Introduction. The management of young patients with painful medial compartment osteoarthritis remains controversial. Opening wedge medial high-tibial osteotomy using a locking plate has shown good results in selected patients. This cohort of patients has high physical demands and previous studies have warned against operating on patients with increased body mass index (BMI). Patients and Methods. Thirty five patients undergoing valgus high tibial osteotomy between Oct 2004 and Feb 2010. Surgical outcome was assessed using Oxford Knee score, pre- and post-operative pain scores, change in employment and patient satisfaction. Results. Mean age at the time of surgery was 41 (22 to 62), mean BMI was 30.9 (21 to 43) and mean Oxford score was 37/48 (16 to 48). Patients rated their overall satisfaction as 7.9/10. Three patients were lost to follow-up, two patients died of unrelated disease. Fifteen (50%) patients had heavy manual jobs and of these 12 (80%) returned to their previous employment post-operatively within 6 months. Seven patients had a BMI > 35 (Mean 39) with a mean weight of 126 Kg (105Kg to 144Kg). These patients had a mean Oxford Score of 42/48 and overall satisfaction of 90%. Pain improved from 8.4/10 pre-op to 1.5/10 post-op (P < 0.0001). None had further procedures. Conclusion. Opening wedge high-tibial osteotomy offers a successful alternative treatment of medial osteoarthritis in young patients with high BMI who place high demands on their knees

Tibial component loosening is an important failure mode in unicompartmental knee arthroplasty (UKA) which may be due to the 6–8 mm of bone resection required or the limited surface area. To address component loosening and fixation, a new Early Intervention (EI) design is proposed which reverses the traditional material scheme between femoral and tibial components. That is, the EI design consists of a plastic inlay component for the distal femur and a thin metal plate for the proximal tibia. With this reversed materials scheme, the EI design requires minimal tibial bone resection compared to traditional UKA to preserve the dense and stiff bone in the proximal tibia. This study investigated, by means of finite element (FE) simulations, the potential advantages of a thin metal tibial component compared with traditional UKA tibial components, such as an all-plastic inlay or a metal-backed onlay. We hypothesized that an EI component would produce comparable stress, strain, and strain energy density characteristics to an intact knee and more favorable values than UKA components. Indeed, the finite element results showed that an EI design reduced stresses, strains and strain energy density in the underlying support bone compared to an all-plastic UKA component. Analyzed parameters were similar for an EI and a metal-backed onlay, but the EI component had the advantage of minimal resection of the stiffest bone.

Introduction

The management of degenerative arthritis of the knee in the younger, active patient presents a challenge to the orthopaedic surgeon. Surgical treatment options include: high tibial osteotomy (HTO), unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). The aim of this study was to examine the long-term survival of closing wedge HTO in a large series of patients up to 19 years after surgery.

Aims

Medial unicompartmental knee arthroplasty (UKA) is undertaken in patients with a passively correctable varus deformity. Our hypothesis was that restoration of natural soft tissue tension would result in a comparable lower limb alignment with the contralateral normal lower limb after mobile-bearing medial UKA.

Introduction. The pathogenesis of primary knee osteoarthritis is due to excess mechanical loading of the articular cartilage. Previous studies have assessed the impact of muscle forces on tibiofemoral kinematics and force distribution. A cadaveric study was performed to evaluate the effect of altering the moment arm of the iliotibial band (ITB) on knee biomechanics. Method. A robotic system consisting of a 6-DOF manipulator capable of measuring forces on the medial and lateral condyle of a cadaveric knee at various flexion angles and muscle forces was utilized [1]. The system measured the compartment forces at flexion angles between 0° and 30° under 3 simulated loading conditions (300N quadriceps, 100N hamstrings and: i. 0N ITB; ii. 50N ITB; iii. 100N ITB). Eight fresh frozen human cadaver knee specimens (4 males, 4 females); age range 36 – 50 years; weight range 49 – 90 kg; height range 154 – 190 cm were used in the study. The ITB and associated lateral soft tissue structures were laterally displaced from the lateral femoral condyle by fixing a metal implant (like in Figure 1) to the distal lateral femur. Mechanical loads on the medial and lateral compartments (with and without the implant) were measured using piezoelectric pressure sensors. Results. For each specimen, lateral displacement of the ITB due to the implant was measured (15 – 20 mm). The % average unloading of the medial compartment for all the specimens ranged from 34% – 65% (Figure 2). Also observed was a concomitant increase in lateral compartment load. Medial unloading was even observed with no ITB force (0N) which indicates a role for other lateral structures attached to the ITB in unloading the medial compartment [2]. In addition, under these non-weight bearing conditions, on average, there was an increase in valgus tibial angulation through the flexion range. Discussion. Increasing mechanical leverage of muscles across a joint is accomplished in nature through sesamoid bones (e.g., patella) which increase the muscle moment arm. By increasing the moment arm of the ITB and lateral soft tissue structures by lateralizing these structures, our model demonstrates a 34–65% unloading of the medial compartment. Studies of knee braces and weight loss have shown that reducing mechanical load on the medial condyle by even 10% provides clinical benefits in terms of reduced pain and improved function. Based on the results of this study, unloading the medial compartment by displacing the ITB laterally may be a means of treating medial osteoarthritis (Figure 3). A prospective, multi-center, non-randomized, open label, single-arm study is currently underway to establish the safety and efficacy of providing medial osteoarthritis pain relief by displacing the ITB using Cotera, Inc.'s Latella™ Knee Implant

