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. This study aims to enhance understanding of clinical and radiological consequences and involved mechanisms that led to corrosion of the Precice Stryde (Stryde) intramedullary lengthening nail in the post market surveillance era of the device. Between 2018 and 2021 more than 2,000 Stryde nails have been implanted worldwide. However, the outcome of treatment with the Stryde system is insufficiently reported. Methods. This is a retrospective single-centre study analyzing outcome of 57 consecutive lengthening procedures performed with the Stryde nail at the authors’ institution from February 2019 until November 2020. Macro- and microscopic metallographic analysis of four retrieved nails was conducted. To investigate observed corrosion at telescoping junction, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) were performed. Results. Adjacent to the nail’s telescoping junction, osteolytic changes were observed in bi-planar radiographs of 20/57 segments (35%) after a mean of 9.5 months (95% confidence interval 7.2 to 11.9) after surgery. A total of 8/20 patients with osseous alterations (40%) reported rest and ambulation pain of the lengthened segment during consolidation. So far, 24 Stryde nails were retrieved and in 20 (83%) macroscopic corrosion was observed at the nail’s telescoping junction. Before implant removal 11/20 radiographs (55%) of lengthened segments with these 20 nails revealed osteolysis. Implant retrieval analysis by means of SEM showed pitting and crevice corrosion. EDX detected chromium as the main metallic element of corrosion. Conclusion. Patients are exposed to the risk of implant-related osteolysis of unclear short- and long-term clinical consequences. The authors advocate in favour of an early implant removal after osseous consolidation. Cite this article: Bone Joint Res 2021;10(7):425–436

Objectives. Bioresorbable orthopaedic devices with calcium phosphate (CaP) fillers are commercially available on the assumption that increased calcium (Ca) locally drives new bone formation, but the clinical benefits are unknown. Electron beam (EB) irradiation of polymer devices has been shown to enhance the release of Ca. The aims of this study were to: 1) establish the biological safety of EB surface-modified bioresorbable devices; 2) test the release kinetics of CaP from a polymer device; and 3) establish any subsequent beneficial effects on bone repair in vivo. Methods. ActivaScrew Interference (Bioretec Ltd, Tampere, Finland) and poly(L-lactide-co-glycolide) (PLGA) orthopaedic screws containing 10 wt% β-tricalcium phosphate (β-TCP) underwent EB treatment. In vitro degradation over 36 weeks was investigated by recording mass loss, pH change, and Ca release. Implant performance was investigated in vivo over 36 weeks using a lapine femoral condyle model. Bone growth and osteoclast activity were assessed by histology and enzyme histochemistry. Results. Calcium release doubled in the EB-treated group before returning to a level seen in untreated samples at 28 weeks. Extensive bone growth was observed around the perimeter of all implant types, along with limited osteoclastic activity. No statistically significant differences between comparative groups was identified. Conclusion. The higher than normal dose of EB used for surface modification did not adversely affect tissue response around implants in vivo. Surprisingly, incorporation of β-TCP and the subsequent accelerated release of Ca had no significant effect on in vivo implant performance, calling into question the clinical evidence base for these commercially available devices. Cite this article: I. Palmer, S. A. Clarke, F. J Buchanan. Enhanced release of calcium phosphate additives from bioresorbable orthopaedic devices using irradiation technology is non-beneficial in a rabbit model: An animal study. Bone Joint Res 2019;8:266–274. DOI: 10.1302/2046-3758.86.BJR-2018-0224.R2

