MSK growth injury & repair - ligament, tendons and bone

what are ligaments

dense bands of collagen that span a joint

Anchored to the bone at either end

Joint stability through range motion

Different portions ligament tensioned at different joint positions

what is the function of ligaments

provide stability and connect bone to bone

what type of collagen fibres do ligaments have

type 1

what are found within ligaments - why

fibroblasts - communication

sensory fibres for proprioception, stretch and sensory

Vessels (surface)

Crimping - allow stretch

why are ligaments different to tendons

lower % collagen

higher % proteoglycans and water

less organised collagen fibres

rounder fibroblasts

what is the most commonly injured ligament

ACL

lateral ligament in ankle

when does a ligament rupture

force exceeds strength of ligament

• Expected

• Unexpected (position/muscle)

• Rate load

Complete vs incomplete

Stability of joint affected

Proprioception loss

how does ligament healing occur

haemorrhage

proliferative phase

remodelling

haemorrhage in ligament rupture

blood clot

resorbed

replaced with heavy cellular filtrate

hypertrophic vascular response

proliferative phase of ligament rupture

production of scar tissue

disorganised collagenous connective tissue

remodelling phase of ligament rupture

matrix becomes ligament life

differences in composition, architecture and function

when is conservative/non-operative treatment used for ligament injuries

partial rupture

no instability

poor surgery candidate

when are ligament injuries operated on

joint instability

expectation/functional demands e.g. athlete

compulsory - multiple ruptures

what is the function of tendons

Connect muscle to bone

allow flexibility

how are tendons arranged structurally

longitudinal arrangement of cells (tenocytes) and type 1 triple helix collagen fibres

- collagen = fascicles of long narrowing bundles

- collagen covered by endotenon

- fascicles covered by paratenon

- tendon covered by epitenon

blood supply to tendons

vinculim - fine network of blood vessels in paratenon

what are tendon sheaths

elongated bursa that wraps around a tendon

- thickenings form strong pulleys

what does immobility cause in tendons

reduced water content and glycosaminoglycan concentration and strength

types of tendon injuries

degeneration

inflammation

esenthesiopathy

traction apophysitis

avulsion +/- bone fragment

tear - intra substance = rupture

tear at musculotendinous junction

laceration/incision

crush

ischaemic

nodules

most commonly degenerated tendon

achilles

intrasubstance mucoid degeneration

achilles tendon degeneration symptoms

could be asymptomatic

swollen painful tender tendon

potential precursor to rupture

inflammation of tendon

tendonitis

what is de Quervain's tenovsynovitis + symptoms

tendons of extensor pollicis brevis and abductor pollicis longus through common tendon sheath at radial aspect of wrist

- swollen tender hot red joint

- positive Finklesteins test

what is ethesiopathy

inflammation at bone insertions

- muscle/tendon usually at muscle origin rather than tendon insertion e.g tennis elbow

- ligament - plantar fasciitis

example of traction apophysitis

Osgood Schlatter disease

what is Osgood Schlatter disease

Rupture of the growth plate at the tibial tuberosity from stress on patellar tendon - common in adolescent active boys

recurrent load, inflammation

what is avulsion +/- bone fragment

failure at insertion with load exceeding strength while muscle is contracting

- mallet finger is common

treatment of avulsion +/- bone fragment

conservative

stack splint - limited application due to retraction tendon

operative

- reattachment of tendon through bone

- fixation of bony fragment

mechanisms of tendon rupture

intrasubstance rupture

pushing off with weight bearing forefoot while extending knee joint e.g. sprint starts or jumping

unexpected dorsiflexion of ankle - slipping into hole

violent dorsiflexion of plantarflexed foot - fall from height

achilles tendon rupture test findings

positive Simmonds test

palpable tender gap

absent/limited active plantar flexion

what is musculotendinous junction tear

junction between muscles tendon tears often partial tear

•E.g. tear at the junction between the medial head of gastrocnemius and the Achilles tendon

when would you do non operative vs operative treatment in intrasubstance tendon rupture

conservative

- where ends can be opposed - mobilise, splint/cast

- where healing will occur - not intra-articular tendons

operative

- when high risk of re-rupture

- high functional demand patient

- ends cannot be opposed

common tendons that are lacerated and treatment of this

finger flexors - FDS, FDP

early surgical repair

long bone anatomy

diaphysis - shaft

epiphysis - on joint side of physis

metaphysis - flare at end of shaft

physis - growth plate

medullary canal

apophysis

where tendons/ligaments attach

what is a fracture

break in the structural continuity of bone

types of bone

cortical - diaphysis, less biologically active

cancellous - metaphysis, site of longitudinal growth at the physis, very biologically active

why do bones fail

high energy transfer in normal bones

repetitive stress in normal bones - stress fracture

low energy transfer in abnormal bones - osteoporosis, osteomalacia, metastatic tumour other bone disorders

fracture biology

•Mechanical and structural failure of bone

•Disruption of blood supply

•Regenerative process

•No scar

Four stages

what are the 4 stages of fracture healing

inflammation

soft callus

hard callus

bone remodelling

inflammation stage 1 of fracture healing

begins immediately

- haematoma and fibrin clot

- platelets, PMN's, neutrophils, monocytes and macrophages

- by-products of cell death - lysosomal enzymes

- fibroblasts

- mesenchyymal and osteprogenitor cells - transformed endothelial cells, osteogenic induction of cells from muscle and soft tissues

- angiogenesis - macrophages

factors affecting stage 1 of fracture healing - inflammation

NSAIDs

Loss of fracture haematoma

•Open fractures

•Surgery

Extensive soft tissue damage

•Leads to poor blood supply

soft callus stage 2 of fracture healing

begins when pain and swelling subsides

lasts until bony fragments are united by cartilage or fibrous tissue

some stability of fracture

angulation can still occur

continued increase in vascularity

stage 3 hard callus of fracture healing

conversion of cartilage to woven bone

typically long bone fracture

increased rigidity - obvious callus on imaging

bone remodelling stage 4 of fracture healing

conversion of woven bone to lamellar bone

medullary canal reconstituted

bone responds to loading characteristics - Wolffs law

delayed union vs non union

delayed union = failure to heal in expected time

non union = failure to heal

what cases delayed union

high energy injury

distraction - increased osteogenic jumping

instability

infection

steroids

immunosuppressant

NSAIDs

warfarin

ciprofloxacin

smoking

what causes non-union

failure of calcification fibrocartilage

instability - excessive osteoclasts

abundant callus formation

pain + tenderness

persistent fracture line

sclerosis

if there is delayed bone healing what do you need to do

consider alternative management

- different fixation

- dynamisation

- bone graft