| Type | Location | Related Disease |
| 1 |
Skin Anulus Tendon Ligament |
Osteogenesis Imperfecta (AD, AR, AR, AD) Ehlers Danlos (AD), Dupytrens Contracture (AD) |
| 2 |
Nucleus Pulposus |
|
| 3 |
Skin ( Callus, scar) |
Dupytrens Contracture (AD) |
| 4 | Basement membrane |
|
| 5 | Interstitial tissue IVD Articular Cartilage |
Classic Ehlers Danlos (AD) |
| 6 |
(Specific to IVD) Articular Cartilage |
|
| 7 | Basement membrane | |
| 8 | Basement membrane | |
| 9 | Articular cartilage Epiphyseal Cartilage |
MED (AD) |
| 10 | Mineralising cartilage (calcified zone) |
|
| 11 | Articular Cartilage | Acts as an adhesive |
| 12 | Tendon |
| Feature | Ageing | OA |
| 1. Water content | Decreases | Increases |
| 2. Collagen content | Decreases | Decreases |
| 3. Collagen concentration | Decreases | Increases (Decrease in PG) |
| 4. Chondroitin: Keratin ratio | Decreases | Increases |
| 5. Proteoglycan degradation | Decreases | Increases |
| 6. Proteoglycan content | Decreases | Decreases |
| 7. Chondrocyte number | Decreases | No change |
| 8. Synthetic activity | Decreases | Increases |
| 9. Chondrocyte Size | Increases | No change |
| 10. Stiffness (young’s modulus) | Increases | Decreases (high water content) |
| Amputation Level | Energy Expenditure |
| Long Trans Tibial | 10% |
| Trans Tibial | 25% |
| Short Trans Tibial | 40% |
| Trans femoral | 65% |
| Hip Diarticulation | 100% |
| Bilateral Trans Tibial | 41% |
| Bilateral Trans Femoral | 200% |
| Wheelchair | 5% |
| Material | Young’s Modulus |
| Ceramic | 250 |
| CoCr | 225 |
| Stainless Steel | 200 |
| Titanium | 100 |
| Cortical Bone | 20 |
| PMMA | 2 |
| Polyethylene | 1.5 |
| Cancellous Bone | 1 |
| Tendon | 0.1 |
| Cartilage | 0.02 |
| Condition | Gene Mutation | Inheritance Pattern |
| Chondrosarcoma | Telemerase/RB Genes | |
Multiple Hereditary Exostosis (Osteochon dromatosis) |
EXT 1 & EXT 2 | |
| Neurofibromatosis Type 2 | Chromosome 22 | |
| Osteosarcoma | RB Gene / p53 | |
| Coxa Vara | AD | |
| Charcot Marie Tooth | PMP 22 (Chrom 17) | AD |
| Achondroplasia | FGFR 3 | AD 80% new mutations |
| Cleidocradial Dysplasia | CBFA | AD |
| Ehlers-Danlos Syndrome | COL5A | AD |
| Fasciosca pulohumeral Dystrophy | AD | |
| Kneist’s Syndrome | COL2A1 | AD |
| Marfans | Fibrillin Gene (C15q21) |
AD |
| Multiple Epiphyseal Dysplasia | COL9A1 | AD |
| Neurofibromatosis Type 1 | Ne urofibromin (Ch 17) | AD |
| Pseudo-Achondroplasia | COMP (Ch 19) | AD |
| Spondyloepiphyseal Dysplasia | COL2A1 | AD Tarda type X linked Recessive |
| Tarsal Coalition | AD | |
| Gauchers Disease | Beta Glucoce rebrosidase | AR |
| Djerne-Stotta Disease (HSMN 3) | AR | |
| Freidrich’s Ataxia | FRATAXIN protein | AR |
| Diastrophic Dysplasia | SLC26A2 gene | AR |
| Muccopolysacharidoses e.g. Morquio | AR | |
| Sickle Cell Disease | HBSS gene (Ch 6) | AR |
| Spinal Muscular Atrophy | AR | |
| Familial Vitamin D dependant Rickets | Alpha 1 hydroxylase problem Vit D resistance |
AR |
| Osteogenesis Imperfecta | COL1A1, COL1A2 | Type 1 & 4 AD Type 2 & 3 AR |
| Hypophosphataemic Vit D resistant Rickets | PEX | X Linked Dominant |
| Beckers Muscular Dystrophy | Reduced Dystrophin | X Linked Recessive |
| Duchenne Muscular Dystrophy | Absent Dystrophin protein | X Linked Recessive |
| Layer | Contents |
| Superficial | Biceps Femoris ITB |
Common Peroneal Nerve |
|
| Middle | Patellofemoral Ligament Patella retinaculum |
| Deep Superficial | Lateral Collateral Fabellofibular Ligament |
Lateral Geniculate Artery |
|
| Deep Deep | Popliteus tendon Arcuate Ligament Coronary Ligament Popliteofibular ligament Lateral Capsule |
| Layer | Contents |
| Layer 1 | Patella Retinacular fascia Sartorius & Sartorius Fascia |
Semitendinosus |
|
| Layer 2 | Superficial Medial Collateral POL |
| Layer 3 | Semimembranosus (5 insertions) Medial Capsule Deep MCL |
| Stable Stance |
| Adequate Step Length |
| Foot Clearance |
| Energy Conservation |
| Pre-positioning of Foot |
| Pelvic Tilt |
| Pelvic Lateral bend |
| Pelvic rotation |
| Knee flexion |
| Ankle Motion |
| Step | Heel strike to the heel strike of the opposite foot |
| Stride | Heel strike to the next heel strike of the same foot |
| Cadence | Steps per unit time |
| Velocity | Stride length/Stride time |
| 1stRocker | Eccentric contraction of Dorsiflexors |
| 2ndRocker | Eccentric contraction of Plantarflexors |
| 3rdRocker | Concentric Contraction of Plantarflexors |
| Seddon | Pathology | Prognosis | Sunderland Equivalent |
| Neuropraxia | Axon in continuity No Wallerian Degeneration Epineurium intact Segmental Demyelination |
Good | 1 |
| Axonotmesis | Wallerian Degeneration distal to lesion Epineurium disrupted Variable perineurial damage Endoneurium intact |
Good | 2-4 |
| Neurotmesis | Wallerian degeneration distal to lesion Epi, peri & Endoneurium disrupted | Poor (No tube for growth) |
5 |
