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Purpose: Windswept deformity (WSD) of the knee, involving valgus deformity in one knee and varus deformity in the other, is uncommon and not well understood. This study aimed to clarify the radiological characteristics of WSD patients with osteoarthritis. Methods: WSD knees with Kellgren–Lawrence stage 3 or 4 osteoarthritis in 36 patients were radiologically evaluated. Mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), arithmetic hip–knee–ankle (aHKA) angle, and joint line obliquity were measured. Comparisons in radiological measurements were made with 47 patients with bilateral valgus and 135 patients with bilateral varus knee osteoarthritis (control groups). Results: Among WSD patients, 75% had valgus deformity in the right knee, while 25% had it in the left knee. The mLDFA in valgus WSD knees was significantly lower than that in varus WSD knees (85.1 ​± ​2.2° vs. 87.3 ​± ​2.3°; p

Purpose: This study investigated the adequacy of improvements in locomotive syndrome (LS) and other clinical outcomes after total knee arthroplasty (TKA) for medial knee osteoarthritis. Methods: A total of 74 patients who underwent unilateral primary TKA were evaluated pre-operatively and 3, 6, and 12 months post-TKA using the 25-question Geriatric Locomotive Function Scale (GLFS-25) to evaluate the severity of LS, the Japanese Knee Osteoarthritis Measure (JKOM), the Knee Society Score (KSS), the timed up and go (TUG) test, and range of motion of the knee joint (ROM). The GLFS-25 score and the severity of LS were compared between these patients and independent ambulatory community dwellers (273 males and 477 females). Results: The GLFS-25, JKOM, KSS, TUG scores, and ROM significantly improved post-operatively. The pre-operative incidence of LS stage 3, indicating the worst locomotive function, decreased from 81.1% to 24.3% at the final follow-up. However, the median (interquartile range) GLFS-25 score of 13 (6–23) seemed much worse, and the incidence of LS stage 3 of 24.3% seemed much higher even 12 months post-TKA compared with independent ambulatory community dwellers. Conclusions: The GLFS-25 score and other clinical outcome scales significantly improved after TKA. However, improvements in locomotive functions were not adequate as approximately 25% of patients remained with LS stage 3. Besides ordinary rehabilitation programmes after TKA, some interventions, such as more rigorous muscle exercises, would be necessary to obtain greater improvements in LS.

Purpose: In patients with moderate-to-severe bilateral medial knee osteoarthritis, it is difficult to determine the necessity of the subsequent contralateral total knee arthroplasty (TKA) after performing the first procedure. This study aimed to compare patient characteristics and clinical outcomes between patients who underwent staged bilateral TKA (group B) and those who underwent unilateral TKA (group U) to identify predictors of contralateral TKA requirement. Methods: Among 153 patients with bilateral medial knee osteoarthritis of Kellgren-Lawrence grade 3 or 4, 43 and 110 patients underwent unilateral and bilateral TKA, respectively. Clinical evaluations using the patient-reported outcome measure (the Japanese Knee Osteoarthritis Measure [JKOM]), the Knee Society Score (KSS), and the timed “Up and Go” test (TUG) were performed preoperatively, at 12 months, and once every year up to 5 years after the unilateral and the contralateral TKA in groups U and B, respectively. Receiver Operating Characteristic (ROC) analysis was used to determine the cut-off value for preoperative JKOM score that indicates the contralateral TKA. Results: There were no significant differences in patient characteristics between groups B and U. The preoperative JKOM scores were significantly worse in group B. Postoperative improvements in JKOM, KSS, and TUG were statistically significant in both groups; however, there were no significant differences in post-procedure scores between the two groups. ROC analysis showed that the optimal cut-off value of the preoperative JKOM score was 41.5 points. Conclusion: A preoperative JKOM score of ≥41.5 is a possible predictor of the contralateral TKA in patients with moderate-to-severe bilateral medial knee osteoarthritis.

Medial open wedge high tibial osteotomy (OWHTO) is usually performed with proximal tuberosity osteotomy or setting the osteotomy line proximal to the tuberosity. However, OWHTO can result in patellofemoral complications due to postoperative patella infera. A new OWHTO technique, biplanar osteotomy with a distal tuberosity osteotomy, was reported in 2004 to prevent postoperative patella infera. To ensure that the 2 osteotomy lines maintain perpendicular, we describe the OWHTO procedure with a distal tuberosity osteotomy technique using a TriS Medial HTO Plate System (Olympus Terumo Biomaterials Corp., Tokyo, Japan) and a right angle guide we developed. In this Technical Note, we describe the procedure and advantages, risks, and limitations, as well as the pearls and pitfalls based on our experience.

