Aims. To compare changes in gait kinematics and walking speed 24 months after conventional (C-MLS) and minimally invasive (MI-MLS) multilevel surgery for children with diplegic cerebral palsy (CP). Methods. A retrospective analysis of 19 children following C-MLS, with mean age at surgery of 12 years five months (seven years ten months to 15 years 11 months), and 36 children following MI-MLS, with mean age at surgery of ten years seven months (seven years one month to 14 years ten months), was performed. The Gait Profile Score (GPS) and walking speed were collected preoperatively and six, 12 and 24 months postoperatively. Type and frequency of procedures as part of MLS, surgical adverse events, and subsequent surgery were recorded. Results. In both groups, GPS improved from the preoperative gait analysis to the six-month assessment with maintenance at 12 and 24 months postoperatively. While reduced at six months in both groups, walking speed returned to preoperative speed by 12 months. The overall pattern of change in GPS and walking speed was similar over time following C-MLS and MI-MLS. There was a median of ten procedures per child as part of both C-MLS (interquartile range (IQR) 8.0 to 11.0) and MI-MLS (IQR 7.8 to 11.0). Surgical adverse events occurred in seven (37%) and 13 (36%) children, with four (21%) and 13 (36%) patients requiring subsequent surgery following C-MLS and MI-MLS, respectively. Conclusion. This study indicates similar improvements in gait kinematics and walking speed 24 months after C-MLS and MI-MLS for children with diplegic CP. Cite this article: Bone Joint J 2021;103-B(1):192–197

Aims. The purpose of this study was to compare the long-term results of primary total hip arthroplasty (THA) in young patients using either a conventional (CPE) or a highly cross-linked (HXLPE) polyethylene liner in terms of functional outcome, incidence of osteolysis, radiological wear and rate of revision. Methods. We included all patients between the ages of 45 and 65 years who, between January 2000 and December 2001, had undergone a primary THA for osteoarthritis at our hospital using a CPE or HXLPE acetabular liner and a 28 mm cobalt-chrome femoral head. . From a total of 160 patients, 158 (177 hips) were available for review (CPE 89; XLPE 88). The mean age, body mass index (BMI) and follow-up in each group were: CPE: 56.8 years (46 to 65); 30.7 kg/m. 2. (19 to 58); 13.2 years (2.1 to 14.7) and HXLPE: 55.6 years (45 to 65); BMI: 30 kg/m. 2. (18 to 51); 13.1 years (5.7 to 14.4). Results. The mean Harris hip score (HHS) at final follow-up was 89.3 for the CPE group and 90.9 for the HXLPE group (p = 0.078). Osteolysis was present around 15 acetabular (17%) and 16 femoral (18%) components in the CPE hips compared with none (0%) in the HXLPE hips. The mean radiological linear wear of the CPE liners was 0.11 mm/year compared with 0.035 mm/year for the HXLPE liners (p = 0.006). The cumulative implant survival, with revision for polyethylene wear as the endpoint, was 86% (95% confidence interval 78 to 94) in the CPE group and 100% in the HXLPE group at 13 years (numbers at risk at 13 years - CPE: 65, XLPE: 61). Discussion. This study shows that HXLPE liners are associated with significantly less osteolysis and a lower rate of revision THA than CPE liners at long-term follow-up. Take home message: The findings of this study highlight the clinical benefits of using HXLPE liners in THA and support the routine use of the material in order to improve implant longevity and to decrease the number of patients needing revision for aseptic osteolysis. . Cite this article: Bone Joint J 2016;98-B:28–32

Abstract. Background. Conventional periacetabular pelvic resections are associated with poor functional outcomes. Resections through surgical corridors beyond the conventional margins may be helpful in retaining greater function without compromising the oncological margins. Methods. The study included a retrospective review of 82 cases of pelvic resections for pelvic tumors. Outcomes of acetabulum preservation (Group A) were compared with complete acetabular resection (Group B). Also, we compared outcomes of Type I+half resections (Group 1) with Type I+II resections (Group 2), and Type III+half resections (Group 3) with Type II+III resections (Group 4). Results. Group A (n=44) had significantly better functional outcome than Group B(n=38) with average MSTS93 score 22.3 vs 20.1 and average HHS 91.3 vs 82.5 (p<0.001). Group 1(n=14) and Group 2(n=12) had similar functional outcomes (mean MSTS93 score 22.07 vs 21.58 (p=0.597) and mean HHS 90.37 vs 86.51 (p=0.205)). Group 3(n=11) had significantly better functional outcome than Group 4(n=17), with mean MSTS93 score 22.8 vs 19.7 (p<0.001) and mean HHS 92.3 vs 80.1 (p<0.001). Oncological outcomes were similar among the groups. Conclusion. Trans-acetabular pelvic resections provide functional benefit over conventional resections without compromising oncological margins. There is a need to revisit and revise the pelvic resection planes

