Aims

This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry.

Aims. The aim of this study was to report the patterns of symptoms and insufficiency fractures in patients with tumour-induced osteomalacia (TIO) to allow the early diagnosis of this rare condition. Methods. The study included 33 patients with TIO who were treated between January 2000 and June 2022. The causative tumour was detected in all patients. We investigated the symptoms and evaluated the radiological patterns of insufficiency fractures of the rib, spine, and limbs. Results. The mean age of the patients was 57 years (24 to 87), and the mean duration of pain from onset to time of presentation was 3.9 years (0.75 to 23). The primary symptoms were low back pain (ten patients), chest wall pain (eight patients), and hip pain (eight patients). There were symptoms at more sites at the time of presentation compared with that at the time of the onset of symptoms. Bone scans showed the uptake of tracer in the rib (100%), thoracic and lumbar vertebrae (83%), proximal femur (62%), distal femur (66%), and proximal tibia (72%). Plain radiographs or MRI scans identified femoral neck fractures in 14 patients, subchondral insufficiency fractures of the femoral head and knee in ten and six patients, respectively, distal femoral fractures in nine patients, and proximal tibial fractures in 12 patients. Thoracic or lumbar vertebral fractures were identified in 23 of 29 patients (79.3%) when using any imaging study, and a biconcave deformity was the most common type of fracture. Conclusion. Insufficiency fractures in patients with TIO caused spinal pain, chest wall pain, and periarticular pain in the lower limbs. Vertebral fractures tended to be biconcave deformities, and periarticular fractures of the hips and knees included subchondral insufficiency fractures and epiphyseal or metaphyseal fractures. In patients with a tumour, the presence of one or more of these symptoms and an insufficiency fracture should suggest the diagnosis of TIO. Cite this article: Bone Joint J 2023;105-B(5):568–574

Aims. Children with spinal dysraphism can develop various musculoskeletal deformities, necessitating a range of orthopaedic interventions, causing significant morbidity, and making considerable demands on resources. This systematic review aimed to identify what outcome measures have been reported in the literature for children with spinal dysraphism who undergo orthopaedic interventions involving the lower limbs. Methods. A PROSPERO-registered systematic literature review was performed following PRISMA guidelines. All relevant studies published until January 2023 were identified. Individual outcomes and outcome measurement tools were extracted verbatim. The measurement tools were assessed for reliability and validity, and all outcomes were grouped according to the Outcome Measures Recommended for use in Randomized Clinical Trials (OMERACT) filters. Results. From 91 eligible studies, 27 individual outcomes were identified, including those related to clinical assessment (n = 12), mobility (n = 4), adverse events (n = 6), investigations (n = 4), and miscellaneous (n = 1). Ten outcome measurement tools were identified, of which Hoffer’s Functional Ambulation Scale was the most commonly used. Several studies used unvalidated measurement tools originally developed for other conditions, and 26 studies developed new measurement tools. On the OMERACT filter, most outcomes reported pathophysiology and/or the impact on life. There were only six patient- or parent-reported outcomes, and none assessed the quality of life. Conclusion. The outcomes that were reported were heterogenous, lack validation and failed to incorporate patient or family perceptions. Until outcomes can be reported unequivocally, research in this area will remain limited. Our findings should guide the development of a core outcome set, which will allow consistency in the reporting of outcomes for this condition. Cite this article: Bone Joint J 2024;106-B(3):277–285

Aims. The Chopart joint complex is a joint between the midfoot and hindfoot. The static and dynamic support system of the joint is critical for maintaining the medial longitudinal arch of the foot. Any dysfunction leads to progressive collapsing flatfoot deformity (PCFD). Often, the tibialis posterior is the primary cause; however, contrary views have also been expressed. The present investigation intends to explore the comprehensive anatomy of the support system of the Chopart joint complex to gain insight into the cause of PCFD. Methods. The study was conducted on 40 adult embalmed cadaveric lower limbs. Chopart joint complexes were dissected, and the structures supporting the joint inferiorly were observed and noted. Results. The articulating bones exhibit features like a cuboid shelf and navicular beak, which appear to offer inferior support to the joint. The expanse of the spring ligament complex is more medial than inferior, while the superomedial part is more extensive than the intermediate and inferoplantar parts. The spring ligament is reinforced by the tendons in the superomedial part (the main tendon of tibialis posterior), the inferomedial part (the plantar slip of tibialis posterior), and the master knot of Henry positioned just inferior to the gap between the inferomedial and inferoplantar bundles. Conclusion. This study highlights that the medial aspect of the talonavicular articulation has more extensive reinforcement in the form of superomedial part of spring ligament and tibialis posterior tendon. The findings are expected to prompt further research in weightbearing settings on the pathogenesis of flatfoot. Cite this article: Bone Jt Open 2024;5(4):335–342

