Joint Reconstruction Research Articles

Local delivery of linezolid in the treatment of complex orthopedic bone and joint infections in patients with vancomycin allergy: a case series.

Introduction: Osteomyelitis is a challenging bone infection associated with ischemia, trauma, or various surgical procedures (e.g., joint reconstruction). Treatment involves eradicating infected bone and soft tissue, local antibiotic delivery, and a 6-week course of antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) infections are common, and vancomycin is the standard treatment, but alternatives like linezolid are needed in vancomycin-resistant and vancomycin-allergic patients. Methods: A retrospective chart review was conducted on patients treated by the senior author between 2013 and 2021. The study included patients who received local delivery of linezolid for bone and/or joint infection with documented evidence of vancomycin allergy. Patient demographics, surgical details, linezolid delivery method, and outcomes were recorded. Clinical outcomes and subsequent procedures leading to infection eradication were documented. Results: A total of 13 patients were treated with linezolid-antibiotic-laden spacers with polymethyl methacrylate (PMMA) carrier. Nine patients were successfully treated using limb-salvage techniques and were still infection-free after a mean follow-up of 55.5 months. Conclusions: Linezolid-loaded bone cement is an option for managing chronic bone and joint infections, particularly MRSA, in patients with vancomycin allergy.

Technical note for intraoperative determination of proper acetabular cup size in primary total hip arthroplasty.

Selecting the optimal size of components is crucial when performing a primary total hip arthroplasty. Implanting the accurate size of the acetabular component can occasionally be exacting, chiefly for surgeons with little experience, whilst the complications of imprecise acetabular sizing or over-reaming can be potentially devastating. To assist clinicians intraoperatively with a simple and repeatable tip in elucidating the ambivalence when determining the proper acetabular component size is not straightforwardly achieved, specifically when surgeons are inexperienced or preoperative templating is unavailable. This method was employed in 263 operations in our department from June 2021 to December 2022. All operations were performed by the same team of joint reconstruction surgeons, employing a typical posterior hip approach technique. The types of acetabular shells implanted were: The Dynasty® acetabular cup system (MicroPort Orthopedics, Shanghai, China) and the R3® acetabular system (Smith & Nephew, Watford, United Kingdom), which both feature cementless press-fit design. The mean value of all cases was calculated and collated with each other. We distinguished as oversized an implanted acetabular shell when its size was > 2 mm larger than the size of the acetabular size indicator reamer (ASIR) or when the implanted shell was larger than 4 mm compared to the preoperative planned cup. The median size of the implanted acetabular shell was 52 (48-54) mm, while the median size of the preoperatively planned cup was 50 (48-56) mm, and the median size of the ASIR was 52 (50-54) mm. The correlation coefficient between ASIR size and implanted acetabular component size exhibited a high positive correlation with r = 0.719 (P < 0.001). Contrariwise, intraoperative ASIR measurements precisely predicted the implanted cups' size or differed by only one size (2 mm) in 245 cases. In our study, we demonstrated that the size of the first acetabular reamer not entering freely in the acetabular rim corroborates the final acetabular component size to implant. This was also corresponding in the majority of the cases with conventional preoperative templating. It can be featured as a valid tool for avoiding the potentially pernicious complications of acetabular cup over-reaming and over-sizing in primary total hip arthroplasty. It is a simple and reproducible technical note useful for confirming the predicted acetabular cup size preoperatively; thus, its application could be considered routinely, even in cases where preoperative templating is unavailable.

Acromioclavicular Joint Reconstruction with Modified Weaver–Dunn Operation Versus Hamstring Tendon Autograft Comparative Study

Abstract Background: The dislocation of the acromioclavicular joint (ACJ) is recognized as one of the most frequently occurring injuries most often after either direct or indirect force is applied to the affected shoulder. The best method of AC reconstruction is still controversial. Modified Weaver–Dunn operation (WD) is one of the popular operations. Recent ACJ reconstruction methods include the usage of the gracilis, semitendinosus auto grafts, synthetic grafts, end buttons, nonabsorbable sutures, suture anchors, and tight-rope system. Aim and Objectives: Clinical and radiological results of hamstring autograft versus modified WD operation for reconsrtuction of coracoclavicular and acromioclavicular ligaments. Patients and Methods: This prospective study was carried out at the orthopedic department of Benha University Hospital carried out on 30 cases with chronic ACJ dislocation. They divided into two groups. The modified WD technique was employed on 15 patients, whereas an autogenous semitendinosus tendon graft was used on the other 15. There was a comparison of radiographs taken before and after surgery. Results: Mean surgical time and coracoclavicular (CC) distance differed statistically between groups. Neither demographic data nor postoperative information (pain, range of motion, and postop) showed a difference of statistical significance between the groups. Constant score and post operative American Shoulder and Elbow Surgeons Score (ASES) and post operative complications show no statistically significant difference. Conclusion: Both AC and CC reconstruction by hamstring tendon autograft showed good-to-excellent outcomes with no implant-related complications as some other treatment methods, also more anatomical procedure more than WD operation with better biomechanical vertical and horizontal stability.

