Abstract. Background. Oxidized zirconium (OxZr) has been introduced as an alternative bearing for femoral components in Total Knee Arthroplasty (TKA). It has a ceramic-like zirconium oxide outer layer with a low coefficient of friction. Early studies have found OxZr TKA to have a low incidence of early failure in young high demand patients. Currently no study has reported on the outcome of these implants beyond ten years. Objectives. The purpose of our study was to present an in-depth 15-year survival analysis of cemented Profix II OxZr TKA. Study Design & Methods. Data was collected prospectively and survival analysis undertaken with multiple strict end points. Complication rates were recorded and patient reported outcomes were measured. Results. 617 Profix II OxZr TKAs were performed over four years. Forty-nine patients underwent reoperation. Aseptic tibial loosening was the most common cause of failure (32.7%) on average occurring 2.8 years post primary procedure. There was one recorded failure due to loosening of the zirconium femoral component. Revision rate at 15-years was 6.38%. Cumulative survivorship was 91.52% with failure considered to be reoperation for any reason. WOMAC score improved in 86% of patients by year 1. The average score improved by 21.2 points and met the standard for minimum clinically important difference. Conclusions. This study presents the first 15-year survival analysis of cemented Profix II OxZr TKA. Our data supports current literature on the long-term survivorship of oxidised zirconium total knee replacements

Unicompartmental knee osteoarthritis can be treated with either Total Knee Arthroplasty (TKA) or Unicompartmental Knee Arthroplasty (UKA) and controversy remains as to which treatment is best. UKA has been reported to offer a variety of advantages, however many still see it as a temporary procedure with higher revision rates. We aimed to clarify the role of UKA and evaluate the long-term and revision outcomes. We retrospectively reviewed the pain, function and total Knee Society Score (KSS) for 602 UKA and 602 TKA in age and gender matched patients over ten years. The total pre-operative KSS scores were not significantly different between UKA and TKA (42.67 vs 40.54 P=0.021). KSS (pain) was significantly better in the TKA group (44.39 vs 41.38 P= 0.007) at one year and at five years post-operatively (45.33 vs 43.12 P=0.004). There was no statistically significant difference for KSS (total) in TKA and UKA during the study period. 16.3% of UKA and 20.1% of TKA had a documented complication. 79 UKA (13%) and 36 TKA (6%) required revision surgery. Despite the higher revision rate, pre-operative KSS (total) before revision was not significantly different between UKA and TKA (42.94 vs 42.43 P=0.84). Performance for UKAs was inferior to TKAs in Kaplan-Meier cumulative survival analysis at 10 years (P<0.001). Both UKA and TKA are viable treatment options for unicompartmental knee osteoarthritis, each with their own merits. UKA is associated with fewer complications whereas TKA provides better initial pain relief and is more durable and less likely to require revision

Studies on recurrent disc herniation quote rates of recurrence without regard to the times of recurrence and the influence of longer follow-up. Our objective was to assess the use of survival analysis to measure the rate of revision after lumbar microdiscectomy. We undertook a retrospective analysis of the hospital records of 993 patients who underwent lumbar microdiscectomy over a period of ten years. After calculating the overall rate of revision for the mean length of follow-up, we carried out a survival analysis using the life-table method. During the study period 49 patients had a revision microdiscectomy. This gave an overall rate of revision of 4.9% at a mean follow-up of 5.25 years. Using survival analysis, the rate of revision was 7.9% at a follow-up of ten years when the number at risk was 84. Survival analysis gives a more accurate estimation of the true rate of recurrence for patients undergoing lumbar microdiscectomy. The method allows better comparison between different interventions for disc herniation

Survival analysis is an important tool for assessing the outcome of total joint replacement. The Kaplan-Meier method is used to estimate the incidence of revision of a prosthesis over time, but does not account appropriately for competing events which preclude revision. In the presence of competing death, this method will lead to statistical bias and the curve will lose its interpretability. A valid comparison of survival results between studies using the method is impossible without accounting for different rates of competing events. An alternative and easily applicable approach, the cumulative incidence of competing risk, is proposed. Using three simulated data sets and realistic data from a cohort of 406 consecutive cementless total hip prostheses, followed up for a minimum of ten years, both approaches were compared and the magnitude of potential bias was highlighted. The Kaplan-Meier method overestimated the incidence of revision by almost 4% (60% relative difference) in the simulations and more than 1% (31.3% relative difference) in the realistic data set. The cumulative incidence of competing risk approach allows for appropriate accounting of competing risk and, as such, offers an improved ability to compare survival results across studies

