Abstract. Background. Multi-ligament knee injury is a rare but severe injury. Treatment strategies are challenging for most orthopedic surgeons & optimal treatment remains controversial. The purpose of our study was to assess clinico-radiological and functional outcomes after surgical management of multi-ligament knee injuries & to determine factors that could predict outcome of surgery. Materials And Method. It is a prospective observational study of 30 consecutive patients of Multi-ligament knee injury conducted between 2018–2020. All patients were treated surgically with single-stage reconstruction of all injured ligaments and followed standardized postoperative rehabilitation protocol. All patients were evaluated for Clinical (VAS score, laxity stress test, muscle-strength, range of motion), Radiological (stress radiographs) & Functional (Lysholm score) outcomes three times-preoperatively, post-operative 3 & 12 months. Results. At final follow up mean VAS score was 0.86±0.77. The anteroposterior & valgus-varus stress test showed ligament laxity >10mm (GradeD) in 93.3% patient which improved to <3mm (normal, GradeA) in 90% patients. Most patients (83.3%) had preoperative-range <100° and muscle strength of MRC Grade-3 which improved to >120° and muscle strength of MRC grade-5 at final followup. Lysholm score was poor (<64) in all patients preoperatively and improved to good (85–94) in 73.3%, excellent (>95) in 20% & fair (65–84) in 6.6% patients. The stress radiographs showed stable results for anterior/posterior & varus/valgus stress. All patients returned to their previous work. Factors that could predict outcomes of surgery are age, timing of surgery, type of surgery & associated injury. Conclusion. Early complete single stage reconstruction can achieve good functional results with overall restoration of sports & working capacity. Positive predictive factors for good outcome are younger age, early surgery & appropriate rehabilitation

Clinical laxity tests are frequently used for assessing knee ligament injuries and for soft tissue balancing in total knee arthroplasty (TKA). Current routine methods are highly subjective with respect to examination technique, magnitude of clinician-applied load and assessment of joint displacement. Alignment measurements generated by computer-assisted technology have led to the development of quantitative TKA soft tissue balancing algorithms. However to make the algorithms applicable in practice requires the standardisation of several parameters: knee flexion angle should be maintained to minimise the potential positional variation in ligament restraining properties; hand positioning of the examining clinician should correspond to a measured lever arm, defined as the perpendicular distance of the applied force from the rotational knee centre; accurate measurement of force applied is required to calculate the moment applied to the knee joint; resultant displacement of the knee should be quantified. The primary aim of this study was to determine whether different clinicians could reliably assess coronal knee laxity with a standardised protocol that controlled these variables. Furthermore, a secondary question was to examine if the experience of the clinician makes a difference. We hypothesised that standardisation would result in a narrow range of laxity measurements obtained by different clinicians. Six consultant orthopaedic surgeons, six orthopaedic trainees and six physiotherapists were instructed to assess the coronal laxity of the right knee of a healthy volunteer. Points were marked over the femoral epicondyles and the malleoli to indicate hand positioning and give a constant moment arm. The non-invasive adaptation of a commercially available image-free navigation system enabled real-time measurement of coronal and sagittal mechanical femorotibial (MFT) angles. This has been previously validated to an accuracy of ±1°. Collateral knee laxity was defined as the amount of angular displacement during a stress manoeuvre. Participants were instructed to maintain the knee joint in 2° of flexion whilst performing a varus-valgus stress test using what they perceived as an acceptable load. They were blinded to the coronal MFT angle measurements. A hand-held force application device (FAD) was then employed to allow the clinicians to apply a moment of 18Nm. This level was based on previous work to determine a suitable subject tolerance limit. They were instructed to repeat the test using the device in the palm of their right hand and to apply the force until the visual display and an auditory alarm indicated that the target had been reached. The FAD was then removed and participants were asked to repeat the clinical varus-valgus stress test, but to try and apply the same amount of force as they had been doing with the device. Maximum MFT angular deviation was automatically recorded for each stress test and the maximum moment applied was recorded for each of the tests using the FAD. Means and standard deviations (SD) were used to compare different clinicians under the same conditions. Paired t-tests were used to measure the change in practice of groups of clinicians before, during and after use of the FAD for both varus and valgus stress tests. All three groups of clinicians initially produced measurements of valgus laxity with consistent mean values (1.5° for physiotherapists, 1.8° for consultants and 1.6° for trainees) and standard deviations (<1°). For varus, mean values were consistent (5.9° for physiotherapists, 5.0° for consultants and 5.4° for trainees) but standard deviations were larger (0.9° to 1.6°). When using the FAD, the standard deviations remained low for all groups for both varus and valgus laxity. Introducing the FAD overall produced a significantly greater angulation in valgus (2.4° compared to 1.6°, p<0.001) but not varus (p = 0.67) when compared to the initial examination. In attempting to reach the target moment of 18Nm, the mean ‘overshoot’ was 0.9Nm for both varus and valgus tests. Standard deviations for varus laxity were lower for all groups following use of the FAD. The consultants' performance remained consistent and valgus assessment remained consistent for all groups. The only statistically significant change in practice for a group before and after use of the FAD was for the trainees testing valgus, who may have been trained to push harder (p = 0.01). Standardising the applied moment indicated that usually a lower force is applied during valgus stress testing than varus. This was re-enforced by clinicians, one third of whom commented that they felt they had to push harder for valgus than varus, despite the FAD target being the same. We have successfully standardised the manual technique of coronal knee laxity assessment by controlling the subjective variables. The results support the hypothesis of producing a narrow range of laxity measurements but with valgus laxity appearing more consistent than varus. The incorporation of a FAD into assessment of coronal knee laxity did not affect the clinicians' ability to produce reliable and repeatable measurements, despite removing the manual perception of laxity. The FAD also provided additional information about the actual moment applied. This information may have a role in improving the balancing techniques of TKA and the management of collateral ligament injuries with regard initial diagnosis and grading as well as rehabilitation. Finally, the results suggest that following use of the FAD, more experienced clinicians returned to applying their usual manual force, while trainees appeared to use this augmented feedback to adapt their technique. Therefore this technique could be a way to harness the experience of senior clinicians and use it to enhance the perceptive skills of more junior trainees who do not have the benefit of this knowledge