Aims. This study aims to estimate economic outcomes associated with 30-day deep surgical site infection (SSI) from closed surgical wounds in patients with lower limb fractures following major trauma. Methods. Data from the Wound Healing in Surgery for Trauma (WHiST) trial, which collected outcomes from 1,547 adult participants using self-completed questionnaires over a six-month period following major trauma, was used as the basis of this empirical investigation. Associations between deep SSI and NHS and personal social services (PSS) costs (£, 2017 to 2018 prices), and between deep SSI and quality-adjusted life years (QALYs), were estimated using descriptive and multivariable analyses. Sensitivity analyses assessed the impact of uncertainty surrounding components of the economic analyses. Results. Compared to participants without deep SSI, those with deep SSI had higher mean adjusted total NHS and PSS costs (adjusted mean difference £1,577 (95% confidence interval (CI) -951 to 4,105); p = 0.222), and lower mean adjusted QALYs (adjusted mean difference -0.015 (95% CI -0.032 to 0.002); p = 0.092) over six months post-injury, but this difference was not statistically significant. The results were robust to the sensitivity analyses performed. Conclusion. This study found worse economic outcomes during the first six months post-injury in participants who experience deep SSI following orthopaedic surgery for major trauma to the lower limb. However, the increase in cost associated with deep SSI was less than previously reported in the orthopaedic trauma literature. Cite this article: Bone Jt Open 2022;3(5):398–403

Aims. Chronic osteomyelitis (COM) of the lower limb in adults can be surgically managed by either limb reconstruction or amputation. This scoping review aims to map the outcomes used in studies surgically managing COM in order to aid future development of a core outcome set. Methods. A total of 11 databases were searched. A subset of studies published between 1 October 2020 and 1 January 2011 from a larger review mapping research on limb reconstruction and limb amputation for the management of lower limb COM were eligible. All outcomes were extracted and recorded verbatim. Outcomes were grouped and categorized as per the revised Williamson and Clarke taxonomy. Results. A total of 3,303 records were screened, of which 99 studies were included. Most studies were case series (77/99; 78%) and assessed one method of reconstruction (68/99; 69%). A total of 511 outcomes were reported, which were grouped into 58 distinct outcomes. Overall, 143/511 of all outcomes (28%) were provided with a clear, in-text definition, and 231 outcomes (45%) had details reported of how and when they were measured. The most commonly reported outcome was ‘recurrence of osteomyelitis’ (62; 12%). The single-most patient-reported outcome measure was ‘pain’. Conclusion. This study has highlighted significant inconsistencies in the defining, reporting, and measuring of outcomes across studies investigating surgical management for chronic osteomyelitis of the lower limb in adults. Future studies should clearly report complete details of how outcomes are defined and measured, including timing. The development of a standardized core outcome set would be of significant benefit in order to allow evidence synthesis and comparison across studies. Cite this article: Bone Jt Open 2023;4(3):146–157

Aims. The aim of this study was to report the outcomes of patients with severe open fractures of the lower limb in the five years after they took part in the Wound management for Open Lower Limb Fracture (WOLLF) trial. Methods. The WOLLF trial compared standard dressings to negative pressure wound therapy (NPWT) applied at the end of the first surgical wound debridement, and patients were followed-up for 12 months. At 12 months, 170 of the original 460 participants agreed to take part in this medium-term follow-up study. Patients reported their Disability Rating Index (DRI) (0 to 100, where 100 is total disability) and health-related quality of life (HRQoL) using the EuroQol five-dimension three-level health questionnaire (EQ-5D-3L) annually by self-reported questionnaire. Further surgical interventions related to the open fracture were also recorded. Results. There was no evidence of a difference in patient-reported disability, HRQoL, or the need for further surgery between patients treated with NPWT versus standard dressings at five years. Considering the combined results for all participants, there was a small but statistically significant change in DRI scores over time (1.6 units per year; p = 0.005), but no evidence that EQ-5D-3L scores changed significantly during years two to five (p = 0.551). Conclusion. This study shows that the high levels of disability and reduced HRQoL reported by patients 12 months after severe open fractures of the lower limb persist in the medium term, with little evidence of improvement between years two and five. Cite this article: Bone Joint J 2022;104-B(5):633–639

