceps retinaculum with resultant subluxation of the tendon. Resnick D, Kang HS (eds): Internal Derangement of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 308-317.

Question 1669

Topic: 9. Shoulder and Elbow

What is the first ossification center to appear radiographically in the pediatric elbow?

Anatomy Board Review 2005: High-Yield MCQs (Set 2) - Figure 33

. Trochlea
. Olecranon
. Radial head
. Capitellum
. Medial epicondyle

Correct Answer & Explanation

. Capitellum

Explanation

The first ossification center to appear in the pediatric elbow is the capitellum. This ossification center generally appears between the first month and the 11th month in girls and between the first month and the 26th month in boys. The other ossification centers in the elbow appear in the following progression: radial head (3.8 to 4.5 years), medial epicondyle (5 to 6 years), olecranon (6 to 7 years), trochlea (9 to 10 years), and the lateral epicondyle (10 years). Wilkins KE, Beaty JH, Chambers HG, et al: Fractures and dislocation of the elbow region, in Rockwood CA, Green DP, Bucholz RW, et al (eds): Rockwood and Green's Fractures in Adults, ed 4. Philadelphia, PA, Lippincott-Raven, 1996, pp 657-662.

Question 1670

Topic: 9. Shoulder and Elbow

A baseball player has had diffuse scapular soreness for the past 8 weeks. He reports that it began insidiously over several days and gradually has become worse. He denies any history of trauma. Examination reveals drooping of the shoulder, with lateral winging of the scapula at rest. He is otherwise neurologically intact. What is the best course of action?

. Immediate MRI of the brain
. Electromyography and nerve conduction velocity studies
. Physical therapy and observation
. Lyme titer
. Psychiatric consultation

Correct Answer & Explanation

. Electromyography and nerve conduction velocity studies

Explanation

Lateral scapular winging is characteristic of trapezius palsy, whereas medial scapular winging is characteristic of long thoracic nerve palsy. During sports activity, injury to the spinal accessory nerve is rare but may occur with blunt or stretching trauma. Patients often report an asymmetric neckline, drooping shoulder, winging of the scapula, and weakness of forward elevation. Evaluation should include a complete electrodiagnostic examination. Wiater JM, Bigliani LU: Spinal accessory nerve injury. Clin Orthop 1999;368:5-16. Wiater JM, Flatow EL: Long thoracic nerve injury. Clin Orthop 1999;368:17-27. Mariani PP, Santoriello P, Maresca G: Spontaneous accessory nerve palsy. J Shoulder Elbow Surg 1998;7:545-546. Porter P, Fernandez GN: Stretch-induced spinal accessory nerve palsy: A case report. J Shoulder Elbow Surg 2001;10:92-94.

Question 1671

Topic: 9. Shoulder and Elbow

A 49-year-old woman with serologically proven rheumatoid arthritis has Larsen grade II radiographic changes in the elbow. Examination reveals a preoperative arc of flexion of less than 90 degrees and there is no instability. Nonsurgical management has failed to provide relief. What is the best treatment option?

Upper Extremity 2008 Practice Questions: Set 1 (Solved) - Figure 34

. Semiconstrained total elbow arthroplasty
. Unlinked total elbow arthroplasty
. Fascial arthroplasty
. Open synovectomy
. Arthroscopic synovectomy

Correct Answer & Explanation

. Arthroscopic synovectomy

Explanation

Larsen grade I and II rheumatoid arthritis is best treated with synovectomy with arthroplasty reserved for later stages, especially in younger patients. Open synovectomy with or without a radial head excision has yielded good results for pain and function, with arthroscopic synovectomies yielding similar results. Arthroscopic synovectomy has been shown to be more effective in restoring function in patients with a flexion arc of less than 90 degrees. Tanaka N, Sakahashi H, Hirose K, et al: Arthroscopic and open synovectomy of the elbow in rheumatoid arthritis. J Bone Joint Surg Am 2006;88:521-525. Horiuchi K, Momohara S, Tomatsu T, et al: Arthroscopic synovectomy of the elbow in rheumatoid arthritis. J Bone Joint Surg Am 2002;84:342-347.