Young, active patients with end-stage medial osteoarthritis (OA) secondary to anterior cruciate ligament (ACL) deficiency present a treatment challenge for surgeons. Current surgical treatment options include high tibial osteotomy (HTO) with or without ACL reconstruction, unicompartmental knee arthroplasty (UKA) with ACL reconstruction, and total knee arthroplasty (TKA). A recent systematic review reported a much higher rate of complications in HTO combined with ACL reconstruction than with UKA-ACL (21.1% vs 2.8%), while survivorship between the two procedures was similar. UKA offers several advantages over TKA, namely faster recovery, lower blood loss, lower rate of postoperative complications, better range of motion, and better knee kinematics. However, UKA has classically been contraindicated in the presence of ACL deficiency due to reported concerns over increased incidence aseptic loosening tibia. However, as a majority of patients presenting with this pathology are young and active, concerns about implant longevity with TKRA and loss of bone stock have arisen. As a result, several authors have described combining ACL reconstruction with medial UKA to decrease the tibiofemoral translation-related stress on the tibial component, thereby decreasing aseptic loosening-related failures. The purpose of this study was to compare the functional outcomes and survivorship of combined medial UKA and ACL reconstruction (UKA-ACL) with those of a matched TKA cohort. We hypothesized that UKA-ACL patients would have better functional outcomes than TKA patients while maintaining similar survivorship. Material and Methods. We conducted a case-control study establishing UKA-ACL as the study group and TKA as the control group by a single senior surgeon between October 2005 and January 2015. We excluded patients who were over the age of 55 at the time of surgery and those who had less than two-year follow-up. A total of 21 patients (23 knees) were ultimately included in each group. Propensity matching was for age-, sex-, and body mass index (BMI)-matched control group of TKA cases. Surgical technique. UKA-ACL. This patient's had an arthroscopy to allow for tunnel preparation in the standard fashion and then the graft was passed and fixed on the femoral side. An MIS medial incision was then made to allow for insertion of the Oxford mobile-bearing unicompartmental prosthesis (Zimmer Biomet, Warsaw, IN). Primary choice of ACL graft was autogenous ipsilateral semitendinosus and gracilis tendons, which was available I and 6 of the cases were revision from previous Gore-Tex synthetic ligament reconstruction. Results. Preoperatively, baseline questionnaires demonstrated that the TKA group had scored significantly lower on the symptom subscore of the KOOS. There was no difference between the groups in the rest of the KOOS subscores, (the UCLA, and the Tegner. All scores (UCLA, and Tegner – TBC post stats) improved significantly after surgery in both groups. Improvement in each subscore of the KOOS surpassed the minimal clinically important difference in both the UKA-ACL and TKA groups. At latest follow-up, there was no significant difference between the groups on the KOOS, UCLA or Tegner, showing that our UKA-ACL patients fared as our TKA patients. This confirms that UKA-ACL is an important tool in dealing with young patients with end-stage medial OA and ACL deficiency and offers an option that leads to less bone loss and potentially easier future revision. For any figures or tables, please contact authors directly

Objective. Open-wedge high tibial osteotomy (OWHTO) involves performing a corrective osteotomy of the proximal tibia and removing a wedge of bone to correct varus alignment. Although previous studies have investigated changes in leg length before and after OWHTO using X-rays, none has evaluated three-dimensional (3D) leg length changes after OWHTO. We therefore used 3D preoperative planning software to evaluate changes in leg length after OWHTO in three dimensions. Methods. The study subjects were 55 knees of 46 patients (10 men and 36 women of mean age 69.9 years) with medial osteoarthritis of the knee or osteonecrosis of the medial femoral condyle with a femorotibial angle of >185º and restricted range of motion (extension <–10º, flexion <130º), excluding those also suffering from patellofemoral arthritis or lateral osteoarthritis of the knee. OWHTO was simulated from computed tomography scans of the whole leg using ZedHTO 3D preoperative planning software. We analyzed the hip-knee-ankle angle (HKA), flexion contracture angle (FCA), mechanical medial proximal tibial angle (mMPTA), angle of correction, wedge length, 3D tibial length, 3D leg length, and 3D increase in leg length before and after OWHTO. We also performed univariate and multivariate analysis of factors affecting the change in leg length (preoperative and postoperative H-K-A angle, wedge length, and correction angle). Results. Mean HKA increased significantly from −4.7º ± 2.7º to 3.5º ± 1.3º, as did mean mMPTA from 83.7º ± 3.3º to 92.5º ± 3.0º (p <0.01). Mean FCA was 4.7º ± 3.6° preoperatively and 4.8º ± 3.3º postoperatively, a difference that was not significant (p = 0.725). The mean correction angle was 9.1º ± 2.8º and the mean wedge length was 9.4º ± 3.2º mm. Mean tibial length increased significantly by 4.7 ± 2.3 mm (p <0.01), and mean leg length by 5.6 ± 2.8 mm (p <0.01). The change in leg length was strongly correlated with wedge length (R = 0.846, adjusted R. 2. = 0.711, p <0.01). Discussion and Conclusion. Mean 3D leg length after OWHTO increased significantly by 5.4 ± 3.1 mm. A difference in leg length of >5 mm is believed to affect back pain and gait abnormalities, and changes in leg length must therefore be taken into consideration. The 3D dimensional change in leg length was strongly correlated with wedge length, and could be predicted by the formula (change in leg length in mm) = [(wedge length in mm) ×0.75) − 1.5]. For any figures or tables, please contact authors directly

