Ben Kendrick's research while affiliated with Cancer Research UK Oxford Centre and other places

There is a paucity of data available for the use of Total Femoral Arthroplasty (TFA) for joint reconstruction in the non-oncological setting. The aim of this study was to evaluate TFA outcomes with minimum 5-year follow-up. This was a retrospective database study of TFAs performed at a UK tertiary referral revision arthroplasty unit. Inclusion criteria were patients undergoing TFA for non-oncological indications. We report demographics, indications for TFA, implant survivorship, clinical outcomes, and indications for re-operation. A total of 39 TFAs were performed in 38 patients between 2015–2018 (median age 68 years, IQR 17, range 46–86), with 5.3 years’ (IQR 1.2, 4.1–18.8) follow-up; 3 patients had died. The most common indication (30/39, 77%) for TFA was periprosthetic joint infection (PJI) or fracture-related infection (FRI); and 23/39 (59%) had a prior periprosthetic fracture (PPF). TFA was performed with dual-mobility or constrained cups in 31/39 (79%) patients. Within the cohort, 12 TFAs (31%) required subsequent revision surgery: infection (7 TFAs, 18%) and instability (5 TFAs, 13%) were the most common indications. 90% of patients were ambulatory post-TFA; 2 patients required disarticulation due to recurrent PJI. While 31/39 (79%) were infection free at last follow-up, the remainder required long-term suppressive antibiotics. This is the largest series of TFA for non-oncological indications. Though TFA has inherent risks of instability and infection, most patients are ambulant after surgery. Patients should be counselled on the risk of life-long antibiotics, or disarticulation when TFA fails.

Background Limb-salvage surgery involving the utilization of endoprosthetic replacements is commonly employed following segmental bone resection for primary and secondary bone tumors. This study aimed to evaluate whether a fully porous bridging collar promotes early osseous integration in endoprosthetic replacements. Methods We undertook a retrospective review of all lower-limb endoprostheses utilizing a fully porous endosteal bridging collar design. We matched this cohort with a conventional extra-osteal non-porous fully hydroxyapatite-coated grooved collar cohort according to surgical indication, implant type, resection length, age, and follow-up time. At 6, 12, and 24 months post-implantation, radiographs were assessed for the number of cortices with or without osseointegration on orthogonal radiographs. Each radiograph was scored on a scale of -4 to + 4 for the number of cortices bridging the ongrowth between the bone and the collar of the prosthesis. Implant survival was estimated using the Kaplan–Meier method, and the mean number of osseointegrated cortices at each time point between the collar designs was compared using a paired t-test. Results Ninety patients were retrospectively identified and analyzed. After exclusion, 40 patients with porous bridging collars matched with 40 patients with conventional extra-osteal non-porous collars were included in the study (n = 80). The mean age was 63.4 years (range 16–91 years); there were 37 males and 43 females. The groups showed no difference in implant survival (P = 0.54). The mean number of cortices with radiographic ongrowth for the porous bridging collar and non-porous collar groups was 2.1 and 0.3, respectively, at 6-month (P < 0.0001), 2.4 and 0.5, respectively, at 12-month (P = 0.044), and 3.2 and -0.2, respectively, at 24-month (P = 0.18) radiological follow-up. Conclusion These findings indicate that fully porous bridging collars increased the number of cortices, with evidence of bone ongrowth between 6 and 24 months post-implantation. By contrast, extra-osteal collars exhibited reduced evidence of ongrowth between 6 and 24 months post-implantation. In the medium term, the use of a fully porous bridging collar may translate to a reduced incidence of aseptic loosening. Graphical Abstract

Introduction A proportion of patients with hip and knee prosthetic joint infection (PJI) undergo multiple revisions with the aim of eradicating infection and improving quality of life. The aim of this study was to describe the microbiology cultured from multiply revised hip and knee replacement procedures to guide antimicrobial therapy at the time of surgery. Patients and Methods Consecutive patients were retrospectively identified from databases at two specialist orthopaedic centres in the United Kingdom between 2011 and 2019. Patient were included who had undergone repeat revision total knee replacement (TKR) or total hip replacement (THR) for infection, following an initial failed revision for infection. Results 106 patients were identified, of which 74 underwent revision TKR and 32 underwent revision THR. Mean age at first revision was 67 years (SD 10). Charlson Comorbidity Index was <2 for 31 patients, 3–4 for 57 patients, and >5 for 18 patients. All patients underwent >2 revisions, 73 patients received 3, 47 patients received 4, 31 patients received 5, and 21 patients received >6. After six revisions, 90% of patients cultured different organisms than the initial revision, and 53% of organisms were multi-drug resistant species. The most frequent organisms at each revision were coagulase negative Staphylococcus (36%) and Staphylococcus aureus (19%). Fungus was cultured from 3% of revisions and 21% of infections were polymicrobial. Conclusion Patients undergoing multiple revisions for PJI are highly likely to experience a change in organisms and sensitivities with each subsequent revision. It is important to administer empirical antibiotics at each subsequent revision, appreciating known drug resistance from previous cultures. Our results do not support routine use of empirical antifungals.

