Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New Zealand. Outcomes following knee arthroplasty are typically defined as implant survivorship at defined timepoints, or revision incidence over time. These estimates are difficult to conceptualise, and lack context for younger patients with more remaining years of life. We therefore aimed to determine a ‘lifetime’ risk of revision as a more useful metric for total (TKA) and unicompartmental knee arthroplasty (UKA). The New Zealand Joint Registry was used to identify 96,497 primary TKAs and 13,481 primary UKAs performed between 1999 and 2019. Patient mortality and revision incidence were also extracted. Estimates of lifetime risk were calculated using an actuarial lifetable method. The estimates were stratified by age and gender. Reasons for revision were categorised using previously published standardised definitions. The lifetime risk of UKA revision was two-fold higher than TKA across all age groups (range 3.7-40.4% UKA, 1.6-22.4% TKA). Revision risk was higher for males with TKA (range 3.4%-25.2% males, 1.1%-20% females), but higher for females with UKA (range 4.3%-43.4% vs. 2.9%-37.4% for males). Revision due to infections were higher for TKA (1.5% males, 0.7% females) compared with UKA (0.4% males, 0.1% females). The increased risk in younger UKA patients was associated with higher incidence of aseptic loosening (UKA 2%, TKA 1%) and ‘unexplained pain’ (UKA 2%, TKA 0.2%). The risk for UKA was two-fold higher than TKA, and this was partially explained by a higher proportion of revisions due to ‘unexplained pain’. For TKA, males had higher risk of revision, in contrast to UKA where females had higher risk; this gender difference was associated with higher incidence of infections with TKA. Younger age, gender and higher ASA status were also associated with increased lifetime risk of UKA revision. Lifetime risk of revision can provide a meaningful measure of arthroplasty outcomes to aid patient counselling

Aim. The current recommendation in Norway is to use four doses of a first-generation cephalosporin (cefazolin or cephalotin) as systemic antibiotic prophylaxis (SAP) the day of surgery in primary joint arthroplasty. Due to shortage of supply, scientific development, changed courses of treatment and improved antibiotic stewardship, this recommendation has been disputed. We therefore wanted to assess if one dose of SAP was non-inferior to four doses in preventing periprosthetic joint infection (PJI) in primary joint arthroplasty. Method. We included patients with primary hip- and knee arthroplasties from the Norwegian Arthroplasty Register and the Norwegian Hip Fracture Register for the period 2005-2023. We included the most used SAPs (cephalotin, cefazolin, cefuroxime, cloxacillin and clindamycin), administered as the only SAP in 1-4 doses, starting preoperatively. Risk of revision (Hazard rate ratio; HRR) for PJI was estimated by Cox regression analyses with adjustment for sex, age, ASA class, duration of surgery, reason for- and type of arthroplasty, and year of primary arthroplasty. The outcome was 1-year reoperation or revision for PJI. Non-inferiority margins were calculated for 1, 2 and 3 doses versus reference of 4 doses of SAP at the day of surgery, against a predetermined limit of 15% increased risk of PJI. Results. In total 274,188 primary arthroplasties (total hip 133,985, hemi hip 51,442, and total knee 88,761) were included. Of these primary arthroplasties, 2,996 (1.1%) had subsequent revisions for PJI during the first postoperative year. One dose of SAP was given in 9,603 arthroplasties, two doses in 10,068, three doses in 18,351, and four doses in 236,166 arthroplasties. With the recommended four doses as reference, the HRR (95% CI) for 1-year revision for infection was 0.9 (0.7-1.1) for one dose, 1.0 (0.8-1.2) for two doses, and 0.9 (0.8-1.1) for three doses. The corresponding adjusted 1-year revision incidences for PJI was 0.9 (0.7-1.1), 1.0 (0.8-1.2), 0.9 (0. 8-1.1) and 1.0 (1.0-1.1) for one, two, three and four doses respectively, and less than four doses was found to be non-inferior. Conclusions. One preoperative dose of SAP in primary joint arthroplasty surgery seems to be non-inferior to the current recommendation of four doses of a first-generation cephalosporin as PJI-prophylaxis. This finding may simplify the course of treatment for arthroplasty patients, save costs, and improve antibiotic stewardship

