Aims. Unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) have both been shown to be effective treatments for osteoarthritis (OA) of the knee. Many studies have compared the outcomes of the two treatments, but less so with the use of robotics, or individualized TKA alignment techniques. Functional alignment (FA) is a novel technique for performing a TKA and shares many principles with UKA. Our aim was to compare outcomes from a case-matched series of robotic-assisted UKAs and robotic-assisted TKAs performed using FA. Methods. From a prospectively collected database between April 2015 and December 2019, patients who underwent a robotic-assisted medial UKA (RA-UKA) were case-matched with patients who had undergone a FA robotic-assisted TKA (RA-TKA) during the same time period. Patients were matched for preoperative BMI, sex, age, and Forgotten Joint Score (FJS). A total of 101 matched pairs were eligible for final review. Postoperatively the groups were then compared for differences in patient-reported outcome measures (PROMs), range of motion (ROM), ability to ascend and descend stairs, and ability to kneel. Results. Both groups had significant improvements in mean FJS (65.1 points in the TKA group and 65.3 points in the UKA group) and mean Oxford Knee Score (OKS) (20 points in the TKA group and 18.2 in the UKA group) two years following surgery. The UKA group had superior outcomes at three months in the OKS and at one year in ROM (5°), ability to kneel (0.5 points on OKS question), and ascend (1.3 points on OKS question) and descend stairs (0.8 points on OKS question), but these were not greater than the minimal clinically important difference. There were no differences seen in FJS or OKS at one year postoperatively. There were no statistically significant differences between the groups at 24 months in all the variables assessed. Conclusion. FA-RATKA and RA-UKA are both successful treatments for medial compartmental knee arthritis in this study. The UKA group showed a quicker recovery, but this study demonstrated equivalent two-year outcomes in all outcomes measured including stair ascent and descent, and kneeling. Cite this article: Bone Jt Open 2024;5(12):1123–1129

Objectives. Acetabular fractures with quadrilateral plate involvement have been shown to have a high rate of complications. Anatomic suprapectineal plating systems have been developed to manage these injuries with good short-term outcomes, however long-term maintenance of anatomical reduction and functional outcomes is yet to be established. Efficacy of maintenance of reduction and functional outcomes at a minimum of 5-years follow-up is the aim of this study. Design and Methods. A retrospective cohort study examining patients aged over 16 years following fixation of acetabular fractures with quadrilateral plate involvement at a trauma centre in the United Kingdom. All patients had acetabular fracture fixation with an anatomically designed suprapectineal plate. Patients were admitted from March 2014 to January 2017. Primary outcomes included objective radiological outcomes such as reduction quality, maintenance of reduction, metalwork failure, complications (such as reoperation, neurological deficit and mortality) and subjective patient-related outcome measures (PROMs) using the Oxford Hip Score and EuroQol EQ5D Score at a minimum of 5-years post-operatively. Results. 16 patients met our eligibility criteria in this cohort. Post-operative mean Oxford Hip Score (OHS) at a minimum of 5-years was 40.5 (SD 11.9) with a median score of 45. Post-operative mean EuroQol EQ-5D scores at a minimum of 5-years were 0.83 (SD 0.25). Comparison of OHS and EQ5D at 1-year and 5-years showed no significant difference (OHS p = 0.27 / EQ5D p = 0.128). Radiographic outcomes were assessed with AP and Judet plain radiographs at a minimum of 5-years follow-up. Rate of conversion to total hip replacement was 6.25%. 56.3% showed some evidence of dome comminution with 18.8% demonstrating dome impaction. 93.7% showed evidence of quadrilateral plate involvement. 12.5% showed evidence of femoral head injury. Conclusion. Maintenance of reduction and functional and patient reported outcomes using anatomically contoured suprapectineal plates do not change significantly between 1 year and 5 years follow-up

