The oblique popliteal ligament: an anatomic and MRI investigation.

PURPOSE: Despite being the largest ligament on the posterior aspect of the knee, relatively little is known about the normal morphology of the oblique popliteal ligament (OPL). The aim of this study was to investigate the detailed anatomy of the OPL in cadavers and healthy volunteers. METHODS: The posterior knee was investigated in 25 cadaver lower limbs (mean age 76 ± 9.5 years; 7 men) by dissection, histology, and serial plastination and in 14 healthy individuals (mean age 23 ± 3.2 years; 11 men) using magnetic resonance (MR) imaging. OPL morphology, attachments sites, ligament length and width, relationship to surrounding structures and histological composition were recorded. Intraobserver reliability was assessed using intraclass correlation coefficients. RESULTS: The OPL is a distinct expansion of the semimembranosus (SM) tendon and sheath, which courses superolaterally to attach to the posterolateral joint capsule or fabella (when present), at the medial margin of the lateral femoral condyle. The ligament blends with the joint capsule medially and laterally, serves as an attachment site for plantaris, and has connections with popliteus. In 70% of dissections, the OPL divided into two bands, separated by small branches of the middle genicular neurovascular bundle that pierced the posterior joint capsule. Differences in mediolateral length were noted between dissection and MR imaging (43.6 ± 6.2 vs. 57.6 ± 4.4 mm; p < 0.001). At its medial and lateral attachments, the OPL was 23.2 ± 6.9 and 17.4 ± 8.7 mm wide (proximodistal), respectively. The OPL was predominantly composed of transverse collagen layers, with little elastin. While visible on axial MR scans, delineation of its most lateral extent was difficult. Repeatability of selected measurements ranged from good to almost perfect. CONCLUSIONS: The OPL is a distinct ligament with identifiable anatomical limits. Based on its morphological characteristics, it appears more tendinous than ligamentous in nature. A better understanding of the OPL may help define its importance in the assessment and treatment of posterior knee injuries.

Reliability tests and guidelines for B-mode ultrasound assessment of central adiposity.

INTRODUCTION: Ultrasound represents a validated and relatively inexpensive diagnostic device for assessing central adiposity; however, widespread adoption has been impeded by the lack of reliable standard operating procedures. PURPOSE: To examine the reliability of, and describe guidelines for, ultrasound-derived recording of intra-abdominal fat thickness (IAT) and maximal preperitoneal fat thickness (PFT). METHODS: Ultrasound scans were obtained from 20 adults (50% female, 26 ± 7 years, 24·5 kg/m(2) ) on three different mornings. IAT was assessed 2 cm above the umbilicus (transverse plane) measuring from linea alba to: (i) anterior aorta, (ii) posterior aorta and (iii) anterior aspect of the vertebral column. PFT was measured from linea alba to visceral peritoneum in (i) sagittal and (ii) transverse planes, immediately over and inferior to the xiphi-sternum, respectively. RESULTS: For IAT, the criterion intraclass correlation coefficient (ICC) of 0·75 was exceeded for measurements to anterior aorta (0·95), posterior aorta (0·94) and vertebra (0·96). The reliability coefficient expressed as a percentage of the mean (RC%) was lowest (better) for measurement to vertebrae (9·8%). For PFT, mean thickness was comparable for sagittal (1·74 cm) and transverse (1·76 cm) planes; ICC values were also comparable for both planes (0·98 vs. 0·98, respectively), as were RC% (7·5% vs. 7·1%, respectively). CONCLUSIONS: IAT assessments to the vertebra were marginally more reliable than those to other structures. While PFT assessments were equally reliable for both measurements planes, precise probe placement was easier for the sagittal plane. Based on these findings, guidelines for the reliable measurement of central adiposity using ultrasound are presented.

Longitudinal In Vivo Ultrasound Observations of the Surgically Repaired Zone II Flexor Digitorum Profundus Tendon.

The link between the healing process and functional outcomes in the surgically repaired digital flexor tendon is poorly understood. This clinical note describes those gray-scale and power Doppler (PD) ultrasound parameters that can be used to document longitudinal change in the morphologic and dynamic properties of the surgically repaired zone II flexor digitorum profundus (FDP) tendon. The method is supported by ultrasound data obtained from three participants at five points in time post-surgically (two, four, six, 12 and 18 weeks). Longitudinal documentation of the ultrasound properties of echogenicity, defect size, tendon excursion and power Doppler signal is feasible and has the potential to explore the possible link between changes in the structural status of surgically repaired flexor tendons and associated clinical outcomes.

Revisiting the surface anatomy of the sciatic nerve in the gluteal region.

