Patellar Tendon RuptureMANAGEMENT

MUSCULOSKELETAL AND RHEUMATOLOGIC PRESENTATIONS · 12 SECTIONS

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734 items

☷ Legend

01Approach to the Critical Patient/attcp36

Immediate priorities

›Extensor mechanism status

›Active knee extension against gravity

›Complete failure indicates complete rupture of extensor mechanism

›Partial lag may indicate partial tear or intact retinaculum

›Straight leg raise ability

›Inability to perform SLR is hallmark of complete rupture

›Test in supine position

›Palpable infrapatellar gap

›Pathognomonic for complete rupture

›Swelling may obscure gap early

Alarm features

›High-risk features requiring urgent orthopedic consultation

›Complete extensor mechanism failure

›Surgical repair is the only definitive treatment

›Delay beyond 2-3 weeks significantly worsens outcomes

›Bilateral rupture

›Strongly associated with systemic disease (SLE, CKD, corticosteroid use)

›Urgent systemic workup required

›Open wound over extensor mechanism

›Open extensor mechanism injury requires emergent operative management

›Antibiotics initiated immediately

›Neurovascular compromise of distal extremity

›Rare but must exclude vascular injury

›Compartment syndrome risk in high-energy mechanisms

Stabilization and consult triggers

›ED stabilization bundle

›Knee immobilizer in full extension applied immediately

›Long-leg posterior splint as alternative

›Non-weight-bearing with crutches

›Ice and elevation of affected limb

›Reduces swelling and pain

›Facilitates surgical planning

›Analgesia

›NSAIDs or acetaminophen for mild to moderate pain

›Opioids as needed for severe pain

›Orthopedic consultation for all complete ruptures

›Surgical timeline established in ED

›Early repair within days to 2-3 weeks is the standard of care

02History/hx81

Mechanism and onset

›Classic mechanism

›Violent eccentric quadriceps contraction against a flexed knee

›Jumping, landing, stumbling, or fall from height

›Stairs or missing a step

›Acute onset anterior knee pain

›Audible or felt "pop" or tearing sensation

›Immediate loss of function

›Timing and acuity

›Acute injury (hours to days)

›Delayed presentation worsens surgical outcomes

Functional history

›Immediate functional impairment

›Inability to walk or bear weight on affected leg

›Complete rupture typically renders patient non-weight-bearing

›Partial tears may permit limited ambulation

›Inability to straighten the knee

›Cannot actively extend from flexed position

›Cannot maintain extension against gravity

›Prior functional level

›Athletic activity level and sport

›Occupational demands

Risk factors and predisposing conditions

›Systemic disease history

›Systemic lupus erythematosus

›Strongly associated with bilateral patellar tendon rupture

›Tendon collagen weakening from disease and treatment

›Chronic kidney disease or dialysis

›Renal osteodystrophy weakens tendon-bone interface

›Dialysis patients at elevated risk

›Diabetes mellitus

›Microvascular changes impair tendon nutrition

›HbA1c as preoperative risk marker

›Rheumatoid arthritis

›Chronic inflammation weakens periarticular structures

›Hyperparathyroidism

›Altered calcium-phosphate metabolism affects bone and tendon

›Medication risk factors

›Corticosteroids (systemic or local injections)

›Weaken tendon collagen matrix

›Prior peritendinous or intra-articular injections

›Fluoroquinolone antibiotics (ciprofloxacin, levofloxacin)

›Associated with tendon degeneration and spontaneous rupture

›Risk persists weeks to months after course completion

›Anabolic steroids

›Disproportionate muscle-tendon strength imbalance

›Anastrozole

›Case reports of bilateral extensor mechanism rupture

›Local tendon history

›Chronic patellar tendinopathy ("jumper's knee")

›Rupture often represents end-stage degenerative tendinopathy

›Prior episodes of tendon pain

›Prior corticosteroid injections around the knee

›Prior knee surgery

›Patellar tendon autograft harvest for ACL reconstruction

›Weakens donor site tendon

Review of systems

›Musculoskeletal review

›Contralateral knee symptoms

›Bilateral rupture risk in systemic disease

›Prior knee pain or tendinopathy episodes

›Rheumatologic review

›Rash, oral ulcers, photosensitivity (SLE)