Quality of life and clinical outcomes in severely involved cerebral palsy patients and spastic hips undergoing Castle surgery: a cross-sectional study.

As progressive hip dislocation causes pain in children with spastic cerebral palsy (CP) and spasticity needs surgical correction, we aimed to describe clinical and radiographic outcomes in CP patients with painful hip deformity treated with the Castle salvage procedure. We included all patients operated in the same hospital between 1989 and 2017 with painful spastic hips and femoral head deformity making joint reconstruction unfeasible. We collected clinical and functional data from medical records and evaluated radiographies to classify cases for femoral head shape and migration, type of deformity, spinal deformity, and heterotopic ossification. We investigated quality of life oneyear after surgery. We analyzed 41 patients (70 hips) with complete medical records. All had severe function compromise GMFCS V (Gross Motor Function Classification System) and heterotopic ossifications, all but one had scoliosis, and most had undergone other surgeries before Castle procedure. Patients were followed up for 77.1months (mean) after surgery. The mean initial migration index was 73%. Seven patients had complications, being three patients minor (two femur and one tibial fracture) and four majors (patients requiring surgical revision). Quality of life was considered improved by most of the carers (35 children; 85.3%) as level 4/5 according to CPCHILD instrument. No child was able to stand or walk, but moving in and out of bed, of vehicles, and to a chair, remaining seated, or visiting public places was "very easy." We considered most patients (37 patients-90%, 66 hips-94%) as having satisfactory outcomes because they had no or minor complications, absence of pain, free mobility of the lower limbs and were able to sit in a wheelchair.

Clavicular tunnel widening after acromioclavicular joint reconstruction: comparison between single and double clavicular tunnel techniques.

Acromioclavicular joint (ACJ) reconstruction using artificial ligaments is a common surgical treatment for Rockwood grade III or higher injuries. These techniques use bone tunnels in the clavicle and coracoid to insert the Tightrope implants. This multicenter retrospective study compares long term radiographic follow up of clavicular tunnel widening in two groups of patients with high-grade ACJ injury who underwent reconstruction using two different surgical techniques. The first group of 23 patients underwent an arthroscopic single clavicular tunnel ACJ reconstruction. The second group of 23 patiënts underwent an open double clavicular tunnel reconstruction. Inclusion criteria are Rockwood grade III or higher injury and minimum 18 months of follow-up. Exclusion criteria are distal clavicle fracture and additional stabilization techniques. Radiographic results were measured on anteroposterior shoulder radiographs taken at the first and last follow-up. Clavicular tunnel widening is the main outcome measurement. Secondary outcomes are heterotopic ligament calcifications, migration of buttons, tunnel fracture and loss of acromioclavicular reduction. The mean clavicular tunnel widening in the single clavicular tunnel technique is 1.91 mm. In the double clavicular tunnel technique, the widening of the medial tunnel is 2.52 mm and 3.59 mm in the lateral tunnel. The difference in widening between the single tunnel and the lateral tunnel is significant (p=0.003). A very clear observation on all follow-up X-rays was a reorientation of the clavicular tunnels towards the coracoid. The double clavicular tunnel technique has more tunnel widening in both tunnels compared to the single bundle technique.

