Radiographs of 110 patients who had undergone 120 high tibial osteotomies (60 closed-wedge, 60 open-wedge) were assessed for posterior tibial slope before and after operation, and before removal of the hardware. In the closed-wedge group the mean slope was 5.7° (sd 3.8) before and 2.4° (sd 3.9) immediately after operation, and 2.4° (sd 3.4) before removal of the hardware. In the open-wedge group, these values were 5.0° (sd 3.7), 7.7° (sd 4.3) and 8.1° (sd 3.9) respectively, when stabilised with a non-locking plate, and 7.7° (sd 3.5), 9.4° (sd 4.1) and 9.1° (sd 3.8), when stabilised with a locking plate. The reduction in slope (−2.7° (sd 4.1)) in the closed-wedge group and the increase (+2.5° (sd 3.4), in the open-wedge group was significantly different before and after operation (p = 0.002, p = 0.003). In no group were the changes in slope directly after operation and before removal of the hardware significant (p > 0.05). There was no correlation between the amount of correction in the frontal plane and the post-operative change in slope.

Posterior tibial slope decreases after closed-wedge high tibial osteotomy and increases after an open-wedge procedure because of the geometry of the proximal tibia. The changes in the slope are stable over time, emphasising the influence of the operative procedure rather than of the implant.

The optimal management of the tibial slope in achieving a high flexion angle in posterior-stabilised (PS) total knee replacement (TKR) is not well understood, and most studies evaluating the posterior tibial slope have been conducted on cruciate-retaining TKRs. We analysed pre- and post-operative tibial slope differences, pre- and post-operative coronal knee alignment and post-operative maximum flexion angle in 167 patients undergoing 209 TKRs. The mean pre-operative posterior tibial slope was 8.6° (1.3° to 17°) and post-operatively it was 8.0° (0.1° to 16.7°). Multiple linear regression analysis showed that the absolute difference between pre- and post-operative tibial slope (p < 0.001), post-operative coronal alignment (p = 0.02) and pre-operative range of movement (p < 0.001) predicted post-operative flexion. The variance of change in tibial slope became larger as the post-operative maximum flexion angle decreased. The odds ratio of having a post-operative flexion angle < 100° was 17.6 if the slope change was > 2°. Our data suggest that recreation of the anatomical tibial slope appears to improve maximum flexion after posterior-stabilised TKR, provided coronal alignment has been restored. Cite this article: Bone Joint J 2013;95-B:1354–8

We report the outcome of 32 patients (37 knees) who underwent hemicallostasis with a dynamic external fixator for osteoarthritis of the medial compartment of the knee. There were 16 men (19 knees) and 16 women (18 knees) with a mean age at operation of 54.6 years (27 to 72). The aim was to achieve a valgus overcorrection of 2° to 8° or mechanical axis at 62.5% (± 12.5%). At a mean follow-up of 62.8 months (51 to 81) there was no change in the mean range of movement, and no statistically significant difference in the Insall-Salvati index or tibial slope (p = 0.11 and p = 0.15, respectively). The mean hip-knee-ankle angle changed from 190.6 (183° to 197°) to 176.0° (171° to 181°), with a mean final position of the mechanical axis of 58.5% (35.1% to 71.2%). The desired alignment was attained in 31 of 37 (84%) knees. There were 21 excellent, 13 good, two fair and one poor result according to the Oxford knee score with no correlation between age and final score. This score was at its best at one year with a statistically significant deterioration at two years (p = 0.001) followed by a small but not statistically significant deterioration until the final follow-up (p = 0.17). All the knees with Ahlback grade 1 osteoarthritis had excellent or good results. Complications included pin tract infections involving 16.4% of all pins used, delayed union in two, knee stiffness in four, fracture of the lateral cortex in one and ring sequestrum in one. In conclusion, hemicallostasis provides precision in attaining the desired alignment without interfering with tibial slope or patellar height, and is relatively free of serious complications

Aims. We conducted a randomised controlled trial to assess the accuracy of positioning and alignment of the components in total knee arthroplasty (TKA), comparing those undertaken using standard intramedullary cutting jigs and those with patient-specific instruments (PSI). Patients and Methods. There were 64 TKAs in the standard group and 69 in the PSI group. The post-operative hip-knee-ankle (HKA) angle and positioning was investigated using CT scans. Deviation of > 3° from the planned position was regarded as an outlier. The operating time, Oxford Knee Scores (OKS) and Short Form-12 (SF-12) scores were recorded. Results. There were 14 HKA-angle outliers (22%) in the standard group and nine (13%) in the PSI group (p = 0.251). The mean HKA-angle was 0.5° varus in the standard group and 0.2° varus in the PSI group (p = 0.492). The accuracy of alignment in the coronal and axial planes and the proportion of outliers was not different in the two groups. The femoral component was more flexed (p = 0.035) and there were significantly more tibial slope outliers (29% versus 13%) in the PSI group (p = 0.032). Operating time and the median three-month OKS were similar (p = 0.218 and p = 0.472, respectively). Physical and mental SF-12 scores were not significantly different at three months (p = 0.418 and p = 0.267, respectively) or at one year post-operatively (p = 0.114 and p = 0.569). The median one-year Oxford knee score was two points higher in the PSI group (p = 0.049). Conclusion. Compared with standard intramedullary jigs, the use of PSI did not significantly reduce the number of outliers or the mean operating time, nor did it clinically improve the accuracy of alignment or the median Oxford Knee Scores. Our data do not support the routine use of PSI when undertaking TKA. Cite this article: Bone Joint J 2016;98-B:1043–9