The purpose of this study was to compare intra-operative, clinical, functional, and patient-reported outcomes following revision anterior cruciate ligament reconstruction (ACL-R) with a matched cohort of primary isolated ACL-R. A secondary purpose was to compare patient-reported outcomes within revision ACL-R based on intra-operative cartilage pathology. Between January 2010 and August 2017, 396 patients underwent revision ACL-R, and were matched to primary isolated ACL-R patients using sex, age, body mass index (BMI), and Beighton score. Intra-operative assessments including meniscal and chondral pathology, and graft diameter were recorded. Lachman and pivot shift tests were completed independently on each patient at two-years post-operative by a physiotherapist and orthopaedic surgeon. A battery of functional tests was assssed including single-leg Bosu balance, and four single-leg hop tests. The Anterior Cruciate Ligament-Quality of Life Questionnaire (ACL-QOL) was completed pre-operatively and two-years post-operatively. Descriptive statistics including means (M) and standard deviations (SD), and as appropriate paired t-tests were used to compare between-groups demographics, the degree and frequency of meniscal and chondral pathology, graft diameter, rate of post-operative ACL graft laxity, the surgical failure rate, and ACL-QOL scores. Comparative assessment of operative to non-operative limb performance on the functional tests was used to assess limb symmetry indices (LSI). Revision ACL-R patients were 52.3% male, mean age 30.7 years (SD=10.2), mean BMI 25.3 kg/m2 (SD=3.79), and mean Beighton score 3.52 (SD=2.51). In the revision group, meniscal (83%) and chondral pathology (57.5%) was significantly more frequent than in the primary group (68.2% and 32.1%) respectively, (p < 0 .05). Mean graft diameter (mm) in the revision ACL-R group for hamstring (M=7.89, SD=0.99), allograft (M=8.42, SD=0.82), and patellar or quadriceps tendon (M=9.56, SD=0.69) was larger than in the primary ACL-R group (M=7.54, SD=0.76, M=8.06, SD=0.55, M=9, SD=1) respectively. The presence of combined positive Lachman and pivot shift tests was significantly more frequent in the revision (21.5%) than primary group (4.89%), (p < 0 .05). Surgical failure rate was higher in the revision (10.3%) than primary group (5.9%). Seventy-three percent of revision patients completed functional testing. No significant LSI differences were demonstrated between the revision and primary ACL-R groups on any of the functional tests. No statistically significant differences were demonstrated in mean preoperative ACL-QOL scores between the revision (M=28.5/100, SD=13.5) and primary groups (M=28.5/100, SD=14.4). Mean two-year scores demonstrated statistically significant and minimally clinically important differences between the revision (M=61.1/100, SD=20.4) and primary groups (M=76.0/100, SD=18.9), (p < 0 .05). Mean two-year scores for revision patients with repair of the medial (M=59.4/100, SD=21.7) or lateral meniscus (M=59.4/100, SD=23.6), partial medial meniscectomy (M=59.7/100, SD=20), grade three or four osteoarthritis (M=55.9/100, SD=19.5), and medial femoral condyle osteoarthritis (M=59.1/100, SD=18) were lower compared with partial lateral meniscectomy (M=67.1/100, SD=19.1), grade one or two osteoarthritis (M=63.8/100, SD=18.9), and lateral femoral condyle osteoarthritis (M=62, SD=21). Revision ACL-R patients demonstrated a greater amount of meniscal and chondral pathology at the time of surgery. Two-years post-operative these patients demonstrated higher rates of graft laxity and lower ACL-QOL scores compared with the primary ACL-R group. Higher grade and medial sided osteoarthritis was associated with inferior ACL-QOL scores in revision ACL-R

