- Email: [email protected]
Ultrasound evaluation of flexor tendon lacerations
Original Communications Ultrasound Evaluation of Flexor Tendon Lacerations Donald H. Lee, MD, Michelle L. Robbin, MD, Robert Galliott, MD, Veronica A. Graveman, RDMS, Birmingham, AL Thirteen injured digits in 10 patients (10 hands) with 20 potentially injured flexor tendons were preoperatively evaluated using real-time ultrasonography. The time interval between injury and ultrasonographic evaluation averaged 22 days. If a complete tendon laceration was found, the location of the proximal tendon stump was determined. Surgery was performed an average of 4 days after the ultrasonographic evaluation to determine the accuracy of the ultrasound study. Ultrasonography accurately identified the status of the flexor tendon in 11 of 13 digits and in 18 of 20 flexor tendons (12 intact, 2 partial lacerations, and 6 complete tendon lacerations). With complete tendon lacerations the location of the proximal tendon stump was accurately identified in 5 of 6 digits. There were 2 false ultrasound findings, including incorrectly identifying a 75% laceration in an intact index flexor and a complete tendon laceration in a 75% lacerated index finger flexor. Ultrasonography can help to evaluate the preoperative status of injured flexor tendons and, in cases of completely lacerated tendons, can help identify the location of the proximal tendon stump. (J Hand Surg 2000; 25A:236 –241. Copyright © 2000 by the American Society for Surgery of the Hand.) Key words: Ultrasound, tendon lacerations, imaging studies.
The evaluation and management of a completely transected hand flexor tendon is relatively clear. A digit with a complete tendon laceration usually displays a loss of the normal partially flexed digital resting posture, a loss of active finger flexion, and an absent tenodesis effect. An equivocal physical examination of a potentially lacerated tendon may be due to pain, limited patient effort (eg, child), or other
From the Division of Orthopedic Surgery and the Department of Radiology, University of Alabama at Birmingham, Birmingham, AL. Received for publication January 27, 1999; accepted for publication October 22, 1999. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Donald H. Lee, MD, Division of Orthopedic Surgery, 505 MEB, 1813 Sixth Ave S, University of Alabama at Birmingham, Birmingham, AL 35294. Copyright © 2000 by the American Society for Surgery of the Hand 0363-5023/00/25A02-0004$3.00/0
236 The Journal of Hand Surgery
associated injuries (eg, fractures, gunshot wounds, foreign bodies). Partial tendon lacerations can occur with penetrating injuries. In contrast to completely lacerated tendons, partial tendon lacerations may be difficult to detect. In patients with neurovascular compromise or displaced fractures, surgical exploration and repair of injured structures are usually warranted. If unknown, the status of the flexor tendon can then be determined. Surgical exploration to determine the status of a functioning flexor tendon without an associated injury is not ideal. Accurate imaging studies that can determine the preoperative status of a potentially lacerated tendon may preclude the need for surgery. Additionally, although less importantly, preoperative localization of a completely lacerated proximal tendon stump may be helpful in planning the surgical incision. Ultrasonography is a relatively inexpensive, noninvasive imaging method that allows real-time imag-
The Journal of Hand Surgery / Vol. 25A No. 2 March 2000 237
Table 1. Patient Demographics Patient No.
Age (y)
Injured Hand
Digit
1 2 3 4 5 6 7 8 9 10
17 25 29 48 42 46 23 46 22 36
R R R L L R R L L L
Thumb Index, long, ring Thumb Thumb Index (palm) Long, ring (palm) Thumb Index Index Index
ing of tendons. The purpose of this prospective study was to prospectively determine whether flexor tendon ultrasonography could accurately evaluate the status of a potentially lacerated or lacerated flexor tendon. In digits with complete tendon lacerations, could ultrasonography accurately locate the position of the proximal tendon stump?