The aim of this study was to evaluate the risk factors for dislocation of the bearing after a mobile-bearing Oxford medial unicompartmental knee replacement (UKR) and to test the hypothesis that surgical factors, as measured from post-operative radiographs, are associated with its dislocation. From a total of 480 UKRs performed between 2001 and 2012, in 391 patients with a mean age of 66.5 years (45 to 82) (316 female, 75 male), we identified 17 UKRs where bearing dislocation occurred. The post-operative radiological measurements of the 17 UKRs and 51 matched controls were analysed using conditional logistic regression analysis. The post-operative radiological measurements included post-operative change in limb alignment, the position of the femoral and tibial components, the resection depth of the proximal tibia, and the femoral component-posterior condyle classification. We concluded that a post-operative decrease in the posterior tibial slope relative to the pre-operative value was the only significant determinant of dislocation of the bearing after medial Oxford UKR (odds ratio 1.881; 95% confidence interval 1.272 to 2.779). A post-operative posterior tibial slope < 8.45° and a difference between the pre-operative and post-operative posterior tibial slope of > 2.19° may increase the risk of dislocation. Cite this article: Bone Joint J 2014; 96-B:914–22

We studied the intra- and interobserver reliability of measurements of the position of the components after total knee replacement (TKR) using a combination of radiographs and axial two-dimensional (2D) and three-dimensional (3D) reconstructed CT images to identify which method is best for this purpose. A total of 30 knees after primary TKR were assessed by two independent observers (an orthopaedic surgeon and a radiologist) using radiographs and CT scans. Plain radiographs were highly reliable at measuring the tibial slope, but showed wide variability for all other measurements; 2D-CT also showed wide variability. 3D-CT was highly reliable, even when measuring rotation of the femoral components, and significantly better than 2D-CT. Interobserver variability in the measurements on radiographs were good (intraclass correlation coefficient (ICC) 0.65 to 0.82), but rotational measurements on 2D-CT were poor (ICC 0.29). On 3D-CT they were near perfect (ICC 0.89 to 0.99), and significantly more reliable than 2D-CT (p < 0.001). 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components. Rotational measurements in particular should be performed on 3D-reconstructed CT images. When faced with a poorly functioning TKR with concerns over component positioning, we recommend 3D-CT as the investigation of choice

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

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

The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population.

Aims

The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).

Aims

We have previously reported the mid-term outcomes of revision total knee arthroplasty (TKA) for flexion instability. At a mean of four years, there were no re-revisions for instability. The aim of this study was to report the implant survivorship and clinical and radiological outcomes of the same cohort of of patients at a mean follow-up of ten years.

Aims

The extensive variation in axial rotation of tibial components can lead to coronal plane malalignment. We analyzed the change in coronal alignment induced by tray malrotation.

Aims

The primary aim of this study was to compare the postoperative systemic inflammatory response in conventional jig-based total knee arthroplasty (conventional TKA) versus robotic-arm assisted total knee arthroplasty (robotic TKA). Secondary aims were to compare the macroscopic soft tissue injury, femoral and tibial bone trauma, localized thermal response, and the accuracy of component positioning between the two treatment groups.

Aims

Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment.

Aims

Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology.

Aims

To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period.

Aims

The purpose of the present study was to compare patient-specific instrumentation (PSI) and conventional surgical instrumentation (CSI) for total knee arthroplasty (TKA) in terms of early implant migration, alignment, surgical resources, patient outcomes, and costs.

Aims

Aseptic loosening of the tibial component is a frequent cause of failure in primary total knee arthroplasty (TKA). Management options include an isolated tibial revision or full component revision. A full component revision is frequently selected by surgeons unfamiliar with the existing implant or who simply wish to “start again”. This option adds morbidity compared with an isolated tibial revision. While isolated tibial revision has a lower morbidity, it is technically more challenging due to difficulties with exposure and maintaining prosthetic stability. This study was designed to compare these two reconstructive options.

Aims

Between 15% and 20% of patients remain dissatisfied following total knee arthroplasty (TKA). The SAIPH knee system (MatOrtho, Surrey, United Kingdom) is a medial ball and socket TKA that has been designed to replicate native knee kinematics in order to maximize the range of movement, stability, and function. This system is being progressively introduced in a stepwise fashion, with this study reporting the mid-term clinical and radiological outcomes.

Aims

This aim of this study was to assess the feasibility of designing and introducing generic 3D-printed instrumentation for routine use in total knee arthroplasty.