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article: Bone Joint J 2021;103-B(5):822–827

Aims. The aims of this study were to report the outcomes of patients with a complex fracture of the lower limb in the five years after they took part in the Wound Healing in Surgery for Trauma (WHIST) trial. Methods. The WHIST trial compared negative pressure wound therapy (NPWT) dressings with standard dressings applied at the end of the first operation for patients undergoing internal fixation of a complex fracture of the lower limb. Complex fractures included periarticular fractures and open fractures when the wound could be closed primarily at the end of the first debridement. A total of 1,548 patients aged ≥ 16 years completed the initial follow-up, six months after injury. In this study we report the pre-planned analysis of outcome data up to five years. Patients reported their Disability Rating Index (DRI) (0 to 100, in which 100 = total disability), and health-related quality of life, chronic pain scores and neuropathic pain scores annually, using a self-reported questionnaire. Complications, including further surgery related to the fracture, were also recorded. Results. A total of 1,015 of the original patients (66%) provided at least one set of outcome data during the five years of follow-up. There was no evidence of a difference in patient-reported disability between the two groups at five years (NPWT group mean DRI 30.0 (SD 26.5), standard dressing group mean DRI 31.5 (SD 28.8), adjusted difference -0.86 (95% CI -4.14 to 2.40; p = 0.609). There was also no evidence of a difference in the complication rates at this time. Conclusion. We found no evidence of a difference in disability ratings between NPWT compared with standard wound dressings in the five years following the surgical treatment of a complex fracture of the lower limb. Patients in both groups reported high levels of persistent disability and reduced quality of life, with little evidence of improvement during this time. Cite this article: Bone Joint J 2024;106-B(8):858–864

Aims. The standard of surgical treatment for lower limb neoplasms had been characterized by highly interventional techniques, leading to severe kinetic impairment of the patients and incidences of phantom pain. Rotationplasty had arisen as a potent limb salvage treatment option for young cancer patients with lower limb bone tumours, but its impact on the gait through comparative studies still remains unclear several years after the introduction of the procedure. The aim of this study is to assess the effect of rotationplasty on gait parameters measured by gait analysis compared to healthy individuals. Methods. The MEDLINE, Scopus, and Cochrane databases were systematically searched without time restriction until 10 January 2022 for eligible studies. Gait parameters measured by gait analysis were the outcomes of interest. Results. Three studies were eligible for analyses. Compared to healthy individuals, rotationplasty significantly decreased gait velocity (-1.45 cm/sec; 95% confidence interval (CI) -1.98 to -0.93; p < 0.001), stride length (-1.20 cm; 95% CI -2.31 to -0.09; p < 0.001), cadence (-0.83 stride/min; 95% (CI -1.29 to -0.36; p < 0.001), and non-significantly increased cycle time (0.54 sec; 95% CI -0.42 to 1.51; p = 0.184). Conclusion. Rotationplasty is a valid option for the management of lower limb bone tumours in young cancer patients. Larger studies, with high patient accrual, refined surgical techniques, and well planned rehabilitation strategies, are required to further improve the reported outcomes of this procedure. Cite this article: Bone Jt Open 2023;4(11):817–824

Aims. Once knee arthritis and deformity have occurred, it is currently not known how to determine a patient’s constitutional (pre-arthritic) limb alignment. The purpose of this study was to describe and validate the arithmetic hip-knee-ankle (aHKA) algorithm as a straightforward method for preoperative planning and intraoperative restoration of the constitutional limb alignment in total knee arthroplasty (TKA). Methods. A comparative cross-sectional, radiological study was undertaken of 500 normal knees and 500 arthritic knees undergoing TKA. By definition, the aHKA algorithm subtracts the lateral distal femoral angle (LDFA) from the medial proximal tibial angle (MPTA). The mechanical HKA (mHKA) of the normal group was compared to the mHKA of the arthritic group to examine the difference, specifically related to deformity in the latter. The mHKA and aHKA were then compared in the normal group to assess for differences related to joint line convergence. Lastly, the aHKA of both the normal and arthritic groups were compared to test the hypothesis that the aHKA can estimate the constitutional alignment of the limb by sharing a similar centrality and distribution with the normal population. Results. There was a significant difference in means and distributions of the mHKA of the normal group compared to the arthritic group (mean -1.33° (SD 2.34°) vs mean -2.88° (SD 7.39°) respectively; p < 0.001). However, there was no significant difference between normal and arthritic groups using the aHKA (mean -0.87° (SD 2.54°) vs mean -0.77° (SD 2.84°) respectively; p = 0.550). There was no significant difference in the MPTA and LDFA between the normal and arthritic groups. Conclusion. The arithmetic HKA effectively estimated the constitutional alignment of the lower limb after the onset of arthritis in this cross-sectional population-based analysis. This finding is of significant importance to surgeons aiming to restore the constitutional alignment of the lower limb during TKA. Cite this article: Bone Jt Open 2021;2(5):351–358