Materials and Methods Thirteen injured digits in 10 hands in 10 patients (8 males and 2 females) were preoperatively evaluated using real-time ultrasonography (Table 1). The right and left hands were equally involved (5 hands each). The injured digits included the thumb (4 digits), index finger (5), long finger (2), and ring finger (2). The mechanism of injury was due to a sharp laceration in all but one (gunshot injury) digit. All open wounds, except the gunshot injury, had a simple wound closure without exploration of the wound. Clinically, complete flexor tendon lacerations was suspected in 6 digits. Flexor tendon function was present in the remaining digits. In addition, all digits had an associated neurologic deficit (except patient 1, who had a metacarpal fracture) requiring exploration and repair of the injured structure. No patient presented with the triggering that might be anticipated with a partial tendon laceration. An Advanced Technology Laboratories Ultramark 9 ultrasound scanner (Bothell, WA), with a 38-mm L10-5 MHz linear transducer was used to evaluate patients before surgery. A 9 cm ⫻ 2 cm round Aquaflex ultrasound gel pad (Parker Laboratories, Orange, NJ) was used during the examination if needed. The flexor tendons were identified and visualized by combining real-time ultrasonography with active and/or passive digital motion. The tendon was examined in both the sagittal and
Mechanism of Injury Gunshot Knife Knife Saw blade Knife Knife Can Band saw Knife Barbecue grill
Time to Scan (d)
Time to Surgery (d)
11 10 4 2 2 7 168 0 4 12
0 6 3 5 10 2 6 3 1 4
transverse planes. Examination in the sagittal plane was, in general, the most useful. The ultrasound gel pad, placed over the volar digit or palm, was used to match the distance between the tendon and the ultrasound transducer to the transducer’s optimal focal zone, thereby enhancing the sonographic resolution. Differential motion of the flexor digitorum profundus (FDP) and flexor digitorum sublimis (FDS) was achieved by having the patient actively flex, if possible, the distal and proximal interphalangeal joint, respectively. The flexor pollicis longus (FPL) was examined by actively flexing the thumb interphalangeal joint. If active motion was absent, passive mobilization of the joint was performed. Real-time video recordings were made during each study with still spot views taken of the injured area. The diagnosis of a complete laceration of a flexor tendon was made when complete disruption in the normal longitudinal fibrillar architecture of the tendon was noted. The lack of proximal tendon motion with passive digital motion also helped confirm a complete tendon laceration. With partial tendon lacerations, a hypoechoic area, usually linear in configuration and oriented perpendicular to the long axis of the tendon, was seen extending through the normal fibrillar tendon architecture. The degree of a partial tendon laceration (in quartiles; eg, 0% to 25%) was graded based on the thickness of the tendon in an area devoid of injury. All evaluations were performed by the same radiologist. All patients were examined to determine the status of the flexor tendon in the injured digit, ie, intact, partial, or complete tendon laceration. In digits with a suspected complete tendon laceration, an attempt was made to determine the location of the proximal tendon stump. Based on the location of the laceration or open wound, the FDP was potentially
238 Lee et al / Ultrasound Evaluation of Flexor Tendon Injuries
Figure 1. An ultrasonographic view of an intact flexor tendon. Note the horizontal striations of the flexor tendons (T). With real-time ultrasonography, movement of the flexor tendon can be seen. The proximal phalanx (P) and metacarpal (M) are located beneath the flexor tendons (T).
lacerated in 9 fingers, the FDS in 7 fingers, and the FPL in 4 thumbs. Therefore, 20 potentially lacerated tendons were evaluated. A surgical exploration was subsequently performed on all patients and the accuracy of the ultrasonographic studies was determined. The time interval between injury and the ultrasound study averaged 22 days (range, 0 –5 months). With exclusion of the single patient evaluated at 5 months after injury (patient 7), the average time between injury and the ultrasound study, in the remaining 9 patients, was 6 days (range, 0 –12 days). The average time between the ultrasound study and surgical exploration was 4 days (range, 0 –10 days). A single surgeon who was blinded to the results of the ultrasound study performed all the surgical procedures. The surgeon noted the status of the flexor tendon, ie, intact tendon (Fig. 1), partial tendon laceration, or complete tendon laceration. With complete tendon lacerations the location of the proximal tendon stump was noted (Fig. 2). The results of the ultrasound study and surgery were compared.
Results Ultrasonography was accurate in determining the status of the flexor tendon in 11 of 13 digits and in 18 of 20 potentially injured flexor tendons (12 intact, 2 partial tendon lacerations, and 6 complete tendon lacerations; Table 2).
Thumb In the 4 thumb injuries, ultrasonography accurately identified a completely lacerated FPL in 3 thumbs and an intact FPL in 1.
Index Finger In the 5 index finger injuries, ultrasonography accurately identified 2 intact FDS, 2 intact FDP, 1 completely lacerated FDS, and 1 completely lacerated FDP. Ultrasonography incorrectly identified 1 intact FDP tendon as being partially (75%) lacerated (patient 8) and 1 partially (75%) lacerated FDP tendon as being completely lacerated (patient 10). One
The Journal of Hand Surgery / Vol. 25A No. 2 March 2000 239
Figure 2. An ultrasonographic view of a completely transected FDP. The proximal tendon stump (T), metacarpal (M), and proximal phalanx (P) are identified.
