Approximately 41% of knees have a looser gap in full extension than in 20° flexion after Oxford unicompartmental arthroplasty.

INTRODUCTION: In Oxford unicompartmental knee arthroplasty (OUKA), the flexion and extension gaps should be adjusted to prevent mobile-bearing dislocation. The extension gap is recommended to be evaluated in the 20° flexion position to avoid underestimation due to tension of the posterior capsule. However, we have become aware of a looser gap in full extension than in 20° flexion in some instances. MATERIALS AND METHODS: We retrospectively investigated 83 knees in 60 patients who underwent OUKA between January and June 2020. During surgery, the extension gaps were measured in both full extension and 20° flexion. The knees were classified into two groups: the gap was looser in full extension (0° group), and the gap was equal or looser in 20° flexion than in full extension (20° group). The hip-knee-ankle angle (HKAA), the lateral distal femoral angle (LDFA), the medial proximal tibia angle (MPTA), the posterior tibial slope angle (PTSA), and the last spigot size were also measured and compared between the groups. RESULTS: There was looseness in approximately 41% of knees (34 out of 83 knees) in full extension. In the knees in the 0° group, the last spigot size was significantly smaller (median 1 and 2, P < 0.01). However, there were no significant differences in the HKAA, MPTA, LDFA or PTSA between the groups. CONCLUSIONS: Approximately 41% of knees have a looser gap in full extension than in 20° flexion after OUKA. Further investigation is needed to better understand which extension gap should be used in such cases, and to find the contributing factors in loose full extension gap other than the size of the last spigot.

Approximately 80% of Japanese osteoarthritic patients fall out of the safety range in restricted kinematically-aligned total knee arthroplasty in an analysis of preoperative long-leg radiograms.

BACKGROUND: Restricted kinematically-aligned total knee arthroplasty (KA-TKA) is a reasonable modification to avoid the alignment outlier that may cause implant failure. However, despite a noted high incidence of constitutional varus in Japanese individuals, there has been no investigation into how many knees require the restriction in restricted KA-TKA (RKA-TKA) among Japanese patients. Therefore, we conducted a study using preoperative long-leg radiograms. METHODS: We studied long-leg radiographs of 228 knees in 114 consecutive patients. The numbers of knees within the safety range and their corrective osteotomy angle in the restriction algorithms advocated by Almaawi et al. (2017) and MacDessi et al. (2020) were evaluated. RESULTS: According to the algorithms used by Almaawi et al. and MacDessi et al., out of 228 knees, 46 (20%) and 39 (17%) fell within the safety range, respectively. The mean correction angles of the hip-knee-ankle angle, lateral distal femoral angle and medial proximal tibial angle were 2.8 ± 3.4°, 0.4 ± 1.4° and 2.4 ± 2.8° in the algorithm used by Almaawi et al., while they were -4.9 ± 4.7°, 1.1 ± 2.5° and -6.0 ± 3.4° in the algorithm used by MacDessi et al. Most of the knees needed to be restricted in order to perform RKA-TKA, regardless of the algorithm used. CONCLUSIONS: Based on a preoperative analysis of long-leg radiograms in a Japanese population, most knees fall out of the safety range in RKA-TKA. Surgeons must consider whether to allow component outlier or to perform corrective osteotomy that likely requires soft tissue release.

Contralateral knee flexion predicts postoperative knee flexion in unilateral total knee arthroplasty: A retrospective study.

