Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029

Aims. Functional rehabilitation has become an increasingly popular treatment for Achilles tendon rupture (ATR), providing comparably low re-rupture rates to surgery, while avoiding risks of surgical complications. Limited evidence exists on whether gap size should affect patient selection for this treatment option. The aim of this study was to assess if size of gap between ruptured tendon ends affects patient-reported outcome following ATR treated with functional rehabilitation. Methods. Analysis of prospectively collected data on all 131 patients diagnosed with ATR at Royal Berkshire Hospital, UK, from August 2016 to January 2019 and managed non-operatively was performed. Diagnosis was confirmed on all patients by dynamic ultrasound scanning and gap size measured with ankle in full plantarflexion. Functional rehabilitation using an established protocol was the preferred treatment. All non-operatively treated patients with completed Achilles Tendon Rupture Scores (ATRS) at a minimum of 12 months following injury were included. Results. In all, 82 patients with completed ATRS were included in the analysis. Their mean age was 51 years (standard deviation (SD) 14). The mean ATRS was 76 (SD 19) at a mean follow-up of 20 months (SD 11) following injury. Gap inversely affected ATRS with a Pearson’s correlation of -0.30 (p = 0.008). Mean ATRS was lower with gaps > 5 mm compared with ≤ 5 mm (73 (SD 21) vs 82 (SD 16); p = 0.031). Mean ATRS was lowest (70 (SD 23)) with gaps > 10 mm, with significant differences in perceived strength and pain. The overall re-rupture rate was two out of 131 (1.5%). Conclusion. Increasing gap size predicts lower patient-reported outcome, as measured by ATRS. Tendon gap > 5 mm may be a useful predictor in physically demanding individuals, and tendon gap > 10 mm for those with low physical demand. Further studies that control for gap size when comparing non-operative and operative treatment are required to assess if these patients may benefit from surgery, particularly when balanced against the surgical risks. Cite this article: Bone Joint J 2020;102-B(11):1535–1541

Objectives. Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replacement (TKR), preserving or sacrificing a PCL affects the gap equivalence; however, there are no criteria for the PCL resection that consider gap situations of each knee. This study aims to investigate gap characteristics of knees and to consider the criteria for PCL resection. Methods. The extension and flexion gaps were measured, first with the PCL preserved and subsequently with the PCL removed (in cases in which posterior substitute components were selected). The PCL preservation or sacrifice was solely determined by the gap measurement results, without considering other functions of the PCL such as ‘roll back.’. Results. Wide variations were observed in the extension and flexion gaps. The flexion gaps were significantly larger than the extension gaps. Cases with 18 mm or more flexion gap and with larger flexion than extension gap were implanted with cruciate retaining component. A posterior substitute component was implanted with the other cases. Conclusions. In order to make adequate gaps, it is important to decide whether to preserve the PCL based on the intra-operative gap measurements made with the PCL intact. Cite this article: Bone Joint Res 2014;3:95–100

Aims. It is unknown whether gap laxities measured in robotic arm-assisted total knee arthroplasty (TKA) correlate to load sensor measurements. The aim of this study was to determine whether symmetry of the maximum medial and lateral gaps in extension and flexion was predictive of knee balance in extension and flexion respectively using different maximum thresholds of intercompartmental load difference (ICLD) to define balance. Methods. A prospective cohort study of 165 patients undergoing functionally-aligned TKA was performed (176 TKAs). With trial components in situ, medial and lateral extension and flexion gaps were measured using robotic navigation while applying valgus and varus forces. The ICLD between medial and lateral compartments was measured in extension and flexion with the load sensor. The null hypothesis was that stressed gap symmetry would not correlate directly with sensor-defined soft tissue balance. Results. In TKAs with a stressed medial-lateral gap difference of ≤1 mm, 147 (89%) had an ICLD of ≤15 lb in extension, and 112 (84%) had an ICLD of ≤ 15 lb in flexion; 157 (95%) had an ICLD ≤ 30 lb in extension, and 126 (94%) had an ICLD ≤ 30 lb in flexion; and 165 (100%) had an ICLD ≤ 60 lb in extension, and 133 (99%) had an ICLD ≤ 60 lb in flexion. With a 0 mm difference between the medial and lateral stressed gaps, 103 (91%) of TKA had an ICLD ≤ 15 lb in extension, decreasing to 155 (88%) when the difference between the medial and lateral stressed extension gaps increased to ± 3 mm. In flexion, 47 (77%) had an ICLD ≤ 15 lb with a medial-lateral gap difference of 0 mm, increasing to 147 (84%) at ± 3 mm. Conclusion. This study found a strong relationship between intercompartmental loads and gap symmetry in extension and flexion measured with prostheses in situ. The results suggest that ICLD and medial-lateral gap difference provide similar assessment of soft-tissue balance in robotic arm-assisted TKA. Cite this article: Bone Jt Open 2021;2(11):974–980

Aims. The results of kinematic total knee arthroplasty (KTKA) have been reported in terms of limb and component alignment parameters but not in terms of gap laxities and differentials. In kinematic alignment (KA), balance should reflect the asymmetrical balance of the normal knee, not the classic rectangular flexion and extension gaps sought with gap-balanced mechanical axis total knee arthroplasty (MATKA). This paper aims to address the following questions: 1) what factors determine coronal joint congruence as measured on standing radiographs?; 2) is flexion gap asymmetry produced with KA?; 3) does lateral flexion gap laxity affect outcomes?; 4) is lateral flexion gap laxity associated with lateral extension gap laxity?; and 5) can consistent ligament balance be produced without releases?. Patients and Methods. A total of 192 KTKAs completed by a single surgeon using a computer-assisted technique were followed for a mean of 3.5 years (2 to 5). There were 116 male patients (60%) and 76 female patients (40%) with a mean age of 65 years (48 to 88). Outcome measures included intraoperative gap laxity measurements and component positions, as well as joint angles from postoperative three-foot standing radiographs. Patient-reported outcome measures (PROMs) were analyzed in terms of alignment and balance: EuroQol (EQ)-5D visual analogue scale (VAS), Knee Injury and Osteoarthritis Outcome Score (KOOS), KOOS Joint Replacement (JR), and Oxford Knee Score (OKS). Results. Postoperative limb alignment did not affect outcomes. The standing hip-knee-ankle (HKA) angle was the sole positive predictor of the joint line convergence angle (JLCA) (p < 0.001). Increasing lateral flexion gap laxity was consistently associated with better outcomes. Lateral flexion gap laxity did not correlate with HKA angle, the JLCA, or lateral extension gap laxity. Minor releases were required in one third of cases. Conclusion. The standing HKA angle is the primary determinant of the JLCA in KTKA. A rectangular flexion gap is produced in only 11% of cases. Lateral flexion gap laxity is consistently associated with better outcomes and does not affect balance in extension. Minor releases are sometimes required as well, particularly in limbs with larger preoperative deformities. Cite this article: Bone Joint J 2019;101-B:331–339