Aims. The aim of this study is to determine the predictors of overall survival (OS) and predictive factors of poor prognosis of conventional high-grade osteosarcoma of the limbs in a single-centre in South Africa. Methods. We performed a retrospective cross-sectional analysis to identify the prognostic factors that predict the OS of patients with histologically confirmed high-grade conventional osteosarcoma of the limbs over ten years. We employed the Cox proportional regression model and the Kaplan-Meier method for statistical analysis. Results. This study comprised 77 patients at a three-year minimum follow-up. The predictors of poor OS were: the median age of ≤ 19 years (hazard ratio (HR) 0.96; 95% confidence interval (CI) 0.92 to 0.99; p = 0.021); median duration of symptoms ≥ five months (HR 0.91; 95% CI 0.83 to 0.99; p < 0.037); metastasis at diagnosis (i.e. Enneking stage III) (HR 3.33; 95% CI 1.81 to 6.00; p < 0.001); increased alkaline phosphatase (HR 3.28; 95% CI 1.33 to 8.11; p < 0.010); palliative treatment (HR 7.27; 95% CI 2.69 to 19.70); p < 0.001); and amputation (HR 3.71; 95% CI 1.12 to 12.25; p < 0.032). In contrast, definitive surgery (HR 0.11; 95% CI 0.03 to 0.38; p < 0.001) and curative treatment (HR 0.18; 95% CI 0.10 to 0.33; p < 0.001) were a protective factor. The Kaplan-Meier median survival time was 24 months, with OS of 57.1% at the three years. The projected five-year event-free survival was 10.3% and OS of 29.8% (HR 0.76; 95% CI 0.52 to 1.12; p = 0.128). Conclusion. In this series of high-grade conventional osteosarcoma of the appendicular skeleton from South Africa, 58.4% (n = 45) had detectable metastases at presentation; hence, an impoverished OS of five years was 29.8%. Large-scale future research is needed to validate our results. Cite this article: Bone Jt Open 2024;5(3):210–217

Aims. This multicentre retrospective observational study’s aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision. Methods. A total of 780 patients (39% male; median age 70.7 years (IQR 62.0 to 77.2)) underwent cemented TKA using the Attune Knee System) at five centres, and with the latest radiograph available for the evaluation of RLL at between six and 36 months from surgery. Univariate and multivariate logistic regression models were performed to assess associations between patient and implant-associated factors on the presence of tibial and femoral RLLs. Differences in revision risk depending on RLLs and tibial baseplate design were investigated with the log-rank test. Results. The conventional and novel Attune baseplates were used in 349 (45%) and 431 (55%) patients, respectively. At a median follow-up of 14 months (IQR 11 to 25), RLLs were present in 29% (n = 228/777) and 15% (n = 116/776) of the tibial and femoral components, respectively, and were more common in the conventional compared to the novel baseplate. The novel baseplate was independently associated with a lower incidence of tibial and femoral RLLs (both regardless of age, sex, BMI, and time to radiograph). One- and three-year revision risk was 1% (95% CI 0.4% to 1.9%)and 6% (95% CI 2.6% to 13.2%), respectively. There was no difference between baseplate design and the presence of RLLs on the the risk of revision at short-term follow-up. Conclusion. The overall incidence of RLLs, as well as the incidence of tibial and femoral RLLs, was lower with the novel compared to the conventional tibial Attune baseplate design, but higher than in the predecessor design and other commonly used TKA systems. Cite this article: Bone Joint J 2024;106-B(11):1240–1248

To date, the literature has not yet revealed superiority of Minimally Invasive (MI) approaches over conventional techniques. We performed a systematic review to determine whether minimally invasive approaches are superior to conventional approaches in total hip arthroplasty for (1) clinical and (2) functional outcomes. We performed a meta-analysis of level 1 evidence to determine whether (3) minimally invasive approaches are superior to conventional approaches for clinical outcomes. All studies comparing MI approaches to conventional approaches were eligible for analysis. The PRISMA guidelines were adhered to throughout this study. Registries were searched using the following MeSH terms: ‘minimally invasive’, ‘muscle-sparing’, ‘THA’, ‘THR’, ‘hip arthroplasty’ and ‘hip replacement’. Locations searched included PubMed, the Cochrane Library, ClinicalTrials.gov, the EU clinical trials register and the International Clinical Trials Registry Platform (World Health Organisation). Twenty studies were identified. There were 1,282 MI THAs and 1,351 conventional THAs performed. (1). There was no difference between MI and conventional approaches for all clinical outcomes of relevance including all-cause revision (p=0.959), aseptic revision (p=0.894), instability (p=0.894), infection (p=0.669) and periprosthetic fracture (p=0.940). (2). There was also no difference in functional outcome at early or intermediate follow-up between the two groups (p=0.38). (3). In level I studies exclusively, random-effects meta-analysis demonstrated no difference in the rate of aseptic revision (p=0.461) between both groups. Intermuscular MI approaches are equivalent to conventional THA approaches when considering all-cause revision, aseptic revision, infection, dislocation, fracture rates and functional outcomes. Meta-analysis of level 1 evidence supports this claim

