Subchondral Collapse Research Articles

Unicompartmental Knee Arthroplasty Versus Opening-Wedge High Tibial Osteotomy for Spontaneous Osteonecrosis of the Knee: A Retrospective Cohort Study.

Unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) are treatment options for patients with medial spontaneous osteonecrosis of the knee (SONK). To compare the clinical outcomes after UKA and HTO in patients with SONK. Cohort study; Level of evidence, 3. This retrospective study included 42 patients who had undergone Oxford UKA and 40 patients who had undergone opening-wedge HTO between 2014 and 2020. All patients were diagnosed with isolated medial SONK without subchondral collapse of the femoral condyle and tibial plateau. The patients were preoperatively and postoperatively evaluated using the Lysholm knee scoring system, the Western Ontario and McMaster Universities Osteoarthritis Index, and a numeric rating scale assessing patient satisfaction. Patients in the UKA group were significantly older than those in the HTO group (median age, 71.5 years [IQR, 68.0-76.5 years] vs 65.0 years [IQR, 60.0-70.0 years], respectively; P < .001). The median follow-up time was 3.78 years (IQR, 2.45-4.53 years) for the UKA group and 3.87 years (IQR, 2.90-5.60 years) for the HTO group. Significant improvements in functional scores were observed in both the UKA and HTO groups (P < .001 for all), with no significant between-group differences in scores at the final follow-up (≥2 years after surgery). The satisfaction rate was similar (80.95% for UKA and 75.0% for HTO). According to the study results, significant improvements in clinical outcomes were seen after opening-wedge HTO with microfracture for a younger group of patients with SONK without subchondral collapse, while Oxford UKA had a comparable effect on an older group of patients. Both UKA and HTO were found to be viable surgical approaches for SONK at short- to midterm follow-up.

Zoledronate alleviates subchondral bone collapse and articular cartilage degeneration in a rat model of rotator cuff tear arthropathy

To evaluate the humeral head bone volume of patients with cuff tear arthropathy (CTA) and examine the therapeutic effect of zoledronate in a rat modified model of CTA (mCTA). The bone mass in patients with CTA was measured using Hounsfield units from CT images. The mCTA was induced by transecting the rotator cuff, biceps brachii tendon, and superior half of the joint capsule in adult rat shoulders. A single subcutaneous injection of zoledronate was followed by bone histomorphometry and immunohistochemistry of the humeral head, as well as the Murine Shoulder Arthritis Score (MSAS) assessment. The humeral head bone volume was decreased in patients with CTA. In the mCTA model, M1 macrophages were increased in the synovium and were decreased by zoledronate treatment. The increased expressions of TNF-α, IL-1β and IL-6 in mCTA synovium and articular cartilage were suppressed in the zoledronate-treated mCTA group. The expression of catabolic enzymes in the articular cartilage and MSAS showed similar results. The zoledronate-treated mCTA group showed a decreased subchondral bone collapse with a decreased RANKL/OPG expression ratio and a suppressed number of osteoclasts compared with the control mCTA group. The enhanced expressions of HMGB1 and S100A9 in the mCTA shoulders were eliminated in the zoledronate-treated mCTA group. The humeral head subchondral bone was decreased in patients with CTA. In the mCTA model, the collapse and osteoarthritic changes were prevented by zoledronate administration. Zoledronate seemed to suppress the number of M1 macrophages in the synovium and osteoclasts in the subchondral bone.

Single Injection AAV2-FGF18 Gene Therapy Reduces Cartilage Loss and Subchondral Bone Damage in a Mechanically Induced Model of Osteoarthritis.

