Original Article
The Journal of Hand Surgery (Asian-Pacific Volume) 2017;22(3):350-354 • DOI: 10.1142/S0218810417500411
Can Physical Examination Create a Stener Lesion? Manesha Lankachandra*, John P. Eggers*, James W. Bogener*, Richard L. Hutchison† *Department of Orthopaedic Surgery, University of Missouri, Kansas City, MO, USA Section of Hand Surgery, Children’s Mercy Hospitals and Clinics, Kansas City, MO, USA
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†
Background: The purpose of this study is to determine whether a Stener lesion can be created while testing stability of the ulnar collateral ligament (UCL) of the thumb. Testing was performed in a manner that reproduced clinical examination. Methods: Six fresh frozen hand and forearm specimens underwent sequential sectioning of the accessory UCL, the proper UCL, and the ulnar sagittal band. Measurements of radial deviation of the metacarpophalangeal (MCP) joint were taken with the thumb in neutral rotation, pronation and supination, both with 0 degrees and with 30 degrees of flexion of the MCP joint. Visual examination was performed to assess the presence of a Stener lesion. Results: No Stener lesion was created in any position as long as the fascial origin of the ulnar sagittal band at the adductor pollicis longus remained intact. After creating a defect in the ulnar sagittal band, a Stener lesion was created in two specimens, but only when the thumb was flexed and supinated. Pronation provided more stability, and supination provided less stability, with one or both components cut, especially when testing at 30° of flexion. Compared to both components cut without flexion or rotation, there was a statistically significant difference in angulation with the 30 degrees of MCP joint flexion in both neutral rotation in supination. Conclusions: Performing a physical examination to assess the amount of instability of an ulnar collateral ligament injury did not create a Stener lesion if the exam was performed in a controlled, gentle manner with the thumb held without rotation. If the thumb is held in neutral rotation during the exam, an iatrogenic Stener lesion should not be created. Keywords: Stener lesion, Ulnar collateral ligament of the thumb, Stress test, Physical examination
INTRODUCTION A Stener lesion can be the result of trauma to the ulnar collateral ligament (UCL) of the metacarpophalangeal (MCP) joint of the thumb, and can potentially be created during physical examination of an injured UCL. Physical examination routinely involves applying a valgus force to the MCP joint at 0° and 30° of flexion and measuring the amount of radial angulation. Multiple
Received: May. 19, 2016; Revised: Aug. 21, 2016; Accepted: Sep. 20, 2016 Correspondence to: Richard L. Hutchison Section of Hand Surgery, Children’s Mercy Hospitals and Clinics, 2401 Gillham Road Kansas City, MO 64108, USA Tel: +816-234-3693, Fax: +816-855-1993 E-mail: [email protected]
studies have evaluated the magnitude of angulation measured during physical examination that correlates with a complete rupture of the UCL. The conclusions vary, but angulation of 30–45°, or a 10–15° difference in laxity when compared to the contralateral uninjured side, generally suggests a complete tear of both components of the UCL.1-6) Treatment guidelines for thumb UCL injuries are based on the severity of injury. Partial tears of the proper UCL (pUCL) or the accessory UCL (aUCL), or complete tears with minimal displacement, can be treated effectively with immobilization. Complete tears respond more predictably to operative repair.1-5) Stener, in his original paper, described his eponymous lesion as complete rupture of the UCL and interposition of the adductor aponeurosis between the distally avulsed UCL and its
351
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footprint on the proximal phalanx, and these injuries are generally treated operatively.7) Since treatment is dependent on the severity of a tear and its displacement, there is a concern that clinical testing may increase the severity of injury, possibly converting a UCL disruption to a Stener lesion. Examination guidelines suggest positioning the thumb without rotation during exam. During exam, pronation or supination of the thumb may inadvertently occur. The purpose of this study was to discover if a Stener lesion could be created by clinical examination in a thumb with nondisplaced transection of the distal components of the ulnar collateral ligament. We hypothesized that a Stener lesion could be created during physical exam if testing was performed while the thumb was rotated into either pronation or supination, and that a Stener lesion would not be created by exam with maintenance of the thumb in neutral rotation.
