Stiffness is reported in up to 16% of patients after total knee replacement (TKR)1. Treatment of stiffness after TKR remains a challenge. Manipulation under anaesthesia (MUA) accounts for between 6%-36% of readmissions following TKR2,3. The outcomes of MUA remain variable/unpredictable. Post-operative CPM is used as an adjuvant to MUA, potentially offering improved ROM, however, remains the subject of debate. We report a retrospective study comparing MUA with and without post-operative CPM. In our institution patients undergoing MUA to receive CPM post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period MUA procedures were undertaken without CPM. Two cohorts were included: 1) MUA + post-operative CPM 2) Daycase MUA. Patients’ demographics, pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded. Between 2017-2022 126 patients underwent MUA and were admitted for CPM and 42 had daycase MUA. The median Age was 66.5 and 64% were female. 57% had extension deficit (>5o), 70% had flexion deficit (< 90o), and 37% had both. The mean Pre-operative ROM was 72.3o(SD:18.3o) vs. 68.5o(19.0o), ROM at MUA was 95.5o(SD:20.7o) vs 108.3o(SD:14.1o) [p< 0.01], and at final follow-up 87.4o(SD:21.9o) vs. 92.1o(SD:18.2o) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92%(SD:17) and 85%(SD:14)[p=0.03] for daycase and CPM groups respectively. There was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. The CPM group lost a greater ROM after MUA (15% vs. 8%). We conclude that post-operative CPM does not improve ROM achieved after MUA.
Stiffness is reported in 4%–16% of patients after having undergone total knee replacement (TKR). Limitation to range of motion (ROM) can limit a patient's ability to undertake activities of daily living with a knee flexion of 83o, 93o, and 106o required to walk up stairs, sit on a chair, and tie one's shoelaces respectively. The treatment of stiffness after TKR remains a challenge. Many treatment options are described for treating the stiff TKR. In addition to physiotherapy the most employed of these is manipulation under anaesthesia (MUA). MUA accounts for up to 36% of readmissions following TKR. Though frequently undertaken the outcomes of MUA remain variable and unpredictable. CPM as an adjuvant therapy to MUA remains the subject of debate. Combining the use of CPM after MUA in theory adds the potential benefits of CPM to those of MUA potentially offering greater improvements in ROM. This paper reports a retrospective study comparing patients who underwent MUA with and without post-operative CPM. Standard practice in our institution is for patients undergoing MUA for stiff TKR to receive CPM for between 12–24hours post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period several MUA procedures were undertaken without subsequent inpatient CPM. We retrospectively identified two cohorts of patients treated for stiff TKR: group 1) MUA + post-operative CPM 2) Daycase MUA. All patients had undergone initial physiotherapy to try and improve their ROM prior to proceeding to MUA. In addition to patients’ demographics pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded for each patient.Abstract
Objectives
Methods
Obesity is prevalent with nearly one third of the world's population being classified as obese. Total knee arthroplasty (TKA) is an effective treatment option for high BMI patients achieving similar outcomes to non-obese patients. However, increased rates of aseptic loosening in patients with a high BMI have been reported. In patients with high BMI/body mass there is an increase in strain placed on the implant fixation interfaces. As such component fixation is a potential concern when performing TKA in the obese patient. To address this concern the use of extended tibial stems in cemented implants or cementless fixation have been advocated. Extend tibial stems are thought to improve implant stability reducing the micromotion between interfaces and consequently the risk of aseptic loosening. Cementless implants, once biologic fixation is achieved, effectively integrate into bone eliminating an interface. This retrospective study compared the use of extended tibial stems and cementless implants to conventional cemented implants in high BMI patients. From a prospectively maintained database of 3239 primary Attune TKA (Depuy, Warsaw, Indiana), obese patients (body mass index (BMI) >30 kg/m²) were retrospectively reviewed. Two groups of patients 1) using a tibial stem extension [n=162] and 2) cementless fixation [n=163] were compared to 3) a control group (n=1426) with a standard tibial stem cemented implant. All operations were performed by or under the direct supervision of specialist arthroplasty surgeons. Analysis compared the groups with respect to class I, II, and III (BMI >30kg/m², >35 kg/m², >40 kg/m²) obesity. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Where radiographic images at greater than 3 months post-operatively were available, radiographs were examined to compare the presence of peri-implant radiolucent lines.Abstract
Objectives
Methods
