Aims. The aim of this study was to screen the entire genome for genetic markers associated with risk for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injury. Methods. Genome-wide association (GWA) analyses were performed using data from the Kaiser Permanente Research Board (KPRB) and the UK Biobank. ACL and PCL injury cases were identified based on electronic health records from KPRB and the UK Biobank. GWA analyses from both cohorts were tested for ACL and PCL injury using a logistic regression model adjusting for sex, height, weight, age at enrolment, and race/ethnicity using allele counts for single nucleotide polymorphisms (SNPs). The data from the two GWA studies were combined in a meta-analysis. Candidate genes previously reported to show an association with ACL injury in athletes were also tested for association from the meta-analysis data from the KPRB and the UK Biobank GWA studies. Results. There was a total of 2,214 cases of ACL and PCL injury and 519,869 controls within the two cohorts, with three loci demonstrating a genome-wide significant association in the meta-analysis: INHBA, AEBP2, and LOC101927869. Of the eight candidate genes previously studied in the literature, six were present in the current dataset, and only COL3A1 (rs1800255) showed a significant association (p = 0.006). Conclusion. Genetic markers in three novel loci in this study and one previously-studied candidate gene were identified as potential risk factors for ACL and PCL injury and deserve further validation and investigation of molecular mechanisms. Cite this article: Bone Jt Open 2021;2(6):414–421

Aims. The objective of this study is to assess the use of ultrasound (US) as a radiation-free imaging modality to reconstruct 3D anatomy of the knee for use in preoperative templating in knee arthroplasty. Methods. Using an US system, which is fitted with an electromagnetic (EM) tracker that is integrated into the US probe, allows 3D tracking of the probe, femur, and tibia. The raw US radiofrequency (RF) signals are acquired and, using real-time signal processing, bone boundaries are extracted. Bone boundaries and the tracking information are fused in a 3D point cloud for the femur and tibia. Using a statistical shaping model, the patient-specific surface is reconstructed by optimizing bone geometry to match the point clouds. An accuracy analysis was conducted for 17 cadavers by comparing the 3D US models with those created using CT. US scans from 15 users were compared in order to examine the effect of operator variability on the output. Results. The results revealed that the US bone models were accurate compared with the CT models (root mean squared error (RM)S: femur, 1.07 mm (SD 0.15); tibia, 1.02 mm (SD 0.13). Additionally, femoral landmarking proved to be accurate (transepicondylar axis: 1.07° (SD 0.65°); posterior condylar axis: 0.73° (SD 0.41°); distal condylar axis: 0.96° (SD 0.89°); medial anteroposterior (AP): 1.22 mm (SD 0.69); lateral AP: 1.21 mm (SD 1.02)). Tibial landmarking errors were slightly higher (posterior slope axis: 1.92° (SD 1.31°); and tubercle axis: 1.91° (SD 1.24°)). For implant sizing, 90% of the femora and 60% of the tibiae were sized correctly, while the remainder were only one size different from the required implant size. No difference was observed between moderate and skilled users. Conclusion. The 3D US bone models were proven to be closely matched compared with CT and suitable for preoperative planning. The 3D US is radiation-free and offers numerous clinical opportunities for bone visualization rapidly during clinic visits, to enable preoperative planning with implant sizing. There is potential to extend its application to 3D dynamic ligament balancing, and intraoperative registration for use with robots and navigation systems. Cite this article: Bone Joint J 2021;103-B(6 Supple A):81–86

Aims. Metaphyseal tritanium cones can be used to manage the tibial bone loss commonly encountered at revision total knee arthroplasty (rTKA). Tibial stems provide additional fixation and are generally used in combination with cones. The aim of this study was to examine the role of the stems in the overall stability of tibial implants when metaphyseal cones are used for rTKA. Methods. This computational study investigates whether stems are required to augment metaphyseal cones at rTKA. Three cemented stem scenarios (no stem, 50 mm stem, and 100 mm stem) were investigated with 10 mm-deep uncontained posterior and medial tibial defects using four loading scenarios designed to mimic activities of daily living. Results. Small micromotions (mean < 12 µm) were found to occur at the bone-implant interface for all loading cases with or without a stem. Stem inclusion was associated with lower micromotion, however these reductions were too small to have any clinical significance. Peak interface micromotion, even when the cone is used without a stem, was too small to effect osseointegration. The maximum difference occurred with stair descent loading. Stress concentrations in the bone occurred around the inferior aspect of each implant, with the largest occurring at the end of the long stem; these may lead to end-of-stem pain. Stem use is also found to result in stress shielding in the bone along the stem. Conclusion. When a metaphyseal cone is used at rTKA to manage uncontained posterior or medial defects of up to 10 mm depth, stem use may not be necessary. Cite this article:Bone Joint Res. 2020;9(4):162–172