METHODS Six thawed fresh-frozen hand and forearm specimens were used. Average age was 86 years, with three males and three females. All specimens were in satisfactory condition, and none had any apparent injury, arthritis, or other disease. Measurements of radial deviation of the MCP joint were taken with the thumb in neutral rotation, pronation and supination, both in 0° and in 30° of MCP flexion. Gentle pronation and supination force was achieved manually by one of the investigators. Measurements were obtained with one examiner stabilizing the metacarpal and proximal phalanx and then slowly and
gently applying the loads in a manner that reproduced clinical examination, while a second examiner used a hand-held goniometer to measure the degree of angulation at the MCP joint in the coronal and sagittal planes of the thumb. An example of the testing method is depicted in Fig. 1. Application of the gentle force was stopped when a firm endpoint was felt. Three measurements were made and then averaged for each combination of joint position. The pUCL and the aUCL were serially sectioned at their distal insertions on the proximal phalanx, mimicking the most common site of clinical rupture. Radial deviation measurements were repeated. The adductor aponeurosis complex and the ulnar sagittal band were initially left intact, and visual examination was performed to assess the presence of a Stener lesion. After measurements were obtained with both UCL components sectioned, a sharp opening was made in the volar origin of the ulnar sagittal band at the soft tissue fascial confluence where the tendinous portion of the adductor aponeurosis joins the ulnar sided sagittal band. Testing was repeated to visualize whether a Stener lesion was created. Statistics Summary statistics were performed. Repeated measures ANOVA was used to compare three factors: UCL (intact, proper cut, both cut), degree of flexion (0° and 30°), and rotation (neutral, supination, pronation). A Bonferroni correction was applied. Subgroup analysis was performed to compare the groups with complete transection of the UCL. Statistical significance was set at p < .05.
RESULTS
Fig. 1. Testing method.
Clinical testing measurements are presented in Table 1. Pronation provided more stability, and supination provided less stability, with the pUCL or both components cut, especially when testing at 30° of flexion. Overall, 30° of flexion at the MCP joint provided less stability than full extension. The greatest amount of angulation occured when the MCP joint was tested in flexion and supination. Factor analysis showed a statistically significant difference in the amount of angulation based on condition of the UCL (p < .001), the degree of flexion (p = .001), but not on the degree of rotation (p = .39). Subgroup analysis showed, when compared to both components cut without flexion or rotation, there was a statistically significant difference in angulation with 30 degrees of MCP joint flexion in both neutral rotation (p
352 Manesha Lankachandra, et al. Stener Lesion Creation Physical Examination
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Table 1. Measurements Mean (SD) p -value
Mean (SD) p -value
Mean (SD) p -value
UCL intact
Proper UCL cut
Complete UCL cut
Neutral 0 degrees flexion 30 degrees flexion
22 (+/-3.9) 24 (+/-3.8)
28 (+/-4.6) 41 (+/-3.3)
43 (+/-6.0) 52 (+/-4.0) .02
Supinated 0 degrees flexion
22 (+/-4.5)
23 (+/-1.8)
25 (+/-5.6)
40 (+/-13.0)
42 (+/-12.9) .82 56 (+/-9/0) .01
22 (+/-4.9)
27 (+/-5.1)
24 (+/-10.9)
34 (+/-6.6)
30 degrees flexion Pronated 0 degrees flexion 30 degrees flexion
41 (+/-9.6) .38 49 (+/-10.0) .17
p -values are pairwise comparisons with the groups compared to the specimen group with the UCL completely cut, 0 degrees flexion, and no rotation. SD: Standard deviation.
= .02) and in supination (p = .01). No Stener lesion was created in any position as long as the fascia overlying the UCL, including the adductor aponeurosis, the ulnar sagittal band of the thumb, and the intervening fascial confluence between these two structures, remained intact. After creating a defect in the fascia as described above, a Stener lesion was created in two of six specimens when applying radial force with flexion and supination. Even with this defect, no lesion was created in neutral rotation. In two more specimens, the proximal limb of the cut UCL could be seen within the fascial defect, again with supination, flexion and a radially directed force. In these specimens, the UCL migrated so that is was proximal to the tendinous portion of the adductor aponeurosis, however, no tissue became interposed between the cut end of the UCL.
