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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.

Although many studies have been performed to evaluate the quality of life (QOL) and patient satisfaction after total knee arthroplasty (TKA), almost all evaluations were performed in patients after unilateral TKA or in patients after mixed unilateral and bilateral TKA. Accordingly, this study aimed to evaluate QOL after staged bilateral TKA. A total of 78 patients who underwent staged bilateral TKA for varus knee osteoarthritis were included in this study. All patients had longitudinal follow-up evaluations for at least five years. QOL was assessed by the Japanese Knee Osteoarthritis Measure (JKOM), a disease-specific and patient-derived QOL measure for Japanese patients. Conventional objective outcome scales, including the Knee Society Score and the Timed Up and Go test, were also assessed. In addition, QOL and objective outcomes were compared between the younger (≤ 80 years, average 75.8 years) and older (> 80 years, average 84.7 years) age groups at the final follow-up. Improvements in both JKOM and objective outcomes reached a plateau one year after staged bilateral TKA. Improvements were prolonged for more than five years. There were no statistically significant differences in JKOM or objective outcomes between the younger and older age groups, despite an 8.9-year difference in the average age. This was the first longitudinal study to evaluate QOL and objective outcomes after staged bilateral TKA for a period of at least five years. Improvements in QOL and objective outcomes reached a plateau one year after staged bilateral TKA and were prolonged for more than five years. No significant differences were observed in outcome scores between the younger and older age groups.

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.

Recent studies have suggested radial displacement of the medial meniscus as a cause of varus knee osteoarthritis (OA). Two anatomical studies reported that such displacement may be associated with anterior insertion of the medial meniscus anterior horn. It was aimed to evaluate the location and area of this insertion in patients with advanced knee OA. Medial meniscus anterior horn insertions were classified into four types, as described in a previously reported classification during 225 total knee arthroplasty (TKA) in 184 patients. The incidence rates of insertion type were compared with previously reported rates in nearly normal or non-arthritic knees. The insertion surface area was also measured during 158 TKAs. Of the 225 knees, 82 (36.4 %), 93 (41.3 %), 35 (15.6 %), and 15 (6.7 %) were classified as I, II, III, and IV, respectively. An anteriorly inserted anterior horn was not more frequent in advanced varus OA knees than in previously reported nearly normal or non-arthritic knees. The insertion surface areas were 57.5 ± 18.9, 56.1 ± 16.0, and 56.4 ± 14.4 mm2 for types I, II, and III, respectively; these areas did not differ significantly. Since the incidence of an anteriorly inserted medial meniscus anterior horn was not higher in advanced varus OA knees than in normal or non-arthritic knees, an anteriorly inserted anterior horn may have little or no effect on the aetiology of varus OA knees. This study provides some information for clarifying the aetiology of knee OA. IV.

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.

This study reports a case series of 44 primary total knee arthroplasties (TKAs) using autogenous morcellised bone grafting for large (≥10-mm-deep) medial tibial defects, which are generally repaired using metal augmentation. The bone-grafting technique is described in detail and the radiological outcomes are presented. A total of 44 TKAs were followed up for a mean period of 58 months (range 24–139 months). Multiple drill holes were made in the sclerotic floor of the defect, followed by the impaction of morcellised cancellous bone grafts to fill the defects. Tibial components were fixed using the cemented or noncemented technique and no internal fixation devices were used. Stem extension of the tibial component was only used in one TKA. Radiograms revealed that the grafted bone was completely incorporated into the host bone within one year post-operatively. No grafted bone absorption or collapse was detected. A clear zone between the tibial component and grafted bone was observed in six knees, but it did not become enlarged thereafter. The presented technique provided favourable radiological outcomes and had several advantages: (1) it enables preservation of as much bone as possible for future revision surgery; (2) it is cost effective and simple because metal augments, internal fixation devices and stem extension are not needed; (3) it can be used in the same manner any defect to a depth ≥3 mm. Thus, this is an acceptable and reproducible alternative technique.

The present study focused on the prevalence of incidental excision of the femoral footprint of the popliteus tendon during total knee arthroplasty and its associated risk factors. A total of 275 knee arthroplasties were performed for 226 patients with varus knee osteoarthritis. The status of the femoral footprint of the popliteus tendon was intraoperatively evaluated and classified into three groups (preserved, partially excised, and completely excised), and the prevalence of the excision was identified. Femoral component size, the thickness of the resected distal femoral condyle, and preoperative patient demographic data were compared for the three groups. Ordinal logistic regression analysis was performed to reveal risk factors associated with the excision. The femoral footprint of the popliteus tendon was preserved in 132 knees (48.0 %), partially excised in 94 knees (34.2 %) and completely excised in 49 knees (17.8 %). The ordinal logistic regression analysis revealed thicker resection of the distal femoral condyle (p

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.

