< Back Biologic Tissues Overview of biologic tissues used in orthopaedics including graft types, sources, and applications. Biologic tissues play a crucial role in orthopaedic surgery by enhancing healing, providing structural support, and promoting integration. These include autografts, allografts, xenografts, and synthetic substitutes. Common biologic materials include bone grafts, cartilage scaffolds, tendons, and decellularized matrices. Sources can be patient-derived (autologous), donor-derived (allogeneic), or animal-derived (xenogeneic). Biologics may be used to fill defects, stimulate osteogenesis, or repair soft tissues. Tissue engineering and regenerative medicine approaches continue to expand the applications of biologic tissues in musculoskeletal care. Previous Next

< Back Anticoagulants Anticoagulants are medications that prevent clot formation. They are essential in orthopaedics for thromboprophylaxis, especially after surgery. Common Anticoagulants in Orthopaedics: Low Molecular Weight Heparin (LMWH): Enoxaparin Direct Oral Anticoagulants (DOACs): Rivaroxaban, Apixaban, Dabigatran Unfractionated Heparin Warfarin (less common due to monitoring needs) Indications in Orthopaedics: Prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) after joint replacement or major trauma Management of patients with a history of thromboembolism Atrial fibrillation with orthopaedic comorbidities Key Considerations: Start prophylaxis 6–12 hours after surgery (depending on bleeding risk) Continue for at least 10–14 days, sometimes up to 35 days in hip replacement Adjust dosing for renal function Monitor for signs of bleeding (wound hematoma, prolonged bleeding) Contraindications: Active bleeding Severe bleeding risk (e.g., recent CNS surgery) Coagulopathy Bridging and Reversal: Reversal agents: Protamine (heparin), Vitamin K (warfarin), Idarucizumab (dabigatran) Bridging required with LMWH in warfarin patients undergoing surgery Previous Next

< Back Contrast-Induced Nephropathy Contrast-induced nephropathy (CIN) is an acute decline in renal function after iodinated contrast exposure, especially in high-risk patients with pre-existing kidney disease or diabetes. Definition: Acute kidney injury (↑ serum creatinine ≥ 0.5 mg/dL or ≥ 25% from baseline) within 48–72 hours of contrast administration Usually reversible within 7–10 days Not due to other identifiable causes Pathophysiology: Renal vasoconstriction and medullary hypoxia Direct tubular epithelial cell toxicity Risk Factors: Chronic kidney disease (eGFR < 60 mL/min/1.73m²) Diabetes mellitus Dehydration Use of nephrotoxic drugs (NSAIDs, aminoglycosides) High contrast volume Advanced age Recent contrast exposure Prevention: IV hydration with isotonic saline (e.g., 0.9% NaCl) pre- and post-procedure Use of low- or iso-osmolar contrast agents Minimise contrast volume Withhold nephrotoxic medications temporarily (e.g., NSAIDs, metformin) Consider N-acetylcysteine (controversial benefit) Management: Supportive care Monitor renal function post-contrast Dialysis is rarely needed unless other causes of AKI exist Orthopaedic Relevance: Consider when ordering contrast-enhanced CT, angiography or preoperative vascular studies in high-risk patients Always document renal function status before contrast studies Previous Next

< Back Bone Circulation Vascular anatomy of bone and its role in development, healing, and pathology. Bone circulation is essential for skeletal development, remodeling, and repair. It involves three main vascular systems: Nutrient Artery System: Enters the diaphysis through the nutrient foramen. Supplies the inner two-thirds of cortical bone and the medullary cavity. Periosteal Vessels: Arise from surrounding soft tissues. Supply the outer third of cortical bone, especially active during healing and in children. Metaphyseal and Epiphyseal Vessels: Arise from adjacent arteries and supply the ends of long bones. These vessels are crucial for growth plate function and are susceptible to disruption in pediatric fractures. Clinical relevance: Avascular necrosis (AVN): Caused by disruption of bone blood supply, common in femoral head, scaphoid, and talus. Fracture healing: Adequate vascular supply is necessary for callus formation and union. Orthopaedic surgery: Careful preservation or restoration of blood flow is essential, especially in joint-preserving procedures and reconstructions. Previous Next

< Back Fracture Healing & Nonunion Principles of fracture healing and causes/types of nonunion. Fracture healing involves a sequence of inflammation, soft callus, hard callus, and remodeling. Nonunion types include hypertrophic, atrophic, and oligotrophic forms. Previous Next