Introduction. Robotic-assisted total knee arthroplasty (TKA) has demonstrated significant benefits, including improved accuracy of component positioning compared to conventional jig-based TKA. However, previous studies have often failed to associate these findings with clinically significant improvements in patient-reported outcome measures (PROMs). Inertial measurement units (IMUs) provide a more nuanced assessment of a patient's functional recovery after TKA. This study aims to compare outcomes of patients undergoing robotic-assisted and conventional TKA in the early postoperative period using conventional PROMS and wearable sensors. Method. 100 patients with symptomatic end-stage knee osteoarthritis undergoing primary TKA were included in this study (44 robotic-assisted TKA and 56 conventional TKA). Functional outcomes were assessed using ankle-worn IMUs and PROMs. IMU- based outcomes included impact load, impact asymmetry, maximum knee flexion angle, and bone stimulus. PROMs, including Oxford Knee Score (OKS), EuroQol-Five Dimension (EQ-5D-5L), EuroQol Visual Analogue Scale (EQ-VAS), and Forgotten Joint Score (FJS-12) were evaluated at preoperative baseline, weeks 2 to 6 postoperatively, and at 3-month postoperative follow-up. Results. By postoperative week 6, when compared to conventional TKA, robotic-assisted TKA was associated with significant improvements in maximum knee flexion angle (118o ± 6.6 vs. 113o ± 5.4; p=0.04), symmetrical loading of limbs (82.3% vs.22.4%; p<0.01), cumulative impact load (146.6% vs 37%; p<0.01), and bone stimulus (25.1% vs 13.6%; p<0.01). Whilst there were no significant differences in PROMs (OKS, EQ-5D-5L, EQ-VAS, and FJS-12) at any time point between the two groups, when comparing OKS subscales, significantly more robotic-assisted TKA patients achieved an ‘excellent’ outcome at 6 weeks compared to conventional (47% vs 41%, p= 0.013). Conclusions. IMU-based metrics detected an earlier return to function among patients that underwent robotic-assisted TKA compared to conventional TKA that PROMs were unable to detect within the first six weeks of surgery

Introduction. Tendon ruptures are a common injury and often require surgical intervention to heal. A refixation is commonly performed with high-strength suture material. However, slipping of the thread is unavoidable even at 7 knots potentially leading to reduced compression of the sutured tendon at its footprint. This study aimed to evaluate the biomechanical properties and effectiveness of a novel dynamic high-strength suture, featuring self-tightening properties. Method. Distal biceps tendon rupture tenotomies and subsequent repairs were performed in sixteen paired human forearms using either conventional or the novel dynamic high-strength sutures in a paired design. Each tendon repair utilized an intramedullary biceps button for radial fixation. Biomechanical testing aimed to simulate an aggressive postoperative rehabilitation protocol stressing the repaired constructs. For that purpose, each specimen underwent in nine sequential days a daily mobilization over 300 cycles under 0-50 N loading, followed by a final destructive test. Result. After the ninth day of cyclic loading, specimens treated with the dynamic suture exhibited significantly less tendon elongation at both proximal and distal measurement sites (-0.569±2.734 mm and 0.681±1.871 mm) compared to the conventional suture group (4.506±2.169 mm and 3.575±1.716 mm), p=0.003/p<0.002. Gap formation at the bone-tendon interface was significantly lower following suturing using dynamic suture (2.0±1.6 mm) compared to conventional suture (4.5±2.2 mm), p=0.04. The maximum load at failure was similar in both treatment groups (dynamic suture: 374± 159 N; conventional suture: 379± 154 N), p=0.925. The predominant failure mechanism was breakout of the button from the bone (dynamic suture: 5/8; conventional suture: 6/8), followed by suture rupturing, suture unraveling and tendon cut-through. Conclusion. From a biomechanical perspective, the novel dynamic high-strength suture demonstrated higher resistance against gap formation at the bone tendon interface compared to the conventional suture, which may contribute to better postoperative tendon integrity and potentially quicker functional recovery in the clinical setting