Osteoarthritis (OA) is a highly debilitating, degenerative pathology of cartilaginous joints affecting over 500 million people worldwide. The global economic burden of OA is estimated at $260-519 billion and growing, driven by aging global population and increasing rates of obesity. To date, only the multi-injection chondroanabolic treatment regimen of Fibroblast Growth Factor 18 (FGF18) has demonstrated clinically meaningful disease-modifying efficacy in placebo-controlled human trials. Our work focuses on the development of a novel single injection disease-modifying gene therapy, based on FGF18's chondroanabolic activity. OA was induced in Sprague-Dawley rats using destabilization of the medial meniscus (DMM) (3 weeks), followed by intra-articular treatment with 3 dose levels of AAV2-FGF18, rh- FGF18 protein, and PBS. Durability, redosability, and biodistribution were measured by quantifying nLuc reporter bioluminescence. Transcriptomic analysis was performed by RNA-seq on cultured human chondrocytes and rat knee joints. Morphological analysis was performed on knee joints stained with Safranin O/Fast Green and anti-PRG antibody. Dose-dependent reductions in cartilage defect size were observed in the AAV2-FGF18- treated joints relative to the vehicle control. Total defect width was reduced by up to 76% and cartilage thickness in the thinnest zone was increased by up to 106%. Morphologically, the vehicle- treated joints exhibited pronounced degeneration, ranging from severe cartilage erosion and bone void formation, to subchondral bone remodeling and near-complete subchondral bone collapse. In contrast, AAV2-FGF18-treated joints appeared more anatomically normal, with only regional glycosaminoglycan loss and marginal cartilage erosion. While effective at reducing cartilage lesions, treatment with rhFGF18 injections resulted in significant joint swelling (19% increase in diameter), as well as a decrease in PRG4 staining uniformity and intensity. In contrast to early-timepoint in vitro RNA-seq analysis, which showed a high degree of concordance between protein- and gene therapy-treated chondrocytes, in vivo transcriptomic analysis, revealed few gene expression changes following protein treatment. On the other hand, the gene therapy treatment exhibited a high degree of durability and localization over the study period, upregulating several chondroanabolic genes while downregulating OA- and fibrocartilage-associated markers. FGF18 gene therapy treatment of OA joints can provide benefits to both cartilage and subchondral bone, with a high degree of localization and durability.

Management of Capitellar Osteochondritis Dissecans: A Critical Analysis Review.

» Osteochondritis dissecans of the capitellum is a localized compromise of bone that may lead to subchondral collapse with articular cartilage damage and loose body formation.» The etiology is multifactorial; proposed mechanisms include repetitive microtrauma, vascular insufficiency, and genetic predisposition.» Diagnosis is based on patient presentation, clinical examination, diagnostic imaging, and intraoperative findings.» Management is dependent on lesion characteristics, with stable lesions amenable to nonoperative treatment and unstable lesions managed with surgical intervention.» Adolescent athletes can expect a return to their preinjury level of activity or competition following indicated surgical intervention.

Three-Dimensional Imaging and Histopathological Features of Third Metacarpal/Tarsal Parasagittal Groove and Proximal Phalanx Sagittal Groove Fissures in Thoroughbred Horses.

Fissure in the third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove is a potential prodromal pathology of fracture; therefore, early identification and characterisation of fissures using non-invasive imaging could be of clinical value. Thirty-three equine cadaver limbs underwent standing cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, low-field magnetic resonance imaging (MRI), and macro/histo-pathological examination. Imaging diagnoses of fissures were compared to microscopic examination. Imaging features of fissures were described. Histopathological findings were scored and compared between locations with and without fissures on CT. Microscopic examination identified 114/291 locations with fissures. The diagnostic sensitivity and specificity were 88.5% and 61.3% for CBCT, 84.1% and 72.3% for FBCT, and 43.6% and 85.2% for MRI. Four types of imaging features of fissures were characterised on CT: (1) CBCT/FBCT hypoattenuating linear defects, (2) CBCT/FBCT striated hypoattenuated lines, (3) CBCT/FBCT subchondral irregularity, and (4) CBCT striated hypoattenuating lines and FBCT subchondral irregularity. Fissures on MRI appeared as subchondral bone hypo-/hyperintense defects. Microscopic scores of subchondral bone sclerosis, microcracks, and collapse were significantly higher in locations with CT-identified fissures. All imaging modalities were able to identify fissures. Fissures identified on CT were associated with histopathology of fatigue injuries.