Aims. To compare patients undergoing total knee arthroplasty (TKA) with ≤ 80° range of movement (ROM) operated with a 2 mm increase in the flexion gap with matched non-stiff patients with at least 100° of preoperative ROM and balanced flexion and extension gaps. Methods. In a retrospective cohort study, 98 TKAs (91 patients) with a preoperative ROM of ≤ 80° were examined. Mean follow-up time was 53 months (24 to 112). All TKAs in stiff knees were performed with a 2 mm increased flexion gap. Data were compared to a matched control group of 98 TKAs (86 patients) with a mean follow-up of 43 months (24 to 89). Knees in the control group had a preoperative ROM of at least 100° and balanced flexion and extension gaps. In all stiff and non-stiff knees posterior stabilized (PS) TKAs with patellar resurfacing in combination with adequate soft tissue balancing were used. Results. Overall mean ROM in stiff knees increased preoperatively from 67° (0° to 80°) to 114° postoperatively (65° to 135°) (p < 0.001). Mean knee flexion improved from 82° (0° to 110°) to 115° (65° to 135°) and mean flexion contracture decreased from 14° (0° to 50°) to 1° (0° to 10°) (p < 0.001). The mean Knee Society Score (KSS) improved from 34 (0 to 71) to 88 (38 to 100) (p < 0.001) and the KSS Functional Score from 43 (0 to 70) to 86 (0 to 100). Seven knees (7%) required manipulations under anaesthesia (MUA) and none of the knees had flexion instability. The mean overall ROM in the control group improved from 117° (100° to 140°) to 123° (100° to 130°) (p < 0.001). Mean knee flexion improved from 119° (100° to 140°) to 123° (100° to 130°) (p < 0.001) and mean flexion contracture decreased from 2° (0° to 15°) to 0° (0° to 5°) (p < 0.001). None of the knees in the control group had flexion instability or required MUA. The mean KSS Knee Score improved from 48 (0 to 80) to 94 (79 to 100) (p < 0.001) and the KSS Functional Score from 52 (5 to 100) to 95 (60 to 100) (p < 0.001). Mean improvement in ROM (p < 0.001) and KSS Knee Score (p = 0.017) were greater in knees with preoperative stiffness compared with the control group, but the KSS Functional Score improvement was comparable (p = 0.885). Conclusion. TKA with a 2 mm increased flexion gap provided a significant improvement of ROM in knees with preoperative stiffness. While the improvement in ROM was greater, the absolute postoperative ROM was less than in matched non-stiff knees. PS TKA with patellar resurfacing and a 2 mm increased flexion gap, in combination with adequate soft tissue balancing, provides excellent ROM and knee function when stiffness of the knee had been present preoperatively. Cite this article: Bone Joint J 2020;102-B(4):426–433

Aims. The primary aim of this study was to address the hypothesis that fracture morphology might be more important than posterior malleolar fragment size in rotational type posterior malleolar ankle fractures (PMAFs). The secondary aim was to identify clinically important predictors of outcome for each respective PMAF-type, to challenge the current dogma that surgical decision-making should be based on fragment size. Methods. This observational prospective cohort study included 70 patients with operatively treated rotational type PMAFs, respectively: 23 Haraguchi Type I (large posterolateral-oblique), 22 Type II (two-part posterolateral and posteromedial), and 25 (avulsion-) Type III. There was no standardized protocol on how to address the PMAFs and CT-imaging was used to classify fracture morphology and quality of postoperative syndesmotic reduction. Quantitative 3D-CT (Q3DCT) was used to assess the quality of fracture reduction, respectively: the proportion of articular involvement; residual intra-articular: gap, step-off, and 3D-displacement; and residual gap and step-off at the fibular notch. These predictors were correlated with the Foot and Ankle Outcome Score (FAOS) at two-years follow-up. Results. Bivariate analyses revealed that fracture morphology (p = 0.039) as well as fragment size (p = 0.007) were significantly associated with the FAOS. However, in multivariate analyses, fracture morphology (p = 0.001) (but not fragment size (p = 0.432)) and the residual intra-articular gap(s) (p = 0.009) were significantly associated. Haraguchi Type-II PMAFs had poorer FAOS scores compared with Types I and III. Multivariate analyses identified the following independent predictors: step-off in Type I; none of the Q3DCT-measurements in Type II, and quality of syndesmotic reduction in small-avulsion Type III PMAFs. Conclusion. PMAFs are three separate entities based on fracture morphology, with different predictors of outcome for each PMAF type. The current debate on whether or not to fix PMAFs needs to be refined to determine which morphological subtype benefits from fixation. In PMAFs, fracture morphology should guide treatment instead of fragment size. Cite this article: Bone Joint J 2020;102-B(9):1229–1241

Aims. Gap junction intercellular communication (GJIC) in osteocytes is impaired by oxidative stress, which is associated with age-related bone loss. Ageing is accompanied by the accumulation of advanced oxidation protein products (AOPPs). However, it is still unknown whether AOPP accumulation is involved in the impairment of osteocytes’ GJIC. This study aims to investigate the effect of AOPP accumulation on osteocytes’ GJIC in aged male mice and its mechanism. Methods. Changes in AOPP levels, expression of connexin43 (Cx43), osteocyte network, and bone mass were detected in 18-month-old and three-month-old male mice. Cx43 expression, GJIC function, mitochondria membrane potential, reactive oxygen species (ROS) levels, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation were detected in murine osteocyte-like cells (MLOY4 cells) treated with AOPPs. The Cx43 expression, osteocyte network, bone mass, and mechanical properties were detected in three-month-old mice treated with AOPPs for 12 weeks. Results. The AOPP levels were increased in aged mice and correlated with degeneration of osteocyte network, loss of bone mass, and decreased Cx43 expression. AOPP intervention induced NADPH oxidase activation and mitochondrial dysfunction, triggered ROS generation, reduced Cx43 expression, and ultimately impaired osteocytes’ GJIC, which were ameliorated by NADPH oxidase inhibitor apocynin, mitochondria-targeted superoxide dismutase mimetic (mito-TEMPO), and ROS scavenger N-acetyl cysteine. Chronic AOPP loading accelerated the degradation of osteocyte networks and decreased Cx43 expression, resulting in deterioration of bone mass and mechanical properties in vivo. Conclusion. Our study suggests that AOPP accumulation contributes to age-related impairment of GJIC in osteocytes of male mice, which may be part of the pathogenic mechanism responsible for bone loss during ageing. Cite this article: Bone Joint Res 2022;11(7):413–425

Interfacial defects between the cement mantle and a hip implant may arise from constrained shrinkage of the cement or from air introduced during insertion of the stem. Shrinkage-induced interfacial porosity consists of small pores randomly located around the stem, whereas introduced interfacial gaps are large, individual and less uniformly distributed areas of stem-cement separation. Using a validated CT-based technique, we investigated the extent, morphology and distribution of interfacial gaps for two types of stem, the Charnley-Kerboul and the Lubinus SPII, and for two techniques of implantation, line-to-line and undersized. The interfacial gaps were variable and involved a mean of 6.43% (. sd. 8.99) of the surface of the stem. Neither the type of implant nor the technique of implantation had a significant effect on the regions of the gaps, which occurred more often over the flat areas of the implant than along the corners of the stems, and were more common proximally than distally for Charnley-Kerboul stems cemented line-to-line. Interfacial defects could have a major effect on the stability and survival of the implant

Aims. The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases. Methods. Patients who underwent RA-TKA between January and December 2022 for primary varus osteoarthritis were included. Safe boundaries for E-rKA were defined. Residual medial compartment tightness was compared following virtual surgical planning using E-rKA and MA, in the same set of knees. Soft-tissue releases were documented. Errors in postoperative alignment in relation to planned alignment were compared between patients who did (group A) and did not (group B) require soft-tissue releases. Results. The use of E-rKA helped restore all knees within the predefined boundaries, with appropriate soft-tissue balancing. E-rKA compared with MA resulted in reduced residual medial tightness following surgical planning, in full extension (2.71 mm (SD 1.66) vs 5.16 mm (SD 3.10), respectively; p < 0.001), and 90° of flexion (2.52 mm (SD 1.63) vs 6.27 mm (SD 3.11), respectively; p < 0.001). Among the study population, 156 patients (78%) were managed with minor adjustments in component positioning alone, while 44 (22%) required additional soft-tissue releases. The mean errors in postoperative alignment were 0.53 mm and 0.26 mm among patients in group A and group B, respectively (p = 0.328). Conclusion. E-rKA is an effective and reproducible alignment strategy during RA-TKA, permitting a large proportion of patients to be managed without soft-tissue releases. The execution of minor alterations in component positioning within predefined multiplanar boundaries is a better starting point for gap management than soft-tissue releases. Cite this article: Bone Jt Open 2024;5(8):628–636

