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Musculoskeletal Imaging |
1 From the Departments of Radiology (A.K., G.B., M.F.S., P.S., W.J., D.z.N.) and Traumatology (M.G.), University Hospital Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria; and the Department of Radiology, Division of Diagnostic Ultrasound (F.F., E.J.H.), Thomas Jefferson University, Philadelphia, Pa. Received April 8, 2001; revision requested May 11; revision received July 30; accepted September 14. Address correspondence to A.K. (e-mail: andrea.klauser@uibk.ac.at).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Sixty-four extreme rock climbers (climbing levels 8–11 on a scale ranging from 1 to 11; Union Internationale des Associations d’Alpinisme) with finger injuries (75 symptomatic and 181 asymptomatic fingers) were examined by using US, with the transducer operating at 12 MHz. The distance between the flexor tendon and phalanx was evaluated in extension and forced flexion at the level of the A2 and A4 annular pulleys as an indicator of tendon bowstringing. A distance between the flexor tendon and phalanx greater than 1.0 mm was interpreted as positive for a pulley injury. US findings were compared with those of magnetic resonance imaging. Surgical correlation was available in seven cases. Statistical analysis was performed by using analysis of variance, the Student t test, and the Bonferroni method.
RESULTS: US depicted 16 (100%) of 16 complete A2 pulley ruptures, nine (100%) of nine complete A4 pulley ruptures, six (86%) of seven surgically proved complete combined A2 and A3 pulley ruptures, and 15 (100%) of 15 incomplete A2 pulley ruptures. Measurement of distance between the flexor tendon and phalanx was significantly different among patient subsets without pulley ruptures and those with incomplete, complete, or complete combined pulley ruptures (P < .001). The sensitivity of US for depiction of finger pulley injuries was 98%, and specificity was 100%.
CONCLUSION: Dynamic US allows excellent depiction of finger pulley injuries in extreme rock climbers.
Index terms: Fingers and toes, injuries, 43.489 • Hand, injuries, 43.489 • Hand, US, 43.1298
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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A survey of injuries in 46 climbers (3) indicated that overuse injuries are more common than acute injuries due to falls. Overuse injuries may be due to a climbing technique in which the entire body weight is placed on only one or two finger holds with the hand in a crimp grip (2,4). This technique results in high forces in the proximal interphalangeal (PIP) joint and the digital pulley system. The pulley system refers to a number of ligaments including annular pulleys (A1–A5) and cruciform pulleys (C1–C3) that span from side to side across the volar margin of the finger phalanges. The A2 and A4 annular pulleys, located at the proximal third of the proximal phalanx and intermediate phalanx, respectively, are the broader and the most functionally important annular pulleys (5). The major function of the pulleys is to stabilize the flexor tendons during finger flexion, therefore, avoiding a radial displacement or volar bowstringing. Displacement of the tendons lowers their mechanical efficiency and reduces digital performance (6).
During climbing, the pulley system is exposed to high grip-specific loads of up to 700 N (7). Pulley ruptures related to climbing are most commonly seen in the ring and middle fingers and are diagnosed in up to 30% of finger injuries (8). Early diagnosis of pulley ruptures is mandatory to prevent fixed contractures of the PIP joint (4).
Clinical examination is the primary diagnostic procedure for differentiation between overuse syndrome and traumatic injuries such as pulley rupture. Clinical examination is limited by pain and soft-tissue swelling, especially, in the acute phase. However, an exact diagnosis is essential for therapeutic management (9–11).
In a recent study on cadaveric fingers, Hauger et al (12) reported that ultrasonography (US) can provide for direct evaluation of the finger pulley system. The purpose of this study was to determine the ability of dynamic US to depict finger pulley injuries in extreme rock climbers.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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US Technique
US was performed by using a unit (Sonoline Elegra; Siemens, Issaquah, Wash) fitted with a multi-D linear array transducer (VFX 13-5; Siemens) operating at a frequency of 12 MHz. A gel standoff pad (Sonar Aid; Geistlich Pharma, Wolhusen, Switzerland) was used in all examinations. Each examination was documented on videotape and hard-copy printout.
