Mg-Zn-Ca Alloy (ZX00) Screws Are Resorbed at a Mean of 2.5 Years After Medial Malleolar Fracture Fixation: Follow-up of a First-in-humans Application and Insights From a Sheep Model.

In the ongoing development of bioresorbable implants, there has been a particular focus on magnesium (Mg)-based alloys. Several Mg alloys have shown promising properties, including a lean, bioresorbable magnesium-zinc-calcium (Mg-Zn-Ca) alloy designated as ZX00. To our knowledge, this is the first clinically tested Mg-based alloy free from rare-earth elements or other elements. Its use in medial malleolar fractures has allowed for bone healing without requiring surgical removal. It is thus of interest to assess the resorption behavior of this novel bioresorbable implant. (1) What is the behavior of implanted Mg-alloy (ZX00) screws in terms of resorption (implant volume, implant surface, and gas volume) and bone response (histologic evaluation) in a sheep model after 13 months and 25 months? (2) What are the radiographic changes and clinical outcomes, including patient-reported outcome measures, at a mean of 2.5 years after Mg-alloy (ZX00) screw fixation in patients with medial malleolar fractures? A sheep model was used to assess 18 Mg-alloy (ZX00) different-length screws (29 mm, 24 mm, and 16 mm) implanted in the tibiae and compared with six titanium-alloy screws. Micro-CT was performed at 13 and 25 months to quantify the implant volume, implant surface, and gas volume at the implant sites, as well as histology at both timepoints. Between July 2018 and October 2019, we treated 20 patients with ZX00 screws for medial malleolar fractures in a first-in-humans study. We considered isolated, bimalleolar, or trimalleolar fractures potentially eligible. Thus, 20 patients were eligible for follow-up. However, 5% (one patient) of patients were excluded from the analysis because of an unplanned surgery for a pre-existing osteochondral lesion of the talus performed 17 months after ZX00 implantation. Additionally, another 5% (one patient) of patients were lost before reaching the minimum study follow-up period. Our required minimum follow-up period was 18 months to ensure sufficient time to observe the outcomes of interest. At this timepoint, 10% (two patients) of patients were either missing or lost to follow-up. The follow-up time was a mean of 2.5 ± 0.6 years and a median of 2.4 years (range 18 to 43 months). In this sheep model, after 13 months, the 29-mm screws (initial volume: 198 ± 1 mm 3 ) degraded by 41% (116 ± 6 mm 3 , mean difference 82 [95% CI 71 to 92]; p < 0.001), and after 25 months by 65% (69 ± 7 mm 3 , mean difference 130 [95% CI 117 to 142]; p < 0.001). After 13 months, the 24-mm screws (initial volume: 174 ± 0.2 mm 3 ) degraded by 51% (86 ± 21 mm 3 , mean difference 88 [95% CI 52 to 123]; p = 0.004), and after 25 months by 72% (49 ± 25 mm 3 , mean difference 125 [95% CI 83 to 167]; p = 0.003). After 13 months, the 16-mm screws (initial volume: 112 ± 5 mm 3 ) degraded by 57% (49 ± 8 mm 3 , mean difference 63 [95% CI 50 to 76]; p < 0.001), and after 25 months by 61% (45 ± 10 mm 3 , mean difference 67 [95% CI 52 to 82]; p < 0.001). Histologic evaluation qualitatively showed ongoing resorption with new bone formation closely connected to the resorbing screw without an inflammatory reaction. In patients treated with Mg-alloy screws after a mean of 2.5 years, the implants were radiographically not visible in 17 of 18 patients and the bone had homogenous texture in 15 of 18 patients. No clinical or patient-reported complications were observed. In this sheep model, Mg-alloy (ZX00) screws showed a resorption to one-third of the original volume after 25 months, without eliciting adverse immunologic reactions, supporting biocompatibility during this period. Mg-alloy (ZX00) implants were not detectable on radiographs after a mean of 2.5 years, suggesting full resorption, but further studies are needed to assess environmental changes regarding bone quality at the implantation site after implant resorption. The study demonstrated successful healing of medial malleolar fractures using bioresorbable Mg-alloy screws without clinical complications or revision surgery, resulting in pain-free ankle function after 2.5 years. Future prospective studies with larger samples and extended follow-up periods are necessary to comprehensively assess the long-term effectiveness and safety of ZX00 screws, including an exploration of limitations when there is altered bone integrity, such as in those with osteoporosis. Additional use of advanced imaging techniques, such as high-resolution CT, can enhance evaluation accuracy.

