Aims. This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy. Methods. Five subjects with valgus, 12 with neutral, and ten with varus limb alignment were assessed during multiple complete cycles of level walking, downhill walking, and stair descent using a combination of dynamic videofluoroscopy, ground reaction force plates, and optical motion capture. Following 2D/3D registration, tibiofemoral kinematics and kinetics were compared between the three limb alignment groups. Results. No significant differences for the rotational or translational patterns between the different limb alignment groups were found for level walking, downhill walking, or stair descent. Neutral and varus aligned subjects showed a mean centre of rotation located on the medial condyle for the loaded stance phase of all three gait activities. Valgus alignment, however, resulted in a centrally located centre of rotation for level and downhill walking, but a more medial centre of rotation during stair descent. Knee adduction/abduction moments were significantly influenced by limb alignment, with an increasing knee adduction moment from valgus through neutral to varus. Conclusion. Limb alignment was not reflected in the condylar kinematics, but did significantly affect the knee adduction moment. Variations in frontal plane limb alignment seem not to be a main modulator of condylar kinematics. The presented data provide insights into the influence of anatomical parameters on tibiofemoral kinematics and kinetics towards enhancing clinical decision-making and surgical restoration of natural knee joint motion and loading. Cite this article: Bone Joint Res 2024;13(9):485–496

There have been many reports which suggest that in patients with tibiofemoral osteoarthritis, a reduction in joint space is demonstrated better on weight-bearing radiographs taken with the knee in semiflexion than in full extension. The reduction has been attributed to the loss of articular cartilage in the contact area in a semiflexed arthritic knee. None of these studies have, however, included normal knees. We have therefore undertaken a prospective, double-blind, randomised study in order to evaluate the difference in the joint-space of arthroscopically-proven normal tibiofemoral joints as seen on weight-bearing full-extension and 30° flexion posteroanterior radiographs. Twenty-two knees were evaluated and the results showed that there may be a difference of up to 2 mm in the two views. This difference could be attributed to the inherent differential thickness of the articular cartilage in different areas of the femoral and tibial condyles and a change in the areas of contact between them

Aims. Focal knee arthroplasty is an attractive alternative to knee arthroplasty for young patients because it allows preservation of a large amount of bone for potential revisions. However, the mechanical behaviour of cartilage has not yet been investigated because it is challenging to evaluate in vivo contact areas, pressure, and deformations from metal implants. Therefore, this study aimed to determine the contact pressure in the tibiofemoral joint with a focal knee arthroplasty using a finite element model. Methods. The mechanical behaviour of the cartilage surrounding a metal implant was evaluated using finite element analysis. We modelled focal knee arthroplasty with placement flush, 0.5 mm deep, or protruding 0.5 mm with regard to the level of the surrounding cartilage. We compared contact stress and pressure for bone, implant, and cartilage under static loading conditions. Results. Contact stress on medial and lateral femoral and tibial cartilages increased and decreased, respectively, the most and the least in the protruding model compared to the intact model. The deep model exhibited the closest tibiofemoral contact stress to the intact model. In addition, the deep model demonstrated load sharing between the bone and the implant, while the protruding and flush model showed stress shielding. The data revealed that resurfacing with a focal knee arthroplasty does not cause increased contact pressure with deep implantation. However, protruding implantation leads to increased contact pressure, decreased bone stress, and biomechanical disadvantage in an in vivo application. Conclusion. These results show that it is preferable to leave an edge slightly deep rather than flush and protruding. Cite this article: Bone Joint Res 2023;12(8):497–503