US of the hand, in the supine position, was performed from the heads of the metacarpals to the distal phalanges in both transverse and longitudinal planes. Based on the study of Martinoli et al (6), who reported that transverse sonograms did not add significant information in the evaluation of finger pulley injuries, we measured the distance between the flexor tendon and phalanx (hereafter, TP distance) in only the longitudinal plane. US measurement was performed on the extended fingers in the resting position, followed by examination during active forced flexion (approximately 10° in the distal interphalangeal joint and 40° in the PIP, with extension of the metacarpophalangeal joint, pressing the fingertips against the resistance of the radiologist’s finger (Fig 1).
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In addition to the TP distance, the gliding ability of the flexor digitorum superficialis, profundus tendons, and tendon sheaths during active and passive motion were visualized. Homogeneous gliding ability was defined subjectively as "smooth gliding" of the flexor tendons. Furthermore, the regions of the tendon and the PIP and distal interphalangeal joints were evaluated for inflammatory (ie, tenosynovitis) or degenerative changes, such as tendon sheath cysts, fibrous tissue, and increased amount of intraarticular fluid collections. At US, fibrous tissue was defined by its slightly hypoechoic heterogeneous appearance (13,14).
In this study we investigated the third and fourth fingers of both hands in 64 patients, for a total of 256 fingers. We evaluated dynamic US for the detection of nonpulley rupture and incomplete, complete, and complete combined (defined as a complete A2 and A3 pulley rupture) pulley rupture. The US examination was jointly performed and interpreted in consensus by two radiologists (A.K., G.B.), who were blinded to the findings at the clinical examination.
MR Imaging
MR imaging, used as the standard, was performed by using a 1.5 T unit (Vision; Siemens, Erlangen, Germany). We studied the third or fourth finger at MR imaging in 75 symptomatic fingers. The hand was first positioned prone with the fingers in an extended position and then positioned prone with the injured finger in a flexed position (10° at the distal interphalangeal joint and 40° at the PIP joint). The imaging protocol consisted of T1-weighted spin-echo and T2-weighted fast spin-echo sequences (528/20 [repetition time msec/echo time msec] and 2,000/86, respectively), short inversion time inversion-recovery (or STIR) sequences (3300/30; inversion time, 150 msec) performed in the sagittal plane, and intermediate proton density T2-weighted fast spin-echo sequences (2,000/20–86) performed in the transverse plane. A dedicated phased-array wrist coil was used. Two averages were obtained. Section thickness was 2 mm, with a 0.2-mm gap intersection. The field of view was 16 cm. To obtain images with forced flexion, the climbers were asked to press their fingertips on the surface of the tuft (special device used to fit fingers in a flexed position) during the course of imaging. To reduce patient motion, we taped the finger to the adjacent finger and the tuft.
The MR imaging criteria for complete and incomplete pulley ruptures, as described in the study of Gabl et al (9), are based on the anatomy of the pulley system. Bowstringing extending from the PIP joint to the base of the proximal phalanx, as depicted on sagittal MR images, indicates complete rupture of the A2 pulley. Bowstringing extending from the PIP joint but not reaching the base of the proximal phalanx indicates incomplete rupture of the A2 pulley. Bowstringing extending from the base of the proximal phalanx into the area distal to the PIP joint indicates complete combined A2 and A3 pulley rupture. Bowstringing extending from the base to the middle part of the intermediate phalanx indicates complete A4 pulley rupture. An additional sign for pulley lesions included the visualization of underlying fluid in the area of the affected pulley. Furthermore, regions of the tendon and PIP and distal interphalangeal joints were evaluated for inflammatory or degenerative changes such as cysts, fibrous tissue, and fluid collections. Fibrous tissue was defined by its low signal intensity on T2-weighted images (15). MR images were interpreted by a third radiologist (M.F.S.), who was blinded to the US findings.
Surgery
Seven patients with complete combined A2 and A3 pulley ruptures underwent surgery. In all patients, the pulleys were reconstructed by means of a tendon graft from the long palmaris muscle by using the Kleinert technique (9).
Statistical Analysis
Each finger was classified into one of the following four categories according to MR imaging findings: nonpulley rupture, incomplete pulley rupture, complete pulley rupture, or complete combined A2 and A3 pulley rupture. The data obtained at US were compared with those obtained at MR imaging in terms of the detection of finger pulley injuries. Sensitivity, specificity, and accuracy, as well as positive and negative predictive values, were determined for the US depiction of pulley injuries. Furthermore, US and MR imaging findings were compared with surgical findings in seven subjects.