Objectives. Platelet-rich fibrin matrix (PRFM) has been proved to enhance tenocyte proliferation but has mixed results when used during rotator cuff repair. The optimal PRFM preparation protocol should be determined before clinical application. To screen the best PRFM to each individual’s tenocytes effectively, small-diameter culture wells should be used to increase variables. The gelling effect of PRFM will occur when small-diameter culture wells are used. A co-culture device should be designed to avoid this effect. Methods. Tenocytes harvested during rotator cuff repair and blood from a healthy volunteer were used. Tenocytes were seeded in 96-, 24-, 12-, and six-well plates and co-culture devices. Appropriate volumes of PRFM, according to the surface area of each culture well, were treated with tenocytes for seven days. The co-culture device was designed to avoid the gelling effect that occurred in the small-diameter culture well. Cell proliferation was analyzed by water soluble tetrazolium-1 (WST-1) bioassay. Results. The relative quantification (condition/control) of WST-1 assay on day seven revealed a significant decrease in tenocyte proliferation in small-diameter culture wells (96 and 24 wells) due to the gelling effect. PRFM in large-diameter culture wells (12 and six wells) and co-culture systems induced a significant increase in tenocyte proliferation compared with the control group. The gelling effect of PRFM was avoided by the co-culture device. Conclusion. When PRFM and tenocytes are cultured in small-diameter culture wells, the gelling effect will occur and make screening of personalized best-fit PRFM difficult. This effect can be avoided with the co-culture device. Cite this article: C-H. Chiu, P. Chen, W-L. Yeh, A. C-Y. Chen, Y-S. Chan, K-Y. Hsu, K-F. Lei. The gelling effect of platelet-rich fibrin matrix when exposed to human tenocytes from the rotator cuff in small-diameter culture wells and the design of a co-culture device to overcome this phenomenon. Bone Joint Res 2019;8:216–223. DOI: 10.1302/2046-3758.85.BJR-2018-0258.R1

Aims. This study aims to evaluate a new home medical stretching device called the Self Treatment Assisted Knee (STAK) tool to treat knee arthrofibrosis. Methods. 35 patients post-major knee surgery with arthrofibrosis and mean range of movement (ROM) of 68° were recruited. Both the STAK intervention and control group received standard physiotherapy for eight weeks, with the intervention group additionally using the STAK at home. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Knee Scores (OKS) were collected at all timepoints. An acceptability and home exercise questionnaire capturing adherence was recorded after each of the interventions. Results. Compared to the control group, the STAK intervention group made significant gains in mean ROM (30° versus 8°, p < 0.0005), WOMAC (19 points versus 3, p < 0.0005), and OKS (8 points versus 3, p < 0.0005). The improvements in the STAK group were maintained at long-term follow-up. No patients suffered any complications relating to the STAK, and 96% of patients found the STAK tool ‘perfectly acceptable’. Conclusion. The STAK tool is effective in increasing ROM and reducing pain and stiffness. Patients find it acceptable and adherence to treatment was high. This study indicates that the STAK tool would be of benefit in clinical practice and may offer a new, cost-effective treatment for arthrofibrosis. Cite this article: Bone Joint Open 2020;1-8:465–473

Objectives. Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs. Methods. Synthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests. Results. The method of loading was found to affect the gap stiffness strongly (by up to six times) but also the magnitude of the plate stress and the location and magnitude of strains at the bone-screw interface. Conclusions. This study demonstrates that the method of loading is responsible for much of the difference in reported stiffness values in the literature. It also shows that previous contradictory findings, such as the influence of working length and very large differences in failure loads, can be readily explained by the choice of loading condition. Cite this article: A. MacLeod, A. H. R. W. Simpson, P. Pankaj. Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices. Bone Joint Res 2018;7:111–120. DOI: 10.1302/2046-3758.71.BJR-2017-0074.R2