Anatomic Popliteus Tendon and Tibiofibular Joint Reconstructions

Background: The popliteus tendon is a primary stabilizer of external knee rotation and has been described as the “fifth ligament of the knee.” Injuries involving the posterolateral corner of the knee commonly involve the popliteus tendon; isolated injury to the popliteus tendon is relatively rare and usually involves a rotatory injury mechanism and symptoms of instability and pain. In this patient, there was a concomitant injury to the proximal tibiofibular joint. Indications: Popliteus tendon reconstruction is indicated for patients with abnormal external rotation on examination and symptoms of pain and instability. Proximal tibiofibular joint reconstruction is indicated for patients with instability of the tibiofibular joint. Technique Description: Preoperative examination under anesthesia is essential to determine the extent of external rotation and assess for additional posterolateral pathology. The popliteus tendon procedure begins with a meticulous common peroneal nerve neurolysis to minimize nerve irritation and decrease the risk of a postoperative foot drop. Semitendinosus and gracilis graft harvest is performed with at least 16 cm of graft length followed by tunnel reaming of the popliteus tendon femoral attachment and tibia tunnel identification and reaming. The femoral attachment of the popliteus tendon is secured, and the semitendinosus graft is anatomically oriented along the native path and passed from posterior to anterior through the femoral tunnel. The gracilis graft for anatomic proximal tibiofibular joint reconstruction requires an anterior to posterior tunnel through the fibular head. Finally, both grafts are secured in the tibial tunnel with the application of an anterior traction force. Results: A cadaveric study by LaPrade et al reported that an anatomic popliteus tendon reconstruction with a semitendinosus autograft significantly reduced external rotation laxity compared with the sectioned state. In addition, popliteus tendon reconstruction resulted in significantly decreased varus laxity, anterior tibial translation, and internal rotation. Discussion: This is a technique that effectively restores external rotation knee stability utilizing an anatomically oriented reconstruction of the popliteus tendon and tibiofibular joint. The popliteus tendon serves as a primary stabilizer to external rotation and facilitates static function of the knee. The proximal tibiofibular joint reconstruction restores the function of the posterior proximal tibiofibular joint ligaments. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Arthroscopic-Assisted Core Decompression of Humeral Head Osteonecrosis With Bone Marrow Aspirate Concentrate Augmentation

Background: The proximal humerus is the second-most common anatomic site for osteonecrosis, a condition of disrupted blood supply leading to death of bone tissue, with resultant shoulder pain and dysfunction. Core decompression is a viable joint-preserving surgical intervention that aims to improve local blood supply and restore bone health prior to bony collapse. Indications: Humeral head osteonecrosis has numerous underlying causes, most commonly the sequelae of prior trauma, chronic use of systemic corticosteroids, sickle cell disease, and alcohol abuse. Core decompression may be indicated in the early, pre-collapse stages of osteonecrosis, whereas more advanced stages of disease are commonly indicated for joint reconstruction procedures, such as bone grafting or arthroplasty. Technique Description: With the patient in the beach chair position, bone marrow aspirate concentrate (BMAC) is harvested through a percutaneous incision along the anterolateral proximal humerus. While viewing through a standard posterior portal, a transtibial anterior cruciate ligament (ACL) guide is placed through an anterior portal at a site on the humeral head surface, centered at the area of greatest humeral head bone edema as identified on preoperative magnetic resonance imaging. A guide pin is placed through a lateral portal within the ACL guide, to the subchondral bone. A 7.0-mm reamer is applied over the guidewire, followed by administration of demineralized bone matrix soaked in BMAC into the reamed channel within the proximal humerus. Results: In patients with early stages of humeral head osteonecrosis, core decompression confers superior clinical outcomes with reduced rates of subsequent surgical procedures compared with nonoperative treatment. Core decompression has shown to reduce the radiographic progression of osteonecrosis. Further research is necessary to determine the additional clinical benefits of augmentation with orthobiologic agents, such as BMAC. Conclusion: Arthroscopic-assisted core decompression is a valuable, minimally invasive surgical treatment for early-stage proximal humerus osteonecrosis. Adjunctive treatment with BMAC and demineralized bone matrix may enhance clinical outcomes. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Development of novel hybrid 3D-printed degradable artificial joints incorporating electrospun pharmaceutical- and growth factor-loaded nanofibers for small joint reconstruction