Background: Publications concerning recurrent disc disease quote percentage recurrence without regard to the times of recurrence and the influence of longer follow-up. Objective: To assess the use of survival analysis to measure revision rate after lumbar microdiscectomy. Design: A retrospective analysis of the hospital records of all patients undergoing lumbar microdiscectomy over a nine-year period was undertaken. Patients who had a repeat microdiscectomy at the same level as the index procedure were designated ‘revisions’. The overall revision rate was calculated for the average length of follow-up. A survival analysis was then carried out using the life table method, as described by Murray et al for follow-up of hip arthroplasty. Subjects: Seven hundred and twenty-nine patients underwent primary microdiscectomy during this time period, average age 40 years. Results: Twenty-seven patients had a revision microdiscectomy during the study period. This gave an overall revision rate of 3.7% at average follow up of five years, one month. Using survival analysis the revision rate was 5.5% at eight years of follow up, number at risk 51. Conclusions: Survival analysis gives a more accurate estimation of the true recurrence rate for patients undergoing lumbar microdiscectomy. The method would allow better comparison between different interventions for intervertebral disc herniation

Aims. The aim of this to study was to compare the previously unreported long-term survival outcome of the Oxford medial unicompartmental knee arthroplasty (UKA) performed by trainee surgeons and consultants. . Patients and Methods. We therefore identified a previously unreported cohort of 1084 knees in 947 patients who had a UKA inserted for anteromedial knee arthritis by consultants and surgeons in training, at a tertiary arthroplasty centre and performed survival analysis on the group with revision as the endpoint. Results. The ten-year cumulative survival rate for revision or exchange of any part of the prosthetic components was 93.2% (95% confidence interval (CI) 86.1 to 100, number at risk 45). Consultant surgeons had a nine-year cumulative survival rate of 93.9% (95% CI 90.2 to 97.6, number at risk 16). Trainee surgeons had a cumulative nine-year survival rate of 93.0% (95% CI 90.3 to 95.7, number at risk 35). Although there was no differences in implant survival between consultants and trainees (p = 0.30), there was a difference in failure pattern whereby all re-operations performed for bearing dislocation (n = 7), occurred in the trainee group. This accounted for 0.6% of the entire cohort and 15% of the re-operations. . Conclusion. This is the largest single series of the Oxford UKA ever reported and demonstrates that good results can be achieved by a heterogeneous group of surgeons, including trainees, if performed within a high-volume centre with considerable experience with the procedure. Cite this article: Bone Joint J 2016;(10 Suppl B):22–7

We describe a prospective survival analysis of 63 consecutive meniscal allografts transplanted into 57 patients. The lateral meniscus was transplanted in 34, the medial meniscus in 17, and both menisci (combined) in the same knee in six. For survival analysis we used persistent pain or mechanical damage as clinical criteria of failure. A total of 13 allografts failed (5 lateral, 7 medial, 1 medial and lateral). A significant negative correlation (p = 0.003) was found between rupture of the anterior cruciate ligament (ACL) and successful meniscal transplantation. A significant difference (p = 0.004) in the clinical results was found between lateral and medial meniscal transplants. The cumulative survival rate of the lateral, medial and combined allografts in the same knee, based on the life-table method and the Kaplan-Meier calculation, was 76%, 50% and 67%, respectively. The survival of medial meniscal allografts may improve when reconstruction of the ACL is carried out at the same time as meniscal transplantation in an ACL-deficient knee

Survival analysis is a powerful tool for analysing the results of total joint replacement, but it has major drawbacks when the failure rates are very low. We have reviewed 35 recent survival analyses of joint replacements to assess the magnitude of these problems and make recommendations as to how they may be avoided