Labmayr V ，Suljevic O ，Sommer NG ，Schwarze UY ，Marek RL ，Brcic I ，Foessl I ，Leithner A ，Seibert FJ ，Herber V ，Holweg PL ... -  《-》

What Are the Functional, Radiographic, and Survivorship Outcomes of a Modified Cup-cage Technique for Pelvic Discontinuity?

Pelvic discontinuity (PD) presents a complex challenge in revision hip arthroplasty. The traditional cup-cage construct, which involves a screw-secured porous metal cup and an overlying antiprotrusio cage, has shown promising mid- to long-term results. However, there is limited information on the outcomes of modifications to the original technique. Our study aims to evaluate a modified technique in which the cup position is determined by the placement of the overlying cage, allowing for adjustments to achieve optimal orientation. Among patients treated for PD with a cup-cage construct in which the cup position was dictated by the position of the cage: (1) What are Harris hip scores achieved at a minimum of 2 years of follow-up? (2) What is the Kaplan-Meier survivorship free from aseptic loosening or component migration? (3) What is the Kaplan-Meier survivorship free from revision for any reason? (4) What surgical complications are associated with the procedure? Between October 2013 and January 2022, we performed 805 acetabular revisions. Among these, 33 patients with PD confirmed intraoperatively were considered potentially eligible for a cup-cage construct; no other method of surgical management was used. We performed 64% (21 of 33) of these procedures from October 2013 to January 2018, with 6% (2 of 33) of patients lost to follow-up before the minimum study follow-up of 2 years; these 19 patients were monitored over a period ranging from 70 to 115 months. A further 12 patients underwent this procedure from January 2018 to January 2022, with one lost to follow-up before the minimum study follow-up of 2 years; the other patients met the minimum 2-year follow-up requirement. The remaining 30 patients with data analyzed here (10 men, 20 women) had a mean ± SD age of 61 ± 12 years and a median BMI of 29 kg/m 2 (range 20 to 33 kg/m 2 ) at the time of revision surgery. Twenty-one patients underwent revision due to aseptic loosening, and nine due to periprosthetic joint infection (PJI). The causes of PD in our patients were as follows: cup aseptic loosening without significant osteolysis in 20% (6 of 30), where the loose cup caused erosion of the host bone, leading to PD; PJI in 30% (9 of 30); intraoperative iatrogenic PD in 3% (1 of 30); and osteolysis in 47% (14 of 30), which also resulted in aseptic loosening. The median follow-up time was 79 months (range 25 to 115 months). The Harris hip score was used to evaluate clinical outcomes, with preoperative values compared with the most recent follow-up. Radiographs were reviewed by two experienced surgeons at each follow-up visit to assess component loosening (defined as migration > 5 mm or the presence of circumferential radiolucent lines) or clear migration. PD was considered healed if bridging callus or trabecular bone was visible across the site of the discontinuity. Complications were assessed through a comprehensive review of electronic medical records. Kaplan-Meier analysis was used to estimate implant survivorship and radiographic loosening, with aseptic loosening or component migration as the endpoint, as well as survivorship free from any reoperation. The Harris hip score improved from a median of 39 (range 30 to 66) preoperatively to a median of 76 (range 30 to 90) postoperatively (median difference 33 [range 2 to 48]; p < 0.01). Within the limitations of two-dimensional (2D) radiographic imaging, successful bone graft integration and the healing of PD were noted in 83% (25 of 30) of patients. Kaplan-Meier survivorship free from radiographic signs of aseptic loosening or component migration was 100% (95% CI 100% to 100%) at 115 months. When any revision related to the acetabular component was considered the endpoint, survivorship free from acetabular component revision at 115 months after revision surgery was 100% (95% CI 100% to 100%). When the need for any reoperation was considered the endpoint, survivorship free from needing reoperation at 115 months after revision surgery was 85% for all patients (95% CI 73% to 100%). When including only patients with a follow-up time of > 4 years (20 of 30), survivorship free from needing reoperation at 115 months after revision surgery was 90% (95% CI 78% to 100%). Postoperative complications during the follow-up period included one early dislocation on the fifth day after surgery, treated with closed reduction and 6 weeks of abduction bracing. One femoral stem loosening occurred at 56 months postoperatively, although the acetabular component remained securely fixed; this patient declined revision surgery. One patient experienced a dislocation 5 months after surgery but refused treatment and opted for prolonged bed rest. Additionally, one patient underwent a debridement, antibiotics, and implant retention procedure 1 week after the revision surgery and subsequently showed no signs of infection at the latest follow-up, 38 months postoperatively. Our study highlights the effectiveness of a modified cup-cage technique in complex hip revisions, showing promising results in terms of construct survivorship and low complication rates. Surgeons could consider delaying screw fixation until after positioning the cage within the porous cup to allow for optimal adjustment and using metal augments for severe bone defects to achieve better alignment. Surgeon experience with the cup-cage technique is crucial for achieving optimal outcomes. Future studies should focus on long-term follow-up visits to assess the durability and effectiveness of these modifications and explore the comparative effectiveness versus other methods, such as custom triflange components and jumbo cups with distraction. Level III, therapeutic study.

