Aim. Knee arthrodesis (KA) and above knee amputation (AKA) have been used for salvage of failed total knee arthroplasty (TKA) in the setting of periprosthetic joint infection (PJI). The factors that lead to a failed fusion and progression to AKA are not well understood. The purpose of our study was to determine factors associated with failure of a staged fusion for PJI and predictive of progression to AKA. Method. We retrospectively reviewed a single-surgeon series of failed TKA for PJI treated with two-stage KA between 2000 and 2016 with minimum 2-year follow-up. Patient demographics, comorbidities, surgical history, tissue compromise, and radiographic data were recorded. Outcomes were additional surgery, delayed union, Visual Analog Pain scale (VAS) and Western Ontario and McMaster Activity score (WOMAC). No power analysis was performed for this retrospective study. Medians are reported as data were not normally distributed. Results. Fifty-one knees underwent fusion with median follow-up of 7 years (interquartile range (IQR) of 2–18 years). Median age was 71 years old (IQR 47 – 98), with a M:F ratio of 23:28. Median BMI was 34.3 kg/m2 (IQR 17.9–61). Infection was eradicated in 47 knees (92.2%); 24 knees (47.0%) required no additional surgery. 41 patients (83.6%) remained ambulatory after knee fusion, with 21% of these patients (10 total) requiring no ambulatory assistive device. Median VAS following arthrodesis was 4.6 (range 0–10). Median WOMAC was 36.2 (range 9–86). Three TKAs (5.9%) underwent AKA for overwhelming infection. Predictors of AKA were chronic kidney disease (OR 4.0, 95% CI 0.6–26.8), peripheral vascular disease (OR 3.5, 95% CI 0.3–44.7), AORI III bone loss (OR 2.6, 95% CI 0.4–35.2), instability (OR 2.2, 95% CI 0.2–15.9), and immunosuppression (OR 1.1, 95% CI 0.1–7.8). Tobacco use (OR 8.6, 95%CI 2.4–31.4), BMI>25 (OR 3.8, 95% CI 0.43–32.5) and instability prior to arthrodesis (OR 2.51, 95% CI 0.77–8.21) were associated with non-union. All other risk factors (gender, diabetes mellitus, chronic kidney disease, peripheral vascular disease, massive bone stock loss, and immunosuppression) were not associated with arthrodesis failure. Conclusions. Staged KA for PJI in severely compromised hosts provides a functional limb free of infection and rarely results in conversion to AKA. Given our small sample size, ability to establish statistical significance of predictive factors for AKA after PJI was limited, but CKD, peripheral vascular disease, AORI III bone loss, instability, and immunosuppression trended towards significance as predictors of failure of KA after PJI predisposing to AKA

Aim & introduction. Infected knee with bone defect resulting from failed total knee arthroplasty (TKA) or destruction of native joint can necessitate restoration of segmental defect and arthrodesis for therapy of infection and maintenance of walking ability. In segmental knee defect external fixators or KAFO are not suitable, not comfortable and poor tolerated by elderly patients. Both custom-made Femoro-Tibial Nail (FTN) combined with acrylic cement spacer and Knee Arthrodesis Nail System (KANS) offer maintenance of supportive function of extremity and avoidance of leg length discrepance after removal of TKA. Method. The group consists of 13 patients. In 12 cases knee arthrodesis have been performed due to infection with bone defect after removal of infected TKA, and in 1case due to inflammatory destruction of native knee joint. In 7 cases FTN with ALAC spacer and in 6 cases KANS (5 cases Orthopedic Salvage System-OSS; 1 case Link KANS) was used. In cases treated with FTN the gap between distal femur and proximal tibia was filled with hand-made acrylic cement spacer loaded with selected antibiotic (2g per 40 g cement) so that the spacer finally gained cylindrical shape. Results. Stable knee was noted after 7 years in 4 of 7 knees treated with FTN with ALAC spacer and after 2 years in 6 of 6 after KANS. Infection free knee was gained after 7 years in 4 of 7 cases treated with FTN with ALAC spacer and after 2 years in 5 of 6 cases treated with KANS. Amputation was necessary after 6 years in 3 of 7 cases treated with FTN with ALAC spacer and after 2 years in none case treated with KANS. Complications occurred in 2 cases after FTN with ALAC spacer (1x: FTN breackage, 1x: stress fracture of femoral neck) and in 1 case after KANS (OSS implant failure). Replacement of FTN nail and cement spacer in 1 case and respectively revision of OSS KANS in 1 cases was performed. Conclusions. Compared with the KANS, custom-made FTN combined with ALAC spacer proved to be effective up to 6 years, but shoved higher rate of complications and amputations after 6 years. It can be considered as a temporary low-cost salvage procedure for infected TKA with segmental bone defect as 1. st. stage in two-stage arthrodesis for infected knee prosthesis

