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DOI:10.2214/AJR.08.1057
AJR 2008; 191:W199-W203
© American Roentgen Ray Society

Clinical Observations

Screw Impingement on the Extensor Tendons in Distal Radius Fractures Treated by Volar Plating: Sonographic Appearance

Stefano Bianchi1, Jan van Aaken2, Thierry Glauser3, Carlo Martinoli4, Jean-Yves Beaulieu2 and Dominique Della Santa2

1 Institut de Radiologie, Clinique des Grangettes, 7 Chemin des Grangettes, 1224 Geneva, Switzerland.
2 Departemente de Orthopedie, Hôpital Universitaire de Geneve, Geneva, Switzerland.
3 Centre de Chirurgie et de Thérapie de la Main, Geneva, Switzerland.
4 Cattedra di Radiologia, DICMI, Università di Genova, Genova, Italia.

Received April 11, 2008; accepted after revision May 23, 2008.

 
Address correspondence to S. Bianchi (stefanobianchi{at}bluewin.ch).

WEB

This is a Web exclusive article.


Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
OBJECTIVE. The objective of our study was to analyze the sonography examinations of nine consecutive patients with a history of distal radius fracture treated by open reduction and internal fixation of the volar plate who were referred by hand surgeons for sonography of the dorsal aspect of the wrist.

CONCLUSION. We postulate that impingement of the extensor tendons in patients with distal radius fracture treated by volar plating starts with local hyperemia and is followed by tenosynovitis and, finally, by partial and complete tendon tears. Sonography is an effective, dynamic, and noninvasive technique with which to diagnose and evaluate damage to the extensor tendons and their synovial sheaths.

Keywords: extensor tendons of the wrist • hand and wrist imaging • radius fracture • screw impingement • sonography • tendinopathy • ultrasound • volar plating


Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Fractures of the distal radius are frequent and their incidence can be expected to increase because the older population continues to increase in number [1]. Surgical treatment allows optimal fragment reduction and is advocated when a significant dorsal tilt is present or fractures are unstable. The most commonly performed surgical procedure is open reduction and internal fixation of the volar plate [1, 2]. Tendon inflammation and tears are possible complications of that procedure due to dorsally protruding screw impingement on the extensor tendons. Sonography is a readily available and atraumatic imaging technique that allows accurate and inexpensive assessment of the musculoskeletal system [3]. The extensor tendons of the wrist are well depicted by high-resolution broadband electronic transducers because of their superficial location [3, 4]. We present a retrospective analysis of the sonography examinations of nine consecutive patients presenting with screw impingement on the extensor tendons examined in the past 3.5 years.


Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
From January 2005 to April 2008, nine consecutive patients were referred by hand surgeons for sonography of the dorsal aspect of the wrist. All had a history of distal radius fracture treated by open reduction and internal fixation of the volar plate. There were two men and seven women with an age range of 42–71 years (mean age, 54 years). Three right wrists and six left wrists were affected. Four patients were referred with a presumptive diagnosis of complete extensor pollicis longus (EPL) tear and three had a diagnosis of tenosynovitis; one, a dorsal mass; and one, a ganglion cyst. Patients presented with local pain (n = 8), swelling (n = 7), and inability to extend the distal phalanx of the thumb (n = 4). Informed consent was obtained to search patients' data retrospectively. Institutional review board approval was obtained.

All sonography examinations were performed by a trained musculoskeletal radiologist with 22 years of experience in musculoskeletal sonography. The mean delay between surgery and sonography examination was 7 months (range, 1–27 months). The dorsal aspect of the wrist was examined on transverse and sagittal sonograms obtained while the patient was seated in front of the examiner with the pronated wrist resting on an examination table. All 12 extensor tendons, running inside the six compartments, were carefully analyzed (Fig. 1). A broadband 17-5–MHz linear transducer (model iU22, Philips Healthcare) was used. No standoff pad was used, and transmission gel was used liberally. Attention was directed to looking for changes in the internal structure of the extensor tendons, thickening of the tendons' sheaths, and evidence of synovial effusions. The presence or absence of tendon tears was noted. We also evaluated focal interruption of the dorsal cortex of the distal radius, the number and location of detectable screw tips, and the length that each screw tip protruded using electronic calipers. In cases of complete tendon tears, the retraction of the tendon ends and their locations were assessed.


