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Overuse injury, tendinopathy and regenerative therapy

Bone stress injury, tennis elbow and platelet-rich plasma for degenerative tendinopathy.

19 questions 3 source pages 1 fact-check flags

Images appear with the first question taken from each source page — tap a question to open it.

19 questions
Q1Define a stress fracture.▸
  • A fracture occurring at a stress below the ultimate tensile strength
Q2What is the difference between a fatigue and an insufficiency fracture?▸
  • Fatigue: repetitive stress under ultimate tensile strength and above endurance limit; normal bone; overuse history, insidious onset, prodromal pain, local tenderness/swelling
  • Insufficiency: normal stress, abnormal bone; sudden pain with no prodromal symptoms
Q3What is the pathogenesis of a stress fracture?▸
  • 1. Bone formation < bone resorption
  • 2. Decrease in ultimate tensile strength with time
  • 3. Microfracture, crack initiation and crack propagation
Q4What do X-ray, bone scan and MRI show in a stress fracture?▸
  • X-ray normal in the initial 2-3 weeks; later lucent line with sclerotic edges and periosteal reaction
  • Bone scan sensitive but not specific
  • Acute: linear increase in uptake in all 3 phases; healing: normalises sequentially phases 1-3; soft tissue: only phases 1 and 2
  • MRI: STIR sequence
Q5What are the high-risk sites for stress fractures?▸
  • Tibial anterior cortex
  • NOF (superolateral), medial malleolus, talus
  • 2nd and 5th metatarsals, patella
  • Hallux sesamoids
Q6What are the sport-specific stress fractures?▸
  • Runner: tibial shaft, NOF, 2nd metatarsal
  • Basketball: 5th metatarsal, navicular
  • Football: metatarsals, hallux sesamoids
Q7What is the Arendt grading and when is operative treatment indicated?▸
  • Grading by Arendt (X-ray, bone scan, MRI)
  • High grade, high risk -> operative treatment
Q8What is lateral epicondylitis and what is the pathoanatomy?▸
  • Overuse injury from eccentric overload at the common extensor origin
  • Microtear begins at the ECRB origin
  • Histology: angiofibroblastic hyperplasia, disorganized collagen (degenerative process)
Q9What is the differential diagnosis of tennis elbow?▸
  • Cervical radiculopathy
  • Radiocapitellar OA
  • Radial tunnel syndrome
  • PLRI of the elbow
Q10What are the physical examination findings in tennis elbow?▸
  • Tenderness at the ECRB origin
  • Decreased grip strength (in entrapment syndromes)
  • Resisted wrist extension with elbow extended; resisted extension of long fingers
  • Maximum wrist flexion -> pain; passive wrist flexion in pronation -> pain
Q11What conservative and operative treatment is used for tennis elbow?▸
  • Conservative: NSAIDs, physiotherapy, shockwave, brace worn 3-4cm distal to the common extensor origin, steroid/PRP injection
  • Operative: release and debridement of ECRB origin
  • Lift ERCL off ECRB (located deep and posterior to ECRL); excise degenerative tissue; decorticate epicondyle; repair capsule if breached; Side to side closure of the tendon
Q12How does the tennis elbow brace work?▸
  • Inhibits the traction force by extensors on the common extensor origin
  • Inhibits full expansion of the muscle belly
  • Worn 3-4cm distal to the common extensor origin
Q13What is the evidence for PRP versus corticosteroid in tennis elbow?▸
  • PM R 2020 Tang et al meta-analysis: PRP better long-term pain and function; corticosteroid most improvement short term
  • Latest Cochrane review 2021 does not support PRP: no evidence of benefit
Q14What is PRP and how is it prepared?▸
  • Plasma from one's own blood enriched with autologous platelets
  • Centrifugation separates the platelet-rich layer from whole blood; calcium chloride used to initiate platelet activation
  • Spin twice: 3200RPM for 15minutes then 2 minutes at 2000RPM with calcium chloride
  • 3 layers: lowest blood cells, middle PRP, top platelet-poor plasma
Q15What is the optimal platelet concentration in PRP?▸
  • 3-5x of whole blood
  • >5x will inhibit healing
Q16What are the indications for PRP in orthopaedics?▸
  • Controversial use for possible stimulation of bone and soft tissue healing
Q17What growth factors do platelets release and what is their proposed role?▸
  • PDGF, TGF-beta, VEGF, IGF-1, EGF, CTGF, FGF-2
  • Important role in the inflammatory cascade response after injury
  • Proposed: increase ECM deposition, Reduced pro-apoptotic signals, minimise joint inflammation
Q18What is the clinical evidence for PRP in soft tissue healing, OA and fracture healing?▸
  • Soft tissue healing: no consensus for acute ligament, tendon or muscle injuries or chronic tendinopathies
  • OA: RESTORE trial (JAMA 2021) and PEAK trial (BJJ 2022) showed no difference vs saline
  • Fracture healing/fusion: limited evidence for bone formation
Q19What is the evidence for PRP in ACL reconstruction, meniscal repair, cuff repair and tendinopathy?▸
  • ACL: does not support ligamentisation/graft maturation; may improve donor site outcomes and decrease patellar tendon gap
  • Meniscal repair: no clear evidence; rotator cuff repair: no benefit
  • Lateral epicondylitis: Cochrane review 2021 - no benefit; midsubstance Achilles: not supported
  • Patellar tendinopathy: AJSM 2016 Laprade group PRP vs saline, no difference

Fact check

Optimal PRP concentration is 3-5x whole blood and >5x will inhibit healing — Oversimplified: the exact inhibitory threshold is not established — Reviews commonly cite 3-4x (600,000-900,000/µL) as optimal and >1.2 million/µL unfavourable; in vitro studies show a plateau with reduced collagen synthesis at high concentrations — (medium confidence) — source
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