›Morning stiffness (RA)

›Joint swelling or synovitis history

›Systemic review

›Constitutional symptoms (fever, weight loss)

›Septic arthritis or underlying inflammatory disease

›Renal symptoms

›Edema, fatigue, dialysis dependence (CKD association)

Demographic and social history

›Patient demographics

›Age under 40 (peak incidence for traumatic rupture)

›Age 35-44 highest-risk bracket in military populations

›43% of cases occur in patients over 40

›Male sex

›91-98% of patellar tendon ruptures occur in males

›Overweight or obesity

›Mean BMI 28.7 kg/m2 in patellar tendon rupture cohorts

›BMI >25 associated with worse prognosis

›Black race

›Rate ratio 9.21 times higher vs White in military data

›Social and functional context

›Athletic goals and return-to-sport expectations

›Occupational demands and disability concerns

›Ability to comply with prolonged postoperative rehabilitation

03Physical Exam/exam64

Inspection and palpation

›Gross appearance

›Swelling and ecchymosis over anterior knee

›Hemarthrosis common with complete tears

›Swelling may obscure palpable gap

›Patella height

›Patella alta — visibly or palpably high-riding patella

›Compare to contralateral knee

›Skin integrity

›Open wound overlying tendon (open injury)

›Palpation findings

›Infrapatellar gap or defect in tendon substance

›Pathognomonic for complete rupture

›Found between inferior pole of patella and tibial tuberosity

›Tenderness localization

›Mid-substance tenderness (most common rupture site)

›Inferior pole of patella tenderness (avulsion pattern)

›Tibial tuberosity tenderness (insertion avulsion)

Functional testing

›Active extension testing

›Straight leg raise

›Inability to perform SLR is the single most important exam finding

›Test in supine with hip flexed to 30 degrees

›Active extension from flexed position

›Complete loss of active extension against gravity = complete rupture

›Extensor lag present in partial tears

›Extensor lag measurement

›Partial tears may show lag from a flexed position

›Quantify degrees of lag

›Retinacular assessment

›Medial and lateral retinaculum palpation

›Intact retinaculum may preserve some extension in complete rupture

›Masking effect leads to missed complete tear diagnoses

›Thompson squeeze test analogue

›Not validated for patella tendon; clinical extension loss is primary

Associated injury exam

›Hemarthrosis assessment

›Joint effusion palpation and ballottement

›Large effusion suggests intra-articular injury

›Aspiration not routinely needed in ED

›Ligamentous stability

›Lachman test

›ACL tear coexists in 18% of cases

›Anterior drawer test as adjunct

›Valgus and varus stress testing

›Collateral ligament integrity

›Meniscal examination

›Joint line tenderness

›Meniscal tear coexists in 18% of cases

›McMurray and Apley tests when tolerated

›Neurovascular exam

›Distal pulses (dorsalis pedis and posterior tibial)

›Compartment syndrome signs with high-energy mechanism

›Sensation and motor function below knee

PITFALLS

›Common diagnostic pitfalls

›Intact retinaculum masking complete tear

›Patient may retain some active extension with complete tear

›Palpable gap and patella alta are more reliable than extension testing alone

›Hemarthrosis obscuring palpable gap

›Tense effusion fills the infrapatellar space

›Do not exclude rupture based on absent palpable gap alone

›Partial tear with preserved extension

›May be misclassified as contusion or tendinopathy

›Ultrasound or MRI required to characterize partial tears

›Missing associated intra-articular injuries

›30% overall and 75% with high-energy mechanism have associated injuries

›Systematic ligament and meniscal exam required

04Differential Diagnosis/ddx51

Extensor mechanism injuries

›Quadriceps tendon rupture

›ICD-10 S76.112 (quadriceps tendon rupture)

›More common in patients over 40

›Palpable suprapatellar gap distinguishes from patellar tendon rupture

›Radiographic differentiation

›Patella baja (low-riding patella) on lateral view

›Opposite pattern to patellar tendon rupture (patella alta)

›Patellar fracture

›ICD-10 S82.0 (fracture of patella)