Purpose. The purpose was to compare the accuracy of the method using 3D printing model with the method using picture archiving and communication system (PACS) images in high tibial osteotomy (HTO). Materials and methods. This study analyzed 40 patients with varus deformity and medial osteoarthritis. From 2012 to 2016, patients underwent HTO using either 3D printing model (20 knees) or method based on a PACS image (20 knees). After obtaining the correction angle for the target point (62.5% point of the mediolateral tibial plateau width), in the 3D printing method, the wedge-shaped 3D-printed model was designed with the measured angle and osteotomy section and was produced by the 3D printer. The PACS method used preoperative radiographs to shift the weight bearing axis. The accuracy of the HTO and the proportion of acceptable range (62.5 ± 5%) at each method was compared using the full-length lower limb radiographs at the sixth postoperative week. The pre and postoperative posterior tibial slope angle was also compared at each method. Results. The weight bearing line on the tibial plateau was corrected from a preoperative 21.1 ± 11.8% to a postoperative 61.6 ± 3.4% in the 3D group and from 19.5 ± 12.3% to 61.4 ± 8.0% in the PACS group. The patients in an acceptable range were more in 3D printing group (80%) than in PACS group (60%) (p=0.028). The mean of absolute difference with the target point was less in 3D printing groups (2.4 ± 2.5) than PACS group (6.2 ± 5.1) (p=0.006). The posterior tibial slope was not significantly different in 3D printing group (8.6° to 8.9°, p=0.073), whereas different in PACS group (9.9° to 10.5°, p=0.042). Conclusions. In HTO, correction based on the 3D printing method was more accurate than correction using the PACS method

Soft tissue balance is important for good clinical outcome and good stability after TKA. Ligament balancer is one of the devices to measure the soft tissue balance. The objective of this study is to clarify the effect of the difference in the rotational position of the TKA balancer on medial and lateral soft tissue balance. Materials and Methods. This study included with 50 knees of the 43 patients (6 males, 37 females) who had undergone TKA with ADLER GENUS system from March 2015 to January 2017. The mean age was 71.1±8.1 years. All patients were diagnosed with medial osteoarthritis of the knee. All implants was cruciate substituted type (CS type) and mobile bearing insert. We developed a new ligament balancer that could be fixed to the tibia with keel and insert trial could be rotated on the paddle. We measured the medial and lateral soft tissue balance during TKA with the new balancer. The A-P position of the balancer was fixed on tibia in parallel with the Akagi line (A-P axis 0 group) and 20 degrees internal rotation (IR group) and 20 degrees external rotation (ER group). Soft tissue balance was measured in extension and 90 degrees of knee flexion on each rotational position. Results. The mean angle of valgus and varus in IR group, 0 group and ER group were 4.6±2.2 degrees varus, 1.9±1.6 degrees varus and 0.4±2.4 degrees varus respectively in extension, and 5.5±3.0 degrees varus, 2.1±2.2 degrees varus and 0.7±3.2 degrees varus respectively in 90 degrees of knee flexion. There were significant differences between three groups in extension (p<0.0001) and flexion (p<0.0001). In other words, when the balancer was fixed on tibia with internal rotation against the Akagi line, the soft tissue balance indicated medial tightness. Conversely, when the balancer was fixed on tibia with external rotation against the Akagi line, the soft tissue balance showed lateral tightness. The insert trial significantly rotated to opposite side against the position of balancer fixed. Discussion. Ligament balancer is used to be inserted between femur and tibia. If balancer is not fixed on tibia, it may rotated and translated during measurement. That movement made impossible to measure the correct soft tissue balance. We created a new balancer that could be fixed to the tibia with keel and the insert trial could be rotated on the paddle. Furthermore, it is possible to measure the soft tissue balance after installation of the femoral trial. As a result, it is possible to check the real soft tissue balance after implantation. In conclusion, direction of A-P axis of the ligament balancer is important to measure the correct soft tissue balance in TKA. This result means that the implantation on excessive rotation of the tibial component affects on the medial and lateral soft tissue balance in fixed type TKA. In mobile type TKA, it is possible to substitute if it is within the possible range of rotation by rotational mobile insert

Introduction. We report a case which total knee arthroplasty (TKA) was able to be performed on schedule for the patient with occult fracture of proximal tibia which seemed to have occurred three months prior to the surgery, and has healed in short period of time by the use of Teriparatide. Case report. The patient is 84-year-old female, having right knee pain for past 7 years. Her knee pain increased by passive extension maneuver that was done by a bonesetter 3 months prior to the surgery. On her initial visit, the X-ray finding was severe medial osteoarthritis, and femorotibial angle (FTA) in the upright film was 197°, but there was no other disorder including fracture. Since the bone mineral density (BMD) of affected femoral neck was 62%YAM, and affected lateral femoral condyle as well as lateral tibial condyle seemed very porotic, we started using daily 20μg Teriparatide injection from 3 months prior to the surgery. Proximal tibial fracture was presented in the X-ray taken on the day before surgery, but since adequate bone union has already been formed, surgery was performed on schedule. Tibial implant with long stem was used for just to be certain. Thanks to the Teriparatide, the condition of cancellous bone in cut surface was excellent, and reaming of the tibia through fracture area felt very solid. Discussion. Proximal tibial fracture that occurred just before TKA is very rare. The fracture in this case was probably due to the maneuver done by the bonesetter. Teriparatide is indicated when osteoporosis is severe and the patient is at risk for fracture. We also indicate Teriparatide for the patients whose femoral neck BMD is very low and severe valgus knee or varus knee is present. Unloaded side of femoral or tibial condyle is usually very porotic in such a case. In our case, the fracture was so called fragility fracture which was found incidentally the day before surgery, but TKA could be done on schedule since adequate callus has been formed by the use of Teriparatide which started 3 months prior to the surgery

