: The pedicle screw (PS) system is widely used for spinal reconstruction. Recently, screw insertion using the cortical bone trajectory (CBT) technique has been reported to provide increased holding strength of the vertebra, even in an osteoporotic spine. CBT is also beneficial due to its low invasiveness. We have been performing hybrid reconstruction with CBT at the cranial level and PS at the caudal level based on the concept of minimal invasiveness. We applied this hybrid technique to 6 cases of degenerative spondylolisthesis. Surgery was completed with a small skin incision of around 5-6 cm, which is shorter than that of the conventional PS procedure. The mean percent slippage before surgery was 19.8% %, and this was reduced to 3.9% % after surgery and almost maintained 3 months after surgery. Furthermore, no major surgical complications were observed. Here, we introduce the minimally invasive hybrid technique of CBT-PS. Surgeons should be aware of the procedure as an option for minimally invasive lumbar spine reconstructive surgery.

The rotational kinematics of the native knee are not always preserved after BCR TKA. Native rotational kinematics are preserved after meniscectomy and femoral replacement, but are lost after tibial replacement in BCR TKA. Surgeons should pay close attention to maintain the anteroposterior stabilizing function of the ACL in BCR TKA, rather than to restore the native rotational kinematics.

Lumbar spondylolysis, a stress fracture of the pars interarticularis, is prevalent in adolescent athletes. Recent advances in diagnostic tools and techniques enable early diagnosis before these fractures progress to complete fractures through the pars. However, because patients often consult family physicians for primary care of low back pain and these physicians may not have access to diagnostic modalities such as magnetic resonance imaging (MRI) and computed tomography, stress fractures can be missed. This study surveyed the prevalence of symptomatic spondylolysis in pediatric patients who consulted an orthopedic clinic for primary care and investigated whether such acute stress fractures may be overlooked without MRI. The prospective study investigated 264 patients who were younger than 19 years and had low back pain. Of the 153 patients (58.0%) with low back pain persisting for longer than 2 weeks, 136 who agreed to undergo MRI were included in the study. This group included 11 elementary school students, 71 junior high school students, and 54 high school students. The overall prevalence of lumbar spondylolysis was 39.7% (54 of 136) and was 9.3% in elementary school students (5 of 11, 45.5%), 59.3% in junior high school students (32 of 71, 45.1%), and 31.5% in high school students (17 of 54, 31.5%). All 54 patients with spondylolysis had a history of athletic activity. Primary care physicians should recognize that approximately 40% of pediatric patients presenting with low back pain persisting for longer than 2 weeks may have spondylolysis and should consider MRI in those with a history of athletic activity. Because the spine is immature in this age group, almost half of affected elementary school and junior high school students may have lumbar spondylolysis. [Orthopedics. 2016; 39(3):e434-e437.].

The rotational kinematics of the native knee was not restored after medial UKA but was preserved after lateral UKA. There were no significant differences in the varus/valgus kinematics after either medial or lateral UKA when compared with those of the native knees. Thus, the geometry of the medial tibial articular surface is a determinant of the ability to restore the rotational kinematics of the native knee. Surgeons and implant designers should be aware that the anatomical medial articular geometry is an important factor in restoration of the native knee kinematics after knee arthroplasty.

: Athletes sometimes experience overuse injuries. To diagnose these injuries, ultrasonography is often more useful than plain radiography, computed tomography (CT), or magnetic resonance imaging (MRI). Ultrasonography can show both bone and soft tissue from various angles as needed, providing great detail in many cases. In conditions such as osteochondrosis or enthesopathies such as Osgood-Schlatter disease, SindingLarsen-Johansson disease, bipartite patella, osteochondritis dissecans of the knee, painful accessory navicular, and jumper's knee, ultrasonography can reveal certain types of bony irregularities or neovascularization of the surrounding tissue. In patients of enthesopathy, ultrasonography can show the degenerative changes at the insertion of the tendon. Given its usefulness in treatment, ultrasonography is expected to become essential in the management of overuse injuries affecting the lower limb in athletes.

Percutaneous endoscopic discectomy (PED) is the least invasive disc surgery available at present. The procedure can be performed under local anesthesia and requires only an 8 mm skin incision. Furthermore, damage to the back muscle is considered minimal, which is particularly important for disc surgery in athletes. However, employing the transforaminal (TF) PED approach at the lumbosacral junction can be challenging due to anatomical constraints imposed by the iliac crest. In such cases, foraminoplasty is required in addition to the standard TF procedure. A 28-year-old man who was a very active rugby player visited us complaining of lower back and left leg pain. His visual analog scale (VAS) score for pain was 8/10 and 3/10, respectively. MRI revealed a herniated nucleus pulposus at L5-S level. TF-PED was planned; however, the anatomy of the iliac crest was later found to prevent access to the herniated mass. Foraminoplasty was therefore performed to enlarge the foramen, thereby allowing a cannula to be passed through the foramen into the canal without causing exiting nerve injury. The herniated mass was then successfully removed via the TF-PED procedure. Pain resolved after surgery, and his VAS score decreased to 0/10 for both back and leg pain. The patient returned to full rugby activity 8 weeks after surgery. In conclusion, even with an intracanalicular herniated mass at the lumbosacral junction, a TF-PED procedure is possible if additional foraminoplasty is adequately performed to enlarge the foramen.

PurposeThe aim of this study was to test the hypothesis that the medial constrained insert would reproduce the native knee kinematics after bicruciate‐retaining (BCR) total knee arthroplasty (TKA). MethodsUsing an image‐free navigation system in six fresh‐frozen whole‐body cadavers, the rotation angle of the tibia at minimum flexion, at 10° intervals from 0° to 130° flexion, and at maximum flexion during manual passive knee flexion was assessed. The data was collected in native knees, in BCR TKA using a normal flat insert (BCR‐XP), and in BCR TKA using a more constrained insert in the medial side (BCR‐AS). The differences in the rotation angle of the tibia were statistically evaluated. ResultsThe rotation angles of the tibia in BCR‐XP were significantly different from those of the native knees both in the early flexion phase (p = 0.002 at minimum knee flexion, p = 0.002 at 0°, p = 0.041 at 10°, p = 0.009 at 20°, p = 0.026 at 30°) and in the late flexion phase (p = 0.015 at 130°, p = 0.015 at maximum knee flexion), whereas the rotational angles of the tibia in BCR‐AS were similar to those of the native knee. ConclusionThis study shows that the rotational kinematics of the native knee is reproduced after BCR TKA with the medial constrained insert. Surgeons and implant designers should be aware that constraint of the medial side in BCR TKA is a crucial factor for restoration of native kinematics which may lead to better clinical outcome.

Application of deformity correction spinal surgery has increased substantially over the past three decades in parallel with improvements in surgical techniques. Intraoperative neuromonitoring (IOM) techniques,including somatosensory evoked potentials (SEPs), muscle evoked potentials (MEPs), and spontaneous electromyography (free-run EMG), have also improved surgical outcome by reducing the risk of iatrogenic neural injury. In this article, we review IOM techniques and their applications in spinal deformity surgery. We also summarize results of selected studies including hundreds of spinal correction surgeries. These studies indicate that multimodal IOM of both motor and sensory responses is superior to either modality alone for reducing the incidence of neural injury during surgery. J. Med. Invest. 62: 103-108, August, 2015.