< Back Bone Basic Science Basic principles of bone biology. Bone cells, remodeling, signalling, etc. Previous Next

< Back Tendons Structure, function, and healing of tendons in orthopaedics. Tendons are dense connective tissues that connect muscle to bone and transmit mechanical forces necessary for movement. They are composed mainly of collagen fibres, particularly type I collagen, and have limited vascularity, which affects their healing capacity. Common tendon injuries include tendinopathy and tears, often resulting from overuse or trauma. Tendon healing is a complex process involving inflammation, cell proliferation, and remodelling, but often results in scar formation and incomplete regeneration. Previous Next

< Back Drug-Induced Tendinopathy Certain medications, especially fluoroquinolones and corticosteroids, are associated with tendinopathy and tendon rupture, particularly in older and physically active patients. Key Offending Agents: Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) Tendon damage (especially Achilles tendon) Risk increased in elderly, renal failure, corticosteroid co-use Tendon symptoms may appear within hours to weeks Corticosteroids (systemic or local injection) Weakening of collagen matrix Risk increases with repeated injections Statins (less common) May cause tendinopathy or myopathy Aromatase inhibitors (e.g., in breast cancer treatment) Associated with musculoskeletal pain and rare tendinopathy Commonly Affected Sites: Achilles tendon Rotator cuff Patellar tendon Biceps tendon Clinical Presentation: Pain, swelling, or tenderness over tendon May lead to partial or complete rupture (especially Achilles) Often bilateral in fluoroquinolone-related cases Management: Immediate discontinuation of the causative drug Rest, ice, NSAIDs Immobilisation if needed MRI/USG for suspected rupture Surgical repair for full rupture in selected cases Prevention: Avoid fluoroquinolones in high-risk populations Limit steroid injections to <3/year per tendon area Counsel patients on early symptoms Previous Next

< Back Ochronosis Ochronosis is a connective tissue disorder caused by homogentisic acid accumulation, leading to dark pigmentation and early degenerative joint disease. Definition: Ochronosis is the bluish-black discolouration of connective tissues due to the accumulation of homogentisic acid, commonly seen in alkaptonuria , a rare autosomal recessive metabolic disorder. Pathophysiology: Deficiency of homogentisate 1,2-dioxygenase enzyme Leads to accumulation of homogentisic acid (HGA) in tissues HGA binds to collagen in cartilage and tendons, causing pigmentation and brittleness Clinical Features: Dark pigmentation of ear cartilage, sclerae (Osler’s sign), and skin folds Urine turns dark on standing (pathognomonic) Progressive degenerative arthropathy , especially of the spine, hips, and knees Tendon ruptures, calcifications May also involve cardiac valves and kidneys Orthopaedic Implications: Early-onset osteoarthritis unresponsive to conventional treatments Spine involvement is common: calcified discs, kyphosis, stiffness Total joint arthroplasty often required at a younger age Intraoperative tissues appear dark brown or black Diagnosis: Clinical suspicion + urine darkening Urinary HGA elevated Genetic testing for HGD mutations Imaging: disc calcifications, joint space narrowing, osteophytes Treatment: No cure High-dose vitamin C may reduce HGA accumulation (limited evidence) Nitisinone reduces HGA levels (off-label in ochronosis) Surgical treatment for degenerative changes (arthroplasty, spinal surgery) Previous Next

< Back Hemophilia Hemophilia is a hereditary bleeding disorder caused by a deficiency of Hemophilia A (Factor VIII deficiency) and Hemophilia B (Factor IX deficiency) are X-linked recessive disorders. They present with prolonged bleeding after minor trauma, spontaneous hemarthroses (especially in knees, ankles, and elbows), and deep muscle hematomas. Musculoskeletal Implications: Recurrent joint bleeding leads to synovial inflammation, cartilage degradation, and ultimately hemophilic arthropathy, characterised by joint stiffness, pain, and deformities. Radiological Findings: X-rays may show joint space narrowing, osteoporosis, and erosions. MRI is more sensitive for detecting early synovial hypertrophy and hemosiderin deposition. Management: Prophylactic replacement of missing clotting factors (especially in children). On-demand factor therapy during bleeds. Physiotherapy to maintain joint function. Synovectomy or joint replacement in advanced arthropathy. Orthopaedic surgeons must be aware of haemostasis protocols before any intervention. Previous Next