Aims. This study aims to determine the proportion of patients with end-stage knee osteoarthritis (OA) possibly suitable for partial (PKA) or combined partial knee arthroplasty (CPKA) according to patterns of full-thickness cartilage loss and anterior cruciate ligament (ACL) status. Methods. A cross-sectional analysis of 300 consecutive patients (mean age 69 years (SD 9.5, 44 to 91), mean body mass index (BMI) 30.6 (SD 5.5, 20 to 53), 178 female (59.3%)) undergoing total knee arthroplasty (TKA) for Kellgren-Lawrence grade ≥ 3 knee OA was conducted. The point of maximal tibial bone loss on preoperative lateral radiographs was determined as a percentage of the tibial diameter. At surgery, Lachman’s test and ACL status were recorded. The presence of full-thickness cartilage loss within 16 articular surface regions (two patella, eight femoral, six tibial) was recorded. Results. According to articular cartilage loss and ACL status, 195/293 (67%) were suitable for PKA or CPKA: medial unicompartmental knee arthroplasty (UKA) 97/293 (33%); lateral UKA 25 (9%); medial bicompartmental arthroplasty 31 (11%); lateral bicompartmental arthroplasty 12 (4%); bicondylar-UKA 23 (8%); and patellofemoral arthroplasty (PFA) seven (2%). The ACL was intact in 166 (55%), frayed in 82 (27%), disrupted in 12 (4%), and absent in 33 (11%). Lachman testing was specific (97%) but poorly sensitive (38%) for disrupted/absent ACLs. The point of maximal tibial bone loss showed good interclass correlation (ICC 0.797, 0.73 to 0.85 95% confidence interval (CI); p < 0.001) and was more posterior when the ACL was absent. Maximum tibial bone loss occurring at > 55% of the anterior to posterior distance predicted ACL absence with 93% sensitivity and 91% specificity (area under the curve 0.97 (0.94 to 0.99 95% CI; p < 0.001). Conclusion. ACL status can be reliably determined from a lateral radiograph using the location of maximal tibial bone loss. According to regions of cartilage loss and ACL status, two-thirds of patients with end-stage knee OA could potentially be treated with PKA or CPKA. Cite this article: Bone Joint J 2020;102-B(6):716–726

Aims. The hip’s capsular ligaments passively restrain extreme range of movement (ROM) by wrapping around the native femoral head/neck. We determined the effect of hip resurfacing arthroplasty (HRA), dual-mobility total hip arthroplasty (DM-THA), conventional THA, and surgical approach on ligament function. Materials and Methods. Eight paired cadaveric hip joints were skeletonized but retained the hip capsule. Capsular ROM restraint during controlled internal rotation (IR) and external rotation (ER) was measured before and after HRA, DM-THA, and conventional THA, with a posterior (right hips) and anterior capsulotomy (left hips). Results. Hip resurfacing provided a near-native ROM with between 5° to 17° increase in IR/ER ROM compared with the native hip for the different positions tested, which was a 9% to 33% increase. DM-THA generated a 9° to 61° (18% to 121%) increase in ROM. Conventional THA generated a 52° to 100° (94% to 199%) increase in ROM. Thus, for conventional THA, the capsule function that exerts a limit on ROM is lost. It is restored to some extent by DM-THA, and almost fully restored by hip resurfacing. In positions of low flexion/extension, the posterior capsulotomy provided more normal function than the anterior, possibly because the capsule was shortened during posterior repair. However, in deep flexion positions, the anterior capsulotomy functioned better. Conclusion. Native head-size and capsular repair preserves capsular function after arthroplasty. The anterior and posterior approach differentially affect postoperative biomechanical function of the capsular ligaments. Cite this article: Bone Joint J 2019;101-B:426–434

