Lumbar Spine Anatomy and Biomechanics

• A zygapophyseal joint is a synovial joint between the superior articular process of one vertebra and the inferior articular process of the vertebra directly above it.
• The lumbar spine has 10 facet joints.
• The lumbar spine carries 20-25% of the body's axial load.
• Spondylosis is caused by degeneration.
• Spondylolysis is a defect in the pars interarticularis, arch, or vertebrae.
• Spondylolisthesis is the forward displacement of vertebrae.
• Retrolisthesis is the backward displacement of vertebrae.
• The superior facet joints face medially and downwards.
• The inferior facet joints face laterally and upwards.
• The capsular pattern of the lumbar spine involves equally limited lateral flexion and rotation, and extension.
• The loosed packed position of the lumbar spine is midway between flexion and extension.
• The closed packed position of the lumbar spine is full extension.
• Lumbarisation occurs when S1 is mobile and results in a 6th lumbar vertebra.
• Sacralisation is the fusion of L5 to the sacrum, resulting in only 4 lumbar vertebrae.
• The iliolumbar ligament originates from L5 and inserts into the ilium.
• The iliolumbar ligament stabilises L5 with the ilium and prevents anterior displacement of L5.
• The annulus fibrosus has 3 layers.
• Over time, hydrophilic mucosal tissue in the nucleus pulposus is gradually replaced by fibrocartilage.
• Schmorl nodes are herniations of the nucleus pulposus (fluid) into the vertebra.
• Four types of disc injuries:
  • Protrusion: disc bulging posteriorly without rupture of the annulus fibrosus.
  • Prolapse/herniation: nucleus pulposus protrudes through the annulus posteriorly.
  • Extrusion: annulus fibrosus tears and nucleus pulposus protrudes into the spinal canal (epidural space).
  • Sequestrated disc: fragments of annulus fibrosus and nucleus pulposus outside of the disc.
• Disc injuries can lead to myelopathy, which is injury to the spinal cord due to severe compression.
• The L5-S1 region of the spine is the most common site of problems because this site bears more weight.
• Two subdivisions of lower back pain (LBP):
  • Back pain dominant.
  • Leg pain dominant.
• Two possible reasons for back pain dominant LBP:
  • Disc involvement.
  • Facet joint involvement.
• Two possible reasons for leg pain dominant LBP:
  • Nerve root involvement.
  • Neurogenic intermittent claudication (pressure on cauda equina).
• Disc problems usually occur in people aged 15-40 years.
• Ankylosing spondylosis usually occurs in people aged 18-45 years (more common in men).
• Spondylosis and osteoarthritis (OA) usually occur in people aged 45+ years.
• Lower back pain (LBP) occurs more in women.
• Radiating anterolateral pain in the leg suggests L4 nerve root problems.
• Radiating posterior pain in the leg suggests L5 nerve root problems.
• Intrathecal pressure is the pressure inside the covering of the spinal cord.
• Symptoms indicating a problem in the lumbar spine include pain during sneezing, coughing, deep breathing, and laughing.
• These actions increase the intrathecal pressure in the lumbar spine.
• Intradiscal pressure is the hydrostatic pressure in the nucleus pulposus of a non-degenerated disc.
• Sitting with sustained flexion increases the intradiscal pressure.
• Extension is painful when standing is painful and the movement of the spine would you expect is also painful.
• Extension is painful when walking is painful and walking accentuates the extension.
• Extension is painful when lying down is painful
• Maintaining one single position for an extended period of time increases discogenic pain/pain from IV disc.
• Postural muscles usually respond to a pathology by tightening.
• Dynamic muscles usually respond to a pathology by atrophying.
• Three body types:
  • Ectomorphic = thin, with a prominence of structures from the embryonic ectoderm.
  • Mesomorphic = muscular, with a prominence of structures from the embryonic mesoderm.