BACKGROUND: Postoperative flexion angle is associated with preoperative flexion in the same knee after total knee arthroplasty (TKA). However, whether the preoperative contralateral knee flexion angle could influence postoperative flexion remains unknown. This study aimed to test the effect of contralateral knee flexion on final flexion in the postoperative knee after unilateral TKA. We hypothesized that the preoperative contralateral knee flexion angle affects postoperative knee flexion, as does preoperative flexion, in the operated knee. PATIENTS AND METHODS: Ninety-five patients with knee osteoarthritis (OA) who underwent cruciate-retaining TKA were included in this study, and their maximum passive knee flexion angle was evaluated preoperatively and at final follow-up on the operative and contralateral sides. Patients were divided according to their preoperative flexion angles: Group C, those whose contralateral knee flexion angle was greater than the operative knee flexion angle; and Group O, those whose contralateral knee flexion angle was equal to or smaller than the operative knee flexion angle. We performed multiple regression analysis, with postoperative flexion and improvement in the flexion angle as objective variables and preoperative predictors (age, sex, body mass index, preoperative flexion, and contralateral knee flexion) as explanatory variables. The results of the flexion angles were compared between the two groups using unpaired t-tests. RESULTS: Postoperative flexion angle was significantly affected by the preoperative contralateral knee flexion angle (ß=0.35, p=0.002), and an improvement in flexion was negatively affected by preoperative flexion of the operated knee (ß=-0.83, p<0.001) and positively affected by contralateral knee flexion (ß=0.35, p=0.001). Group O achieved poorer postoperative flexion than Group C (110.4±16.6° vs 119.6±16.5°, p=0.0017). CONCLUSION: Patients with less flexion of the contralateral knee are less likely to obtain a greater degree of knee flexion after TKA. LEVEL OF EVIDENCE: III; retrospective comparative study.

Validation of the Macroscopic Anterior Cruciate Ligament Status Using the Oxford Classification System in Relation to Cartilage Defects on the Medial Tibial Plateau in Osteoarthritic Knees.

This study evaluated the relationships between anterior cruciate ligament (ACL) grading using the Oxford classification system and cartilage defects on the medial tibial plateau to clarify the validity of the system. We studied the location and size of a full-thickness cartilage defect of the medial tibial plateau in 154 knees (97 patients) treated by unicompartmental (113) or total (41) knee arthroplasty between April 2017 and January 2018, and analyzed their relationship to the anterior cruciate ligament (ACL) grade, Grade 1 (normal), Grade 2 (synovial damage), Grade 3 (longitudinal split), Grade 4 (friable and fragmented), and Grade 5 (absent). Significant trends in decreased posterior preserved cartilage, increased defect length, and posteriorized defect center were associated with increasing ACL grade. Multiple comparison analysis revealed that the measurements were significantly different between ACL functional (Grades 1-3) and ACL deficient (Grades 4 and 5). On the other hand, the anterior preserved cartilage was consistent among the Grades. The macroscopic Oxford ACL classification system well described the disease progression where the cartilage defect extends posteriorly with ACL damage. However, 38% of ACL deficient knees had well-preserved posterior cartilage with no evident tibial anterior translation.

Manipulation of Tibial Component to Ensure Avoidance of Bearing Separation from the Vertical Wall of Tibial Component in Oxford Unicompartmental Arthroplasty.

In Oxford unicompartmental knee arthroplasty, the relationship between the mobile bearing and the vertical wall of the tibial tray is important in preventing bearing dislocation. Separation of the bearing from the vertical wall can cause spinning of the bearing with an increased risk of subsequent dislocation. We report on intraoperative adjustment of the tibial tray performed to prevent the bearing from spinning. After tibial and femoral bone cutting and adjustment of the flexion and extension gap, the trial bearing is inserted and the bearing-vertical wall distance is evaluated before the preparation using the tibial template and bearing trial. In the case of separation, it can be resolved by medialization with or without rotational adjustment. The technique is useful and can be easily performed, it is therefore recommendable for all cases of Oxford mobile-bearing unicompartmental arthroplasty.

A Novel Technique for Varus Tibial Cutting for Oxford Unicompartmental Knee Arthroplasty.

