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.

The purpose of this study was to evaluate the change in sagittal tibiotalar alignment after total ankle arthroplasty (TAA) for osteoarthritis and to investigate factors affecting the restoration of alignment. . This retrospective study included 119 patients (120 ankles) who underwent three component TAA using the Hintegra prosthesis. A total of 63 ankles had anterior displacement of the talus before surgery (group A), 49 had alignment in the normal range (group B), and eight had posterior displacement of the talus (group C). Ankles in group A were further sub-divided into those in whom normal alignment was restored following TAA (41 ankles) and those with persistent displacement (22 ankles). Radiographic and clinical results were assessed. Pre-operatively, the alignment in group A was significantly more varus than that in group B, and the posterior slope of the tibial plafond was greater (p < 0.01 in both cases). The posterior slope of the tibial component was strongly associated with restoration of alignment: ankles in which the alignment was restored had significantly less posterior slope (p < 0.001). . An anteriorly translated talus was restored to a normal position after TAA in most patients. We suggest that surgeons performing TAA using the Hintegra prosthesis should aim to insert the tibial component at close to 90° relative to the axis of the tibia, hence reducing posterior soft-tissue tension and allowing restoration of normal tibiotalar alignment following surgery. Cite this article: Bone Joint J 2015;97-B:1525–32

Aims

The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery.

Aims

This study aimed to describe the use of revision knee arthroplasty in Australia and examine changes in lifetime risk over a decade.

We performed a CT-based computer simulation study to determine how the relationship between any inbuilt posterior slope in the proximal tibial osteotomy and cutting jig rotational orientation errors affect tibial component alignment in total knee replacement. Four different posterior slopes (3°, 5°, 7° and 10°), each with a rotational error of 5°, 10°, 15°, 20°, 25° or 30°, were simulated. Tibial cutting block malalignment of 20° of external rotation can produce varus malalignment of 2.4° and 3.5° with a 7° and a 10° sloped cutting jig, respectively. Care must be taken in orientating the cutting jig in the sagittal plane when making a posterior sloped proximal tibial osteotomy in total knee replacement. Cite this article: Bone Joint J 2013;95-B:1201–3

Aims

Higher osteoblastic bone activity is expected in aseptic loosening and painful unicompartmental knee arthroplasty (UKA). However, insights into normal bone activity patterns after medial UKAs are lacking. The aim of this study was to identify the evolution in bone activity pattern in well-functioning medial mobile-bearing UKAs.

In this study we present our experience with four generations of uncemented total knee arthroplasty (TKA) from Smith & Nephew: Tricon M, Tricon LS, Tricon II and Profix, focusing on the failure rates correlating with each design change. Beginning in 1984, 380 Tricon M, 435 Tricon LS, 305 Tricon 2 and 588 Profix were implanted by the senior author. The rate of revision for loosening was 1.1% for the Tricon M, 1.1% for the Tricon LS, 0.5% for the Tricon 2 with a HA coated tibial component, and 1.3% for the Profix TKA. No loosening of the femoral component was seen with the Tricon M, Tricon LS or Tricon 2, with no loosening seen of the tibial component with the Profix TKA. Regarding revision for wear, the incidence was 13.1% for the Tricon M, 6.6% for the Tricon LS, 2.3% for the Tricon 2, and 0% for the Profix. These results demonstrate that improvements in the design of uncemented components, including increased polyethylene thickness, improved polyethylene quality, and the introduction of hydroxyapatite coating, has improved the outcomes of uncemented TKA over time

Aims

Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but the solid metal implants disrupt the natural distribution of stress and strain which can lead to bone loss over time. This generates problems if the implant needs to be revised. This study investigates whether titanium lattice UKA and TKA implants can maintain natural load transfer in the proximal tibia.

Aims

Simultaneous bilateral total knee arthroplasty (TKA) has been used due to its financial advantages, overall resource usage, and convenience for the patient. The training model where a trainee performs the first TKA, followed by the trainer surgeon performing the second TKA, is a unique model to our institution. This study aims to analyze the functional and clinical outcomes of bilateral simultaneous TKA when performed by a trainee or a supervising surgeon, and also to assess these outcomes based on which side was done by the trainee or by the surgeon.

