MR imaging of overuse injuries of the Achilles tendon

OBJECTIVE: This study was conducted to illustrate and classify the abnormalities found on high-resolution MR imaging of symptomatic Achilles tendons in athletic adult patients. SUBJECTS AND METHODS: One hundred patients with 118 painful Achilles tendons were imaged with a 1.5-T magnet. The tendon, peritendinous tissues, tendon insertion, and musculotendinous junction were examined on MR imaging. Twenty-eight patients underwent surgery, and histopathologic samples were taken in 13. Long-term follow-up was performed, on average, 3.4 years after MR imaging. RESULTS: Of 118 painful Achilles tendons, abnormalities were detected in 111. These were in the tendon (n = 90), surrounding structures, or both. Fifty-four tendons had a focal area of increased intratendinous signal, best detected on axial high-resolution T1-weighted gradient-echo MR imaging. Histopathology confirmed abnormal tendon structure. Of the 21 surgically proven foci of tendinosis, 20 were revealed on MR imaging. At the level of the insertion, changes were found in the tendon in 15%, in the retrocalcaneal bursa in 19%, and in the calcaneal bone marrow in 8% of the studies. Abnormalities in peritendinous soft tissues were detected in 67%. More than one type of abnormality was found in 64% of the studies. CONCLUSION: Lesions in the Achilles tendon and in the peritendinous structures can have similar clinical presentation. MR imaging detects and characterizes these changes. A more specific diagnosis and prognosis can be made with the use of MR imaging than with clinical examination alone.     

Achilles tendon: MR imaging at 1.5 T

Thirty magnetic resonance (MR) examinations of the Achilles tendon were performed: 20 from patients without suspected tendon abnormalities; ten from patients with suspected tendon abnormalities. The appearance of the normal Achilles tendon is hypointense and flattened. Partial tears appeared as high-signal intratendinous collections, complete acute ruptures appeared as tendinous discontinuity, and uncomplicated surgical repairs appeared as areas of tendinous continuity with inhomogeneous signal in the operative site. Chronic tendinitis appeared as a diffuse thickening of the tendon. MR imaging of the Achilles tendon at 1.5 T enabled the determination of the degree of tendinous continuity, which may help with diagnosis, treatment, and the pacing of rehabilitation.     

Contrast-enhanced magic-angle MR imaging of the Achilles tendon

OBJECTIVE: The objective of this study was to image the Achilles tendon with MR imaging at the magic angle (the long axis of the tendon at 55 degrees relative to the direction of the main static magnetic field [B(0)]) to detect signal from the tendon, to measure the T1 of the tendon, and to determine patterns of contrast enhancement in control subjects and patients. CONCLUSION: Mean T1 values of 311 +/- 30 msec (at 1.0 T) were found in six volunteers. In six control volunteers, slow uptake of contrast material that dispersed over 40 min-1.5 hr was shown without focal change, with elimination in most cases occurring within 18-24 hr. Small rapidly enhancing focal areas of enhancement were seen next to the insertion of the tendon and centrally within 5-10 min in two control volunteers. The focal areas were located at the sites of the blood supply. A patient with chronic tendinopathy showed early local contrast enhancement that extended widely within the tendon over several hours. Two patients with a partially ruptured or repaired tendon showed marked rapid contrast enhancement. The enhancement was obvious with the tendon at the magic angle but was not evident with the tendon in the usual orientation for MR examinations parallel to B(0).     

外伤性跟腱撕裂的MRI诊断

目的：评价磁共振(MRI)对外伤性跟腱撕裂的诊断价值。方法：收集经删检查并由手术证实的外伤性跟腱撕裂患者10例，回顾、分析其MRI表现。结果：10例患者均诊断正确(敏感性100％，特异性100％)。其中完全性撕裂8例，不完全性撕裂2例；撕裂发生在跟腱中上段2例、跟腱中段7例、跟腱下段1例；MRI主要表现为肌腱增粗10例，肌腱内信号增高10例，宽径／前后径比值缩小8例，肌腱连续性中断9例，断端分离、肌腱缩短3例。跟腱周围软组织肿胀及积液9例。结论：MRI能够直接显示跟腱的形态及其内部结构．对跟腱撕裂的术前诊断具有很高的敏感件和特异性．     

High-resolution MR imaging of the asymptomatic Achilles tendon: new observations.