We investigated whether the extension gap in total knee replacement (TKR) would be changed when the femoral component was inserted. The extension gap was measured with and without the femoral component in place in 80 patients with varus osteoarthritis undergoing posterior-stabilised TKR. The effect of a post-operative increase in the size of the femoral posterior condyles was also evaluated. The results showed that placement of the femoral component significantly reduced the medial and lateral extension gaps by means of 1.0 mm and 0.9 mm, respectively (p < 0.0001). The extension gap was reduced when a larger femoral component was selected relative to the thickness of the resected posterior condyle. When the post-operative posterior lateral condyle was larger than that pre-operatively, 17 of 41 knees (41%) showed a decrease in the extension gap of > 2.0 mm. When a specially made femoral trial component with a posterior condyle enlarged by 4 mm was tested, the medial and lateral extension gaps decreased further by means of 2.1 mm and 2.8 mm, respectively. If the thickness of the posterior condyle is expected to be larger than that pre-operatively, it should be recognised that the extension gap is likely to be altered. This should be taken into consideration when preparing the extension gap

Clinical experience indicates the beneficial effects of antibiotic-loaded bone cement. Although in vitro studies have shown the formation of a biofilm on its surface they have not considered the gap between the cement and the bone. We have investigated bacterial survival in that gap. Samples with gaps 200 μm wide were made of different bone cements. These were stored dry (‘pre-elution’) or submersed in phosphate-buffered saline to simulate the initial release of gentamicin (‘post-elution’). The gaps were subsequently inoculated with bacteria, which had been isolated from infected orthopaedic prostheses and assessed for their sensitivity to gentamicin. Bacterial survival was measured 24 hours after inoculation. All the strains survived in plain cements. In the pre-elution gentamicin-loaded cements only the most gentamicin-resistant strain, CN5115, survived, but in post-elution samples more strains did so, depending on the cement tested. Although high concentrations of gentamicin were demonstrated in the gaps only the gentamicin-sensitive strains were killed. This could explain the increased prevalence of gentamicin-resistant infections which are seen clinically

We have developed a new tensor for total knee replacements which is designed to assist with soft-tissue balancing throughout the full range of movement with a reduced patellofemoral joint. Using this tensor in 40 patients with osteoarthritis we compared the intra-operative joint gap in cruciate-retaining and posterior-stabilised total knee replacements at 0°, 10°, 45°, 90° and 135° of flexion, with the patella both everted and reduced. While the measurement of the joint gap with a reduced patella in posterior-stabilised knees increased from extension to flexion, it remained constant for cruciate-retaining joints throughout a full range of movement. The joint gaps at deep knee flexion were significantly smaller for both types of prosthetic knee when the patellofemoral joint was reduced (p < 0.05)

Varus and valgus joint laxity of the normal living knee in flexion was assessed using MRI. Twenty knees were flexed to 90° and were imaged in neutral and under a varus-valgus stress in an open MRI system. The configuration of the tibiofemoral joint gap was studied in slices which crossed the epicondyles of the femur. When a varus stress was applied, the lateral joint gap opened by 6.7 ± 1.9 mm (mean ± . sd. ; 2.1 to 9.2) whereas the medial joint gap opened by only by a mean of 2.1 ± 1.1 mm (0.2 to 4.2). These discrepancies indicate that the tibiofemoral flexion gap in the normal knee is not rectangular and that the lateral joint gap is significantly lax. These results may be useful for adequate soft-tissue balancing and bone resection in total knee arthroplasty and reconstruction surgery on ligaments

Aims. This is a prospective randomised study which compares the radiological and functional outcomes of ring and rail fixators in patients with an infected gap (> 3 cm) nonunion of the tibia. Patients and Methods. Between May 2008 and February 2013, 70 patients were treated at our Institute for a posttraumatic osseocutaneous defect of the tibia measuring at least 3 cm. These were randomised into two groups of 35 patients using the lottery method. Group I patients were treated with a ring fixator and group II patients with a rail fixator. The mean age was 33.2 years (18 to 64) in group I and 29.3 years (18 to 65) in group II. The mean bone gap was 5.84 cm in group I and 5.78 cm in group II. The mean followup was 33.8 months in group I and 32.6 months in group II. Bone and functional results were assessed using the classification of the Association for the Study and Application of the Method of Ilizarov (ASAMI). Functional results were also assessed at six months using the short musculoskeletal functional assessment (SMFA) score. Results. The bone result was excellent, good, fair and poor in 21, 12, 0 and 2 in group I; and 14, 15, 3, and 3 in group II, respectively. The functional results were excellent, good, fair, poor and failure in 16, 17, 1, 0 and 1 in group I; and 22, 10, 0, 3 and 0 in group II, respectively. Both fixator systems achieved comparable rates of union and functional outcomes. The rate of deep pintract infection was significantly higher in the rail fixator group but patients found it more comfortable. Conclusion. We recommend the use of a ring fixator in patients with a bone gap of more than 6 cm. Patients with a bone gap up to 6 cm can be managed with either a ring or rail fixator. Cite this article: Bone Joint J 2016;98B:1399–1405

The shape of the flexion gap in 20 normal knees was evaluated by axial radiography of the distal femur, and the results compared with those obtained in a previous study by MRI. The observed asymmetry was reduced by 29% using radiography, with a mean value of 3.6° (1.5° to 6.3°) compared with that obtained by MRI of 5.1° (2.6° to 9.5°), a mean discrepancy of 1.49°. The results obtained by radiography and MRI showed a strong correlation (r = 0.78). Axial radiography is acceptable for the evaluation of the flexion gap and is less expensive and more comfortable to perform than MRI. Additionally, no metallic artefact occurs when the radiological method is used for assessment after arthroplasty

Aims

The aim of this study was to assess the clinical and radiological outcomes of an antiprotrusio acetabular cage (APC) when used in the surgical treatment of periacetabular bone metastases.

Achieving deep flexion after total knee replacement remains a challenge. In this study we compared the soft-tissue tension and tibiofemoral force in a mobile-bearing posterior cruciate ligament-sacrificing total knee replacement, using equal flexion and extension gaps, and with the gaps increased by 2 mm each. The tests were conducted during passive movement in five cadaver knees, and measurements of strain were made simultaneously in the collateral ligaments. The tibiofemoral force was measured using a customised mini-force plate in the tibial tray. Measurements of collateral ligament strain were not very sensitive to changes in the gap ratio, but tibiofemoral force measurements were. Tibiofemoral force was decreased by a mean of 40% (. sd. 10.7) after 90° of knee flexion when the flexion gap was increased by 2 mm. Increasing the extension gap by 2 mm affected the force only in full extension. Because increasing the range of flexion after total knee replacement beyond 110° is a widely-held goal, small increases in the flexion gap warrant further investigation

We have compared the interface morphology at the stem-cement interface of standard Charnley stems with a satin finish (Ra = 0.75 μm) with identical stems which had been grit-blasted over their proximal third (Ra = 5.3 μm) to promote a proximal bond. The stems were cemented into cadaver femora using conventional contemporary cementing techniques. After transverse sectioning, we determined the percentage of the perimeter of the stem which had a gap at the interface. There were substantial gaps (mean 31.4 ± 17.1%) at the stem-cement interface in the grit-blasted region. This fraction was significantly (paired t-test, p = 0.0054) higher than that found around the contralateral satin-finished stems (mean 7.7 ± 11.7%). Although studies of isolated metal-cement interfaces have shown that the bond strength can increase with surface roughness it cannot be assumed that this effect will be observed under clinical conditions

A clay containing hydroxyapatite (HA) was developed for use as a filling material between an uncemented implant and bone. It consists of 55% HA granules greater than 0.1 mm in size with a homogeneous pore distribution and a porosity of 35% to 48% in a saline solution of sodium alginate (6%). Ti-6A1-4V alloy rods with smooth surfaces were implanted into the distal medullary canal of one osteotomised tibia of 32 Japanese white rabbits. Sixteen rods were inserted with HA clay and 16 without the clay to act as a control group. Six of each group were killed at one week and ten at 12 weeks postoperatively. The pull-out strength of the implants with HA clay was significantly greater at 12 weeks (p < 0.05), as was the percentage of the area of the new bone (p < 0.05). The study suggests that HA clay has an osteoconductive property, allowing adequate bone fixation across a gap at an early stage. The use of HA clay to enhance the early stability of uncemented components may help to improve the functional outcome of total joint arthroplasty

Aims

There are two techniques widely used to determine the rotational alignment of the components in total knee arthroplasty (TKA); gap balancing (GB) and measured resection (MR). Which technique is the best remains controversial. We aimed to investigate this in a systematic review and meta-analysis.