50% lacerated FDS tendon was correctly identified (patient 10).
patient (no. 6) with a palmar laceration, ultrasonography did not identify the proximal tendon stump, which was located at the wrist level.
Long Finger In the 2 long finger injuries, ultrasonography accurately identified an intact FDS and a completely lacerated FDP in 1 digit and an intact FDP and a completely lacerated FDS in the second digit.
Ring Finger In the 2 ring fingers injuries, ultrasonography accurately identified an intact FDS and an intact FDP in both digits.
Intact Tendons Ultrasonography identified 11 of 12 intact tendons. One intact tendon was incorrectly identified as being 75% lacerated (patient 8).
Complete Tendon Lacerations Ultrasonography identified all 6 completely lacerated tendons as would be expected from the clinical examination. Ultrasonography identified the location of the proximal tendon stump in 5 of the 6 digits with a complete laceration of the flexor tendon. In 1
Partial Tendon Lacerations In 1 digit (patient 10) with 2 partial tendon lacerations, ultrasonography correctly identified the tendon status of the FDS (50% laceration) and incorrectly identified a 75% lacerated FDP as being completely lacerated.
False Ultrasound Findings There were 2 cases of false-positive ultrasonographic results. Ultrasonography incorrectly identified a 75% laceration in an intact index FDP (patient 8) and a complete FDP laceration in a 75% lacerated FDP index finger (patient 10). Ultrasonography correctly identified a partial (50% or ulnar slip laceration) FDS laceration in the same digit. No lacerated tendons were missed by ultrasonographic examination.
Discussion There are several potential uses of ultrasonography in examining the hand, including evaluating flexor
240 Lee et al / Ultrasound Evaluation of Flexor Tendon Injuries
Table 2. Results of Surgical Findings and Ultrasound Studies Patient No. 1
2 3 4 5 6 7 8 9 10 Total
Surgical Findings Intact FPL Intact index FDS, FDP Intact ring FDS, FDP Intact long FDS Cut long FDP Cut FPL Cut FPL Intact index FDS, FDP Cut long FDS Intact long FDP Intact ring FDP, FDS Cut FPL Intact index FDP Cut index FDP Cut index ulnar slip FDS Cut (75%) index FDP
Ultrasound Accurate?
Identify Proximal End of Tendon?
Yes ⫻ 1
Other Injured Structures Metacarpal fracture
Yes ⫻ 6 Yes ⫻ 1 Yes ⫻ 1 Yes ⫻ 2
Yes Yes Yes
Index ulnar digital nerve Partial radial digital nerve, ulnar digital nerve Radial and ulnar digital nerves Ulnar digital nerve
Yes ⫻ 4 Yes ⫻ 1 No ⫻ 1 Yes ⫻ 1 Yes ⫻ 1 No ⫻ 1 18 of 20
No Yes
Common digital nerve Ulnar digital nerve Radial digital nerve Radial digital nerve Ulnar digital nerve
and extensor tendon lacerations and avulsion injuries. Ultrasound can also evaluate the status of repaired tendons, ligament injuries, masses, and fluid collections (eg, ganglions, abscesses) and detect foreign bodies.1,2 To date, the experience in evaluating flexor tendon injuries with ultrasonography is limited. Corduff et al3 used ultrasonography to evaluate repaired flexor tendons. These investigators found that ultrasound could detect tendons bound down in scar, tendon gap formation following tendon repair, and late secondary tendon ruptures. They proposed a new method of grading the results of tendon repairs based on ultrasonographic findings. Serafini et al4 used ultrasonography to evaluate the pathologic changes in the flexor tendons of patients with trigger fingers. These changes included synovial sheath thickening, irregular internal tendon echotexture, and synovial cysts. Ultrasonography also has been used to evaluate the Achilles tendon, rotator cuff tendons, quadriceps tendon, biceps tendon, and plantaris tendons.5–10 The results of this small prospective study show that ultrasonography may be useful in the preoperative evaluation of flexor tendon injuries. Ultrasonography appears to be accurate in determining the status of intact and completely lacerated tendons. Ultrasound was able to accurately identify 11 of 12 intact tendons. The location of the proximal tendon stump in completely lacerated tendons can be determined before surgery (accurate in 5 of 6 completely
Yes
5 of 6
lacerated tendons). This information may be useful to the surgeon in planning surgical incisions, particularly when the proximal tendon stump cannot be palpated. The location of the proximal tendon stump was not accurately identified in 1 patient with a palmar laceration (patient 6). The proximal tendon stump in this patient was located at the wrist level. Detection of a tendon stump at this level is difficult due to the aggregation of tendons in the carpal canal and distal forearm. One of the more useful prospects of ultrasonography may be in evaluating partial tendon injuries. There is no consensus, however, regarding whether partially transected tendons should be repaired, resected, or left alone. The potential complications of partial tendon lacerations include triggering, rupture, and entrapment. Most surgeons probably would repair or bevel a triggering partially lacerated flexor tendon. Some surgeons also would repair a laceration involving more than 50% to 60% of the tendon.11 Would the surgeon, however, explore a laceration for only a suspected partial tendon laceration? It would be ideal if the degree of a partial tendon laceration could be determined without surgery. Because there were only 2 partially lacerated tendons in this study, we are unable to conclude that ultrasonography can accurately determine the status of partially transected tendons. Ultrasonography did correctly identify 1 partially (50%) lacerated tendon and incorrectly identified another partially (75%) lacerated FDP as being completely lacerated. Ultrasonography can ad-