OBJECTIVE: Our aim was to describe the normal appearance of the Achilles tendon and peritendinous tissues in asymptomatic active volunteers using high-resolution MR imaging. MATERIALS AND METHODS: One hundred clinically asymptomatic Achilles tendons were imaged at 1.5 T with axial high-resolution T1-weighted gradient-echo (fast low-angle shot [FLASH]) and short inversion time inversion recovery (STIR) sequences. The tendons, peritendinous tissues, tendon insertions, and musculotendinous junctions were separately evaluated by two observers. RESULTS: The average anteroposterior diameter (+/-SD) of the asymptomatic Achilles tendons was 5.2+/-0.73 mm. The anterior margin was flat or concave in all, except for 10 tendons that showed mild convexity. A wave-like bulge, which shifted from lateral to medial in the craniocaudal direction, was detected in the anterior margin of 56 tendons. The signal intensity was heterogeneous in 45 tendons. In these tendons, distal stripes or punctate foci were seen. A small (3 mm) intermediate intensity intratendinous region thought to represent tendon degeneration was detected in four cases on FLASH images. The retrocalcaneal bursae contained a prominent fluid collection in 15 cases. The paratenon was visualized in all cases on both FLASH and STIR images. CONCLUSION: High-resolution MR imaging depicts the Achilles tendon and peritendinous soft tissues in great detail. The normal anatomy of the asymptomatic Achilles tendon is variable. We postulate that the variability may be a potential source of diagnostic misinterpretation.     

Achilles tendon imaging

The Achilles tendon is the largest and strongest tendon in the body, yet one of the most commonly injured. Tendon degeneration is a relatively common disorder, predisposing to tears and often associated with paratenonitis. Numerous other diseases involve the Achilles tendon, some with classic imaging appearances, others with non-specific appearances. The aim of this pictorial essay is to review the radiographic, computed tomographic, ultrasonographic and MR appearances of the normal and diseased Achilles tendon.     

Achilles tendon overuse injuries.

Overuse injuries of the Achilles tendon are common in patients engaging in recreational athletics. Achilles tendon overuse injuries exist as a spectrum of diseases ranging from inflammation of the paratendinous tissue (paratenonitis), to structural degeneration of the tendon (tendinosis), and finally tendon rupture. Factors known to predispose patients to Achilles tendinitis include inadequate stretching, training errors, mechanical malalignment of the lower extremities, rigid training surfaces, and occasionally systemic disease. Treatment of the patient with paratenonitis and tendinosis is initially conservative, emphasizing passive stretching, concentric and eccentric strengthening, correction of training errors, and restoration of normal limb alignment. Patients resistant to this protocol often exhibit a more advanced degree of tendon change. A high percentage of these patients can benefit from surgical debridement of the involved tendon, and they can anticipate successful return to recreational athletics. Steroid injections should not be routinely used in patients with Achilles tendinitis. Rupture of the Achilles tendon following intratendinous injection has been reported.     

MR imaging of the Achilles tendon: overlap of findings in symptomatic and asymptomatic individuals

Objective: To differentiate MR imaging characteristics of symptomatic as compared with asymptomatic Achilles tendons. Design: 1.5 T MR images of 94 feet (88 patients) with ”abnormal” MR examinations were retrospectively evaluated and clinically correlated. Two masked, independent observers systematically evaluated for intratendon T2 signal, tendon thickness, presence of peritendonitis, retrocalcaneal bursal fluid volume, pre-Achilles edema, bone marrow edema at the Achilles insertion, and tears (interstitial, partial, complete). These findings were correlated with symptoms (onset and duration) and physical examination results (tenderness, palpable defects, increased angle of resting dorsiflexion). Results: Of the 94 ankles, 64 ankles (32 females, 29 males) were clinically symptomatic. No relationship between Achilles tendon disorders and age or gender was identified. Asymptomatic Achilles tendons frequently demonstrated mild increased intratendon signal (21/30), 0.747 cm average tendon thickness, peritendonitis (11/30), pre-Achilles edema (12/30), and 0.104 ml average retrocalcaneal bursal fluid volume. Symptomatic patients had thicker tendons (0.877 cm), greater retrocalcaneal fluid volume (0.278 ml), more frequent tears (23/64), a similar frequency of peritendonitis (22/64) but less frequent pre-Achilles edema (18/64). Sixty-four percent of the Achilles tendon tears were interstitial. Except for two interstitial tears in control patients, the majority of Achilles tears were in symptomatic patients (14/16). Only symptomatic tendons demonstrated partial or complete tendon tears. In addition, calcaneal edema was found almost exclusively in actively symptomatic patients. Thicker tendons were associated more often with chronic symptoms and with tears. When present in symptomatic patients, peritendonitis was usually associated with acute symptoms. The presence of pre-Achilles edema, however, did not distinguish acute from chronic disorders. Conclusion: There is significant overlap of MR findings in symptomatic and asymptomatic Achilles tendons. Furthermore, there is apparently a spectrum of disease in symptomatic tendons ranging from subtle intratendinous and peritendinous signal to partial and complete tendon tear. Received: 17 March 2000 Revision requested: 26 May 2000 Revision received: 19 July 2000 Accepted: 19 July 2000     

MR imaging of ligament and tendon injuries of the fingers.