Aims. A variety of surgical approaches are used for total hip arthroplasty (THA), all with reported advantages and disadvantages. A number of common complications can occur following THA regardless of the approach used. The purpose of this study was to compare five commonly used surgical approaches with respect to the incidence of surgery-related complications. Patients and Methods. The electronic medical records of all patients who underwent primary elective THA at a single large-volume arthroplasty centre, between 2011 and 2016, with at least two years of follow-up, were reviewed. After exclusion, 3574 consecutive patients were included in the study. There were 1571 men (44.0%) and 2003 women (56.0%). Their mean age and body mass index (BMI) was 63.0 years (. sd. 11.8) and 29.1 kg/m. 2. (. sd. 6.1), respectively. Data gathered included the age of the patient, BMI, the American Society of Anesthesiologists (ASA) score, estimated blood loss (EBL), length of stay (LOS), operating time, the presence of intra- or postoperative complications, type of complication, and the surgical approach. The approaches used during the study were posterior, anterior, direct lateral, anterolateral, and the northern approach. The complications that were recorded included prolonged wound drainage without infection, superficial infection, deep infection, dislocation, aseptic loosening, and periprosthetic fracture. Finally, the need for re-operation was recorded. Means were compared using analysis of variance (ANOVA) and Student’s t-tests where appropriate and proportions were compared using the chi-squared test. Results. A total of 248 patients had 263 complications related to the surgery, with an incidence of 6.94%. The anterior approach had the highest incidence of complications (8.5% (113/1329)) and the posterior approach had the lowest, at 5.85% (97/1657; p = 0.006). Most complications were due to deep infection (22.8%), periprosthetic fracture (22.4%), and prolonged wound drainage (21.3%). The rate of dislocation was 0.84% (14/1657) with the posterior approach and 1.28% (17/1329) with the anterior approach (p = 0.32). Conclusion. Overall, THA has a relatively low complication rate. However, the surgical approach plays a role in the incidence of complications. We found that the posterior approach had a significantly lower overall complication rate compared with the anterior approach, with an equal dislocation rate. Periprosthetic fracture and surgical site infection contributed most to the early complication rates. Cite this article: Bone Joint J 2019;101-B:646–651

Aims. To evaluate the perioperative complications associated with total en bloc spondylectomy (TES) in patients with spinal tumours, based on the extent and level of tumour resection. Methods. In total, 307 patients who underwent TES in a single centre were reviewed retrospectively. There were 164 male and 143 female patients with a mean age at the time of surgery of 52.9 years (SD 13.3). A total of 225 patients were operated on for spinal metastases, 34 for a malignant primary tumour, 41 for an aggressive benign tumour, and seven with a primary of unknown origin. The main lesion was located in the thoracic spine in 213, and in the lumbar spine in 94 patients. There were 97 patients who underwent TES for more than two consecutive vertebrae. Results. Major and minor perioperative complications were observed in 122 (39.7%) and 84 (27.4%) patients respectively. The breakdown of complications was as follows: bleeding more than 2,000 ml in 60 (19.5%) patients, hardware failure in 82 (26.7%), neurological in 46 (15.0%), surgical site infection in 23 (7.5%), wound dehiscence in 16 (5.2%), cerebrospinal fluid leakage in 45 (14.7%), respiratory in 52 (16.9%), cardiovascular in 11 (3.6%), digestive in 19 (6.2%)/ The mortality within two months of surgery was four (1.3%). The total number of complications per operation were 1.01 (SD 1.0) in the single vertebral resection group and 1.56 (SD 1.2) in the group with more than two vertebral resections. Cardiovascular and respiratory complications, along with hardware failure were statistically higher in the group who had more than two vertebrae resected. Also, in this group the amount of bleeding in patients with a lumbar lesion or respiratory complication in patients with a thoracic lesion, were statistically higher. Multivariate analysis showed that using a combined anterior and posterior approach, when more than two vertebral resections were significant independent factors. Conclusion. The characteristics of perioperative complications after TES were different depending on the extent and level of the tumour resection. In addition to preoperative clinical and pathological factors, it is therefore important to consider these factors in patients who undergo en bloc resection for spinal tumours. Cite this article: Bone Joint J 2021;103-B(5):976–983

