Aims. Valgus subsidence of uncemented tibial components following medial unicompartmental knee arthroplasty (UKA) poses a challenge in the early postoperative phase, necessitating a comprehensive understanding of its prevalence, risk factors, and impact on patient outcomes. Methods. This prospective multicentre study analyzed 97 knees from 90 patients undergoing UKA across four participating hospitals. A standardized surgical technique was employed uniformly by all participating surgeons. Postoperative evaluations were conducted preoperatively, and one day, four weeks, three months, and one year postoperative, encompassing weightbearing radiographs, bone mineral density assessments, and clinical outcome reports using the Forgotten Joint Score and Oxford Knee Score. Statistical analyses, including non-parametric correlation analysis using the Kendall correlation coefficient and Mann-Whitney U test, were performed to explore associations between subsidence and various patient-related or radiological parameters. Results. A total of eight patients showed more than 2° valgus subsidence (8.2%), higher than previously reported rates. There were significant correlations between subsidence and higher preoperative varus alignment of the tibia, larger adaptation of the preoperative varus to a postoperative neutral or valgus alignment, mediolateral undersizing of the tibial component, excessive lateral load of tibial component by more lateral position of femoral component relative to tibial component, a lower T-score, and female sex. Our study found no significant difference in pain scores between subsidence and non-subsidence groups at various postoperative milestones. Conclusion. These findings corroborate earlier suggested risk factors based on biomechanical models. Further research might provide the opportunity to identify high-risk groups preoperatively and adapt treatment strategies for these patients. Cite this article: Bone Jt Open 2025;6(2):178–185

Aims

Unicompartmental knee arthroplasty (UKA) is associated with an accelerated recovery, improved functional outcomes, and retention of anatomical knee kinematics when compared to manual total knee arthroplasty (mTKA). UKA is not universally employed by all surgeons as there is a higher revision risk when compared to mTKA. Robotic arm-assisted (ra) UKA enables the surgeon to position the prosthesis more accurately when compared to manual UKA, and is associated with improved functional outcomes and a lower early revision risk. Non-randomized data suggests that, when compared to mTKA, raUKA has a clinically meaningful greater functional benefit. This protocol describes a randomized controlled trial that aims to evaluate the clinical and cost-effectiveness of raUKA compared to mTKA for individuals with isolated medial compartment osteoarthritis (OA).

Aims. Sagittal lumbar pelvic alignment alters with posterior pelvic tilt (PT) following total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The individual value of pelvic sagittal inclination (PSI) following rebalancing of lumbar-pelvic alignment is unknown. In different populations, PT regresses in a linear relationship with pelvic incidence (PI). PSI and PT have a direct relationship to each other via a fixed individual angle ∠γ. This study aimed to investigate whether the new PI created by acetabular component positioning during THA also has a linear regression relationship with PT/PSI when lumbar-pelvic alignment rebalances postoperatively in patients with Crowe type III/IV DDH. Methods. Using SPINEPARA software, we measured the pelvic sagittal parameters including PI, PT, and PSI in 61 patients with Crowe III/IV DDH. Both PSI and PT represent the pelvic tilt state, and the difference between their values is ∠γ (PT = PSI + ∠γ). The regression equation between PI and PT at one year after THA was established. By substituting ∠γ, the relationship between PI and PSI was also established. The Bland-Altman method was used to evaluate the consistency between the PSI calculated by the linear regression equation (ePSI) and the actual PSI (aPSI) measured one year postoperatively. Results. The mean PT and PSI changed from preoperative values of 7.0° (SD 6.5°) and -8.0° (SD 6.7°), respectively, to 8.4° (SD 5.5°) and -4.5° (SD 5.9°) at one year postoperatively. This change shows that the pelvis tilted posteriorly following THA. In addition, when lumbar-pelvic alignment rebalanced, the linear regression equation between PI and PT was PT = 0.45 × PI - 10.5°, and PSI could be expressed as PSI = 0.45 × PI - 10.5° - ∠γ. The absolute difference between ePSI and aPSI was less than 5° in 55 of 61 patients (90.16%). Conclusion. The new PI created by the positioning of the acetabular component significantly affects the PSI when lumbar-pelvic alignment changes and rebalances after THA in patients with Crowe III/IV DDH. Cite this article: Bone Joint J 2025;107-B(2):149–156