Magnetic resonance (MR) imaging can provide important information for diagnosis and evaluation of soft-tissue trauma in the fingers. An optimal imaging technique should include proper positioning, dedicated surface coils, and specific protocols for the suspected abnormalities. Familiarity with the fine anatomy of the normal finger is crucial for identifying pathologic entities. MR imaging is a powerful method for evaluating acute and chronic lesions of the stabilizing articular elements (volar plate and collateral ligaments) of the fingers and thumbs, particularly in the frequently affected proximal interphalangeal and metacarpophalangeal joints. As in other body regions, MR imaging is also useful for depicting traumatic conditions of the extensor and flexor tendons, including injuries to the pulley system. In general, normal ligaments and tendons have low signal intensity on MR images, whereas disruption manifests as increased signal intensity. Radiologists need to understand the full spectrum of finger abnormalities and associated MR imaging findings.     

腘肌及胭肌腱损伤的MR诊断

目的 回顾性分析胭肌及胭肌腱损伤的MR表现,了解其影像学特征,提高诊断和鉴别诊断水平,减少误诊率.方法 患者共26例,均行膝关节外旋15°的矢状位快速自旋回波T1WI序列、矢状位脂肪抑制STIR序列和冠状位自旋回波T2 WI及质子相双回波序列扫描.结果 26例患者中,单纯胭肌损伤为11例,胭肌腱损伤5例,胭肌及腘肌腱同时损伤者为10例.胭肌及腘肌腱的损伤,以矢状位脂肪抑制STIR序列及冠状位自旋回波T2WI序列显示病变最为清楚,可显示胭肌急慢性损伤水肿所致的长T2高信号,同时可显示胭肌腱撕裂所致的连续性中断.轴位快速自旋回波T2加权序列也可清楚显示胭肌损伤所致信号异常.结论 MR成像是显示胭肌及胭肌腱损伤最佳的影像学手段,通过常规方位扫描图像可做出准确的诊断.     

Repair of Achilles tendon ruptures with a polylactic acid implant: assessment with MR imaging

An investigational tendon repair device composed of a polymer of lactic acid (PLA) is currently undergoing multicenter clinical trials for use in repairing rupture of the Achilles tendon. The advantages of the PLA device include high tensile strength and the induction of a rapid proliferative tissue response resulting in a shorter rehabilitation period than with conventional surgical repair. We reviewed 16 MR examinations performed in 10 patients 3-35 months after repair to characterize the MR appearance. All 16 T1-weighted sagittal images revealed a thickened fusiform tendon with streaks of moderate signal within the tendon corresponding to the PLA device and its surrounding collagenogenic response. The double-echo T2-weighted axial images at the mid tendon level demonstrated progressive changes in the signal pattern of the central portion of the tendon that reflected the maturation of the healing tendon. All tendons repaired with PLA implants were uniformly hypertrophied relative to the contralateral normal side because of the induced proliferative collagenogenic ingrowth. Two follow-up MR examinations were performed in six patients and showed mean reductions in tendon caliber of 24% and 30% at the mid and inferior levels. MR imaging of the Achilles tendon repaired with PLA implants shows a diffusely thickened tendon with streaks of signal within the tendon that distinguish it from tendons repaired by conventional techniques.     

Magnetic resonance imaging of Achilles tendon ruptures

Preoperative magnetic resonance images of three acute Achilles tendon ruptures were correlated with the findings observed during surgical repair of the tendon. Specific comparisons were made regarding the condition (shredded, uniform, etc.) and orientation (antegrade, retrograde, etc.) of the torn fibers, and the width of the diastasis (with and without ankle flexion) between the ends of the tendon. Magnetic resonance imaging (MRI) accurately assessed all of these parameters.     

Ossification of the Achilles tendon: imaging abnormalities in 12 patients

Ossification of the Achilles tendon is a rare clinical entity that is characterized by the presence of an ossific mass contained within the fibrocartilaginous substance of the tendon. Because the radiographic features of this condition have not been documented entirely and the magnetic resonance (MR) imaging findings have not been determined, a review of 16 affected tendons in 12 patients was performed in an attempt to characterize the imaging abnormalities associated with this process. MR imaging was performed in three Achilles tendons which demonstrated thickening of the tendons at the level of the ossifications and a lack of intratendinous signal abnormalities compatible with acute tendinitis. Signal intensity similar to that of bone marrow was present in the ossifications.     

