Kinematic comparison between the knee after bicruciate stabilized total knee arthroplasty and the native knee: A cadaveric study.

BACKGROUND: Although bicruciate stabilized total knee arthroplasty (BCS-TKA) is expected to provide kinematics similar to those of the normal knee, there are limited data available for comparison of the kinematics of the knee after BCS-TKA with those of the normal knee. The purpose of this study was to confirm whether the knee after BCS-TKA are the same as those of the native knee. METHODS: Seven fresh-frozen cadavers underwent TKA using a BCS-type prosthesis with navigation system. Anteroposterior translation of the femur and internal rotation of the tibia were evaluated using the navigation system. RESULTS: There was no statistically significant difference in anteroposterior translation of the femur between the native knee and the knee after BCS-TKA in the early flexion phase (0°-30°) or in the deep flexion phase (over 100°). In the middle flexion phase (40°-90°), the knee after BCS-TKA was placed significantly more anteriorly than the native knee. The knee after BCS-TKA also showed a gradual internal rotation pattern similar to that of the native knee but the total tibial internal rotation angle was significantly smaller than that of the native knee. At each angle from 0° to 120° of flexion, internal rotation of the knee after BCS-TKA was significantly greater than that of the native knee. CONCLUSION: Kinematics of BCS-TKA is close to that of the native knee. However, there is a statistically significant difference in AP position of the femur during mid flexion and initial rotational position of the tibia between the BCS-TKA knee and the native knee.

Insertion of a spacer block translates the tibia anteriorly during evaluation of soft tissue balance in cruciate-retaining total knee arthroplasty.

BACKGROUND: Soft tissue balance is an important determinant of the outcome of total knee arthroplasty (TKA). However, there are differences in the joint gap and ligament balance between the osteotomized femoral and tibial surfaces and those after TKA. The aim of this study was to compare the relationship between the femur and tibia at insertion of a spacer block with that after cruciate-retaining (CR) TKA. METHODS: Thirty knees in 30 patients (26 women, 4 men) who underwent primary CR TKA with a navigation system were enrolled. Mean age at surgery was 76.3 (range, 63-87) years. After osteotomy of the femur and tibia, the flexion-extension gap and ligament balance were evaluated using a spacer block. The location of the tibial center in relation to the femoral center in the sagittal plane calculated from navigation data at insertion of an appropriately sized spacer block in knee flexion was compared with that after CR TKA using the paired t-test. RESULTS: The mean sagittal location of the tibial center relative to the femoral center in knee flexion was 5.16 (range, -2.4, 16.3) mm at insertion of the spacer block and 6.60 (range, -1.4, 15.1) mm after CR TKA, and this difference was significant (p = 0.016). CONCLUSION: Assessment of soft tissue balance using a spacer block in CR TKA during knee flexion changes the location of the tibia. Surgeons should be aware of the potential for overestimating the postoperative flexion gap in CR TKA when using a spacer block to assess the flexion gap.

Preoperative Planning Using Three-dimensional Printing for Full-endoscopic Spine Surgery: A Technical Note.

Transforaminal full-endoscopic spine surgery (TF-FESS) is a novel minimally invasive spine surgery that requires only an 8-mm skin incision and causes minimal damage to the paravertebral muscles. To perform TF-FESS safely and efficiently, preoperative planning is quite important as the intervention requires anatomical understanding and high technical skills. Recently, three-dimensional (3D) printing has become a useful tool in various surgeries, and several studies have addressed its efficacy; however, there are no reports on the application of 3D printing to FESS. In this study, we present two cases of severe lumbar deformities for which preoperative 3D printing was useful. The 3D printing enabled the surgeons to visualize and plan the drilling of the superior articular process for a successful foraminoplasty at a low cost. The manufacturing equipment cost about USD 900 and is able to produce an actual-size model at a cost of less than USD 10 per patient. In conclusion, preoperative planning using 3D printing should be adopted to safely perform FESS.

Insufficient lateral joint laxity after bicruciate-retaining total knee arthroplasty potentially influences kinematics during flexion: A biomechanical cadaveric study.

