Aims. Analysis of the morphology of the distal femur, and by extension of the femoral components in total knee arthroplasty (TKA), has largely been related to the aspect ratio, which represents the width of the femur. Little is known about variations in trapezoidicity (i.e. whether the femur is more rectangular or more trapezoidal). This study aimed to quantify additional morphological characteristics of the distal femur and identify anatomical features associated with higher risks of over- or under-sizing of components in TKA. Methods. We analysed the shape of 114 arthritic knees at the time of primary TKA using the pre-operative CT scans. The aspect ratio and trapezoidicity ratio were quantified, and the post-operative prosthetic overhang was calculated. We compared the morphological characteristics with those of 12 TKA models. Results. There was significant variation in both the aspect ratio and trapezoidicity ratio between individuals. Femoral trapezoidicity was mostly due to an inward curve of the medial cortex. Overhang was correlated with the aspect ratio (with a greater chance of overhang in narrow femurs), trapezoidicity ratio (with a greater chance in trapezoidal femurs), and the tibio-femoral angle (with a greater chance in valgus knees). . Discussion. This study shows that rectangular/trapezoidal variability of the distal femur cannot be ignored. Most of the femoral components which were tested appeared to be excessively rectangular when compared with the bony contours of the distal femur. These findings suggest that the design of TKA should be more concerned with matching the trapezoidal/rectangular shape of the native femur. Take home message: The distal femur is considerably more trapezoidal than most femoral components, and therefore, care must be taken to avoid anterior prosthetic overhang in TKA. Cite this article: Bone Joint J 2016;98-B:49–57

Aims

The transepicondylar axis is a well-established reference for the determination of femoral component rotation in total knee arthroplasty (TKA). However, when severe bone loss is present in the femoral condyles, rotational alignment can be more complicated. There is a lack of validated landmarks in the supracondylar region of the distal femur. Therefore, the aim of this study was to analyze the correlation between the surgical transepicondylar axis (sTEA) and the suggested dorsal cortex line (DCL) in the coronal plane and the inter- and intraobserver reliability of its CT scan measurement.

1. Double osteotomy was performed on 1 50 knees between 1961 and 1969. The first fifty-seven cases were assessed independently. 2. The operation of osteotomy of the upper end of the tibia and the lower end of the femur is described. it is emphasised that the osteotomy sites are close to the bone ends and well within the cancellous expansion. 3. The indications for the operation are pain and loss of function in a mobile arthritic knee joint. 4. Flexion of the knee is important during the operation to allow the popliteal artery to be moved away from bone. Arteriograms at necropsy show the danger of damaging the popliteal artery when the knee is extended. 5. The operation appears to be equally effective in osteoarthritis and rheumatoid arthritis. The proliferated synovium of the active rheumatoid knee regresses rapidly following operation. 6. The operation has resulted in relief of pain and increase in function in many knees which had no deformity. When a deformity did exist before operation recurrence of the deformity did not appear to influence the result. 7. The cause of relief of symptoms after osteotomy is not known, and it is suggested that answers to the following questions should be sought: Why are some arthritic knees painful and some not ? Why does physiotherapy relieve pain ? Why does osteotomy relieve pain? Why is double osteotomy followed by regression of synovial proliferation ? Why does osteotomy sometimes fail ? Would osteotomy of one bone (tibia or femur) be sufficient?

The February 2024 Knee Roundup³⁶⁰ looks at: Do patients with hypoallergenic total knee arthroplasty implants for metal allergy do worse? An analysis of healthcare utilizations and patient-reported outcome measures; Defining a successful total knee arthroplasty; Incidence, microbiological studies, and factors associated with periprosthetic joint infection after total knee arthroplasty; A modified Delphi consensus statement on patellar instability; Cause for concern? Significant cement coverage in retrieved metaphyseal cones after revision total knee arthroplasty; Prevalence of post-traumatic osteoarthritis after anterior cruciate ligament injury remains high despite advances in surgical techniques; Cost-effectiveness of arthroscopic partial meniscectomy versus physical therapy for traumatic meniscal tears in patients aged under 45 years.

Aims

The outcomes of patients with unexpected positive cultures (UPCs) during revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain unknown. The objectives of this study were to establish the prevalence and infection-free implant survival in UPCs during presumed aseptic single-stage revision THA and TKA at mid-term follow-up.