The Journal of Hand Surgery / Vol. 25A No. 2 March 2000 241
equately evaluate the longitudinal fibrillar tendon architecture if the ultrasound beam is oriented perpendicularly to the tendon. If, however, the beam is oriented obliquely to the tendon, inadequate reflection of the beam may produce a hypoechoic area. This area may be confused with a tendon laceration. The tendon therefore must be viewed from multiple angles to avoid this pitfall. Ultrasonography correctly identified 11 of 12 intact tendons but incorrectly identified 1 intact tendon as being 75% lacerated. In this patient the finger was evaluated on the day of injury. Air artifact from a newly closed wound and a lack of active motion secondary to pain may have caused the false finding. There were no false negative findings. The major advantage of ultrasonography lies in its ability to provide real-time dynamic images of a moving flexor tendon, unlike the static images provided by magnetic resonance imaging and computed tomography. Additionally, it is relatively inexpensive, noninvasive, and widely available. The disadvantages of ultrasonography include its high operator dependence, relatively poor image quality, and difficulty for the clinician in evaluating the images. Before this clinical study the radiologist and surgeon evaluated several cadaver hands. To adequately evaluate the status of flexor tendons, the radiologist must be familiar with normal hand anatomy. At the time of the study a 38-mm L10-5 MHz linear transducer was used. A newer compact linear (CL 10-5) scan head (Advanced Technology Laboratories) is now available. Either scan head appears to provide adequate visualization of the tendons. In addition, newer ultrasound scanners are also available that may provide even greater ultrasonographic resolution. The purpose of this study was to determine whether ultrasonography could determine the status preoperative of the flexor tendons. Since all patients in this study had an additional injury (nerve injury or fracture) warranting surgical exploration, ultrasonography did not effect the ultimate decision for surgery. We are encouraged, however, by the ability of ultrasonography to evaluate flexor tendon injuries. It may
be a reasonable option in evaluating patients when the clinical examination may be difficult, such as in children and in cases of possible partial tendon lacerations. Ultrasonography may be a viable diagnostic tool in preoperatively evaluating flexor tendon injuries. It can, with reasonable accuracy, assess the status of potentially injured flexor tendons. In the case of completely lacerated tendons, ultrasonography can help identify the location of the proximal tendon stump.
References 1. Kaplan PA, Anderson JC, Norris MA, Matamoros A Jr. Ultrasonography of post-traumatic soft-tissue lesions. Radiol Clin North Am 1989;27:973–982. 2. Hoglund M, Tordai P, Engkvist O. Ultrasonography for the diagnosis of soft tissue conditions in the hand. Scand J Plast Reconstr Surg Hand Surg 1991;25:225–231. 3. Corduff N, Jones R, Ball J. The role of ultrasound in the management of zone 1 flexor tendon injuries. J Hand Surg 1994;19B:76 – 80. 4. Serafini G, Derchi LE, Quadri P, et al. High resolution sonography of the flexor tendons in trigger fingers. J Ultrasound Med 1996;16:213–219. 5. Bianchi S, Zwass A, Abdelwahab IF, Banderali A. Diagnosis of tears of the quadriceps tendon of the knee: value of sonography. AJR Am J Roentgenol 1994;162:1137– 1140. 6. Laine HR, Harjula A, Peltokallio P. Ultrasound in the evaluation of the knee and patellar regions. J Ultrasound Med 1987;6:33–36. 7. Lozano V, Alonso P. Sonographic detection of distal biceps tendon rupture. J Ultrasound Med 1995;14:389 –391. 8. Mack LA, Matsen FA III, Kilcoyne RF, Davies PK, Sickler ME. US evaluation of the rotator cuff. Radiology 1985; 157:205–209. 9. Martinoli C, Derchi LE, Pastorino C, Bertolotto M, Silvestri E. Analysis of echotexture of tendons with US. Radiology 1993;186:839 – 843. 10. Paavolainen P, Ahovuo J. Ultrasonography and arthrography in the diagnosis of tears of the rotator cuff. J Bone Joint Surg 1994;76A:335–340. 11. McCarthy DM, Boardman ND III, Tramaglini DM, Sotereanos DG, Herndon JH. Clinical management of partially lacerated digital flexor tendons: a survey of hand surgeons. J Hand Surg 1995;20A:273–275.