Aims. The purpose of this study was to compare the radiological outcomes of manual versus robotic-assisted medial unicompartmental knee arthroplasty (UKA). Methods. Postoperative radiological outcomes from 86 consecutive robotic-assisted UKAs (RAUKA group) from a single academic centre were retrospectively reviewed and compared to 253 manual UKAs (MUKA group) drawn from a prior study at our institution. Femoral coronal and sagittal angles (FCA, FSA), tibial coronal and sagittal angles (TCA, TSA), and implant overhang were radiologically measured to identify outliers. Results. When assessing the accuracy of RAUKAs, 91.6% of all alignment measurements and 99.2% of all overhang measurements were within the target range. All alignment and overhang targets were simultaneously met in 68.6% of RAUKAs. When comparing radiological outcomes between the RAUKA and MUKA groups, statistically significant differences were identified for combined outliers in FCA (2.3% vs 12.6%; p = 0.006), FSA (17.4% vs 50.2%; p < 0.001), TCA (5.8% vs 41.5%; p < 0.001), and TSA (8.1% vs 18.6%; p = 0.023), as well as anterior (0.0% vs 4.7%; p = 0.042), posterior (1.2% vs 13.4%; p = 0.001), and medial (1.2% vs 14.2%; p < 0.001) overhang outliers. Conclusion. Robotic system navigation decreases alignment and overhang outliers compared to manual UKA. Given the association between component placement errors and revision in UKA, this strong significant improvement in accuracy may improve implant survival. Level of Evidence: III. Cite this article: Bone Jt Open 2021;2-3:191–197

Aims. Highly cross-linked polyethylene (HXLPE) has greatly improved the durability of total hip arthroplasty (THA) in young patients because of its improved wear characteristics. Few studies have followed this population into the second decade, and therefore the purpose of this investigation was to evaluate the clinical outcome for THA patients 50 years of age and younger at a minimum of 15 years postoperatively. The second purpose was to evaluate the radiological findings secondary to wear or mechanical failure of the implant. Methods. Between October 1999 and December 2005, 105 THAs were performed in 95 patients (53 female, 42 male) aged 50 years and younger (mean 42 years (20 to 50)). There were 87 patients (96 hips) that were followed for a minimum of 15 years (mean 17.3 years (15 to 21)) for analysis. Posterior approach was used with cementless fixation with a median head size of 28 mm. HXLPE was the acetabular bearing for all hips. Radiographs were evaluated for polyethylene wear, radiolucent lines, and osteolysis. Results. Clinical outcomes showed significant improvement of mean Harris Hip Scores from 52.8 (SD 13.5) preoperatively to 94.8 (SD 7.6) postoperatively. One hip was revised for recurrent instability, and there were no infections. No hips were revised for mechanical loosening or osteolysis. Mean polyethylene linear wear was 0.04 mm/year and volumetric wear was 6.22 mm. 3. /year, with no significant differences between head size or material. Osteolysis was not present in any of the hips. Conclusion. The use of HXLPE in THA for patients aged 50 years and younger has performed exceptionally well without evidence of significant wear causing mechanical loosening or necessitating revision. The radiolucent lines of the acetabular component must be followed to determine the prognostic significance. This investigation represents the longest clinical follow-up of a large, consecutive cohort of patients aged 50 years or younger with THA using HXLPE. This long-term analysis found negligible polyethylene wear, no incidence of aseptic loosening, and excellent clinical outcomes at and beyond 15 years of follow-up. Cite this article: Bone Joint J 2021;103-B(7 Supple B):78–83

