Diagnosis and localisation of flexor tendon injuries by surgeon-performed ultrasound: A cadaveric study

Diagnosis and treatment of flexor tendon injuries of the hand: what the radiologist needs to know

This article reviews the diagnosis and treatment of flexor tendon injuries of the hand highlighting flexor tendon anatomy, important pre-operative imaging findings, surgical options, and post-operative complications. Imaging plays a key role in guiding treatment of these difficult to manage injuries. Thus, it is important for radiologists to have a sound understanding of factors important in treatment decision-making. In the pre-operative setting, accurately identifying the location of the torn proximal tendon stump in subacute and chronic injuries helps dictate whether the patient is a candidate for a primary flexor tendon repair or may require a tendon reconstruction to restore function. In the post-operative setting, the status of the repair and presence of surrounding adhesions help dictate if and when the patient will require subsequent surgery and whether that surgery will be a tenolysis, revision repair, reconstruction, or fusion.

Correlation of In-situ Hand Anatomy With Point of Care Ultrasound

The effective use of point-of-care ultrasound for the diagnosis and treatment of hand conditions is dependent upon a thorough understanding of its anatomic bases. To facilitate this understanding, in-situ cadaveric hand dissections were correlated with handheld ultrasound images in the palm focusing on key areas of clinical relevance. The palms of an embalmed cadaver were dissected, minimizing the reflection of structures whenever possible to emphasize normal relationships and tissue planes. Point-of-care ultrasound images were obtained from a living hand and correlated with related anatomy in the cadaver. Juxtaposing cadaver structures, spaces, and relationships with the associated ultrasound images, surface hand orientation, and ultrasound probe positioning, a series of images were developed as a guide to correlating in-situ anatomy with point-of-care ultrasound in the hand.

Flexor Tendons Sonography

Ultrasonography is the best examination to explore the flexor tendons anatomy and disorders from the wrist to the digit. It is the only dynamic and comparative tool easily accessible for the surgeon. Indeed, ultrasonography is always available in all the departments of your hospital. Recent innovations permit to see superficially (high-frequency probes), precisely (smaller probes), and with greater softwares for an effective Doppler mode. Ultrasonography becomes a very important help at the outpatient clinic examination. In the future it can be used in the operating room to perform miniinvasive surgery under local anesthesia to control active motion of the gliding of flexor tendons.

Role of Ultrasound in Flexor Tendon Injuries of the Hand: A New Insight

This study was aimed at validating the diagnostic accuracy of ultrasound (US) scans in pre-operative evaluation of flexor tendon injuries in the hand and to determine its value in the management of such injuries and in the prediction of patient outcome. This descriptive cross-sectional prospective study included 35 patients with penetrating trauma to the volar aspect of the hand or wrist with questionable clinical findings. They had 50 injured tendons and were candidates for exploratory surgery versus physiotherapy. They underwent pre-operative US to guide their management. Ultrasound results were compared with the operative findings as the gold standard test. Patients were followed up postoperatively, and functional outcome was assessed and correlated with pre-operative sonographic findings. Our results indicate that sonographic examination of hand tendon injury has high accuracy in diagnosing complete or partial flexor injuries, with 100% accuracy, sensitivity and specificity in diagnosing full-thickness tears as well as tenosynovitis of hand flexor tendons. Zonal II injury was the most frequent among our study population and correlated with poorest functional outcome after rehabilitation at 3 mo follow-up. US of the hand is a fast, inexpensive and potentially indispensable dynamic tool for accurate assessment of flexor tendon injuries. It provides data on the extent of injury that effectively helps both set up an appropriate operative plan and predict the patient's functional outcome post-operatively, which in turn will have a direct impact on the patient's rehabilitation plan and lifestyle. Thus, it should be a fundamental part of the management of patients with tendon injuries.