The surface anatomy of the sciatic nerve (SN) in the gluteal region is clinically important (e.g., intramuscular injection). Anatomy texts describe the nerve in relation to the posterior superior iliac spine (PSIS), ischial tuberosity (IT), and greater trochanter (GT) but descriptions are inconsistent. The surface anatomy of the SN was determined in relation to these bony landmarks using computed tomography (CT) scans in living adults. One hundred consecutive adult pelvic CT scans (36 females, mean age 76 years) were available for dual consensus analysis. A further 19 adults (9 females, mean age 74 years) underwent pelvic CT scans in both prone and supine positions. The surface projection of the SN along a line between the PSIS and IT and between the IT and GT was measured. The SN was identified in 95% of scans at a mean of 5.2 ± 1.0 cm from the PSIS and 11.4 ± 1.1 cm from the IT. The SN was a mean of 5.8 ± 0.8 cm from the IT and 6.2 ± 1.0 cm from the GT. There were no significant differences in mean positions of the nerve between sides and sexes. A small but clinically irrelevant difference in the surface marking of the SN was found between supine and prone positions with respect to the GT and IT but not in relation to the PSIS and IT. In living adults, the SN lies approximately one-third of the way along a line between the PSIS and IT and half way between the GT and IT.

Articularis genus: an anatomic and MRI study in cadavers.

BACKGROUND: The articularis genus muscle is closely associated with the anterior aspect of the knee joint and may act to elevate or retract the suprapatellar bursa. Its form and function are poorly understood. The purpose of this study was to define the morphology of the articularis genus and its relationship to the suprapatellar bursa. METHODS: The articularis genus muscle was investigated in twenty-two human lower limbs obtained from eleven donors (six men and five women; mean age at death, eighty-three years). Eighteen of these limbs underwent magnetic resonance imaging (MRI) followed by dissection. The number, length, physiological cross-sectional area, attachment sites, and orientation of individual fascicles, muscle bundles, and whole muscles were recorded. The remaining four limbs underwent immunohistochemical analysis to determine muscle fiber types. RESULTS: The articularis genus comprised multiple layered muscle bundles originating from the anterior, anterolateral, and/or anteromedial surfaces of the distal third of the femur. Distal attachment sites included the proximal and/or posterior wall of the suprapatellar bursa, the deep surface of the distal tendon of the vastus intermedius, and the medial and lateral aspects of the knee joint capsule. On dissection, the muscle was observed to consist of a mean of seven muscle bundles (range, four to ten), but only a mean of four bundles were observed on MRI scans (p < 0.0001). The mean cross-sectional area of the articularis genus (and standard deviation) was 1.5 ± 0.7 cm2, and its mean fascicular length and bundle physiological cross-sectional area were 5.9 ± 1.0 cm and 0.2 ± 0.1 cm2, respectively. The articularis genus displayed a mixed fiber type, with the proportion of type-I fibers varying among specimens (range, 39.9% to 76.4%). CONCLUSIONS: These findings highlight the complex and variable anatomy of the articularis genus, particularly with respect to the number of bundles and the distal attachment sites. Distinguishing the superficial bundles of the articularis genus from the vastus intermedius on MRI can be difficult. CLINICAL RELEVANCE: Given its relationship to the anterior aspect of the knee joint and its association with the suprapatellar bursa, the articularis genus may be a neglected cause of undifferentiated anterior knee pain.

Isolated popliteus rupture at the musculo-tendinous junction.

We report the case of a 23-year-old professional senior international rugby union player who sustained a lateral blow to his semiflexed knee during a competitive game. Initial clinical examination was unremarkable apart from some posterolateral tenderness. A magnetic resonance imaging scan showed an isolated popliteus tendon rupture at the musculo-tendinous junction. After 5 weeks of focused rehabilitation and graduated training, he was able to resume his playing career and resumed his international playing career later that season. At the time of reporting, he has completed a full domestic and international season without any sequelae from the injury. This report highlights the rarity of such an injury, especially at the musculo-tendinous junction, and sets out a detailed rehabilitation program that has enabled the patient in question to resume his playing career.

Osteitis condensans ilii: a significant association with sacroiliac joint tenderness in women.

AIM: To determine whether subjects with radiological evidence of osteitis condensans ilii exhibit symptoms and signs in common with sacroiliitis when compared with an age-matched control group and to examine demographic features. METHODS: The Dunedin Hospital radiology database was searched for all subjects with changes of osteitis condensans ilii over a 10-year period. An age-matched control group with plain X-rays of the pelvis was recruited from the same database. All subjects were sent a questionnaire enquiring about back pain and details of previous pregnancies. Those who responded to the questionnaire were invited for clinical assessment. RESULTS: Thirty-five individuals with osteitis condensans ilii were identified over the 10-year period. All were female and reported prior pregnancy supporting an association between osteitis condensans ilii and pregnancy. Stress testing of the sacroiliac joints was associated with greater tenderness in the osteitis condensans ilii group with a mean of 1.8 positive tests out of a possible 4, compared to 0.8 in the control group (Wilcoxon rank-sum test P = 0.02). Comparison between the two groups showed no difference in number of pregnancies, newborn weight, presence of back pain, back pain assessed by the Oswestry Low Back Pain Questionnaire or loss of function using the Bath Ankylosing Spondylitis Functional Index (BASFI). CONCLUSION: Osteitis condensans ilii is associated with tenderness during sacroiliac joint compression tests and should be considered in the differential diagnosis when sacroiliac joint tenderness is elicited.

Accidental human injection of Excenel RTU: ceftiofur hydrochloride in cottonseed oil.