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. There are concerns regarding complications and longevity of total elbow arthroplasty (TEA) in young patients, and the few previous publications are mainly limited to reports on linked elbow devices. We investigated the clinical outcome of unlinked TEA for patients aged less than 50 years with rheumatoid arthritis (RA). Methods. We retrospectively reviewed the records of 26 elbows of 21 patients with RA who were aged less than 50 years who underwent primary TEA with an unlinked elbow prosthesis. The mean patient age was 46 years (35 to 49), and the mean follow-up period was 13.6 years (6 to 27). Outcome measures included pain, range of motion, Mayo Elbow Performance Score (MEPS), radiological evaluation for radiolucent line and loosening, complications, and revision surgery with or without implant removal. Results. The mean MEPS significantly improved from 47 (15 to 70) points preoperatively to 95 (70 to 100) points at final follow-up (p < 0.001). Complications were noted in six elbows (23%) in six patients, and of these, four with an ulnar neuropathy and one elbow with postoperative traumatic fracture required additional surgeries. There was no revision with implant removal, and there was no radiological evidence of loosening around the components. With any revision surgery as the endpoint, the survival rates up to 25 years were 78.1% (95% confidence interval 52.8 to 90.6) as determined by Kaplan-Meier analysis. Conclusion. The clinical outcome of primary unlinked TEA for young patients with RA was satisfactory and comparable with that for elderly patients. A favourable survival rate without implant removal might support the use of unlinked devices for young patients with this disease entity, with a caution of a relatively high complication rate regarding ulnar neuropathy. Level of Evidence: Therapeutic Level IV. Cite this article: Bone Jt Open 2023;4(1):19–26

Aims. To fully verify the reliability and reproducibility of an experimental method in generating standardized micromotion for the rat femur fracture model. Methods. A modularized experimental device has been developed that allows rat models to be used instead of large animal models, with the aim of reducing systematic errors and time and money constraints on grouping. The bench test was used to determine the difference between the measured and set values of the micromotion produced by this device under different simulated loading weights. The displacement of the fixator under different loading conditions was measured by compression tests, which was used to simulate the unexpected micromotion caused by the rat’s ambulation. In vivo preliminary experiments with a small sample size were used to test the feasibility and effectiveness of the whole experimental scheme and surgical scheme. Results. The bench test showed that a weight loading < 500 g did not affect the operation of experimental device. The compression test demonstrated that the stiffness of the device was sufficient to keep the uncontrollable motion between fracture ends, resulting from the rat’s daily activities, within 1% strain. In vivo results on 15 rats prove that the device works reliably, without overburdening the experimental animals, and provides standardized micromotion reproductively at the fracture site according to the set parameters. Conclusion. Our device was able to investigate the effect of micromotion parameters on fracture healing by generating standardized micromotion to small animal models. Cite this article: Bone Joint Res 2021;10(11):714–722

Aims. The primary aim of this study is to assess the survival of the uncemented hydroxyapatite (HA) coated Trident II acetabular component as part of a hybrid total hip arthroplasty (THA) using a cemented Exeter stem. The secondary aims are to assess the complications, joint-specific function, health-related quality of life, and radiological signs of loosening of the acetabular component. Methods. A single-centre, prospective cohort study of 125 implants will be undertaken. Patients undergoing hybrid THA at the study centre will be recruited. Inclusion criteria are patients suitable for the use of the uncemented acetabular component, aged 18 to 75 years, willing and able to comply with the study protocol, and provide informed consent. Exclusion criteria includes patients not meeting study inclusion criteria, inadequate bone stock to support fixation of the prosthesis, a BMI > 40 kg/m. 2. , or THA performed for pain relief in those with severely restricted mobility. Results. Implant survival, complications, functional outcomes and radiological assessment up to ten years following index THA (one, two, five, seven, and ten years) will be performed. Functional assessment will include the Oxford Hip Score, Forgotten Joint Score, 12-Item Short Form Health Survey, EuroQol five-dimension health questionnaire, and pain and patient satisfaction. Radiological assessment with assess for acetabula lucent lines, lysis, and loosening according to DeLee and Charnley zones. Conclusion. This study is part of a stepwise introduction of a new device to orthopaedic practice, and careful monitoring of implants should be carried out as part of the Beyond Compliance principles. The results of this study will provide functional, radiological, and survival data to either support the ongoing use of the HA acetabulum or highlight potential limitations of this new implant before wide adoption. Cite this article: Bone Jt Open 2023;4(10):782–790

