Delayed Union of Stress Fracture of the First Rib in a Yoga Instructor: A Case Report.

CASE: We describe the case of a 38-year-old woman, a yoga instructor, who had pain in the right shoulder and scapular region of 4 months' duration while performing yoga. Radiography and computed tomography diagnosed delayed union of a first rib stress fracture. The delayed union of stress fracture of the first rib was successfully treated with the limiting of yoga activity and low-intensity pulsed ultrasound (LIPUS). CONCLUSIONS: Physicians should be aware that even yoga posing can cause stress fractures of the first rib. LIPUS therapy may be effective for delayed union in addition to rest.

Quantitative In Situ Analysis of the Anterior Cruciate Ligament: Length, Midsubstance Cross-sectional Area, and Insertion Site Areas.

BACKGROUND: Quantification of the cross-sectional area (CSA) of the anterior cruciate ligament (ACL) in different loading conditions is important for understanding the native anatomy and thus achieving anatomic reconstruction. The ACL insertion sites are larger than the ACL midsubstance, and the isthmus (region of the smallest CSA) location may vary with the load or flexion angle. PURPOSE: To (1) quantify the CSA along the entire ACL, (2) describe the location of the ACL isthmus, (3) explore the relationship between ACL length and CSA, and (4) validate magnetic resonance imaging (MRI) for assessing the CSA of the midsubstance ACL. STUDY DESIGN: Descriptive laboratory study. METHODS: Eight cadaveric knees were dissected to expose the ACL and its attachments. Knees were positioned using a robotic loading system through a range of flexion angles in 3 loading states: (1) unloaded, (2) anterior tibial translation, and (3) combined rotational load of valgus and internal torque. Laser scanning quantified the shape of the ACL and its insertion site boundaries. The CSA of the ACL was measured, and the location of the isthmus was determined; the CSA of the ACL was also estimated from MRI and compared with the laser-scanned data. RESULTS: The CSA of the ACL varied along the ligament, and the isthmus existed at an average (±SD) of 53.8% ± 5.5% of the distance from the tibial insertion center to the femoral insertion center. The average CSA at the isthmus was smallest in extension (39.9 ± 13.7 mm(2)) and increased with flexion (43.9 ± 12.1 mm(2) at 90°). The ACL length was shortest at 90° of flexion and increased by 18.8% ± 10.1% in unloaded extension. Application of an anterior load increased the ACL length by 5.0% ± 3.3% in extension, and application of a combined rotational load increased its length by 4.1% ± 3.0% in extension. CONCLUSION: The ACL isthmus is located almost half of the distance between the insertion sites. The CSA of the ACL at the isthmus is largest with the knee unloaded and at 90° of flexion, and the area decreases with extension and applied loads. The CSA at the isthmus represents less than half the area of the insertion sites. CLINICAL RELEVANCE: These results may aid surgical planning, specifically for choosing a graft size and fixation angle that most closely matches the native anatomy and function across the entire range of knee motion.

Effect of tear location on propagation of isolated supraspinatus tendon tears during increasing levels of cyclic loading.

BACKGROUND: The morphology of the supraspinatus tendon may affect tear propagation. It was hypothesized that tears located in the anterior third of the supraspinatus tendon would propagate more readily and would require lower loads to reach critical amounts of tear propagation than those located in the middle third of the supraspinatus tendon. METHODS: Twenty-three fresh-frozen human cadaveric shoulders were tested under increasing levels of cyclic loading. Tears were created in the anterior third (Group A, n=10) or the middle third (Group M, n=13) of the supraspinatus tendon. The maximum load at which a critical tear retraction was reached and the tear area for the final loading set were compared between groups. A correlation analysis was also performed for age compared with maximum load. RESULTS: No significant differences were found between the anterior-third tear group (Group A) and the middle-third tear group (Group M) in maximum load (p=0.09) or tear area (p=0.6). However, Group A first reached a 100% increase in tear size at a significantly lower load than Group M (p=0.03). Strong negative correlations were detected between age and maximum load in Group A (τ=-0.82) and Group M (r=-0.63). CONCLUSIONS: Other factors being equal, tears in the anterior supraspinatus tendon may propagate more readily than tears in the tendon's middle part. Age may be a factor for tear propagation. CLINICAL RELEVANCE: Older patients and patients with tears in the anterior supraspinatus should be followed especially carefully.

Strain distribution due to propagation of tears in the anterior supraspinatus tendon.

Rotator cuff tears are a significant clinical problem. Tears in the anterior supraspinatus might behave differently compared to central tears due to differences in regional structural properties. The objective of this study was to determine strain distributions for anterior supraspinatus tendon tears and the relationship to tear propagation during cyclic loading. It was hypothesized that highest maximum principal strain would be posterior to the tear, and tears would propagate in the direction of the maximum principal strain. Eight human cadaveric supraspinatus tendons with surgically created small tears in the anterior third were tested with increasing levels of cyclic loads. The position of strain markers was recorded on the bursal surface of the tendon to calculate strain. Tendons reached a 2 cm critical tendon retraction at 580 ± 181 N. Largest strains were found medial and posterior to the tear (26.1 ± 9.4%). In five tendons, the strain direction for the initial (114 ± 28°) and final loading sets (86 ± 20°) indicated the strain direction shifted from an anterior to posterior orientation (p < 0.01), corresponding to the direction of tear propagation. Based on the results, anterior supraspinatus tears would remain isolated to the supraspinatus tendon during activities of daily living.

Individualized anatomic anterior cruciate ligament reconstruction.

Arthroscopic anterior cruciate ligament reconstruction (ACL-R) is a technique that continues to evolve. Good results have been established with respect to reducing anteroposterior laxity. However, these results have come into question because nonanatomic techniques have been ineffective at restoring knee kinematics and raised concerns that abnormal kinematics may impact long-term knee health. Anatomic ACL-R attempts to closely reproduce the patient's individual anatomic characteristics. Measurements of the patient's anatomy help determine graft choice and whether anatomic reconstruction should be performed with a single- or double-bundle technique. The bony landmarks and insertions of the anterior cruciate ligament (ACL) are preserved to assist with anatomic placement of both tibial and femoral tunnels. An anatomic single- or double-bundle reconstruction is performed with a goal of reproducing the characteristics of the native ACL. Long-term outcomes for anatomic ACL reconstruction are unknown. By individualizing ACL-R, we strive to reproduce the patient's native anatomy and restore knee kinematics to improve patient outcomes.