DISCUSSION In our study, performing a physical examination to assess the amount of instability of an ulnar collateral ligament injury did not create a Stener lesion if the exam was performed in a controlled, gentle manner with the thumb held without rotation. It was possible to create a Stener lesion when the thumb was tested in a flexed and supinated position, but only if there was sectioning of
the pUCL, the aUCL, and the origin of the ulnar sagittal band at the adductor aponeurosis. Injury to the thumb UCL of the MCP joint is common, and clinical evaluation guides further evaluation and treatment.8) Acute injuries are the result of a sudden, significant radial force causing abduction of the thumb. 9-11) The results of stress testing of the thumb MCP joint help to determine whether treatment will be non-operative with immobilization or with surgical reconstruction or repair. Fluoroscopy, MRI and ultrasound are increasingly being used and evaluated as diagnostic tools.3,6,12-14) Our results confirm the findings of Mayer et al that pronation and supination play a role in stability of the thumb MCP joint.15) We showed that supination and flexion of the thumb provided less stability when both components of the UCL were sectioned. In our study, the method of examination was designed to simulate clinical examination. The measurements were deliberately taken in a manner that reproduced a common method of clinical examination; one examiner stabilized and stressed the thumb in a slow, gentle manner while an assistant measured the alignment with a plastic goniometer (Fig. 1). Since measurements of the amount of force applied to the thumb are not routinely measured, force measurements were not performed. The order of sectioning the tissues, pUCL, aUCL, and then the aponeurosis, reproduced the sequence of injury in traumatic events.10,16) Similar to the finding of Adler et al, we were unable to create a Stener lesion after complete sectioning of the UCL at 0°and 30° of flexion with no rotation.16) We also did not create a Stener lesion with supination or pronation with intact overlying fascia. Unlike the study by Adler, we used fresh frozen cadavers rather than preserved specimens. We were also able to create a Stener lesion once the overlying fascia of the ulnar sagittal band was sectioned, likely because of the addition of a rotational component to our testing maneuver. The adductor aponeurosis lies superficial to the UCL and is continuous with the extensor mechanism of the thumb dorsally and to the tendinous insertion of the adductor pollicis on the ulnar sesamoid and palmar surface of the proximal phalanx volarly. It includes a thickened tendinous portion distally that is continuous with the thin fascial sheet of the ulnar sided sagittal band that lies more proximally. This complex lies over the UCL of the thumb.17) The study by Adler describes fibers connecting the UCL to the underlying joint capsule and the adductor aponeurosis superficially, and these soft tissue connections were apparent during our dissection.16)
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The adductor aponeurosis is often described or depicted as a discrete band over the ulnar side of the MCP joint.11) In our specimens, there was always a firm connection of the origin of the ulnar sagittal band to the proximal edge of the adductor aponeurosis. This connection has been described by Jaibaji et al.17) The ulnar sagittal band provides a continuous fascial connection from the adductor tendon, the volar plate, and the A1 pulley to the thumb extensor tendons. When the MCP joint is flexed, the ulnar sagittal band moves distally. In our study, as long as the adductor aponeurosis and the more proximal fascia of the ulnar sagittal band remained intact, the cut proximal end of the UCL did not migrate proximal and dorsal to the aponeurosis, and there was no interposition of tissue between the UCL and its footprint. New findings in our study showed that after creating a defect in this origin of the sagittal band, we were able to produce a Stener lesion with thumb supination and 30° of MCP joint flexion. The defect in the fascia overlying the UCL, along with the distal migration of the ulnar sagittal band with MCP joint flexion, allowed the proximal limb of the cut UCL to herniate through the fascia, thus isolating it from its footprint on the proximal phalanx. This finding is different than other studies, including Stener’s original study, that have not described a defect in this overlying fascia as part of the pathoanatomy of a Stener lesion.6,7,11) Based on our findings, in order to create an iatrogenic Stener lesion, there must also be a deficiency in the fascia overlying the UCL. Starting with an intact adductor aponeurosis complex and intact ulnar sagittal band in all of our specimens, we were not able to create this defect during any of our clinical testing