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PURPOSE: Dynamic four dimensional (4D) computed tomography (CT) has recently emerged as a practical method for evaluating complex functional abnormality of joints. We retrospectively analysed 4D CT studies undertaken as part of the clinical management of hand and wrist symptoms. We present our initial experience of 4D CT in the assessment of functional abnormalities of the wrist in a group of patients with mid carpal instability (MCI), specifically carpal instability non-dissociative. We aim to highlight unique features in assessment of the radius-lunate-capitate (RLC) axis which allows insight and understanding of abnormalities in function, not just morphology, which may be contributing to symptoms. MATERIALS AND METHODS: Wide field of view multi-detector CT scanner (320 slices, 0.5 mm detector thickness) was used to acquire bilateral continuous motion assessment in hand flexion and extension. A maximum z-axis coverage of 16 cm was available for each acquisition, and a large field of view (FOV) was used. Due to the volume acquisition during motion, reconstructions at multiple time points were undertaken. Dynamic and anatomically targeted multi-planar-reconstructions (MPRs) were then used to establish the kinematic functionality of the joint. RESULTS: Our initial cohort of 20 patients was reviewed. Three findings were identified which were present either in isolation or in combination. These are vacuum phenomenon, triggering of the lunate and capitate subluxation. We provide 4D CT representations of each and highlight features considered of clinical importance and their significance. We also briefly discuss how the current classifications of dynamic wrist abnormalities may alter with the supplementary information provided by dynamic 4D CT MSK acquisitions. CONCLUSION: 4D CT has provided a unique insight into motion disorders. We highlight our early experience with the ability of 4D CT to investigate the RLC axis and three signs which have provided a unique assessment of MCI. This improved assessment of wrist motion disorders has highlighted sufficient differences in the dynamic CT classifications we have described and suggests that further research may result in refinement of the MCI classification system.

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BACKGROUND: The human biceps femoris long head is susceptible to injury, especially when sprinting. The potential mechanical action of this muscle at a critical stage in the stride cycle was evaluated by calculating three-dimensional lines-of-action and moment arms about the hip and knee joints in vivo. METHODS: Axial magnetic resonance images of the right lower-limb (pelvis to proximal tibia) were recorded from four participants under two conditions: a reference pose, with the lower-limb in the anatomical position and the hamstrings relaxed; and a terminal swing pose, with the hip and knee joints flexed to mimic the lower-limb orientation during the terminal swing phase of sprinting and the hamstrings isometrically activated. Images were used to segment biceps femoris long head and the relevant bones. The musculotendon path and joint coordinate systems were defined from which lines-of-action and moment arms were computed. FINDINGS: Biceps femoris long head displayed hip extensor and adductor moment arms as well as knee flexor, abductor and external-rotator moment arms. Sagittal-plane moment arms were largest, whereas transverse-plane moment arms were smallest. Moment arms remained consistent in polarity across all participants and testing conditions, except in the transverse-plane about the hip. For the terminal swing pose compared to the reference pose, sagittal-plane moment arms for biceps femoris long head increased by 19.9% to 48.9% about the hip and 42.3% to 93.9% about the knee. INTERPRETATION: Biceps femoris long head has the potential to cause hip extension and adduction as well as knee flexion during the terminal swing phase of sprinting.

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OBJECTIVE: The purpose of this study was to describe the normal anatomy of the soleus muscle using magnetic resonance (MR) imaging, anatomic dissection and histologic correlation in cadavers. The second objective of this study was to analyse the morphometry of the soleus muscle in normal volunteers. The final objective was to undertake a retrospective review of soleal strain injuries confirmed with MR imaging, with correlation made between the cadaveric anatomic findings and the MR imaging features. MATERIALS AND METHODS: Eleven fresh cadaveric legs were studied using a high resolution 3.0 T (T) MR imaging scanner to obtain images in the axial, coronal and sagittal planes. After imaging, six specimens were dissected and evaluated by histological analysis, with the remaining five specimens then frozen and cut into axial sections. The corresponding levels on the MR examination were then compared with the levels of anatomic sectioning. MR imaging was also used to examine the soleus muscle in both legs of 20 healthy volunteers. Finally, 55 clinical cases of soleus muscle strains diagnosed between October 2006 and January 2011 that had also previously undergone MR imaging were re-evaluated. The location of strain injury was reviewed and correlated with the anatomic information that had been revealed in the anatomic component of our study. RESULTS: Dissection of the soleus muscle revealed two proximal intramuscular aponeuroses (medial and lateral) that are formed as a direct continuation of the surrounding epimysium. From an anatomic, functional and pathologic perspective, these aponeuroses are considered in this study as intramuscular tendons, however they have been not previously described as such. These tendons penetrate deep into the muscle belly, from which the proximal muscle fibres of the soleus arise. Inferiorly, these muscle fibres insert onto a long distal central tendon that becomes confluent with the overlying distal tendon of gastrocnemius to form the Achilles tendon. Significant differences between the length of the central tendon on the right side (31.35 cm) and the left side (30.36 cm) were observed (p = .002), as well as the length of insertion of this tendon onto the Achilles tendon on the right side (7.19 cm) compared with the left (7.94 cm) (p = .02). The retrospective analysis identified five sites within the soleus where strains were distributed: musculotendinous junction sites (proximal medial strains accounting for 25.5% of all injuries, proximal lateral strains accounting for 12.7% and distal central tendon strains accounting for 18.2%) and myofascial sites (anterior strains accounting for 21.8% of all injuries and posterior strains accounting for 21.8%). Strains of the proximal medial musculotendinous junction were the most common of soleal muscle injuries, comprising 56.4% of all cases. CONCLUSION: Current information on the detailed anatomy of the soleus muscle in the anatomic and radiological literature is lacking. Knowledge of this anatomy accounts for the distribution of sports-induced injuries within the soleus muscle-tendon unit and therefore assists in the accurate identification of these injuries, with possible prognostic benefit.