BACKGROUND: Soft tissue balancing in bicruciate-retaining (BCR) total knee arthroplasty (TKA) is a challenge that must be overcome to achieve excellent clinical outcomes. However, the optimal degree of joint laxity has yet to be clarified. This cadaveric study sought to examine joint laxity after BCR TKA using a navigation system. METHODS: Knee joint laxity was quantified using an image-free navigation system in 8 intact fresh frozen cadavers under three conditions: the native knee, BCR TKA knee, and BCR TKA knee after anterior cruciate ligament resection. Rotational kinematics in the BCR TKA knee during flexion were compared according to whether joint laxity was increased or decreased. RESULTS: Knee joint laxity after BCR TKA under varus-valgus movement, anterior translation, and internal-external rotation loadings was similar to that of the native knee. However, lateral joint laxity was decreased during flexion in some cases. BCR TKA-treated knees with decreased lateral joint laxity at 90° of flexion demonstrated more limited tibial internal rotation in deep flexion than the native knee (p < 0.05). The loss of internal rotation in deep flexion was partly recovered by using a lateral insert with a posterior slope of +3°. CONCLUSIONS: Restoring optimal joint laxity was not always straightforward in BCR TKA if the 4 ligaments were preserved. Lateral joint laxity was potentially decreased in BCR TKA and may result in kinematic conflict during flexion. Surgeons should be aware of the need to achieve sufficient lateral joint laxity in this type of BCR TKA.

Joint distraction force changes the three-dimensional articulation of the femur and tibia in total knee arthroplasty: a cadaveric study.

PURPOSE: The purpose of this study was to test the hypotheses that the joint distraction force changes the three-dimensional articulation between the femur and the tibia and that the presence of posterior cruciate ligament (PCL) affects the three-dimensional articulation during joint gap evaluation in total knee arthroplasty (TKA). METHODS: Cruciate-retaining TKA procedures were performed on 6 cadaveric knees using a navigation system. The joint center gap and varus ligament balance were measured using Offset Repo-Tensor® with the knee at 90° of flexion before and after PCL resection for joint distraction forces of 89, 178, and 266 N. The three-dimensional location of the tibia relative to the femur and the axial rotational angle of the tibia were also assessed. RESULTS: Regardless of PCL resection, the joint center gap became larger (p = 0.002, p = 0.020) and varus ligament balance became more varus (p = 0.002, p = 0.002) with increasing joint distraction force, whereas the tibia was more internally rotated (p = 0.015, p = 0.009) and more anteriorly located (p = 0.004, p = 0.009). The tibia was more internally rotated (p = 0.015) and more posteriorly located (p = 0.026) after PCL resection than before resection. CONCLUSIONS: Joint distraction force changed three-dimensional articulation regardless of PCL preservation. PCL function was revealed as a factor restraining both tibial posterior translation and internal rotation. Surgeons should recognize that joint gap evaluation using a tensor device is subject to three-dimensional changes depending on the magnitude of the joint distraction force.

The medial constrained insert restores native knee rotational kinematics after bicruciate-retaining total knee arthroplasty.

PURPOSE: The 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). METHODS: Using 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. RESULTS: The 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. CONCLUSION: This 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.

Native rotational knee kinematics is restored after lateral UKA but not after medial UKA.

PURPOSE: The aim of this study was to compare the intraoperative kinematics of medial and lateral unicompartmental knee arthroplasty (UKA) with those of the native knee using a navigation system. METHODS: Six fresh-frozen cadaveric knees were included in the study. Medial UKA was performed in all right knees and lateral UKA was performed in all left knees. All UKA procedures were performed with a computerised navigation system. The tibial internal rotation angle and coronal alignment of the mechanical axis during passive knee flexion were assessed as rotational and varus/valgus kinematics before and after surgery using the navigation system. RESULTS: The rotation angles of the tibia in the early flexion phase of medial UKA were significantly larger than those of native knees (p = 0.008 at minimum knee flexion, p = 0.008 at 0° knee flexion). The rotational kinematics of lateral UKA was similar to those of the native knees throughout knee flexion. There were no significant differences in varus/valgus kinematics between native and UKA knees. CONCLUSION: 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.

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

PURPOSE: To 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. METHODS: The 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. RESULTS: The 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. CONCLUSION: 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.

Radiographic changes of cervical destructive spondyloarthropathy in long-term hemodialysis patients: A 9-year longitudinal observational study.

Analyses of radiographic changes and clinical symptom of destructive spondyloarthropathy (DSA) on consecutive 42 patients managed with long-term hemodialysis were performed to elucidate radiographic changes of DSA and the factors that influence to the destructive changes. Patients underwent plain radiographs of the cervical spine with 9 years interval. Grading of radiological feature from lateral view was classified into grade 0 to grade 3. Clinical symptom was evaluated using modified Japanese Orthopaedic Association scoring system for cervical myelopathy (mJOA score). Destructive changes were observed in 3 patients at the first examination, and those were observed in 15 patients 9 years after the first examination. There is no statistically significant difference between the duration of hemodialysis and the grade. The mean age at the onset of hemodialysis, however, was significantly higher in patients of grade 2 and 3 than those of grade 1. Older patients with long-term hemodialysis had destructive changes. Destructive changes commonly observed in lower cervical spine. The average numbers of the involved disc level were 1.6 in grade 2 and 1.0 in grade 3. Clinical symptoms were varied in each grade and there was no statistically significant difference in total mJOA score among these grades. J. Med. Invest. 64: 68-73, February, 2017.