Arthroscopy of ankle is becoming a common procedure for the diagnosis and treatment of ankle pain. Little information exists regarding the long term prognosis following ankle arthroscopy, particularly in avoiding further major surgery. The purpose of this study is to evaluate the prognosis of arthroscopic ankle treatment, based on survival analysis. Also we will formalise the relationship between the arthroscopic treatment and time for a further major ankle surgery. Type of study. Consecutive Case Series study using prospectively gathered data. Methods. Eighty consecutive patients (80 ankles) having ankle arthroscopy (between 1998 and 2000) with the finding of OA or impingement were identified and their outcome at five years ascertained. Results. Fifty-five (69%) patients had soft tissue impingement, and 25 (31%) patients had osteoarthritic degenerative changes. Seven (9%) patients had further major surgery (arthrodesis or arthroplasty) and 6 (8%) had repeat arthroscopy. The surgery was required for 7 arthritic ankles within five years of arthroscopic procedure. Survival analysis showed no statistical significance between those under 50 and those over 50 years in the OA group. Seven (28%) of osteoarthritic patients progress to major ankle surgery, within 5 years of arthroscopic treatment. None of the patients with impingement symptoms required further major surgery. Conclusion. Arthroscopically treated impingement ankles have an excellent prognosis, while osteoarthritic ankles have a less favoured prognosis, with a high proportion requiring further major surgery. Age does not affect prognosis in the OA group

Objective: The purpose of this study is to evaluate the prognosis of arthroscopic ankle treatment. Also we will formalise the relationship between the arthroscopic treatment and time for a further major ankle surgery. Patients and Methods: Consecutive Case Series study using prospectively gathered database. Between January 1997 to December 2000, Eighty consecutive patients (80 ankles) having ankle arthroscopy with the finding of Osteoarthritis (OA) or impingement were identified and their outcome at five years ascertained. Arthroscopic procedure involved pre operative skin markings. Ankle distraction is used. An anterior approach used with standard Anteromedial and antero-lateral portals. Treatment: debridement of osteochondral lesions, removal of loose bodies, curettage, drilling, synovec-tomy, and abrasion of the subchondral bone. All ankle joints had wash out. Results: Results were examined using Kaplan Meier survival analysis. Statistical analysis of the results was done using Chi squared test. Fifty five (69%) patients had soft tissue impingement, and 25 (31%) patients had osteoarthritic degenerative changes. Seven (9%) patients had further major surgery and 6 (8%) had repeat arthroscopy. The surgery was required for 7 arthritic ankles (7/25). Survivorship: Survival analysis. 28% of osteoarthritic patients progress to major ankle surgery, within 5 years of arthroscopic treatment. None of patients with impingement symptoms required further major surgery. No statistical significance between those under 50 and those over 50 years in OA group. Conclusion: Arthroscopically treated impingement Ankles has an excellent prognosis, while osteoarthritic ankles have less favoured prognosis, with high proportion requiring further major surgery. Age does not affect prognosis in O.A group. Arthroscopy for OA, is likely to fail within 18 months

Introduction: Osteogenic Sarcoma is one of the most common malignant bone tumors in the younger population. The advances in chemotherapy in conjunction with surgery has improved the survival rates from less than 20% in 1970s to more than 70% in 1990s. Advanced imaging, better histopathological techniques, availability of bone banks and newer chemotherapeutic agents have made limb salvage surgery a viable option even in advanced stages of the disease. We reviewed the outcome and analysed the complications of patients with Osteogenic Sarcoma at our institution. Materials and methods: The objective of our study was to evaluate our experience with the treatment of osteogenic sarcoma and to do a survival analysis. It was a retrospective study consisting of 20 patients who were treated between 1990–1998. Mean age was 17 years with equal distribution of males and females. Of all the patients, 18 had stage II b disease and 2 patients had stage III disease. The quetionnaire focused on the initial mode of presentation of the patients, their stage of disease, the type of neo-adjuvent chemotherapy used and the type of surgery they underwent. Results: Majority of the patients presented at least six months after the onset of symptoms with pain and swelling being the most common modes of presentation. Majority of our patients had open biopsies done outside our hospital and received non-uniform neo-adjuvant chemotherapy. Distal femur was involved in 60% of the cases followed by proximal and distal tibia. Limb salvage surgery was performed in 90% of the cases, while the rest had primary amputation due to the extent of the disease. Autoclaved bone, allografts, free fibular grafts and custom made prostheses were used to reconstruct the intercalary defects left by the resection of the tumor. Polyuria was our main early post operative complication followed by wound infection. Only one patient had a local recurrence and 7/20 had distant metastasis in our follow-up (mean 2.5 years). Mortality rate was 25% in our study. Conclusion: Limb salvage surgery was performed quite successfully with only one local recurrence in all of our patients with stage II b disease. Most of our patients who developed late distant metastasis had a non-uniform and uncontrolled chemotherapy protocol which could have adversely affected our final outcome