Background. The use of Computed Tomography (CT) as a medical imaging tool has widespread applications in the field of knee surgery. Surgeons use a CT scan in a conventional way during the pre-operative stage, to plan the position of the femoral component in the horizontal plane. In the post-operative stage, the use of a CT scan is a routine tool in the evaluation of failed TKA as rotational malalignment of the femoral component has been determined as a cause of poor clinical outcome after TKA. Aim. How accurately can we measure the different angles with importance for alignment on a 3D-image in comparison to a standard CT, 2D, image. Material and methods. This study includes patients above 55 years of age who were scheduled for a TKA at our centre and who had a pre- and postoperative full-leg length computed tomography (CT). These images were analysed using Mimics V 16.0 ® and 3-matic V 8.0 ® (Materialise, Haasrode, Belgium) to create the surface reconstruction and perform the 3D-measurements. Different angles were measured pre- and post-operatively on these images both in 2D as in 3D: condylar twist angle (CTA), posterior condylar angle (PCA), hip-knee-ankle angle (HKA), tibiofemoral rotation angle (TFRA), posterior tilt of the tibial implant (STPA) and the frontal plane angle of the tibial implant (FTPA). A power analysis showed a needed sample size of 18 patients. Pre-operatively 21 patients were included, 18 of them also received a post-operative full-leg CT. Three observers participated in the study and they all performed all analyses twice with a minimum interval of one week for obtaining intra-observer repeatability. Statistical analysis was performed to obtain the intra- and interobserver variability. Results. The intra-and interobserver intra-class coefficients (ICC) were evaluated using the classification of Landis&Koch (see table). Preoperative results: Rotation of femoral component in 3D: ICC CTA=0,73; ICC PCA=0,66. Rotation in 2D: ICC PCA=0,75, ICC CTA=0,84. The highest ICC was found for the HKA: ICC>0,98 both 2D and 3D. Postoperative results. All ICC's are in the highest category (‘almost perfect’) except for the intraobserver ICC PCA in 2D which was ‘substantial’. Conclusions and clinical implications. CT-evaluation is invaluable for the preoperative planning of the position of the femoral component, for the evaluation of the rotation of the femoral component and for accurate assessment of the overall knee alignment,. This study demonstrates low intra- and inter- observer variability in the CT measurement of the pre- and postoperative alignment of the knee. To determine the rotation of the femoral component preoperatively there was no advantage for 3D over 2D. Post-operatively the use of the 3D technique has a lower variability with regard to the assessment of the rotation of the femoral component

The vast majority of fractures around the knee will heal with well-done internal fixation. TKA has a role in several scenarios. Acute TKA can be effective for fractures of the distal femur (especially periprosthetic) in very elderly patients where internal fixation attempts are likely to fail. Acute TKA for tibia plateau fractures may have a role in fractures in the elderly with pre-existing DJD and relatively simple fracture patterns. There is very little published literature regarding the outcomes of TKA for acute tibial plateau fracture and caution is advised until more data is available. TKA is commonly indicated for failed fixation and post-traumatic arthritis. Challenges include managing retained hardware, soft tissue injury and contracture, unusual ligamentous imbalances, and multiple prior incisions and/or flaps. Occasionally, a partial hardware removal may be appropriate. If extensive or multiple incisions are needed for hardware removal it may be wise to stage the reconstruction after soft tissue recovery. The available data on TKA for post-traumatic reconstructions generally demonstrate predictable functional improvement but higher complications

