Abstract. Objective. 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. Methods. 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. Results. At a mean of 8.4 years follow-up, 308 implants underwent revision equating to 3.58 revisions per 1000 implant-years. The lowest risk of revision was noted in the ATTUNE cohort with 2.98 per 1000-implant-years where the PFC and All Other Implant groups were 3.15 and 4.4 respectively. Aseptic loosing was the most common cause for revision across all cemented implants with 76% (65/88) of involving loosening of the tibia. Survival analysis comparing the ATTUNE cohort to the PFC and All Other Cemented Implant cohorts showed no significant differences for: all-cause revision, aseptic loosening, or tibial loosening (p=0.15,0.77,0.47). Radiolucent lines were detected in 4.6%, 5.8%, and 5.0% of the ATTUNE S+, standard ATTUNE, and PFC groups respectively. These differences were not significant. Conclusion. This study represents the largest non-registry review of the original and S+ ATTUNE TKR in comparison to its predicate design as well as other cemented implants. There appears to be no significant increased revision rate for all-cause revision or aseptic loosening. Radiographic analysis also showed no significant difference in peri-implant radiolucency. It appears that concerns of early loosening may be unfounded. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Introduction. Unicompartmental Knee Replacement (UKR) is an appealing alternative to Total Knee Replacement (TKR) when the patient has isolated compartment osteoarthritis (OA). A common observation post-operatively is radiolucency between the tibial tray wall and the bone. In addition, some patients complain of persistent pain following implantation with a UKR; this may be related to elevated bone strains in the tibia. The aim of this study was to investigate the mechanical environment of the tibia bone adjacent to the tray wall, following UKR, to determine whether this region of bone resorbs, and how altering the mechanical environment affects tibia strains. Materials and methods. A finite element (FE) model of a cadaver tibia implanted with an Oxford UKR was used in this study, based on a validated model. A single static load, measured in-vivo during a step-up activity was used. There was a 1 mm layer of cement surrounding the keel in the cemented UKR, and the cement filled the cement pocket. In accordance with the operating procedure, no cement was used between the tray wall and bone. For the cementless UKR a layer of titanium filled the cement pocket. An intact tibia was used to compare to the cemented and cementless UKR implanted tibiae. The tibia was sectioned by the tray wall, defining the radiolucency zone (parallel to the vertical tray wall, 2 mm wide with a volume of 782.5 mm. 3. ), corresponding to the region on screened x-rays where radiolucencies are observed. Contact mechanics algorithms were used between all contacting surfaces; bonded contact was also introduced between the tray wall and adjacent bone, simulating a mechanical tie between them. Strain energy density (SED), was compared between the intact and implanted tibia for the radiolucency zone. Equivalent strains were compared on the proximal tibia between the intact and implanted tibia models. Forty patients (20 cemented, 20 cementless) who had undergone UKR were randomly selected from a database, and assessed for radiolucency. Results. The SED in the radiolucency zone was 80% lower in the cemented and cementless tibia, compared to the intact tibia, without a mechanical tie between the tibial tray wall and adjacent bone. When a mechanical tie was introduced the SED in the radiolucency zone was 35% higher in the cemented and cementless tibia, compared to the intact tibia. The strain on the proximal tibia was reduced by 20% when a mechanical tie was used between the tray wall and adjacent bone. Radiolucency at the tray wall was observed in all forty radiographs examined. Discussion. This work has presented a static snapshot of the load being carried through the proximal tibia following implantation with an Oxford UKR. It has been shown that by introducing a mechanical tie between the tibial tray wall and the adjacent bone, the SED in the region observed to have radiolucency is increased; this has the potential of reducing the likelihood of a radiolucency occurring in that region. Moreover, the strain observed in the proximal tibia was reduced when a mechanical tie was introduced, which may reduce the incidence of pain following implantation with a UKR. It is recommended that integration between the bone and the tray wall is important for UKR