Aims Aseptic loosening is the most common cause of failure following cemented total knee arthroplasty (TKA), and has been linked to poor cementation technique. We aimed to develop a consensus on the optimal technique for component cementation in TKA. Methods A UK-based, three-round, online modified Delphi Expert Consensus Study was completed focusing on cementation technique in TKA. Experts were identified as having a minimum of five years’ consultant experience in the NHS and fulfilling any one of the following criteria: a ‘high volume’ knee arthroplasty practice (> 150 TKAs per annum) as identified from the National joint Registry of England, Wales, Northern Ireland and the Isle of Man; a senior author of at least five peer reviewed articles related to TKA in the previous five years; a surgeon who is named trainer for a post-certificate of comletion of training fellowship in TKA. Results In total, 81 experts (round 1) and 80 experts (round 2 and 3) completed the Delphi Study. Four domains with a total of 24 statements were identified. 100% consensus was reached within the cement preparation, pressurization, and cement curing domains. 90% consensus was reached within the cement application domain. Consensus was not reached with only one statement regarding the handling of cement during initial application to the tibial and/or femoral bone surfaces. Conclusion The Cementing Techniques In Knee Surgery (CeTIKS) Delphi consensus study presents comprehensive recommendations on the optimal technique for component cementing in TKA. Expert opinion has a place in the hierarchy of evidence and, until better evidence is available these recommendations should be considered when cementing a TKA. Cite this article: Bone Jt Open 2023;4(9):682–688.

Primary total hip replacement (THR) is a successful and common operation which orthopaedic trainees must demonstrate competence in prior to completion of training. This study aimed to determine the impact of operating surgeon grade and level of supervision on the incidence of 1-year patient mortality and all-cause revision following elective primary THR in a large UK training centre. National Joint Registry (NJR) data for all elective primary THR performed in a single University Teaching Hospital from 2005–2020 were used, with analysis performed on the 15-year dataset divided into 5-year temporal periods (B1 2005–2010, B2 2010–2015, B3 2015–2020). Outcome measures were mortality and revision surgery at one year, in relation to lead surgeon grade, and level of supervision for trainee-led operations. 9999 eligible primary THR were undertaken, of which 5526 (55.3%) were consultant led (CL), and 4473 (44.7%) trainees led (TL). Of TL, 2404 (53.7%) were non-consultant supervised (TU), and 2069 (46.3%) consultant supervised (TS). The incidence of 1-year patient mortality was 2.05% (n=205), and all-cause revision was 1.11% (n=111). There was no difference in 1-year mortality between TL (n=82, 1.8%) and CL (n=123, 2.2%) operations (p=0.20, OR 0.78, CI 0.55–1.10). The incidence of 1-year revision was not different for TL (n=56, 1.3%) and CL (n=55, 1.0%) operations (p=0.15, OR 1.37, CI 0.89–2.09). Overall, there was no temporal change for either outcome measure between TL or CL operations. A significant increase in revision within 1-year was observed in B3 between TU (n=17, 2.7%) compared to CL (n=17, 1.0%) operations (p=0.005, OR 2.81, CI 1.35–5.87). We found no difference in 1-year mortality or 1-year all-cause revision rate between trainee-led primary THR and consultant-led operations over the entire fifteen-year period. However, unsupervised trainee led THR in the most recent 5-year block (2015–2020) has a significantly increased risk of early revision, mainly due to instability and prosthetic joint infection. This suggests that modern surgical training is having a detrimental effect on THR patient outcomes. More research is needed to understand the reasons if this trend is to be reversed.

Introduction: Limb-salvage surgery using endoprosthetic replacements (EPRs) is frequently used to reconstruct segmental bone defects, but the reconstruction longevity is still a major concern. In EPRs, the stem-collar junction is the most critical region for bone resorption. We hypothesised that an in-lay collar would be more likely to promote bone ongrowth in Proximal Femur Reconstruction (PFR), and we tested this hypothesis through validated Finite Element (FE) analyses simulating the maximum load during walking. Methods: We simulated three different femur reconstruction lengths (proximal, mid-diaphyseal, and distal). For each reconstruction length one in-lay and one traditional on-lay collar model was built and compared. All reconstructions were virtually implanted in a population-average femur. Personalised Finite Element models were built from Computed Tomography for the intact case and for all reconstruction cases, including contact interfaces where appropriate. We compared the mechanical environment in the in-lay and on-lay collar configurations, through metrics of reconstruction safety, osseointegration potential, and risk of long-term bone resorption due to stress-shielding. Results: In all models, differences with respect to intact conditions were localized at the inner bone-implant interface, being more marked in the collar-bone interface. In proximal and mid-diaphyseal reconstructions, the in-lay configuration doubled the area in contact at the bone-collar interface with respect to the on-lay configuration, showed less critical values and trends of contact micromotions, and consistently showed higher (roughly double) volume percentages of predicted bone apposition and reduced (up to one-third) percentages of predicted bone resorption. In the most distal reconstruction, results for the in-lay and on-lay configurations were generally similar and showed overall less favourable maps of the bone remodelling tendency. Discussion: In summary, the models corroborate the hypothesis that an in-lay collar, by realising a more uniform load transfer into the bone with a more physiological pattern, creates an advantageous mechanical environment at the bone-collar interface, compared to an on-lay design. Therefore, it could significantly increase the survivorship of endo-prosthetic replacements.