Abstract. Objective. Short-stem total hip arthroplasty (THA) aims to preserve the proximal bone stock for future revisions, so that the first revision should resemble a primary intervention rather than a revision. This study aimed to compare the clinical and radiological outcomes in revision THA after failed short stem versus after failed conventional stem THA. Methods. This study included forty-five patients with revision THA divided into three groups (15 each); group A: revision after short stem, group B: revision after conventional cementless stem and group C revision after conventional cemented stem. The studied groups were compared regarding 31 variables including demographic data, details of the primary and revision procedures, postoperative radiological subsidence, hospital stay, time for full weight bearing (FWB), preoperative and postoperative clinical scores. Results. Early stem subsidence (40%) was the main indication of revision in group A compared to peri-prosthetic femoral fractures (PFFs) (73.3%) and aseptic loosening (53.3%) in group B and C respectively (P=0.021). The mean time to revision was significantly shorter in group A (15 months) compared to 95.33 and 189.40 months in group B and C respectively. (P=0.005). Sixty % (9 patients) in group A were revised in the first year. The mean operative time, blood loss, postoperative blood transfusion and hospital stay were significantly lower in group A compared to group B and C (P<0.001, <0.001, 0.002 and 0.001 respectively). Revisions in group A were performed using either short stems (13.3%) or conventional stems (86.7%) whilst 80% of patients needed long stems and 20% of patients needed conventional stems in group B and C (P<0.001). The mean postoperative Harris Hip Score (HHS) at the latest follow up was 87.07, 87.53 and 85.47 in group A, B and C respectively. All PFFS had excellent results according to Beal's and Tower's criteria; all fractures healed and the implants were stable. Conclusion. The most common cause of failure of short stems is early stem subsidence. Short stem THA has specific indications and patient selection is very crucial. Preoperative templating for short stems and a detailed analysis of the individual patient anatomy in anteroposterior and lateral views are mandatory to predict the correct implant size more accurately. The use of intraoperative imaging can verify the sizing, implant position, and sufficient contact with the lateral cortex. Revision of short stem THA resembled the primary THA. If a standard implant can be used in a surgical revision instead of a longer revision stem, this can be considered as an advantage for the hip arthroplasty treatment concept. However, this only applies if the longevity of the first treatment with a short stem is comparable with that of a standard stem. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

The purpose of this randomized controlled trial was to evaluate serum metal levels in patients undergoing total hip arthroplasty (THA) with a conventional compared to a modular dual-mobility bearing. Patients undergoing primary THA for osteoarthritis were randomized to receive either a modular dual-mobility or conventional polyethylene bearing. All patients received the same titanium acetabular and femoral component and a ceramic femoral head. Serum metal levels were drawn pre-operatively then annually for a minimum of two years postoperatively. An a priori power analysis determined that 40 patients (20 per cohort) were needed to identify a clinically relevant difference in serum cobalt of 0.35 ng/ml (ppb) at 90% power. Forty-six patients were randomized to a modular dual-mobility (n=25) or conventional bearing (n=21) with 40 at a minimum follow-up of two years. No differences in serum cobalt (mean 0.14 ppb [range, 0.075–0.29] vs. 0.20 ppb [range, 0.075–0.57], p=0.39) or chromium levels (mean 0.14 ppb [range, 0.05–0.50] vs. 0.12 ppb [range, 0.05–0.35], p=0.65) were identified between the modular dual-mobility and conventional cohorts, respectively. There was no statistically significant difference in serum Co or Cr at two years postoperatively in subjects implanted with a ceramic head and this particular dual mobility bearing in comparison to a ceramic head and a conventional acetabular component. While modest expected elevations in serum Co and Cr were observed in the dual mobility group, in no case did the Co level exceed the laboratory reference range nor the threshold of one part per billion that has been associated with adverse local tissue reactions to mechanically-assisted crevice corrosion