Introduction. In prosthetic knee surgery, the axis of the lower limb is often determined only by static radiographic analysis. However, it is relevant to determine if this axis varies during walking, as this may alter the stresses on the implants. The aim of this study was to determine whether pre-operative measurement of the mechanical femorotibial axis (mFTA) varies between static and dynamic analysis in isolated medial femorotibial osteoarthritis. Methods. Twenty patients scheduled for robotic-assisted medial unicompartmental knee arthroplasty (UKA) were included in this prospective study. We compared three measurements of the coronal femorotibial axis: in a static and weightbearing position (on long leg radiographs), in a dynamic but non-weightbearing position (intra-operative acquisition during robotic-assisted UKA), and in a dynamic and weightbearing position (during walking by a gait analysis). Results. There was no significant difference in the mFTA between radiological (173.9 ± 3.3°), robotic (174.4 ± 3.4°), and gait analysis (172.9 ± 5.1°) measurements (p < 0.05). Conclusion. There is no significant variation in varus between lying, standing, and while walking in patients who are candidates for medial UKA. This study also allows us to validate the accuracy of the robotic system in varus estimation, and to rely on intra-operative planning as it also reflects the dynamic knee under load

Background. In measured resection (MR) technique it is sometimes not easy to equalize extension gap (EG) and flexion gap (FG) because the size of femoral component is generally determined only depending on the anteroposterior and mediolateral size of femoral condyle in MR technique. In order to equalize the EG and FG, femoral implant size should be determined so that the FG is similar to the EG. We developed the novel sizing technique of femoral component to equalize the EG and FG in MR technique. The purpose of this study was to examine the usefulness of this technique. Methods. Before surgery, the condylar twist angle: CTA (angle between the transepicondylar axis and the posterior condylar axis) was determined for individual knees by transepicondylar view (X ray) or CT. During surgery, after osteophyte was removed EG was made and measured. Knee was flexed in 90° and the specially made tensor which upper paddle has the medial inclination angle (same as the CTA) was inserted to FG before posterior femoral osteotomy. Then, the appropriate traction force was applied to FG. Under this condition, the correct rotational alignment of femur relative to tibia was obtained, and then, the size of femoral component could be determined so that the FG was similar to the EG by measuring the distance between tibial cut surface and posterior cut level of the respective size of femoral conponent. 23 knees that undergone TKA for end stage medial osteoarthritis were examined and the final EG and FG were measured. EG and FG were measured at the mediolateral center of the gap without any trial component. Results. The mean (± SD) and maximum difference between EG and FG was 2.2±0.9 mm (EG>FG) and 3.5 mm, respectively. The mean (± SD) varus-valgus alignment of gap was 2.1 ± 0.8° varus in extension and 0.9 ± 1.2° varus in flexion. Discussion. As the EG was reduced by about 2mm after implantation of femoral components, the difference between DG and FG in this series was thought to be very small after implantation. Although it was reported that gap balancing technique has superior ability to control EG and FG compared to MR technique, it was indicated that EG and FG were well controlled also in MR technique by this novel sizing method. Further study to examine the relationship between the clinical results and this method was definitely required

«Purpose». High tibial osteotomy (HTO) is a useful treatment option for osteoarthritis of the knee. Closing-wedge HTO (CW-HTO) had been mostly performed previously, but the difficulties of surgical procedure when total knee arthroplasty (TKA) conversion is needed are sometimes pointed out because of the severe deformity in proximal tibia. Recently, opening-wedge HTO (OW-HTO) is becoming more popular, but the difference of the two surgical techniques about the influence on proximal tibia deformity and difficulties in TKA conversion are not fully understood. The purpose of this study was to compare the influence of two surgical techniques with CW-HTO and OW-HTO on the tibial bone deformity using computer simulation and to assess the difficulties when TKA conversion should be required in the future. «Methods». In forty knees with medial osteoarthritis, the 3D bone models were created from the series of 1 mm slices two-dimensional contours using the 3D reconstruction algorithm. The 3-D imaging software (Mimics, materialize NV, Leuven, Belgium) was applied and simulated surgical procedure of each CW-HTO and OW-HTO were performed on the same knee models. In CWHTO, insertion level was set 2cm below the medial joint line [Fig.1]. While in OW-HTO, that was set 3.5cm below the medial joint line and passed obliquely towards the tip of the fibular head [Fig.2]. The correction angle was determined so that the postoperative tibiofemoral angle would be 170 degrees. The distance between the center of resection surface and anatomical axis, and the angle of anatomical axis and mechanical axis were measured in each procedure. Secondly, a simulated TKA conversion was operated on the each tibial bone models after HTO [Fig.3]. The distance between the nearest points of tibial implant and lateral cortical bone was assessed as the index of the bone-implant interference. «Results». The distance between the center of resection surface and anatomical axis was significantly shifted to the lateral side in CW group (0.62 ±2.95 mm lateral shift) than in OW group (0.93 ± 3.68 mm medial shift) (P<0.01). The angle of anatomical axis and mechanical axis was significantly increased in the CW group (CW: 0.77 ± 0.79 degree, OW: 0.49 ± 0.83 degree, P<0.01). In the simulation of TKA conversion, if thickness of the lateral cortical bone was 3mm, it was showed that the tibial implant was more interfered with the lateral cortical bone in CW group (2.77 ± 1.38 mm) than in OW group (4.32 ± 1.61 mm) (P<0.01). «Conclusions». The results suggested that bone deformity in proximal tibia after HTO might affect the difficulty of TKA conversion, particularly in the case of CWHTO