Small joint reconstruction remains challenging and can lead to prosthesis-related complications, mainly due to the suboptimal performance of the silicone materials used and adverse host reactions. In this study, we developed hybrid artificial joints using three-dimensional printing (3D printing) for polycaprolactone (PCL) and incorporated electrospun nanofibers loaded with drugs and biomolecules for small joint reconstruction. We evaluated the mechanical properties of the degradable joints and the drug discharge patterns of the nanofibers. Empirical data revealed that the 3D-printed PCL joints exhibited good mechanical and fatigue properties. The drug-eluting nanofibers sustainedly released teicoplanin, ceftazidime, and ketorolac in vitro for over 30, 19, and 30 days, respectively. Furthermore, the nanofibers released high levels of bone morphogenetic protein-2 and connective tissue growth factors for over 30 days. An in vivo animal test demonstrated that nanofiber-loaded joints released high concentrations of antibiotics and analgesics in a rabbit model for 28 days. The animals in the drug-loaded degradable joint group showed greater activity counts than those in the surgery-only group. The experimental data suggest that degradable joints with sustained release of drugs and biomolecules may be utilized in small joint arthroplasty.

Application of high hip center technique in total hip arthroplasty in patients with Crowe typeⅡand Ⅲ developmental dysplasia of hip and severe hip osteoarthritis

To explore the clinical efficacy of high hip center technique total hip arthroplasty （THA） for Crowe Ⅱand Ⅲ developmental dysplasia of hip （DDH） and severe hip osteoarthritis （HOA）. From January 2018 to January 2020, 74 patients with Crowe typeⅡand Ⅲ DDH and severe HOA were admitted, and 37 cases of anatomical hip center reconstruction were taken as control group, including 7 males and 30 females, aged from 42 to 65 years old with an average of （58.40±4.98） years old, body mass index （BMI） ranged from 18 to 29 kg·m-2 with an average of （23.02±2.21） kg·m-2. Thirty-seven routine high hip center technical reconstruction were performed as study group, including 5 males and 32 females, aged from 41 to 65 years old with an average of （57.31±5.42） years old, BMI ranged from 18 to 29 kg·m-2 with an average of （23.14±2.07） kg·m-2. The patients presented with hip pain, limited function and range of motion, and gait instability before surgery. All patients underwent THA, the control group underwent intraoperative anatomical hip center reconstruction, and the study group underwent intraoperative high hip joint reconstruction. The perioperative indicators of the two groups were compared. The hip joint function, balance function and gait of the patients were evaluated before surgery, 3 months, 6 months, and 12 months after surgery. The length difference of both lower limbs, horizontal distance of rotation center, vertical distance of rotation center and femoral eccentricity were measured before operation and 1 year after operation. The incidence of complications in the two groups during the operation and postoperative follow-up was counted. The operation time of the study group was shorter than that of the control group, and the intraoperative blood loss was less than that of the control group （P<0.05）. After 12-months follow-up, 1 was lost to followvup in study group and 2 were lost to follow-up in control group. The Harris scores and Berg balance scale（BBS）, pace, stride frequency and single step length in the study group were higher than those in the control group at 3 months and 6 months after operation （P<0.05）；there was no statistically significant difference between the two groups in the indexes 12 months after operation （P>0.05）. The vertical distance of the center of rotation of the study group was greater than that of the control group 12 months after operation （P<0.05）, and there was no significant difference in the length difference of the lower limbs, the horizontal distance of the center of rotation, and the femoral eccentricity between two groups （P>0.05）. There were no complications in either group. The long-term effects of THA in patients with DDH and severe HOA were similar between the two central hip reconstruction methods, and the safety was good, and the high hip central reconstruction technique could shorten the operation time and reduce the amount of intraoperative blood loss.At the same time, it has certain advantages in early recovery of hip joint function, balance function and walking function of patients.

Assessing Ability for ChatGPT to Answer Total Knee Arthroplasty-Related Questions

BackgroundArtificial intelligence in the field of orthopaedics has been a topic of increasing interest and opportunity in recent years. Its applications are widespread both for physicians and patients, including use in clinical decision-making, in the operating room, and in research. In this study, we aimed to assess the quality of ChatGPT answers when asked questions related to total knee arthroplasty. MethodsChatGPT prompts were created by turning 15 of the American Academy of Orthopaedic Surgeons Clinical Practice Guidelines into questions. An online survey was created, which included screenshots of each prompt and answers to the 15 questions. Surgeons were asked to grade ChatGPT answers from 1 to 5 based on their characteristics: (1) relevance, (2) accuracy, (3) clarity, (4) completeness, (5) evidence-based, and (6) consistency. There were 11 Adult Joint Reconstruction fellowship-trained surgeons who completed the survey. Questions were subclassified based on the subject of the prompt: (1) risk factors, (2) implant/intraoperative, and (3) pain/functional outcomes. The average and standard deviation for all answers, as well as for each subgroup, were calculated. Inter-rater reliability (IRR) was also calculated. ResultsAll answer characteristics were graded as being above average (ie, a score > 3). Relevance demonstrated the highest scores (4.43 ± 0.77) by surgeons surveyed, and consistency demonstrated the lowest scores (3.54 ± 1.10). ChatGPT prompts in the Risk Factors group demonstrated the best responses, while those in the Pain/Functional Outcome group demonstrated the lowest. The overall IRR was found to be 0.33 (poor reliability), with the highest IRR for relevance (0.43) and the lowest for evidence-based (0.28). ConclusionsChatGPT can answer questions regarding well-established clinical guidelines in total knee arthroplasty with above-average accuracy but demonstrates variable reliability. This investigation is the first step in understanding large language model artificial intelligence like ChatGPT and how well they perform in the field of arthroplasty.