The objective of this study was to work with a consecutive series of patients having Hospital for Special Surgery scores higher than 90 to evaluate kinematic patterns, under in vivo conditions, for 20 Japanese subjects implanted with 2 different mobile-bearing (MB) total knee arthroplasties (TKAs). Femorotibial contact paths for the medial and lateral condyles were then determined using a computer-automated model-fitting technique. This present study has shown that kinematic patterns for subjects having 2 different MB TKA designs differed but were not statistically different. Subjects implanted with a rotating platform (RP) MB TKA experienced minimal anteroposterior (AP) motion and larger axial rotation (RP). Subjects implanted with an anterior glide MB TKA experienced both femoral rotation and femoral translation (AP glide). There was minimal variability in the kinematic patterns for subjects implanted with an RP, whereas subjects implanted with an AP glide experienced more variable kinematic patterns. Key words: total knee arthroplasty, in vivo, fluoroscopy, kinematics.

Four knees in three patients with traumatic separation of a Type I bipartite patella are reported. Sudden anterior knee pain and an audible pop occurred at the time of the injury and the patients had aching or dull pain before the traumatic episode. Previous aching or dull pain led us to differentiate this type of injury from a usual transverse fracture. A round fracture line seen on the radiographs also led us to differentiate this type of injury from a stress fracture. Accordingly, the diagnosis of a traumatic separation of a Type I bipartite patella was confirmed. This is the first report of a traumatic separation of a Type I bipartite patella to our knowledge.

Five patients with pigmented villonodular synovitis of the knee associated with lesions of the posterior periarticular bursae were treated by posterior exploration, excision of the bursal tissue, and routine anterior synovectomy of the knee. It was hypothesized that complete excision of the posterior periarticular bursae would reduce the high recurrence rate of pigmented villonodular synovitis of the knee. To completely excise the periarticular lesions, two posterior oblique skin incisions were used. In all patients, periarticular lesions were seen clearly on computed tomography scans after air arthrography and on magnetic resonance imaging scans. The patients were followed up for 6.9 years on average (range, 3.3-8.1 years) after surgery. One of five patients required reoperation because of recurrence. Two of five patients required manual mobilization after release of the intraarticular adhesion. However, in the remaining three patients, who started continuous passive motion exercise immediately after surgery, full range of motion was restored within 3 months after the operation. Complete excision of the periarticular lesions is recommended to reduce the high recurrence rate, and continuous passive motion exercise immediately after surgery also is recommended to prevent reduction of range of motion.

We present 12 cases of patients with injury to the posterolateral aspect of the knee accompanied by a compression fracture of the anterior part of the medial tibial plateau. There were 11 male patients and 1 female patient with an average age of 26 years (range, 17 to 44 years). There were 4 cases of posterolateral rotatory instability and 8 cases of straight lateral instability of the knee. The size of the compression fracture was classified into 2 types, small (8 cases) and large (4 cases). Although the mechanism of injury was considered to be hyperextension and varus force, the pattern of cruciate ligament injuries varied from case to case. The following 3 questions should be considered to determine which cruciate ligament is damaged: (1) Was the ipsilateral foot fixed to the ground? (2) Was forward inertia involved? (3) Was there a direct blow to the anteromedial aspect of the tibia or to the femur? Accompanied fractures of the medial tibial plateau were considered to have been compressed by the medial femoral condyle. The size of the accompanying compression fracture varied; 7 of 8 cases with a small-type fracture had posterior cruciate ligament injuries and 3 of 4 cases with a large-type fracture had anterior cruciate ligament injuries. The size of the fracture is determined by which point of the medial tibial plateau touched the medial femoral condyle. We propose that a compression fracture of the anterior part of the medial tibial plateau indicates a coexistent posterolateral aspect injury, and that especially a small compression fracture strongly suggests an accompanying posterior cruciate ligament injury, as well.