Introduction. We have previously reported that patients who demonstrated medial pivot kinematics pattern after total knee arthroplasty (TKA) had better clinical results than that of non-medial pivot pattern. However, it is unclear how preoperative kinematics pattern affects postoperative knee kinematics. The aim of this study was to evaluate the relationship between preoperative and postoperative knee kinematics pattern in TKA. Materials and Methods. The present study consists of 38 patients with medial osteoarthritis who underwent a primary TKA using a CT-based navigation system from July 2010 to September 2012. All the operations were performed by a single surgeon using a subvastus approach and the same posterior cruciate ligament substituting type (PS type) of prosthesis (Genesis II™ total knee system, Smith & Nephew, Memphis, TN). The proximal tibia osteotomy and the distal femur osteotomy were set on the navigation system perpendicular to the mechanical axis in the coronal plane with 3° tibial posterior inclination in the sagittal plane. The coronal plane ligament imbalance was corrected until the gap imbalance was fewer than 2 mm. This gap balance was checked using a ligament balancer (Smith & Nephew) at 80 N in medial and lateral compartment of the knee. The navigation system was used to measure the flexion gap with the CAS ligament balancer (Depuy, Warsaw, IN, USA) at 90° knee flexion. The amount of external rotation on femoral osteotomy was adjusted by the navigation system with a balanced gap technique. The patella was resurfaced and a lateral release was not performed. Tibial A-P axis of the tibial tray was placed parallel to Akagi's line. We measured each kinematics pattern immediately after capsule incision (preoperative knee kinematics) and after implantation (postoperative knee kinematics) in TKA. Subjects were divided into two groups based on kinematics patterns: a medial pivot group (group M) and a non-medial pivot group (group N). A chi-square test was used for statistical analysis. P values less than 0.05 were considered significant. Results. There were 19 knees in group M and 19 knees in group N at preoperative knee kinematics measurement. Nineteen knees in group M at preoperation resulted in 14 knees in group M and five knees in group N at postoperative knee kinematics measurement. On the other hand in group N at preoperation resulted in 2 knees in group M and 17 knees in group N at postoperative kinematics. Preoperative knee kinematics significantly correlated with postoperative knee kinematics (P < 0.01). Our results suggest that preoperative knee kinematics robustly impacted upon postoperative knee kinematics in most cases. Discussion and Conclusion. In conclusion, this study revealed that a precise bone cut assisted by a navigation system and a modified gap technique could not improve the knee kinematics pattern in most cases. Further technical improvement or a new implant design is required to correct preoperative abnormal knee kinematics in TKA

INTRODUCTION. The major loss of articular cartilage in medial osteoarthritis occurs in a central band on the distal femur, and in the center of the tibial plateau (Figure). This is consistent with varus deformity due to cartilage loss and meniscal degeneration, together with the sliding regions in walking. Treatment at an early stage such as KL grade 2 or 3, has the advantages of little bone deformity and cruciate preservation, and could be accomplished by resurfacing only the arthritic areas with Early Intervention (EI) components. Such components would need to be geometrically compatible with the surrounding bearing surfaces, to preserve continuity and stability. However because of the relatively small surface area covered, compared with total knees and even unicompartmentals, it is hypothesized that EI components will be an accurate fit on a population of knees with only a small number of sizes, and that accuracy can be maintained without requiring right-left components. We examined this hypothesis using unique design and methodology. METHODS. Average femur and tibia models, including cartilage, were generated from MRI scans of 20 normal males. The images were imported into Geomagic software. Surface point clouds based on least squares algorithms produced the average models. Averages were also produced from different numbers to determine method validity. Average arthritic models were also generated from 12 KL 1–2 cases, and 13 KL 2–3 cases. The 3 averages were compared by deviation mapping. Using the average from the 20 knees, femoral and tibial implant surfaces were designed using contour matching to fit the arthritic regions, maintaining right-left symmetry. A 5 size system was designed corresponding to large male, average male, small male/large female, average female, small female. For the 20 knees, the components were fitted based on the best possible matching of the contours to the surrounding bearing surfaces. For the femoral component the target was 1 mm projection at the center, matching at the ends. The accuracy of reproducing the cartilage surfaces was then determined by mapping the deviations between the implant surfaces and the cartilage surfaces. RESULTS & DISCUSSION. The average femur and tibia from the 20 knees (Figure) was almost identical no matter what groupings were used to produce the average. Likewise the 2 arthritic and the normal averages were almost identical. The accuracy of fit (Figure) averaged for the 20 normal knees was well below 1mm either above or below the original cartilage surfaces (see table below). This study indicates that such Early Intervention components are a viable method for resurfacing cases with early arthritis, and are likely to show almost normal mechanics due to preserving the original normal geometry. Deviations between tibial cartilage and implant (mm). Above implant mean 0.5 SD 0.2. Max deviation 1.5 SD 0.7. Below implant mean 0.7 SD 0.2. Max deviation 2.0 SD 0.1. Deviations between femoral cartilage and implant (mm). Above implant mean 0.3 SD 0.1. Max deviation 0.8 SD 0.1. Below implant mean 0.3 SD 0.1. Max deviation 0.8 SD 0.3