We orthopaedic surgeons are not familiar with the popliteus bursa. It is defined as the expansion in the synovial membrane of the posterolateral part of the knee that lies between the lateral meniscus and the tendon of the popliteus muscle. The popliteus bursa extends approximately 1 cm distal to the joint line and has 4 borders; the medial border is the peripheral margin of the lateral meniscus, the lateral border is the popliteus tendon, and the superior and inferior borders are formed by 2 fascicles. We very rarely observe cystic lesions that expand more distally, such as pigmented villonodular synovitis (PVNS) and synovial osteochondromatosis. We consider the distally expanded bursa as the pathologic expansion of the popliteus bursa. When this expansion is involved with PVNS, it may be the cause of recurrence of PVNS in the knee joint. Synovial osteochondromatosis in this expansion may cause pain in the posterolateral corner of the knee and may become a source of free bodies in the knee joint. In such conditions, these lesions should be surgically excised. The purpose of this Technical Note is to describe a surgical approach to the pathologic expansion of the popliteus bursa.

Purpose. To evaluate the outcome of autologous morselised bone grafting for a medial tibial defect of ≥10 mm deep in 45 total knee arthroplasties (TKAs). Methods. 38 patients aged 46 to 85 (mean, 73) years underwent 45 TKAs and autologous morselised bone grafting for a medial tibial defect of ≥10 (range, 10–25) mm in depth by a single surgeon. In the first 19 TKAs, 2 resected subchondral bone plates from the lateral tibial plateau were driven into 2 gutters made on the floor of the medial tibial defect as bony support posts. Morselised cancellous bone grafts were then impacted around these posts. In the remaining 26 TKAs, multiple drill holes were made on the floor of the defect to decrease the remodelling time. Morselised cancellous bone grafts were impacted to fill the defects. The tibial components were fixed with cemented (n=34) or non-cemented (n=11) technique. Internal fixation devices were not used; stem extension was used in only 2 TKAs (in a patient with Charcot joint and a patient undergoing revision TKA). Results. After a mean follow-up duration of 65 (range, 24–174) months, no patient showed gait disturbance. The mean knee flexion angle was 113.8° (range, 90°–130°). No absorption or collapse of the grafted bone, or component loosening were noted on radiographs. The grafted bone completely incorporated into the host bone, with bony trabeculae crossing the interface within 2 years in the first 19 TKAs and within one year in the latter 26 TKAs. The margin of the grafted area resembled bony cortex in 30 TKAs. Conclusion. Autologous morselised bone grafting is a viable option for most medial tibial defects during TKA.

Recently, a remnant-preserving anterior cruciate ligament (ACL) reconstruction technique has been developed. However, the pre-operative condition of remnant ACL is occasionally difficult to evaluate by magnetic resonance imaging. The purpose of this study is to evaluate the accuracy of pre-operative visualization of remnant ACL using three-dimensional computed tomography (3D-CT). The remnant ACL in 25 patients was examined by 3D-CT before ACL reconstruction surgery. Findings on 3D-CT images and arthroscopy were compared. The 3D-CT images were classified into 4 groups: Group A, remnant fibers attached to the posterior cruciate ligament (PCL); Group B, those located between the PCL and the lateral wall; Group C, those attached to the lateral wall; and Group D, no identifiable remnant fibers on the tibial side. These groups were made up of 4, 3, 9 and 9 patients, respectively. Findings on 3D-CT images were identical to those during arthroscopy in 20 of 25 cases (80%). Remnant ACL can be accurately evaluated using 3D-CT in 80% of cases of torn ACL. This novel method is a useful technique for pre-operative assessment of remnant ACL.

We report the second case of osteochondritis dissecans (OCD) of the knee in identical twins (bilaterally in one and unilaterally in the other). Fixations with bio-absorbable pins, cylindrical osteochondral graft, and osteochondral mosaicplasty were all successful and bone union was achieved. We considered that genetic factors remain essential even if other factors (particularly repetitive trauma) are mainly responsible for the occurrence of OCD.

Articular cartilage is a specific type of connective tissue composed of hydrated proteoglycans within a matrix of collagen fibrils. In the elderly population, it shows degenerative changes that may results in osteoarthritis. The more severe form of osteoarthritis occasionally demonstrates bone formation within the cartilage, which is designated as a bony protuberance, however, such lesions are rare in children. This report presents the case of a 10-year-old boy with a bony protuberance within the articular cartilage of the knee. The patient initially complained of knee pain and he subsequently developed flexion contracture. Radiological and arthroscopic examinations revealed a bony protuberance in the articular cartilage and degenerative changes of the cartilage above it. He was successfully treated by the removal of the bony protuberance and osteochondral grafting. The bony protuberance may have caused cartilage degradation since the thickness of the cartilage above it was thinner than that around the lesion. The bony protuberance within the articular cartilage formed in the younger population may be a possible cause of osteoarthritis. This case is a noteworthy with regard to the pathogenesis of osteoarthritis.