Aims. Taper corrosion has been widely reported to be problematic for modular total hip arthroplasty implants. A simple and systematic method to evaluate taper damage with sufficient resolution is needed. We introduce a semiquantitative grading system for modular femoral tapers to characterize taper corrosion damage. Methods. After examining a unique collection of retrieved cobalt-chromium (CoCr) taper sleeves (n = 465) using the widely-used Goldberg system, we developed an expanded six-point visual grading system intended to characterize the severity, visible material loss, and absence of direct component contact due to corrosion. Female taper sleeve damage was evaluated by three blinded observers using the Goldberg scoring system and the expanded system. A subset (n = 85) was then re-evaluated following destructive cleaning, using both scoring systems. Material loss for this subset was quantified using metrology and correlated with both scoring systems. Results. There was substantial agreement in grading among all three observers with uncleaned (n = 465) and with the subset of cleaned (n = 85) implants. The expanded scoring criteria provided a wider distribution of scores which ultimately correlated well with corrosion material loss. Cleaning changed the average scores marginally using the Goldberg criteria (p = 0.290); however, using the VGS, approximately 40% of the scores for all observers changed, increasing the average score from 4.24 to 4.35 (p = 0.002). There was a strong correlation between measured material loss and new grading scores. Conclusion. The expanded scoring criteria provided a wider distribution of scores which ultimately correlated well with corrosion material loss. This system provides potential advantages for assessing taper damage without requiring specialized imaging devices. Cite this article: Bone Joint Res 2023;12(3):155–164

Aims. Arthroscopic microfracture is a conventional form of treatment for patients with osteochondritis of the talus, involving an area of < 1.5 cm. 2. However, some patients have persistent pain and limitation of movement in the early postoperative period. No studies have investigated the combined treatment of microfracture and shortwave treatment in these patients. The aim of this prospective single-centre, randomized, double-blind, placebo-controlled trial was to compare the outcome in patients treated with arthroscopic microfracture combined with radial extracorporeal shockwave therapy (rESWT) and arthroscopic microfracture alone, in patients with ostechondritis of the talus. Methods. Patients were randomly enrolled into two groups. At three weeks postoperatively, the rESWT group was given shockwave treatment, once every other day, for five treatments. In the control group the head of the device which delivered the treatment had no energy output. The two groups were evaluated before surgery and at six weeks and three, six and 12 months postoperatively. The primary outcome measure was the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale. Secondary outcome measures included a visual analogue scale (VAS) score for pain and the area of bone marrow oedema of the talus as identified on sagittal fat suppression sequence MRI scans. Results. A total of 40 patients were enrolled and randomly divided into the two groups, with 20 in each. There was no statistically significant difference in the baseline characteristics of the groups. No complications, such as wound infection or neurovascular injury, were found during follow-up of 12 months. The mean AOFAS scores in the rESWT group were significantly higher than those in the control group at three, six, and 12 months postoperatively (p < 0.05). The mean VAS pain scores in the rESWT group were also significantly lower than those in the control group at these times (p < 0.05). The mean area of bone marrow oedema in the rESWT group was significantly smaller at six and 12 months than in the control group at these times (p < 0.05). Conclusion. Local shockwave therapy was safe and effective in patients with osteochondiritis of the talus who were treated with a combination of arthroscopic surgery and rESWT. Preliminary results showed that, compared with arthroscopic microfracture alone, those treated with arthroscopic microfracture combined with rESWT had better relief of pain at three months postoperatively and improved weightbearing and motor function of the ankle. Cite this article: Bone Joint J 2023;105-B(10):1108–1114

