Ultrasonic examination of the flexor tendons of the fingers

Comparative Sensitivity and Specificity of Static and Dynamic High-Resolution Ultrasound in Diagnosis of Small Gaps in Repaired Flexor Tendons: A Cadaveric Study

PURPOSE

To compare the sensitivity and specificity of high-resolution static and dynamic ultrasound (US) for diagnosing intact repairs and small, clinically relevant gaps (≥4 mm) in repaired flexor digitorum profundus tendons within zone 2 and, secondarily, to evaluate the effect of suture artifact from 3 commonly used suture types.

METHODS

Eighty-eight fresh-frozen cadaveric digits (thumbs excluded) were randomized to either an intact repair (0-mm gap) or repairs using a locked 4-strand suture repair with either 4-0 Prolene, Ethibond, or FiberWire and gaps of 2, 4, or 6 mm and no suture in which 2-, 4-, or 6-mm gaps were created without a suture crossing the repair site. Gap widths were estimated by a blinded musculoskeletal ultrasonographer in static and dynamic modes.

RESULTS

Both static and dynamic modalities tended to overestimate actual gap sizes. For the suture gaps, both modalities had poor sensitivity (29% static; 42% dynamic) for accurately diagnosing a clinically intact repair (<4 mm), but better specificity (83% static; 75% dynamic) for diagnosing a clinically failed repair (≥4-mm gap). Although suture presence decreased the sensitivity of gap width measurement for both modalities, no differences were seen between suture types.

CONCLUSIONS

Static and dynamic US have poor sensitivity for diagnosing clinically intact repairs (gaps < 4 mm) because they typically overestimate gap size. The ability to diagnose failed repairs (gap ≥ 4 mm), based on greater specificity, is much better, but still suboptimal.

CLINICAL RELEVANCE

Based on a receiver operating characteristic analysis cutoff of 5 mm, if a gap of 5 mm or larger is identified with US when evaluating a zone 2 flexor digitorum profundus tendon repair, a failed repair is likely in about 80% of cases. A gap measurement of less than 5 mm may miss a high percentage of repairs that are clinically failed.

Closed rupture of flexor digitorum profundus in zone III

Closed ruptures of the flexor digitorum profundus (FDP) tendon cause a loss of active flexion at the distal interphalangeal joint. Commonly referred to as a 'jersey finger' because of its association with tackling sports, the distal aspect of FDP is avulsed from its insertion on the distal phalanx in zone I, with or without a fragment of bone. Because of this classic injury mechanism and pattern, providers may not seek advanced imaging beyond plain radiographs. Although rare, injury to FDP more proximally may occur. More often this injury is associated with a weak underlying tendon because of repetitive microtrauma or anomalous anatomy, for example. We present a case of a closed rupture of the FDP in zone III, and stress the importance of maintaining a high clinical suspicion and the potential use of adjunct ultrasound imaging to localise the site of injury.

Ultrasound localization of lacerated flexor tendon ends in the hand: a cadaveric study

OBJECTIVE

Flexor tendon repair currently requires extensive exposure to locate and repair tendons. Ultrasound (US) has been used to identify lacerated tendon ends with little information on accuracy. This study was designed to measure the accuracy of US to localize tendon ends in zone II flexor tendon lacerations in a cadaveric model.

MATERIALS AND METHODS

US was used to locate tendon ends in zone II lacerations of fingers of six cadaveric hands (96 tendon ends) by a musculoskeletal radiologist. The distance of each tendon end relative to the laceration was recorded. Specimens were dissected and tendon position was compared to US position.

RESULTS

The radiologist correctly identified full-thickness lacerations of both superficial and deep tendons 99.0% (n = 05/96 tendons) of the time. The average difference between mean US predicted retraction and anatomic confirmed retraction for all digits all tendons was 3.5 mm of underestimation. US correctly identified the position of all tendon stumps to within 10 mm 92.7% (n = 89/96 tendons) of the time and 69.8% (n = 67/96 tendons) of the time to within 5 mm. Error tended to underestimate (61.5%; 59/96 tendons) rather than overestimate retraction (29.2%; 28/96 tendons).

CONCLUSIONS

This fresh cadaveric study has demonstrated that with an experienced radiologist, there was 99.0% accuracy identifying a completed tendon tear and locating the tendon ends with US to within 1 cm was 92.7% accurate.