›Six times more common than patellar tendon rupture

›Bony tenderness and crepitus on palpation

›Plain radiograph identification

›Visible on AP and lateral knee views

›Transverse fracture common with extensor mechanism failure

›Tibial tubercle avulsion fracture

›ICD-10 S89.0 (physeal fracture tibial tubercle)

›Occurs in skeletally immature patients

›Pain and swelling centered at tibial tuberosity

›Compartment syndrome risk

›Anterior compartment at risk

›Tibial artery branches involved in some cases

›Patellar sleeve fracture

›Pediatric patients with open physes

›Cartilaginous avulsion may be radiographically occult

›MRI or ultrasound required to characterize

›Partial patellar tendon tear

›ICD-10 S76.112 (partial extensor mechanism injury)

›May retain active extension

›Diagnosis requires ultrasound or MRI confirmation

Associated and coexisting injuries

›Anterior cruciate ligament rupture

›ICD-10 S83.51 (ACL sprain/rupture)

›Coexists in 18% of patellar tendon ruptures

›Positive Lachman and anterior drawer tests

›Hemarthrosis common with ACL injury

›Meniscal tear

›ICD-10 S83.2 (meniscal tear)

›Coexists in 18% of patellar tendon ruptures

›Joint line tenderness and mechanical symptoms

›MRI required for definitive characterization

›Patellar dislocation and subluxation

›ICD-10 S83.0 (dislocation of patella)

›Lateral displacement and apprehension sign

›Medial retinacular tenderness distinguishes from tendon rupture

Other knee diagnoses

›Septic arthritis

›ICD-10 M00.069 (septic arthritis, knee)

›Fever and elevated inflammatory markers

›Joint aspiration for diagnosis

›Prepatellar bursitis

›ICD-10 M70.4 (prepatellar bursitis)

›Localized swelling over patella without extensor mechanism failure

›Active extension preserved

05Laboratory Tests/lt36

Routine trauma labs

›Standard injury assessment

›Complete blood count

›Preoperative baseline

›Leukocytosis if infection concern

›Basic metabolic panel

›Renal function for antibiotic dosing

›Electrolytes as surgical baseline

›Coagulation studies (PT/INR, aPTT)

›Preoperative requirement

›Anticoagulant use assessment

Systemic disease workup

›Indicated for bilateral rupture or atraumatic mechanism

›Renal function panel

›Creatinine and eGFR (CKD association)

›BUN for dialysis assessment

›Inflammatory markers

›ESR and CRP

›Elevated in SLE, RA, and inflammatory arthropathy

›Autoimmune panel

›ANA and anti-dsDNA (SLE screening)

›Complement levels (C3, C4) in SLE

›Calcium and phosphorus metabolism

›Calcium, phosphorus, PTH (hyperparathyroidism)

›Vitamin D level

›Endocrine panel

›HbA1c (diabetes mellitus)

›TSH (thyroid disease association)

›Uric acid

›Gout association (rare)

Perioperative labs

›Preoperative preparation

›Blood type and screen

›Surgical blood loss risk

›Urinalysis

›Infection exclusion before implant surgery

›ECG

›Cardiac risk assessment if age >50 or cardiac comorbidities

›Baseline before procedural sedation

06Diagnostic Tests/dt80

Scoring Systems

›Insall-Salvati ratio

›Measurement on lateral knee radiograph

›Patellar tendon length divided by patellar length

›Normal ratio is 0.8 to 1.2

›Threshold and performance

›Ratio >1.2 indicates patella alta

›Sensitivity 84%, specificity 79% for patellar tendon rupture

›Clinical application

›Compare to contralateral knee for greatest accuracy

›Single best radiographic sign of patellar tendon rupture

›Focal intratendinous radiolucency sign

›Newer radiographic diagnostic sign

›Lucency within tendon substance on lateral radiograph

›Sensitivity 82.5%, specificity 95.2%

›Interpretation

›High specificity makes it a useful confirmatory sign

›Can be subtle and easily missed on casual inspection

MRI

›MRI knee for extensor mechanism characterization

›Indications

›Equivocal clinical diagnosis

›Partial vs complete tear differentiation

›Associated intra-articular injury assessment (ACL, meniscus)

›Sequences and findings

›T1 and T2-weighted sagittal images primary planes

›Complete tear: tendon discontinuity with retraction

›Partial tear: focal tendon thickening with signal abnormality but continuity maintained

