The purpose of this study is to investigate the three-dimensional (3D) kinematics of normal knees in deep knee-bending motions like squatting and kneeling. Material & Methods: We investigated the in vivo kinematics of 4 Japanese healthy male volunteers (8 normal knees in squatting, 7 normal knees in kneeling). Each sequential motion was performed under fluoroscopic surveillance in the sagittal plane. Femorotibial motion was analyzed using 2D/3D registration technique, which uses computer-assisted design (CAD) models to reproduce the spatial position of the femur and tibia from single-view fluoroscopic images. We evaluated the femoral rotation relative to the tibia and anteroposterior (AP) translation of the femoral sulcus and lateral epicondyle on the plane perpendicular to the tibial mechanical axis. Student's t test was used to analyze differences in the absolute value of axial rotation and AP translation of the femoral sulcus and lateral epicondyle during squatting and kneeling. Values of P < 0.05 were considered statistically significant. During squatting, knees were gradually flexed from −2.8 ± 1.3° to 145.5 ± 5.1° on average. Knees were gradually flexed from 100.8 ± 3.9° to 155.6 ± 3.2° on average during kneeling. Femurs during squatting displayed sharp external rotation relative to the tibia from 0° to 30° of flexion and it reached 12.5 ± 3.3° on average. From 30° to 130° of flexion, the femoral external rotation showed gradually, and it reached 19.1 ± 7.3° on average. From 130° to 140° of flexion, it was observed additionally, and reached 22.4 ± 6.1° on average. All kneeling knees displayed femoral external rotation relative to the tibia sharply from 100° to 150° of flexion, and it reached 20.7 ± 7.5° on average. From 100° to 120° of flexion, the femoral external rotation during squatting was larger than that during kneeling significantly. From 120° to 140° of flexion, there was no significant difference between squatting and kneeling. The sulcus during squatting moved 4.1 ± 4.8 mm anterior from 0° to 60° of flexion. From 60° of flexion it moved 13.6 ± 13.4 mm posterior. The sulcus during kneeling was not indicated significant movement with the knee flexion. The lateral epicondyle during squatting moved 39.4 ± 7.7 mm posterior from 0° to 140° of flexion. The lateral epicondyle during kneeling moved 22.0 ± 5.4 mm posterior movement from 100° to 150° of flexion. In AP translation of the sulcus from 100° to 140° of flexion, there was no significant difference between squatting and kneeling. However in that of the lateral epicondyle, squatting groups moved posterior significantly. Even if they were same deep knee-bending, the kinematics were different because of the differences of daily motions. The results in this study demonstrated that in vivo kinematics of deep knee-bending were different between squatting and kneeling

Objective

To evaluate the clinical and functional outcomes obtained by combination of high-flexion Freedom® Total Knee System (TKS) and mini-subvastus approach in total knee replacement patients.

Introduction & Aim

During TKR it is mandatory to achieve perfect soft tissue balance and component alignment. It is necessary to access all tight structures for proper releases. We aim to analyze the results of Trivector arthrotomy approach for TKRs.

Aims

The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes.

Aims

Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised.

Aims

As has been shown in larger animal models, knee immobilization can lead to arthrofibrotic phenotypes. Our study included 168 C57BL/6J female mice, with 24 serving as controls, and 144 undergoing a knee procedure to induce a contracture without osteoarthritis (OA).

Background: Total knee replacement remains one of the most common knee surgery practices worldwide. The operative procedure universally requires the use of cutting jigs to resect predetermined amounts of bone irrespective of the preoperative anatomy and morphology of the femur and tibia.

Aims: The aims of this study were to elucidate anatomical morphological differences between ethnicities pre-operatively and to assess whether any change elucidated was preserved post-operatively.

Method: This was a retrospective study comparing the pre and postoperative lateral view X-Rays of TKRs performed. Distances measured from most prominent anterior point to midline and the most prominent posterior point to midline and their ratio was compared between two ethnic groups. Each x-ray measurement was triple checked.