maneuvers. Instead, we had to surgically section the overlying fascia proximal to the adductor aponeurosis and add a rotational component and distal migration in order to create a Stener lesion. This could explain why Adler et al were not able to create a Stener lesion during their testing. It is likely that the forces that result in a complete clinical rupture of the UCL also simultaneously create weakness or a tear in the overlying ulnar sagittal band. All of our injuries were created sharply, and therefore do not mimic the true mechanism of a UCL rupture. Further study is needed to verify our finding that there needs to be a rent in the fascia for a Stener lesion to occur. It is unknown whether all complete tears require operative treatment. In a retrospective study of 43 patients with UCL injuries reported by Milner et al., all patients were initially evaluated with MRI. All incomplete tears healed with immobilization, as did the patients with
complete tears displaced less than 3 mm. If the displacement was greater than 3 mm, 90% failed non-operative care. The authors discuss the potential dangers of clinical testing in increasing the displacement. 12) Further cadaveric and clinical studies will need to be performed to determine how clinical testing affects displacement and if clinical testing can convert a minimally displaced complete tear into a lesion that requires surgery. Most guidelines suggest clinical testing of patients suspected of having an UCL tear be performed at 0° and 30° without any rotation, and our study supports this recommendation. Our testing protocol reproduced the method used in clinical testing. If testing is inadvertently done with the thumb supinated, especially at 30° of flexion, a Stener lesion can be created. Care needs to be taken during examination to prevent supination. Limitations of our study include the small number of specimens, the high age of the specimens, and inability to test the contralateral side. The magnitude of the force applied by the examiner was not measured. Gentle force mimicking an actual physical exam in a patient was applied. While we looked at whether or not a Stener lesion could be created, additional studies are needed to determine how much displacement occurs during examination with a nondisplaced UCL rupture. Since only one set of examiners performed the study, the exam technique may not be consistent with other examiners. Further research is also needed to determine if, given the potential to increase the degree of injury, clinical exam with radial deviation should be replaced by other imaging modalities. While many authors have cautioned against the use of clinical exam, obtaining an MRI on every patient who presents with ulnar sided thumb pain is neither cost effective nor practical. We suggest that if clinical suspicion for a complete UCL injury is low, then an appropriately performed exam showing a solid end point that is similar to the contralateral side is a useful way to rule out the diagnosis of UCL rupture. If, due to the patient’s mechanism of injury or other physical exam findings, clinical suspicion for a more severe UCL injury is high, practitioners may consider the risks of physical exam versus other imaging modalities. If the thumb is held in neutral rotation during the exam, an iatrogenic Stener lesion should not be created.
SUPPORT PROVIDED Support provided the Department of Orthopaedic Surgery, University of Missouri–Kansas City School of
354 Manesha Lankachandra, et al. Stener Lesion Creation Physical Examination
Medicine
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REFERENCES 1. Heyman P. Injuries to the Ulnar Collateral Ligament of the Thumb Metacarpophalangeal Joint. J Am Acad Orthop Surg. 1997;5:224-9. 2. Louis DS, Huebner JJ, Jr., Hankin FM. Rupture and displacement of the ulnar collateral ligament of the metacarpophalangeal joint of the thumb. Preoperative diagnosis. J Bone Joint Surg Am. 1986;68:1320-6. 3. Rhee PC, Jones DB, Kakar S. Management of thumb metacarpophalangeal ulnar collateral ligament injuries. J Bone Joint Surg Am. 2012;94:2005-12. 4. Ritting AW, Baldwin PC, Rodner CM. Ulnar collateral ligament injury of the thumb metacarpophalangeal joint. Clin J Sport Med. 2010;20:106-12. 5. Schroeder NS, Goldfarb CA. Thumb ulnar collateral and radial collateral ligament injuries. Clin Sports Med. 2015;34:117-26. 6. Tsiouri C, Hayton MJ, Baratz M. Injury to the ulnar collateral ligament of the thumb. Hand (N Y). 2009;4:12-8. 7. Stener B. Skeletal injuries associated with rupture of the ulnar collateral ligament of the metacarpophalangeal joint of the thumb. A clinical and anatomical study. Acta Chir Scand. 1963;125:583-6. 8. Avery DM, Caggiano NM, Matullo KS. Ulnar collateral ligament injuries of the thumb: a comprehensive review. Orthop Clin North Am. 2015;46:281-92. 9. Carlson MG, Warner KK, Meyers KN, Hearns KA, Kok PL.