Mu W ，Xu B ，Wahafu T ，Wang F ，Guo W ，Zou C ，Cao L ... -  《-》

Far Posterior Approach for Rib Fracture Fixation: Surgical Technique and Tips.

The present video article describes the far posterior or paraspinal approach to posterior rib fractures. This approach is utilized to optimize visualization intraoperatively in cases of far-posterior rib fractures. This technique is also muscle-sparing, and muscle-sparing posterolateral, axillary, and anterior approaches have been shown to return up to 95% of periscapular strength by 6 months postoperatively1. Like most fractures, the skin incision depends on the fracture position. The vertical incision is made either just medial to a line equidistant between the palpable spinous processes and medial scapular border or directly centered over the fracture line in this region. The incision and superficial dissection must be extended cranially and caudally, approximately 1 or 2 rib levels past the planned levels of instrumentation, in order to allow muscle elevation and soft-tissue retraction. Superficial dissection reveals the trapezius muscle, with its fibers coursing from inferomedial to superolateral caudal to the scapular spine, and generally coursing transversely above this level. The trapezius is split in line with its fibers (or elevated proximally at the caudal-most surface), and the underlying layer will depend on the location of the incision. The rhomboid minor muscle overlies ribs 1 and 2, the rhomboid major muscle overlies ribs 3 to 7, and the latissimus dorsi overlies the remaining rib levels. To avoid muscle transection, the underlying muscle is also split in line with its fibers. Next, the thoracolumbar fascia is encountered and sharply incised, revealing the erector spinae muscles, which comprise the spinalis thoracis, longissimus thoracis, and iliocostalis thoracis muscles. These muscles and their tendons must be sharply elevated from lateral to midline; electrocautery is useful for this because there is a robust blood supply in this region. Medially, while retracting the paraspinal musculature, visualization with this approach can extend to the head and neck of the rib, and even to the spine. Following deep dissection, the fractures are now visualized. During fracture reduction, it is critical to assess reduction of both the costovertebral joint and the costotransverse joint. With fractures closer to the spine, it is recommended to have at least 2 cm between the rib head and tubercle in order to allow 2 plate holes to be positioned on the neck of the rib; if comminution exists and plating onto the transverse process is needed, several screws are required here for stability as well. For appropriate stability if plating onto the spine is not required, a minimum of 3 locking screws on each side of the fracture are recommended. Contouring of the plates to match the curvature of the rib and to allow for proper apposition may be required with posterior rib fractures. Screws must be placed perpendicular to the rib surface. Following operative stabilization of the rib fractures, a layered closure is performed, and a soft dressing is applied. Nonoperative alternatives include non-opioid and opioid medications as well as corticosteroid injections for pain control. Supportive mechanical ventilation and physiotherapy breathing exercises can also be implemented as needed. Operative alternatives include open reduction and internal fixation utilizing conventional locking plates and screws. Rib fractures are often treated nonoperatively when nondisplaced because of the surrounding soft-tissue support2,3. According to Chest Wall Injury Society guidelines, contraindications to surgical fixation of rib fractures include patients requiring ongoing resuscitation; rib fractures involving ribs 1, 2, 11, or 12, which are relative contraindications; severe traumatic brain injury; and acute myocardial infarction. Patient age of <18 years is also a relative contraindication for the operative treatment of rib fractures. The current literature does not recommend surgical fixation in this age group because these fractures typically heal as the patient ages; however, fracture-dislocations may require the use of instrumentation to prevent displacement. Currently, the U.S. Food and Drug Administration does not approve most plating systems for patients <18 years old4. In certain cases, including those with substantial displacement, persistent respiratory distress, pain, or fracture nonunion, stabilization with open reduction and internal fixation may be appropriate5-7. In cases of flail chest injuries, surgery is often indicated6. Flail chest injuries have been noted in the literature to have an incidence of approximately 150 cases per 100,000 injuries and have been shown to carry a mortality rate of up to 33%8,9. Surgical treatment of rib fractures has been shown to be associated with a decreased hospital length of stay