Understanding spinopelvic mechanics is important for the success of total hip arthroplasty (THA). Despite significant advancements in appreciating spinopelvic balance, numerous challenges remain. It is crucial to recognize the individual variability and postoperative changes in spinopelvic parameters and their consequential impact on prosthetic component positioning to mitigate the risk of dislocation and enhance postoperative outcomes. This review describes the integration of advanced diagnostic approaches, enhanced technology, implant considerations, and surgical planning, all tailored to the unique anatomy and biomechanics of each patient. It underscores the importance of accurately predicting postoperative spinopelvic mechanics, selecting suitable imaging techniques, establishing a consistent nomenclature for spinopelvic stiffness, and considering implant-specific strategies. Furthermore, it highlights the potential of artificial intelligence to personalize care.

Cite this article: Bone Joint J 2024;106-B(11):1206–1215.

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The aim of this study was to investigate the impact of the level of upper instrumented vertebra (UIV) in frail patients undergoing surgery for adult spine deformity (ASD).

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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.

Aims. The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population. Methods. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics. Results. There were evident biomechanical differences between the simulated patient models, but also trends that appeared reproducible at the population level. Optimizing the implant position significantly reduced the maximum observed strain root mean square deviations within the cohort from 36.5% to below 5.3% for all but the anterolateral ligament; and concomitantly reduced the kinematic deviations from 3.8 mm (SD 1.7) and 4.7° (SD 1.9°) with MA to 2.7 mm (SD 1.4) and 3.7° (SD 1.9°) relative to the pre-diseased state. To achieve this, the femoral component consistently required translational adjustments in the anterior, lateral, and proximal directions, while the tibial component required a more posterior slope and varus rotation in most cases. Conclusion. These findings confirm that MA-induced biomechanical alterations relative to the pre-diseased state can be reduced by optimizing the implant position, and may have implications to further advance pre-planning in robotic-assisted surgery in order to restore pre-diseased knee function. Cite this article: Bone Joint J 2024;106-B(11):1231–1239

Aims. The Coronal Plane Alignment of the Knee (CPAK) classification has been developed to predict individual variations in inherent knee alignment. The impact of preoperative and postoperative CPAK classification phenotype on the postoperative clinical outcomes of total knee arthroplasty (TKA) remains elusive. This study aimed to examine the effect of postoperative CPAK classification phenotypes (I to IX), and their pre- to postoperative changes on patient-reported outcome measures (PROMs). Methods. A questionnaire was administered to 340 patients (422 knees) who underwent primary TKA for osteoarthritis (OA) between September 2013 and June 2019. A total of 231 patients (284 knees) responded. The ­Knee Society Score 2011 (KSS 2011), Knee injury and Osteoarthritis Outcome Score-12 (KOOS-12), and Forgotten Joint Score-12 (FJS-12) were used to assess clinical outcomes. Using preoperative and postoperative anteroposterior full-leg radiographs, the arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) were calculated and classified based on the CPAK classification. To investigate the impact on PROMs, multivariable regression analyses using stepwise selection were conducted, considering factors such as age at surgery, time since surgery, BMI, sex, implant use, postoperative aHKA classification, JLO classification, and changes in aHKA and JLO classifications from preoperative to postoperative. Results. The preoperative and postoperative CPAK classifications were predominantly phenotype I (155 knees; 55%) and phenotype V (73 knees; 26%), respectively. The change in the preoperative to postoperative aHKA classification was a significant negative predictive factor for KOOS-12 and FJS-12, while postoperative apex proximal JLO was a significant negative predictive factor for KSS 2011 and KOOS-12. Conclusion. In primary TKA for OA, preoperative and postoperative CPAK phenotypes were associated with PROMs. Alteration in varus/valgus alignment from preoperative to postoperative was recognized as a negative predictive factor for both KOOS-12 and FJS-12. Moreover, the postoperative apex proximal JLO was identified as a negative factor for KSS 2011 and KOOS-12. Determining the target alignment for each preoperative phenotype with reproducibility could improve PROMs. Cite this article: Bone Joint J 2024;106-B(10):1059–1066

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This study aimed to gather insights from elbow experts using the Delphi method to evaluate the influence of patient characteristics and fracture morphology on the choice between operative and nonoperative treatment for coronoid fractures.

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The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution.