Aims. To clarify the effectiveness of the induced membrane technique (IMT) using beta-tricalcium phosphate (β-TCP) for reconstruction of segmental bone defects by evaluating clinical and radiological outcomes, and the effect of defect size and operated site on surgical outcomes. Methods. A review of the medical records was conducted of consecutive 35 lower limbs (30 males and five females; median age 46 years (interquartile range (IQR) 40 to 61)) treated with IMT using β-TCP between 2014 and 2018. Lower Extremity Functional Score (LEFS) was examined preoperatively and at final follow-up to clarify patient-centered outcomes. Bone healing was assessed radiologically, and time from the second stage to bone healing was also evaluated. Patients were divided into ≥ 50 mm and < 50 mm defect groups and into femoral reconstruction, tibial reconstruction, and ankle arthrodesis groups. Results. There were ten and 25 defects in the femur and tibia, respectively. Median LEFS improved significantly from 8 (IQR 1.5 to 19.3) preoperatively to 63.5 (IQR 57 to 73.3) at final follow-up (p < 0.001). Bone healing was achieved in all limbs, and median time from the second stage to bone healing was six months (IQR 5 to 10). Median time to bone healing, preoperative LEFS, or postoperative LEFS did not differ significantly between the defect size groups or among the treatment groups. Conclusion. IMT using β-TCP provided satisfactory clinical and radiological outcomes for segmental bone defects in the lower limbs; surgical outcomes were not influenced by bone defect size or operated part. Cite this article: Bone Joint J 2021;103-B(3):456–461

Aims. To evaluate mid-to long-term patient-reported outcome measures (PROMs) of endoprosthetic reconstruction after resection of malignant tumours arising around the knee, and to investigate the risk factors for unfavourable PROMs. Methods. The medical records of 75 patients who underwent surgery between 2000 and 2020 were retrospectively reviewed, and 44 patients who were alive and available for follow-up (at a mean of 9.7 years postoperatively) were included in the study. Leg length discrepancy was measured on whole-leg radiographs, and functional assessment was performed with PROMs (Toronto Extremity Salvage Score (TESS) and Comprehensive Outcome Measure for Musculoskeletal Oncology Lower Extremity (COMMON-LE)) with two different aspects. The thresholds for unfavourable PROMs were determined using anchor questions regarding satisfaction, and the risk factors for unfavourable PROMs were investigated. Results. The thresholds for favourable TESS and COMMON were 64.8 and 70.4 points, respectively. Multivariate analysis showed that age at surgery (p = 0.004) and postoperative leg length discrepancy (p = 0.043) were significant risk factors for unfavourable TESS results, while age at surgery (p < 0.001) was a significant risk factor for unfavourable COMMON-LE results. Following receiver operating characteristic analysis, the threshold for both TESS and COMMON-LE was 29 years of age at surgery. Additionally, a leg length discrepancy of 8.2 mm was the threshold for unfavourable TESS. Conclusion. Patients aged > 29 years at the time of surgery require appropriate preoperative counselling and adequate postoperative physical and socioemotional support. Reconstruction equivalent to the length of the resected bone can reduce the risk of functional disabilities in daily living. Cite this article: Bone Jt Open 2023;4(12):906–913