Introduction and Objective. Difficult primary total knee arthroplasty (TKA) and revision TKA are high demanding procedures. Joint exposure is the first issue to face off, in order to achieve a good result. Aim of this study is to evaluate the clinical and radiological outcomes of a series of patients, who underwent TKA and revision TKA, where tibial tubercle osteotomy (TTO) was performed. Materials and Methods. We retrospectively reviewed a cohort of 79 consecutives TKAs where TTO was performed, from our Institution registry. Patients were assessed clinically and radiographically at their last follow-up (mean, 7.4 ± 3.7 years). Clinical evaluation included the Knee Society Score (KSS), the pain visual analogue scale (VAS), and range of motion. Radiological assessment included the evaluation of radiolucent lines, osteolysis, cortical bone hypertrophy, time of bone healing of the TTO fragment, and the hardware complication. Results. KSS raised from 40.7 ± 3.1 to 75 ± 4.3 (p < 0.0001). Knee flexion increased from 78.7 ± 9.9° to 95.0 ± 9.5° (p < 0.0001), and VAS improved from 7.9 ± 0.9 to 3.8 ± 1 (p < 0.0001). No signs of loosening or evolutive radiolucency lineswere found. Osteolytic areas around the stem were detected. No significant association was found between the implant design and the outcomes, while aseptic loosening showed significantly better results. Complications were: 4 painful hardware, 3 late periprosthetic infections, 1 extension lag of 5°, and 3 flexion lag. Conclusions. Our experience suggests the use of TTO to improve the surgical approach in difficult primary TKA or revision TKA. A strict surgical technique leads to good results with low risk of complications

Introduction and Objective. The surgical strategy for acetabular component revision is determined by available host bone stock. Acetabular bone deficiencies vary from cavitary or segmental defects to complete discontinuity. For segmental acetabular defects with more than 50% of the graft supporting the cup it is recommended the application of reinforcement ring or ilioischial antiprotrusio devices. Acetabular reconstruction with the use of the antiprotrusion cage (APC) and allografts represents a reliable procedure to manage severe periprosthetic deficiencies with highly successful long-term outcomes in revision arthroplasty. Objective. We present our experience, results, critical issues and technical innovations aimed at improving survival rates of antiprotrusio cages. Materials and Methods. From 2004 to 2019 we performed 69 revisions of the acetabulum using defrosted morcellized bone graft and the Burch Schneider anti-protrusion cage. The approach was direct lateral in 25 cases, direct anterior in 44. Patients were re-evaluated with standard radiography and clinical examination. Results. Eight patients died from causes not related to surgery, and two patients were not available for follow up. Five patients were reviewed for, respectively, non-osseointegration of the ring, post-traumatic loosening with rupture of the screws preceded by the appearance of supero-medial radiolucency, post-traumatic rupture of the distal flange, post-traumatic rupture of the cemented polyethylene-ceramic insert, and dislocation treated with new dual-mobility insert. Among these cases, the first three did not show macroscopic signs of osseointegration of the ring, and the only areas of stability were represented by the bone-cement contact at the holes in the ring. Although radiographic studies have shown fast remodeling of the bone graft and the implant survival range from 70% to 100% in the 10-year follow up, the actual osseointegration of the ring has yet to be clarified. To improve osseointegration of the currently available APC whose metal surface in contact with the bone is sandblasted, we combined the main features of the APC design long validated by surgical experience with the 3D-Metal Technology for high porosity of the external surface already applied to and validated with the press fit cups. The new APC design is produced with the 3D-Metal technology using Titanium alloy (Ti6Al4V ELI) that Improves fatigue resistance, primary stability and favorable environment for bone graft ingrowth. We preview the results of the first cases with short-term follow up. Conclusions. Acetabular reconstruction with impacted morcellized bone graft and APC is a current and reliable surgical technique that allows the restoration of bone loss with a high survival rate of the implant in the medium to long term. The new 3D Metal Cage is designed to offer high friction for the initial stability. The high porosity of the 3D Metal structure creates a favorable environment for bone growth, thus providing valid secondary fixation reproducing the results achieved with the 3D metal press fit cup