Glenoid baseplate positioning for reverse total shoulder replacements (rTSR) is key for stability and longevity. 3D planning and image-derived instrumentation (IDI) are techniques for improving implant placement accuracy. This is a single-blinded randomised controlled trial comparing 3D planning with IDI jigs versus 3D planning with conventional instrumentation. Eligible patients were enrolled and had 3D pre-operative planning. They were randomised to either IDI or conventional instrumentation; then underwent their rTSR. 6 weeks post operatively, a CT scan was performed and blinded assessors measured the accuracy of glenoid baseplate position relative to the pre-operative plan. 47 patients were included: 24 with IDI and 23 with conventional instrumentation. The IDI group were more likely to have a guidewire placement within 2mm of the preoperative plan in the superior/inferior plane when compared to the conventional group (p=0.01). The IDI group had a smaller degree of error when the native glenoid retroversion was >10° (p=0.047) when compared to the conventional group. All other parameters (inclination, anterior/posterior plane, glenoids with retroversion <10°) showed no significant difference between the two groups. Both IDI and conventional methods for rTSA placement are very accurate. However, IDI is more accurate for complex glenoid morphology and placement in the superior-inferior plane. Clinically, these two parameters are important and may prevent long term complications of scapular notching or glenoid baseplate loosening. Image-derived instrumentation (IDI) is significantly more accurate in glenoid component placement in the superior/inferior plane compared to conventional instrumentation when using 3D pre-operative planning. Additionally, in complex glenoid morphologies where the native retroversion is >10°, IDI has improved accuracy in glenoid placement compared to conventional instrumentation. IDI is an accurate method for glenoid guidewire and component placement in rTSA

Abstract. Cemented total hip arthroplasty (THA) in the younger patient has historically been associated with higher wear and revision rates. We carried out a retrospective study of a prospectively collected database of patients at Wrightington hospital undergoing cemented THA under 55 years of age to determine acetabular wear and revision rates. Between August 2005 and December 2021 a cohort of 110 patients, 56 males and 54 females, underwent Cemented Total Hip Replacement through a posterior approach. Mean age at operation was 50yrs (35–55). The mean follow up was 6 years 9 months (0–16 years). 3 patients were lost to follow-up. Of the remaining 107 patients, Conventional and cross lined polyethylene were used in 54 and 53 patients respectively. Ceramic heads were used in 102 patients. 22.225mm and 28mm heads were used in 60 and 47 patients respectively. Clinical outcomes were assessed by Merle d'Aubigne and Postel scores which showed significant functional improvement. Linear wear was measured on plain radiographs using TRAUMA CAD and cup loosening was assessed by classification of Hodgkinson et al. No cases were revised during the observed follow up period. The mean wear rate in conventional and crosslinked polyethylene cups were 2.31mm (0.1–4.6) and 1.02mm (0.1–2.6) respectively. Cemented THA with both conventional and crosslinked polyethylene provides excellent survival rates in adults under the age of 55 years and crosslinked polyethylene may further improve these results due to improved wear rates

Aims. Lateral femoral cutaneous nerve (LFCN) injury is a potential complication after the direct anterior approach for total hip arthroplasty (DAA-THA). The aim of this study was to determine how the location of the fasciotomy in DAA-THA affects LFCN injury. Methods. In this trial, 134 patients were randomized into a lateral fasciotomy (n = 67) or a conventional fasciotomy (n = 67) group. This study was a dual-centre, double-blind, prospective randomized controlled two-arm trial with parallel group design and a 1:1 allocation ratio. The primary endpoint was the presence of LFCN injury, which was determined by the presence of numbness, decreased sensation, tingling, jolt-like sensation, or pain over the lateral aspect of the thigh, excluding the surgical scar, using a patient-based questionnaire. The secondary endpoints were patient-reported outcome measures (PROMs) using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ), and the Forgotten Joint Score-12 (FJS-12). Assessments were obtained three months after surgery. Results. The incidence of LFCN injury tended to be lower in the lateral fasciotomy group (p = 0.089). In the lateral fasciotomy group, there were no significant differences in the mean PROM scores between patients with and without LFCN injury (FJS-12: 54.42 (SD 15.77) vs 65.06 (SD 26.14); p = 0.074; JHEQ: 55.21 (SD 12.10) vs 59.72 (SD 16.50); p = 0.288; WOMAC: 82.45 (SD 6.84) vs 84.40 (SD 17.91); p = 0.728). In the conventional fasciotomy group, there were significant differences in FJS-12 and JHEQ between patients with and without LFCN injury (FJS-12: 43.21 (SD 23.08) vs 67.28 (SD 20.47); p < 0.001; JHEQ: 49.52 (SD 13.97) vs 59.59 (SD 15.18); p = 0.012); however, there was no significant difference in WOMAC (76.63 (SD 16.81) vs 84.16 (SD 15.94); p = 0.107). Conclusion. The incidence of LFCN injury at three months after THA was comparable between the lateral and conventional fasciotomy groups. Further studies are needed to assess the long-term effects of these approaches. Cite this article: Bone Joint J 2023;105-B(12):1252–1258