| Test | Sensitivity | Specificity |
| Combined CRP & ESR (>15 & >30) | 99% | 95% |
| PET Scan | 98% | 98% |
| Triple phase Bone Scan | 99% | 95% |
| Frozen Section | 85% | 95% |
| Joint aspiration & Culture (⇑ by multiple aspirations) | 70% | 95% |
| Gram Stain | 25% | 95% |
| PCR (too sensitive – contaminants = false positive) | >99% | 80% |
| Type | Subtype | Examples |
| Fibrous | SUTURES | Between skull bones |
| SYNDESMOSIS | Ankle syndesmosis | |
| Cartilaginous Primary | SYNCHONDROSIS | Physis Epiphysis |
| Cartilaginous Secondary | SYMPHISIS | Pelvic Bones IVD |
| Synovial (Diarthrodial) | HINGE | Ulnohumeral IPJs Ankle Knee |
| Synovial (Diarthrodial) | SADDLE | Thumb CMCJ |
| Synovial (Diarthrodial) | CONYLOID | MCPJ Wrist |
| Synovial (Diarthrodial) | ROTATORY | PRUJ |
| Synovial (Diarthrodial) | BALL & SOCKET | Hip Shoulder |
| Synovial (Diarthrodial) | SLIDING | Carpal Tarsal |
| Hazy Physis |
| Widened Physis |
| Metaphyseal cupping |
| Metaphyseal Flaring |
| Looser’s zones |
| Coxa Vara |
| Tibial Varus |
| Small ossific nuclei |
| Coarse Trabecullae |
| Thickened cortices |
| Coxa Vara |
| Varus Tibia |
| Rachitic Rosary |
| Short Stature |
| Frontal Bossing |
| Waddling Gait |
| Harrisons Sulcus |
| Dental Disease |
| Codfish Spine – central depressed vertebrae |
| Kyphosis – cat back |
| 1st Law | The sum of forces acting on a body at rest must be equal |
| 2ndLaw | Acceleration is directly proportional to the force applied (F=MA) |
| 3rdLaw | Every action has a reaction of equal magnitude and opposite direction |
| J | Joints are frictionless hinges |
| O | Only compressive forces act on joints |
| I | Internal forces are all equal |
| N | No antagonistic muscle action |
| B | Bones are rigid rods |
| M | Muscle pull is in one direction only |
| W | Weight is at the centre of the body mass |
| Tumour | Location | Features |
| Osteoid Osteoma | Posterior | Apex & convexity of curve Curve resloves with resection |
| Osteoblastoma | Posterior | Painful; Adults |
| ABC | Posterior | May spread anterior May be within a malignant tumour |
| Osteochondroma | Posterior | Snapping Scapula syndrome |
| Fibrous Dysplasia | Body | 50% with polyostotic have FB in spine |
| Haemangioma | Body | Jail house Vertebrae |
| Eosinophilic Granuloma | Body | Vertebra Plana |
| Giant cell Tumour | Body | May undergo malignant change |
| Myeloma | Body | Lytic, multiple lesions |
| Cordoma | Body | Sacrum, Radiosensitive |
| Lymphoma | Body | Ivory vertebra |
| Type | Location | Features |
| Intramedullary (classic) | MD junction Around knee |
80% High grade Metaphysis-diaphysis junction Classic type features |
| Parosteal | Distal femur Proximal Humerus |
15% Low grade On Bone surface Mainly osteoid – like osteochondroma |
| Periosteal | Tibia Femur Diaphysis |
Very rare Low grade Bone surface Chondroid and oseoid features |
| Taelangectic | Around knee | Highly grade Poor prognosis Lytic May mimic ABC |
| Post Radiotherapy | Anywhere | High grade Mean occurrence 17 years post Rx Poor prognosis |
| Pagets | Femur Pelvis Humerus |
High grade Mainly in polyostotic chronic disease |
| High LDH levels |
| High Alkaline phosphotase |
| Expression of p Glycoprotein |
| Absence of Antishock protein 90 |
| Pelvic location |
| Pathologic fracture at presentation |
| <90% tumour necrosis after neo-adjuvant chemo |
| Vascular invasion |
| Recurrence/incomplete margins |
| Metastases at presentation (bone worse than lung) |
| Type | Location | Features |
| Intramedullary (classic) | P elvis Sho ulder Prox Femur Hand |
Mean age 45 Telemora se/RT genes Slow growing large mass Prognosis correlates to grade Not radio- chemo sensitive |
| Dedifferentiated | Same | Low grade CS on Spindle cell Tumour (OS) Worst prognosis (10% at 5 y ears) Rx for both lesions |
| Clear Cell | Epip hysis | Mimics Chondrobla stoma Low grade, lytic |
| Mesenchymal | Same | Very rare Younger patients Bad prognosis |
| Tumour | Feature |
| Adamantinoma or GCT | Soap Bubble Appearance |
| Chondroblastoma | Chicken wire calcification |
| Chondrosarcoma | Featureless a ppearance Large binuclear cells |
| Chordoma | Phylsaliferous cells |
| Eosinophilic Granuloma | Birbeck granules (raquet shaped) |
| Ewings Sarcoma | Round blue cells |
| Fibrosarcoma | Herring Bone Pattern Spindle cells |
| Fibrous Dysplasia | Ground Glass appearance Chinese letter /Alphabet soup appearance |
| Lymphoma | Small round B cells (CD20 positive) |
| Malignant Fibrous Histiocytoma | Storiform appearance No spindle cells |
| Osteosarcoma | Pleomorphic Spindle cells |
| Plasma cells | Clock face pattern |
| Rhabdomyosarcoma | Raquet shaped cells |
| Synovial Sarcoma | Biphasic pattern |
| Polished Exeter stem | 0.01 |
| Ceramic head | 0.02 |
| Metal head | 0.025 |
| Polyethylene cup | 2.0 |
| Articular cartilage | 3.0 |
| Native Knee | 0.005 |
| Native hip | 0.01 |