›MRI performance

›Gold standard for soft tissue characterization

›Superior to ultrasound for associated intra-articular pathology

›Associated findings on MRI

›ACL tear (coexisting in 18% of high-energy cases)

›Meniscal tear (coexisting in 18% of cases)

›Bone marrow edema at avulsion site

›Retinacular integrity assessment

›CT knee role

›Primary indications

›Complex patellar fracture characterization

›Avulsion fracture fragment assessment

›Preoperative planning for comminuted fractures

›CT performance for tendon injury

›Not the primary modality for soft tissue patellar tendon assessment

›Inferior to MRI and ultrasound for tendon characterization

›CT radiograph relationship

›Plain radiograph is the initial bony assessment

›CT reserved for complex bony injury or inconclusive plain films

›Protocol

›Helical CT without contrast for musculoskeletal assessment

›Coronal and sagittal reconstructions from axial source data

Ultrasound

›Musculoskeletal ultrasound of the patellar tendon

›Indications

›Point-of-care bedside diagnosis

›Dynamic evaluation of tendon during active extension

›Partial vs complete tear differentiation

›Technique

›High-frequency linear transducer (10-15 MHz) for optimal resolution

›Long-axis (sagittal) and short-axis (transverse) views

›Dynamic assessment with knee flexion and extension

›Ultrasound findings

›Complete tear: gap with retraction, loss of fibrillar echotexture

›Partial tear: focal hypoechoic defect within intact tendon

›Hematoma may fill gap (anechoic or hypoechoic collection)

›Ultrasound performance

›High sensitivity and specificity for complete tears

›Differentiates partial from complete tears accurately

›Real-time dynamic evaluation is a key advantage over MRI

›Limitations

›Operator-dependent

›Limited assessment of intra-articular structures

›Bone shadowing may limit visualization of bony avulsions

Plain Radiograph

›Bilateral lateral knee radiographs

›First-line imaging modality

›Standard initial assessment for all suspected ruptures

›Bilateral comparison for patellar height assessment

›Radiographic findings

›Patella alta (high-riding patella)

