Physical examination maneuver

Physical Exam

Patellar Deep Tendon Reflex

also known as Knee jerk
🎬
Video coming September 2026

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 3 of 12 findings

Lumbosacral Radiculopathy

Hyporeflexia (≤1+) at patella
Rule in
Somewhat helpfulDerived CI
Rule out
InconclusiveWide CI
Evidence:Limited

Peripheral Neuropathy

Multi-level hyporeflexia pattern (all deep tendon reflexes impaired)
Rule in
Very helpfulDerived CI
Rule out
Minimally helpfulDerived CI
Evidence:Limited
Lower-extremity hyporeflexia pattern (Achilles + patellar both impaired)
Rule in
Somewhat helpfulDerived CI
Rule out
Somewhat helpfulDerived CI
Evidence:Limited

References

  • Iversen T, et al. BMC Musculoskelet Disord. 2013;14:206. PMID: 23837886.
  • van der Windt DAWM, Simons E, Riphagen II, Ammendolia C, Verhagen AP, Laslett M, Devillé W, Deyo RA, Bouter LM, de Vet HCW, Aertgeerts B. Physical examination for lumbar radiculopathy due to disc herniation in patients with low-back pain. Cochrane Database Syst Rev. 2010;(2):CD007431. doi:10.1002/14651858.CD007431.pub2. PMID: 20166095.
  • 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(8397):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.

Related Systems / Regions

Lower ExtremitiesNeurological

Related Bedside Tests

🎬Video coming Sept 2026
Achilles Deep Tendon Reflex
aka Ankle jerk
Rule in:VHPeripheral Neuropathy, SHHypothyroidism, NHLumbosacral Radiculopathy +5 more
Rule out:VHPeripheral Neuropathy, ICHypothyroidism, NHLumbosacral Radiculopathy +5 more
🎬Video coming Sept 2026
Gait Assessment
Rule in:VHStroke, HFalls, HVascular Parkinsonism +24 more
Rule out:SHDementia, SHVascular Parkinsonism, MHFalls +24 more
🎬Video coming Sept 2026
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 Sept 2026
Babinski Reflex
aka Plantar reflex
Rule in:VHUpper Motor Neuron Lesion, VHVascular Parkinsonism, IEMotor Neuron Disease +4 more
Rule out:SHUpper Motor Neuron Lesion, NHVascular Parkinsonism, IEMotor Neuron Disease +4 more
🎬Video coming Sept 2026
Head and Face Inspection
Rule in:HAcromegaly, HStroke, NHHypothyroidism +5 more
Rule out:SHAcromegaly, SHHypothyroidism, SHStroke +5 more
🎬Video coming Sept 2026
Heart Rate
Rule in:HAtrial Fibrillation, SHDecompensation, SHHypothyroidism +15 more
Rule out:VHAtrial Fibrillation, HDecompensation, SHPostoperative Complication +15 more