Aims. This study aimed to investigate the optimal sagittal positioning of the uncemented femoral component in total knee arthroplasty to minimize the risk of aseptic loosening and periprosthetic fracture. Methods. Ten different sagittal placements of the femoral component, ranging from -5 mm (causing anterior notch) to +4 mm (causing anterior gap), were analyzed using finite element analysis. Both gait and squat loading conditions were simulated, and Von Mises stress and interface micromotion were evaluated to assess fracture and loosening risk. Results. During gait, varied sagittal positioning did not lead to excessive Von Mises stress or micromotion. However, under squat conditions, posterior positioning (-4 and -5 mm) resulted in stress exceeding 150 MPa at the femoral notch, indicating potential fracture risk. Conversely, +1 mm and 0 mm sagittal positions demonstrated minimal interface micromotion. Conclusion. Slightly anterior sagittal positioning (+1 mm) or neutral positioning (0 mm) effectively reduced stress concentration at the femoral notch and minimized interface micromotion. Thus, these positions are deemed suitable to decrease the risk of aseptic loosening and periprosthetic femoral fracture

The October 2024 Trauma Roundup³⁶⁰ looks at: Early versus delayed weightbearing following operatively treated ankle fracture (WAX): a non-inferiority, multicentre, randomized controlled trial; The effect of early weightbearing and later weightbearing rehabilitation interventions on outcomes after ankle fracture surgery; Is intramedullary nailing of femoral diaphyseal fractures in the lateral decubitus position as safe and effective as on a traction table?; Periprosthetic fractures of the hip: Back to the Future, Groundhog Day, and horses for courses; Two big bones, one big decision: when to fix bilateral femur fractures; Comparison of ankle fracture fixation using intramedullary fibular nailing versus plate fixation; Unclassified acetabular fractures: do they really exist?

Aims

Custom-made partial pelvis replacements (PPRs) are increasingly used in the reconstruction of large acetabular defects and have mainly been designed using a triflange approach, requiring extensive soft-tissue dissection. The monoflange design, where primary intramedullary fixation within the ilium combined with a monoflange for rotational stability, was anticipated to overcome this obstacle. The aim of this study was to evaluate the design with regard to functional outcome, complications, and acetabular reconstruction.

Highly cross-linked polyethylene (HXLPE) has decreased wear and revision rates in total hip replacement (THR) at a long-term. However, the effect of HXLPE manufacturing characteristics on femoral head penetration has not been clearly defined yet. We report this single-institution study to investigate the clinical and radiological results of different HXLPE liners in THR. In this retrospective cohort analysis of our prospective database, we identified 904 THRs performed between 2000 and 2013. Seven different HXLPE liner types were assessed: remelted (3), annealed (2), sequentially annealed (1) and vitamin E-infused (1). The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Roman Software v1.70 package. Thirty hips were revised for the following reasons: aseptic loosening (11), dislocation (12), periprosthetic femoral fracture (6), and infection (1). No hip was revised for wear or osteolysis. 741 THRs were evaluated for a mean follow-up of 15 years (range, 10 to 20). The mean total penetration 15 years after THR was 0.17 mm in the sequentially annealed, and 0.16 mm in the vitamin E-infused groups, whereas it was 0.26 mm in the melted 95 kGy, 0.27 mm in the melted 5 Mrad and 0.25 mm in the melted 100 kGy groups (p=0.001). From one to 15 years after surgery, the mean wear was 0.206 mm in cups with an acetabular inclination greater than 50º and 0.105 mm in those placed between 35º and 50º (p<0.001). Although HXLPE characteristics can result in a different wear performance in patients undergoing THR at a mean follow-up of 15 years, the clinical results are excellent. The position of the acetabular component can influence on the femoral head penetration of modern HXLPEs. Nevertheless, these patients should continue to be monitored to detect future problems