To determine a significant change in TP distance with the various forms of finger pulley injuries, analysis of variance was performed by using statistical software (StatView, version 4.02; Abacus Concepts, Berkeley, Calif). By using the F test, a P value of less than .05 was considered to indicate a statistically significant difference.
Once an overall significant change in TP distance was demonstrated with analysis of variance, the Student t test was used to assess differences among the various subgroups of finger pulley injury. Since this analysis involved five comparisons among the subgroups, the adjusted P value cutoff was set at .01 by using the Bonferroni method (16).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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US evaluation was adequate for all 256 fingers in the 64 extreme rock climbers. Compared with the MR imaging and surgical findings, which served as the reference standard, US demonstrated an accuracy of 99%, a sensitivity of 98%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 97% for the detection of finger pulley injuries (Table 1).
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In the 181 asymptomatic fingers, we found a A2 TP distance of 0.3 mm (± 0.3) and A4 TP distance of 0.2 mm (± 0.2) at rest. During forced flexion, no statistically significant increases in TP distance (A2, 0.4 mm ± 0.3 and A4, 0.3 mm ± 0.3) were depicted in these fingers (P > .05).
Additional US findings in the 75 symptomatic fingers are summarized in Table 3. Fluid collection in a joint capsule at the area of the PIP joint is demonstrated in Figure 5. Fibrous tissue (ie, chronic, degenerative changes) between the phalanx and the flexor tendon was observed in symptomatic and asymptomatic climbers. Both groups demonstrated homogeneous gliding abilities of the flexor digitorum superficialis and profundus tendons.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Limited clinical examination, due to pain, soft-tissue swelling, and restricted range of motion, may create difficulty in obtaining the diagnosis of a pulley rupture (10,11). In the study by Marco et al (18), isolated rupture of the A2 pulley, with minor bowstringing, did not result in clinically detectable bowstringing. Obvious clinical bowstringing occurred only after complete rupture of A2, A3, and A4 pulleys. By using US we were able to correctly detect 46 (98%) of 47 finger pulley injuries. Therefore, US has been shown to be superior to the clinical examination. Martinoli et al (6) reported in a small group of patients (n = 16) that US can demonstrate finger pulley ruptures. They reported one case with US findings suggestive of an incomplete pulley rupture without tendon bowstringing. However, this disagreement, compared with our results, may be based on the limitation that they investigated only one case and, furthermore, that they did not report values for the anterior tendon displacement. We measured TP distance during dynamic US for detection of finger pulley injuries. An increasing TP distance with active forced flexion against resistance was significantly correlated with pulley injuries (P < .001). Even though there is some overlap between the measurements of TP distance obtained in fingers with incomplete and complete rupture, the TP distance is significantly greater with complete rupture as compared with incomplete rupture of the pulley, as shown in Table 2.
Significant differences in TP distance at rest were found in all groups except between the group of complete A2 rupture and the group of complete combined A2 and A3 rupture (P = .38). The correct diagnosis of a complete combined A2 and A3 pulley rupture is important for clinical management. Since A2 and A3 pulley injuries cannot be differentiated from A2 pulley ruptures at rest, we recommend TP distance measurement with forced flexion. As shown in the current study, dynamic US used to measure the TP distance demonstrated a sensitivity of 98% and a specificity of 100% for the detection of finger pulley injuries. MR imaging, the reference standard in this study, was proved to be accurate in detecting pulley system abnormalities in a human cadaver study by Hauger et al (12) and in a human study by Martinoli et al (6). Our US findings demonstrate excellent agreement with our MR imaging findings and with the findings presented by Hauger et al (12). We suggest that a value of 1.0 mm should be considered as the upper limit for a TP distance with forced flexion when differentiating a normal pulley from a ruptured pulley.
We detected at US six of seven complete combined A2 and A3 pulley ruptures. This dedicated diagnosis of isolated or combined pulley rupture is essential because complete combined A2 and A3 pulley ruptures should be treated by using operative pulley reconstruction (9). However, we misdiagnosed one complete combined A2 and A3 rupture (this was the first case) as an isolated complete A2 pulley rupture. Retrospectively, this false-negative finding may have resulted from a restricted dynamic US examination. In our experience, maximal active forced flexion during the dynamic US examination is the most important factor for assessment of TP distance and detection of finger pulley injuries.