To reduce the stress on the medial tibial cortex and to decrease the risk of fracture, a varus cut of the tibia appears to be a reasonable alternative to the orthogonal cut by conventional methods. We present a new instrument and procedure, which enables a varus tibial cut for Oxford unicompartmental knee arthroplasty. We used a custom-made, slidable fixator instead of the standard fixator to set the extramedullary rod on the leg. We also made a numeric formula and a chart to arrange the varus cutting angle using the length of the mediolateral shift of the distal end and the longitudinal extension length of the extramedullary tibial rod. A varus cut up to 4.5° can be controlled. This technique is a simple and useful means of obtaining a varus tibial cut for Oxford unicompartmental knee arthroplasty.

Bilateral unicompartmental knee arthroplasty for windswept knee osteoarthritis: A report of 13 cases.

BACKGROUND: Windswept deformity is a condition of the lower limbs with a valgus knee on one side and a varus knee on the other. We present a case series of bilateral unicompartmental knee arthroplasty (UKA) for windswept knee osteoarthritis (WSKO). METHODS: We analysed the outcomes of 26 knees of 13 consecutive patients with WSKO treated with bilateral UKA. The mean age was 73.0 years and the mean follow up period was 2.6 years. Pre- and postoperative Oxford Knee Score (OKS) and Japanese Orthopaedic Association (JOA) score, radiological measurements and postoperative complications were evaluated. No knees required revision for either infection or loosening. RESULTS: The mean preoperative OKS was 25.3 ± 9.7, which increased to 34.9 ± 5.8 at the latest follow up. The mean preoperative JOA scores for the varus and the valgus sides were 64.6 ± 12.5 and 66.9 ± 14.1, which increased to 85.0 ± 11.3 and 84.6 ± 11.2, respectively, after operation. CONCLUSIONS: Our results show that good short-term clinical results can be achieved by bilateral UKA in cases of WSKO. Bilateral UKA may be an effective treatment for WSKO if indications are met.

Extent of in vivo sagittal bearing movement and its relationship with tibial posterior slopes in Oxford mobile-bearing unicompartmental knee arthroplasty.

BACKGROUND: The effect of increased tibial slope on the bearing movement and clinical results in mobile-bearing unicompartmental knee arthroplasty has not been well discussed. We aimed to clarify the extent of in vivo sagittal bearing movement and bearing overhang using fluoroscopy and their relationship with the tibial posterior slopes and clinical results. METHODS: This retrospective study included 40 patients who underwent Oxford unicompartmental knee arthroplasty for anteromedial osteoarthritis or osteonecrosis of the knee. Intraoperative posterior translation and posterior overhang of the bearing were assessed during flexion. The tibial posterior slopes were evaluated before and 2 weeks after surgery, and its increment was recorded. Clinical evaluations were also performed preoperatively and at 2 years postoperatively (maximum flexion angle, Oxford Knee Score). Single linear regression analysis was performed to assess the correlation between the tibial posterior slopes and the posterior translation and the posterior overhang and determine if these could affect the clinical outcomes. FINDINGS: The average posterior translation was 10.7 ± 4.3 mm, and posterior overhang of the mobile bearing was found in 35% of overall patients. They were associated with increased tibial slope as well as poorer improvement in Oxford Knee Score at 2 years postoperatively. INTERPRETATION: In Oxford unicompartmental knee arthroplasty, mobile bearing can probably move posteriorly beyond the posterior margin of the tibial component during flexion when the tibial posterior slope increases more than the original magnitude. Additionally, the posterior translation and posterior overhang closely correlated with the poorer improvement in Oxford Knee Score at 2 years postoperatively.

Does the duration to bipolar hip arthroplasty for femoral neck fracture influence on postoperative muscular strength?

BACKGROUND: The primary purpose of this study was to compare the postoperative muscular strength and functional performance between early versus late bipolar hip arthroplasty (BHA) intervention for femoral neck fracture classified by the duration from the onset to surgery. METHODS: Twenty-one patients who could walk at 12 months or more after BHA were enrolled into this study. We examined the muscular strength of hip flexion, extension, abduction, and knee extension of these patients. Time of one-leg standing, timed up and go test, pain grade by visual analog scale, and Barthel index were also evaluated as functional indices. We classified these patients into two groups by the duration from the onset to surgery, namely: within 3 days until BHA (early OP) and more than 4 days (late OP) to compare these indices at the latest follow-up. RESULTS: The mean days until operation were 2.3 days in the early-OP group and 5.9 days in the late-OP group, showing a significant difference between the two groups. Muscular strength and other functional indices were also found to have no significant differences between these two groups. CONCLUSION: Our study suggests that the delay to operate might not severely compromise the muscular strength around the hip joint for least 1.5 years among ambulatory patients.