The position of the fibula around the proximal tibia varies in different people; it was therefore hypothesized that this variation would affect the orientation of the lateral collateral ligament and the popliteofibular ligament complex. This hypothesis was studied in 10 cadaveric knees by measuring the orientation and length changes in these structures as the knee was flexed. The data were correlated with tibiofibular joint position. The strength of the ligaments was also tested. There were significant correlations between fibular head position and ligament orientation with the knee extended. The lateral collateral ligament slackened significantly with knee flexion, whereas the popliteofibular ligament complex did not. The structures became significantly steeper in the sagittal plane as the knee was flexed. The lateral collateral ligament passed through vertical at 70° of knee flexion and was thus poorly oriented to withstand tibial external rotation. The lateral collateral and popliteofibular ligaments had tensile strengths of 309 and 186 N, respectively. The popliteofibular ligament is dominant when the knee is flexed, because of the slackening of the lateral collateral ligament, and so it should always be reconstructed. The anatomic variation causes some knees to have better ligament orientations to withstand posterolateral tibial displacements and, conversely, other knees may be inherently more difficult to stabilize by reconstruction.

The macroscopic and histologic findings for 31 medial menisci and medial tibial plateaus obtained during total knee arthroplasty were examined to clarify the etiology and progression of varus osteoarthritis. Medial menisci were preserved fairly well in cases of severe osteoarthritis in which the medial joint space had already disappeared. The anterior segment was preserved in 26 (84%) menisci and the posterior segment was preserved in 11 (35%). The medial meniscus may have been preserved because of its radial displacement. Exposure of subchondral bone of the medial tibial plateau occurred in all 31 knees. The exposure of subchondral bone was centered in the anterior, middle, and posterior in nine, 10, and 12 medial tibial plateaus, respectively. There was a mechanical inconsistency between the pattern of preservation of the medial menisci and the location of exposure of subchondral bone on the medial tibial plateaus. The inconsistency reflects that the segment of the medial meniscus on which the excessive load was considered to exist was preserved fairly well. The authors' hypothesis for explaining this inconsistency is that radial displacement of the medial meniscus precedes narrowing of the medial joint space during progression of varus osteoarthritis, so that the displaced meniscus is saved from severe degeneration or attrition.

There is an argument regarding the aetiology and pathology of the so called `dorsal defect of the patella'. We present three cases discussing pathological macro and microscopical findings and conclude that the aetiology is an ischemic episode followed by subchondral collapse and consequent active reparative reaction.

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.

The objective of this study was to determine the effect of patellar morphology and implant design on patellofemoral contact stress in total knee arthroplasty (TKA) without patellar resurfacing. Radiographic investigation: One hundred and fifty-seven knees of 127 patients were included in the study. Implants used in the present series were Low Contact Stress (LCS), Genesis II and NexGen. The relationship between the pre-operative patellar facet angle and newly identified post-operative osteosclerosis was assessed. Finite element analysis: Using patient-specific patellar three-dimensional finite element models, the relationship between the patellar facet angle and mean von Mises stress within the patella was calculated at flexion angles of 15°, 45°, 75° and 105°. Radiographic investigation: Post-operative osteosclerosis was observed with decreasing patellar facet angle in the Genesis II (odds ratio = 0.72; 95% confidence interval, 0.55–0.93; P = 0.012) and NexGen implants (odds ratio = 0.87; 95% confidence interval, 0.77–0.99; P = 0.029). Patients treated with the Genesis II had significantly more advanced osteosclerosis than those treated with the other two implants. Finite element analysis: A negative correlation was found between the patellar facet angle and the mean von Mises stress for all three implants. The Genesis II showed significantly higher von Mises stress than the other two implants at flexion angles of 15°, 45° and 105°. Both patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing. Case control study, Level III.

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.

Purpose This study aimed to document the incidence of medial plicae (plica synovialis mediopatellaris) in a large sample of the Japanese population and classify them in a type-dependent manner. Methods The incidence of medial plicae was investigated during arthroscopic surgery of 3,889 knee joints in 3,563 patients (mean age, 35 years); medial plicae were classified according to Sakakibara's classification (type A, a cord-like elevation in the synovial wall; type B, a shelf-like appearance; type C, a large shelf-like appearance covering the anterior surface of the medial femoral condyle; and type D, double insertions into the medial wall or having a central defect). Of all the knee joints examined, 2,006 knees belonged to male patients and 1,883 to female patients. Both knee joints were examined in 326 patients. From these data, the incidence of medial plicae was calculated. Results The overall incidence rate of medial plicae was 79.9%. The incidence of Sakakibara type A, B, C, and D medial plicae was 35.2%, 22.4%, 12.3%, and 10.0%, respectively. This pattern was reflected in all age groups in both genders, except in women aged 20 to 39 years. The κ coefficient was moderate, at 0.407, in the patients in whom both knee joints were examined. Conclusions In a large cohort of Japanese patients undergoing arthroscopic knee surgery, the incidence of medial plica was 79.9%. The same pattern was seen in almost all age groups and in both genders (type A > type B > type C > type D). Level of Evidence Level IV, prognostic case series.