US proved to be superior to the clinical examination in that US depicted 75 fingers suspicious for pulley injuries. Forty-seven (63%) of these digits proved to have pulley injuries. In the remaining 28 cases, tenosynovitis was the most common reason for clinical symptoms. Early diagnosis is important, because many climbing-induced injuries are related to repetitive use of holds and because many climbers are unwilling to rest adequately (3). In chronic cases, scar tissues forming can cause limited PIP joint extension. Le Viet et al (8) found fibrous tissue interposed between the phalanx and the flexor tendons. US also allows for the detection of fibrous tissue underneath the tendon, which was found in 42 (16%) of all 256 fingers. By enabling early accurate diagnosis of pulley injuries, US should be helpful for selecting appropriate therapeutic interventions. Patients with complete combined A2 and A3 pulley ruptures undergo surgery, whereas complete A2 pulley ruptures are primarily treated without surgery (9). High sensitivity in the detection of finger pulley injuries is important for therapeutic management. Underdiagnosis of a complete pulley rupture can result in restricted range of motion of the finger. Our results suggest that the sensitivity of US for this diagnosis is close to 100%.
Other authors have used MR imaging (19–22) and CT (8) in the evaluation of finger pulley injuries and have used anterior displacement of the flexor tendon in detecting annular pulley rupture. However, our experience suggests that MR imaging is more time-consuming, as compared with US. Motion artifacts due to long examination time present a further limitation (9). However, these artifacts can be avoided by gently taping the affected finger with the finger adjacent to the tuft. Neither MR imaging nor CT enables a real-time evaluation, and both modalities are more costly and less universally available compared with US. The exponential increase in climbing enthusiasts described in the study by Rooks et al (1) requires a widely available and economical imaging modality for the evaluation of finger injuries in climbers.
A limitation of this study is the fact that all examinations were jointly performed and interpreted by two radiologists, as it does not provide data on intraobserver and/or interobserver variability. Furthermore, we performed only MR imaging in the 75 symptomatic fingers because of limited availability of the MR unit. Therefore, we do not have MR imaging correlation for US findings in the asymptomatic fingers. The evaluation of the gliding ability during active and passive movement of the fingers showed no difference in gliding ability in asymptomatic and symptomatic fingers. In a previous study (23), we investigated healthy subjects to evaluate the gliding ability, and our results were similar to the findings of Martinoli et al (6), who described a normal gliding ability as a "smooth gliding" of the flexor tendons, which we defined as a "normal homogenous gliding ability." Yet, these are subjective findings, and the interpretation might be difficult. To the best of our knowledge there is no study in which findings of objective parameters for evaluating the gliding ability in flexor tendons have been reported.
US has proved to be an attractive approach for direct visualization of injuries to the joints, tendons, and soft tissues of the hand (23–25). It is a noninvasive easily performed diagnostic study with no ionizing radiation. US permits the real-time demonstration of finger anatomy and correlation with focal tenderness, which can be discussed with the climber (23). The interactive nature of the examination may improve acceptance of therapeutic strategies, although it is difficult to persuade injured climbers to rest until their injuries completely heal (3). In conclusion, dynamic US provides excellent depiction of finger pulley injuries. Particularly in cases of acute injuries, in which clinical evaluation can be difficult, US allows accurate measurement of anterior tendon displacement. Measurement of the distance between the flexor tendon and phalanx during dynamic US examination with active forced flexion is an excellent marker for the evaluation of finger pulley injuries. We suggest that dynamic US should be routinely performed in extreme rock climbers with any suspicion of finger pulley injury, because exact diagnosis is important for deciding adequate therapeutic strategies.
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, A.K., M.G.; study concepts, A.K., F.F., G.B.; study design, A.K., M.F.S., F.F.; literature research, A.K.; clinical studies, A.K., G.B.; data acquisition, F.F.; data analysis/interpretation, E.J.H., W.J.; statistical analysis, E.J.H.; manuscript preparation, A.K., F.F., E.J.H.; manuscript definition of intellectual content, A.K., F.F., G.B.; manuscript editing, M.F.S., M.G.; manuscript revision/review, A.K., F.F., E.J.H., P.S., D.z.N., M.F.S.; manuscript final version approval, A.K., F.F., G.B., P.S.
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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