SYSTEMATIC REVIEW AND META-ANALYSIS OF TREATMENT OUTCOMES FOR SECONDARY OSTEONECROSIS OF THE KNEE IN YOUNG ADULTS

AbstractIntroductionSecondary osteonecrosis of the knee affects young population and causes bilateral extensive lesions. Arthroplasty is the last resort in younger population and joint preserving options questionable in pathological bone. Conservative measures have shown failure in multiple studies and hence no gold standard treatment advocated. We aimed at identifying and analysing various treatment options for secondary osteonecrosis with respect to the outcomes and studying features of symptomatic secondary osteonecrosis with regards to demographic pattern, radiological features and causative factors.MethodsA systematic review of literature was performed in accordance with the Cochrane handbook for systematic reviews and reported according to the PRISMA guidelines.ResultsSix studies which included a total of 192 patients with data on 240 knee joints were included in the final review. Follow up period ranged from 1 year to 16 years. The mean age of the patients was 34.7. 3 studies were on arthroplasty and 3 on joint preserving interventions. Majority of patients were in Stage 2 or Stage 4 of osteonecrosis. Steroid induced osteonecrosis was the majority followed by SLE and sickle cell disease. The pooled analysis showed an improvement of pre-operative knee score from 50.47 to 89.21 post-operatively. The pooled effect size for failure rate was 8.7% in joint preserving interventions and 9.2% in joint replacement group.ConclusionJoint preserving techniques with bone marrow aspirate infiltration showed promising functional outcome and to a certain extent reversal of the pathological process. For advanced stages with subchondral collapse cemented arthroplasty showed satisfactory functional outcomes.

Development of a novel animal model of rotator cuff tear arthropathy replicating clinical features of progressive osteoarthritis with subchondral bone collapse

ObjectiveTo establish an animal model of modified cuff tear arthropathy (mCTA) in order to better replicate the pathophysiology associated with rotator cuff tear-induced humeral head collapse. DesignmCTA was induced by transection of the rotator cuff, the long head of the biceps brachii (LHB), and superior half of the joint capsule in the right shoulder of 12-week-old rats; the left shoulder underwent sham surgery. The severity of CTA was quantitated using the Murine Shoulder Arthritis Score (MSAS). The trabecular bone of the humeral head and metaphysis was analyzed using bone histomorphometry. The expression of proinflammatory cytokines and catabolic enzymes was evaluated immunohistochemically. ResultsIn the mCTA model, the MSAS increased starting from 2 weeks after induction, and there was notable subchondral bone collapse with fibrous cells at 4 weeks. The mCTA cartilage exhibited positive staining for TNF-α, IL-1β/6, MMP-3/13, and ADAMTS5. The trabecular bone volume was reduced not only in the subchondral bone but also in the metaphysis of the humeri, and bone resorption was enhanced in these areas. In the collapsed subchondral bone, both bone formation and resorption were increased. The fibrous cells showed expression of TNF-α, IL-6, and MMP-13, along with specific markers of mesenchymal stem cells. Furthermore, the fibrous cells showed osteoblastic characteristics (RUNX2-positive) and expressed RANKL. ConclusionsThe LHB and the capsuloligamentous complex are critical stabilizers of the glenohumeral joint, serving to prevent the advancement of CTA following massive rotator cuff tears. Fibrous cells appear to play a role in the humeral head bone resorption.

Poster 260: Influence of Donor Demographics on Graft Survival following Knee Osteochondral Allograft Transplantation