Question 1672

Topic: 9. Shoulder and Elbow

A 28-year-old woman sustained an injury to her dominant right arm after falling off her porch. Examination reveals a deformity at the elbow. She is neurovascularly intact. Figures 46a and 46b show the radiographs obtained before closed reduction, and postreduction radiographs are shown in Figure 46c and 46d. What is the most likely early complication?

. Radial nerve injury
. Intra-articular loose body causing a block to motion
. Lack of active elbow flexion
. Recurrent dislocation
. Forearm compartment syndrome

Correct Answer & Explanation

. Recurrent dislocation

Explanation

The patient has a complex fracture-dislocation of the elbow. The radial head is fractured, and there is a displaced coronoid fracture. These associated fractures indicate that the elbow is at high risk for recurrent instability after initial treatment. To prevent this complication, surgical treatment will most likely be required and will consist of some or all of the following: radial head open reduction and internal fixation or replacement, coronoid open reduction and internal fixation, medial and lateral ligament repairs, and even articulated external fixation. This patient was treated with open reduction and internal fixation of the radial head, and the elbow redislocated postoperatively. Ring D, Jupiter JB: Reconstruction of posttraumatic elbow instability. Clin Orthop 2000;370:44-56. O'Driscoll SW: Classification and evaluation of recurrent instability of the elbow. Clin Orthop 2000;370:34-43.

Question 1673

Topic: 9. Shoulder and Elbow

Figure 37 shows a coronal T2-weighted MRI scan. What is the name of the labeled torn structure?

Upper Extremity Board Review 2008: High-Yield MCQs (Set 4) - Figure 1

. Brachialis tendon
. Biceps tendon
. Flexor/pronator origin
. Medial collateral ligament (MCL)
. Lateral collateral ligament (LCL)

Correct Answer & Explanation

. Lateral collateral ligament (LCL)

Explanation

The labeled structure is the LCL, and it is avulsed from the lateral humeral epicondyle. This is the most common site of injury for the LCL. The biceps and brachialis tendon insertions are not well visualized in this section. The MCL and flexor/pronator origin are intact. Potter HG, Weiland AJ, Schatz JA, et al: Posterolateral rotatory instability of the elbow: Usefulness of MR imaging in diagnosis. Radiology 1997;204:185-189.

Question 1674

Topic: Shoulder Pathology

A 50-year-old man reports left shoulder pain and weakness after undergoing a lymph node biopsy in his neck 2 years ago. Examination reveals winging of the left scapula. Electromyography shows denervation of the trapezius. Surgical treatment for this condition involves

Sports Medicine 2007 Practice Questions: Set 1 (Solved) - Figure 10

. pectoralis transfer to the medial border of the scapula.
. pectoralis transfer to the inferior border of the scapula.
. lateral transfer of the levator scapulae only.
. lateral transfer of the levator scapulae and rhomboid minor and major.
. latissimus dorsi transfer.

Correct Answer & Explanation

. lateral transfer of the levator scapulae and rhomboid minor and major.

Explanation

The muscle transfer procedure most commonly performed for trapezius paralysis is the Eden-Lange procedure. Trapezius paralysis in this patient is secondary to iatrogenic injury to the spinal accessory nerve during lymph node biopsy. In this procedure, the levator scapulae and rhomboid minor and major muscles are transferred laterally. Pectoralis transfer to the inferior border of the scapula is used as a dynamic transfer for serratus anterior winging. Kuhn JE, Plancher KD, Hawkins RJ: Scapular winging. J Am Acad Orthop Surg 1995;3:319-325. Langenskiold A, Ryoppy S: Treatment of paralysis of the trapezius muscle by Eden-Lange operation. Acta Orthop Scand 1973;44:383-388.

