01Approach to the Critical Patient/attcp38

Triage and limb threat

›Immediate priorities

›Hemodynamic instability as separate diagnosis

›Open knee wound as potential open extensor mechanism injury

›Rapidly expanding thigh hematoma as major bleeding concern

›Inability to actively extend knee as functional limb threat

›Immediate immobilization

›Knee immobilizer locked in extension

›Crutches

›Non weight bearing until ortho plan

›Neurovascular status

›Distal pulses DP

›Distal pulses PT

›Capillary refill

›Sensation superficial peroneal

›Sensation deep peroneal

›Sensation tibial

›Motor ankle dorsiflexion

›Motor ankle plantarflexion

›Escalation triggers

›If open injury near patella or tendon gap then urgent ortho and antibiotics pathway

›If suspected knee dislocation then immediate vascular evaluation pathway

›If compartment syndrome concern then emergent ortho and fasciotomy pathway

Key concepts

›Extensor mechanism failure

›Quadriceps tendon disruption prevents active knee extension

›Classic triad pain

›Classic triad suprapatellar gap

02History/hx37

Mechanism and timeline

›Injury context

›Eccentric quadriceps contraction with knee flexed

›Fall with forced knee flexion

›Direct blow to anterior thigh

›Low energy mechanism in older patient

›Time course

›Time from injury

›Progressive swelling

›Audible pop

›Immediate loss of extension

›Functional impact

›Inability to straight leg raise

›Inability to climb stairs

›Inability to stand from chair

›Knee buckling episodes

Risk factors for tendon failure

›Systemic risks

›Diabetes mellitus :contentReference[oaicite:1]{index=1}

›Chronic kidney disease

›Hyperparathyroidism

›Gout :contentReference[oaicite:2]{index=2}

›Rheumatoid arthritis

›Medication risks

›Systemic corticosteroids :contentReference[oaicite:3]{index=3}

›Fluoroquinolone exposure

›Anabolic steroid use

›Local risks

03Physical Exam/exam46

Core extensor mechanism exam

›Inspection

›Suprapatellar swelling

›Ecchymosis anterior thigh

›Patella position low riding patella as supportive sign :contentReference[oaicite:4]{index=4}

›Palpation

›Palpable gap proximal to patella :contentReference[oaicite:5]{index=5}

›Tenderness at superior pole patella

›Quadriceps tendon contour loss

›Active function

›Straight leg raise ability

›Active knee extension against gravity

›Active knee extension against resistance

›Passive motion

›Passive knee flexion range

›Effusion degree

›Focused special tests

›Patellar mobility and tracking

›Fixed patella test if available in local practice :contentReference[oaicite:6]{index=6}