Aims. No randomized comparative study has compared the extensile lateral approach (ELA) and sinus tarsi approach (STA) for Sanders type 2 calcaneal fractures. This randomized comparative study was conducted to confirm whether the STA was prone to fewer wound complications than the ELA. Methods. Between August 2013 and August 2018, 64 patients with Sanders type 2 calcaneus fractures were randomly assigned to receive surgical treatment by the ELA (32 patients) and STA (32 patients). The primary outcome was development of wound complications. The secondary outcomes were postoperative complications, pain scored of a visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, 36-item Short Form health survey, operative duration, subtalar joint range of motion (ROM), Böhler’s angle and calcaneal width, and posterior facet reduction. Results. Although four patients (12.5%) in the ELA groups and none in the STA group experienced complications, the difference was not statistically significant (p = 0.113). VAS and AOFAS score were significantly better in the STA group than in the ELA group at six months (p = 0.017 and p = 0.021), but not at 12 months (p = 0.096 and p = 0.200) after surgery. The operation time was significantly shorter in the STA group than in the ELA group (p < 0.001). The subtalar joint ROM was significantly better in the STA group (p = 0.015). Assessment of the amount of postoperative reduction compared with the uninjured limb showed significant restoration of calcaneal width in the ELA group compared with that in the STA group (p < 0.001). Conclusion. The ELA group showed higher frequency of wound complications than the STA group for Sanders type 2 calcaneal fractures even though this was not statistically significant. Cite this article: Bone Joint J 2021;103-B(2):286–293

Aims. The direct posterior approach with subperiosteal dissection of the paraspinal muscles from the vertebrae is considered to be the standard approach for the surgical treatment of adolescent idiopathic scoliosis (AIS). We investigated whether or not a minimally-invasive surgery (MIS) technique could offer improved results. Methods. Consecutive AIS patients treated with an MIS technique at two tertiary centres from June 2013 to March 2016 were retrospectively included. Preoperative patient deformity characteristics, perioperative parameters, power of deformity correction, and complications were studied. A total of 93 patients were included. The outcome of the first 25 patients and the latter 68 were compared as part of our safety analysis to examine the effect of the learning curve. Results. In the first 25 cases, with a mean follow-up of 5.6 years (standard deviation (SD) 0.4), the mean preoperative major Cobb angle was 57.6° (SD 9.8°) and significantly corrected to mean 15.4° (SD 5.6°, 73% curve correction). The mean preoperative T5-T12 was 26.2 (SD 12.8) and significantly increased to mean 32.9 (SD 8.3). Both frontal and sagittal plane correction was conserved two years after surgery. The rate of perioperative complications was 12% and three further complications occurred (three deep delayed infection). In the latter cases, 68 patients were included with a mean follow-up time of three years (SD 0.6). The mean preoperative major Cobb angle was 58.4° (SD 9.2°) and significantly corrected to mean 20.4° (SD 7.3°).The mean preoperative T5-T12 kyphosis was 26.6° (SD 12.8°) and was significantly increased to mean 31.4° (SD 8.3°). Both frontal and sagittal correction was conserved two years after surgery. The perioperative (30 day) complication rate was 1.4%. Two (2.9%) additional complications occurred in two patients. Conclusion. MIS for AIS is associated with a significant correction of spine deformity in the frontal and sagittal planes, together with low estimated blood loss and short length of stay. The perioperative complication rate seems to be lower compared with the standard open technique based on the literature data. The longer-term safety of MIS for AIS needs to be documented with a larger cohort and compared with the standard posterior approach. Cite this article: Bone Joint J 2020;102-B(4):506–512

Aims. The primary aim of this study was to define and quantify three new measurements to indicate the position of the greater trochanter. Secondary aims were to define ‘functional antetorsion’ as it relates to abductor function in populations both with and without torsional abnormality. Patients and Methods. Three new measurements, functional antetorsion, posterior tilt, and posterior translation of the greater trochanter, were assessed from 61 CT scans of cadaveric femurs, and their reliability determined. These measurements and their relationships were also evaluated in three groups of patients: a control group (n = 22), a ‘high-antetorsion’ group (n = 22) and a ‘low-antetorsion’ group (n = 10). Results. In the cadaver group, the mean anatomical antetorsion was 14.7° (. sd. 8.5; 0 to 36.5) and the functional antetorsion 21.5° (. sd. 8.1; 3.6 to 44.3): the posterior tilt was 73.3° (. sd. 10.8; 46.9 to 88.7) and the posterior translation 0.59 (. sd. 0.2; 0.2 to 0.9). These measurements had excellent intra and interobserver agreement with a range from 0.93 to 0.99. When the anatomical antetorsion decreased, the greater trochanter was more tilted and translated posteriorly in relation to the axis of the femoral neck, and the difference between functional and anatomical antetorsion increased. The results the three patient groups were similar to those of the cadaver group. Conclusion. The position of the greater trochanter and functional antetorsion varied with anatomical antetorsion. In the surgical management of femoral retrotorsion, subtrochanteric osteotomy can result in an excessively posterior position of the greater trochanter and an increase in functional antetorsion. Cite this article: Bone Joint J 2018;100-B:712–19

Aims

To describe the epidemiology of acetabular fractures including patient characteristics, injury mechanisms, fracture patterns, treatment, and mortality.

