Medial Meniscus Posterior Root Reconstruction and Open-Wedge High-Tibial Osteotomy for Medial Meniscus Posterior Root Tear With Varus Knee Alignment: A Retrospective Study on Short-Term Outcomes.

PURPOSE: We describe 13 cases of medial meniscus posterior root tear (MMPRT) with varus knee alignment treated with medial meniscus posterior root reconstruction (MMPR-R) and open-wedge high-tibial osteotomy (OWHTO) to identify an optimal MMPRT treatment. METHODS: We retrospectively reviewed 13 patients (mean age: 66.3 ± 8.0 years) who underwent MMPR-R and OWHTO. The Knee Injury and Osteoarthritis Outcome Score (KOOS), femorotibial angle (FTA), percentage mechanical axis (%MA) on radiography, and medial meniscus extrusion (MME) on magnetic resonance imaging (MRI) between the preoperative period and last follow-up were compared. Moreover, meniscus healing status and the International Cartilage Repair Society (ICRS) classification of the medial femoral condyle and medial tibial plateau on arthroscopy between the initial surgery and second-look arthroscopy were compared. RESULTS: The mean follow-up duration was 12.8 ± 2.2 months. At the last follow-up, the KOOS significantly improved (P < 0.01). Based on the FTA and %MA, the varus alignment was predominantly corrected at the last follow-up (P < 0.01). The MME was increased in nine (62.9%) patients, and the mean MME significantly increased at the last follow-up (P = 0.04). Second-look arthroscopy revealed improvements in the ICRS grade for the medial femoral condyle and medial tibial plateau in six (46.2%) patients. However, the results did not significantly differ. Regarding meniscus healing, four (30.8%) patients presented with complete healing, eight (57.1%) with partial healing, and one (7.7%) with failed healing. CONCLUSIONS: The MMPRT with varus knee alignment significantly improved with MMPR-R and OWHTO. However, the MME and meniscus healing were unsatisfactory.

Osteosynthesis with Arthroscopy of a Nonunited Tibial Anterior Cruciate Ligament Avulsion Fracture 30 Years after Injury.

There are a few reports on the treatment of nonunited tibial anterior cruciate ligament (ACL) avulsion fractures. To our knowledge, this is the first report of a case of nonunited tibial ACL avulsion fracture 30 years after injury. A 36-year-old woman injured her knee during a road traffic accident 30 years ago. Since then, she had persistent knee instability that was left untreated. She presented to our clinic because of knee pain she had been experiencing for a week. Radiography and computed tomography revealed tibial ACL avulsion fracture nonunions. Screw fixation with arthroscopy was performed, and bone fusion was obtained. The knee injury and osteoarthritis outcome score improved from 24 points preoperatively to 83 points postoperatively. The nonunion of intercondylar eminence fractures of the tibia, even up to 30 years after the initial injury, can be treated by osteosynthesis with arthroscopy.

Type V Tibial Tubercle Avulsion Fracture with Suspected Complication of Anterior Cruciate Ligament Injury: A Case Report.

Background and Objectives: Type V tibial tubercle avulsion fractures are extremely rare; therefore, information on them remains limited. Furthermore, although these fractures are intra-articular, to the best of our knowledge, there are no reports on their assessment via magnetic resonance imaging (MRI) or arthroscopy. Accordingly, this is the first report to describe the case of a patient undergoing detailed evaluation via MRI and arthroscopy. Case Presentation: A 13-year-old male adolescent athlete jumped while playing basketball, experienced discomfort and pain at the front of his knee, and fell down. He was transported to the emergency room by ambulance after he was unable to walk. The radiographic examination revealed a Type Ⅴ tibial tubercle avulsion fracture that was displaced. In addition, an MRI scan revealed a fracture line extending to the attachment of the anterior cruciate ligament (ACL); moreover, high MRI intensity and swelling due to ACL were observed, suggesting an ACL injury. On day 4 of the injury, open reduction and internal fixation were performed. Furthermore, 4 months after surgery, bone fusion was confirmed, and metal removal was performed. Simultaneously, an MRI scan obtained at the time of injury revealed findings suggestive of ACL injury; therefore, an arthroscopy was performed. Notably, no parenchymal ACL injury was observed, and the meniscus was intact. The patient returned to sports 6 months postoperatively. Conclusion: Type V tibial tubercle avulsion fractures are known to be extremely rare. Based on our report, we suggest that MRI should be performed without hesitation if intra-articular injury is suspected.