  • Endomorphic = heavy/fat, with a prominence of structures from the embryonic endoderm.
• Recurvatum is hyperextension.
• The greatest range of motion (ROM) in the lumbar spine comes from L4-L5 & L5-S1.
• Three stages of degeneration:
  • Functional.
  • Unstable.
  • Stable.
• During the functional and unstable stages of degeneration, there is increased intersegmental motion, rotation, and lateral flexion.
• During the stable stage of degeneration, there is decreased intersegmental motion, rotation, and lateral flexion.
• The dynamic extensor endurance test assesses the strength of the iliocostalis lumborum (part of erector spinae) and multifidus.
• The load on the lumbar spine is reduced by 30% with strong abdominals.
• The Trendelenburg sign test assesses weak hip abductors (gluteus medius & minimus).
• To perform the Trendelenburg sign test: the patient stands on one leg for 30 seconds, and you observe whether the pelvis remains level.
• A positive Trendelenburg sign is a drop of the pelvis on the contralateral (unsupported) side.
• The myotome for L1-L2 is hip flexion.
• The myotome for L3 is knee extension.
• The myotome for L4 is ankle dorsiflexion.
• The myotome for L5 is big toe extension.
• The myotome for S1 is plantarflexion and eversion.
• The myotome for S2 is hip extension & knee flexion.
• The myotome for S3 is knee flexion.
• A positive Babinski test on both sides indicates an upper motor neuron (UMN) lesion.
• A positive Babinski test on one side indicates a lower motor neuron (LMN) lesion.
• The prone knee bend test stresses the femoral nerve & L2-L4 nerve root.
• Tension is applied to the sciatic roots at 35-70° of hip flexion during the straight leg raise (SLR).
• If pain doesn't occur during the SLR until hip flexion of +70° is reached, the pain is probably joint pain.
• The Oswestry Disability Index assesses functional disability in patients with LBP (ADLs).
• The Schober test measures the degree of flexion in the lumbar spine.
• The bicycle test of van Gelderen is a test for intermittent claudication.
• The L3-L4 nerve root is assessed by the patellar tap reflex test.
• The L5-S1 nerve root is assessed by the medial hamstring reflex test.
• The S1-S2 nerve root is assessed by the lateral hamstring reflex test.
• The L4-L5 nerve root is assessed by the posterior tibial reflex test.
• The S1-S2 nerve root is assessed by the Achilles reflex test.
• The loose packed position of the sacrum is nutation, which is backward rotation of the sacrum (base of sacrum moves forward).
• The closed packed position of the sacrum is counternutation.
• Three structures that limit nutation of the sacrum:
  • Anterior sacroiliac ligaments.
  • Sacrospinous ligament.
  • Sacrotuberous ligament.
• During trunk flexion, the sacrum moves:
  • First 45° = nutation (sacrum moves forward).
  • Near 60° = sacrum begins counternutation (backwards).
• During trunk extension, the sacrum moves with the pelvic girdle as it rotates posteriorly on the femoral heads.
• The loose packed position of the hip:
  • 30 degrees flexion.
  • 30 degrees abduction.
  • Slight external rotation.
• The closed packed position of the hip:
  • Full extension.
  • Internal rotation.
  • Abduction.
• Capsular pattern of the hip:
  • Flexion.
  • Abduction.
  • Internal rotation.
• Clicking of the hip is associated with labral tears.
• Internal snapping of the hip is caused by:
  • The iliofemoral ligament or iliopsoas tendon over the femoral head.
  • Occurs at 45° flexion.
• External snapping of the hip is caused by a tight iliotibial band or gluteus maximus over the greater trochanter.
• Intra-articular snapping of the hip is caused by acetabular labral tears or loose bodies (due to trauma or degeneration).
• Hip flexion range of motion is 110-120°.
• Hip extension range of motion is 10-15°.
• Hip abduction range of motion is 30-50°.
• Hip adduction range of motion is 30° (never pure adduction).
• Hip external rotation range of motion is 40-60°.