›Intratendinous radiolucency

›Avulsion fragments from inferior pole of patella or tibial tuberosity

›AP knee radiograph adjunct

›Patellar fracture exclusion

›Tibial tuberosity assessment

07Disposition/dispo41

Discharge from ED

›Criteria for ED discharge with outpatient orthopedic follow-up

›Isolated complete patellar tendon rupture without complications

›No open wound

›No vascular compromise

›No polytrauma

›Discharge requirements

›Knee immobilizer in full extension applied

›Non-weight-bearing with crutches

›Urgent orthopedic follow-up within 3-7 days arranged

›Partial tears with intact active extension

›Immobilization and close outpatient follow-up

›Orthopedic referral within 1 week

Admission criteria

›Indications for hospital admission

›Open extensor mechanism injury

›Emergent operative management required

›IV antibiotics initiated in ED

›Associated vascular injury

›Vascular surgery consultation

›Limb-threatening emergency

›Bilateral rupture

›Requires urgent bilateral repair

›Systemic workup initiated during admission

›Polytrauma

›Concurrent fractures or organ injuries

›Trauma team involvement

›Inability to safely mobilize

›Social circumstance or comorbidity preventing safe discharge

›Inpatient occupational therapy or physiotherapy initiation

Transfer criteria

›Transfer indications

›Orthopedic surgery not available at receiving facility

›Transfer to center with orthopedic capability

›Immobilize before transfer

›Vascular injury requiring specialist intervention

›Transfer with vascular surgery capability

Follow-up

›Outpatient follow-up expectations

›Urgent orthopedic appointment within 3-7 days

›Delay beyond 2-3 weeks from injury significantly worsens outcomes

›Surgical planning and consent

›Delayed presentation workup

›MRI to assess retraction and tissue quality

›Chronic ruptures may require reconstruction rather than primary repair

08Treatment/t94

Immediate ED management

›Immobilization

›Knee immobilizer in full extension

›Applied immediately on diagnosis

›Maintains apposition of torn tendon ends

›Long-leg posterior splint alternative

›Plaster or fiberglass from proximal thigh to ankle

›Knee at 0 degrees extension

›Weight-bearing restriction

›Non-weight-bearing (NWB) for complete tears

›Toe-touch weight-bearing (TDWB) may be considered for partial tears

›Crutch instruction provided before discharge

›Analgesia protocol

›First-line analgesics

›Acetaminophen 1000 mg orally every 6-8 hours

›Ibuprofen 600 mg orally every 8 hours with food

›NSAID caution with renal impairment

›Opioid analgesics for severe pain

›Oxycodone 5-10 mg orally every 4-6 hours as needed

›Hydromorphone 0.5-1 mg IV for immediate severe pain control

›Short course only for perioperative period

›Avoid intra-articular or peritendinous corticosteroid injection

›Worsens tendon collagen integrity

›Contraindicated in acute setting

›Supportive measures

›Ice application

›20 minutes on, 20 minutes off

›Reduces hemarthrosis and swelling

›Leg elevation

›Above heart level to reduce swelling

›Facilitates surgical wound healing

Surgical treatment

›Complete rupture surgical repair

›Indication

›All complete patellar tendon ruptures require surgical repair

›Non-operative management is not appropriate for complete tears

›Timing

›Ideally within days to 2-3 weeks of injury

›Outcomes decline significantly with delay beyond 6 weeks

›Chronic repairs may require reconstruction techniques

›Transosseous bone tunnel repair

›Traditional gold standard technique

›Krackow locking suture through tendon substance

›Sutures threaded through patellar bone tunnels

›Tied over superior pole of patella

›Suture anchor repair

›Anchors placed at inferior patellar pole

›Smaller incision with less dissection

›Rerupture rate 0% vs 7.5% vs transosseous technique in one cohort

›Augmentation techniques

›Cerclage wire augmentation

›Suture tape or internal brace augmentation

›Semitendinosus or gracilis allograft for mid-substance tears or chronic ruptures

›Augmented primary repair failure rate approximately 2%

›Partial tear operative indications

›High-grade partial tears with functional impairment

›Failure of conservative management at 6-8 weeks

›Surgeon and patient preference

Postoperative rehabilitation protocol

›Phase 1 (weeks 0-6)

›Weight-bearing progression

›Immediate protected weight-bearing in locked knee immobilizer

›Progress to full weight-bearing in immobilizer by week 4-6

›Range of motion progression

›Early passive ROM initiated weeks 1-2

›Safe-zone flexion only (avoid active extension)

›0-45 degrees week 1-3

›0-90 degrees by weeks 3-6

›Phase 2 (weeks 6-12)

›Active ROM and strengthening

›Full active ROM initiated after week 6

›Concentric quadriceps strengthening

›Proprioception and balance training

›Functional activities

›Stationary cycling

›Pool walking and aquatic therapy

›Phase 3 (months 3-12)

›Progressive return to activity

›Running program initiated approximately 9 months postoperatively

›Plyometric and sport-specific training

›Return to pre-injury sport level at 12-18 months

›Return-to-sport criteria

›Quadriceps strength symmetry >90% of contralateral limb

›Full ROM without pain

›Functional performance tests passed

Nonoperative management

›Criteria for nonoperative management

›Select partial tears with intact active extension

›Grade I or II partial tear on imaging

›No extensor lag

›Low-demand patients or surgical candidates

›Significant comorbidities prohibiting surgery

›Patient preference after risk-benefit discussion

›Nonoperative protocol

›Knee immobilizer in full extension for 6 weeks

›Progressive ROM as tolerated

›Physiotherapy referral

›Close monitoring for functional deterioration

09Special Populations/sp61

Pregnancy

›Patellar tendon rupture in pregnancy

›Incidence and risk

›Rare in pregnancy

›Relaxin-mediated ligamentous laxity may affect periarticular structures

›Falls from balance changes may precipitate injury

›Diagnostic considerations

›Plain radiograph with abdominal shielding if needed

›Ultrasound is preferred imaging (no radiation)

›MRI without gadolinium preferred over CT for soft tissue assessment

›Treatment considerations

›Surgical repair generally recommended for complete tears

›Anesthetic planning with obstetric team

›NSAIDs avoided in third trimester (premature ductus arteriosus closure)

