Introduction and Objective. TKA have shown both excellent long-term survival rate and symptoms and knee function improvement. Despite the good results, the literature reports dissatisfaction rates around 20%. This rate of dissatisfaction could be due to the overstuff that mechanically aligned prostheses could produce during the range of motion. Either size discrepancy between bone resection and prosthetic component and constitutional mechanical tibiofemoral alignment (MTFA) alteration might increase soft tissue tension within the joint, inducing pain and functional limitation. Materials and Methods. Total knee arthroplasties performed between July 2019 and September 2020 were examined and then divided into two groups based on the presence (Group A) or absence (Group B) of patellofemoral overstuff, defined as a thickness difference of more than 2 mm between chosen component and bone resection performed, taking into account at least one of the following: femoral medial and lateral condyle, medial or lateral trochlea and patella. Based on pre and post-operative MTFA measurements, Group A was further divided into two subgroups whether the considered alignment was modified or not. Patients were assessed pre-operatively and at 6 months post-op using the Knee Society Score (KSS), Oxford Knee Score (OKS), Forgotten Joint Score (FJS), Visual Analogue Scale (VAS) and Range of Motion (ROM). Results. One hundred total knee arthroplasties were included in the present study, 69 in Group A and 31 in group B. Mean age and BMI of patients was respectively 71 and 29.2. The greatest percentage of Patellofemoral Overstuff was found at the distal lateral femoral condyle. OKS, KSS functional score, and FJS were statistically significant higher in patients without Patellofemoral Overstuff. Therefore, Group A patients with a non-modified MTFA demonstrated statistically significant better KSS, ROM and FJS. Conclusions. Patellofemoral Overstuff decrease post-operative clinical scores in patients treated with TKA. The conventional mechanically aligned positioning of TKA components might be the primary cause of prosthetic overstuffing leading to worsened clinical results. Level of evidence: III; Prospective Cohort Observational study;

High tibial osteotomy (HTO) is an effective surgical treatment for isolated medial compartment knee osteoarthritis; however, widespread adoption is limited due to difficulty in achieving the planned correction, and patient dissatisfaction due to soft tissue irritation. A new HTO system – Tailored Osteotomy Knee Alignment (TOKA®, 3D Metal Printing Ltd, Bath, UK) could potentially address these barriers having a custom titanium plate and titanium surgical guides featuring a unique mechanism for precise osteotomy opening as well as saw cutting and drilling guides. The aim of this study was to assess the accuracy of this novel HTO system using cadaveric specimens; a preclinical testing stage ahead of first-in-human surgery according to the ‘IDEAL-D’ framework for device innovation. Local ethics committee approval was obtained. The novel opening wedge HTO procedure was performed on eight cadaver leg specimens. Whole lower limb CT scans pre- and post-operatively provided geometrical assessment quantifying the discrepancy between pre-planned and post-operative measurements for key variables: the gap opening angle and the patient specific surgical instrumentation positioning and rotation - assessed using the implanted plate. The average discrepancy between the pre-operative plan and the post-operative osteotomy correction angle was: 0.0 ± 0.2°. The R2 value for the regression correlation was 0.95. The average error in implant positioning was −0.4 ± 4.3 mm, −2.6 ± 3.4 mm and 3.1 ± 1.7° vertically, horizontally, and rotationally respectively. This novel HTO surgery has greater accuracy and smaller variability in correction angle achieved compared to that reported for conventional or other patient specific methods with published data available. This system could potentially improve the accuracy and reliability of osteotomy correction angles achieved surgically