The evaluation and management of a completely transected hand flexor tendon is relatively clear. A digit with a complete tendon laceration usually displays a loss of the normal partially flexed digital resting posture, a loss of active finger flexion, and an absent tenodesis effect. An equivocal physical examination of a potentially lacerated tendon may be due to pain, limited patient effort (eg, child), or other
From the Division of Orthopedic Surgery and the Department of Radiology, University of Alabama at Birmingham, Birmingham, AL. Received for publication January 27, 1999; accepted for publication October 22, 1999. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Donald H. Lee, MD, Division of Orthopedic Surgery, 505 MEB, 1813 Sixth Ave S, University of Alabama at Birmingham, Birmingham, AL 35294. Copyright © 2000 by the American Society for Surgery of the Hand 0363-5023/00/25A02-0004$3.00/0
236 The Journal of Hand Surgery
associated injuries (eg, fractures, gunshot wounds, foreign bodies). Partial tendon lacerations can occur with penetrating injuries. In contrast to completely lacerated tendons, partial tendon lacerations may be difficult to detect. In patients with neurovascular compromise or displaced fractures, surgical exploration and repair of injured structures are usually warranted. If unknown, the status of the flexor tendon can then be determined. Surgical exploration to determine the status of a functioning flexor tendon without an associated injury is not ideal. Accurate imaging studies that can determine the preoperative status of a potentially lacerated tendon may preclude the need for surgery. Additionally, although less importantly, preoperative localization of a completely lacerated proximal tendon stump may be helpful in planning the surgical incision. Ultrasonography is a relatively inexpensive, noninvasive imaging method that allows real-time imag-
The Journal of Hand Surgery / Vol. 25A No. 2 March 2000 237
Table 1. Patient Demographics Patient No.
Age (y)
Injured Hand
Digit
1 2 3 4 5 6 7 8 9 10
17 25 29 48 42 46 23 46 22 36
R R R L L R R L L L
Thumb Index, long, ring Thumb Thumb Index (palm) Long, ring (palm) Thumb Index Index Index
ing of tendons. The purpose of this prospective study was to prospectively determine whether flexor tendon ultrasonography could accurately evaluate the status of a potentially lacerated or lacerated flexor tendon. In digits with complete tendon lacerations, could ultrasonography accurately locate the position of the proximal tendon stump?
Materials and Methods Thirteen injured digits in 10 hands in 10 patients (8 males and 2 females) were preoperatively evaluated using real-time ultrasonography (Table 1). The right and left hands were equally involved (5 hands each). The injured digits included the thumb (4 digits), index finger (5), long finger (2), and ring finger (2). The mechanism of injury was due to a sharp laceration in all but one (gunshot injury) digit. All open wounds, except the gunshot injury, had a simple wound closure without exploration of the wound. Clinically, complete flexor tendon lacerations was suspected in 6 digits. Flexor tendon function was present in the remaining digits. In addition, all digits had an associated neurologic deficit (except patient 1, who had a metacarpal fracture) requiring exploration and repair of the injured structure. No patient presented with the triggering that might be anticipated with a partial tendon laceration. An Advanced Technology Laboratories Ultramark 9 ultrasound scanner (Bothell, WA), with a 38-mm L10-5 MHz linear transducer was used to evaluate patients before surgery. A 9 cm ⫻ 2 cm round Aquaflex ultrasound gel pad (Parker Laboratories, Orange, NJ) was used during the examination if needed. The flexor tendons were identified and visualized by combining real-time ultrasonography with active and/or passive digital motion. The tendon was examined in both the sagittal and
Mechanism of Injury Gunshot Knife Knife Saw blade Knife Knife Can Band saw Knife Barbecue grill
Time to Scan (d)
Time to Surgery (d)
11 10 4 2 2 7 168 0 4 12
0 6 3 5 10 2 6 3 1 4