Background. Implant stability and is an important factor for adequate bone remodelling and both are crucial in the long-term clinical survival of total hip arthroplasty (THA). Assessment of early bone remodelling on X-rays during the first 2 years post-operatively is mandatory when stepwise introduction of a new implant is performed. Regardless of fixation type (cemented or cementless), early acetabular component migration is usually the weakest link in THA, eventually leading to loosening. Over the past years, a shift towards uncemented cup designs has occurred. Besides the established hydroxyapatite (HA) coated uncemented cups which provide ongrowth of bone, new uncemented implant designs stimulating ingrowth of bone have increased in popularity. These cups initiate ingrowth of bone into the implant by their open metallic structure with peripheral pores, to obtain a mechanical interlock with the surrounding bone, thereby stabilising the prosthesis in an early stage after implantation. This retrospective study assessed bone remodelling, osseointegration and occurrence of radiolucency around a new ingrowth philosophy acetabular implant. Methods. In a retrospectively, single centre cohort study all patients whom underwent primary THA with a Tritanium acetabular component in 2011 were included. Bone remodelling, osseointegration and occurrence of radiolucency were determined by two reviewers from X-ray images that were made at 6 weeks, 3–6-12 and 24 months post-operatively. Bone contact % was calculated based on the original Charnley and DeLee zones. According to Charnley and DeLee the outer surface of an acetabular cup is divided into 3 zones (1-2-3). For our analysis the original 3 zones were further divided into 2 producing 6 zones 1A to 3B. Each of these 6 zones were then further divided into 4 equal sections. We attributed 25 points per section in which complete bone contact without lucency was observed. If lucency was observed no points were attributed to the section. A fully osteointegrated cup in all 24 sections could therefore attain 600 points. The total of each section and zone was subsequently tallied and recalculated to produce the percentage of bone contact on a 1–100% score. Results. In 2011 131 patients; 54 male and 76 female with average age of 60.83 (SD 12.42) and 60.57 (SD 12.11) year respectively underwent primary THA at our institution and all where included in our study cohort. Majority of this cohort underwent primary THA due to osteoarthrosis and most patients were classified ASO I (18%) or ASA II (65%). At two year clinical follow-up two revision were performed. One constituted a femur and acetabulum revision due to leg length difference and a snapping hip phenomenon. Complications included 3 dislocations (all treated policlinic), 4 deep infections (all treated with Genta PMMA beads with prosthesis in situ and healed) and 1 removal of hematoma. In another patient the femoral component was revised due to a peri-prosthetic fracture. Mean bone contact % values for all Charnley and DeLee zones combined were calculated and improved from 68,18% (SD 22,36) at 6 weeks to 73,61% SD (16,26) at 3 months to 84,21% (SD 19,02) at 6 months to 86,90% (SD 16,0) at 1 year to 92,19% (SD 12,74) at two year follow-up. When analysing the bone contact % per individual zone a remarkable difference was found for zones 2A-B. In contrast to zone 1A-B and 3A-B the initial bone contact % was clearly although not significantly lower until two year follow-up. Conclusions. In this study, the bone apposition around Tritanium actebular component was retrospectively assessed until two year clinical. Our results show excellent bone apposition that continues to improve over time (at least until two year clinical follow-up) suggesting that the open trabecular Ti structure of the Tritanium has a positive effect on cup osseointegration. However, some recent reports have shown the development of reactive lines around cups with porous/trabecular metal surfaces, of which the meaning is still unclear. Our analysis indicated that especially acetabular zone 2A-B according to Charnley&DeLee needs time to establish a direct contact of the implant surface and the surrounding bone tissues. Perhaps this might be explained by reaming technique (underreaming vs line to line reaming) resulting in suboptimal seating of the cup. Therefore, careful follow-up of this new implant technology will remain necessary and continued in this study. We aim to improve cohort size and establish results at longer follow-up times. Furthermore we aim to correlate these results to RSA component migration analysis