The success of total knee replacement (TKR) depends on optimal soft-tissue balancing, among many other factors. The objective of this study is to correlate post-operative anteroposterior (AP) translation of a posterior cruciate ligament-retaining TKR with clinical outcome at two years. In total 100 patients were divided into three groups based on their AP translation as measured by the KT-1000 arthrometer. Group 1 patients had AP translation < 5 mm, Group 2 had AP translation from 5 mm to 10 mm, and Group 3 had AP translation >  10 mm. Outcome assessment included range of movement of the knee, the presence of flexion contractures, hyperextension, knee mechanical axes and functional outcome using the Knee Society score, Oxford knee score and the Short-Form 36 questionnaire.

At two years, patients in Group 2 reported significantly better Oxford knee scores than the other groups (p = 0.045). A positive correlation between range of movement and AP translation was noted, with patients in group 3 having the greatest range of movement (mean flexion: 117.9° (106° to 130°)) (p < 0.001). However, significantly more patients in Group 3 developed hyperextension > 10° (p = 0.01).

In this study, the best outcome for cruciate-ligament retaining TKR was achieved in patients with an AP translation of 5 mm to 10 mm.

A cortical bone graft on a muscle pedicle was taken from the ulna and transferred to bridge a complete defect of the radius in 16 dogs. In 14 control dogs a free graft was used, that is, one without a muscle pedicle. Union in the group with pedicle grafts was far superior to that in the group with free grafts, mainly because in those with pedicle grafts there was good subperiosteal new bone formation from active viable periosteum. In six of the pedicle grafts the viability of some osteocytes was retained over a 12-week period and in five the graft was almost completely replaced by new bone.

Aims. In this study, we aimed to explore surgical variations in the Femoral Neck System (FNS) used for stable fixation of Pauwels type III femoral neck fractures. Methods. Finite element models were established with surgical variations in the distance between the implant tip and subchondral bone, the gap between the plate and lateral femoral cortex, and inferior implant positioning. The models were subjected to physiological load. Results. Under a load of single-leg stance, Pauwels type III femoral neck fractures fixed with 10 mm shorter bolts revealed a 7% increase of the interfragmentary gap. The interfragmentary sliding, compressive, and shear stress remained similar to models with bolt tips positioned close to the subchondral bone. Inferior positioning of FNS provided a similar interfragmentary distance, but with 6% increase of the interfragmentary sliding distance compared to central positioning of bolts. Inferior positioning resulted in a one-third increase in interfragmentary compressive and shear stress. A 5 mm gap placed between the diaphysis and plate provided stability comparable to standard fixation, with a 7% decrease of interfragmentary gap and sliding distance, but similar compressive and shear stress. Conclusion. Finite element analysis with FNS on Pauwels type III femoral neck fractures revealed that placement of the bolt tip close to subchondral bone provides increased stability. Inferior positioning of FNS bolt increased interfragmentary sliding distance, compressive, and shear stress. The comparable stability of the fixation model with the standard model suggests that a 5 mm gap placed between the plate and diaphysis could viably adjust the depth of the bolt. Cite this article: Bone Joint Res 2022;11(2):102–111

Aims. Periprosthetic fracture and implant loosening are two of the major reasons for revision surgery of cementless implants. Optimal implant fixation with minimal bone damage is challenging in this procedure. This pilot study investigates whether vibratory implant insertion is gentler compared to consecutive single blows for acetabular component implantation in a surrogate polyurethane (PU) model. Methods. Acetabular components (cups) were implanted into 1 mm nominal under-sized cavities in PU foams (15 and 30 per cubic foot (PCF)) using a vibratory implant insertion device and an automated impaction device for single blows. The impaction force, remaining polar gap, and lever-out moment were measured and compared between the impaction methods. Results. Impaction force was reduced by 89% and 53% for vibratory insertion in 15 and 30 PCF foams, respectively. Both methods positioned the component with polar gaps under 2 mm in 15 PCF foam. However, in 30 PCF foam, the vibratory insertion resulted in a clinically undesirable polar gap of over 2 mm. A higher lever-out moment was achieved with the consecutive single blow insertion by 42% in 15 PCF and 2.7 times higher in 30 PCF foam. Conclusion. Vibratory implant insertion may lower periprosthetic fracture risk by reducing impaction forces, particularly in low-quality bone. Achieving implant seating using vibratory insertion requires adjustment of the nominal press-fit, especially in denser bone. Further preclinical testing on real bone tissue is necessary to assess whether its viscoelasticity in combination with an adjusted press-fit can compensate for the reduced primary stability after vibratory insertion observed in this study. Cite this article: Bone Joint Res 2024;13(6):272–278

Aims. To evaluate whether low-intensity pulsed ultrasound (LIPUS) accelerates bone healing at osteotomy sites and promotes functional recovery after open-wedge high tibial osteotomy (OWHTO). Methods. Overall, 90 patients who underwent OWHTO without bone grafting were enrolled in this nonrandomized retrospective study, and 45 patients treated with LIPUS were compared with 45 patients without LIPUS treatment in terms of bone healing and functional recovery postoperatively. Clinical evaluations, including the pain visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score, were performed preoperatively as well as six weeks and three, six, and 12 months postoperatively. The progression rate of gap filling was evaluated using anteroposterior radiographs at six weeks and three, six, and 12 months postoperatively. Results. The pain VAS and JOA scores significantly improved after OWHTO in both groups. Although the LIPUS group had better pain scores at six weeks and three months postoperatively, there were no significant differences in JOA score between the groups. The lateral hinge united at six weeks postoperatively in 34 (75.6%) knees in the control group and in 33 (73.3%) knees in the LIPUS group. The progression rates of gap filling in the LIPUS group were 8.0%, 15.0%, 27.2%, and 46.0% at six weeks and three, six, and 12 months postoperatively, respectively, whereas in the control group at the same time points they were 7.7%, 15.2%, 26.3%, and 44.0%, respectively. There were no significant differences in the progression rate of gap filling between the groups. Conclusion. The present study demonstrated that LIPUS did not promote bone healing and functional recovery after OWHTO with a locking plate. The routine use of LIPUS after OWHTO was not recommended from the results of our study. Cite this article: Bone Jt Open 2022;3(11):885–893

The recently published Prophylactic Antibiotic Regimens In Tumor Surgery (PARITY) trial found no benefit in extending antibiotic prophylaxis from 24 hours to five days after endoprosthetic reconstruction for lower limb bone tumours. PARITY is the first randomized controlled trial in orthopaedic oncology and is a huge step forward in understanding antibiotic prophylaxis. However, significant gaps remain, including questions around antibiotic choice, particularly in the UK, where cephalosporins are avoided due to concerns of Clostridioides difficile infection. We present a review of the evidence for antibiotic choice, dosing, and timing, and a brief description of PARITY, its implication for practice, and the remaining gaps in our understanding. Cite this article: Bone Joint J 2023;105-B(8):850–856