Prevalence of Symptomatic Lumbar Spondylolysis in Pediatric Patients.

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.].

State of the art: Intraoperative neuromonitoring in spinal deformity surgery.

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.

State-of-the-art ultrasonographic findings in lower extremity sports injuries.

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, Sinding-Larsen-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. J. Med. Invest. 62: 109-113, August, 2015.

Foraminoplastic transforaminal percutaneous endoscopic discectomy at the lumbosacral junction under local anesthesia in an elite rugby player.

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.

A review of the pathomechanism of forward slippage in pediatric spondylolysis: the Tokushima theory of growth plate slippage.

Spondylolysis is a stress fracture of the pars interarticularis, which in some cases progresses to spondylolisthesis (forward slippage of the vertebral body). This slip progression is prevalent in children and occurs very rarely after spinal maturation. The pathomechanism and predilection for children remains controversial despite considerable clinical and basic research into the disorder over the last three decades. Here we review the pathomechanism of spondylolytic spondylolisthesis in children and adolescents, and specifically the Tokushima theory of growth plate slippage developed from our extensive research findings. Clinically, we have observed the slippage site near the growth plate on MRI; then, using fresh cadaveric spines, we found the weakest link against forward shear loading was the growth plate. We subsequently developed an immature rat model showing forward slippage after growth plate injury. Moreover, finite element analysis of the pediatric spine clearly showed increased mechanical stress at the growth plate in the spondylolytic pediatric spine model compared with the intact pediatric spine. Thus, spondylolysis progresses to spondylolisthesis (forward slippage) in children and adolescents with the growth plate as the site of the slippage. Repetitive mechanical loading on to the growth plate may serve to separate the growth plate and subsequently progress to spondylolisthesis.

Percutaneous endoscopic lumbar discectomy for a huge herniated disc causing acute cauda equina syndrome: a case report.

Microsurgery for lumbar disc herniation that requires surgical intervention has been well described. The methods vary from traditional open discectomy to minimally invasive techniques. All need adequate preanesthetic preparation of patients as general anesthesia is required for the procedure, and nerve monitoring is necessary to prevent iatrogenic nerve injury. Conventional surgical techniques sometimes require the removal of the corresponding lamina to assess the nerve root and herniated disc, and this may increase the risk for posterior instability of the vertebral body. Should this occur, fusion surgery may be needed, further increasing morbidity and cost. We present here a case of lumbar herniated disc fragments causing acute cauda equina syndrome that were endoscopically resected through a transforaminal approach in an awake patient under local anesthesia. Percutaneous endoscopic discectomy under local anesthesia proved to be a better alternative to open back surgery as it made immediate intervention possible, was associated with fewer perioperative complications and morbidity, minimized soft tissue damage, and allowed early rehabilitation with a better outcome and greater patient satisfaction. In addition to these advantages, percutaneous endoscopic discectomy protects other approaches that may be needed in subsequent surgeries, whether open or minimally invasive.

Hybrid technique of cortical bone trajectory and pedicle screwing for minimally invasive spine reconstruction surgery: a technical note.

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.

Efficacy of hip arthroscopy in the diagnosis and treatment of synovial osteochondromatosis: a case report and literature review.

Here we report a rare case of synovial osteochondromatosis of the hip and provide a brief review of the literature. A 37-year-old woman was referred to our department with a 3-year history of right hip pain. At initial consultation, she complained of pain upon standing and when sitting down, occasional pain at rest and nocturnal pain in the right hip, and worsening of the pain at premenstruum. The range of motion of the affected hip was totally limited by pain. Plain radiography revealed a slightly calcified (or ossified) lesion at the acetabular fossa of the right hip. Computed tomography showed clusters of loose bodies filling the acetabular fossa. Synovial osteochondromatosis was suspected and she underwent hip arthroscopic surgery. Complete resection was performed using the lateral and anterior portals. Postoperatively, her symptoms disappeared entirely and she was discharged 4 days after surgery. The patient regained full range of motion of the right hip and follow-up CT revealed no remaining loose bodies in the right hip. Hip arthroscopy is considered to be effective for the diagnosis and treatment of synovial osteochondromatosis of the hip and is minimally invasive.