Osteoblasts – synthesize nonmineralized bone cortex

  Osteoclasts – reabsorb bone

•  Stages of bone healing – 1) inflammation, 2) soft callus formation, 3) mineralization of the callus, 4) remodeling of the callus

  Cartilage receives nutrients from synovial fluid (osmotic)

  Salter-Harris fractures III, IV, and V – cross the epiphyseal plate and can affect the growth plate of the bone; need open reduction and internal fixation (ORIF)

  Salter-Harris fractures I and II – closed reduction

  Fractures associated with avascular necrosis (AVN) – scaphoid, femoral neck, talus

  Fractures associated with nonunion – clavicle, 5th metatarsal fracture (Jones’ fracture)

  Fractures associated with compartment syndrome – supracondylar humerus, tibia

  Biggest risk factor for nonunion – smoking

LOWER EXTREMITY NERVES

  Obturator nerve – hip adduction

  Superior gluteal nerve – hip abduction

  Inferior gluteal nerve – hip extension

  Femoral nerve – knee extension

LUMBAR DISC HERNIATION

  Presents with back pain, sciatica

  Herniated nucleus pulposus

  Nerve root compression affects 1 nerve root below disc:

•  L3 nerve compression (L2–3 disc) – weak hip flexion

•  L4 nerve compression (L3–4 disc) – weak knee extension (quadriceps), weak patellar reflex

•  L5 nerve compression (L4–5 disc) – weak dorsiflexion (foot drop)

•  ↓ sensation in big toe web space

•  S1 nerve compression (L5–S1 disc) – weak plantar flexion, weak Achilles reflex

•  ↓ sensation in lateral foot

  Dx: patients with neurologic findings need MRI

  Tx: NSAIDs, heat, and rest; surgery for substantial/progressive neurologic deficit, refractory cases, severe sciatica, or disc fragments that have herniated into the cord

TERMINAL BRANCHES OF BRACHIAL PLEXUS

  Ulnar nerve

•  Motor – intrinsic musculature of hand (palmar interossei, palmaris brevis, adductor pollicis, and hypothenar eminence); finger abduction (spread fingers); wrist flexion

•  Sensory – all of 5th and ½ 4th fingers, back of hand

•  Injury results in claw hand

  Median nerve

•  Motor – thumb apposition (anterior interosseous muscle, OK sign); finger flexors

•  Sensory – most of palm and 1st 3 and ½ 4th fingers on palmar side

•  Nerve is involved in carpal tunnel syndrome

  Radial nerve

•  Motor – wrist extension, finger extension, thumb extension, and triceps; no hand muscles

•  Sensory – 1st 3 and ½ 4th fingers on dorsal side

  Axillary nerve – motor to deltoid (abduction)

  Musculocutaneous nerve – motor to biceps, brachialis, and coracobrachialis

CERVICAL RADICULOPATHY

  C1, C2, C3, and C4 nerve compression (C1–2, C2–3, C3–4 discs) – neck and scalp pain

  C5 nerve compression (C4–5 disc) – weak deltoid and biceps

•  Weak biceps reflex

  C6 nerve compression (C5–6 disc) – weak deltoid and biceps, weak wrist extensors

•  Weak biceps reflex and brachioradialis reflex

  C7 nerve compression (most common, C6–7 disc) – weak triceps

•  Weak triceps reflex

  C8 nerve compression (C7–T1 disc) – weak triceps, weak intrinsic muscles of hand and wrist flexion

•  Weak triceps reflex

  Radial nerve – C5–C8

  Median nerve – C6–T1

  Ulnar nerve – C8–T1

  Musculocutaneous nerve – C5–C7

  Axillary nerve – C5–C6

  Radial nerve roots – on the superior portion of the brachial plexus

  Ulnar nerve roots – on the inferior portion of the brachial plexus

UPPER EXTREMITY

  Clavicle fracture – usually just treated with sling (risk of vascular impingement)

  Shoulder dislocation

•  Anterior (90%) risk of axillary nerve injury. Tx: closed reduction

•  Posterior (seizures, electrocution) risk of axillary artery injury. Tx: closed reduction

  Acromioclavicular separation – Tx: sling (risk of brachial plexus and subclavian vessel injury)

  Scapula fracture

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