Objectives: To evaluate whether donor and recipient factors such as donor age, sex mismatch, and time from death to graft implantation affect graft survival following knee osteochondral allograft (OCA) transplantation. Methods: Patients undergoing OCA transplantation in the knee from 2003-2016 were prospectively followed. Inclusion criteria consisted of primary OCA transplantation and minimum 2-year follow-up. Patient and donor demographic data were collected. Patients were evaluated for failure, defined as (1) subchondral collapse of the OCA as confirmed on postoperative MRI scans, or via second-look arthroscopy in the setting of persistent symptoms, (2) removal or revision of the primary OCA, or (3) conversion to arthroplasty. Multivariate cox proportional hazards modelling was utilized to evaluate associations between demographic variables and graft failure. Results: A total of 220 patients undergoing OCA transplantation met inclusion criteria and were followed for a mean of 5.9 ± 2.8 years (range: 2.0 – 16.3, Table 1). The most common concomitant procedure was meniscal allograft transplantation (Table 2). A mismatch in donor and recipient sex was present for significantly more female patients (65%) than male patients (10%, p &lt; 0.001). The mean days from donor death until implantation was 24.1 days (range: 15 – 28). Thirty-nine patients (18%) met criteria for graft failure at a mean of 4.3 ± 3.2 years (Table 3). Log-rank testing did not determine a difference in survivability between those with a donor-recipient sex mismatch for female or male patients (P = .130 and .831, respectively). Upon multivariate cox regression, no association existed between donor-recipient sex mismatch or time from donor death to implantation with graft survival. Of note, increased donor age was associated with failure for female patients (P = .020) and trended towards significance in males (P = .166). Conclusions: OCA graft survival appears to be most strongly influenced by donor age. In contrast to previous historic data, no substantial survival difference was noted for sex mismatched donors and recipients. These data can help inform graft selection and outcome optimization following OCA. [Table: see text][Table: see text][Table: see text]

Arthroscopic Transtibial Repair of Acute Traumatic Posterior Medial Meniscus Root Tear

Background: The posteromedial meniscal root is a critical structure in maintaining balanced tibiofemoral contact stresses and joint stability. Studies have shown that posterior root tears are biomechanically equivalent to total meniscectomy and can lead to the rapid development of osteoarthritis. Our presentation focuses on the less common, acute, traumatic posteromedial meniscal root avulsion, although our technique is also applicable to the more common degenerative posteromedial meniscal root tears. Indications: Surgical indications include acute tears, as well as chronic or degenerative tears in patients without advanced osteoarthritis. Absolute surgical contraindications include subchondral bone collapse, substantial concurrent meniscal pathology, malalignment of &gt;5°, and advanced knee osteoarthritis. Technique Description: Once the tear is identified, the bone at the root insertion is prepared with a meniscal rasp. Two looped sutures are passed through the meniscal root in a cinch-type fashion using a knee scorpion. A tunnel is drilled at the root insertion using a specialized meniscal root repair guide. Approximately, 10 mm of bone are drilled in a retrograde fashion with a flip cutter deployed to 7 mm to decorticate the bone and enhance healing. The drill is then removed and a rubber tube with a retrieval suture is advanced through the drill guide into the joint. The loop suture is retrieved through the anteromedial portal and the repair sutures are passed through the retrieval loop. Under arthroscopic visualization, the root is then reduced to its anatomic insertion and the sutures secured to the tibia using a knotless suture anchor placed 1 cm distal to the transtibial tunnel. Results: Several recent studies have shown that meniscal root repair decreases rapid knee degeneration as gauged by meniscal extrusion, progression of Kellgren-Lawrence grade and rate of conversion to total knee arthroplasty (TKA). Discussion/Conclusion: Posteromedial meniscal root tears are increasingly being recognized as a distinct meniscal pathology that can lead to rapid arthritis if left unrepaired. Arthroscopic repair techniques continue to improve allowing orthopedic surgeons to more readily address this significant, but treatable pathology. 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.

Avascular necrosis of bone tissue: Definition, epidemiology, types, risk factors, pathogenesis of the disease. Analytical review of the literature

Avascular necrosis (AN) of bone tissue is a common pathology that affects people of any age, more often young and able-bodied. The disease leads to rapid destruction of the subchondral bone and collapse, followed by the development of secondary osteoarthritis (OA) of the affected joint.The purpose of this review article is to present the accumulated knowledge about the prevalence of AN, the most commonly affected joints, risk factors and pathogenesis of the disease. Since most of the world’s literature sources present knowledge about the individual parts and facts that make up the pathogenesis of AN, this article analyzes all known paths of the development of the disease from the onset of ischemia to collapse and the development of secondary OA and the pathogenesis is presented in chronological order. Based on the results of the article, a definition of the term AN was proposed, and the stages of the disease within the pathogenesis, the most promising for conservative methods of treatment, were identified.