Background. The rise in the adoption of outpatient arthroplasty has been attributed to its cost-effectiveness, although safety concerns persist. In this meta-analysis, we compare inpatient and outpatient joint arthroplasty with a primary focus on readmission and complication rates, using exclusively high-quality prospective data. Cost-effectiveness was used as a secondary outcome measure. Methods. A literature search was performed in Medline, Embase and Cochrane Library from inception to October 2023. A predefined strategy was used to conduct a systematic review and meta-analysis. Twelve studies were deemed eligible for inclusion. These were critically appraised using RoB analysis and MINORS criteria. Overall readmission rate, readmission rate for THA, readmission rate for TKA, complication rate and cost-analysis were selected as outcomes of interest. Forest plots were extracted using RevMan 5.3.5 software. Results. The twelve studies included 2470 patients, of which 1052 were outpatients and 1418 inpatient subjects undergoing arthroplasty. Forest plot analysis showed no significant difference in safety outcomes (readmission and complication rates). However, there were significantly lower costs in the outpatient group compared to the inpatient group. The results of the analysis were; overall readmission rate (Odds ratio 0.66; P= 0.29; I. 2. =18%), readmission rate in THA (odds ratio 0.62; P=0.10; I. 2. =51%), readmission rate in TKA (odds ratio 0.67; P=0.56; I. 2. =0%), overall complication rate (odds ratio 0.77; P=0.12; I. 2. =38%) and cost analysis (RR −2.88; P<0.00001; I. 2. = 93%). Conclusions. This meta-analysis demonstrates that outpatient total joint arthroplasty (TJA) is a safe option, when compared to inpatient surgery. However, it is clear that further prospective studies and long-term randomized clinical data are necessary for a more comprehensive understanding

Aims. In the treatment of basal thumb osteoarthritis (OA), intra-articular autologous fat transplantation has become of great interest within recent years as a minimally invasive and effective alternative to surgical intervention with regard to pain reduction. This study aims to assess its long-term effectiveness. Methods. Patients diagnosed with stage one to three OA received a single intra-articular autologous fat transplantation. Fat tissue was harvested from the abdomen and injected into the trapeziometacarpal (TMC) joint under radiological guidance, followed by one week of immobilization. Patients with a minimum three-year post-procedure period were assessed for pain level (numerical rating scale), quality of life (Mental Health Quotient (MHQ)), the abbreviated version of the Disabilities of Arm, Shoulder and Hand questionnaire (QuickDASH)), and grip and pinch strength, as well as their overall impression of the treatment. Wilcoxon tests compared data from pre-intervention, and at one and three years post-intervention. Results. Out of 136 treated joints, the study involved 87 patients (37 patients were loss to follow-up, and 12 patients (9%) who underwent resection arthroplasty) with a median follow-up of 4.9 years (IQR 5.4 to 5.9). Pain, both at rest and during stress, significantly improved at one year and remained stable through three years. Sex, age, and stage of disease were not associated with postoperative pain levels. Patient-reported outcome measures for QuickDASH and MHQ improved up to at least three years post-treatment. Patients reported high satisfaction and willingness to recommend the procedure. Grip and pinch strength did not significantly change over time. Conclusion. The data show that autologous fat transfer has a longer-lasting effect in two-thirds of re-examined patients. If patients had an initial positive response, the pain-reducing effect lasted for at least three years. Therefore, this minimally invasive approach can offer a valuable treatment alternative for basal thumb OA

Aims

Extracellular matrix (ECM) is a critical determinant of tissue mechanobiology, yet remains poorly characterized in joint tissues beyond cartilage in osteoarthritis (OA). This review aimed to define the composition and architecture of non-cartilage soft joint tissue structural ECM in human OA, and to compare the changes observed in humans with those seen in animal models of the disease.