Purpose. Operative treatment of Lisfranc joint injuries typically includes reduction and stabilization of the medial and middle columns of the midfoot. Mobility of the lateral column is preserved where possible, such that indications for lateral column stabilization rely upon the surgeons assessment of instability. In this case series, the indication for lateral column stabilization was defined by the results of an intra-operative stress test. The purpose of this study was to determine whether an intra-operative fluoroscopic stress test of the lateral column was sufficient to determine the need for internal fixation of the lateral column in Lisfranc joint injuries. Method. 35 adult patients with Lisfranc injuries operated in our centre by a single surgeon from 2005–2009 were reviewed. All patients had unstable midfoot fracture dislocations, treated by reduction and internal fixation including an intra-operative stress examination to determine the need for lateral column fixation. Patients were contacted for clinical and radiographic review at a mean of 31 months post injury. Functional outcome was assessed using general and joint-specific outcome tools (AOFAS midfoot score and LEM). Radiographic review included analysis of joint displacement and arthritic changes in preoperative, postoperative, and most recent radiographs. Results. Pre-operative imaging demonstrated displacement of the lateral column in 25 / 35 patients. Nineteen of these 25 had a stable reduction of the lateral column following medial and middle column fixation, based upon an intra-operative stress examination. Only 6 patients had persistent instability; these were treated with lateral column stabilization. Reduction of the lateral column was maintained at final follow up in 100 percent of 35 patients. Lateral midfoot pain was present in 5/6 patients requiring lateral fixation, compared to 1/(19) patient who did not require lateral fixation. AOFAS midfoot scores (mean) were 80 15. in patients with no evidence of lateral column instability, 79 15. in patients with preoperative displacement but a negative stress examination, and 77 18 in patients requiring lateral fixation (p>0.05). Post-traumatic arthrosis was present in 3/10 patients with no evidence of lateral column instability, 4/19 patients with preoperative displacement but a negative stress examination, and 4/6 in patients requiring lateral fixation (p>0.05). Conclusion. The decision to stabilize the lateral column during surgery on Lisfranc injuries was aided by an intra-operative fluoroscopic stress examination. Based upon the stress examination, 19 / 25 patients who had a displaced lateral column at the time of presentation avoided lateral fixation. None of these 19 patients treated without lateral fixation lost reduction in the follow up period. A fluoroscopic intra operative stress test safely reduced the need for lateral column fixation in displaced Lisfranc joint injuries

Postero-lateral rotator instability (PLRI) is the most common pattern of recurrent elbow instability. Unfortunately, current imaging to aid PLRI diagnosis is limited. We have developed an ultrasound (US) technique to measure ulnohumeral joint gap with and without stress of the lateral ulnocollateral ligament. We sought to define lateral ulnohumeral joint gap measurements in the resting and stressed state to provide insight into how US may aid diagnosis of PLRI. Sixteen elbows were evaluated in eight healthy volunteers. Lateral ulnohumeral gap was measured on US in the resting position and with posterolateral drawer stress test maneuver applied. Joint laxity was calculated as the difference between stress and rest conditions. Measurements were performed by two independent readers with comparison performed between stress and rest positions. A highly significant difference in ulnohumeral gap was seen between stress and rest conditions (Reader 1: p < 0 .0001 and Reader 2: p=0.0002) with median values of 2.93 mm and 2.50 mm at rest and 3.92 mm and 3.40 mm at stress for Reader 1 and 2 respectively. Median joint laxity was 1.02 mm and 0.74 mm respectively for each reader. Correlation and agreement between readers was good. This study provides key new insight into use of US for diagnosis as PLRI as it defines normal ulnohumeral distances and demonstrates widening when applying the posterolateral drawer stress maneuver. Further evaluation of this technique is required in patients with PLRI

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment/loosening which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Care should be given to assessing collateral ligament integrity. This can be done during physical examination by radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate retaining knees, anteroposterior instability must be assessed. For instability, most revisions will require a posterior cruciate substituting design or a constrained condylar design that is unlinked. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Infection should be ruled out by aspiration and off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result