Results: The study groups comprised of 60 Caucasian knees and 40 Asian knees. Preoperatively the mean ratio was 0.55 in Caucasians and 0.44 in Asians, with this difference being statistically significant (p value < 0.005). Post operatively the mean ratio was 0.59 in Caucasians and 0.55 in Asians and this difference was not statistically significant (p value =0.166). These findings were also cross-checked with range of movement measurements post-operatively in the same group of patients. There was no comparable improvement in range of movements (ROM) post-operatively in the Asian group.

Conclusion: We infer that the present TKR cutting jigs are not taking into account the anatomical differences within the knee of Asians individuals. This is converting the post operative distal femurs of this group to become morphologically comparable to the Caucasian knee and this is possibly affecting the kinematics of those knees leading to no significant improvement in the post operative ROM and affecting satisfaction with surgery.

Knees of patients with chronic anterior cruciate ligament instability and who were awaiting surgery were examined with respect to increasing co-morbidity following diagnosis and subsequently during surgical reconstruction. 141 patients were included in this study. All had undergone initial arthroscopic evaluation of their unstable knees following diagnosis and subsequently a further arthroscopy was performed at a later stage during hamstring anterior cruciate ligament reconstruction. All injuries to the menisci and articular cartilage were recorded using a standardised evaluation form. The Lysholm and Tegner scores were obtained as well as knee stability using the KT-2000 arthrometer. Successive deterioration in the Lysholm and Tegner scores and the arthrometric side to side difference was noted with time since injury. Initial arthroscopic examination of the knee revealed that 66 patients (46%) had at least one meniscal injury necessitating treatment whilst 67 (47.5%) had at least one chondral lesion on the femoral condyles. 22 patients (15.6%) presented with chondral lesions of the articular surface of the patella. During definitive ACL reconstruction when a second arthroscopy was performed, it was noted that 111 patients (78.7%) had meniscal pathology, 102 patients (72.34%) had intraarticular chondral lesions and the patella was affected in 41 cases (29%). The delay between initial arthroscopy and stabilization was 16 +/− 5.2 months (range 7–19 months). The difference in the arthroscopic findings between the first and second arthroscopic inspections in terms of meniscal and chondral lesions was statistically significant. Knee instability due to chronic ACL deficiency poses a serious threat to the menisci and the articular cartilage of the affected knee. The severity of these lesions increases with time since injury. ACL reconstruction should be undertaken as soon as possible in those individuals with uncompensated anterior cruciate ligament instability

Aims

The mid-term results of kinematic alignment (KA) for total knee arthroplasty (TKA) using image derived instrumentation (IDI) have not been reported in detail, and questions remain regarding ligamentous stability and revisions. This paper aims to address the following: 1) what is the distribution of alignment of KA TKAs using IDI; 2) is a TKA alignment category associated with increased risk of failure or poor patient outcomes; 3) does extending limb alignment lead to changes in soft-tissue laxity; and 4) what is the five-year survivorship and outcomes of KA TKA using IDI?