Regional and associated injuries

›Knee stability screen

›ACL laxity concern

›PCL laxity concern

›MCL tenderness

›LCL tenderness

›Joint above and below

›Hip pain and ROM

›Ankle pain and ROM

04Differential Diagnosis/ddx20

Extensor mechanism and knee trauma differentials

›Extensor mechanism injuries

›Patellar tendon rupture ICD-10 S76.10 series

›Patella fracture ICD-10 S82.0 series

›Quadriceps muscle tear ICD-10 S76.1 series

›Intraarticular knee injuries

›ACL tear ICD-10 S83.51 series

›PCL tear ICD-10 S83.52 series

›Meniscal tear ICD-10 S83.2 series

›Osteochondral fracture ICD-10 S82.0 and M93.2 context

›Major associated trauma

›Knee dislocation ICD-10 S83.10 series

›Tibial plateau fracture ICD-10 S82.14 series

›Distal femur fracture ICD-10 S72.4 series

Mimics and alternative diagnoses

›Pain with preserved extension

›Prepatellar bursitis ICD-10 M70.4

›Quadriceps contusion ICD-10 S70.1

›Septic arthritis ICD-10 M00.9

›Spontaneous rupture contexts

›Spontaneous tendon rupture ICD-10 M66.2

›Systemic inflammatory disease flare

05Laboratory Tests/lt26

When labs are needed

›Perioperative and bleeding context

›CBC for anemia or major hematoma

›Hemoglobin trend if large swelling or anticoagulated

›Platelets for procedural planning

›INR if warfarin use

›INR target per local surgical pathway

›Reversal planning trigger if urgent OR

›Creatinine for DOAC context

›Renal function affects anticoagulant clearance

›Contrast planning if CT angiography needed for dislocation concern

›Infection concern

›CRP if septic arthritis differential

›Elevated CRP non specific

›Normal CRP does not exclude early infection

›WBC count if systemic symptoms

›Leukocytosis non specific

›Normal WBC does not exclude infection

›Rhabdomyolysis and crush context

›CK if prolonged entrapment or massive thigh trauma

›Rising CK supports muscle injury burden

›CK does not diagnose tendon rupture

›Potassium if crush injury

›Hyperkalemia escalation trigger

PITFALLS

›Limitations

›Labs do not confirm tendon rupture

›Normal labs do not exclude surgical need

06Diagnostic Tests/dt48

Scoring Systems

›Classification and decision framing

›Tear completeness

›Partial tear

›Preserved active extension possible

›Often nonoperative pathway if low grade

›Complete tear

›Loss of active knee extension

›Operative pathway typical :contentReference[oaicite:7]{index=7}

›Location description

›Osteotendinous junction

›Midsubstance tendon

›Patellar insertion

›Evidence gaps

›No widely validated ED scoring system for quadriceps tendon rupture

›Postoperative rehab protocols vary with limited comparative evidence :contentReference[oaicite:8]{index=8}

Radiographs

›Plain radiography role

›Knee radiographs for avulsion fracture and patella position :contentReference[oaicite:9]{index=9}

›Suggested views

›AP knee

›Lateral knee

›Sunrise or merchant view if patellar injury concern

›Supportive signs

›Patella baja supportive of quadriceps tendon rupture :contentReference[oaicite:10]{index=10}

›Suprapatellar soft tissue swelling

›Superior pole patella avulsion fragment

›Limitations

07Disposition/dispo25

Ortho involvement and timing

›Urgent referral criteria

›Suspected complete rupture

›Loss of active knee extension

›Palpable tendon gap

›Open injury over extensor mechanism

›Timing concepts

›Early repair preferred for complete rupture

›Commonly cited window 48 to 72 hours for best technical conditions :contentReference[oaicite:12]{index=12}

Admit vs discharge

›Admission criteria

›Uncontrolled pain despite ED regimen

›Unable to mobilize safely with aids

›Social barriers to urgent follow up

›Anticoagulation with large hematoma and monitoring need

›Open injury requiring operative management

›Discharge criteria

›Hemodynamically stable

›Pain controlled with oral plan

›Knee immobilizer locked in extension

›Safe crutch use

›Ortho follow up arranged within 24 to 72 hours

Transfer criteria

›Higher level care triggers

›Open extensor mechanism injury

›Suspected knee dislocation with vascular concern

›Compartment syndrome concern

›Polytrauma needing trauma service

08Treatment/t74

Immediate life-saving interventions

›Immediate stabilization

›If hemorrhagic shock then trauma resuscitation pathway

›If open wound then open injury pathway

›If vascular compromise then emergent vascular and ortho escalation

›Analgesia early

›Acetaminophen PO 1000 mg

›Maximum 4000 mg per day

›Maximum 3000 mg per day if chronic alcohol use or liver disease risk

›Ibuprofen PO 400 mg

›Every 6 hours as needed

›Avoid in high GI bleed risk or significant renal dysfunction

›Naproxen PO 500 mg

›Then 250 mg every 6 to 8 hours as needed

›Avoid in high GI bleed risk or significant renal dysfunction

›Hydromorphone PO 1 mg

›Every 4 to 6 hours as needed for severe pain

›Older adult start 0.5 mg if frailty or opioid naive

›If severe pain then hydromorphone IV 0.2 mg

›Repeat every 10 to 15 minutes to effect

›Respiratory monitoring and sedation scale

Immobilization and Splinting

›Immobilization selection

›Knee immobilizer

›Locked in full extension

›Worn continuously except hygiene if approved by ortho

›Hinged knee brace

›Locked in extension initially if provided

›ROM progression per ortho protocol

›Key principles

›Extension positioning reduces tendon gap

›Avoid active knee extension against resistance

›Ice and elevation for swelling control

›Post immobilization checks

›Pain trend

›Skin pressure points

›Distal neurovascular reassessment

Reduction

›Not typically applicable

›No fracture reduction target in isolated tendon rupture

›If associated patellar dislocation then standard reduction pathway

Open fracture medications and timing

›Open extensor mechanism laceration pathway

›If tendon exposed then treat as open joint or open extensor mechanism injury until proven otherwise

›Cefazolin IV 2 g

›Every 8 hours while awaiting operative plan

›If weight 120 kg or more then 3 g per dose per local protocol

›If severe beta lactam allergy then clindamycin IV 900 mg

›Every 8 hours

›MRSA risk add vancomycin per local protocol

›Tetanus prophylaxis per immunization status

›Tdap if incomplete or unknown

›TIG if high risk wound and incomplete series

DVT prophylaxis when relevant

›Risk assessment for lower limb immobilization

›Surgery planned

›Pharmacologic prophylaxis per ortho protocol

›Mechanical prophylaxis if anticoagulation contraindicated

›Nonoperative immobilization

›Individual risk assessment prior VTE

›Individual risk assessment active cancer

›Individual risk assessment thrombophilia

›Contraindications

›Active bleeding

›High fall risk with anticoagulation

›Evidence note

›Prophylaxis approach varies by jurisdiction and local protocol

Definitive management overview

›Operative management typical for complete rupture

›Early repair recommended in many reviews :contentReference[oaicite:13]{index=13}