Question 1675

Topic: 9. Shoulder and Elbow

A 40-year-old man who is an avid weight lifter has had chronic pain in the proximal anterior shoulder for the past year. He denies any history of trauma. Examination reveals tenderness at the intertubercular groove, a positive speed test, and a positive Neer impingement sign. Nonsurgical management has failed to provide relief, and he is now considering surgery. Arthroscopic findings in the glenohumeral joint are shown in Figure 31. Based on these findings, treatment should consist of

Upper Extremity 2005 Practice Questions: Set 3 (Solved) - Figure 16

. debridement of the biceps tendon.
. debridement of the rotator cuff tear.
. repair of the biceps pulley system.
. repair of the rotator cuff tear.
. tenodesis of the biceps tendon.

Correct Answer & Explanation

. tenodesis of the biceps tendon.

Explanation

The arthroscopic image shows a tear through more than 50% of the biceps tendon; therefore, treatment should consist of tenodesis or tenotomy of the tendon. However, because this patient is relatively young and active, the treatment of choice is tenodesis of the biceps tendon. Sethi N, Wright R, Yamaguchi K: Disorders of the long head of the biceps tendon. J Shoulder Elbow Surg 1999;8:644-654. Eakin CL, Faber KJ, Hawkins RJ, et al: Biceps tendon disorders in athletes. J Am Acad Orthop Surg 1999;7:300-310.

Question 1676

Topic: 9. Shoulder and Elbow

A 25-year-old woman returns for her first postoperative visit after arthroscopic thermal capsulorrhaphy for recurrent multidirectional instability. Examination reveals that the portals are healed, there is no swelling; and passive range of motion is within the normal range. However, she is unable to actively raise her arm. Shoulder radiographs are normal. What is the most likely cause of these findings?

Upper Extremity 2008 Practice Questions: Set 1 (Solved) - Figure 14

. Adhesive capsulitis
. Sling immobilization
. Thermal chondrolysis
. Subacromial impingement
. Axillary nerve injury

Correct Answer & Explanation

. Axillary nerve injury

Explanation

Treatment of shoulder instability with thermal devices has lead to numerous complications including recurrent instability, chondrolysis, stiffness, and capsular necrosis. This patient's findings are consistent with a heat-induced axillary nerve injury. Normal radiographs exclude extensive chondrolysis. Levine WN, Bigliani LU, Ahmad CS: Thermal capsulorrhaphy. Orthopedics 2004;27:823-826.

Question 1677

Topic: 9. Shoulder and Elbow

Figure 2 shows the radiograph of a 26-year-old auto mechanic who injured his right dominant elbow in a fall during a motocross race. Examination reveals pain and catching that limits his range of motion to 45 degrees of supination and 20 degrees of pronation. The interosseous space and distal radioulnar joint are stable. Management should consist of

Sports Medicine 2004 Practice Questions: Set 1 (Solved) - Figure 7

. splinting for 3 weeks, followed by range-of-motion exercises.
. aspiration of the hemarthrosis, followed by range-of-motion exercises the following day.
. fragment excision.
. open reduction and internal fixation.
. radial head excision.

Correct Answer & Explanation

. open reduction and internal fixation.

Explanation

The radial head is an important secondary stabilizer of the elbow, helping to resist valgus forces. There has been a movement toward open reduction and internal fixation of the radial head when technically feasible, especially in a relatively high-demand athlete or laborer. The examination and radiograph suggest that displacement of the fragment is great enough to create a mechanical block. Extended splinting would only serve to encourage arthrofibrosis. Early range of motion is appropriate if there is minimal displacement of the radial head fragement, it is stable, and there is no mechanical block to motion. Fragments larger than one third of the joint surface should be excised only if it is not possible to reduce and repair the fragment. Primary excision of the radial head should be avoided if possible. Complications after excision of the radial head include muscle weakness, wrist pain, valgus elbow instability, heterotopic ossification, and arthritis. Hotchkiss RN: Displaced fractures of the radial head: Internal fixation or excision? J Am Acad Orthop Surg 1997;5:1-10.