| Metal on poly | 0.02 |
| Metal on metal | 0.8 |
| Boundary | Single molecular thickness boundary between surfaces Predominant in prosthetic joints Lift off phase of gait |
| Fluid Film | Predominates in Native Joints Also in MoM articulations Preferred |
| Hydrodynamic | High speed low load More in prosthetic joints Higher loads lead to contact of surfaces |
| Elastohydrodynamic | Predominant in native articular cartilage Reliant on deformation of articular cartilage Increased SA, viscosity and decreased shear rate |
| Squeeze Film | Rapid loading builds pressure in lubricating fluid Enables fluid to resist load better Initial contact in gait |
| Weeping | Compression elutes further fluid from articular surface |
| Boosted | Under constant load water is pressurised into cartilage This leaves a more viscous hylaronic rich fluid |
| Gait Cycle Phase | Predominant type of Lubrication |
| Initial contact | Squeeze Film |
| Stance | Elastohydrodynamic |
| Lift off | Boundary & Elastohydrodynamic |
| Swing | Hydrodynamic |
| Prolonged Stance | Boundary, boosted |
Zone |
Disease |
| Epiphysis | MED SED Trevors |
| Reserve | Pseudoachondroplasia Gauchers |
| Proliferative | Achondroplasia Gigantism |
Hypertrophic Maturation & Degenerative |
SUFE Trauma Enchondroma Mucopollysacharidoses |
Hypertrophic Zone of Provisional Clacification |
Rickets Osteomalacia |
| Metaphysis | Renal SUFE Scurvy Osteomyelitis Osteogenesis Imperfecta |
| Term | Definition |
| Sensitivity | Ability of a test to correctly identify those with the disease - TP/TP+FN |
| Specificity | Ability of a test to correctly identify those without the disease - TN/TN+FP |
| PPV | How often a positive test result is truly positive - TP/TP+FP |
| NPV | How often a negative test result truly is negative - TN/TN+FN |
| Accuracy | With repetition who often a test is correct - TP+TN/TP +FP+TN+FN |
| Reliability | With repetition how often a test will produce the same result Inter & Intra -observer |
| Odds Ratio | Likelihood the positive finding will occur more often in the treatment group rather than the control group |
| Validity | Degree to which a test or study correctly measures what its meant to be measuring |
| P revalence | The number of people with a disease within an at risk population at any given time point – a snapshot |
| Incidence | The number of new diagnoses of a disease within an at risk population per year |
| P value | The probability that the finding was purely by chance |
| Type 1 Error | Rejecting the null hypothesis in correctly (5% acceptable) |
| Type 2 Error | Accepting the null hypothesis in correctly (20% acceptable) |
| Power | 1-Type 2 error |
| Power Analysis | Tells us how many participants are needed to have no more than a type 2-error rate of 0.2 (20%) (pre or post hoc) |
| Normal Distribution | A distribution in which the mean, mode and median are the same |
| Non-Parametric | A distribution in which the mode and median must be used to describe the central tendancy, not the mean |
| Power Analysis | Tells us how many participants are needed to have no more than a type 2-error rate of 0.2 (20%) (pre or post hoc) |
| Standard Deviation | Describes the deviation away from the mean for a parametric distribution |
| Confidence Interval | Describes the spread away from the mean for a non-parametric distribution The range of values in which there is a 95% chance the true result lies |
| Inte rquartile Range | Describes the spread from the mean for a non-parametric distribution Just another method to confidence intervals (confidence intervals p referred) |
| Test | Use |
| Student T Test | Parametric 2 variables |
| ANOVA | Parametric Multiple variables |
| Chi Squared | Non-Parametric For 2 discrete variables e.g. to show that the number of females and number of males with or without SUFE is different |
| Yates Correction | Correction to Chi Squared when sample size <30 |
| Fisher’s exact test | Replaces Ch i-Squared when sample size <5 |
| Mann Whitney U | Non-Parametric For discrete data e.g. to show the difference between the PS angle measurement in men and women |
| Kruskal l-Wallace | Non-Parametric Multiple variables Continuous Data |
| AIS Score | Injury |
| 1 | Minor |
| 2 | Moderate |
| 3 | Serious |
| 4 | Severe |
| 5 | Critical |
| 6 | Unsurvivable |
| Body Region | Injury description | AIS | Square of top 3 |
| Head & Neck | Cerebral contusion | 3 | 9 |
| Face | No injury | ||
| Chest | Flail chest | 4 | 16 |
| Abdomen | Liver Laceration | 4 | 16 |
| Extremity | Femur Fracture | 3 | |
| External | No Injury | 0 | |
| Total ISS score | 41 |
ISS >25 = severe injury ISS >40 = life threatening
Layer 1 (most plantar) |
ABDm ABDh FDB |
| Layer 2 | Lumbricals FHL FDL Quadratus Plantae |
| Layer 3 | ADDh FHB FDM |
Layer 4 (deepest) |
Dorsal Interossei x4 Plantar Interossei x3 Peroneus Longus Tibialis Posterior |