Anatomy of the thumb metacarpophalangeal ulnar and radial collateral ligaments. J Hand Surg Am. 2012;37:2021-6. 10. Fraser B, Veitch J, Firoozbakhsh K. Assessment of rotational instability with disruption of the accessory collateral ligament of the thumb MCP joint: a biomechanical study. Hand (N Y). 2008;3:224-8. 11. Tang P. Collateral ligament injuries of the thumb metacarpophalangeal joint. J Am Acad Orthop Surg. 2011;19:28796. 12. Milner CS, Manon-Matos Y, Thirkannad SM. Gamekeeper's thumb--a treatment-oriented magnetic resonance imaging classification. J Hand Surg Am. 2015;40:90-5. 13. Patel A, Patel A, Edelstein D, Choueka J. Fluoroscopyassisted stress testing of the thumb metacarpophalangeal joint to assess the ulnar collateral ligament. Hand (N Y). 2013;8:205-9. 14. McKeon KE, Gelberman RH, Calfee RP. Ulnar collateral ligament injuries of the thumb: phalangeal translation during valgus stress in human cadavera. J Bone Joint Surg Am. 2013;95:881-7. 15. Mayer SW, Ruch DS, Leversedge FJ. The influence of thumb metacarpophalangeal joint rotation on the evaluation of ulnar collateral ligament injuries: a biomechanical study in a cadaver model. J Hand Surg Am. 2014;39:474-9. 16. Adler T, Eisenbarth I, Hirschmann MT, Müller-Gerbl M, Fricker R. Can clinical examination cause a Stener lesion in patients with skier's thumb?: a cadaveric study. Clin Anat. 2012;25:762-6. 17. Jaibaji M, Rayan GM, Chung KW. Functional anatomy of the thumb sagittal band. J Hand Surg Am. 2008;33:879-84.
The Journal of Hand Surgery (Asian-Pacific Volume) 2017;22(3):350-354 • DOI: 10.1142/S0218810417500411
Can Physical Examination Create a Stener Lesion? Manesha Lankachandra*, John P. Eggers*, James W. Bogener*, Richard L. Hutchison† *Department of Orthopaedic Surgery, University of Missouri, Kansas City, MO, USA Section of Hand Surgery, Children’s Mercy Hospitals and Clinics, Kansas City, MO, USA
J Hand Surg Asian-Pac Vol 2017.22:350-354. Downloaded from www.worldscientific.com by UNIVERSITY OF AUCKLAND on 09/17/17. For personal use only.
†
Background: The purpose of this study is to determine whether a Stener lesion can be created while testing stability of the ulnar collateral ligament (UCL) of the thumb. Testing was performed in a manner that reproduced clinical examination. Methods: Six fresh frozen hand and forearm specimens underwent sequential sectioning of the accessory UCL, the proper UCL, and the ulnar sagittal band. Measurements of radial deviation of the metacarpophalangeal (MCP) joint were taken with the thumb in neutral rotation, pronation and supination, both with 0 degrees and with 30 degrees of flexion of the MCP joint. Visual examination was performed to assess the presence of a Stener lesion. Results: No Stener lesion was created in any position as long as the fascial origin of the ulnar sagittal band at the adductor pollicis longus remained intact. After creating a defect in the ulnar sagittal band, a Stener lesion was created in two specimens, but only when the thumb was flexed and supinated. Pronation provided more stability, and supination provided less stability, with one or both components cut, especially when testing at 30° of flexion. Compared to both components cut without flexion or rotation, there was a statistically significant difference in angulation with the 30 degrees of MCP joint flexion in both neutral rotation in supination. Conclusions: Performing a physical examination to assess the amount of instability of an ulnar collateral ligament injury did not create a Stener lesion if the exam was performed in a controlled, gentle manner with the thumb held without rotation. If the thumb is held in neutral rotation during the exam, an iatrogenic Stener lesion should not be created. Keywords: Stener lesion, Ulnar collateral ligament of the thumb, Stress test, Physical examination
INTRODUCTION A Stener lesion can be the result of trauma to the ulnar collateral ligament (UCL) of the metacarpophalangeal (MCP) joint of the thumb, and can potentially be created during physical examination of an injured UCL. Physical examination routinely involves applying a valgus force to the MCP joint at 0° and 30° of flexion and measuring the amount of radial angulation. Multiple
Received: May. 19, 2016; Revised: Aug. 21, 2016; Accepted: Sep. 20, 2016 Correspondence to: Richard L. Hutchison Section of Hand Surgery, Children’s Mercy Hospitals and Clinics, 2401 Gillham Road Kansas City, MO 64108, USA Tel: +816-234-3693, Fax: +816-855-1993 E-mail: [email protected]
studies have evaluated the magnitude of angulation measured during physical examination that correlates with a complete rupture of the UCL. The conclusions vary, but angulation of 30–45°, or a 10–15° difference in laxity when compared to the contralateral uninjured side, generally suggests a complete tear of both components of the UCL.1-6) Treatment guidelines for thumb UCL injuries are based on the severity of injury. Partial tears of the proper UCL (pUCL) or the accessory UCL (aUCL), or complete tears with minimal displacement, can be treated effectively with immobilization. Complete tears respond more predictably to operative repair.1-5) Stener, in his original paper, described his eponymous lesion as complete rupture of the UCL and interposition of the adductor aponeurosis between the distally avulsed UCL and its