Ideal screw positions for multiple screw fixation in femoral neck fractures - Study of proximal femur morphology in a Japanese population.

BACKGROUND: Despite the fact that multiple screw fixation is a common option of surgical treatment for femoral neck fractures, there is a paucity of precise morphological study of the femoral neck. To identify appropriate positions and spacing of hip screws for multiple-screw femoral neck fracture fixation, proximal femur morphology in Japanese patients was studied. METHOD: One hundred hips in fifty knee arthroplasty candidates were studied. Following full limb CT, defined slices were created and anatomical variables measured. RESULT: The average neck-shaft angle was 126.5° and the distance from the subcapital line to the subchondral bone on a line parallel to the femoral neck axis (FNA) was approximately 25 mm at the superior and inferior; borders of the femoral neck. The FNA was shown to run anterior to the femoral axis (FA). The cross section of the femoral neck forms a reverse right triangle. The height and width of the neck medullary canal were equal (approximately 25 mm), with the posterior wall closer to the femoral axis than the anterior wall. CONCLUSION: Based on these data, the anterior screw positioned just above the calcar femorale, 16 mm proximal and 27° anterior to the FA, and the posterior screw positioned 12 mm proximal and 5 mm posterior to the FA is recommended. For screws inserted with a fixed angle side-plate, ≤130° is recommended.

Additional Visualization via Smart Glasses Improves Accuracy of Wire Insertion in Fracture Surgery.

BACKGROUND: Smart glasses (SG) are a wearable device consisting of a small computer built into a head-mounted monitor (HMM) that can display various kinds of information. Lateral side visualization is displayed on the HMM of SG so the operator may also see it and the anteroposterior (AP) direction simultaneously. The present pilot study aimed to investigate the usefulness of SG in wire insertion for bone fracture. METHODS: We marked both the front and lateral sides of the shaft of an artificial femur bone. From the tip of the greater trochanter, we inserted a 2.4-mm Kirschner wire (K-wire) so that it could be directed toward the marks in both planes. Three surgeons enrolled in the study each performed 10 trials, both with SG (SG arm) and without (direct vision arm). We defined the error angle as the angle between the K-wire and the line connecting the marking point from the insertion point in both the front and lateral view images. We also measured the time it took to insert the K-wire in both arms. RESULTS: The SG had a significantly reduced (mean = 3.2°) error angle ( P = .02) when compared to the direct vision group (mean = 4.8°). However, no significant difference was found between direct vision (mean = 17.5 seconds) and SG arms (mean = 14.9 seconds) in the insertion time. CONCLUSION: While keeping the AP image view in primary focus, simultaneously viewing the lateral side of the surgical field using SG helps achieve more accurate wire insertion in surgery.

The Use of Smart Glasses for Surgical Video Streaming.

Observation of surgical procedures performed by experts is extremely important for acquisition and improvement of surgical skills. Smart glasses are small computers, which comprise a head-mounted monitor and video camera, and can be connected to the internet. They can be used for remote observation of surgeries by video streaming. Although Google Glass is the most commonly used smart glasses for medical purposes, it is still unavailable commercially and has some limitations. This article reports the use of a different type of smart glasses, InfoLinker, for surgical video streaming. InfoLinker has been commercially available in Japan for industrial purposes for more than 2 years. It is connected to a video server via wireless internet directly, and streaming video can be seen anywhere an internet connection is available. We have attempted live video streaming of knee arthroplasty operations that were viewed at several different locations, including foreign countries, on a common web browser. Although the quality of video images depended on the resolution and dynamic range of the video camera, speed of internet connection, and the wearer's attention to minimize image shaking, video streaming could be easily performed throughout the procedure. The wearer could confirm the quality of the video as the video was being shot by the head-mounted display. The time and cost for observation of surgical procedures can be reduced by InfoLinker, and further improvement of hardware as well as the wearer's video shooting technique is expected. We believe that this can be used in other medical settings.