Aims. Ideal component sizing may be difficult to achieve in unicompartmental knee arthroplasty (UKA). Anatomical variants, incremental implant size, and a reduced surgical exposure may lead to over- or under-sizing of the components. The purpose of this study was to compare the accuracy of UKA sizing with robotic-assisted techniques versus a conventional surgical technique. Methods. Three groups of 93 medial UKAs were assessed. The first group was performed by a conventional technique, the second group with an image-free robotic-assisted system (Image-Free group), and the last group with an image-based robotic arm-assisted system, using a preoperative CT scan (Image-Based group). There were no demographic differences between groups. We compared six parameters on postoperative radiographs to assess UKA sizing. Incorrect sizing was defined by an over- or under-sizing greater than 3 mm. Results. There was a higher rate of tibial under-sizing posteriorly in the conventional group compared to robotic-assisted groups (47.3% (n = 44) in conventional group, 29% (n = 27) in Image-Free group, 6.5% (n = 6) in Image-Based group; p < 0.001), as well as a higher rate of femoral under-sizing posteriorly (30.1% (n = 28) in conventional group, 7.5% (n = 7) in Image-Free group, 12.9% (n = 12) in Image-Based group; p < 0.001). The posterior femoral offset was more often increased in the conventional group, especially in comparison to the Image-Based group (43% (n = 40) in conventional group, 30.1% (n = 28) in Image-Free group, 8.6% (n = 8) in Image-Based group; p < 0.001). There was no significant overhang of the femoral or tibial implant in any groups. Conclusion. Robotic-assisted surgical techniques for medial UKA decrease the risk of tibial and femoral under-sizing, particularly with an image-based system using a preoperative CT scan. Cite this article: Bone Joint J 2021;103-B(4):610–618

Aims. Achieving accurate implant positioning and restoring native hip biomechanics are key surgeon-controlled technical objectives in total hip arthroplasty (THA). The primary objective of this study was to compare the reproducibility of the planned preoperative centre of hip rotation (COR) in patients undergoing robotic arm-assisted THA versus conventional THA. Methods. This prospective randomized controlled trial (RCT) included 60 patients with symptomatic hip osteoarthritis undergoing conventional THA (CO THA) versus robotic arm-assisted THA (RO THA). Patients in both arms underwent pre- and postoperative CT scans, and a patient-specific plan was created using the robotic software. The COR, combined offset, acetabular orientation, and leg length discrepancy were measured on the pre- and postoperative CT scanogram at six weeks following surgery. Results. There were no significant differences for any of the baseline characteristics including spinopelvic mobility. The absolute error for achieving the planned horizontal COR was median 1.4 mm (interquartile range (IQR) 0.87 to 3.42) in RO THA versus 4.3 mm (IQR 3 to 6.8; p < 0.001); vertical COR mean 0.91 mm (SD 0.73) in RO THA versus 2.3 mm (SD 1.3; p < 0.001); and combined offset median 2 mm (IQR 0.97 to 5.45) in RO THA versus 3.9 mm (IQR 2 to 7.9; p = 0.019). Improved accuracy was observed with RO THA in achieving the desired acetabular component positioning (root mean square error for anteversion and inclination was 2.6 and 1.3 vs 8.9 and 5.3, repectively) and leg length (mean 0.6 mm vs 1.4 mm; p < 0.001). Patient-reported outcome measures were comparable between the two groups at baseline and one year. Participants in the RO THA group needed fewer physiotherapy sessions postoperatively (median six (IQR 4.5 to 8) vs eight (IQR 6 to 11; p = 0.005). Conclusion. This RCT suggested that robotic-arm assistance in THA was associated with improved accuracy in restoring the native COR, better preservation of the combined offset, leg length correction, and superior accuracy in achieving the desired acetabular component positioning. Further evaluation through long-term and registry data is necessary to assess whether these findings translate into improved implant survival and functional outcomes. Cite this article: Bone Joint J 2024;106-B(4):324–335