Aims

The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs).

We aimed to obtain anthropometric data on Korean knees and to compare these with data on commonly available total knee arthroplasties (TKAs). The dimensions of the femora and tibiae of 1168 knees were measured intra-operatively. The femoral components were found to show a tendency toward mediolateral (ML) under-coverage in small femurs and ML overhang in the large femurs. The ML under-coverage was most prominent for the small prostheses. The ML/anteroposterior (ML/AP) ratio of Korean tibiae was greater than that of tibial components. This study shows that, for different reasons, current TKAs do not provide a reasonable fit for small or large Korean knees, and that the ‘gender-specific’ and ‘stature-specific’ components help for large Korean femurs but offer less satisfactory fits for small femurs. Specific modifications of prostheses are needed for Asian knees

We investigated the characteristics of patients who achieved Japanese-style deep flexion (seiza-sitting) after total knee replacement (TKR) and measured three-dimensional positioning and the contact positions of the femoral and tibial components. Seiza-sitting was achieved after surgery by 23 patients (29 knees) of a series of 463 TKRs in 341 patients. Pre-operatively most of these patients were capable of seiza-sitting, had a lower body mass index and a favourable attitude towards the Japanese lifestyle (27 of 29 knees). According to two-/three-dimensional image registration analysis in the seiza-sitting position, flexion, varus and internal rotation angles of the tibial component relative to the femoral component had means of 148° (. sd. 8.0), 1.9° (. sd. 3.2) and 13.4° (. sd. 5.9), respectively. Femoral surface contact positions tended to be close to the posterior edge of the tibial polyethylene insert, particularly in the lateral compartment, but only 8.3% (two of 24) of knees showed femoral subluxation over the posterior edge. The mean contact positions of the femoral cam on the tibial post were located 7.8 mm (. sd. 1.5) proximal to the lowest point of the polyethylene surface and 5.5 mm (. sd. 0.9) medial to the centre of the post, indicating that the post-cam contact position translated medially during seiza-sitting, but not proximally. Collectively, the seiza-sitting position seems safe against component dislocation, but the risks of posterior edge loading and breakage of the tibial polyethylene post remain. Cite this article: Bone Joint J 2013;95-B:782–7

We performed a randomised controlled trial comparing computer-assisted surgery (CAS) with conventional surgery (CONV) in total knee replacement (TKR). Between 2009 and 2011 a total of 192 patients with a mean age of 68 years (55 to 85) with osteoarthritis or arthritic disease of the knee were recruited from four Norwegian hospitals. At three months follow-up, functional results were marginally better for the CAS group. Mean differences (MD) in favour of CAS were found for the Knee Society function score (MD: 5.9, 95% confidence interval (CI) 0.3 to 11.4, p = 0.039), the Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales for ‘pain’ (MD: 7.7, 95% CI 1.7 to 13.6, p = 0.012), ‘sports’ (MD: 13.5, 95% CI 5.6 to 21.4, p = 0.001) and ‘quality of life’ (MD: 7.2, 95% CI 0.1 to 14.3, p = 0.046). At one-year follow-up, differences favouring CAS were found for KOOS ‘sports’ (MD: 11.0, 95% CI 3.0 to 19.0, p = 0.007) and KOOS ‘symptoms’ (MD: 6.7, 95% CI 0.5 to 13.0, p = 0.035). The use of CAS resulted in fewer outliers in frontal alignment (> 3° malalignment), both for the entire TKR (37.9% vs 17.9%, p = 0.042) and for the tibial component separately (28.4% vs 6.3%, p = 0.002). Tibial slope was better achieved with CAS (58.9% vs 26.3%, p < 0.001). Operation time was 20 minutes longer with CAS. In conclusion, functional results were, statistically, marginally in favour of CAS. Also, CAS was more predictable than CONV for mechanical alignment and positioning of the prosthesis. However, the long-term outcomes must be further investigated. Cite this article: Bone Joint J 2014; 96-B:609–18