The December 2024 Wrist & Hand Roundup³⁶⁰ looks at: Variability in thumb ulnar collateral ligament rupture management across the UK: survey insights; Identifying five distinct hand osteoarthritis pain phenotypes highlights the impact of biopsychosocial factors; Long-term outcomes of MAÏA TMC joint prosthesis for osteoarthritis: a possible alternative to trapeziectomy; Diagnostic and management strategies for malignant melanoma of the hand; Early versus delayed surgery for distal radius fractures: comparable outcomes but higher complications in delayed treatment; Perioperative anticoagulant and antiplatelet use does not increase complications in wide-awake hand surgery; Variability in treatment of metacarpal shaft fractures highlights need for standardized care; Low-intensity pulsed ultrasound ineffective in reducing time to union for scaphoid nonunion post-surgery.

The December 2024 Knee Roundup³⁶⁰ looks at: Unicompartmental knee arthroplasty and total knee arthroplasty in the same patient?; Lateral unicompartmental knee arthroplasty: is it a good option?; The fate of the unresurfaced patellae in contemporary total knee arthroplasty: early- to mid-term results; Tibial baseplate migration is not associated with change in PROMs and clinical scores after total knee arthroplasty; Unexpected positive intraoperative cultures in aseptic revision knee arthroplasty: what effect does this have?; Kinematic or mechanical alignment in total knee arthroplasty surgery?; Revision total knee arthroplasty achieves minimal clinically important difference faster than primary total knee arthroplasty; Outcomes after successful DAIR for periprosthetic joint infection in total knee arthroplasty.

Aims. Lower limb reconstruction (LLR) has a profound impact on patients, affecting multiple areas of their lives. Many patient-reported outcome measures (PROMs) are employed to assess these impacts; however, there are concerns that they do not adequately capture all outcomes important to patients, and may lack content validity in this context. This review explored whether PROMs used with adults requiring, undergoing, or after undergoing LLR exhibited content validity and adequately captured outcomes considered relevant and important to patients. Methods. A total of 37 PROMs were identified. Systematic searches were performed to retrieve content validity studies in the adult LLR population, and hand-searches used to find PROM development studies. Content validity assessments for each measure were performed following Consensus-based Standards for the selection of health measurement Instruments (COSMIN) guidelines. A mapping exercise compared all PROMs to a conceptual framework previously developed by the study team (‘the PROLLIT framework’) to explore whether each PROM covered important and relevant concepts. Results. The systematic searches found 13 studies, while hand searches found 50 PROM development studies, and copies of all 37 measures. Although several studies discussed content validity, none were found which formally assessed this measurement property in the adult LLR population. Development of many PROMs was rated as inadequate, no PROM had sufficient content validity in the study population, and none covered all areas of the PROLLIT framework. The LIMB-Q was the most promising and comprehensive measure assessed, although further validation in a wider sample of LLR patients was recommended. Conclusion. Current PROMs used in adults requiring, undergoing, or after undergoing LLR lack content validity and do not assess all important and relevant outcomes. There is an urgent need for improved outcome measurement in this population. This can be achieved through development of a new PROM, or through validation of existing measures in representative samples. Cite this article: Bone Jt Open 2024;5(12):1049–1066

The December 2024 Research Roundup³⁶⁰ looks at: Skeletal muscle composition, power, and mitochondrial energetics in older men and women with knee osteoarthritis; Machine-learning models to predict osteonecrosis in patients with femoral neck fractures undergoing internal fixation; Aetiology of patient dissatisfaction following primary total knee arthroplasty in the era of robotic-assisted technology; Efficacy and safety of commonly used thromboprophylaxis agents following hip and knee arthroplasty; The COVID-19 effect continues; Nickel allergy in knee arthroplasty: does self-reported sensitivity affect outcomes?; Tranexamic acid use and joint infection risk in total hip and knee arthroplasty.