Ultrasonography of the Hand in Rheumatoid Arthritis

High resolution ultrasonography of the hand and wrist was performed on 20 patients with definite or probable rheumatoid arthritis (ARA standard criteria) in its early stage. In all the patients, swelling of the soft tissues of the fingers corresponded to an enlargement of the joint capsule containing a hypoechoic exudate. The rheumatoid nodules appeared as fluid-filled rounded cavities with sharp borders. Rheumatoid tenosynovitis was observed in 18/20 patients. This corresponded to oval or spindle-shaped cavities with a hypoechoic (10/18 cases) or anechoic content (8/18 cases) and with the tendon ribbon inside. Rupture of a tendon was diagnosed in 8/20 cases and it was always confirmed at surgery. Tenosynovitis of the flexor carpi ulnaris at the wrist level was observed in 10/20 patients. Ultrasonography is proposed as an effective first-line approach and as a periodical follow-up survey in early stage rheumatoid arthritis, in combination with standard radiography.

US Diagnosis of UCL Tears of the Thumb and Stener Lesions: Technique, Pattern-based Approach, and Differential Diagnosis

The thumb is a central component supporting the intricate movements of the hand. Patients with acute thumb pain, particularly after trauma, require prompt evaluation of structural integrity, thus avoiding long-term morbidity such as instability, chronic pain, and osteoarthritis. Injury to the ulnar collateral ligament (UCL) of the thumb requires imaging for diagnosis of surgically important entities such as the Stener lesion. Historically, routine radiography including stress views does not allow such diagnosis and is potentially detrimental to patient care. Both magnetic resonance imaging and ultrasonography (US) are currently used for direct evaluation of the UCL of the thumb and are safe and accurate. US is more dynamic and less time-consuming and may be easier to perform. Furthermore, other disorders such as tenosynovitis, tendon tears, and articular pathologic conditions can involve the thumb and thenar region and may also be diagnosed with US. In this context, US is an underused tool because it is potentially an adjunct to the clinical examination in the appropriate setting. A sound knowledge of the regional anatomy and basic training in the principles of US should equip the imager with the skills necessary to evaluate the UCL of the thumb and its surrounding structures.

Magnetic resonance imaging of the upper extremity: advances in technique and application

Vast advances in technology have taken place in the field of radiology led by the introduction of magnetic resonance imaging. The added advantages of exquisite soft tissue contrast and multiplanar imaging capabilities have revolutionized the understanding of complex anatomic relationships and diagnoses. The current authors will focus on the introduction of new advances in magnetic resonance imaging of the upper extremity that may prove helpful in the diagnosis and treatment of upper extremity abnormalities.

Pulley system in the fingers: normal anatomy and simulated lesions in cadavers at MR imaging, CT, and US with and without contrast material distention of the tendon sheath

PURPOSE

To describe the normal anatomy of the finger flexor tendon pulley system, with anatomic correlation, and to define criteria to diagnose pulley abnormalities with different imaging modalities.

MATERIALS AND METHODS

Three groups of cadaveric fingers underwent computed tomography (CT), magnetic resonance (MR) imaging, and ultrasonography (US). The normal anatomy of the pulley system was studied at extension and flexion without and with MR tenography. Pulley lengths were measured, and anatomic correlation was performed. Pulley lesions were created and studied at flexion, extension, and forced flexion. Two radiologists reviewed the studies in blinded fashion.

RESULTS

MR imaging demonstrated A2 (proximal phalanx) and A4 (middle phalanx) pulleys in 12 (100%) of 12 cases, without and with tenography. MR tenography showed the A3 (proximal interphalangeal) and A5 (distal interphalangeal) pulleys in 10 (83%) and nine (75%) cases, respectively. US showed the A2 pulley in all cases and the A4 pulley in eight (67%). CT did not allow direct pulley visualization. No significant differences in pulley lengths were measured at MR, US, or pathologic examination (P: =.512). Direct lesion diagnosis was possible with MR imaging and US in 79%-100% of cases, depending on lesion type. Indirect diagnosis was successful with all methods with forced flexion.

CONCLUSION

MR imaging and US provide means of direct finger pulley system evaluation.

