Keizo Wada

Diffusion tensor imaging and tractography of the sciatic nerve: assessment of fractional anisotropy and apparent diffusion coefficient values relative to the piriformis muscle, a preliminary study

ObjectivePiriformis muscle syndrome (PMS) is underdiagnosed. To evaluate the potential of diffusion tensor imaging and diffusion tensor tractography as innovative tools for the diagnosis of PMS by functional assessment of the sciatic nerve, the aims of this study are to assess the reproducibility and to evaluate the changes in the parameters at levels proximal and distal to the piriformis.Materials and methodsFractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve at three levels were quantified twice each by two examiners using the fiber-tracking method. In the first part of the study, laterality and reproducibility were evaluated using intraclass correlation coefficients (ICC) in ten healthy volunteers. In the second part of the study, the healthy side and symptomatic side were assessed in ten consecutive patients with sciatica. There were three patients with no findings on lumbar magnetic resonance imaging (MRI).ResultsThere was no laterality in either FA or ADC values in asymptomatic patients at any level. The mean intra-rater ICC was 0.90 and the mean inter-rater ICC was 0.87. FA was significantly lower and ADC significantly higher on the symptomatic side at each level in patients with sciatica. In the three sciatica patients with no findings on lumbar MRI, FA was significantly lower and ADC was significantly higher only at levels distal to the piriformis. These patients experienced full pain relief after ultrasound-guided injection of local anesthesia.ConclusionsDiffusion tensor imaging and diffusion tensor tractography might be innovative tools for the diagnosis of PMS.

Tendon retraction with rotator cuff tear causes a decrease in cross-sectional area of the supraspinatus muscle on magnetic resonance imaging

BACKGROUND Muscle atrophy and fatty degeneration of the rotator cuff muscles have been reported as negative prognostic indicators after rotator cuff repair. Although the Y-shaped view is widely used for measuring the cross-sectional area of the supraspinatus muscle, the contribution of retraction of the torn tendon as well as muscle atrophy must be considered. The purpose of this study was to clarify the relationship between cross-sectional area and tendon retraction or size of the tear. METHODS This study included 76 shoulders that were evaluated arthroscopically for the presence and size of tears. Cross-sectional areas of rotator cuff muscles were measured from the Y-shaped view to 3 more medial slices. The occupation ratio and tangent sign were evaluated on the Y-shaped view. The retraction of torn tendon was also measured on the oblique coronal images. RESULTS On the Y-shaped view, the cross-sectional area of the supraspinatus and the occupation ratio decreased in conjunction with the increase in tear size. A significant decrease in cross-sectional area was noted only in large and massive tears on more medial slices from the Y-shaped view. Significant decreases in the cross-sectional area of the infraspinatus were observed in large and massive tears on all images. A negative correlation was found between tendon retraction and cross-sectional area, which was strongest on the Y-shaped view. CONCLUSIONS To avoid the influence of retraction of the supraspinatus tendon, sufficient medial slices from the musculotendinous junction should be used for evaluation of muscle atrophy.

Hemorrhagic Facet Cyst in the Lumbar Spine Causing Contralateral Leg Symptoms: A Case Report

Here we present a case of hemorrhagic lumbar facet cyst presenting with progressive radiculopathy only on the contralateral side. If a patient has previous back pain or neuropathy for several months and then suddenly deteriorates, hemorrhagic facet cyst of the lumbar spine should be part of the differential diagnosis. However, as in the present case, we should be aware that there is a possibility of a contralateral lesion.

Intrapelvic Migration of the Lag Screw in Intramedullary Nailing

Internal fixation with intramedullary devices has gained popularity for the treatment of intertrochanteric femoral fractures, which are common injuries in the elderly. The most common complications are lag screw cut out from the femoral head and femoral fracture at the distal tip of the nail. We report here a rare complication of postoperative lag screw migration into the pelvis with no trauma. The patient was subsequently treated with lag screw removal and revision surgery with total hip arthroplasty. This case demonstrated that optimal fracture reduction and positioning of the lag screw are the most important surgical steps for decreasing the risk of medial migration of the lag screw. Furthermore, to prevent complications, careful attention should be paid to subsequent steps such as precise insertion of the set screw.