Mechanical alignment (MA) in total knee arthroplasty (TKA), although considered the gold standard, reportedly has up to 25% of patients expressing post-operative dissatisfaction. Biomechanical outcomes following kinematic alignment (KA) in TKA, developed to restore native joint alignment, remain unclear. Without a clear consensus for the optimal alignment strategy during TKA, the purpose of this study was to conduct a paired biomechanical comparison of MA and KA in TKA by experimentally quantifying joint laxity and medial collateral ligament (MCL) strain. 14 bilateral native fresh-frozen cadaveric lower limbs underwent medially-stabilised TKA (GMK Sphere, Medacta, Switzerland) using computed CT-based subject-specific guides, with KA and MA performed on left and right legs, respectively. Each specimen was subjected to sensor-controlled mediolateral laxity tests. A handheld force sensor (Mark-10, USA) was used to generate an abduction-adduction moment of 10Nm at the knee at fixed flexion angles (0°, 30°, 60°, 90°). A digital image correlation system was used to compute the strain on the superficial medial collateral ligament. A six-camera optical motion capture system (Vicon MX+, UK) was used to acquire kinematics using a pre-defined CT-based anatomical coordinate system. A linear mixed model and Tukey's posthoc test were performed to compare native, KA and MA conditions (p<0.05). Unlike MA, medial joint laxity in KA was similar to the native condition; however, no significant difference was found at any flexion angle (p>0.08). Likewise, KA was comparable with the native condition for lateral joint laxity, except at 30°, and no statistical difference was observed. Although joint laxity in MA seemed lower than the native condition, this difference was significant only for 30° flexion (p=0.01). Both KA and MA exhibited smaller MCL strain at 0° and 30°; however, all conditions were similar at 60° and 90°. Medial and lateral joint laxity seemed to have been restored better following KA than MA; however, KA did not outperform MA in MCL strain, especially after mid-flexion. Although this study provides only preliminary indications regarding the optimal alignment strategy to restore native kinematics following TKA, further research in postoperative joint biomechanics for load bearing conditions is warranted

Introduction and Objective. Total shoulder replacement is a common elective procedure offered to patients with end stage arthritis. While most patients experience significant pain relief and improved function within months of surgery, some remain unsatisfied because of residual pain or dissatisfaction with their functional status. Among these patients, when laboratory workup eliminates infection as a possibility, corticosteroid injection (CSI) into the joint space, or on the periprosthetic anatomic structures, is a common procedure used for symptom management. However, the efficacy and safety of this procedure has not been previously reported in shoulder literature. Materials and Methods. A retrospective chart review identified primary TSA patients who subsequently received a CSI into a replaced shoulder from 2011 – 2018 by multiple surgeons. Patients receiving an injection underwent clinical exam, laboratory analysis to rule out infection, and radiographic evaluation prior to CSI. Demographic variables were recorded, and a patient satisfaction survey assessed the efficacy of the injection. Results. Of the 43 responders, 48.8% remembered the injection. The average time from index arthroplasty to injection was median 16.8 months. Overall, 61.9% reported decreased pain, 28.6% reported increased motion, and 28.6% reported long term decreased swelling. Improvement lasted greater than one month for 42.9% of patients, and overall 52.4% reported improvement (slight to great) in the shoulder following CSI. No patient developed a periprosthetic joint infection (PJI) within 2 years of injection. Conclusions. This study suggests that certain patients following TSA may benefit from a CSI. However, this should only be performed once clinical, radiographic, and laboratory examination has ruled out conditions unlikely to improve long term from a CSI. Given these findings, further study in a large, prospective trial is warranted to fully evaluate the benefits of CSI following TSA