Aims. Severe spinal deformity in growing patients often requires surgical management. We describe the incidence of spinal deformity surgery in a National Health Service. Methods. Descriptive study of prospectively collected data. Clinical data of all patients undergoing surgery for spinal deformity between 2005 and 2018 was collected, compared to the demographics of the national population, and analyzed by underlying aetiology. Results. Our cohort comprised 2,205 patients; this represents an incidence of 14 per 100,000 individuals among the national population aged between zero and 18 years. There was an increase in mean annual incidence of spinal deformity surgery across the study period from 9.6 (7.2 to 11.7) per 100,000 individuals in 2005 to 2008, to 17.9 (16.1 to 21.5) per 100,000 individuals in 2015 to 2018 (p = 0.001). The most common cause of spinal deformity was idiopathic scoliosis accounting for 56.7% of patients. There was an increase in mean incidence of surgery for adolescent idiopathic scoliosis (AIS) (from 4.4 (3.1 to 5.9) to 9.8 (9.1 to 10.8) per 100,000 individuals; p < 0.001), juvenile idiopathic scoliosis (JIS) (from 0.2 (0.1 to 0.4) to one (0.5 to 1.3) per 100,000 individuals; p = 0.009), syndromic scoliosis (from 0.7 (0.3 to 0.9) to 1.7 (1.2 to 2.4) per 100,000 individuals; p = 0.044), Scheuermann’s kyphosis (SK) (from 0.2 (0 to 0.7) to 1.2 (1.1 to 1.3) per 100,000 individuals; p = 0.001), and scoliosis with intraspinal abnormalities (from 0.04 (0 to 0.08) to 0.6 (0.5 to 0.8) per 100,000 individuals; p = 0.008) across the study period. There was an increase in mean number of posterior spinal fusions performed each year from mean 84.5 (51 to 108) in 2005 to 2008 to 182.5 (170 to 210) in 2015 to 2018 (p < 0.001) and a reduction in mean number of growing rod procedures from 45.5 (18 to 66) in 2005 to 2008 to 16.8 (11 to 24) in 2015 to 2018 (p = 0.046). Conclusion. The incidence of patients with spinal deformity undergoing surgery increased from 2005 to 2018. This was largely attributable to an increase in surgical patients with adolescent idiopathic scoliosis. Paediatric spinal deformity was increasingly treated by posterior spinal fusion, coinciding with a decrease in the number of growing rod procedures. These results can be used to plan paediatric spinal deformity services but also evaluate preventative strategies and research, including population screening

Aims. Minimally invasive fixation of pelvic fragility fractures is recommended to reduce pain and allow early mobilization. The purpose of this study was to evaluate the outcome of two different stabilization techniques in bilateral fragility fractures of the sacrum (BFFS). Methods. A non-randomized, prospective study was carried out in a level 1 trauma centre. BFFS in 61 patients (mean age 80 years (SD 10); four male, 57 female) were treated surgically with bisegmental transsacral stablization (BTS; n = 41) versus spinopelvic fixation (SP; n = 20). Postoperative full weightbearing was allowed. The outcome was evaluated at two timepoints: discharge from inpatient treatment (TP1; Fitbit tracking, Zebris stance analysis), and ≥ six months (TP2; Fitbit tracking, Zebris analysis, based on modified Oswestry Disability Index (ODI), Majeed Score (MS), and the 12-Item Short Form Survey 12 (SF-12). Fracture healing was assessed by CT. The primary outcome parameter of functional recovery was the per-day step count; the secondary parameter was the subjective outcome assessed by questionnaires. Results. Overall, no baseline differences were observed between the BTS and SP cohorts. In total, 58 (BTS = 19; SP = 39) and 37 patients (BTS = 14; SP = 23) could be recruited at TP1 and TP2, respectively. Mean steps per day at TP1 were median 308 (248 to 434) in the BTS group and 254 (196 to 446) in the SP group. At TP2, median steps per day were 3,759 (2,551 to 3,926) in the BTS group and 3,191 (2,872 to 3,679) in the SP group, each with no significant difference. A significant improvement was observed in each group (p < 0.001) between timepoints. BTS patients obtained better results than SP patients in ODI (p < 0.030), MS (p = 0.007), and SF-12 physical status (p = 0.006). In all cases, CT showed sufficient fracture healing of the posterior ring. Conclusion. Both groups showed significant outcome improvement and sufficient fracture healing. Both techniques can be recommended for BFFS, although BTS was superior with respect to subjective outcome. Step-count tracking represents a reliable method to evaluate the mobility level. Cite this article: Bone Joint J 2021;103-B(3):462–468