Background. Total knee arthroplasty (TKA) is a proven and cost-effective treatment for osteoarthritis. Despite the good to excellent long-term results, some patients remain dissatisfied. Our study aimed at establishing a predictive model to aid patient selection and decision-making in TKA. Methods. Using data from our prospective arthroplasty outcome database, 113 patients were included. Pre- and postoperatively, the patients completed 107 questions in 5 questionnaires: KOOS, OKS, PCS, EQ-5D and KSS. First, outcome parameters were compared between the satisfied and dissatisfied group. Secondly, we developed a new prediction tool using regression analysis. Each outcome score was analysed with simple regression. Subsequently, the predictive weight of individual questions was evaluated applying multiple linear regression. Finally, 10 questions were retained to construct a new prediction tool. Results. Overall satisfaction rate in this study was found to be 88%. We identified a significant difference between the satisfied and dissatisfied group when looking at the preoperative questionnaires. Dissatisfied patients had more preoperative symptoms (such as stiffness), less pain and a lower QOL. They were more likely to ruminate and had a lower preoperative KSS satisfaction score. The developed prediction tool consists of 10 simple, but robust questions. Sensitivity was 97% with a positive predictive value of 93%. Conclusions. Based upon preoperative parameters, we were able to partially predict satisfaction and dissatisfaction after TKA. After further validation this new prediction tool for patient satisfaction following TKA may allow surgeons and patients to evaluate the risks and benefits of surgery on an individual basis and help in patient selection

The histopathology of periprosthetic tissues has been important to understanding the relationship between wear debris and arthroplasty outcome. In a landmark 1977paper, Willert and Semlitsch (1) used a semiquantitative rating to show that tissue reactions largely reflected the extent of particulate debris. Notably, small amounts of debris, including metal, could be eliminated without “overstraining the tissues” but excess debris led to deleterious changes. Currently, a plethora of terms is used to describe tissues from metal-on-metal (M-M) hips and corroded modular connections. We reviewed the evaluation and reporting of local tissue reactions over time, and asked if a dose response has been found between metal and tissue features, and how the use of more standardized terms and quantitative methodologies could reduce the current confusion in terminology. Methods. The PubMed database was searchedbetween 2000 and 2015 for papers using “metal sensitivity /allergy /hypersensitivity, Adverse Local Tissue Reaction (ALTR): osteolysis, metallosis, lymphocytic infiltration, Aseptic Lymphocytic Vasculitis-Associated Lesions (ALVAL), Adverse Reaction to Metal Debris (ARMD) or pseudotumor/ pseudotumour” as well as metal-on-metal / metal-metal AND hip arthroplasty/replacement. Reports lacking soft tissue histological analysis were excluded. Results. 131 articles describing M-M tissue histology were found. In earlier studies, the terms metal sensitivity / hypersensitivity /allergy implied or stated the potential for a Type IV delayed type hypersensitivity response as a reason for revision. More recently those terms have largely been replaced by broader terms such as ALTR, ALVAL and ARMD. ALVAL and metal hypersensitivity were often used interchangeably, both as failure modes and histological findings. Several histology scoring systems have been published but were only used in a limited number of studies. Correlations of histological features with metal levels or component wear were inconclusive, typically because of a high degree of variability. Interestingly, there were very few descriptions that concluded that the observed reactions were benign / normal or anticipated i.e. regardless of the histological features, extent of debris or failure mode, the histology was interpreted as showing an adverse reaction. Discussion. There is now an expanded set of terms to describe tissues but they lack clear definitions and typically do not use quantitative histological data to describe a wide range of periprosthetic reactions to metal. Lower limits of inflammation, necrosis or re-organization that represent a “normal” reaction to surgery and/or small amounts of wear debris are not clearly defined and are rarely discussed. The widespread adoption of the term “adverse” in the present tissue lexicon implies a cause and effect relationship between metal wear and corrosion products and histological features even though this has yet to be determined. The use of quantitative histological scores rather than subjective histological descriptions is imperative to improve the understanding and reporting of the range of periprosthetic reactions. In particular, a new lexicon that allows for a level of tissue reaction that is not misinterpreted as adverse is required