Aims. The aim of this retrospective study was to determine if there are differences in short-term clinical outcomes among four different types of matrix-associated autologous chondrocyte transplantation (MACT). Methods. A total of 88 patients (mean age 34 years (SD 10.03), mean BMI 25 kg/m. 2. (SD 3.51)) with full-thickness chondral lesions of the tibiofemoral joint who underwent MACT were included in this study. Clinical examinations were performed preoperatively and 24 months after transplantation. Clinical outcomes were evaluated using the International Knee Documentation Committee (IKDC) Subjective Knee Form, the Brittberg score, the Tegner Activity Scale, and the visual analogue scale (VAS) for pain. The Kruskal-Wallis test by ranks was used to compare the clinical scores of the different transplant types. Results. The mean defect size of the tibiofemoral joint compartment was 4.28 cm. 2. (SD 1.70). In total, 11 patients (12.6%) underwent transplantation with Chondro-Gide (matrix-associated autologous chondrocyte implantation (MACI)), 40 patients (46.0%) with Hyalograft C (HYAFF), 21 patients (24.1%) with Cartilage Regeneration System (CaReS), and 15 patients (17.2%) with NOVOCART 3D. The mean IKDC Subjective Knee Form score improved from 35.71 (SD 6.44) preoperatively to 75.26 (SD 18.36) after 24 months postoperatively in the Hyalograft group, from 35.94 (SD 10.29) to 71.57 (SD 16.31) in the Chondro-Gide (MACI) group, from 37.06 (SD 5.42) to 71.49 (SD 6.76) in the NOVOCART 3D group, and from 45.05 (SD 15.83) to 70.33 (SD 19.65) in the CaReS group. Similar improvements were observed in the VAS and Brittberg scores. Conclusion. Two years postoperatively, there were no significant differences in terms of outcomes. Our data demonstrated that MACT, regardless of the implants used, resulted in good clinical improvement two years after transplantation for localized tibiofemoral defects. Cite this article: Bone Joint Res 2021;10(7):370–379

Aims. A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes. Methods. ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions. Results. Anterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs. Conclusion. Fixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon. Cite this article: Bone Joint Res 2022;11(7):494–502

Eighty-one patients treated by patellectomy for osteoarthritis have been reviewed. Eighty-seven knees were examined with a mean follow-up period of six and a half years. Clinical and radiological assessment was carried out and the results have been analysed. A good result was achieved in 53 per cent, a fair result in 26 per cent and a poor result in 21 per cent. The overall result did not deteriorate significantly with time and the radiological appearance of the tibiofemoral joint deteriorated minimally. Pain before operation, radiological changes at the patellofemoral and tibiofemoral joints and the duration of immobilisation after operation were analysed against the end-result. The only factor before operation that indicated a good prognosis was a minimal radiological change at the tibiofemoral joint. Immobilisation for at least three weeks after operation appeared to be beneficial

We continued a prospective longitudinal follow-up study of 53 remaining patients who underwent open total meniscectomy as adolescents and who at that time had no other intra-articular pathology of the knee. Their clinical, radiological and patient-reported outcomes are described at a mean follow-up of 40 years (33 to 50). The cohort of patients who had undergone radiological evaluation previously after 30 years were invited for clinical examination, radiological evaluation and review using two patient-reported outcome measures. . A total of seven patients (13.2%) had already undergone total knee replacement at the time of follow-up. A significant difference was observed between the operated and non-operated knee in terms of range of movement and osteoarthritis of the tibiofemoral joint, indicating a greater than fourfold relative risk of osteoarthritis at 40 years post-operatively. All patients were symptomatic as defined by the Knee Injury and Osteoarthritis Outcome Score. This study represents the longest follow-up to date and it can be concluded that meniscectomy leads to symptomatic osteoarthritis of the knee later in life, with a resultant 132-fold increase in the rate of total knee replacement in comparison to their geographical and age-matched peers

Aims

The aim of this study was to evaluate whether achieving medial joint opening, as measured by the change in the joint line convergence angle (∆JLCA), is a better predictor of clinical outcomes after high tibial osteotomy (HTO) compared with the mechanical axis deviation, and to find individualized targets for the redistribution of load that reflect bony alignment, joint laxity, and surgical technique.

Aims

This study aimed to evaluate if total knee arthroplasty (TKA) femoral components aligned in either mechanical alignment (MA) or kinematic alignment (KA) are more biomimetic concerning trochlear sulcus orientation and restoration of trochlear height.

Cite this article: Bone Jt Open 2024;5(12):1120–1122.