Arthroscopic Osteophyte Resection for Osteophyte-Induced Popliteal Impingement.

Popliteal tendinitis causes lateral knee pain. A cause is impingement of the popliteal tendon by lateral femoral condylar osteophytes. Conservative and surgical treatments have been reported; however, popliteal impingement is a relatively rare disease, and no treatment has been established. Reduction of mechanical stress is important in the treatment of impingement syndromes. The popliteal tendon is an important tissue that contributes to knee stability and, therefore, usually cannot be transected. On the other hand, osteophyte resection may allow the reduction of mechanical stress. Therefore, we describe an arthroscopic osteophyte resection technique for the treatment of osteophyte-induced popliteal impingement. In brief, this technique involves confirmation of popliteal impingement, osteophyte resection using an osteotome, smoothening of the resected area, and confirmation of the resolution of popliteal impingement.

Arthroscopic Medial Meniscus Posterior Root Reconstruction and Pull-Out Repair Combined Technique for Root Tear of Medial Meniscus.

Repair of medial meniscus posterior root tear is important in preventing rapid progression of knee osteoarthritis. There are many repair techniques for medial meniscus posterior root tears, and good clinical results have been reported. Conversely, in terms of improving extrusion and healing meniscal injuries, sufficient results have not been obtained. Reconstruction of the medial meniscus posterior root can restore meniscal hoop action and normal knee biomechanics. Moreover, pull-out repair technique provides strong traction. We describe arthroscopic medial meniscus posterior root reconstruction and pull-out repair technique combined technique for medial meniscus root tear.

Localized Pigmented Villonodular Synovitis of the Bilateral Knee: A Case Report.

Introduction: Localized pigmented villonodular synovitis (PVNS) is a rare and benign condition of synovial tissue proliferation that affects the joints, tendon sheaths, and bursae. This case report is the first to describe a patient with a diagnosis of localized PVNS of the knee after presentation with bilateral and simultaneous onset of associated knee pain. Case Report: A 28-year-old Japanese woman presented to our hospital with a 1-year history of bilateral knee pain and right knee locking that started 1 month ago. Magnetic resonance imaging demonstrated a mass lesion in both the anterior compartment of the right knee and in the posterior compartments of the left knee. Arthroscopic resection of the lesions was performed, and the diagnosis of localized PVNS was made by pathological analysis. At the 6-month follow-up, no evidence of recurrence was noted. Conclusion: This case report describes localized PVNS of the bilateral knee, which is extremely rare. PVNS is a disease requiring surgical resection and should not be overlooked. It should be treated with the possibility of bilateral occurrence in mind.

Medial Meniscus Posterior Root Reconstruction and Open- Wedge High Tibial Osteotomy for Medial Meniscus Posterior Root Tear with Varus Knee: A Case Report.