Advanced 3D imaging and CT-based navigation have emerged as valuable tools to use in total knee arthroplasty (TKA), for both preoperative planning and the intraoperative execution of different philosophies of alignment. Preoperative planning using CT-based 3D imaging enables more accurate prediction of the size of components, enhancing surgical workflow and optimizing the precision of the positioning of components. Surgeons can assess alignment, osteophytes, and arthritic changes better. These scans provide improved insights into the patellofemoral joint and facilitate tibial sizing and the evaluation of implant-bone contact area in cementless TKA. Preoperative CT imaging is also required for the development of patient-specific instrumentation cutting guides, aiming to reduce intraoperative blood loss and improve the surgical technique in complex cases. Intraoperative CT-based navigation and haptic guidance facilitates precise execution of the preoperative plan, aiming for optimal positioning of the components and accurate alignment, as determined by the surgeon’s philosophy. It also helps reduce iatrogenic injury to the periarticular soft-tissue structures with subsequent reduction in the local and systemic inflammatory response, enhancing early outcomes. Despite the increased costs and radiation exposure associated with CT-based navigation, these many benefits have facilitated the adoption of imaged based robotic surgery into routine practice. Further research on ultra-low-dose CT scans and exploration of the possible translation of the use of 3D imaging into improved clinical outcomes are required to justify its broader implementation. Cite this article: Bone Joint J 2024;106-B(9):892–897

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The primary objective of this study was to develop a validated classification system for assessing iatrogenic bone trauma and soft-tissue injury during total hip arthroplasty (THA). The secondary objective was to compare macroscopic bone trauma and soft-tissues injury in conventional THA (CO THA) versus robotic arm-assisted THA (RO THA) using this classification system.

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. Methods. Bone surfaces from 1,012 CT scans of non-arthritic femora were segmented using a modelling and analytics system. TKA femoral components (Triathlon; Stryker) were virtually implanted in both MA and KA. Trochlear sulcus orientation was assessed by measuring the distal trochlear sulcus angle (DTSA) in native femora and in KA and MA prosthetic femoral components. Trochlear anatomy restoration was evaluated by measuring the differences in medial, lateral, and sulcus trochlear height between native femora and KA and MA prosthetic femoral components. Results. Femoral components in both MA and KA alignments exhibited a more valgus DTSA compared to native femora. However, DTSA deviation from native was significantly less in KA than in MA (4.8° (SD 2.2°) vs 8.8° (SD 1.8°); p < 0.001). DTSA deviation from native orientation correlated positively with the mechanical lateral distal femoral angle (mLDFA) in KA and negatively in MA (r = 0.53, p < 0.001; r = -0.18, p < 0.001). Medial trochlear height was not restored with either MA or KA, with MA resulting in lower medial trochlear height than KA in the proximal 20% of the trochlea. Lateral and sulcus trochlear height was not restored with either alignment in the proximal 80% of the trochlea. At the terminal arc point, KA replicated sulcus and lateral trochlear height, while MA led to over-restoration. Conclusion. Femoral components aligned in KA demonstrated greater biomimetic qualities than those in MA regarding trochlear sulcus orientation and trochlear height restoration, particularly in valgus femora. Variability across knees was observed, warranting further research to evaluate the clinical implications of these findings. Cite this article: Bone Joint J 2024;106-B(8):817–825

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Spinopelvic pathology increases the risk for instability following total hip arthroplasty (THA), yet few studies have evaluated how pathology varies with age or sex. The aims of this study were: 1) to report differences in spinopelvic parameters with advancing age and between the sexes; and 2) to determine variation in the prevalence of THA instability risk factors with advancing age.

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It is not clear which type of casting provides the best initial treatment in adults with a distal radial fracture. Given that between 32% and 64% of adequately reduced fractures redisplace during immobilization in a cast, preventing redisplacement and a disabling malunion or secondary surgery is an aim of treatment. In this study, we investigated whether circumferential casting leads to fewer fracture redisplacements and better one-year outcomes compared to plaster splinting.

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We compared decompression alone to decompression with fusion surgery for lumbar spinal stenosis, with or without degenerative spondylolisthesis (DS). The aim was to evaluate if five-year outcomes differed between the groups. The two-year results from the same trial revealed no differences.