Aims. The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI). Methods. This is a retrospective cohort study of operatively managed orthopaedic trauma patients from 1 January 2007 to 31 December 2016, performed in Queensland, Australia. Record linkage was used to develop a person-centric, population-based dataset incorporating routinely collected administrative, clinical, and health economic information. The FRI group consisted of patients with International Classification of Disease 10th Revision diagnosis codes for deep infection associated with an implanted device within two years following surgery, while all others were deemed not infected. Demographic and clinical variables, as well as healthcare utilization costs, were compared. Results. There were 111,402 patients operatively managed for orthopaedic trauma, with 2,775 of these (2.5%) complicated by FRI. The development of FRI had a statistically significant association with older age, male sex, residing in rural/remote areas, Aboriginal or Torres Strait Islander background, lower socioeconomic status, road traffic accident, work-related injuries, open fractures, anatomical region (lower limb, spine, pelvis), high injury severity, requiring soft-tissue coverage, and medical comorbidities (univariate analysis). Patients with FRI had an eight-times longer median inpatient length of stay (24 days vs 3 days), and a 2.8-times higher mean estimated inpatient hospitalization cost (AU$56,565 vs AU$19,773) compared with uninfected patients. The total estimated inpatient cost of the FRI cohort to the healthcare system was AU$156.9 million over the ten-year period. Conclusion. The results of this study advocate for improvements in trauma care and infection management, address social determinants of health, and highlight the upside potential to improve prevention and treatment strategies. Cite this article: Bone Joint J 2024;106-B(1):77–85

Aims. Rotator cuff (RC) tears are common musculoskeletal injuries which often require surgical intervention. Noninvasive pulsed electromagnetic field (PEMF) devices have been approved for treatment of long-bone fracture nonunions and as an adjunct to lumbar and cervical spine fusion surgery. This study aimed to assess the effect of continuous PEMF on postoperative RC healing in a rat RC repair model. Methods. A total of 30 Wistar rats underwent acute bilateral supraspinatus tear and repair. A miniaturized electromagnetic device (MED) was implanted at the right shoulder and generated focused PEMF therapy. The animals’ left shoulders served as controls. Biomechanical, histological, and bone properties were assessed at three and six weeks. Results. Extension of the tendon from preload to the maximum load to failure was significantly better in the PEMF-treated shoulders at three weeks compared to controls (p = 0.038). The percentage strain was significantly higher in the PEMF group at both timepoints (p = 0.037). Collagen organization was significantly better (p = 0.034) as was tissue mineral density in the PEMF-treated group at three weeks (p = 0.028). Tendon immunohistochemistry revealed a prominent increase in type I collagen at the repair site at three weeks following continuous PEMF treatment compared with controls. None of the other tested parameters differed between the groups. Conclusion. MED-generated PEMF may enhance early postoperative tendon-to-bone healing in an acute rat supraspinatus detachment and repair model. Superior biomechanical elasticity parameters together with better collagen organization suggest improved RC healing. Cite this article: Bone Joint Res 2021;10(5):298–306

Aims. Orthopaedic surgery uses many varied instruments with high-speed, high-impact, thermal energy and sometimes heavy instruments, all of which potentially result in aerosolization of contaminated blood, tissue, and bone, raising concerns for clinicians’ health. This study quantifies the aerosol exposure by measuring the number and size distribution of the particles reaching the lead surgeon during key orthopaedic operations. Methods. The aerosol yield from 17 orthopaedic open surgeries (on the knee, hip, and shoulder) was recorded at the position of the lead surgeon using an Aerodynamic Particle Sizer (APS; 0.5 to 20 μm diameter particles) sampling at 1 s time resolution. Through timestamping, detected aerosol was attributed to specific procedures. Results. Diathermy (electrocautery) and oscillating bone saw use had a high aerosol yield (> 100 particles detected per s) consistent with high exposure to aerosol in the respirable range (< 5 µm) for the lead surgeon. Pulsed lavage, reaming, osteotome use, and jig application/removal were medium aerosol yield (10 to 100 particles s. -1. ). However, pulsed lavage aerosol was largely attributed to the saline jet, osteotome use was always brief, and jig application/removal had a large variability in the associated aerosol yield. Suctioning (with/without saline irrigation) had a low aerosol yield (< 10 particles s. -1. ). Most surprisingly, other high-speed procedures, such as drilling and screwing, had low aerosol yields. Conclusion. This work suggests that additional precautions should be recommended for diathermy and bone sawing, such as enhanced personal protective equipment or the use of suction devices to reduce exposure. Cite this article: Bone Joint Res 2023;12(10):636–643