• Hip internal rotation range of motion is 30-40°.
• Diagnosis rule for hip osteoarthritis (OA): 4/5 must be positive for there to be a high probability of hip OA:
  • Limited active hip flexion accompanied by lateral hip pain.
  • Active hip extension causes pain.
  • Limited passive hip internal rotation (25° or less).
  • Squatting = limited & painful.
  • Scour test with abduction causes lateral/groin pain.
• Some functional tests for the hip:
  • Squatting.
  • Stairs.
  • Running.
  • Jumping.
• 120° of hip flexion is needed to tie shoelaces.
• 112° of hip flexion is needed to sit.
• 125° of hip flexion is needed to bend down/stoop.
• Hip movement needed to squat:
  • 115° flexion.
  • 20° abduction.
  • 20° internal rotation.
• 67° of hip flexion is needed to go up stairs.
• 36° of hip flexion is needed to go down stairs.
• The hip scour test is used to assess for hip OA or labral tears.
• To perform the hip scour test:
  • Patient is supine.
  • Hip and knee are at 90°.
  • Then adduct as you internally rotate, applying pressure down through femur.
  • Abduct and externally rotate, applying pressure down through femur.
• Patrick's test/FABER (flexion, abduction, external rotation) assists in diagnosing pathologies in the hip, lumbar spine, and sacroiliac (SI) joint.
• To perform the FABER test:
  • Patient is supine.
  • Lateral ankle of leg being tested is placed proximal to opposite knee.
  • Fixate opposite ASIS.
  • Push down on knee of leg being tested.
• If the FABER test produces SIJ pain, the hypothesis is:
  • SIJ dysfunction.
  • Sacroilitis.
• If the FABER test produces groin pain, the hypothesis is:
  • Iliopsoas strain/bursitis.
  • Intra-articular hip disorder: femoral acetabular/hip impingement, labral tear, loose bodies, chondral lesion (due to damage of articular cartilage), or OA.
• If the FABER test produces posterior hip pain, the hypothesis is posterior hip impingement.
• The FADDIR (flexion, adduction, internal rotation) test is for:
  • Femoral impingement syndrome.
  • Anterior labral tear.
• To perform the FADDIR test: hip and knee in 90 degrees flexion, then internally rotate and adduct the hip.
• A positive FADDIR test is reproduction of patient's symptoms.
• The posterior labral tear test tests for:
  • Posterior & inferior hip impingement.
  • Posterior labral tear.
  • Anterior hip instability.
• To perform the posterior labral tear test:
  • Patient in supine.
  • Perform passive extension, abduction, external rotation from the position of full hip flexion, internal rotation, and abduction.
• A positive posterior labral tear test is pain reproduction with or without an audible click.
• The 90 SLR test is for testing hamstring tightness.
• To perform the 90 SLR test:
  • Patient in supine with both hips flexed to 90° while the knees are bent.
  • Then the patient extends the knee as much as possible.
• A positive 90 SLR test:
  • Knee extension should be within 20° of full extension.
  • Anything more is positive.
• The Ober's test is for tightness in the iliotibial (IT) band.
• The Thomas test is for hip flexor (iliopsoas) tightness.
• The medial meniscus is C-shaped.
• The lateral meniscus is O-shaped.
• The loose packed position of the knee is 25° flexion.
• The closed packed position of the knee is full extension.
• The capsular pattern of the knee is flexion and extension.
• The superior tibiofibular joint is a plane joint.
• The unhappy triad is damage to the ACL, medial collateral ligament (MCL), and medial meniscus.
• A valgus knee injury often produces the unhappy triad.
• Hyperextension of the knee often produces ACL with meniscus tears.
• Flexion with posterior translation often produces PCL injuries.
• A varus mechanism often produces PCL, LCL, lateral capsule knee injuries.
• The growth plate of the knee is often injured in young children.
• Injury to the tibial tubercle results in Osgood-Schlatter disease.
• A "popping" sound at the time of the knee injury indicates an ACL tear or osteochondral fracture (behind patella on lateral femoral condyle).