| Dorsal | EDB EHB (only rarely present) |
| Type | Description | Notes |
| Salter | Volume neutral Hinges on sciatic notch and pubic symphisis |
Triradiate can be open |
| Ganz | Volume neutral Multiplanar osteotomy close to acetabulum Allows large correction |
Triradiate must be closed |
| Pemberton | Volume Reducing Iliac wing to triradiate held open with bone Hinges on triradiate |
|
| Dega | Volume reducing Iliac wing to just before sciatic notch |
|
| Chiari | Volume Increasing - Salvage Osteotomies around acetabulum and medialisation Creates a lateral shelf to increase coverage |
Fibrocartilage forms beneath shelf Salvage |
| Shelf | Volume Increasing – Salvage Bone grafting lateral to acetabulum Creates a shelf |
Salvage |
| Primary Static | Secondary Static | Secondary Dynamic |
Ulna collateral of LCL (varus & posterolateral) |
Radial Head Primary stabilizer if coronoid/MCL fractured /torn(v algus & AP) |
Anconeus |
| Anterior band of MCL(valgus) | Brachialis | |
| Coronoid Process | Flexor & Extensor masses |
| Grade | Clinical Findings |
| 0 | No Movement |
| 1 | Flicker of movement |
| 2 | Active movement with gravity eliminated |
| 3 | Active movement against gravity |
| 4 | Active movement against some resistance |
| 5 | Normal power |
| Screw Type | Cortical | Cortical | Cancellous | Locking | Locking |
| Thread diameter | 2.7 | 3.5 | 4.0 | 2.7 | 3.5 |
| Drill | 2.0 | 2.5 | 2.5 | 2.0 | 2.8 |
| Tap | 2.7 | 3.5 | 4.0 | Self tap | Self tap |
| Screw Type | Cortical | Cortical | Cancellous | Locking | Locking |
| Thread diameter | 4.5 | 5.5 | 6.5 | 4.0 | 5.0 |
| Drill | 3.2 | 4.0 | 3.2 | 3.2 | 4.3 |
| Tap | 4.5 | 5.5 | 6.5 | Self tap | Self tap |
| View | Description | Use |
| True AP | Beam at 45 degree to body or Arm externally rotated |
GHJ pathology General screening |
| Axilliary Lateral | Arm abducted 90 deg Beam shot cranially through axilla |
Dislocations Humeral head shape |
| Trauma Axilliary | Arm abducted 20 deg | Same – slightly inferior quality |
| Valpeau Axilliary | Beam directed caudally through shoulder | Allows sling to be left on Inferior quality |
| Trans-scapula | Shot in plane of scapula spine | Dislocation |
| Supraspinatus outlet | In plane of scapula with 10 degree caudal tilt | Acromium morphology |
| Westpoint | Prone with arm of table at 90 degrees. Beam shot 25 deg caudally and medially |
Glenoid rim fractures |
| Stryker notch | Supine with hand on hed Beam shot 10 degree cephalic |
Hill Sachs lesion |
| Zanca | AP with 10 degree caudal tilt | ACJ |
| Serendipity | 45 degree cephalic | SCJ |
| Garth Apical Oblique | Seated with arm in IR Beam 45 deg caudal and lateral |
Shoulder instability Hill Sach, Glenoid rim |
| Joint | Position |
|---|---|
| Hip | Flexion 30; Adduction 5; ER 10 |
| Knee | Flexion 0- 10; Valgus 5; ER 10 (Charnley recommended full extension – cosmetic) |
| Ankle | Flexion 0; Valgus 5; ER 10 Slight posterior dis placement of talus (reduces stress on knee) |
| 1st MTPJ | Valgus 10, neutral rotation Dorsiflexion – toe just of floor in plantigrade foot position |
| Subtalar Joint | Valgus 10; Flexion 0 (neutral) |
| Shoulder | Flexion 30; Abduction 30; IR 30 (IR is most important determinant of function) |
| Elbow | Flexion 70-90 (More better for personal hygiene, less better for other use) (If bilateral one should be more flexed than the other) |
| Wrist | Ulna deviation 5; Extension 5(some extension better for grip – too much limits pronation/supination) |
| Thumb CMCJ | Abduction 30; Extension 30; Pronation 15 |
| Thumb MCPJ | Flexion 25 |
| Finger MCPJ | [Flexion 45 (Index with supination 10 degrees – pinch grip) |
| Finger PIPJ | Index & Middle – Flexion 20 with supination( pinch) Ring & Little – Flexion 40 (grip) |
| Finger DIPJ | Index & Middle] – straight Ring & Little – straight stops catching, 5 deg flex ion aids grip |
| Ligament | Restrains against |
| SGHL | ER in Adduction |
| MGHL | Anterior translation in mid range of Abduction |
| Anterior IGHL | Anterior translation in 90 deg Abduction & ER |
| Posterior IGHL | Posterior Translation in 90 deg Abduction & IR |
| Medication | Mode of Action |
|---|---|
| Paracetamol | Weak COX inhibition Central action (poorly understood) |
| NSAIDs | Inhibit cyclo- oxegenase enzyme – prevent PG formation COX1 non s elective, COX2 selective |
| Opiates | Mimic endogenus opioids Centrally via G proteins on mu receptors |
| Steroids | Direct inhibition of T Lymphocytes and Macrophages (immunosupressive) Prevent transcription of gene which codes for COX2 enzyme ( anti-inflammatory) |
| Local Ana esthetics | Inhibit action potential formation by blocking Na channels pH dependent |
| Warfarin | Affects Factors 2, 7, 9, 10 (Vit K dependent) Prevents carboxylation of glutamine residues Renders these factors useless Also de- activates Protein C and protein S |