Introduction. Total knee arthroplasty (TKA) is a well-established procedure associated with excellent clinical results. We have previously reported that intraoperative knee kinematics correlate with the clinical outcome in mobile bearing TKA. In addition, the intraoperative knee kinematics pattern does not correlate with the degree of preoperative knee deformity in mobile bearing TKA. However, the relationship among preoperative knee deformity, intraoperative kinematics and clinical outcome in fixed bearing TKA has been unknown. The purpose of this study is to compare the relationship among preoperative knee deformity, knee kinematics after fixed bearing TKA and the clinical outcome including the subjective outcomes evaluated by the new knee society score (KSS). Materials and Methods. A cross-sectional survey of thirty-five consecutive medial osteoarthritis patients who had a primary TKA using a CT-based navigation system was conducted. All knees had a Kellgren-Lawrence grade of 4 in the medial compartment and underwent a primary posterior stabilized TKA (Genesis II, Smith&Nephew) between May 2010 and October 2012. In all cases, a computed tomography-guided navigation system (Brain LAB, Heimstetten, Germany) was used. All surgery was performed by the subvastus approach and modified gap technique. Intraoperative knee kinematics was measured using the navigation system after implantation and closure of the retinaculum and soft tissue except for the skin. Subjects were divided into two groups based on intraoperative kinematic patterns: a medial pivot group (M group, n=19)(Figure 1) and a non-medial pivot group (N group, n=16)(Figure 2). Subjective outcomes with the new KSS and clinical outcomes were evaluated. Statistical analysis to compare the two groups was made using unpaired a Student t test. Result. Regarding the postoperative clinical result (knee flexion angle, knee extension angle, mechanical FTA,% mechanical axis), there were no significant differences between the two groups. Although there were also no significant differences in KSS evaluation between the two groups, there was a tendency for M group to be superior to N group in current knee symptom (M group: 17.3±5.6, N group: 12.9±8.2, p = 0.07) and functional activities (M group: 55.1±21.5, N group: 42.7±22.6, p = 0.10). Regarding preoperative examination, varus knee deformity (mechanical FTA and% mechanical axis) in N group was significantly more severe than that of M group (p=0.04, p=0.04, respectively). Discussion. Over half of patients (54%) could achieve medial pivot kinematics in fixed bearing TKA with the possibility to improve a subjective clinical result. Although we previously could not detect any relationship between preoperative varus knee deformity and intraoperative kinematics in mobile bearing TKA, the preoperative varus knee deformity in the non-medial pivot group was significantly severer than that of the medial pivot group in fixed type TKA. Our results indicate that if a TKA is done to a severe varus knee deformity the postoperative knee kinematics tend to result in a non-medial pivot pattern. In conclusion, because it tends to result in a non-medial pivot pattern, extra care needs to be taken to avoid postoperative abnormal knee kinematics in the performance of a fixed type TKA to a severe varus knee deformity

Total Knee Replacement (TKR) has been proven to be an effective procedure not only to eliminate pain but also to achieve better knee function. Recent rehabilitation is basically focused on achieving better ROM and muscle strength. However, improvements of balancing or walking ability in detail have not been sufficiently elucidated yet. Methods. 91 consecutive knees of 70 patients, with medial osteoarthritis undergone TKR have been nominated in this study. All were done by a single surgeon, via mid vastus approach, using cemented PS implant with patellar resurfacing. Patients were arrowed to start full weight bearing from the next day. Assessing walking ability, gait speed and width of a step were measured. As for balancing, “Functional Reach (FR)” which was the difference between arm's length and maximal forward reach (Duncan PW et al), “Timed Up and Go Test (TUG)” which was time while a patient rose from an arm chair, walked 3 meters, turned, walked back, and sat down again (Podsiadlo D et al), and possible period standing on one leg (one leg standing) were used. Every measurement was performed prior to the operation, 1,2,3,4 weeks, 2 months and 6 months after operation. Data of prior to the operation, 2, and 6 monts after the operation were analyzed by one-way repeated ANOVA, and then differences among means were analyzed using Bonferroni procedures. P-value lower than 5% is regarded as significant. Result. Every result except for one-leg standing time on contralateral leg (non-operative side) showed the worst during the first week, followed by better results over time (Fig. 1,2,3). One leg standing time of operative leg reached maximum at 2 months of time, while the others revealed improvement even at 6 months of time. Interestingly, postoperative one leg standing period of contra-lateral leg showed improvement with similar tendency until 4 weeks, followed by reaching plateau over time. Discussion. In 6 months after operation, every result showed better function than that of prior to operation. Generally, the factors other than ROM and muscle strength are hard to be measured for both clinician and patients. However, this study showed total function including dynamic and static balancing ability certainly improved correlatively after TKR until at least 6 months