When treating periprosthetic femur fractures (PPFFs) around total hip arthroplasty (THA)], determining implant fixation status preoperatively is important, since this guides treatment regarding ORIF versus revision. The purpose of this study was to determine the accuracy of preoperative implant fixation status determination utilizing plain films and CT scans. Twenty-four patients who underwent surgery for Vancouver B type PPFF were included in the study. Two joint surgeons and two traumatologists reviewed plain films alone and made a judgment on fixation status. They then reviewed CT scans and fixation status was reassessed. Concordance and discordance were recorded. Interobserver reliability was assessed using Kendall's W and intraobserver reliability was assessed using Cohen's Kappa. Ultimately, the “correct” response was determined by intraoperative findings, as we routinely test the component intraoperatively. Fifteen implants were found to be well-fixed (63%) and 9 were loose. Plain radiographs alone predicted correct fixation status in 53% of cases. When adding the CT data, the correct prediction only improved to 55%. Interestingly, concordance between plain radiographs and CT was noted in 82%. In concordant cases, the fixation status was found to be correct in 55% of cases. Of the 18% of cases with discordance, plain films were correct in 43% of cases, and the CT was correct in 57%. Interobserver reliability demonstrated poor agreement on plain films and moderate agreement on CT. Intraobserver reliability demonstrated moderate agreement on both plain films and CT. The ability to determine fixation status for proximal PPFFs around uncemented femoral components remains challenging. The addition of routine CT scanning did not significantly improve accuracy. We recommend careful intraoperative testing of femoral component fixation with surgical dislocation if necessary, and the surgeon should be prepared to revise or fix the fracture based on those findings

The stem design in total hip arthroplasty (THA) is constantly evolving. The impact of the collar on the risk of periprosthetic fracture remains controversial. This study aimed to determine whether adding a collar to the femoral stem impacts the early periprosthetic fracture risk within 90 days of surgery. This retrospective study included 1,623 patients who underwent primary total hip arthroplasty in a single orthopedic department between January 2010 and December 2020. The inclusion criteria were uncemented stem with or without a collar, in a primary intention, without previous hip surgery with a similar “corail like” design. The assessed data were demographic characteristics (age, gender, number of obese (BMI > 30)), single or dual mobility, the surgical approach, the early complication, particularly the periprosthetic femoral fractures. Of the 1,623 patients, 1,380 received a collared stem (85%), and 243 received a collarless stem (15%). A multivariate analysis was performed to determine the collar's effect on the risk of early periprosthetic fracture (<90 days). Nine (0.55%) early periprosthetic fractures were identified in the whole cohort. There were four fractures (1.65%) in the collarless stem group and five fractures (0.36%) in the collared stem group (p=0,005). One patient required revision surgery in the collared stem group, while two patients required revision surgery in the collarless stem group. The multinomial logistic regression model indicated a statistically significant lower (p<0.05) risk of early periprosthetic fracture within 90 days of surgery in the collared stems group. No other risk factor for early periprosthetic fractures has been identified. Using collared stems in cementless THA protects early periprosthetic femoral fractures within 90 days of surgery

A: - determine the incidence of intraoperative periprosthetic femoral fracture (PFF). B: - determine the incidence of, and the reoperation rate for postoperative PFF. When using either CC or PTS femoral components. Retrospective review of a consecutive series of 11,018 THAs over a ten-year period. All PFFs were identified using regional radiograph archiving and electronic care systems. Of the 11,018 THAs 4,952 were CC and 6,066 were PTS. Between groups, age, sex, and BMI did not differ. A: - 55 (0.5%) had an intraoperative PFF. 44 CC and 11 PTS (p<0.001). 3 patients in each group had a femoral shaft fracture, remaining fractures were either the calcar (20 CC and 2 group) or the greater trochanter (11 CC and 6 PTS). B: - 91(0.8%) sustained a postoperative PFF. Of those 15 were managed conservatively, 15 were revised and 61 (80.3%) had an ORIF. The CC group had both a lower overall rate of postoperative PFFs (0.7% (36/4,952) vs 0.9% (55/6,066); p = 0.341), and a lower rate of return to theatre (0.4% (22/4,952) vs 0.9% (54/6,066); p = 0.005). 1.3% of male PTS (36/2,674) had a reoperation compared to 0.3% of male CC (7/2,121) (p<0.001). With regard to stem fracture there were none in the Corail group and 5 in the Exeter group. Of these 2 were sub trunnion and 3 were basal neck. A: - There were significantly more intraoperative PFFs with CC 44 (0.8%) than PTS 11 (0.2%). However, the majority of fractures were either of the calcar or greater trochanter with no impact on early recovery or one year Oxford scores. B: - Male PTS were five times more likely to have a reoperation for postoperative PFF. Females had the same incidence of reoperation with either component type. There were 5 stem fractures in the Exeter group and none in the Corail. These results represent robust estimates, which are likely to be more accurate than revision only studies typically generated from registry data

Previous studies have highlighted differences in the risk of periprosthetic fracture between tapered slip (TS) and composite beam (CB) stems. This biomechanical study explored periprosthetic fractures around these stems and the effect of adding a 16-gauge calcar or diaphyseal wire to TS stems on their resistance to torque.