• A "popping" on the lateral side of the knee at the time of injury may be due to the popliteus tendon snapping over the lateral femoral inferior posterior tubercle.
• Aching pain in the knee indicates degeneration.
• Sharp, catching pain in the knee indicates a mechanical problem.
• Anterior pain in the knee indicates:
  • Patellofemoral problems.
  • Bursa pathology.
  • Fat pad pathology.
  • Tendinosis.
  • Osgood-Schlatter's disease.
• Pain in the knee after activity indicates overuse, which leads to inflammation:
  • Synovial plica (membrane between patella & tibiofemoral joint) irritation.
  • Early tendinosis.
  • Paratendinosis, leading to jumper's knee or Sinding-Larsen-Johansson syndrome (pain at bottom of patella in teens w/ growth spurts).
• Pain in the knee during ankle movements indicates a problem with the superior tibiofibular joint.
• Generalised pain in the knee usually indicates tears of muscles or ligaments.
• Locking of the knee means the knee cannot fully extend and indicates meniscal pathology.
• Swelling of the knee after a twisting injury indicates meniscus injury.
• If the knee doesn't swell, there is often no swelling after serious knee injuries because some of the structures are avascular.
• Localised swelling of the knee indicates inflammation of the bursa.
• There is a higher probability of injury if the knee is in a closed chain.
• The menisci of the knee are often injured by acceleration or twisting.
• The cruciate ligaments of the knee are often injured by deceleration.
• A normal knee has 6° of valgus.
• The knees are considered varus when 2 or more fingers (4cm) can fit between the knees when the ankles are together.
• Six components of Miserable malalignment syndrome:
  • Anterior pelvic tilt.
  • Increased hip anteversion.
  • Decreased tibiofemoral angle.
  • Genu recurvatum = knee hyperextension.
  • Navicular drop.
  • Increased foot pronation.
• If a patient has excessive lordosis, the knees are often hyperextended to maintain the centre of gravity, which can lead to posterior knee pain.
• Hyperextension of the knee makes you prone to PCL tears because the posterior oblique ligaments are being stretched.
• The problem is usually meniscus pathology is limiting extension if only one knee hyperextends.
• Patella alta is when the patella is located higher and can increase the patellofemoral contact force during flexion and can give anterior knee pain.
• Patella baja/infera is when the patella is lower than normal.
• A Baker's cyst is a herniation of synovial tissue through the posterior capsule of the knee.
• Knee flexion has 125° of motion.
• Knee extension has O to -15° of motion, especially in women.
• Most of the force for the last 15° of knee extension comes from the quadriceps.
• When testing hamstring strength, and the heel is turned out, the biceps femoris is being targeted.
• When testing hamstring strength, and the heel is turned in, the semitendinosus & semimembranosus are being targeted.
• If only the ACL is torn, the anterior drawer test will be negative because the posterior medial & lateral structures & posterior capsule limits movement.
• The posterior drawer test is used for detecting PCL injury.
• The Lachman's test is used to diagnose ACL injury.
• The gravity sag test is used for diagnosing PCL injury.
• To perform the gravity sag test: patient is supine, hip flexed 90°, knee flexed 45°, and observe if the tibia drops back, indicating a PCL tear.
• Three menisci tests:
  • McMurray.
  • Thessaly.
  • Apley.
• How to perform the McMurray test:
  • Testing lateral meniscus
    • Patient supine
    • Knee fully flexed
    • Rotate foot medially
    • Bring knee into full extension
  • Testing medial meniscus
    • Patient supine
    • Knee fully flexed
    • Rotate food laterally
    • Bring knee into full extension
• A positive McMurray test: clicking, locking or knee pain
• To perform Thessaly test:

• Patient stands on injured leg
• With slightly bent knee, rotate left to right

• A positive Thessaly test: pain at joint line during rotations
• To perform the Apley test:

• Patient prone
• Fixate upper thigh with knee bent 90 degrees
• Distract knee
• Perform lateral & medial rotation
• Repeat but with compression

• A positive Apley test
  • If distraction + rotation is painful and ROM is increased = ligamentous injury
  • If compression + rotation is painful and ROM is decreased = meniscus injury
• Fairbank apprehension test is a dislocation test for the patella
• The Q angle is the between the rectus femoris and patellar tendon
  • Draw a line from ASIS to mid point of patella
  • Draw a line from mid patella to the tibial tubercle
• Average Q angle
  • Men: 13 degrees
  • Women: 18 degrees
• The Q angle should be 0 in sitting position
• The bayonet sign is the abnormal alignment of quadriceps musculature, patella tendon & tibial shaft
• A Q angle of <13 is patella alta
• A Q angle of >18 is
  • Subluxating patella
  • Valgus
  • Lateral displacement of tibial tubercle or increased tibial torsion
• The three joints of the hindfoot
  • Tibiofibular
  • Talocrural
  • Subtalar (Talus & Calcaneus)
• The loose packed position of the tibiofibular joint is plantarflexion
• The close packed position of the tibiofibular joint is max dorsiflexion
• The loose packed position of the talocrural joint is 10 degrees plantarflexion and midway between inversion and eversion
• The close packed position of the talocrural joint is maximum dorsiflexion
• The capsular pattern of the talocrural joint: plantarflexion, then dorsiflexion
• The type of synovial joint of the talocrural joint: uniaxial hinge joint
• The close packed position of the subtalar joint: full supination
• The type of synovial joint of the subtalar joint: plane joint
• How many degrees of freedom do the talocrural and subtalar joints have? 3 degrees of freedom
  • Plantar/dorsiflexion
  • Inversion/eversion
  • Supination/pronation
• The type of synovial joint of the talocalcaneonavicular joint: ball & socket joint
• The close packed position of the talocalcaneonavicular joint: full supination
• The type of synovial joint of the calcaneocuboid joint: saddle joint
• The six joints of the midfoot
  • Talocalcaneonavicular
  • Cuneonavicular
  • Cuboideonavicular
  • Intercuneiform Joints
  • Cuneocuboid
  • Calcaneocuboid
• The four joints of the forefoot
  • Tarsometatarsal
  • Intermetatarsal
  • Metatarsophalangeal
  • Interphalangeal
• The line of chopart: talus & calcaneus proximally cuboid & navicular distally
• The line of lisfranc: along the line of tarsometatarsal
• How many degrees of freedom do the metatarsophalangeal joints have?

• 2 degrees

• How many degrees of freedom do the interphalangeal joints have?

• 1 degree

• Most ankle sprains happen in plantar flexion, inversion, adduction
• The which ankle ligament is most frequently injured with inversion traumas: ATFL (anterior talofibular ligament)
• A combination of movements make up supination:
  • Inversion & external rotation of calcaneus
  • Adduction of forefoot
  • Internal rotation of tarsometatarsal joint
• A combination of movements make up pronation:
  • Eversion & internal rotation of calcaneus
  • Abduction of forefoot
  • External rotation of tarsometatarsal joint
• How to perform the navicular drop test?
  • Measure distance from navicular bone to floor while standing
  • Measure distance from navicular bone to floor in relaxed position
  • Difference = navicular drop
• What does the navicular drop test indicate? The amount of foot pronation or flattening of the medial longitudinal arch during stance
• In open chain exercises of the foot, the talus considered fixed
• In closed chain exercises of the foot, the talus considered moving to help leg and foot adapt
• the stance phase is 60-65% of the gait cycle
• the swing phase is 35-40% of the gait cycle
• Stages in the stance phase of the gait cycle
  • Initial contact = heel strike
  • Load response = foot flat
  • Midstance = SL stance
  • Terminal swing = heel off
  • Pre-swing = toe off
• what % of the stance phase is the initial contact = 10%
• what % of the stance phase is the load response & midstance = 40%
• what % of the stance phase is in the terminal swing & pre-swing = 10%
• is there double leg support in the stance phase = initial contact (heel strike)
• what is essential in the load response and midstance stages of stance phase = lateral hip stability (glute medius & minimus)
• what are the stages in the swing phase of the gait cycle
  • initial swing
  • mid-swing
  • terminal swing
• what joint movements need to happen in the initial swing stage is knee flexion & ankle dorsiflexion
• what mucles are required to decelerate the leg & prepare for initial contact quadriceps & hamstrings