Figure 1
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  		Fig. 1 —Axial schematic drawing shows that 12 extensor tendons of wrist (a–i) run inside six fibroosseous tunnels (1–6) numbered from lateral to medial. a = abductor pollicis longus, b = extensor pollicis brevis, c = extensor carpi radialis longus, d = extensor carpi radialis brevis, e = extensor pollicis longus, f = extensor indicis proprius, g = extensor digitorum communis, h = extensor digiti minimi, i = extensor carpi ulnaris, LT = Lister tubercle.

 

Color Doppler imaging was used to evaluate local neovascularity. Dynamic examination was performed; sagittal and transverse sonograms were obtained during simultaneous active and passive movements of the fingers. To confirm the sonography appearance of the screw tips, we performed an in vitro examination of a surgical screw that is used to fix volar plates. For this purpose, the screw was placed in a water bath and assessed with the same sonographic equipment and transducer that is used in vivo (Fig. 2A, 2B). A screw's tip was recognized on sonography both in vitro and then in vivo as a triangular structure made by multiple parallel hyperechoic lines corresponding to the thread (Figs. 2A, 2B and 3A, 3B, 3C).


Figure 2
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  		Fig. 2A —In vitro appearance of a volar plate screw. Sonogram obtained over screw tip (arrow) shows that thread (arrowheads) appears as multiple oblique parallel hyperechoic lines.

 

Figure 3
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  		Fig. 2B —In vitro appearance of a volar plate screw. Corresponding photograph of examined screw shows tip (arrow) and thread (arrowheads).

 

Figure 4
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  		Fig. 3A —In vivo sonography appearance of screw tip impingement on extensor tendons in 66-year-old woman who had undergone volar plating for distal radius fracture (patient 8 in Table 1). Transverse sonogram obtained over dorsal distal epiphysis of radius shows tips of small (small arrow) and large (large arrow) screws (cursors) protruding inside third and fourth extensor compartments. Extensor tendons (ETs) are located close to tips and are surrounded by thickened synovium. LT = Lister tubercle.

 

Figure 5
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  		Fig. 3B —In vivo sonography appearance of screw tip impingement on extensor tendons in 66-year-old woman who had undergone volar plating for distal radius fracture (patient 8 in Table 1). Sagittal sonogram obtained over fourth extensor compartment shows close relation of large screw tip (arrow) and extensor tendons (ETs). Note hypoechoic, thickened synovium (arrowheads) surrounding tendons. Lun = lunate bone.

 

Figure 6
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  		Fig. 3C —In vivo sonography appearance of screw tip impingement on extensor tendons in 66-year-old woman who had undergone volar plating for distal radius fracture (patient 8 in Table 1). Photograph obtained during surgical exploration confirms screw tip (black arrow) is protruding inside fourth extensor compartment. Note distal stump of torn extensor indicis proprius tendon (white arrow). ETs = extensor tendons.

 
On sonography, tenosynovitis was diagnosed by the presence of an effusion or thickening of the synovium (or both) (Fig. 4A, 4B). A partial tendon tear was diagnosed if an incomplete interruption of the normal fibrillar tendon structure was found. A complete tear was diagnosed if the tendon appeared completely broken and retraction of the tendon's ends was evident (Fig. 5A, 5B, 5C, 5D). All patients had anteroposterior and lateral standard radiographs of the affected wrist that had been interpreted as normal. Because of the presence of a metallic screw or screws, neither CT nor MRI was performed. All patients underwent hardware removal (mean interval between sonography and surgical removal, 25 days). Follow-up information was obtained by telephone calls with seven patients (mean, 4 months after surgery). Follow-up sonog raphy was not performed.


Figure 7
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  		Fig. 4A —61-year-old woman with history of volar plating for distal radius fracture who presented with screw impingement on extensor tendons and tenosynovitis (patient 2 in Table 1). Transverse sonogram obtained over dorsal aspect of wrist shows tenosynovitis of extensor tendons (ETs). Note anechoic effusion (black arrowhead) and hypertrophy of synovium (white arrowheads) filling tendon sheath.

