Physical examination maneuver

Physical Exam

Patellar Deep Tendon Reflex

also known as Knee jerk
🎬
Video coming soon

How to Perform

With the knee flexed and the lower leg relaxed and hanging freely, strike the patellar tendon just below the patella with the reflex hammer. Compare both sides.

How to Interpret

Showing 5 of 12 findings

Lumbosacral Radiculopathy

Side-to-side asymmetry of the patellar reflex
Rule in
Very helpfulWide CI
Rule out
Not helpful
Evidence:Moderate
Hyporeflexia (≤1+) at patella
Rule in
Somewhat helpful
Rule out
InconclusiveWide CI
Evidence:Moderate

Peripheral Neuropathy

Hyporeflexia (≤1+) at patella
Rule in
Very helpfulDerived CI
Rule out
Somewhat helpfulDerived CI
Evidence:ModerateResearch in progress
Multi-level hyporeflexia pattern (all deep tendon reflexes impaired)
Rule in
Very helpfulDerived CI
Rule out
Minimally helpfulDerived CI
Evidence:Moderate
Lower-extremity hyporeflexia pattern (Achilles + patellar both impaired)
Rule in
Somewhat helpfulDerived CI
Rule out
Somewhat helpfulDerived CI
Evidence:Moderate

Related Bedside Tests

🎬Video coming soon
Achilles Deep Tendon Reflex
aka Ankle jerk
Rule in:VHPeripheral Neuropathy, SHHypothyroidism, NHLumbosacral Radiculopathy +5 more
Rule out:VHPeripheral Neuropathy, MHHypothyroidism, NHLumbosacral Radiculopathy +5 more
🎬Video coming soon
Gait Assessment
Rule in:VHStroke, HFalls, HVascular Parkinsonism +24 more
Rule out:SHDementia, SHVascular Parkinsonism, MHFalls +24 more
Biceps Deep Tendon ReflexMembers
Sign in
Biceps Deep Tendon Reflex
aka Biceps jerk
Rule in:VHPeripheral Neuropathy, SHCervical Radiculopathy, IECervical Myelopathy +2 more
Rule out:MHPeripheral Neuropathy, NHCervical Radiculopathy, IECervical Myelopathy +2 more
🎬Video coming soon
Babinski Reflex
aka Plantar reflex
Rule in:VHUpper Motor Neuron Lesion, VHVascular Parkinsonism, HMultiple System Atrophy +4 more
Rule out:SHUpper Motor Neuron Lesion, MHMultiple System Atrophy, NHVascular Parkinsonism +4 more
Head and Face InspectionMembers
Sign in
Head and Face Inspection
Rule in:HAcromegaly, HStroke, SHCushing Syndrome +5 more
Rule out:SHAcromegaly, SHCushing Syndrome, SHStroke +5 more
Heart RateMembers
Sign in
Heart Rate
Rule in:SHAtrial Fibrillation, SHDecompensation, SHHypothyroidism +15 more
Rule out:HDecompensation, SHAtrial Fibrillation, SHPostoperative Complication +15 more

Related Systems / Regions

KneeLower ExtremitiesNeurological

Related Diagnoses

Cerebellar DiseaseFemoral NeuropathyGuillain-Barré SyndromeHypothyroidismLumbosacral RadiculopathyPeripheral NeuropathySpinal Cord LesionUpper Motor Neuron Lesion

Related Chief Complaints

Arm WeaknessAscending WeaknessBack PainBalance ProblemsBladder ProblemsBurning FeetClumsinessCold IntoleranceConstipationDepressionDifficulty Climbing StairsDifficulty WalkingDouble VisionDry SkinFacial SwellingFacial WeaknessFatigueFoot NumbnessFoot PainHair LossHand ClumsinessHeavy PeriodsHoarse VoiceKnee BucklingLeg NumbnessLeg PainLeg WeaknessLoss of SensationMemory ProblemsMuscle AchesNumbnessPins and NeedlesProgressive Leg WeaknessPuffy FaceSciaticaShooting Leg PainShortness of BreathSlow Heart RateSpasticityStiffnessThigh NumbnessThigh PainTinglingTingling in the LegWeaknessWeakness After InfectionWeight Gain

References

Research in progress on one or more findings above; ratings may change.

  • Iversen T, et al. BMC Musculoskelet Disord. 2013;14:206. PMID: 23837886.
  • Suri P, Rainville J, Katz JN, Jouve C, Hartigan C, Limke J, Pena E, Li L, Swaim B, Hunter DJ. The accuracy of the physical examination for the diagnosis of midlumbar and low lumbar nerve root impingement. Spine (Phila Pa 1976). 2011;36(1):63-73. doi:10.1097/BRS.0b013e3181c953cc. PMID: 20543768. PMCID: PMC2978791.
  • Abraham A, Alabdali M, Alsulaiman A, Albulaihe H, Breiner A, Katzberg HD, Aljaafari D, Lovblom LE, Bril V. The sensitivity and specificity of the neurological examination in polyneuropathy patients with clinical and electrophysiological correlations. PLoS One. 2017;12(3):e0171597. doi:10.1371/journal.pone.0171597. PMID: 28249029. PMCID: PMC5332032.
  • Li ZF, Niu XL, Nie LL, Chen LP, Cao CF, Guo L. Diagnostic value of clinical deep tendon reflexes in diabetic peripheral neuropathy. Arch Med Sci. 2023;19(5):1201-1206. doi:10.5114/aoms.2020.100656. PMID 37732044. PMC10507750.
  • Teitelbaum JS, Eliasziw M, Garner M. Tests of motor function in patients suspected of having mild unilateral cerebral lesions. Can J Neurol Sci. 2002;29(4):337-344. doi:10.1017/S0317167100002201. PMID: 12463489.
  • Teasdall RD, van den Ende H. The crossed adductor reflex in humans: an EMG study. Can J Neurol Sci. 1981;8(1):81-85. PMID: 6261907.
  • Jiang Z, Davies B, Zipser C, Margetis K, Martin A, Matsoukas S, et al. The value of clinical signs in the diagnosis of degenerative cervical myelopathy: a systematic review and meta-analysis. Global Spine J. 2024;14(4):1369-1394. doi:10.1177/21925682231209869. PMID: 37903098. PMCID: PMC11289551.
  • Pickett JB, Tatum EJ. Pendular knee reflexes: a reliable sign of hypotonia? Lancet. 1984;2(8396):236-237. PMID: 6146801.
  • Erb WH. Über Sehnenreflexe bei Gesunden und bei Rückenmarkskranken. Arch Psychiatr Nervenkr. 1875;5:792-802.

Research last updated September 9, 2026.