After a hip fracture, infections are common, but signs of infection resemble those of systemic inflammatory response to trauma and surgery, and conventional infection markers lack specificity. Plasma-calprotectin, a novel marker of neutrophil activation, has shown potential as an infection marker in ER and ICU settings. To investigate if plasma-calprotectin is superior compared to conventional infection biomarkers after hip fracture. Prospective cohort study of hip fracture patients admitted to our department. Calprotectin, procalcitonin (PCT), C-reactive protein (CRP), and white blood cell (WBC) count were measured in blood plasma upon admission and on day 3 post-surgery. Patients with infection (pneumonia, UTI, sepsis, SSI, other soft tissue infections) pre- or post-surgery were compared to a control group without infection within 30 days. Statistics: Wilcoxon rank-sum test, medians with interquartile range, and area under the curve (AUC) with 95% confidence intervals. Pilot study comprises calprotectin obtained at least once for 60 patients at admission and 48 on day 3. Mean age 84 years (SD 8.4), 65% women. 9/60 patients (23%) were admitted with infections. They had higher levels of CRP (median 111 [73-149]) and PCT (0.35 [0.18–0.86]) compared to the control group (29 [16-64], p=0.037; 0.10 [0.07–0.17], p=0.007). Calprotectin (2.67 vs 2.51) and WBC (12.2 vs 9.3) did not differ significantly. AUC was highest for PCT (0.79 [CI 0.60–0.97]), followed by CRP (0.71 [0.46–0.96]), WBC (0.60 [0.35–0.84]), and calprotectin (0.58, [0.33–0.83]). Day 3, 6/48 (13%) had infections, without significant differences between groups in any marker. The median levels were: calprotectin 3.5 vs 3.1, CRP 172 vs 104, WBC 12 vs 9, PCT 0.16 vs 0.17. Calprotectin had highest AUC 0.68 (0.41–0.93, n.s.). AUC for WBC was 0.67 (0.31–1.00), CRP 0.66 (0.38–0.94), PCT 0.56 (0.29–0.82). Preliminary data show no significant associations with postoperative infection for any of the studied biomarkers. However, plasma-calprotectin might perform slightly better compared to conventional markers

Introduction: Aim of the study was to investigate the fixation patterns of cementless short-stem designs compared to the fixation patterns of well-known conventional stems artificially shortened in several steps. Method: Primary rotational stability and tilting were measured in a standardized and validated simulator set-up. The tested short-stem designs included the Mayo (Zimmer), the CFP (Link), and the CUT (Eska). The “conventional” group consisted of the ABG (Stryker), the S-Rom (DePuy), and the G2 (DePuy). Additionally, these systems were tested when gradually shortened in several steps. Results: The Mayo stem showed a 2/3 fixation pattern with 11.5 mdeg/Nm relative movement at the level of the lesser trochanter. The CFP showed a more distal fixation with 6.8 mdeg/Nm, and the CUT a proximal fixation with 7.6 mdeg/Nm. The Mayo and the CFP adapted to the femoral canal during ventro-dorsal tilting. The CUT tilted like a rigid body. This pattern of tilting was also shown by the ABG after it was shortened from 12.5 cm to 8.5 cm, by the G2 after a reduction from 15 to 6 cm, and the S-Rom after shortening from 18 to 6.9 cm. Discussion: The shortened conventional stems showed a similar fixation pattern compared to the short-stem designs, the rotational stability was even better than with the Mayo and CFP stem. The CUT design acts like an extensively shortened conventional stem and seems to tilt in the femoral canal like a rigid body with a pressure increase at the lateral cortex of the femur