 

Figure 8
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  		Fig. 4B —61-year-old woman with history of volar plating for distal radius fracture who presented with screw impingement on extensor tendons and tenosynovitis (patient 2 in Table 1). Corresponding transverse color Doppler sonogram depicts hyperemic changes within inflamed tendon sheath. ETs = extensor tendons.

 

Figure 9
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  		Fig. 5A —71-year-old woman with screw impingement on extensor tendons and complete tear of extensor pollicis longus tendon (patient 3 in Table 1). Sagittal sonograms obtained over proximal (A) and distal (B) stump show retracted hypoechoic, swollen tendon stumps (asterisks). Tendon sheath (arrowheads, A) located between stumps contains debris and small effusion. ETs = extensor tendons. In B, ECRL indicates extensor carpi radialis longus muscle and ECRB, extensor carpi radialis brevis muscle.

 

Figure 10
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  		Fig. 5B —71-year-old woman with screw impingement on extensor tendons and complete tear of extensor pollicis longus tendon (patient 3 in Table 1). Sagittal sonograms obtained over proximal (A) and distal (B) stump show retracted hypoechoic, swollen tendon stumps (asterisks). Tendon sheath (arrowheads, A) located between stumps contains debris and small effusion. ETs = extensor tendons. In B, ECRL indicates extensor carpi radialis longus muscle and ECRB, extensor carpi radialis brevis muscle.

 

Figure 11
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  		Fig. 5C —71-year-old woman with screw impingement on extensor tendons and complete tear of extensor pollicis longus tendon (patient 3 in Table 1). Transverse sonograms obtained over retracted proximal stump (asterisk, C) and at level of Lister tubercle (LT, D). In D, note empty tendon sheath (arrowhead) and extensor tendons (ETs).

 

Figure 12
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  		Fig. 5D —71-year-old woman with screw impingement on extensor tendons and complete tear of extensor pollicis longus tendon (patient 3 in Table 1). Transverse sonograms obtained over retracted proximal stump (asterisk, C) and at level of Lister tubercle (LT, D). In D, note empty tendon sheath (arrowhead) and extensor tendons (ETs).

 

Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
In the nine patients, sonography showed 12 protruding screws: Two screws were evident in each of three patients and one screw was evident in each of six patients. The results are summarized in Table 1. Six screws were located in the third extensor compartment, five in the fourth, and one in the second. The mean length of the portion of screw protruding from the radial cortex was 2.7 mm (range, 1.6–5.1 mm).


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  		TABLE 1: Patient Characteristics, Sonography Findings, Treatment, and Outcome in Nine Patients

 

All patients had signs of screw impingement of the extensor tendons at dynamic examination. For one patient (patient 9), sonography showed normal tendons and tendon sheaths. Nevertheless, sonography performed during finger movements revealed that pressure applied with the transducer on the protruding screw tip was painful. Five patients presented with tenosynovitis with synovial effusions and hypertrophy and increased vascularity at color Doppler imaging. Four patients presented with a complete tear of the EPL associated with retractions of the tendon stumps. The mean gap between the tendon stumps was 31 mm (range, 25–39 mm). Patient 8 had a partial tear of the EPL and a complete tear of the extensor indicis proprius (EIP) due to two screws' tips protruding inside the third and fourth compartments, respectively. Both tears were not diagnosed clinically.

Surgery confirmed the sonography diagnosis in all patients. In four patients, surgery showed an EPL tear and in one patient, an EIP tear. In all patients with complete tendon tears, a tendon transfer was performed. In seven patients, telephone follow-up revealed a good outcome with disappearance of local pain and swelling. Two patients were unavailable for follow-up.


Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Fractures of the distal radius can be complicated by tendon inflammation and tears [1]. Tears of the EPL occur in as many as 3% of patients [5]. They can follow a direct crush injury, mechanical impingement on sharp bone fragments, local ischemia due to reduced flow in the tenuous blood supply of the tendon, and increased pressure inside the osteofibrous tunnel when the retinaculum is intact [6]. The other extensor tendons are less subject to ischemia than the EPL because of their larger tendon sheath and better vascularity and they rupture mainly as a result of mechanical insults.