Anatomical referencing, component positioning, limb alignments and correction of mechanical axes are essential first steps in successful computer assisted navigation. However, apart from basic gap balancing and quantification of ranges of motion, routine navigation technique usually fails to use the full potential of the registered information. Enhanced dynamic assessment using an upgraded navigation system (Brainlab V. 2.2) is now capable of producing enhanced ‘range of motion’ analysis, ‘tracking curves’ and ‘contact point observations’. ‘Range of motion analysis’ was performed simultaneously for both tibio-femoral and patella-femoral joints. Other dynamic information including epicondylar axis motion, valgus and varus alignments, antero-posterior tibio-femoral shifts, as well as flexion and extension gaps were simultaneously stored as a series of ‘tracking curves’ throughout a full range of motion. Simultaneous tracking values for both tibiofemoral and patellofemoral motion was also obtained after performing registration of the prosthetic trochlea. However, there seems to be little point in carrying out such observations without fully assessing joint stability by applying controlled force to the prosthetic joint. Therefore, in order to fully assess ‘potential envelopes of motion’, observations have been made using a set of standardised simple dynamic tests during insertion and after final positioning of trial components. Also, such tests have been carried out before and after any necessary ligament balancing. Firstly, the lower leg was placed in neutral alignment and the knee put through a flexion-extension cycle. Secondly the test was repeated but with the lower leg being placed into varus and internal rotation. The third test was performed with the lower leg in valgus and external rotation. Force applied was up to the point where resistance occurred without any gross elastic deformation of capsule or ligament in a manner typical of any surgeon assessing the stability of the construct. Also a passive technique of using gravity to ‘Drop-Test’ the limb into flexion and extension gave useful information regarding potential problems such as blocks to extension, over-stuffing of the extensor mechanism and tightness of the flexion gap. All the definitive tests were performed after temporary medial capsular closure. Ten total knee arthroplasties have been studied using this technique with particular reference to the patterns of instability found before, during and after adjustments to component positioning and ligament balancing. Marked intra-operative variation in the stability characteristics of the trial implanted joints has been quantified before correction. These corrections have been analysed in terms of change in translations, rotations and contact points induced by any such adjustments to components and ligament. Certain major typical patterns of instability have begun to be identified including excessive rotational and translational movements. Instability to valgus and external rotational stress was found in two cases and to varus and internal rotational stress in one case before correction. In particular, surprising amounts of edge loading in mid-flexion under stress testing has been identified and corrective measures carried out. Reductions in paradoxical tibio-femoral antero-posterior motion were also observed. Global instability and conversely tightness were also observed in early stages of surgery. Adjustments to component sizes, rotations, tibial slope angles and insert thickness were found to be necessary to optimise range of motion and stability characterisitics on an almost case-by-case basis. Two cases were identified where use of more congruent or stabilised components was necessary. Observation of quite marked loss of contact between tibia and femur was seen on the lateral side of the knee in deep flexion in several cases. Patellar tracking was also being observed during such dynamic tests and in two cases staged partial lateral retinacular releases were carried out to centre patellar tracking on the prosthetic trochlea. Although numbers in this case series are small, it has been possible to begin to observe, classify and quantify patterns of instability intra-operatively using simple stress tests. Such enhanced intra-operative information may in future make it possible to create algorithms for logical and precise adjustments to ligaments and components in order to optimise range of motion, contact areas and stability in TKR

Background. The Bundled Payments for Care Improvement (BPCI) was developed by the US Center for Medicare and Medicaid (CMS) to evaluate a payment and service delivery model to reduce cost but preserve quality. 90 day postoperative expenditures are reconciled against a target price, allowing for a monetary bonus to the provider if savings were achieved. The surgeon is placed in a position to optimize the patients preoperatively to minimize expensive postoperative cardiovascular readmissions in a high risk population. Traditionally, surgeons request that primary care providers medically clear the patient for surgery with or without additional cardiology consultation, without dictating specific testing. Typical screening includes an EKG, occasionally an echocardiogram and nuclear stress test, and rarely a cardiac catheterization. Our participation in the BPCI program for total hip and knee replacement surgeries since 1/1/15 has demonstrated a significant number of patients having readmissions for cardiac events. Objective. To determine the medical effectiveness and cost savings of instituting a new innovative cardiac screening program (Preventive Cardio-Orthopaedics) for total hip and knee replacement patients in the BPCI program and to compare result to those managed in the more traditional fashion. Methods. The new screening program was instituted on 11/1/17 directed by an advanced cardiac imaging cardiologist (EH). Testing included an electrocardiogram, echocardiogram, carotid and abdominal ultrasound, and coronary computed tomography angiography (CCTA). If needed, a 3 day cardiac rhythm monitor was also performed. Four of the ten physicians in our group performing hip and knee replacement surgeries participated. Charts of readmitted patients were reviewed to determine past medical history, method of cardiac clearance, length and cost of readmission. Results. 1,361 patients had total hip or knee replacement in the BPCI program between 1/1/15 and 1/28/18 and all had complete 90 day postoperative readmission data supplied by the CMS, with 25 of these patients evaluated through the Preventive Cardio- Orthopaedics program. 12 (0.90%) screened via the traditional cardiac program had a cardiac event readmission. The average readmission hospital stay was 3.67 days at a total cost of $69,378. 7 of 12 had a preoperative clearance by a cardiologist. In 9 of the 12 patients, the only preoperative cardiac screening tool performed was an electrocardiogram. None of these 25 patients evaluated through the new program has been readmitted. 84 more patients have been evaluated in this program since 1/28/18, but 90 day readmission data is still incomplete. Preliminary data suggests that the highest risk in these patients is not severe coronary artery disease, but atrial fibrillation, hypertension with left ventricular hypertrophy, and cardiac plaques with ulceration. Conclusions. Risk sharing programs have forced joint replacement surgeons to take a more active role in optimizing their patients medically; otherwise they will be penalized with a decreased reimbursement. Traditionally, we have abdicated this responsibility to primary care and cardiology physicians but have noted a high readmission risk with a cardiac event. In response, we have begun using a unique cardiac screening model. Our preliminary experience predicts fewer cardiac readmissions thereby improving care, and at a lower cost