Abstract. Introduction. Component mal-positioning in total hip replacement (THR) and total knee replacement (TKR) can increase the risk of revision for various reasons. Compared to conventional surgery, relatively improved accuracy of implant positioning can be achieved using computer assisted technologies including navigation, patient-specific jigs, and robotic systems. However, it is not known whether application of these technologies has improved prosthesis survival in the real-world. This study aimed to compare risk of revision for all-causes following primary THR and TKR, and revision for dislocation following primary THR performed using computer assisted technologies compared to conventional technique. Methods. We performed an observational study using National Joint Registry data. All adult patients undergoing primary THR and TKR for osteoarthritis between 01/04/2003 to 31/12/2020 were eligible. Patients who received metal-on-metal bearing THR were excluded. We generated propensity score weights, using Sturmer weight trimming, based on: age, gender, ASA grade, side, operation funding, year of surgery, approach, and fixation. Specific additional variables included position and bearing for THR and patellar resurfacing for TKR. For THR, effective sample sizes and duration of follow up for conventional versus computer-guided and robotic-assisted analyses were 9,379 and 10,600 procedures, and approximately 18 and 4 years, respectively. For TKR, effective sample sizes and durations of follow up for conventional versus computer-guided, patient-specific jigs, and robotic-assisted groups were 92,579 procedures over 18 years, 11,665 procedures over 8 years, and 644 procedures over 3 years, respectively. Outcomes were assessed using Kaplan-Meier analysis and expressed using hazard ratios (HR) and 95% confidence intervals (CI). Results. For THR, analysis comparing computer-guided versus conventional technique demonstrated HR of 0.771 (95%CI 0.573–1.036) p=0.085, and 0.594 (95%CI 0.297–1.190) p=0.142, for revision for all-causes and dislocation, respectively. When comparing robotic-assisted versus conventional technique, HR for revision for all-causes was 0.480 (95%CI 0.067 –3.452) p=0.466. For TKR, compared to conventional surgery, HR for all-cause revision for procedures performed using computer guidance and patient-specific jigs were 0.967 (95% CI 0.888–1.052) p=0.430, and 0.937 (95% CI 0.708–1.241) p=0.65, respectively. HR for analysis comparing robotic-assisted versus conventional technique was 2.0940 (0.2423, 18.0995) p = 0.50. Conclusions. This is the largest study investigating this topic utilising propensity score analysis methods. We did not find a statistically significant difference in revision for all-causes and dislocation although these analyses are underpowered to detect smaller differences in effect size between groups. Additional comparison for revision for dislocation between robotic-assisted versus conventionally performed THR was not performed as this is a subset of revision for all-causes and wide confidence intervals were already observed for that analysis. It is also important to mention this NJR analysis study is of an observational study design which has inherent limitations. Nonetheless, this is the most feasible study design to answer this research question requiring use of a large data set due to revision being a rare outcome. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aims. Postoperative length of stay (LOS) and discharge dispositions following arthroplasty can be used as surrogate measurements for improvements in patients’ pathways and costs. With the increasing use of robotic technology in arthroplasty, it is important to assess its impact on LOS. The aim of this study was to identify factors associated with decreased LOS following robotic arm-assisted total hip arthroplasty (RO THA) compared with the conventional technique (CO THA). Methods. This large-scale, single-institution study included 1,607 patients of any age who underwent 1,732 primary THAs for any indication between May 2019 and January 2023. The data which were collected included the demographics of the patients, LOS, type of anaesthetic, the need for treatment in a post-anaesthesia care unit (PACU), readmission within 30 days, and discharge disposition. Univariate and multivariate logistic regression models were used to identify factors and the characteristics of patients which were associated with delayed discharge. Results. The multivariate model identified that age, female sex, admission into a PACU, American Society of Anesthesiologists grade > II, and CO THA were associated with a significantly higher risk of a LOS of > two days. The median LOS was 54 hours (interquartile range (IQR) 34 to 78) in the RO THA group compared with 60 hours (IQR 51 to 100) in the CO THA group (p < 0.001). The discharge dispositions were comparable between the two groups. A higher proportion of patients undergoing CO THA required PACU admission postoperatively, although without reaching statistical significance (7.2% vs 5.2%, p = 0.238). Conclusion. We found that among other baseline characteristics and comorbidities, RO THA was associated with a significantly shorter LOS, with no difference in discharge destination. With the increasing demand for THA, these findings suggest that robotic assistance in THA could reduce costs. However, randomized controlled trials are required to investigate the cost-effectiveness of this technology. Cite this article: Bone Joint J 2024;106-B(3 Supple A):24–30

Patient-reported outcome measures (PROMs) have failed to highlight differences in function or outcome when comparing knee replacement designs and implantation techniques. Ankle-worn inertial measurement units (IMUs) can be used to remotely measure and monitor the bi-lateral impact load of patients, augmenting traditional PROMs with objective data. The aim of this study was to compare IMU-based impact loads with PROMs in patients who had undergone conventional total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and robotic-assisted TKA (RA-TKA). 77 patients undergoing primary knee arthroplasty (29 RA-TKA, 37 TKA, and 11 UKA) for osteoarthritis were prospectively enrolled. Remote patient monitoring was performed pre-operatively, then weekly from post-operative weeks two to six using ankle-worn IMUs and PROMs. IMU-based outcomes included: cumulative impact load, bone stimulus, and impact load asymmetry. PROMs scores included: Oxford Knee Score (OKS), EuroQol Five-dimension with EuroQol visual analogue scale, and the Forgotten Joint Score. On average, patients showed improved impact load asymmetry by 67% (p=0.001), bone stimulus by 41% (p<0.001), and cumulative impact load by 121% (p=0.035) between post-operative week two and six. Differences in IMU-based outcomes were observed in the initial six weeks post-operatively between surgical procedures. The mean change scores for OKS were 7.5 (RA-TKA), 11.4 (TKA), and 11.2 (UKA) over the early post-operative period (p=0.144). Improvements in OKS were consistent with IMU outcomes in the RA-TKA group, however, conventional TKA and UKA groups did not reflect the same trend in improvement as OKS, demonstrating a functional decline. Our data illustrate that PROMs do not necessarily align with patient function, with some patients reporting good PROMs, yet show a decline in cumulative impact load or load asymmetry. These data also provide evidence for a difference in the functional outcome of TKA and UKA patients that might be overlooked by using PROMs alone