| Heparin | Forms a complex with Ant ithrombin 3 Primarily directly inhibits Thrombin (factor 2a) and Factor |
10a Also affects all active factors in intrinsic pathway 12a, 11a, 9a |
|
| LMWH | Also forms a complex with Ant ithrombin 3 But, se lectively affects Factor 10a only |
| Fondaparinaux | Selective factor 10a inhibitor |
| Rivaroxiban | Selective factor 10a inhibitor |
| Dabigatran | Direct THROMBIN (factor 2a) inhibitor |
| Aspirin | Binds irreversibly with COX1 enzyme Inhibits PG production Prevents platelet aggregation and prevents platelet secretion of Thromboxane A2 (prothrombotic agent) |
| Bisphosphonates | Stabilise HA crystals Directly inhibit Osteoclasts – prevent ruffled border formation Cause apoptosis of osteoclasts Nitrogen Containing malevonate pathway: farnesyl synhthesis Non -nitrogen containing form toxic ATP anologue - apoptosis |
| Strontium | Anabolic and Catabolic effect on bone Increase formation and decrease r esorption |
| Methotrexate | Non biologic DMARD Inhibits purine metabolism (azothioprine similar) |
| Entanercept | Biologic DMARD – TNF inhibitor |
| Infliximab | Biologic DMARD – TNF inhibitor |
| Penicillamine | Biologic DMARD – Reduces T Lymphocytes |
| Anakinara | Biologic DMARD – Interleukin 1a ntagonist |
| Condition | Features |
| Metatarsus Adductus | Packaging issue – benign Due to stronger inverters and plantar flexors Measured by thigh foot axis Resolves spontaneously by WB age |
| Internal Tibial Torsion | Normal Measured by inter-malleolar axis Resolves by age 2-4 years (30 degrees ER) |
| Anteversion of the femoral neck | Normal variant Resolves by age 5 – 8 to 20 deg anteversion |
| Club Foot | Pathologic |
| Cerebral Palsy | Pathologic |
| Cause | Features |
| Muscular | Most common SCM spasm and contracture (Intrauterine Compartment syndrome) Head tilted towards the contracture, neck away Plagiocephaly, facial asymetry |
| Acute Idiopathic | Wakes up with it No SCM contracture or mass |
| Congenital | Look for low hair line, webbed neck etc. |
| Neurogenic | No SCM contracture Nerve tumour |
| Occular | Due to visual problem |
Atlanto-Axial Rotatory Instability |
Traumatic Syndromic (Morquio’s, Down’s etc.) Infective – Griesel’s |
| Genu Varum | Genu Valgum |
| Blount’s Disease | Fibula Hemimelia – Hypoplastic LFC |
| Rickets (all types) | Morquio Syndrome |
| Achondroplasia | MED |
| Tibial Hemimelia | Cozen’s fracture |
| Osteogenesis I mperfecta | Hypophos phataemic Rickets sometimes |
Multiple hereditry Osteochond romatosis Infection Trauma |
| Sign |
| Gage’s Sign: triangular lucency from lateral aspect of physis |
| Lateral Head Subluxation |
| Calcification lateral to the head |
| Horizontal physis |
| Stage | Features |
| Initial | Sclerosis – normal head shape |
| Fragmentation | Fragmented head usually lateral aspect epiphysis This is the time where treatment can affect outcome most |
| Re-Ossification | Head resorption |
| Re- Modelling | Head attempts to remodel into normal shape |
| Measurement | Value |
| ADI (C1/2) | Normal = 3mm (adult) 5mm (child) 3-5mm = Transverse ligament torn (adult) >5mm = Transverse, apical & alar ligaments torn (adult) 3.5 mm change on Flexion/extension = Instability >9mm in RA is an indication for surgery (In RA 4-9mm may not be an indication for surgery if neurologically normal) |
| PADI (SAC) (C1/2) | <14mm indicates stenosis (<14mm best prognostic indicator for successful surgery) <10mm indicates absoloute stenosis |
| Ranawat Index | <14mm indicates Basilar invagination – indication for surgery |
| Subaxial Instability | Up to 4mm or 40% displacement of vertebrae is acceptable |
Fl exion- Extension views |
>11 degree Cobb angle change indicates instability |
| Powers Ratio | <1 is normal (more may indicate Atlanto-occipital dissociation) |
| Torg Ratio | 0.8 or less indicates stenotic spine |
| Lateral Mass widening | >7mm indicates TL disruption of C2 (on PEG view) |
Schwischuks line |
Interspinous processes of C1-3 intersect within 2mm Allows C2/3 or C3/4 pseudosubluxation up to 4mm or 40% |
Pre-vertebral Soft Tissue Swelling |
>7mm at C3 abnormal (adult) >20mm at C6 abnormal (adult) >5mm at C3 abnormal (child) - may be false positively increased if child crying – retropharangeal swel ling) >16mm at C6 abnormal (child) |
| Level | Risk |
| C1 | 50% |
| C2 | 30% |
| C3 | 20% |
| Metal | Composition |
| Stainless Steel 316L | 60% Iron 20% Chromium 16% Nickel 3% Molybdenum 0.03% Carbon L = low carbon: improves heat resistance |
| Titanium AL-6 V-4 | 90% Titanium 6% Aluminium 4% Vanadium <1% other |
| Cobalt Chrome | 60% Cobalt 25% Chromium 5% M olybdenum 10 % other |
| Fibre Type | Example | Myelination | Diameter | Velocity |
| Aα | Motor large diameter |
Myelinated | 20 | 100 |
| Aβ | Organised sensory ( hair) | Myelinated | 10 | 50 |
| Aδ | Pain & Temperature | Myelinated | 5 | 25 |