Introduction. Modified gap technique has been reported to be beneficial for the intraoperative soft tissue balancing in posterior-stabilized (PS) -TKA. We have found intraoperative ligament balance changed depending on joint distraction force, which might be controlled according to surgeons' fells. We have developed a new surgical concept named as “medial preserving gap technique (MPGT)” to preserve medial knee stability and provide quantitative surgical technique according to soft tissue balance measurement using a tensor device. The purpose of this study was to compare 3-years postoperative knee stability after PS-TKA in varus type osteoarthritic (OA) knees between MPGT and measured resection technique (MRT). Material & Method. The subjects were 94 patients underwent primary unilateral PS-TKA for varus type OA knees. The surgical technique was MPGT in 47 patients and MRT in 47 patients. An originally developed off-set type tensor device was used to evaluate intraoperative soft tissue balance. In MPGT, medial release was limited until the spacer block corresponding to the bone thickness from proximal lateral tibial plateau could be easily inserted. Femoral component size and external rotation angle were adjusted depending on the differences of center gaps and varus angles between extension and flexion before posterior femoral condylar resection. The knee stabilities at extension and flexion were assessed by stress radiographies at 1 and 3 years after TKA; varus-valgus stress test at extension and stress epicondylar view at flexion. We measured medial and lateral joint openings (MJO, LJO) at both knee extension and flexion. MJOs and LJOs at 2 time periods were compared in each group using paired t-test. Each joint opening distance was compared between 2 groups using unpaired t-test. The significance level was set as P < 0.05. Results. The mean extension MJOs at 1 and 3 years after TKA were 2.4, 2.6 mm in MPGT and 3.2, 3.1 mm in MRT respectively. The mean extension LJOs were 3.5, 3.5 mm in MPGT and 4.6, 4.5 mm in MRT. The mean flexion MJOs were 0.95, 0.77 mm in MPGT and 1.5, 1.2 mm in MRT, and the mean flexion LJOs were 2.2, 2.1 mm in MPGT and 3.0, 2.7 mm in MRT. MJOs were significantly smaller than LJOs in each group at 2 time periods. MJOs at extension and flexion, and LJOs at extension were significantly smaller in MPGT than MRT at 2 time periods. Discussion. Medial knee stabilities had been reported to be essential for postoperative clinical results. We reported medial compartment gap was more stable during mid-to-deep knee flexion in MPGT than MRT. MPGT provided the more stable intraoperative soft tissue balance than MRT in PS-TKA. MPGT was useful to preserve the higher medial knee stability than the lateral as well as MRT, and beneficial to enhance postoperative knee stabilities as long as 3-years after PS-TKA in varus OA knees. MPGT would be an objective and safer gap technique to enhance clinical outcomes

Introduction. Both measured resection technique and gap balancing technique have been important surgical concepts in total knee arthroplasty (TKA). Modified gap technique has been reported to be beneficial for the intra-operative soft tissue balancing in posterior-stabilizing (PS) -TKA. On the other hand, we have found joint distraction force changed soft tissue balance measurement and medial knee instability would be more likely with aiming at perfect ligament balance at extension in modified gap technique. The medial knee stability after TKA was reported to essential for post-operative clinical result. We have developed a new surgical concept named as “medial preserving gap technique” for varus type osteoarthritic (OA) knees to preserve medial knee stability and provide quantitative surgical technique using tensor device. The purpose of this study was to compare post-operative knee stability between medial preserving gap technique (MPGT) and measured resection technique (MRT) in PS-TKA. Material & Method. The subjects were 140 patients underwent primary unilateral PS-TKA for varus type OA knees. The surgical technique was MPGT in 70 patients and MRT in 70 patients. There were no significant differences between two groups in the pre-operative clinical features including age, sex, ROM and deformity. Originally developed off-set type tensor device was used to evaluate both center gap and varus angle with 40 lbs. of joint distraction force. The extension gap preparation was identical in both group. In MPGT group, femoral component size and external rotation angle were adjusted depending on the differences of center gaps and varus angles between extension and flexion before posterior femoral condylar osteotomy. The knee stabilities at extension and flexion were assessed by stress radiographies; varus-valgus stress test with extension and stress epicondylar view with flexion, at one-month and one-year after TKA. We measured joint opening distance (mm) at medial and lateral compartment at both knee extension and flexion. Joint opening distances were compared between two groups using unpaired t-test, and the difference between medial and lateral compartment in each group was compared using paired t- test (p<0.05). Results. Joint opening distances at medial compartments with both extension and flexion were significantly smaller than lateral in both groups. There were no significant differences in join opening distance between two groups at medial compartment, but those at lateral were significantly smaller in MPGT than MRT with both knee extension and flexion. Discussion. In the present study, we found MPGT resulted in equal postoperative medial knee stability as in MRT, and superior to MRT as for the lateral knee stability. This finding would be the result of different femoral external rotation angle and femoral component size selection between two groups. We used the difference of varus angle and center gap between flexion and extension for the femoral component size selection and external rotation angle in MPGT. Quantitative surgical concept; MPGT, was found to be safer and feasible gap technique in PS-TKA to preserving medial knee stability and control lateral laxity in varus type OA knee. MPGT would be an advantageous gap technique to enhance clinical outcome