Aims. Approximately 10% to 20% of knee arthroplasty patients are not satisfied with the result, while a clear indication for revision surgery might not be present. Therapeutic options for these patients, who often lack adequate quadriceps strength, are limited. Therefore, the primary aim of this study was to evaluate the clinical effect of a novel rehabilitation protocol that combines low-load resistance training (LL-RT) with blood flow restriction (BFR). Methods. Between May 2022 and March 2024, we enrolled 45 dissatisfied knee arthroplasty patients who lacked any clear indication for revision to this prospective cohort study. All patients were at least six months post-surgery and had undergone conventional physiotherapy previously. The patients participated in a supervised LL-RT combined with BFR in 18 sessions. Primary assessments included the following patient-reported outcome measures (PROMs): Knee injury and Osteoarthritis Outcome Score (KOOS); Knee Society Score: satisfaction (KSSs); the EuroQol five-dimension five-level questionnaire (EQ-5D-5L); and the pain catastrophizing scale (PCS). Functionality was assessed using the six-minute walk Test (6MWT) and the 30-second chair stand test (30CST). Follow-up timepoints were at baseline, six weeks, three months, and six months after the start. Results. Six weeks of BFR with LL-RT improved all the PROMs except the sports subscale of the KOOS compared to baseline. Highest improvements after six weeks were found for quality of life (QoL) (mean 28.2 (SD 17.2) vs 19 (SD 14.7); p = 0.002), activities of daily living (mean 54.7 (SD 18.7) vs 42.9 (SD 17.3); p < 0.001), and KSSs (mean 17.1 (SD 8.8) vs 12.8 (SD 6.7); p < 0.001). PROMs improvements continued to be present at three-month and six-month follow-up compared to baseline. However, no significant differences were observed in the paired comparisons of the six-week, three-month, and six-month follow-up. The same trends are observed for the 6MWT and 30CST. Conclusion. The reported regime demonstrates improved QoL and function of dissatisfied knee arthroplasty patients. In light of this, the pathway described may provide a valuable and safe treatment option for dissatisfied knee arthroplasty patients for whom therapeutic options are limited. Cite this article: Bone Joint J 2024;106-B(12):1416–1425

In the UK, multidisciplinary teamwork for patients with hip fracture has been shown to reduce mortality and improves health-related quality of life for patients, while also reducing hospital bed days and associated healthcare costs. However, despite rapidly increasing numbers of fragility fractures, multidisciplinary shared care is rare in low- and middle-income countries around the world. The HIPCARE trial will test the introduction of multidisciplinary care pathways in five low- and middle-income countries in South and Southeast Asia, with the aim to improve patients’ quality of life and reduce healthcare costs.

Cite this article: Bone Joint J 2024;106-B(12):1369–1371.

Aims. A recent study used the RAND Corporation at University of California, Los Angeles (RAND/UCLA) method to develop anatomical total shoulder arthroplasty (aTSA) appropriateness criteria. The purpose of our study was to determine how patient-reported outcome measures (PROMs) vary based on appropriateness. Methods. Clinical data from a multicentre database identified patients who underwent primary aTSA from November 2004 to January 2023. A total of 390 patients (mean follow-up 48.1 months (SD 42.0)) were included: 97 (24.9%) were classified as appropriate, 218 (55.9%) inconclusive, and 75 (19.2%) inappropriate. Patients were classified as “appropriate”, “inconclusive”, or “inappropriate”, using a modified version of an appropriateness algorithm, which accounted for age, rotator cuff status, mobility, symptomatology, and Walch classification. Multiple pre- and postoperative scores were analyzed using Pearson’s chi-squared test and one-way analysis of variance (ANOVA). Postoperative complications were also analyzed. Results. All groups achieved significant improvement in mean PROM scores postoperatively. “Appropriate” patients experienced significantly greater improvement in visual analogue scale (VAS) and American Shoulder and Elbow Surgeons (ASES) score compared to “inconclusive” and “inappropriate”. The appropriate group had a significantly greater proportion of patients who achieved minimal clinically important difference (MCID) (95.8%; n = 93) and substantial clinical benefit (SCB) (92.6%; n = 89). Overall, 13 patients had postoperative complications. No significant differences in postoperative complications among classifications were found. Conclusion. Our data clinically validate the RAND/UCLA aTSA appropriateness criteria algorithm, allowing for more rapid and reliable determination of aTSA candidacy. “Appropriate” patients were more likely to achieve MCID and SCB for ASES scores compared to “inappropriate” patients. Among “appropriate” patients who did not achieve SCB, 50% (n = 4) had a postoperative complication. There was a significantly higher proportion of postoperative complications among those who did not achieve SCB across all three groups. Only 7.1% (n = 1) of patients who did not achieve SCB in the inappropriate group had a postoperative complication. Thus, it can be inferred that the failure to reach SCB in the appropriate group was likely to be due to a postoperative complication, whereas for patients deemed “inappropriate”, failure to reach SCB may be secondary to factors accounted for within our algorithm. Cite this article: Bone Joint J 2024;106-B(12):1451–1460