The function of the knee joint is to allow for locomotion and is comprised of various bodily structures including the four major ligaments; medial collateral ligament (MCL), lateral collateral ligament (LCL), anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). The primary function of the ligaments are to provide stability to the joint. The knee is prone to injury as a result of osteoarthritis as well as ligamentous and meniscal lesions. Furthermore, compromised joint integrity due to ligamentous injury may be a result of direct and indirect trauma, illness, occupational hazard as well as lifestyle. A device capable of non-invasively determining the condition of the ligaments in the knee joint would be a useful tool to assist the clinician in making a more informed diagnosis and prognosis of the injury. Furthermore, the device would potentially reduce the probability of a misdiagnosis, timely diagnosis and avoidable surgeries. The existing Laxmeter prototype (UK IPN: GB2520046) is a Stress Radiography Device currently limited to measuring the laxity of the MCL and LCL at multiple fixed degrees of knee flexion. Laxity refers to the measure of a ligament's elasticity and stiffness i.e. the condition of the ligament, by applying a known load (200N) to various aspects of the proximal tibial and thereby inducing tibial translation. The extent of translation would indicate the condition of the ligament. The Laxmeter does not feature a load applying component as of yet, however, it allows for the patient to be in the most comfortable and ideal position during radiographic laxity measurement testing. The entire structure is radiolucent and attempts to address the limitations of existing laxity measurement devices, which includes: excessive radiation exposure to the radiographic assistant, little consideration for patient ergonomics and restrictions to cruciate or collateral ligament laxity measurements. The study focusses on further developing and modifying the Laxmeter to allow for: the laxity measurement of all four major ligaments of the knee joint, foldability for improved storage and increased structural integrity. Additionally, a load applicator has been designed as an add-on to the system thereby making the Laxmeter a complete Stress Radiography Device. Various materials including Nylon, Polycarbonate, Ultra High Molecular Weight Polyethylene (UHMWPE) – PE 1000, and Acetal/ POM were tested, using the Low Dose X-ray (Lodox) scanner, to determine their radiolucency. All materials were found to be radiolucent enough for the manufacture of the Laxmeter structure as well as the load applicator in order to identify and measure the translation of the tibia with respect to the stationary femur. The Laxmeter allows for the measurement of the laxity of the MCL and LCL at multiple fixed degrees of flexion by providing the ideal patient position for testing. The next iteration of the device will present an affordable and complete Stress Radiography Device capable of measuring the laxity of all four major ligaments of the knee joint at multiple fixed degrees of flexion. Future work would include aesthetic considerations as well as an investigation into carbon-fibre-reinforced plastics

We have examined 26 retrieved, failed titanium-alloy femoral stems. The clinical details, radiological appearances and the histology of the surrounding soft tissues in each patient were also investigated. The stems were predominantly of the flanged design and had a characteristic pattern of wear. A review of the radiographs showed a series of changes, progressive with time. The first was lateral debonding with subsidence of the stem. This was followed by calcar resorption and fragmentation or fracture of the cement. Finally, osteolysis was seen, starting with a radiolucency at the cement-bone interface and progressing to endosteal cavitation. Three histological appearances were noted: granulomatous, necrobiotic and necrotic. We suggest that an unknown factor, possibly related to the design of the stem, caused it to move early. After this, micromovement at the cement-stem interface led to the generation of particulate debris and fracture of the cement. A soft-tissue reaction to the debris resulted in osteolysis and failure of fixation of the prostheses

We examined the radiographs from a prospective clinical study of fixation by pedicle screws and those from an experimental study in a sheep model. In the clinical study, instruments were removed from 21 patients after implantation for 11 to 16 months and the extraction torques of the screws were recorded. A structured protocol was used for the radiological examinations. In the experimental study, loaded pedicle screw instrumentations were implanted in the sheep for six or 12 weeks. After radiological examination the pull-out resistance and the histological characteristics were studied. In the clinical study, all screws with radiolucent zones had a significantly reduced mean extraction torque compared with screws without radiolucent zones (16 ± 10 Ncm v 403 ± 220 Ncm; p < 0.0001). In the experimental study the mean maximum pull-out resistance for the screws with radiolucent zones was significantly lower than for those with no radiolucency (243 ± 156 N v 2214 ± 578 N; p = 0.0006) and the mean bone-to-screw contact was reduced for screws with zones compared with those without zones (8 ± 9% v 55 ± 29%; p = 0.0002). Our findings showed that all screws with radiolucent zones had low extraction torques or low pull-out resistance. A radiolucent zone is a good indicator of loosening of a pedicle screw