Meniscus repair is now an accepted procedure, but many questions remain, regarding the results, indications versus meniscal resection. How to assess the results of meniscal repair?. Clinical results doesn’t allow to assess the healing rate. Some failure of healing can be asymptomatic. There is thus a need for an objective assessment of the healing process: by arthroscopy (but it is invasive); by MRI but the hypersignal in the meniscus area is difficult to interpret. The best way seems to be arthro CT, even if it is a quite invasive technique. Indications: Indications mainly depend on two factors: location of the lesion stability of the knee. 1. Location of the lesion. In case of lesions in the red-red zone or red-white zone: the healing potential is good ameniscectomy would be total and would lead to secondary degenerative changes. it is thus the best indications for meniscal repair. In case of lesions in the white-white zone: the healing potential is poor the meniscectomy would be partial with usual good long term results. Indications for meniscal repair should be very selective in this occurrence. 2. Etiology. 2.1. ACL Tears Meniscectomy is the key of degenerative process after ACL rupture. ACL reconstruction is able to preserve meniscal status. We must thus preserve the menisci as much as possible: by doing a meniscal repair in case of unstable extended lesions by abstention if he meniscal is table. In all the cases, ACL should be reconstructed. Results of meniscal repair in this context are good both in terms of clinical results and healing rate. Isolated meniscal repair should be only considered in presence of 4 criteria: symptomatic meniscal lesion, no functional instability, non repairable meniscal lesion, low demanding patient. 2.2. Stable Knees. Meniscectomy remains the most frequent procedute in this condition with good functional results. But, according to the long term FU results (> 10year) (multi-centre study of the SFA 1996), the rate of asymptomatic knees is only 60% on the medial side, and 50% on the lateral side. The rate of joint line narrowing is 28% on the MM and 40% on the lateral side. The recovery after lateral meniscectomy is often long with a high rate of rearthroscopy (14%). There is a specific complication on the lateral side: rapid chondrolysis by young patients. Meniscal repair should be thus proposed as often as possible. The best indcation is a peripheral vertical lesion by a young patient. The rate of secondary meniscectomy is about 10% but the rate of complete healing is only 50 to 60% according to the literature. Prognostic factors are: time to surgery: recent lesions have a better prognosis (12 weeks ?) extension of the lesion side of the lesion: lateral lesion is better than medial one. Intrameniscal horizontal cleavage grade 2 lesion by young patients is a specific indication which gives good results and avoids a total meniscectomy. Conclusion: Meniscectomy and meniscal repair are not opposite techniques but complementaries technique. Meniscal repair should be recommended for red-red or red-white zone to preserve the meniscus and thus the cartilage, specially on ACL unstable knees, lateral side, young patients (children+++). But many questions remain: which strength do we need ? what about shear forces is there any secondary degenerative changes of the meniscal tissue with an increasing risk of iterative tear which long term results with the new devices ?

Summary Statement. Increased Dkk-1 signaling is associated with OA occurrence and joint microenvironment damage. Interruption of Dkk1 action is beneficial to improve OA knees. Introduction. Osteoarthritis (OA) is a leading cause of disability and healthcare financial burden for total knee arthroplasty, rehabilitation, and disability. Inappropriate mechanical stress, immunological, or biochemical regulation reportedly disturbs homeostasis among cartilage, synovium and subchondral bone microstructure that contributes to OA pathogenesis. Control of joint-deleterious factor action is an emerging strategy to ameliorate OA-induced joint deterioration. Dickkopf-1 (Dkk-1) is a potent inhibitor for Wnt/β-catenin signaling regulation of tissue development and remodeling in physiological or pathological contexts. Dkk-1 also acts as a master deleterious factor that represses osteoblast differentiation capacity and bone repair. Associations among Dkk-1 expression, chondrocyte fate, synovial fibroblast behavior or OA incidence are merit of characterization. Patients & Methods. Cartilage, synovial tissue and fluid were harvested from informed consent OA patients underwent arthroplasty and patient with knee injuries without OA changes as controls. Primary chondrocyte cultures and synovial fibroblasts were treated with inflammatory cytokines or Dkk-1 antisense oligonucleotide or monoclonal antibodies. Knees in experimental animals were subjected to anterior cruciate ligament transection- or intra-articular collagenase injection to induce OA. Joint inflammation, integrity and subchondral bone microstructure in knees as well gait profiles were quantified using 2-deoxyglucose-probed near-infrared in vivo image, µCT, catwalk and histomorphometric analyses. Results. In clinical vignettes, patients with end-stage OA knee had higher abundances of Dkk-1 in cartilage, synovial tissue, and synovial fluid compared to control patients. Disruption of DKk-1 signaling ameliorated the promoting effects of inflammatory cytokines on the survival and cartilage matrix synthesis in primary cartilage chondrocyte cultures. Of interest, Dkk-1 neutralization attenuated the excessive angiogenic activities and matrix metalloproteinase secretion in primary synovial fibroblasts of OA knees. Dkk-1 modulation of survival or metabolic activities in chondrocytes and synovial fibroblasts were through β-catenin-dependent and -independent signaling pathways. Moreover, increased Dkk-1 expression in lesion sites and sera was associated with the incidence of femoral head osteonecrosis. Loss of Dkk-1 action alleviated bone cell apoptosis in osteonecrotic bone microenvironments. In experimental OA knee models, knockdown of Dkk-1 alleviated articular cartilage damage as evidenced by improved Mankin score in OA knees. Dkk-1 disruption also alleviated the adverse effects of OA on subchondral bone exposure and loss of trabecular bone volume and mineral acquisition in injured joints. Loss of Dkk-1 function reduced joint inflammation, vessel number, leukocyte infiltration in synovium compartment of OA joint and improved gait profiles of affected limbs. Conclusion. Dkk-1 signaling is associated with the OA knee occurrence and accelerates apoptosis, matrix degradation and angiogenic activities in chondrocytes and synovial fibroblasts of OA joint. Dkk-1 interference alleviates the promoting effects of OA on cartilage, synovial and subchondral bone remodeling. Blocking the deleterious actions of Dkk-1 in joint microenvironment will be a prospective molecular regime beneficial for retarding excessive joint deterioration in OA knees