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening and settling of the implants which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Also, collateral ligament integrity may change following total knee replacement slightly after complete correction of a severe deformity that presents rarely as instability after several months. Care should be given to assessing collateral ligament integrity. This can be done during physical examination by manual or radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate ligament retaining knees, anteroposterior instability must be assessed. For instability, most revisions will require a posterior cruciate substituting design or a constrained unlinked condylar design. Occasionally, a posterior cruciate ligament preserving design can be used in situations where the bone-stock is well preserved and the posterior cruciate ligament shows excellent structural integrity. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. Revision can range from simple polyethylene insert exchange to a thicker dimension, isolated component revision or complete revision of both femoral and tibial devices. During revision surgery, laminar spreaders may be utilised to assess the flexion and extension spaces after the tibial platform is restored. If a symmetric flexion and extension space is achieved, then the collateral ligaments are intact. Depending on the remaining existing bone stock, a posterior stabilised or constrained condylar unlinked prosthesis may be used for implantation. In cases with considerable asymmetry or a large flexion/extension mismatch, a rotating hinge design should be utilised. Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Currently, stems should be placed cementless to permit easier future revision. Cementing the stems is only recommended if there is lack of intramedullary isthmic support or there is a hip prosthetic stem that prohibits a stem from engaging the isthmic cortex. However, it should be realised that later revision of the fully cemented revision implant may be quite difficult. Infection should be ruled out by aspiration off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability early. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result

Introduction. Knee instability, stiffness, and soft-tissue imbalance are causes of aseptic revision and patient dissatisfaction following total knee arthroplasty (TKA). Surgical techniques that ensure optimal ligament balance throughout the range of motion may help reduce TKA revision for instability and improve outcomes. We evaluated a novel tibial-cut first gap balancing technique where a computer-controlled tensioner is used to dynamically apply a varying degree of distraction force in real-time as the knee is taken through a range of motion. Femoral bone cuts can then be planned while visualizing the predicted knee implant laxity throughout the arc of flexion. Surgical Technique Description. After registering the mechanical axes and morphology of the tibia and femur using computer navigation, the tibial resection was performed and a robotic tensioning tool was inserted into the knee prior to cutting the femur. The tool was programmed to apply equal loads in the medial and lateral compartments of the knee, but to dynamically vary the distraction force in each compartment as the knee is flexed with a higher force being applied in extension and a progressively lower force applied though mid-flexion up to 90° of flexion. The tension and predictive femoral gaps between the tibial cut and the femoral component in real-time was determined based on the planned 3D position and size of the femoral implant and the acquired pre-resection gaps (figure 1). Femoral resections were then performed using a robotic cutting guide and the trial components were inserted. Methods. The technique was evaluated by three experienced knee arthroplasty surgeons on 4 cadaver knees (3 torso-to-toe specimens, Pre-operative deformity range: 4° varus − 6° valgus; Extension lag: 0° – 13°; BMI 23.4 – 32.6; Age 68 – 85yr). An applied targeted load of 80N in extension and 50N in flexion was used in each of the four knees. These force values were determined in a prior cadaver study aimed at determining what magnitude of applied load corresponded to an optimally rated knee tension and stability. The femoral component was planned in each of the four knees to have symmetric gaps at 0° and 90° of flexion. The overall balance of the knee was assessed clinically by each surgeon using a varus/valgus stress test with the trial components inserted. No soft-tissue releases were performed other than a standard medial release during initial exposure of the knee. The following scale was used to rate the final knee stability achieved: 1 – too loose; 2 – slightly loose; 3 – ideal; 4 slightly tight; 5 – too tight. Results. ‘Ideal' balance was achieved in three out of the four knees tested (table 1). In two of the four knees the final inserted thickness selected was 1mm thicker than the planned insert thickness. Conclusions. Our preliminary cadaver results suggest that it is possible to achieve a balanced knee by incorporating dynamic ligament tensioning and gap data throughout flexion into the femoral planning process using a robotic tensioning tool. For figures/tables, please contact authors directly.

The literature contains limited and contradictory information regarding the amount of physical effort and/or emotional stress needed to perform surgery. We therefore investigated cardiovascular response to psychophysical stress in orthopaedic surgeons while they were performing surgery. We monitored 29 male orthopaedic surgeons from four university centers while they performed total hip arthroplasties. Changes in their cardiovascular parameters were recorded by ambulatory monitoring methods. Exercise stress testing of each participant was used as a control state. We compared the cardiovascular response during surgery to energy requirements of everyday activities. Preoperative and postoperative testing showed lower values of cardiovascular parameters than during physically less difficult parts of the operation; physically more difficult phases of the operation additionally increased the values of parameters. We concluded performing total hip arthroplasty increases surgeons’ cardiovascular parameters because of psychologic stress and physical effort. Excitement of the cardiovascular system during total hip arthroplasty appears similar to the excitement during moderate-intensity daily activities, such as walking the dog, leisurely bicycling, or climbing stairs