transverse planes. Examination in the sagittal plane was, in general, the most useful. The ultrasound gel pad, placed over the volar digit or palm, was used to match the distance between the tendon and the ultrasound transducer to the transducer’s optimal focal zone, thereby enhancing the sonographic resolution. Differential motion of the flexor digitorum profundus (FDP) and flexor digitorum sublimis (FDS) was achieved by having the patient actively flex, if possible, the distal and proximal interphalangeal joint, respectively. The flexor pollicis longus (FPL) was examined by actively flexing the thumb interphalangeal joint. If active motion was absent, passive mobilization of the joint was performed. Real-time video recordings were made during each study with still spot views taken of the injured area. The diagnosis of a complete laceration of a flexor tendon was made when complete disruption in the normal longitudinal fibrillar architecture of the tendon was noted. The lack of proximal tendon motion with passive digital motion also helped confirm a complete tendon laceration. With partial tendon lacerations, a hypoechoic area, usually linear in configuration and oriented perpendicular to the long axis of the tendon, was seen extending through the normal fibrillar tendon architecture. The degree of a partial tendon laceration (in quartiles; eg, 0% to 25%) was graded based on the thickness of the tendon in an area devoid of injury. All evaluations were performed by the same radiologist. All patients were examined to determine the status of the flexor tendon in the injured digit, ie, intact, partial, or complete tendon laceration. In digits with a suspected complete tendon laceration, an attempt was made to determine the location of the proximal tendon stump. Based on the location of the laceration or open wound, the FDP was potentially
238 Lee et al / Ultrasound Evaluation of Flexor Tendon Injuries
Figure 1. An ultrasonographic view of an intact flexor tendon. Note the horizontal striations of the flexor tendons (T). With real-time ultrasonography, movement of the flexor tendon can be seen. The proximal phalanx (P) and metacarpal (M) are located beneath the flexor tendons (T).
lacerated in 9 fingers, the FDS in 7 fingers, and the FPL in 4 thumbs. Therefore, 20 potentially lacerated tendons were evaluated. A surgical exploration was subsequently performed on all patients and the accuracy of the ultrasonographic studies was determined. The time interval between injury and the ultrasound study averaged 22 days (range, 0 –5 months). With exclusion of the single patient evaluated at 5 months after injury (patient 7), the average time between injury and the ultrasound study, in the remaining 9 patients, was 6 days (range, 0 –12 days). The average time between the ultrasound study and surgical exploration was 4 days (range, 0 –10 days). A single surgeon who was blinded to the results of the ultrasound study performed all the surgical procedures. The surgeon noted the status of the flexor tendon, ie, intact tendon (Fig. 1), partial tendon laceration, or complete tendon laceration. With complete tendon lacerations the location of the proximal tendon stump was noted (Fig. 2). The results of the ultrasound study and surgery were compared.
Results Ultrasonography was accurate in determining the status of the flexor tendon in 11 of 13 digits and in 18 of 20 potentially injured flexor tendons (12 intact, 2 partial tendon lacerations, and 6 complete tendon lacerations; Table 2).
Thumb In the 4 thumb injuries, ultrasonography accurately identified a completely lacerated FPL in 3 thumbs and an intact FPL in 1.
Index Finger In the 5 index finger injuries, ultrasonography accurately identified 2 intact FDS, 2 intact FDP, 1 completely lacerated FDS, and 1 completely lacerated FDP. Ultrasonography incorrectly identified 1 intact FDP tendon as being partially (75%) lacerated (patient 8) and 1 partially (75%) lacerated FDP tendon as being completely lacerated (patient 10). One
The Journal of Hand Surgery / Vol. 25A No. 2 March 2000 239
Figure 2. An ultrasonographic view of a completely transected FDP. The proximal tendon stump (T), metacarpal (M), and proximal phalanx (P) are identified.
50% lacerated FDS tendon was correctly identified (patient 10).
patient (no. 6) with a palmar laceration, ultrasonography did not identify the proximal tendon stump, which was located at the wrist level.
Long Finger In the 2 long finger injuries, ultrasonography accurately identified an intact FDS and a completely lacerated FDP in 1 digit and an intact FDP and a completely lacerated FDS in the second digit.
Ring Finger In the 2 ring fingers injuries, ultrasonography accurately identified an intact FDS and an intact FDP in both digits.
Intact Tendons Ultrasonography identified 11 of 12 intact tendons. One intact tendon was incorrectly identified as being 75% lacerated (patient 8).