Aims. Robotic arm-assisted surgery offers accurate and reproducible guidance in component positioning and assessment of soft-tissue tensioning during knee arthroplasty, but the feasibility and early outcomes when using this technology for revision surgery remain unknown. The objective of this study was to compare the outcomes of robotic arm-assisted revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) versus primary robotic arm-assisted TKA at short-term follow-up. Methods. This prospective study included 16 patients undergoing robotic arm-assisted revision of UKA to TKA versus 35 matched patients receiving robotic arm-assisted primary TKA. In all study patients, the following data were recorded: operating time, polyethylene liner size, change in haemoglobin concentration (g/dl), length of inpatient stay, postoperative complications, and hip-knee-ankle (HKA) alignment. All procedures were performed using the principles of functional alignment. At most recent follow-up, range of motion (ROM), Forgotten Joint Score (FJS), and Oxford Knee Score (OKS) were collected. Mean follow-up time was 21 months (6 to 36). Results. There were no differences between the two treatment groups with regard to mean change in haemoglobin concentration (p = 0.477), length of stay (LOS, p = 0.172), mean polyethylene thickness (p = 0.065), or postoperative complication rates (p = 0.295). At the most recent follow-up, the primary robotic arm-assisted TKA group had a statistically significantly improved OKS compared with the revision UKA to TKA group (44.6 (SD 2.7) vs 42.3 (SD 2.5); p = 0.004) but there was no difference in the overall ROM (p = 0.056) or FJS between the two treatment groups (86.1 (SD 9.6) vs 84.1 (4.9); p = 0.439). Conclusion. Robotic arm-assisted revision of UKA to TKA was associated with comparable intraoperative blood loss, early postoperative rehabilitation, functional outcomes, and complications to primary robotic TKA at short-term follow-up. Robotic arm-assisted surgery offers a safe and reproducible technique for revising failed UKA to TKA. Cite this article: Bone Joint J 2024;106-B(7):680–687

The aim of mechanical alignment in total knee arthroplasty is to align all knees into a fixed neutral position, even though not all knees are the same. As a result, mechanical alignment often alters a patient’s constitutional alignment and joint line obliquity, resulting in soft-tissue imbalance. This annotation provides an overview of how the Coronal Plane Alignment of the Knee (CPAK) classification can be used to predict imbalance with mechanical alignment, and then offers practical guidance for bone balancing, minimizing the need for soft-tissue releases. Cite this article: Bone Joint J 2024;106-B(6):525–531

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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).

Aims. The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral. Methods. The study involved 945 TKAs, which were performed in 641 patients with primary OA, between January 2000 and January 2009. These were classified into 12 phenotypes based on the combined assessment of four categories of the arithmetic hip-knee-ankle angle and three categories of actual joint line obliquity. The rates of survival were analyzed using Kaplan-Meier methods and the log-rank test. The Hospital for Special Surgery score and survival of each phenotype were compared with those of the reference phenotype with neutral alignment and a parallel joint line. We also compared long-term survival between the unchanged phenotype group and the corrected to neutral alignment-parallel joint line group in patients with Type IV-b (mild to moderate varus alignment-parallel joint line) phenotype. Results. The most common phenotype was Type I-b (mild to moderate varus alignment-medial joint line; 27.1% (n = 256)), followed by Type IV-b (23.2%; n = 219). There was no significant difference in the clinical outcomes and long-term survival between the groups. In Type IV-b phenotypes, the neutrally corrected group showed higher 15-year survival compared with the unchanged-phenotype group (94.9% (95% confidence interval (CI) 92.0 to 97.8) vs 74.2% (95% CI 98.0 to 100); p = 0.020). Conclusion. Constitutional varus was confirmed in more than half of these patients. Mechanically aligned TKA can achieve consistent clinical outcomes and long-term survival, regardless of the patient’s phenotype. The neutrally corrected group had better long-term survival compared with the unchanged phenotype group. Cite this article: Bone Joint J 2024;106-B(5):460–467

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The aim was to assess whether robotic-assisted total knee arthroplasty (rTKA) had greater knee-specific outcomes, improved fulfilment of expectations, health-related quality of life (HRQoL), and patient satisfaction when compared with manual TKA (mTKA).

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The purpose of this study was to assess the success rate and functional outcomes of bone grafting for periprosthetic bone cysts following total ankle arthroplasty (TAA). Additionally, we evaluated the rate of graft incorporation and identified associated predisposing factors using CT scan.