The April 2023 Knee Roundup³⁶⁰ looks at: Does bariatric surgery reduce complications after total knee arthroplasty?; Mid-flexion stability in total knee arthroplasties implanted with kinematic alignment: posterior-stabilized versus medial-stabilized implants; Inflammatory response in robotic-arm-assisted versus conventional jig-based total knee arthroplasty; Journey II bicruciate stabilized (JII-BCS) and GENESIS II total knee arthroplasty: the CAPAbility, blinded, randomized controlled trial; Lifetime risk of revision and patient factors; Platelet-rich plasma use for hip and knee osteoarthritis in the USA; Where have the knee revisions gone?; Tibial component rotation in total knee arthroplasty: CT-based study of 1,351 tibiae.

The aim of mechanical alignment in total knee arthroplasty is to align all knees into a fixed neutral position, even though not all knees are the same. As a result, mechanical alignment often alters a patient’s constitutional alignment and joint line obliquity, resulting in soft-tissue imbalance. This annotation provides an overview of how the Coronal Plane Alignment of the Knee (CPAK) classification can be used to predict imbalance with mechanical alignment, and then offers practical guidance for bone balancing, minimizing the need for soft-tissue releases.

Cite this article: Bone Joint J 2024;106-B(6):525–531.

The December 2023 Knee Roundup³⁶⁰ looks at: Obesity is associated with greater improvement in patient-reported outcomes following primary total knee arthroplasty; Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?; Robotic or manual total knee arthroplasty: a randomized controlled trial; Patient-relevant outcomes following first revision total knee arthroplasty, by diagnosis: an analysis of implant survivorship, mortality, serious medical complications, and patient-reported outcome measures using the National Joint Registry data set; Sagittal alignment in total knee arthroplasty: are there any discrepancies between robotic-assisted and manual axis orientation?; Tourniquet use does not impact recovery trajectory in total knee arthroplasty; Impact of proximal tibial varus anatomy on survivorship after medial unicondylar knee arthroplasty; Bone cement directly to the implant in primary total knee arthroplasty?; Maintaining joint line obliquity optimizes outcomes in patients with constitutionally varus knees.

The December 2022 Knee Roundup³⁶⁰ looks at: Effect of physical therapy versus arthroscopic partial meniscectomy: the ESCAPE trial at five years; Patellofemoral arthroplasty or total knee arthroplasty: a randomized controlled trial; Rehabilitation versus surgical reconstruction for anterior cruciate ligament injury; End-stage knee osteoarthritis in Australia: the effect of obesity; Do poor patient-reported outcome measures at six months relate to knee revision?; What is the cost of nonoperative interventions for knee osteoarthritis?

The August 2023 Knee Roundup³⁶⁰ looks at: Curettage and cementation of giant cell tumour of bone: is arthritis a given?; Anterior knee pain following total knee arthroplasty: does the patellar cement-bone interface affect postoperative anterior knee pain?; Nickel allergy and total knee arthroplasty; The use of artificial intelligence for the prediction of periprosthetic joint infection following aseptic revision total knee arthroplasty; Ambulatory unicompartmental knee arthroplasty: development of a patient selection tool using machine learning; Femoral asymmetry: a missing piece in knee alignment; Needle arthroscopy – a benefit to patients in the outpatient setting; Can lateral unicompartmental knees be done in a day-case setting?

Aims

The aim of this study was to determine whether obesity had a detrimental effect on the long-term performance and survival of medial unicompartmental knee arthroplasties (UKAs).

Aims

The primary aim of this study was to assess the feasibility of recruiting and retaining patients to a patient-blinded randomized controlled trial comparing corticosteroid injection (CSI) to autologous protein solution (APS) injection for the treatment of subacromial shoulder pain in a community care setting. The study focused on recruitment rates and retention of participants throughout, and collected data on the interventions’ safety and efficacy.

Aims

The goal was to evaluate tibiofemoral knee joint kinematics during stair descent, by simulating the full stair descent motion in vitro. The knee joint kinematics were evaluated for two types of knee implants: bi-cruciate retaining and bi-cruciate stabilized. It was hypothesized that the bi-cruciate retaining implant better approximates native kinematics.

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.

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To map the Oxford Knee Score (OKS) and High Activity Arthroplasty Score (HAAS) items to a common scale, and to investigate the psychometric properties of this new scale for the measurement of knee health.

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Platelet-rich plasma (PRP) intra-articular injections may provide a simple and minimally invasive treatment for early-stage knee osteoarthritis (OA). This has led to an increase in its adoption as a treatment for knee OA, although there is uncertainty about its efficacy and benefit. We hypothesized that patients with early-stage symptomatic knee OA who receive multiple PRP injections will have better clinical outcomes than those receiving single PRP or placebo injections.

Aims

To identify the responsiveness, minimal clinically important difference (MCID), minimal clinical important change (MIC), and patient-acceptable symptom state (PASS) thresholds in the 36-item Short Form Health Survey questionnaire (SF-36) (v2) for each of the eight dimensions and the total score following total knee arthroplasty (TKA).