Aims: In this study, data from previously published survival analysis life tables of primary total condylar type TKRs has been combined to enable comparison of different design features. In particular, does posterior stabilisation or metal backing of the tibial component improve the longevity of primary cemented þxed bearing condylar type TKRs?Methods: To be included, the article had to give 5 or more years results of a primary cemented þxed bearing condylar type TKRs including a survival analysis life table. Series performed on a selected patient group (for example young age, elderly or rheumatoid arthritis) were excluded to reduce possible bias. When 2 series of the same implant from the same institution were available, the most recent article with the longest follow up was used. Results: Survival analysis data from 16 papers (5950 knees) was combined to compare design features. There was no difference in survival between posterior stabilised implants and those that were not or between metal-backed and all-polyethylene tibial components. Those all-polyethylene tibial components that were not stabilised had signiþcantly better survival than metal-backed, non stabilised tibial components and posterior stabilised, metalbacked components (p< 0.05) but not posterior stabilised, all-polyethylene components. Conclusions: Using the currently available literature, posterior stabilisation or metal backing of the tibial component does not improve the longevity of primary cemented þxed bearing condylar type TKRs

Objectives. To examine patient mortality, implant survivorship, and complication profiles of proximal femoral replacement (PFR) as compared to revision total hip arthroplasty (REV) or open reduction internal fixation (ORIF) in the treatment of acute periprosthetic fractures of the proximal femur. Methods. We performed a retrospective controlled chart review at our tertiary center from from 2000–2010, identifying 97 consecutive acute periprosthetic proximal femoral fractures. Patients were stratified into three treatment groups: PFR (n=21), REV (n=19), and ORIF (n=57). Primary outcome measures included death, implant failure, and reoperation. We also recorded patient demographics, medical comorbidities, fracture type, treatment duration, time to treatment, and complication profiles. Statistical analyis included competing risks survival, which allows independent survival analysis of competing failure mechanisms such as death and implant failure. Results. Competing Risks survival analysis of overall mortality during the mean 35-month follow-up showed no difference between the three groups (p=0.65; 12 and 60 month mortality for PFR: 37%, 45%; REV: 16%, 46%; ORIF: 14%, 100%). Implant survival was worse for the PFR group (p=0.03, 12 and 60-month implant failure rate for PFR: 5%, 39%; REV: 93%, 93%; ORIF 98%, 98%). Comparing PFR to REV and ORIF, PFR had a trend towards higher dislocation (19% vs. 5% vs. 4%, p=0.06). There was no difference between groups with regard to summary non-death complications including DVT, infection, dislocation, and other measures (30% vs. 40% vs. 34%, p=0.80). Operative times were not different between groups (172 min. vs. 162 min. vs. 168 min, p=0.92). Conclusions. In treating difficult periprosthetic fractures, PFR as compared with REV or ORIF has worse medium-term implant survival, primarily due to instability and dislocation. The groups had similar perioperative complication rates, similar short and long term mortality, and similar operative times

Although about 200 000 cementless Zweymüller-Alloclassic total hip arthroplasties (THAs) were carried out worldwide in the last decade, the survival analysis of these prostheses was not available in the 2000 report of the Swedish national hip arthroplasty registry. We report a prospective survivorship analysis of 200 consecutive grit-blasted cementless Alloclassic primary THAs carried out since 1988. Using surgical, clinical and radiological endpoints for the stem and the threaded cup the ten-year survivorship was 91.5% for reoperation for any cause, 96.4% for hip pain (Merle d’Aubigné score < 5 points, clinical failure), 99.4% for definite aseptic loosening (radiological failure) and 99.3% for revision for aseptic loosening. Using the Swedish registry criteria of primary osteoarthritis and revision for aseptic loosening as the endpoint, the survival rate of 99.1% at ten years for the subgroup of 157 Alloclassic THAs in osteoarthritis compares favourably with that of the best modern cemented hip replacements reported in the Swedish arthroplasty registry

We reviewed 264 consecutive primary total hip replacements in 244 patients in which the Harris-Galante I porous-coated acetabular component had been used. The mean follow-up was 95 months (69 to 132). In 221 arthroplasties a 32 mm ceramic head had been used, and in the other 43 one of cobalt-chrome alloy. There were 124 women and 120 men with a mean age at operation of 56.8 years (21 to 83). Survival analysis of the acetabular components was performed using the following definitions of failure: 1) infection; 2) removal because of aseptic loosening; 3) removal for any cause; and 4) a worst-case analysis including removal of the cup or infection or loss to follow-up. Two well-fixed cups had been removed because of deep infection and three, similarly sound cups had been exchanged at the time of femoral revision. None of the acetabular components had required revision for aseptic loosening. After 11 years survival was 97.7% using the worst-case criterion. Radiological analysis of 187 acetabular components at a mean of 82 months (41 to 132) revealed no case of aseptic loosening. Pelvic osteolysis was seen in only one patient, but was not progressive and showed signs of regression. The results using these acetabular components are encouraging but the need for regular follow-up remains since complications such as significant wear of the liner, massive osteolysis of the pelvis, aseptic loosening and late infection may increase in the second decade