Introduction. Hip resurfacing arthroplasty (HRA) with metal-on-metal bearing is currently emerging as a major evolution of hip arthroplasty. It could be an alternative to total hip arthroplasty. HRA also may allow young patients to perform high sports activities. It preserves proximal femoral bone stock and keeps the medullary canal intact. A large diameter of the femoral head provides wider range of the hip motion. Incidence of dislocation is very low. Most of HRA have been reported for young patients with stage of osteoarthritis. But, reports of HRA for osteonecrosis of the femoral head (ONFH) are rare and the outcomes are uncertain. Methods. This study was performed to introduce our indication and technique of HRA for the patients with ONFH and to assess the outcomes after a minimum 5-year follow up. After the biomechanical study, we set our own indications for HRA as follows: when the size of a lesion was less than 50% of the entire head and the rim at the head-neck junction was intact at least to a 5 mm above from the head-neck junction. From December 1998 to July 2004; 157 hips (139 patients) underwent HRA under the diagnosis of ONFH. Their mean age was 37 years. One hundred and fourteen hips were in men and 25 hips were in women. The average follow-up period was 88 months (range, 60 to 128 months). Clinical outcomes were evaluated with Harris Hip Scores, hip or thigh pain, limb length discrepancy, and range of motion. As a radiological evaluation, the preoperative size and staging of the lesion, patterns of bone remodeling, and complications such as femoral neck fracture, neck narrowing, loosening, and osteolysis were analyzed. Results. Sixty-two percent of the hips were staged as Steinberg IV or more. The size of the necrotic lesion in magnetic resonance imaging ranged from 23 to 50%. The Harris Hip Score increased from 77 points pre-operatively to 98 points at the final visit. All range of motions significantly improved after the operation. No patient complained of limb length discrepancy. Twenty-eight hips showed painless radiographic changes including impingement (22 hips), focal radiolucency (4 hips), and neck narrowing (2 hips). All patients showed no clinical symptoms. There was no detectable wear, dislocation, femoral neck fracture, or other complications. No revision or additional surgery was required in all patients. Conclusion. Even for the patients with ONFH, the overall minimum 5-year outcomes of HRA are promising and superior to other reports of conventional THA. Patient satisfaction is extremely high. A strict application of indications and meticulous surgical technique are critical for these successful results

Objectives

To review the systemic impact of smoking on bone healing as evidenced within the orthopaedic literature.

Studies on the migration of an implant may be the only way of monitoring the early performance of metal-on-metal prostheses. The Ein Bild Roentgen Analyse - femoral component analysis (EBRA-FCA) method was adapted to measure migration of the femoral component in a metal-on-metal surface arthroplasty of the hip using standard antero-posterior radiographs. In order to determine the accuracy and precision of this method a prosthesis was implanted into cadaver bones. Eleven series of radiographs were used to perform a zero-migration study. After adjustment of the femoral component to simulate migration of 3 mm the radiographs were repeated. All were measured independently by three different observers.

The accuracy of the method was found to be ± 1.6 mm for the x-direction and ± 2 mm for the y-direction (95% percentile). The method was validated using 28 hips with a minimum follow-up of 3.5 years after arthroplasty. Seventeen were sound, but 11 had failed because of loosening of the femoral component. The normal (control) group had a different pattern of migration compared with that of the loose group. At 29.2 months, the control group showed a mean migration of 1.62 mm and 1.05 mm compared with 4.39 mm and 4.05 mm in the failed group, for the centre of the head and the tip of the stem, respectively (p = 0.001). In the failed group, the mean time to migration greater than 2 mm was earlier than the onset of clinical symptoms or radiological evidence of failure, 19.1 versus 32.2 months (p = 0.001) and 24.8 months (p = 0.012), respectively.

EBRA-FCA is a reliable and valid tool for measuring migration of the femoral component after surface arthroplasty and can be used to predict early failure of the implant. It may be of value in determining the long-term performance of surface arthroplasty.

Post-mortem retrieval of canine, cemented femoral components was analysed to assess the performance of these implants in the dog as a model for human total hip replacement (THR). Mechanical testing and radiological analysis were performed to determine the stability of the implant and the quality of the cement. Thirty-eight implants from 29 dogs were retrieved after time intervals ranging from 0.67 to 11.67 years. The incidence of aseptic loosening was 63.2%, much higher than in human patients (6% in post-mortem studies). Failure of the femoral implants began with debonding at the cement-metal interface, similar to that in implants in man. The incidence of aseptic loosening was much lower in bilateral than in unilateral implants. Significant differences were observed for three different designs of implant. While the dog remains the animal model of choice for THR, results from this study provide insight into interspecies differences in the performance of implants. For example, the performance of THR in dogs should be compared with that in young rather than in elderly human patients.