Computer-Assisted and Hip Arthroscopy for Avascular Necrosis of the Femoral Head With Femoroacetabular Impingement

Avascular necrosis of the femoral head with femoroacetabular impingement is a disabling disease. Without early treatment and intervention, its further development will even lead to hip osteoarthritis and hip dysfunction. This technical note aims to introduce a computer-assisted precise core decompression of the femoral head, followed by injection of platelet-rich plasma and bone marrow aspirate concentrate. Then, the autologous ipsilateral iliac bone is transplanted to the core decompression area. Thereafter, under hip arthroscopy, the injured glenoid lip of the hip joint is repaired, and the cam deformity of the femoral head/neck junction is polished and formed. The advantages of this technique include accurately locating the core decompression area, combined with autologous cells and bone transplantation, being able to delay the process of avascular necrosis of the femoral head, and evaluating articular cartilage injury, subchondral collapse, and guidance during reaming and curettage.

Relationship between the degree of subchondral collapse and articular surface irregularities in osteonecrosis of the femoral head.

Articular surface irregularities are often observed in collapsed femoral heads with osteonecrosis, while the effects of the degree of collapse on the articular surface are poorly understood. We first macroscopically assessed the articular surface irregularities on 2-mm coronal slices obtained using high-resolution microcomputed tomography of 76 surgically resected femoral heads with osteonecrosis. These irregularities were observed in 68/76 femoral heads, mainly at the lateral boundary of the necrotic region. The mean degree of collapse was significantly larger for femoral heads with articular surface irregularities than for those without (p < 0.0001). Receiver operating characteristic analysis showed that the cutoff value for the degree of collapse in femoral heads with articular surface irregularities at the lateral boundary was 1.1 mm. Next, for femoral heads with <3-mm collapse (n = 28), articular surface irregularities were quantitatively assessed based on the number of automatically counted negative curvature points. Quantitative evaluation showed that the degree of collapse was positively correlated with the presence of articular surface irregularities (r = 0.95, p < 0.0001). Histological examination of articular cartilage above the necrotic region (n = 8) revealed cell necrosis in the calcified layer and abnormal cellular arrangement in the deep and middle layers. In conclusion, articular surface irregularities of the necrotic femoral head depended on the degree of collapse, and articular cartilage was already altered even in the absence of macroscopically determined gross irregularities.

Spontaneous Osteonecrosis of the Knee: State of the Art.

Osteonecrosis is a terrible condition that can cause advanced arthritis in a number of joints, including the knee. The three types of osteonecrosis that can affect the knee are secondary, post-arthroscopic, and spontaneous osteonecrosis of the knee (SPONK). Regardless of osteonecrosis classification, treatment for this condition seeks to prevent further development or postpone the onset of knee end-stage arthritis. Joint arthroplasty is the best course of action whenever there is significant joint surface collapse or there are signs of degenerative arthritis. The non-operative options for treatment at the moment include observation, nonsteroidal anti-inflammatory medications (NSAIDs), protective weight bearing, and analgesia if needed. Depending on the severity and type of the condition, operational procedures may include unilateral knee arthroplasty (UKA), total knee arthroplasty (TKA), or joint preservation surgery. Joint preservation techniques, such as arthroscopy, core decompression, osteochondral autograft, and bone grafting, are frequently used in precollapse and some postcollapse lesions, when the articular cartilage is typically unaffected and only the underlying subchondral bone is affected. In contrast, operations that try to save the joint following significant subchondral collapse are rarely successful and joint replacement is required to ease discomfort. This article's goal is to summarise the most recent research on evaluations, clinical examinations, imaging and various therapeutic strategies for osteonecrosis of the knee, including lesion surveillance, medicines, joint preservation methods, and total joint arthroplasty.