351
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footprint on the proximal phalanx, and these injuries are generally treated operatively.7) Since treatment is dependent on the severity of a tear and its displacement, there is a concern that clinical testing may increase the severity of injury, possibly converting a UCL disruption to a Stener lesion. Examination guidelines suggest positioning the thumb without rotation during exam. During exam, pronation or supination of the thumb may inadvertently occur. The purpose of this study was to discover if a Stener lesion could be created by clinical examination in a thumb with nondisplaced transection of the distal components of the ulnar collateral ligament. We hypothesized that a Stener lesion could be created during physical exam if testing was performed while the thumb was rotated into either pronation or supination, and that a Stener lesion would not be created by exam with maintenance of the thumb in neutral rotation.
METHODS Six thawed fresh-frozen hand and forearm specimens were used. Average age was 86 years, with three males and three females. All specimens were in satisfactory condition, and none had any apparent injury, arthritis, or other disease. Measurements of radial deviation of the MCP joint were taken with the thumb in neutral rotation, pronation and supination, both in 0° and in 30° of MCP flexion. Gentle pronation and supination force was achieved manually by one of the investigators. Measurements were obtained with one examiner stabilizing the metacarpal and proximal phalanx and then slowly and
gently applying the loads in a manner that reproduced clinical examination, while a second examiner used a hand-held goniometer to measure the degree of angulation at the MCP joint in the coronal and sagittal planes of the thumb. An example of the testing method is depicted in Fig. 1. Application of the gentle force was stopped when a firm endpoint was felt. Three measurements were made and then averaged for each combination of joint position. The pUCL and the aUCL were serially sectioned at their distal insertions on the proximal phalanx, mimicking the most common site of clinical rupture. Radial deviation measurements were repeated. The adductor aponeurosis complex and the ulnar sagittal band were initially left intact, and visual examination was performed to assess the presence of a Stener lesion. After measurements were obtained with both UCL components sectioned, a sharp opening was made in the volar origin of the ulnar sagittal band at the soft tissue fascial confluence where the tendinous portion of the adductor aponeurosis joins the ulnar sided sagittal band. Testing was repeated to visualize whether a Stener lesion was created. Statistics Summary statistics were performed. Repeated measures ANOVA was used to compare three factors: UCL (intact, proper cut, both cut), degree of flexion (0° and 30°), and rotation (neutral, supination, pronation). A Bonferroni correction was applied. Subgroup analysis was performed to compare the groups with complete transection of the UCL. Statistical significance was set at p < .05.
RESULTS
Fig. 1. Testing method.
Clinical testing measurements are presented in Table 1. Pronation provided more stability, and supination provided less stability, with the pUCL or both components cut, especially when testing at 30° of flexion. Overall, 30° of flexion at the MCP joint provided less stability than full extension. The greatest amount of angulation occured when the MCP joint was tested in flexion and supination. Factor analysis showed a statistically significant difference in the amount of angulation based on condition of the UCL (p < .001), the degree of flexion (p = .001), but not on the degree of rotation (p = .39). Subgroup analysis showed, when compared to both components cut without flexion or rotation, there was a statistically significant difference in angulation with 30 degrees of MCP joint flexion in both neutral rotation (p
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Table 1. Measurements Mean (SD) p -value
Mean (SD) p -value
Mean (SD) p -value
UCL intact
Proper UCL cut
Complete UCL cut
Neutral 0 degrees flexion 30 degrees flexion
22 (+/-3.9) 24 (+/-3.8)
28 (+/-4.6) 41 (+/-3.3)
43 (+/-6.0) 52 (+/-4.0) .02
Supinated 0 degrees flexion
22 (+/-4.5)
23 (+/-1.8)
25 (+/-5.6)
40 (+/-13.0)
42 (+/-12.9) .82 56 (+/-9/0) .01
22 (+/-4.9)
27 (+/-5.1)
24 (+/-10.9)
34 (+/-6.6)
30 degrees flexion Pronated 0 degrees flexion 30 degrees flexion
41 (+/-9.6) .38 49 (+/-10.0) .17
p -values are pairwise comparisons with the groups compared to the specimen group with the UCL completely cut, 0 degrees flexion, and no rotation. SD: Standard deviation.