Background: Fungal infections are a rare cause of periprosthetic joint infection (PJI), identified in 1% of all of these cases. Outcomes are not well-established due to small cohort sizes in the published literature. The aims of this study were to establish the patient demographics and infection-free survival of patients presenting to two high volume revision arthroplasty centers who had fungal infection of either a hip or knee arthroplasty. We sought to identify risk factors for poor outcomes. Methods: A retrospective analysis was performed of patients at two high volume revision arthroplasty centers who had confirmed fungal PJI of the total hip arthroplasty (THA) and total knee arthroplasty (TKA). Consecutive patients treated between 2010 and 2019 were included. Patient outcomes were classified as infection eradication or persistence. A total of 67 patients who had 69 fungal PJI cases were identified. There were 47 cases involving the knee and 22 of the hip. Mean age at presentation was 68 years (THA mean 67, range 46 to 86) (TKA mean 69, range, 45 to 88). A history of sinus or open woundwas present in 60 cases (89%)(THA 21 cases, TKA 39 cases). The median number of operations prior to the procedure at which fungal PJI was identified was 4 (range, 0 to 9)(THA 5 (range, 3 to 9) and TKA 3 (range, 0 to 9). Results: At mean follow up 34 months (range, 2 to 121), remission rates were 11 of 24 (45%) and 22 of 45 (49%) for hip and knee, respectively. There were seven TKA (16%) and one THA (4%) who failed treatment resulting in amputations. During the study period, seven THA and six TKA patients had died. Two deaths were directly attributable to PJI. Patient outcome was not associated with the number of prior procedures, patient comorbidities, or organisms. Conclusion: Eradication of fungal PJI is achieved in less than half of patients, and outcomes are comparable for TKA and THA. The majority of patients who have fungal PJI present with an open wound or sinus. No factors were identified that increase the risk of persistent infection. Patients who have fungal PJI should be informed of the poor outcomes.

Introduction Accurate acetabular cup and femoral stem component orientation are critical for optimising patient outcomes, reducing complications and increasing component longevity following total hip replacement (THR). This study aimed to determine the accuracy of a novel virtual reality (VR) platform in assessing component orientation in a simulated THR model. Methods The VR platform (HTC Vive Pro® system hardware) was compared against the validated Vicon® optical motion capture (MoCap) system. An acetabular cup and femoral stem were manually implanted across a range of orientations into pelvic and femur sawbones, respectively. Simultaneous readings of the acetabular cup operative anteversion (OA) and inclination (OI) and femoral stem alignment (FSA) and neck anteversion (FNA) were obtained from the VR and MoCap systems. Statistical analysis was performed using Pearson product-moment correlation coefficient (PPMCC) (Pearson’s r) and linear regression (R ² ). Results A total of 55 readings were obtained for the acetabular cup and 68 for the femoral stem model. The mean average differences in OA, OI, FSA and FNA between the systems were 3.44°, −0.01°, 0.01° and −0.04°, respectively. Strong positive correlations were demonstrated between both systems in OA, OI, FSA and FNA, with Pearson’s r = 0.92, 0.94, 0.99 and 0.99, and adjusted R ² = 0.82, 0.9, 0.98 and 0.98, respectively. Conclusion The novel VR platform is highly accurate and reliable in determining both acetabular cup and femoral stem component orientations in simulated THR models. This adaptable and cost-effective digital tracking platform may be modified for use in a range of simulated surgical training and educational purposes, particularly in orthopaedic surgery.

Purpose Unicompartmental knee arthroplasty (UKA) is an effective treatment for late knee osteoarthritis (OA). However, its indications remain controversial. Young age (< 60 years) has been associated with worse outcomes. The goal of this systematic review and meta-analysis is to study the effect of age on UKA outcomes. Methods The primary objective was to compare the UKA revision rate in young patients with that of old patients, using the age thresholds of 60 and 55 years. Secondary objectives were patient-reported outcome measures (PROMs) and implant design. PubMed, Ovid, Web of Science, Google Scholar, and Cochrane library were searched in June 2021. This review was conducted in accordance with the PRISMA guidelines (PROSPERO registration number: CRD42021248322). Results A total of 12 observational studies with 6,448 knees were included. A mean MINORS score of 19 was assigned to the review. The mean age of patients was 64.32 years, with follow-up ranging from 0.2 to 15 years. There was no significant difference in revision rate, incident or PROMs between young and old patients in the analysis for each age threshold. Further sub-analysis adjusting for implant type in mobile- and fixed-bearing prostheses also showed similar results between those above and under 60 and 55 years. Conclusion Young age was not associated with a higher revision rate or lower functional scores. Thus, this review provides evidence that performing UKA at a younger age (< 60 years) should not be considered suboptimal. However, this finding should be applied in context, as other confounding factors need to be explored.