Flexor tendon injuries: Repair & Rehabilitation

Flexor tendon injuries are common and occur mostly by penetrating trauma. Suspected flexor tendon injuries require a thorough clinical assessment and often are not isolated injuries. A detailed understanding of flexor tendon anatomy and spatial relationships is essential, especially when repairing multi-tendon injuries. Principles of flexor tendon repair include a strong suture construct, minimising gap formation between tendon ends, preserving tendon blood supply and providing a smooth repair interface. Moreover, adequate exposure of the zone of injury using full-thickness skin flaps and preservation of neurovascular and pulley structures is essential. In this article an overview of contemporary management strategies is presented. Today's hand surgeons and therapists can choose from a variety of treatment options when managing these important and potentially life-changing injuries.

The Use of Point of Care Ultrasound in Hand Surgery

Point of care ultrasound (POCUS) is the use of ultrasound (US) imaging technology by non-sonographer, non-radiologist treating clinicians. Handheld US systems are increasing in popularity and becoming widely available and easily accessible to hand surgeons in clinical practice. Adapting POCUS into the repertoire of the hand surgeon can aid in the diagnosis of many common hand surgery presentations and shorten operative times. In this review, we outline the potential uses and advantages of incorporating POCUS into hand surgery practice incuding its use in emergencies such as trauma, infections, and foreign body localization, as well as elective presentations such as nerve compression, procedural guidance, and anesthesia. Finally, this review outlines the training and curriculum development required to ensure safe implementation of POCUS into a hand surgery practice.

Comparative Accuracy of 1.5T MRI, 3T MRI, and Static Ultrasound in Diagnosis of Small Gaps in Repaired Flexor Tendons: A Cadaveric Study

PURPOSE

We hypothesized that magnetic resonance imaging (MRI) would more accurately diagnose small gaps (<6 mm) after flexor tendon repair than static ultrasound (US) and that suture artifact would negatively impair accuracy.

METHODS

A laceration of the flexor digitorum profundus was created in 160 fresh-frozen cadaveric digits and 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 and gaps of 2, 4,or 6 mm; or no suture in which 2-, 4-, or 6-mm gaps were created without a suture crossing the repair site. We performed 1.5T and 3T MRI and static US studies; gap widths were estimated by radiologists blinded to suture presence and true gap widths.

RESULTS

The 1.5 and 3.0T MRI had a lower mean error than US for gap sizes 0 and 2 mm. All 3 modalities performed similarly for 4- and 6-mm gaps. Documentation of imaging artifact worsened error, and odds of seeing artifacts were 1.72 higher with MRI than with US. Suture did not worsen artifact nor impair accuracy for any of the 3 modalities. When no suture was used, all 3 modalities significantly overestimated the true gap.

CONCLUSIONS

MRI is most accurate for small gaps less than 4 mm. Although all modalities overestimated gap sizes in specimens with a 0-mm gap (intact tendon repair), mean overestimation (<2 mm) was not clinically relevant. Ultrasound overestimated 2-mm gaps (clinically intact repairs), whereas MRIs did not. We recommend MRI for evaluation of gaps after flexor tendon repair. The 1.5T has slightly better sensitivity and specificity for distinguishing clinically intact (gap < 3 mm) from clinically impaired (gap > 3 mm) repairs than the 3T.

CLINICAL RELEVANCE

Accurate diagnosis of intact repairs or small gaps (<3 mm) might prevent unnecessary exploration or allow modification of rehabilitation protocols. Diagnosis of clinically relevant gaps (3-6 mm) may allow for earlier revision surgery before significant tendon retraction and adhesions develop, possibly necessitating a staged reconstruction.

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 for the orthopaedic surgeon