Literature Update Topics The Femoral Head Edema Zone: A Novel Classification Scheme to Better Predict Osteonecrosis Progression The Journal of Arthroplasty (2025) Retrospective single-institution study evaluating whether a new Edema Zone classification (based on extent of femoral head edema on MRI) predicts conversion to total hip arthroplasty (THA) after core decompression for osteonecrosis of the femoral head (ONFH). Compared against the established Japanese Investigation Committee (JIC) classification. 🧠 Key Points Study Population: 94 hips with ONFH treated with core decompression (20 converted to THA within 26 months, 74 did not). Edema Zone vs JIC: Edema Zone classification correlated with THA conversion, while JIC did not (P < 0.001 vs P = 0.83). Predictive accuracy: AUC 0.71 for Edema Zone vs 0.52 for JIC → better prognostic tool . Reliability: Excellent inter-rater reliability for Edema Zone (κ = 0.87), outperforming JIC and other systems. Risk association: Higher Edema Zone grades (≥3) had significantly greater THA conversion rates (e.g., 67% for grade 4). Clinical implication: The Edema Zone classification provides a simple, MRI-based, reliable system to guide surgical decision-making and avoid ineffective core decompressions in high-risk patients. doi.org/10.1016/j.arth.2025.08.035 Optimal Tightrope Positioning for Adequate Syndesmotic Stabilization in Simulated Syndesmotic Injuries Foot & Ankle Orthopaedics (2025) Use of syndesmotic suture button fixation has gained in popularity for treating an injury to the tibiofibular syndesmosis. Biomechanical fixation stability with suture button device (TightRope; Arthrex, Naples, FL) placed at 4 distances from the tibiotalar joint line (0.5, 1.5, 2.5, and 3.5 cm) and 3 trajectories (anterior, medial, and posterior) were studied using cadaveric lower extremities with created syndesmotic injuries. Fixation placed at 0.5 or 1.5 cm from the joint line in medial or posterior trajectories resulted in the lowest increases in fibular rotation. More proximal or anterior placements led to increased fibular motion and decreased rotational stability. 🧠 Key Points Syndesmotic suture button placement 0.5–1.5 cm from the joint line provides the most rotationally stable fixation. Medial and posterior trajectories are more stable than anterior placements. Proximal placements beyond 1.5 cm increase fibular motion and reduce stability. Ankle width changes were minimal but increased slightly with anterior or proximal placement. Biomechanical cadaveric testing simulates in vivo weightbearing and rotational loads. DOI: 10.1177/24730114251342243 Mirels' Score for Upper Limb Metastatic Lesions: Do We Need a Different Cutoff for Recommending Prophylactic Fixation? JSES International (2022), Vol 6(4): 675–681 Conclusions: This study demonstrates moderate to substantial agreement between and within raters using Mirels’ score on upper limb radiographs. However, Mirels’ score had a poor ensitivity and specifity in predicting upper extremity fractures. Until a more valid scoring system has been developed, based on our study, we recommend a Mirels’ threshold of 7/12 for considering prophylactic fixation of impending upper limb pathologic fractures. This contrasts with the current 9/12 cutoff, which is recommended for lower limb pathologic fractures. 🧠 Key Points: Mirels score was originally proposed for metastatic lesions in the lower extremities; its applicability to the upper extremity has been questioned. A score of ≥7 may be sufficient to consider prophylactic fixation in upper extremity metastases. This was a retrospective study analyzing 138 cases. DOI:10.1016/j.jseint.2022.03.006 Body Mass Index > 40 Is Not Correlated With Early Complications in Patients Undergoing Primary Total Joint Arthroplasty at an Ambulatory Surgical Center The Journal of Arthroplasty (2025) Retrospective study of 2,367 patients undergoing primary total hip or knee arthroplasty (THA/TKA) at an ambulatory surgical center. Patients were stratified by BMI groups (normal, overweight, obesity classes I–III including ≥40). Outcomes assessed: early (24h) and 1–90 day complications, perioperative times, PACU course, and pain scores. 