›Opioid use brief and with neonatal monitoring planning

›Rehabilitation

›Physiotherapy adapted to pregnancy stage

›Postpartum rehabilitation continuation

Geriatric

›Patellar tendon rupture in older adults (>65 years)

›Epidemiology

›Less common than quadriceps tendon rupture in this age group

›Degenerative tendinopathy more prevalent

›Comorbidities (diabetes, CKD, CKD) increase risk

›Diagnostic considerations

›Higher prevalence of underlying systemic disease

›Comprehensive metabolic workup indicated

›Osteoporosis reduces bone anchor holding strength

›Treatment modifications

›Surgical repair still indicated for complete tears

›Higher complication rates with medical comorbidities

›Augmentation recommended for poor tissue quality

›Prolonged immobilization risk

›Medication considerations

›NSAIDs with caution (renal function, GI risk, cardiovascular risk)

›Opioid caution (falls risk, confusion, constipation)

›Acetaminophen preferred first-line

›Rehabilitation modifications

›Slower progression of ROM and strengthening

›Fall prevention strategies

›Physiotherapy with geriatric-appropriate exercise intensity

Pediatrics

›Patellar tendon rupture in children and adolescents

›Epidemiology

›Rare in skeletally immature patients

›Male adolescents involved in jumping sports at highest risk

›Osgood-Schlatter disease is a predisposing factor

›Anatomy considerations

›Patellar sleeve fracture more common than tendon midsubstance tear in young children

›Skeletally immature: cartilaginous avulsion may be radiographically occult

›Growth plate physeal injuries at tibial tuberosity must be excluded

›Diagnostic approach

›Plain radiograph to assess tibial tuberosity and patellar height

›MRI or ultrasound for soft tissue characterization

›Physeal injury patterns differ from adult presentations

›Treatment

›Surgical repair principles similar to adults

›Physeal-sparing techniques used when growth plates open

›Patellar sleeve fractures repaired with suture anchor or cerclage

›Early repair recommended to prevent growth disturbance

›Rehabilitation

›Return to sport typically faster in pediatric patients

›Sport-specific rehabilitation aligned with skeletal maturity

›Close monitoring for physeal growth disturbance

10Background/b103

Epidemiology

›Incidence and distribution

›General population incidence

›Approximately 0.68 per 100,000 person-years in general population

›Up to 6 per 100,000 in active military populations

›Demographics

›Male sex predominance: 91-98% of cases

›Peak age of injury: under 40 years (high-energy athletic mechanism)

›43% of cases occur in patients over 40 years

›Black race: rate ratio 9.21 times higher vs White in military data

›Mean BMI 28.7 kg/m2 in affected cohorts

›Relative frequency

›Accounts for approximately 5% of all extensor mechanism injuries

›Six times less common than patellar fracture

›Quadriceps tendon rupture is more common overall (especially age >40)

›Risk populations

›Athletes in jumping sports

›Basketball, volleyball, weightlifting, track and field

›Military personnel

›Higher incidence due to high-demand physical activity

›Systemic disease patients

›SLE, CKD, diabetes, RA, hyperparathyroidism

›Medication-exposed patients

›Corticosteroids (systemic and intra-articular)

›Fluoroquinolone antibiotics

Pathophysiology

›Tendon biology and failure mechanism

›Normal tendon structure

›Patellar tendon composed of type I collagen fibers

›Tensile strength dependent on collagen crosslinks and fibrillar organization

›Enthesis at inferior patellar pole is the most common rupture site

›Degenerative tendinopathy pathway

›Chronic repetitive microtrauma leads to collagen fiber disorganization

›Tendinosis (mucoid degeneration, fibrocartilaginous metaplasia) reduces tensile strength

›Rupture represents terminal event in cumulative tendinopathy

›75-98% of ruptured tendons show pre-existing degenerative changes histologically