and mortality rate in patients with major trauma1. Expected outcomes of this procedure include low complication rates, decreased hospital and intensive care unit length of stay, and reduced mechanical ventilation time10,11. However, as with any procedure, there are also risks involved, including iatrogenic lung injury from long screws or an aortic or inferior vena cava injury with aggressive manipulation of displaced fractured fragments, especially on the left side of the body. During open reduction, there is also a risk of injuring the neurovascular bundle. Tanaka et al. demonstrated a significant reduction in the rate of postoperative pneumonia in their operative group (22%) compared with their nonoperative group (90%)12. Schuette et al. demonstrated a 23% rate of postoperative pneumonia, 0% mortality at 1 year, an average of 6.2 days in the intensive care unit, an average total hospital length of stay of 17.3 days, and an average total ventilator time of 4 days in the operative group10. Prins et al. reported a significantly lower incidence of pneumonia in operative (24%) versus nonoperative patients (47.3%; p = 0.033), as well as a significantly lower 30-day mortality rate (0% versus 17.7%; p = 0.018)3. This procedure utilizes a muscle-sparing technique, which has demonstrated successful results in the literature on the use of the posterolateral, axillary, and anterior approaches, returning up to 95% of periscapular strength, compared with the uninjured shoulder, by 6 months postoperatively1. The use of a muscle-sparing technique with the far-posterior approach represents a topic that requires further study in order to compare the results with the successful results previously shown with other approaches. The ipsilateral extremity can be prepared into the field to allow its intraoperative manipulation in order to achieve scapulothoracic motion and improved subscapular access.For costovertebral fracture-dislocations, the vertical incision line is made just medial to a line equidistant between the palpable spinous processes and medial scapular border.Lateral decubitus positioning can be utilized to allow for simultaneous access to fractures that extend more laterally and warrant a posterolateral approach; however, it is generally more difficult to access the fracture sites near the spine with this approach.This muscle-sparing technique is recommended to optimize postoperative periscapular strength, as previously demonstrated with other approaches.Incision and superficial dissection must be extended cranially and caudally approximately 1 or 2 rib levels past the planned levels of instrumentation in order to allow muscle elevation and soft-tissue retraction.To avoid muscle transection during surgical dissection, the underlying muscle is split in line with its fibers.During deep dissection, it can be difficult to delineate underlying muscles because these muscles have fibers that do not run in line with the trapezius, and some, like the rhomboid major, run nearly perpendicular to it.Electrocautery is useful while elevating the erector spinae muscles and tendons, as there is a robust blood supply in this region.The erector spinae muscle complex is relatively tight and adherent to the underlying ribs, which may make it difficult to achieve adequate visualization; therefore, at least 3 rib levels must be elevated to access a rib for reduction and instrumentation.Although internal rotation deformities are more common in this region, any external displacement of a fracture can lead to a muscle injury that can be utilized for access.During fracture reduction, it is critical to assess reduction of both the costovertebral joint and the costotransverse joint.Special attention must be given to contouring the implants because there are not any commercially available precontoured implants for this region at this time, and plating onto the spine remains an off-label use of any currently available implant.For the more challenging fracture patterns, the use of a right-angled power drill and screwdriver is recommended.Generally, the incision is utilized as previously described to provide access as far medial as the transverse process if needed. However, in cases in which this approach does not allow proper visualization with rib fracture-dislocations involving the posterior ribs or spine, a midline spinal incision can be utilized while working in combination with a spine surgeon.With fractures closer to the spine, it is recommended to have at least 2 cm between the rib head and tubercle in order to allow 2 plate holes to be positioned on the neck of the rib.If comminution exists and plating onto the transverse process is needed, several screws are required for stability.When measuring the length of screws to be placed in the transverse process, preoperative CT scans can be utilized. CT = computed tomographyCWIS = Chest Wall Injury SocietyIVC = inferior vena cava.