The February 2025 Knee Roundup. 360. looks at: Once-weekly semaglutide in patients with obesity and knee osteoarthritis; How many patients should have a unicompartmental knee arthroplasty?; Staged revision of the infected knee arthroplasty and endoprosthesis; The metal allergy argument and knee arthroplasty; Is kinematic alignment all it’s cracked up to be?; Is bone-patella-bone the gold standard for revision?; Blood flow restriction and the dissatisfied knee arthroplasty

The February 2025 Trauma Roundup³⁶⁰ looks at: Risk factors for nonunion in femoral neck fracture patients with internal fixation: a multicentre (TRON group) retrospective study; Tranexamic acid administered at time of hospital admission does not decrease transfusion rates or blood loss for extracapsular hip fractures; The effect of anterior support screw (AS2) in unstable femoral trochanteric fractures; The effect of coronal plane angulation on patient-reported outcome measures of operatively treated distal femur fractures; Do proximal humerus fractures treated nonoperatively benefit from supervised physiotherapy?; Cephalomedullary nails: are dual lag screws superior to single lag screws?; Does cement need to be pressurized for hemiarthroplasty?.

Aims. To evaluate how fore- and midfoot coronal plane alignment differs in feet with hallux valgus (HV), using 3DCT when measured in standard weightbearing (SWB) versus sesamoid view (SV) position, and to determine whether first metatarsophalangeal (MTP) dorsiflexion affects the relationship between the first metatarsal (M1) head and the sesamoid bones. Methods. A consecutive series of 34 feet that underwent 3DCT in SWB and SV positions for symptomatic HV was assessed, of which four feet were excluded for distorted or incomplete images. Two foot and ankle clinicians independently digitized a series of points, and measured a series of angles according to a pre-defined protocol. Measurements include navicular pronation angle, M1 head (Saltzman angle), and metatarsosesamoid rotation angle (MSRA). Results. The mean age of the 30 patients was 57.5 years (SD 13.4). The mean navicular pronation angle was significantly smaller in the SV position (9.6° (SD 4.4°)) compared to the SWB position (16.4° (SD 5.8°); p < 0.001). There was a difference in MSRA between the SWB and SV positions, revealing an increase in MSRA in 22 patients, while there was a decrease in eight patients. In patients where the MSRA increased, the mean Saltzman angle was 2.5° (SD 5.7°) lower in the SV position versus the SWB position, while in patients where MSRA decreased, the mean Saltzman angle was 3.4° (SD 3.6°) greater in the SV position versus the SWB position. Conclusion. MTP dorsiflexion causes supination of the navicular, while other first ray parameters remain unchanged, and has a greater influence on the M1 head coronal alignment than on the sesamoids. MTP dorsiflexion induces axial rotations of M1, which vary in direction and magnitude from one patient to another. Cite this article: Bone Joint Res 2025;14(2):69–76

The February 2025 Wrist & Hand Roundup³⁶⁰ looks at: Delayed fixation of distal radial fractures beyond three weeks increases the odds of reoperation; A systematic review of management options for symptomatic scaphometacarpal impingement after trapeziectomy; Diagnosing occult scaphoid fractures: an art or science?; Dual-mobility trapeziometacarpal arthroplasty shows promising outcomes but lacks long-term evidence; 3D-printed titanium scaphoid implant offers a promising alternative for unreconstructable scaphoid nonunion; Lidocaine co-injection reduces pain intensity during corticosteroid injections in hand and wrist conditions; Long-term outcomes of PyroDisk arthroplasty for trapeziometacarpal osteoarthritis; Evaluating the impact of COVID-19 on hand surgery practices: adaptations and missed opportunities.

Aims

Radiostereometric analysis (RSA) is considered the gold standard for in vivo migration analysis, but CT-based alternatives show comparable results in the shoulder and hip. We have previously validated a CT-based migration analysis method (CTMA) in a knee phantom compared to RSA. In this study, we validated the method in patients undergoing total knee arthroplasty (TKA). Our primary outcome measure was the difference in maximum total point motion (MTPM) between the differing methods.