Up to 20% of patients can remain dissatisfied following TKR. A proportion of TKRs will need early revision with aseptic loosening the most common. The ATTUNE TKR was introduced in 2011 as successor to its predicate design The PFC Sigma (DePuy Synthes, Warsaw, In). However, following reports of early failures of the tibial component there have been ongoing concerns of increased loosening rates with the ATTUNE TKR. In 2017 a redesigned tibial baseplate (S+) was introduced, which included cement pockets and an increased surface roughness to improve cement bonding. Given the concerns of early tibial loosening with the ATTUNE knee system, this study aimed to compare revision rates and those specific to aseptic loosening of the ATTUNE implant in comparison to an established predicate as well as other implant designs used in a high-volume arthroplasty centre. The Attune TKR was introduced to our unit in December 2011. Prior to this we routinely used a predicate design with an excellent long-term track record (PFC Sigma) which remains in use. In addition, other designs were available and used as per surgeon preference. Using a prospectively maintained database, we identified 10,202 patients who underwent primary cemented TKR at our institution between 01/04/2003–31/03/2022 with a minimum of 1 year follow-up (Mean 8.4years, range 1–20years): 1) 2406 with ATTUNE TKR (of which 557 were S+) 2) 4652 with PFC TKR 3) 3154 with other cemented designs. All implants were cemented using high viscosity cement. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Matched cohorts were selected from the ATTUNE subsets (original and S+) and PFC groups using the nearest neighbor method for radiographic analysis. Radiographs were assessed to compare the presence of radiolucent lines in the Attune S+, standard Attune, and PFC implants.Abstract
Objective
Methods
Total hip replacement (THR) is one of the most successful and cost-effective interventions in orthopaedic surgery. Dislocation is a debilitating complication of THR and managing an unstable THR constitutes a significant clinical challenge. Stability in THR is multifactorial and is influenced by surgical, patient and implant related factors. It is established that larger diameter femoral heads have a wider impingement-free range of movement and an increase in jump distance, both of which are relevant in reducing the risk of dislocation. However, they can generate higher frictional torque which has led to concerns related to increased wear and loosening. Furthermore, the potential for taper corrosion or trunnionosis is also a potential concern with larger femoral heads, particularly those made from cobalt-chrome. These concerns have meant there is hesitancy among surgeons to use larger sized heads. This study presents the comparison of clinical outcomes for different head sizes (28mm, 32mm and 36mm) in primary THR for 10,104 hips in a single centre. A retrospective study of all consecutive patients who underwent primary THR at our institution between 1st April 2003 and 31st Dec 2019 was undertaken. Institutional approval for this study was obtained. Demographic and surgical data were collected. The primary outcome measures were all-cause revision, revision for dislocation, and all-cause revision excluding dislocation. Continuous descriptive statistics used means, median values, ranges, and 95% confidence intervals where appropriate. Kaplan-Meier survival curves were used to estimate time to revision. Cox proportional hazard regression analysis was used to compare revision rates between the femoral head size groups. Adjustments were made for age at surgery, gender, primary diagnosis, ASA score, articulation type, and fixation method.Abstract
Objectives
Methods
The angle of acetabular inclination is an important measurement in total hip replacement (THR) procedures. Determining the acetabular component orientation intra-operatively remains a challenge. An increasing number of innovators have described techniques and devices to achieve it. This paper describes a mechanical inclinometer design to measure intra-operative acetabular cup inclination. Then, the mechanical device is tested to determine its accuracy. The aim was to design an inclinometer to measure inclination without existing instrumentation modification. The device was designed to meet the following criteria: 1. measure inclination with acceptable accuracy (+/− 5o); 2. easy to use intra-operatively (handling & visualization); 3. adaptable and useable with majority of instrumentation kits without modification; 4. sterilizable by all methods; 5. robust/reusable. The prototype device was drafted by computer aided design (CAD) software. Then a prototype was constructed using a 3D printer to establish the final format. The final device was CNC machined from SAE 304 stainless steel. The design uses an eccentrically weighted flywheel mounted on two W16002-2RS ball bearings pressed into symmetrical housing components. The weighted wheel is engraved with calibrated markings relative to its mass centre. Device functioning is dependent on gravity maintaining the weighted wheel in a fixed orientation while the housing can adapt to the calibration allowing for determining the corresponding measurement. The prototype device accuracy was compared to a digital device. A digital protractor was used to create an angle. The mechanical inclinometer (user blinded to digital reading) was used to determine the angle and compared to the digital reading. The accuracy of the device compared to the standard freehand technique was assessed using a saw bone pelvis fixed in a lateral decubitus position. 