›Technique options transosseous tunnels

›Patellar bone tunnels

›Nonabsorbable sutures

›Postop brace locked extension initially

›Technique options suture anchors :contentReference[oaicite:14]{index=14}

›Anchor fixation to patella

›Comparable functional restoration reported

›Nonoperative management options for selected partial tears

›Extension immobilization

›Early protected rehab per specialist plan

09Special Populations/sp30

Pregnancy

›Pregnancy considerations

›Analgesia selection

›Acetaminophen preferred first line

›NSAIDs avoid in third trimester

›Opioids short course only if required

›Imaging considerations

›Radiographs acceptable with shielding when clinically needed

›MRI without gadolinium preferred when advanced imaging needed

›VTE risk

›Pregnancy hypercoagulable state increases immobilization risk

›Prophylaxis decisions coordinate with obstetrics and ortho

Geriatric

›Higher risk features

›Low energy rupture with systemic tendon degeneration :contentReference[oaicite:15]{index=15}

›Higher fall risk with crutches

›Delirium risk with opioids

›Disposition thresholds

›Lower threshold for admission if unsafe mobility

›Early PT and mobility aids planning

›Medication adjustments

›Opioid start low and slow

›NSAID renal and GI risk higher

Pediatrics

›Rarity and alternatives

›Quadriceps tendon rupture uncommon

›Consider sleeve fracture of patella

›Consider physeal injury

10Background/b18

Epidemiology

›Typical demographics

›More common in males over 40 years :contentReference[oaicite:16]{index=16}

›Association with systemic disease and tendon degeneration :contentReference[oaicite:17]{index=17}

›Clinical impact

›Missed diagnosis leads to delayed repair and worse functional recovery :contentReference[oaicite:18]{index=18}

Pathophysiology

›Tendon failure mechanism

›Degenerative tendon changes reduce tensile strength

›Eccentric loading during sudden knee flexion precipitates rupture

›Complete rupture disrupts extensor mechanism

›Anatomy notes

›Quadriceps tendon described with multiple layers important for tear pattern :contentReference[oaicite:19]{index=19}

Therapeutic Considerations

›Treatment rationale

›Complete rupture usually requires repair to restore active extension :contentReference[oaicite:20]{index=20}

›Early repair reduces retraction and improves technical success :contentReference[oaicite:21]{index=21}

›Partial tears may succeed with immobilization and rehab in selected cases

›Rehabilitation expectations

›Recovery often months with structured rehab :contentReference[oaicite:22]{index=22}

›Protocol variability and limited comparative evidence :contentReference[oaicite:23]{index=23}

11Patient Discharge Instructions/pdi24

copy discharge instructions

›Discharge plan

›Knee immobilizer locked in extension at all times

›Crutches

›Non weight bearing until ortho review

›Elevation above heart when resting

›Ice 15 to 20 minutes every 2 to 3 hours for 48 hours

›Keep brace dry and intact

›Pain plan

›Acetaminophen as directed on label

›NSAID only if safe for you

›Opioid only if prescribed

›No driving while taking opioids

›Follow up

›Orthopedics within 24 to 72 hours

›Return earlier if unable to arrange follow up

›Return to ED now if

›New numbness or tingling in foot

›Foot pale or cold

›Severe increasing pain despite medications

›Brace too tight with worsening swelling

›Fever or worsening redness

›Wound drainage if any cut near knee

›Chest pain or shortness of breath

›Calf swelling or calf pain

12References/r11

Clinical guidelines and core references

›Key sources

›AAOS OrthoInfo Quadriceps Tendon Tear patient education and recovery timelines :contentReference[oaicite:24]{index=24}

›StatPearls Quadriceps Tendon Rupture review including early repair timing :contentReference[oaicite:25]{index=25}

›ACEP Sports Medicine Tendon Injuries in the Emergency Department clinical overview :contentReference[oaicite:26]{index=26}

›Orthobullets Quadriceps Tendon Rupture summary and anatomy notes :contentReference[oaicite:27]{index=27}

›Survey of treatment trends and evidence gaps in postoperative rehab :contentReference[oaicite:28]{index=28}

Imaging and diagnostic evidence

›Imaging references

›Emergency and MSK ultrasound overview including quadriceps tendon rupture presentation :contentReference[oaicite:29]{index=29}

›RSNA review on ultrasound for acute tendon tears :contentReference[oaicite:30]{index=30}

›Fixed patella test clinical study for quadriceps tendon rupture detection :contentReference[oaicite:31]{index=31}

›Delayed diagnosis discussion and classic clinical findings :contentReference[oaicite:32]{index=32}

Evidence & Review

Evidence & Review