Sonography is a readily available and atraumatic imaging technique that allows accurate and inexpensive assessment of the musculoskeletal system [3]. Sonography has two definite advantages in assessing extensor tendons of the wrist: It allows a dynamic examination during passive and active tendon movements and it can be used when the presence of orthopedic hardware limits use of MRI. Pathologic changes of the EPL and its tendon sheath can be detected on sonography in patients with previous distal radius fractures [6–8]. In a study by Owers et al. [6], sonography showed thickening of both the tendon and its retinaculum in 62 patients with a radius fracture in which open reduction and internal fixation had not been performed.

Changes due to tendinopathy could impair the already tenuous blood supply to the tendon and lead to attrition and subsequent rupture.

Fractures of the distal epiphysis of the radius are treated surgically when dorsally displaced and unstable. Volar plating is currently widely replacing dorsal plate fixation because of the lower rate of local complications [2]. Although volar plates are usually well tolerated, they can lead to impingement on the extensor tendons when the fixation screws are too long and extend beyond the dorsal cortex of the radius. This form of impingement has been reported in several articles in the orthopedics literature [8–12], but we are unaware of similar studies in the radiology literature.

In a recent study, De Maeseneer et al. [7] reported the normal sonography appearance of EPL and correlated the sonography findings with findings at cadaveric dissection. In addition, they reported the sonography appearance of a complete EPL tear in five patients. In two patients, a history of wrist and radius fracture was present, but no information concerning eventual impingement with screws was reported.

Santiago et al. [8] reported on 12 patients presenting with EPL tears that were evaluated on sonography. The authors correlated the sonography appearance with CT and MRI as well as surgical findings. Only four of the 12 patients studied presented with tears after distal radius fractures. All were treated with Kirschner-wire fixation and not with volar plating [8]. Although the authors of several articles in the orthopedics literature have described extensor tendon tears caused by protruding screws [9–12], in none was sonography used preoperatively.

Because in recent years we examined several patients who presented with screw impingement on the extensor tendons using sonography, we performed a computer retrospective analysis of our files that allowed us to collect sonography examinations of nine patients. To the best of our knowledge, our small series is the largest showing the sonography appearance of screw impingement on the extensor tendons after volar plating. Limitations of our study are the small sample size and the presence of only one reader.

Our data show that sonography can be used to evaluate pathologic findings related to dorsal extrusion of screws and impingement on adjacent soft tissues. The screws' tips can be easily detected on either axial or sagittal scans when they protrude from the bone cortex. A screw typically appears as a hyperechoic structure made by multiple parallel oblique echogenic lines that correspond to the thread of the screw. The in vitro sonography appearance correlated precisely with the in vivo findings.

The sonographic appearance of tenosynovitis in patients with screw impingement on the extensor tendons was similar to that seen in systemic inflammatory disorders. The effusion could be seen as a hypoechoic–anechoic area that partially or completely surrounded the tendon and that was contained within the tendon sheath. The sheath appeared as a focal or diffuse thickening presenting internal flow signals at color Doppler imaging as a result of local hyperemia. The relation of the tendons, their inflamed sheaths, and the protruding screws was evident at sonography, particularly during dynamic examination. Scanning in both the transverse and sagittal planes while patients moved their fingers clearly showed impingement of the tendons against the protruding screws. The tendons' internal echostructure was easily assessed because of their superficial location.

As for other regions, an internal hypoechoic appearance of a tendon together with swelling or thinning of a tendon was noted in the patient with a partial EPL tear. Complete tears were shown more easily as a complete interruption of the tendon. Dynamic examination performed while asking the patient to extend the affected finger showed movements only of the proximal stump, thus confirming the diagnosis.