18 surgeons (6 expert, 6 intermediate, 6 novice) were asked to place an uncemented acetabular cup in a saw bone pelvis to a target of 40 degrees. First freehand then using the inclinometer. The inclination was determined using a custom-built inertial measurement unit with the user blinded to the result. Comparison between the mechanical and digital devices showed that the mechanical device had an average error of −0.2, a standard deviation of 1.5, and range −3.3 to 2.6. The average root mean square error was 1.1 with a standard deviation of 0.9. Comparison of the inclinometer to the freehand technique showed that with the freehand component placement 50% of the surgeons were outside the acceptable range of 35–45 degrees. The use of the inclinometer resulted all participants to achieve placement within the acceptable range. It was noted that expert surgeons were more accurate at achieving the target inclination when compared to less experienced surgeons. This work demonstrates that the design and initial testing of a mechanical inclinometer is suitable for use in determining the acetabular cup inclination in THR. Experimental testing showed that the device is accurate to within acceptable limits and reliably improved the accuracy of uncemented cup implantation in all surgeons.
Method of fixation in THA is a contentious issue, with proponents of either technique citing improved implant survival and outcomes. Current comparisons rely on insufficiently powered studies with short-term follow up or larger poorly controlled registry studies. Patient factors are considered a key variable contributing to the risk of implant failure. One way to overcome this confounder is to compare the survival of cementless and cemented THAs patients who have undergone bilateral THAs with cemented hip on one side and cementless hip on the other. We compared stem survival of patients who have bilateral THA with one cemented stem in one hip and a cementless stem in the contralateral hip in the National Joint Registry. UK National Joint Registry is the largest registry of its kind in the world. This study included 2934 patients with 5868 THAs who underwent bilateral THAs s between 2003 and 2016. These patients had undergone bilateral sequential THAs within 3 years of each other: cemented THA on one side and cementless on the other, Patients had identical pre-operative American Society of Anaesthesiologists group for both THAs and same indication for surgery. Implant survival was compared using Cox regression with an endpoint of stem revision.Background
Methods
Intraoperative periprosthetic femoral fractures (IOPFF) lead to reduced implant survival. A deeper understanding of predictors enables surgeons to modify techniques and patient selection to reduce the risk of IOPFF. The aim of this study was to estimate predictors of IOPFF and each anatomical subtype (calcar crack, trochanteric fracture, femoral shaft fracture) during primary THA. This retrospective cohort study included 793823 primary THAs between 2004 and 2016. Relative risks for patient, surgical and implant factors are estimated for any IOPFF fracture and for all anatomical subtypes of IOPFF.Introduction
Methods
Hip fractures cause significant morbidity and mortality, affecting 70,000 people in the UK each year. The dynamic hip screw (DHS) is used for the osteosynthesis of extracapsular neck of femur fractures, a procedure that requires complex psychomotor skills to achieve optimal lag screw positioning. The tip-apex distance (TAD) is a measure of the position of the lag screw from the apex of the femoral head, and is the most comprehensive predictor of cut-out (failure of the DHS construct). To develop these skills, trainees need exposure to the procedure, however with the European Working Time Directive, this is becoming harder to achieve. Simulation can be used as an adjunct to theatre learning, however it is limited. FluoroSim is a digital fluoroscopy simulator that can be used in conjunction with workshop bones to simulate the first step of the DHS procedure (guide-wire insertion) using image guidance. This study assessed the construct validity of FluoroSim. The null hypothesis stated that there would be no difference in the objective metrics recorded from FluoroSim between users with different exposure to the DHS procedure. This multicentre study recruited twenty-six orthopaedic doctors. They were categorised into three groups based on the number of DHS procedures they had completed as the primary surgeon (novice <10, intermediate 10≤x<40 and experienced ≥40). Twenty-six participants completed a single DHS guide-wire attempt into a workshop bone using FluoroSim. The TAD, procedural time, number of radiographs, number of guide-wire retires and cut-out rate (COR) were recorded for each attempt.Background
Methods