Aims. Multiligament knee injuries (MLKI) are devastating injuries that can result in significant morbidity and time away from sport. There remains considerable variation in strategies employed for investigation, indications for operative intervention, outcome reporting, and rehabilitation following these injuries. At present no study has yet provided a comprehensive overview evaluating the extent, range, and overall summary of the published literature pertaining to MLKI. Our aim is to perform a methodologically rigorous scoping review, mapping the literature evaluating the diagnosis and management of MLKI. Methods. This scoping review will address three aims: firstly, to map the current extent and nature of evidence for diagnosis and management of MLKI; secondly, to summarize and disseminate existing research findings to practitioners; and thirdly, to highlight gaps in current literature. A three-step search strategy as described by accepted methodology will be employed to identify peer-reviewed literature including reviews, technical notes, opinion pieces, and original research. An initial limited search will be performed to determine suitable search terms, followed by an expanded search of four electronic databases (MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Web of Science). Two reviewers will independently screen identified studies for final inclusion. Dissemination. We will map key concepts and evidence, and disseminate existing research findings to the wider orthopaedic and sports medicine community, through both peer-reviewed and non-peer-reviewed literature, and conference and in-person communications. We will highlight gaps in the current literature and determine future priorities for further research. Cite this article: Bone Jt Open 2022;3(11):894–897

Aims. Proper preoperative planning benefits fracture reduction, fixation, and stability in tibial plateau fracture surgery. We developed and clinically implemented a novel workflow for 3D surgical planning including patient-specific drilling guides in tibial plateau fracture surgery. Methods. A prospective feasibility study was performed in which consecutive tibial plateau fracture patients were treated with 3D surgical planning, including patient-specific drilling guides applied to standard off-the-shelf plates. A postoperative CT scan was obtained to assess whether the screw directions, screw lengths, and plate position were performed according the preoperative planning. Quality of the fracture reduction was assessed by measuring residual intra-articular incongruence (maximum gap and step-off) and compared to a historical matched control group. Results. A total of 15 patients were treated with 3D surgical planning in which 83 screws were placed by using drilling guides. The median deviation of the achieved screw trajectory from the planned trajectory was 3.4° (interquartile range (IQR) 2.5 to 5.4) and the difference in entry points (i.e. plate position) was 3.0 mm (IQR 2.0 to 5.5) compared to the 3D preoperative planning. The length of 72 screws (86.7%) were according to the planning. Compared to the historical cohort, 3D-guided surgery showed an improved surgical reduction in terms of median gap (3.1 vs 4.7 mm; p = 0.126) and step-off (2.9 vs 4.0 mm; p = 0.026). Conclusion. The use of 3D surgical planning including drilling guides was feasible, and facilitated accurate screw directions, screw lengths, and plate positioning. Moreover, the personalized approach improved fracture reduction as compared to a historical cohort. Cite this article: Bone Jt Open 2024;5(1):46–52

Aims. The aim of the study was to investigate whether the primary stability of press-fit acetabular components can be improved by altering the impaction procedure. Methods. Three impaction procedures were used to implant acetabular components into human cadaveric acetabula using a powered impaction device. An impaction frequency of 1 Hz until complete component seating served as reference. Overimpaction was simulated by adding ten strokes after complete component seating. High-frequency implantation was performed at 6 Hz. The lever-out moment of the acetabular components was used as measure for primary stability. Permanent bone deformation was assessed by comparison of double micro-CT (µCT) measurements before and after impaction. Acetabular component deformation and impaction forces were recorded, and the extent of bone-implant contact was determined from 3D laser scans. Results. Overimpaction reduced primary acetabular component stability (p = 0.038) but did not significantly increase strain release after implantation (p = 0.117) or plastic deformations (p = 0.193). Higher press-fits were associated with larger polar gaps for the 1 Hz reference impaction (p = 0.002, R. 2. = 0.77), with a similar trend for overimpaction (p = 0.082, R. 2. = 0.31). High-frequency impaction did not significantly increase primary stability (p = 0.170) at lower impaction forces (p = 0.001); it was associated with smaller plastic deformations (p = 0.035, R. 2. = 0.34) and a trend for increased acetabular component relaxation between strokes (p = 0.112). Higher press-fit was not related to larger polar gaps for the 6 Hz impaction (p = 0.346). Conclusion. Overimpaction of press-fit acetabular components should be prevented since additional strokes can be associated with increased bone damage and reduced primary stability as shown in this study. High-frequency impaction at 6 Hz was shown to be beneficial compared with 1 Hz impaction. This benefit has to be confirmed in clinical studies. Cite this article: Bone Joint J 2023;105-B(3):261–268

Aims. The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA). Methods. This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus). Results. ACL resection increased the mean extension gap significantly more than the flexion gap in the medial (mean 1.2 mm (SD 1.0) versus mean 0.2 mm (SD 0.7) respectively; p < 0.001) and lateral (mean 1.1 mm (SD 0.9) versus mean 0.2 mm (SD 0.6) respectively; p < 0.001) compartments. The mean gap differences following ACL resection did not create any significant mediolateral soft tissue laxity in extension (gap difference: mean 0.1 mm (SD 2.4); p = 0.89) or flexion (gap difference: mean 0.2 mm (SD 3.1); p = 0.40). ACL resection did not significantly affect maximum knee extension (change in maximum knee extension = mean 0.2° (SD 0.7°); p = 0.23) or fixed flexion deformity (mean 4.2° (SD 3.2°) pre-ACL release versus mean 3.9° (SD 3.7°) post-ACL release; p = 0.61). ACL resection did not significantly affect overall limb alignment (change in alignment = mean 0.2° valgus (SD 1.0° valgus; p = 0.11). Conclusion. ACL resection creates flexion-extension mismatch by increasing the extension gap more than the flexion gap. However, gap differences following ACL resection do not create any mediolateral soft tissue laxity in extension or flexion. ACL resection does not affect maximum knee extension or overall limb alignment. Cite this article: Bone Joint J 2020;102-B(4):442–448

Aims. The aim of this study was to assess the effect of posterior cruciate ligament (PCL) resection on flexion-extension gaps, mediolateral soft-tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilized (PS) total knee arthroplasty (TKA). Patients and Methods. This prospective study included 110 patients with symptomatic osteoarthritis of the knee undergoing primary robot-assisted PS TKA. All operations were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps before and after PCL resection in extension and 90° knee flexion. Measurements were made after excision of the anterior cruciate ligament and prior to bone resection. There were 54 men (49.1%) and 56 women (50.9%) with a mean age of 68 years (. sd. 6.2) at the time of surgery. The mean preoperative hip-knee-ankle deformity was 4.1° varus (. sd. 3.4). Results. PCL resection increased the mean flexion gap significantly more than the extension gap in the medial (2.4 mm (. sd. 1.5) vs 1.3 mm (. sd. 1.0); p < 0.001) and lateral (3.3 mm (. sd. 1.6) vs 1.2 mm (. sd. 0.9); p < 0.01) compartments. The mean gap differences after PCL resection created significant mediolateral laxity in flexion (gap difference: 1.1 mm (. sd. 2.5); p < 0.001) but not in extension (gap difference: 0.1 mm (. sd. 2.1); p = 0.51). PCL resection significantly improved the mean FFD (6.3° (. sd. 4.4) preoperatively vs 3.1° (. sd. 1.5) postoperatively; p < 0.001). There was a strong positive correlation between the preoperative FFD and change in FFD following PCL resection (Pearson’s correlation coefficient = 0.81; p < 0.001). PCL resection did not significantly affect limb alignment (mean change in alignment: 0.2° valgus (. sd. 1.2); p = 0.60). Conclusion. PCL resection creates flexion-extension mismatch by increasing the flexion gap more than the extension gap. The increase in the lateral flexion gap is greater than the increase in the medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity before PCL resection. Cite this article: Bone Joint J 2019;101-B:1230–1237