Manes TJ ，DeGenova DT ，Taylor BC ，Patel JN ... -  《-》

Comparison of Two Modern Survival Prediction Tools, SORG-MLA and METSSS, in Patients With Symptomatic Long-bone Metastases Who Underwent Local Treatment With Surgery Followed by Radiotherapy and With Radiotherapy Alone.

Survival estimation for patients with symptomatic skeletal metastases ideally should be made before a type of local treatment has already been determined. Currently available survival prediction tools, however, were generated using data from patients treated either operatively or with local radiation alone, raising concerns about whether they would generalize well to all patients presenting for assessment. The Skeletal Oncology Research Group machine-learning algorithm (SORG-MLA), trained with institution-based data of surgically treated patients, and the Metastases location, Elderly, Tumor primary, Sex, Sickness/comorbidity, and Site of radiotherapy model (METSSS), trained with registry-based data of patients treated with radiotherapy alone, are two of the most recently developed survival prediction models, but they have not been tested on patients whose local treatment strategy is not yet decided. (1) Which of these two survival prediction models performed better in a mixed cohort made up both of patients who received local treatment with surgery followed by radiotherapy and who had radiation alone for symptomatic bone metastases? (2) Which model performed better among patients whose local treatment consisted of only palliative radiotherapy? (3) Are laboratory values used by SORG-MLA, which are not included in METSSS, independently associated with survival after controlling for predictions made by METSSS? Between 2010 and 2018, we provided local treatment for 2113 adult patients with skeletal metastases in the extremities at an urban tertiary referral academic medical center using one of two strategies: (1) surgery followed by postoperative radiotherapy or (2) palliative radiotherapy alone. Every patient's survivorship status was ascertained either by their medical records or the national death registry from the Taiwanese National Health Insurance Administration. After applying a priori designated exclusion criteria, 91% (1920) were analyzed here. Among them, 48% (920) of the patients were female, and the median (IQR) age was 62 years (53 to 70 years). Lung was the most common primary tumor site (41% [782]), and 59% (1128) of patients had other skeletal metastases in addition to the treated lesion(s). In general, the indications for surgery were the presence of a complete pathologic fracture or an impending pathologic fracture, defined as having a Mirels score of ≥ 9, in patients with an American Society of Anesthesiologists (ASA) classification of less than or equal to IV and who were considered fit for surgery. The indications for radiotherapy were relief of pain, local tumor control, prevention of skeletal-related events, and any combination of the above. In all, 84% (1610) of the patients received palliative radiotherapy alone as local treatment for the target lesion(s), and 16% (310) underwent surgery followed by postoperative radiotherapy. Neither METSSS nor SORG-MLA was used at the point of care to aid clinical decision-making during the treatment period. Survival was retrospectively estimated by these two models to test their potential for providing survival probabilities. We first compared SORG to METSSS in the entire population. Then, we repeated the comparison in patients who received local treatment with palliative radiation alone. We assessed model performance by area under the receiver operating characteristic curve (AUROC), calibration analysis, Brier score, and decision curve analysis (DCA). The AUROC measures discrimination, which is the ability to distinguish patients with the event of interest (such as death at a particular time point) from those without. AUROC typically ranges from 0.5 to 1.0, with 0.5 indicating random guessing and 1.0 a perfect prediction, and in general, an AUROC of ≥ 0.7 indicates adequate discrimination for clinical use. Calibration refers to the agreement between the predicted outcomes (in this case, survival probabilities) and the actual outcomes, with a perfect calibration curve having an intercept of 0 and a slope of 1. A positive intercept indicates that the actual survival is generally underestimated by the prediction model, and a negative intercept suggests the opposite (overestimation). When comparing