We introduce a novel active tensioning system that can be used for dynamic gap-based implant planning as well as for assessment of final soft tissue balance during implant trialing. We report on the concept development and preliminary findings observed during early feasibility testing in cadavers with two prototype systems. System description. The active spacer (fig 1) consists of a motorized actuator unit with integrated force sensors, independently actuated medial and lateral upper arms, and a set of modular attachments for replicating the range of tibial baseplate and insert trial sizes. The spacer can be controlled in either force or position (gap) control and is integrated into the OMNIBotics. TM. Robotic-assisted TKA platform (OMNI, MA, USA). Cadaver Study. Two design iterations were evaluated on eleven cadaver specimens by seven orthopaedic surgeons in three separate cadaver labs. The active spacer was used in a tibial-first technique to apply loads and measure gaps prior to and after femoral resections. To determine the range of forces applied on the spacer during a varus/valgus assessment procedure, each surgeon performed a varus/valgus stress test and peak medial and lateral forces were measured. Surgeons also rated the feel of the stability of the knee at 50N and 80N of preload using the following scale: 1 – too loose; 2 – slightly loose; 3 – ideal; 4 slightly tight; 5 – too tight. Final balanced was assessed with the spacer and with manual trial components. Results. Overall the prototype system successfully met the functional requirements for applying controlled tension during ligament balancing, and user feedback on usability and feasibility for use in TKA was highly positive. Peak forces measured during blinded stability assessments were significantly imbalanced from medial to lateral and exhibited a wide range across users (range: 70N – 310N, table 1). Each surgeon rated 50N of tension as feeling “slightly loose” and 80N as feeling “ideal” in extension. “Ideal” soft tissue balance was achieved in the last three knees tested using the second design iteration, as rated by the surgeons with final trial components in place. Discussion. Our preliminary cadaver results have established the initial feasibility of the active spacer concept for applying tension during ligament balancing and implant planning. Our initial results also suggest that performing a varus/valgus assessment without force readings can lead to imbalanced mediolateral load application. This may be due to factors such as hand dominance and pulling in varus versus pushing in valgus. There was also considerable inter-surgeon variability in the peak forces applied. An advantage of computer-controlled ligament tensioning and force sensing is ability to standardize applied mediolateral forces across patients and surgeons. In the assessment of the ‘ideal' static ligament tension in extension a force of 80N was preferred over 50N, which is in the range of forces applied by others during ligament balancing. What is the ideal patient specific force to apply remains a topic of future research. Our next steps will be to further evaluate use of the system in the context of virtual trialing

Introduction. The purpose of this study was to examine whether three types of mobile-bearing PCL sacrificing TKA could restore the native knee translation and rotation. The primary hypothesis was that there are differences in knee kinematics and laxity between three different cruciate-substituting TKA designs: 1 with post-cam mechanism, 2 post-cam mechanism based on an inter-condylar ‘third condyle’ concept, 3 anterior stabilized with deep-dished highly congruent tibial insert; specifically, showing different femoral external rotation with flexion, different femoral translation with flexion and different laxity under stress test. The secondary hypothesis was that there is different clinical outcome between the three TKA designs at 2 years follow-up. Methods. We recruited 3 cohorts consisting of 30 patients each divided according 3 different TKA designs. All patients were operated with navigated procedure. During surgery preoperative and postoperative kinematics were recorded, in terms of femoral antero-posterior translation and tibial rotation during knee flexion, as also preoperative and postoperative at 2 years follow-up clinical scores have been acquired. Results. Preoperative rotation pattern were superimposable for all three cohorts of patients. All patients showed an average external rotation of 12±5° in extension. In the first part of flexion (0°-30°) screw-home mechanism was present with an internal tibial rotation of about 8°. After this the rotation of the tibia remained stable within 1° up to 120°. After implant, compared to preoperative status, all patients had less external rotation in extension, (6.5±7.1° for First; 4.6±5.3° for Gemini; 5.6±7.2° for Noetos), even if this reduced external rotation did not change significanlty with respect to preoperative conditions (Fig.2). Screw home mechanism was distributed in a larger flexion range (0–90° for HLS Noetos, 0–100° for FIRST, 0–110° for Gemini) with respect to native knee. Pre-operative translation of medial and lateral compartments of femur had similar pattern in all three cohorts. After implant, knee was in a more anterior position in extension, especially in the medial compartment. For all implants femoral position in flexion (range 90–120°) was similar to native knee. After implant all clinical scores were significantly improved (p<0.001). No differences were found between the three cohorts both in the pre-operative and post-operative values. CONCLUSION. All clinical scores, of the three cohorts of patients, were significantly improved postoperatively compared to the preoperative values. Rotating platform MB TKA reproduced femoral translation and tibial rotation postoperatively compared to preoperative knees, despite design variations. Moreover, no superiority of one design over another in clinical function was observed