The influence of bone marrow edema for the assessment of the boundaries of necrotic lesions in patients with osteonecrosis of the femoral head

This study aimed to investigate the influence of bone marrow edema (BME) for the assessment of the boundaries of necrotic lesions using unenhanced and contrast-enhanced (CE) magnetic resonance (MR) images in patients with osteonecrosis of the femoral head (ONFH). We retrospectively reviewed 72 consecutive hips in 55 patients of ONFH that were Association Research Circulation Osseous (ARCO) stage III or higher and underwent both unenhanced and contrast-enhanced MR imaging between January 2005 and February 2016. The degree of extension of BMEs, and the boundaries of the necrotic lesions were compared using unenhanced and CE MR images on both mid coronal and mid oblique-axial slices. Forty-two percent of the coronal T1 images, 40% of the coronal fat-saturated T2 images, and 48% of the oblique-axial T1 images showed differences in the boundaries of necrotic lesion, by comparison with those of CET1-weighted MR images. The boundaries of necrotic lesions were clearly detected in all hips on CE coronal slices and 97% of all hips on CE oblique-axial slices. The BME grade in the difference group was significantly higher than in the non-difference group on the coronal plane (P = 0.0058). There were significant differences between the BME grade and duration from the onset of hip pain to MR imaging examination. Multivariate analyses revealed that the duration from the onset to MR imaging examination in both coronal (P = 0.0008) and oblique-axial slices (P = 0.0143) were independently associated with differences in the boundary of necrotic lesion between T1 and CET1-weighted MR images. Our findings suggest that unenhanced MR image may be insufficient for a precise assessment of the boundaries of the necrotic lesions for ONFH cases in the early phase of subchondral collapse due to the diffuse BME.

Pathophysiology of Avascular Necrosis.

Avascular necrosis is a complicated, multifactorial disease with potentially devastating consequences. Although the underlying root cause is a lack of appropriate vascular perfusion to affected bone, there are often varying patient-specific, anatomic-specific, and injury-specific predispositions. These factors generally fall into 3 categories: direct vascular disruption, intravascular obliteration, or extravascular compression. The initial stages of disease can be insidiously symptomatic because edematous bone marrow progresses to subchondral collapse and subsequent degenerative arthritis. Although much of the current literature focuses on the femoral head, other common areas of occurrence include the proximal humerus, knee, and the carpus. The low-incidence rate of carpal avascular necrosis poses a challenge in establishing adequately powered, control-based validated treatment options, and therefore, optimal surgical management remains a continued debate among hand surgeons. Appreciation for expectant fracture healing physiology may help guide future investigation into carpal-specific causes of avascular necrosis.

Arthroscopic Core Decompression for Avascular Necrosis of the Femoral Head Using Multiple Small-Diameter Tunnels

Avascular necrosis of the femoral head (AVNFH) is a debilitating disease that requires early intervention to prevent subchondral collapse and irreversible damage leading to premature hip replacement. Patients presenting with AVNFH can have concomitant intra-articular pathology, including femoroacetabular impingement (FAI), that contributes to their hip pain and dysfunction. It is important to restore the native hip anatomy in addition to providing revascularization of necrotic areas to reduce pain, improve function, and maximize efforts to preserve the joint. The purpose of this Technical Note is to describe our preferred arthroscopic approach to core decompression through the femoral neck in combination with femoral osteoplasty to address AVNFH and FAI in a single-staged and minimally invasive procedure.

3D Printed Total Talus Replacement after Free Vascularized Medial Femoral Condyle Osteocutaneous Flap for Avascular Necrosis of the Talus Leads to Poor Clinical Outcomes