Introduction: Pull-out suture, suture anchor, and open- wedge high tibial osteotomy have been widely used for surgical treatment of medial meniscus posterior root tear, and relatively good clinical results have been reported. However, radiologic and arthroscopic findings are not sufficient. This report describes the first case, to the best of our knowledge, of medial meniscus posterior root reconstruction and high tibial osteotomy for medial meniscus posterior root tear with varus knee. Case Report: A 78-year-old Japanese man was referred to our hospital due to the right popliteal pain. Plain radiography showed the mechanical axis percentage of the right limb to be 17%, indicating a varus mechanical axis. magnetic Magnetic resonance imaging noted a medial meniscus posterior root tear. Medial meniscus posterior root reconstruction and high tibial osteotomy were performed. His knee injury and osteoarthritis score improved from 22 points preoperatively to 91 points 1 year postoperatively. The graft had a good live induction and the medial meniscus hoop was maintained. Conclusion: This report is the first case, to the best of our knowledge, of medial meniscus posterior root reconstruction and high tibial osteotomy for medial meniscus posterior root tear with varus knee. This type surgical technique may be useful for a meniscus posterior root tear with varus knee.

Potential of the non-weight-bearing tunnel view in diagnosing medial meniscus posterior root tear: a pilot study of X-ray characteristics.

PURPOSE: Early detection of medial meniscus posterior root tear (MMPRT) is important in preventing the rapid onset and progression of degenerative knee disease. Diagnosis is facilitated by the availability of non-weight-bearing X-ray view, but information on the X-ray characteristics of MMPRT is scarce. Here, we conducted a pilot study of the X-ray characteristics of MMPRT on non-weight-bearing tunnel view. METHODS: We retrospectively reviewed 43 consecutive patients treated in the outpatient department for medial knee pain or popliteal pain. Patients were divided into MMPRT (21 knees) and non-MMPRT groups (22 knees). We investigated X-ray characteristics and magnetic resonance imaging findings. Femorotibial angle, posterior tibial slope, medial tibial eminence (MTE)-medial femoral condyle (MFC) distance (contralateral and affected sides, and difference between the two), medial tibiofemoral joint (MTFJ) width (contralateral and affected sides, and difference between the two), and meniscus radial dislocation between the groups were evaluated using the Mann-Whitney U test. The association between X-ray characteristics and MMPRT was determined using univariate and multivariate logistic regression analyses. RESULTS: A highly significant difference between the affected and contralateral sides was seen in MTFJ width and MTE-MFC distance on non-weight-bearing tunnel view between the MMPRT and non-MMPRT groups. Moreover, a difference in MTFJ width of <-0.575 mm and in MTE-MFC distance of >0.665 mm between the affected and contralateral sides was useful in predicting MMPRT. CONCLUSIONS: The non-weight-bearing tunnel view is useful for the initial diagnosis of MMPRT. Prospective evaluation in a larger population is warranted.

Consistent modelling of material weight loss and gas release due to pyrolysis and conducting benchmark tests of the model-A case for glovebox panel materials such as polymethyl methacrylate.

It is necessary to consider how a glove box's confinement function will be lost when evaluating the amount of radioactive material leaking from a nuclear facility during a fire. In this study, we build a model that consistently explains the weight loss of glove box materials because of heat input from a flame and accompanying generation of the pyrolysis gas. The weight loss suggests thinning of the glove box housing, and the generation of pyrolysis gas suggests the possibility of fire spreading. The target was polymethyl methacrylate (PMMA), used as the glove box panel. Thermal gravimetric tests on PMMA determined the parameters to be substituted in the Arrhenius equation for predicting the weight loss in pyrolysis. The pyrolysis process of PMMA was divided into 3 stages with activation energies of 62 kJ/mol, 250 kJ/mol, and 265 kJ/mol. Furthermore, quantifying the gas composition revealed that the composition of the pyrolysis gas released from PMMA can be approximated as 100% methyl methacrylate. This result suggests that the released amount of methyl methacrylate can be estimated by the Arrhenius equation. To investigate the validity of such estimation, a sealed vessel test was performed. In this test, we observed increase of the number of gas molecules during the pyrolysis as internal pressure change of the vessel. The number of gas molecules was similar to that estimated from the Arrhenius equation, and indicated the validity of our method. Moreover, we also performed the same tests on bisphenol-A-polycarbonate (PC) for comparison. In case of PC, the number of gas molecules obtained in the vessel test was higher than the estimated value.