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. The aims of this study were to determine the effect of osteophyte excision on deformity correction and soft tissue gap balance in varus knees undergoing computer-assisted total knee arthroplasty (TKA). Methods. A total of 492 consecutive, cemented, cruciate-substituting TKAs performed for varus osteoarthritis were studied. After exposure and excision of both cruciates and menisci, it was noted from operative records the corrective interventions performed in each case. Knees in which no releases after the initial exposure, those which had only osteophyte excision, and those in which further interventions were performed were identified. From recorded navigation data, coronal and sagittal limb alignment, knee flexion range, and medial and lateral gap distances in maximum knee extension and 90° knee flexion with maximal varus and valgus stresses, were established, initially after exposure and excision of both cruciate ligaments, and then also at trialling. Knees were defined as ‘aligned’ if the hip-knee-ankle axis was between 177° and 180°, (0° to 3° varus) and ‘balanced’ if medial and lateral gaps in extension and at 90° flexion were within 2 mm of each other. Results. Of 50 knees (10%) with no soft tissue releases (other than cruciate ligaments), 90% were aligned, 81% were balanced, and 73% were aligned and balanced. In 288 knees (59%) only osteophyte excision was performed by subperiosteally releasing the deep medial collateral ligament. Of these, 98% were aligned, 80% were balanced, and 79% were aligned and balanced. In 154 knees (31%), additional procedures were performed (reduction osteotomy, posterior capsular release, and semimembranosus release). Of these, 89% were aligned, 68% were balanced, and 66% were aligned and balanced. The superficial medial collateral ligament was not released in any case. Conclusion. Two-thirds of all knees could be aligned and balanced with release of the cruciate ligaments alone and excision of osteophytes. Excision of osteophytes can be a useful step towards achieving deformity correction and gap balance without having to resort to soft tissue release in varus knees while maintaining classical coronal and sagittal alignment of components. Cite this article: Bone Joint J 2020;102-B(6 Supple A):49–58

Aims. A number of anti-retroviral therapies (ART) have been implicated in potentially contributing to HIV-associated bone disease. The aim of this study was to evaluate the effect of combination ART on the fracture healing process. Methods. A total of 16 adult male Wistar rats were randomly divided into two groups (n = eight each): Group 1 was given a combination of Tenfovir 30 mg, Lamivudine 30 mg, and Efavirenz 60 mg per day orally, whereas Group 2 was used as a control. After one week of medication preload, all rats underwent a standardized surgical procedure of mid-shaft tibial osteotomy fixed by intramedullary nail with no gap at the fracture site. Progress in fracture healing was monitored regularly for eight weeks. Further evaluations were carried out after euthanasia by micro-CT, mechanically and histologically. Two blinded orthopaedic surgeons used the Radiological Union Scoring system for the Tibia (RUST) to determine fracture healing. Results. The fracture healing process was different between the two groups at week 4 after surgery; only two out of eight rats showed full healing in Group 1 (ART-treated), while seven out of eight rats had bone union in Group 2 (control) (p = 0.040). However, at week eight postoperatively, there was no statistical difference in bone healing; seven out of eight progressed to full union in both groups. Conclusion. This study demonstrated that combination ART resulted in delayed fracture healing at week 4 after surgery in rats, but did not result in the development of nonunion. Cite this article: Bone Joint Res 2022;11(8):585–593

Aims. Cementless acetabular components rely on press-fit fixation for initial stability. In certain cases, initial stability is more difficult to obtain (such as during revision). No current study evaluates how a surgeon’s impaction technique (mallet mass, mallet velocity, and number of strikes) may affect component fixation. This study seeks to answer the following research questions: 1) how does impaction technique affect a) bone strain generation and deterioration (and hence implant stability) and b) seating in different density bones?; and 2) can an impaction technique be recommended to minimize risk of implant loosening while ensuring seating of the acetabular component?. Methods. A custom drop tower was used to simulate surgical strikes seating acetabular components into synthetic bone. Strike velocity and drop mass were varied. Synthetic bone strain was measured using strain gauges and stability was assessed via push-out tests. Polar gap was measured using optical trackers. Results. A phenomenon of strain deterioration was identified if an excessive number of strikes was used to seat a component. This effect was most pronounced in low-density bone at high strike velocities. Polar gap was reduced with increasing strike mass and velocity. Conclusion. A high mallet mass with low strike velocity resulted in satisfactory implant stability and polar gap, while minimizing the risk of losing stability due to over-striking. Extreme caution not to over-strike must be exercised when using high velocity strikes in low-density bone for any mallet mass. Cite this article: Bone Joint Res 2020;9(7):386–393

Aims. Machine-learning (ML) prediction models in orthopaedic trauma hold great promise in assisting clinicians in various tasks, such as personalized risk stratification. However, an overview of current applications and critical appraisal to peer-reviewed guidelines is lacking. The objectives of this study are to 1) provide an overview of current ML prediction models in orthopaedic trauma; 2) evaluate the completeness of reporting following the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) statement; and 3) assess the risk of bias following the Prediction model Risk Of Bias Assessment Tool (PROBAST) tool. Methods. A systematic search screening 3,252 studies identified 45 ML-based prediction models in orthopaedic trauma up to January 2023. The TRIPOD statement assessed transparent reporting and the PROBAST tool the risk of bias. Results. A total of 40 studies reported on training and internal validation; four studies performed both development and external validation, and one study performed only external validation. The most commonly reported outcomes were mortality (33%, 15/45) and length of hospital stay (9%, 4/45), and the majority of prediction models were developed in the hip fracture population (60%, 27/45). The overall median completeness for the TRIPOD statement was 62% (interquartile range 30 to 81%). The overall risk of bias in the PROBAST tool was low in 24% (11/45), high in 69% (31/45), and unclear in 7% (3/45) of the studies. High risk of bias was mainly due to analysis domain concerns including small datasets with low number of outcomes, complete-case analysis in case of missing data, and no reporting of performance measures. Conclusion. The results of this study showed that despite a myriad of potential clinically useful applications, a substantial part of ML studies in orthopaedic trauma lack transparent reporting, and are at high risk of bias. These problems must be resolved by following established guidelines to instil confidence in ML models among patients and clinicians. Otherwise, there will remain a sizeable gap between the development of ML prediction models and their clinical application in our day-to-day orthopaedic trauma practice. Cite this article: Bone Jt Open 2024;5(1):9–19

Aims. The purpose was to evaluate early clinical, patient-reported, and radiological outcomes of the scapholunate ligament 360° tenodesis (SL 360) technique for treatment of scapholunate (SL) instability. Methods. We studied the results of nine patients (eight males and one female with a mean age of 44.7 years (26 to 55)) who underwent the SL 360 procedure for reducible SL instability between January 2016 and June 2019, and who were identified from retrospective review of electronic medical records. Final follow-up of any kind was a mean of 33.7 months (12.0 to 51.3). Clinical, radiological, and patient-reported outcome data included visual analogue scale (VAS) for pain, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), Mayo Wrist Score (MWS), and Patient-Rated Wrist Examination (PRWE). Means were analyzed using paired t-test. Results. Before surgery, patients with SL instability were significantly impaired with respect to wrist flexion, extension, and grip strength (mean flexion, 51° (20° to 85°) vs 73° (45° to 90°); mean extension, 46° (15° to 70°) vs 66° (45° to 80°); mean grip strength, 25 kg (20 to 31) vs 50 kg (35 to 68) compared to the unaffected side). The mean SL gap (4.9 mm (2.3 to 7.3) vs 2.1 mm (1.6 to 2.9)) and mean SL angle (71° (59° to 105°) vs 50° (38° to 64°) were also significantly greater in the affected wrist. At final follow-up, there was mean improvement regarding clinical, radiological, and functional outcomes comparing preoperative to final postoperative values for the VAS for pain scale, QuickDASH, MWS, PRWE, and SL gap and SL angle. Conclusion. In our small series, the SL 360 procedure for reducible SL instability has favourable early clinical, patient-reported, and radiological outcomes at a mean of 33.7 months (12.0 to 51.3). The suture tape and tendon construct confers robust stability, permitting earlier mobilization without the inherent disadvantages of Kirschner wire stabilization. Cite this article: Bone Joint J 2021;103-B(5):939–945

