Stress or load: Force over area (has units of Newton per square metre) Strain or deformation: Change in length over original length caused by applied stress or load (unitless and expressed as ratio or percentage) Mnemonic: If your boss is under a lot of stress, his personality changes (strain) A….
Tag: Orthopedics
Section Editor: Dr. Sulabh Kumar Shrestha, MBBS, PGY1 Orthopedics
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Motor March Phenomenon
Motor march phenomenon is a sign of reinnervation like Hoffman-Tinel’s sign which has been discussed earlier. Observed in: Axonotmesis Repaired Neurotmesis Not observed in: Neuropraxia Motor march phenomenon: As the re-innervation of injured nerve proceeds, the muscles nearest to the site of injury recovers first followed by distal ones sequentially…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Perkin’s Timetable for Fracture Healing
One needs to understand the difference between bone union and consolidation first Union Consolidation Definition Partial/Incomplete repair Full/Complete repair Callus Calcified Ossified Attempted angulation Painful Painless Fracture line in X-ray Still visible Obliterated and crossed by bony trabeculae Full weight bearing Cannot be undertaken Can be undertaken Reference: Physiotherapy in…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
AO fracture classification made easy
It is an alpha-numeric system of classification developed by Muller and colleagues. Step 1: 1st digit specifies bone Step 2: 2nd digit specifies segment of bone Square definition: Proximal and distal segments are defined by a square whose sides = length of widest part of epiphysis Exceptions of square definition:…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Osteochondroma : Mnemonics
Features of Osteochondroma Mnemonic: Six “C” Commonest benign bone tumor Continue to grow until Closure of physis Cartilage cap (appears larger clinically than in X-ray) Continuous with native bone (cortex and medullary canal) Cane (pedunculated/stalked points away from joint and sessile/broad based have higher risk of malignant degeneration) Change (mutation)…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Palmar Aponeurosis or Fascia
5 components a. Central aponeurosis It is triangular in shape with apex originating at the level of flexor retinaculum as a continuation of palmaris longus and thins and fans out distally. It has 3 dimensional fiber orientation: longitudinal, transverse and vertical 1. Longitudinal: Gives 4 pre-tendinous band (PTB) in the…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Rheumatoid hand
Ulnar drift or deviation of fingers Normal anatomical factors contributing to ulnar drift of fingers at MCP joint: Normal mechanical advantage of ulnar intrinsic muscles Asymmetry and ulnar slope of metacarpal heads of index and middle fingers Greater ulnar deviation permitted by radial collateral ligament when MCP joint is flexed…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Gout : Mnemonics
Urate Lowering Therapy (ULT) Mnemonic: 1, 2, 3, 4, 5, 6 Start Urate Lowering Therapy if: ≥1 subcutaneous tophi ≥2 flares per year ≥3 stage CKD with Serum uric acid (SUA) ≥ 9 mg/dl Other indications: Urate renal stone, Evidence of joint destruction in X-ray 4. ≥4 weeks to be…