›Acute eccentric overload mechanism

›Violent eccentric quadriceps contraction against flexed knee

›Tensile load exceeds remaining tendon capacity

›Sudden catastrophic failure at weakest point

›Anatomical vulnerability

›Inferior patellar pole enthesis

›Watershed zone of poor vascularity predisposes to degeneration

›Stress concentration at bone-tendon interface

›Mid-substance tears

›Less common than pole avulsions

›More common in younger high-energy trauma patients

›Tibial tuberosity avulsion

›Rare in adults; more common in skeletally immature patients

›Systemic disease mechanisms

›SLE and corticosteroid use

›Immune complex deposition in tendon vessels causing ischemia

›Corticosteroids impair collagen synthesis and promote proteolysis

›CKD and renal osteodystrophy

›Secondary hyperparathyroidism weakens bone-tendon interface

›Tendon calcifications and degeneration

›Fluoroquinolone tendon toxicity

›Inhibition of tenocyte proliferation and matrix metalloprotease upregulation

›Direct disruption of collagen fibril structure

Therapeutic Considerations

›Surgical vs nonoperative outcomes

›Complete tear management

›All complete patellar tendon ruptures require surgical repair

›Nonoperative management of complete tears leads to poor functional outcomes

›Quadriceps strength deficit, chronic extensor lag, and disability

›Repair timing and outcomes

›Acute repair (within 2-3 weeks): best functional outcomes

›Delayed repair (6-12 weeks): requires more extensive mobilization

›Chronic repair (>3 months): graft augmentation or reconstruction required

›Return-to-sport data

›75-94% of patients return to sport after surgical repair

›83% return to pre-injury athletic level

›Return-to-running approximately 9 months; pre-injury sport 12-18 months

›Surgical technique evidence

›Suture anchor vs transosseous technique

›Suture anchor: rerupture rate 0% vs 7.5% for transosseous in one large cohort

›Both techniques yield similar functional scores (IKDC, Lysholm, Tegner)

›Augmentation reduces failure rate to approximately 2%

›Augmentation rationale

›Protects repair during early healing

›Recommended for mid-substance tears, poor tissue quality, and chronic ruptures

›Complications

›Rerupture rate

›3-7.5% with transosseous technique

›Reduced with suture anchor repair

›Quadriceps atrophy

›Universal after repair; responds to rehabilitation

›Knee stiffness

›Risk reduced with early passive ROM protocol

›Patellofemoral symptoms

›Altered patellar tracking post-repair

›Infection

›Surgical site infection risk

›Higher with diabetes, immunosuppression

›Prognostic factors

›Favorable prognosis

›Acute repair within 2 weeks

›Age under 40

›No systemic disease

›BMI under 25

›Unfavorable prognosis

›Delayed repair

›Age over 40

›BMI over 25

›Systemic disease (SLE, CKD, diabetes)

›Prior corticosteroid exposure

11Patient Discharge Instructions/pdi54

copy discharge instructions

›Diagnosis and injury explanation

›You have been diagnosed with a patellar tendon rupture

›The patellar tendon connects your kneecap (patella) to your shin bone

›This tendon is part of the extensor mechanism that allows you to straighten your knee

›This is a surgical injury

›Surgery is required to repair a complete tear

›Timing of surgery is important — delay worsens outcomes

›Immobilization and activity restrictions

›Keep your knee immobilizer on at all times

›The knee must be kept straight in the immobilizer

›Do not remove it except for hygiene under medical guidance

›Weight-bearing restriction

›Do not put weight through your injured leg

›Use crutches for all movement

›Non-weight-bearing until instructed otherwise by your surgeon

›Elevation

›Keep your leg raised above the level of your heart

›Reduces swelling and pain

›Pain and swelling management

›Ice application

›Apply ice wrapped in a cloth for 20 minutes every 2 hours

›Do not apply ice directly to skin

›Pain medication

›Acetaminophen (Tylenol) 500-1000 mg every 6-8 hours as needed

›Ibuprofen (Advil, Motrin) 400-600 mg every 8 hours with food if no allergy

›Take prescribed pain medication as directed

›Follow-up instructions

›Orthopedic surgery appointment

›Your urgent orthopedic follow-up is critical

›Appointment within 3-7 days of this visit

›Bring imaging results from today

›Do not delay this appointment

›Surgical outcomes depend on early repair

›Each week of delay increases difficulty of surgery

›Return to emergency department immediately for

›Red flag symptoms requiring emergency return

›Severe increasing pain not controlled by medication

›Significant increase in swelling

›Numbness, tingling, or coldness in the foot or toes

›Skin color change (pale, blue, or mottled) of the leg or foot

›Inability to feel or move your toes

›Signs of complications

›Fever above 38.5 degrees Celsius

›Redness or warmth spreading around the knee

›Signs of compartment syndrome: severe pain worsened by passively moving the foot