Aims. The aim of this study was to report patient and clinical outcomes following robotic-assisted total knee arthroplasty (RA-TKA) at multiple institutions with a minimum two-year follow-up. Methods. This was a multicentre registry study from October 2016 to June 2021 that included 861 primary RA-TKA patients who completed at least one pre- and postoperative patient-reported outcome measure (PROM) questionnaire, including Forgotten Joint Score (FJS), Knee Injury and Osteoarthritis Outcomes Score for Joint Replacement (KOOS JR), and pain out of 100 points. The mean age was 67 years (35 to 86), 452 were male (53%), mean BMI was 31.5 kg/m. 2. (19 to 58), and 553 (64%) cemented and 308 (36%) cementless implants. Results. There were significant improvements in PROMs over time between preoperative, one- to two-year, and > two-year follow-up, with a mean FJS of 17.5 (SD 18.2), 70.2 (SD 27.8), and 76.7 (SD 25.8; p < 0.001); mean KOOS JR of 51.6 (SD 11.5), 85.1 (SD 13.8), and 87.9 (SD 13.0; p < 0.001); and mean pain scores of 65.7 (SD 20.4), 13.0 (SD 19.1), and 11.3 (SD 19.9; p < 0.001), respectively. There were eight superficial infections (0.9%) and four revisions (0.5%). Conclusion. RA-TKA demonstrated consistent clinical results across multiple institutions with excellent PROMs that continued to improve over time. With the ability to achieve target alignment in the coronal, axial, and sagittal planes and provide intraoperative real-time data to obtain balanced gaps, RA-TKA demonstrated excellent clinical outcomes and PROMs in this patient population. Cite this article: Bone Jt Open 2022;3(7):589–595

Abstract. MAGnetic Expansion Control (MAGEC) rods are used in the surgical treatment of children with early onset scoliosis. The magnetically controlled lengthening mechanism enables rod distractions without the need for repeated invasive surgery. The CE certification of these devices was suspended in March 2021 due, primarily, to performance evidence gaps in the documents provided by the manufacturer to regulators and notified bodies. MAGEC rods are therefore not permitted for use in countries requiring CE marking. This was a survey of 18 MAGEC rod surgeons in the UK about their perception of the impact of the CE suspension on the clinical management of their patients. Unsurprisingly, virtually all perceived a negative impact, reflecting the complexity of this patient group. Reassuringly, these surgeons are highly experienced in alternative treatment methods. Cite this article: Bone Jt Open 2022;3(2):155–157

Aims. Musculoskeletal infection is a devastating complication in both trauma and elective orthopaedic surgeries that can result in significant morbidity. Aim of this study was to assess the effectiveness and complications of local antibiotic impregnated dissolvable synthetic calcium sulphate beads (Stimulan Rapid Cure) in the hands of different surgeons from multiple centres in surgically managed bone and joint infections. Methods. Between January 2019 and December 2022, 106 patients with bone and joint infections were treated by five surgeons in five hospitals. Surgical debridement and calcium sulphate bead insertion was performed for local elution of antibiotics in high concentration. In all, 100 patients were available for follow-up at regular intervals. Choice of antibiotic was tailor made for each patient in consultation with microbiologist based on the organism grown on culture and the sensitivity. In majority of our cases, we used a combination of vancomycin and culture sensitive heat stable antibiotic after a thorough debridement of the site. Primary wound closure was achieved in 99 patients and a split skin graft closure was done in one patient. Mean follow-up was 20 months (12 to 30). Results. Overall, six out of 106 patients (5.6%) presented with sepsis and poorly controlled comorbid conditions, and died in the hospital within few days of index surgery. Out of the remaining 100 patients, control of infection was achieved in 95 patients (95%). Persistence of infection was noted in five (5%) patients. Out of these 95 patients that had good control of infection, four patients (4.2%) with gap nonunion needed Masquelet procedure to achieve union. Conclusion. Our multicentre experience confirmed that surgical debridement along with calcium sulphate bead insertion was effective in treating bone and joint infections without any side effects and complications. Cite this article: Bone Jt Open 2023;4(7):516–522

Aims. The use of biologics in the treatment of musculoskeletal injuries in Olympic and professional athletes appears to be increasing. There are no studies which currently map the extent, range, and nature of existing literature concerning the use and efficacy of such therapies in this arena. The objective of this scoping review is to map the available evidence regarding the use of biologics in the treatment of musculoskeletal injuries in Olympic and professional sport. Methods. Best-practice methodological frameworks suggested by Arksey and O’Malley, Levac et al, and the Joanna Briggs Institute will be used. This scoping review will aim to firstly map the current extent, range, and nature of evidence for biologic strategies to treat injuries in professional and Olympic sport; secondly, to summarize and disseminate existing research findings; and thirdly, to identify gaps in existing literature. A three-step search strategy will identify peer reviewed and non-peer reviewed literature, including reviews, original research, and both published and unpublished (‘grey’) literature. An initial limited search will identify suitable search terms, followed by a search of five electronic databases (MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Web of Science, and Google Scholar) using keyword and index terms. Studies will be screened independently by two reviewers for final inclusion. Dissemination. We will chart key concepts and evidence, and disseminate existing research findings to practitioners and clinicians, through both peer reviewed and non-peer reviewed literature, online platforms (including social media), conference, and in-person communications. We will identify gaps in current literature and priorities for further study

Aims. This study aimed to investigate the estimated change in primary and revision arthroplasty rate in the Netherlands and Denmark for hips, knees, and shoulders during the COVID-19 pandemic in 2020 (COVID-period). Additional points of focus included the comparison of patient characteristics and hospital type (2019 vs COVID-period), and the estimated loss of quality-adjusted life years (QALYs) and impact on waiting lists. Methods. All hip, knee, and shoulder arthroplasties (2014 to 2020) from the Dutch Arthroplasty Register, and hip and knee arthroplasties from the Danish Hip and Knee Arthroplasty Registries, were included. The expected number of arthroplasties per month in 2020 was estimated using Poisson regression, taking into account changes in age and sex distribution of the general Dutch/Danish population over time, calculating observed/expected (O/E) ratios. Country-specific proportions of patient characteristics and hospital type were calculated per indication category (osteoarthritis/other elective/acute). Waiting list outcomes including QALYs were estimated by modelling virtual waiting lists including 0%, 5% and 10% extra capacity. Results. During COVID-period, fewer arthroplasties were performed than expected (Netherlands: 20%; Denmark: 5%), with the lowest O/E in April. In the Netherlands, more acute indications were prioritized, resulting in more American Society of Anesthesiologists grade III to IV patients receiving surgery. In both countries, no other patient prioritization was present. Relatively more arthroplasties were performed in private hospitals. There were no clinically relevant differences in revision arthroplasties between pre-COVID and COVID-period. Estimated total health loss depending on extra capacity ranged from: 19,800 to 29,400 QALYs (Netherlands): 1,700 to 2,400 QALYs (Denmark). With no extra capacity it will take > 30 years to deplete the waiting lists. Conclusion. The COVID-19 pandemic had an enormous negative effect on arthroplasty rates, but more in the Netherlands than Denmark. In the Netherlands, hip and shoulder patients with acute indications were prioritized. Private hospitals filled in part of the capacity gap. QALY loss due to postponed arthroplasty surgeries is considerable. Cite this article: Bone Jt Open 2022;3(12):977–990

Objectives

The aim of this experimental study on New Zealand’s white rabbits was to investigate the transplantation of autogenous growth plate cells in order to treat the injured growth plate. They were assessed in terms of measurements of radiological tibial varus and histological characteristics.