Aims

Around the world, the emergence of robotic technology has improved surgical precision and accuracy in total knee arthroplasty (TKA). This territory-wide study compares the results of various robotic TKA (R-TKA) systems with those of conventional TKA (C-TKA) and computer-navigated TKA (N-TKA).

Aims

Overall sagittal flexion is restricted in patients who have undergone both lumbar fusion and total hip arthroplasty (THA). However, it is not evident to what extent this movement is restricted in these patients and how this influences quality of life (QoL). The purpose of this study was to determine the extent to which hip-lumbar mobility is decreased in these patients, and how this affects their QoL score.

Hallux valgus (HV) presents as a common forefoot deformity that causes problems with pain, mobility, footwear, and quality of life. The most common open correction used in the UK is the Scarf and Akin osteotomy, which has good clinical and radiological outcomes and high levels of patient satisfaction when used to treat a varying degrees of deformity. However, there are concerns regarding recurrence rates and long-term outcomes. Minimally invasive or percutaneous surgery (MIS) has gained popularity, offering the potential for similar clinical and radiological outcomes with reduced postoperative pain and smaller scars. Despite this, MIS techniques vary widely, hindering comparison and standardization. This review evaluates the evidence for both open Scarf and Akin osteotomy and newer-generation MIS techniques. Fourth-generation MIS emphasizes multiplanar rotational deformity correction through stable fixation. While MIS techniques show promise, their evidence mainly comprises single-surgeon case series. Comparative studies between open and MIS techniques suggest similar clinical and radiological outcomes, although MIS may offer advantages in scar length and less early postoperative pain. MIS may afford superior correction in severe deformity and lower recurrence rates due to correcting the bony deformity rather than soft-tissue correction. Recurrence remains a challenge in HV surgery, necessitating long-term follow-up and standardized outcome measures for assessment. Any comparison between the techniques requires comparative studies. Surgeons must weigh the advantages and risks of both open and MIS approaches in collaboration with patients to determine the most suitable treatment.

Cite this article: Bone Joint J 2025;107-B(1):10–18.

Traditionally, patients with a fracture of the distal radius are treated in a cast if they do not require surgery. If the fracture requires manipulation, the cast is moulded to hold the reduction and maintain normal anatomical alignment during healing. However, is a cast necessary for patients whose fracture does not require manipulation? Removable splints are an alternative treatment option. Such splints have the advantage that they can be adjusted to improve fit around the wrist as swelling reduces, and can be removed and reapplied for the purpose of washing or, in some cases, exercise. However, evidence for their safety and effectiveness in the management of distal radius fractures is lacking. DRAFT3 is a multicentre randomized non-inferiority trial and economic analysis designed to determine the safety and effectiveness of removable splints as an alternative to casts in the treatment of distal radius fractures that do not require manipulation. Cite this article: Bone Joint J 2025;107-B(1):7–9

Aims

Excellent outcomes have been reported following CT-based robotic arm-assisted total hip arthroplasty (rTHA) compared with manual THA; however, its superiority over CT-based navigation THA (nTHA) remains unclear. This study aimed to determine whether a CT-based robotic arm-assisted system helps surgeons perform accurate cup placement, minimizes leg length, and offsets discrepancies more than a CT-based navigation system.

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

Aims

Limb salvage surgery (LSS) is the primary treatment option for primary bone malignancy. It involves the removal of bone and tissue, followed by reconstruction with endoprosthetic replacements (EPRs) to prevent amputation. Trabecular metal (TM) collars have been developed to encourage bone ingrowth (osseointegration (OI)) into EPRs. The primary aim of this study was to assess whether OI occurs when TM collars are used in EPRs for tumour.