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The aim of this article is to provide a state-of-the-art review for treatment of acute, total proximal hamstring tendon ruptures. For total proximal hamstring tendon ruptures, early (<2-3 w) surgical refixation minimizes muscle atrophy and facilitates a somewhat predictable time course for healing and rehabilitation. A postoperative rehabilitation program is detailed that has been used by one physical therapist for the past 7 years on over 200 patients with surgical repair for total proximal hamstring tendon rupture. One re-rupture has occurred, 7 months after surgery, following the rehabilitation program described herein. The rehabilitation program, including avoidance of postoperative bracing, appears effective for total proximal hamstring ruptures. Early surgery together with a specific rehabilitation program appears to be the treatment of choice for timely and safe return to sport and an active lifestyle. Level of evidence V.

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The increased use of abdominal imaging techniques for a variety of indications has contributed to more-frequent detection of renal cell carcinoma (RCC). Ultrasonography has been used to characterize the solid versus cystic nature of renal masses. This modality has limitations, however, in further characterization of solid tumors and in staging of malignancy, although contrast-enhanced ultrasonography has shown promise. Cross-sectional imaging with multiplanar reconstruction capability via CT or MRI has become the standard-bearer in the diagnosis, staging and surveillance of renal cancers. The use of specific protocols and the exploitation of different imaging characteristics of RCC subtypes, including variations in contrast agent timing, MRI weighting and digital subtraction, have contributed to this diagnostic capability. Cystic renal masses are a special case, evaluation of which can require multiple imaging modalities. Rigorous evaluation of these lesions can provide information that is crucial to prediction of the likelihood of malignancy. Such imaging is not without risk, however, as radiation from frequent CT imaging has been implicated in the development of secondary malignancies, and contrast agents for CT and MRI can pose risks, particularly in patients with compromised renal function.

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Traumatic lesions of the hip in athletes may be clinically challenging because of the overlap in clinical presentation due to differing pathologies and the presence of multiple injuries. Imaging of the hip in the athlete has undergone a recent resurgence of interest and understanding related to the increasing accessibility and use of hip arthroscopy, which expands the treatment options available for intra-articular pathology. MR imaging and MR arthrography have a unique role in diagnosis of these pathologies, guiding the surgeon, arthroscopist, and referring clinician in their management of bony and soft tissue injury.

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BACKGROUND: Peroneal nerve is susceptible to injuries due to its anatomical course. Excessive weight loss, which reduces the fatty cushion protecting the nerve, is considered a common underlying cause of peroneal palsy. Other predisposing factors, such as prolonged postures, traumas of the region or concomitant pathologies (for example diabetes mellitus) contribute to the nerve damage. This study aims to reveal the multiple predisposing factors of peroneal nerve mononeuropathy after substantial weight loss that coexist in psychiatric patients and to make suggestions on their management. METHODS: Nine psychiatric inpatients, major depressive or schizophrenic, with foot drop underwent a complete clinical neurological and neurophysiological examination. All had excessive weight loss, which was completed in a short period of time and had not resulted from a well-balanced low-calorie diet, but was due to their psychiatric illness. Data regarding predisposing factors to peroneal nerve mononeuropathy were gathered, such as habitual leg crossing, squatting or other prolonged postures. RESULTS: The clinical examination and the neurophysiological evaluation in all patients were indicative of a focal lesion of the peroneal nerve at the fibular head. CONCLUSION: Patients with major depressive and schizophrenic disorders gather multiple predisposing factors to peroneal palsy, adequate to classify them at a high risk group. The better focus of the attendant medical and nursing staff on this condition, the early clinical and neurophysiologic evaluation and surgical interventions may enable an improved management and prognosis of these patients.