Diagnostic ultrasound of the hand and wrist

To assess the efficacy, role, and limitations of diagnostic ultrasound in the hand and wrist, the results of 98 examinations performed for a variety of surgical conditions were retrospectively analyzed. Ultrasound was shown to be reliable in evaluating radiolucent foreign body, tendon rupture versus tendon adhesion, tendinitis, peritendinitis, and ganglion cyst (specificity, 1; positive predictive value, 1). A correct suggestion of soft tissue mass histology was offered in six of eight operated cases. Tumor size and extent was accurately assessed in all but one case. The observed limitation of ultrasound was a small false negative rate in each category, which related to a variety of factors, including operator dependence, resolution threshold in the submillimeter range, image degradation due to postoperative edema, a narrow field of view, and one instance of indiscrete tumor margination. More work is needed to determine the role (if any) of ultrasound in the evaluation of peripheral nerve, triangular fibrocartilage, dorsal carpal ligament, and bone pathology.

The role of ultrasound in the management of zone 1 flexor tendon injuries

We have reviewed 22 flexor tendon repairs in zone 1 undertaken in Hobart, Tasmania, during the period 1986 to 1991. The repairs were assessed using both ultrasound and Strickland's clinical criteria. The results are presented, and the two methods of assessment compared. A new method of grading results is proposed based on the ultrasound findings. We have demonstrated that ultrasound has an important role to play in assessing tendon repairs, both in the on-going management and as an objective method of measuring the results of repair.

Closed flexor tendon rupture in the palm: an unusual but predictable clinical entity

Closed intratendinous ruptures of flexor tendons are uncommon. Two such cases that occurred within the lumbrical origin are reported. Accurate history taking and clinical examination usually enable the site of rupture to be determined. Ultrasound examination can also help to localize the site. The role of the lumbrical, extrinsic flexors and trauma in the aetiology of the rupture are discussed.

Hide and seek: pre-operative ultrasonic localization of non radio-opaque foreign bodies

Ultrasound has long been used as a diagnostic and therapeutic tool in surgery. We have extended its use to hand surgery, where is has several applications. Non radio-opaque foreign body extraction is invariably a frustrating exercise of 'hide and seek'. Accurate pre-operative localization with ultrasound illustrating size, shape, depth, soft tissue and bony relationships can ensure rapid and complete removal. Several cases are presented to demonstrate the use of ultrasound for the detection of non radio-opaque foreign bodies. The technique used will be described. We feel pre-operative localization by ultrasound is a useful technique to assist with the removal of non radio-opaque foreign bodies.

Ultrasonography of the elbow joint

The nonechogenic space between the bone and the joint capsule was measured in ultrasonographic scans at six different sites in 60 elbow joints of 30 healthy adults as well as in 35 joints with clinical arthritis. The space could be demonstrated in all healthy joints on the volar side at the levels of the trochlea and the capitulum of the humerus. The space was more than 2 mm in three out of the 60 healthy joints at these levels, and the space did not increase in 30 degrees flexion of the joint. The means of the measurements were significantly higher at all six sites in the arthritic joints than in the healthy joints and on the volar site the space increased in 30 degrees flexion of the arthritic joint. The space was more than 2 mm in all arthritic joints at the levels of either the trochlea or the capitulum of the humerus. An ultrasonographic distance of more than 2 mm on the volar side of the elbow joint between the joint capsule and the bone is with high probability a sign of intraarticular effusion or synovitis. The effusion in the olecranon fossa can also be demonstrated in all cases.

Quantitative Sonographic Assessment of Scoliosis and Its Correlation with Radiographic Findings

Scoliosis is a common problem primarily affecting children. The purpose of this pilot study was to develop and test a technique to identify whether sonography can assess the lateral deviation and rotation occurring in scoliosis. If so, then it could become the diagnostic modality of choice for serial follow-up of these patients after the baseline x-ray, thus decreasing radiation exposure. Five subjects (7 to 30 years old) were scanned with real-time and static equipment. Lateral deviation could be mapped, but it was underestimated sonographically. A new finding was that the depth of soft tissue muscle mass on either side of the apical spinous process was essentially symmetrical, indicating virtually no vertebral rotation with respect to the skin. These results warrant further investigation. With a larger sample and refinements in technique, sonography may prove to be a potential tool in the management of scoliosis.