Avoiding sural nerve injuries during percutaneous Achilles tendon repair

BACKGROUND: Sural nerve injury is a reported risk during percutaneous repair of the Achilles tendon. HYPOTHESIS: Exposure of the sural nerve during percutaneous repair can minimize the risk of nerve injury. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: The authors retrospectively examined the results of 84 patients who were treated for acute Achilles tendon rupture at 2 different hospitals. Both hospitals used the same percutaneous repair technique, except that the sural nerve was exposed in the 38 patients (mean age, 38 years; range, 23-68 years) of one hospital; the nerve was not exposed in the 46 patients (mean age, 42 years; range, 24-71 years) of the other hospital (the nonexposure group). RESULTS: All patients recovered and returned to work after 44 days (range, 5-202 days). All patients returned to their previous sports levels within 1 year. On the 100-point Hannover Achilles Tendon Score, the mean score was 81 points (range, 44-100 points). The overall incidence of sural nerve related complications was 18%. All sural nerve lesions occurred in the nonexposure group. In the total study population, there were 3 cases of deep vein thrombosis, 1 rerupture, and 1 case of infection. CONCLUSION: Sural nerve injuries can be minimized during surgery by carefully placing the stab incisions to expose the nerve so as to avoid it during repair. If the sural nerve is exposed, percutaneous repair of the ruptured Achilles tendon is a safe and reliable method of treating Achilles tendon ruptures.     

Knee injuries: high-resolution MR imaging

Recent technologic advances have made high-resolution magnetic resonance (MR) imaging of the knee a clinical reality. Ten healthy volunteers and 30 patients with suspected knee injuries were imaged using receive-only surface coils and two-dimensional multisection or three-dimensional selective acquisition techniques. Arthroscopic and/or surgical correlation was available in 15 patients. Tears of the cruciate ligament, medial collateral ligament, and meniscus are illustrated. Nonorthogonal views of the anterior cruciate ligament are useful for demonstrating both femoral and tibial attachments in the same section. The posterior cruciate ligament is usually well seen on sagittal views. T2-weighted images are helpful for demonstrating collateral ligament tears and meniscal tears when joint effusion is present. Thin sections (1-5 mm) are necessary to define many meniscal and cruciate tears. High-resolution, thin-section MR imaging can be used to diagnose soft-tissue injuries of the knee and has the potential to become a major imaging method in the evaluation of knee injuries.     

Avulsion fractures and chronic avulsion injuries of the knee: role of MR imaging

Avulsion fractures and chronic avulsion injuries of the knee are common lesions in sports-related trauma, especially among adolescents. Magnetic resonance imaging may prove useful in detecting and characterizing such lesions, and has several advantages with regard to other imaging modalities. We review, illustrate, and discuss the MR imaging features of some of the more frequent avulsion fractures and chronic avulsion injuries of the knee, including avulsion fractures of the cruciate ligaments, avulsion fractures of lateral and medial stabilizers, avulsion fractures and chronic avulsion injuries of the extensor mechanism, and avulsive cortical irregularities of the distal femur. The role of MR imaging in evaluating such lesions is emphasized.     

High-field and low-field MR imaging of superior glenoid labral tears and associated tendon injuries

OBJECTIVE: The purpose of this study was to determine the performance characteristics of high-field and low-field MR imaging for the diagnosis of a glenoid superior labral anteroposterior (SLAP) tear. MATERIALS AND METHODS: High-field (n = 46) or low-field (n = 21) MR imaging was performed on 41 patients with SLAP tears and 26 patients with normal superior labra. The superior labrum was classified into one of four types on the basis of patterns of intralabral signal intensity. The relative frequency of rotator cuff tears and long head of the biceps tendinopathy was also assessed. RESULTS: For the diagnosis of SLAP tear, the sensitivity of high-field MR imaging was 90% (95% confidence interval = 74%, 98%), specificity was 63% (35%, 85%), and accuracy was 80% (66%, 91%). The sensitivity of low-field MR imaging was 64% (31%, 89%), specificity was 70% (35%, 93%), and accuracy was 67% (43%, 85%). A branched linear or stellate focus of abnormal intralabral signal intensity was associated with a SLAP tear in 86% of patients. Conversely, two other labral patterns correlated with a normal superior labrum in 71% of patients. Abnormal signal intensity in the biceps tendon was seen in 15% of patients with a SLAP tear. Full-thickness (37%) and partial-thickness (31%) rotator cuff tears were often seen. CONCLUSION: The performance characteristics of high-field MR imaging are superior to those of low-field MR imaging for the diagnosis of a superior labral tear. Rotator cuff tears can be seen in many patients with superior labral tears, but abnormal signal intensity in the biceps tendon is uncommon.