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The tibial resection depth during total knee arthroplasty for valgus knees has been variously described and not been standardized yet. Accordingly, it has been proposed in this article, that the sulcus between the medial and lateral intercondylar tibial tubercles can be used as a reference point for the tibial resection depth. The resection can be performed 8 to 9 mm distal to the sulcus.

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., Technique Video Video 1 A right angle guide for distal tuberosity osteotomy with medial open wedge high tibial osteotomy for varus knee osteoarthritis. Medial open wedge high tibial osteotomy (OWHTO) is recognized as a very useful treatment option for varus knee osteoarthritis. In this Technical Note, we describe the OWHTO procedure with the distal tuberosity osteotomy (DTO) technique using a TriS Medial HTO Plate System and a right angle guide we developed. The TriS Medial HTO Plate System is composed of a locking plate with 8 holes (A-D in the proximal part and I–IV in the distal part) and 8 cannulated locking screws. A right angle guide consists of two 1-mm thick stainless-steel plates (Plate I and Plate II) that are joined together at a right angle. The 2 ends of Plate I are referred to as the right and left wings. This video shows medial OWHTO with distal tuberosity osteotomy on the right tibia. The patient is placed in the supine position on the operating table. A skin incision starts 3 to 4 cm distal to the tibial tuberosity and near the tibial crest and continues proximally and posteriorly 1 to 2 cm distal to the knee joint line. After retraction of the skin and subcutaneous fatty tissue, the deep fascia, together with the semitendinosus and gracilis tendons, is then incised in an L-shaped fashion. The distal border of the incision is along the inferior border of the semitendinosus tendon. The incised fascia is reflected proximally to expose and completely release the superficial layer of the medial collateral ligament. After releasing the posterior periosteum of the tibia with a Cobb-type spinal elevator, a radiolucent retractor is then subperiosteally inserted just posterior to the tibia to protect the popliteal neurovascular structures. Next the first osteotomy, that is, medial OWHTO, is performed. Before the first osteotomy, 2 Kirschner wires are inserted in parallel to serve as guide pins. We usually fit the trial locking plate to the tibia and place the insertion point between holes D and I under fluoroscopic control. The 2 Kirschner wires are inserted using a parallel guide under fluoroscopic control. The direction of the wires is the proximal tibiofibular joint. The first osteotomy is also performed under fluoroscopic control using an oscillating saw with a 1.27-mm thick blade and osteotomes inserted along the distal surface of the 2 Kirschner wires. The end of the first osteotomy is about 5 mm medial to the lateral tibial cortex. Next, the right wing of Plate I is inserted into the first osteotomy line, and then the second osteotomy is performed along the upper surface of Plate II using an oscillating saw with a 1.27-mm thick blade, a reciprocating saw with a 0.8 mm thick blade, and osteotomes. After completion of both osteotomies, which is confirmed with the use of a metal ruler, the first osteotomy site is opened. At first, 5 osteotomes are inserted one by one in order to gradually open the osteotomy site. An HTO opener is then inserted to open the site to the desired distance as preoperatively calculated. When opening the first osteotomy site, it is necessary to check whether a gap had formed or not at the second osteotomy site. The accuracy of the acquired coronal alignment is determined under fluoroscopic control as to whether the mechanical axis (from the center of the femoral head to the center of ankle joint) passes through a point of 60% to 70% of the medial to lateral width of the tibia, which is examined using a metal alignment rod. Then, an artificial bone, β-tricalcium phosphate (β-TCP), is inserted into the first osteotomy site. At first, a 10-mm long β-TCP wedge with 60% porosity and an appropriate width (equal to the osteotomy gap) is inserted into the posterior and peripheral part of the osteotomy gap. Next, the second osteotomy site is fixed with a 4-mm diameter cannulated cancellous screw and a washer. β-TCP granules with 75% porosity are then stuffed into the osteotomy gap. Finally, a β-TCP wedge of an appropriate width and 10 mm in length is inserted at the anterior and peripheral part of the osteotomy gap. The released superficial layer of the medial collateral ligament is only repositioned onto the tibial surface. The reflected deep fascia is sutured to the surrounding soft tissue to cover the first osteotomy gap and to repair the semitendinosus and gracilis tendons. Finally, the first osteotomy site is fixed with a locking plate and 8 cannulated locking screws. Upon completion of the procedure, an aspiration device is set and the subcutaneous fatty tissue and skin are closed.