Abstract

Robotic assistance in knee arthroplasty has become increasingly popular due to improved accuracy of prosthetic implantation. However, literature on the mid-term outcomes is limited especially that of hand-held robotic-assisted devices. We present one of the longest follow-up series to date using this novel technology and discuss the learning curve for introducing robotic technology into our practice.

The purpose of this single-surgeon study is to evaluate the survival, patient-reported outcomes and learning curve for handheld boundary-controlled robotic-assisted unicompartmental knee arthroplasties (HBRUKAs) at our hospital.

This retrospective study evaluates 100 cases (94 Medial, 6 Lateral) performed by a single surgeon between October 2012 and July 2018. 52% were males, mean age was 64.5y (range 47.3y-85.2y) and mean BMI was 31.3 (range 21.8–43). Both inlay (40%) and onlay (60%) designs were implanted. Patients were followed up routinely at 1 and 5 years with Oxford Knee Scores (OKS) recorded. The learning curve was determined by tourniquet times.

At a mean follow-up of 4.3 years (range 1.6y–7.3y), survivorship was 97%. There were three revisions: One case of aseptic loosening (1.5y), one case of deep-infection (3.8y) and one case of contralateral compartment osteoarthritis progression (5y). Mean 5-year OKS was 39.8. A 14.3% reduction in mean tourniquet times between the first 25 cases (105.5minutes) and subsequent cases (90.4minutes) was seen.

This single-surgeon study showed good survivorship and patient-reported outcomes for HBRUKAs at our hospital. A learning curve of approximately 25 cases was shown, with significant decreases in tourniquet times with respect to increased surgeon experience.

Abstract

Introduction

A common goal of total knee arthroplasty (TKA) is to restore normal knee kinematics. While substantial data is available on TKA kinematics, information regarding non-implanted knee kinematics is less well studied especially in larger patient populations. The objectives of this study were to determine normal femorotibial kinematics in a large number of non-implanted knees and to investigate parameters that yield higher knee flexion with weight-bearing activities.

Abstract

Abstract

Abstract

Introduction

Valgus deformity in an end stage osteoarthritic knee can be difficult to correct with no clear consensus on case management. Dependent on if the joint can be reduced and the degree of medial laxity or distension, a surgeon must use their discretion on the correct method for adequate lateral releases. Robotic assisted (RA) technology has been shown to have three dimensional (3D) cut accuracy which could assist with addressing these complex cases. The purpose of this work was to determine the number of soft tissue releases and component orientation of valgus cases performed with RA total knee arthroplasty (TKA).

Introduction

Robotics have been applied to total knee arthroplasty (TKA) to improve surgical precision in components’ placement, providing a physiologic ligament tensioning throughout knee range of motion. The purpose of the present study is to evaluate femoral and tibial components’ positioning in robotic-assisted TKA after fine-tuning according to soft tissue tensioning, aiming symmetric and balanced medial and lateral gaps in flexion/extension.