The recent development of high-frequency ultrasonography transducers has provided better accuracy and improved the ability to image more superficial body structures. Ultrasonography is a widely available, inexpensive, comparative, and dynamic imaging technique that involves no radiation exposure and has no other adverse effects. Ultrasonography must always be combined with a medical history, physical examination, and radiographic assessment. What is ultrasound-assisted orthopaedic surgery? This approach consists in the use of ultrasonography by orthopaedic surgeons during patient visits and/or in the operating room. Similar to arthroscopy, ultrasonography is used as a complementary technique by physicians involved in the management of musculo-skeletal disease (e.g., radiologists, rheumatologists, and sports physicians). What knowledge of biophysics is needed to use ultrasonography? The surgeon must be familiar with the mechanisms by which the ultrasound waves are generated and received during B-mode and Doppler ultrasonography and with possible types of image artefacts. What is the procedure for examining a structure by ultrasonography? Each anatomic component must be assessed along two perpendicular planes in scanning mode. What does ultrasonography contribute during patient visits? Ultrasonography provides additional diagnostic information and helps to explain the pathological process to the patient. How does the contribution of ultrasonography vary across body sites and pathological processes? Ultrasonographic imaging is easier at some body sites than at others. Ultrasonography can provide useful information in patients with joint disease, sports injuries, osteo-articular infections, peripheral neuropathy, or tumours. What is interventional ultrasonography in orthopaedic surgery? Ultrasound-guided orthopaedic interventions include injections, aspirations, and minimally invasive surgical procedures. How can orthopaedic surgeons incorporate ultrasonography into their practice? The surgeon must purchase an ultrasound machine dedicated to the musculo-skeletal system and follow the necessary training courses.

How does a cadaver model work for testing ultrasound diagnostic capability for rheumatic-like tendon damage?

To establish whether a cadaver model can serve as an effective surrogate for the detection of tendon damage characteristic of rheumatoid arthritis (RA). In addition, we evaluated intraobserver and interobserver agreement in the grading of RA-like tendon tears shown by US, as well as the concordance between the US findings and the surgically induced lesions in the cadaver model. RA-like tendon damage was surgically induced in the tibialis anterior tendon (TAT) and tibialis posterior tendon (TPT) of ten ankle/foot fresh-frozen cadaveric specimens. Of the 20 tendons examined, six were randomly assigned a surgically induced partial tear; six a complete tear; and eight left undamaged. Three rheumatologists, experts in musculoskeletal US, assessed from 1 to 5 the quality of US imaging of the cadaveric models on a Likert scale. Tendons were then categorized as having either no damage, (0); partial tear, (1); or complete tear (2). All 20 tendons were blindly and independently evaluated twice, over two rounds, by each of the three observers. Overall, technical performance was satisfactory for all items in the two rounds (all values over 2.9 in a Likert scale 1-5). Intraobserver and interobserver agreement for US grading of tendon damage was good (mean κ values 0.62 and 0.71, respectively), with greater reliability found in the TAT than the TPT. Concordance between US findings and experimental tendon lesions was acceptable (70-100 %), again greater for the TAT than for the TPT. A cadaver model with surgically created tendon damage can be useful in evaluating US metric properties of RA tendon lesions.

Correspondence of high-frequency ultrasound and histomorphometry of healing rabbit Achilles tendon tissue

OBJECTIVES

Static and dynamic high-frequency ultrasound of healing rabbit Achilles tendons were set in relationship to histomorphometric analyses at three and six weeks post-surgery.

MATERIALS AND METHODS

Twelve New Zealand White rabbits received a clean-cut Achilles tendon laceration (the medial and lateral Musculus gastrocnemius) and were repaired with a four-strand Becker suture. Six rabbits got additionally a tight polyester urethane tube at the repair site in order to vary the adhesion extent. Tendons were analysed by static and dynamic ultrasound (control: healthy contralateral legs). The ultrasound outcome was corresponded to the tendon shape, tenocyte and tenoblast density, tenocyte and tenoblast nuclei width, collagen fibre orientation and adhesion extent.

RESULTS

The spindle-like morphology of healing tendons (ultrasound) was confirmed by the swollen epitenon (histology). Prediction of adhesion formation by dynamic ultrasound assessment was confirmed by histology (contact region to surrounding tissue). Hyperechogenic areas corresponded to acellular zones with aligned fibres and hypoechogenic zones to not yet oriented fibres and to cell-rich areas.

CONCLUSIONS

These findings add new in-depth structural knowledge to the established non-invasive analytical tool, ultrasound.

High-resolution ultrasound in the detection of silicone gel breast implant shell failure: background, in vitro studies, and early clinical results

BACKGROUND

Magnetic resonance imaging (MRI) has historically been considered the "gold standard" for imaging silicone gel breast implants and is currently recommended by the US Food and Drug Administration for device surveillance. Recent studies, however, have questioned its accuracy as the best screening test for implant failure. In addition, the high cost of MRI is a significant deterrent to follow-up, especially among asymptomatic patients. Recent advancements in ultrasound technology have led to the development of high-resolution devices with the potential to accurately image breast implants and breast tissues.