A power analysis determined a sample size of 7 specimens per group, assuming a standard deviation of 14.8 Nm in peak torque, to provide 90% power to detect a difference of at least 30 Nm between groups. Twenty-one TS stems (eight alone, six with calcar wiring, seven with diaphyseal wiring placed 2 cm distal to the lesser trochanter) and seven CB stems were cemented into standard Sawbones. A servo-hydraulic test machine applied a 1000 N load with a 1-degree rotation per second until failure. The peak torque at failure was measured, and the fracture location recorded. Comparisons were performed using two-sample t-tests.

CB stems exhibited a significantly higher peak torque at failure (205.3 Nm) than TS stems (159.5 Nm, p=0.020). Calcar-wire-TS (148.2 Nm, p=0.036) and diaphyseal-wire-TS (164.9 Nm, p=0.036) were both weaker than CB stems. Wired-TS stems showed no significant difference from non-wired-TS stems. Additionally, the study could not conclude that calcar wiring is stronger than diaphyseal wiring. All TS fractures occurred at the mid-stem, simulating a B-type fracture, while the addition of the diaphyseal wire shifted the fracture location more distally in four of seven stems (p=0.0699).

This biomechanical study supports the clinical evidence that CB stems have stronger resistance to torque than TS stems and may explain lower risk of periprosthetic fracture. The addition of calcar or diaphyseal wires to TS stems resulted in no significant changes in peak torque to fracture. In patients at high risk of periprosthetic fracture, CB cemented stems should be considered.

Post-operative peri-prosthetic femoral fracture (PO-PPFF) is one of the most relevant complications in primary Total Hip Arthroplasty (pTHA), accountable for a significant clinical and socio-economic burden both in revision and fixation settings. We retrospectively reviewed of our series of 1586 cementless total hip arthroplasty performed between 1999 and 2019 (achieving a minimum of 5-years follow-up) with different short stems. We have observed a cumulative low incidence of PO-PPFF of 0,33% (5 cases): we divided Po-PPFF in two groups: fracture occurred around a short stem (A) and around a standard shortened stem (B), according to French Hip & Knee Classification of Short Stems. Despite the length of observed period (mean follow-up 12 years, min 5 years max 24 years) a total of 1512 cases (mean age at surgery 61 years, max 74, min 40 years) were available to clinical and radiographic follow-up, being this population enrolled in elective surgery clinical protocols. Our data exceed the low incidence of post-operative femoral fracture around bone -preserving previously reported by Kim in 2018 (12 fracture out of 1089 cases:1.1%). No correlation have been observed among occurrence of PO-PPF age of the patient and no fracture occurred around cemented short stems despite patient's characteristics were unfavourable in term of age and bone quality. This result is not unexpected, giving the lower incidence of peri-prosthetic fracture even cemented conventional stems, as reported in all registry and systematic reviews. A similar behaviour was reported in 2020 Australian Joint Registry, where Post-operative periprosthetic femoral fracture showed a steep curve in early period, but remaining firmly below 1% during the following 12 years. Our clinical data seems to confirm previous studies by Jones (conducted on synthetic bone and fresh-frozen cadaveric femurs) where higher fracture angles and higher fracture torque were detected in short hips compared to standard stems