= .02) and in supination (p = .01). No Stener lesion was created in any position as long as the fascia overlying the UCL, including the adductor aponeurosis, the ulnar sagittal band of the thumb, and the intervening fascial confluence between these two structures, remained intact. After creating a defect in the fascia as described above, a Stener lesion was created in two of six specimens when applying radial force with flexion and supination. Even with this defect, no lesion was created in neutral rotation. In two more specimens, the proximal limb of the cut UCL could be seen within the fascial defect, again with supination, flexion and a radially directed force. In these specimens, the UCL migrated so that is was proximal to the tendinous portion of the adductor aponeurosis, however, no tissue became interposed between the cut end of the UCL.
DISCUSSION In our study, performing a physical examination to assess the amount of instability of an ulnar collateral ligament injury did not create a Stener lesion if the exam was performed in a controlled, gentle manner with the thumb held without rotation. It was possible to create a Stener lesion when the thumb was tested in a flexed and supinated position, but only if there was sectioning of
the pUCL, the aUCL, and the origin of the ulnar sagittal band at the adductor aponeurosis. Injury to the thumb UCL of the MCP joint is common, and clinical evaluation guides further evaluation and treatment.8) Acute injuries are the result of a sudden, significant radial force causing abduction of the thumb. 9-11) The results of stress testing of the thumb MCP joint help to determine whether treatment will be non-operative with immobilization or with surgical reconstruction or repair. Fluoroscopy, MRI and ultrasound are increasingly being used and evaluated as diagnostic tools.3,6,12-14) Our results confirm the findings of Mayer et al that pronation and supination play a role in stability of the thumb MCP joint.15) We showed that supination and flexion of the thumb provided less stability when both components of the UCL were sectioned. In our study, the method of examination was designed to simulate clinical examination. The measurements were deliberately taken in a manner that reproduced a common method of clinical examination; one examiner stabilized and stressed the thumb in a slow, gentle manner while an assistant measured the alignment with a plastic goniometer (Fig. 1). Since measurements of the amount of force applied to the thumb are not routinely measured, force measurements were not performed. The order of sectioning the tissues, pUCL, aUCL, and then the aponeurosis, reproduced the sequence of injury in traumatic events.10,16) Similar to the finding of Adler et al, we were unable to create a Stener lesion after complete sectioning of the UCL at 0°and 30° of flexion with no rotation.16) We also did not create a Stener lesion with supination or pronation with intact overlying fascia. Unlike the study by Adler, we used fresh frozen cadavers rather than preserved specimens. We were also able to create a Stener lesion once the overlying fascia of the ulnar sagittal band was sectioned, likely because of the addition of a rotational component to our testing maneuver. The adductor aponeurosis lies superficial to the UCL and is continuous with the extensor mechanism of the thumb dorsally and to the tendinous insertion of the adductor pollicis on the ulnar sesamoid and palmar surface of the proximal phalanx volarly. It includes a thickened tendinous portion distally that is continuous with the thin fascial sheet of the ulnar sided sagittal band that lies more proximally. This complex lies over the UCL of the thumb.17) The study by Adler describes fibers connecting the UCL to the underlying joint capsule and the adductor aponeurosis superficially, and these soft tissue connections were apparent during our dissection.16)
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The Journal of Hand Surgery (Asian-Pacific Volume) • Vol. 22, No. 3, 2017 • www.jhs-ap.org
The adductor aponeurosis is often described or depicted as a discrete band over the ulnar side of the MCP joint.11) In our specimens, there was always a firm connection of the origin of the ulnar sagittal band to the proximal edge of the adductor aponeurosis. This connection has been described by Jaibaji et al.17) The ulnar sagittal band provides a continuous fascial connection from the adductor tendon, the volar plate, and the A1 pulley to the thumb extensor tendons. When the MCP joint is flexed, the ulnar sagittal band moves distally. In our study, as long as the adductor aponeurosis and the more proximal fascia of the ulnar sagittal band remained intact, the cut proximal end of the UCL did not migrate proximal and dorsal to the