Abstract. Background. Accurate analysis of the patellar resurfacing is essential to better understand the etiology of patella-femoral problems and dissatisfaction following total knee arthroplasty (TKA). In the current published literature patellar resurfacing is analysed using 2D radiographs. With use of radiographs there is potential for error due to differences in limb positioning, projection, anatomic variability and difficulties in appreciating the cement-bone interface. So, we have developed a CT Scan based 3D modelled technique for accurate evaluation of patellar resurfacing. Methods. This technique for analyses of patellar resurfacing is based on the pre-operative and pos-operative CT Scan data of the patients who underwent TKA with patellar resurfacing. In the first step, accurately landmarked 3D models of pre-op patellae were created from pre-operative CT Scan data in ScanIP software. This model was imported in Geomagic design software and computational model of post-op patella was created. This was further analysed to determine the inclination of the patellar resection plane, patellar button positioning and articular volumetric restoration of the patella. Reliability and reproducibility of the technique was tested by comparing 3 sets of 10 measurements done by 2 independent investigators on 30 computational models of patellae derived from the data of randomly chosen 30 TKA patients. Results. The developed technique for analyses of patellar resurfacing is reliable and reproducible. The intraclass correlation co-efficient was >0.90 for the 10 measurements performed by two investigators. Conclusions. This technique can be used by surgeons and engineers for accurate analysis of the patellar resurfacing especially in patients with persistent patello-femoral problems after TKA. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Poor soft tissue balance in total knee arthroplasty (TKA) is one of the most primary causes of dissatisfaction and reduced joint longevity, which are associated with postoperative instability and early implant failure. 1. Therefore, surgical techniques, including mechanical instruments and 3-D guided navigation systems, in TKA aim to achieve optimum soft tissue balancing in the knee to improve postoperative outcome. 2. Patella-in-Place balancing (PIPB) is a novel technique which aims to restore native collateral ligament behaviour by preserving the original state without any release. Moreover, reduction of the joint laxity compensates for the loss of the visco-elastic properties of the cartilage and meniscus. Following its clinical success, we aimed to evaluate the impact of the PIPB technique on collateral ligament strain and laxity behaviour, with the hypothesis that PIPB would restore strains in the collateral ligaments. 3. . Eight fresh-frozen cadaveric legs were obtained (KU Leuven, Belgium, H019 2015-11-04) and CT images were acquired while rigid marker frames were affixed into the femur, and tibia for testing. After carefully removing the soft tissues around the knee joint, while preserving the joint capsule, ligaments, and tendons, digital extensometers (MTS, Minnesota, USA) were attached along the length of the superficial medial collateral ligament (MCL) and lateral collateral ligament (LCL). A handheld digital dynamometer (Mark-10, Copiague, USA) was used to apply an abduction or adduction moment of 10 Nm at fixed knee flexion angles of 0°, 30°, 60° and 90°. A motion capture system (Vicon Motion Systems, UK) was used to record the trajectories of the rigid marker frames while synchronized strain data was collected for MCL/LCL. All motion protocols were applied following TKA was performed using PIPB with a cruciate retaining implant (Stryker Triathlon, MI, USA). Furthermore, tibiofemoral kinematics were calculated. 4. and combined with the strain data. Postoperative tibial varus/valgus stresses and collateral ligament strains were compared to the native condition using the Wilcoxon Signed-Rank Test (p<0.05). Postoperative tibial valgus laxity was lower than the native condition for all flexion angles. Moreover, tibial valgus of TKA was significantly different than the native condition, except for 0° (p=0.32). Although, tibial varus laxity of TKA was lower than the native at all angles, significant difference was only found at 0° (p=0.03) and 90° (p=0.02). No significant differences were observed in postoperative collateral ligament strains, as compared to the native condition, for all flexion angles, except for MCL strain at 30° (p=0.02) and 60° (p=0.01). Results from this experimental study supported our hypotheses, barring MCL strain in mid-flexion, which might be associated with the implant design. Restored collateral ligament strains with reduced joint laxity, demonstrated by the PIPB technique in TKA in vitro, could potentially restore natural joint kinematics, thereby improving patient outcomes. In conclusion, to further prove the success of PIPB, further biomechanical studies are required to evaluate the success rate of PIPB technique in different implant designs

Conventional TKA surgery attempts to restore patients to a neutral alignment, and devices are designed with this in mind. Neutral alignment may not be natural for many patients, and may cause dissatisfaction. To solve this, kinematical alignment (KA) attempts to restore the native pre-arthritic joint-line of the knee, with the goal of improving knee kinematics and therefore patient's function and satisfaction. Proper prosthetic trochlea alignment is important to prevent patella complications such as instability or loosening. However, available TKA components have been designed for mechanical implantation, and concerns remain relating the orientation of the prosthetic trochlea when implants are kinematically positioned. The goal of this study is to investigate how a currently available femoral component restores the native trochlear geometry of healthy knees when virtually placed in kinematic alignment. The healthy knee OAI (Osteoarthritis Initiative) MRI dataset was used. 36 MRI scans of healthy knees were segmented to produce models of the bone and cartilage surfaces of the distal femur. A set of commercially available femoral components was laser scanned. Custom 3D planning software aligned these components with the anatomical models: distal and posterior condyle surfaces of implants were coincident with distal and posterior condyle surfaces of the cartilage; the anterior flange of the implant sat on the anterior cortex; the largest implant that fitted with minimal overhang was used, performing ‘virtual surgery’ on healthy subjects. Software developed in-house fitted circles to the deepest points in the trochlear grooves of the implant and the cartilage. The centre of the cartilage trochlear circle was found and planes, rotated from horizontal (0%, approximately cutting through the proximal trochlea) through to vertical (100%, cutting through the distal trochlea) rotated around this, with the axis of rotation parallel to the flexion facet axis. These planes cut through the trochlea allowing comparison of cartilage and implant surfaces at 1 degree increments. Trochlear groove geometry was quantified with (1) groove radial distance from centre of rotation cylinder (2) medial facet radial distance (3) lateral facet radial distance and (4) sulcus angle, along the length of the trochlea. Data were normalised to the mean trochlear radius. The orientation of the groove was measured in the coronal and axial plane relative to the flexion facet axis. Inter- and intra-observer reliability was measured. In the coronal plane, the implant trochlear groove was oriented a mean of 8.7° more valgus (p<0.001) than the normal trochlea. The lateral facet was understuffed most at the proximal groove between 0–60% by a mean of 5.3 mm (p<0.001). The medial facet was understuffed by a mean of 4.4 mm between 0–60% (p<0.001). Despite attempts to design femoral components with a more anatomical trochlea, there is significant understuffing of the trochlea, which could lead to reduced extensor moment of the quadriceps and contribute to patient dissatisfaction