Introduction: Unicompartmental osteoarticular defects of the knee are challenging due to demands of stability and function of this weight-bearing joint. Prostheses reconstruction often requires sacrificing the uninvolved compartment. Osteoarticular allograft reconstruction can restore the anatomy, and allows reattaching soft tissue structures such as meniscus and ligaments from the host. The purpose of this study was to perform a survival analysis of unicompartimental osteoarticular allografts of the knee and evaluate their complications. Material and Methods: Forty unicompartmental osteo-articular allograft of the knee performed in 38 patients during the period 1962–2001, were followed for a mean of 11 years. In 36 patients, the bone defect was created by the resection of a tumor (33 giant cell tumors, 1 osteogenic sarcoma, 1 chondrosarcoma and 1 malignant fibrous histiocytoma) and in the remaining two by an open fracture. Twenty nine transplants were located at the femur that includes 11 medial and 18 lateral condyles. Eleven transplants were located at the tibia, including 4 medial and 7 lateral tibial plateaus. According to the reconstructed compartment, host meniscus and ligaments were reattached to the graft. Rigid internal fixation with plates and screws were used in each patient. Allografts survival from the date of implantation to the date of revision or the time of the latest follow-up was determined with the use of the Kaplan-Meier method. Complications as local recurrence, fracture, articular collapse and infection were analyzed. Results: The global rate of allograft survival was 85% at five years. There were 8 complications in 6 patients: 2 local recurrences, 2 infections, 1 fracture, 1 massive resorption and 2 articular collapses. In 6 patients the allograft was removed and they were considered as failures. All these patients required a second allograft that included 2 unicompartmental and 4 bicompartimental reconstructions. The two patients with articular collapses required a regular total knee resurfacing prosthesis. Discussion: Although the incidence of reoperations due to allograft complications may be high, the allograft survivor rate at five years was 85%. Unicondylar allografts, appear to be an alternative in those situations in which the massive osteoarticular bone loss to be reconstructed, is limited to one knee compartment

Introduction. Reverse hybrid total hip replacement (THR) offers significant theoretical benefits but is uncommonly used. Our primary objective was to evaluate implant survival with all cause revision and revision for aseptic loosening of either component as endpoints. Patients/Materials & Methods. Data was collected prospectively on 1, 088 (988 patients) consecutive reverse hybrid THRs. Mean patient age was 69.3 years (range, 21–94) and mean follow-up was 8.2 years (range, 5–11.3). No patients were lost to follow-up. Overall, 194 (17.8%) procedures were performed in patients under 60 years, 666 (61.1%) were performed in female patients and 349 (32.1%) were performed by a trainee. Acetabular components were ultra-high molecular weight polyethylene in 415 (38.1%) hips, highly cross-linked polyethylene in 669 (61.5%) hips and vitamin E stabilised polyethylene in 4 (0.4%) hips. Femoral stems were collared in 757 (69.7%) hips and collarless in 331 (30.3%) hips. Femoral head sizes were 28 mm in 957 (87.9%) hips and 32 mm in 131 (12.1%) hips. Survival analysis was performed using Kaplan Meier methodology. Log rank tests were used to asses differences in survival by age, gender, head size and surgeon grade. Results. Ten-year implant survival (122 hips at risk) was 97.2% (95% CI 95.8–98.1%) for all cause revision (Figure 1), 100% for aseptic acetabular loosening and 99.6% (95% CI 99.0–99.9%) for aseptic stem loosening (Figure 2). There was no difference in implant survival by age (p = 0.39), gender (p = 0.68), head size (p = 0.76) or surgeon grade (p = 0.20) for all cause revision. There was no difference in survival by gender (p = 0.12), head size (p = 0.38) or surgeon grade (p = 0.76) for stem revision. Four (0.4%) stems failed at mean 2.5 years (range, 0.6–4.8) because they were undersized. These were associated with patient age under 60 years (p = 0.015). Discussion. This is the largest reported study on the outcomes of reverse hybrid THR in a consecutive series of patients at medium to long term follow-up. Cemented acetabular components are less costly than uncemented cups and offer other significant benefits such as improved fixation in osteoporotic or pathological bone, reduced risk of intraoperative periprosthetic fracture, easier revision and local antibiotic delivery which can reduce deep infection rates. Advantages of uncemented stems over cemented stems include biological fixation, shorter operating times, fewer adverse pulmonary events and reduced proximal stress shielding. Our results indicate high implant survival rates at ten-year follow-up with low rates of aseptic loosening (0.4%). Meticulous surgical technique is required to avoid stem undersizing which may lead to early failure particularly in younger patients. Conclusion. This study confirms that reverse hybrid THR offers highly successful outcomes, irrespective of age, gender, head size and surgeon grade. For any figures and tables, please contact the authors directly