Complete Tendon Lacerations Ultrasonography identified all 6 completely lacerated tendons as would be expected from the clinical examination. Ultrasonography identified the location of the proximal tendon stump in 5 of the 6 digits with a complete laceration of the flexor tendon. In 1
Partial Tendon Lacerations In 1 digit (patient 10) with 2 partial tendon lacerations, ultrasonography correctly identified the tendon status of the FDS (50% laceration) and incorrectly identified a 75% lacerated FDP as being completely lacerated.
False Ultrasound Findings There were 2 cases of false-positive ultrasonographic results. Ultrasonography incorrectly identified a 75% laceration in an intact index FDP (patient 8) and a complete FDP laceration in a 75% lacerated FDP index finger (patient 10). Ultrasonography correctly identified a partial (50% or ulnar slip laceration) FDS laceration in the same digit. No lacerated tendons were missed by ultrasonographic examination.
Discussion There are several potential uses of ultrasonography in examining the hand, including evaluating flexor
240 Lee et al / Ultrasound Evaluation of Flexor Tendon Injuries
Table 2. Results of Surgical Findings and Ultrasound Studies Patient No. 1
2 3 4 5 6 7 8 9 10 Total
Surgical Findings Intact FPL Intact index FDS, FDP Intact ring FDS, FDP Intact long FDS Cut long FDP Cut FPL Cut FPL Intact index FDS, FDP Cut long FDS Intact long FDP Intact ring FDP, FDS Cut FPL Intact index FDP Cut index FDP Cut index ulnar slip FDS Cut (75%) index FDP
Ultrasound Accurate?
Identify Proximal End of Tendon?
Yes ⫻ 1
Other Injured Structures Metacarpal fracture
Yes ⫻ 6 Yes ⫻ 1 Yes ⫻ 1 Yes ⫻ 2
Yes Yes Yes
Index ulnar digital nerve Partial radial digital nerve, ulnar digital nerve Radial and ulnar digital nerves Ulnar digital nerve
Yes ⫻ 4 Yes ⫻ 1 No ⫻ 1 Yes ⫻ 1 Yes ⫻ 1 No ⫻ 1 18 of 20
No Yes
Common digital nerve Ulnar digital nerve Radial digital nerve Radial digital nerve Ulnar digital nerve
and extensor tendon lacerations and avulsion injuries. Ultrasound can also evaluate the status of repaired tendons, ligament injuries, masses, and fluid collections (eg, ganglions, abscesses) and detect foreign bodies.1,2 To date, the experience in evaluating flexor tendon injuries with ultrasonography is limited. Corduff et al3 used ultrasonography to evaluate repaired flexor tendons. These investigators found that ultrasound could detect tendons bound down in scar, tendon gap formation following tendon repair, and late secondary tendon ruptures. They proposed a new method of grading the results of tendon repairs based on ultrasonographic findings. Serafini et al4 used ultrasonography to evaluate the pathologic changes in the flexor tendons of patients with trigger fingers. These changes included synovial sheath thickening, irregular internal tendon echotexture, and synovial cysts. Ultrasonography also has been used to evaluate the Achilles tendon, rotator cuff tendons, quadriceps tendon, biceps tendon, and plantaris tendons.5–10 The results of this small prospective study show that ultrasonography may be useful in the preoperative evaluation of flexor tendon injuries. Ultrasonography appears to be accurate in determining the status of intact and completely lacerated tendons. Ultrasound was able to accurately identify 11 of 12 intact tendons. The location of the proximal tendon stump in completely lacerated tendons can be determined before surgery (accurate in 5 of 6 completely
Yes
5 of 6
lacerated tendons). This information may be useful to the surgeon in planning surgical incisions, particularly when the proximal tendon stump cannot be palpated. The location of the proximal tendon stump was not accurately identified in 1 patient with a palmar laceration (patient 6). The proximal tendon stump in this patient was located at the wrist level. Detection of a tendon stump at this level is difficult due to the aggregation of tendons in the carpal canal and distal forearm. One of the more useful prospects of ultrasonography may be in evaluating partial tendon injuries. There is no consensus, however, regarding whether partially transected tendons should be repaired, resected, or left alone. The potential complications of partial tendon lacerations include triggering, rupture, and entrapment. Most surgeons probably would repair or bevel a triggering partially lacerated flexor tendon. Some surgeons also would repair a laceration involving more than 50% to 60% of the tendon.11 Would the surgeon, however, explore a laceration for only a suspected partial tendon laceration? It would be ideal if the degree of a partial tendon laceration could be determined without surgery. Because there were only 2 partially lacerated tendons in this study, we are unable to conclude that ultrasonography can accurately determine the status of partially transected tendons. Ultrasonography did correctly identify 1 partially (50%) lacerated tendon and incorrectly identified another partially (75%) lacerated FDP as being completely lacerated. Ultrasonography can ad-