| B | Auto nomic Pre- Gangl ionic | Myelinated | 5 | 10 |
| C | Autonomic Postganglionic Cutaneous slow pain |
Unmyelinated | 1 | 2 |
| Type | T1 | T2 | Relevance |
| Modic 1 | Dark | Bright | Associated with pain and inflammation End plate fissuring Histology – vascular granulation (25%) |
| Modic 2 | Bright | Bright | Trabecular fissuring Fatty infiltration of vertebra Correlates with chronic stable back pain Most common type (70%) |
| Modic 3 | Dark | Dark | Rare to see Sclerotic vertebra and end plates |
| Sign |
| Over reaction |
| Hysteria |
| Simulation |
| Non-dermatomal pain |
| Pain and numbness simultaneously |
| Pain on light touch |
| Distraction pain reduction |
| Phase | Features |
| Interphase | Encompasses the whole cycle except Mitosis G1, S and G2 are all part of interphase |
| G0 | When a cell has left the cell cycle i.e. not dividing Neurons are permanently in G0 |
| G1 | Growth phase Controlled by p53 gene Cells are increasing in size Being redied for synthesis |
| S | DNA Synthetic phase Chromosomes divide into chromatids Still all contained in one nucleus |
| G2 | Growth phase 2 Again the cell grows post synthesis Readies itself for mitosis |
| M | Mitosis – cell division (not part of interphase) Chromatids are separated into different nuclei Cell divided (cytokinesis) This is the shortest phase |
| 1st | APL, EPB |
| 2nd | ECRL, ECRB |
| 3rd | EPL |
| 4th | EDC, EIP,PIN |
| 5th | EDM |
| 6th | ECU |
| Greater | Lesser |
| Above Piriformis | Superior Gemellius |
| Superior Gluteal Nerve | Obturator Externus |
| Superior Gluteal Artery | Inferior Gemellius |
| Below Piriformis | Quadratus Femoris |
| Inferior Gluteal Nerve | |
| Inferior Gluteal artery | |
| Pudendal Nerve | |
| Pudendal Artery (internal) | |
| Sciatic Nerve | |
| Nerve to Obturator Internus | |
| Posterior Femoral Cutaneous Nerve | |
| Nerve to Quadratus Femoris | |
| Don’ forget Piriformis |
| Vertebrae | Coronal Plane | Saggital Plane |
| Cervical | 0 | 45 |
| Thoracic | 20 | 55 |
| Lumbar | 50 | 90 |
T4 smallest in whole spine
L1 smallest in lumbar spine
T1 largest in Thoracic spine
| Vertebra | Features |
| Cervical | Foramina transversarium (C7’s is empty) Bifid spinous processes (not C7) Facets 0 degree in coronal, 45 degree saggital plane |
| Thoracic | Costal facets on all vertebral bodies Costal facets on T1-9 transverse processes Facet orientation 20 coronal 55 saggital |
| Lumbar | Mamilliary processes Taller anteriorly – provide lordosis Shorter wider pedicles Facet orientation 50 coronal, 90 saggital |
| Type | Features |
| Type 1 | Medial and Lateral Facets equal – ridge central |
| Type 2 | Medial Facet smaller – ridge medialised (most common) |
| Type 3 | Medial facet tiny & far medialised rendering ridge almost absent |
| Type | Features |
| Polycentric (4 Bar Linkage) | Allows varied COR during gait COR Anterior during flexion/sitting COR Posterior during stance for stability Bilateral amputees Transfemoral Through Knee |
| Hydraulic/Pneumatic Knee | Heavier Provides most fluid gait pattern Varied resistance during flexion Good for young high demand patients |
| Constant Friction | Basic hinge that uses a pad/screw to dampen flexion Stance control not great Common in children |
Variable Friction (cadence control) |
Varied resistance with multiple pads Poor durability |
Stance Phase Control (safety knee) |
Knee freezes in extension (frictional jamming) Provides extra stability in extension for stable stance Good for elderly or those at risk of falling |
| Manual Locking Knee | Knee can be physically locked in extension For very weak, unstable patients |
| Albumin <3.5 g/dL |
| Lymphocyte count <1500mm3 |
| Low Serum Transferratin |
| ABPI <0.45 |
| Transcutaneous Oxygen Sats <20mmHg (>40 is a positive predictor) |
| Hb <10g/dL |
| Region | Level |
| Forearm | Junction proximal 2/3 and distal 1/3 |
| Humerus | Middle 1/3 |
| Trans Tibial | 8cm per meter of height (usually around 15 cm below TT) |
| TransFemoral | Middle 1/3 |
| Part | Features |
| Socket | Interface between residuum and prosthesis |
| Suspension | Method of attachment to the residuum |
| Struts | Restore length Connect to the terminal device |
| Articulations | Replace joint function as necessary |
| Terminal Device | Most distal part Passive (cosmetic) or active (functional) Active are controlled by cables, struts, or myoelectric |
| Type | Immunoglobulin | Examples |
| 1 | IgE | Atopy & allergy Immediate hypersensitivity Asthma |
| 2 | IgM | Antibody related – cytotoxic ITP, Graves disease etc. |
| 3 | IgG | Immune complex mediated e.g SLE & Rheumatoid arthritis |
| 4 | T cells | Delayed hypersensitivity Mantoux test Contact dermatitis |
Inate form of immunity that ‘complements’ other forms of immunity. Main role is enhancing macrophage function, chemotaxis and cytokine co-ordination.