Background. There is a 20% dissatisfaction rate with knee replacements. Calls for tools that can pre-operatively identify patients at risk of being dissatisfied postoperatively have been widespread. However, it is unclear what sort of information patients would want from such a tool, how it would affect their decision making process, and at what part of the pathway such a tool should be used. Methods. Using focus groups involving 12 participants and in-depth interviews with 10 participants, we examined the effect outcome prediction has by providing fictitious predictions to patients at different stages of treatment. A qualitative analysis of themes, based on a constant comparative method, is used to analyse the data. This study was approved by the Dyfed Powys Research Ethics Committee (13/WA/0140). Results. Our results demonstrate several interesting findings. Firstly, patients who have received information from friends and family are unwilling to adjust their expectation of outcome down (i.e. to a worse outcome), but highly willing to adjust it up (to a better outcome). This is an example of the optimism bias, and suggests the effect on expectation of any poor outcome prediction would be blunted. Secondly, patients generally wanted a “bottom line” outcome, rather than lots of detail. Thirdly, patients who were earlier in their treatment for osteoarthritis were more likely to find the information useful, and for it to affect their decision, than patients later in their pathway. Conclusion. An outcome prediction tool would have most effect targeted towards people at the start of their treatment pathway, with a “bottom line” prediction of outcome. However, any effect on expectation and decision making of a poor outcome prediction is likely to be blunted by the optimism bias. Level of Evidence. 4

Background. Knee replacement surgery is currently facing three dilemmas: a high dissatisfaction rate; increasing demand with financial constraints; and variation in utilisation. A patient centred approach, usually achieved through shared decision-making, has the potential to help address these dilemmas. However, such an approach requires an understanding of the factors involved in patient decision-making. This is the first study examining decision-making in knee replacements that includes patients at different stages of decision-making – this is critical when considering decision-making as a process. We base our findings in a theoretical model, proposed by Elwyn et al, that highlights the distinction between deliberation and decision-making, and propose modifications to this model specific to knee replacement decision-making. Methods. This study used two focus groups of six patients each and in-depth interviews with 10 patients to examine the factors that affect patient decision-making and their interaction at different points in the decision-making process. A qualitative analysis of themes, based on a constant comparative method, is used to analyse the data. This study was approved by the Dyfed Powys Research Ethics Committee (13/WA/0140). Results. We describe 10 themes that affect patient deliberation over the decision: decision-making style; coping strategies; expectation of outcome; decision-making stress; personal situation; preferred model of care; trust in doctor; sources of information; mental state; and loss of control. We add to Elwyn's model by demonstrating the boundary between deliberation and decision-making is the decision-making threshold. Conclusion. This study provides increased detail on a theoretical model that can be used to describe decision-making, and an understanding of the factors that affect decision-making for patients considering knee replacement. Such an understanding will aid patient centred care, and has particular relevance in developing interventions aimed at delivering information. This is likely to affect the satisfaction rate, demand, and utilisation of knee replacements. Level of evidence. 4