Aims. Day-case knee and hip replacement, in which patients are discharged on the day of surgery, has been gaining popularity during the last two decades, and particularly since the COVID-19 pandemic. This systematic review presents the evidence comparing day-case to inpatient-stay surgery. Methods. A systematic literature search was performed of MEDLINE, Embase, and grey literature databases to include all studies which compare day-case with inpatient knee and hip replacement. Meta-analyses were performed where appropriate using a random effects model. The protocol was registered prospectively (PROSPERO CRD42023392811). Results. A total of 38 studies were included, with a total of 83,888 day-case procedures. The studies were predominantly from the USA and Canada, observational, and with a high risk of bias. Day-case patients were a mean of 2.08 years younger (95% CI 1.05 to 3.12), were more likely to be male (odds ratio (OR) 1.3 (95% CI 1.19 to 1.41)), and had a lower mean BMI and American Society of Anesthesiologists grades compared with inpatients. Overall, day-case surgery was associated with significantly lower odds of readmission (OR 0.83 (95% CI 0.73 to 0.96); p = 0.009), subsequent emergency department attendance (OR 0.62 (95% CI 0.48 to 0.79); p < 0.001), and complications (OR 0.7 (95% CI 0.55 to 0.89) p = 0.004), than inpatient surgery. There were no significant differences in the rates of reoperation or mortality. The overall rate of successful same-day discharge for day-case surgery was 85% (95% CI 81 to 88). Patient-reported outcome measures and cost-effectiveness were either equal or favoured day-case. Conclusion. Within the limitations of the literature, in particular the substantial risk of selection bias, the outcomes following day-case knee and hip replacement appear not to be inferior to those following an inpatient stay. The evidence is more robust for unicompartmental knee replacement (UKR) than for total knee replacement (TKR) or total hip replacement (THR). The rate of successful same-day discharge is highest in UKR, followed by TKR and comparatively lower in THR. Cite this article: Bone Joint J 2024;106-B(12):1385–1392

The December 2024 Shoulder & Elbow Roundup³⁶⁰ looks at: Predicting recurrence of instability after a primary traumatic anterior shoulder dislocation; Predictors of surgery and long-term outcomes in nonoperative management of full-thickness rotator cuff tears; Reverse shoulder arthroplasty viable despite acquired acromial compromise, but higher infection risk noted; LP-PRP reduces retear rates in rotator cuff repair but shows no functional outcome advantage; Long-term clinical outcomes of arthroscopic supraspinatus tendon repair using the single anchor tension band technique – minimum five-year follow-up; Arthroscopic stabilization for anterior shoulder dislocation shows low recurrence rates regardless of prior dislocations; ORIF outperforms arthroplasty for complex radial head fractures: mid-term outcomes; Routine use of surgical helmet systems may not reduce infection risk in shoulder arthroplasty.

