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Purpose-To investigate immobilization-induced ventilation defects when performing hyperpolarized 3 He (H 3 He) MRI of the lung.Methods and Materials-Twelve healthy subjects underwent MRI of the lungs following inhalation of H 3 He gas at three time points: 1) immediately after having been positioned supine on the MR scanner table, 2) at 45 minutes while remaining supine, 3) and immediately thereafter after having turned prone. All image sets were reviewed in random order by three independent, blinded readers who recorded number, location and size of H 3 He ventilation defects. Scores were averaged for each time point and comparisons were made to determine change in number, location and size of ventilation defects with time and positioning of the subject in the scanner.Results-At baseline supine there were small numbers of defects in the dependent (posterior) and non-dependent (anterior) portions of the lung (p=0.625). At 45 minutes there was a significant increase in the mean number of ventilation defects/slice (VDS) for the dependent (p=0.005) and a decrease for the non-dependent lung portions (p=0.021). After subjects turned prone, mean VDS for posterior defects decreased significantly (p=0.011) while those for anterior defects increased (p=0.010). Most defects were less than 3 cm in diameter.Conclusion-It was found that immobilization of the subject for an extended period of time led to increased number of H 3 He ventilation defects in the dependent portions of the lung. Therefore, after a subject is positioned in the scanner, H 3 He MR imaging should be performed quickly to avoid the occurrence of the immobilization-induced ventilation defects, and possible overestimation of disease.

The clinical syndrome of "tennis leg" is often associated with a calf hematoma and was originally ascribed to a ruptured plantaris tendon. Recent publications have demonstrated a much higher association of myotendinous injuries of the Medial Head of the Gastrocnemius (MHG), with infrequent injuries to the plantaris, in the setting of calf hematoma. Nevertheless, a purported association between plantaris tendon rupture and calf hematoma persists in some literature and clinical discussions.Hypothesis/Purpose: The purpose of our study is to evaluate whether a hematoma or fluid collection between the soleus and MHG muscles after trauma may be caused by an isolated plantaris tendon tear.Study Design: Cross-sectional study.Methods: IRB approval was obtained for this retrospective review. An institutional radiology database search for MRI examinations of the calf performed over a ten year period returned 710 MRI examinations, 67 of which demonstrated an interfascial hematoma, fluid collection or edema between the MHG and soleus muscles. Each MRI was scrutinized by two fellowship trained musculoskeletal radiologists for integrity of the plantaris, gastrocnemius, and soleus myotendinous structures and intervening fascia. Discrepancies were resolved by consensus.Results: 62 of the 67 cases demonstrated a visible plantaris tendon and hematoma, fluid collection, or edema interposed between the soleus and MHG muscles. The plantaris was not visible and was presumed to be congenitally absent in five cases. Of the remaining 62 cases, the MHG was abnormal in 62/62 (100%) cases and the plantaris tendon was abnormal in 3/62 (4.8%) cases. Isolated injury to the MHG was observed in 59/62 (95.2%) cases; isolated injury to the plantaris tendon was not observed in any cases (0%). Conclusion:Our results demonstrate no association between a hematoma, fluid collection, or edema between the soleus and MHG muscles and a plantaris tendon tear. In concert with previous studies, our results support gastrocnemius injuries as the causative etiology of a calf hematoma in this location following acute trauma.Clinical Relevance: A hematoma interposed between the soleus and MHG muscles following acute trauma is not associated with plantaris tendon tears; this historical association should be abandoned.What is known about this subject: Medial head gastrocnemius muscle injury is more common than plantaris tendon injuries in cases of "tennis leg." What this study adds to existing knowledge: A hematoma between the soleus and MHG muscles following trauma is not attributable to isolated plantaris tendon injury. In cases of tennis leg, even when the plantaris tendon is injured, a hematoma between the soleus and MHG muscles is attributable to concurrent gastrocnemius injury.

Women with anterior cruciate ligament reconstruction report worse pain and knee‐related symptoms, and also exhibit biomechanical changes that may be related to knee osteoarthritis (OA) development. This is particularly concerning as symptom state has been previously associated with knee OA development. The purpose of this study was to compare lower extremity walking biomechanics between women (age: 21.40 ± 8.54 years) experiencing clinically significant knee‐related symptoms and women with acceptable symptoms 6 months following surgery. Twenty‐eight women with history of primary, unilateral anterior cruciate ligament reconstruction who completed a lower extremity walking biomechanics assessment 6 months following surgery were included in this analysis. Women were dichotomized as experiencing acceptable or clinically significant knee symptoms according to Knee injury and OA Outcomes Score cut‐offs described by Englund et al. Walking biomechanics were compared between women with clinically significant and acceptable symptoms using one‐way analysis of covariances for involved limb biomechanics. Biomechanical variables of interest were: peak vertical ground reaction forces (vGRFs), vGRF loading rates, knee flexion angles, knee extension moments, knee adduction angles, and knee adduction moments, and gait speed. Nearly 60% of women reported clinically significant knee symptoms 6 months postoperative. There were no statistically significant differences between symptom groups for walking biomechanics and gait speed outcomes. These findings suggest patient reported knee symptoms may not be a primary influence on walking biomechanics 6 months following anterior cruciate ligament reconstruction. Though, longitudinal assessment of changes in symptom state and walking biomechanics may be warranted as poorer walking biomechanics and symptoms are indicators of knee OA.