Aims. To our knowledge, there is currently no information available about the rate of venous thromboembolism (VTE) or recommendations regarding chemoprophylaxis for patients whose lower limb is immobilized in a plaster cast. We report a retrospective case series assessing the rate of symptomatic VTE in patients treated with a lower limb cast. Given the complex, heterogeneous nature of this group of patients, with many risk factors for VTE, we hypothesized that the rate of VTE would be higher than in the general population. Patients and Methods. Patients treated with a lower limb cast between 2006 and 2018 were identified using plaster room records. Their electronic records and radiological reports were reviewed for details about their cast, past medical history, and any VTE recorded in our hospital within a year of casting. Results. There were 136 episodes of casting in 100 patients. The mean age was 55 years (22 to 91). The mean time in a cast was 45 days (five days to eight months). A total of 76 patients had neuropathy secondary to diabetes. No patient received chemical thromboprophylaxis while in a cast. One VTE (0.7% of casting episodes) was documented. This was confirmed by Doppler scan nine days after removing the cast. Conclusion. The frequency of VTE was higher than that of the general population (0.05%); this is most likely attributable to our patients’ apparent increase in VTE risk as suggested by The National Institute for Health and Care Excellence (NICE). These findings suggest that thromboprophylaxis is not routinely indicated in patients who undergo immobilization of the lower limb in a cast, although the risks of VTE should be assessed. While the cast itself does not pose an increased risk, other pathologies, such as active cancer, mean that each individual case needs to be considered on their merit. Cite this article: Bone Joint J 2019;101-B:691–694

Aims. The aim of this study was to estimate the cost-effectiveness of negative-pressure wound therapy (NPWT) in comparison with standard wound management after initial surgical wound debridement in adults with severe open fractures of the lower limb. Patients and Methods. An economic evaluation was conducted from the perspective of the United Kingdom NHS and Personal Social Services, based on evidence from the 460 participants in the Wound Management of Open Lower Limb Fractures (WOLLF) trial. Economic outcomes were collected prospectively over the 12-month follow-up period using trial case report forms and participant-completed questionnaires. Bivariate regression of costs (given in £, 2014 to 2015 prices) and quality-adjusted life-years (QALYs), with multiple imputation of missing data, was conducted to estimate the incremental cost per QALY gained associated with NPWT dressings. Sensitivity and subgroup analyses were undertaken to assess the impacts of uncertainty and heterogeneity, respectively, surrounding aspects of the economic evaluation. Results. The base case analysis produced an incremental cost-effectiveness ratio of £267 910 per QALY gained, reflecting higher costs on average (£678; 95% confidence interval (CI) -£1082 to £2438) and only marginally higher QALYS (0.002; 95% CI -0.054 to 0.059) in the NPWT group. The probability that NPWT is cost-effective in this patient population did not exceed 27% regardless of the value of the cost-effectiveness threshold. This result remained robust to several sensitivity and subgroup analyses. Conclusion. This trial-based economic evaluation suggests that NPWT is unlikely to be a cost-effective strategy for improving outcomes in adult patients with severe open fractures of the lower limb. Cite this article: Bone Joint J 2019;101-B:1392–1401

Aims. To compare the cost-utility of standard dressing with incisional negative-pressure wound therapy (iNPWT) in adults with closed surgical wounds associated with major trauma to the lower limbs. Methods. A within-trial economic evaluation was conducted from the UK NHS and personal social services (PSS) perspective based on data collected from the Wound Healing in Surgery for Trauma (WHiST) multicentre randomized clinical trial. Health resource utilization was collected over a six-month post-randomization period using trial case report forms and participant-completed questionnaires. Cost-utility was reported in terms of incremental cost per quality-adjusted life year (QALY) gained. Sensitivity analysis was conducted to test the robustness of cost-effectiveness estimates while uncertainty was handled using confidence ellipses and cost-effectiveness acceptability curves. Results. The incremental cost of standard dressing versus iNPWT over six months was £2,037 (95% confidence interval (CI) £349 to £3,724). There was an insignificant increment in QALYs gained in the iNPWT group (0.005, 95% CI -0.018 to 0.028). The probability of iNPWT being cost-effective at £20,000 per QALY was 1.9%. The results remained robust in the sensitivity analysis. Conclusion. The within-trial economic evaluation suggests that iNPWT is unlikely to be a cost-effective alternative to standard dressing in adults with closed surgical wounds to their lower limbs. Cite this article: Bone Joint J 2020;102-B(8):1072–1081