Since the publication by Berger in 1993, many total knee replacements (TKR) have been measured using his technique to assess component rotation. Whereas the femoral landmarks have been showed to be accurate and precise, the use of the tibial tuberosity to ascertain the true tibial orientation is more controversial. The goal of this study was to identify a new anatomical landmark to measure tibial component rotation. 211 CTs performed after TKR were reviewed. The authors noticed that the lateral cortex of the tibia below the tibial plateau component was flat over a depth of approximately 10mm. A protocol to measure tibial rotation in relation to this landmark was developed: the slice below the tibial plateau was identified; a primary line was drawn over the straight lateral cortex of the tibia; a perpendicular to this line defined the reference axis (A); the posterior tibial component axis was drawn (B); the angle between A and B was measured with internal rotation being negative and external positive. Two independent observers measured 31 CTs twice each and Intraclass Correlation Coefficients (ICC) were calculated for intra- and inter-observer error. The 211CTs were measured according to Berger's and this protocol. Intra-observer ICCs were 0.812 for Observer1 and 0.806 for Observer2. The inter-observer ICCs were 0.699 for Reading1 and 0.752 for Reading2. The Berger protocol mean tibial rotation was 9.7°±5.5° (−29.0° to 5.2°) and for the new landmark 0°±5.4° (−18.6° to 14°). This new tibial landmark appeared easy to identify and intra- and inter-observer errors were acceptable. The fact that the mean tibial rotation was 0° makes this landmark attractive. A consistent easily identified landmark for tibial rotation may allow for improvement in component rotation and the diagnosis of dissatisfaction after TKR. Further studies are under way to confirm the relevance of this landmark

Background. Recent years have witnessed a paradigm shift in the assessment of outcome in spine surgery, with patient-centred questionnaires replacing traditional surgeon-based assessments. The assessment of “complications” — loosely defined as new/unexpected problems arising as a result of surgery — has not enjoyed this same enlightened approach. Methods. Patients with lumbar degenerative disorders operated with the goal of pain relief, completed a questionnaire 1 year post-operatively enquiring about complications arising as a consequence of their operation. They rated the bothersomeness of any such complications on a 5-point adjectival scale. Global outcome of surgery and satisfaction were rated on 5-point Likert scales. Results. Of 2946 (92% compliance) patients completing the questionnaire, 861 (29%) reported complications, most commonly sensory disturbances (37% of those with complications) or ongoing pain (22%), followed by motor problems (9%), pain plus sensory disturbances (8%), and problems with wound healing (6%). The corresponding “bothersomeness” ratings for these were: 1% not at all, 23% slightly, 26% moderately, 31% very, and 19% extremely bothersome. Bothersomeness was significantly correlated with global outcome (Rho=0.51, p<0.0001) and satisfaction (Rho=0.43, p<0.0001). A good global outcome was reported by 80% of patients with no complications and only 58% of those with complications; satisfaction was 88% and 72%, respectively. Conclusion. Most complications reported by the patient are perceived to be at least moderately bothersome and are hence not inconsequential. Complications and their severity should be assessed from both the patient's and the surgeon's perspective — not least to better understand the reasons for poor outcome and dissatisfaction with treatment. Conflicts of Interest. None. Source of Funding. None

Cubitus varus following paediatric supra-condylar humeral fracture represents a complex three-dimensional malunion. This affects cosmesis, function and subsequent distal humeral fracture risk. Operative correction is however difficult with high complication rates. We present the 40-year Yorkhill experience of managing this deformity. From a total of 3220 supracondylar humeral fractures, 40 cases of post-traumatic cubitus varus were identified. There were ten undisplaced fractures, treated in cast, and thirty displaced fractures. Five were treated in cast, thirteen manipulated (MUA), four MUA+k-wires, seven ORIF (six k-wire, one steinman pin) and one in skeletal-traction. Sixteen malunions were treated operatively. The mean pre-operative varus was 19°. All had cosmetic concerns, three mild pain, one paraesthesia/weakness and three reduced movement (ROM). The operative indication was cosmetic in fifteen and functional in one (concern about instability). Twelve patients had lateral closing-wedge osteotomies; three complex/3D osteotomies (dome, unspecified rotational, antero-lateral wedge) and two had attempted 8-plate guided-growth correction. Complications occurred in eight patients (50 %): Fixation was lost in three (two staples, one k-wiring), incomplete correction in six (both 8-plates, both staples, two standard plates) and one early wound infection requiring metalwork removal resulting in deformity recurrence. One patient underwent revision lateral wedge osteotomy with full deformity correction but marked ROM restriction (20–100°) secondary to loose bodies. Those without complications were satisfied (50 %). All patients with residual deformity were unsatisfied. 1 patient with keloid scarring was unsatisfied despite deformity correction. Varus malunion is uncommon (1 %) but needs to be guarded against. It tended to occur in displaced fractures treated with MUA and cast alone. We therefore recommend additional pin fixation in all displaced fractures. Deformity correction should only be attempted in those with significant symptomatic deformity due to the high complication/dissatisfaction rates. Staple osteotomy fixation and 8-plate guided growth correction are not recommended

Objectives

This study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group.