models, an intercept closer to 0 typically indicates better calibration. Calibration can also be summarized as log(O:E), the logarithm scale of the ratio of observed (O) to expected (E) survivors. A log(O:E) > 0 signals an underestimation (the observed survival is greater than the predicted survival); and a log(O:E) < 0 indicates the opposite (the observed survival is lower than the predicted survival). A model with a log(O:E) closer to 0 is generally considered better calibrated. The Brier score is the mean squared difference between the model predictions and the observed outcomes, and it ranges from 0 (best prediction) to 1 (worst prediction). The Brier score captures both discrimination and calibration, and it is considered a measure of overall model performance. In Brier score analysis, the "null model" assigns a predicted probability equal to the prevalence of the outcome and represents a model that adds no new information. A prediction model should achieve a Brier score at least lower than the null-model Brier score to be considered as useful. The DCA was developed as a method to determine whether using a model to inform treatment decisions would do more good than harm. It plots the net benefit of making decisions based on the model's predictions across all possible risk thresholds (or cost-to-benefit ratios) in relation to the two default strategies of treating all or no patients. The care provider can decide on an acceptable risk threshold for the proposed treatment in an individual and assess the corresponding net benefit to determine whether consulting with the model is superior to adopting the default strategies. Finally, we examined whether laboratory data, which were not included in the METSSS model, would have been independently associated with survival after controlling for the METSSS model's predictions by using the multivariable logistic and Cox proportional hazards regression analyses. Between the two models, only SORG-MLA achieved adequate discrimination (an AUROC of > 0.7) in the entire cohort (of patients treated operatively or with radiation alone) and in the subgroup of patients treated with palliative radiotherapy alone. SORG-MLA outperformed METSSS by a wide margin on discrimination, calibration, and Brier score analyses in not only the entire cohort but also the subgroup of patients whose local treatment consisted of radiotherapy alone. In both the entire cohort and the subgroup, DCA demonstrated that SORG-MLA provided more net benefit compared with the two default strategies (of treating all or no patients) and compared with METSSS when risk thresholds ranged from 0.2 to 0.9 at both 90 days and 1 year, indicating that using SORG-MLA as a decision-making aid was beneficial when a patient's individualized risk threshold for opting for treatment was 0.2 to 0.9. Higher albumin, lower alkaline phosphatase, lower calcium, higher hemoglobin, lower international normalized ratio, higher lymphocytes, lower neutrophils, lower neutrophil-to-lymphocyte ratio, lower platelet-to-lymphocyte ratio, higher sodium, and lower white blood cells were independently associated with better 1-year and overall survival after adjusting for the predictions made by METSSS. Based on these discoveries, clinicians might choose to consult SORG-MLA instead of METSSS for survival estimation in patients with long-bone metastases presenting for evaluation of local treatment. Basing a treatment decision on the predictions of SORG-MLA could be beneficial when a patient's individualized risk threshold for opting to undergo a particular treatment strategy ranged from 0.2 to 0.9. Future studies might investigate relevant laboratory items when constructing or refining a survival estimation model because these data demonstrated prognostic value independent of the predictions of the METSSS model, and future studies might also seek to keep these models up to date using data from diverse, contemporary patients undergoing both modern operative and nonoperative treatments. Level III, diagnostic study.

Lee CC ，Chen CW ，Yen HK ，Lin YP ，Lai CY ，Wang JL ，Groot OQ ，Janssen SJ ，Schwab JH ，Hsu FM ，Lin WH ... -  《-》

Defining the optimum strategy for identifying adults and children with coeliac disease: systematic review and economic modelling.

Elwenspoek MM ，Thom H ，Sheppard AL ，Keeney E ，O'Donnell R ，Jackson J ，Roadevin C ，Dawson S ，Lane D ，Stubbs J ，Everitt H ，Watson JC ，Hay AD ，Gillett P ，Robins G ，Jones HE ，Mallett S ，Whiting PF ... -  《-》