Our cohort of patients is too small to define the pathogenesis of the spectrum of soft-tissue abnormalities in extensor tendon screw impingement. We can only postulate that impingement starts with local hyperemia and is followed by tenosynovitis and, finally, by partial and complete tendon tears. EPL tears are probably more frequent because of the watershed area of the tendon at the level of the Lister tubercle making it subject to tears when exposed to local repetitive trauma. In addition, the third extensor compartment is smaller and does not allow the EPL to be displaced by the screw if the retinaculum is intact.

Standard radiography and MRI can be used theoretically to assess screws protruding dorsally and screw impingement on the extensor tendons. The protruding screw tips can be masked by the Lister tubercle at standard fluoroscopy performed during plate positioning as well as at follow-up radiography [9]. In addition, standard radiographs are useless in evaluating soft tissue. MRI has not been evaluated in assessing soft tissues in patients who have undergone surgery owing to the presence of artifacts due to the metallic hardware.

In conclusion, screw impingement on the extensor tendons can develop in patients treated by volar plating for radius fractures when there is significant dorsal protrusion of the screws. Clinical findings can suggest the correct diagnosis, but imaging can confirm the clinical data and show tears that cannot be confirmed on the basis of the clinical examination such as tears of the EIP. Standard radiography and MRI have evident limitations in assessing screw impingement on the extensor tendons due to the impossibility of evaluating soft tissues and the presence of artifact because of the metallic hardware. Sonography is an effective, dynamic, and noninvasive technique with which to diagnose screw impingement on the extensor tendons and evaluate damage to the extensor tendons and their synovial sheaths.


References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Neal C, Chen NC, Jupiter JB. Management of distal radial fractures. J Bone Joint Surg Am 2007;89 :2051 –2062[Free Full Text]
  2. Ruch DS, Papadonikolakis A. Volar versus dorsal plating in the management of intra-articular distal radius fractures. J Hand Surg Am 2006; 31:9 –16[CrossRef][Medline]
  3. Bianchi S, Martinoli C. Ultrasound of the musculoskeletal system, 1st ed. Heidelberg, Germany: Springer-Verlag, 2007: 975
  4. Tagliafico A, Rubino M, Autuori A, Bianchi S, Martinoli C. Wrist and hand ultrasound. Semin Musculoskelet Radiol2007; 11:95 –104[CrossRef][Medline]
  5. Skoff HD. Postfracture extensor pollicis longus tenosynovitis and tendon rupture: a scientific study and personal series. Am J Orthop 2003; 32:245 –247[Medline]
  6. Owers KL, Lee J, Khan N, Healy J, Eckersley R. Ultrasound changes in the extensor pollicis longus tendon following fractures of the distal radius: a preliminary report. J Hand Surg Eur Vol2007; 32:467 –471[Abstract/Free Full Text]
  7. De Maeseneer M, Marcelis S, Osteaux M, Jager T, Machiels F, Van Roy P. Sonography of a rupture of the tendon of the extensor pollicis longus muscle: initial clinical experience and correlation with findings at cadaveric dissection. AJR 2005;184 : 175–179[Abstract/Free Full Text]
  8. Santiago FR, Plazas PG, Fernández JM. Sonography findings in tears of the extensor pollicis longus tendon and correlation with CT, MRI and surgical findings. Eur J Radiol 2008;66 : 112–116[CrossRef][Medline]
  9. Benson EC, DeCarvalho A, Mikola EA, Veitch JM, Moneim MS. Two potential causes of EPL rupture after distal radius volar plate fixation. Clin Orthop Relat Res 2006;451 : 218–222[CrossRef][Medline]
  10. Al-Rashid M, Theivendran K, Craigen MA. Delayed ruptures of the extensor tendon secondary to the use of volar locking compression plates for distal radial fractures. J Bone Joint Surg Br2006; 88:1610 –1612[CrossRef][Medline]
  11. Arora R, Lutz M, Hennerbichler A, Krappinger D, Espen D, Gabl M. Complications following internal fixation of unstable distal radius fracture with a palmar locking-plate. J Orthop Trauma2007; 21:316 –322[CrossRef][Medline]
  12. Failla JM, Koniuch MP, Moed BR. Extensor pollicis longus rupture at the tip of a prominent fixation screw: report of three cases. J Hand Surg Am 1993; 18:648 –651[CrossRef][Medline]

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