Background The efficacy of morphine added to periarticular multimodal drug injection (PMDI) for pain management after total knee arthroplasty (TKA) is controversial. Adding morphine to spinal anesthesia has reportedly improved pain relief for the first 24 h. We examined the effect of morphine added to PMDI or spinal anesthesia on pain management and functional recovery after TKA. Methods A total of 97 patients were randomized into three groups: in Group A (34 patients), 10 mg morphine was added to PMDI; Group B (31 patients), 0.1 mg morphine was added to spinal anesthesia; and Group C (32 patients), morphine was added to neither the PMDI nor spinal anesthetic. To evaluate the efficacy of added morphine for pain management, we assessed rest pain, the number of times analgesics were used, and the time period until the first analgesic use. The adverse effects of morphine were assessed by counting the numbers of times vomiting occurred and antiemetics were used. Functional recovery was evaluated by recording the range of motion of the knee and the date of ability to walk. Results Rest pain was the least in Group B at 6 and 12 h after operation. The number of times analgesics were used was the least in Group B. The time period until the first analgesic use was the longest in Group B. The number of vomiting episodes was the least in Group C. The number of times antiemetics were used was higher in Group A than in Group C. There were no significant differences in the range of motion and date of ability to walk among the three groups. Conclusions The efficacy of morphine added to PMDI was limited, and that of morphine added to spinal anesthesia disappeared within 20 h postoperatively. Adding morphine to PMDI or spinal anesthesia did not improve functional recovery and caused some adverse effects.

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.

Recently, the Japanese knee osteoarthritis measure (JKOM), a new disease-specific and patient-derived quality of life (QOL) measure, has been developed. The objectives of this study were to longitudinally evaluate QOL assessed by JKOM and objective outcomes including knee society score (KSS), range of motion (ROM), and timed up and go test (TUG) of patients who underwent bilateral total knee arthroplasties (TKAs) for osteoarthritis; to evaluate correlations between JKOM and those objective outcomes; and to test our hypothesis that increased maximum flexion leads to better JKOM. Forty patients with bilateral TKAs and ≥ 3-year follow-up were included. There were 35 female and 5 male patients with a mean patient age of 74 years. They were evaluated preoperatively (Pre), 5–29 months after unilateral TKA (after U), 12–21 months after bilateral TKAs (1 year after B), 24–34 months after bilateral TKAs (2 years after B), and 36–46 months after bilateral TKAs (3 years after B) using JKOM, KSS, TUG, and ROM. Improvements in JKOM and TUG were statistically significant between “Pre” and “after U”, and between the “after U” and “1 year after B”. Improvements in the KSS function score were statistically significant between “after U” and “1 year after B” but not between “Pre” and “after U”. The improvements in the JKOM scores, the KSS function score, and TUG did not increase after the 1-year follow-up but was maintained at “3 years after B”. The maximum flexion value did not change among the evaluation time points. There were statistically significant correlations between JKOM with KSS and TUG but not with ROM. There were statistically significant correlations between JKOM with KSS and TUG but not with ROM. Therefore, our hypothesis was false even in a Japanese population.