In the early days of total hip arthroplasty, the discussion of surgical approaches centered on issues related to obtaining optimum exposure for accurate insertion and fixation of implants and appropriate restoration of hip kinematics. More recently, attention has been directed to those aspects of exposure that appear to be associated with rapid recovery, shorter lengths of stay, less pain and minimal gait disturbance. The role of less invasive (“MIS”) exposures in achieving these outcomes has been sharply and extensively debated. Currently, the Direct Anterior Approach is being used by an increasing number of surgeons to address these outcomes. The purpose of this presentation is to discuss the relationship of total hip surgical approaches to peri-operative morbidity, rate of functional recovery, length of hospital stay and ultimate lower extremity function. Many factors affect the quality and rate of recovery from THA surgery. These include: 1) patient characteristics; 2) implant type; 3) surgical exposure and technique; and 4) peri-operative management. Numerous reports suggest that patient selection and effective peri-operative management have the greatest impact on the rate of recovery. The quality of the arthroplasty outcome is related to the accuracy with which the procedure is performed, regardless of the surgical approach used. Available evidence strongly suggests that the quality of the surgical technique used to perform a THA is a much more important determinant of outcome than the surgical approach used

Introduction. Our primary hypothesis was simple: does gait on a downhill gradient distinguish between types of knee arthroplasty? Our secondary hypotheses were these: are stride length and other kinematic variables affected by cruciate ligament integrity following knee arthroplasty?. Participants. Ethical approval was sought and gained prior to commencement of the study. 52 subjects were tested on the instrumented treadmill, 3 groups (UKA, TKA, and young healthy control) of 19, 14, and 19 respectively. The two high performing arthroplasty groups were recruited from a database of patient related outcome measures (PROMs) and were chosen based on high Oxford knee scores (OKS) with a minimum 12 months post hip arthroplasty. Gait Analysis. Gait performance was tested on a validated instrumented treadmill (Kistler Gaitway®, Kistler Instrument Corporation, Amherst NY)[22, 23]. The rear of the treadmill was ramped with 30 cm axle stands in order to create a 7 degree decline for downhill walking (figure 1). The speed was increased incrementally. Hof scaling and body weight normalising was also applied to the outputted mechanical data to correct for leg length and mass differences, respectively. Results. Patient Related Outcome Measures. Both arthroplasty groups outcome scores were substantially better than the average reported by national joint registries. Treadmill Gait Analysis. When walking fast downhill, UKA patients walked 15% faster than the TKA patients (1.75 vs 1.52 m/sec p=0.000) despite having the same cadence (134 vs 135step/min) (figures 2,3,4). The 15% difference in speed was largely due to the reduced mean step (p=0.001) and stride lengths (p=0.000) seen in the TKA patients. These finding persisted after Hof scaling, which normalised speed for leg length (p=0.000). The values are indicated as means ± standard deviation; †significant difference between implant versus control (p <0.05); ‡significant difference between implant groups (p<0.05);H=normalized to leg length; BW=normalized to body weight. Discussion. The UKA group walked 15% faster than the TKA, with stride length almost matching the normal controls. The presence of intact cruciate ligaments allow a normal and co-ordinated swing phase, enabling the more normal stride, while the absence of the anterior cruciate ligament contributes to the reduction of knee flexion in swing phase, and thus the shorter stride length

Introduction. In 1976 the senior author presented to the Associations the results of patellectomy with satisfactory results in less than 50% of cases. In 1989 with the increasing success of TKR we started a prospective study of the Lubinus prosthesis for patellofemoral arthritis. After 4 years results were not satisfactory. The main causes of failure were mal-tracking and instability leading to polythene button wear, and arthritic disease progression. A new prosthesis was designed in 1996 to correct these problems. Methods. We have prospectively recorded the results of a consecutive cohort of 537 Avon arthroplasties. The outcomes have been assessed with survivorship, pain, Oxford and WOMAC scores. We have identified 24 patients from our own series and from tertiary referrals who have persistent pain, due to technical error rather than arthritic disease progression. Results. Survivorship for revision at 5 Years was 96% and overall there were 63 revisions. Results over 10 years show excellent and consistent improvement in both pain and function as judged by the median WOMAC score and are similar to patients with a TKR. The pain score improved from 45% (16) to 87% (7.5), the function score improved from 50% (21) to 80% (12.5). The Oxford score improved from 39.5% (19) to 69% (33). Symptomatic arthritic disease progression occurred in 12% of cases causing recurrent pain. Persistent non-arthritic pain was due to three main causes: minor misplacement of the femoral or patella components or over sizing, leading to retinacular impingement and over stuffing of the patellofemoral joint. Conclusion. This prosthesis has shown consistently good results with few problems over 14 years. New instruments will increase the accuracy of insertion and attention to detail in the performance of the operation will prevent problems. Disease progression remains the main cause of failure and strict pre-operative criteria are essential