| Angioplasty | -‐upto 57mSv | 15-‐20years |
| Bone Scan–T99m | -‐3mSv | 1year |
| CT Neck | -‐0.6mSv | 2months |
| CT Pelvis-‐abdo | -‐10mSv | 3years |
| CXR | -‐0.1mSv | 10 days background |
| DEXA scan | -‐0.001mSv | <1day |
| Limb X-‐ray | -‐0.001mSv | <1day |
| PET Scan | -‐14mSV | 4years |
| Spine X-‐ray | -‐1.5mSv | 6months |
| Feature | Ligament | Tendon |
| Elastin Content | Greater | Less |
| Strength | Weaker | Stronger |
Collagen Arrangement |
Layered Each layer has parallel fibres |
Longitudinal |
| Insertion | Direct | Indirect or Direct |
| Function | Stabilise j oints | Place muscle at optimal distance Act as a spring – store energy |
| Blood Supply | Via insertion site Uniform |
Via Para tenon (vascular) Via single Vinculae & diffusion ( avascular) Musculotendinous junction Insertion site |
| Component | Features | |
Cells 20% |
Fibrob lasts | Predominate |
| Tenocytes | Some present after healing of tendon/ligament | |
| Matrix 80% | Collagen 90% | 90% Type 1 Type 3 during proliferative phase of healing <1% other types |
| Proteoglycans | Negatively charged at tract water – create gelatinous matrix | |
| Elastin | Aids ability to recoil – more in ligaments | |
| Other Proteins | MMP’s, glycoprotein’s etc. |
| Mode | XR features | Cause |
| 1a PIVOT | Stem subsidence | Inadequate bonding |
| (Stem in cement) | Lucency zone 1 & 7 Cement fracture zone 4 |
Inadequate cement |
1b P IVOT (cement in bone) |
Subsidence Circumferential lucency |
Inadequate pressurization Removal of all cancellous bone |
| 2 Mid – Stem Pivot | Lucency zone 1, 2, 5, 6 Cement fracture at midstem Stem in varus |
Poor fixation proximal & distal |
| 3 Calcar Pivot | Lucency zones 4,5,6 Windscreen wipering stem Sclerosis at stem tip |
Poor distal fixation |
| 4 Canti lever Bending | Lucency 1, 2,6,7 Stem fracture |
Poor proximal fixation |
| 1stGeneration | 2ndGeneration (1975) | 3rdGeneration (1982) |
| Finger Packing | Cement Gun – retrograde | Porosity reduction (vacuum mix) |
| Sharp edged stem | Pulse lavage | Pressurisation (interdigitation) |
| Canal brushed & dryed | Stem centraliser (mantle defects) | |
| Cement Restrictor | Rough Stem Finish |
| Liquid (1 Part) | Powder (2 Parts) |
| Monomer -MMA | Polymer - PMMA |
| Accelerator – N-Dimethyl-p-toludine | Initiator – Di-benzoyl Peroxide |
| Inhibitor – Hydroquinone | Barium Sulphate |
| Dye (chlorophyll) | Antibiotics |
| Phase | Features |
| Mixing Phase | Performed homogenously in a vacuum to reduce porosity |
| Waiting (Dough phase) | From mixing until cement is no longer doughy Viscosity increases Too low a viscosity will allow blood to mix into cement |
| Working Phase | The time during which cement can be manipulated Difference between doughy and setting times |
| Hardening Phase | Cement completely hardens Influenced by temperature of stem, cement, theatre |
| Setting Time | From mixing until cement has reached half its maximal heat |
| Deformity | Releases |
| Varus | Osteophytes Medial capsule & deep MCL PM corner & Semimembranosus PCL Sequential release of superficial MCL at Pes Anserinus |
| Valgus | Osteophytes Lateral capsule from tibia ITB if tight in extension, Popliteus if tight in flexion LCL from femur Pie crust posterolateral capsule |
| Flexion | Posterior condyle osteophytes & capsule Sequential PCL release Pie crust posterior capsule Increase tibial slope Downsize femur |
| Measurement | Method | Values |
| Height | Lateral XR in 30 deg flexion Blumensats line Insall-Salvetti Patella tendon:Patella length[Balckburn-Peel] Distal pole patella to joint line: Patella articular surface |
Distal pole lies at B line <0.8 = Baja >1.2 = Alta <0.8 = Baja >1.0 = Alta |
| Tilt | Merchant CT mid-axial cuts Between patella edges and horizontal line |
>10 = significantly abnormal <7= normal |
| TTTG Distance | CT mid-axial cuts | <10 = normal 10-20 = borderline abnormal >20 = significantly abnormal |
| Name | Equation | Clinical relevance |
| Law of wear | V=SL/H | Volumetric wear can be reduced by decreasing head size, decreasing load or increasing hardness of the bearings |
| Radial Clearance | Cup r - Head r | Increased clearance articulations have a longer bedding in period Mid-polar contact achieved with 90400um Radial clearance |
| Fracture Energy | E=1/2MV2 | Fracture energy more influenced by velocity than mass |
| Bending Rigidity | BR = SMI x Young’s | BR is a product of the material and its spacial distribution around the neutral axis of the plate |
| 2nd moment of inertia of a plate | SMI = W x T3 | SMI influenced more by thickness (to the power 3 for a plate) than width therefore BR more influenced by thickness |
| 2nd moment inertia of a cylinder | SMI = 0.25 x 3.14 x r4 | Bending rigidity of a tube is increased to the 4[th]{st yle=“font-size:8pt; v ertical-align:super”} power |
| Torsional Rigidity | TR = PMI x Young’s | Polar moment of inertia reflects torsional rigidity |
| Polar Moment of Inertia | PMI = 0.5 x 3.14 x r4 | Torsional rigidity of a tube is increased to the 4[th]{st yle=“font-size:8pt; v ertical-align:super”} power but more influenced by increase in size than bending rigidity (x0.5) |
| PMI of a hollow tube | PMI=0.5x3.1 4(ro-ri)4 | Difference between radii of outer and inner part of nail |
| Newtons law of viscosity | Viscosity = Shear stress /Shear rate V is proportional to change in shear rate |
Synovial fluid is a non-newtonian fluid Disobeys this law Displays Thixotropy and pseudoplasticity |
| Features | Details |
|---|---|
| Uniform Attack | Most common form of corrosion |
| Affects the whole surface of the implant | |
| Occurs when a metal is in an electrolyte solution – e.g. human body | |
| Galvanic Corrosion | Two dissimilar metals create an electrochemical gradient between them |
| Effectively a small battery | |