Aims. Many biomechanical studies have shown that the weakest biomechanical point of a rotator cuff repair is the suture-tendon interface at the medial row. We developed a novel double rip-stop (DRS) technique to enhance the strength at the medial row for rotator cuff repair. The objective of this study was to evaluate the biomechanical properties of the DRS technique with the conventional suture-bridge (SB) technique and to evaluate the biomechanical performance of the DRS technique with medial row knots. Methods. A total of 24 fresh-frozen porcine shoulders were used. The infraspinatus tendons were sharply dissected and randomly repaired by one of three techniques: SB repair (SB group), DRS repair (DRS group), and DRS with medial row knots repair (DRSK group). Specimens were tested to failure. In addition, 3 mm gap formation was measured and ultimate failure load, stiffness, and failure modes were recorded. Results. The mean load to create a 3 mm gap formation in the DRSK and DRS groups was significantly higher than in the SB group. The DRSK group had the highest load to failure with a mean ultimate failure load of 395.0 N (SD 56.8) compared to the SB and DRS groups, which recorded 147.1 N (SD 34.3) and 285.9 N (SD 89.8), respectively (p < 0.001 for both). The DRS group showed a significantly higher mean failure load than the SB group (p = 0.006). Both the DRS and DRSK groups showed significantly higher mean stiffness than the SB group. Conclusion. The biomechanical properties of the DRS technique were significantly improved compared to the SB technique. The DRS technique with medial row knots showed superior biomechanical performance than the DRS technique alone

Aims. A growing number of fractures progress to delayed or nonunion, causing significant morbidity and socioeconomic impact. Localized delivery of stem cells and subcutaneous parathyroid hormone (PTH) has been shown individually to accelerate bony regeneration. This study aimed to combine the therapies with the aim of upregulating fracture healing. Methods. A 1.5 mm femoral osteotomy (delayed union model) was created in 48 female juvenile Wistar rats, aged six to nine months, and stabilized using an external fixator. At day 0, animals were treated with intrafracture injections of 1 × 10. 6. cells/kg bone marrow mesenchymal stem cells (MSCs) suspended in fibrin, daily subcutaneous injections of high (100 μg/kg) or low (25 μg/kg) dose PTH 1-34, or a combination of PTH and MSCs. A group with an empty gap served as a control. Five weeks post-surgery, the femur was excised for radiological, histomorphometric, micro-CT, and mechanical analysis. Results. Combination therapy treatment led to increased callus formation compared to controls. In the high-dose combination group there was significantly greater mineralized tissue volume and trabecular parameters compared to controls (p = 0.039). This translated to significantly improved stiffness (and ultimate load to failure (p = 0.049). The high-dose combination therapy group had the most significant improvement in mean modified Radiographic Union Score for Tibia fractures (RUST) compared to controls (13.8 (SD 1.3) vs 5.8 (SD 0.5)). All groups demonstrated significant increases in the radiological scores – RUST and Allen score – histologically compared to controls. Conclusion. We demonstrate the beneficial effect of localized MSC injections on fracture healing combined with low- or high-dose teriparatide, with efficacy dependent on PTH dose. Cite this article: Bone Joint Res 2021;10(10):659–667

Aims. Precise implant positioning, tailored to individual spinopelvic biomechanics and phenotype, is paramount for stability in total hip arthroplasty (THA). Despite a few studies on instability prediction, there is a notable gap in research utilizing artificial intelligence (AI). The objective of our pilot study was to evaluate the feasibility of developing an AI algorithm tailored to individual spinopelvic mechanics and patient phenotype for predicting impingement. Methods. This international, multicentre prospective cohort study across two centres encompassed 157 adults undergoing primary robotic arm-assisted THA. Impingement during specific flexion and extension stances was identified using the virtual range of motion (ROM) tool of the robotic software. The primary AI model, the Light Gradient-Boosting Machine (LGBM), used tabular data to predict impingement presence, direction (flexion or extension), and type. A secondary model integrating tabular data with plain anteroposterior pelvis radiographs was evaluated to assess for any potential enhancement in prediction accuracy. Results. We identified nine predictors from an analysis of baseline spinopelvic characteristics and surgical planning parameters. Using fivefold cross-validation, the LGBM achieved 70.2% impingement prediction accuracy. With impingement data, the LGBM estimated direction with 85% accuracy, while the support vector machine (SVM) determined impingement type with 72.9% accuracy. After integrating imaging data with a multilayer perceptron (tabular) and a convolutional neural network (radiograph), the LGBM’s prediction was 68.1%. Both combined and LGBM-only had similar impingement direction prediction rates (around 84.5%). Conclusion. This study is a pioneering effort in leveraging AI for impingement prediction in THA, utilizing a comprehensive, real-world clinical dataset. Our machine-learning algorithm demonstrated promising accuracy in predicting impingement, its type, and direction. While the addition of imaging data to our deep-learning algorithm did not boost accuracy, the potential for refined annotations, such as landmark markings, offers avenues for future enhancement. Prior to clinical integration, external validation and larger-scale testing of this algorithm are essential. Cite this article: Bone Jt Open 2024;5(8):671–680

Aims. This systematic review places a recently completed multicentre randomized controlled trial (RCT), UK FROST, in the context of existing randomized evidence for the management of primary frozen shoulder. UK FROST compared the effectiveness of pre-specified physiotherapy techniques with a steroid injection (PTSI), manipulation under anaesthesia (MUA) with a steroid injection, and arthroscopic capsular release (ACR). This review updates a 2012 review focusing on the effectiveness of MUA, ACR, hydrodilatation, and PTSI. Methods. MEDLINE, Embase, PEDro, Science Citation Index, Clinicaltrials.gov, CENTRAL, and the World Health Organization (WHO) International Clinical Trials Registry were searched up to December 2018. Reference lists of included studies were screened. No language restrictions applied. Eligible studies were RCTs comparing the effectiveness of MUA, ACR, PTSI, and hydrodilatation against each other, or supportive care or no treatment, for the management of primary frozen shoulder. Results. Nine RCTs were included. The primary outcome of patient-reported shoulder function at long-term follow-up (> 6 months and ≤ 12 months) was reported for five treatment comparisons across four studies. Standardized mean differences (SMD) were: ACR versus MUA: 0.21 (95% confidence interval (CI) 0.00 to 0.42), ACR versus supportive care: -0.13 (95% CI -1.10 to 0.83), and ACR versus PTSI: 0.33 (95% CI 0.07 to 0.59) and 0.25 (95% CI -0.34 to 0.85), all favouring ACR; MUA versus supportive care: 0 (95% CI -0.44 to 0.44) not favouring either; and MUA versus PTSI: 0.12 (95% CI -0.14 to 0.37) favouring MUA. None of these differences met the threshold of clinical significance agreed for the UK FROST and most confidence intervals included zero. Conclusion. The findings from a recent multicentre RCT provided the strongest evidence that, when compared with each other, neither PTSI, MUA, nor ACR are clinically superior. Evidence from smaller RCTs did not change this conclusion. The effectiveness of hydrodilatation based on four RCTs was inconclusive and there remains an evidence gap. Cite this article: Bone Jt Open 2021;2(9):773–784