INTRODUCTION: There is little knowledge within the medical community of the existence of veterinary antibiotics in oil-based suspensions and the adverse effects that may occur with accidental human injection. CASE REPORT: A farmer injected an unknown quantity of Excenel RTU into her right thigh. Despite early debridement she developed a deep infection and recurrent chronic inflammation in the subcutaneous tissues and muscle secondary to the cottonseed oil suspension. Radical debridement and extensive split skin grafting was required but she still has had recurrences 12 months after injury. DISCUSSION: Prompt surgical debridement should be performed as in cases of oil based veterinary vaccines. Despite being an antibiotic there is a significant risk of infection from a dirty needle following inoculation and multiple cultures should be taken and appropriate broad spectrum antibiotics used. Radical debridement and skin grafting necessitating specialist plastic surgical attention may be required.

Lateral hip pain: findings from magnetic resonance imaging and clinical examination.

STUDY DESIGN: Prospective cross-sectional study. OBJECTIVES: To examine the radiological and physical therapy diagnoses of lateral hip pain (LHP), and determine the validity of selected clinical variables for predicting gluteal tendon pathology. BACKGROUND: LHP is frequently encountered by clinicians. Further investigation is required to establish the specific pathologies implicated in the cause of LHP, and which clinical tests are useful in the assessment of this problem. METHODS AND MEASURES: Forty patients with unilateral LHP underwent a physical therapy examination followed by magnetic resonance imaging (MRI) studies. Three radiologists analyzed the images of both hips for signs of pathology. Interobserver reliability of the image analyses, the agreement between the physical therapy and radiological diagnoses, and the validity of the clinical tests were examined. RESULTS: Gluteus medius tendon pathology, bursitis, osteoarthritis and gluteal muscle atrophy (predominantly affecting gluteus minimus) were all implicated in the imaging report of LHP. While prevalent in symptomatic hips, abnormalities were also identified in asymptomatic hips, particularly relating to the diagnosis of bursitis. The strength of agreement between radiologists was variable and little agreement existed between the physical therapy and radiological diagnoses of pathology. Nine of the 26 clinical variables examined in relation to gluteal tendon pathology had likelihood ratios above 2.0 or below 0.5, but the associated 95% confidence intervals were large. CONCLUSIONS: The diagnosis of LHP is challenging and our results highlight some problems associated with the use of MRI as a diagnostic reference standard. This factor, together with the imprecise point estimates of the likelihood ratios, means that no firm conclusions can be made regarding the diagnostic utility of the clinical tests used in the assessment of gluteal tendon pathology.

Ultrasound appearance of scrotal fat necrosis in prepubertal boys.

BACKGROUND: Scrotal fat necrosis is a rare cause of scrotal pain in prepubertal boys. Despite its characteristic clinical presentation, it is an under-recognized entity. Specific scrotal US imaging features of this condition have not been previously reported. OBJECTIVE: To describe the US imaging features of scrotal fat necrosis. MATERIALS AND METHODS: Between January 1999 and November 2006 we identified all boys with idiopathic scrotal fat necrosis presenting for ultrasound imaging. All the children were reviewed by the urology service during the initial presentation and assessment with clinical confirmation of the diagnosis of scrotal fat necrosis. The sonographic appearances in each child were reviewed. RESULTS: Over the course of 6 years we identified ten children who had the classic clinical diagnosis of idiopathic scrotal fat necrosis. The scrotal fat was characteristically hyperechoic, with posterior shadowing. This was located inferior to the testes which were displaced superiorly. The testes and epididymi were normal in all children. CONCLUSION: There are specific imaging features of scrotal fat necrosis that when combined with the characteristic clinical presentation can confirm the diagnosis of scrotal fat necrosis.

STIR MRI to direct muscle biopsy in suspected idiopathic inflammatory myopathy.

Successful management of the idiopathic inflammatory myopathies requires an early and accurate diagnosis. The muscle biopsy remains the definitive test. However, false-negative biopsy results are common, as the disease is typically patchy in distribution. The advent of short tau inversion recovery sequences now allows rapid magnetic resonance imaging of the whole body to be performed, enabling identification of the muscles most suitable for biopsy. It also provides further diagnostic information through the form and anatomic distribution of the pathology. We report 2 cases illustrating the advantages of whole-body short tau inversion recovery magnetic resonance imaging before muscle biopsy. We encourage clinicians to use the technique in this context.

Patterns of injury in patients with radiographic occult fracture of neck of femur as determined by magnetic resonance imaging.

The purpose of the present study was to review retrospectively our experience with MRI in patients over the age of 50 who present to the emergency department with inability to weight bear following a fall and whose initial radiographs were normal. The study was designed to establish the incidence and pattern of bone and soft tissue injuries in these patients and to determine whether MRI could provide predictive information regarding length of hospital stay. The present study demonstrated the practicality of a protocol using MRI to obtain rapid definitive diagnosis in patients with occult fractures of the pelvic ring and neck of femur. The present study also suggests that significant prognostic information with regard to length of hospital stay can be obtained from an early MRI scan.