Introduction. The project of a modular, double-conicity stem is born from the need to obtain primary stability and correct osseointegration in patients with developmental hip dysplasia, or proximal femoral dysmorphisms requiring a femoral shortening osteotomy or presenting characteristics of non-adaptability to single-conicity or straight stems. Such an implant could also be employed in femoral nail failures, or lateral femoral neck fractures requiring prosthetic substitution. Aim of the study. To assess implantability of the new double-conicity stem in cadaver femurs, determining “fit and fill” and the behaviour of femoral cortical bone by means of Rx, CT and pre- and post-implantation mechanical testing. Methods. Seven double-conicity stems with anti-rotation fins were implanted in cadaver femurs of various sizes. All femurs underwent pre- and post-implantation radiological assessment for evaluation of fit and fill at the 2 levels corresponding to the 2 conicities, fins penetration, possible microfractures and stem positioning. Prior to implantation, templating was carried out to define the correct size of the stem to be implanted. Modular necks with cervico-diaphyseal angle of 125° or 135° (short or long) were implanted, to preserve the correct rotation center and femoral offset. In 2 femurs, mechanical testing was performed before and after implantation, in order to assess, by means of strain gauges, the variation of the tensional state of cortical bone under dynamic loading (gait cycle simulation). In 2 femurs, 3 cm chevron shortening osteotomies were performed and stabilized with the stem alone. Results. Implanted stems respected pre-operative planning. In the 2 cases in which shortening osteotomies were performed, the stem allowed for good meta-diaphyseal stability without the employment of fixation devices. Radiographic assessment evidenced a valid “fit and fill”. In 4 cases the stem was correctly aligned; in 2 cases it was positioned in 1° varus and in 1 case in 1° valgus. In the 2 osteotomy cases, penetration of the fins was good at the proximal level and slight distally. In the remaining 4 cases penetration at both levels ranged from slight to good. No microfractures, either intraoperative or following stress testing, were evidenced. Mechanical tests showed that stem implantation reduced deformation of the femoral cortical bone undergoing cyclic loading, in comparison with the pre-implantation situation. Conclusions. The double-conicity prosthetic stem showed good implantability, with the capacity to allow for stability in case of femoral shortening osteotomies without the use of plates or cerclage fixation. Mechanical testing also showed a correct load distribution, and a reduction of stress on femoral cortical bone in comparison with the state before implantation. Prospective clinical studies are necessary to assess efficacy and dependability from a clinical and radiographic viewpoint

Soft tissue balancing in total knee replacement may well be the determining factor in raising the fair patient satisfaction. The development of intelligent implants allows quantification of reactive loads to applied pressures. This can be tested in dynamic mode such as heel push test at surgery, or in static mode such as when testing for varus/valgus (VV) laxity of the collateral ligaments of the knee. We postulate that a well-balanced knee will have comparable if not equal load distribution across compartments in dynamic loading. When tested for laxity, we anticipate an equal or comparable response to VV applied loads under physiologic load range of 10–50N. This study sought to analyze the relationship between the kinematic (joint motion) and kinetic (force) effects to VV testing in the 0–15 degrees range of flexion. One goal was to demonstrate that testing the knee in locked extension (Screw Home effect) is unreliable and should be abandoned in favor of the more reliable VV testing at 10–15 degrees of flexion. This is a preliminary cadaveric study utilizing data from two hemibodies. The pelvis was fixed in a custom test rig with open or closed chain lower leg testing capability along a sliding rail with foot VV translational. Forces were applied at the malleoli with a wireless hand held dynamometer. Kinematic analysis of the hip-knee-ankle (HKA) tibiofemoral angle was derived from a commercial navigation system with mounted infrared trackers. Kinetic analysis was derived from a commercially available sensor imbedded in a tibial trial liner. Balance was optimized by conventional methods with the use of the sensor feedback until loads were roughly symmetrical and VV testing yielded symmetrical rise in opposite compartments. The VV testing was then performed with the knees locked at the femoral side in axial rotation and translational motion in any plane. Sagittal flexion was pre-set at 0, 10, and 15 degrees and progressive load was applied. Results. From the graphs one can observe significant differences between VV testing at 0 degrees (locked Screw Home), 10 degrees, and 15 degrees of flexion. The shaded area corresponds to the common range of VV stress testing loading pressure, typically less than 35N. The HKA deviates from neutrality no sooner than by the middle of the physiologic test zone. By 35N, the magnitude of the effect is also much less than that observed at 10 and 15 degrees (unlocked from Screw Home). From the kinetic analysis one can also note the significant difference in the High-Low spread throughout the testing range of applied pressure. If the surgeon tests in the low range of applied loads, he/she may not observe the kinematic joint opening effect. The kinetic effect seems more reliable as sensed loads are detectable earlier on. It is clear however that testing at 10–15 degrees offers a much better sensitivity to the VV laxity or stiffness as exemplified in the bottom portions of the figure. Therefore testing in locked Screw Home full extension may lead to underestimation of the true coronal laxity of the joint