| As ions are exchanged | |
| Typical with Stainless Steel, especially when coupled with Titanium | |
| Crevice Corrosion | Cracks in the metal destabilise the passivity layer |
| The base of the cracks lacks oxygen therefore can’t self passivate | |
| Corrosion occurs at these defects | |
| Pitting Corrosion | Similar process to crevice corrosion |
| More insidious and localised | |
| Crevice more widespread | |
| Fretting Corrosion | Actually a combination of wear and corrosion |
| Two non-articulating areas abrade each other | |
| Micromotion abrades the passive layer and wear debris are generated | |
| Head neck junction in large diameter MoM THR | |
| Intergranular Corrosion | Galvanic gradient occurs between grains in the metal ultrastructure |
| Caused by the presence of impurities trapped in manufacturing process | |
| Occurs at the grain boundaries | |
| Leeching (Intragranular Corrosion) | Effectively intra-granular corrosion |
| Galvanic corrosion within, not between metal grains | |
| Inclusion Corrosion | Iatrogenic corrosion |
| Galvanic corrosion occurs because of accidentally retained metal fragments | |
| E.g., screw driver tip | |
| Stress Corrosion | Repeated stress in one area disrupts the passive layer |
| Common in cyclically loaded stainless steel |
| Features | Details |
|---|---|
| Contact Healing | Minimal activity at areas in direct contact |
| Mesenchymal cells differentiate to osteoblasts | |
| Lay down lamellar bone in small gaps, woven bone in large gaps | |
| Gap Healing | Cutting Cones: Osteoclast-headed cutting cones tunnel across the fracture |
| Neo-vascularisation and osteoblasts migrate in their wake | |
| Osteoblasts form Harversian canals which take 1-2 years | |
| Remodeling | Osteoblasts form Harversian canals which takes 1-2 years |
| Features | Details |
|---|---|
| Haematoma | Hours |
| Clot formation | |
| Platelet degradation – PDGF released | |
| Activates clotting cascade & complement system | |
| Activates chemotactic factors (TNFa, TGFb, IL-1 & 6) | |
| Attract PMN’s and activate BMPs | |
| Inter-fragmentary strain is 100% | |
| Inflammation | 1 week |
| BMPs cause angiogenesis and are osteoinductive | |
| PMN’s attract macrophages, fibroblasts, and osteoclasts | |
| Macrophages phagocytose necrotic bone and debris | |
| Osteoclasts resorb bone ends | |
| Fibroblasts lay down granulation tissue (type 3 collagen) | |
| Inter-fragmentary strain reduced to 15% | |
| Soft Callus | 1-4 weeks |
| Chondroblasts proliferate and lay down Type 2 cartilage | |
| Forms bridging endosteal callus | |
| Strain further reduced to 2-5% | |
| Hard Callus | 4-16 weeks |
| Chondroclasts resorb cartilage | |
| Osteoblasts lay down type 1 collagen | |
| At endosteal surface replacing cartilage (endochondral) | |
| At periosteal surface (intra-membranous) | |
| Collagen mineralized to form woven bone (hard callus) | |
| Fracture stable | |
| Strain <1% | |
| Remodeling | Years |
| Woven bone remodeled according to Wolff’s Law to give stress-oriented mature lamellar bone |
| Component | Amount | Features | ||
| Cells | Chondrocytes | 2% | Maintain and produce Matrix | |
| Extracellular Matrix | Water | 80% wet weight | Permits deformation and nutrition by movement in and out of cartilage | |
| Collagen | 70% 90% type 2 10% 6, 10, 11 |
Responsible for tensile strength 6 – binds chondrocytes to matrix – calcified zone – Acts as a binder of the lattice |
||
| Proteoglycans | 20% | Responsible for tensile strength Negatively charged therefore attract water |
||
Other Proteins |
10% | Matrix Mettaloproteinases Elastin Glycoproteins |
| Parameter | Ageing | OA |
| Water content | Decreases | Increases |
| Synthetic activity | Decreases | Increases |
| Collagen content | Decreases | Decreases (concentration increases) |
| Proteoglycan content | Decreases | Decreases |
| Chondrocyte Size | Increases | |
| Chondrocyte number | Decreases | |
| Chondroitin: Keratin ratio | Decreases | Increases |
| Stiffness (young’s) | Increases | Decreases (high water content) |
| 1. 3 or more joints swollen for >6 weeks |
| 2. Morning Stiffness for 1 hour per day for >6 weeks |
| 3. Hand or Wrist involvement for >6 weeks |
| 4. Symmetric polyarthropathy |
| 5. Rheumatoid nodules |
| 6. Rheumatoid factor positive |
| 7. Radiographic features typical of RA |
| Region | Changes |
|---|---|
| Proximal | Axon atrophies but doesn’t die |
| Cell body changes | |
| Migrates to periphery of cell | |
| Starts producing regenerative proteins | |
| Cell volume Increases | |
| Chromatolysis – degeneration of Nissl bodies | |
| Distal | Wallerian degeneration occurs |
| De-myelination | |
| Axon is phagocytosed | |
| Endoneurium collapses but intact (unless neurotmesis) | |
| Schwann cells proliferate | |
| Proximal axon forms growth cones – sprouts on each fibre | |
| Schwann cells form columns (bands of bunger) - direct re-growth | |
| Motor End Plate | <3 months: More end plates are generated – seek out nerve supply |
| 3-6 months: Begins to degenerate | |
| 12-18 months: Muscle spindles and sensory organs regenerate | |
| End plate dies: Unable to be re-innervated |
| Stage | Features |
|---|---|
| Stage 1 | Mechanical disruption of the collagen network |
| Increased water content | |
| Stage 2 | Alters balance of cartilage metabolism – catabolic processes dominate |
| Products of catabolism are released into synovial fluid | |
| (Chondroitin & keratan sulphate, collagen & PGs fragments) | |
| Stage 3 | Incites an inflammatory response |
| PMNs, Macrophages, IL-1 and MMPs accumulate | |
| Stage 4 | These mediators degrade the cartilage matrix, disrupt collagen further and alter chondrocyte function |
| Stage 5 | Histology shows Fibrillated, eburnated, sclerotic shiny cartilage with loss of chondrocytes, collagen and PGs |