Precise single column resection and reconstruction with femoral head plus total hip replacement for primary malignant peri-acetabulum tumors

To evaluate whether single acetabular column can be reserved and the effect of reconstruction with femoral head plus total hip replacement (THR) for primary malignant peri-acetabulum tumors. From 2007 to 2015, nineteen patients with primary malignant peri-acetabulum tumors were enrolled. All cases underwent single column resection with clear surgical margins. Ten of the 19 tumor’s resections were assisted by computer navigation. Femoral heads were applied to reconstruct anterior or posterior column defects; THR was used for joint reconstruction. The surgical safety, oncologic outcome and prosthesis survivorship and function were evaluated by regular follow-up. The average follow-up period was 65.9 months. Surgical margins contained wide resection in 12 cases and marginal resection in 7 cases. One patient with Ewing's sarcoma died 14 months postoperative due to lung metastasis. One case with chondrosarcoma had recurrence. One prosthesis was removed due to infection. The average MusculoSkeletal Tumor Society (MSTS) function score was 83.7%. Due to the relative small number of cases, there was no significant difference in the recurrence rate and prosthesis failure rate between the navigation group and non-navigation group. Single column resection and reconstruction with femoral head autograft plus THR is an effective, safe method with less complication rate and better functional outcome for patients with peri-acetabular tumors.

Accelerated diffusion-weighted magnetic resonance imaging at 7 T: Joint reconstruction for shift-encoded navigator-based interleaved echo planar imaging (JETS-NAViEPI)

Abstract The pursuit of high spatial-angular-temporal resolution for in vivo diffusion-weighted magnetic resonance imaging (DW-MRI) at ultra-high field strength (7 T and above) is important in understanding brain microstructure and function. Such pursuit, however, faces several technical challenges. First, increased off-resonance and shorter T2 relaxation require faster echo train readouts. Second, existing high-resolution DW-MRI techniques usually employ in-plane fully-sampled multi-shot EPI, which not only prolongs the scan time but also induces a high specific absorption rate (SAR) at 7 T. To address these challenges, we develop in this work navigator-based interleaved EPI (NAViEPI) which enforces the same effective echo spacing (ESP) between the imaging and the navigator echo. First, NAViEPI renders no distortion mismatch between the two echoes, and thus simplifies shot-to-shot phase variation correction. Second, NAViEPI allows for a large number of shots (e.g., &amp;gt;4) with undersampled iEPI acquisition, thereby rendering clinically-feasible high-resolution sub-milliemeter protocols. To retain signal-to-noise ratio (SNR) and to reduce undersampling artifacts, we developed a ky-shift encoding among diffusion encodings to explore complementary k- q-space sampling. Moreover, we developed a novel joint reconstruction with overlapping locally low-rank regularization generalized to the multi-band multi-shot acquisition at 7 T (dubbed JETS-NAViEPI). Our method was demonstrated, with experimental results covering 1 mm isotropic resolution multi b-value DWI and sub-millimeter in-plane resolution fast TRACE acquisition.