›Expected recovery timeline

›Recovery milestones after surgery

›6 weeks: progressive movement and early strengthening begins

›3-6 months: functional daily activities resumed

›9 months: running program started

›12-18 months: return to pre-injury sport level expected

›Rehabilitation commitment

›Physiotherapy is essential to successful recovery

›Compliance with rehabilitation program determines functional outcome

12References/r33

Guidelines and key sources

›Core clinical references

›Matava MJ. Patellar Tendon Ruptures. Journal of the American Academy of Orthopaedic Surgeons. 1996. PMID 10797196

›Foundational clinical review of mechanism, diagnosis, and management

›Pengas IP, Assiotis A, Khan W, Spalding T. Adult Native Knee Extensor Mechanism Ruptures. Injury. 2016. PMID 27423309

›Demographics, outcomes, and return-to-sport data

›Fredericks DR, Slaven SE, McCarthy CF, et al. Incidence and Risk Factors of Acute Patellar Tendon Rupture in Active-Duty Military. American Journal of Sports Medicine. 2021. PMID 34313493

›Incidence data, risk factors including race and fluoroquinolones

›Surgical technique references

›Danaher M, Faucett SC, Endres NK, Geeslin AG. Repair of Quadriceps and Patellar Tendon Tears. Arthroscopy. 2023. PMID 36332853

›Contemporary surgical technique review and augmentation evidence

›O'Dowd JA, Lehoang DM, Butler RR, et al. Operative Treatment of Acute Patellar Tendon Ruptures. American Journal of Sports Medicine. 2020. PMID 32757970

›Suture anchor vs transosseous technique comparison and rerupture rates

›Di Stefano MT, Young M, Corvi M, et al. Management of Acute Midsubstance Patella Tendon Rupture. JBJS Reviews. 2025. PMID 41662180

›Current concepts for mid-substance tear management

›Imaging references

›Ng JP, Cawley DT, Beecher SM, et al. Focal Intratendinous Radiolucency. The Knee. 2016. PMID 26746043

›Sensitivity 82.5% and specificity 95.2% for new radiographic sign

›Yu JS, Petersilge C, Sartoris DJ, et al. MR Imaging of Injuries of the Extensor Mechanism of the Knee. Radiographics. 1994. PMID 8066269

›MRI characterization of extensor mechanism injuries

›Flores D, Atinga A, Beaulieu C, et al. Extensor Apparatus of the Knee: Anatomy and Injury Patterns. Skeletal Radiology. 2026. PMID 42059955

›Contemporary anatomical and imaging review

Associated injury and special population references

›Associated injuries and return to sport

›McKinney B, Cherney S, Penna J. Intra-Articular Knee Injuries in Patients With Knee Extensor Mechanism Ruptures. Knee Surgery Sports Traumatology Arthroscopy. 2008. PMID 18478204

›30% overall and 75% high-energy associated intra-articular injury rates

›Beranger JS, Kajetanek C, Bayoud W, et al. Return to Sport After Early Surgical Repair of Acute Patellar Tendon Ruptures. Orthopaedics and Traumatology Surgery Research. 2020. PMID 32179020

›Return-to-sport outcomes data

›Special populations

›Ali Yousef MA, Rosenfeld S. Acute Traumatic Rupture of the Patellar Tendon in Pediatric Population. Injury. 2017. PMID 28888715

›Pediatric patellar tendon rupture case series and management

›El Ouali Z, Nassar K, Bassa E, et al. Bilateral Patellar Tendon Rupture on Lupus Undergoing Corticosteroids. BMC Musculoskeletal Disorders. 2020. PMID 32693777

›SLE and corticosteroid bilateral rupture case report

›MacDonald J, Rodenberg R, Sweeney E. Acute Knee Injuries in Children and Adolescents. JAMA Pediatrics. 2021

›Pediatric knee injury review including extensor mechanism injuries

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Comprehensive Clinical Review

Structured, evidence-informed, long-form analysis for deeper understanding.

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed June 16, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.