Location and direction of the nutrient artery to the first metatarsal at risk in osteotomy for hallux valgus

BACKGROUND Osteotomy for hallux valgus interrupts intraosseous blood supply to the first metatarsal, presumably causing non-union, delayed union, or osteonecrosis of the head of the first metatarsal. We investigated the first metatarsal nutrient artery, arising from the first dorsal metatarsal artery, and identified aspects of surgical technique contributing to nutrient artery injury. METHODS Enhanced computed tomography scans of 8 feet of 8 fresh cadavers were assessed. Barium was injected through the external iliac artery; location and direction of the first metatarsal nutrient artery was recorded. RESULTS Mostly, the nutrient artery entered the first metatarsal at the distal third or junction of the middle and distal thirds obliquely from a proximal direction coronally; entry point and direction varied axially. Saw blade overpenetration alone or with extensive capsular stripping might damage the artery. CONCLUSIONS Location and direction of the first metatarsal nutrient artery was established.

Radiation Exposure to the Surgeon and Patient During a Fluoroscopic Procedure: How High is the Exposure Dose? A Cadaveric Study.

Study Design. Using fresh cadavers, real-time dosimeters were used to estimate the radiation exposure dose from C-arm fluoroscopy to surgeons, medical staff, and patients during various procedures. Objective. The aim of this study was to evaluate the radiation exposure dose from C-arm fluoroscopy, which is used to generate real-time images of the human body, under a variety of conditions and in different areas. Summary of Background Data. Awareness of the harmful effects of long-term low-dose radiation is rising. There are no all-inclusive reports evaluating the radiation exposure dose to medical staff associated with fluoroscopic procedures that can accurately simulate the real clinical situation. Methods. Seven fresh cadavers were irradiated for 1, 3, and 5 minutes with C-arm fluoroscopy. The x-ray source was positioned under the table, over the table, and laterally. Radiation exposure doses were measured at different simulated areas such as the center area, and the surgeons hand or thyroid gland. Results. There were significant differences in the radiation exposure dose under different conditions and for different irradiated areas. The risk of direct and scatter radiation exposure was the greatest with the lateral position, which increased by more than 200 times and more than 30 times, respectively, compared with that from a position under the table. Direct radiation was attenuated to less than one-hundredth after passing through the body of the cadaver. All radiation exposure doses were positively correlated with total exposure time. Conclusion. Our study revealed the direct and scatter radiation exposure dose from C-arm fluoroscopy to different areas under a variety of conditions when fluoroscopy is used to generate real-time images of the human body. Our results serve as a guide for medical staff to understand the risk of radiation exposure during each fluoroscopic procedure. Medical staff, especially surgeons, should consider how to protect themselves and reduce radiation exposure by using appropriate shielding. Level of Evidence: 4

A new concept of transforaminal ventral facetectomy including simultaneous decompression of foraminal and lateral recess stenosis: Technical considerations in a fresh cadaver model and a literature review

Percutaneous endoscopic surgery for the lumbar spine, which was established in the last decade, requires only an 8-mm skin incision and causes minimal damage to the paravertebral muscles; thus, it is considered to be a minimally invasive technique for spinal surgery. It has been used to perform percutaneous endoscopic discectomy via two main approaches: the TF approach is a posterolateral one through the intervertebral foramen and can be done under local anesthesia; the IL approach is a more traditional one through the interlaminar space and is difficult to perform under local anesthesia. Recently, these techniques have been applied for lumbar spinal stenosis (LSS), the TF method for foraminal stenosis under local anesthesia, and the IL method for central and lateral recess stenosis under general anesthesia. In this study, using a fresh human cadaver model, we performed simultaneous decompression of the lateral recess and foraminal stenosis at L4-5 using the TF approach. Computed tomography confirmed enlargement of the lateral recess and intervertebral foramen. This technique, which can be performed under local anesthesia, should benefit elderly patients with LSS and poor general condition due to multiple comorbidities. Finally, we introduce the concept of percutaneous transforaminal ventral facetectomy using a spinal percutaneous endoscope. J. Med. Invest. 64: 1-6, February, 2017.