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OBJECTIVE: Groin pain in elite athletes is a common yet challenging diagnostic and management dilemma for the sports clinician, accounting for a significant proportion of athletic injuries. It is often debilitating and, if severe enough, may compromise an athlete's career. Traditionally, groin pain has been poorly understood by radiologists. CONCLUSION: A major reason groin pain has been misunderstood is the complexity of the anatomy of this region, which this article discusses in detail in an effort to inform the reader.

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Groin injuries are common in athletes who participate in sports that require twisting at the waist, sudden and sharp changes in direction, and side-to-side ambulation. Such injuries frequently lead to debilitating pain and lost playing time, and they may be difficult to diagnose. Diagnostic confusion often arises from the complex anatomy and biomechanics of the pubic symphysis region, the large number of potential sources of groin pain, and the similarity of symptoms in athletes with different types or sites of injury. Many athletes with a diagnosis of "sports hernia" or "athletic pubalgia" have a spectrum of related pathologic conditions resulting from musculotendinous injuries and subsequent instability of the pubic symphysis without any finding of inguinal hernia at physical examination. The actual causal mechanisms of athletic pubalgia are poorly understood, and imaging studies have been deemed inadequate or unhelpful for clarification. However, a large-field-of-view magnetic resonance (MR) imaging survey of the pelvis, combined with high-resolution MR imaging of the pubic symphysis, is an excellent means of assessing various causes of athletic pubalgia, providing information about the location of injury, and delineating the severity of disease. Familiarity with the pubic anatomy and with MR imaging findings in athletic pubalgia and in other confounding causes of groin pain allows accurate imaging-based diagnoses and helps in planning treatment that targets specific pathologic conditions.

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Postoperative imaging of the shoulder is challenging. This article reviews the radiologic evaluation following surgery for subacromial impingment, rotator cuff lesions and glenohumeral instability, including the common surgical procedures, the expected postoperative findings and potential complications. A specific emphasis is made on magnetic resonance imaging.

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PURPOSE: To retrospectively determine the sensitivity and specificity of magnetic resonance (MR) imaging findings in patients with clinical athletic pubalgia, with either surgical or physical examination findings as the reference standard. MATERIALS AND METHODS: Institutional review board approval was granted for this HIPAA-compliant study, and informed consent was waived. MR imaging studies in 141 patients (134 male patients, seven female patients; mean age, 30.1 years; range, 17-71 years) who had been referred to a subspecialist because of groin pain were reviewed for findings including hernia, pubic bone marrow edema, secondary cleft sign, and rectus abdominis and adductor tendon injury. MR imaging findings were compared with surgical findings for 102 patients, physical examination findings for all 141 patients, and MR imaging findings in an asymptomatic control group of 25 men (mean age, 29.8 years; range, 18-39 years). Sensitivity and specificity of MR imaging for rectus abdominis and adductor tendon injury were determined by using a chi(2) analysis, and significance of the findings was analyzed with an unpaired Student t test. Disease patterns seen at MR imaging were compared with those reported in the surgical and sports medicine literature. RESULTS: One hundred thirty-eight (98%) of 141 patients had findings at MR imaging that could cause groin pain. Compared with surgery, MR imaging had a sensitivity and specificity, respectively, of 68% and 100% for rectus abdominis tendon injury and 86% and 89% for adductor tendon injury. Injury in each of these structures was significantly more common in the patient group than in the control group (P < .001). Only two patients had hernias at surgery. At MR imaging, injury or disease could be fit into distinct groups, including osteitis pubis, adductor compartment injury, rectus abdominis tendon injury, and injury or disease remote from the pubic symphysis. Patients with injury involving the rectus abdominis insertion were most likely to go on to surgical pelvic floor repair. CONCLUSION: MR imaging depicts patterns of findings in patients with athletic pubalgia, including rectus abdominis insertional injury, thigh adductor injury, and articular diseases at the pubic symphysis (osteitis pubis).

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This case report describes a 20-year-old elite-level Australian Rules football player who suffered three unilateral hamstring injuries within a 2 month period. The first two episodes were managed conservatively. Magnetic resonance imaging following the third episode revealed full thickness disruption of the proximal musculotendinous junction of the biceps femoris long head and semitendinosus muscles and the common proximal (conjoint) tendon. The injury was subsequently surgically repaired. At 16 months following surgery, the player had successfully completed a full competitive season of elite-level Australian Rules football symptom free. Follow-up magnetic resonance imaging demonstrated the repaired tendon to be uniformly hypointense in keeping with reparative granulation tissue formation and restoration of normal muscle morphology. These findings are consistent with an intact repair. The case demonstrates that complete functional and radiological resolution is possible following surgical repair of significant hamstring musculotendinous junction tears.

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