Periprosthetic femoral fractures (PFFs) remain a major concern following cementless total hip arthroplasty (THA). This study aimed to evaluate the association between different types of cementless tapered stems and the risk of postoperative PFF. A retrospective review of primary THAs performed at a single center from January 2011 to December 2018 included 3,315 hips (2,326 patients). Cementless stems were classified according to their design geometry using the system proposed by Radaelli et al. The incidence of PFF was compared between flat taper porous-coated stems (type A), rectangular taper grit-blasted stems (type B1), and quadrangular taper hydroxyapatite-coated stems (type B2). Multivariate regression analyses were performed to identify independent factors related to PFF. The mean follow-up duration was 61 months (range, 12‒139 months). Overall, 45 (1.4%) postoperative PFFs occurred. The incidence of PFF was significantly higher in type B1 stems than in type A and type B2 stems (1.8 vs. 0.7 vs. 0.7%; P=0.022). Additionally, more surgical treatments (1.7 vs. 0.5 vs. 0.7%; P=0.013) and femoral revisions (1.2 vs. 0.2 vs. 0%; P=0.004) were required for PFF in type B1 stems. After controlling for confounding variables, older age (P<0.001), diagnosis of hip fracture (P<0.001), and use of type B1 stems (P=0.001) were significant factors associated with PFF. Type B1 rectangular taper stems were found to have higher risks for postoperative PFF and PFF requiring surgical management than type A and type B2 stems in THA. Femoral stem geometry should be considered when planning for cementless THA in elderly patients with compromised bone quality

The results of total hip arthroplasty (THA) revisions to correct leg length discrepancy (LLD) are not clear, with only two former limited series (< 25 patients). Therefore, we conducted a retrospective study of THA revisions for LLD to determine: 1) the change in LLD, 2) the function outcomes and whether obtaining equal leg lengths influenced function, 3) the complication and survival rates. This multicenter study included 57 patients: 42 THA revisions for limb shortening and 15 revisions for limb lengthening. LLD was measured on conventional radiographs and EOS. The Oxford-12 and FJS outcome scores were collected and the number of patients achieving the Oxford-12 MCID. The revisions were carried out a mean of 2.8 years after the index THA. The median LLD decreased from 7.5 mm (IQR: [5;12]) to 1 mm (IQR: [0.5;2.5]) at follow-up (p=0.0002). Overall, 55 of 57 patients (96%) had < 5 mm LLD at follow-up and 12 patients (21%) had equal leg lengths. The complication rate was 25%: 12 mechanical complications (8 periprosthetic femoral fractures, 2 stem loosening and 1 cup loosening, 1 dislocation) and 1 periprosthetic infection. The patient satisfaction was high with a median FJS of 79.2/100 and 77% of patients reached the Oxford-12 MCID. Lengthening procedures had significantly worst function than shortening (38% vs 91% of patients achieving the Oxford-12 MCID (p=0.0004)). Survivorship was 85% (95% CI: 77.9 – 92.5) at 2 years and 77% (95% CI: 66.3 – 87.1) at 4.6 years when using re-revision for any reason as the endpoint. When LLD after THA does not respond to conservative management, revision THA should be considered. Although revision THA for LLD improved medium-term functional outcomes with a high patient satisfaction rate, especially for shortening procedures, the complication rate was high, particularly related to periprosthetic femoral fracture

Short stems have been developed to conserve bone stock, especially in younger populations undergoing a total hip arthroplasty (THA), and showed similar functional outcomes compared to conventional stems. Recent literature suggested that stem length might be an independent risk factor for acute periprosthetic femoral fracture in direct anterior THA (1) or with different short stem designs (2). The purpose of the present study was to compare the incidence of acute periprosthetic femoral fractures, between stems of the same manufacture (Taperloc microplasty vs Taperloc complete), which have the same stem characteristics, except for the stem length which is 35 mm shorter in Taperloc microplasty during posterior and lateral THA. Our institution's arthroplasty database was searched for all primary total hip arthroplasties utilizing short femoral stems performed between August 2016 and August 2023. Pre-operative X-rays for each case were analysed to characterize the proximal femoral geometry, specifically the canal bone ratio (CBR) and canal flare index (CFI). Data analysis was performed to identify risk factors for periprosthetic fractures. For the time period assessed, 2107 femoral stems (Taperloc Microplasty:1727, Taperloc complete: 380) were implanted. Females constituted 53% of the cohort. The average patient age was 70±11 years. The periprosthetic fracture rate was 0.94%, with 20 periprosthetic fractures (Taperloc Microplasty:17, Taperloc complete: 3) excluding 2 greater trochanteric fractures (1 at each group), identified at follow-up of three months. There was no significant difference between the periprosthetic fracture rates between the two stems (0.98% vs 0.79%, p>0.72) The multivariate regression analysis demonstrated that the stem length, CBR, CFI, age, and gender were not risk factors for periprosthetic fracture. The present study demonstrated that both Taperloc Microplasty and Taperloc complete stems had similar rates of periprosthetic fractures, and the stem length was not a risk factor for a periprosthetic fracture during uncemented THA. 1. Tamaki T, Cementless Tapered-Wedge Stem Length Affects the Risk of Periprosthetic Femoral Fractures in Direct Anterior Total Hip Arthroplasty. J Arthroplasty. 2018 Mar;33(3):805-809. 2. Staunton P. Acute Periprosthetic Hip Fracture with Short Uncemented Femoral Stems. J Arthroplasty 2024 accepted