Augmented reality: The use of the PicoLinker smart glasses improves wire insertion under fluoroscopy.

AIM: To demonstrate the feasibility of the wearable smart glasses, PicoLinker, in guide wire insertion under fluoroscopic guidance. METHODS: Under a fluoroscope, a surgeon inserted 3 mm guide wires into plastic femurs from the lateral cortex to the femoral head center while the surgeon did or did not wear PicoLinker, which are wearable smart glasses where the fluoroscopic video was displayed (10 guide wires each). RESULTS: The tip apex distance, radiation exposure time and total insertion time were significantly shorter while wearing the PicoLinker smart glasses. CONCLUSION: This study indicated that the PicoLinker smart glasses can improve accuracy, reduce radiation exposure time, and reduce total insertion time. This is due to the fact that the PicoLinker smart glasses enable surgeons to keep their eyes on the operation field.

[Severe Japanese Spotted Fever Complicated by Acute Respiratory Failure in Kobe City].

We report herein on a case of severe Japanese spotted fever complicated by acute respiratory failure in Kobe City. A 70-year-old female presenting with general malaise and systematic erythema was admitted to our hospital in June, 2013. From her history and physical examination, she was found to be suffering from scleroderma and mild interstitial pneumonia. From admission, the patient was noted to have a fever of 39 degrees C accompanied by relative bradycardia. Physical examination revealed a black eschar on her right leg, making us suspect rickettsial infection since Kobe City is not an area predisposed to Japanese spotted fever. Three days after admission, her condition worsened and treatment with minocycline and levofloxacin was initiated in accordance with the treatment protocol for Japanese spotted fever. The following day, the patient developed acute respiratory distress syndrome (ARDS) and was put on a respirator. She gradually recovered with the antibiotic treatment and was discharged from the hospital 23 days after admission. The diagnosis of Japanese spotted fever was confirmed by conducting a polymerase chain reaction test on the eschar. Japanese spotted fever is noted to occur in any place other than Kobe City. Late diagnoses may result in aggravated cases of Japanese spotted fever, with the possibility of developing ARDS as a complication.

The tail domain of tomosyn controls membrane fusion through tomosyn displacement by VAMP2.

Neurotransmitter release is regulated by SNARE complex-mediated synaptic vesicle fusion. Tomosyn sequesters target SNAREs (t-SNAREs) through its C-terminal VAMP-like domain (VLD). Cumulative biochemical results suggest that the tomosyn-SNARE complex is so tight that VAMP2 cannot displace tomosyn. Based on these results, the tomosyn-SNARE complex has been believed to be a dead-end complex to inhibit neurotransmitter release. On the other hand, some studies using siRNA depletion of tomosyn suggest that tomosyn positively regulates exocytosis. Therefore, it is still controversial whether tomosyn is a simple inhibitor for neurotransmitter release. We recently reported that the inhibitory activity of tomosyn is regulated by the tail domain binding to the VLD. In this study, we employed the liposome fusion assay in order to further understand modes of action of tomosyn in detail. The tail domain unexpectedly had no effect on binding of the VLD to t-SNARE-bearing liposomes. Nonetheless, the tail domain decreased the inhibitory activity of the VLD on the SNARE complex-mediated liposome fusion. These results indicate that the tail domain controls membrane fusion through tomosyn displacement by VAMP2. Deletion of the tail domain-binding region in the VLD retained the binding to t-SNAREs and promoted the liposome fusion. Together, we propose here a novel mechanism of tomosyn that controls synaptic vesicle fusion positively by serving as a placeholder for VAMP2.