Corrective osteotomies are often planned and performed on the basis of normal anatomical proportions. We have evaluated the length and torsion of the segments of the lower limb in normal individuals, to analyse the differences between left and right sides, and to provide tolerance figures for both length and torsion. We used CT on 355 adult patients and measured length and torsion by the Ulm method. We excluded all patients with evidence of trauma, infection, tumour or any congenital disorder. The mean length of 511 femora was 46.3 ± 6.4 cm (±2. sd. ) and of 513 tibiae 36.9 ± 5.6 cm; the mean total length of 378 lower limbs was 83.2 ± 11.4 cm with a tibiofemoral ratio of 1 to 1.26 ± 0.1. The 99th percentile level for length difference in 178 paired femora was 1.2 cm, in 171 paired tibiae 1.0 cm and in 60 paired lower limbs 1.4 cm. In 505 femora the mean internal torsion was 24.1 ± 17.4°, and in 504 tibiae the mean external torsion was 34.9 ± 15.9°. For 352 lower limbs the mean external torsion was 9.8 ± 11.4°. The mean torsion angle of right and left femora in individuals did not differ significantly, but mean tibial torsion showed a significant difference between right (36.46° of external torsion) and left sides (33.07° of external torsion). For the whole legs torsion on the left was 7.5 ± 18.2° and 11.8 ± 18.8°, respectively (p < 0.001). There was a trend to greater internal torsion in femora in association with an increased external torsion in tibiae, but we found no correlation. The 99th percentile value for the difference in 172 paired femora was 13°; in 176 pairs of tibiae it was 14.3° and for 60 paired lower limbs 15.6°. These results will help to plan corrective osteotomies in the lower limbs, and we have re-evaluated the mathematical limits of differences in length and torsion

Aims

The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients.

Aims. The aim of this study was to validate the Mirels score in predicting pathological fractures in metastatic disease of the lower limb. Patients and Methods. A total of 62 patients with confirmed metastatic disease met the inclusion criteria. Of the 62 patients, 32 were female and 30 were male. The mean age of patients was 65 years (35 to 89). The primary malignancy originated from the breast in 27 (44%) patients, prostate in 15 (24%) patients, kidney in seven (11%), and lung in four (6%) of patients. One patient (2%) had metastatic carcinoma from the lacrimal gland, two patients (3%) had multiple myeloma, one patient (2%) had lymphoma of bone, and five patients (8%) had metastatic carcinoma of unknown primary. Plain radiographs at the time of initial presentation were scored using Mirels system by the four authors. The radiographic components of the score (anatomical site, size, and radiographic appearance) were scored two weeks apart. Inter- and intraobserver reliability were calculated with Fleiss’ kappa test. Bland-Altman plots were created to compare the variances of the individual components of the score and the total Mirels score. Results. Kappa values for the interobserver variability of the components of the Mirels score were k = 0.554 (95% CI 0.483 to 0.626) for site, k = 0.342 (95% CI 0.285 to 0.400) for size, k = 0.443 (95% CI 0.387 to 0.499) for radiographic appearance, and k = 0.294 (95% CI 0.258 to 0.331)for the total score. Kappa values for the intra-observer reliability were k = 0.608 (95% CI 0.506 to 0.710) for site, k = 0.579 (95% CI 0.487 to 0.670) for size, k = 0.614 (95% CI 0.522 to 0.703) for radiographic appearance, and k = 0.323 (95% CI 0.266 to 0.379) for total score. Conclusion. Our study showed fair to moderate agreement between authors when using the Mirels score, and moderate to substantial agreement when authors rescored radiographs. The Mirels score is subjective and lacks reproducibility in predicting the risk of pathological fracture. Cite this article: Bone Joint J 2018;100-B:1100–5

The aim of this study was to examine the loading of the other joints of the lower limb in patients with unilateral osteoarthritis (OA) of the knee. We recruited 20 patients with no other symptoms or deformity in the lower limbs from a consecutive cohort of patients awaiting knee replacement. Gait analysis and electromyographic recordings were performed to determine moments at both knees and hips, and contraction patterns in the medial and lateral quadriceps and hamstrings bilaterally. The speed of gait was reduced in the group with OA compared with the controls, but there were only minor differences in stance times between the limbs. Patients with OA of the knee had significant increases in adduction moment impulse at both knees and the contralateral hip (adjusted p-values: affected knee: p < 0.01, unaffected knee p = 0.048, contralateral hip p = 0.03), and significantly increased muscular co-contraction bilaterally compared with controls (all comparisons for co-contraction, p < 0.01). The other major weight-bearing joints are at risk from abnormal biomechanics in patients with unilateral OA of the knee. Cite this article: Bone Joint J 2013;95-B:348–53