Patients who have undergone Total Knee Replacement (TKR) improve their knee functions with time dependent recovery. However, the speed and degree of recovery widely varies from person to person. Practitioners generally find that postoperative satisfaction after TKR is closely related to the degree of preoperative severity in deformity. We focused on preoperative FTA to determine how the degree of deformity affects postoperative improvements after TKR. Methods:. 44 consecutive knees of 44 patients with medial osteoarthritis underwent TKR for nomination in this study. All operations were conducted by a single surgeon using a mid vastus approach with cemented posterior stabilized (PS) implant and patellar resurfacing. Patients were targeted for full weight bearing the next day. Patients were divided into 3 groups of preoperative FTA: 174–180 degrees (11 knees), 181–189 degrees (17 knees), and more than 190 degrees (16 knees). Walking ability was assessed by gait speed and width of step. Balance was measured by a “Functional Reach Test (FR),” which is the difference between arm's length and maximal forward reach (Duncan PW et al. 1990), a “Timed Up and Go Test (TUG),” the time interval for a patient rise from an arm chair, walk 3 meters, and return (Podsiadlo and Richardson 1991), and the capacity to stand on one leg (one leg standing time trial). Every measurement was performed prior to the operation (pre-op), and 4 weeks after operation (post-op 4w). The recovery rate (%) was defined as post-op 4w/pre-op ×100. Data were analyzed by one-way ANOVA, and then differences among means were analyzed using Bonferroni procedures. P-values lower than 5% are regarded as significant. Result:. The recovery rate of walking speed and TUG showed significant improvement in the FTA more than >190 degree group than that of 174–180 degree group. Every other result showed a higher recovery rate for the >190 degree group, although results were not statistically significant. Discussion:. Both walking speed and TUG represent the patients' ability for walking and dynamic balancing, while FR and one leg standing depend more on the ability for static balancing. This study demonstrates that patients with severely deformed knees could show better postoperative recovery in walking and dynamic balancing than those with less severely deformed knees. Moreover, this study could suggest it is always not too late for patients with severely deformed knees to undergo TKR

Introduction. Total knee arthroplasty (TKA) designs evolve as evidence accumulates on natural and prosthetic knee function. TKA designs based upon a medially conforming tibiofemoral articulation seek to reproduce essential aspects of normal knee stability and have enjoyed good clinical success and high patient satisfaction for over two decades. Fluoroscopic kinematic studies on several medially conforming knee designs show extremely stable knee function, but very small ranges of tibial axial rotation compared to healthy knees. The GMK Sphere TKA is a recent evolution in medially-conforming TKA designs that adopts a sagittally unconstrained lateral tibiofemoral articulation to allow more natural tibial rotation. This study was conducted to quantify motions in knees with this prosthesis to address two questions:. Does the medially conforming GMK Sphere design provide an AP-stable articulation that provides for tibiofemoral translations that are comparable to, but not larger than, translations measured in natural knees?. Does the medially conforming GMK Sphere design provide sufficient rotatory laxity to allow tibiofemoral rotations comparable to, but not larger than, rotations measured in natural knees?. Materials and Methods. Fifteen patients (9 females), mean age 65 years and mean BMI of 30 ±3, consented to participate. Sixteen knees received the GMK Sphere TKA. Mean Oxford Knee Score (OKS) improved significantly from 19±7 to 40±3 six months post surgery (P< 0.0001). On the day of the study, the mean OKS, Knee Society Score, EQ5D and Heath status scores were 40, 87, 0.83 and 85 respectively. Mean ROM from active maximum extension till maximum supine flexion was 108°±8°. Motions in 16 knees were observed using pulsed-fluoroscopy during a range of activities. Subjects were observed in maximum flexion kneeling and lunging positions, and in stepping up/down on a 22cm step. Model-image registration methods were used to quantify three-dimensional knee motions from digitized fluoroscopic images. Results. Tibial internal rotation averaged 8° during lunge and kneeling activities. During lunging, the medial and lateral condyles were an average of 2mm and 8mm posterior to the tibial sulcus, respectively, and 2mm and 9mm posterior to the tibial sulcus during kneeling. During the stair-stepping activity, the medial condyle did not translate significantly, while the lateral condyle moved 5mm posteriorly with flexion, accompanying 5° tibial internal rotation. Discussion. The GMK Sphere TKA was designed to provide intrinsic stability through a medially conforming articulation, and provide for more natural tibial rotation with an unconstrained lateral articulation. Fluoroscopic observation of these knees during lunge, kneel and stair-stepping activities showed a stable medial articulation with little translation, and a lateral articulation translating in direct relation to tibial rotation. Tibial rotation during kneeling (8° average) was approximately twice that observed in knees with an earlier medially conforming TKA design (Moonot et al., Knee Surg Sports Traumatol Arthrosc, 2009) and similar to that observed in natural knees with medial osteoarthritis (Hamai et al., J Orthop Res, 2009). At only six months follow-up, knees with the GMK Sphere arthroplasty show functional kinematics that are AP stable and have more natural tibial rotation, consistent with the implant design intent