Training within surgery is changing from the traditional Halstedian apprenticeship model. There is need for objective assessment of trainees, especially their technical skills, to ensure they are safe to practice and to highlight areas for development. In addition, due to working time restrictions in both the UK and the US, theatre time is being limited for trainees, reducing their opportunities to learn such technical skills. Simulation is one adjunct to training that can be utilised to both assess trainees objectively, and provide a platform for trainees to develop their skills in a safe and controlled environment. The insertion of a dynamic hip screw (DHS) relies on complex psychomotor skills to obtain an optimal implant position. The tip-apex distance (TAD) is a measurement of this positioning, used to predict failure of the implant. These skills can be obtained away from theatre using workshop bone simulation, however this method does not utilise fluoroscopy due to the associated radiation risks. FluoroSim is a novel digital fluoroscopy simulator that can recreate digital radiographs with workshop bone simulation for the insertion of a DHS guide-wire. In this study, we present the training effect demonstrated on FluoroSim. The null hypothesis states that no difference will be present between users with different amounts of exposure to FluoroSim. Medical students were recruited from three London universities and randomised into a training (n=23) and a control (n=22) cohort. All participants watched a video explanation of the simulator and task and were blinded to their allocation. Training participants completed 10 attempts in total, 5 attempts in week one, followed by a one week wash out period, followed by 5 attempts in week 2. The control group completed a single attempt each week. For each attempt, 5 metrics were recorded; TAD, procedural time, number of radiographs, number of guide-wire retires and cut-out rate (COR).Background
Methods
Hip fractures affect 1.6 million people globally per annum, associated with significant morbidity and mortality. A large proportion are extracapsular neck of femur fractures, treated with the dynamic hip screw (DHS). Mechanical failure due to cut-out is seen in up to 7% of DHS implants. The most important predictor of cut-out is the tip-apex distance (TAD), a numerical value of the lag screw”s position in the femoral head. This distance is determined by the psychomotor skills of the surgeon guided by fluoroscopic imaging in theatre. With the current state of surgical training, it is harder for junior trainees to gain exposure to these operations, resulting in reduced practice. Additionally, methods of simulation using workshop bones do not utilise the imaging component due to the associated radiation risks. We present a digital fluoroscopy software, FluoroSim, a realistic, affordable, and accessible fluoroscopic simulation tool that can be used with workshop bones to simulate the first step of the DHS procedure. Additionally, we present the first round of accuracy tests with this software. The software was developed at the Royal National Orthopaedic Hospital, London, England. Two orthogonally placed cameras were used to track two coloured markers attached to a DHS guide-wire. Affine transformation matrices were used in both the anterior-posterior (AP) and cross table lateral (CTL) planes to match three points from the camera image of the workshop bone to three points on a pre-loaded hip radiograph. The two centre points of each marker were identified with image processing algorithms and utilised to digitally produce a line representing the guide-wire on the two radiographs. To test the accuracy of the system, the software generated 3D guide-wire apex distance (GAD) (from the tip of the guide-wire to a marker at the centre of calibration) was compared to the same distance measured with a digital calliper (MGAD). In addition, the same accuracy value was determined in a simulation scenario, from 406 attempts by 67 medical students.Background
Methods
Traditional TKR designs exhibit abnormal and unpredictable kinematics: with posterior subluxation in extension and anterior slide with flexion. These can contribute to restricted knee flexion and reduced quadriceps efficiency. Newer designs attempt to provide “guided motion” with the aim of mimicking normal knee kinematics. The Journey (Smith & Nephew) BCS TKR incorporates both an anterior and a posterior cam/post mechanism while Triathlon PS TKR (Stryker) incorporates a posterior cam/post mechanism. This study compares the in-vivo kinematics of these two designs and compares it with normal knee. Knee kinematics of 10 patients with Journey-BCS TKR and 11 patients with Triathlon PS TKR; all with excellent clinical outcome (average age: 65) were analysed. Patients underwent fluoroscopic assessment of the knee during a step-up and deep knee bend exercise. 2D fluoroscopic images were recorded. Data was analysed for patella tendon angle (PTA) and contact points using a 3D model fitting technique. This data was compared to normal knee kinematics (n=20).Introduction
Methods
This study reports a clinical comparison of new and old establishing whether this modified implant has maintained the established normal kinematic profile of the Oxford UKR.
Knee kinematics were assessed by analysing the movement of the femur relative to the tibia using the PTA.