The Journal of Hand Surgery / Vol. 25A No. 2 March 2000 241
equately evaluate the longitudinal fibrillar tendon architecture if the ultrasound beam is oriented perpendicularly to the tendon. If, however, the beam is oriented obliquely to the tendon, inadequate reflection of the beam may produce a hypoechoic area. This area may be confused with a tendon laceration. The tendon therefore must be viewed from multiple angles to avoid this pitfall. Ultrasonography correctly identified 11 of 12 intact tendons but incorrectly identified 1 intact tendon as being 75% lacerated. In this patient the finger was evaluated on the day of injury. Air artifact from a newly closed wound and a lack of active motion secondary to pain may have caused the false finding. There were no false negative findings. The major advantage of ultrasonography lies in its ability to provide real-time dynamic images of a moving flexor tendon, unlike the static images provided by magnetic resonance imaging and computed tomography. Additionally, it is relatively inexpensive, noninvasive, and widely available. The disadvantages of ultrasonography include its high operator dependence, relatively poor image quality, and difficulty for the clinician in evaluating the images. Before this clinical study the radiologist and surgeon evaluated several cadaver hands. To adequately evaluate the status of flexor tendons, the radiologist must be familiar with normal hand anatomy. At the time of the study a 38-mm L10-5 MHz linear transducer was used. A newer compact linear (CL 10-5) scan head (Advanced Technology Laboratories) is now available. Either scan head appears to provide adequate visualization of the tendons. In addition, newer ultrasound scanners are also available that may provide even greater ultrasonographic resolution. The purpose of this study was to determine whether ultrasonography could determine the status preoperative of the flexor tendons. Since all patients in this study had an additional injury (nerve injury or fracture) warranting surgical exploration, ultrasonography did not effect the ultimate decision for surgery. We are encouraged, however, by the ability of ultrasonography to evaluate flexor tendon injuries. It may
be a reasonable option in evaluating patients when the clinical examination may be difficult, such as in children and in cases of possible partial tendon lacerations. Ultrasonography may be a viable diagnostic tool in preoperatively evaluating flexor tendon injuries. It can, with reasonable accuracy, assess the status of potentially injured flexor tendons. In the case of completely lacerated tendons, ultrasonography can help identify the location of the proximal tendon stump.
References 1. Kaplan PA, Anderson JC, Norris MA, Matamoros A Jr. Ultrasonography of post-traumatic soft-tissue lesions. Radiol Clin North Am 1989;27:973–982. 2. Hoglund M, Tordai P, Engkvist O. Ultrasonography for the diagnosis of soft tissue conditions in the hand. Scand J Plast Reconstr Surg Hand Surg 1991;25:225–231. 3. Corduff N, Jones R, Ball J. The role of ultrasound in the management of zone 1 flexor tendon injuries. J Hand Surg 1994;19B:76 – 80. 4. Serafini G, Derchi LE, Quadri P, et al. High resolution sonography of the flexor tendons in trigger fingers. J Ultrasound Med 1996;16:213–219. 5. Bianchi S, Zwass A, Abdelwahab IF, Banderali A. Diagnosis of tears of the quadriceps tendon of the knee: value of sonography. AJR Am J Roentgenol 1994;162:1137– 1140. 6. Laine HR, Harjula A, Peltokallio P. Ultrasound in the evaluation of the knee and patellar regions. J Ultrasound Med 1987;6:33–36. 7. Lozano V, Alonso P. Sonographic detection of distal biceps tendon rupture. J Ultrasound Med 1995;14:389 –391. 8. Mack LA, Matsen FA III, Kilcoyne RF, Davies PK, Sickler ME. US evaluation of the rotator cuff. Radiology 1985; 157:205–209. 9. Martinoli C, Derchi LE, Pastorino C, Bertolotto M, Silvestri E. Analysis of echotexture of tendons with US. Radiology 1993;186:839 – 843. 10. Paavolainen P, Ahovuo J. Ultrasonography and arthrography in the diagnosis of tears of the rotator cuff. J Bone Joint Surg 1994;76A:335–340. 11. McCarthy DM, Boardman ND III, Tramaglini DM, Sotereanos DG, Herndon JH. Clinical management of partially lacerated digital flexor tendons: a survey of hand surgeons. J Hand Surg 1995;20A:273–275.