Bone marrow lesions (BMLs) on magnetic resonance (MR) images in knee osteoarthritis patients are considered to predict the severity and progression of the disease. We evaluated the histological findings of BMLs on MR images of the subchondral area of the medial femoral condyle in varus osteoarthritic knees. In 24 patients with varus knee osteoarthritis who underwent total knee arthroplasty (TKA), sagittal T1- and T2-weighted MR images of the affected knee were acquired before TKA. During TKA, resected bone pieces from the distal medial femoral condyle were obtained. Sagittal specimens obtained from the center of the bone pieces were histologically examined. Twenty patients had BMLs. Histological findings of BMLs in the subchondral area showed various features, such as fibrovascular tissue, cyst formation, active bone remodeling with bone formation and bone resorption, and hyaline cartilage. BMLs were not found in four patients; histological findings of these patients showed normal bone marrow tissue with normal-thickness trabeculae. Subchondral bony end plate in knees with BMLs was usually thin or destroyed, while that without BMLs was thick or normal. The condition of the subchondral bony end plate would explain the differences in the severity and progression between patients with or without BMLs.

Background Precise matching of the tibial component and resected bony surfaces and proper rotational implanting of the tibial component are crucial for successful total knee arthroplasty. We aimed to analyze the exact anthropometric proximal tibial data of Japanese patients undergoing total knee arthroplasty and correlate the measurements with the dimensions of current total knee arthroplasty systems. Methods A total of 703 knees in 566 Japanese patients who underwent total knee arthroplasty for osteoarthritis were included. The bone resection in the proximal tibia was performed perpendicular to the tibial axis in the frontal plane. Measurements of the proximal tibia were intraoperatively obtained after proximal tibial preparation. Results There were significant positive correlations between the lateral anteroposterior and medial anteroposterior and mediolateral dimensions. A progressive decrease in the mediolateral/lateral anteroposterior ratio with an increasing lateral anteroposterior dimension or the mediolateral/anteroposterior ratio with an increasing anteroposterior dimension was observed. The lateral anteroposterior dimension was smaller than the medial anteroposterior dimension by a mean of 4.8 ± 2.0 mm. The proximal tibia exhibited asymmetry between the lateral and medial plateaus. A comparison of the morphological data and dimensions of the implants, one of which was a symmetric tibial component (NexGen) and the others were asymmetric (Genesis II and Persona), indicated that an asymmetric tibial component could be beneficial to maximize tibial plateau coverage. Conclusions This study provided important reference data for designing a proper tibial component for Japanese people. The proximal tibial cut surface was asymmetric. There was wide dispersion in the lateral anteroposterior, medial anteroposterior, and mediolateral dimensions depending on the patient. Our data showed that the tibial components of the Genesis II and Persona rather than that of the NexGen may be preferable for Japanese people because of their asymmetric design.

It is well known that anterior cruciate ligament (ACL) injuries are commoner in female athletes. Accordingly, we hypothesized that serum estrogen may play some role in this sex difference. We evaluated the relationship between serum estrogen levels and the mechanical properties of the ACL in rabbits.In 40 ovariectomized rabbits, the serum estrogen levels (SEL) were controlled by intramuscular injection of 17beta-estradiol. The mean SEL in each rabbit was defined as the average of 5 determinations done at 1, 2, 3, 4 and 5 weeks after ovariectomy. The animals were divided into 4 groups according to the dose of estradiol administered (low, medium, high and control: L, M, H and C, respectively) and into 2 groups according to the mean SEL (high-SEL group and low-SEL group). The medial portions of ACL attached to both femur and tibia harvested at 5 weeks after ovariectomy were examined mechanically.The mean serum estrogen levels in groups C, L, M and H were 37, 50, 60 and 231 pg/mL. Statistically significant differences in the mean serum estrogen levels were seen among the 4 groups, except between groups L and M. Statistically significant differences were found between groups M and H in both the ultimate tensile stress and linear stiffness. In the comparison between 2 groups using the mean SEL value, both ultimate tensile stress and linear stiffness were lower in the high-SEL group. In all animals, a positive correlation was found between ultimate tensile stress and linear stiffness.Our findings suggest that high SEL might be one of the factors in the multifactorial pathogenesis of ACL rupture.

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.