Coracoclavicular and acromioclavicular ligament reconstruction with a double-bundle semitendinosus autograft and cortical buttons for chronic acromioclavicular joint dislocations: clinical and imaging outcomes

BackgroundThere are few clinical and radiographic studies of coracoclavicular (CC) ligament reconstruction in chronic acromioclavicular (AC) joint dislocation. Additionally, reported AC joint reduction rates vary. HypothesisArthroscopically assisted double-bundle semitendinosus tendon autografts with CC and AC ligament reconstruction for AC joint reconstruction provide AC joint stability and improved function at the final visit. MethodsIn this retrospective study of prospectively collected data, 21 patients surgically treated for chronic AC joint dislocation (Rockwood III–V) were assessed clinically and radiographically preoperatively, and at day 1, 3 months, 12 months, and at a final visit (> 24 months) postoperatively. Clinical assessments included Constant and ASES scores. The CC vertical distance (CCD) on the affected and unaffected sides [CCD ratio (%)] on the anterosuperior view were measured. AC joint vertical reduction loss was defined as an increase in the CCD ratio of > 25%. Horizontal AC joint instability was evaluated on axillary views. Pearsons’ correlation coefficients were generated to examine the relationships among postoperative clinical scores, CCD ratio, interval from injury to surgery, and age at the time of surgery. ResultsTwenty-one shoulders in 21 patients (mean age, 40.0 years at the time of surgery; 16 men, 5 women) were evaluated with a mean 31.7-month follow-up period. The mean Constant scores, ASES scores, and CCD ratios significantly improved from preoperatively to the final visit [57.4 ± 10.1, 49.1 ± 12.1, 101.6 ± 64.1 preoperatively; 89.6 ± 5.3, 96.5 ± 4.2, 9.9 ± 34.5 at the final visit, respectively (P < 0.001 for all)]. Vertical AC and horizontal AC joint instability were observed in four shoulders (19.0%) and in one shoulder (4.8%), respectively. However, there was no significant correlation between the increase in CCD and clinical scores at the final visit (Constant score; r = 0.179, P = .438: ASES score; r = -0.260, P = .256) or the interval from injury to surgery (r = 0.099, P = .669) or age at the time of surgery (r = 0.019, P = .935). No clinical complications were associated with clinical symptoms. ConclusionsPatients who underwent the index procedure achieved significant improvement in shoulder function without complications related clinical symptom after a mean follow-up interval of 31.7 months. In contrast, the rates of total ACJ instability in the vertical and horizontal planes were unsatisfactory but compatible with those in previous studies.

RPCA-AENet: Clutter Suppression and Simultaneous Stationary Scene and Moving Targets Imaging in the Presence of Motion Errors.

Clutter suppression and ground moving target imaging in synthetic aperture radar (SAR) system have been receiving increasing attention for both civilian and military applications. The problem of clutter suppression and ground moving target imaging in practical applications is much more challenging due to the motion error of the radar platform. In this article, we focus on the problems of clutter suppression and simultaneous stationary and moving target imaging in the presence of motion errors. Specifically, we propose a robust principal component analysis autoencoder network (RPCA-AENet) in a single-channel SAR system. In RPCA-AENet, the encoder transforms the SAR echo into imaging results of stationary scene and ground moving targets, and the decoder regenerates the SAR echo using the obtained imaging results. The encoder is designed by the unfolded robust principal component analysis (RPCA), while the decoder is formulated into two dense layers and one additional layer. Joint reconstruction loss, entropy loss, and measurement distance loss are utilized to guide the training of the RPCA-AENet. Notably, the algorithm operates in a totally self-supervised form and requires no other labeled SAR data. The methodology was tested on numerical SAR data. These tests show that the proposed architecture outperforms other state-of-the-art methods.

Management of Bone Loss in Revision Total Knee Arthroplasty: An International Consensus Symposium.

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research.

Acromioclavicular joint dislocation: a novel surgical technique for acromioclavicular joint reduction with coracoclavicular ligament reconstruction and anatomic conoid ligament reconstruction

The management of acromioclavicular (AC) joint dislocations remains controversial. Many implant designs offer a single pole of coracoclavicular (CC) fixation. Furthermore, previously described techniques for reconstruction of the CC ligaments are limited in their ability to replicate the obliquity of the native CC ligaments. We describe a novel technique for AC joint reduction and reconstruction using posterior to anterior obliquity of the medial clavicular tunnel with a dual-limb suture fixation method and allograft augmentation.