Question 1678

Topic: 9. Shoulder and Elbow

Figure 31 shows the AP and lateral radiographs of the elbow of a 56-year-old man with chronic polyarticular rheumatoid arthritis. His function continues to be limited by pain with activities of daily living. Examination shows that his total arc of motion is 110 degrees. Nonsurgical management has failed to provide relief. Treatment should now consist of

Shoulder 2002 Practice Questions: Set 3 (Solved) - Figure 6

. elbow fusion with a contoured dynamic compression plate.
. radial head excision and synovectomy.
. distraction arthroplasty with interpositional tissue.
. total elbow replacement with an unconstrained prosthesis.
. total elbow replacement with a semiconstrained prosthesis.

Correct Answer & Explanation

. total elbow replacement with a semiconstrained prosthesis.

Explanation

A semiconstrained prosthesis can provide excellent results in carefully selected patients. Because the radiographs show extensive joint destruction with loss of the capitellum and trochlea, a capitellocondylar total elbow (unconstrained) prosthesis is contraindicated. Elbow fusion is poorly accepted, and the radiographs show too much articular destruction for a radial head excision, synovectomy, or interposition arthroplasty to be effective. Ewald FC, Simmons ED Jr, Sullivan JA, et al: Capitellocondylar total elbow replacement in rheumatoid arthritis: Long-term results. J Bone Joint Surg Am 1993;75:498-507.

Question 1679

Topic: 9. Shoulder and Elbow

Figure 3 shows the radiographs of a 32-year-old man who fell 12 feet onto his outstretched arm and sustained a fracture-dislocation of the elbow. Initial management consisted of closed reduction of the dislocation. Surgical treatment should now include repair or reduction and fixation of the

Shoulder 2002 Practice Questions: Set 1 (Solved) - Figure 5

. medial and lateral collateral ligaments, radial head, and coronoid.
. medial collateral ligament and coronoid.
. lateral collateral ligament and radial head.
. medial and lateral collateral ligaments.
. radial head and coronoid.

Correct Answer & Explanation

. medial and lateral collateral ligaments, radial head, and coronoid.

Explanation

The radiographs show fractures of the coronoid and radial head. The medial collateral ligament has been avulsed from the ulnar insertion, and there is a valgus opening on the medial side. The lateral collateral ligament is always disrupted in elbow dislocations and fracture-dislocations that occur secondary to falls. This is known as the terrible triad injury (dislocation and fractures of the coronoid and radial head); it has a very poor prognosis because of its propensity for recurrent or persistent instability and late arthritis. The principle in treating this injury is to repair all of the injured parts or protect them with a hinged external fixator until they heal. Norris TR (ed): Orthopaedic Knowledge Update: Shoulder and Elbow. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 345-354. Kasser JR (ed): Orthopaedic Knowledge Update 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 283-294.

Question 1680

Topic: 9. Shoulder and Elbow

A 30-year-old right hand-dominant woman is seen in the trauma unit after a high-speed motor vehicle accident. She sustained a right shoulder anterior dislocation that is gently reduced under sedation. A CT scan is shown in Figure 3. If left untreated, the patient is at greatest risk for

Upper Extremity 2008 Practice Questions: Set 1 (Solved) - Figure 8

. axillary neuropathy.
. recurrent instability.
. shoulder girdle weakness.
. luxatio erecta.
. biceps tendinitis.

Correct Answer & Explanation

. recurrent instability.

Explanation

Large, displaced anterior inferior glenoid rim fractures predispose patients to recurrent anterior instability due to loss of the normal concavity compression effect of the glenoid. These defects require open reduction and internal fixation to reestablish shoulder stability. Although intra-articular fractures may lead to arthrosis, recurrent instability is more common. Robinson CM, Kelly M, Wakefield AE: Redislocation of the shoulder during the first six weeks after a primary anterior dislocation: Risk factors and results of treatment. J Bone Joint Surg Am 2002;84:1552-1559.

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