Aims. Knee arthroplasty surgery is a highly effective treatment for arthritis and disorders of the knee. There are a wide variety of implant brands and types of knee arthroplasty available to surgeons. As a result of a number of highly publicized failures, arthroplasty surgery is highly regulated in the UK and many other countries through national registries, introduced to monitor implant performance, surgeons, and hospitals. With time, the options available within many brand portfolios have grown, with alternative tibial or femoral components, tibial insert materials, or shapes and patella resurfacings. In this study we have investigated the effect of the expansion of implant brand portfolios and where there may be a lack of transparency around a brand name. We also aimed to establish the potential numbers of compatible implant construct combinations. Methods. Hypothetical implant brand portfolios were proposed, and the number of compatible implant construct combinations was calculated. Results. A simple knee portfolio with cemented cruciate-retaining (CR) and posterior-stabilized (PS) components, with and without a patella, has four combinations. If there are two options available for each component, the numbers double for each option, resulting in 32 combinations. The effect of adding a third option multiplies the number by 1.3. Introducing compatible uncemented options, with the effect of hybrids, multiplies the number by 4. An implant portfolio with two femoral components (both in CR and PS), with two insert options and a patella, all in cemented and uncemented versions leads to 192 possible compatible implant construct combinations. There are implant brands available to surgeons with many more than two options. Conclusion. This study demonstrates that the addition of multiple variants within a knee brand portfolio leads to a large number (many hundreds) of compatible implant construct combinations. Revision rates of implant combinations are not currently reviewed at this level of granularity, leading to the risk of camouflage of true outcomes. Cite this article: Bone Joint J 2021;103-B(10):1555–1560

We carried out a prospective investigation into the radiological outcomes of uncemented Oxford medial compartment unicondylar replacement in 220 consecutive patients (231 knees) performed in a single centre with a minimum two-year follow-up. The functional outcomes using the mean Oxford knee score and the mean high-activity arthroplasty score were significantly improved over the pre-operative scores (p < 0.001). There were 196 patients with a two-year radiological examination performed under fluoroscopic guidance, aiming to provide images acceptable for analysis of the bone–implant interface. Of the six tibial zones examined on each knee on the anteroposterior radiograph, only three had a partial radiolucent line. All were in the medial aspect of the tibial base plate (zone 1) and all measured < 1 mm. All of these patients were asymptomatic. There were no radiolucent lines seen around the femoral component or on the lateral view. There was one revision for loosening at one year due to initial inadequate seating of the tibial component. These results confirm that the early uncemented Oxford medial unicompartmental compartmental knee replacements were reliable and the incidence of radiolucent lines was significantly decreased compared with the reported results of cemented versions of this implant. These independent results confirm those of the designing centre

Locking after total knee replacement is uncommon and is generally caused by the formation of fibrous tissue around the patella. We report an unusual cause of locking resulting from intermittent occlusion of the popliteal artery, which was tethered to cement at the posterior aspect of the tibial component

We randomised 62 knees to receive either cemented or cementless versions of the Oxford unicompartmental knee replacement. The implants used in both arms of the study were similar, except that the cementless components were coated with porous titanium and hydroxyapatite. The tibial interfaces were studied with fluoroscopically-aligned radiographs. At one year there was no difference in clinical outcome between the two groups. Narrow radiolucent lines were seen at the bone-implant interfaces in 75% of cemented tibial components. These were partial in 43%, and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. These differences are statistically significant (p < 0.0001) and imply satisfactory bone ingrowth into the cementless implants

Aims

Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA).

After obtaining informed consent, 80 patients were randomised to undergo a navigated or conventional total knee replacement. All received a cemented, unconstrained, cruciate-retaining implant with a rotating platform. Full-length standing and lateral radiographs and CT scans of the hip, knee and ankle joint were carried out five to seven days after operation. No notable differences were found between computer-assisted navigation and conventional implantation techniques as regards the rotational alignment of the femoral or tibial components. Although the deviation from the transepicondylar axis was relatively low, there was a considerable range of deviation for the tibial rotational alignment. There was no statistically significant difference regarding the occurrence pattern of outliers in mechanical malalignment but the number of outliers was reduced in the navigated group