The gold standard for measuring knee alignment is the lower limb mechanical axis. This is traditionally assessed by weight-bearing full length lower limb X-rays (LLX). CT scanograms (CTS) are however, becoming increasingly popular in view of lower radiation exposure, speed and supine positioning. We assessed the correlation and reproducibility of knee joint coronal alignment using these two imaging modalities. LLX and CTS images were obtained in 24 knees with degenerate joint disease or failed TKR. Hip to ankle mechanical alignment were measured using the PACS software. Coronal knee alignment was assessed from the centre of the knee, measuring the valgus/varus angle relative to the mechanical axis. Measurements were made by two orthopaedic surgeons (Research Fellow and Consultant) on two separate occasions. The mean alignment angles measured by observers 1 and 2 on CTS were 180.29° (SD 6.04) and 180.71° (SD 6.13) respectively, while on LLX were 181.04° (SD7.58) and 181.04° (SD 7.72). The measurements between the two observers were highly correlated for both the CTS (r = 0.97, p < 0.001) and the LLX (r = 0.99, p < 0.001). The angles measured on CTS and LLX were highly correlated (r = 0.826, p < 0.001) with high degree of internal consistency (ICC = 0.804). Malalignment of greater than 5° was seen in 19% of the CTS and 35% of the LLX. There was good correlation between CT scanogram and weight-bearing X-ray measurements in normally-aligned knees. However, as expected, in the malaligned lower limb, the influence of weight-bearing is critical which demonstrates the significance of weight-bearing X-rays

Full-thickness burns around the knee can involve the extensor mechanism. The gastrocnemius flap is well described for soft tissue reconstruction around the knee. We describe a method where a Whichita Fusion Nail¯ knee arthrodesis, combined with a medial gastrocnemius muscle flap was used to salvage the knee and preserve the lower leg following a full-thickness contact burn. The gastrocnemius flap for wound coverage of an open knee joint was originally described in 1970 and remains the workhorse for soft tissue knee reconstruction. There are a number of local alternatives including the vastus lateralis, medialis and sartorius flap; and perforator flaps such as the medial sural artery perforator island flap and islanded posterior calf perforator flap, however many of these are unsuitable for larger defects. Full-thickness burns around the knee can put the extensor mechanism at risk and subsequent rupture is a possible consequence. The gastrocnemius flap has been used to cover a medial knee defect with exposed joint cavity following a burn and also been used in post burn contracture release around the knee. The primary indication for Wichita fusion nail is a failed total knee replacement. It allows intramedullary stabilization with compression at the arthrodesis site to stimulate bone union. With fusion rates reported up to 100% and low complication rates as compared to other methods of fusion, the technique has a useful role in limb salvage type procedures. While use of the gastrocnemius flap in knee burns has been described before we believe this is the first time that this combination of techniques, namely knee arthrodesis with soft tissue reconstruction using a gastrocnemius flap, has been reported. Combining these procedures with a multidisciplinary approach provides a useful alternative leading to limb salvage and avoiding the need for an above knee amputation when extensor reconstruction is not possible

The initial application of bone ingrowth technology to the fixation of total knee arthroplasty (TKA) components without bone cement was based on the premise that bone cement was “not biologic”, and so over time would undergo fatigue failure with subsequent loosening. It was hoped that this problem could be obviated by cementless fixation by bone ingrowth, which would remodel over time and not fatigue. In addition, it was anticipated that the failed cementless TKA might be easier to revise and leave the surgeon with more bone to work with. Whether or not cementless fixation of TKA components was justified on any of these counts was uncertain through the first 2 decades of their use. Much of the data accumulated during that period poorly supported these contentions, while cemented TKA was increasingly reported as a reliable, consistent and less complicated form of TKA fixation. However, over the past decade, new evidence has accumulated demonstrating greater success with this technology in several well designed studies as well as from registry studies. Most of this evidence involves the use of Porous Tantalum. However, increasing evidence that loosening of well done, well designed cemented TKA is rare along with some evidence that a certain percentage of cementless TKA patients fail to achieve stability remains concerning. In addition, no studies have justified improved longevity to the extent that the increased cost of cementless devices can be justified