Category: Hindfoot Introduction/Purpose: Talar avascular necrosis (AVN) is a difficult pathology to diagnose and manage. Traditional treatment options include both joint sparing procedures (vascularized bone graft, core decompression, intraosseous stem cell injection) and joint sacrificing procedures (arthrodesis or arthroplasty). Three dimensional (3D) printed total talus replacement (TTR) has recently gained more popularity as an intervention to salvage joint motion in patients with talus pathology. Although vascularized bone grafting can treat localized talar AVN, failure of this procedure to improve talar vascularity and prevent further subchondral collapse may require revision surgery. This is the first study to compare outcomes of patients with talar AVN who underwent primary 3D printed TTR and patients who underwent a secondary TTR subsequent to failure of a free vascularized medial femoral condyle (MFC) flap. Methods: This case series analyzed the outcomes of two patients who underwent a secondary 3D printed TTR subsequent to failure of the index revascularization procedure using an MFC flap in 2016. These patients were compared to a cohort of patients who underwent a primary 3D printed TTR to treat talar AVN between 2016 and 2019. Preoperative and postoperative assessment included ankle range of motion, foot and ankle outcome score (FAOS), visual analogue scale (VAS) pain scores, and radiographic imaging. A minimum 12-month follow-up period was reported for patients. Results: Within the group that underwent a secondary TTR after a failed revascularization, both patients had a mean followup of 23.5 months. The 25 patients in the comparison group who all underwent a primary 3D printed TTR had an mean follow-up period of 22.1 (range:12-43) months. All patients in the study experienced improved VAS pain scores and ankle dorsiflexion post- operatively. In the secondary 3D printed TTR group, both patients demonstrated reduced plantarflexion of 20 degrees and ankle motion of 15 degrees relative to the comparison group which showed a minimal increase in both. When analyzing FAOS functional outcome score subscales, patient two demonstrated improvement in pain from 44 to 46, symptoms from 29 to 46, and activities of daily living from 47 to 76. Patient one experienced a decrease in sports and recreation from 15 to 5 and quality of life from 38 to 31. Conclusion: This case series demonstrated poor functional outcomes of two patients who underwent 3D printed TTR after talar revascularization with MFC grafts when compared to the cohort of patients who solely underwent a primary 3D printed TTR for talar AVN. Further investigation is warranted to determine which patients may benefit from a revascularization procedure or a primary 3D printed TTR.

Early Outcomes of Combined Total Ankle Total Talus Replacement Using a 3D-Printed Talus Component With Hindfoot Arthrodesis.

Late-stage talar avascular necrosis (AVN) results in devascularization of the talus with osteonecrosis and subchondral collapse. A combined total ankle and total talus replacement (TATTR) with hindfoot arthrodesis may be utilized for end-stage talar AVN with tibiotalar and hindfoot joint arthritis. The purpose of this study is to evaluate the short-term outcomes of combined TATTR with hindfoot arthrodesis. Patients who underwent a combined TATTR or TTR with a hindfoot arthrodesis (subtalar with or without talonavicular arthrodesis) from 2016 to 2020 were retrospectively reviewed. Patient demographics, comorbidities, and surgical data were collected. Outcomes included the Visual Analog Scale (VAS) scores, range of motion, radiographic parameters, union rates, and complications. A total of 18 patients were reviewed. Nine patients were included with an average of 19.4 months follow-up. Significant postoperative improvements were observed in VAS scores (P < .001), ankle plantarflexion (P = .04), talocalcaneal height (P = .03), and tibiotalar alignment (P = .02). All patients achieved a successful union of their subtalar and talonavicular joints arthrodesis. There was one reoperation for a persistent varus ankle deformity. This is the first study to evaluate the clinical outcomes, radiographic outcomes, and union rate in combined TATTR with hindfoot arthrodesis. The early results demonstrated significant clinical improvement with 100% hindfoot union rate and no prosthetic failure.Level of Evidence: IV.

Current Radiological Aspects of Subchondral Insufficiency Fracture of the Knee

Subchondral stress insufficiency fracture of the knee is a new type of fracture that occurs in people of the older age group (from 50–55 years old) when exposed to a normal load on weakened bone trabeculae. In Russian sources, there is few information about this type of fracture. This is primarily due to the fact that initially the world and domestic medical communities designated this type of pathology as “spontaneous osteonecrosis of the knee”. In recent years, this term has been revised abroad and replaced by a more suitable one – “subchondral insufficiency fracture”. The etiology of insufficiency fracture is based on many diseases and conditions that lead to bone tissue weakening (osteoporosis, collagenosis, rheumatoid arthritis, post-radiation changes in bones, etc.). The main method for diagnosing this type of fracture is magnetic resonance imaging, since it is able to detect a fracture at any stage (especially at an early one). According to modern concepts, the terms “osteonecrosis” and “subchondral insufficiency fracture” require completely different approaches to the treatment. In the presence of complications, a fracture of insufficiency of the knee joint condyles threatens with subchondral collapse and secondary osteoarthritis, which leads to disability of a patient. Given the relevance of this medical problem, the aim of the review is to show the current state of literature data on the issue.