Optimizing baseplate position in reverse total shoulder arthroplasty in small-sized Japanese females: technical notes and literature review

The management of cuff tear arthropathy (CTA) has always been a challenge for shoulder surgeons. Introduction of reverse total shoulder arthroplasty (RTSA) helped in providing pain relief and improved shoulder function in patients with CTA. In this study, we aimed to evaluate the short-term clinical results and some clinical details regarding the types of available prosthesis, positioning, and size of the components for RTSA in a population of short-stature female Japanese. In our seven cases, the average glenoid size was 23.9 mm in width and 34.2 mm in height. The average width was smaller than the size of all available baseplates. We implanted reverse shoulder prostheses with baseplate that measured 28 mm in diameter and two locking screws. The center of the baseplate was shifted to allow slight anterior overhang relative to the anatomical center to avoid breakage of the posterior cortex and to achieve firm fixation. One case of humeral shaft fracture occurred while inserting the humeral stem and required encircling wiring. In our experience, the short term clinical results of RTSA were excellent, but a new prosthesis that is designed to fit the short stature of Asians with smaller glenoid and humerus should be considered.

Native rotational knee kinematics are lost in bicruciate-retaining total knee arthroplasty when the tibial component is replaced

PurposeTo compare the kinematics between native knees and knees that have undergone bicruciate-retaining (BCR) total knee arthroplasty (TKA) with cruciate-retaining (CR) TKA converted from BCR TKA in the same whole-body cadaveric specimen using a navigation system and, if differences exist, to investigate the point at which normal kinematics are lost during the procedure.MethodsThe rotational kinematics throughout passive flexion of the native knee and of knees after meniscectomy, femoral replacement, BCR TKA, or CR TKA were assessed in nine fresh frozen cadavers using an image-free navigation system.ResultsThe rotational kinematic pattern of a knee after BCR TKA was different from that of a native knee, especially in the early flexion phase, and was similar to that after CR TKA. Screw-home movement was not observed after BCR TKA, but still occurred after meniscectomy or femoral replacement with intact cruciate ligaments and an intact tibial articular surface.ConclusionThe 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.

The Posterior Condylar Cartilage Affects Rotational Alignment of the Femoral Component in Varus Knee Osteoarthritis

Rotational alignment of the femoral component in total knee arthroplasty (TKA) is important for patellar tracking and ligament balance. Preoperative planning based on radiography might have a potential risk for over-rotation because these X-ray based measurements can not detect asymmetric cartilage wear on posterior condyle. The purpose of this study is to evaluate the effect of the posterior condylar cartilage of varus osteoarthritic knee on rotational alignment of the femoral component in TKA. We established two different condylar twist angles (CTA) from intraoperative multiplanar reconstruction (MPR) images and intraoperative information of navigation system. The CTA measured by a navigation system that includes the cartilage (4.8±2.0°) was smaller than those measured by MPR images, which does not include the cartilage (6.6±2.1°) (p<0.05). The difference between these two angles that corresponds to the remaining posterior condylar cartilage was 1.7±1.2°. This result demonstrated that the posterior condylar cartilage might lead to over-rotational of the femoral component in varus osteoarthritic knee. Therefore, when determining rotational alignment of the femoral component, surgeons should consider the effect of the remaining posterior condylar cartilage to avoid the over-rotation of the femoral component, especially in severe varus knees. J. Med. Invest. 64: 24-29, February, 2016.