Aims. Functional alignment (FA) in total knee arthroplasty (TKA) aims to achieve balanced gaps by adjusting implant positioning while minimizing changes to constitutional joint line obliquity (JLO). Although FA uses kinematic alignment (KA) as a starting point, the final implant positions can vary significantly between these two approaches. This study used the Coronal Plane Alignment of the Knee (CPAK) classification to compare differences between KA and final FA positions. Methods. A retrospective analysis compared pre-resection and post-implantation alignments in 2,116 robotic-assisted FA TKAs. The lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were measured to determine the arithmetic hip-knee-ankle angle (aHKA = MPTA – LDFA), JLO (JLO = MPTA + LDFA), and CPAK type. The primary outcome was the proportion of knees that varied ≤ 2° for aHKA and ≤ 3° for JLO from their KA to FA positions, and direction and magnitude of those changes per CPAK phenotype. Secondary outcomes included proportion of knees that maintained their CPAK phenotype, and differences between sexes. Results. Overall, 71.6% had an aHKA change ≤ 2°, and 87.0% a JLO change ≤ 3°. Mean aHKA changed from -1.1° (SD 2.8°) in KA to -1.9° (SD 2.3°) in FA (mean difference (MD) -0.83 (SD 2.0); p < 0.001). Mean JLO changed from 173.9° (SD 3.0°) in KA to 174.2° (SD 2.6°) in FA (MD 0.38 (SD 2.3); p < 0.001). CPAK type was maintained in 58.1% of knees, with the proportion highest for Types I (73.9%), II (61.1%), and IV (51.2%). In valgus knees, 67.5% of Type III and 71.7% of Type VI were shifted to neutral phenotypes. There was minimal change to constitutional JLO across all CPAK types (MDs -2.0° to 1.2°). Conclusion. Functional alignment may alter CPAK type, but does not significantly change JLO. A kinematic starting point minimizes changes to native anatomy, while final position with FA provides an optimally balanced TKA. Cite this article: Bone Jt Open 2024;5(12):1081–1091

Aims. The transepicondylar axis is a well-established reference for the determination of femoral component rotation in total knee arthroplasty (TKA). However, when severe bone loss is present in the femoral condyles, rotational alignment can be more complicated. There is a lack of validated landmarks in the supracondylar region of the distal femur. Therefore, the aim of this study was to analyze the correlation between the surgical transepicondylar axis (sTEA) and the suggested dorsal cortex line (DCL) in the coronal plane and the inter- and intraobserver reliability of its CT scan measurement. Methods. A total of 75 randomly selected CT scans were measured by three experienced surgeons independently. The DCL was defined in the coronal plane as a tangent to the dorsal femoral cortex located 75 mm above the joint line in the frontal plane. The difference between sTEA and DCL was calculated. Descriptive statistics and angulation correlations were generated for the sTEA and DCL, as well as for the distribution of measurement error for intra- and inter-rater reliability. Results. The external rotation of the DCL to the sTEA was a mean of 9.47° (SD 3.06°), and a median of 9.2° (IQR 7.45° to 11.60°), with a minimum value of 1.7° and maximum of 16.3°. The measurements of the DCL demonstrated very good to excellent test-retest and inter-rater reliability coefficients (intraclass correlation coefficient 0.80 to 0.99). Conclusion. This study reveals a correlation between the sTEA and the DCL. Overall, 10° of external rotation of the dorsal femoral cortical bone to the sTEA may serve as a reliable landmark for initial position of the femoral component. Surgeons should be aware that there are outliers in this study in up to 17% of the measurements, which potentially could result in deviations of femoral component rotation. Cite this article: Bone Jt Open 2024;5(12):1067–1071

The December 2024 Knee Roundup. 360. looks at: Unicompartmental knee arthroplasty and total knee arthroplasty in the same patient?; Lateral unicompartmental knee arthroplasty: is it a good option?; The fate of the unresurfaced patellae in contemporary total knee arthroplasty: early- to mid-term results; Tibial baseplate migration is not associated with change in PROMs and clinical scores after total knee arthroplasty; Unexpected positive intraoperative cultures in aseptic revision knee arthroplasty: what effect does this have?; Kinematic or mechanical alignment in total knee arthroplasty surgery?; Revision total knee arthroplasty achieves minimal clinically important difference faster than primary total knee arthroplasty; Outcomes after successful DAIR for periprosthetic joint infection in total knee arthroplasty

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