Background The histologic findings of osteochondritis dissecans of the knee vary widely, leading to differences in the interpretation of its origins. Hypothesis The differences in the histologic findings of osteochondritis dissecans might represent a course of pathologic progression. Study Design Descriptive laboratory study. Methods Twelve knees in 11 patients (average age, 16 years) with osteochondritis dissecans of the medial femoral condyle were treated by biological internal fixation. During the surgery, cylinder osteochondral plugs were taken from the center of the osteochondritis dissecans lesion and examined with light microscopy. Results A complete or partial cleft separated the specimens into 2 parts: basal and fragment sides. The surface of the basal side was covered with dense fibrous or cartilaginous tissue and active bone remodeling was found beneath the surface. In the fragment side, the deep surface was also covered with dense fibrous or cartilaginous tissue and the articular surface consisted of normal articular cartilage. The area between these 2 surfaces could be classified into 3 types: (1) necrotic subchondral trabeculae, (2) viable subchondral trabeculae, and (3) cartilage without bone trabeculae. Conclusion Based on the histologic findings of this study, the following origins and the pathologic progression of osteochondritis dissecans might be assumed: the initial change in the subchondral area is bone necrosis or subchondral fracture; the necrotic bone is then absorbed and replaced either by viable subchondral trabeculae or cartilage without bone trabeculae. Clinical Relevance The results of this histologic study provide readers with several insights about the causes and treatment options of osteochondritis dissecans.

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.

This study describes the soft X-ray examinations of 24 lateral tibial plateaus obtained during total knee arthroplasty for varus osteoarthritis. The average thickness of the articular cartilage was 3.5 min and ranged from 2.1 to 5.0. We considered that 21 out of the 24 lateral tibial plateaus had well preserved articular cartilage. Within the well preserved articular cartilage, bony protuberances of various sizes were found in five cases. All lateral tibial plateaus except one showed osteophyte formation. We considered that 12 of the 24 lateral tibial plateaus had large osteophytes. Ten of these 12 lateral tibial plateaus had well preserved articular cartilage. Large osteophyte formation may not necessarily be a contra-indication of high tibial osteotomy (HTO) or unicompartmental knee arthroplasty (UKA). Cases with a bony protuberance may not be suitable for HTO or UKA, because the overlying articular cartilage is thin and inadequate for supporting load.

This study examined the relationship between the bone quality of the proximal tibia, which was quantitatively investigated by histomorphometric method at the time of total knee arthroplasty, and the occurrence of loosening of an all-polyethylene tibial component in nine rheumatoid arthritis patients. Despite severe osteoporosis, there was no loosening after 12.8 years. These results suggest that even severe osteoporosis does not influence the occurrence of loosening of a cemented, all-polyethylene tibial component in rheumatoid patients with low activity levels. We recommend the use of all-polyethylene tibial component for low-activity patients.

Sleeve fracture of the upper pole of the patella in an adult with osteogenesis imperfecta Taro Kakazu a,∗, Hitoshi Tatemoto b, Masanori Kawamura b, Takehiko Sugita a a Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, 980-8574 Sendai-City, Japan b Department of Orthopaedic Surgery, Iwate Prefectural Central Hospital, 1-4-1 Ueda, Morioka-City 020-0066, Japan

This study proposes that the mechanism of traumatic posterior dislocation of the hip (TPDH) is a brake pedal injury rather than a dashboard injury. A total of 168 cases of TPDH were treated during the past 10 years. Clinical records of 48 patients, who were drivers and suffered from a head-on collision accident, were examined. The right hip was involved in 45 cases. A total of 31 cases were not accompanied by knee injuries. In 11 cases with foot or ankle injuries and right hip dislocation, 10 had right foot or ankle injuries. If the mechanism of TPDH was a dashboard injury, the left hip would be involved more frequently and there would be more knee injuries. Our hypothesis about the mechanism is that, in a head-on collision, the driver presses desperately on the brake pedal with his right hip slightly flexed, adducted and internally rotated.