The December 2024 Foot & Ankle Roundup³⁶⁰ looks at: Tibiotalar sector and lateral ankle instability; Isolated subtalar fusion and correction of progressive collapsing foot deformity; Diabetic control and postoperative complications following ankle fracture fixation; Are insoles of any benefit for plantar fasciitis?; Postoperative foot shape and patient-reported outcome following surgery for progressing collapsing foot deformity; Calcaneo-stop procedure for symptomatic flexible flatfoot in children.

Aims. Calcaneal osteomyelitis remains a difficult condition to treat with high rates of recurrence and below-knee amputation, particularly in the presence of severe soft-tissue destruction. This study assesses the outcomes of single-stage orthoplastic surgical treatment of calcaneal osteomyelitis with large soft-tissue defects. Methods. A retrospective review was performed of all patients who underwent combined single-stage orthoplastic treatment of calcaneal osteomyelitis (01/2008 to 12/2022). Primary outcome measures were osteomyelitis recurrence and below-knee amputation (BKA). Secondary outcome measures included flap failure, operating time, complications, and length of stay. Results. A total of 30 patients (14 female, 16 male; mean age 53.7 years (95% CI 48.0 to 59.5)) underwent combined orthoplastic surgical treatment for BACH “complex” calcaneal osteomyelitis with a median follow-up of 31 months (IQR 11.75 to 49.25). Of these, 19 received a local flap and 11 received a free flap. The most common causes were fracture-related infection (n = 12; 40%) and ulceration (n = 10; 33%); 21 patients (70%) had already undergone at least one operation elsewhere. Osteomyelitis was eradicated in 23 patients (77%). There were seven patients who developed recurrent osteomyelitis (23%), all in the local flap group. One patient required a BKA. Univariate analysis revealed that local flap reconstruction (OR 13.5 (95% CI 0.7 to 269.7); p = 0.029) and peripheral vascular disease (OR 16.5 (95% CI 1.35 to 203.1); p = 0.008) were associated with increased risk of recurrence. Free flap reconstruction took significantly longer intraoperatively than local flaps (mean 481 minutes (408 to 554) vs mean 168 minutes (119 to 216); p < 0.001), but without significant differences in length of stay or frequency of outpatient appointments. Conclusion. In our study involving 30 patients, single-stage orthoplastic management was associated with 77% (n = 23) eradication of infection and only one amputation in this complex and comorbid patient group. Risk factors for failure were peripheral vascular disease and local flap reconstruction. While good outcomes can be achieved, this treatment requires high levels of inpatient and outpatient care. Cite this article: Bone Joint J 2024;106-B(12):1443–1450

The December 2024 Hip & Pelvis Roundup³⁶⁰ looks at: Total hip arthroplasty after femoral neck fractures versus osteoarthritis at one-year follow-up: a comparative, retrospective study; Excellent mid-term survival of a monoblock conical prosthesis in treating atypical and complex femoral anatomy with total hip arthroplasty; Hip arthroscopy for femoroacetabular impingement improves sexual function; Fast-track hip arthroplasty does not increase complication rates; Ten-year experience with same-day discharge outpatient total hip arthroplasty: patient demographics changed, but safe outcomes were maintained.