Aims. Varus-valgus constrained (VVC) devices are typically used in revision settings, often with stems to mitigate the risk of aseptic loosening. However, in at least one system, the VVC insert is compatible with the primary posterior-stabilized (PS) femoral component, which may be an option in complex primary situations. We sought to determine the implant survivorship, radiological and clinical outcomes, and complications when this VVC insert was coupled with a PS femur without stems in complex primary total knee arthroplasties (TKAs). Methods. Through our institution’s total joint registry, we identified 113 primary TKAs (103 patients) performed between 2007 and 2017 in which a VVC insert was coupled with a standard cemented PS femur without stems. Mean age was 68 years (SD 10), mean BMI was 32 kg/m. 2. (SD 7), and 59 patients (50%) were male. Mean follow-up was four years (2 to 10). Results. The five-year survivorship free from aseptic loosening was 100%. The five-year survivorship free from any revision was 99%, with the only revision performed for infection. The five-year survivorship free from reoperation was 93%. The most common reoperation was treatment for infection (n = 4; 4%), followed by manipulation under anaesthesia (MUA; n = 2; 2%). Survivorship free from any complication at five years was 90%, with superficial wound infection as the most frequent (n = 4; 4%). At most recent follow-up, two TKAs had non-progressive radiolucent lines about both the tibial and femoral components. Knee Society Scores improved from 53 preoperatively to 88 at latest follow-up (p < 0.001). Conclusion. For complex primary TKA in occasional situations, coupling a VVC insert with a standard PS femur without stems proved reliable and durable at five years. Longer-term follow-up is required before recommending this technique more broadly. Cite this article: Bone Jt Open 2021;2(11):921–925

Aims. To evaluate graft healing of decellularized porcine superflexor tendon (pSFT) xenograft in an ovine anterior cruciate ligament (ACL) reconstruction model using two femoral fixation devices. Also, to determine if pSFT allows functional recovery of gait as compared with the preoperative measurements. Methods. A total of 12 sheep underwent unilateral single-bundle ACL reconstruction using pSFT. Two femoral fixation devices were investigated: Group 1 (n = 6) used cortical suspensory fixation (Endobutton CL) and Group 2 (n = 6) used cross-pin fixation (Stratis ST). A soft screw was used for tibial fixation. Functional recovery was quantified using force plate analysis at weeks 5, 8, and 11. The sheep were euthanized after 12 weeks and comprehensive histological analysis characterized graft healing at the graft-bone interface and the intra-articular graft (ligamentization). Results. The pSFT remodelled into a ligament-like structure and no adverse inflammatory reaction was seen. The ground reaction force in the operated leg of the Endobutton group was higher at 11 weeks (p < 0.05). An indirect insertion was seen at the graft-bone interface characterized by Sharpey-like fibres. Qualitative differences in tendon remodelling were seen between the two groups, with greater crimp-like organization and more aligned collagen fibres seen with Endobutton fixation. One graft rupture occurred in the cross-pin group, which histologically showed low collagen organization. Conclusion. Decellularized pSFT xenograft remodels into a ligament-like structure after 12 weeks and regenerates an indirect-type insertion with Sharpey-like fibres. No adverse inflammatory reaction was observed. Cortical suspensory femoral fixation was associated with more enhanced graft remodelling and earlier functional recovery when compared with the stiffer cross-pin fixation