In 671 knees of 351 patients, the proximal tibiofibular joint was radiologically investigated. To clearly detect the contour of the joint, radiographs were obtained under fluoroscopic control with the lower extremity internally rotated. The contour was classified into three types: the joint lines of both tibia and fibula are straight (A); the joint line of the fibula is convex (B); the joint line of the tibia is convex (C). The rotation and the inclination of the joint were measured. Of the 671 knees, CT examination was also carried out in 51 knees. The obliquity of the joint was measured and the location of the fibula as related to the tibia was evaluated by CT. We also examined the relationships between the contour and the rotation, inclination, obliquity of the joint and the location of the fibula, and determined the characteristics of type B and C as compared with type A. The characteristics of type B were as follows: (1) this type was mainly seen in younger patients, (2) the rotation was the lowest and the inclination was the highest among the three types, (3) in CT the joint line was more saggital and the fibula was located more anteriorly. The characteristics of type C were as follows: (1) this type was seen in older patients, (2) the rotation was the highest and the inclination was the lowest among the three types, (3) in CT the joint line was more frontal and the fibula was located more posteriorly.

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.

Previous epidemiological studies revealed that anterior cruciate ligament (ACL) injuries were more frequently seen in female athletes than in male athletes. To elucidate the pathogenetic roles of estrogen in ACL ruptures, the elasticity of ACL tissue was measured using a scanning acoustic microscope (SAM) in an estrogen-controlled animal model.A total of 40 ovariectomized Japanese white rabbits were randomly divided into four groups according to the administered dose of 17beta-estradiol (groups L, M, H, and C). Injection of 17beta-estradiol was performed 1, 2, 3, and 4 weeks after surgery, and doses in groups L, M, and H were 50, 100, and 500 microg/kg, respectively. Group C received no estradiol. Only groups L, M, and C were used for current analyses because their mean serum estrogen levels were within the physiological range (groups C, L, M, and H: 37, 50, 60, and 231 pg/ml, respectively). Five weeks after ovariectomy, the lateral portion of the ligament was harvested. Specimens were fixed with 10% neutralized formalin and embedded in paraffin. Then, 10 mum thick sections were cut perpendicular to the ligament fibers for routine histological staining and measurement with SAM.The mean tissue sound speeds of groups C, L, and M were 1727 +/- 32, 1683 +/- 53, and 1665 +/- 63 m/s, respectively. Group M presented significantly lower tissue sound speed than group C (P = 0.021). Furthermore, a negative correlation was found between the mean serum estrogen level and mean tissue sound speed of the ACL among all animals in groups C, L, and M (r = 0.47, P = 0.016).The results of the present study indicated that estrogen altered the tissue elasticity of rabbit ACL. Estrogen may constitute one of the pathogenetic factors in ACL rupture in female athletes.

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been used to examine muscle activity during running. The dash is a basic activity in various kinds of sports but differs from running in terms of intensity and severity. The purpose of this study was to evaluate muscle activity during running at full speed using FDG PET.Six healthy men were investigated during a dash for 10 min after intravenous injection of FDG (37 MBq). Another six healthy men were studied as controls. PET images were obtained 45 min after the FDG injection. Regions of interest were drawn on the anterior and posterior thighs and the anterior and posterior legs. The standardized uptake value (SUV) was calculated to examine the FDG uptake of muscle tissue per unit volume according to an equation.In the control group, the mean SUVs of the anterior thigh, posterior thigh, anterior leg, and posterior leg were 0.49 +/- 0.04, 0.44 +/- 0.02, 0.46 +/- 0.05, and 0.44 +/- 0.07, respectively. In the dash group, the mean SUVs of the anterior thigh, posterior thigh, anterior leg, and posterior leg were 0.74 +/- 0.20, 0.79 +/- 0.08, 0.61 +/- 0.07, and 0.60 +/- 0.08, respectively. FDG accumulation of every one of the four compartments in the dash group was significantly higher than that in the control. FDG accumulation of the posterior thigh was significantly higher than that of the anterior and the posterior leg in the dash group (P0.02).Based on the results of our investigation, posterior thigh muscles were especially active during a dash.