Objectives. Unicompartmental knee arthroplasty (UKA) is a potential treatment for isolated bone on bone osteoarthritis when limited to a single compartment. The risk for revision of UKA is three times higher than for total knee arthroplasty (TKA). The aim of this review was to discuss the different revision options after UKA failure. Materials and Methods. A search was performed for English language articles published between 2006 and 2016. After reviewing titles and abstracts, 105 papers were selected for further analysis. Of these, 39 papers were deemed to contain clinically relevant data to be included in this review. Results. The most common reasons for failure are liner dislocation, aseptic loosening, disease progression of another compartment and unexplained pain. . UKA can be revised to or with another UKA if the failure mode allows reconstruction of the joint with UKA components. In case of disease progression another UKA can be added, either at the patellofemoral joint or at the remaining tibiofemoral joint. Often the accompanying damage to the knee joint doesn’t allow these two former techniques resulting in a primary TKA. In a third of cases, revision TKA components are necessary. This is usually on the tibial side where augments and stems might be required. Conclusions. In case of failure of UKA, several less invasive revision techniques remain available to obtain primary results. Revision in a late stage of failure or because of surgical mistakes might ask for the use of revision components limiting the clinical outcome for the patients. Cite this article: Bone Joint J 2017;99-B(1 Supple A):65–9

Aims

With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

Orthopaedic surgeons are currently faced with an overwhelming number of choices surrounding total knee arthroplasty (TKA), not only with the latest technologies and prostheses, but also fundamental decisions on alignment philosophies. From ‘mechanical’ to ‘adjusted mechanical’ to ‘restricted kinematic’ to ‘unrestricted kinematic’ — and how constitutional alignment relates to these — there is potential for ambiguity when thinking about and discussing such concepts. This annotation summarizes the various alignment strategies currently employed in TKA. It provides a clear framework and consistent language that will assist surgeons to compare confidently and contrast the concepts, while also discussing the latest opinions about alignment in TKA. Finally, it provides suggestions for applying consistent nomenclature to future research, especially as we explore the implications of 3D alignment patterns on patient outcomes.

Cite this article: Bone Joint J 2023;105-B(2):102–108.

Aims

Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))?

Aims

Therapeutic agents that prevent chondrocyte loss, extracellular matrix (ECM) degradation, and osteoarthritis (OA) progression are required. The expression level of epidermal growth factor (EGF)-like repeats and discoidin I-like domains-containing protein 3 (EDIL3) in damaged human cartilage is significantly higher than in undamaged cartilage. However, the effect of EDIL3 on cartilage is still unknown.

Aims

Pigment epithelium-derived factor (PEDF) is known to induce several types of tissue regeneration by activating tissue-specific stem cells. Here, we investigated the therapeutic potential of PEDF 29-mer peptide in the damaged articular cartilage (AC) in rat osteoarthritis (OA).

Aims

A fracture of the medial tibial plateau is a serious complication of Oxford mobile-bearing unicompartmental knee arthroplasty (OUKA). The risk of these fractures is reportedly lower when using components with a longer keel-cortex distance (KCDs). The aim of this study was to examine how slight varus placement of the tibial component might affect the KCDs, and the rate of tibial plateau fracture, in a clinical setting.

The Bisurface knee prosthesis (BP) has a posterior stabilising cam (ball-and-socket joint) in the mid-posterior region of the femorotibial joint in an attempt to improve the range of movement. Based on an in vitro weight-bearing study contact areas of the Insall/Burstein 2 (IB2) and the BP knee were compared using pressure-sensitive films. The stability afforded by the cam was evaluated by means of dislocation distances in the vertical and horizontal planes. Significant adverse anterior translation in mid-flexion was not observed with the BP knee since the cam was effective above 60° of flexion. At flexion of 60° or more, the total contact areas were larger, as the cam represented a weight-bearing surface. The dislocation distances for the BP knee compared favourably with those for the IB2 knee. We conclude that the cam of the BP knee allows good movement, stability and wear

There has been only one limited report dating from 1941 using dissection which has described the tibiofemoral joint between 120° and 160° of flexion despite the relevance of this arc to total knee replacement. We now provide a full description having examined one living and eight cadaver knees using MRI, dissection and previously published cryosections in one knee. In the range of flexion from 120° to 160° the flexion facet centre of the medial femoral condyle moves back 5 mm and rises up on to the posterior horn of the medial meniscus. At 160° the posterior horn is compressed in a synovial recess between the femoral cortex and the tibia. This limits flexion. The lateral femoral condyle also rolls back with the posterior horn of the lateral meniscus moving with the condyle. Both move down over the posterior tibia at 160° of flexion. Neither the events between 120° and 160° nor the anatomy at 160° could result from a continuation of the kinematics up to 120°. Therefore hyperflexion is a separate arc. The anatomical and functional features of this arc suggest that it would be difficult to design an implant for total knee replacement giving physiological movement from 0° to 160°