Aims. There has been limited literature regarding outcomes of acetabular rim syndrome (ARS) with persistent acetabular os in the setting of acetabular dysplasia. The purpose of this study was to characterize a cohort of adolescent and young adult patients with ARS with persistent os and compare their radiological and clinical outcomes to patients with acetabular dysplasia without an os. Methods. We reviewed a prospective database of patients undergoing periacetabular osteotomy (PAO) for symptomatic acetabular dysplasia between January 1999 and December 2021 to identify hips with preoperative os acetabuli, defined as a closed triradiate cartilage but persistence of a superolateral os acetabulum. A total of 14 hips in 12 patients with persistent os acetabuli (ARS cohort) were compared to 50 randomly selected ‘control’ hips without persistent os acetabuli. Preoperative and postoperative radiographs were measured for markers of dysplasia: lateral centre-edge angle, anterior centre-edge angle, acetabular inclination, and migration index. Union of the os was determined in patients with ≥ six months’ follow-up. Patient-reported outcome measures (PROMs) included the University of California, Los Angeles (UCLA) activity score and modified Harris Hip Score (mHHS, maximum score 80) completed at one year postoperatively. Results. There was no significant difference between the ARS and control cohorts with regard to sex distribution (p = 0.270), age at surgery (p = 0.186), or BMI (p = 0.442). Preoperatively, the ARS cohort had more severe dysplasia, including lower lateral centre-edge angle (-9.3° (SD 12.5°) vs 7.6° (SD 10.7°); p < 0.001) and greater acetabular inclination (33.9° (SD 8.2°) vs 21.8° (SD 8.7°); p < 0.001). Postoperatively, 6/13 (46%) hips with ≥ six months of radiological follow up demonstrated union of the os. There was no difference between the ARS and control cohorts at one year in UCLA score (9.1 (SD 1.5) vs 8.2 (SD 1.9); p = 0.167) or mHHS (73.4 (SD 9.5) vs 69.9 (SD 8.8); p = 0.312). Conclusion. ARS with persistent acetabular os may occur in more severe dysplasia. Union occurs in 50% cases following corrective PAO. Cite this article: Bone Joint J 2024;106-B(12):1393–1398

Aim. Periprosthetic joint infection (PJI) is a complication of total joint arthroplasty that typically requires revision surgery for treatment. Systemic antibiotics are usually held prior to surgery to improve yield of intraoperative cultures. However, recent studies suggest that preoperative aspirations have a high concordance with intraoperative cultures, which may allow surgeons to initiate antibiotic treatment earlier. The purpose of the study was to investigate the effect of Pre-surgical systemic antibiotic therapy on the bacterial burden within the periprosthetic space and systemic immune reaction. Method. PJI was induced with MSSA (Xen36) S. aureus in the right knee of 16-week old, female, C57BL6 mice using a previously validated murine model. Mice were randomized to three groups (n=8, each): control; Vanc, receiving systemic vancomycin (110mg/kg, SQ, twice daily); or VancRif receiving vancomycin same as in Vanc group, plus rifampin (12mg/kg dose, IV, once daily). Following 2 weeks of treatment, mice were euthanized and periprosthetic bone, soft tissue and the implant were harvested. Bacterial burden, colony forming units (CFUs), was quantified in soft tissue, tibial bone, and on the implant. Specifically, tissues were homogenized and serially plated for CFUs, while the implant was sonicated and then plated for CFUs. The host immune response was analysed through weighing inguinal and iliac lymph nodes and through measuring serum amyloid A (SAA). Non-parametric pairwise group comparisons of the three outcome measures were performed using a Mann-Whitney U test. Results. VancRif, the combined treatment significantly reduced bacterial burden in the periprosthetic soft tissue, bone, and implant compared to control (p<0.001) and Vanc alone (p<0.001). While not significant, Vanc alone did reduce bacterial load as compared to control. The ipsilateral weight of the iliac lymph nodes was significantly reduced in Vanc and VancRif mice compared to controls (p<0.001), was well as in VancRif versus Vanc alone (p<0.001). Interestingly, SAA levels did not significantly differ among all groups. During tissue harvesting, minimal purulence was observed in antibiotic treatment groups, unlike controls. Conclusions. Treating active PJI with vancomycin alone decreases periprosthetic bacterial loads and reduces the local immunological response. This effect is significantly enhanced with the combined rifampin use. These findings could suggest that when culture positive PJI is diagnosed, pre-surgical treatment with antibiotics may decrease immunosuppression and soft tissue infiltration, leading to a better chance of infection cure with subsequent surgical debridement. Histological investigations and repeat experiments involving subsequent surgical treatment are underway. Acknowledgements. Funding comes from internal institutional grants