Aims. This study, using a surgeon-maintained database, aimed to explore the risk factors for surgery-related complications in patients undergoing primary cervical spine surgery for degenerative diseases. Methods. We studied 5,015 patients with degenerative cervical diseases who underwent primary cervical spine surgery from 2012 to 2018. We investigated the effects of diseases, surgical procedures, and patient demographics on surgery-related complications. As subcategories, the presence of cervical kyphosis ≥ 10°, the presence of ossification of the posterior longitudinal ligament (OPLL) with a canal-occupying ratio ≥ 50%, and foraminotomy were selected. The surgery-related complications examined were postoperative upper limb palsy (ULP) with a manual muscle test (MMT) grade of 0 to 2 or a reduction of two grade or more in the MMT, neurological deficit except ULP, dural tear, dural leakage, surgical-site infection (SSI), and postoperative haematoma. Multivariate logistic regression analysis was performed. Results. The significant risk factors (p < 0.050) for ULP were OPLL (odds ratio (OR) 1.88, 95% confidence interval (CI) 1.29 to 2.75), foraminotomy (OR 5.38, 95% CI 3.28 to 8.82), old age (per ten years, OR 1.18, 95% CI 1.03 to 1.36), anterior spinal fusion (OR 2.85, 95% CI 1.53 to 5.34), and the number of operated levels (OR 1.25, 95% CI 1.11 to 1.40). OPLL was also a risk factor for neurological deficit except ULP (OR 5.84, 95% CI 2.80 to 12.8), dural tear (OR 1.94, 95% CI 1.11 to 3.39), and dural leakage (OR 3.15, 95% CI 1.48 to 6.68). Among OPLL patients, dural tear and dural leakage were frequently observed in those with a canal-occupying ratio ≥ 50%. Cervical rheumatoid arthritis (RA) was a risk factor for SSI (OR 10.1, 95% CI 2.66 to 38.4). Conclusion. The high risk of ULP, neurological deficit except ULP, dural tear, and dural leak should be acknowledged by clinicians and OPLL patients, especially in those patients with a canal-occupying ratio ≥ 50%. Foraminotomy and RA were dominant risk factors for ULP and SSI, respectively. An awareness of these risks may help surgeons to avoid surgery-related complications in these conditions. Cite this article: Bone Joint J 2021;103-B(1):157–163

Aims

Post-traumatic periprosthetic acetabular fractures are rare but serious. Few studies carried out on small cohorts have reported them in the literature. The aim of this work is to describe the specific characteristics of post-traumatic periprosthetic acetabular fractures, and the outcome of their surgical treatment in terms of function and complications.

Aims

The aim of this study is to evaluate whether acetabular retroversion (AR) represents a structural anatomical abnormality of the pelvis or is a functional phenomenon of pelvic positioning in the sagittal plane, and to what extent the changes that result from patient-specific functional position affect the extent of AR.

Aims

Professional dancers represent a unique patient population in the setting of hip arthroplasty, given the high degree of hip strength and mobility required by their profession. We sought to determine the clinical outcomes and ability to return to professional dance after total hip arthroplasty (THA) or hip resurfacing arthroplasty (HRA).

Aims

Periacetabular osteotomy (PAO) is widely recognized as a demanding surgical procedure for acetabular reorientation. Reports about the learning curve have primarily focused on complication rates during the initial learning phase. Therefore, our aim was to assess the PAO learning curve from an analytical perspective by determining the number of PAOs required for the duration of surgery to plateau and the accuracy to improve.