Megaprosthetic replacement in complex distal humerus fractures in elderly patients: a case series

BackgroundManaging distal humeral fractures can be challenging for orthopedic surgeons. There are several treatment options for managing this type of fracture, and the treatment method for these fractures should be based on patient-related factors. In elderly patients with osteoporotic bone and severe comminution of the fracture, adequate fixation can be a major challenge for surgeons. The use of megaprosthesis has been recently proposed in traumatology as an alternative to osteosynthesis or conventional prosthesis for the management of comminuted articular fractures in elderly patients with poor bone stock.MethodsA consecutive case series of 5 patients who underwent reconstruction of the elbow joint with a trabecular hinged modular elbow megaprosthesis was reviewed retrospectively. All patients included had AO/OTA 13C2 and 13C3 fractures with metaphyseal extension and considerable bone loss of the distal humerus. The primary outcome was the evaluation of functional and clinical outcomes with the MEPS score in comminuted distal humerus fractures with metaphyseal extension and poor bone stock in elderly patients treated with elbow megaprosthesis. The secondary outcome was assessing the treatment-related complication rate of this technique in non-oncological fields.ResultsFive patients were included in the study with a mean age of 82.66 ± 7.72 years at surgery. The mean MEPS value was 63 ± 24.2 at 1 month, 81 ± 23.53 at 3 months, 83 ± 24.2 at 6 months, and 84 ± 24.57 at 12 months. No intraoperative complications were recorded in our series. Of 5 patients, four patients had excellent clinical and functional outcomes. We did not encounter wound dehiscence, prosthetic joint infection, aseptic loosening, or periprosthetic fractures.ConclusionsThe indication for this type of treatment must be selected and narrowed down, as it is a salvage procedure, and any failure would cause even more complex situations. Short operating times and early mobilization of the elbow are the advantages of this technique.

Joint multi-contrast CT for edge illumination X-ray phase contrast imaging using split Barzilai-Borwein steps.

Edge illumination (EI) is an X-ray imaging technique that, in addition to conventional absorption contrast, provides refraction and scatter contrast. It relies on an absorption mask in front of the sample that splits the X-ray beam into beamlets, which hits a second absorption mask positioned in front of the detector. The sample mask is then shifted in multiple steps with respect to the detector mask, thereby measuring an illumination curve per detector element. The width, position, and area of this curve estimated with and without the sample in the beam is then compared, which ultimately provides absorption, refraction, and scatter contrast for each detector pixel. From the obtained contrast sinograms, three contrast tomograms can be computed. In summary, conventional EI relies on a two-stage process comprised of a computational and time intensive contrast retrieval process, followed by tomographic reconstruction. In this work, a novel joint reconstruction method is proposed, which utilizes a combined forward model to reconstruct the three contrasts simultaneously, without the need for an intermediate contrast retrieval step. Compared to the state-of-the-art, this approach reduces reconstruction times, as the retrieval step is skipped and allows a much more flexible acquisition scheme, as there is no need to sample a full illumination curve at each projection angle. The proposed method is shown to improve reconstruction quality on subsampled datasets, enabling the reconstruction of three contrasts from single-shot datasets.

Compliant Intramedullary Stems for Joint Reconstruction.

The longevity of current joint replacements is limited by aseptic loosening, which is the primary cause of non-infectious failure for hip, knee, and ankle arthroplasty. Aseptic loosening is typically caused either by osteolysis from particulate wear, or by high shear stresses at the bone-implant interface from over-constraint. Our objective was to demonstrate feasibility of a compliant intramedullary stem that eliminates over-constraint without generating particulate wear. The compliant stem is built around a compliant mechanism that permits rotation about a single axis. We first established several models to understand the relationship between mechanism geometry and implant performance under a given angular displacement and compressive load. We then used a neural network to identify a design space of geometries that would support an expected 100-year fatigue life inside the body. We additively manufactured one representative mechanism for each of three anatomic locations, and evaluated these prototypes on a KR-210 robot. The neural network predicts maximum stress and torsional stiffness with 2.69% and 4.08% error respectively, relative to finite element analysis data. We identified feasible design spaces for all three of the anatomic locations. Simulated peak stresses for the three stem prototypes were below the fatigue limit. Benchtop performance of all three prototypes was within design specifications. Our results demonstrate the feasibility of designing patient- and joint-specific compliant stems that address the root causes of aseptic loosening. Guided by these results, we expect the use of compliant intramedullary stems in joint reconstruction technology to increase implant lifetime.

Joint Reconstruction and Multiple Attenuation Using One-Step Randomized-Order Damped Rank Reduction Method

Joint Reconstruction and Multiple Attenuation Using One-Step Randomized-Order Damped Rank Reduction Method