Paper 42: Effects of Blood Type Mismatching on Functional Graft Survival after Osteochondral Allograft Transplantation

Objectives:To explore a factor that may contribute to potentially detrimental sub-rejection immune responses, we compared donor and recipient blood types following osteochondral allograft (OCA) transplants from a subset of patients in an IRB-approved dedicated lifelong registry to determine potential relationships for blood type mismatches with documented graft failures. The study was designed to test the hypothesis that OCA transplantation patients receiving blood type mismatched allografts would be more likely to require OCA revision or artificial arthroplasty surgery compared to those receiving donor-recipient matched allografts.Methods:A subset of patients was selected from those enrolled (n=414) in our center’s IRB-approved lifelong registry for OCA transplantation clinical outcomes. This subset included patients with complete donor and recipient ABO and Rh Factor data available such that there was a 2:1 ratio of successful versus failed outcomes for age-, BMI-, and joint-matched OCA transplant recipients for statistical analyses. Donor blood type information was obtained from the respective tissue banks. Recipient blood type information was obtained from electronic medical records. Patients who required OCA revision or artificial arthroplasty were defined as graft failures. Outcomes were assessed for all patients included in the blood type mismatching analyses. Osteochondral tissues that were resected from the knee, hip, and ankle of patients undergoing standard-of-care revision or arthroplasty surgeries, and that otherwise would be discarded, were recovered for histologic assessments. Subjective histologic assessments were performed by a pathologist who was blinded to patient demographics, blood typing information, outcomes data, and tissue source. When aggregates of lymphocytes and plasma cells were observed surrounding small blood vessels (consistent with an immune response), immunohistochemistry for CD3, CD8, and CD20 was performed to further characterize the lymphocytes (T cell marker, cytotoxic T lymphocytes, and B cell marker, respectively) for subjective assessment of relevant immune responses. Subjects were grouped by ABO blood type, Rh Factor, and both. Histologically evaluated failures were separated by immune response as positive or negative. Fisher’s exact tests were used for statistical analyses with a p-value of less than 0.05 set a priori to define statistical significance.Results:A total of 103 patients were included for analysis with 33 of these requiring OCA revision or artificial arthroplasty. Of the clinical failures, 18 had previously transplanted osteochondral allograft tissues recovered for histological assessment. Twelve (66%) of these recovered OCAs had aggregates of CD3+, CD8+, and CD20+ lymphocytes around small blood vessels in the bone marrow spaces and adipose/collagenous tissue of the previously transplanted allograft. The remaining resected OCAs (34%) did not show a similar pattern of T- and B-cell infiltrates around blood vessels. Other histologic abnormalities associated with failed OCAs included avascular necrosis, subchondral micro and macro fractures, subchondral collapse, and/or articular cartilage erosion or delamination. No statistically significant differences in proportions for success versus failure based on mismatches for ABO type, Rh Factor, or both were noted. Similarly, no statistically significant differences in proportions for positive versus negative immune responses based on mismatches for ABO type, Rh Factor, or both were noted.Conclusions:Donor-recipient mismatches for ABO blood type and/or Rh Factor were not associated with higher likelihood for patients to require OCA revision or artificial arthroplasty surgery. Similarly, donor-recipient mismatches for ABO blood type and/or Rh Factor were not associated with higher likelihood for positive immune responses in previously implanted OCA tissues recovered from patients who required revision or artificial arthroplasty surgeries. However, two-thirds of the tissues recovered from graft failure cases had T- and B-cell infiltrates, suggesting sub-rejection immune responses occur after OCA transplantation that should be further investigated to determine potential mechanistic relationships with graft failures. The results of the present study support current clinical practice for transplantation of fresh OCAs, which does not require HLA or blood type matching or immunosuppressive medication for recipients. However, histologic assessments suggest that sub-rejection immune responses may play a role in graft failures and should be further investigated.