OBJECTIVES

The authors evaluate the feasibility of portable, high-resolution ultrasound (HRUS) for imaging of silicone gel breast implants and perform preliminary comparisons of HRUS to MRI in the assessment of both intact and failed implants in a clinical setting by both radiologists and plastic surgeons.

METHODS

Phase 1 was composed of in vitro and ex vivo scanning model assessments in a variety of implant models utilizing multiple HRUS hardware platforms (GE LOGIQ-9, LOGIQ-e, LOGIQ-i, and Venue-40 devices) and transducer heads (range, 8-16 MHz, mainly GE12ML transducer). In Phase 2, these technologies were applied clinically to provide imaging experience in three patients previously diagnosed with unilateral implant failure. Phase 3 was a preliminary prospective evaluation of HRUS of 29 implants in 15 consecutive patients for whom MRI and independent surgeon-performed and radiologist-performed HRUS scans were compared to subsequent surgical findings.

RESULTS

In Phase 1, all hardware models easily detected both intact and intentionally damaged shells in currently marketed fourth-generation responsive gel implants and in investigational, fifth-generation highly-cohesive gel devices. Although multiple transducers were able to detect shell failure, the 12-MHz head produced the best images at the normal clinical depth range. In Phase 2, confirmatory HRUS scans correctly identified the side of rupture and were consistent with MRI and surgical findings in all patients. In Phase 3, MRI, surgeon-performed HRUS, and radiologist-performed HRUS scans were all accurate in predicting implant shell integrity in 29 of 29 imaged breasts (100%) as confirmed at the time of surgery in both symptomatic and asymptomatic patients.

CONCLUSIONS

Preliminary results with a variety of base and transducer systems demonstrated that HRUS provides excellent visualization of current fourth- and fifth-generation silicone gel implants both in the in vitro and ex vivo scanning models. In vivo surgeon-performed HRUS accurately identified implant status and correlated with radiologist-performed HRUS, MRI, and surgical findings. An ongoing Phase 4 prospective study is under way to help define the sensitivity and specificity of HRUS technologies in the evaluation of current implant designs. However, the relative affordability, accessibility, availability, and dynamic real-time visualization provided by HRUS represent significant potential advantages of HRUS over MRI in both the screening and future diagnosis of breast implant shell failure.

Value of high frequency ultrasonography in diagnosis and surgical repair of traumatic finger tendon ruptures

OBJECTIVE

To investigate the value of high frequency ultrasonography in the diagnosis of zone 2 flexor tendon injuries.

SUBJECTS AND METHODS

Ninety-two patients (49 males and 43 females, mean age 32.6 ± 11.2 years) with zone 2 flexor tendon injuries in one or more digits were randomly divided into a study (n = 46, 95 digits) and a control group (n = 46, 90 digits). In the study group, preoperative ultrasound was performed and surgical repair was conducted based on ultrasonographic findings. Diagnosis and surgical repair of the control group was based on history of trauma and physical examination.

RESULTS

Types of ruptures (complete or partial) and the location of the distal end of the ruptured tendon diagnosed by preoperative ultrasonography were consistent with surgical findings in all cases (95/95, 100%) of the study group, whereas the concordance rate between clinically diagnosed ruptures and surgical findings was only 34.4% (31/90) in the control group (p = 0.02).

CONCLUSION

Preoperative high frequency ultrasound examination yielded excellent diagnostic accuracy for zone 2 flexor tendon injuries.

Zone 2 flexor tendon injuries: Venturing into the no man's land

Flexor tendon injuries are seen commonly yet the management protocols are still widely debated. The advances in suture techniques, better understanding of the tendon morphology and its biomechanics have resulted in better outcomes. There has been a trend toward the active mobilization protocols with development of multistrand core suture techniques. Zone 2 injuries remain an enigma for the hand surgeons even today but the outcome results have definitely improved. Biomolecular modulation of tendon repair and tissue engineering are now the upcoming fields for future research. This review article focuses on the current concepts in the management of flexor tendon injuries in zone 2.