Aims. The aim of this study is to report the implant survival and factors associated with revision of total elbow arthroplasty (TEA) using data from the Dutch national registry. Methods. All TEAs recorded in the Dutch national registry between 2014 and 2020 were included. The Kaplan-Meier method was used for survival analysis, and a logistic regression model was used to assess the factors associated with revision. Results. A total of 514 TEAs were included, of which 35 were revised. The five-year implant survival was 91%. Male sex, a higher BMI, and previous surgery to the same elbow showed a statistically significant association with revision (p < 0.036). Of the 35 revised implants, ten (29%) underwent a second revision. Conclusion. This study reports a five-year implant survival of TEA of 91%. Patient factors associated with revision are defined and can be used to optimize informed consent and shared decision-making. There was a high rate of secondary revisions. Cite this article: Bone Jt Open 2023;4(2):110–119

We used survival analysis to evaluate 113 consecutive semiconstrained total elbow arthroplasties (TEAs) in 95 patients at a maximum follow-up of 99 months. Our criteria for failure were mechanical malfunction, revision for any reason, and deep infection. The primary diagnosis was inflammatory arthritis in 86 elbows, post-traumatic arthritis in 6, supracondylar nonunion or fracture in 12, osteoarthritis in 2 and other causes in 3. Seven failures were due to deep infection, and five of these had a primary diagnosis of inflammatory arthritis. Eight failures were revised or had revision recommended for aseptic loosening, and six of these were in patients with post-traumatic arthritis or supracondylar nonunion. The cumulative survival for TEAs performed for post-traumatic arthritis, fractures or supracondylar nonunion was 73% at three years and 53% at five years, significantly worse than the cumulative three- and five-year survivals of 92% and 90%, respectively, for patients with inflammatory arthritis. TEA with a semiconstrained prosthesis appears to have a satisfactory survival in selected patients with arthritic disorders. The incidence of deep infection was reduced by improvements in surgical technique and postoperative management, and the routine use of antibiotic-impregnated cement. The incidence of aseptic loosening was low, except in patients with supracondylar nonunion or post-traumatic arthritis

Aims. Bacteriophages infect, replicate inside bacteria, and are released from the host through lysis. Here, we evaluate the effects of repetitive doses of the Staphylococcus aureus phage 191219 and gentamicin against haematogenous and early-stage biofilm implant-related infections in Galleria mellonella. Methods. For the haematogenous infection, G. mellonella larvae were implanted with a Kirschner wire (K-wire), infected with S. aureus, and subsequently phages and/or gentamicin were administered. For the early-stage biofilm implant infection, the K-wires were pre-incubated with S. aureus suspension before implantation. After 24 hours, the larvae received phages and/or gentamicin. In both models, the larvae also received daily doses of phages and/or gentamicin for up to five days. The effect was determined by survival analysis for five days and quantitative culture of bacteria after two days of repetitive doses. Results. In the haematogenous infection, a single combined dose of phages and gentamicin, and repetitive injections with gentamicin or in combination with phages, resulted in significantly improved survival rates. In the early-stage biofilm infection, only repetitive combined administration of phages and gentamicin led to a significantly increased survival. Additionally, a significant reduction in number of bacteria was observed in the larvae after receiving repetitive doses of phages and/or gentamicin in both infection models. Conclusion. Based on our results, a single dose of the combination of phages and gentamicin is sufficient to prevent a haematogenous S. aureus implant-related infection, whereas gentamicin needs to be administered daily for the same effect. To treat early-stage S. aureus implant-related infection, repetitive doses of the combination of phages and gentamicin are required. Cite this article: Bone Joint Res 2024;13(8):383–391