The August 2024 Hip & Pelvis Roundup³⁶⁰ looks at: Understanding perceived leg length discrepancy post-total hip arthroplasty: the role of pelvic obliquity; Influence of femoral stem design on revision rates in total hip arthroplasty; Outcomes of arthroscopic labral treatment of femoroacetabular impingement in adolescents; Characteristics and quality of online searches for direct anterior versus posterior approach for total hip arthroplasty; Rapid return to braking after anterior and posterior approach total hip arthroplasty; How much protection does a collar provide?; Timing matters: reducing infection risk in total hip arthroplasty with corticosteroid injection intervals; Identifying pain recovery patterns in total hip arthroplasty using PROMIS data.

Aims

This study aimed to evaluate if total knee arthroplasty (TKA) femoral components aligned in either mechanical alignment (MA) or kinematic alignment (KA) are more biomimetic concerning trochlear sulcus orientation and restoration of trochlear height.

The recruitment drive, investment and collaboration within Betsi Cadwaladr University Health Board (BCUHB) sites providing specialist lower limb arthroplasty and trauma service has evolved over last few years with aims to improve patient care and reduce reliance on tertiary referral centres. Through our service-evaluation project, we reviewed the results of treatment provided for periprosthetic femur fractures (PPFFs) presenting to BCUHB sites over last 4 years. We retrospectively reviewed consecutive PPFFs admitted at three BCUHB sites from January’20 to June’23 with mean follow-up of 20.8 ± 13.2 (8–49) months [n=161; Mean age: 82.2 ± 8.5 (59–101) years, Females:107]. Over the review period we noted a 23% increase in service demand for care of PPFFs. Majority were managed surgically [132/161] [38 revision arthroplasties; 94 ORIFs] at BCUHB sites and two patients were referred to tertiary centre. Average time to surgery was 3.5 days. 90% of the PPFFs were managed successfully with 10% (16/159) having orthopaedic complications needing further intervention. 6.3 (10/159) had medical complications and did not need orthopaedic re-intervention. In our series, 12-month re-operation rate was 6.1% (8/132) and 1-month, 3-month and 1-year mortality rate was 6.3%, 11.3% and 21.4% respectively. These results are comparable to the published results of PPFF management at tertiary centres. Potential cost savings compared to transfer to tertiary centre for PPFF management was £2.31 million. Thus, it is possible to successfully provide adequate care for PPFFs at DGHs and efforts should be made to appropriately equip and adequately staff DGHs, to provide service for local PPFF care

Aims

In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component.

The June 2024 Hip & Pelvis Roundup³⁶⁰ looks at: Machine learning did not outperform conventional competing risk modelling to predict revision arthroplasty; Unravelling the risks: incidence and reoperation rates for femoral fractures post-total hip arthroplasty; Spinal versus general anaesthesia for hip arthroscopy: a COVID-19 pandemic- and opioid epidemic-driven study; Development and validation of a deep-learning model to predict total hip arthroplasty on radiographs; Ambulatory centres lead in same-day hip and knee arthroplasty success; Exploring the impact of smokeless tobacco on total hip arthroplasty outcomes: a deeper dive into postoperative complications.

Aims

The aim of this study was to compare the pattern of initial fixation and changes in periprosthetic bone mineral density (BMD) between patients who underwent total hip arthroplasty (THA) using a traditional fully hydroxyapatite (HA)-coated stem (T-HA group) and those with a newly introduced fully HA-coated stem (N-HA group).