Aims. Navigation devices are designed to improve a surgeon’s accuracy in positioning the acetabular and femoral components in total hip arthroplasty (THA). The purpose of this study was to both evaluate the accuracy of an optical computer-assisted surgery (CAS) navigation system and determine whether preoperative spinopelvic mobility (categorized as hypermobile, normal, or stiff) increased the risk of acetabular component placement error. Methods. A total of 356 patients undergoing primary THA were prospectively enrolled from November 2016 to March 2018. Clinically relevant error using the CAS system was defined as a difference of > 5° between CAS and 3D radiological reconstruction measurements for acetabular component inclination and anteversion. Univariate and multiple logistic regression analyses were conducted to determine whether hypermobile (. Δ. sacral slope(SS). stand-sit. > 30°), or stiff (. ∆. SS. stand-sit. < 10°) spinopelvic mobility contributed to increased error rates. Results. The paired absolute difference between CAS and postoperative imaging measurements was 2.3° (standard deviation (SD) 2.6°) for inclination and 3.1° (SD 4.2°) for anteversion. Using a target zone of 40° (± 10°) (inclination) and 20° (± 10°) (anteversion), postoperative standing radiographs measured 96% of acetabular components within the target zone for both inclination and anteversion. Multiple logistic regression analysis controlling for BMI and sex revealed that hypermobile spinopelvic mobility significantly increased error rates for anteversion (odds ratio (OR) 2.48, p = 0.009) and inclination (OR 2.44, p = 0.016), whereas stiff spinopelvic mobility increased error rates for anteversion (OR 1.97, p = 0.028). There were no dislocations at a minimum three-year follow-up. Conclusion. Despite high reliability in acetabular positioning for inclination in a large patient cohort using an optical CAS system, hypermobile and stiff spinopelvic mobility significantly increased the risk of clinically relevant errors. In patients with abnormal spinopelvic mobility, CAS systems should be adjusted for use to avoid acetabular component misalignment and subsequent risk for long-term dislocation. Cite this article: Bone Jt Open 2022;3(6):475–484

Aims. Temporary epiphysiodesis (ED) is commonly applied in children and adolescents to treat leg length discrepancies (LLDs) and tall stature. Traditional Blount staples or modern two-hole plates are used in clinical practice. However, they require accurate planning, precise surgical techniques, and attentive follow-up to achieve the desired outcome without complications. This study reports the results of ED using a novel rigid staple (RigidTack) incorporating safety, as well as technical and procedural success according to the idea, development, evaluation, assessment, long-term (IDEAL) study framework. Methods. A cohort of 56 patients, including 45 unilateral EDs for LLD and 11 bilateral EDs for tall stature, were prospectively analyzed. ED was performed with 222 rigid staples with a mean follow-up of 24.4 months (8 to 49). Patients with a predicted LLD of ≥ 2 cm at skeletal maturity were included. Mean age at surgery was 12.1 years (8 to 14). Correction and complication rates including implant-associated problems, and secondary deformities as well as perioperative parameters, were recorded (IDEAL stage 2a). These results were compared to historical cohorts treated for correction of LLD with two-hole plates or Blount staples. Results. The mean LLD was reduced from 25.2 mm (15 to 45) before surgery to 9.3 mm (6 to 25) at skeletal maturity. Implant-associated complications occurred in 4/56 treatments (7%), and secondary frontal plane deformities were detected in 5/45 legs (11%) of the LLD cohort. Including tall stature patients, the rate increased to 12/67 legs (18%). Sagittal plane deformities were observed during 1/45 LLD treatments (2%). Compared to two-hole plates and Blount staples, similar correction rates were observed in all devices. Lower rates of frontal and sagittal plane deformities were observed using rigid staples. Conclusion. Treatment of LLD using novel rigid staples appears a feasible and promising strategy. Secondary frontal and sagittal plane deformities remain a potential complication, although the rate seems to be lower in patients treated with rigid staples. Further comparative studies are needed to investigate this issue. Cite this article: Bone Joint J 2021;103-B(8):1428–1437