🧠 Key Points Complication rates at 24h and 1–90 days were not significantly different across BMI groups, including BMI ≥40. Operative and pre-op times were longer in higher BMI patients, but PACU discharge was earlier . Pain scores before discharge were higher in obesity groups, but without increased adverse events. Estimated blood loss was similar across BMI groups. Conclusion: With proper preoperative optimization, BMI ≥40 should not be an exclusion criterion for outpatient TJA; outcomes are comparable to lower BMI patients. doi.org/10.1016/j.arth.2025.08.065 Alignment Techniques in Total Knee Arthroplasty Journal of Joint Surgery and Research (2023), Vol 1: 108–116 Conclusion: Wide range of clinical results exist for new alignment techniques in the short term. The safe range of alignment for long-term survivorship remains unknown. Further high-quality studies should be performed to warrant the widespread use of new alignment techniques. 🧠 Key Points: • Mechanical alignment remains standard in TKA but doesn’t consider individual pre-arthritic alignment. • Newer techniques (kinematic, restricted, inverse, modified, functional alignment) aim to restore native joint line and improve satisfaction. • Most RCTs show comparable or better short-term outcomes with novel techniques. • Long-term survivorship data are still lacking; alignment “safe zones” remain debated. • Robotic and navigation systems are key tools in implementing newer alignment methods. doi.org/10.1016/j.jjoisr.2023.02.003 Quality of Life and Outcomes After Treatment Failure for Recurrent PJI of TKA The Journal of Arthroplasty (2025) Multicenter retrospective study comparing outcomes of above-knee amputation (AKA), permanent spacers, and knee arthrodesis in patients with recurrent periprosthetic joint infection (PJI) of the knee after failed revisions. A total of 86 patients (35 AKA, 43 spacer, 8 arthrodesis) were evaluated for quality of life (SF-36), pain (VAS, DN4), complications, and functional outcomes. 🧠 Key Points AKA patients had better quality of life scores (higher SF-36 general health and role-physical scores) compared to spacers. Pain relief was superior in AKA (lower VAS and DN4) than both spacer and arthrodesis. Complication and reoperation rates were highest with spacers (53% and 42%) vs. lowest with AKA (14% each). Functional mobility: AKA patients more often walked >1 mile (26% vs. 5% with spacer) and were more frequently able to drive (42% vs. 23%). Mortality and reinfection rates were similar across groups at 2 years. Conclusion: AKA should not only be a last resort —it offers better pain control, fewer complications, and improved QoL in selected patients. doi.org/10.1016/j.arth.2025.08.017 Short-term contemporary outcomes for staged versus primary lower limb amputation in diabetic foot disease Journal of Vascular Surgery (2020) Conclusion : In the setting of infected diabetic foot disease, a staged lower extremity amputation achieves quality outcomes superior to a one-stage amputation, despite the former cohort’s greater illness acuity level. SA should be considered in all diabetic patients presenting with active foot infection. 🧠 Key Points: Staged amputation (SA) was compared with primary amputation (PA) in diabetic foot patients with severe infections. • SA showed lower 30-day readmission (17% vs 27%) and 30-day unplanned reoperation (11% vs 13%). • Length of stay and major adverse cardiovascular events were similar. • SA may provide better short-term quality outcomes in selected patients. doi.org/10.1016/j.jvs.2019.10.083

< Back The Femoral Head Edema Zone: A Novel Classification Scheme to Better Predict Osteonecrosis Progression Retrospective single-institution study evaluating whether a new Edema Zone classification (based on extent of femoral head edema on MRI) predicts conversion to total hip arthroplasty (THA) after core decompression for osteonecrosis of the femoral head (ONFH). Compared against the established Japanese Investigation Committee (JIC) classification. 🧠 Key Points Study Population: 94 hips with ONFH treated with core decompression (20 converted to THA within 26 months, 74 did not). Edema Zone vs JIC: Edema Zone classification correlated with THA conversion, while JIC did not (P < 0.001 vs P = 0.83). Predictive accuracy: AUC 0.71 for Edema Zone vs 0.52 for JIC → better prognostic tool . Reliability: Excellent inter-rater reliability for Edema Zone (κ = 0.87), outperforming JIC and other systems. Risk association: Higher Edema Zone grades (≥3) had significantly greater THA conversion rates (e.g., 67% for grade 4). Clinical implication: The Edema Zone classification provides a simple, MRI-based, reliable system to guide surgical decision-making and avoid ineffective core decompressions in high-risk patients. The Journal of Arthroplasty (2025) doi.org/10.1016/j.arth.2025.08.035 Previous Next