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Care should be given to assessing collateral ligament integrity. This can be done during physical examination by manual or radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate ligament retaining knees, anteroposterior instability must be assessed. For instability, most revisions will require a posterior cruciate substituting design or a constrained unlinked condylar design that, although sometimes a posterior cruciate ligament preserving design can be used in situations where the bone-stock is well preserved. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. During revision surgery, laminar spreaders may be utilised to assess the flexion and extension spaces after the tibial platform is restored. If a symmetric flexion and extension space is achieved, then the collateral ligaments are intact. Depending on the remaining existing bone stock, a posterior stabilised or constrained condylar unlinked prosthesis may be used for implantation. In cases with considerable asymmetry or a large flexion/extension mismatch, then a rotating hinge design should be utilised. Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Currently, stems should be placed cementless to permit easier future revision. Cementing the stems is only recommended if there is lack of intramedullary isthmic support or there is a hip prosthetic stem that prohibits a stem from engaging the isthmic cortex. However, it should be realised that later revision of the fully cemented revision implant may be quite difficult. Infection should be ruled out by aspiration off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Care should be given to assessing collateral ligament integrity. This can be done during physical examination by radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate retaining knees, anteroposterior instability must be assessed. For instability, must revisions will require a posterior cruciate substituting design or a constrained condylar design that are unlinked. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. During revision surgery, laminar spreaders may be utilised to assess the flexion and extension spaces after the tibial platform is restored. If a symmetric flexion and extension space are achieved, then the collateral ligaments are intact. Depending on the remaining existing bone stock, a posterior stabilised or constrained condylar unlinked prosthesis may be used for implantation. If there is considerable asymmetry or a large flexion/extension mismatch, then a rotating hinge design should be utilised. Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Currently, stems should be placed cementless to permit easier future revision. Cementing the stems is only recommended if there is lack of intramedullary isthmic support. However, revision of fully cemented revision implants may be quite difficult later. Infection should be ruled out by aspiration off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result

There have been few reports with efficient treatments for neglected distal tibiofibular syndesmosis disruption. Here we will report four cases of successful anatomical reconstruction with autologous gracilis tendon, using the interference fit anchoring (IFA) system. All four cases were males between 20 and 58 years of age at the time of surgery (mean age 36 years). The post-injury period to surgery was between 7 and 59 months (mean 20.1 months), with the consultation period being from 5 to 19 months (mean 9.5 months). Radiographs at the time of injuries were all malleolar fractures of pronation-external rotation (PE) stage 3 in the Lauge-Hansen classification. Stress tests for distal tibiofibular syndesmosis were positive in all cases (dilation more than 2 mm). Arthroscopic drilling was conducted in two cases with a cartilaginous injury of trochlea of talus. Distal tibiofibular syndesmosis was anatomically repositioned and was fixed with screws after bony and soft tissues within the tibiofibular syndesmosis were removed and fibular adhesion was dissected. Ipsilateral autologous gracilis tendon was passed through foramen in the insertion of the anterior inferior tibiofibular tendon on tibia and fibula, and was fixated using the IFA system. The preoperative Japanese society for surgery of the foot (JSSF) score was from 26 to 74 points (mean 43.5) and postoperative JSSF score was from 67 to 100 (mean 89.5). In a case where there was a poor outcome, five years of post injury had passed before the surgery. Although the JSSF score improved to 67 points postoperatively (from the preoperative score of 26) in this case, arthroscopic arthrodesis was conducted 5 months postoperatively due to persistent pain. Anatomical reconstruction with autologous gracilis tendon using the IFA system showed a favorable functional prognosis overall. However, there was a case with progressive degenerated changes of injured distal tibiofibular syndesmosis due to a prolonged post-injury period resulted in a poor outcome

Introduction. A few follow-up studies of high flexion total knee arthoplasties report disturbingly high incidences of femoral loosening. Finite element analysis showed a high risk for early loosening at the cement-implant interface at the anterior flange. However, femoral implant fixation is depending on two interfaces: cement-implant interface and the cement-bone interface. Due to the geometry of the distal femur, a part of the cement-bone interface consists of cement-cortical bone interface. The strength of the cement-bone interface is lower than the strength of the cement-implant interface. The research questions addressed in this study were: 1) which interface is more prone to loosening and 2) what is the effect of different surgical preparation techniques on the risk for early loosening. Materials & methods. To achieve data for the cement-(cortical)bone interface strength and the effects of different preparation techniques on interfacial strength, human cadaver interface stress tests were performed for different preparation techniques of the bony surface and the results were implemented in a finite element (FE) model as described before. The FE model consisted of a proximal tibia and fibula, TKA components, a quadriceps and patella tendon and a non-resurfaced patella. For use in this study, the distal femur was integrated in the FE model including cohesive interface elements and a 1 mm bone cement layer. In the model, the cement-bone interface was divided into two areas, representing cortical and cancellous bone. The posterior-stabilised PFC Sigma RP-F (DePuy, J&J, USA) was incorporated in the FE knee model following the surgical procedure provided by the manufacturer. A full weight-bearing squatting cycle was simulated (ROM = 50°-155°). The interface failure index was calculated. Results. Overall, the highest stresses were found at the proximo-medial part beneath the anterior flange of the femoral component. Highest shear stresses were found at the cement-implant interface (peak shear stress of 3.33 MPa at 150° of flexion). Highest tensile stresses were found at the cement-cortical bone interface (peak tensile stress of 1.30 MPa at 150° of flexion). The failure index was highest at the cement-bone interface. When the total anterior flange was covering cancellous bone, 0.4% of the cement-bone interface would fail and 0% of the cement-implant interface at 145° of flexion. In the more realistic simulation of cortical bone with periost, almost 31.3% of the complete cement-bone interface would fail even within normal range of motion (<120°). This can be reduced by drilling holes through the cortex to 2.6%. Discussion. Obviously, the FE knee model utilized in this study contains limitations which may have affected the interface stresses calculated. However, the results presented here clearly demonstrate high risk of early loosening at the cement-bone interface. This risk can be reduced by some simple preparation techniques of the cortex behind the anterior flange. Proper anterior fixation of the femoral component, and thus adequate surgical technique, is essential to reduce the risk of femoral loosening for high-flexion TKA