aponeurosis, and there was no interposition of tissue between the UCL and its footprint. New findings in our study showed that after creating a defect in this origin of the sagittal band, we were able to produce a Stener lesion with thumb supination and 30° of MCP joint flexion. The defect in the fascia overlying the UCL, along with the distal migration of the ulnar sagittal band with MCP joint flexion, allowed the proximal limb of the cut UCL to herniate through the fascia, thus isolating it from its footprint on the proximal phalanx. This finding is different than other studies, including Stener’s original study, that have not described a defect in this overlying fascia as part of the pathoanatomy of a Stener lesion.6,7,11) Based on our findings, in order to create an iatrogenic Stener lesion, there must also be a deficiency in the fascia overlying the UCL. Starting with an intact adductor aponeurosis complex and intact ulnar sagittal band in all of our specimens, we were not able to create this defect during any of our clinical testing maneuvers. Instead, we had to surgically section the overlying fascia proximal to the adductor aponeurosis and add a rotational component and distal migration in order to create a Stener lesion. This could explain why Adler et al were not able to create a Stener lesion during their testing. It is likely that the forces that result in a complete clinical rupture of the UCL also simultaneously create weakness or a tear in the overlying ulnar sagittal band. All of our injuries were created sharply, and therefore do not mimic the true mechanism of a UCL rupture. Further study is needed to verify our finding that there needs to be a rent in the fascia for a Stener lesion to occur. It is unknown whether all complete tears require operative treatment. In a retrospective study of 43 patients with UCL injuries reported by Milner et al., all patients were initially evaluated with MRI. All incomplete tears healed with immobilization, as did the patients with
complete tears displaced less than 3 mm. If the displacement was greater than 3 mm, 90% failed non-operative care. The authors discuss the potential dangers of clinical testing in increasing the displacement. 12) Further cadaveric and clinical studies will need to be performed to determine how clinical testing affects displacement and if clinical testing can convert a minimally displaced complete tear into a lesion that requires surgery. Most guidelines suggest clinical testing of patients suspected of having an UCL tear be performed at 0° and 30° without any rotation, and our study supports this recommendation. Our testing protocol reproduced the method used in clinical testing. If testing is inadvertently done with the thumb supinated, especially at 30° of flexion, a Stener lesion can be created. Care needs to be taken during examination to prevent supination. Limitations of our study include the small number of specimens, the high age of the specimens, and inability to test the contralateral side. The magnitude of the force applied by the examiner was not measured. Gentle force mimicking an actual physical exam in a patient was applied. While we looked at whether or not a Stener lesion could be created, additional studies are needed to determine how much displacement occurs during examination with a nondisplaced UCL rupture. Since only one set of examiners performed the study, the exam technique may not be consistent with other examiners. Further research is also needed to determine if, given the potential to increase the degree of injury, clinical exam with radial deviation should be replaced by other imaging modalities. While many authors have cautioned against the use of clinical exam, obtaining an MRI on every patient who presents with ulnar sided thumb pain is neither cost effective nor practical. We suggest that if clinical suspicion for a complete UCL injury is low, then an appropriately performed exam showing a solid end point that is similar to the contralateral side is a useful way to rule out the diagnosis of UCL rupture. If, due to the patient’s mechanism of injury or other physical exam findings, clinical suspicion for a more severe UCL injury is high, practitioners may consider the risks of physical exam versus other imaging modalities. If the thumb is held in neutral rotation during the exam, an iatrogenic Stener lesion should not be created.
SUPPORT PROVIDED Support provided the Department of Orthopaedic Surgery, University of Missouri–Kansas City School of
354 Manesha Lankachandra, et al. Stener Lesion Creation Physical Examination
Medicine
J Hand Surg Asian-Pac Vol 2017.22:350-354. Downloaded from www.worldscientific.com by UNIVERSITY OF AUCKLAND on 09/17/17. For personal use only.
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